Copyright © 1995-2019 The FreeBSD Documentation Project
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THIS DOCUMENTATION IS PROVIDED BY THE FREEBSD DOCUMENTATION PROJECT "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FREEBSD DOCUMENTATION PROJECT BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS DOCUMENTATION, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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Welcome to FreeBSD! This handbook covers the installation and day to day use of FreeBSD 12.0-RELEASE and FreeBSD 11.3-RELEASE. This book is the result of ongoing work by many individuals. Some sections might be outdated. Those interested in helping to update and expand this document should send email to the FreeBSD documentation project mailing list.
The latest version of this book is available from the
FreeBSD web
site. Previous versions can be obtained from https://docs.FreeBSD.org/doc/
.
The book can be downloaded in a variety of formats and
compression options from the FreeBSD
FTP server or one of the numerous
mirror sites. Printed
copies can be purchased at the
FreeBSD
Mall. Searches can be performed on the handbook and
other documents on the
search
page.
root
Passwordpfctl
Optionsrmuser
Interactive Account
Removalchpass
as
Superuserchpass
as Regular
Userscfb
Video Driver in a
FileX
and LaterX
and Earlierboot0
Screenshotboot2
Screenshot/etc/ttys
dump
over
sshdump
over
ssh with RSH
Settar
tar
ls
and cpio
to Make a Recursive Backup of the Current Directorypax
/etc/ntp.conf
The FreeBSD newcomer will find that the first section of this book guides the user through the FreeBSD installation process and gently introduces the concepts and conventions that underpin UNIX®. Working through this section requires little more than the desire to explore, and the ability to take on board new concepts as they are introduced.
Once you have traveled this far, the second, far larger, section of the Handbook is a comprehensive reference to all manner of topics of interest to FreeBSD system administrators. Some of these chapters may recommend that you do some prior reading, and this is noted in the synopsis at the beginning of each chapter.
For a list of additional sources of information, please see Appendix B, Bibliography.
The current online version of the Handbook represents the cumulative effort of many hundreds of contributors over the past 10 years. The following are some of the significant changes since the two volume third edition was published in 2004:
Chapter 24, DTrace has been added with information about the powerful DTrace performance analysis tool.
Chapter 20, Other File Systems has been added with information about non-native file systems in FreeBSD, such as ZFS from Sun™.
Chapter 16, Security Event Auditing has been added to cover the new auditing capabilities in FreeBSD and explain its use.
Chapter 21, Virtualization has been added with information about installing FreeBSD on virtualization software.
Chapter 2, Installing FreeBSD has been added to cover installation of FreeBSD using the new installation utility, bsdinstall.
The third edition was the culmination of over two years of work by the dedicated members of the FreeBSD Documentation Project. The printed edition grew to such a size that it was necessary to publish as two separate volumes. The following are the major changes in this new edition:
Chapter 11, Configuration and Tuning has been expanded with new
information about the ACPI power and resource management, the
cron
system utility, and more kernel tuning
options.
Chapter 13, Security has been expanded with new information about virtual private networks (VPNs), file system access control lists (ACLs), and security advisories.
Chapter 15, Mandatory Access Control is a new chapter with this edition. It explains what MAC is and how this mechanism can be used to secure a FreeBSD system.
Chapter 17, Storage has been expanded with new information about USB storage devices, file system snapshots, file system quotas, file and network backed filesystems, and encrypted disk partitions.
A troubleshooting section has been added to Chapter 27, PPP.
Chapter 28, Electronic Mail has been expanded with new information about using alternative transport agents, SMTP authentication, UUCP, fetchmail, procmail, and other advanced topics.
Chapter 29, Network Servers is all new with this edition. This chapter includes information about setting up the Apache HTTP Server, ftpd, and setting up a server for Microsoft® Windows® clients with Samba. Some sections from Chapter 31, Advanced Networking were moved here to improve the presentation.
Chapter 31, Advanced Networking has been expanded with new information about using Bluetooth® devices with FreeBSD, setting up wireless networks, and Asynchronous Transfer Mode (ATM) networking.
A glossary has been added to provide a central location for the definitions of technical terms used throughout the book.
A number of aesthetic improvements have been made to the tables and figures throughout the book.
The second edition was the culmination of over two years of work by the dedicated members of the FreeBSD Documentation Project. The following were the major changes in this edition:
A complete Index has been added.
All ASCII figures have been replaced by graphical diagrams.
A standard synopsis has been added to each chapter to give a quick summary of what information the chapter contains, and what the reader is expected to know.
The content has been logically reorganized into three parts: “Getting Started”, “System Administration”, and “Appendices”.
Chapter 3, FreeBSD Basics has been expanded to contain additional information about processes, daemons, and signals.
Chapter 4, Installing Applications: Packages and Ports has been expanded to contain additional information about binary package management.
Chapter 5, The X Window System has been completely rewritten with an emphasis on using modern desktop technologies such as KDE and GNOME on XFree86™ 4.X.
Chapter 12, The FreeBSD Booting Process has been expanded.
Chapter 17, Storage has been written from what used to be two separate chapters on “Disks” and “Backups”. We feel that the topics are easier to comprehend when presented as a single chapter. A section on RAID (both hardware and software) has also been added.
Chapter 26, Serial Communications has been completely reorganized and updated for FreeBSD 4.X/5.X.
Chapter 27, PPP has been substantially updated.
Many new sections have been added to Chapter 31, Advanced Networking.
Chapter 28, Electronic Mail has been expanded to include more information about configuring sendmail.
Chapter 10, Linux® Binary Compatibility has been expanded to include information about installing Oracle® and SAP® R/3®.
The following new topics are covered in this second edition:
This book is split into five logically distinct sections. The first section, Getting Started, covers the installation and basic usage of FreeBSD. It is expected that the reader will follow these chapters in sequence, possibly skipping chapters covering familiar topics. The second section, Common Tasks, covers some frequently used features of FreeBSD. This section, and all subsequent sections, can be read out of order. Each chapter begins with a succinct synopsis that describes what the chapter covers and what the reader is expected to already know. This is meant to allow the casual reader to skip around to find chapters of interest. The third section, System Administration, covers administration topics. The fourth section, Network Communication, covers networking and server topics. The fifth section contains appendices of reference information.
Introduces FreeBSD to a new user. It describes the history of the FreeBSD Project, its goals and development model.
Walks a user through the entire installation process of
FreeBSD 9.x
and later using
bsdinstall.
Covers the basic commands and functionality of the FreeBSD operating system. If you are familiar with Linux® or another flavor of UNIX® then you can probably skip this chapter.
Covers the installation of third-party software with both FreeBSD's innovative “Ports Collection” and standard binary packages.
Describes the X Window System in general and using X11 on FreeBSD in particular. Also describes common desktop environments such as KDE and GNOME.
Lists some common desktop applications, such as web browsers and productivity suites, and describes how to install them on FreeBSD.
Shows how to set up sound and video playback support for your system. Also describes some sample audio and video applications.
Explains why you might need to configure a new kernel and provides detailed instructions for configuring, building, and installing a custom kernel.
Describes managing printers on FreeBSD, including information about banner pages, printer accounting, and initial setup.
Describes the Linux® compatibility features of FreeBSD. Also provides detailed installation instructions for many popular Linux® applications such as Oracle® and Mathematica®.
Describes the parameters available for system administrators to tune a FreeBSD system for optimum performance. Also describes the various configuration files used in FreeBSD and where to find them.
Describes the FreeBSD boot process and explains how to control this process with configuration options.
Describes many different tools available to help keep your FreeBSD system secure, including Kerberos, IPsec and OpenSSH.
Describes the jails framework, and the improvements of jails over the traditional chroot support of FreeBSD.
Explains what Mandatory Access Control (MAC) is and how this mechanism can be used to secure a FreeBSD system.
Describes what FreeBSD Event Auditing is, how it can be installed, configured, and how audit trails can be inspected or monitored.
Describes how to manage storage media and filesystems with FreeBSD. This includes physical disks, RAID arrays, optical and tape media, memory-backed disks, and network filesystems.
Describes what the GEOM framework in FreeBSD is and how to configure various supported RAID levels.
Examines support of non-native file systems in FreeBSD, like the Z File System from Sun™.
Describes what virtualization systems offer, and how they can be used with FreeBSD.
Describes how to use FreeBSD in languages other than English. Covers both system and application level localization.
Explains the differences between FreeBSD-STABLE, FreeBSD-CURRENT, and FreeBSD releases. Describes which users would benefit from tracking a development system and outlines that process. Covers the methods users may take to update their system to the latest security release.
Describes how to configure and use the DTrace tool from Sun™ in FreeBSD. Dynamic tracing can help locate performance issues, by performing real time system analysis.
Explains how to connect terminals and modems to your FreeBSD system for both dial in and dial out connections.
Describes how to use PPP to connect to remote systems with FreeBSD.
Explains the different components of an email server and dives into simple configuration topics for the most popular mail server software: sendmail.
Provides detailed instructions and example configuration files to set up your FreeBSD machine as a network filesystem server, domain name server, network information system server, or time synchronization server.
Explains the philosophy behind software-based firewalls and provides detailed information about the configuration of the different firewalls available for FreeBSD.
Describes many networking topics, including sharing an Internet connection with other computers on your LAN, advanced routing topics, wireless networking, Bluetooth®, ATM, IPv6, and much more.
Lists different sources for obtaining FreeBSD media on CDROM or DVD as well as different sites on the Internet that allow you to download and install FreeBSD.
This book touches on many different subjects that may leave you hungry for a more detailed explanation. The bibliography lists many excellent books that are referenced in the text.
Describes the many forums available for FreeBSD users to post questions and engage in technical conversations about FreeBSD.
Lists the PGP fingerprints of several FreeBSD Developers.
To provide a consistent and easy to read text, several conventions are followed throughout the book.
An italic font is used for filenames, URLs, emphasized text, and the first usage of technical terms.
Monospace
A monospaced
font is used for error
messages, commands, environment variables, names of ports,
hostnames, user names, group names, device names, variables,
and code fragments.
A bold font is used for applications, commands, and keys.
Keys are shown in bold to stand out from
other text. Key combinations that are meant to be typed
simultaneously are shown with `+
' between
the keys, such as:
Ctrl+Alt+Del
Meaning the user should type the Ctrl, Alt, and Del keys at the same time.
Keys that are meant to be typed in sequence will be separated with commas, for example:
Ctrl+X, Ctrl+S
Would mean that the user is expected to type the Ctrl and X keys simultaneously and then to type the Ctrl and S keys simultaneously.
Examples starting with C:\>
indicate a MS-DOS® command. Unless otherwise noted, these
commands may be executed from a “Command Prompt”
window in a modern Microsoft® Windows®
environment.
E:\>
tools\fdimage floppies\kern.flp A:
Examples starting with #
indicate a command that
must be invoked as the superuser in FreeBSD. You can login as
root
to type the
command, or login as your normal account and use su(1) to
gain superuser privileges.
#
dd if=kern.flp of=/dev/fd0
Examples starting with %
indicate a command that
should be invoked from a normal user account. Unless otherwise
noted, C-shell syntax is used for setting environment variables
and other shell commands.
%
top
The book you are holding represents the efforts of many hundreds of people around the world. Whether they sent in fixes for typos, or submitted complete chapters, all the contributions have been useful.
Several companies have supported the development of this document by paying authors to work on it full-time, paying for publication, etc. In particular, BSDi (subsequently acquired by Wind River Systems) paid members of the FreeBSD Documentation Project to work on improving this book full time leading up to the publication of the first printed edition in March 2000 (ISBN 1-57176-241-8). Wind River Systems then paid several additional authors to make a number of improvements to the print-output infrastructure and to add additional chapters to the text. This work culminated in the publication of the second printed edition in November 2001 (ISBN 1-57176-303-1). In 2003-2004, FreeBSD Mall, Inc, paid several contributors to improve the Handbook in preparation for the third printed edition.
This part of the handbook is for users and administrators who are new to FreeBSD. These chapters:
Introduce FreeBSD.
Guide readers through the installation process.
Teach UNIX® basics and fundamentals.
Show how to install the wealth of third party applications available for FreeBSD.
Introduce X, the UNIX® windowing system, and detail how to configure a desktop environment that makes users more productive.
The number of forward references in the text have been kept to a minimum so that this section can be read from front to back with minimal page flipping.
Thank you for your interest in FreeBSD! The following chapter covers various aspects of the FreeBSD Project, such as its history, goals, development model, and so on.
After reading this chapter, you will know:
How FreeBSD relates to other computer operating systems.
The history of the FreeBSD Project.
The goals of the FreeBSD Project.
The basics of the FreeBSD open-source development model.
And of course: where the name “FreeBSD” comes from.
FreeBSD is an Open Source, standards-compliant Unix-like operating system for x86 (both 32 and 64 bit), ARM®, AArch64, RISC-V®, MIPS®, POWER®, PowerPC®, and Sun UltraSPARC® computers. It provides all the features that are nowadays taken for granted, such as preemptive multitasking, memory protection, virtual memory, multi-user facilities, SMP support, all the Open Source development tools for different languages and frameworks, and desktop features centered around X Window System, KDE, or GNOME. Its particular strengths are:
Liberal Open Source license, which grants you rights to freely modify and extend its source code and incorporate it in both Open Source projects and closed products without imposing restrictions typical to copyleft licenses, as well as avoiding potential license incompatibility problems.
Strong TCP/IP networking - FreeBSD implements industry standard protocols with ever increasing performance and scalability. This makes it a good match in both server, and routing/firewalling roles - and indeed many companies and vendors use it precisely for that purpose.
Fully integrated OpenZFS support, including root-on-ZFS, ZFS Boot Environments, fault management, administrative delegation, support for jails, FreeBSD specific documentation, and system installer support.
Extensive security features, from the Mandatory Access Control framework to Capsicum capability and sandbox mechanisms.
Over 30 thousand prebuilt packages for all supported architectures, and the Ports Collection which makes it easy to build your own, customized ones.
Documentation - in addition to Handbook and books from different authors that cover topics ranging from system administration to kernel internals, there are also the man(1) pages, not only for userspace daemons, utilities, and configuration files, but also for kernel driver APIs (section 9) and individual drivers (section 4).
Simple and consistent repository structure and build system - FreeBSD uses a single repository for all of its components, both kernel and userspace. This, along with an unified and easy to customize build system and a well thought out development process makes it easy to integrate FreeBSD with build infrastructure for your own product.
Staying true to Unix philosophy, preferring composability instead of monolithic “all in one” daemons with hardcoded behavior.
Binary compatibility with Linux, which makes it possible to run many Linux binaries without the need for virtualisation.
FreeBSD is based on the 4.4BSD-Lite release from Computer Systems Research Group (CSRG) at the University of California at Berkeley, and carries on the distinguished tradition of BSD systems development. In addition to the fine work provided by CSRG, the FreeBSD Project has put in many thousands of man-hours into extending the functionality and fine-tuning the system for maximum performance and reliability in real-life load situations. FreeBSD offers performance and reliability on par with other Open Source and commercial offerings, combined with cutting-edge features not available anywhere else.
The applications to which FreeBSD can be put are truly limited only by your own imagination. From software development to factory automation, inventory control to azimuth correction of remote satellite antennae; if it can be done with a commercial UNIX® product then it is more than likely that you can do it with FreeBSD too! FreeBSD also benefits significantly from literally thousands of high quality applications developed by research centers and universities around the world, often available at little to no cost.
Because the source code for FreeBSD itself is generally available, the system can also be customized to an almost unheard of degree for special applications or projects, and in ways not generally possible with operating systems from most major commercial vendors. Here is just a sampling of some of the applications in which people are currently using FreeBSD:
Internet Services: The robust TCP/IP networking built into FreeBSD makes it an ideal platform for a variety of Internet services such as:
Education: Are you a student of computer science or a related engineering field? There is no better way of learning about operating systems, computer architecture and networking than the hands on, under the hood experience that FreeBSD can provide. A number of freely available CAD, mathematical and graphic design packages also make it highly useful to those whose primary interest in a computer is to get other work done!
Research: With source code for the entire system available, FreeBSD is an excellent platform for research in operating systems as well as other branches of computer science. FreeBSD's freely available nature also makes it possible for remote groups to collaborate on ideas or shared development without having to worry about special licensing agreements or limitations on what may be discussed in open forums.
Networking: Need a new router? A name server (DNS)? A firewall to keep people out of your internal network? FreeBSD can easily turn that unused PC sitting in the corner into an advanced router with sophisticated packet-filtering capabilities.
Embedded: FreeBSD makes an excellent platform to build embedded systems upon. With support for the ARM®, MIPS® and PowerPC® platforms, coupled with a robust network stack, cutting edge features and the permissive BSD license FreeBSD makes an excellent foundation for building embedded routers, firewalls, and other devices.
Desktop: FreeBSD makes a fine choice for an inexpensive desktop solution using the freely available X11 server. FreeBSD offers a choice from many open-source desktop environments, including the standard GNOME and KDE graphical user interfaces. FreeBSD can even boot “diskless” from a central server, making individual workstations even cheaper and easier to administer.
Software Development: The basic FreeBSD system comes with a full complement of development tools including a full C/C++ compiler and debugger suite. Support for many other languages are also available through the ports and packages collection.
FreeBSD is available to download free of charge, or can be obtained on either CD-ROM or DVD. Please see Appendix A, Obtaining FreeBSD for more information about obtaining FreeBSD.
FreeBSD has been known for its web serving capabilities - sites that run on FreeBSD include Hacker News, Netcraft, NetEase, Netflix, Sina, Sony Japan, Rambler, Yahoo!, and Yandex.
FreeBSD's advanced features, proven security, predictable release cycle, and permissive license have led to its use as a platform for building many commercial and open source appliances, devices, and products. Many of the world's largest IT companies use FreeBSD:
Apache - The Apache Software Foundation runs most of its public facing infrastructure, including possibly one of the largest SVN repositories in the world with over 1.4 million commits, on FreeBSD.
Apple - OS X borrows heavily from FreeBSD for the network stack, virtual file system, and many userland components. Apple iOS also contains elements borrowed from FreeBSD.
Cisco - IronPort network security and anti-spam appliances run a modified FreeBSD kernel.
Citrix - The NetScaler line of security appliances provide layer 4-7 load balancing, content caching, application firewall, secure VPN, and mobile cloud network access, along with the power of a FreeBSD shell.
Dell EMC Isilon - Isilon's enterprise storage appliances are based on FreeBSD. The extremely liberal FreeBSD license allowed Isilon to integrate their intellectual property throughout the kernel and focus on building their product instead of an operating system.
Quest KACE - The KACE system management appliances run FreeBSD because of its reliability, scalability, and the community that supports its continued development.
iXsystems - The TrueNAS line of unified storage appliances is based on FreeBSD. In addition to their commercial products, iXsystems also manages development of the open source projects TrueOS and FreeNAS.
Juniper - The JunOS operating system that powers all Juniper networking gear (including routers, switches, security, and networking appliances) is based on FreeBSD. Juniper is one of many vendors that showcases the symbiotic relationship between the project and vendors of commercial products. Improvements generated at Juniper are upstreamed into FreeBSD to reduce the complexity of integrating new features from FreeBSD back into JunOS in the future.
McAfee - SecurOS, the basis of McAfee enterprise firewall products including Sidewinder is based on FreeBSD.
NetApp - The Data ONTAP GX line of storage appliances are based on FreeBSD. In addition, NetApp has contributed back many features, including the new BSD licensed hypervisor, bhyve.
Netflix - The OpenConnect appliance that Netflix uses to stream movies to its customers is based on FreeBSD. Netflix has made extensive contributions to the codebase and works to maintain a zero delta from mainline FreeBSD. Netflix OpenConnect appliances are responsible for delivering more than 32% of all Internet traffic in North America.
Sandvine - Sandvine uses FreeBSD as the basis of their high performance real-time network processing platforms that make up their intelligent network policy control products.
Sony - The PlayStation 4 gaming console runs a modified version of FreeBSD.
Sophos - The Sophos Email Appliance product is based on a hardened FreeBSD and scans inbound mail for spam and viruses, while also monitoring outbound mail for malware as well as the accidental loss of sensitive information.
Spectra Logic - The nTier line of archive grade storage appliances run FreeBSD and OpenZFS.
Stormshield - Stormshield Network Security appliances are based on a hardened version of FreeBSD. The BSD license allows them to integrate their own intellectual property with the system while returning a great deal of interesting development to the community.
The Weather Channel - The IntelliStar appliance that is installed at each local cable provider's headend and is responsible for injecting local weather forecasts into the cable TV network's programming runs FreeBSD.
Verisign - Verisign is responsible for operating the .com and .net root domain registries as well as the accompanying DNS infrastructure. They rely on a number of different network operating systems including FreeBSD to ensure there is no common point of failure in their infrastructure.
Voxer - Voxer powers their mobile voice messaging platform with ZFS on FreeBSD. Voxer switched from a Solaris derivative to FreeBSD because of its superior documentation, larger and more active community, and more developer friendly environment. In addition to critical features like ZFS and DTrace, FreeBSD also offers TRIM support for ZFS.
WhatsApp - When WhatsApp needed a platform that would be able to handle more than 1 million concurrent TCP connections per server, they chose FreeBSD. They then proceeded to scale past 2.5 million connections per server.
Wheel Systems - The FUDO security appliance allows enterprises to monitor, control, record, and audit contractors and administrators who work on their systems. Based on all of the best security features of FreeBSD including ZFS, GELI, Capsicum, HAST, and auditdistd.
FreeBSD has also spawned a number of related open source projects:
BSD Router - A FreeBSD based replacement for large enterprise routers designed to run on standard PC hardware.
FreeNAS - A customized FreeBSD designed to be used as a network file server appliance. Provides a python based web interface to simplify the management of both the UFS and ZFS file systems. Includes support for NFS, SMB/CIFS, AFP, FTP, and iSCSI. Includes an extensible plugin system based on FreeBSD jails.
GhostBSD - A desktop oriented distribution of FreeBSD bundled with the Gnome desktop environment.
mfsBSD - A toolkit for building a FreeBSD system image that runs entirely from memory.
NAS4Free - A file server distribution based on FreeBSD with a PHP powered web interface.
OPNSense - OPNsense is an open source, easy-to-use and easy-to-build FreeBSD based firewall and routing platform. OPNsense includes most of the features available in expensive commercial firewalls, and more in many cases. It brings the rich feature set of commercial offerings with the benefits of open and verifiable sources.
TrueOS - A customized version of FreeBSD geared towards desktop users with graphical utilities to exposing the power of FreeBSD to all users. Designed to ease the transition of Windows and OS X users.
pfSense - A firewall distribution based on FreeBSD with a huge array of features and extensive IPv6 support.
ZRouter - An open source alternative firmware for embedded devices based on FreeBSD. Designed to replace the proprietary firmware on off-the-shelf routers.
A list of testimonials from companies basing their products and services on FreeBSD can be found at the FreeBSD Foundation website. Wikipedia also maintains a list of products based on FreeBSD.
The following section provides some background information on the project, including a brief history, project goals, and the development model of the project.
The FreeBSD Project had its genesis in the early part of 1993, partially as an outgrowth of the Unofficial 386BSDPatchkit by the patchkit's last 3 coordinators: Nate Williams, Rod Grimes and Jordan Hubbard.
The original goal was to produce an intermediate snapshot of 386BSD in order to fix a number of problems with it that the patchkit mechanism just was not capable of solving. The early working title for the project was 386BSD 0.5 or 386BSD Interim in reference of that fact.
386BSD was Bill Jolitz's operating system, which had been up to that point suffering rather severely from almost a year's worth of neglect. As the patchkit swelled ever more uncomfortably with each passing day, they decided to assist Bill by providing this interim “cleanup” snapshot. Those plans came to a rude halt when Bill Jolitz suddenly decided to withdraw his sanction from the project without any clear indication of what would be done instead.
The trio thought that the goal remained worthwhile, even without Bill's support, and so they adopted the name "FreeBSD" coined by David Greenman. The initial objectives were set after consulting with the system's current users and, once it became clear that the project was on the road to perhaps even becoming a reality, Jordan contacted Walnut Creek CDROM with an eye toward improving FreeBSD's distribution channels for those many unfortunates without easy access to the Internet. Walnut Creek CDROM not only supported the idea of distributing FreeBSD on CD but also went so far as to provide the project with a machine to work on and a fast Internet connection. Without Walnut Creek CDROM's almost unprecedented degree of faith in what was, at the time, a completely unknown project, it is quite unlikely that FreeBSD would have gotten as far, as fast, as it has today.
The first CD-ROM (and general net-wide) distribution was FreeBSD 1.0, released in December of 1993. This was based on the 4.3BSD-Lite (“Net/2”) tape from U.C. Berkeley, with many components also provided by 386BSD and the Free Software Foundation. It was a fairly reasonable success for a first offering, and they followed it with the highly successful FreeBSD 1.1 release in May of 1994.
Around this time, some rather unexpected storm clouds formed on the horizon as Novell and U.C. Berkeley settled their long-running lawsuit over the legal status of the Berkeley Net/2 tape. A condition of that settlement was U.C. Berkeley's concession that large parts of Net/2 were “encumbered” code and the property of Novell, who had in turn acquired it from AT&T some time previously. What Berkeley got in return was Novell's “blessing” that the 4.4BSD-Lite release, when it was finally released, would be declared unencumbered and all existing Net/2 users would be strongly encouraged to switch. This included FreeBSD, and the project was given until the end of July 1994 to stop shipping its own Net/2 based product. Under the terms of that agreement, the project was allowed one last release before the deadline, that release being FreeBSD 1.1.5.1.
FreeBSD then set about the arduous task of literally re-inventing itself from a completely new and rather incomplete set of 4.4BSD-Lite bits. The “Lite” releases were light in part because Berkeley's CSRG had removed large chunks of code required for actually constructing a bootable running system (due to various legal requirements) and the fact that the Intel port of 4.4 was highly incomplete. It took the project until November of 1994 to make this transition, and in December it released FreeBSD 2.0 to the world. Despite being still more than a little rough around the edges, the release was a significant success and was followed by the more robust and easier to install FreeBSD 2.0.5 release in June of 1995.
Since that time, FreeBSD has made a series of releases each time improving the stability, speed, and feature set of the previous version.
For now, long-term development projects continue to take place in the 10.X-CURRENT (trunk) branch, and snapshot releases of 10.X are continually made available from the snapshot server as work progresses.
The goals of the FreeBSD Project are to provide software that may be used for any purpose and without strings attached. Many of us have a significant investment in the code (and project) and would certainly not mind a little financial compensation now and then, but we are definitely not prepared to insist on it. We believe that our first and foremost “mission” is to provide code to any and all comers, and for whatever purpose, so that the code gets the widest possible use and provides the widest possible benefit. This is, I believe, one of the most fundamental goals of Free Software and one that we enthusiastically support.
That code in our source tree which falls under the GNU General Public License (GPL) or Library General Public License (LGPL) comes with slightly more strings attached, though at least on the side of enforced access rather than the usual opposite. Due to the additional complexities that can evolve in the commercial use of GPL software we do, however, prefer software submitted under the more relaxed BSD copyright when it is a reasonable option to do so.
The development of FreeBSD is a very open and flexible process, being literally built from the contributions of thousands of people around the world, as can be seen from our list of contributors. FreeBSD's development infrastructure allow these thousands of contributors to collaborate over the Internet. We are constantly on the lookout for new developers and ideas, and those interested in becoming more closely involved with the project need simply contact us at the FreeBSD technical discussions mailing list. The FreeBSD announcements mailing list is also available to those wishing to make other FreeBSD users aware of major areas of work.
Useful things to know about the FreeBSD Project and its development process, whether working independently or in close cooperation:
For several years, the central source tree for FreeBSD
was maintained by
CVS
(Concurrent Versions System), a freely available source
code control tool. In June 2008, the Project switched
to using SVN
(Subversion). The switch was deemed necessary, as the
technical limitations imposed by
CVS were becoming obvious due
to the rapid expansion of the source tree and the amount
of history already stored. The Documentation Project
and Ports Collection repositories also moved from
CVS to
SVN in May 2012 and July
2012, respectively. Please refer to the Synchronizing your source
tree section for more information on obtaining
the FreeBSD src/
repository and Using the Ports
Collection for details on obtaining the FreeBSD
Ports Collection.
The committers
are the people who have
write access to the Subversion
tree, and are authorized to make modifications to the
FreeBSD source (the term “committer” comes
from commit
, the source control
command which is used to bring new changes into the
repository). Anyone can submit a bug to the Bug
Database. Before submitting a bug report, the
FreeBSD mailing lists, IRC channels, or forums can be used to
help verify that an issue is actually a bug.
The FreeBSD core team would be equivalent to the board of directors if the FreeBSD Project were a company. The primary task of the core team is to make sure the project, as a whole, is in good shape and is heading in the right directions. Inviting dedicated and responsible developers to join our group of committers is one of the functions of the core team, as is the recruitment of new core team members as others move on. The current core team was elected from a pool of committer candidates in July 2018. Elections are held every 2 years.
Like most developers, most members of the core team are also volunteers when it comes to FreeBSD development and do not benefit from the project financially, so “commitment” should also not be misconstrued as meaning “guaranteed support.” The “board of directors” analogy above is not very accurate, and it may be more suitable to say that these are the people who gave up their lives in favor of FreeBSD against their better judgement!
Last, but definitely not least, the largest group of developers are the users themselves who provide feedback and bug fixes to us on an almost constant basis. The primary way of keeping in touch with FreeBSD's more non-centralized development is to subscribe to the FreeBSD technical discussions mailing list where such things are discussed. See Appendix C, Resources on the Internet for more information about the various FreeBSD mailing lists.
The FreeBSD Contributors List is a long and growing one, so why not join it by contributing something back to FreeBSD today?
Providing code is not the only way of contributing to the project; for a more complete list of things that need doing, please refer to the FreeBSD Project web site.
In summary, our development model is organized as a loose set of concentric circles. The centralized model is designed for the convenience of the users of FreeBSD, who are provided with an easy way of tracking one central code base, not to keep potential contributors out! Our desire is to present a stable operating system with a large set of coherent application programs that the users can easily install and use — this model works very well in accomplishing that.
All we ask of those who would join us as FreeBSD developers is some of the same dedication its current people have to its continued success!
In addition to the base distributions, FreeBSD offers a
ported software collection with thousands of commonly
sought-after programs. At the time of this writing, there
were over 24,000 ports! The list of ports ranges from
http servers, to games, languages, editors, and almost
everything in between. The entire Ports Collection requires
approximately 500 MB. To compile a port, you simply
change to the directory of the program you wish to install,
type make install
, and let the system do
the rest. The full original distribution for each port you
build is retrieved dynamically so you need only enough disk
space to build the ports you want. Almost every port is also
provided as a pre-compiled “package”, which can
be installed with a simple command
(pkg install
) by those who do not wish to
compile their own ports from source. More information on
packages and ports can be found in
Chapter 4, Installing Applications: Packages and Ports.
All supported FreeBSD versions provide an option in the
installer to
install additional documentation under
/usr/local/share/doc/freebsd
during the
initial system setup. Documentation may also be installed at
any later time using packages as described in
Section 23.3.2, “Updating Documentation from Ports”. You may view the
locally installed manuals with any HTML capable browser using
the following URLs:
You can also view the master (and most frequently updated)
copies at https://www.FreeBSD.org/
.
There are several different ways of getting FreeBSD to run, depending on the environment. Those are:
Virtual Machine images, to download and import on a virtual environment of choice. These can be downloaded from the Download FreeBSD page. There are images for KVM (“qcow2”), VMWare (“vmdk”), Hyper-V (“vhd”), and raw device images that are universally supported. These are not installation images, but rather the preconfigured (“already installed”) instances, ready to run and perform post-installation tasks.
Virtual Machine images available at Amazon's AWS Marketplace, Microsoft Azure Marketplace, and Google Cloud Platform, to run on their respective hosting services. For more information on deploying FreeBSD on Azure please consult the relevant chapter in the Azure Documentation.
SD card images, for embedded systems such as Raspberry Pi or BeagleBone Black. These can be downloaded from the Download FreeBSD page. These files must be uncompressed and written as a raw image to an SD card, from which the board will then boot.
Installation images, to install FreeBSD on a hard drive for the usual desktop, laptop, or server systems.
The rest of this chapter describes the fourth case, explaining how to install FreeBSD using the text-based installation program named bsdinstall.
In general, the installation instructions in this chapter are written for the i386™ and AMD64 architectures. Where applicable, instructions specific to other platforms will be listed. There may be minor differences between the installer and what is shown here, so use this chapter as a general guide rather than as a set of literal instructions.
Users who prefer to install FreeBSD using a graphical installer may be interested in pc-sysinstall, the installer used by the TrueOS Project. It can be used to install either a graphical desktop (TrueOS) or a command line version of FreeBSD. Refer to the TrueOS Users Handbook for details (https://www.trueos.org/handbook/trueos.html).
After reading this chapter, you will know:
The minimum hardware requirements and FreeBSD supported architectures.
How to create the FreeBSD installation media.
How to start bsdinstall.
The questions bsdinstall will ask, what they mean, and how to answer them.
How to troubleshoot a failed installation.
How to access a live version of FreeBSD before committing to an installation.
Before reading this chapter, you should:
Read the supported hardware list that shipped with the version of FreeBSD to be installed and verify that the system's hardware is supported.
The hardware requirements to install FreeBSD vary by architecture. Hardware architectures and devices supported by a FreeBSD release are listed on the FreeBSD Release Information page. The FreeBSD download page also has recommendations for choosing the correct image for different architectures.
A FreeBSD installation requires a minimum of 96 MB of RAM and 1.5 GB of free hard drive space. However, such small amounts of memory and disk space are really only suitable for custom applications like embedded appliances. General-purpose desktop systems need more resources. 2-4 GB RAM and at least 8 GB hard drive space is a good starting point.
These are the processor requirements for each architecture:
This is the most common desktop and laptop processor type, used in most modern systems. Intel® calls it Intel64. Other manufacturers sometimes call it x86-64.
Examples of amd64 compatible processors include: AMD Athlon™64, AMD Opteron™, multi-core Intel® Xeon™, and Intel® Core™ 2 and later processors.
Older desktops and laptops often use this 32-bit, x86 architecture.
Almost all i386-compatible processors with a floating point unit are supported. All Intel® processors 486 or higher are supported.
FreeBSD will take advantage of Physical Address Extensions (PAE) support on CPUs with this feature. A kernel with the PAE feature enabled will detect memory above 4 GB and allow it to be used by the system. However, using PAE places constraints on device drivers and other features of FreeBSD. Refer to pae(4) for details.
Currently supported processors are the Itanium® and the Itanium® 2. Supported chipsets include the HP zx1, Intel® 460GX, and Intel® E8870. Both Uniprocessor (UP) and Symmetric Multi-processor (SMP) configurations are supported.
All New World ROM Apple® Mac® systems with built-in USB are supported. SMP is supported on machines with multiple CPUs.
A 32-bit kernel can only use the first 2 GB of RAM.
Systems supported by FreeBSD/sparc64 are listed at the FreeBSD/sparc64 Project.
SMP is supported on all systems with more than 1 processor. A dedicated disk is required as it is not possible to share a disk with another operating system at this time.
Once it has been determined that the system meets the minimum hardware requirements for installing FreeBSD, the installation file should be downloaded and the installation media prepared. Before doing this, check that the system is ready for an installation by verifying the items in this checklist:
Back Up Important Data
Before installing any operating system, always backup all important data first. Do not store the backup on the system being installed. Instead, save the data to a removable disk such as a USB drive, another system on the network, or an online backup service. Test the backup before starting the installation to make sure it contains all of the needed files. Once the installer formats the system's disk, all data stored on that disk will be lost.
Decide Where to Install FreeBSD
If FreeBSD will be the only operating system installed, this step can be skipped. But if FreeBSD will share the disk with another operating system, decide which disk or partition will be used for FreeBSD.
In the i386 and amd64 architectures, disks can be divided into multiple partitions using one of two partitioning schemes. A traditional Master Boot Record (MBR) holds a partition table defining up to four primary partitions. For historical reasons, FreeBSD calls these primary partition slices. One of these primary partitions can be made into an extended partition containing multiple logical partitions. The GUID Partition Table (GPT) is a newer and simpler method of partitioning a disk. Common GPT implementations allow up to 128 partitions per disk, eliminating the need for logical partitions.
Some older operating systems, like Windows® XP, are not compatible with the GPT partition scheme. If FreeBSD will be sharing a disk with such an operating system, MBR partitioning is required.
The FreeBSD boot loader requires either a primary or GPT partition. If all of the primary or GPT partitions are already in use, one must be freed for FreeBSD. To create a partition without deleting existing data, use a partition resizing tool to shrink an existing partition and create a new partition using the freed space.
A variety of free and commercial partition resizing tools are listed at http://en.wikipedia.org/wiki/List_of_disk_partitioning_software. GParted Live (http://gparted.sourceforge.net/livecd.php) is a free live CD which includes the GParted partition editor. GParted is also included with many other Linux live CD distributions.
When used properly, disk shrinking utilities can safely create space for creating a new partition. Since the possibility of selecting the wrong partition exists, always backup any important data and verify the integrity of the backup before modifying disk partitions.
Disk partitions containing different operating systems make it possible to install multiple operating systems on one computer. An alternative is to use virtualization (Chapter 21, Virtualization) which allows multiple operating systems to run at the same time without modifying any disk partitions.
Collect Network Information
Some FreeBSD installation methods require a network connection in order to download the installation files. After any installation, the installer will offer to setup the system's network interfaces.
If the network has a DHCP server, it can be used to provide automatic network configuration. If DHCP is not available, the following network information for the system must be obtained from the local network administrator or Internet service provider:
Check for FreeBSD Errata
Although the FreeBSD Project strives to ensure that each release of FreeBSD is as stable as possible, bugs occasionally creep into the process. On very rare occasions those bugs affect the installation process. As these problems are discovered and fixed, they are noted in the FreeBSD Errata (https://www.freebsd.org/releases/12.0R/errata.html) on the FreeBSD web site. Check the errata before installing to make sure that there are no problems that might affect the installation.
Information and errata for all the releases can be found on the release information section of the FreeBSD web site (https://www.freebsd.org/releases/index.html).
The FreeBSD installer is not an application that can be run from within another operating system. Instead, download a FreeBSD installation file, burn it to the media associated with its file type and size (CD, DVD, or USB), and boot the system to install from the inserted media.
FreeBSD installation files are available at www.freebsd.org/where.html#download.
Each installation file's name includes the release version of
FreeBSD, the architecture, and the type of file. For example, to
install FreeBSD 10.2 on an amd64 system from a
DVD, download
FreeBSD-10.2-RELEASE-amd64-dvd1.iso
, burn
this file to a DVD, and boot the system
with the DVD inserted.
Installation files are available in several formats. The formats vary depending on computer architecture and media type.
Additional
installation files are included for computers that boot with
UEFI (Unified Extensible Firmware
Interface). The names of these files include the string
uefi
.
File types:
-bootonly.iso
: This is the smallest
installation file as it only contains the installer. A
working Internet connection is required during
installation as the installer will download the files it
needs to complete the FreeBSD installation. This file should
be burned to a CD using a
CD burning application.
-disc1.iso
: This file contains all
of the files needed to install FreeBSD, its source, and the
Ports Collection. It should be burned to a
CD using a CD
burning application.
-dvd1.iso
: This file contains all
of the files needed to install FreeBSD, its source, and the
Ports Collection. It also contains a set of popular
binary packages for installing a window manager and some
applications so that a complete system can be installed
from media without requiring a connection to the Internet.
This file should be burned to a DVD
using a DVD burning application.
-memstick.img
: This file contains
all of the files needed to install FreeBSD, its source, and
the Ports Collection. It should be burned to a
USB stick using the instructions
below.
-mini-memstick.img
: Like
-bootonly.iso
, does not include
installation files, but downloads them as needed. A
working internet connection is required during
installation. Write this file to a USB
stick as shown in Section 2.3.1.1, “Writing an Image File to USB”.
After downloading the image file, download
CHECKSUM.SHA256
from
the same directory. Calculate a
checksum for the image file.
FreeBSD provides sha256(1) for this, used as sha256
.
Other operating systems have similar programs.imagefilename
Compare the calculated checksum with the one shown in
CHECKSUM.SHA256
. The checksums must
match exactly. If the checksums do not match, the image file
is corrupt and must be downloaded again.
The *.img
file is an
image of the complete contents of a
memory stick. It cannot be copied to
the target device as a file. Several applications are
available for writing the *.img
to a
USB stick. This section describes two of
these utilities.
Before proceeding, back up any important data on the USB stick. This procedure will erase the existing data on the stick.
dd
to Write the
ImageThis example uses /dev/da0
as
the target device where the image will be written. Be
very careful that the correct
device is used as this command will destroy the existing
data on the specified target device.
The dd(1) command-line utility is
available on BSD, Linux®, and Mac OS® systems. To burn
the image using dd
, insert the
USB stick and determine its device
name. Then, specify the name of the downloaded
installation file and the device name for the
USB stick. This example burns the
amd64 installation image to the first
USB device on an existing FreeBSD
system.
#
dd if=
FreeBSD-10.2-RELEASE-amd64-memstick.img
of=/dev/da0
bs=1M conv=sync
If this command fails, verify that the
USB stick is not mounted and that the
device name is for the disk, not a partition. Some
operating systems might require this command to be run
with sudo(8). The dd(1) syntax varies slightly
across different platforms; for example, Mac OS® requires
a lower-case bs=1m
.
Systems like Linux® might buffer
writes. To force all writes to complete, use
sync(8).
Be sure to give the correct drive letter as the existing data on the specified drive will be overwritten and destroyed.
Obtaining Image Writer for Windows®
Image Writer for
Windows® is a free application that can
correctly write an image file to a memory stick.
Download it from https://sourceforge.net/projects/win32diskimager/
and extract it into a folder.
Writing the Image with Image Writer
Double-click the
Win32DiskImager icon to start
the program. Verify that the drive letter shown under
Device
is the drive
with the memory stick. Click the folder icon and select
the image to be written to the memory stick. Click
to accept the
image file name. Verify that everything is correct, and
that no folders on the memory stick are open in other
windows. When everything is ready, click
to write the
image file to the memory stick.
You are now ready to start installing FreeBSD.
By default, the installation will not make any changes to the disk(s) before the following message:
Your changes will now be written to disk. If you have chosen to overwrite existing data, it will be PERMANENTLY ERASED. Are you sure you want to commit your changes?
The install can be exited at any time prior to this warning. If there is a concern that something is incorrectly configured, just turn the computer off before this point and no changes will be made to the system's disks.
This section describes how to boot the system from the installation media which was prepared using the instructions in Section 2.3.1, “Prepare the Installation Media”. When using a bootable USB stick, plug in the USB stick before turning on the computer. When booting from CD or DVD, turn on the computer and insert the media at the first opportunity. How to configure the system to boot from the inserted media depends upon the architecture.
These architectures provide a BIOS menu for selecting the boot device. Depending upon the installation media being used, select the CD/DVD or USB device as the first boot device. Most systems also provide a key for selecting the boot device during startup without having to enter the BIOS. Typically, the key is either F10, F11, F12, or Escape.
If the computer loads the existing operating system instead of the FreeBSD installer, then either:
The installation media was not inserted early enough in the boot process. Leave the media inserted and try restarting the computer.
The BIOS changes were incorrect or not saved. Double-check that the right boot device is selected as the first boot device.
This system is too old to support booting from the chosen media. In this case, the Plop Boot Manager (http://www.plop.at/en/bootmanagers.html) can be used to boot the system from the selected media.
On most machines, holding C on the
keyboard during boot will boot from the CD.
Otherwise, hold Command+Option+O+F, or
Windows+Alt+O+F on non-Apple® keyboards. At the
0 >
prompt, enter
boot cd:,\ppc\loader cd:0
Most SPARC64® systems are set up to boot automatically from disk. To install FreeBSD from a CD requires a break into the PROM.
To do this, reboot the system and wait until the boot message appears. The message depends on the model, but should look something like this:
Sun Blade 100 (UltraSPARC-IIe), Keyboard Present Copyright 1998-2001 Sun Microsystems, Inc. All rights reserved. OpenBoot 4.2, 128 MB memory installed, Serial #51090132. Ethernet address 0:3:ba:b:92:d4, Host ID: 830b92d4.
If the system proceeds to boot from disk at this point,
press L1+A
or Stop+A
on the keyboard, or send a BREAK
over the
serial console. When using tip or
cu, ~#
will
issue a BREAK. The PROM prompt will be
ok
on systems with one
CPU and ok {0}
on
SMP systems, where the digit indicates the
number of the active CPU.
At this point, place the CD into the
drive and type boot cdrom
from the
PROM prompt.
Once the system boots from the installation media, a menu similar to the following will be displayed:
By default, the menu will wait ten seconds for user input before booting into the FreeBSD installer or, if FreeBSD is already installed, before booting into FreeBSD. To pause the boot timer in order to review the selections, press Space. To select an option, press its highlighted number, character, or key. The following options are available.
Boot Multi User
: This will
continue the FreeBSD boot process. If the boot timer has
been paused, press 1, upper- or
lower-case B, or
Enter.
Boot Single User
: This mode can be
used to fix an existing FreeBSD installation as described in
Section 12.2.4.1, “Single-User Mode”. Press
2 or the upper- or lower-case
S to enter this mode.
Escape to loader prompt
: This will
boot the system into a repair prompt that contains a
limited number of low-level commands. This prompt is
described in Section 12.2.3, “Stage Three”. Press
3 or Esc to boot into
this prompt.
Reboot
: Reboots the system.
Configure Boot Options
: Opens the
menu shown in, and described under, Figure 2.2, “FreeBSD Boot Options Menu”.
The boot options menu is divided into two sections. The first section can be used to either return to the main boot menu or to reset any toggled options back to their defaults.
The next section is used to toggle the available options
to On
or Off
by pressing
the option's highlighted number or character. The system will
always boot using the settings for these options until they
are modified. Several options can be toggled using this
menu:
ACPI Support
: If the system hangs
during boot, try toggling this option to
Off
.
Safe Mode
: If the system still
hangs during boot even with ACPI
Support
set to Off
, try
setting this option to On
.
Single User
: Toggle this option to
On
to fix an existing FreeBSD installation
as described in Section 12.2.4.1, “Single-User Mode”. Once
the problem is fixed, set it back to
Off
.
Verbose
: Toggle this option to
On
to see more detailed messages during
the boot process. This can be useful when troubleshooting
a piece of hardware.
After making the needed selections, press 1 or Backspace to return to the main boot menu, then press Enter to continue booting into FreeBSD. A series of boot messages will appear as FreeBSD carries out its hardware device probes and loads the installation program. Once the boot is complete, the welcome menu shown in Figure 2.3, “Welcome Menu” will be displayed.
Press Enter to select the default of to enter the installer. The rest of this chapter describes how to use this installer. Otherwise, use the right or left arrows or the colorized letter to select the desired menu item. The can be used to access a FreeBSD shell in order to use command line utilities to prepare the disks before installation. The option can be used to try out FreeBSD before installing it. The live version is described in Section 2.10, “Using the Live CD”.
To review the boot messages, including the hardware
device probe, press the upper- or lower-case
S and then Enter to access
a shell. At the shell prompt, type more
/var/run/dmesg.boot
and use the space bar to
scroll through the messages. When finished, type
exit
to return to the welcome
menu.
This section shows the order of the bsdinstall menus and the type of information that will be asked before the system is installed. Use the arrow keys to highlight a menu option, then Space to select or deselect that menu item. When finished, press Enter to save the selection and move onto the next screen.
Depending on the system console being used, bsdinstall may initially display the menu shown in Figure 2.4, “Keymap Selection”.
To configure the keyboard layout, press Enter with selected, which will display the menu shown in Figure 2.5, “Selecting Keyboard Menu”. To instead use the default layout, use the arrow key to select and press Enter to skip this menu screen.
When configuring the keyboard layout, use the up and down arrows to select the keymap that most closely represents the mapping of the keyboard attached to the system. Press Enter to save the selection.
Pressing Esc will exit this menu and use the default keymap. If the choice of keymap is not clear, is also a safe option.
In FreeBSD 10.0-RELEASE and later, this menu has been enhanced. The full selection of keymaps is shown, with the default preselected. In addition, when selecting a different keymap, a dialog is displayed that allows the user to try the keymap and ensure it is correct before proceeding.
The next bsdinstall menu is used to set the hostname for the newly installed system.
Type in a hostname that is unique for the network. It
should be a fully-qualified hostname, such as machine3.example.com
.
Next, bsdinstall will prompt to select optional components to install.
Deciding which components to install will depend largely on the intended use of the system and the amount of disk space available. The FreeBSD kernel and userland, collectively known as the base system, are always installed. Depending on the architecture, some of these components may not appear:
doc
- Additional documentation,
mostly of historical interest, to install into
/usr/share/doc
. The documentation
provided by the FreeBSD Documentation Project may be
installed later using the instructions in Section 23.3, “Updating the Documentation Set”.
games
- Several traditional
BSD games, including
fortune,
rot13, and others.
lib32
- Compatibility libraries for
running 32-bit applications on a 64-bit version of
FreeBSD.
ports
- The FreeBSD Ports Collection
is a collection of files which automates the downloading,
compiling and installation of third-party software
packages. Chapter 4, Installing Applications: Packages and Ports discusses how to use
the Ports Collection.
The installation program does not check for adequate disk space. Select this option only if sufficient hard disk space is available. The FreeBSD Ports Collection takes up about 500 MB of disk space.
src
- The complete FreeBSD source code
for both the kernel and the userland. Although not
required for the majority of applications, it may be
required to build device drivers, kernel modules, or some
applications from the Ports Collection. It is also used
for developing FreeBSD itself. The full source tree requires
1 GB of disk space and recompiling the entire FreeBSD
system requires an additional 5 GB of space.
The menu shown in Figure 2.9, “Installing from the Network” only appears when
installing from a -bootonly.iso
CD as this installation media does not hold
copies of the installation files. Since the installation
files must be retrieved over a network connection, this menu
indicates that the network interface must be first
configured.
To configure the network connection, press Enter and follow the instructions in Section 2.8.2, “Configuring Network Interfaces”. Once the interface is configured, select a mirror site that is located in the same region of the world as the computer on which FreeBSD is being installed. Files can be retrieved more quickly when the mirror is close to the target computer, reducing installation time.
Installation will then continue as if the installation files were located on the local installation media.
The next menu is used to determine the method for allocating disk space.
Guided
partitioning automatically sets up
the disk partitions, Manual
partitioning
allows advanced users to create customized partitions from menu
options, and Shell
opens a shell prompt where
advanced users can create customized partitions using
command-line utilities like gpart(8), fdisk(8), and
bsdlabel(8). ZFS
partitioning, only
available in FreeBSD 10 and later, creates an optionally encrypted
root-on-ZFS system with support for boot
environments.
This section describes what to consider when laying out the disk partitions. It then demonstrates how to use the different partitioning methods.
When laying out file systems, remember that hard drives
transfer data faster from the outer tracks to the inner.
Thus, smaller and heavier-accessed file systems should be
closer to the outside of the drive, while larger partitions
like /usr
should be placed toward the
inner parts of the disk. It is a good idea to create
partitions in an order similar to: /
,
swap, /var
, and
/usr
.
The size of the /var
partition
reflects the intended machine's usage. This partition is
used to hold mailboxes, log files, and printer spools.
Mailboxes and log files can grow to unexpected sizes
depending on the number of users and how long log files are
kept. On average, most users rarely need more than about a
gigabyte of free disk space in
/var
.
Sometimes, a lot of disk space is required in
/var/tmp
. When new software is
installed, the packaging tools extract a temporary copy of
the packages under /var/tmp
. Large
software packages, like Firefox,
Apache OpenOffice or
LibreOffice may be tricky to
install if there is not enough disk space under
/var/tmp
.
The /usr
partition holds many of the
files which support the system, including the FreeBSD Ports
Collection and system source code. At least 2 gigabytes of
space is recommended for this partition.
When selecting partition sizes, keep the space requirements in mind. Running out of space in one partition while barely using another can be a hassle.
As a rule of thumb, the swap partition should be about double the size of physical memory (RAM). Systems with minimal RAM may perform better with more swap. Configuring too little swap can lead to inefficiencies in the VM page scanning code and might create issues later if more memory is added.
On larger systems with multiple SCSI disks or multiple IDE disks operating on different controllers, it is recommended that swap be configured on each drive, up to four drives. The swap partitions should be approximately the same size. The kernel can handle arbitrary sizes but internal data structures scale to 4 times the largest swap partition. Keeping the swap partitions near the same size will allow the kernel to optimally stripe swap space across disks. Large swap sizes are fine, even if swap is not used much. It might be easier to recover from a runaway program before being forced to reboot.
By properly partitioning a system, fragmentation
introduced in the smaller write heavy partitions will not
bleed over into the mostly read partitions. Keeping the
write loaded partitions closer to the disk's edge will
increase I/O performance in the
partitions where it occurs the most. While
I/O performance in the larger partitions
may be needed, shifting them more toward the edge of the disk
will not lead to a significant performance improvement over
moving /var
to the edge.
When this method is selected, a menu will display the available disk(s). If multiple disks are connected, choose the one where FreeBSD is to be installed.
Once the disk is selected, the next menu prompts to install to either the entire disk or to create a partition using free space. If
is chosen, a general partition layout filling the whole disk is automatically created. Selecting creates a partition layout from the unused space on the disk.After the partition layout has been created, review it to ensure it meets the needs of the installation. Selecting
will reset the partitions to their original values and pressing will recreate the automatic FreeBSD partitions. Partitions can also be manually created, modified, or deleted. When the partitioning is correct, select to continue with the installation.Selecting this method opens the partition editor:
Highlight the installation drive
(ada0
in this example) and select
to display a menu
of available partition schemes:
GPT is usually the most appropriate choice for amd64 computers. Older computers that are not compatible with GPT should use MBR. The other partition schemes are generally used for uncommon or older computers.
Abbreviation | Description |
---|---|
APM | Apple Partition Map, used by PowerPC®. |
BSD | BSD label without an MBR, sometimes called dangerously dedicated mode as non-BSD disk utilities may not recognize it. |
GPT | GUID Partition Table (http://en.wikipedia.org/wiki/GUID_Partition_Table). |
MBR | Master Boot Record (http://en.wikipedia.org/wiki/Master_boot_record). |
PC98 | MBR variant used by NEC PC-98 computers (http://en.wikipedia.org/wiki/Pc9801). |
VTOC8 | Volume Table Of Contents used by Sun SPARC64 and UltraSPARC computers. |
After the partitioning scheme has been selected and created, select Tab key is used to move the cursor between fields.
again to create the partitions. TheA standard FreeBSD GPT installation uses at least three partitions:
freebsd-boot
- Holds the FreeBSD boot
code.
freebsd-ufs
- A FreeBSD
UFS file system.
freebsd-swap
- FreeBSD swap
space.
Another partition type worth noting is
freebsd-zfs
, used for partitions that will
contain a FreeBSD ZFS file system (Chapter 19, The Z File System (ZFS)). Refer to gpart(8) for
descriptions of the available GPT partition
types.
Multiple file system partitions can be created and some
people prefer a traditional layout with separate partitions
for /
, /var
,
/tmp
, and /usr
. See
Example 2.1, “Creating Traditional Split File System
Partitions” for an
example.
The Size
may be entered with common
abbreviations: K for kilobytes,
M for megabytes, or
G for gigabytes.
Proper sector alignment provides the best performance, and making partition sizes even multiples of 4K bytes helps to ensure alignment on drives with either 512-byte or 4K-byte sectors. Generally, using partition sizes that are even multiples of 1M or 1G is the easiest way to make sure every partition starts at an even multiple of 4K. There is one exception: the freebsd-boot partition should be no larger than 512K due to current boot code limitations.
A Mountpoint
is needed if the partition
will contain a file system. If only a single
UFS partition will be created, the
mountpoint should be /
.
The Label
is a name by which the
partition will be known. Drive names or numbers can change if
the drive is connected to a different controller or port, but
the partition label does not change. Referring to labels
instead of drive names and partition numbers in files like
/etc/fstab
makes the system more tolerant
to hardware changes. GPT labels appear in
/dev/gpt/
when a disk is attached. Other
partitioning schemes have different label capabilities and
their labels appear in different directories in
/dev/
.
Use a unique label on every partition to avoid
conflicts from identical labels. A few letters from the
computer's name, use, or location can be added to the label.
For instance, use labroot
or
rootfslab
for the UFS
root partition on the computer named
lab
.
For a traditional partition layout where the
/
, /var
,
/tmp
, and /usr
directories are separate file systems on their own
partitions, create a GPT partitioning
scheme, then create the partitions as shown. Partition
sizes shown are typical for a 20G target disk. If more
space is available on the target disk, larger swap or
/var
partitions may be useful. Labels
shown here are prefixed with ex
for
“example”, but readers should use other unique
label values as described above.
By default, FreeBSD's gptboot
expects
the first UFS partition to be the
/
partition.
Partition Type | Size | Mountpoint | Label |
---|---|---|---|
freebsd-boot | 512K | ||
freebsd-ufs | 2G | / | exrootfs |
freebsd-swap | 4G | exswap | |
freebsd-ufs | 2G | /var | exvarfs |
freebsd-ufs | 1G | /tmp | extmpfs |
freebsd-ufs | accept the default (remainder of the disk) | /usr | exusrfs |
After the custom partitions have been created, select
to continue with the installation.Support for automatic creation of root-on-ZFS
installations was added in FreeBSD 10.0-RELEASE. This
partitioning mode only works with whole disks and will erase
the contents of the entire disk. The installer will
automatically create partitions aligned to 4k boundaries and
force ZFS to use 4k sectors. This is safe
even with 512 byte sector disks, and has the added benefit of
ensuring that pools created on 512 byte disks will be able to
have 4k sector disks added in the future, either as additional
storage space or as replacements for failed disks. The
installer can also optionally employ GELI
disk encryption as described in Section 17.12.2, “Disk Encryption with geli
”.
If encryption is enabled, a 2 GB unencrypted boot pool
containing the /boot
directory is
created. It holds the kernel and other files necessary to
boot the system. A swap partition of a user selectable size
is also created, and all remaining space is used for the
ZFS pool.
The main ZFS configuration menu offers a number of options to control the creation of the pool.
Select T to configure the Pool
Type
and the disk(s) that will constitute the
pool. The automatic ZFS installer
currently only supports the creation of a single top level
vdev, except in stripe mode. To create more complex pools,
use the instructions in Section 2.6.5, “Shell Mode Partitioning” to create the pool. The
installer supports the creation of various pool types,
including stripe (not recommended, no redundancy), mirror
(best performance, least usable space), and RAID-Z 1, 2, and 3
(with the capability to withstand the concurrent failure of 1,
2, and 3 disks, respectively). While selecting the pool type,
a tooltip is displayed across the bottom of the screen with
advice about the number of required disks, and in the case of
RAID-Z, the optimal number of disks for each
configuration.
Once a Pool Type
has been selected, a
list of available disks is displayed, and the user is prompted
to select one or more disks to make up the pool. The
configuration is then validated, to ensure enough disks are
selected. If not, select to return to the list of disks, or
to change the pool
type.
If one or more disks are missing from the list, or if disks were attached after the installer was started, select
to repopulate the list of available disks. To avoid accidentally erasing the wrong disk, the menu can be used to inspect each disk, including its partition table and various other information such as the device model number and serial number, if available.The main ZFS configuration menu also allows the user to enter a pool name, disable forcing 4k sectors, enable or disable encryption, switch between GPT (recommended) and MBR partition table types, and select the amount of swap space. Once all options have been set to the desired values, select the
option at the top of the menu.If GELI disk encryption was enabled, the installer will prompt twice for the passphrase to be used to encrypt the disks.
The installer then offers a last chance to cancel before the contents of the selected drives are destroyed to create the ZFS pool.
The installation then proceeds normally.
When creating advanced installations, the
bsdinstall partitioning menus may
not provide the level of flexibility required. Advanced users
can select the option from the
partitioning menu in order to manually partition the drives,
create the file system(s), populate
/tmp/bsdinstall_etc/fstab
, and mount the
file systems under /mnt
. Once this is
done, type exit
to return to
bsdinstall and continue the
installation.
Once the disks are configured, the next menu provides the last chance to make changes before the selected hard drive(s) are formatted. If changes need to be made, select
to return to the main partitioning menu. will exit the installer without making any changes to the hard drive.To instead start the actual installation, select Enter.
and pressInstallation time will vary depending on the distributions chosen, installation media, and speed of the computer. A series of messages will indicate the progress.
First, the installer formats the selected disk(s) and initializes the partitions. Next, in the case of a bootonly media, it downloads the selected components:
Next, the integrity of the distribution files is verified to ensure they have not been corrupted during download or misread from the installation media:
Finally, the verified distribution files are extracted to the disk:
Once all requested distribution files have been extracted, bsdinstall displays the first post-installation configuration screen. The available post-configuration options are described in the next section.
Once FreeBSD is installed, bsdinstall will prompt to configure several options before booting into the newly installed system. This section describes these configuration options.
Once the system has booted,
bsdconfig
provides a menu-driven method for
configuring the system using these and additional
options.
First, the root
password must be set. While entering the password, the
characters being typed are not displayed on the screen. After
the password has been entered, it must be entered again. This
helps prevent typing errors.
Next, a list of the network interfaces found on the computer is shown. Select the interface to configure.
The network configuration menus will be skipped if the network was previously configured as part of a bootonly installation.
If an Ethernet interface is selected, the installer will skip ahead to the menu shown in Figure 2.34, “Choose IPv4 Networking”. If a wireless network interface is chosen, the system will instead scan for wireless access points:
Wireless networks are identified by a Service Set Identifier (SSID), a short, unique name given to each network. SSIDs found during the scan are listed, followed by a description of the encryption types available for that network. If the desired SSID does not appear in the list, select
to scan again. If the desired network still does not appear, check for problems with antenna connections or try moving the computer closer to the access point. Rescan after each change is made.Next, enter the encryption information for connecting to the selected wireless network. WPA2 encryption is strongly recommended as older encryption types, like WEP, offer little security. If the network uses WPA2, input the password, also known as the Pre-Shared Key (PSK). For security reasons, the characters typed into the input box are displayed as asterisks.
Next, choose whether or not an IPv4 address should be configured on the Ethernet or wireless interface:
There are two methods of IPv4 configuration. DHCP will automatically configure the network interface correctly and should be used if the network provides a DHCP server. Otherwise, the addressing information needs to be input manually as a static configuration.
Do not enter random network information as it will not work. If a DHCP server is not available, obtain the information listed in Required Network Information from the network administrator or Internet service provider.
If a DHCP server is available, select
in the next menu to automatically configure the network interface. The installer will appear to pause for a minute or so as it finds the DHCP server and obtains the addressing information for the system.If a DHCP server is not available, select
and input the following addressing information in this menu:IP Address
- The
IPv4 address assigned to this computer.
The address must be unique and not already in use by
another piece of equipment on the local network.
Subnet Mask
- The subnet mask for
the network.
Default Router
- The
IP address of the network's default
gateway.
The next screen will ask if the interface should be configured for IPv6. If IPv6 is available and desired, choose
to select it.IPv6 also has two methods of configuration. StateLess Address AutoConfiguration (SLAAC) will automatically request the correct configuration information from a local router. Refer to http://tools.ietf.org/html/rfc4862 for more information. Static configuration requires manual entry of network information.
If an IPv6 router is available, select
in the next menu to automatically configure the network interface. The installer will appear to pause for a minute or so as it finds the router and obtains the addressing information for the system.If an IPv6 router is not available, select
and input the following addressing information in this menu:IPv6 Address
- The
IPv6 address assigned to this computer.
The address must be unique and not already in use by
another piece of equipment on the local network.
Default Router
- The
IPv6 address of the network's default
gateway.
The last network configuration menu is used to configure
the Domain Name System (DNS) resolver,
which converts hostnames to and from network addresses. If
DHCP or SLAAC was used
to autoconfigure the network interface, the Resolver
Configuration
values may already be filled in.
Otherwise, enter the local network's domain name in the
Search
field. DNS #1
and DNS #2
are the IPv4
and/or IPv6 addresses of the
DNS servers. At least one
DNS server is required.
The next menu asks if the system clock uses UTC or local time. When in doubt, select
to choose the more commonly-used local time.The next series of menus are used to determine the correct local time by selecting the geographic region, country, and time zone. Setting the time zone allows the system to automatically correct for regional time changes, such as daylight savings time, and perform other time zone related functions properly.
The example shown here is for a machine located in the Eastern time zone of the United States. The selections will vary according to the geographical location.
The appropriate region is selected using the arrow keys and then pressing Enter.
Select the appropriate country using the arrow keys and press Enter.
The appropriate time zone is selected using the arrow keys and pressing Enter.
Confirm the abbreviation for the time zone is correct. If it is, press Enter to continue with the post-installation configuration.
The next menu is used to configure which system services will be started whenever the system boots. All of these services are optional. Only start the services that are needed for the system to function.
Here is a summary of the services which can be enabled in this menu:
sshd
- The Secure Shell
(SSH) daemon is used to remotely access
a system over an encrypted connection. Only enable this
service if the system should be available for remote
logins.
moused
- Enable this service if the
mouse will be used from the command-line system
console.
ntpd
- The Network Time Protocol
(NTP) daemon for automatic clock
synchronization. Enable this service if there is a
Windows®, Kerberos, or LDAP server on
the network.
powerd
- System power control
utility for power control and energy saving.
The next menu is used to configure whether or not crash dumps should be enabled. Enabling crash dumps can be useful in debugging issues with the system, so users are encouraged to enable crash dumps.
The next menu prompts to create at least one user account.
It is recommended to login to the system using a user account
rather than as root
.
When logged in as root
, there are essentially no
limits or protection on what can be done. Logging in as a
normal user is safer and more secure.
Select
to add new users.Follow the prompts and input the requested information for
the user account. The example shown in Figure 2.49, “Enter User Information” creates the asample
user account.
Here is a summary of the information to input:
Username
- The name the user will
enter to log in. A common convention is to use the first
letter of the first name combined with the last name, as
long as each username is unique for the system. The
username is case sensitive and should not contain any
spaces.
Full name
- The user's full name.
This can contain spaces and is used as a description for
the user account.
Uid
- User ID.
Typically, this is left blank so the system will assign a
value.
Login group
- The user's group.
Typically this is left blank to accept the default.
Invite
- Additional groups to which the
user will be added as a member. If the user needs
administrative access, type user
into
other groups?wheel
here.
Login class
- Typically left blank
for the default.
Shell
- Type in one of the listed
values to set the interactive shell for the user. Refer
to Section 3.9, “Shells” for more information about
shells.
Home directory
- The user's home
directory. The default is usually correct.
Home directory permissions
-
Permissions on the user's home directory. The default is
usually correct.
Use password-based authentication?
- Typically yes
so that the user is
prompted to input their password at login.
Use an empty password?
-
Typically no
as it is insecure to have
a blank password.
Use a random password?
- Typically
no
so that the user can set their own
password in the next prompt.
Enter password
- The password for
this user. Characters typed will not show on the
screen.
Enter password again
- The password
must be typed again for verification.
Lock out the account after
creation?
- Typically no
so
that the user can login.
After entering everything, a summary is shown for review.
If a mistake was made, enter no
and try
again. If everything is correct, enter yes
to create the new user.
If there are more users to add, answer the Add
another user?
question with
yes
. Enter no
to finish
adding users and continue the installation.
For more information on adding users and user management, see Section 3.3, “Users and Basic Account Management”.
After everything has been installed and configured, a final chance is provided to modify settings.
Use this menu to make any changes or do any additional configuration before completing the installation.
Add User
- Described in Section 2.8.6, “Add Users”.
Root Password
- Described in Section 2.8.1, “Setting the
root
Password”.
Hostname
- Described in Section 2.5.2, “Setting the Hostname”.
Network
- Described in Section 2.8.2, “Configuring Network Interfaces”.
Services
- Described in Section 2.8.4, “Enabling Services”.
Time Zone
- Described in Section 2.8.3, “Setting the Time Zone”.
Handbook
- Download and install the
FreeBSD Handbook.
After any final configuration is complete, select
.bsdinstall will prompt if there are any additional configuration that needs to be done before rebooting into the new system. Select to exit to a shell within the new system or to proceed to the last step of the installation.
If further configuration or special setup is needed, select
to boot the install media into Live CD mode.If the installation is complete, select
to reboot the computer and start the new FreeBSD system. Do not forget to remove the FreeBSD install media or the computer may boot from it again.As FreeBSD boots, informational messages are displayed.
After the system finishes booting, a login prompt is
displayed. At the login:
prompt, enter the
username added during the installation. Avoid logging in as
root
. Refer to
Section 3.3.1.3, “The Superuser Account” for instructions on how to
become the superuser when administrative access is
needed.
The messages that appeared during boot can be reviewed by
pressing Scroll-Lock to turn on the
scroll-back buffer. The PgUp,
PgDn, and arrow keys can be used to scroll
back through the messages. When finished, press
Scroll-Lock again to unlock the display and
return to the console. To review these messages once the
system has been up for some time, type less
/var/run/dmesg.boot
from a command prompt. Press
q to return to the command line after
viewing.
If sshd was enabled in Figure 2.46, “Selecting Additional Services to Enable”, the first boot may be a bit slower as the system will generate the RSA and DSA keys. Subsequent boots will be faster. The fingerprints of the keys will be displayed, as seen in this example:
Generating public/private rsa1 key pair. Your identification has been saved in /etc/ssh/ssh_host_key. Your public key has been saved in /etc/ssh/ssh_host_key.pub. The key fingerprint is: 10:a0:f5:af:93:ae:a3:1a:b2:bb:3c:35:d9:5a:b3:f3 root@machine3.example.com The key's randomart image is: +--[RSA1 1024]----+ | o.. | | o . . | | . o | | o | | o S | | + + o | |o . + * | |o+ ..+ . | |==o..o+E | +-----------------+ Generating public/private dsa key pair. Your identification has been saved in /etc/ssh/ssh_host_dsa_key. Your public key has been saved in /etc/ssh/ssh_host_dsa_key.pub. The key fingerprint is: 7e:1c:ce:dc:8a:3a:18:13:5b:34:b5:cf:d9:d1:47:b2 root@machine3.example.com The key's randomart image is: +--[ DSA 1024]----+ | .. . .| | o . . + | | . .. . E .| | . . o o . . | | + S = . | | + . = o | | + . * . | | . . o . | | .o. . | +-----------------+ Starting sshd.
Refer to Section 13.8, “OpenSSH” for more information about fingerprints and SSH.
FreeBSD does not install a graphical environment by default. Refer to Chapter 5, The X Window System for more information about installing and configuring a graphical window manager.
Proper shutdown of a FreeBSD computer helps protect data and
hardware from damage. Do not turn off the power
before the system has been properly shut down! If
the user is a member of the wheel
group, become the
superuser by typing su
at the command line
and entering the root
password. Then, type
shutdown -p now
and the system will shut
down cleanly, and if the hardware supports it, turn itself
off.
This section covers basic installation troubleshooting, such as common problems people have reported.
Check the Hardware Notes (https://www.freebsd.org/releases/index.html)
document for the version of FreeBSD to make sure the hardware is
supported. If the hardware is supported and lock-ups or other
problems occur, build a custom kernel using the instructions in
Chapter 8, Configuring the FreeBSD Kernel to add support for devices which
are not present in the GENERIC
kernel. The
default kernel assumes that most hardware devices are in their
factory default configuration in terms of
IRQs, I/O addresses, and
DMA channels. If the hardware has been
reconfigured, a custom kernel configuration file can tell FreeBSD
where to find things.
Some installation problems can be avoided or alleviated by updating the firmware on various hardware components, most notably the motherboard. Motherboard firmware is usually referred to as the BIOS. Most motherboard and computer manufacturers have a website for upgrades and upgrade information.
Manufacturers generally advise against upgrading the motherboard BIOS unless there is a good reason for doing so, like a critical update. The upgrade process can go wrong, leaving the BIOS incomplete and the computer inoperative.
If the system hangs while probing hardware during boot, or
it behaves strangely during install, ACPI may
be the culprit. FreeBSD makes extensive use of the system
ACPI service on the i386,
amd64, and ia64 platforms to aid in system configuration
if it is detected during boot. Unfortunately, some bugs still
exist in both the ACPI driver and within
system motherboards and BIOS firmware.
ACPI can be disabled by setting the
hint.acpi.0.disabled
hint in the third stage
boot loader:
set hint.acpi.0.disabled="1"
This is reset each time the system is booted, so it is
necessary to add hint.acpi.0.disabled="1"
to
the file /boot/loader.conf
. More
information about the boot loader can be found in Section 12.1, “Synopsis”.
The welcome menu of bsdinstall, shown in Figure 2.3, “Welcome Menu”, provides a option. This is useful for those who are still wondering whether FreeBSD is the right operating system for them and want to test some of the features before installing.
The following points should be noted before using the
:To gain access to the system, authentication is
required. The username is root
and the password is
blank.
As the system runs directly from the installation media, performance will be significantly slower than that of a system installed on a hard disk.
This option only provides a command prompt and not a graphical interface.
This chapter covers the basic commands and functionality of the FreeBSD operating system. Much of this material is relevant for any UNIX®-like operating system. New FreeBSD users are encouraged to read through this chapter carefully.
After reading this chapter, you will know:
How to use and configure virtual consoles.
How to create and manage users and groups on FreeBSD.
How UNIX® file permissions and FreeBSD file flags work.
The default FreeBSD file system layout.
The FreeBSD disk organization.
How to mount and unmount file systems.
What processes, daemons, and signals are.
What a shell is, and how to change the default login environment.
How to use basic text editors.
What devices and device nodes are.
How to read manual pages for more information.
Unless FreeBSD has been configured to automatically start a graphical environment during startup, the system will boot into a command line login prompt, as seen in this example:
FreeBSD/amd64 (pc3.example.org) (ttyv0) login:
The first line contains some information about the system.
The amd64
indicates that the system in this
example is running a 64-bit version of FreeBSD. The hostname is
pc3.example.org
, and
ttyv0
indicates that this is the
“system console”. The second line is the login
prompt.
Since FreeBSD is a multiuser system, it needs some way to distinguish between different users. This is accomplished by requiring every user to log into the system before gaining access to the programs on the system. Every user has a unique name “username” and a personal “password”.
To log into the system console, type the username that was configured during system installation, as described in Section 2.8.6, “Add Users”, and press Enter. Then enter the password associated with the username and press Enter. The password is not echoed for security reasons.
Once the correct password is input, the message of the
day (MOTD) will be displayed followed
by a command prompt. Depending upon the shell that was
selected when the user was created, this prompt will be a
#
, $
, or
%
character. The prompt indicates that
the user is now logged into the FreeBSD system console and ready
to try the available commands.
While the system console can be used to interact with the system, a user working from the command line at the keyboard of a FreeBSD system will typically instead log into a virtual console. This is because system messages are configured by default to display on the system console. These messages will appear over the command or file that the user is working on, making it difficult to concentrate on the work at hand.
By default, FreeBSD is configured to provide several virtual consoles for inputting commands. Each virtual console has its own login prompt and shell and it is easy to switch between virtual consoles. This essentially provides the command line equivalent of having several windows open at the same time in a graphical environment.
The key combinations
Alt+F1
through
Alt+F8
have been reserved by FreeBSD for switching between virtual
consoles. Use
Alt+F1
to switch to the system console
(ttyv0
),
Alt+F2
to access the first virtual console
(ttyv1
),
Alt+F3
to access the second virtual console
(ttyv2
), and so on.
When using Xorg as a graphical
console, the combination becomes Ctrl+Alt+F1 to return to a text-based virtual console.
When switching from one console to the next, FreeBSD manages the screen output. The result is an illusion of having multiple virtual screens and keyboards that can be used to type commands for FreeBSD to run. The programs that are launched in one virtual console do not stop running when the user switches to a different virtual console.
Refer to kbdcontrol(1), vidcontrol(1), atkbd(4), syscons(4), and vt(4) for a more technical description of the FreeBSD console and its keyboard drivers.
In FreeBSD, the number of available virtual consoles is
configured in this section of
/etc/ttys
:
# name getty type status comments # ttyv0 "/usr/libexec/getty Pc" xterm on secure # Virtual terminals ttyv1 "/usr/libexec/getty Pc" xterm on secure ttyv2 "/usr/libexec/getty Pc" xterm on secure ttyv3 "/usr/libexec/getty Pc" xterm on secure ttyv4 "/usr/libexec/getty Pc" xterm on secure ttyv5 "/usr/libexec/getty Pc" xterm on secure ttyv6 "/usr/libexec/getty Pc" xterm on secure ttyv7 "/usr/libexec/getty Pc" xterm on secure ttyv8 "/usr/X11R6/bin/xdm -nodaemon" xterm off secure
To disable a virtual console, put a comment symbol
(#
) at the beginning of the line
representing that virtual console. For example, to reduce the
number of available virtual consoles from eight to four, put a
#
in front of the last four lines
representing virtual consoles ttyv5
through ttyv8
.
Do not comment out the line for the
system console ttyv0
. Note that the last
virtual console (ttyv8
) is used to access
the graphical environment if Xorg
has been installed and configured as described in
Chapter 5, The X Window System.
For a detailed description of every column in this file and the available options for the virtual consoles, refer to ttys(5).
The FreeBSD boot menu provides an option labelled as
“Boot Single User”. If this option is selected,
the system will boot into a special mode known as
“single user mode”. This mode is typically used
to repair a system that will not boot or to reset the
root
password when
it is not known. While in single user mode, networking and
other virtual consoles are not available. However, full
root
access to the
system is available, and by default, the
root
password is not
needed. For these reasons, physical access to the keyboard is
needed to boot into this mode and determining who has physical
access to the keyboard is something to consider when securing
a FreeBSD system.
The settings which control single user mode are found in
this section of /etc/ttys
:
# name getty type status comments # # If console is marked "insecure", then init will ask for the root password # when going to single-user mode. console none unknown off secure
By default, the status is set to
secure
. This assumes that who has physical
access to the keyboard is either not important or it is
controlled by a physical security policy. If this setting is
changed to insecure
, the assumption is that
the environment itself is insecure because anyone can access
the keyboard. When this line is changed to
insecure
, FreeBSD will prompt for the
root
password when a
user selects to boot into single user mode.
Be careful when changing this setting to
insecure
! If the
root
password is
forgotten, booting into single user mode is still possible,
but may be difficult for someone who is not familiar with
the FreeBSD booting process.
The FreeBSD console default video mode may be adjusted to
1024x768, 1280x1024, or any other size supported by the
graphics chip and monitor. To use a different video mode
load the VESA
module:
#
kldload vesa
To determine which video modes are supported by the hardware, use vidcontrol(1). To get a list of supported video modes issue the following:
#
vidcontrol -i mode
The output of this command lists the video modes that are
supported by the hardware. To select a new video mode,
specify the mode using vidcontrol(1) as the
root
user:
#
vidcontrol MODE_279
If the new video mode is acceptable, it can be permanently
set on boot by adding it to
/etc/rc.conf
:
allscreens_flags="MODE_279"
FreeBSD allows multiple users to use the computer at the same time. While only one user can sit in front of the screen and use the keyboard at any one time, any number of users can log in to the system through the network. To use the system, each user should have their own user account.
This chapter describes:
The different types of user accounts on a FreeBSD system.
How to add, remove, and modify user accounts.
How to set limits to control the resources that users and groups are allowed to access.
How to create groups and add users as members of a group.
Since all access to the FreeBSD system is achieved using accounts and all processes are run by users, user and account management is important.
There are three main types of accounts: system accounts, user accounts, and the superuser account.
System accounts are used to run services such as DNS, mail, and web servers. The reason for this is security; if all services ran as the superuser, they could act without restriction.
Examples of system accounts are
daemon
,
operator
,
bind
,
news
, and
www
.
nobody
is the
generic unprivileged system account. However, the more
services that use
nobody
, the more
files and processes that user will become associated with,
and hence the more privileged that user becomes.
User accounts are assigned to real people and are used to log in and use the system. Every person accessing the system should have a unique user account. This allows the administrator to find out who is doing what and prevents users from clobbering the settings of other users.
Each user can set up their own environment to accommodate their use of the system, by configuring their default shell, editor, key bindings, and language settings.
Every user account on a FreeBSD system has certain information associated with it:
The user name is typed at the
login:
prompt. Each user must have
a unique user name. There are a number of rules for
creating valid user names which are documented in
passwd(5). It is recommended to use user names
that consist of eight or fewer, all lower case
characters in order to maintain backwards
compatibility with applications.
Each account has an associated password.
The User ID (UID) is a number used to uniquely identify the user to the FreeBSD system. Commands that allow a user name to be specified will first convert it to the UID. It is recommended to use a UID less than 65535, since higher values may cause compatibility issues with some software.
The Group ID (GID) is a number used to uniquely identify the primary group that the user belongs to. Groups are a mechanism for controlling access to resources based on a user's GID rather than their UID. This can significantly reduce the size of some configuration files and allows users to be members of more than one group. It is recommended to use a GID of 65535 or lower as higher GIDs may break some software.
Login classes are an extension to the group mechanism that provide additional flexibility when tailoring the system to different users. Login classes are discussed further in Section 13.13.1, “Configuring Login Classes”.
By default, passwords do not expire. However, password expiration can be enabled on a per-user basis, forcing some or all users to change their passwords after a certain amount of time has elapsed.
By default, FreeBSD does not expire accounts. When creating accounts that need a limited lifespan, such as student accounts in a school, specify the account expiry date using pw(8). After the expiry time has elapsed, the account cannot be used to log in to the system, although the account's directories and files will remain.
The user name uniquely identifies the account to FreeBSD, but does not necessarily reflect the user's real name. Similar to a comment, this information can contain spaces, uppercase characters, and be more than 8 characters long.
The home directory is the full path to a directory
on the system. This is the user's starting directory
when the user logs in. A common convention is to put
all user home directories under
or /home/username
.
Each user stores their personal files and
subdirectories in their own home directory./usr/home/username
The shell provides the user's default environment for interacting with the system. There are many different kinds of shells and experienced users will have their own preferences, which can be reflected in their account settings.
The superuser account, usually called
root
, is used to
manage the system with no limitations on privileges. For
this reason, it should not be used for day-to-day tasks like
sending and receiving mail, general exploration of the
system, or programming.
The superuser, unlike other user accounts, can operate without limits, and misuse of the superuser account may result in spectacular disasters. User accounts are unable to destroy the operating system by mistake, so it is recommended to login as a user account and to only become the superuser when a command requires extra privilege.
Always double and triple-check any commands issued as the superuser, since an extra space or missing character can mean irreparable data loss.
There are several ways to gain superuser privilege.
While one can log in as
root
, this is
highly discouraged.
Instead, use su(1) to become the superuser. If
-
is specified when running this command,
the user will also inherit the root user's environment. The
user running this command must be in the
wheel
group or
else the command will fail. The user must also know the
password for the
root
user
account.
In this example, the user only becomes superuser in
order to run make install
as this step
requires superuser privilege. Once the command completes,
the user types exit
to leave the
superuser account and return to the privilege of their user
account.
%
configure
%
make
%
su -
Password:#
make install
#
exit
%
The built-in su(1) framework works well for single systems or small networks with just one system administrator. An alternative is to install the security/sudo package or port. This software provides activity logging and allows the administrator to configure which users can run which commands as the superuser.
FreeBSD provides a variety of different commands to manage user accounts. The most common commands are summarized in Table 3.1, “Utilities for Managing User Accounts”, followed by some examples of their usage. See the manual page for each utility for more details and usage examples.
Command | Summary |
---|---|
adduser(8) | The recommended command-line application for adding new users. |
rmuser(8) | The recommended command-line application for removing users. |
chpass(1) | A flexible tool for changing user database information. |
passwd(1) | The command-line tool to change user passwords. |
pw(8) | A powerful and flexible tool for modifying all aspects of user accounts. |
The recommended program for adding new users is
adduser(8). When a new user is added, this program
automatically updates /etc/passwd
and
/etc/group
. It also creates a home
directory for the new user, copies in the default
configuration files from
/usr/share/skel
, and can optionally
mail the new user a welcome message. This utility must be
run as the superuser.
The adduser(8) utility is interactive and walks
through the steps for creating a new user account. As seen
in Example 3.2, “Adding a User on FreeBSD”, either input
the required information or press Return
to accept the default value shown in square brackets.
In this example, the user has been invited into the
wheel
group,
allowing them to become the superuser with su(1).
When finished, the utility will prompt to either
create another user or to exit.
#
adduser
Username:jru
Full name:J. Random User
Uid (Leave empty for default): Login group [jru]: Login group is jru. Invite jru into other groups? []:wheel
Login class [default]: Shell (sh csh tcsh zsh nologin) [sh]:zsh
Home directory [/home/jru]: Home directory permissions (Leave empty for default): Use password-based authentication? [yes]: Use an empty password? (yes/no) [no]: Use a random password? (yes/no) [no]: Enter password: Enter password again: Lock out the account after creation? [no]: Username : jru Password : **** Full Name : J. Random User Uid : 1001 Class : Groups : jru wheel Home : /home/jru Shell : /usr/local/bin/zsh Locked : no OK? (yes/no):yes
adduser: INFO: Successfully added (jru) to the user database. Add another user? (yes/no):no
Goodbye!#
Since the password is not echoed when typed, be careful to not mistype the password when creating the user account.
To completely remove a user from the system, run rmuser(8) as the superuser. This command performs the following steps:
Removes the user's crontab(1) entry, if one exists.
Removes any at(1) jobs belonging to the user.
Kills all processes owned by the user.
Removes the user from the system's local password file.
Optionally removes the user's home directory, if it is owned by the user.
Removes the incoming mail files belonging to the
user from /var/mail
.
Removes all files owned by the user from temporary
file storage areas such as
/tmp
.
Finally, removes the username from all groups to
which it belongs in /etc/group
. If
a group becomes empty and the group name is the same as
the username, the group is removed. This complements
the per-user unique groups created by
adduser(8).
rmuser(8) cannot be used to remove superuser accounts since that is almost always an indication of massive destruction.
By default, an interactive mode is used, as shown in the following example.
rmuser
Interactive Account
Removal#
rmuser jru
Matching password entry: jru:*:1001:1001::0:0:J. Random User:/home/jru:/usr/local/bin/zsh Is this the entry you wish to remove?y
Remove user's home directory (/home/jru)?y
Removing user (jru): mailspool home passwd.#
Any user can use chpass(1) to change their default shell and personal information associated with their user account. The superuser can use this utility to change additional account information for any user.
When passed no options, aside from an optional username, chpass(1) displays an editor containing user information. When the user exits from the editor, the user database is updated with the new information.
This utility will prompt for the user's password when exiting the editor, unless the utility is run as the superuser.
In Example 3.4, “Using chpass
as
Superuser”, the
superuser has typed chpass jru
and is
now viewing the fields that can be changed for this user.
If jru
runs this
command instead, only the last six fields will be displayed
and available for editing. This is shown in
Example 3.5, “Using chpass
as Regular
User”.
chpass
as
Superuser#Changing user database information for jru. Login: jru Password: * Uid [#]: 1001 Gid [# or name]: 1001 Change [month day year]: Expire [month day year]: Class: Home directory: /home/jru Shell: /usr/local/bin/zsh Full Name: J. Random User Office Location: Office Phone: Home Phone: Other information:
chpass
as Regular
User#Changing user database information for jru. Shell: /usr/local/bin/zsh Full Name: J. Random User Office Location: Office Phone: Home Phone: Other information:
The commands chfn(1) and chsh(1) are links
to chpass(1), as are ypchpass(1),
ypchfn(1), and ypchsh(1). Since
NIS support is automatic, specifying
the yp
before the command is not
necessary. How to configure NIS is covered in Chapter 29, Network Servers.
Any user can easily change their password using passwd(1). To prevent accidental or unauthorized changes, this command will prompt for the user's original password before a new password can be set:
%
passwd
Changing local password for jru. Old password: New password: Retype new password: passwd: updating the database... passwd: done
The superuser can change any user's password by specifying the username when running passwd(1). When this utility is run as the superuser, it will not prompt for the user's current password. This allows the password to be changed when a user cannot remember the original password.
#
passwd jru
Changing local password for jru. New password: Retype new password: passwd: updating the database... passwd: done
As with chpass(1), yppasswd(1) is a link to passwd(1), so NIS works with either command.
The pw(8) utility can create, remove, modify, and display users and groups. It functions as a front end to the system user and group files. pw(8) has a very powerful set of command line options that make it suitable for use in shell scripts, but new users may find it more complicated than the other commands presented in this section.
A group is a list of users. A group is identified by its group name and GID. In FreeBSD, the kernel uses the UID of a process, and the list of groups it belongs to, to determine what the process is allowed to do. Most of the time, the GID of a user or process usually means the first group in the list.
The group name to GID mapping is listed
in /etc/group
. This is a plain text file
with four colon-delimited fields. The first field is the
group name, the second is the encrypted password, the third
the GID, and the fourth the comma-delimited
list of members. For a more complete description of the
syntax, refer to group(5).
The superuser can modify /etc/group
using a text editor. Alternatively, pw(8) can be used to
add and edit groups. For example, to add a group called
teamtwo
and then
confirm that it exists:
In this example, 1100
is the
GID of
teamtwo
. Right
now, teamtwo
has no
members. This command will add
jru
as a member of
teamtwo
.
#
pw groupmod teamtwo -M jru
#
pw groupshow teamtwo
teamtwo:*:1100:jru
The argument to -M
is a comma-delimited
list of users to be added to a new (empty) group or to replace
the members of an existing group. To the user, this group
membership is different from (and in addition to) the user's
primary group listed in the password file. This means that
the user will not show up as a member when using
groupshow
with pw(8), but will show up
when the information is queried via id(1) or a similar
tool. When pw(8) is used to add a user to a group, it
only manipulates /etc/group
and does not
attempt to read additional data from
/etc/passwd
.
#
pw groupmod teamtwo -m db
#
pw groupshow teamtwo
teamtwo:*:1100:jru,db
In this example, the argument to -m
is a
comma-delimited list of users who are to be added to the
group. Unlike the previous example, these users are appended
to the group and do not replace existing users in the
group.
%
id jru
uid=1001(jru) gid=1001(jru) groups=1001(jru), 1100(teamtwo)
In this example,
jru
is a member of
the groups jru
and
teamtwo
.
For more information about this command and the format of
/etc/group
, refer to pw(8) and
group(5).
In FreeBSD, every file and directory has an associated set of permissions and several utilities are available for viewing and modifying these permissions. Understanding how permissions work is necessary to make sure that users are able to access the files that they need and are unable to improperly access the files used by the operating system or owned by other users.
This section discusses the traditional UNIX® permissions used in FreeBSD. For finer grained file system access control, refer to Section 13.9, “Access Control Lists”.
In UNIX®, basic permissions are assigned using
three types of access: read, write, and execute. These access
types are used to determine file access to the file's owner,
group, and others (everyone else). The read, write, and execute
permissions can be represented as the letters
r
, w
, and
x
. They can also be represented as binary
numbers as each permission is either on or off
(0
). When represented as a number, the
order is always read as rwx
, where
r
has an on value of 4
,
w
has an on value of 2
and x
has an on value of
1
.
Table 4.1 summarizes the possible numeric and alphabetic
possibilities. When reading the “Directory
Listing” column, a -
is used to
represent a permission that is set to off.
Value | Permission | Directory Listing |
---|---|---|
0 | No read, no write, no execute | --- |
1 | No read, no write, execute | --x |
2 | No read, write, no execute | -w- |
3 | No read, write, execute | -wx |
4 | Read, no write, no execute | r-- |
5 | Read, no write, execute | r-x |
6 | Read, write, no execute | rw- |
7 | Read, write, execute | rwx |
Use the -l
argument to ls(1) to view a
long directory listing that includes a column of information
about a file's permissions for the owner, group, and everyone
else. For example, a ls -l
in an arbitrary
directory may show:
%
ls -l
total 530 -rw-r--r-- 1 root wheel 512 Sep 5 12:31 myfile -rw-r--r-- 1 root wheel 512 Sep 5 12:31 otherfile -rw-r--r-- 1 root wheel 7680 Sep 5 12:31 email.txt
The first (leftmost) character in the first column indicates
whether this file is a regular file, a directory, a special
character device, a socket, or any other special pseudo-file
device. In this example, the -
indicates a
regular file. The next three characters, rw-
in this example, give the permissions for the owner of the file.
The next three characters, r--
, give the
permissions for the group that the file belongs to. The final
three characters, r--
, give the permissions
for the rest of the world. A dash means that the permission is
turned off. In this example, the permissions are set so the
owner can read and write to the file, the group can read the
file, and the rest of the world can only read the file.
According to the table above, the permissions for this file
would be 644
, where each digit represents the
three parts of the file's permission.
How does the system control permissions on devices? FreeBSD
treats most hardware devices as a file that programs can open,
read, and write data to. These special device files are
stored in /dev/
.
Directories are also treated as files. They have read, write, and execute permissions. The executable bit for a directory has a slightly different meaning than that of files. When a directory is marked executable, it means it is possible to change into that directory using cd(1). This also means that it is possible to access the files within that directory, subject to the permissions on the files themselves.
In order to perform a directory listing, the read permission must be set on the directory. In order to delete a file that one knows the name of, it is necessary to have write and execute permissions to the directory containing the file.
There are more permission bits, but they are primarily used in special circumstances such as setuid binaries and sticky directories. For more information on file permissions and how to set them, refer to chmod(1).
Symbolic permissions use characters instead of octal values to assign permissions to files or directories. Symbolic permissions use the syntax of (who) (action) (permissions), where the following values are available:
Option | Letter | Represents |
---|---|---|
(who) | u | User |
(who) | g | Group owner |
(who) | o | Other |
(who) | a | All (“world”) |
(action) | + | Adding permissions |
(action) | - | Removing permissions |
(action) | = | Explicitly set permissions |
(permissions) | r | Read |
(permissions) | w | Write |
(permissions) | x | Execute |
(permissions) | t | Sticky bit |
(permissions) | s | Set UID or GID |
These values are used with chmod(1), but with
letters instead of numbers. For example, the following
command would block other users from accessing
FILE
:
%
chmod go= FILE
A comma separated list can be provided when more than one
set of changes to a file must be made. For example, the
following command removes the group and
“world” write permission on
FILE
, and adds the execute
permissions for everyone:
%
chmod go-w,a+x
FILE
In addition to file permissions, FreeBSD supports the use of
“file flags”. These flags add an additional
level of security and control over files, but not directories.
With file flags, even
root
can be
prevented from removing or altering files.
File flags are modified using chflags(1). For
example, to enable the system undeletable flag on the file
file1
, issue the following
command:
#
chflags sunlink file1
To disable the system undeletable flag, put a
“no” in front of the
sunlink
:
#
chflags nosunlink file1
To view the flags of a file, use -lo
with
ls(1):
#
ls -lo file1
-rw-r--r-- 1 trhodes trhodes sunlnk 0 Mar 1 05:54 file1
Several file flags may only be added or removed by the
root
user. In other
cases, the file owner may set its file flags. Refer to
chflags(1) and chflags(2) for more
information.
Other than the permissions already discussed, there are
three other specific settings that all administrators should
know about. They are the setuid
,
setgid
, and sticky
permissions.
These settings are important for some UNIX® operations as they provide functionality not normally granted to normal users. To understand them, the difference between the real user ID and effective user ID must be noted.
The real user ID is the UID who owns
or starts the process. The effective UID
is the user ID the process runs as. As an example,
passwd(1) runs with the real user ID when a user changes
their password. However, in order to update the password
database, the command runs as the effective ID of the
root
user. This
allows users to change their passwords without seeing a
Permission Denied error.
The setuid permission may be set by prefixing a permission set with the number four (4) as shown in the following example:
#
chmod 4755 suidexample.sh
The permissions on
now look like the following:suidexample.sh
-rwsr-xr-x 1 trhodes trhodes 63 Aug 29 06:36 suidexample.sh
Note that a s
is now part of the
permission set designated for the file owner, replacing the
executable bit. This allows utilities which need elevated
permissions, such as passwd(1).
The nosuid
mount(8) option will
cause such binaries to silently fail without alerting
the user. That option is not completely reliable as a
nosuid
wrapper may be able to circumvent
it.
To view this in real time, open two terminals. On
one, type passwd
as a normal user.
While it waits for a new password, check the process
table and look at the user information for
passwd(1):
In terminal A:
Changing local password for trhodes Old Password:
In terminal B:
#
ps aux | grep passwd
trhodes 5232 0.0 0.2 3420 1608 0 R+ 2:10AM 0:00.00 grep passwd root 5211 0.0 0.2 3620 1724 2 I+ 2:09AM 0:00.01 passwd
Although passwd(1) is run as a normal user, it is
using the effective UID of
root
.
The setgid
permission performs the
same function as the setuid
permission;
except that it alters the group settings. When an application
or utility executes with this setting, it will be granted the
permissions based on the group that owns the file, not the
user who started the process.
To set the setgid
permission on a
file, provide chmod(1) with a leading two (2):
#
chmod 2755 sgidexample.sh
In the following listing, notice that the
s
is now in the field designated for the
group permission settings:
-rwxr-sr-x 1 trhodes trhodes 44 Aug 31 01:49 sgidexample.sh
In these examples, even though the shell script in question is an executable file, it will not run with a different EUID or effective user ID. This is because shell scripts may not access the setuid(2) system calls.
The setuid
and
setgid
permission bits may lower system
security, by allowing for elevated permissions. The third
special permission, the sticky bit
, can
strengthen the security of a system.
When the sticky bit
is set on a
directory, it allows file deletion only by the file owner.
This is useful to prevent file deletion in public directories,
such as /tmp
, by users
who do not own the file. To utilize this permission, prefix
the permission set with a one (1):
#
chmod 1777 /tmp
The sticky bit
permission will display
as a t
at the very end of the permission
set:
#
ls -al / | grep tmp
drwxrwxrwt 10 root wheel 512 Aug 31 01:49 tmp
The FreeBSD directory hierarchy is fundamental to obtaining an overall understanding of the system. The most important directory is root or, “/”. This directory is the first one mounted at boot time and it contains the base system necessary to prepare the operating system for multi-user operation. The root directory also contains mount points for other file systems that are mounted during the transition to multi-user operation.
A mount point is a directory where additional file systems
can be grafted onto a parent file system (usually the root file
system). This is further described in
Section 3.6, “Disk Organization”. Standard mount points
include /usr/
, /var/
,
/tmp/
, /mnt/
, and
/cdrom/
. These directories are usually
referenced to entries in /etc/fstab
. This
file is a table of various file systems and mount points and is
read by the system. Most of the file systems in
/etc/fstab
are mounted automatically at
boot time from the script rc(8) unless their entry includes
noauto
. Details can be found in
Section 3.7.1, “The fstab
File”.
A complete description of the file system hierarchy is available in hier(7). The following table provides a brief overview of the most common directories.
Directory | Description |
---|---|
/ | Root directory of the file system. |
/bin/ | User utilities fundamental to both single-user and multi-user environments. |
/boot/ | Programs and configuration files used during operating system bootstrap. |
/boot/defaults/ | Default boot configuration files. Refer to loader.conf(5) for details. |
/dev/ | Device nodes. Refer to intro(4) for details. |
/etc/ | System configuration files and scripts. |
/etc/defaults/ | Default system configuration files. Refer to rc(8) for details. |
/etc/mail/ | Configuration files for mail transport agents such as sendmail(8). |
/etc/periodic/ | Scripts that run daily, weekly, and monthly, via cron(8). Refer to periodic(8) for details. |
/etc/ppp/ | ppp(8) configuration files. |
/mnt/ | Empty directory commonly used by system administrators as a temporary mount point. |
/proc/ | Process file system. Refer to procfs(5), mount_procfs(8) for details. |
/rescue/ | Statically linked programs for emergency recovery as described in rescue(8). |
/root/ | Home directory for the
root
account. |
/sbin/ | System programs and administration utilities fundamental to both single-user and multi-user environments. |
/tmp/ | Temporary files which are usually
not preserved across a system
reboot. A memory-based file system is often mounted
at /tmp . This can be automated
using the tmpmfs-related variables of rc.conf(5)
or with an entry in /etc/fstab ;
refer to mdmfs(8) for details. |
/usr/ | The majority of user utilities and applications. |
/usr/bin/ | Common utilities, programming tools, and applications. |
/usr/include/ | Standard C include files. |
/usr/lib/ | Archive libraries. |
/usr/libdata/ | Miscellaneous utility data files. |
/usr/libexec/ | System daemons and system utilities executed by other programs. |
/usr/local/ | Local executables and libraries. Also used as
the default destination for the FreeBSD ports framework.
Within
/usr/local , the
general layout sketched out by hier(7) for
/usr should be
used. Exceptions are the man directory, which is
directly under /usr/local rather than
under /usr/local/share , and
the ports documentation is in share/doc/ . |
/usr/obj/ | Architecture-specific target tree produced by
building the /usr/src
tree. |
/usr/ports/ | The FreeBSD Ports Collection (optional). |
/usr/sbin/ | System daemons and system utilities executed by users. |
/usr/share/ | Architecture-independent files. |
/usr/src/ | BSD and/or local source files. |
/var/ | Multi-purpose log, temporary, transient, and
spool files. A memory-based file system is sometimes
mounted at
/var . This can
be automated using the varmfs-related variables in
rc.conf(5) or with an entry in
/etc/fstab ; refer to
mdmfs(8) for details. |
/var/log/ | Miscellaneous system log files. |
/var/mail/ | User mailbox files. |
/var/spool/ | Miscellaneous printer and mail system spooling directories. |
/var/tmp/ | Temporary files which are usually preserved
across a system reboot, unless
/var is a
memory-based file system. |
/var/yp/ | NIS maps. |
The smallest unit of organization that FreeBSD uses to find
files is the filename. Filenames are case-sensitive, which
means that readme.txt
and
README.TXT
are two separate files. FreeBSD
does not use the extension of a file to determine whether the
file is a program, document, or some other form of data.
Files are stored in directories. A directory may contain no files, or it may contain many hundreds of files. A directory can also contain other directories, allowing a hierarchy of directories within one another in order to organize data.
Files and directories are referenced by giving the file or
directory name, followed by a forward slash,
/
, followed by any other directory names that
are necessary. For example, if the directory
foo
contains a directory
bar
which contains the
file readme.txt
, the full name, or
path, to the file is
foo/bar/readme.txt
. Note that this is
different from Windows® which uses \
to
separate file and directory names. FreeBSD does not use drive
letters, or other drive names in the path. For example, one
would not type c:\foo\bar\readme.txt
on
FreeBSD.
Directories and files are stored in a file system. Each
file system contains exactly one directory at the very top
level, called the root directory for that
file system. This root directory can contain other directories.
One file system is designated the
root file system or /
.
Every other file system is mounted under
the root file system. No matter how many disks are on the FreeBSD
system, every directory appears to be part of the same
disk.
Consider three file systems, called A
,
B
, and C
. Each file
system has one root directory, which contains two other
directories, called A1
, A2
(and likewise B1
, B2
and
C1
, C2
).
Call A
the root file system. If
ls(1) is used to view the contents of this directory,
it will show two subdirectories, A1
and
A2
. The directory tree looks like
this:
A file system must be mounted on to a directory in another
file system. When mounting file system B
on to the directory A1
, the root directory
of B
replaces A1
, and
the directories in B
appear
accordingly:
Any files that are in the B1
or
B2
directories can be reached with the path
/A1/B1
or
/A1/B2
as necessary. Any
files that were in /A1
have been temporarily hidden. They will reappear if
B
is unmounted from
A
.
If B
had been mounted on
A2
then the diagram would look like
this:
and the paths would be
/A2/B1
and
/A2/B2
respectively.
File systems can be mounted on top of one another.
Continuing the last example, the C
file
system could be mounted on top of the B1
directory in the B
file system, leading to
this arrangement:
Or C
could be mounted directly on to the
A
file system, under the
A1
directory:
It is entirely possible to have one large root file system, and not need to create any others. There are some drawbacks to this approach, and one advantage.
Different file systems can have different
mount options. For example, the root
file system can be mounted read-only, making it impossible
for users to inadvertently delete or edit a critical file.
Separating user-writable file systems, such as
/home
, from other
file systems allows them to be mounted
nosuid. This option prevents the
suid/guid bits
on executables stored on the file system from taking effect,
possibly improving security.
FreeBSD automatically optimizes the layout of files on a file system, depending on how the file system is being used. So a file system that contains many small files that are written frequently will have a different optimization to one that contains fewer, larger files. By having one big file system this optimization breaks down.
FreeBSD's file systems are robust if power is lost. However, a power loss at a critical point could still damage the structure of the file system. By splitting data over multiple file systems it is more likely that the system will still come up, making it easier to restore from backup as necessary.
File systems are a fixed size. If you create a file system when you install FreeBSD and give it a specific size, you may later discover that you need to make the partition bigger. This is not easily accomplished without backing up, recreating the file system with the new size, and then restoring the backed up data.
FreeBSD features the growfs(8) command, which makes it possible to increase the size of file system on the fly, removing this limitation.
File systems are contained in partitions. This does not
have the same meaning as the common usage of the term partition
(for example, MS-DOS® partition), because of FreeBSD's UNIX®
heritage. Each partition is identified by a letter from
a
through to h
. Each
partition can contain only one file system, which means that
file systems are often described by either their typical mount
point in the file system hierarchy, or the letter of the
partition they are contained in.
FreeBSD also uses disk space for swap space to provide virtual memory. This allows your computer to behave as though it has much more memory than it actually does. When FreeBSD runs out of memory, it moves some of the data that is not currently being used to the swap space, and moves it back in (moving something else out) when it needs it.
Some partitions have certain conventions associated with them.
Partition | Convention |
---|---|
a | Normally contains the root file system. |
b | Normally contains swap space. |
c | Normally the same size as the enclosing slice.
This allows utilities that need to work on the entire
slice, such as a bad block scanner, to work on the
c partition. A file system would not
normally be created on this partition. |
d | Partition d used to have a
special meaning associated with it, although that is now
gone and d may work as any normal
partition. |
Disks in FreeBSD are divided into slices, referred to in Windows® as partitions, which are numbered from 1 to 4. These are then divided into partitions, which contain file systems, and are labeled using letters.
Slice numbers follow the device name, prefixed with an
s
, starting at 1. So
“da0s1” is the first slice on
the first SCSI drive. There can only be four physical slices on
a disk, but there can be logical slices inside physical slices
of the appropriate type. These extended slices are numbered
starting at 5, so “ada0s5” is
the first extended slice on the first SATA disk. These devices
are used by file systems that expect to occupy a slice.
Slices, “dangerously dedicated” physical
drives, and other drives contain
partitions, which are represented as
letters from a
to h
. This
letter is appended to the device name, so
“da0a” is the
a
partition on the first
da
drive, which is
“dangerously dedicated”.
“ada1s3e” is the fifth
partition in the third slice of the second SATA disk
drive.
Finally, each disk on the system is identified. A disk name starts with a code that indicates the type of disk, and then a number, indicating which disk it is. Unlike slices, disk numbering starts at 0. Common codes are listed in Table 3.3, “Disk Device Names”.
When referring to a partition, include the disk name,
s
, the slice number, and then the partition
letter. Examples are shown in
Example 3.12, “Sample Disk, Slice, and Partition Names”.
Example 3.13, “Conceptual Model of a Disk” shows a conceptual model of a disk layout.
When installing FreeBSD, configure the disk slices, create partitions within the slice to be used for FreeBSD, create a file system or swap space in each partition, and decide where each file system will be mounted.
Drive Type | Drive Device Name |
---|---|
SATA and IDE hard drives | ada or
ad |
SCSI hard drives and USB storage devices | da |
SATA and IDE CD-ROM drives | cd or
acd |
SCSI CD-ROM drives | cd |
Floppy drives | fd |
Assorted non-standard CD-ROM drives | mcd for Mitsumi
CD-ROM and scd for
Sony CD-ROM devices |
SCSI tape drives | sa |
IDE tape drives | ast |
RAID drives | Examples include aacd for
Adaptec® AdvancedRAID, mlxd and
mlyd for Mylex®,
amrd for AMI MegaRAID®,
idad for Compaq Smart RAID,
twed for 3ware® RAID. |
Name | Meaning |
---|---|
ada0s1a | The first partition (a ) on the
first slice (s1 ) on the first
SATA
disk (ada0 ). |
da1s2e | The fifth partition (e ) on the
second slice (s2 ) on the second
SCSI disk (da1 ). |
This diagram shows FreeBSD's view of the first
SATA disk attached to the system. Assume
that the disk is 250 GB in size, and contains an
80 GB slice and a 170 GB slice (MS-DOS®
partitions). The first slice contains a Windows®
NTFS file system, C:
,
and the second slice contains a FreeBSD installation. This
example FreeBSD installation has four data partitions and a swap
partition.
The four partitions each hold a file system. Partition
a
is used for the root file system,
d
for /var/
,
e
for /tmp/
, and
f
for /usr/
.
Partition letter c
refers to the entire
slice, and so is not used for ordinary partitions.
The file system is best visualized as a tree, rooted, as it
were, at /
.
/dev
,
/usr
, and the other
directories in the root directory are branches, which may have
their own branches, such as
/usr/local
, and so
on.
There are various reasons to house some of these
directories on separate file systems.
/var
contains the
directories log/
,
spool/
, and various types
of temporary files, and as such, may get filled up. Filling up
the root file system is not a good idea, so splitting
/var
from
/
is often
favorable.
Another common reason to contain certain directory trees on other file systems is if they are to be housed on separate physical disks, or are separate virtual disks, such as Network File System mounts, described in Section 29.3, “Network File System (NFS)”, or CDROM drives.
During the boot process (Chapter 12, The FreeBSD Booting Process), file
systems listed in /etc/fstab
are
automatically mounted except for the entries containing
noauto
. This file contains entries in the
following format:
device
/mount-point
fstype
options
dumpfreq
passno
device
An existing device name as explained in Table 3.3, “Disk Device Names”.
mount-point
An existing directory on which to mount the file system.
fstype
The file system type to pass to mount(8). The
default FreeBSD file system is
ufs
.
options
Either rw
for read-write file
systems, or ro
for read-only file
systems, followed by any other options that may be
needed. A common option is noauto
for
file systems not normally mounted during the boot
sequence. Other options are listed in
mount(8).
dumpfreq
Used by dump(8) to determine which file systems require dumping. If the field is missing, a value of zero is assumed.
passno
Determines the order in which file systems should be
checked. File systems that should be skipped should
have their passno
set to zero. The
root file system needs to be checked before everything
else and should have its passno
set
to one. The other file systems should be set to
values greater than one. If more than one file system
has the same passno
, fsck(8)
will attempt to check file systems in parallel if
possible.
Refer to fstab(5) for more information on the format
of /etc/fstab
and its options.
File systems are mounted using mount(8). The most basic syntax is as follows:
#
mount
device
mountpoint
This command provides many options which are described in mount(8), The most commonly used options include:
-a
Mount all the file systems listed in
/etc/fstab
, except those marked as
“noauto”, excluded by the
-t
flag, or those that are already
mounted.
-d
Do everything except for the actual mount system
call. This option is useful in conjunction with the
-v
flag to determine what mount(8)
is actually trying to do.
-f
Force the mount of an unclean file system (dangerous), or the revocation of write access when downgrading a file system's mount status from read-write to read-only.
-r
Mount the file system read-only. This is identical
to using -o ro
.
-t
fstype
Mount the specified file system type or mount only
file systems of the given type, if -a
is included. “ufs” is the default file
system type.
-u
Update mount options on the file system.
-v
Be verbose.
-w
Mount the file system read-write.
The following options can be passed to -o
as a comma-separated list:
Do not interpret setuid or setgid flags on the file system. This is also a useful security option.
To unmount a file system use umount(8). This command
takes one parameter which can be a mountpoint, device name,
-a
or -A
.
All forms take -f
to force unmounting,
and -v
for verbosity. Be warned that
-f
is not generally a good idea as it might
crash the computer or damage data on the file system.
To unmount all mounted file systems, or just the file
system types listed after -t
, use
-a
or -A
. Note that
-A
does not attempt to unmount the root file
system.
FreeBSD is a multi-tasking operating system. Each program running at any one time is called a process. Every running command starts at least one new process and there are a number of system processes that are run by FreeBSD.
Each process is uniquely identified by a number called a
process ID (PID).
Similar to files, each process has one owner and group, and
the owner and group permissions are used to determine which
files and devices the process can open. Most processes also
have a parent process that started them. For example, the
shell is a process, and any command started in the shell is a
process which has the shell as its parent process. The
exception is a special process called init(8) which is
always the first process to start at boot time and which always
has a PID of 1
.
Some programs are not designed to be run with continuous user input and disconnect from the terminal at the first opportunity. For example, a web server responds to web requests, rather than user input. Mail servers are another example of this type of application. These types of programs are known as daemons. The term daemon comes from Greek mythology and represents an entity that is neither good nor evil, and which invisibly performs useful tasks. This is why the BSD mascot is the cheerful-looking daemon with sneakers and a pitchfork.
There is a convention to name programs that normally run as
daemons with a trailing “d”. For example,
BIND is the Berkeley Internet Name
Domain, but the actual program that executes is
named
. The
Apache web server program is
httpd
and the line printer spooling daemon
is lpd
. This is only a naming convention.
For example, the main mail daemon for the
Sendmail application is
sendmail
, and not
maild
.
To see the processes running on the system, use ps(1) or top(1). To display a static list of the currently running processes, their PIDs, how much memory they are using, and the command they were started with, use ps(1). To display all the running processes and update the display every few seconds in order to interactively see what the computer is doing, use top(1).
By default, ps(1) only shows the commands that are running and owned by the user. For example:
%
ps
PID TT STAT TIME COMMAND 8203 0 Ss 0:00.59 /bin/csh 8895 0 R+ 0:00.00 ps
The output from ps(1) is organized into a number of
columns. The PID
column displays the
process ID. PIDs are assigned starting at
1, go up to 99999, then wrap around back to the beginning.
However, a PID is not reassigned if it is
already in use. The TT
column shows the
tty the program is running on and STAT
shows the program's state. TIME
is the
amount of time the program has been running on the CPU. This
is usually not the elapsed time since the program was started,
as most programs spend a lot of time waiting for things to
happen before they need to spend time on the CPU. Finally,
COMMAND
is the command that was used to
start the program.
A number of different options are available to change the
information that is displayed. One of the most useful sets is
auxww
, where a
displays
information about all the running processes of all users,
u
displays the username and memory usage of
the process' owner, x
displays
information about daemon processes, and ww
causes ps(1) to display the full command line for each
process, rather than truncating it once it gets too long to
fit on the screen.
The output from top(1) is similar:
%
top
last pid: 9609; load averages: 0.56, 0.45, 0.36 up 0+00:20:03 10:21:46 107 processes: 2 running, 104 sleeping, 1 zombie CPU: 6.2% user, 0.1% nice, 8.2% system, 0.4% interrupt, 85.1% idle Mem: 541M Active, 450M Inact, 1333M Wired, 4064K Cache, 1498M Free ARC: 992M Total, 377M MFU, 589M MRU, 250K Anon, 5280K Header, 21M Other Swap: 2048M Total, 2048M Free PID USERNAME THR PRI NICE SIZE RES STATE C TIME WCPU COMMAND 557 root 1 -21 r31 136M 42296K select 0 2:20 9.96% Xorg 8198 dru 2 52 0 449M 82736K select 3 0:08 5.96% kdeinit4 8311 dru 27 30 0 1150M 187M uwait 1 1:37 0.98% firefox 431 root 1 20 0 14268K 1728K select 0 0:06 0.98% moused 9551 dru 1 21 0 16600K 2660K CPU3 3 0:01 0.98% top 2357 dru 4 37 0 718M 141M select 0 0:21 0.00% kdeinit4 8705 dru 4 35 0 480M 98M select 2 0:20 0.00% kdeinit4 8076 dru 6 20 0 552M 113M uwait 0 0:12 0.00% soffice.bin 2623 root 1 30 10 12088K 1636K select 3 0:09 0.00% powerd 2338 dru 1 20 0 440M 84532K select 1 0:06 0.00% kwin 1427 dru 5 22 0 605M 86412K select 1 0:05 0.00% kdeinit4
The output is split into two sections. The header (the
first five or six lines) shows the PID of
the last process to run, the system load averages (which are a
measure of how busy the system is), the system uptime (time
since the last reboot) and the current time. The other
figures in the header relate to how many processes are
running, how much memory and swap space has been used, and how
much time the system is spending in different CPU states. If
the ZFS file system module has been loaded,
an ARC
line indicates how much data was
read from the memory cache instead of from disk.
Below the header is a series of columns containing similar information to the output from ps(1), such as the PID, username, amount of CPU time, and the command that started the process. By default, top(1) also displays the amount of memory space taken by the process. This is split into two columns: one for total size and one for resident size. Total size is how much memory the application has needed and the resident size is how much it is actually using now.
top(1) automatically updates the display every two
seconds. A different interval can be specified with
-s
.
One way to communicate with any running process or daemon
is to send a signal using kill(1).
There are a number of different signals; some have a specific
meaning while others are described in the application's
documentation. A user can only send a signal to a process
they own and sending a signal to someone else's process will
result in a permission denied error. The exception is the
root
user, who can
send signals to anyone's processes.
The operating system can also send a signal to a process.
If an application is badly written and tries to access memory
that it is not supposed to, FreeBSD will send the process the
“Segmentation Violation” signal
(SIGSEGV
). If an application has been
written to use the alarm(3) system call to be alerted
after a period of time has elapsed, it will be sent the
“Alarm” signal
(SIGALRM
).
Two signals can be used to stop a process:
SIGTERM
and SIGKILL
.
SIGTERM
is the polite way to kill a process
as the process can read the signal, close any log files it may
have open, and attempt to finish what it is doing before
shutting down. In some cases, a process may ignore
SIGTERM
if it is in the middle of some task
that cannot be interrupted.
SIGKILL
cannot be ignored by a
process. Sending a SIGKILL
to a
process will usually stop that process there and then.
[1].
Other commonly used signals are SIGHUP
,
SIGUSR1
, and SIGUSR2
.
Since these are general purpose signals, different
applications will respond differently.
For example, after changing a web server's configuration
file, the web server needs to be told to re-read its
configuration. Restarting httpd
would
result in a brief outage period on the web server. Instead,
send the daemon the SIGHUP
signal. Be
aware that different daemons will have different behavior, so
refer to the documentation for the daemon to determine if
SIGHUP
will achieve the desired
results.
This example shows how to send a signal to
inetd(8). The inetd(8) configuration file is
/etc/inetd.conf
, and inetd(8) will
re-read this configuration file when it is sent a
SIGHUP
.
Find the PID of the process to send the signal to using pgrep(1). In this example, the PID for inetd(8) is 198:
%
pgrep -l inetd
198 inetd -wW
Use kill(1) to send the signal. Because
inetd(8) is owned by
root
, use
su(1) to become
root
first.
%
su
Password:
#
/bin/kill -s HUP 198
Like most UNIX® commands, kill(1) will not print
any output if it is successful. If a signal is sent to a
process not owned by that user, the message
kill: PID
: Operation
not permitted will be displayed. Mistyping
the PID will either send the signal to
the wrong process, which could have negative results, or
will send the signal to a PID that is
not currently in use, resulting in the error
kill: PID
: No such
process.
/bin/kill
?: Many shells provide kill
as a
built in command, meaning that the shell will send the
signal directly, rather than running
/bin/kill
. Be aware that different
shells have a different syntax for specifying the name
of the signal to send. Rather than try to learn all of
them, it can be simpler to specify
/bin/kill
.
When sending other signals, substitute
TERM
or KILL
with the
name of the signal.
A shell provides a command line
interface for interacting with the operating system. A shell
receives commands from the input channel and executes them.
Many shells provide built in functions to help with everyday
tasks such as file management, file globbing, command line
editing, command macros, and environment variables. FreeBSD comes
with several shells, including the Bourne shell (sh(1)) and
the extended C shell (tcsh(1)). Other shells are available
from the FreeBSD Ports Collection, such as
zsh
and bash
.
The shell that is used is really a matter of taste. A C
programmer might feel more comfortable with a C-like shell such
as tcsh(1). A Linux® user might prefer
bash
. Each shell has unique properties that
may or may not work with a user's preferred working environment,
which is why there is a choice of which shell to use.
One common shell feature is filename completion. After a
user types the first few letters of a command or filename and
presses Tab, the shell completes the rest of
the command or filename. Consider two files called
foobar
and football
.
To delete foobar
, the user might type
rm foo
and press Tab to
complete the filename.
But the shell only shows rm foo
. It was
unable to complete the filename because both
foobar
and football
start with foo
. Some shells sound a beep or
show all the choices if more than one name matches. The user
must then type more characters to identify the desired filename.
Typing a t
and pressing Tab
again is enough to let the shell determine which filename is
desired and fill in the rest.
Another feature of the shell is the use of environment variables. Environment variables are a variable/key pair stored in the shell's environment. This environment can be read by any program invoked by the shell, and thus contains a lot of program configuration. Table 3.4, “Common Environment Variables” provides a list of common environment variables and their meanings. Note that the names of environment variables are always in uppercase.
Variable | Description |
---|---|
USER | Current logged in user's name. |
PATH | Colon-separated list of directories to search for binaries. |
DISPLAY | Network name of the Xorg display to connect to, if available. |
SHELL | The current shell. |
TERM | The name of the user's type of terminal. Used to determine the capabilities of the terminal. |
TERMCAP | Database entry of the terminal escape codes to perform various terminal functions. |
OSTYPE | Type of operating system. |
MACHTYPE | The system's CPU architecture. |
EDITOR | The user's preferred text editor. |
PAGER | The user's preferred utility for viewing text one page at a time. |
MANPATH | Colon-separated list of directories to search for manual pages. |
How to set an environment variable differs between shells.
In tcsh(1) and csh(1), use
setenv
to set environment variables. In
sh(1) and bash
, use
export
to set the current environment
variables. This example sets the default EDITOR
to /usr/local/bin/emacs
for the
tcsh(1) shell:
%
setenv EDITOR /usr/local/bin/emacs
The equivalent command for bash
would be:
%
export EDITOR="/usr/local/bin/emacs"
To expand an environment variable in order to see its
current setting, type a $
character in front
of its name on the command line. For example,
echo $TERM
displays the current
$TERM
setting.
Shells treat special characters, known as meta-characters,
as special representations of data. The most common
meta-character is *
, which represents any
number of characters in a filename. Meta-characters can be used
to perform filename globbing. For example, echo
*
is equivalent to ls
because
the shell takes all the files that match *
and echo
lists them on the command
line.
To prevent the shell from interpreting a special character,
escape it from the shell by starting it with a backslash
(\
). For example, echo
$TERM
prints the terminal setting whereas
echo \$TERM
literally prints the string
$TERM
.
The easiest way to permanently change the default shell is
to use chsh
. Running this command will
open the editor that is configured in the
EDITOR
environment variable, which by default
is set to vi(1). Change the Shell:
line to the full path of the new shell.
Alternately, use chsh -s
which will set
the specified shell without opening an editor. For example,
to change the shell to bash
:
%
chsh -s /usr/local/bin/bash
The new shell must be present in
/etc/shells
. If the shell was
installed from the FreeBSD Ports Collection as described in
Chapter 4, Installing Applications: Packages and Ports, it should be automatically added
to this file. If it is missing, add it using this command,
replacing the path with the path of the shell:
#
echo
/usr/local/bin/bash
>> /etc/shells
Then, rerun chsh(1).
The UNIX® shell is not just a command interpreter, it acts as a powerful tool which allows users to execute commands, redirect their output, redirect their input and chain commands together to improve the final command output. When this functionality is mixed with built in commands, the user is provided with an environment that can maximize efficiency.
Shell redirection is the action of sending the output or the input of a command into another command or into a file. To capture the output of the ls(1) command, for example, into a file, redirect the output:
%
ls > directory_listing.txt
The directory contents will now be listed in
directory_listing.txt
. Some commands can
be used to read input, such as sort(1). To sort this
listing, redirect the input:
%
sort < directory_listing.txt
The input will be sorted and placed on the screen. To redirect that input into another file, one could redirect the output of sort(1) by mixing the direction:
%
sort < directory_listing.txt > sorted.txt
In all of the previous examples, the commands are performing redirection using file descriptors. Every UNIX® system has file descriptors, which include standard input (stdin), standard output (stdout), and standard error (stderr). Each one has a purpose, where input could be a keyboard or a mouse, something that provides input. Output could be a screen or paper in a printer. And error would be anything that is used for diagnostic or error messages. All three are considered I/O based file descriptors and sometimes considered streams.
Through the use of these descriptors, the shell allows output and input to be passed around through various commands and redirected to or from a file. Another method of redirection is the pipe operator.
The UNIX® pipe operator, “|” allows the output of one command to be directly passed or directed to another program. Basically, a pipe allows the standard output of a command to be passed as standard input to another command, for example:
%
cat directory_listing.txt | sort | less
In that example, the contents of
directory_listing.txt
will be sorted and
the output passed to less(1). This allows the user to
scroll through the output at their own pace and prevent it
from scrolling off the screen.
Most FreeBSD configuration is done by editing text files. Because of this, it is a good idea to become familiar with a text editor. FreeBSD comes with a few as part of the base system, and many more are available in the Ports Collection.
A simple editor to learn is ee(1), which stands for
easy editor. To start this editor, type ee
where
filename
filename
is the name of the file to
be edited. Once inside the editor, all of the commands for
manipulating the editor's functions are listed at the top of the
display. The caret (^
) represents
Ctrl, so ^e
expands to
Ctrl+e. To leave ee(1), press Esc,
then choose the “leave editor” option from the main
menu. The editor will prompt to save any changes if the file
has been modified.
FreeBSD also comes with more powerful text editors, such as vi(1), as part of the base system. Other editors, like editors/emacs and editors/vim, are part of the FreeBSD Ports Collection. These editors offer more functionality at the expense of being more complicated to learn. Learning a more powerful editor such as vim or Emacs can save more time in the long run.
Many applications which modify files or require typed input
will automatically open a text editor. To change the default
editor, set the EDITOR
environment
variable as described in Section 3.9, “Shells”.
A device is a term used mostly for hardware-related
activities in a system, including disks, printers, graphics
cards, and keyboards. When FreeBSD boots, the majority of the boot
messages refer to devices being detected. A copy of the boot
messages are saved to
/var/run/dmesg.boot
.
Each device has a device name and number. For example,
ada0
is the first SATA hard drive,
while kbd0
represents the
keyboard.
Most devices in FreeBSD must be accessed through special
files called device nodes, which are located in
/dev
.
The most comprehensive documentation on FreeBSD is in the form
of manual pages. Nearly every program on the system comes with
a short reference manual explaining the basic operation and
available arguments. These manuals can be viewed using
man
:
%
man
command
where command
is the name of the
command to learn about. For example, to learn more about
ls(1), type:
%
man ls
Manual pages are divided into sections which represent the type of topic. In FreeBSD, the following sections are available:
User commands.
System calls and error numbers.
Functions in the C libraries.
Device drivers.
File formats.
Games and other diversions.
Miscellaneous information.
System maintenance and operation commands.
System kernel interfaces.
In some cases, the same topic may appear in more than one
section of the online manual. For example, there is a
chmod
user command and a
chmod()
system call. To tell man(1)
which section to display, specify the section number:
%
man 1 chmod
This will display the manual page for the user command chmod(1). References to a particular section of the online manual are traditionally placed in parenthesis in written documentation, so chmod(1) refers to the user command and chmod(2) refers to the system call.
If the name of the manual page is unknown, use man
-k
to search for keywords in the manual page
descriptions:
%
man -k
This command displays a list of commands that have the keyword “mail” in their descriptions. This is equivalent to using apropos(1).
To read the descriptions for all of the commands in
/usr/bin
, type:
%
cd /usr/bin
%
man -f * | more
or
%
cd /usr/bin
%
whatis * |more
FreeBSD includes several applications and utilities produced
by the Free Software Foundation (FSF). In addition to manual
pages, these programs may include hypertext documents called
info
files. These can be viewed using
info(1) or, if editors/emacs is
installed, the info mode of
emacs.
To use info(1), type:
%
info
For a brief introduction, type h
. For
a quick command reference, type ?
.
[1] There are a few tasks that cannot be interrupted. For example, if the process is trying to read from a file that is on another computer on the network, and the other computer is unavailable, the process is said to be “uninterruptible”. Eventually the process will time out, typically after two minutes. As soon as this time out occurs the process will be killed.
FreeBSD is bundled with a rich collection of system tools as part of the base system. In addition, FreeBSD provides two complementary technologies for installing third-party software: the FreeBSD Ports Collection, for installing from source, and packages, for installing from pre-built binaries. Either method may be used to install software from local media or from the network.
After reading this chapter, you will know:
The difference between binary packages and ports.
How to find third-party software that has been ported to FreeBSD.
How to manage binary packages using pkg.
How to build third-party software from source using the Ports Collection.
How to find the files installed with the application for post-installation configuration.
What to do if a software installation fails.
The typical steps for installing third-party software on a UNIX® system include:
Find and download the software, which might be distributed in source code format or as a binary.
Unpack the software from its distribution format. This is typically a tarball compressed with a program such as compress(1), gzip(1), bzip2(1) or xz(1).
Locate the documentation in
INSTALL
, README
or some file in a doc/
subdirectory and
read up on how to install the software.
If the software was distributed in source format,
compile it. This may involve editing a
Makefile
or running a
configure
script.
Test and install the software.
A FreeBSD port is a collection of files designed to automate the process of compiling an application from source code. The files that comprise a port contain all the necessary information to automatically download, extract, patch, compile, and install the application.
If the software has not already been adapted and tested on FreeBSD, the source code might need editing in order for it to install and run properly.
However, over 24,000 third-party applications have already been ported to FreeBSD. When feasible, these applications are made available for download as pre-compiled packages.
Packages can be manipulated with the FreeBSD package management commands.
Both packages and ports understand dependencies. If a package or port is used to install an application and a dependent library is not already installed, the library will automatically be installed first.
A FreeBSD package contains pre-compiled copies of all the
commands for an application, as well as any configuration files
and documentation. A package can be manipulated with the
pkg(8) commands, such as
pkg install
.
While the two technologies are similar, packages and ports each have their own strengths. Select the technology that meets your requirements for installing a particular application.
A compressed package tarball is typically smaller than the compressed tarball containing the source code for the application.
Packages do not require compilation time. For large applications, such as Mozilla, KDE, or GNOME, this can be important on a slow system.
Packages do not require any understanding of the process involved in compiling software on FreeBSD.
Packages are normally compiled with conservative options because they have to run on the maximum number of systems. By compiling from the port, one can change the compilation options.
Some applications have compile-time options relating to which features are installed. For example, Apache can be configured with a wide variety of different built-in options.
In some cases, multiple packages will exist for the same
application to specify certain settings. For example,
Ghostscript is available as a
ghostscript
package and a
ghostscript-nox11
package, depending on
whether or not Xorg is installed.
Creating multiple packages rapidly becomes impossible if an
application has more than one or two different compile-time
options.
The licensing conditions of some software forbid binary distribution. Such software must be distributed as source code which must be compiled by the end-user.
Some people do not trust binary distributions or prefer to read through source code in order to look for potential problems.
Source code is needed in order to apply custom patches.
To keep track of updated ports, subscribe to the FreeBSD ports mailing list and the FreeBSD ports bugs mailing list.
Before installing any application, check https://vuxml.freebsd.org/
for security issues related to the application or type
pkg audit -F
to check all installed
applications for known vulnerabilities.
The remainder of this chapter explains how to use packages and ports to install and manage third-party software on FreeBSD.
FreeBSD's list of available applications is growing all the time. There are a number of ways to find software to install:
The FreeBSD web site maintains an up-to-date searchable list of all the available applications, at https://www.FreeBSD.org/ports/. The ports can be searched by application name or by software category.
Dan Langille maintains FreshPorts.org which provides a comprehensive search utility and also tracks changes to the applications in the Ports Collection. Registered users can create a customized watch list in order to receive an automated email when their watched ports are updated.
If finding a particular application becomes challenging, try searching a site like SourceForge.net or GitHub.com then check back at the FreeBSD site to see if the application has been ported.
To search the binary package repository for an application:
#
pkg search
git-subversion-subversion
1.9.2
java-subversion-1.8.8_2
p5-subversion-1.8.8_2
py27-hgsubversion-1.6
py27-subversion-1.8.8_2
ruby-subversion-1.8.8_2
subversion-1.8.8_2
subversion-book-4515
subversion-static-1.8.8_2
subversion16-1.6.23_4
subversion17-1.7.16_2
Package names include the version number and, in the
case of ports based on python, the version number of the
version of python the package was built with. Some ports
also have multiple versions available. In the case of
Subversion, there are different
versions available, as well as different compile options.
In this case, the statically linked version of
Subversion. When indicating
which package to install, it is best to specify the
application by the port origin, which is the path in the
ports tree. Repeat the pkg search
with
-o
to list the origin of each
package:
#
pkg search -o
devel/git-subversion java/java-subversion devel/p5-subversion devel/py-hgsubversion devel/py-subversion devel/ruby-subversion devel/subversion16 devel/subversion17 devel/subversion devel/subversion-book devel/subversion-staticsubversion
Searching by shell globs, regular expressions, exact
match, by description, or any other field in the repository
database is also supported by pkg search
.
After installing ports-mgmt/pkg or
ports-mgmt/pkg-devel, see
pkg-search(8) for more details.
If the Ports Collection is already installed, there are
several methods to query the local version of the ports
tree. To find out which category a port is in, type
whereis
,
where file
file
is the program to be
installed:
#
whereis lsof
lsof: /usr/ports/sysutils/lsof
Alternately, an echo(1) statement can be used:
#
echo /usr/ports/*/*lsof*
/usr/ports/sysutils/lsof
Note that this will also return any matched files
downloaded into the
/usr/ports/distfiles
directory.
Another way to find software is by using the Ports
Collection's built-in search mechanism. To use the search
feature, cd to
/usr/ports
then run make
search name=program-name
where
program-name
is the name of the
software. For example, to search for
lsof
:
#
cd /usr/ports
#
make search name=lsof
Port: lsof-4.88.d,8 Path: /usr/ports/sysutils/lsof Info: Lists information about open files (similar to fstat(1)) Maint: ler@lerctr.org Index: sysutils B-deps: R-deps:
The built-in search mechanism uses a file
of index information. If a message indicates that the
INDEX
is required, run
make fetchindex
to download the current
index file. With the INDEX
present,
make search
will be able to perform the
requested search.
The “Path:” line indicates where to find the port.
To receive less information, use the
quicksearch
feature:
#
cd /usr/ports
#
make quicksearch name=lsof
Port: lsof-4.88.d,8 Path: /usr/ports/sysutils/lsof Info: Lists information about open files (similar to fstat(1))
For more in-depth searching, use
make search
key=
or
string
make quicksearch
key=
, where
string
string
is some text to search
for. The text can be in comments, descriptions, or
dependencies in order to find ports which relate to a
particular subject when the name of the program is
unknown.
When using search
or
quicksearch
, the search string
is case-insensitive. Searching for “LSOF” will
yield the same results as searching for
“lsof”.
pkg is the next generation replacement for the traditional FreeBSD package management tools, offering many features that make dealing with binary packages faster and easier.
For sites wishing to only use prebuilt binary packages from the FreeBSD mirrors, managing packages with pkg can be sufficient.
However, for those sites building from source or using their own repositories, a separate port management tool will be needed.
Since pkg only works with binary packages, it is not a replacement for such tools. Those tools can be used to install software from both binary packages and the Ports Collection, while pkg installs only binary packages.
FreeBSD includes a bootstrap utility which can be used to
download and install pkg
and its manual pages. This utility is designed to work
with versions of FreeBSD starting with
10.X
.
Not all FreeBSD versions and architectures support this bootstrap process. The current list is at https://pkg.freebsd.org/. For other cases, pkg must instead be installed from the Ports Collection or as a binary package.
To bootstrap the system, run:
#
/usr/sbin/pkg
You must have a working Internet connection for the bootstrap process to succeed.
Otherwise, to install the port, run:
#
cd /usr/ports/ports-mgmt/pkg
#
make
#
make install clean
When upgrading an existing system that originally used the older pkg_* tools, the database must be converted to the new format, so that the new tools are aware of the already installed packages. Once pkg has been installed, the package database must be converted from the traditional format to the new format by running this command:
#
pkg2ng
This step is not required for new installations that do not yet have any third-party software installed.
This step is not reversible. Once the package database
has been converted to the pkg
format, the traditional pkg_*
tools
should no longer be used.
The package database conversion may emit errors as the
contents are converted to the new version. Generally, these
errors can be safely ignored. However, a list of
software that was not successfully converted
is shown after pkg2ng
finishes.
These applications must be manually reinstalled.
To ensure that the Ports Collection registers
new software with pkg instead of
the traditional packages database, FreeBSD versions earlier than
10.X
require this line in
/etc/make.conf
:
WITH_PKGNG= yes
By default, pkg uses the binary packages from the FreeBSD package mirrors (the repository). For information about building a custom package repository, see Section 4.6, “Building Packages with Poudriere”.
Additional pkg configuration options are described in pkg.conf(5).
Usage information for pkg is
available in the pkg(8) manual page or by running
pkg
without additional arguments.
Each pkg command argument is
documented in a command-specific manual page. To read the
manual page for pkg install
, for example,
run either of these commands:
#
pkg help install
#
man pkg-install
The rest of this section demonstrates common binary package management tasks which can be performed using pkg. Each demonstrated command provides many switches to customize its use. Refer to a command's help or man page for details and more examples.
Information about the packages installed on a system
can be viewed by running pkg info
which,
when run without any switches, will list the package version
for either all installed packages or the specified
package.
For example, to see which version of pkg is installed, run:
#
pkg info pkg
pkg-1.1.4_1
To install a binary package use the following command,
where packagename
is the name of
the package to install:
#
pkg install
packagename
This command uses repository data to determine which version of the software to install and if it has any uninstalled dependencies. For example, to install curl:
#
pkg install curl
Updating repository catalogue /usr/local/tmp/All/curl-7.31.0_1.txz 100% of 1181 kB 1380 kBps 00m01s /usr/local/tmp/All/ca_root_nss-3.15.1_1.txz 100% of 288 kB 1700 kBps 00m00s Updating repository catalogue The following 2 packages will be installed: Installing ca_root_nss: 3.15.1_1 Installing curl: 7.31.0_1 The installation will require 3 MB more space 0 B to be downloaded Proceed with installing packages [y/N]:y
Checking integrity... done [1/2] Installing ca_root_nss-3.15.1_1... done [2/2] Installing curl-7.31.0_1... done Cleaning up cache files...Done
The new package and any additional packages that were installed as dependencies can be seen in the installed packages list:
#
pkg info
ca_root_nss-3.15.1_1 The root certificate bundle from the Mozilla Project curl-7.31.0_1 Non-interactive tool to get files from FTP, GOPHER, HTTP(S) servers pkg-1.1.4_6 New generation package manager
Packages that are no longer needed can be removed with
pkg delete
. For example:
#
pkg delete curl
The following packages will be deleted: curl-7.31.0_1 The deletion will free 3 MB Proceed with deleting packages [y/N]:y
[1/1] Deleting curl-7.31.0_1... done
Installed packages can be upgraded to their latest versions by running:
#
pkg upgrade
This command will compare the installed versions with those available in the repository catalogue and upgrade them from the repository.
Software vulnerabilities are regularly discovered in third-party applications. To address this, pkg includes a built-in auditing mechanism. To determine if there are any known vulnerabilities for the software installed on the system, run:
#
pkg audit -F
Removing a package may leave behind dependencies which are no longer required. Unneeded packages that were installed as dependencies (leaf packages) can be automatically detected and removed using:
#
pkg autoremove
Packages to be autoremoved: ca_root_nss-3.15.1_1 The autoremoval will free 723 kB Proceed with autoremoval of packages [y/N]:y
Deinstalling ca_root_nss-3.15.1_1... done
Packages installed as dependencies are called automatic packages. Non-automatic packages, i.e the packages that were explicity installed not as a dependency to another package, can be listed using:
#
pkg prime-list
nginx openvpn sudo
pkg prime-list
is an alias command
declared in /usr/local/etc/pkg.conf
.
There are many others that can be used to query the package
database of the system. For instance, command
pkg prime-origins
can be used to get the
origin port directory of the list mentioned above:
#
pkg prime-origins
www/nginx security/openvpn security/sudo
This list can be used to rebuild all packages installed on a system using build tools such as ports-mgmt/poudriere or ports-mgmt/synth.
Marking an installed package as automatic can be done using:
#
pkg set -A 1 devel/cmake
Once a package is a leaf package and is marked
as automatic, it gets selected by
pkg autoremove
.
Marking an installed package as not automatic can be done using:
#
pkg set -A 0 devel/cmake
Unlike the traditional package management system, pkg includes its own package database backup mechanism. This functionality is enabled by default.
To disable the periodic script from backing up the
package database, set
daily_backup_pkgdb_enable="NO"
in
periodic.conf(5).
To restore the contents of a previous package database
backup, run the following command replacing
/path/to/pkg.sql
with the location
of the backup:
#
pkg backup -r
/path/to/pkg.sql
If restoring a backup taken by the periodic script, it must be decompressed prior to being restored.
To run a manual backup of the
pkg database, run the following
command, replacing /path/to/pkg.sql
with a suitable file name and location:
#
pkg backup -d
/path/to/pkg.sql
By default, pkg stores
binary packages in a cache directory defined by
PKG_CACHEDIR
in pkg.conf(5). Only copies
of the latest installed packages are kept. Older versions of
pkg kept all previous packages. To
remove these outdated binary packages, run:
#
pkg clean
The entire cache may be cleared by running:
#
pkg clean -a
Software within the FreeBSD Ports Collection can
undergo major version number changes. To address this,
pkg has a built-in command to
update package origins. This can be useful, for example, if
lang/php5 is renamed to
lang/php53 so that
lang/php5 can now
represent version 5.4
.
To change the package origin for the above example, run:
#
pkg set -o lang/php5:lang/php53
As another example, to update lang/ruby18 to lang/ruby19, run:
#
pkg set -o lang/ruby18:lang/ruby19
As a final example, to change the origin of the
libglut
shared libraries from
graphics/libglut to
graphics/freeglut, run:
#
pkg set -o graphics/libglut:graphics/freeglut
When changing package origins, it is important to reinstall packages that are dependent on the package with the modified origin. To force a reinstallation of dependent packages, run:
#
pkg install -Rf
graphics/freeglut
The Ports Collection is a set of
Makefiles
, patches, and description files.
Each set of these files is used to compile and install an
individual application on FreeBSD, and is called a
port.
By default, the Ports Collection itself is stored as a
subdirectory of /usr/ports
.
Before an application can be compiled using a port, the Ports Collection must first be installed. If it was not installed during the installation of FreeBSD, use one of the following methods to install it:
The base system of FreeBSD includes Portsnap. This is a fast and user-friendly tool for retrieving the Ports Collection and is the recommended choice for most users. This utility connects to a FreeBSD site, verifies the secure key, and downloads a new copy of the Ports Collection. The key is used to verify the integrity of all downloaded files.
To download a compressed snapshot of the Ports
Collection into
/var/db/portsnap
:
#
portsnap fetch
When running Portsnap for the
first time, extract the snapshot into
/usr/ports
:
#
portsnap extract
After the first use of
Portsnap has been completed as
shown above, /usr/ports
can be updated
as needed by running:
#
portsnap fetch
#
portsnap update
When using fetch
, the
extract
or the update
operation may be run consecutively, like so:
#
portsnap fetch update
If more control over the ports tree is needed or if local changes need to be maintained, Subversion can be used to obtain the Ports Collection. Refer to the Subversion Primer for a detailed description of Subversion.
Subversion must be installed before it can be used to check out the ports tree. If a copy of the ports tree is already present, install Subversion like this:
#
cd /usr/ports/devel/subversion
#
make install clean
If the ports tree is not available, or pkg is being used to manage packages, Subversion can be installed as a package:
#
pkg install subversion
Check out a copy of the ports tree:
#
svn checkout https://svn.FreeBSD.org/ports/head /usr/ports
As needed, update /usr/ports
after
the initial Subversion
checkout:
#
svn update /usr/ports
The Ports Collection contains directories for software categories. Inside each category are subdirectories for individual applications. Each application subdirectory contains a set of files that tells FreeBSD how to compile and install that program, called a ports skeleton. Each port skeleton includes these files and directories:
Makefile
: contains statements that
specify how the application should be compiled and where
its components should be installed.
distinfo
: contains the names and
checksums of the files that must be downloaded to build the
port.
files/
: this directory contains
any patches needed for the program to compile and install
on FreeBSD. This directory may also contain other files used
to build the port.
pkg-descr
: provides a more detailed
description of the program.
pkg-plist
: a list of all the
files that will be installed by the port. It also tells
the ports system which files to remove upon
deinstallation.
Some ports include pkg-message
or
other files to handle special situations. For more details
on these files, and on ports in general, refer to the FreeBSD
Porter's Handbook.
The port does not include the actual source code, also
known as a distfile
. The extract portion
of building a port will automatically save the downloaded
source to /usr/ports/distfiles
.
This section provides basic instructions on using the
Ports Collection to install or remove software. The detailed
description of available make
targets and
environment variables is available in ports(7).
Before compiling any port, be sure to update the Ports
Collection as described in the previous section. Since
the installation of any third-party software can introduce
security vulnerabilities, it is recommended to first check
https://vuxml.freebsd.org/
for known security issues related to the port. Alternately,
run pkg audit -F
before installing a new
port. This command can be configured to automatically
perform a security audit and an update of the vulnerability
database during the daily security system check. For more
information, refer to pkg-audit(8) and
periodic(8).
Using the Ports Collection assumes a working Internet connection. It also requires superuser privilege.
To compile and install the port, change to the directory
of the port to be installed, then type make
install
at the prompt. Messages will indicate
the progress:
#
cd /usr/ports/sysutils/lsof
#
make install
>> lsof_4.88D.freebsd.tar.gz doesn't seem to exist in /usr/ports/distfiles/. >> Attempting to fetch from ftp://lsof.itap.purdue.edu/pub/tools/unix/lsof/. ===> Extracting for lsof-4.88 ... [extraction output snipped] ... >> Checksum OK for lsof_4.88D.freebsd.tar.gz. ===> Patching for lsof-4.88.d,8 ===> Applying FreeBSD patches for lsof-4.88.d,8 ===> Configuring for lsof-4.88.d,8 ... [configure output snipped] ... ===> Building for lsof-4.88.d,8 ... [compilation output snipped] ... ===> Installing for lsof-4.88.d,8 ... [installation output snipped] ... ===> Generating temporary packing list ===> Compressing manual pages for lsof-4.88.d,8 ===> Registering installation for lsof-4.88.d,8 ===> SECURITY NOTE: This port has installed the following binaries which execute with increased privileges. /usr/local/sbin/lsof#
Since lsof
is a program that runs
with increased privileges, a security warning is displayed
as it is installed. Once the installation is complete, the
prompt will be returned.
Some shells keep a cache of the commands that are
available in the directories listed in the
PATH
environment variable, to speed up lookup
operations for the executable file of these commands. Users
of the tcsh
shell should type
rehash
so that a newly installed command
can be used without specifying its full path. Use
hash -r
instead for the
sh
shell. Refer to the documentation
for the shell for more information.
During installation, a working subdirectory is created which contains all the temporary files used during compilation. Removing this directory saves disk space and minimizes the chance of problems later when upgrading to the newer version of the port:
#
make clean
===> Cleaning for lsof-88.d,8#
To save this extra step, instead use make
install clean
when compiling the port.
Some ports provide build options which can be used to
enable or disable application components, provide security
options, or allow for other customizations. Examples
include www/firefox,
security/gpgme, and
mail/sylpheed-claws. If the port depends
upon other ports which have configurable options, it may
pause several times for user interaction as the default
behavior is to prompt the user to select options from a
menu. To avoid this and do all of the configuration in one
batch, run make config-recursive
within
the port skeleton. Then, run make install
[clean]
to compile and install the port.
When using
config-recursive
, the list of
ports to configure are gathered by the
all-depends-list
target. It is
recommended to run make
config-recursive
until all dependent ports
options have been defined, and ports options screens no
longer appear, to be certain that all dependency options
have been configured.
There are several ways to revisit a port's build options
menu in order to add, remove, or change these options after
a port has been built. One method is to
cd
into the directory containing the
port and type make config
. Another
option is to use make showconfig
.
Another option is to execute make
rmconfig
which will remove all selected options
and allow you to start over. All of these options, and
others, are explained in great detail in
ports(7).
The ports system uses fetch(1) to download the
source files, which supports various environment variables.
The FTP_PASSIVE_MODE
,
FTP_PROXY
, and FTP_PASSWORD
variables may need to be set if the FreeBSD system is behind
a firewall or FTP/HTTP proxy. See fetch(3) for the
complete list of supported variables.
For users who cannot be connected to the Internet all
the time, make fetch
can be run within
/usr/ports
, to fetch all distfiles, or
within a category, such as
/usr/ports/net
, or within the specific
port skeleton. Note that if a port has any dependencies,
running this command in a category or ports skeleton will
not fetch the distfiles of ports from
another category. Instead, use make
fetch-recursive
to also fetch the distfiles for
all the dependencies of a port.
In rare cases, such as when an organization has a local
distfiles repository, the MASTER_SITES
variable can be used to override the download locations
specified in the Makefile
. When using,
specify the alternate location:
#
cd /usr/ports/
directory
#
make MASTER_SITE_OVERRIDE= \
ftp://ftp.organization.org/pub/FreeBSD/ports/distfiles/
fetch
The WRKDIRPREFIX
and
PREFIX
variables can override the default
working and target directories. For example:
#
make WRKDIRPREFIX=/usr/home/example/ports install
will compile the port in
/usr/home/example/ports
and install
everything under /usr/local
.
#
make PREFIX=/usr/home/example/local install
will compile the port in /usr/ports
and install it in
/usr/home/example/local
. And:
#
make WRKDIRPREFIX=../ports PREFIX=../local install
will combine the two.
These can also be set as environmental variables. Refer to the manual page for your shell for instructions on how to set an environmental variable.
Installed ports can be uninstalled using pkg
delete
. Examples for using this command can be
found in the pkg-delete(8) manual page.
Alternately, make deinstall
can be
run in the port's directory:
#
cd /usr/ports/sysutils/lsof
make deinstall
===> Deinstalling for sysutils/lsof ===> Deinstalling Deinstallation has been requested for the following 1 packages: lsof-4.88.d,8 The deinstallation will free 229 kB [1/1] Deleting lsof-4.88.d,8... done
It is recommended to read the messages as the port is uninstalled. If the port has any applications that depend upon it, this information will be displayed but the uninstallation will proceed. In such cases, it may be better to reinstall the application in order to prevent broken dependencies.
Over time, newer versions of software become available in the Ports Collection. This section describes how to determine which software can be upgraded and how to perform the upgrade.
To determine if newer versions of installed ports are available, ensure that the latest version of the ports tree is installed, using the updating command described in either Procedure 4.1, “Portsnap Method” or Procedure 4.2, “Subversion Method”. On FreeBSD 10 and later, or if the system has been converted to pkg, the following command will list the installed ports which are out of date:
#
pkg version -l "<"
For FreeBSD 9.X
and lower, the
following command will list the installed ports that are out
of date:
#
pkg_version -l "<"
Before
attempting an upgrade, read
/usr/ports/UPDATING
from the top of
the file to the date closest to the last time ports were
upgraded or the system was installed. This file describes
various issues and additional steps users may encounter and
need to perform when updating a port, including such things
as file format changes, changes in locations of
configuration files, or any incompatibilities with previous
versions. Make note of any instructions which match any of
the ports that need upgrading and follow these instructions
when performing the upgrade.
The Ports Collection contains several utilities to perform the actual upgrade. Each has its strengths and weaknesses.
Historically, most installations used either Portmaster or Portupgrade. Synth is a newer alternative.
The choice of which tool is best for a particular system is up to the system administrator. It is recommended practice to back up your data before using any of these tools.
ports-mgmt/portmaster is a very small utility for upgrading installed ports. It is designed to use the tools installed with the FreeBSD base system without depending on other ports or databases. To install this utility as a port:
#
cd /usr/ports/ports-mgmt/portmaster
#
make install clean
Portmaster defines four categories of ports:
Root port: has no dependencies and is not a dependency of any other ports.
Trunk port: has no dependencies, but other ports depend upon it.
Branch port: has dependencies and other ports depend upon it.
Leaf port: has dependencies but no other ports depend upon it.
To list these categories and search for updates:
#
portmaster -L
===>>> Root ports (No dependencies, not depended on) ===>>> ispell-3.2.06_18 ===>>> screen-4.0.3 ===>>> New version available: screen-4.0.3_1 ===>>> tcpflow-0.21_1 ===>>> 7 root ports ... ===>>> Branch ports (Have dependencies, are depended on) ===>>> apache22-2.2.3 ===>>> New version available: apache22-2.2.8 ... ===>>> Leaf ports (Have dependencies, not depended on) ===>>> automake-1.9.6_2 ===>>> bash-3.1.17 ===>>> New version available: bash-3.2.33 ... ===>>> 32 leaf ports ===>>> 137 total installed ports ===>>> 83 have new versions available
This command is used to upgrade all outdated ports:
#
portmaster -a
By default, Portmaster
makes a backup package before deleting the existing port.
If the installation of the new version is successful,
Portmaster deletes the
backup. Using -b
instructs
Portmaster not to automatically
delete the backup. Adding -i
starts
Portmaster in interactive mode,
prompting for confirmation before upgrading each port.
Many other options are available. Read through the
manual page for portmaster(8) for details regarding
their usage.
If errors are encountered during the upgrade process,
add -f
to upgrade and rebuild all
ports:
#
portmaster -af
Portmaster can also be used to install new ports on the system, upgrading all dependencies before building and installing the new port. To use this function, specify the location of the port in the Ports Collection:
#
portmaster
shells/bash
More information about
ports-mgmt/portmaster may be found in its
pkg-descr
.
ports-mgmt/portupgrade is another utility that can be used to upgrade ports. It installs a suite of applications which can be used to manage ports. However, it is dependent upon Ruby. To install the port:
#
cd /usr/ports/ports-mgmt/portupgrade
#
make install clean
Before performing an upgrade using this utility, it is
recommended to scan the list of installed ports using
pkgdb -F
and to fix all the
inconsistencies it reports.
To upgrade all the outdated ports installed on the
system, use portupgrade -a
. Alternately,
include -i
to be asked for confirmation
of every individual upgrade:
#
portupgrade -ai
To upgrade only a specified application instead of all
available ports, use portupgrade
. It is very
important to include pkgname
-R
to first upgrade
all the ports required by the given application:
#
portupgrade -R firefox
If
-P
is included,
Portupgrade searches for
available packages in the local directories listed in
PKG_PATH
. If none are available locally, it
then fetches packages from a remote site. If packages can
not be found locally or fetched remotely,
Portupgrade will use ports. To
avoid using ports entirely, specify -PP
.
This last set of options tells
Portupgrade to abort if no
packages are available:
#
portupgrade -PP gnome3
To just fetch the port distfiles, or packages, if
-P
is specified, without building or
installing anything, use -F
. For further
information on all of the available switches, refer to the
manual page for portupgrade
.
More information about
ports-mgmt/portupgrade may be found in
its pkg-descr
.
Using the Ports Collection will use up disk space over
time. After building and installing a port, running
make clean
within the ports skeleton will
clean up the temporary work
directory.
If Portmaster is used to install a
port, it will automatically remove this directory unless
-K
is specified. If
Portupgrade is installed, this
command will remove all work
directories
found within the local copy of the Ports Collection:
#
portsclean -C
In addition, outdated source distribution files
accumulate in /usr/ports/distfiles
over
time. To use Portupgrade to
delete all the distfiles that are no longer
referenced by any ports:
#
portsclean -D
Portupgrade can remove all distfiles not referenced by any port currently installed on the system:
#
portsclean -DD
If Portmaster is installed, use:
#
portmaster --clean-distfiles
By default, this command is interactive and prompts the user to confirm if a distfile should be deleted.
In addition to these commands, ports-mgmt/pkg_cutleaves automates the task of removing installed ports that are no longer needed.
Poudriere is a BSD-licensed utility for creating and testing FreeBSD packages. It uses FreeBSD jails to set up isolated compilation environments. These jails can be used to build packages for versions of FreeBSD that are different from the system on which it is installed, and also to build packages for i386 if the host is an amd64 system. Once the packages are built, they are in a layout identical to the official mirrors. These packages are usable by pkg(8) and other package management tools.
Poudriere is installed using
the ports-mgmt/poudriere package
or port. The installation includes a sample configuration
file /usr/local/etc/poudriere.conf.sample
.
Copy this file to
/usr/local/etc/poudriere.conf
. Edit the
copied file to suit the local configuration.
While ZFS is not required on the system
running poudriere, it is beneficial.
When ZFS is used,
ZPOOL
must be specified in
/usr/local/etc/poudriere.conf
and
FREEBSD_HOST
should be set to a nearby
mirror. Defining CCACHE_DIR
enables the use
of devel/ccache to cache
compilation and reduce build times for frequently-compiled code.
It may be convenient to put
poudriere datasets in an isolated
tree mounted at /poudriere
. Defaults for the
other configuration values are adequate.
The number of processor cores detected is used to define how many builds will run in parallel. Supply enough virtual memory, either with RAM or swap space. If virtual memory runs out, the compilation jails will stop and be torn down, resulting in weird error messages.
After configuration, initialize
poudriere so that it installs a
jail with the required FreeBSD tree and a ports tree. Specify a
name for the jail using -j
and the FreeBSD
version with -v
. On systems running
FreeBSD/amd64, the architecture can be set with
-a
to either i386
or
amd64
. The default is the
architecture shown by uname
.
#
poudriere jail -c -j
====>> Creating 10amd64 fs... done ====>> Fetching base.txz for FreeBSD 10.0-RELEASE amd64 /poudriere/jails/10amd64/fromftp/base.txz 100% of 59 MB 1470 kBps 00m42s ====>> Extracting base.txz... done ====>> Fetching src.txz for FreeBSD 10.0-RELEASE amd64 /poudriere/jails/10amd64/fromftp/src.txz 100% of 107 MB 1476 kBps 01m14s ====>> Extracting src.txz... done ====>> Fetching games.txz for FreeBSD 10.0-RELEASE amd64 /poudriere/jails/10amd64/fromftp/games.txz 100% of 865 kB 734 kBps 00m01s ====>> Extracting games.txz... done ====>> Fetching lib32.txz for FreeBSD 10.0-RELEASE amd64 /poudriere/jails/10amd64/fromftp/lib32.txz 100% of 14 MB 1316 kBps 00m12s ====>> Extracting lib32.txz... done ====>> Cleaning up... done ====>> Jail 10amd64 10.0-RELEASE amd64 is ready to be used10amd64
-v10.0-RELEASE
#
poudriere ports -c -p
====>> Creating local fs... done ====>> Extracting portstree "local"... Looking up portsnap.FreeBSD.org mirrors... 7 mirrors found. Fetching public key from ec2-eu-west-1.portsnap.freebsd.org... done. Fetching snapshot tag from ec2-eu-west-1.portsnap.freebsd.org... done. Fetching snapshot metadata... done. Fetching snapshot generated at Tue Feb 11 01:07:15 CET 2014: 94a3431f0ce567f6452ffde4fd3d7d3c6e1da143efec76100% of 69 MB 1246 kBps 00m57s Extracting snapshot... done. Verifying snapshot integrity... done. Fetching snapshot tag from ec2-eu-west-1.portsnap.freebsd.org... done. Fetching snapshot metadata... done. Updating from Tue Feb 11 01:07:15 CET 2014 to Tue Feb 11 16:05:20 CET 2014. Fetching 4 metadata patches... done. Applying metadata patches... done. Fetching 0 metadata files... done. Fetching 48 patches. (48/48) 100.00% done. done. Applying patches... done. Fetching 1 new ports or files... done. /poudriere/ports/tester/CHANGES /poudriere/ports/tester/COPYRIGHT [...] Building new INDEX files... done.local
On a single computer, poudriere can build ports with multiple configurations, in multiple jails, and from different port trees. Custom configurations for these combinations are called sets. See the CUSTOMIZATION section of poudriere(8) for details after ports-mgmt/poudriere or ports-mgmt/poudriere-devel is installed.
The basic configuration shown here puts a single jail-,
port-, and set-specific make.conf
in
/usr/local/etc/poudriere.d
.
The filename in this example is created by combining the jail
name, port name, and set name:
.
The system 10amd64-local-workstation
-make.confmake.conf
and this new file
are combined at build time to create the
make.conf
used by the build jail.
Packages to be built are entered in
:10amd64-local-workstation
-pkglist
editors/emacs devel/git ports-mgmt/pkg ...
Options and dependencies for the specified ports are configured:
#
poudriere options -j
10amd64
-plocal
-zworkstation
-f10amd64-local-workstation-pkglist
Finally, packages are built and a package repository is created:
#
poudriere bulk -j
10amd64
-plocal
-zworkstation
-f10amd64-local-workstation-pkglist
While running, pressing Ctrl+t
displays the current state of the build.
Poudriere also builds files in
/poudriere/logs/bulk/
that can be used with a web server to display build
information.jailname
After completion, the new packages are now available for installation from the poudriere repository.
For more information on using poudriere, see poudriere(8) and the main web site, https://github.com/freebsd/poudriere/wiki.
While it is possible to use both a custom repository along
side of the official repository, sometimes it is useful to
disable the official repository. This is done by creating a
configuration file that overrides and disables the official
configuration file. Create
/usr/local/etc/pkg/repos/FreeBSD.conf
that contains the following:
FreeBSD: { enabled: no }
Usually it is easiest to serve a poudriere repository to
the client machines via HTTP. Set up a webserver to serve up
the package directory, for instance:
/usr/local/poudriere/data/packages/
,
where 10amd64
is the name of the build.10amd64
If the URL to the package repository is:
http://pkg.example.com/10amd64
, then the
repository configuration file in
/usr/local/etc/pkg/repos/custom.conf
would look like:
custom: {
url: "http://pkg.example.com/10amd64
",
enabled: yes,
}
Regardless of whether the software was installed from a binary package or port, most third-party applications require some level of configuration after installation. The following commands and locations can be used to help determine what was installed with the application.
Most applications install at least one default
configuration file in /usr/local/etc
.
In cases where an application has a large number of
configuration files, a subdirectory will be created to hold
them. Often, sample configuration files are installed which
end with a suffix such as .sample
. The
configuration files should be reviewed and possibly
edited to meet the system's needs. To edit a sample file,
first copy it without the .sample
extension.
Applications which provide documentation will install
it into /usr/local/share/doc
and many
applications also install manual pages. This documentation
should be consulted before continuing.
Some applications run services which must be added
to /etc/rc.conf
before starting the
application. These applications usually install a startup
script in /usr/local/etc/rc.d
. See
Starting
Services for more information.
By design, applications do not run their startup script upon installation, nor do they run their stop script upon deinstallation or upgrade. This decision is left to the individual system administrator.
Users of csh(1) should run
rehash
to rebuild the known binary list
in the shells PATH
.
Use pkg info
to determine which
files, man pages, and binaries were installed with the
application.
When a port does not build or install, try the following:
Search to see if there is a fix pending for the port in the Problem Report database. If so, implementing the proposed fix may fix the issue.
Ask the maintainer of the port for help. Type
make maintainer
in the ports skeleton or read the port's
Makefile
to find the maintainer's
email address. Remember to include the
$FreeBSD:
line from the port's
Makefile
and the output leading up to
the error in the email to the maintainer.
Some ports are not maintained by an individual but
instead by a group maintainer represented by a mailing
list. Many, but not all, of these addresses look
like <freebsd-
.
Please take this into account when sending an
email.listname
@FreeBSD.org>
In particular, ports maintained by
<ports@FreeBSD.org>
are not
maintained by a specific individual. Instead, any fixes
and support come from the general community who subscribe
to that mailing list. More volunteers are always
needed!
If there is no response to the email, use Bugzilla to submit a bug report using the instructions in Writing FreeBSD Problem Reports.
Fix it! The Porter's Handbook includes detailed information on the ports infrastructure so that you can fix the occasional broken port or even submit your own!
Install the package instead of the port using the instructions in Section 4.4, “Using pkg for Binary Package Management”.
An installation of FreeBSD using bsdinstall does not automatically install a graphical user interface. This chapter describes how to install and configure Xorg, which provides the open source X Window System used to provide a graphical environment. It then describes how to find and install a desktop environment or window manager.
Users who prefer an installation method that automatically configures the Xorg and offers a choice of window managers during installation should refer to the http://www.trueos.org/ website.
For more information on the video hardware that Xorg supports, refer to the x.org website.
After reading this chapter, you will know:
The various components of the X Window System, and how they interoperate.
How to install and configure Xorg.
How to install and configure several window managers and desktop environments.
How to use TrueType® fonts in Xorg.
How to set up your system for graphical logins (XDM).
Before reading this chapter, you should:
Know how to install additional third-party software as described in Chapter 4, Installing Applications: Packages and Ports.
While it is not necessary to understand all of the details of the various components in the X Window System and how they interact, some basic knowledge of these components can be useful.
X was designed from the beginning to be network-centric, and adopts a “client-server” model. In this model, the “X server” runs on the computer that has the keyboard, monitor, and mouse attached. The server's responsibility includes tasks such as managing the display, handling input from the keyboard and mouse, and handling input or output from other devices such as a tablet or a video projector. This confuses some people, because the X terminology is exactly backward to what they expect. They expect the “X server” to be the big powerful machine down the hall, and the “X client” to be the machine on their desk.
Each X application, such as XTerm or Firefox, is a “client”. A client sends messages to the server such as “Please draw a window at these coordinates”, and the server sends back messages such as “The user just clicked on the OK button”.
In a home or small office environment, the X server and the X clients commonly run on the same computer. It is also possible to run the X server on a less powerful computer and to run the X applications on a more powerful system. In this scenario, the communication between the X client and server takes place over the network.
X does not dictate what windows should look like
on-screen, how to move them around with the mouse, which
keystrokes should be used to move between windows, what
the title bars on each window should look like, whether or
not they have close buttons on them, and so on. Instead,
X delegates this responsibility to a separate window
manager application. There are dozens of window
managers available. Each window manager provides
a different look and feel: some support virtual desktops,
some allow customized keystrokes to manage the desktop,
some have a “Start” button, and some are
themeable, allowing a complete change of the desktop's
look-and-feel. Window managers are available in the
x11-wm
category of the Ports
Collection.
Each window manager uses a different configuration mechanism. Some expect configuration file written by hand while others provide graphical tools for most configuration tasks.
KDE and GNOME are considered to be desktop environments as they include an entire suite of applications for performing common desktop tasks. These may include office suites, web browsers, and games.
The window manager is responsible for the mouse focus policy. This policy provides some means for choosing which window is actively receiving keystrokes and it should also visibly indicate which window is currently active.
One focus policy is called “click-to-focus”. In this model, a window becomes active upon receiving a mouse click. In the “focus-follows-mouse” policy, the window that is under the mouse pointer has focus and the focus is changed by pointing at another window. If the mouse is over the root window, then this window is focused. In the “sloppy-focus” model, if the mouse is moved over the root window, the most recently used window still has the focus. With sloppy-focus, focus is only changed when the cursor enters a new window, and not when exiting the current window. In the “click-to-focus” policy, the active window is selected by mouse click. The window may then be raised and appear in front of all other windows. All keystrokes will now be directed to this window, even if the cursor is moved to another window.
Different window managers support different focus models. All of them support click-to-focus, and the majority of them also support other policies. Consult the documentation for the window manager to determine which focus models are available.
Widget is a term for all of the items in the user interface that can be clicked or manipulated in some way. This includes buttons, check boxes, radio buttons, icons, and lists. A widget toolkit is a set of widgets used to create graphical applications. There are several popular widget toolkits, including Qt, used by KDE, and GTK+, used by GNOME. As a result, applications will have a different look and feel, depending upon which widget toolkit was used to create the application.
On FreeBSD, Xorg can be installed as a package or port.
The binary package can be installed quickly but with fewer options for customization:
#
pkg install xorg
To build and install from the Ports Collection:
#
cd /usr/ports/x11/xorg
#
make install clean
Either of these installations results in the complete Xorg system being installed. Binary packages are the best option for most users.
A smaller version of the X system suitable for experienced users is available in x11/xorg-minimal. Most of the documents, libraries, and applications will not be installed. Some applications require these additional components to function.
Xorg supports most common video cards, keyboards, and pointing devices.
Video cards, monitors, and input devices are
automatically detected and do not require any manual
configuration. Do not create xorg.conf
or run a -configure
step unless automatic
configuration fails.
If Xorg has been used on this computer before, move or remove any existing configuration files:
#
mv /etc/X11/xorg.conf ~/xorg.conf.etc
#
mv /usr/local/etc/X11/xorg.conf ~/xorg.conf.localetc
Add the user who will run
Xorg to the
video
or
wheel
group to enable 3D acceleration
when available. To add user
jru
to whichever group is
available:
#
pw groupmod video -m
jru
|| pw groupmod wheel -mjru
The TWM window manager is included by default. It is started when Xorg starts:
%
startx
On some older versions of FreeBSD, the system console must be set to vt(4) before switching back to the text console will work properly. See Section 5.4.3, “Kernel Mode Setting (KMS)”.
Access to /dev/dri
is needed to allow
3D acceleration on video cards. It is usually simplest to add
the user who will be running X to either the
video
or wheel
group.
Here, pw(8) is used to add user
slurms
to the
video
group, or to the
wheel
group if there is no
video
group:
#
pw groupmod video -m
slurms
|| pw groupmod wheel -mslurms
When the computer switches from displaying the console to a higher screen resolution for X, it must set the video output mode. Recent versions of Xorg use a system inside the kernel to do these mode changes more efficiently. Older versions of FreeBSD use sc(4), which is not aware of the KMS system. The end result is that after closing X, the system console is blank, even though it is still working. The newer vt(4) console avoids this problem.
Add this line to /boot/loader.conf
to enable vt(4):
kern.vty=vt
Manual configuration is usually not necessary. Please do not manually create configuration files unless autoconfiguration does not work.
Xorg looks in several
directories for configuration files.
/usr/local/etc/X11/
is the recommended
directory for these files on FreeBSD. Using this directory
helps keep application files separate from operating system
files.
Storing configuration files in the legacy
/etc/X11/
still works. However, this
mixes application files with the base FreeBSD files and is not
recommended.
It is easier to use multiple files that each configure a
specific setting than the traditional single
xorg.conf
. These files are stored in
the xorg.conf.d/
subdirectory of the
main configuration file directory. The full path is
typically
/usr/local/etc/X11/xorg.conf.d/
.
Examples of these files are shown later in this section.
The traditional single xorg.conf
still works, but is neither as clear nor as flexible as
multiple files in the xorg.conf.d/
subdirectory.
Because of changes made in recent versions of FreeBSD, it is now possible to use graphics drivers provided by the Ports framework or as packages. As such, users can use one of the following drivers available from graphics/drm-kmod.
2D and 3D acceleration is supported on most Intel KMS driver graphics cards provided by Intel.
Driver name: i915kms
2D and 3D acceleration is supported on most older Radeon KMS driver graphics cards provided by AMD.
Driver name: radeonkms
2D and 3D acceleration is supported on most newer AMD KMS driver graphics cards provided by AMD.
Driver name: amdgpu
For reference, please see https://en.wikipedia.org/wiki/List_of_Intel_graphics_processing_units or https://en.wikipedia.org/wiki/List_of_AMD_graphics_processing_units for a list of supported GPUs.
3D acceleration is supported on most Intel® graphics up to Ivy Bridge (HD Graphics 2500, 4000, and P4000), including Iron Lake (HD Graphics) and Sandy Bridge (HD Graphics 2000).
Driver name: intel
For reference, see https://en.wikipedia.org/wiki/List_of_Intel_graphics_processing_units.
2D and 3D acceleration is supported on Radeon cards up to and including the HD6000 series.
Driver name: radeon
For reference, see https://en.wikipedia.org/wiki/List_of_AMD_graphics_processing_units.
Several NVIDIA drivers are available in the
x11
category of the Ports
Collection. Install the driver that matches the video
card.
For reference, see https://en.wikipedia.org/wiki/List_of_Nvidia_graphics_processing_units.
Some notebook computers add additional graphics processing units to those built into the chipset or processor. Optimus combines Intel® and NVIDIA hardware. Switchable Graphics or Hybrid Graphics are a combination of an Intel® or AMD® processor and an AMD® Radeon GPU.
Implementations of these hybrid graphics systems vary, and Xorg on FreeBSD is not able to drive all versions of them.
Some computers provide a BIOS option to disable one of the graphics adapters or select a discrete mode which can be used with one of the standard video card drivers. For example, it is sometimes possible to disable the NVIDIA GPU in an Optimus system. The Intel® video can then be used with an Intel® driver.
BIOS settings depend on the model
of computer. In some situations, both
GPUs can be left enabled, but
creating a configuration file that only uses the main
GPU in the Device
section is enough to make such a system
functional.
Drivers for some less-common video cards can be
found in the x11-drivers
directory
of the Ports Collection.
Cards that are not supported by a specific driver might still be usable with the x11-drivers/xf86-video-vesa driver. This driver is installed by x11/xorg. It can also be installed manually as x11-drivers/xf86-video-vesa. Xorg attempts to use this driver when a specific driver is not found for the video card.
x11-drivers/xf86-video-scfb is a similar nonspecialized video driver that works on many UEFI and ARM® computers.
To set the Intel® driver in a configuration file:
/usr/local/etc/X11/xorg.conf.d/driver-intel.conf
Section "Device" Identifier "Card0" Driver "intel" # BusID "PCI:1:0:0" EndSection
If more than one video card is present, the
BusID
identifier can be uncommented
and set to select the desired card. A list of video
card bus IDs can be displayed with
pciconf -lv | grep -B3
display
.
To set the Radeon driver in a configuration file:
/usr/local/etc/X11/xorg.conf.d/driver-radeon.conf
Section "Device" Identifier "Card0" Driver "radeon" EndSection
To set the VESA driver in a configuration file:
/usr/local/etc/X11/xorg.conf.d/driver-vesa.conf
Section "Device" Identifier "Card0" Driver "vesa" EndSection
To set the scfb
driver for use
with a UEFI or ARM® computer:
scfb
Video Driver in a
File/usr/local/etc/X11/xorg.conf.d/driver-scfb.conf
Section "Device" Identifier "Card0" Driver "scfb" EndSection
Almost all monitors support the Extended Display Identification Data standard (EDID). Xorg uses EDID to communicate with the monitor and detect the supported resolutions and refresh rates. Then it selects the most appropriate combination of settings to use with that monitor.
Other resolutions supported by the monitor can be chosen by setting the desired resolution in configuration files, or after the X server has been started with xrandr(1).
Run xrandr(1) without any parameters to see a list of video outputs and detected monitor modes:
%
xrandr
Screen 0: minimum 320 x 200, current 3000 x 1920, maximum 8192 x 8192 DVI-0 connected primary 1920x1200+1080+0 (normal left inverted right x axis y axis) 495mm x 310mm 1920x1200 59.95*+ 1600x1200 60.00 1280x1024 85.02 75.02 60.02 1280x960 60.00 1152x864 75.00 1024x768 85.00 75.08 70.07 60.00 832x624 74.55 800x600 75.00 60.32 640x480 75.00 60.00 720x400 70.08 DisplayPort-0 disconnected (normal left inverted right x axis y axis) HDMI-0 disconnected (normal left inverted right x axis y axis)
This shows that the DVI-0
output
is being used to display a screen resolution of
1920x1200 pixels at a refresh rate of about 60 Hz.
Monitors are not attached to the
DisplayPort-0
and
HDMI-0
connectors.
Any of the other display modes can be selected with xrandr(1). For example, to switch to 1280x1024 at 60 Hz:
%
xrandr --mode 1280x1024 --rate 60
A common task is using the external video output on a notebook computer for a video projector.
The type and quantity of output connectors varies
between devices, and the name given to each output
varies from driver to driver. What one driver calls
HDMI-1
, another might call
HDMI1
. So the first step is to run
xrandr(1) to list all the available
outputs:
%
xrandr
Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192 LVDS1 connected 1366x768+0+0 (normal left inverted right x axis y axis) 344mm x 193mm 1366x768 60.04*+ 1024x768 60.00 800x600 60.32 56.25 640x480 59.94 VGA1 connected (normal left inverted right x axis y axis) 1280x1024 60.02 + 75.02 1280x960 60.00 1152x864 75.00 1024x768 75.08 70.07 60.00 832x624 74.55 800x600 72.19 75.00 60.32 56.25 640x480 75.00 72.81 66.67 60.00 720x400 70.08 HDMI1 disconnected (normal left inverted right x axis y axis) DP1 disconnected (normal left inverted right x axis y axis)
Four outputs were found: the built-in panel
LVDS1
, and external
VGA1
, HDMI1
, and
DP1
connectors.
The projector has been connected to the
VGA1
output. xrandr(1) is now
used to set that output to the native resolution of the
projector and add the additional space to the right side
of the desktop:
%
xrandr --output VGA1 --auto --right-of LVDS1
--auto
chooses the resolution and
refresh rate detected by EDID. If
the resolution is not correctly detected, a fixed value
can be given with --mode
instead of
the --auto
statement. For example,
most projectors can be used with a 1024x768 resolution,
which is set with
--mode 1024x768
.
xrandr(1) is often run from
.xinitrc
to set the appropriate
mode when X starts.
To set a screen resolution of 1024x768 in a configuration file:
/usr/local/etc/X11/xorg.conf.d/screen-resolution.conf
Section "Screen" Identifier "Screen0" Device "Card0" SubSection "Display" Modes "1024x768" EndSubSection EndSection
The few monitors that do not have
EDID can be configured by setting
HorizSync
and
VertRefresh
to the range of
frequencies supported by the monitor.
/usr/local/etc/X11/xorg.conf.d/monitor0-freq.conf
Section "Monitor" Identifier "Monitor0" HorizSync 30-83 # kHz VertRefresh 50-76 # Hz EndSection
The standardized location of keys on a keyboard is called a layout. Layouts and other adjustable parameters are listed in xkeyboard-config(7).
A United States layout is the default. To select
an alternate layout, set the
XkbLayout
and
XkbVariant
options in an
InputClass
. This will be applied
to all input devices that match the class.
This example selects a French keyboard layout with
the oss
variant.
/usr/local/etc/X11/xorg.conf.d/keyboard-fr-oss.conf
Section "InputClass" Identifier "KeyboardDefaults" Driver "keyboard" MatchIsKeyboard "on" Option "XkbLayout" "fr" Option "XkbVariant" "oss" EndSection
Set United States, Spanish, and Ukrainian keyboard layouts. Cycle through these layouts by pressing Alt+Shift. x11/xxkb or x11/sbxkb can be used for improved layout switching control and current layout indicators.
/usr/local/etc/X11/xorg.conf.d/kbd-layout-multi.conf
Section "InputClass" Identifier "All Keyboards" MatchIsKeyboard "yes" Option "XkbLayout" "us, es, ua" EndSection
X can be closed with a combination of keys.
By default, that key combination is not set because it
conflicts with keyboard commands for some
applications. Enabling this option requires changes
to the keyboard InputDevice
section:
/usr/local/etc/X11/xorg.conf.d/keyboard-zap.conf
Section "InputClass" Identifier "KeyboardDefaults" Driver "keyboard" MatchIsKeyboard "on" Option "XkbOptions" "terminate:ctrl_alt_bksp" EndSection
Many mouse parameters can be adjusted with configuration options. See mousedrv(4) for a full list.
The number of buttons on a mouse can be set in the
mouse InputDevice
section of
xorg.conf
. To set the number of
buttons to 7:
/usr/local/etc/X11/xorg.conf.d/mouse0-buttons.conf
Section "InputDevice" Identifier "Mouse0" Option "Buttons" "7" EndSection
In some cases, Xorg autoconfiguration does not work with particular hardware, or a different configuration is desired. For these cases, a custom configuration file can be created.
Do not create manual configuration files unless required. Unnecessary manual configuration can prevent proper operation.
A configuration file can be generated by Xorg based on the detected hardware. This file is often a useful starting point for custom configurations.
Generating an xorg.conf
:
#
Xorg -configure
The configuration file is saved to
/root/xorg.conf.new
. Make any changes
desired, then test that file with:
#
Xorg -config /root/xorg.conf.new
After the new configuration has been adjusted and tested,
it can be split into smaller files in the normal location,
/usr/local/etc/X11/xorg.conf.d/
.
The default fonts that ship with Xorg are less than ideal for typical desktop publishing applications. Large presentation fonts show up jagged and unprofessional looking, and small fonts are almost completely unintelligible. However, there are several free, high quality Type1 (PostScript®) fonts available which can be readily used with Xorg. For instance, the URW font collection (x11-fonts/urwfonts) includes high quality versions of standard type1 fonts (Times Roman®, Helvetica®, Palatino® and others). The Freefonts collection (x11-fonts/freefonts) includes many more fonts, but most of them are intended for use in graphics software such as the Gimp, and are not complete enough to serve as screen fonts. In addition, Xorg can be configured to use TrueType® fonts with a minimum of effort. For more details on this, see the X(7) manual page or Section 5.5.2, “TrueType® Fonts”.
To install the above Type1 font collections from binary packages, run the following commands:
#
pkg install urwfonts
Alternatively, to build from the Ports Collection, run the following commands:
#
cd /usr/ports/x11-fonts/urwfonts
#
make install clean
And likewise with the freefont or other collections. To
have the X server detect these fonts, add an appropriate line
to the X server configuration file
(/etc/X11/xorg.conf
), which reads:
FontPath "/usr/local/share/fonts/urwfonts/"
Alternatively, at the command line in the X session run:
%
xset fp+ /usr/local/share/fonts/urwfonts
%
xset fp rehash
This will work but will be lost when the X session is
closed, unless it is added to the startup file
(~/.xinitrc
for a normal
startx
session, or
~/.xsession
when logging in through a
graphical login manager like XDM).
A third way is to use the new
/usr/local/etc/fonts/local.conf
as
demonstrated in Section 5.5.3, “Anti-Aliased Fonts”.
Xorg has built in support for
rendering TrueType® fonts. There are two different modules
that can enable this functionality. The freetype module is
used in this example because it is more consistent with the
other font rendering back-ends. To enable the freetype module
just add the following line to the "Module"
section of /etc/X11/xorg.conf
.
Load "freetype"
Now make a directory for the TrueType® fonts (for
example, /usr/local/share/fonts/TrueType
)
and copy all of the TrueType® fonts into this directory.
Keep in mind that TrueType® fonts cannot be directly taken
from an Apple® Mac®; they must be in
UNIX®/MS-DOS®/Windows® format for use by
Xorg. Once the files have been
copied into this directory, use
mkfontscale to create a
fonts.dir
, so that the X font renderer
knows that these new files have been installed.
mkfontscale
can be installed as a
package:
#
pkg install mkfontscale
Then create an index of X font files in a directory:
#
cd /usr/local/share/fonts/TrueType
#
mkfontscale
Now add the TrueType® directory to the font path. This is just the same as described in Section 5.5.1, “Type1 Fonts”:
%
xset fp+ /usr/local/share/fonts/TrueType
%
xset fp rehash
or add a FontPath
line to
xorg.conf
.
Now Gimp, Apache OpenOffice, and all of the other X applications should now recognize the installed TrueType® fonts. Extremely small fonts (as with text in a high resolution display on a web page) and extremely large fonts (within StarOffice™) will look much better now.
All fonts in Xorg that are
found in /usr/local/share/fonts/
and
~/.fonts/
are automatically made
available for anti-aliasing to Xft-aware applications. Most
recent applications are Xft-aware, including
KDE,
GNOME, and
Firefox.
To control which fonts are anti-aliased, or to
configure anti-aliasing properties, create (or edit, if it
already exists) the file
/usr/local/etc/fonts/local.conf
. Several
advanced features of the Xft font system can be tuned using
this file; this section describes only some simple
possibilities. For more details, please see
fonts-conf(5).
This file must be in XML format. Pay careful attention to
case, and make sure all tags are properly closed. The file
begins with the usual XML header followed by a DOCTYPE
definition, and then the <fontconfig>
tag:
<?xml version="1.0"?> <!DOCTYPE fontconfig SYSTEM "fonts.dtd"> <fontconfig>
As previously stated, all fonts in
/usr/local/share/fonts/
as well as
~/.fonts/
are already made available to
Xft-aware applications. To add another directory
outside of these two directory trees, add a line like
this to
/usr/local/etc/fonts/local.conf
:
<dir>/path/to/my/fonts</dir>
After adding new fonts, and especially new font directories, rebuild the font caches:
#
fc-cache -f
Anti-aliasing makes borders slightly fuzzy, which makes very small text more readable and removes “staircases” from large text, but can cause eyestrain if applied to normal text. To exclude font sizes smaller than 14 point from anti-aliasing, include these lines:
<match target="font"> <test name="size" compare="less"> <double>14</double> </test> <edit name="antialias" mode="assign"> <bool>false</bool> </edit> </match> <match target="font"> <test name="pixelsize" compare="less" qual="any"> <double>14</double> </test> <edit mode="assign" name="antialias"> <bool>false</bool> </edit> </match>
Spacing for some monospaced fonts might also be inappropriate with anti-aliasing. This seems to be an issue with KDE, in particular. One possible fix is to force the spacing for such fonts to be 100. Add these lines:
<match target="pattern" name="family"> <test qual="any" name="family"> <string>fixed</string> </test> <edit name="family" mode="assign"> <string>mono</string> </edit> </match> <match target="pattern" name="family"> <test qual="any" name="family"> <string>console</string> </test> <edit name="family" mode="assign"> <string>mono</string> </edit> </match>
(this aliases the other common names for fixed fonts as
"mono"
), and then add:
<match target="pattern" name="family"> <test qual="any" name="family"> <string>mono</string> </test> <edit name="spacing" mode="assign"> <int>100</int> </edit> </match>
Certain fonts, such as Helvetica, may have a problem when
anti-aliased. Usually this manifests itself as a font that
seems cut in half vertically. At worst, it may cause
applications to crash. To avoid this, consider adding the
following to local.conf
:
<match target="pattern" name="family"> <test qual="any" name="family"> <string>Helvetica</string> </test> <edit name="family" mode="assign"> <string>sans-serif</string> </edit> </match>
After editing
local.conf
, make certain to end the file
with the </fontconfig>
tag. Not
doing this will cause changes to be ignored.
Users can add personalized settings by creating their own
~/.config/fontconfig/fonts.conf
. This
file uses the same XML format described
above.
One last point: with an LCD screen, sub-pixel sampling may
be desired. This basically treats the (horizontally
separated) red, green and blue components separately to
improve the horizontal resolution; the results can be
dramatic. To enable this, add the line somewhere in
local.conf
:
<match target="font"> <test qual="all" name="rgba"> <const>unknown</const> </test> <edit name="rgba" mode="assign"> <const>rgb</const> </edit> </match>
Depending on the sort of display,
rgb
may need to be changed to
bgr
, vrgb
or
vbgr
: experiment and see which works
best.
Xorg provides an X Display Manager, XDM, which can be used for login session management. XDM provides a graphical interface for choosing which display server to connect to and for entering authorization information such as a login and password combination.
This section demonstrates how to configure the X Display Manager on FreeBSD. Some desktop environments provide their own graphical login manager. Refer to Section 5.7.1, “GNOME” for instructions on how to configure the GNOME Display Manager and Section 5.7.2, “KDE” for instructions on how to configure the KDE Display Manager.
To install XDM, use the
x11/xdm package or port. Once installed,
XDM can be configured to run when
the machine boots up by editing this entry in
/etc/ttys
:
ttyv8 "/usr/local/bin/xdm -nodaemon" xterm off secure
Change the off
to on
and save the edit. The ttyv8
in this entry
indicates that XDM will run on the
ninth virtual terminal.
The XDM configuration directory
is located in /usr/local/etc/X11/xdm
.
This directory contains several files used to change the
behavior and appearance of XDM, as
well as a few scripts and programs used to set up the desktop
when XDM is running. Table 5.1, “XDM Configuration Files” summarizes the function of each
of these files. The exact syntax and usage of these files is
described in xdm(1).
File | Description |
---|---|
Xaccess | The protocol for connecting to XDM is called the X Display Manager Connection Protocol (XDMCP) This file is a client authorization ruleset for controlling XDMCP connections from remote machines. By default, this file does not allow any remote clients to connect. |
Xresources | This file controls the look and feel of the XDM display chooser and login screens. The default configuration is a simple rectangular login window with the hostname of the machine displayed at the top in a large font and “Login:” and “Password:” prompts below. The format of this file is identical to the app-defaults file described in the Xorg documentation. |
Xservers | The list of local and remote displays the chooser should provide as login choices. |
Xsession | Default session script for logins which is run by
XDM after a user has logged
in. This points to a customized session
script in ~/.xsession . |
Xsetup_ * | Script to automatically launch applications
before displaying the chooser or login interfaces.
There is a script for each display being used, named
Xsetup_* , where
* is the local display number.
Typically these scripts run one or two programs in the
background such as
xconsole . |
xdm-config | Global configuration for all displays running on this machine. |
xdm-errors | Contains errors generated by the server program.
If a display that XDM is
trying to start hangs, look at this file for error
messages. These messages are also written to the
user's ~/.xsession-errors on a
per-session basis. |
xdm-pid | The running process ID of XDM. |
By default, only users on the same system can login using XDM. To enable users on other systems to connect to the display server, edit the access control rules and enable the connection listener.
To configure XDM to listen for
any remote connection, comment out the
DisplayManager.requestPort
line in
/usr/local/etc/X11/xdm/xdm-config
by
putting a !
in front of it:
! SECURITY: do not listen for XDMCP or Chooser requests ! Comment out this line if you want to manage X terminals with xdm DisplayManager.requestPort: 0
Save the edits and restart XDM.
To restrict remote access, look at the example entries in
/usr/local/etc/X11/xdm/Xaccess
and refer
to xdm(1) for further information.
This section describes how to install three popular desktop
environments on a FreeBSD system. A desktop environment can range
from a simple window manager to a complete suite of desktop
applications. Over a hundred desktop environments are available
in the x11-wm
category of the Ports
Collection.
GNOME is a user-friendly desktop environment. It includes a panel for starting applications and displaying status, a desktop, a set of tools and applications, and a set of conventions that make it easy for applications to cooperate and be consistent with each other. More information regarding GNOME on FreeBSD can be found at https://www.FreeBSD.org/gnome. That web site contains additional documentation about installing, configuring, and managing GNOME on FreeBSD.
This desktop environment can be installed from a package:
#
pkg install gnome3
To instead build GNOME from ports, use the following command. GNOME is a large application and will take some time to compile, even on a fast computer.
#
cd /usr/ports/x11/gnome3
#
make install clean
GNOME
requires /proc
to be mounted. Add this
line to /etc/fstab
to mount this file
system automatically during system startup:
proc /proc procfs rw 0 0
GNOME uses
D-Bus and
HAL for a message bus and hardware
abstraction. These applications are automatically installed
as dependencies of GNOME. Enable
them in /etc/rc.conf
so they will be
started when the system boots:
dbus_enable="YES" hald_enable="YES"
After installation,
configure Xorg to start
GNOME. The easiest way to do this
is to enable the GNOME Display Manager,
GDM, which is installed as part of
the GNOME package or port. It can
be enabled by adding this line to
/etc/rc.conf
:
gdm_enable="YES"
It is often desirable to also start all
GNOME services. To achieve this,
add a second line to /etc/rc.conf
:
gnome_enable="YES"
GDM will start automatically when the system boots.
A second method for starting
GNOME is to type
startx
from the command-line after
configuring ~/.xinitrc
. If this file
already exists, replace the line that starts the current
window manager with one that starts
/usr/local/bin/gnome-session
. If this
file does not exist, create it with this command:
%
echo "exec /usr/local/bin/gnome-session" > ~/.xinitrc
A third method is to use XDM as
the display manager. In this case, create an executable
~/.xsession
:
%
echo "exec /usr/local/bin/gnome-session" > ~/.xsession
KDE is another easy-to-use desktop environment. This desktop provides a suite of applications with a consistent look and feel, a standardized menu and toolbars, keybindings, color-schemes, internationalization, and a centralized, dialog-driven desktop configuration. More information on KDE can be found at http://www.kde.org/. For FreeBSD-specific information, consult http://freebsd.kde.org.
To install the KDE package, type:
#
pkg install x11/kde5
To instead build the KDE port, use the following command. Installing the port will provide a menu for selecting which components to install. KDE is a large application and will take some time to compile, even on a fast computer.
#
cd /usr/ports/x11/kde5
#
make install clean
KDE requires
/proc
to be mounted. Add this line to
/etc/fstab
to mount this file system
automatically during system startup:
proc /proc procfs rw 0 0
KDE uses
D-Bus and
HAL for a message bus and hardware
abstraction. These applications are automatically installed
as dependencies of KDE. Enable
them in /etc/rc.conf
so they will be
started when the system boots:
dbus_enable="YES" hald_enable="YES"
Since KDE Plasma 5, the KDE Display Manager, KDM is no longer developed. A possible replacement is SDDM. To install it, type:
#
pkg install x11/sddm
Add this line to
/etc/rc.conf
:
sddm_enable="YES"
A second method for launching
KDE is to type
startx
from the command line. For this to
work, the following line is needed in
~/.xinitrc
:
exec ck-launch-session startkde
A third method for starting KDE
is through XDM. To do so, create
an executable ~/.xsession
as
follows:
%
echo "exec ck-launch-session startkde" > ~/.xsession
Once KDE is started, refer to its built-in help system for more information on how to use its various menus and applications.
Xfce is a desktop environment based on the GTK+ toolkit used by GNOME. However, it is more lightweight and provides a simple, efficient, easy-to-use desktop. It is fully configurable, has a main panel with menus, applets, and application launchers, provides a file manager and sound manager, and is themeable. Since it is fast, light, and efficient, it is ideal for older or slower machines with memory limitations. More information on Xfce can be found at http://www.xfce.org.
To install the Xfce package:
#
pkg install xfce
Alternatively, to build the port:
#
cd /usr/ports/x11-wm/xfce4
#
make install clean
Xfce uses
D-Bus for a message bus. This
application is automatically installed as dependency of
Xfce. Enable it in
/etc/rc.conf
so it will be started when
the system boots:
dbus_enable="YES"
Unlike GNOME or
KDE,
Xfce does not provide its own login
manager. In order to start Xfce
from the command line by typing startx
,
first create ~/.xinitrc
with this
command:
%
echo ". /usr/local/etc/xdg/xfce4/xinitrc" > ~/.xinitrc
An alternate method is to use
XDM. To configure this method,
create an executable ~/.xsession
:
%
echo ". /usr/local/etc/xdg/xfce4/xinitrc" > ~/.xsession
One way to make using a desktop computer more pleasant is with nice 3D effects.
Installing the Compiz Fusion package is easy, but configuring it requires a few steps that are not described in the port's documentation.
Desktop effects can cause quite a load on the graphics
card. For an nVidia-based graphics card, the proprietary
driver is required for good performance. Users of other
graphics cards can skip this section and continue with the
xorg.conf
configuration.
To determine which nVidia driver is needed see the FAQ question on the subject.
Having determined the correct driver to use for your card, installation is as simple as installing any other package.
For example, to install the latest driver:
#
pkg install x11/nvidia-driver
The driver will create a kernel module, which needs to be
loaded at system startup. Add the following line to
/boot/loader.conf
:
nvidia_load="YES"
To immediately load the kernel module into the running
kernel issue a command like kldload
nvidia
. However, it has been noted that some
versions of Xorg will not
function properly if the driver is not loaded at boot time.
After editing /boot/loader.conf
, a
reboot is recommended.
With the kernel module loaded, you normally only need to
change a single line in xorg.conf
to enable the proprietary driver:
Find the following line in
/etc/X11/xorg.conf
:
Driver "nv"
and change it to:
Driver "nvidia"
Start the GUI as usual, and you should be greeted by the nVidia splash. Everything should work as usual.
To enable Compiz Fusion,
/etc/X11/xorg.conf
needs to be
modified:
Add the following section to enable composite effects:
Section "Extensions" Option "Composite" "Enable" EndSection
Locate the “Screen” section which should look similar to the one below:
Section "Screen" Identifier "Screen0" Device "Card0" Monitor "Monitor0" ...
and add the following two lines (after “Monitor” will do):
DefaultDepth 24 Option "AddARGBGLXVisuals" "True"
Locate the “Subsection” that refers to the screen resolution that you wish to use. For example, if you wish to use 1280x1024, locate the section that follows. If the desired resolution does not appear in any subsection, you may add the relevant entry by hand:
SubSection "Display" Viewport 0 0 Modes "1280x1024" EndSubSection
A color depth of 24 bits is needed for desktop composition, change the above subsection to:
SubSection "Display" Viewport 0 0 Depth 24 Modes "1280x1024" EndSubSection
Finally, confirm that the “glx” and “extmod” modules are loaded in the “Module” section:
Section "Module" Load "extmod" Load "glx" ...
The preceding can be done automatically with x11/nvidia-xconfig by running (as root):
#
nvidia-xconfig --add-argb-glx-visuals
#
nvidia-xconfig --composite
#
nvidia-xconfig --depth=24
Installing Compiz Fusion is as simple as any other package:
#
pkg install x11-wm/compiz-fusion
When the installation is finished, start your graphic desktop and at a terminal, enter the following commands (as a normal user):
%
compiz --replace --sm-disable --ignore-desktop-hints ccp &
%
emerald --replace &
Your screen will flicker for a few seconds, as your window manager (e.g. Metacity if you are using GNOME) is replaced by Compiz Fusion. Emerald takes care of the window decorations (i.e. close, minimize, maximize buttons, title bars and so on).
You may convert this to a trivial script and have it run at startup automatically (e.g. by adding to “Sessions” in a GNOME desktop):
#! /bin/sh compiz --replace --sm-disable --ignore-desktop-hints ccp & emerald --replace &
Save this in your home directory as, for example,
start-compiz
and make it
executable:
%
chmod +x ~/start-compiz
Then use the GUI to add it to GNOME desktop).
(located in , , on aTo actually select all the desired effects and their settings, execute (again as a normal user) the Compiz Config Settings Manager:
%
ccsm
In GNOME, this can also be found in the , menu.
If you have selected “gconf support” during
the build, you will also be able to view these settings using
gconf-editor
under
apps/compiz
.
If the mouse does not work, you will need to first configure
it before proceeding.
In recent Xorg
versions, the InputDevice
sections in
xorg.conf
are ignored in favor of the
autodetected devices. To restore the old behavior, add the
following line to the ServerLayout
or
ServerFlags
section of this file:
Option "AutoAddDevices" "false"
Input devices may then be configured as in previous versions, along with any other options needed (e.g., keyboard layout switching).
As previously explained the hald daemon will, by default, automatically detect your keyboard. There are chances that your keyboard layout or model will not be correct, desktop environments like GNOME, KDE or Xfce provide tools to configure the keyboard. However, it is possible to set the keyboard properties directly either with the help of the setxkbmap(1) utility or with a hald's configuration rule.
For example if, one wants to use a PC 102 keys keyboard
coming with a french layout, we have to create a keyboard
configuration file for hald
called x11-input.fdi
and saved in the
/usr/local/etc/hal/fdi/policy
directory. This file should contain the following
lines:
<?xml version="1.0" encoding="iso-8859-1"?> <deviceinfo version="0.2"> <device> <match key="info.capabilities" contains="input.keyboard"> <merge key="input.x11_options.XkbModel" type="string">pc102</merge> <merge key="input.x11_options.XkbLayout" type="string">fr</merge> </match> </device> </deviceinfo>
If this file already exists, just copy and add to your file the lines regarding the keyboard configuration.
You will have to reboot your machine to force hald to read this file.
It is possible to do the same configuration from an X terminal or a script with this command line:
%
setxkbmap -model pc102 -layout fr
/usr/local/share/X11/xkb/rules/base.lst
lists the various keyboard, layouts and options
available.
The xorg.conf.new
configuration file
may now be tuned to taste. Open the file in a text editor
such as emacs(1) or ee(1). If the monitor is an
older or unusual model that does not support autodetection of
sync frequencies, those settings can be added to
xorg.conf.new
under the
"Monitor"
section:
Section "Monitor" Identifier "Monitor0" VendorName "Monitor Vendor" ModelName "Monitor Model" HorizSync 30-107 VertRefresh 48-120 EndSection
Most monitors support sync frequency autodetection, making manual entry of these values unnecessary. For the few monitors that do not support autodetection, avoid potential damage by only entering values provided by the manufacturer.
X allows DPMS (Energy Star) features to be used with capable monitors. The xset(1) program controls the time-outs and can force standby, suspend, or off modes. If you wish to enable DPMS features for your monitor, you must add the following line to the monitor section:
Option "DPMS"
While the xorg.conf.new
configuration
file is still open in an editor, select the default resolution
and color depth desired. This is defined in the
"Screen"
section:
Section "Screen" Identifier "Screen0" Device "Card0" Monitor "Monitor0" DefaultDepth 24 SubSection "Display" Viewport 0 0 Depth 24 Modes "1024x768" EndSubSection EndSection
The DefaultDepth
keyword describes the
color depth to run at by default. This can be overridden with
the -depth
command line switch to
Xorg(1). The Modes
keyword describes
the resolution to run at for the given color depth. Note that
only VESA standard modes are supported as defined by the
target system's graphics hardware. In the example above, the
default color depth is twenty-four bits per pixel. At this
color depth, the accepted resolution is 1024 by 768
pixels.
Finally, write the configuration file and test it using the test mode given above.
One of the tools available to assist you during
troubleshooting process are the
Xorg log files, which contain
information on each device that the
Xorg server attaches to.
Xorg log file names are in the
format of /var/log/Xorg.0.log
. The
exact name of the log can vary from
Xorg.0.log
to
Xorg.8.log
and so forth.
If all is well, the configuration file needs to be
installed in a common location where Xorg(1) can find it.
This is typically /etc/X11/xorg.conf
or
/usr/local/etc/X11/xorg.conf
.
#
cp xorg.conf.new /etc/X11/xorg.conf
The Xorg configuration process is now complete. Xorg may be now started with the startx(1) utility. The Xorg server may also be started with the use of xdm(1).
Configuration with Intel® i810 integrated chipsets
requires the agpgart
AGP programming
interface for Xorg to drive the
card. See the agp(4) driver manual page for more
information.
This will allow configuration of the hardware as any
other graphics board. Note on systems without the
agp(4) driver compiled in the kernel, trying to load
the module with kldload(8) will not work. This driver
has to be in the kernel at boot time through being compiled
in or using /boot/loader.conf
.
This section assumes a bit of advanced configuration knowledge. If attempts to use the standard configuration tools above have not resulted in a working configuration, there is information enough in the log files to be of use in getting the setup working. Use of a text editor will be necessary.
Current widescreen (WSXGA, WSXGA+, WUXGA, WXGA, WXGA+, et.al.) formats support 16:10 and 10:9 formats or aspect ratios that can be problematic. Examples of some common screen resolutions for 16:10 aspect ratios are:
2560x1600
1920x1200
1680x1050
1440x900
1280x800
At some point, it will be as easy as adding one of these
resolutions as a possible Mode
in the
Section "Screen"
as such:
Section "Screen" Identifier "Screen0" Device "Card0" Monitor "Monitor0" DefaultDepth 24 SubSection "Display" Viewport 0 0 Depth 24 Modes "1680x1050" EndSubSection EndSection
Xorg is smart enough to pull the resolution information from the widescreen via I2C/DDC information so it knows what the monitor can handle as far as frequencies and resolutions.
If those ModeLines
do not exist in
the drivers, one might need to give
Xorg a little hint. Using
/var/log/Xorg.0.log
one can extract
enough information to manually create a
ModeLine
that will work. Simply look for
information resembling this:
(II) MGA(0): Supported additional Video Mode: (II) MGA(0): clock: 146.2 MHz Image Size: 433 x 271 mm (II) MGA(0): h_active: 1680 h_sync: 1784 h_sync_end 1960 h_blank_end 2240 h_border: 0 (II) MGA(0): v_active: 1050 v_sync: 1053 v_sync_end 1059 v_blanking: 1089 v_border: 0 (II) MGA(0): Ranges: V min: 48 V max: 85 Hz, H min: 30 H max: 94 kHz, PixClock max 170 MHz
This information is called EDID information. Creating a
ModeLine
from this is just a matter of
putting the numbers in the correct order:
ModeLine <name> <clock> <4 horiz. timings> <4 vert. timings>
So that the ModeLine
in
Section "Monitor"
for this example would
look like this:
Section "Monitor" Identifier "Monitor1" VendorName "Bigname" ModelName "BestModel" ModeLine "1680x1050" 146.2 1680 1784 1960 2240 1050 1053 1059 1089 Option "DPMS" EndSection
Now having completed these simple editing steps, X should start on your new widescreen monitor.
5.9.3.1. | I have installed Compiz Fusion, and after running the commands you mention, my windows are left without title bars and buttons. What is wrong? |
You are probably missing a setting in
| |
5.9.3.2. | When I run the command to start Compiz Fusion, the X server crashes and I am back at the console. What is wrong? |
If you check
(EE) NVIDIA(0): Failed to initialize the GLX module; please check in your X (EE) NVIDIA(0): log file that the GLX module has been loaded in your X (EE) NVIDIA(0): server, and that the module is the NVIDIA GLX module. If (EE) NVIDIA(0): you continue to encounter problems, Please try (EE) NVIDIA(0): reinstalling the NVIDIA driver. This is usually the case when you upgrade Xorg. You will need to reinstall the x11/nvidia-driver package so glx is built again. |
Now that the basics have been covered, this part of the book discusses some frequently used features of FreeBSD. These chapters:
Introduce popular and useful desktop applications: browsers, productivity tools, document viewers, and more.
Introduce a number of multimedia tools available for FreeBSD.
Explain the process of building a customized FreeBSD kernel to enable extra functionality.
Describe the print system in detail, both for desktop and network-connected printer setups.
Show how to run Linux applications on the FreeBSD system.
Some of these chapters recommend prior reading, and this is noted in the synopsis at the beginning of each chapter.
While FreeBSD is popular as a server for its performance and stability, it is also suited for day-to-day use as a desktop. With over 24,000 applications available as FreeBSD packages or ports, it is easy to build a customized desktop that runs a wide variety of desktop applications. This chapter demonstrates how to install numerous desktop applications, including web browsers, productivity software, document viewers, and financial software.
Users who prefer to install a pre-built desktop version of FreeBSD rather than configuring one from scratch should refer to the trueos.org website.
Readers of this chapter should know how to:
Install additional software using packages or ports as described in Chapter 4, Installing Applications: Packages and Ports.
Install X and a window manager as described in Chapter 5, The X Window System.
For information on how to configure a multimedia environment, refer to Chapter 7, Multimedia.
FreeBSD does not come with a pre-installed web browser. Instead, the www category of the Ports Collection contains many browsers which can be installed as a package or compiled from the Ports Collection.
The KDE and GNOME desktop environments include their own HTML browser. Refer to Section 5.7, “Desktop Environments” for more information on how to set up these complete desktops.
Some lightweight browsers include www/dillo2, www/links, and www/w3m.
This section demonstrates how to install the following popular web browsers and indicates if the application is resource-heavy, takes time to compile from ports, or has any major dependencies.
Application Name | Resources Needed | Installation from Ports | Notes |
---|---|---|---|
Firefox | medium | heavy | FreeBSD, Linux®, and localized versions are available |
Opera | light | light | FreeBSD and Linux® versions are available |
Konqueror | medium | heavy | Requires KDE libraries |
Chromium | medium | heavy | Requires Gtk+ |
Firefox is an open source browser that features a standards-compliant HTML display engine, tabbed browsing, popup blocking, extensions, improved security, and more. Firefox is based on the Mozilla codebase.
To install the package of the latest release version of Firefox, type:
#
pkg install firefox
To instead install Firefox Extended Support Release (ESR) version, use:
#
pkg install firefox-esr
Localized versions are available in www/firefox-i18n and www/firefox-esr-i18n.
The Ports Collection can instead be used to compile the
desired version of Firefox from
source code. This example builds
www/firefox, where
firefox
can be replaced with the ESR or
localized version to install.
#
cd /usr/ports/www/firefox
#
make install clean
Opera is a full-featured and standards-compliant browser which is still lightweight and fast. It comes with a built-in mail and news reader, an IRC client, an RSS/Atom feeds reader, and more. It is available as a native FreeBSD version and as a version that runs under Linux® emulation.
This command installs the package of the FreeBSD version of
Opera. Replace
opera
with linux-opera
to instead install the Linux® version.
#
pkg install opera
Alternately, install either version through the Ports Collection. This example compiles the native version:
#
cd /usr/ports/www/opera
#
make install clean
To install the Linux® version, substitute
linux-opera
in place of
opera
.
To install Adobe® Flash® plugin support, first compile the www/linux-flashplayer port. Licensing restrictions prevent making a package available. Then install www/opera-linuxplugins. This example compiles both applications from ports:
#
cd /usr/ports/www/linux-flashplayer
#
make install clean
#
cd /usr/ports/www/opera-linuxplugins
#
make install clean
Once installed, check the presence of the plugin by
starting the browser, entering
opera:plugins
in the location bar and
pressing Enter. A list should appear with
all the currently available plugins.
To add the Java™ plugin, follow install java/icedtea-web.
Konqueror is more than a web browser as it is also a file manager and a multimedia viewer. It is included in the x11/kde4-baseapps package or port.
Konqueror supports WebKit as well as its own KHTML. WebKit is a rendering engine used by many modern browsers including Chromium. To use WebKit with Konqueror on FreeBSD, install the www/kwebkitpart package or port. This example installs the package:
#
pkg install kwebkitpart
To install from the Ports Collection:
#
cd /usr/ports/www/kwebkitpart
#
make install clean
To enable WebKit within Konqueror, click “Settings”, “Configure Konqueror”. In the “General” settings page, click the drop-down menu next to “Default web browser engine” and change “KHTML” to “WebKit”.
Konqueror also supports
Flash®. A “How To”
guide for getting Flash® support
on Konqueror is available at http://freebsd.kde.org/howtos/konqueror-flash.php
.
Chromium is an open source browser project that aims to build a safer, faster, and more stable web browsing experience. Chromium features tabbed browsing, popup blocking, extensions, and much more. Chromium is the open source project upon which the Google Chrome web browser is based.
Chromium can be installed as a package by typing:
#
pkg install chromium
Alternatively, Chromium can be compiled from source using the Ports Collection:
#
cd /usr/ports/www/chromium
#
make install clean
The executable for Chromium
is /usr/local/bin/chrome
, not
/usr/local/bin/chromium
.
When it comes to productivity, users often look for an office suite or an easy-to-use word processor. While some desktop environments like KDE provide an office suite, there is no default productivity package. Several office suites and graphical word processors are available for FreeBSD, regardless of the installed window manager.
This section demonstrates how to install the following popular productivity software and indicates if the application is resource-heavy, takes time to compile from ports, or has any major dependencies.
Application Name | Resources Needed | Installation from Ports | Major Dependencies |
---|---|---|---|
Calligra | light | heavy | KDE |
AbiWord | light | light | Gtk+ or GNOME |
The Gimp | light | heavy | Gtk+ |
Apache OpenOffice | heavy | huge | JDK™ and Mozilla |
LibreOffice | somewhat heavy | huge | Gtk+, or KDE/ GNOME, or JDK™ |
The KDE desktop environment includes an office suite which can be installed separately from KDE. Calligra includes standard components that can be found in other office suites. Words is the word processor, Sheets is the spreadsheet program, Stage manages slide presentations, and Karbon is used to draw graphical documents.
In FreeBSD, editors/calligra can be installed as a package or a port. To install the package:
#
pkg install calligra
If the package is not available, use the Ports Collection instead:
#
cd /usr/ports/editors/calligra
#
make install clean
AbiWord is a free word processing program similar in look and feel to Microsoft® Word. It is fast, contains many features, and is user-friendly.
AbiWord can import or export
many file formats, including some proprietary ones like
Microsoft® .rtf
.
To install the AbiWord package:
#
pkg install abiword
If the package is not available, it can be compiled from the Ports Collection:
#
cd /usr/ports/editors/abiword
#
make install clean
For image authoring or picture retouching, The GIMP provides a sophisticated image manipulation program. It can be used as a simple paint program or as a quality photo retouching suite. It supports a large number of plugins and features a scripting interface. The GIMP can read and write a wide range of file formats and supports interfaces with scanners and tablets.
To install the package:
#
pkg install gimp
Alternately, use the Ports Collection:
#
cd /usr/ports/graphics/gimp
#
make install clean
The graphics category (freebsd.org/ports/graphics.html) of the Ports Collection contains several GIMP-related plugins, help files, and user manuals.
Apache OpenOffice is an open source office suite which is developed under the wing of the Apache Software Foundation's Incubator. It includes all of the applications found in a complete office productivity suite: a word processor, spreadsheet, presentation manager, and drawing program. Its user interface is similar to other office suites, and it can import and export in various popular file formats. It is available in a number of different languages and internationalization has been extended to interfaces, spell checkers, and dictionaries.
The word processor of Apache OpenOffice uses a native XML file format for increased portability and flexibility. The spreadsheet program features a macro language which can be interfaced with external databases. Apache OpenOffice is stable and runs natively on Windows®, Solaris™, Linux®, FreeBSD, and Mac OS® X. More information about Apache OpenOffice can be found at openoffice.org. For FreeBSD specific information refer to porting.openoffice.org/freebsd/.
To install the Apache OpenOffice package:
#
pkg install apache-openoffice
Once the package is installed, type the following command to launch Apache OpenOffice:
%
openoffice-
X.Y.Z
where X.Y.Z
is the version
number of the installed version of Apache
OpenOffice. The first time
Apache OpenOffice launches, some
questions will be asked and a
.openoffice.org
folder will be created in
the user's home directory.
If the desired Apache OpenOffice package is not available, compiling the port is still an option. However, this requires a lot of disk space and a fairly long time to compile:
#
cd /usr/ports/editors/openoffice-4
#
make install clean
To build a localized version, replace the previous command with:
#
make LOCALIZED_LANG=
your_language
install clean
Replace
your_language
with the correct
language ISO-code. A list of supported language codes is
available in
files/Makefile.localized
, located in
the port's directory.
LibreOffice is a free software office suite developed by documentfoundation.org. It is compatible with other major office suites and available on a variety of platforms. It is a rebranded fork of Apache OpenOffice and includes applications found in a complete office productivity suite: a word processor, spreadsheet, presentation manager, drawing program, database management program, and a tool for creating and editing mathematical formulæ. It is available in a number of different languages and internationalization has been extended to interfaces, spell checkers, and dictionaries.
The word processor of LibreOffice uses a native XML file format for increased portability and flexibility. The spreadsheet program features a macro language which can be interfaced with external databases. LibreOffice is stable and runs natively on Windows®, Linux®, FreeBSD, and Mac OS® X. More information about LibreOffice can be found at libreoffice.org.
To install the English version of the LibreOffice package:
#
pkg install libreoffice
The editors category (freebsd.org/ports/editors.html)
of the Ports Collection contains several localizations for
LibreOffice. When installing a
localized package, replace libreoffice
with the name of the localized package.
Once the package is installed, type the following command to run LibreOffice:
%
libreoffice
During the first launch, some questions will be asked
and a .libreoffice
folder will be created
in the user's home directory.
If the desired LibreOffice package is not available, compiling the port is still an option. However, this requires a lot of disk space and a fairly long time to compile. This example compiles the English version:
#
cd /usr/ports/editors/libreoffice
#
make install clean
To build a localized version,
cd
into the port directory of
the desired language. Supported languages can be found
in the editors category (freebsd.org/ports/editors.html)
of the Ports Collection.
Some new document formats have gained popularity since the advent of UNIX® and the viewers they require may not be available in the base system. This section demonstrates how to install the following document viewers:
Application Name | Resources Needed | Installation from Ports | Major Dependencies |
---|---|---|---|
Xpdf | light | light | FreeType |
gv | light | light | Xaw3d |
Geeqie | light | light | Gtk+ or GNOME |
ePDFView | light | light | Gtk+ |
Okular | light | heavy | KDE |
For users that prefer a small FreeBSD PDF viewer, Xpdf provides a light-weight and efficient viewer which requires few resources. It uses the standard X fonts and does not require any additional toolkits.
To install the Xpdf package:
#
pkg install xpdf
If the package is not available, use the Ports Collection:
#
cd /usr/ports/graphics/xpdf
#
make install clean
Once the installation is complete, launch
xpdf
and use the right mouse button to
activate the menu.
gv is a PostScript® and PDF viewer. It is based on ghostview, but has a nicer look as it is based on the Xaw3d widget toolkit. gv has many configurable features, such as orientation, paper size, scale, and anti-aliasing. Almost any operation can be performed with either the keyboard or the mouse.
To install gv as a package:
#
pkg install gv
If a package is unavailable, use the Ports Collection:
#
cd /usr/ports/print/gv
#
make install clean
Geeqie is a fork from the unmaintained GQView project, in an effort to move development forward and integrate the existing patches. Geeqie is an image manager which supports viewing a file with a single click, launching an external editor, and thumbnail previews. It also features a slideshow mode and some basic file operations, making it easy to manage image collections and to find duplicate files. Geeqie supports full screen viewing and internationalization.
To install the Geeqie package:
#
pkg install geeqie
If the package is not available, use the Ports Collection:
#
cd /usr/ports/graphics/geeqie
#
make install clean
ePDFView is a lightweight PDF document viewer that only uses the Gtk+ and Poppler libraries. It is currently under development, but already opens most PDF files (even encrypted), save copies of documents, and has support for printing using CUPS.
To install ePDFView as a package:
#
pkg install epdfview
If a package is unavailable, use the Ports Collection:
#
cd /usr/ports/graphics/epdfview
#
make install clean
Okular is a universal document viewer based on KPDF for KDE. It can open many document formats, including PDF, PostScript®, DjVu, CHM, XPS, and ePub.
To install Okular as a package:
#
pkg install okular
If a package is unavailable, use the Ports Collection:
#
cd /usr/ports/graphics/okular
#
make install clean
For managing personal finances on a FreeBSD desktop, some powerful and easy-to-use applications can be installed. Some are compatible with widespread file formats, such as the formats used by Quicken and Excel.
This section covers these programs:
Application Name | Resources Needed | Installation from Ports | Major Dependencies |
---|---|---|---|
GnuCash | light | heavy | GNOME |
Gnumeric | light | heavy | GNOME |
KMyMoney | light | heavy | KDE |
GnuCash is part of the GNOME effort to provide user-friendly, yet powerful, applications to end-users. GnuCash can be used to keep track of income and expenses, bank accounts, and stocks. It features an intuitive interface while remaining professional.
GnuCash provides a smart register, a hierarchical system of accounts, and many keyboard accelerators and auto-completion methods. It can split a single transaction into several more detailed pieces. GnuCash can import and merge Quicken QIF files. It also handles most international date and currency formats.
To install the GnuCash package:
#
pkg install gnucash
If the package is not available, use the Ports Collection:
#
cd /usr/ports/finance/gnucash
#
make install clean
Gnumeric is a spreadsheet program developed by the GNOME community. It features convenient automatic guessing of user input according to the cell format with an autofill system for many sequences. It can import files in a number of popular formats, including Excel, Lotus 1-2-3, and Quattro Pro. It has a large number of built-in functions and allows all of the usual cell formats such as number, currency, date, time, and much more.
To install Gnumeric as a package:
#
pkg install gnumeric
If the package is not available, use the Ports Collection:
#
cd /usr/ports/math/gnumeric
#
make install clean
KMyMoney is a personal finance application created by the KDE community. KMyMoney aims to provide the important features found in commercial personal finance manager applications. It also highlights ease-of-use and proper double-entry accounting among its features. KMyMoney imports from standard Quicken QIF files, tracks investments, handles multiple currencies, and provides a wealth of reports.
To install KMyMoney as a package:
#
pkg install kmymoney-kde4
If the package is not available, use the Ports Collection:
#
cd /usr/ports/finance/kmymoney-kde4
#
make install clean
FreeBSD supports a wide variety of sound cards, allowing users to enjoy high fidelity output from a FreeBSD system. This includes the ability to record and play back audio in the MPEG Audio Layer 3 (MP3), Waveform Audio File (WAV), Ogg Vorbis, and other formats. The FreeBSD Ports Collection contains many applications for editing recorded audio, adding sound effects, and controlling attached MIDI devices.
FreeBSD also supports the playback of video files and DVDs. The FreeBSD Ports Collection contains applications to encode, convert, and playback various video media.
This chapter describes how to configure sound cards, video playback, TV tuner cards, and scanners on FreeBSD. It also describes some of the applications which are available for using these devices.
After reading this chapter, you will know how to:
Configure a sound card on FreeBSD.
Troubleshoot the sound setup.
Playback and encode MP3s and other audio.
Prepare a FreeBSD system for video playback.
Play DVDs, .mpg
,
and .avi
files.
Rip CD and DVD content into files.
Configure a TV card.
Install and setup MythTV on FreeBSD
Configure an image scanner.
Configure a Bluetooth headset.
Before reading this chapter, you should:
Know how to install applications as described in Chapter 4, Installing Applications: Packages and Ports.
Before beginning the configuration, determine the model of the sound card and the chip it uses. FreeBSD supports a wide variety of sound cards. Check the supported audio devices list of the Hardware Notes to see if the card is supported and which FreeBSD driver it uses.
In order to use the sound device, its device driver must be loaded. The easiest way is to load a kernel module for the sound card with kldload(8). This example loads the driver for a built-in audio chipset based on the Intel specification:
#
kldload snd_hda
To automate the loading of this driver at boot time, add the
driver to /boot/loader.conf
. The line for
this driver is:
snd_hda_load="YES"
Other available sound modules are listed in
/boot/defaults/loader.conf
. When unsure
which driver to use, load the snd_driver
module:
#
kldload snd_driver
This is a metadriver which loads all of the most common
sound drivers and can be used to speed up the search for the
correct driver. It is also possible to load all sound drivers
by adding the metadriver to
/boot/loader.conf
.
To determine which driver was selected for the sound card
after loading the snd_driver
metadriver,
type cat /dev/sndstat
.
This section is for users who prefer to statically compile in support for the sound card in a custom kernel. For more information about recompiling a kernel, refer to Chapter 8, Configuring the FreeBSD Kernel.
When using a custom kernel to provide sound support, make sure that the audio framework driver exists in the custom kernel configuration file:
device sound
Next, add support for the sound card. To continue the example of the built-in audio chipset based on the Intel specification from the previous section, use the following line in the custom kernel configuration file:
device snd_hda
Be sure to read the manual page of the driver for the device name to use for the driver.
Non-PnP ISA sound cards may require the IRQ and I/O port
settings of the card to be added to
/boot/device.hints
. During the boot
process, loader(8) reads this file and passes the
settings to the kernel. For example, an old Creative
SoundBlaster® 16 ISA non-PnP card will use the
snd_sbc(4) driver in conjunction with
snd_sb16
. For this card, the following
lines must be added to the kernel configuration file:
device snd_sbc device snd_sb16
If the card uses the 0x220
I/O port and
IRQ 5
, these lines must also be added to
/boot/device.hints
:
hint.sbc.0.at="isa" hint.sbc.0.port="0x220" hint.sbc.0.irq="5" hint.sbc.0.drq="1" hint.sbc.0.flags="0x15"
The syntax used in /boot/device.hints
is described in sound(4) and the manual page for the
driver of the sound card.
The settings shown above are the defaults. In some cases, the IRQ or other settings may need to be changed to match the card. Refer to snd_sbc(4) for more information about this card.
After loading the required module or rebooting into the
custom kernel, the sound card should be detected. To confirm,
run dmesg | grep pcm
. This example is
from a system with a built-in Conexant CX20590 chipset:
pcm0: <NVIDIA (0x001c) (HDMI/DP 8ch)> at nid 5 on hdaa0 pcm1: <NVIDIA (0x001c) (HDMI/DP 8ch)> at nid 6 on hdaa0 pcm2: <Conexant CX20590 (Analog 2.0+HP/2.0)> at nid 31,25 and 35,27 on hdaa1
The status of the sound card may also be checked using this command:
#
cat /dev/sndstat
FreeBSD Audio Driver (newpcm: 64bit 2009061500/amd64) Installed devices: pcm0: <NVIDIA (0x001c) (HDMI/DP 8ch)> (play) pcm1: <NVIDIA (0x001c) (HDMI/DP 8ch)> (play) pcm2: <Conexant CX20590 (Analog 2.0+HP/2.0)> (play/rec) default
The output will vary depending upon the sound card. If no
pcm
devices are listed, double-check
that the correct device driver was loaded or compiled into the
kernel. The next section lists some common problems and their
solutions.
If all goes well, the sound card should now work in FreeBSD. If the CD or DVD drive is properly connected to the sound card, one can insert an audio CD in the drive and play it with cdcontrol(1):
%
cdcontrol -f /dev/acd0 play 1
Audio CDs have specialized encodings which means that they should not be mounted using mount(8).
Various applications, such as audio/workman, provide a friendlier interface. The audio/mpg123 port can be installed to listen to MP3 audio files.
Another quick way to test the card is to send data to
/dev/dsp
:
%
cat
filename
> /dev/dsp
where
can
be any type of file. This command should produce some noise,
confirming that the sound card is working.filename
The /dev/dsp*
device nodes will
be created automatically as needed. When not in use, they
do not exist and will not appear in the output of
ls(1).
Connecting to a Bluetooth device is out of scope for this chapter. Refer to Section 31.5, “Bluetooth” for more information.
To get Bluetooth sound sink working with FreeBSD's sound system, users have to install audio/virtual_oss first:
#
pkg install virtual_oss
audio/virtual_oss requires
cuse
to be loaded into the kernel:
#
kldload cuse
To load cuse
during system startup, run
this command:
#
sysrc -f /boot/loader.conf cuse_load=yes
To use headphones as a sound sink with audio/virtual_oss, users need to create a virtual device after connecting to a Bluetooth audio device:
#
virtual_oss -C 2 -c 2 -r 48000 -b 16 -s 768 -R /dev/null -P /dev/bluetooth/
headphones
-d dsp
headphones
in this example is
a hostname from /etc/bluetooth/hosts
.
BT_ADDR
could be used instead.
Refer to virtual_oss(8) for more information.
Table 7.1, “Common Error Messages” lists some common error messages and their solutions:
Error | Solution |
---|---|
sb_dspwr(XX) timed out | The I/O port is not set correctly. |
bad irq XX | The IRQ is set incorrectly. Make sure that the set IRQ and the sound IRQ are the same. |
xxx: gus pcm not attached, out of memory | There is not enough available memory to use the device. |
xxx: can't open /dev/dsp! | Type |
Modern graphics cards often come with their own sound
driver for use with HDMI. This sound
device is sometimes enumerated before the sound card meaning
that the sound card will not be used as the default playback
device. To check if this is the case, run
dmesg and look for
pcm
. The output looks something like
this:
... hdac0: HDA Driver Revision: 20100226_0142 hdac1: HDA Driver Revision: 20100226_0142 hdac0: HDA Codec #0: NVidia (Unknown) hdac0: HDA Codec #1: NVidia (Unknown) hdac0: HDA Codec #2: NVidia (Unknown) hdac0: HDA Codec #3: NVidia (Unknown) pcm0: <HDA NVidia (Unknown) PCM #0 DisplayPort> at cad 0 nid 1 on hdac0 pcm1: <HDA NVidia (Unknown) PCM #0 DisplayPort> at cad 1 nid 1 on hdac0 pcm2: <HDA NVidia (Unknown) PCM #0 DisplayPort> at cad 2 nid 1 on hdac0 pcm3: <HDA NVidia (Unknown) PCM #0 DisplayPort> at cad 3 nid 1 on hdac0 hdac1: HDA Codec #2: Realtek ALC889 pcm4: <HDA Realtek ALC889 PCM #0 Analog> at cad 2 nid 1 on hdac1 pcm5: <HDA Realtek ALC889 PCM #1 Analog> at cad 2 nid 1 on hdac1 pcm6: <HDA Realtek ALC889 PCM #2 Digital> at cad 2 nid 1 on hdac1 pcm7: <HDA Realtek ALC889 PCM #3 Digital> at cad 2 nid 1 on hdac1 ...
In this example, the graphics card
(NVidia
) has been enumerated before the
sound card (Realtek ALC889
). To use the
sound card as the default playback device, change
hw.snd.default_unit
to the unit that should
be used for playback:
#
sysctl hw.snd.default_unit=
n
where n
is the number of the sound
device to use. In this example, it should be
4
. Make this change permanent by adding
the following line to
/etc/sysctl.conf
:
hw.snd.default_unit=4
It is often desirable to have multiple sources of sound that are able to play simultaneously. FreeBSD uses “Virtual Sound Channels” to multiplex the sound card's playback by mixing sound in the kernel.
Three sysctl(8) knobs are available for configuring virtual channels:
#
sysctl dev.pcm.0.play.vchans=4
#
sysctl dev.pcm.0.rec.vchans=4
#
sysctl hw.snd.maxautovchans=4
This example allocates four virtual channels, which is a
practical number for everyday use. Both
dev.pcm.0.play.vchans=4
and
dev.pcm.0.rec.vchans=4
are configurable
after a device has been attached and represent the number of
virtual channels pcm0
has for playback
and recording. Since the pcm
module can
be loaded independently of the hardware drivers,
hw.snd.maxautovchans
indicates how many
virtual channels will be given to an audio device when it is
attached. Refer to pcm(4) for more information.
The number of virtual channels for a device cannot be changed while it is in use. First, close any programs using the device, such as music players or sound daemons.
The correct pcm
device will
automatically be allocated transparently to a program that
requests /dev/dsp0
.
The default values for the different mixer channels are
hardcoded in the source code of the pcm(4) driver. While
sound card mixer levels can be changed using mixer(8) or
third-party applications and daemons, this is not a permanent
solution. To instead set default mixer values at the driver
level, define the appropriate values in
/boot/device.hints
, as seen in this
example:
hint.pcm.0.vol="50"
This will set the volume channel to a default value of
50
when the pcm(4) module is
loaded.
This section describes some MP3 players available for FreeBSD, how to rip audio CD tracks, and how to encode and decode MP3s.
A popular graphical MP3 player is Audacious. It supports Winamp skins and additional plugins. The interface is intuitive, with a playlist, graphic equalizer, and more. Those familiar with Winamp will find Audacious simple to use. On FreeBSD, Audacious can be installed from the multimedia/audacious port or package. Audacious is a descendant of XMMS.
The audio/mpg123 package or port provides an alternative, command-line MP3 player. Once installed, specify the MP3 file to play on the command line. If the system has multiple audio devices, the sound device can also be specified:
#
mpg123
High Performance MPEG 1.0/2.0/2.5 Audio Player for Layers 1, 2 and 3 version 1.18.1; written and copyright by Michael Hipp and others free software (LGPL) without any warranty but with best wishes Playing MPEG stream from Foobar-GreatestHits.mp3 ... MPEG 1.0 layer III, 128 kbit/s, 44100 Hz joint-stereo-a /dev/dsp1.0 Foobar-GreatestHits.mp3
Additional MP3 players are available in the FreeBSD Ports Collection.
Before encoding a CD or CD track to MP3, the audio data on the CD must be ripped to the hard drive. This is done by copying the raw CD Digital Audio (CDDA) data to WAV files.
The cdda2wav
tool, which is installed
with the sysutils/cdrtools suite, can be
used to rip audio information from
CDs.
With the audio CD in the drive, the
following command can be issued as
root
to rip an
entire CD into individual, per track,
WAV files:
#
cdda2wav -D
0,1,0
-B
In this example, the
-D
indicates
the SCSI device 0,1,0
0,1,0
containing the CD to rip. Use
cdrecord -scanbus
to determine the correct
device parameters for the system.
To rip individual tracks, use -t
to
specify the track:
#
cdda2wav -D
0,1,0
-t 7
To rip a range of tracks, such as track one to seven, specify a range:
#
cdda2wav -D
0,1,0
-t 1+7
To rip from an ATAPI (IDE) CDROM drive, specify the device name in place of the SCSI unit numbers. For example, to rip track 7 from an IDE drive:
#
cdda2wav -D
/dev/acd0 -t 7
Alternately, dd
can be used to extract
audio tracks on ATAPI drives, as described
in Section 17.5.5, “Duplicating Audio CDs”.
Lame is a popular MP3 encoder which can be installed from the audio/lame port. Due to patent issues, a package is not available.
The following command will convert the ripped
WAV file
to
audio01.wav
:audio01.mp3
#
lame -h -b
128
--tt "Foo Song Title
" --ta "FooBar Artist
" --tl "FooBar Album
" \ --ty "2014
" --tc "Ripped and encoded by Foo
" --tg "Genre
"audio01.wav audio01.mp3
The specified 128 kbits is a standard
MP3 bitrate while the 160 and 192 bitrates
provide higher quality. The higher the bitrate, the larger
the size of the resulting MP3. The
-h
turns on the
“higher quality but a little slower”
mode. The options beginning with --t
indicate ID3 tags, which usually contain
song information, to be embedded within the
MP3 file. Additional encoding options can
be found in the lame manual
page.
In order to burn an audio CD from MP3s, they must first be converted to a non-compressed file format. XMMS can be used to convert to the WAV format, while mpg123 can be used to convert to the raw Pulse-Code Modulation (PCM) audio data format.
To convert audio01.mp3
using
mpg123, specify the name of the
PCM file:
#
mpg123 -s
audio01.mp3
>audio01.pcm
To use XMMS to convert a MP3 to WAV format, use these steps:
Launch XMMS.
Right-click the window to bring up the XMMS menu.
Select Preferences
under
Options
.
Change the Output Plugin to “Disk Writer Plugin”.
Press Configure
.
Enter or browse to a directory to write the uncompressed files to.
Load the MP3 file into XMMS as usual, with volume at 100% and EQ settings turned off.
Press Play
. The
XMMS will appear as if it is
playing the MP3, but no music will be
heard. It is actually playing the MP3
to a file.
When finished, be sure to set the default Output Plugin back to what it was before in order to listen to MP3s again.
Both the WAV and PCM formats can be used with cdrecord. When using WAV files, there will be a small tick sound at the beginning of each track. This sound is the header of the WAV file. The audio/sox port or package can be used to remove the header:
%
sox -t wav -r 44100 -s -w -c 2
track.wav track.raw
Refer to Section 17.5, “Creating and Using CD Media” for more information on using a CD burner in FreeBSD.
Before configuring video playback, determine the model and
chipset of the video card. While
Xorg supports a wide variety of
video cards, not all provide good playback performance. To
obtain a list of extensions supported by the
Xorg server using the card, run
xdpyinfo
while
Xorg is running.
It is a good idea to have a short MPEG test file for
evaluating various players and options. Since some
DVD applications look for
DVD media in /dev/dvd
by
default, or have this device name hardcoded in them, it might be
useful to make a symbolic link to the proper device:
#
ln -sf /dev/cd0 /dev/dvd
Due to the nature of devfs(5), manually created links
will not persist after a system reboot. In order to recreate
the symbolic link automatically when the system boots, add the
following line to /etc/devfs.conf
:
link cd0 dvd
DVD decryption invokes certain functions that require write permission to the DVD device.
To enhance the shared memory Xorg interface, it is recommended to increase the values of these sysctl(8) variables:
kern.ipc.shmmax=67108864 kern.ipc.shmall=32768
There are several possible ways to display video under Xorg and what works is largely hardware dependent. Each method described below will have varying quality across different hardware.
Common video interfaces include:
Xorg: normal output using shared memory.
XVideo: an extension to the Xorg interface which allows video to be directly displayed in drawable objects through a special acceleration. This extension provides good quality playback even on low-end machines. The next section describes how to determine if this extension is running.
SDL: the Simple Directmedia Layer is a porting layer for many operating systems, allowing cross-platform applications to be developed which make efficient use of sound and graphics. SDL provides a low-level abstraction to the hardware which can sometimes be more efficient than the Xorg interface. On FreeBSD, SDL can be installed using the devel/sdl20 package or port.
DGA: the Direct Graphics Access is
an Xorg extension which
allows a program to bypass the
Xorg server and directly
alter the framebuffer. Because it relies on a low level
memory mapping, programs using it must be run as
root
. The
DGA extension can be tested and
benchmarked using dga(1). When
dga
is running, it changes the colors
of the display whenever a key is pressed. To quit, press
q.
SVGAlib: a low level console graphics layer.
To check whether this extension is running, use
xvinfo
:
%
xvinfo
XVideo is supported for the card if the result is similar to:
X-Video Extension version 2.2 screen #0 Adaptor #0: "Savage Streams Engine" number of ports: 1 port base: 43 operations supported: PutImage supported visuals: depth 16, visualID 0x22 depth 16, visualID 0x23 number of attributes: 5 "XV_COLORKEY" (range 0 to 16777215) client settable attribute client gettable attribute (current value is 2110) "XV_BRIGHTNESS" (range -128 to 127) client settable attribute client gettable attribute (current value is 0) "XV_CONTRAST" (range 0 to 255) client settable attribute client gettable attribute (current value is 128) "XV_SATURATION" (range 0 to 255) client settable attribute client gettable attribute (current value is 128) "XV_HUE" (range -180 to 180) client settable attribute client gettable attribute (current value is 0) maximum XvImage size: 1024 x 1024 Number of image formats: 7 id: 0x32595559 (YUY2) guid: 59555932-0000-0010-8000-00aa00389b71 bits per pixel: 16 number of planes: 1 type: YUV (packed) id: 0x32315659 (YV12) guid: 59563132-0000-0010-8000-00aa00389b71 bits per pixel: 12 number of planes: 3 type: YUV (planar) id: 0x30323449 (I420) guid: 49343230-0000-0010-8000-00aa00389b71 bits per pixel: 12 number of planes: 3 type: YUV (planar) id: 0x36315652 (RV16) guid: 52563135-0000-0000-0000-000000000000 bits per pixel: 16 number of planes: 1 type: RGB (packed) depth: 0 red, green, blue masks: 0x1f, 0x3e0, 0x7c00 id: 0x35315652 (RV15) guid: 52563136-0000-0000-0000-000000000000 bits per pixel: 16 number of planes: 1 type: RGB (packed) depth: 0 red, green, blue masks: 0x1f, 0x7e0, 0xf800 id: 0x31313259 (Y211) guid: 59323131-0000-0010-8000-00aa00389b71 bits per pixel: 6 number of planes: 3 type: YUV (packed) id: 0x0 guid: 00000000-0000-0000-0000-000000000000 bits per pixel: 0 number of planes: 0 type: RGB (packed) depth: 1 red, green, blue masks: 0x0, 0x0, 0x0
The formats listed, such as YUV2 and YUV12, are not present with every implementation of XVideo and their absence may hinder some players.
If the result instead looks like:
X-Video Extension version 2.2 screen #0 no adaptors present
XVideo is probably not supported for the card. This means that it will be more difficult for the display to meet the computational demands of rendering video, depending on the video card and processor.
This section introduces some of the software available from the FreeBSD Ports Collection which can be used for video playback.
MPlayer is a command-line video player with an optional graphical interface which aims to provide speed and flexibility. Other graphical front-ends to MPlayer are available from the FreeBSD Ports Collection.
MPlayer can be installed using the multimedia/mplayer package or port. Several compile options are available and a variety of hardware checks occur during the build process. For these reasons, some users prefer to build the port rather than install the package.
When compiling the port, the menu options should be reviewed to determine the type of support to compile into the port. If an option is not selected, MPlayer will not be able to display that type of video format. Use the arrow keys and spacebar to select the required formats. When finished, press Enter to continue the port compile and installation.
By default, the package or port will build the
mplayer
command line utility and the
gmplayer
graphical utility. To encode
videos, compile the multimedia/mencoder
port. Due to licensing restrictions, a package is not
available for MEncoder.
The first time MPlayer is
run, it will create ~/.mplayer
in the
user's home directory. This subdirectory contains default
versions of the user-specific configuration files.
This section describes only a few common uses. Refer to mplayer(1) for a complete description of its numerous options.
To play the file
,
specify the video interfaces with testfile.avi
-vo
, as
seen in the following examples:
%
mplayer -vo xv
testfile.avi
%
mplayer -vo sdl
testfile.avi
%
mplayer -vo x11
testfile.avi
#
mplayer -vo dga
testfile.avi
#
mplayer -vo 'sdl:dga'
testfile.avi
It is worth trying all of these options, as their relative performance depends on many factors and will vary significantly with hardware.
To play a DVD, replace
with testfile.avi
dvd://
, where
N
-dvd-device
DEVICE
N
is the title number to play and
DEVICE
is the device node for the
DVD. For example, to play title 3 from
/dev/dvd
:
#
mplayer -vo xv dvd://3 -dvd-device /dev/dvd
The default DVD device can be
defined during the build of the
MPlayer port by including the
WITH_DVD_DEVICE=/path/to/desired/device
option. By default, the device is
/dev/cd0
. More details can be found
in the port's
Makefile.options
.
To stop, pause, advance, and so on, use a keybinding.
To see the list of keybindings, run mplayer
-h
or read mplayer(1).
Additional playback options include -fs
-zoom
, which engages fullscreen mode, and
-framedrop
, which helps performance.
Each user can add commonly used options to their
~/.mplayer/config
like so:
vo=xv fs=yes zoom=yes
mplayer
can be used to rip a
DVD title to a .vob
.
To dump the second title from a
DVD:
#
mplayer -dumpstream -dumpfile out.vob dvd://2 -dvd-device /dev/dvd
The output file, out.vob
, will be
in MPEG format.
Anyone wishing to obtain a high level of expertise with UNIX® video should consult mplayerhq.hu/DOCS as it is technically informative. This documentation should be considered as required reading before submitting any bug reports.
Before using mencoder
, it is a good
idea to become familiar with the options described at mplayerhq.hu/DOCS/HTML/en/mencoder.html.
There are innumerable ways to improve quality, lower
bitrate, and change formats, and some of these options may
make the difference between good or bad performance.
Improper combinations of command line options can yield
output files that are unplayable even by
mplayer
.
Here is an example of a simple copy:
%
mencoder
input.avi
-oac copy -ovc copy -ooutput.avi
To rip to a file, use -dumpfile
with
mplayer
.
To convert
to
the MPEG4 codec with MPEG3 audio encoding, first install the
audio/lame port. Due to licensing
restrictions, a package is not available. Once installed,
type:input.avi
%
mencoder
input.avi
-oac mp3lame -lameopts br=192 \ -ovc lavc -lavcopts vcodec=mpeg4:vhq -ooutput.avi
This will produce output playable by applications such
as mplayer
and
xine
.
can be replaced with input.avi
dvd://1 -dvd-device
/dev/dvd
and run as root
to re-encode a
DVD title directly. Since it may take a
few tries to get the desired result, it is recommended to
instead dump the title to a file and to work on the
file.
xine is a video player with a reusable base library and a modular executable which can be extended with plugins. It can be installed using the multimedia/xine package or port.
In practice, xine requires either a fast CPU with a fast video card, or support for the XVideo extension. The xine video player performs best on XVideo interfaces.
By default, the xine player starts a graphical user interface. The menus can then be used to open a specific file.
Alternatively, xine may be invoked from the command line by specifying the name of the file to play:
%
xine -g -p
mymovie.avi
Refer to xine-project.org/faq for more information and troubleshooting tips.
Transcode provides a suite of tools for re-encoding video and audio files. Transcode can be used to merge video files or repair broken files using command line tools with stdin/stdout stream interfaces.
In FreeBSD, Transcode can be installed using the multimedia/transcode package or port. Many users prefer to compile the port as it provides a menu of compile options for specifying the support and codecs to compile in. If an option is not selected, Transcode will not be able to encode that format. Use the arrow keys and spacebar to select the required formats. When finished, press Enter to continue the port compile and installation.
This example demonstrates how to convert a DivX file into a PAL MPEG-1 file (PAL VCD):
%
transcode -i
input.avi
-V --export_prof vcd-pal -o output_vcd%
mplex -f 1 -o
output_vcd.mpg output_vcd.m1v output_vcd.mpa
The resulting MPEG file,
,
is ready to be played with
MPlayer. The file can be burned
on a CD media to create a video
CD using a utility such as
multimedia/vcdimager or
sysutils/cdrdao.output_vcd.mpg
In addition to the manual page for
transcode
, refer to transcoding.org/cgi-bin/transcode
for further information and examples.
TV cards can be used to watch broadcast or cable TV on a computer. Most cards accept composite video via an RCA or S-video input and some cards include a FM radio tuner.
FreeBSD provides support for PCI-based TV cards using a Brooktree Bt848/849/878/879 video capture chip with the bktr(4) driver. This driver supports most Pinnacle PCTV video cards. Before purchasing a TV card, consult bktr(4) for a list of supported tuners.
In order to use the card, the bktr(4) driver must be
loaded. To automate this at boot time, add the following line
to /boot/loader.conf
:
bktr_load="YES"
Alternatively, one can statically compile support for the TV card into a custom kernel. In that case, add the following lines to the custom kernel configuration file:
device bktr device iicbus device iicbb device smbus
These additional devices are necessary as the card components are interconnected via an I2C bus. Then, build and install a new kernel.
To test that the tuner is correctly detected, reboot the system. The TV card should appear in the boot messages, as seen in this example:
bktr0: <BrookTree 848A> mem 0xd7000000-0xd7000fff irq 10 at device 10.0 on pci0 iicbb0: <I2C bit-banging driver> on bti2c0 iicbus0: <Philips I2C bus> on iicbb0 master-only iicbus1: <Philips I2C bus> on iicbb0 master-only smbus0: <System Management Bus> on bti2c0 bktr0: Pinnacle/Miro TV, Philips SECAM tuner.
The messages will differ according to the hardware. If necessary, it is possible to override some of the detected parameters using sysctl(8) or custom kernel configuration options. For example, to force the tuner to a Philips SECAM tuner, add the following line to a custom kernel configuration file:
options OVERRIDE_TUNER=6
or, use sysctl(8):
#
sysctl hw.bt848.tuner=6
Refer to bktr(4) for a description of the available sysctl(8) parameters and kernel options.
To use the TV card, install one of the following applications:
multimedia/fxtv provides TV-in-a-window and image/audio/video capture capabilities.
multimedia/xawtv is another TV application with similar features.
audio/xmradio provides an application for using the FM radio tuner of a TV card.
More applications are available in the FreeBSD Ports Collection.
If any problems are encountered with the TV card, check that the video capture chip and the tuner are supported by bktr(4) and that the right configuration options were used. For more support or to ask questions about supported TV cards, refer to the freebsd-multimedia mailing list.
MythTV is a popular, open source Personal Video Recorder (PVR) application. This section demonstrates how to install and setup MythTV on FreeBSD. Refer to mythtv.org/wiki for more information on how to use MythTV.
MythTV requires a frontend and a backend. These components can either be installed on the same system or on different machines.
The frontend can be installed on FreeBSD using the multimedia/mythtv-frontend package or port. Xorg must also be installed and configured as described in Chapter 5, The X Window System. Ideally, this system has a video card that supports X-Video Motion Compensation (XvMC) and, optionally, a Linux Infrared Remote Control (LIRC)-compatible remote.
To install both the backend and the frontend on FreeBSD, use the multimedia/mythtv package or port. A MySQL™ database server is also required and should automatically be installed as a dependency. Optionally, this system should have a tuner card and sufficient storage to hold recorded data.
MythTV uses Video for Linux (V4L) to access video input devices such as encoders and tuners. In FreeBSD, MythTV works best with USB DVB-S/C/T cards as they are well supported by the multimedia/webcamd package or port which provides a V4L userland application. Any Digital Video Broadcasting (DVB) card supported by webcamd should work with MythTV. A list of known working cards can be found at wiki.freebsd.org/WebcamCompat. Drivers are also available for Hauppauge cards in the multimedia/pvr250 and multimedia/pvrxxx ports, but they provide a non-standard driver interface that does not work with versions of MythTV greater than 0.23. Due to licensing restrictions, no packages are available and these two ports must be compiled.
The wiki.freebsd.org/HTPC page contains a list of all available DVB drivers.
To install MythTV using binary packages:
#
pkg install mythtv
Alternatively, to install from the Ports Collection:
#
cd /usr/ports/multimedia/mythtv
#
make install
Once installed, set up the MythTV database:
#
mysql -uroot -p < /usr/local/share/mythtv/database/mc.sql
Then, configure the backend:
#
mythtv-setup
Finally, start the backend:
#
sysrc mythbackend_enable=yes
#
service mythbackend start
In FreeBSD, access to image scanners is provided by SANE (Scanner Access Now Easy), which is available in the FreeBSD Ports Collection. SANE will also use some FreeBSD device drivers to provide access to the scanner hardware.
FreeBSD supports both SCSI and USB scanners. Depending upon the scanner interface, different device drivers are required. Be sure the scanner is supported by SANE prior to performing any configuration. Refer to http://www.sane-project.org/sane-supported-devices.html for more information about supported scanners.
This chapter describes how to determine if the scanner has been detected by FreeBSD. It then provides an overview of how to configure and use SANE on a FreeBSD system.
The GENERIC
kernel includes the
device drivers needed to support USB
scanners. Users with a custom kernel should ensure that the
following lines are present in the custom kernel configuration
file:
device usb device uhci device ohci device ehci
To determine if the USB scanner is
detected, plug it in and use dmesg
to
determine whether the scanner appears in the system message
buffer. If it does, it should display a message similar to
this:
ugen0.2: <EPSON> at usbus0
In this example, an EPSON
Perfection® 1650
USB scanner was detected on
/dev/ugen0.2
.
If the scanner uses a SCSI interface,
it is important to know which SCSI
controller board it will use. Depending upon the
SCSI chipset, a custom kernel configuration
file may be needed. The GENERIC
kernel
supports the most common SCSI controllers.
Refer to /usr/src/sys/conf/NOTES
to
determine the correct line to add to a custom kernel
configuration file. In addition to the
SCSI adapter driver, the following lines
are needed in a custom kernel configuration file:
device scbus device pass
Verify that the device is displayed in the system message buffer:
pass2 at aic0 bus 0 target 2 lun 0 pass2: <AGFA SNAPSCAN 600 1.10> Fixed Scanner SCSI-2 device pass2: 3.300MB/s transfers
If the scanner was not powered-on at system boot, it is
still possible to manually force detection by performing a
SCSI bus scan with
camcontrol
:
#
camcontrol rescan all
Re-scan of bus 0 was successful Re-scan of bus 1 was successful Re-scan of bus 2 was successful Re-scan of bus 3 was successful
The scanner should now appear in the SCSI devices list:
#
camcontrol devlist
<IBM DDRS-34560 S97B> at scbus0 target 5 lun 0 (pass0,da0) <IBM DDRS-34560 S97B> at scbus0 target 6 lun 0 (pass1,da1) <AGFA SNAPSCAN 600 1.10> at scbus1 target 2 lun 0 (pass3) <PHILIPS CDD3610 CD-R/RW 1.00> at scbus2 target 0 lun 0 (pass2,cd0)
Refer to scsi(4) and camcontrol(8) for more details about SCSI devices on FreeBSD.
The SANE system is split in two parts: the backends (graphics/sane-backends) and the frontends (graphics/sane-frontends or graphics/xsane). The backends provide access to the scanner. Refer to http://www.sane-project.org/sane-supported-devices.html to determine which backend supports the scanner. The frontends provide the graphical scanning interface. graphics/sane-frontends installs xscanimage while graphics/xsane installs xsane.
To install the two parts from binary packages:
#
pkg install xsane sane-frontends
Alternatively, to install from the Ports Collection
#
cd /usr/ports/graphics/sane-frontends
#
make install clean
#
cd /usr/ports/graphics/xsane
#
make install clean
After installing the
graphics/sane-backends port or package, use
sane-find-scanner
to check the scanner
detection by the SANE
system:
#
sane-find-scanner -q
found SCSI scanner "AGFA SNAPSCAN 600 1.10" at /dev/pass3
The output should show the interface type of the scanner and the device node used to attach the scanner to the system. The vendor and the product model may or may not appear.
Some USB scanners require firmware to be loaded. Refer to sane-find-scanner(1) and sane(7) for details.
Next, check if the scanner will be identified by a
scanning frontend. The SANE
backends include scanimage
which can be
used to list the devices and perform an image acquisition.
Use -L
to list the scanner devices. The
first example is for a SCSI scanner and the
second is for a USB scanner:
#
scanimage -L
device `snapscan:/dev/pass3' is a AGFA SNAPSCAN 600 flatbed scanner#
scanimage -L
device 'epson2:libusb:/dev/usb:/dev/ugen0.2' is a Epson GT-8200 flatbed scanner
In this second example,
'epson2:libusb:/dev/usb:/dev/ugen0.2'
is
the backend name (epson2
) and
/dev/ugen0.2
is the device node used by the
scanner.
If scanimage
is unable to identify the
scanner, this message will appear:
#
scanimage -L
No scanners were identified. If you were expecting something different, check that the scanner is plugged in, turned on and detected by the sane-find-scanner tool (if appropriate). Please read the documentation which came with this software (README, FAQ, manpages).
If this happens, edit the backend configuration file in
/usr/local/etc/sane.d/
and define the
scanner device used. For example, if the undetected scanner
model is an EPSON
Perfection® 1650 and it uses the
epson2
backend, edit
/usr/local/etc/sane.d/epson2.conf
. When
editing, add a line specifying the interface and the device
node used. In this case, add the following line:
usb /dev/ugen0.2
Save the edits and verify that the scanner is identified with the right backend name and the device node:
#
scanimage -L
device 'epson2:libusb:/dev/usb:/dev/ugen0.2' is a Epson GT-8200 flatbed scanner
Once scanimage -L
sees the scanner, the
configuration is complete and the scanner is now ready to
use.
While scanimage
can be used to perform
an image acquisition from the command line, it is often
preferable to use a graphical interface to perform image
scanning. The graphics/sane-frontends
package or port installs a simple but efficient graphical
interface, xscanimage.
Alternately, xsane, which is installed with the graphics/xsane package or port, is another popular graphical scanning frontend. It offers advanced features such as various scanning modes, color correction, and batch scans. Both of these applications are usable as a GIMP plugin.
In order to have access to the scanner, a user needs read
and write permissions to the device node used by the scanner.
In the previous example, the USB scanner
uses the device node /dev/ugen0.2
which
is really a symlink to the real device node
/dev/usb/0.2.0
. The symlink and the
device node are owned, respectively, by the wheel
and operator
groups. While
adding the user to these groups will allow access to the
scanner, it is considered insecure to add a user to
wheel
. A better
solution is to create a group and make the scanner device
accessible to members of this group.
This example creates a group called
:usb
#
pw groupadd usb
Then, make the /dev/ugen0.2
symlink
and the /dev/usb/0.2.0
device node
accessible to the usb
group with write
permissions of 0660
or
0664
by adding the following lines to
/etc/devfs.rules
:
[system=5] add path ugen0.2 mode 0660 group usb add path usb/0.2.0 mode 0666 group usb
Finally, add the users to
in order to allow access to the scanner:usb
#
pw groupmod usb -m
joe
For more details refer to pw(8).
The kernel is the core of the FreeBSD operating system. It is responsible for managing memory, enforcing security controls, networking, disk access, and much more. While much of FreeBSD is dynamically configurable, it is still occasionally necessary to configure and compile a custom kernel.
After reading this chapter, you will know:
When to build a custom kernel.
How to take a hardware inventory.
How to customize a kernel configuration file.
How to use the kernel configuration file to create and build a new kernel.
How to install the new kernel.
How to troubleshoot if things go wrong.
All of the commands listed in the examples in this chapter
should be executed as root
.
Traditionally, FreeBSD used a monolithic kernel. The kernel was one large program, supported a fixed list of devices, and in order to change the kernel's behavior, one had to compile and then reboot into a new kernel.
Today, most of the functionality in the FreeBSD kernel is contained in modules which can be dynamically loaded and unloaded from the kernel as necessary. This allows the running kernel to adapt immediately to new hardware and for new functionality to be brought into the kernel. This is known as a modular kernel.
Occasionally, it is still necessary to perform static kernel configuration. Sometimes the needed functionality is so tied to the kernel that it can not be made dynamically loadable. Some security environments prevent the loading and unloading of kernel modules and require that only needed functionality is statically compiled into the kernel.
Building a custom kernel is often a rite of passage for
advanced BSD users. This process, while time consuming, can
provide benefits to the FreeBSD system. Unlike the
GENERIC
kernel, which must support a wide
range of hardware, a custom kernel can be stripped down to only
provide support for that computer's hardware. This has a number
of benefits, such as:
Faster boot time. Since the kernel will only probe the hardware on the system, the time it takes the system to boot can decrease.
Lower memory usage. A custom kernel often uses less
memory than the GENERIC
kernel by
omitting unused features and device drivers. This is
important because the kernel code remains resident in
physical memory at all times, preventing that memory from
being used by applications. For this reason, a custom
kernel is useful on a system with a small amount of
RAM.
Additional hardware support. A custom kernel can add
support for devices which are not present in the
GENERIC
kernel.
Before building a custom kernel, consider the reason for doing so. If there is a need for specific hardware support, it may already exist as a module.
Kernel modules exist in /boot/kernel
and may be dynamically loaded into the running kernel using
kldload(8). Most kernel drivers have a loadable module and
manual page. For example, the ath(4) wireless Ethernet
driver has the following information in its manual page:
Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5): if_ath_load="YES"
Adding if_ath_load="YES"
to
/boot/loader.conf
will load this module
dynamically at boot time.
In some cases, there is no associated module in
/boot/kernel
. This is mostly true for
certain subsystems.
Before editing the kernel configuration file, it is recommended to perform an inventory of the machine's hardware. On a dual-boot system, the inventory can be created from the other operating system. For example, Microsoft®'s Device Manager contains information about installed devices.
Some versions of Microsoft® Windows® have a System icon which can be used to access Device Manager.
If FreeBSD is the only installed operating system, use dmesg(8) to determine the hardware that was found and listed during the boot probe. Most device drivers on FreeBSD have a manual page which lists the hardware supported by that driver. For example, the following lines indicate that the psm(4) driver found a mouse:
psm0: <PS/2 Mouse> irq 12 on atkbdc0 psm0: [GIANT-LOCKED] psm0: [ITHREAD] psm0: model Generic PS/2 mouse, device ID 0
Since this hardware exists, this driver should not be removed from a custom kernel configuration file.
If the output of dmesg
does not display
the results of the boot probe output, instead read the contents
of /var/run/dmesg.boot
.
Another tool for finding hardware is pciconf(8), which provides more verbose output. For example:
%
pciconf -lv
ath0@pci0:3:0:0: class=0x020000 card=0x058a1014 chip=0x1014168c rev=0x01 hdr=0x00 vendor = 'Atheros Communications Inc.' device = 'AR5212 Atheros AR5212 802.11abg wireless' class = network subclass = ethernet
This output shows that the ath
driver
located a wireless Ethernet device.
The -k
flag of man(1) can be used to
provide useful information. For example, it can be
used to display a list of manual pages which contain a
particular device brand or name:
#
man -k
ath(4) - Atheros IEEE 802.11 wireless network driver ath_hal(4) - Atheros Hardware Access Layer (HAL)Atheros
Once the hardware inventory list is created, refer to it to ensure that drivers for installed hardware are not removed as the custom kernel configuration is edited.
In order to create a custom kernel configuration file and build a custom kernel, the full FreeBSD source tree must first be installed.
If /usr/src/
does not exist or it is
empty, source has not been installed. Source can be installed
using Subversion and the instructions
in Section A.3, “Using Subversion”.
Once source is installed, review the contents of
/usr/src/sys
. This directory contains a
number of subdirectories, including those which represent the
following supported architectures: amd64
,
i386
, ia64
,
powerpc
, and
sparc64
. Everything inside a particular
architecture's directory deals with that architecture only and
the rest of the code is machine independent code common to all
platforms. Each supported architecture has a
conf
subdirectory which contains the
GENERIC
kernel configuration file for that
architecture.
Do not make edits to GENERIC
. Instead,
copy the file to a different name and make edits to the copy.
The convention is to use a name with all capital letters. When
maintaining multiple FreeBSD machines with different hardware, it
is a good idea to name it after the machine's hostname. This
example creates a copy, named MYKERNEL
, of
the GENERIC
configuration file for the
amd64
architecture:
#
cd /usr/src/sys/
amd64
/conf#
cp GENERIC
MYKERNEL
can
now be customized with any ASCII text editor.
The default editor is vi, though an
easier editor for beginners, called
ee, is also installed with
FreeBSD.MYKERNEL
The format of the kernel configuration file is simple.
Each line contains a keyword that represents a device or
subsystem, an argument, and a brief description. Any text
after a #
is considered a comment and
ignored. To remove kernel support for a device or subsystem,
put a #
at the beginning of the line
representing that device or subsystem. Do not add or remove a
#
for any line that you do not
understand.
It is easy to remove support for a device or option and end up with a broken kernel. For example, if the ata(4) driver is removed from the kernel configuration file, a system using ATA disk drivers may not boot. When in doubt, just leave support in the kernel.
In addition to the brief descriptions provided in this file,
additional descriptions are contained in
NOTES
, which can be found in the same
directory as GENERIC
for that architecture.
For architecture independent options, refer to
/usr/src/sys/conf/NOTES
.
When finished customizing the kernel configuration file,
save a backup copy to a location outside of
/usr/src
.
Alternately, keep the kernel configuration file elsewhere and create a symbolic link to the file:
#
cd /usr/src/sys/amd64/conf
#
mkdir /root/kernels
#
cp GENERIC /root/kernels/MYKERNEL
#
ln -s /root/kernels/MYKERNEL
An include
directive is available for use
in configuration files. This allows another configuration file
to be included in the current one, making it easy to maintain
small changes relative to an existing file. If only a small
number of additional options or drivers are required, this
allows a delta to be maintained with respect to
GENERIC
, as seen in this example:
include GENERIC ident MYKERNEL options IPFIREWALL options DUMMYNET options IPFIREWALL_DEFAULT_TO_ACCEPT options IPDIVERT
Using this method, the local configuration file expresses
local differences from a GENERIC
kernel.
As upgrades are performed, new features added to
GENERIC
will also be added to the local
kernel unless they are specifically prevented using
nooptions
or nodevice
. A
comprehensive list of configuration directives and their
descriptions may be found in config(5).
To build a file which contains all available options,
run the following command as root
:
#
cd /usr/src/sys/
arch
/conf && make LINT
Once the edits to the custom configuration file have been saved, the source code for the kernel can be compiled using the following steps:
Change to this directory:
#
cd /usr/src
Compile the new kernel by specifying the name of the custom kernel configuration file:
#
make buildkernel KERNCONF=
MYKERNEL
Install the new kernel associated with the specified
kernel configuration file. This command will copy the new
kernel to /boot/kernel/kernel
and save
the old kernel to
/boot/kernel.old/kernel
:
#
make installkernel KERNCONF=
MYKERNEL
Shutdown the system and reboot into the new kernel. If something goes wrong, refer to The kernel does not boot.
By default, when a custom kernel is compiled, all kernel
modules are rebuilt. To update a kernel faster or to build
only custom modules, edit /etc/make.conf
before starting to build the kernel.
For example, this variable specifies the list of modules to build instead of using the default of building all modules:
MODULES_OVERRIDE = linux acpi
Alternately, this variable lists which modules to exclude from the build process:
WITHOUT_MODULES = linux acpi sound
Additional variables are available. Refer to make.conf(5) for details.
There are four categories of trouble that can occur when building a custom kernel:
config
failsIf config
fails, it will print the
line number that is incorrect. As an example, for the
following message, make sure that line 17 is typed
correctly by comparing it to GENERIC
or NOTES
:
config: line 17: syntax error
make
failsIf make
fails, it is usually due to
an error in the kernel configuration file which is not
severe enough for config
to catch.
Review the configuration, and if the problem is not
apparent, send an email to the FreeBSD general questions mailing list which
contains the kernel configuration file.
If the new kernel does not boot or fails to recognize
devices, do not panic! Fortunately, FreeBSD has an excellent
mechanism for recovering from incompatible kernels.
Simply choose the kernel to boot from at the FreeBSD boot
loader. This can be accessed when the system boot menu
appears by selecting the “Escape to a loader
prompt” option. At the prompt, type
boot
, or the
name of any other kernel that is known to boot
properly.kernel.old
After booting with a good kernel, check over the
configuration file and try to build it again. One helpful
resource is /var/log/messages
which
records the kernel messages from every successful boot.
Also, dmesg(8) will print the kernel messages from
the current boot.
When troubleshooting a kernel, make sure to keep
a copy of GENERIC
, or some other
kernel that is known to work, as a different name that
will not get erased on the next build. This is
important because every time a new kernel is installed,
kernel.old
is overwritten with the
last installed kernel, which may or may not be bootable.
As soon as possible, move the working kernel by renaming
the directory containing the good kernel:
#
mv /boot/kernel
/boot/kernel.bad
#
mv /boot/
kernel.good
/boot/kernel
If the kernel version differs from the one that the system utilities have been built with, for example, a kernel built from -CURRENT sources is installed on a -RELEASE system, many system status commands like ps(1) and vmstat(8) will not work. To fix this, recompile and install a world built with the same version of the source tree as the kernel. It is never a good idea to use a different version of the kernel than the rest of the operating system.
Putting information on paper is a vital function, despite many attempts to eliminate it. Printing has two basic components. The data must be delivered to the printer, and must be in a form that the printer can understand.
Basic printing can be set up quickly. The printer must be capable of printing plain ASCII text. For printing to other types of files, see Section 9.5.3, “Filters”.
Create a directory to store files while they are being printed:
#
mkdir -p /var/spool/lpd/lp
#
chown daemon:daemon /var/spool/lpd/lp
#
chmod 770 /var/spool/lpd/lp
As root
,
create /etc/printcap
with these
contents:
lp:\
:lp=/dev/unlpt0:\
:sh:\
:mx#0:\
:sd=/var/spool/lpd/lp:\
:lf=/var/log/lpd-errs:
Enable lpd
by editing
/etc/rc.conf
, adding this line:
lpd_enable="YES"
Start the service:
#
service lpd start
Starting lpd.
Print a test:
#
printf "1. This printer can print.\n2. This is the second line.\n" | lpr
If both lines do not start at the left border, but “stairstep” instead, see Section 9.5.3.1, “Preventing Stairstepping on Plain Text Printers”.
Text files can now be printed with
lpr
. Give the filename on the command
line, or pipe output directly into
lpr
.
%
lpr textfile.txt
%
ls -lh | lpr
Printers are connected to computer systems in a variety of ways. Small desktop printers are usually connected directly to a computer's USB port. Older printers are connected to a parallel or “printer” port. Some printers are directly connected to a network, making it easy for multiple computers to share them. A few printers use a rare serial port connection.
FreeBSD can communicate with all of these types of printers.
USB printers can be connected to any available USB port on the computer.
When FreeBSD detects a USB printer,
two device entries are created:
/dev/ulpt0
and
/dev/unlpt0
. Data sent to either
device will be relayed to the printer. After each print
job, ulpt0
resets the
USB port. Resetting the port can cause
problems with some printers, so the
unlpt0
device is usually used
instead. unlpt0
does not reset the
USB port at all.
The parallel port device is
/dev/lpt0
. This device appears
whether a printer is attached or not, it is not
autodetected.
Vendors have largely moved away from these “legacy” ports, and many computers no longer have them. Adapters can be used to connect a parallel printer to a USB port. With such an adapter, the printer can be treated as if it were actually a USB printer. Devices called print servers can also be used to connect parallel printers directly to a network.
Serial ports are another legacy port, rarely used for printers except in certain niche applications. Cables, connectors, and required wiring vary widely.
For serial ports built into a motherboard, the serial
device name is /dev/cuau0
or
/dev/cuau1
. Serial
USB adapters can also be used, and
these will appear as
/dev/cuaU
.0
Several communication parameters must be known to communicate with a serial printer. The most important are baud rate or BPS (Bits Per Second) and parity. Values vary, but typical serial printers use a baud rate of 9600 and no parity.
Network printers are connected directly to the local computer network.
The DNS hostname of the printer must be known. If the printer is assigned a dynamic address by DHCP, DNS should be dynamically updated so that the host name always has the correct IP address. Network printers are often given static IP addresses to avoid this problem.
Most network printers understand print jobs sent with
the LPD protocol. A print queue name
can also be specified. Some printers process data
differently depending on which queue is used. For
example, a raw
queue prints the data
unchanged, while the text
queue adds
carriage returns to plain text.
Many network printers can also print data sent directly to port 9100.
Wired network connections are usually the easiest to set up and give the fastest printing. For direct connection to the computer, USB is preferred for speed and simplicity. Parallel connections work but have limitations on cable length and speed. Serial connections are more difficult to configure. Cable wiring differs between models, and communication parameters like baud rate and parity bits must add to the complexity. Fortunately, serial printers are rare.
Data sent to a printer must be in a language that the printer can understand. These languages are called Page Description Languages, or PDLs.
Plain ASCII text is the simplest
way to send data to a printer. Characters correspond one
to one with what will be printed: an A
in the data prints an A
on the page.
Very little formatting is available. There is no way to
select a font or proportional spacing. The forced
simplicity of plain ASCII means that
text can be printed straight from the computer with little
or no encoding or translation. The printed output
corresponds directly with what was sent.
Some inexpensive printers cannot print plain ASCII text. This makes them more difficult to set up, but it is usually still possible.
PostScript® is almost the opposite of ASCII. Rather than simple text, a PostScript® program is a set of instructions that draw the final document. Different fonts and graphics can be used. However, this power comes at a price. The program that draws the page must be written. Usually this program is generated by application software, so the process is invisible to the user.
Inexpensive printers sometimes leave out PostScript® compatibility as a cost-saving measure.
PCL is an extension of ASCII, adding escape sequences for formatting, font selection, and printing graphics. Many printers provide PCL5 support. Some support the newer PCL6 or PCLXL. These later versions are supersets of PCL5 and can provide faster printing.
Manufacturers can reduce the cost of a printer by giving it a simple processor and very little memory. These printers are not capable of printing plain text. Instead, bitmaps of text and graphics are drawn by a driver on the host computer and then sent to the printer. These are called host-based printers.
Communication between the driver and a host-based printer is often through proprietary or undocumented protocols, making them functional only on the most common operating systems.
Many applications from the Ports Collection and FreeBSD utilities produce PostScript® output. This table shows the utilities available to convert that into other common PDLs:
Output PDL | Generated By | Notes |
---|---|---|
PCL or PCL5 | print/ghostscript9-base | -sDEVICE=ljet4 for monochrome,
-sDEVICE=cljet5 for color |
PCLXL or PCL6 | print/ghostscript9-base | -sDEVICE=pxlmono for
monochrome, -sDEVICE=pxlcolor for
color |
ESC/P2 | print/ghostscript9-base | -sDEVICE=uniprint |
XQX | print/foo2zjs |
For the easiest printing, choose a printer that supports PostScript®. Printers that support PCL are the next preferred. With print/ghostscript9-base, these printers can be used as if they understood PostScript® natively. Printers that support PostScript® or PCL directly almost always support direct printing of plain ASCII text files also.
Line-based printers like typical inkjets usually do not support PostScript® or PCL. They often can print plain ASCII text files. print/ghostscript9-base supports the PDLs used by some of these printers. However, printing an entire graphic-based page on these printers is often very slow due to the large amount of data to be transferred and printed.
Host-based printers are often more difficult to set up. Some cannot be used at all because of proprietary PDLs. Avoid these printers when possible.
Descriptions of many PDLs can be found at http://www.undocprint.org/formats/page_description_languages. The particular PDL used by various models of printers can be found at http://www.openprinting.org/printers.
For occasional printing, files can be sent directly to a
printer device without any setup. For example, a file called
sample.txt
can be sent to a
USB printer:
#
cp sample.txt /dev/unlpt0
Direct printing to network printers depends on the
abilities of the printer, but most accept print jobs on port
9100, and nc(1) can be used with them. To print the
same file to a printer with the DNS
hostname of netlaser
:
#
nc
netlaser
9100 < sample.txt
Printing a file in the background is called spooling. A spooler allows the user to continue with other programs on the computer without waiting for the printer to slowly complete the print job.
FreeBSD includes a spooler called lpd(8). Print jobs are submitted with lpr(1).
A directory for storing print jobs is created, ownership is set, and the permissions are set to prevent other users from viewing the contents of those files:
#
mkdir -p /var/spool/lpd/lp
#
chown daemon:daemon /var/spool/lpd/lp
#
chmod 770 /var/spool/lpd/lp
Printers are defined in
/etc/printcap
. An entry for each printer
includes details like a name, the port where it is attached,
and various other settings. Create
/etc/printcap
with these contents:
lp:\ :lp=/dev/unlpt0:\ :sh:\ :mx#0:\ :sd=/var/spool/lpd/lp:\ :lf=/var/log/lpd-errs:
The name of this printer. lpr(1) sends print
jobs to the | |||||||||||
The device where the printer is connected. Replace this line with the appropriate one for the connection type shown here.
| |||||||||||
Suppress the printing of a header page at the start of a print job. | |||||||||||
Do not limit the maximum size of a print job. | |||||||||||
The path to the spooling directory for this printer. Each printer uses its own spooling directory. | |||||||||||
The log file where errors on this printer will be reported. |
After creating /etc/printcap
, use
chkprintcap(8) to test it for errors:
#
chkprintcap
Fix any reported problems before continuing.
Enable lpd(8) in
/etc/rc.conf
:
lpd_enable="YES"
Start the service:
#
service lpd start
Documents are sent to the printer with
lpr
. A file to be printed can be named on
the command line or piped into lpr
. These
two commands are equivalent, sending the contents of
doc.txt
to the default printer:
%
lpr doc.txt
%
cat doc.txt | lpr
Printers can be selected with -P
. To
print to a printer called
laser
:
%
lpr -Plaser doc.txt
The examples shown so far have sent the contents of a text file directly to the printer. As long as the printer understands the content of those files, output will be printed correctly.
Some printers are not capable of printing plain text, and the input file might not even be plain text.
Filters allow files to be translated or processed. The typical use is to translate one type of input, like plain text, into a form that the printer can understand, like PostScript® or PCL. Filters can also be used to provide additional features, like adding page numbers or highlighting source code to make it easier to read.
The filters discussed here are
input filters or
text filters. These filters convert the
incoming file into different forms. Use su(1) to become
root
before
creating the files.
Filters are specified in
/etc/printcap
with the
if=
identifier. To use
/usr/local/libexec/lf2crlf
as a filter,
modify /etc/printcap
like this:
lp:\ :lp=/dev/unlpt0:\ :sh:\ :mx#0:\ :sd=/var/spool/lpd/lp:\ :if=/usr/local/libexec/lf2crlf:\ :lf=/var/log/lpd-errs:
The backslash line continuation
characters at the end of the lines in
printcap
entries reveal that an entry
for a printer is really just one long line with entries
delimited by colon characters. An earlier example can be
rewritten as a single less-readable line:
lp:lp=/dev/unlpt0:sh:mx#0:sd=/var/spool/lpd/lp:if=/usr/local/libexec/lf2crlf:lf=/var/log/lpd-errs:
Typical FreeBSD text files contain only a single line feed character at the end of each line. These lines will “stairstep” on a standard printer:
A printed file looks like the steps of a staircase scattered by the wind
A filter can convert the newline characters into
carriage returns and newlines. The carriage returns make
the printer return to the left after each line. Create
/usr/local/libexec/lf2crlf
with these
contents:
#!/bin/sh CR=$'\r' /usr/bin/sed -e "s/$/${CR}/g"
Set the permissions and make it executable:
#
chmod 555 /usr/local/libexec/lf2crlf
Modify /etc/printcap
to use the
new filter:
:if=/usr/local/libexec/lf2crlf:\
Test the filter by printing the same plain text file. The carriage returns will cause each line to start at the left side of the page.
GNU Enscript converts plain text files into nicely-formatted PostScript® for printing on PostScript® printers. It adds page numbers, wraps long lines, and provides numerous other features to make printed text files easier to read. Depending on the local paper size, install either print/enscript-letter or print/enscript-a4 from the Ports Collection.
Create /usr/local/libexec/enscript
with these contents:
#!/bin/sh /usr/local/bin/enscript -o -
Set the permissions and make it executable:
#
chmod 555 /usr/local/libexec/enscript
Modify /etc/printcap
to use the
new filter:
:if=/usr/local/libexec/enscript:\
Test the filter by printing a plain text file.
Many programs produce PostScript® documents. However, inexpensive printers often only understand plain text or PCL. This filter converts PostScript® files to PCL before sending them to the printer.
Install the Ghostscript PostScript® interpreter, print/ghostscript9-base, from the Ports Collection.
Create /usr/local/libexec/ps2pcl
with these contents:
#!/bin/sh /usr/local/bin/gs -dSAFER -dNOPAUSE -dBATCH -q -sDEVICE=ljet4 -sOutputFile=- -
Set the permissions and make it executable:
#
chmod 555 /usr/local/libexec/ps2pcl
PostScript® input sent to this script will be rendered and converted to PCL before being sent on to the printer.
Modify /etc/printcap
to use this
new input filter:
:if=/usr/local/libexec/ps2pcl:\
Test the filter by sending a small PostScript® program to it:
%
printf "%%\!PS \n /Helvetica findfont 18 scalefont setfont \ 72 432 moveto (PostScript printing successful.) show showpage \004" | lpr
A filter that detects the type of input and
automatically converts it to the correct format for the
printer can be very convenient. The first two characters of
a PostScript® file are usually %!
. A
filter can detect those two characters. PostScript® files
can be sent on to a PostScript® printer unchanged. Text
files can be converted to PostScript® with
Enscript as shown earlier.
Create /usr/local/libexec/psif
with
these contents:
#!/bin/sh # # psif - Print PostScript or plain text on a PostScript printer # IFS="" read -r first_line first_two_chars=`expr "$first_line" : '\(..\)'` case "$first_two_chars" in %!) # %! : PostScript job, print it. echo "$first_line" && cat && exit 0 exit 2 ;; *) # otherwise, format with enscript ( echo "$first_line"; cat ) | /usr/local/bin/enscript -o - && exit 0 exit 2 ;; esac
Set the permissions and make it executable:
#
chmod 555 /usr/local/libexec/psif
Modify /etc/printcap
to use this
new input filter:
:if=/usr/local/libexec/psif:\
Test the filter by printing PostScript® and plain text files.
Writing a filter that detects many different types of input and formats them correctly is challenging. print/apsfilter from the Ports Collection is a smart “magic” filter that detects dozens of file types and automatically converts them to the PDL understood by the printer. See http://www.apsfilter.org for more details.
The entries in /etc/printcap
are
really definitions of queues. There can
be more than one queue for a single printer. When combined
with filters, multiple queues provide users more control over
how their jobs are printed.
As an example, consider a networked PostScript® laser
printer in an office. Most users want to print plain text,
but a few advanced users want to be able to print PostScript®
files directly. Two entries can be created for the same
printer in /etc/printcap
:
textprinter:\ :lp=9100@officelaser:\ :sh:\ :mx#0:\ :sd=/var/spool/lpd/textprinter:\ :if=/usr/local/libexec/enscript:\ :lf=/var/log/lpd-errs: psprinter:\ :lp=9100@officelaser:\ :sh:\ :mx#0:\ :sd=/var/spool/lpd/psprinter:\ :lf=/var/log/lpd-errs:
Documents sent to textprinter
will be
formatted by the
/usr/local/libexec/enscript
filter shown
in an earlier example. Advanced users can print PostScript®
files on psprinter
, where no filtering is
done.
This multiple queue technique can be used to provide direct access to all kinds of printer features. A printer with a duplexer could use two queues, one for ordinary single-sided printing, and one with a filter that sends the command sequence to enable double-sided printing and then sends the incoming file.
Several utilities are available to monitor print jobs and check and control printer operation.
lpq(1) shows the status of a user's print jobs. Print jobs from other users are not shown.
Show the current user's pending jobs on a single printer:
%
lpq -P
Rank Owner Job Files Total Size 1st jsmith 0 (standard input) 12792 byteslp
Show the current user's pending jobs on all printers:
%
lpq -a
lp: Rank Owner Job Files Total Size 1st jsmith 1 (standard input) 27320 bytes laser: Rank Owner Job Files Total Size 1st jsmith 287 (standard input) 22443 bytes
lprm(1) is used to remove print jobs. Normal users
are only allowed to remove their own jobs.
root
can remove
any or all jobs.
Remove all pending jobs from a printer:
#
lprm -P
dfA002smithy dequeued cfA002smithy dequeued dfA003smithy dequeued cfA003smithy dequeued dfA004smithy dequeued cfA004smithy dequeuedlp
-
Remove a single job from a printer. lpq(1) is used to find the job number.
%
lpq
Rank Owner Job Files Total Size 1st jsmith 5 (standard input) 12188 bytes%
lprm -P
dfA005smithy dequeued cfA005smithy dequeuedlp
5
lpc(8) is used to check and modify printer status.
lpc
is followed by a command and an
optional printer name. all
can be used
instead of a specific printer name, and the command will be
applied to all printers. Normal users can view status with
lpc(8). Only
root
can use
commands which modify printer status.
Show the status of all printers:
%
lpc status all
lp: queuing is enabled printing is enabled 1 entry in spool area printer idle laser: queuing is enabled printing is enabled 1 entry in spool area waiting for laser to come up
Prevent a printer from accepting new jobs, then begin accepting new jobs again:
#
lpc disable
lp: queuing disabledlp
#
lpc enable
lp: queuing enabledlp
Stop printing, but continue to accept new jobs. Then begin printing again:
#
lpc stop
lp: printing disabledlp
#
lpc start
lp: printing enabled daemon startedlp
Restart a printer after some error condition:
#
lpc restart
lp: no daemon to abort printing enabled daemon restartedlp
Turn the print queue off and disable printing, with a message to explain the problem to users:
#
lpc down
lp: printer and queuing disabled status message is now: Repair parts will arrive on Mondaylp
Repair parts will arrive on Monday
Re-enable a printer that is down:
#
lpc up
lp: printing enabled daemon startedlp
See lpc(8) for more commands and options.
Printers are often shared by multiple users in businesses and schools. Additional features are provided to make sharing printers more convenient.
The printer name is set in the first line of the
entry in /etc/printcap
. Additional
names, or aliases, can be added after
that name. Aliases are separated from the name and each
other by vertical bars:
lp|repairsprinter
|salesprinter
:\
Aliases can be used in place of the printer name. For example, users in the Sales department print to their printer with
%
lpr -P
salesprinter
sales-report.txt
Users in the Repairs department print to their printer with
%
lpr -P
repairsprinter
repairs-report.txt
All of the documents print on that single printer. When the Sales department grows enough to need their own printer, the alias can be removed from the shared printer entry and used as the name of a new printer. Users in both departments continue to use the same commands, but the Sales documents are sent to the new printer.
It can be difficult for users to locate their documents in the stack of pages produced by a busy shared printer. Header pages were created to solve this problem. A header page with the user name and document name is printed before each print job. These pages are also sometimes called banner or separator pages.
Enabling header pages differs depending on whether the printer is connected directly to the computer with a USB, parallel, or serial cable, or is connected remotely over a network.
Header pages on directly-connected printers are enabled
by removing the :sh:\
(Suppress Header)
line from the entry in /etc/printcap
.
These header pages only use line feed characters for new
lines. Some printers will need the
/usr/share/examples/printing/hpif
filter to prevent stairstepped text. The filter configures
PCL printers to print both carriage
returns and line feeds when a line feed is received.
Header pages for network printers must be configured on
the printer itself. Header page entries in
/etc/printcap
are ignored. Settings
are usually available from the printer front panel or a
configuration web page accessible with a web browser.
Several other printing systems are available in addition to the built-in lpd(8). These systems offer support for other protocols or additional features.
CUPS is a popular printing system available on many operating systems. Using CUPS on FreeBSD is documented in a separate article:../../../../doc/en_US.ISO8859-1/articles/cups
Hewlett Packard provides a printing system that supports many of their inkjet and laser printers. The port is print/hplip. The main web page is at http://hplipopensource.com/hplip-web/index.html. The port handles all the installation details on FreeBSD. Configuration information is shown at http://hplipopensource.com/hplip-web/install/manual/hp_setup.html.
LPRng was developed as an enhanced alternative to lpd(8). The port is sysutils/LPRng. For details and documentation, see http://www.lprng.com/.
FreeBSD provides binary compatibility with Linux®, allowing users to install and run most Linux® binaries on a FreeBSD system without having to first modify the binary. It has even been reported that, in some situations, Linux® binaries perform better on FreeBSD than they do on Linux®.
However, some Linux®-specific operating system features are not supported under FreeBSD. For example, Linux® binaries will not work on FreeBSD if they overly use i386™ specific calls, such as enabling virtual 8086 mode.
Support for 64-bit binary compatibility with Linux® was added in FreeBSD 10.3.
After reading this chapter, you will know:
How to enable Linux® binary compatibility on a FreeBSD system.
How to install additional Linux® shared libraries.
How to install Linux® applications on a FreeBSD system.
The implementation details of Linux® compatibility in FreeBSD.
Before reading this chapter, you should:
Know how to install additional third-party software.
By default, Linux® libraries are not installed and Linux® binary compatibility is not enabled. Linux® libraries can either be installed manually or from the FreeBSD Ports Collection.
Before attempting to build the port, load the Linux® kernel module, otherwise the build will fail:
#
kldload linux
For 64-bit compatibility:
#
kldload linux64
To verify that the module is loaded:
%
kldstat
Id Refs Address Size Name 1 2 0xc0100000 16bdb8 kernel 7 1 0xc24db000 d000 linux.ko
The emulators/linux_base-c6 package or port is the easiest way to install a base set of Linux® libraries and binaries on a FreeBSD system. To install the port:
#
pkg install emulators/linux_base-c6
For Linux® compatibility to be enabled at boot time,
add this line to /etc/rc.conf
:
linux_enable="YES"
On 64-bit machines, /etc/rc.d/abi
will
automatically load the module for 64-bit emulation.
Since the Linux® binary compatibility layer has gained support for running both 32- and 64-bit Linux® binaries (on 64-bit x86 hosts), it is no longer possible to link the emulation functionality statically into a custom kernel.
If a Linux® application complains about missing shared libraries after configuring Linux® binary compatibility, determine which shared libraries the Linux® binary needs and install them manually.
From a Linux® system, ldd
can be used
to determine which shared libraries the application needs.
For example, to check which shared libraries
linuxdoom
needs, run this command from a
Linux® system that has Doom
installed:
%
ldd linuxdoom
libXt.so.3 (DLL Jump 3.1) => /usr/X11/lib/libXt.so.3.1.0 libX11.so.3 (DLL Jump 3.1) => /usr/X11/lib/libX11.so.3.1.0 libc.so.4 (DLL Jump 4.5pl26) => /lib/libc.so.4.6.29
Then, copy all the files in the last column of the output
from the Linux® system into
/compat/linux
on the FreeBSD system. Once
copied, create symbolic links to the names in the first
column. This example will result in the following files on
the FreeBSD system:
/compat/linux/usr/X11/lib/libXt.so.3.1.0 /compat/linux/usr/X11/lib/libXt.so.3 -> libXt.so.3.1.0 /compat/linux/usr/X11/lib/libX11.so.3.1.0 /compat/linux/usr/X11/lib/libX11.so.3 -> libX11.so.3.1.0 /compat/linux/lib/libc.so.4.6.29 /compat/linux/lib/libc.so.4 -> libc.so.4.6.29
If a Linux® shared library already exists with a
matching major revision number to the first column of the
ldd
output, it does not need to be copied
to the file named in the last column, as the existing library
should work. It is advisable to copy the shared library if it
is a newer version, though. The old one can be removed, as
long as the symbolic link points to the new one.
For example, these libraries already exist on the FreeBSD system:
/compat/linux/lib/libc.so.4.6.27 /compat/linux/lib/libc.so.4 -> libc.so.4.6.27
and ldd
indicates that a binary
requires a later version:
libc.so.4 (DLL Jump 4.5pl26) -> libc.so.4.6.29
Since the existing library is only one or two versions out
of date in the last digit, the program should still work with
the slightly older version. However, it is safe to replace
the existing libc.so
with the newer
version:
/compat/linux/lib/libc.so.4.6.29 /compat/linux/lib/libc.so.4 -> libc.so.4.6.29
Generally, one will need to look for the shared libraries that Linux® binaries depend on only the first few times that a Linux® program is installed on FreeBSD. After a while, there will be a sufficient set of Linux® shared libraries on the system to be able to run newly installed Linux® binaries without any extra work.
ELF binaries sometimes require an extra step. When an unbranded ELF binary is executed, it will generate an error message:
%
./my-linux-elf-binary
ELF binary type not known Abort
To help the FreeBSD kernel distinguish between a FreeBSD ELF binary and a Linux® binary, use brandelf(1):
%
brandelf -t Linux my-linux-elf-binary
Since the GNU toolchain places the appropriate branding information into ELF binaries automatically, this step is usually not necessary.
To install a Linux® RPM-based
application, first install the
archivers/rpm4 package or port. Once
installed, root
can
use this command to install a
.rpm
:
#
cd /compat/linux
#
rpm2cpio < /path/to/linux.archive.rpm | cpio -id
If necessary, brandelf
the installed
ELF binaries. Note that this will prevent
a clean uninstall.
If DNS does not work or this error appears:
resolv+: "bind" is an invalid keyword resolv+: "hosts" is an invalid keyword
configure /compat/linux/etc/host.conf
as follows:
order hosts, bind multi on
This specifies that /etc/hosts
is
searched first and DNS is searched second.
When /compat/linux/etc/host.conf
does not
exist, Linux® applications use
/etc/host.conf
and complain about the
incompatible FreeBSD syntax. Remove bind
if a
name server is not configured using
/etc/resolv.conf
.
This section describes how Linux® binary compatibility
works and is based on an email written to FreeBSD chat mailing list by
Terry Lambert <tlambert@primenet.com>
(Message ID:
<199906020108.SAA07001@usr09.primenet.com>
).
FreeBSD has an abstraction called an “execution class loader”. This is a wedge into the execve(2) system call.
Historically, the UNIX® loader examined the magic number (generally the first 4 or 8 bytes of the file) to see if it was a binary known to the system, and if so, invoked the binary loader.
If it was not the binary type for the system, the execve(2) call returned a failure, and the shell attempted to start executing it as shell commands. The assumption was a default of “whatever the current shell is”.
Later, a hack was made for sh(1) to examine the first
two characters, and if they were :\n
, it
invoked the csh(1) shell instead.
FreeBSD has a list of loaders, instead of a single loader, with
a fallback to the #!
loader for running shell
interpreters or shell scripts.
For the Linux® ABI support, FreeBSD sees the magic number as an ELF binary. The ELF loader looks for a specialized brand, which is a comment section in the ELF image, and which is not present on SVR4/Solaris™ ELF binaries.
For Linux® binaries to function, they must be
branded as type Linux
using brandelf(1):
#
brandelf -t Linux file
When the ELF loader sees the Linux
brand, the loader replaces a pointer in the
proc
structure. All system calls are indexed
through this pointer. In addition, the process is flagged for
special handling of the trap vector for the signal trampoline
code, and several other (minor) fix-ups that are handled by the
Linux® kernel module.
The Linux® system call vector contains, among other things,
a list of sysent[]
entries whose addresses
reside in the kernel module.
When a system call is called by the Linux® binary, the trap
code dereferences the system call function pointer off the
proc
structure, and gets the Linux®, not the
FreeBSD, system call entry points.
Linux® mode dynamically reroots
lookups. This is, in effect, equivalent to
union
to file system mounts. First, an
attempt is made to lookup the file in
/compat/linux/
.
If that fails, the lookup is done in
original-path
/
.
This makes sure that binaries that require other binaries can
run. For example, the Linux® toolchain can all run under
Linux® ABI support. It also means that the
Linux® binaries can load and execute FreeBSD binaries, if there
are no corresponding Linux® binaries present, and that a
uname(1) command can be placed in the
original-path
/compat/linux
directory tree to ensure that
the Linux® binaries cannot tell they are not running on
Linux®.
In effect, there is a Linux® kernel in the FreeBSD kernel. The various underlying functions that implement all of the services provided by the kernel are identical to both the FreeBSD system call table entries, and the Linux® system call table entries: file system operations, virtual memory operations, signal delivery, and System V IPC. The only difference is that FreeBSD binaries get the FreeBSD glue functions, and Linux® binaries get the Linux® glue functions. The FreeBSD glue functions are statically linked into the kernel, and the Linux® glue functions can be statically linked, or they can be accessed via a kernel module.
Technically, this is not really emulation, it is an ABI implementation. It is sometimes called “Linux® emulation” because the implementation was done at a time when there was no other word to describe what was going on. Saying that FreeBSD ran Linux® binaries was not true, since the code was not compiled in.
The remaining chapters cover all aspects of FreeBSD system administration. Each chapter starts by describing what will be learned as a result of reading the chapter, and also details what the reader is expected to know before tackling the material.
These chapters are designed to be read as the information is needed. They do not need to be read in any particular order, nor must all of them be read before beginning to use FreeBSD.
One of the important aspects of FreeBSD is proper system configuration. This chapter explains much of the FreeBSD configuration process, including some of the parameters which can be set to tune a FreeBSD system.
After reading this chapter, you will know:
The basics of rc.conf
configuration
and /usr/local/etc/rc.d
startup
scripts.
How to configure and test a network card.
How to configure virtual hosts on network devices.
How to use the various configuration files in
/etc
.
How to tune FreeBSD using sysctl(8) variables.
How to tune disk performance and modify kernel limitations.
Before reading this chapter, you should:
Understand UNIX® and FreeBSD basics (Chapter 3, FreeBSD Basics).
Be familiar with the basics of kernel configuration and compilation (Chapter 8, Configuring the FreeBSD Kernel).
Many users install third party software on FreeBSD from the Ports Collection and require the installed services to be started upon system initialization. Services, such as mail/postfix or www/apache22 are just two of the many software packages which may be started during system initialization. This section explains the procedures available for starting third party software.
In FreeBSD, most included services, such as cron(8), are started through the system startup scripts.
Now that FreeBSD includes rc.d
,
configuration of application startup is easier and provides
more features. Using the key words discussed in
Section 11.4, “Managing Services in FreeBSD”, applications can be set to
start after certain other services and extra flags can be
passed through /etc/rc.conf
in place of
hard coded flags in the startup script. A basic script may
look similar to the following:
#!/bin/sh # # PROVIDE: utility # REQUIRE: DAEMON # KEYWORD: shutdown . /etc/rc.subr name=utility rcvar=utility_enable command="/usr/local/sbin/utility" load_rc_config $name # # DO NOT CHANGE THESE DEFAULT VALUES HERE # SET THEM IN THE /etc/rc.conf FILE # utility_enable=${utility_enable-"NO"} pidfile=${utility_pidfile-"/var/run/utility.pid"} run_rc_command "$1"
This script will ensure that the provided
utility
will be started after the
DAEMON
pseudo-service. It also provides a
method for setting and tracking the process ID
(PID).
This application could then have the following line placed
in /etc/rc.conf
:
utility_enable="YES"
This method allows for easier manipulation of command
line arguments, inclusion of the default functions provided
in /etc/rc.subr
, compatibility with
rcorder(8), and provides for easier configuration via
rc.conf
.
Other services can be started using inetd(8). Working with inetd(8) and its configuration is described in depth in Section 29.2, “The inetd Super-Server”.
In some cases, it may make more sense to use cron(8) to start system services. This approach has a number of advantages as cron(8) runs these processes as the owner of the crontab(5). This allows regular users to start and maintain their own applications.
The @reboot
feature of cron(8),
may be used in place of the time specification. This causes
the job to run when cron(8) is started, normally during
system initialization.
One of the most useful utilities in FreeBSD is
cron. This utility runs in the
background and regularly checks
/etc/crontab
for tasks to execute and
searches /var/cron/tabs
for custom crontab
files. These files are used to schedule tasks which
cron runs at the specified times.
Each entry in a crontab defines a task to run and is known as a
cron job.
Two different types of configuration files are used: the
system crontab, which should not be modified, and user crontabs,
which can be created and edited as needed. The format used by
these files is documented in crontab(5). The format of the
system crontab, /etc/crontab
includes a
who
column which does not exist in user
crontabs. In the system crontab,
cron runs the command as the user
specified in this column. In a user crontab, all commands run
as the user who created the crontab.
User crontabs allow individual users to schedule their own
tasks. The root
user
can also have a user crontab
which can be
used to schedule tasks that do not exist in the system
crontab
.
Here is a sample entry from the system crontab,
/etc/crontab
:
# /etc/crontab - root's crontab for FreeBSD # # $FreeBSD$ # SHELL=/bin/sh PATH=/etc:/bin:/sbin:/usr/bin:/usr/sbin # #minute hour mday month wday who command # */5 * * * * root /usr/libexec/atrun
Lines that begin with the | |
The equals ( | |
This line defines the seven fields used in a system
crontab: | |
This entry defines the values for this cron job. The
Commands can include any number of switches. However, commands which extend to multiple lines need to be broken with the backslash “\” continuation character. |
To create a user crontab, invoke
crontab
in editor mode:
%
crontab -e
This will open the user's crontab using the default text editor. The first time a user runs this command, it will open an empty file. Once a user creates a crontab, this command will open that file for editing.
It is useful to add these lines to the top of the crontab file in order to set the environment variables and to remember the meanings of the fields in the crontab:
SHELL=/bin/sh PATH=/etc:/bin:/sbin:/usr/bin:/usr/sbin # Order of crontab fields # minute hour mday month wday command
Then add a line for each command or script to run,
specifying the time to run the command. This example runs the
specified custom Bourne shell script every day at two in the
afternoon. Since the path to the script is not specified in
PATH
, the full path to the script is
given:
0 14 * * * /usr/home/dru/bin/mycustomscript.sh
Before using a custom script, make sure it is executable and test it with the limited set of environment variables set by cron. To replicate the environment that would be used to run the above cron entry, use:
env -i SHELL=/bin/sh PATH=/etc:/bin:/sbin:/usr/bin:/usr/sbin HOME=/home/dru
LOGNAME=dru
/usr/home/dru/bin/mycustomscript.sh
The environment set by cron is discussed in crontab(5). Checking that scripts operate correctly in a cron environment is especially important if they include any commands that delete files using wildcards.
When finished editing the crontab, save the file. It will automatically be installed and cron will read the crontab and run its cron jobs at their specified times. To list the cron jobs in a crontab, use this command:
%
crontab -l
0 14 * * * /usr/home/dru/bin/mycustomscript.sh
To remove all of the cron jobs in a user crontab:
%
crontab -r
remove crontab for dru?y
FreeBSD uses the rc(8) system of startup scripts during
system initialization and for managing services. The scripts
listed in /etc/rc.d
provide basic services
which can be controlled with the start
,
stop
, and restart
options to
service(8). For instance, sshd(8) can be restarted
with the following command:
#
service sshd restart
This procedure can be used to start services on a running
system. Services will be started automatically at boot time
as specified in rc.conf(5). For example, to enable
natd(8) at system startup, add the following line to
/etc/rc.conf
:
natd_enable="YES"
If a natd_enable="NO"
line is already
present, change the NO
to
YES
. The rc(8) scripts will
automatically load any dependent services during the next boot,
as described below.
Since the rc(8) system is primarily intended to start
and stop services at system startup and shutdown time, the
start
, stop
and
restart
options will only perform their action
if the appropriate /etc/rc.conf
variable
is set. For instance, sshd restart
will
only work if sshd_enable
is set to
YES
in /etc/rc.conf
.
To start
, stop
or
restart
a service regardless of the settings
in /etc/rc.conf
, these commands should be
prefixed with “one”. For instance, to restart
sshd(8) regardless of the current
/etc/rc.conf
setting, execute the following
command:
#
service sshd onerestart
To check if a service is enabled in
/etc/rc.conf
, run the appropriate
rc(8) script with rcvar
. This example
checks to see if sshd(8) is enabled in
/etc/rc.conf
:
#
service sshd rcvar
# sshd # sshd_enable="YES" # (default: "")
The # sshd
line is output from the
above command, not a
root
console.
To determine whether or not a service is running, use
status
. For instance, to verify that
sshd(8) is running:
#
service sshd status
sshd is running as pid 433.
In some cases, it is also possible to
reload
a service. This attempts to send a
signal to an individual service, forcing the service to reload
its configuration files. In most cases, this means sending
the service a SIGHUP
signal. Support for
this feature is not included for every service.
The rc(8) system is used for network services and it
also contributes to most of the system initialization. For
instance, when the
/etc/rc.d/bgfsck
script is executed, it
prints out the following message:
Starting background file system checks in 60 seconds.
This script is used for background file system checks, which occur only during system initialization.
Many system services depend on other services to function properly. For example, yp(8) and other RPC-based services may fail to start until after the rpcbind(8) service has started. To resolve this issue, information about dependencies and other meta-data is included in the comments at the top of each startup script. The rcorder(8) program is used to parse these comments during system initialization to determine the order in which system services should be invoked to satisfy the dependencies.
The following key word must be included in all startup scripts as it is required by rc.subr(8) to “enable” the startup script:
PROVIDE
: Specifies the services this
file provides.
The following key words may be included at the top of each startup script. They are not strictly necessary, but are useful as hints to rcorder(8):
REQUIRE
: Lists services which are
required for this service. The script containing this key
word will run after the specified
services.
BEFORE
: Lists services which depend
on this service. The script containing this key word will
run before the specified
services.
By carefully setting these keywords for each startup script, an administrator has a fine-grained level of control of the startup order of the scripts, without the need for “runlevels” used by some UNIX® operating systems.
Additional information can be found in rc(8) and rc.subr(8). Refer to this article for instructions on how to create custom rc(8) scripts.
The principal location for system configuration
information is /etc/rc.conf
. This file
contains a wide range of configuration information and it is
read at system startup to configure the system. It provides
the configuration information for the
rc*
files.
The entries in /etc/rc.conf
override
the default settings in
/etc/defaults/rc.conf
. The file
containing the default settings should not be edited.
Instead, all system-specific changes should be made to
/etc/rc.conf
.
A number of strategies may be applied in clustered
applications to separate site-wide configuration from
system-specific configuration in order to reduce
administration overhead. The recommended approach is to place
system-specific configuration into
/etc/rc.conf.local
. For example, these
entries in /etc/rc.conf
apply to all
systems:
sshd_enable="YES" keyrate="fast" defaultrouter="10.1.1.254"
Whereas these entries in
/etc/rc.conf.local
apply to this system
only:
hostname="node1.example.org" ifconfig_fxp0="inet 10.1.1.1/8"
Distribute /etc/rc.conf
to every
system using an application such as
rsync or
puppet, while
/etc/rc.conf.local
remains
unique.
Upgrading the system will not overwrite
/etc/rc.conf
, so system configuration
information will not be lost.
Both /etc/rc.conf
and
/etc/rc.conf.local
are parsed by sh(1). This allows system operators to
create complex configuration scenarios. Refer to
rc.conf(5) for further information on this
topic.
Adding and configuring a network interface card (NIC) is a common task for any FreeBSD administrator.
First, determine the model of the NIC and the chip it uses. FreeBSD supports a wide variety of NICs. Check the Hardware Compatibility List for the FreeBSD release to see if the NIC is supported.
If the NIC is supported, determine
the name of the FreeBSD driver for the NIC.
Refer to /usr/src/sys/conf/NOTES
and
/usr/src/sys/
for the list of NIC drivers with some
information about the supported chipsets. When in doubt, read
the manual page of the driver as it will provide more
information about the supported hardware and any known
limitations of the driver.arch
/conf/NOTES
The drivers for common NICs are already
present in the GENERIC
kernel, meaning
the NIC should be probed during boot. The
system's boot messages can be viewed by typing
more /var/run/dmesg.boot
and using the
spacebar to scroll through the text. In this example, two
Ethernet NICs using the dc(4) driver
are present on the system:
dc0: <82c169 PNIC 10/100BaseTX> port 0xa000-0xa0ff mem 0xd3800000-0xd38 000ff irq 15 at device 11.0 on pci0 miibus0: <MII bus> on dc0 bmtphy0: <BCM5201 10/100baseTX PHY> PHY 1 on miibus0 bmtphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto dc0: Ethernet address: 00:a0:cc:da:da:da dc0: [ITHREAD] dc1: <82c169 PNIC 10/100BaseTX> port 0x9800-0x98ff mem 0xd3000000-0xd30 000ff irq 11 at device 12.0 on pci0 miibus1: <MII bus> on dc1 bmtphy1: <BCM5201 10/100baseTX PHY> PHY 1 on miibus1 bmtphy1: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto dc1: Ethernet address: 00:a0:cc:da:da:db dc1: [ITHREAD]
If the driver for the NIC is not
present in GENERIC
, but a driver is
available, the driver will need to be loaded before the
NIC can be configured and used. This may
be accomplished in one of two ways:
The easiest way is to load a kernel module for the
NIC using kldload(8). To also
automatically load the driver at boot time, add the
appropriate line to
/boot/loader.conf
. Not all
NIC drivers are available as
modules.
Alternatively, statically compile support for the
NIC into a custom kernel. Refer to
/usr/src/sys/conf/NOTES
,
/usr/src/sys/
and the manual page of the driver to determine which line
to add to the custom kernel configuration file. For more
information about recompiling the kernel, refer to Chapter 8, Configuring the FreeBSD Kernel. If the NIC
was detected at boot, the kernel does not need to be
recompiled.arch
/conf/NOTES
Unfortunately, there are still many vendors that do not provide schematics for their drivers to the open source community because they regard such information as trade secrets. Consequently, the developers of FreeBSD and other operating systems are left with two choices: develop the drivers by a long and pain-staking process of reverse engineering or using the existing driver binaries available for Microsoft® Windows® platforms.
FreeBSD provides “native” support for the Network Driver Interface Specification (NDIS). It includes ndisgen(8) which can be used to convert a Windows® XP driver into a format that can be used on FreeBSD. Because the ndis(4) driver uses a Windows® XP binary, it only runs on i386™ and amd64 systems. PCI, CardBus, PCMCIA, and USB devices are supported.
To use ndisgen(8), three things are needed:
FreeBSD kernel sources.
A Windows® XP driver binary with a
.SYS
extension.
A Windows® XP driver configuration file with a
.INF
extension.
Download the .SYS
and
.INF
files for the specific
NIC. Generally, these can be found on
the driver CD or at the vendor's website. The following
examples use W32DRIVER.SYS
and
W32DRIVER.INF
.
The driver bit width must match the version of FreeBSD. For FreeBSD/i386, use a Windows® 32-bit driver. For FreeBSD/amd64, a Windows® 64-bit driver is needed.
The next step is to compile the driver binary into a
loadable kernel module. As
root
, use
ndisgen(8):
#
ndisgen
/path/to/W32DRIVER.INF
/path/to/W32DRIVER.SYS
This command is interactive and prompts for any extra information it requires. A new kernel module will be generated in the current directory. Use kldload(8) to load the new module:
#
kldload
./W32DRIVER_SYS.ko
In addition to the generated kernel module, the
ndis.ko
and
if_ndis.ko
modules must be loaded.
This should happen automatically when any module that
depends on ndis(4) is loaded. If not, load them
manually, using the following commands:
#
kldload ndis
#
kldload if_ndis
The first command loads the ndis(4) miniport driver wrapper and the second loads the generated NIC driver.
Check dmesg(8) to see if there were any load errors. If all went well, the output should be similar to the following:
ndis0: <Wireless-G PCI Adapter> mem 0xf4100000-0xf4101fff irq 3 at device 8.0 on pci1 ndis0: NDIS API version: 5.0 ndis0: Ethernet address: 0a:b1:2c:d3:4e:f5 ndis0: 11b rates: 1Mbps 2Mbps 5.5Mbps 11Mbps ndis0: 11g rates: 6Mbps 9Mbps 12Mbps 18Mbps 36Mbps 48Mbps 54Mbps
From here, ndis0
can be
configured like any other NIC.
To configure the system to load the ndis(4) modules
at boot time, copy the generated module,
W32DRIVER_SYS.ko
, to
/boot/modules
. Then, add the following
line to /boot/loader.conf
:
W32DRIVER_SYS_load="YES"
Once the right driver is loaded for the NIC, the card needs to be configured. It may have been configured at installation time by bsdinstall(8).
To display the NIC configuration, enter the following command:
%
ifconfig
dc0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 options=80008<VLAN_MTU,LINKSTATE> ether 00:a0:cc:da:da:da inet 192.168.1.3 netmask 0xffffff00 broadcast 192.168.1.255 media: Ethernet autoselect (100baseTX <full-duplex>) status: active dc1: flags=8802<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 options=80008<VLAN_MTU,LINKSTATE> ether 00:a0:cc:da:da:db inet 10.0.0.1 netmask 0xffffff00 broadcast 10.0.0.255 media: Ethernet 10baseT/UTP status: no carrier lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384 options=3<RXCSUM,TXCSUM> inet6 fe80::1%lo0 prefixlen 64 scopeid 0x4 inet6 ::1 prefixlen 128 inet 127.0.0.1 netmask 0xff000000 nd6 options=3<PERFORMNUD,ACCEPT_RTADV>
In this example, the following devices were displayed:
dc0
: The first Ethernet
interface.
dc1
: The second Ethernet
interface.
lo0
: The loopback
device.
FreeBSD uses the driver name followed by the order in which
the card is detected at boot to name the
NIC. For example,
sis2
is the third
NIC on the system using the sis(4)
driver.
In this example, dc0
is up and
running. The key indicators are:
UP
means that the card is
configured and ready.
The card has an Internet (inet
)
address, 192.168.1.3
.
It has a valid subnet mask
(netmask
), where
0xffffff00
is the
same as 255.255.255.0
.
It has a valid broadcast address, 192.168.1.255
.
The MAC address of the card
(ether
) is 00:a0:cc:da:da:da
.
The physical media selection is on autoselection mode
(media: Ethernet autoselect (100baseTX
<full-duplex>)
). In this example,
dc1
is configured to run with
10baseT/UTP
media. For more
information on available media types for a driver, refer
to its manual page.
The status of the link (status
) is
active
, indicating that the carrier
signal is detected. For dc1
, the
status: no carrier
status is normal
when an Ethernet cable is not plugged into the
card.
If the ifconfig(8) output had shown something similar to:
dc0: flags=8843<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1500 options=80008<VLAN_MTU,LINKSTATE> ether 00:a0:cc:da:da:da media: Ethernet autoselect (100baseTX <full-duplex>) status: active
it would indicate the card has not been configured.
The card must be configured as
root
. The
NIC configuration can be performed from the
command line with ifconfig(8) but will not persist after
a reboot unless the configuration is also added to
/etc/rc.conf
. If a
DHCP server is present on the LAN,
just add this line:
ifconfig_dc0="DHCP"
Replace dc0
with the correct
value for the system.
The line added, then, follow the instructions given in Section 11.5.3, “Testing and Troubleshooting”.
If the network was configured during installation, some
entries for the NIC(s) may be already
present. Double check /etc/rc.conf
before adding any lines.
In the case, there is no DHCP server, the NIC(s) have to be configured manually. Add a line for each NIC present on the system, as seen in this example:
ifconfig_dc0="inet 192.168.1.3 netmask 255.255.255.0" ifconfig_dc1="inet 10.0.0.1 netmask 255.255.255.0 media 10baseT/UTP"
Replace dc0
and
dc1
and the IP
address information with the correct values for the system.
Refer to the man page for the driver, ifconfig(8), and
rc.conf(5) for more details about the allowed options and
the syntax of /etc/rc.conf
.
If the network is not using DNS, edit
/etc/hosts
to add the names and
IP addresses of the hosts on the
LAN, if they are not already there. For
more information, refer to hosts(5) and to
/usr/share/examples/etc/hosts
.
If there is no DHCP server and access to the Internet is needed, manually configure the default gateway and the nameserver:
#
echo 'defaultrouter="
your_default_router
"' >> /etc/rc.conf#
echo 'nameserver
your_DNS_server
' >> /etc/resolv.conf
Once the necessary changes to
/etc/rc.conf
are saved, a reboot can be
used to test the network configuration and to verify that the
system restarts without any configuration errors.
Alternatively, apply the settings to the networking system
with this command:
#
service netif restart
If a default gateway has been set in
/etc/rc.conf
, also issue this
command:
#
service routing restart
Once the networking system has been relaunched, test the NICs.
To verify that an Ethernet card is configured correctly, ping(8) the interface itself, and then ping(8) another machine on the LAN:
%
ping -c5 192.168.1.3
PING 192.168.1.3 (192.168.1.3): 56 data bytes 64 bytes from 192.168.1.3: icmp_seq=0 ttl=64 time=0.082 ms 64 bytes from 192.168.1.3: icmp_seq=1 ttl=64 time=0.074 ms 64 bytes from 192.168.1.3: icmp_seq=2 ttl=64 time=0.076 ms 64 bytes from 192.168.1.3: icmp_seq=3 ttl=64 time=0.108 ms 64 bytes from 192.168.1.3: icmp_seq=4 ttl=64 time=0.076 ms --- 192.168.1.3 ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max/stddev = 0.074/0.083/0.108/0.013 ms
%
ping -c5 192.168.1.2
PING 192.168.1.2 (192.168.1.2): 56 data bytes 64 bytes from 192.168.1.2: icmp_seq=0 ttl=64 time=0.726 ms 64 bytes from 192.168.1.2: icmp_seq=1 ttl=64 time=0.766 ms 64 bytes from 192.168.1.2: icmp_seq=2 ttl=64 time=0.700 ms 64 bytes from 192.168.1.2: icmp_seq=3 ttl=64 time=0.747 ms 64 bytes from 192.168.1.2: icmp_seq=4 ttl=64 time=0.704 ms --- 192.168.1.2 ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max/stddev = 0.700/0.729/0.766/0.025 ms
To test network resolution, use the host name instead
of the IP address. If there is no
DNS server on the network,
/etc/hosts
must first be
configured. To this purpose, edit
/etc/hosts
to add the names and
IP addresses of the hosts on the
LAN, if they are not already there. For
more information, refer to hosts(5) and to
/usr/share/examples/etc/hosts
.
When troubleshooting hardware and software configurations, check the simple things first. Is the network cable plugged in? Are the network services properly configured? Is the firewall configured correctly? Is the NIC supported by FreeBSD? Before sending a bug report, always check the Hardware Notes, update the version of FreeBSD to the latest STABLE version, check the mailing list archives, and search the Internet.
If the card works, yet performance is poor, read through tuning(7). Also, check the network configuration as incorrect network settings can cause slow connections.
Some users experience one or two device timeout messages, which is normal for some cards. If they continue, or are bothersome, determine if the device is conflicting with another device. Double check the cable connections. Consider trying another card.
To resolve watchdog timeout errors, first check the network cable. Many cards require a PCI slot which supports bus mastering. On some old motherboards, only one PCI slot allows it, usually slot 0. Check the NIC and the motherboard documentation to determine if that may be the problem.
No route to host messages occur
if the system is unable to route a packet to the destination
host. This can happen if no default route is specified or
if a cable is unplugged. Check the output of
netstat -rn
and make sure there is a
valid route to the host. If there is not, read
Section 31.2, “Gateways and Routes”.
ping: sendto: Permission denied error messages are often caused by a misconfigured firewall. If a firewall is enabled on FreeBSD but no rules have been defined, the default policy is to deny all traffic, even ping(8). Refer to Chapter 30, Firewalls for more information.
Sometimes performance of the card is poor or below
average. In these cases, try setting the media
selection mode from autoselect
to the
correct media selection. While this works for most
hardware, it may or may not resolve the issue. Again,
check all the network settings, and refer to
tuning(7).
A common use of FreeBSD is virtual site hosting, where one server appears to the network as many servers. This is achieved by assigning multiple network addresses to a single interface.
A given network interface has one “real”
address, and may have any number of “alias”
addresses. These aliases are normally added by placing alias
entries in /etc/rc.conf
, as seen in this
example:
ifconfig_fxp0_alias0="inet xxx.xxx.xxx.xxx netmask xxx.xxx.xxx.xxx"
Alias entries must start with
alias
using a
sequential number such as
0
alias0
, alias1
,
and so on. The configuration process will stop at the first
missing number.
The calculation of alias netmasks is important. For a
given interface, there must be one address which correctly
represents the network's netmask. Any other addresses which
fall within this network must have a netmask of all
1
s, expressed as either
255.255.255.255
or
0xffffffff
.
For example, consider the case where the
fxp0
interface is connected to two
networks: 10.1.1.0
with a netmask of
255.255.255.0
and
202.0.75.16
with a
netmask of
255.255.255.240
. The
system is to be configured to appear in the ranges
10.1.1.1
through
10.1.1.5
and
202.0.75.17
through
202.0.75.20
. Only
the first address in a given network range should have a real
netmask. All the rest
(10.1.1.2
through
10.1.1.5
and
202.0.75.18
through
202.0.75.20
) must be
configured with a netmask of
255.255.255.255
.
The following /etc/rc.conf
entries
configure the adapter correctly for this scenario:
ifconfig_fxp0="inet 10.1.1.1 netmask 255.255.255.0" ifconfig_fxp0_alias0="inet 10.1.1.2 netmask 255.255.255.255" ifconfig_fxp0_alias1="inet 10.1.1.3 netmask 255.255.255.255" ifconfig_fxp0_alias2="inet 10.1.1.4 netmask 255.255.255.255" ifconfig_fxp0_alias3="inet 10.1.1.5 netmask 255.255.255.255" ifconfig_fxp0_alias4="inet 202.0.75.17 netmask 255.255.255.240" ifconfig_fxp0_alias5="inet 202.0.75.18 netmask 255.255.255.255" ifconfig_fxp0_alias6="inet 202.0.75.19 netmask 255.255.255.255" ifconfig_fxp0_alias7="inet 202.0.75.20 netmask 255.255.255.255"
A simpler way to express this is with a space-separated list
of IP address ranges. The first address
will be given the
indicated subnet mask and the additional addresses will have a
subnet mask of 255.255.255.255
.
ifconfig_fxp0_aliases="inet 10.1.1.1-5/24 inet 202.0.75.17-20/28"
Generating and reading system logs is an important aspect of system administration. The information in system logs can be used to detect hardware and software issues as well as application and system configuration errors. This information also plays an important role in security auditing and incident response. Most system daemons and applications will generate log entries.
FreeBSD provides a system logger,
syslogd, to manage logging. By
default, syslogd is started when the
system boots. This is controlled by the variable
syslogd_enable
in
/etc/rc.conf
. There are numerous
application arguments that can be set using
syslogd_flags
in
/etc/rc.conf
. Refer to syslogd(8) for
more information on the available arguments.
This section describes how to configure the FreeBSD system logger for both local and remote logging and how to perform log rotation and log management.
The configuration file,
/etc/syslog.conf
, controls what
syslogd does with log entries as
they are received. There are several parameters to control
the handling of incoming events. The
facility describes which subsystem
generated the message, such as the kernel or a daemon, and the
level describes the severity of the
event that occurred. This makes it possible to configure if
and where a log message is logged, depending on the facility
and level. It is also possible to take action depending on
the application that sent the message, and in the case of
remote logging, the hostname of the machine generating the
logging event.
This configuration file contains one line per action,
where the syntax for each line is a selector field followed by
an action field. The syntax of the selector field is
facility.level
which will match log
messages from facility
at level
level
or higher. It is also
possible to add an optional comparison flag before the level
to specify more precisely what is logged. Multiple selector
fields can be used for the same action, and are separated with
a semicolon (;
). Using
*
will match everything. The action field
denotes where to send the log message, such as to a file or
remote log host. As an example, here is the default
syslog.conf
from FreeBSD:
# $FreeBSD$
#
# Spaces ARE valid field separators in this file. However,
# other *nix-like systems still insist on using tabs as field
# separators. If you are sharing this file between systems, you
# may want to use only tabs as field separators here.
# Consult the syslog.conf(5) manpage.
*.err;kern.warning;auth.notice;mail.crit /dev/console
*.notice;authpriv.none;kern.debug;lpr.info;mail.crit;news.err /var/log/messages
security.* /var/log/security
auth.info;authpriv.info /var/log/auth.log
mail.info /var/log/maillog
lpr.info /var/log/lpd-errs
ftp.info /var/log/xferlog
cron.* /var/log/cron
!-devd
*.=debug /var/log/debug.log
*.emerg *
# uncomment this to log all writes to /dev/console to /var/log/console.log
#console.info /var/log/console.log
# uncomment this to enable logging of all log messages to /var/log/all.log
# touch /var/log/all.log and chmod it to mode 600 before it will work
#*.* /var/log/all.log
# uncomment this to enable logging to a remote loghost named loghost
#*.* @loghost
# uncomment these if you're running inn
# news.crit /var/log/news/news.crit
# news.err /var/log/news/news.err
# news.notice /var/log/news/news.notice
# Uncomment this if you wish to see messages produced by devd
# !devd
# *.>=info
!ppp
*.* /var/log/ppp.log
!*
In this example:
Line 8 matches all messages with a level of
err
or higher, as well as
kern.warning
,
auth.notice
and
mail.crit
, and sends these log messages
to the console
(/dev/console
).
Line 12 matches all messages from the
mail
facility at level
info
or above and logs the messages to
/var/log/maillog
.
Line 17 uses a comparison flag (=
)
to only match messages at level debug
and logs them to
/var/log/debug.log
.
Line 33 is an example usage of a program
specification. This makes the rules following it only
valid for the specified program. In this case, only the
messages generated by ppp are
logged to /var/log/ppp.log
.
The available levels, in order from most to least
critical are emerg
,
alert
, crit
,
err
, warning
,
notice
, info
, and
debug
.
The facilities, in no particular order, are
auth
, authpriv
,
console
, cron
,
daemon
, ftp
,
kern
, lpr
,
mail
, mark
,
news
, security
,
syslog
, user
,
uucp
, and local0
through
local7
. Be aware that other operating
systems might have different facilities.
To log everything of level notice
and
higher to /var/log/daemon.log
, add the
following entry:
daemon.notice /var/log/daemon.log
For more information about the different levels and
facilities, refer to syslog(3) and syslogd(8).
For more information about
/etc/syslog.conf
, its syntax, and more
advanced usage examples, see syslog.conf(5).
Log files can grow quickly, taking up disk space and making it more difficult to locate useful information. Log management attempts to mitigate this. In FreeBSD, newsyslog is used to manage log files. This built-in program periodically rotates and compresses log files, and optionally creates missing log files and signals programs when log files are moved. The log files may be generated by syslogd or by any other program which generates log files. While newsyslog is normally run from cron(8), it is not a system daemon. In the default configuration, it runs every hour.
To know which actions to take,
newsyslog reads its configuration
file, /etc/newsyslog.conf
. This file
contains one line for each log file that
newsyslog manages. Each line
states the file owner, permissions, when to rotate that file,
optional flags that affect log rotation, such as compression,
and programs to signal when the log is rotated. Here is the
default configuration in FreeBSD:
# configuration file for newsyslog
# $FreeBSD$
#
# Entries which do not specify the '/pid_file' field will cause the
# syslogd process to be signalled when that log file is rotated. This
# action is only appropriate for log files which are written to by the
# syslogd process (ie, files listed in /etc/syslog.conf). If there
# is no process which needs to be signalled when a given log file is
# rotated, then the entry for that file should include the 'N' flag.
#
# The 'flags' field is one or more of the letters: BCDGJNUXZ or a '-'.
#
# Note: some sites will want to select more restrictive protections than the
# defaults. In particular, it may be desirable to switch many of the 644
# entries to 640 or 600. For example, some sites will consider the
# contents of maillog, messages, and lpd-errs to be confidential. In the
# future, these defaults may change to more conservative ones.
#
# logfilename [owner:group] mode count size when flags [/pid_file] [sig_num]
/var/log/all.log 600 7 * @T00 J
/var/log/amd.log 644 7 100 * J
/var/log/auth.log 600 7 100 @0101T JC
/var/log/console.log 600 5 100 * J
/var/log/cron 600 3 100 * JC
/var/log/daily.log 640 7 * @T00 JN
/var/log/debug.log 600 7 100 * JC
/var/log/kerberos.log 600 7 100 * J
/var/log/lpd-errs 644 7 100 * JC
/var/log/maillog 640 7 * @T00 JC
/var/log/messages 644 5 100 @0101T JC
/var/log/monthly.log 640 12 * $M1D0 JN
/var/log/pflog 600 3 100 * JB /var/run/pflogd.pid
/var/log/ppp.log root:network 640 3 100 * JC
/var/log/devd.log 644 3 100 * JC
/var/log/security 600 10 100 * JC
/var/log/sendmail.st 640 10 * 168 B
/var/log/utx.log 644 3 * @01T05 B
/var/log/weekly.log 640 5 1 $W6D0 JN
/var/log/xferlog 600 7 100 * JC
Each line starts with the name of the log to be rotated,
optionally followed by an owner and group for both rotated and
newly created files. The mode
field sets
the permissions on the log file and count
denotes how many rotated log files should be kept. The
size
and when
fields
tell newsyslog when to rotate the
file. A log file is rotated when either its size is larger
than the size
field or when the time in the
when
field has passed. An asterisk
(*
) means that this field is ignored. The
flags
field gives further
instructions, such as how to compress the rotated file or to
create the log file if it is missing. The last two fields are
optional and specify the name of the Process ID
(PID) file of a process and a signal number
to send to that process when the file is rotated.
For more information on all fields, valid flags, and how to specify the rotation time, refer to newsyslog.conf(5). Since newsyslog is run from cron(8), it cannot rotate files more often than it is scheduled to run from cron(8).
Monitoring the log files of multiple hosts can become unwieldy as the number of systems increases. Configuring centralized logging can reduce some of the administrative burden of log file administration.
In FreeBSD, centralized log file aggregation, merging, and
rotation can be configured using
syslogd and
newsyslog. This section
demonstrates an example configuration, where host
A
, named logserv.example.com
, will
collect logging information for the local network. Host
B
, named logclient.example.com
,
will be configured to pass logging information to the logging
server.
A log server is a system that has been configured to accept logging information from other hosts. Before configuring a log server, check the following:
If there is a firewall between the logging server and any logging clients, ensure that the firewall ruleset allows UDP port 514 for both the clients and the server.
The logging server and all client machines must
have forward and reverse entries in the local
DNS. If the network does not have a
DNS server, create entries in each
system's /etc/hosts
. Proper name
resolution is required so that log entries are not
rejected by the logging server.
On the log server, edit
/etc/syslog.conf
to specify the name of
the client to receive log entries from, the logging facility
to be used, and the name of the log to store the host's log
entries. This example adds the hostname of
B
, logs all facilities, and stores
the log entries in
/var/log/logclient.log
.
When adding multiple log clients, add a similar two-line entry for each client. More information about the available facilities may be found in syslog.conf(5).
Next, configure
/etc/rc.conf
:
syslogd_enable="YES" syslogd_flags="-a logclient.example.com -v -v"
The first entry starts
syslogd at system boot. The
second entry allows log entries from the specified client.
The -v -v
increases the verbosity of logged
messages. This is useful for tweaking facilities as
administrators are able to see what type of messages are
being logged under each facility.
Multiple -a
options may be specified to
allow logging from multiple clients. IP
addresses and whole netblocks may also be specified. Refer
to syslogd(8) for a full list of possible
options.
Finally, create the log file:
#
touch /var/log/logclient.log
At this point, syslogd should be restarted and verified:
#
service syslogd restart
#
pgrep syslog
If a PID is returned, the server
restarted successfully, and client configuration can begin.
If the server did not restart, consult
/var/log/messages
for the error.
A logging client sends log entries to a logging server on the network. The client also keeps a local copy of its own logs.
Once a logging server has been configured, edit
/etc/rc.conf
on the logging
client:
syslogd_enable="YES" syslogd_flags="-s -v -v"
The first entry enables
syslogd on boot up. The second
entry prevents logs from being accepted by this client from
other hosts (-s
) and increases the
verbosity of logged messages.
Next, define the logging server in the client's
/etc/syslog.conf
. In this example, all
logged facilities are sent to a remote system, denoted by
the @
symbol, with the specified
hostname:
*.* @logserv.example.com
After saving the edit, restart syslogd for the changes to take effect:
#
service syslogd restart
To test that log messages are being sent across the network, use logger(1) on the client to send a message to syslogd:
#
logger "
Test message from logclient
"
This message should now exist both in
/var/log/messages
on the client and
/var/log/logclient.log
on the log
server.
If no messages are being received on the log server, the
cause is most likely a network connectivity issue, a
hostname resolution issue, or a typo in a configuration
file. To isolate the cause, ensure that both the logging
server and the logging client are able to
ping
each other using the hostname
specified in their /etc/rc.conf
. If
this fails, check the network cabling, the firewall ruleset,
and the hostname entries in the DNS
server or /etc/hosts
on both the
logging server and clients. Repeat until the
ping
is successful from both
hosts.
If the ping
succeeds on both hosts
but log messages are still not being received, temporarily
increase logging verbosity to narrow down the configuration
issue. In the following example,
/var/log/logclient.log
on the logging
server is empty and /var/log/messages
on the logging client does not indicate a reason for the
failure. To increase debugging output, edit the
syslogd_flags
entry on the logging server
and issue a restart:
syslogd_flags="-d -a logclient.example.com -v -v"
#
service syslogd restart
Debugging data similar to the following will flash on the console immediately after the restart:
logmsg: pri 56, flags 4, from logserv.example.com, msg syslogd: restart syslogd: restarted logmsg: pri 6, flags 4, from logserv.example.com, msg syslogd: kernel boot file is /boot/kernel/kernel Logging to FILE /var/log/messages syslogd: kernel boot file is /boot/kernel/kernel cvthname(192.168.1.10) validate: dgram from IP 192.168.1.10, port 514, name logclient.example.com; rejected in rule 0 due to name mismatch.
In this example, the log messages are being rejected due
to a typo which results in a hostname mismatch. The
client's hostname should be logclient
,
not logclien
. Fix the typo, issue a
restart, and verify the results:
#
service syslogd restart
logmsg: pri 56, flags 4, from logserv.example.com, msg syslogd: restart syslogd: restarted logmsg: pri 6, flags 4, from logserv.example.com, msg syslogd: kernel boot file is /boot/kernel/kernel syslogd: kernel boot file is /boot/kernel/kernel logmsg: pri 166, flags 17, from logserv.example.com, msg Dec 10 20:55:02 <syslog.err> logserv.example.com syslogd: exiting on signal 2 cvthname(192.168.1.10) validate: dgram from IP 192.168.1.10, port 514, name logclient.example.com; accepted in rule 0. logmsg: pri 15, flags 0, from logclient.example.com, msg Dec 11 02:01:28 trhodes: Test message 2 Logging to FILE /var/log/logclient.log Logging to FILE /var/log/messages
At this point, the messages are being properly received and placed in the correct file.
As with any network service, security requirements should be considered before implementing a logging server. Log files may contain sensitive data about services enabled on the local host, user accounts, and configuration data. Network data sent from the client to the server will not be encrypted or password protected. If a need for encryption exists, consider using security/stunnel, which will transmit the logging data over an encrypted tunnel.
Local security is also an issue. Log files are not
encrypted during use or after log rotation. Local users may
access log files to gain additional insight into system
configuration. Setting proper permissions on log files is
critical. The built-in log rotator,
newsyslog, supports setting
permissions on newly created and rotated log files. Setting
log files to mode 600
should prevent
unwanted access by local users. Refer to
newsyslog.conf(5) for additional information.
There are a number of directories in which configuration information is kept. These include:
/etc | Generic system-specific configuration information. |
/etc/defaults | Default versions of system configuration files. |
/etc/mail | Extra sendmail(8) configuration and other MTA configuration files. |
/etc/ppp | Configuration for both user- and kernel-ppp programs. |
/usr/local/etc | Configuration files for installed applications. May contain per-application subdirectories. |
/usr/local/etc/rc.d | rc(8) scripts for installed applications. |
/var/db | Automatically generated system-specific database files, such as the package database and the locate(1) database. |
How a FreeBSD system accesses the Internet Domain Name System (DNS) is controlled by resolv.conf(5).
The most common entries to
/etc/resolv.conf
are:
nameserver | The IP address of a name server the resolver should query. The servers are queried in the order listed with a maximum of three. |
search | Search list for hostname lookup. This is normally determined by the domain of the local hostname. |
domain | The local domain name. |
A typical /etc/resolv.conf
looks
like this:
search example.com nameserver 147.11.1.11 nameserver 147.11.100.30
Only one of the search
and
domain
options should be used.
When using DHCP, dhclient(8)
usually rewrites /etc/resolv.conf
with information received from the DHCP
server.
/etc/hosts
is a simple text
database which works in conjunction with
DNS and
NIS to provide host name to
IP address mappings. Entries for local
computers connected via a LAN can be
added to this file for simplistic naming purposes instead
of setting up a named(8) server. Additionally,
/etc/hosts
can be used to provide a
local record of Internet names, reducing the need to query
external DNS servers for commonly
accessed names.
# $FreeBSD$
#
#
# Host Database
#
# This file should contain the addresses and aliases for local hosts that
# share this file. Replace 'my.domain' below with the domainname of your
# machine.
#
# In the presence of the domain name service or NIS, this file may
# not be consulted at all; see /etc/nsswitch.conf for the resolution order.
#
#
::1 localhost localhost.my.domain
127.0.0.1 localhost localhost.my.domain
#
# Imaginary network.
#10.0.0.2 myname.my.domain myname
#10.0.0.3 myfriend.my.domain myfriend
#
# According to RFC 1918, you can use the following IP networks for
# private nets which will never be connected to the Internet:
#
# 10.0.0.0 - 10.255.255.255
# 172.16.0.0 - 172.31.255.255
# 192.168.0.0 - 192.168.255.255
#
# In case you want to be able to connect to the Internet, you need
# real official assigned numbers. Do not try to invent your own network
# numbers but instead get one from your network provider (if any) or
# from your regional registry (ARIN, APNIC, LACNIC, RIPE NCC, or AfriNIC.)
#
The format of /etc/hosts
is as
follows:
[Internet address] [official hostname] [alias1] [alias2] ...
For example:
10.0.0.1 myRealHostname.example.com myRealHostname foobar1 foobar2
Consult hosts(5) for more information.
sysctl(8) is used to make changes to a running FreeBSD system. This includes many advanced options of the TCP/IP stack and virtual memory system that can dramatically improve performance for an experienced system administrator. Over five hundred system variables can be read and set using sysctl(8).
At its core, sysctl(8) serves two functions: to read and to modify system settings.
To view all readable variables:
%
sysctl -a
To read a particular variable, specify its name:
%
sysctl kern.maxproc
kern.maxproc: 1044
To set a particular variable, use the
variable
=value
syntax:
#
sysctl kern.maxfiles=5000
kern.maxfiles: 2088 -> 5000
Settings of sysctl variables are usually either strings,
numbers, or booleans, where a boolean is 1
for yes or 0
for no.
To automatically set some variables each time the machine
boots, add them to /etc/sysctl.conf
. For
more information, refer to sysctl.conf(5) and
Section 11.9.1, “sysctl.conf
”.
The configuration file for sysctl(8),
/etc/sysctl.conf
, looks much like
/etc/rc.conf
. Values are set in a
variable=value
form. The specified values
are set after the system goes into multi-user mode. Not all
variables are settable in this mode.
For example, to turn off logging of fatal signal exits
and prevent users from seeing processes started by other
users, the following tunables can be set in
/etc/sysctl.conf
:
# Do not log fatal signal exits (e.g., sig 11) kern.logsigexit=0 # Prevent users from seeing information about processes that # are being run under another UID. security.bsd.see_other_uids=0
In some cases it may be desirable to modify read-only sysctl(8) values, which will require a reboot of the system.
For instance, on some laptop models the cardbus(4) device will not probe memory ranges and will fail with errors similar to:
cbb0: Could not map register memory device_probe_and_attach: cbb0 attach returned 12
The fix requires the modification of a read-only
sysctl(8) setting. Add
hw.pci.allow_unsupported_io_range=1
to
/boot/loader.conf
and reboot. Now
cardbus(4) should work properly.
The following section will discuss various tuning mechanisms and options which may be applied to disk devices. In many cases, disks with mechanical parts, such as SCSI drives, will be the bottleneck driving down the overall system performance. While a solution is to install a drive without mechanical parts, such as a solid state drive, mechanical drives are not going away anytime in the near future. When tuning disks, it is advisable to utilize the features of the iostat(8) command to test various changes to the system. This command will allow the user to obtain valuable information on system IO.
The vfs.vmiodirenable
sysctl(8)
variable
may be set to either 0
(off) or
1
(on). It is set to
1
by default. This variable controls
how directories are cached by the system. Most directories
are small, using just a single fragment (typically 1 K)
in the file system and typically 512 bytes in the
buffer cache. With this variable turned off, the buffer
cache will only cache a fixed number of directories, even
if the system has a huge amount of memory. When turned on,
this sysctl(8) allows the buffer cache to use the
VM page cache to cache the directories,
making all the memory available for caching directories.
However, the minimum in-core memory used to cache a
directory is the physical page size (typically 4 K)
rather than 512 bytes. Keeping this option enabled
is recommended if the system is running any services which
manipulate large numbers of files. Such services can
include web caches, large mail systems, and news systems.
Keeping this option on will generally not reduce
performance, even with the wasted memory, but one should
experiment to find out.
The vfs.write_behind
sysctl(8)
variable
defaults to 1
(on). This tells the file
system to issue media writes as full clusters are collected,
which typically occurs when writing large sequential files.
This avoids saturating the buffer cache with dirty buffers
when it would not benefit I/O performance. However, this
may stall processes and under certain circumstances should
be turned off.
The vfs.hirunningspace
sysctl(8)
variable determines how much outstanding write I/O may be
queued to disk controllers system-wide at any given
instance. The default is usually sufficient, but on
machines with many disks, try bumping it up to four or five
megabytes. Setting too high a value
which exceeds the buffer cache's write threshold can lead
to bad clustering performance. Do not set this value
arbitrarily high as higher write values may add latency to
reads occurring at the same time.
There are various other buffer cache and VM page cache related sysctl(8) values. Modifying these values is not recommended as the VM system does a good job of automatically tuning itself.
The vm.swap_idle_enabled
sysctl(8) variable is useful in large multi-user
systems with many active login users and lots of idle
processes. Such systems tend to generate continuous
pressure on free memory reserves. Turning this feature on
and tweaking the swapout hysteresis (in idle seconds) via
vm.swap_idle_threshold1
and
vm.swap_idle_threshold2
depresses the
priority of memory pages associated with idle processes more
quickly then the normal pageout algorithm. This gives a
helping hand to the pageout daemon. Only turn this option
on if needed, because the tradeoff is essentially pre-page
memory sooner rather than later which eats more swap and
disk bandwidth. In a small system this option will have a
determinable effect, but in a large system that is already
doing moderate paging, this option allows the
VM system to stage whole processes into
and out of memory easily.
Turning off IDE write caching reduces
write bandwidth to IDE disks, but may
sometimes be necessary due to data consistency issues
introduced by hard drive vendors. The problem is that
some IDE drives lie about when a write
completes. With IDE write caching
turned on, IDE hard drives write data
to disk out of order and will sometimes delay writing some
blocks indefinitely when under heavy disk load. A crash or
power failure may cause serious file system corruption.
Check the default on the system by observing the
hw.ata.wc
sysctl(8) variable. If
IDE write caching is turned off, one can
set this read-only variable to
1
in
/boot/loader.conf
in order to enable
it at boot time.
For more information, refer to ata(4).
The SCSI_DELAY
kernel configuration
option may be used to reduce system boot times. The
defaults are fairly high and can be responsible for
15
seconds of delay in the boot process.
Reducing it to 5
seconds usually works
with modern drives. The
kern.cam.scsi_delay
boot time tunable
should be used. The tunable and kernel configuration
option accept values in terms of
milliseconds and
not
seconds.
To fine-tune a file system, use tunefs(8). This program has many different options. To toggle Soft Updates on and off, use:
#
tunefs -n enable /filesystem
#
tunefs -n disable /filesystem
A file system cannot be modified with tunefs(8) while it is mounted. A good time to enable Soft Updates is before any partitions have been mounted, in single-user mode.
Soft Updates is recommended for UFS
file systems as it drastically improves meta-data performance,
mainly file creation and deletion, through the use of a memory
cache. There are two downsides to Soft Updates to be aware
of. First, Soft Updates guarantee file system consistency
in the case of a crash, but could easily be several seconds
or even a minute behind updating the physical disk. If the
system crashes, unwritten data may be lost. Secondly, Soft
Updates delay the freeing of file system blocks. If the
root file system is almost full, performing a major update,
such as make installworld
, can cause the
file system to run out of space and the update to fail.
Meta-data updates are updates to non-content data like inodes or directories. There are two traditional approaches to writing a file system's meta-data back to disk.
Historically, the default behavior was to write out
meta-data updates synchronously. If a directory changed,
the system waited until the change was actually written to
disk. The file data buffers (file contents) were passed
through the buffer cache and backed up to disk later on
asynchronously. The advantage of this implementation is
that it operates safely. If there is a failure during an
update, meta-data is always in a consistent state. A
file is either created completely or not at all. If the
data blocks of a file did not find their way out of the
buffer cache onto the disk by the time of the crash,
fsck(8) recognizes this and repairs the file system
by setting the file length to 0
.
Additionally, the implementation is clear and simple. The
disadvantage is that meta-data changes are slow. For
example, rm -r
touches all the files in a
directory sequentially, but each directory change will be
written synchronously to the disk. This includes updates to
the directory itself, to the inode table, and possibly to
indirect blocks allocated by the file. Similar
considerations apply for unrolling large hierarchies using
tar -x
.
The second approach is to use asynchronous meta-data
updates. This is the default for a UFS
file system mounted with mount -o async
.
Since all meta-data updates are also passed through the
buffer cache, they will be intermixed with the updates of
the file content data. The advantage of this
implementation is there is no need to wait until each
meta-data update has been written to disk, so all operations
which cause huge amounts of meta-data updates work much
faster than in the synchronous case. This implementation
is still clear and simple, so there is a low risk for bugs
creeping into the code. The disadvantage is that there is
no guarantee for a consistent state of the file system.
If there is a failure during an operation that updated
large amounts of meta-data, like a power failure or someone
pressing the reset button, the file system will be left
in an unpredictable state. There is no opportunity to
examine the state of the file system when the system comes
up again as the data blocks of a file could already have
been written to the disk while the updates of the inode
table or the associated directory were not. It is
impossible to implement a fsck(8) which is able to
clean up the resulting chaos because the necessary
information is not available on the disk. If the file
system has been damaged beyond repair, the only choice
is to reformat it and restore from backup.
The usual solution for this problem is to implement dirty region logging, which is also referred to as journaling. Meta-data updates are still written synchronously, but only into a small region of the disk. Later on, they are moved to their proper location. Because the logging area is a small, contiguous region on the disk, there are no long distances for the disk heads to move, even during heavy operations, so these operations are quicker than synchronous updates. Additionally, the complexity of the implementation is limited, so the risk of bugs being present is low. A disadvantage is that all meta-data is written twice, once into the logging region and once to the proper location, so performance “pessimization” might result. On the other hand, in case of a crash, all pending meta-data operations can be either quickly rolled back or completed from the logging area after the system comes up again, resulting in a fast file system startup.
Kirk McKusick, the developer of Berkeley
FFS, solved this problem with Soft
Updates. All pending meta-data updates are kept in memory
and written out to disk in a sorted sequence
(“ordered meta-data updates”). This has the
effect that, in case of heavy meta-data operations, later
updates to an item “catch” the earlier ones
which are still in memory and have not already been written
to disk. All operations are generally performed in memory
before the update is written to disk and the data blocks are
sorted according to their position so that they will not be
on the disk ahead of their meta-data. If the system
crashes, an implicit “log rewind” causes all
operations which were not written to the disk appear as if
they never happened. A consistent file system state is
maintained that appears to be the one of 30 to 60 seconds
earlier. The algorithm used guarantees that all resources
in use are marked as such in their blocks and inodes.
After a crash, the only resource allocation error that
occurs is that resources are marked as “used”
which are actually “free”. fsck(8)
recognizes this situation, and frees the resources that
are no longer used. It is safe to ignore the dirty state
of the file system after a crash by forcibly mounting it
with mount -f
. In order to free
resources that may be unused, fsck(8) needs to be run
at a later time. This is the idea behind the
background fsck(8): at system
startup time, only a snapshot of the
file system is recorded and fsck(8) is run afterwards.
All file systems can then be mounted
“dirty”, so the system startup proceeds in
multi-user mode. Then, background fsck(8) is
scheduled for all file systems where this is required, to
free resources that may be unused. File systems that do
not use Soft Updates still need the usual foreground
fsck(8).
The advantage is that meta-data operations are nearly as fast as asynchronous updates and are faster than logging, which has to write the meta-data twice. The disadvantages are the complexity of the code, a higher memory consumption, and some idiosyncrasies. After a crash, the state of the file system appears to be somewhat “older”. In situations where the standard synchronous approach would have caused some zero-length files to remain after the fsck(8), these files do not exist at all with Soft Updates because neither the meta-data nor the file contents have been written to disk. Disk space is not released until the updates have been written to disk, which may take place some time after running rm(1). This may cause problems when installing large amounts of data on a file system that does not have enough free space to hold all the files twice.
The kern.maxfiles
sysctl(8)
variable can be raised or lowered based upon system
requirements. This variable indicates the maximum number
of file descriptors on the system. When the file descriptor
table is full, file: table is full
will show up repeatedly in the system message buffer, which
can be viewed using dmesg(8).
Each open file, socket, or fifo uses one file descriptor. A large-scale production server may easily require many thousands of file descriptors, depending on the kind and number of services running concurrently.
In older FreeBSD releases, the default value of
kern.maxfiles
is derived from
maxusers
in the kernel configuration file.
kern.maxfiles
grows proportionally to the
value of maxusers
. When compiling a custom
kernel, consider setting this kernel configuration option
according to the use of the system. From this number, the
kernel is given most of its pre-defined limits. Even though
a production machine may not have 256 concurrent users, the
resources needed may be similar to a high-scale web
server.
The read-only sysctl(8) variable
kern.maxusers
is automatically sized at
boot based on the amount of memory available in the system,
and may be determined at run-time by inspecting the value
of kern.maxusers
. Some systems require
larger or smaller values of
kern.maxusers
and values of
64
, 128
, and
256
are not uncommon. Going above
256
is not recommended unless a huge
number of file descriptors is needed. Many of the tunable
values set to their defaults by
kern.maxusers
may be individually
overridden at boot-time or run-time in
/boot/loader.conf
. Refer to
loader.conf(5) and
/boot/defaults/loader.conf
for more
details and some hints.
In older releases, the system will auto-tune
maxusers
if it is set to
0
.
[2]. When
setting this option, set maxusers
to
at least 4
, especially if the system
runs Xorg or is used to
compile software. The most important table set by
maxusers
is the maximum number of
processes, which is set to
20 + 16 * maxusers
. If
maxusers
is set to 1
,
there can only be
36
simultaneous processes, including
the 18
or so that the system starts up
at boot time and the 15
or so used by
Xorg. Even a simple task like
reading a manual page will start up nine processes to
filter, decompress, and view it. Setting
maxusers
to 64
allows
up to 1044
simultaneous processes, which
should be enough for nearly all uses. If, however, the
proc table full error is displayed
when trying to start another program, or a server is
running with a large number of simultaneous users, increase
the number and rebuild.
maxusers
does
not limit the number of users which
can log into the machine. It instead sets various table
sizes to reasonable values considering the maximum number
of users on the system and how many processes each user
will be running.
The kern.ipc.soacceptqueue
sysctl(8) variable limits the size of the listen queue
for accepting new TCP
connections. The
default value of 128
is typically too low
for robust handling of new connections on a heavily loaded
web server. For such environments, it is recommended to
increase this value to 1024
or higher. A
service such as sendmail(8), or
Apache may itself limit the
listen queue size, but will often have a directive in its
configuration file to adjust the queue size. Large listen
queues do a better job of avoiding Denial of Service
(DoS) attacks.
The NMBCLUSTERS
kernel configuration
option dictates the amount of network Mbufs available to the
system. A heavily-trafficked server with a low number of
Mbufs will hinder performance. Each cluster represents
approximately 2 K of memory, so a value of
1024
represents 2
megabytes of kernel memory reserved for network buffers. A
simple calculation can be done to figure out how many are
needed. A web server which maxes out at
1000
simultaneous connections where each
connection uses a 6 K receive and 16 K send buffer,
requires approximately 32 MB worth of network buffers
to cover the web server. A good rule of thumb is to multiply
by 2
, so
2x32 MB / 2 KB =
64 MB / 2 kB =
32768
. Values between
4096
and 32768
are
recommended for machines with greater amounts of memory.
Never specify an arbitrarily high value for this parameter
as it could lead to a boot time crash. To observe network
cluster usage, use -m
with
netstat(1).
The kern.ipc.nmbclusters
loader tunable
should be used to tune this at boot time. Only older versions
of FreeBSD will require the use of the
NMBCLUSTERS
kernel config(8)
option.
For busy servers that make extensive use of the
sendfile(2) system call, it may be necessary to increase
the number of sendfile(2) buffers via the
NSFBUFS
kernel configuration option or by
setting its value in /boot/loader.conf
(see loader(8) for details). A common indicator that
this parameter needs to be adjusted is when processes are seen
in the sfbufa
state. The sysctl(8)
variable kern.ipc.nsfbufs
is read-only.
This parameter nominally scales with
kern.maxusers
, however it may be necessary
to tune accordingly.
Even though a socket has been marked as non-blocking,
calling sendfile(2) on the non-blocking socket may
result in the sendfile(2) call blocking until enough
struct sf_buf
's are made
available.
The net.inet.ip.portrange.*
sysctl(8) variables control the port number ranges
automatically bound to TCP
and
UDP
sockets. There are three ranges: a
low range, a default range, and a high range. Most network
programs use the default range which is controlled by
net.inet.ip.portrange.first
and
net.inet.ip.portrange.last
, which default
to 1024
and 5000
,
respectively. Bound port ranges are used for outgoing
connections and it is possible to run the system out of
ports under certain circumstances. This most commonly
occurs when running a heavily loaded web proxy. The port
range is not an issue when running a server which handles
mainly incoming connections, such as a web server, or has
a limited number of outgoing connections, such as a mail
relay. For situations where there is a shortage of ports,
it is recommended to increase
net.inet.ip.portrange.last
modestly. A
value of 10000
, 20000
or 30000
may be reasonable. Consider
firewall effects when changing the port range. Some
firewalls may block large ranges of ports, usually
low-numbered ports, and expect systems to use higher ranges
of ports for outgoing connections. For this reason, it
is not recommended that the value of
net.inet.ip.portrange.first
be
lowered.
TCP
bandwidth delay product limiting
can be enabled by setting the
net.inet.tcp.inflight.enable
sysctl(8) variable to 1
. This
instructs the system to attempt to calculate the bandwidth
delay product for each connection and limit the amount of
data queued to the network to just the amount required to
maintain optimum throughput.
This feature is useful when serving data over modems,
Gigabit Ethernet, high speed WAN
links,
or any other link with a high bandwidth delay product,
especially when also using window scaling or when a large
send window has been configured. When enabling this option,
also set net.inet.tcp.inflight.debug
to
0
to disable debugging. For production
use, setting net.inet.tcp.inflight.min
to at least 6144
may be beneficial.
Setting high minimums may effectively disable bandwidth
limiting, depending on the link. The limiting feature
reduces the amount of data built up in intermediate route
and switch packet queues and reduces the amount of data
built up in the local host's interface queue. With fewer
queued packets, interactive connections, especially over
slow modems, will operate with lower
Round Trip Times. This feature only
effects server side data transmission such as uploading.
It has no effect on data reception or downloading.
Adjusting net.inet.tcp.inflight.stab
is not recommended. This parameter
defaults to 20
, representing 2 maximal
packets added to the bandwidth delay product window
calculation. The additional window is required to stabilize
the algorithm and improve responsiveness to changing
conditions, but it can also result in higher ping(8)
times over slow links, though still much lower than without
the inflight algorithm. In such cases, try reducing this
parameter to 15
, 10
,
or 5
and reducing
net.inet.tcp.inflight.min
to a value such
as 3500
to get the desired effect.
Reducing these parameters should be done as a last resort
only.
A vnode is the internal representation of a file or directory. Increasing the number of vnodes available to the operating system reduces disk I/O. Normally, this is handled by the operating system and does not need to be changed. In some cases where disk I/O is a bottleneck and the system is running out of vnodes, this setting needs to be increased. The amount of inactive and free RAM will need to be taken into account.
To see the current number of vnodes in use:
#
sysctl vfs.numvnodes
vfs.numvnodes: 91349
To see the maximum vnodes:
#
sysctl kern.maxvnodes
kern.maxvnodes: 100000
If the current vnode usage is near the maximum, try
increasing kern.maxvnodes
by a value of
1000
. Keep an eye on the number of
vfs.numvnodes
. If it climbs up to the
maximum again, kern.maxvnodes
will need
to be increased further. Otherwise, a shift in memory
usage as reported by top(1) should be visible and
more memory should be active.
Sometimes a system requires more swap space. This section describes two methods to increase swap space: adding swap to an existing partition or new hard drive, and creating a swap file on an existing partition.
For information on how to encrypt swap space, which options exist, and why it should be done, refer to Section 17.13, “Encrypting Swap”.
Adding a new hard drive for swap gives better performance than using a partition on an existing drive. Setting up partitions and hard drives is explained in Section 17.2, “Adding Disks” while Section 2.6.1, “Designing the Partition Layout” discusses partition layouts and swap partition size considerations.
Use swapon
to add a swap partition to
the system. For example:
#
swapon
/dev/ada1s1b
It is possible to use any partition not currently
mounted, even if it already contains data. Using
swapon
on a partition that contains data
will overwrite and destroy that data. Make sure that the
partition to be added as swap is really the intended
partition before running swapon
.
To automatically add this swap partition on boot, add an
entry to /etc/fstab
:
/dev/ada1s1b
none swap sw 0 0
See fstab(5) for an explanation of the entries in
/etc/fstab
. More information about
swapon
can be found in
swapon(8).
These examples create a 64M swap file called
/usr/swap0
instead of using a
partition.
Using swap files requires that the module needed by md(4) has either been built into the kernel or has been loaded before swap is enabled. See Chapter 8, Configuring the FreeBSD Kernel for information about building a custom kernel.
X
and LaterCreate the swap file:
#
dd if=/dev/zero of=
/usr/swap0
bs=1m count=64
Set the proper permissions on the new file:
#
chmod 0600
/usr/swap0
Inform the system about the swap file by adding a
line to /etc/fstab
:
md99 none swap sw,file=/usr/swap0,late 0 0
The md(4) device md99
is
used, leaving lower device numbers available for
interactive use.
Swap space will be added on system startup. To add swap space immediately, use swapon(8):
#
swapon -aL
X
and EarlierCreate the swap file,
/usr/swap0
:
#
dd if=/dev/zero of=
/usr/swap0
bs=1m count=64
Set the proper permissions on
/usr/swap0
:
#
chmod 0600
/usr/swap0
Enable the swap file in
/etc/rc.conf
:
swapfile="/usr/swap0
" # Set to name of swap file
Swap space will be added on system startup. To enable the swap file immediately, specify a free memory device. Refer to Section 17.9, “Memory Disks” for more information about memory devices.
#
mdconfig -a -t vnode -f
/usr/swap0
-u0
&& swapon /dev/md0
It is important to utilize hardware resources in an efficient manner. Power and resource management allows the operating system to monitor system limits and to possibly provide an alert if the system temperature increases unexpectedly. An early specification for providing power management was the Advanced Power Management (APM) facility. APM controls the power usage of a system based on its activity. However, it was difficult and inflexible for operating systems to manage the power usage and thermal properties of a system. The hardware was managed by the BIOS and the user had limited configurability and visibility into the power management settings. The APM BIOS is supplied by the vendor and is specific to the hardware platform. An APM driver in the operating system mediates access to the APM Software Interface, which allows management of power levels.
There are four major problems in APM. First, power management is done by the vendor-specific BIOS, separate from the operating system. For example, the user can set idle-time values for a hard drive in the APM BIOS so that, when exceeded, the BIOS spins down the hard drive without the consent of the operating system. Second, the APM logic is embedded in the BIOS, and it operates outside the scope of the operating system. This means that users can only fix problems in the APM BIOS by flashing a new one into the ROM, which is a dangerous procedure with the potential to leave the system in an unrecoverable state if it fails. Third, APM is a vendor-specific technology, meaning that there is a lot of duplication of efforts and bugs found in one vendor's BIOS may not be solved in others. Lastly, the APM BIOS did not have enough room to implement a sophisticated power policy or one that can adapt well to the purpose of the machine.
The Plug and Play BIOS (PNPBIOS) was unreliable in many situations. PNPBIOS is 16-bit technology, so the operating system has to use 16-bit emulation in order to interface with PNPBIOS methods. FreeBSD provides an APM driver as APM should still be used for systems manufactured at or before the year 2000. The driver is documented in apm(4).
The successor to APM is the Advanced Configuration and Power Interface (ACPI). ACPI is a standard written by an alliance of vendors to provide an interface for hardware resources and power management. It is a key element in Operating System-directed configuration and Power Management as it provides more control and flexibility to the operating system.
This chapter demonstrates how to configure ACPI on FreeBSD. It then offers some tips on how to debug ACPI and how to submit a problem report containing debugging information so that developers can diagnosis and fix ACPI issues.
In FreeBSD the acpi(4) driver is loaded by default at
system boot and should not be compiled
into the kernel. This driver cannot be unloaded after boot
because the system bus uses it for various hardware
interactions. However, if the system is experiencing
problems, ACPI can be disabled altogether
by rebooting after setting
hint.acpi.0.disabled="1"
in
/boot/loader.conf
or by setting this
variable at the loader prompt, as described in Section 12.2.3, “Stage Three”.
ACPI and APM cannot coexist and should be used separately. The last one to load will terminate if the driver notices the other is running.
ACPI can be used to put the system into
a sleep mode with acpiconf
, the
-s
flag, and a number from
1
to 5
. Most users only
need 1
(quick suspend to
RAM) or 3
(suspend to
RAM). Option 5
performs
a soft-off which is the same as running
halt -p
.
Other options are available using
sysctl
. Refer to acpi(4) and
acpiconf(8) for more information.
ACPI is present in all modern computers that conform to the ia32 (x86), ia64 (Itanium), and amd64 (AMD) architectures. The full standard has many features including CPU performance management, power planes control, thermal zones, various battery systems, embedded controllers, and bus enumeration. Most systems implement less than the full standard. For instance, a desktop system usually only implements bus enumeration while a laptop might have cooling and battery management support as well. Laptops also have suspend and resume, with their own associated complexity.
An ACPI-compliant system has various components. The BIOS and chipset vendors provide various fixed tables, such as FADT, in memory that specify things like the APIC map (used for SMP), config registers, and simple configuration values. Additionally, a bytecode table, the Differentiated System Description Table DSDT, specifies a tree-like name space of devices and methods.
The ACPI driver must parse the fixed
tables, implement an interpreter for the bytecode, and modify
device drivers and the kernel to accept information from the
ACPI subsystem. For FreeBSD, Intel® has
provided an interpreter (ACPI-CA) that is
shared with Linux® and NetBSD. The path to the
ACPI-CA source code is
src/sys/contrib/dev/acpica
. The glue
code that allows ACPI-CA to work on FreeBSD is
in src/sys/dev/acpica/Osd
. Finally,
drivers that implement various ACPI devices
are found in src/sys/dev/acpica
.
For ACPI to work correctly, all the parts have to work correctly. Here are some common problems, in order of frequency of appearance, and some possible workarounds or fixes. If a fix does not resolve the issue, refer to Section 11.13.4, “Getting and Submitting Debugging Info” for instructions on how to submit a bug report.
In some cases, resuming from a suspend operation will
cause the mouse to fail. A known work around is to add
hint.psm.0.flags="0x3000"
to
/boot/loader.conf
.
ACPI has three suspend to
RAM (STR) states,
S1
-S3
, and one suspend
to disk state (STD), called
S4
. STD can be
implemented in two separate ways. The
S4
BIOS is a
BIOS-assisted suspend to disk and
S4
OS is implemented
entirely by the operating system. The normal state the
system is in when plugged in but not powered up is
“soft off” (S5
).
Use sysctl hw.acpi
to check for the
suspend-related items. These example results are from a
Thinkpad:
hw.acpi.supported_sleep_state: S3 S4 S5 hw.acpi.s4bios: 0
Use acpiconf -s
to test
S3
, S4
, and
S5
. An s4bios
of one
(1
) indicates
S4
BIOS support instead
of S4
operating system support.
When testing suspend/resume, start with
S1
, if supported. This state is most
likely to work since it does not require much driver
support. No one has implemented S2
,
which is similar to S1
. Next, try
S3
. This is the deepest
STR state and requires a lot of driver
support to properly reinitialize the hardware.
A common problem with suspend/resume is that many device drivers do not save, restore, or reinitialize their firmware, registers, or device memory properly. As a first attempt at debugging the problem, try:
#
sysctl debug.bootverbose=1
#
sysctl debug.acpi.suspend_bounce=1
#
acpiconf -s 3
This test emulates the suspend/resume cycle of all
device drivers without actually going into
S3
state. In some cases, problems such
as losing firmware state, device watchdog time out, and
retrying forever, can be captured with this method. Note
that the system will not really enter S3
state, which means devices may not lose power, and many
will work fine even if suspend/resume methods are totally
missing, unlike real S3
state.
Harder cases require additional hardware, such as a serial port and cable for debugging through a serial console, a Firewire port and cable for using dcons(4), and kernel debugging skills.
To help isolate the problem, unload as many drivers as
possible. If it works, narrow down which driver is the
problem by loading drivers until it fails again. Typically,
binary drivers like nvidia.ko
, display
drivers, and USB will have the most
problems while Ethernet interfaces usually work fine. If
drivers can be properly loaded and unloaded, automate this
by putting the appropriate commands in
/etc/rc.suspend
and
/etc/rc.resume
. Try setting
hw.acpi.reset_video
to 1
if the display is messed up after resume. Try setting
longer or shorter values for
hw.acpi.sleep_delay
to see if that
helps.
Try loading a recent Linux® distribution to see if suspend/resume works on the same hardware. If it works on Linux®, it is likely a FreeBSD driver problem. Narrowing down which driver causes the problem will assist developers in fixing the problem. Since the ACPI maintainers rarely maintain other drivers, such as sound or ATA, any driver problems should also be posted to the freebsd-current list and mailed to the driver maintainer. Advanced users can include debugging printf(3)s in a problematic driver to track down where in its resume function it hangs.
Finally, try disabling ACPI and enabling APM instead. If suspend/resume works with APM, stick with APM, especially on older hardware (pre-2000). It took vendors a while to get ACPI support correct and older hardware is more likely to have BIOS problems with ACPI.
Most system hangs are a result of lost interrupts or an interrupt storm. Chipsets may have problems based on boot, how the BIOS configures interrupts before correctness of the APIC (MADT) table, and routing of the System Control Interrupt (SCI).
Interrupt storms can be distinguished from lost
interrupts by checking the output of
vmstat -i
and looking at the line that
has acpi0
. If the counter is increasing
at more than a couple per second, there is an interrupt
storm. If the system appears hung, try breaking to
DDB (CTRL+ALT+ESC on console) and type
show interrupts
.
When dealing with interrupt problems, try disabling
APIC support with
hint.apic.0.disabled="1"
in
/boot/loader.conf
.
Panics are relatively rare for ACPI
and are the top priority to be fixed. The first step is to
isolate the steps to reproduce the panic, if possible, and
get a backtrace. Follow the advice for enabling
options DDB
and setting up a serial
console in Section 26.6.4, “Entering the DDB Debugger from the Serial Line” or setting
up a dump partition. To get a backtrace in
DDB, use tr
. When
handwriting the backtrace, get at least the last five and
the top five lines in the trace.
Then, try to isolate the problem by booting with
ACPI disabled. If that works, isolate
the ACPI subsystem by using various
values of debug.acpi.disable
. See
acpi(4) for some examples.
First, try setting
hw.acpi.disable_on_poweroff="0"
in
/boot/loader.conf
. This keeps
ACPI from disabling various events during
the shutdown process. Some systems need this value set to
1
(the default) for the same reason.
This usually fixes the problem of a system powering up
spontaneously after a suspend or poweroff.
Some BIOS vendors provide incorrect or buggy bytecode. This is usually manifested by kernel console messages like this:
ACPI-1287: *** Error: Method execution failed [\\_SB_.PCI0.LPC0.FIGD._STA] \\ (Node 0xc3f6d160), AE_NOT_FOUND
Often, these problems may be resolved by updating the BIOS to the latest revision. Most console messages are harmless, but if there are other problems, like the battery status is not working, these messages are a good place to start looking for problems.
The BIOS bytecode, known as ACPI Machine Language (AML), is compiled from a source language called ACPI Source Language (ASL). The AML is found in the table known as the Differentiated System Description Table (DSDT).
The goal of FreeBSD is for everyone to have working
ACPI without any user intervention.
Workarounds are still being developed for common mistakes made
by BIOS vendors. The Microsoft®
interpreter (acpi.sys
and
acpiec.sys
) does not strictly check for
adherence to the standard, and thus many
BIOS vendors who only test
ACPI under Windows® never fix their
ASL. FreeBSD developers continue to identify
and document which non-standard behavior is allowed by
Microsoft®'s interpreter and replicate it so that FreeBSD can
work without forcing users to fix the
ASL.
To help identify buggy behavior and possibly fix it
manually, a copy can be made of the system's
ASL. To copy the system's
ASL to a specified file name, use
acpidump
with -t
, to show
the contents of the fixed tables, and -d
, to
disassemble the AML:
#
acpidump -td >
my.asl
Some AML versions assume the user is
running Windows®. To override this, set
hw.acpi.osname=
in
"Windows
2009"
/boot/loader.conf
, using the most recent
Windows® version listed in the ASL.
Other workarounds may require my.asl
to be customized. If this file is edited, compile the new
ASL using the following command. Warnings
can usually be ignored, but errors are bugs that will usually
prevent ACPI from working correctly.
#
iasl -f
my.asl
Including -f
forces creation of the
AML, even if there are errors during
compilation. Some errors, such as missing return statements,
are automatically worked around by the FreeBSD
interpreter.
The default output filename for iasl
is
DSDT.aml
. Load this file instead of the
BIOS's buggy copy, which is still present
in flash memory, by editing
/boot/loader.conf
as follows:
acpi_dsdt_load="YES" acpi_dsdt_name="/boot/DSDT.aml"
Be sure to copy DSDT.aml
to
/boot
, then reboot the system. If this
fixes the problem, send a diff(1) of the old and new
ASL to freebsd-acpi so that developers can
work around the buggy behavior in
acpica
.
The ACPI driver has a flexible
debugging facility. A set of subsystems and the level of
verbosity can be specified. The subsystems to debug are
specified as layers and are broken down into components
(ACPI_ALL_COMPONENTS
) and
ACPI hardware support
(ACPI_ALL_DRIVERS
). The verbosity of
debugging output is specified as the level and ranges from
just report errors (ACPI_LV_ERROR
) to
everything (ACPI_LV_VERBOSE
). The level is
a bitmask so multiple options can be set at once, separated by
spaces. In practice, a serial console should be used to log
the output so it is not lost as the console message buffer
flushes. A full list of the individual layers and levels is
found in acpi(4).
Debugging output is not enabled by default. To enable it,
add options ACPI_DEBUG
to the custom kernel
configuration file if ACPI is compiled into
the kernel. Add ACPI_DEBUG=1
to
/etc/make.conf
to enable it globally. If
a module is used instead of a custom kernel, recompile just
the acpi.ko
module as follows:
#
cd /sys/modules/acpi/acpi && make clean && make ACPI_DEBUG=1
Copy the compiled acpi.ko
to
/boot/kernel
and add the desired level
and layer to /boot/loader.conf
. The
entries in this example enable debug messages for all
ACPI components and hardware drivers and
output error messages at the least verbose level:
debug.acpi.layer="ACPI_ALL_COMPONENTS ACPI_ALL_DRIVERS" debug.acpi.level="ACPI_LV_ERROR"
If the required information is triggered by a specific
event, such as a suspend and then resume, do not modify
/boot/loader.conf
. Instead, use
sysctl
to specify the layer and level after
booting and preparing the system for the specific event. The
variables which can be set using sysctl
are
named the same as the tunables in
/boot/loader.conf
.
Once the debugging information is gathered, it can be sent to freebsd-acpi so that it can be used by the FreeBSD ACPI maintainers to identify the root cause of the problem and to develop a solution.
Before submitting debugging information to this mailing list, ensure the latest BIOS version is installed and, if available, the embedded controller firmware version.
When submitting a problem report, include the following information:
Description of the buggy behavior, including system type, model, and anything that causes the bug to appear. Note as accurately as possible when the bug began occurring if it is new.
The output of dmesg
after running
boot -v
, including any error messages
generated by the bug.
The dmesg
output from boot
-v
with ACPI disabled,
if disabling ACPI helps to fix the
problem.
Output from sysctl hw.acpi
. This
lists which features the system offers.
The URL to a pasted version of the system's ASL. Do not send the ASL directly to the list as it can be very large. Generate a copy of the ASL by running this command:
#
acpidump -dt >
name
-system
.asl
Substitute the login name for
name
and manufacturer/model for
system
. For example, use
njl-FooCo6000.asl
.
Most FreeBSD developers watch the FreeBSD-CURRENT mailing list, but one should submit problems to freebsd-acpi to be sure it is seen. Be patient when waiting for a response. If the bug is not immediately apparent, submit a bug report. When entering a PR, include the same information as requested above. This helps developers to track the problem and resolve it. Do not send a PR without emailing freebsd-acpi first as it is likely that the problem has been reported before.
More information about ACPI may be found in the following locations:
The FreeBSD ACPI Mailing List Archives
(https://lists.freebsd.org/pipermail/freebsd-acpi/
)
The ACPI 2.0 Specification (http://acpi.info/spec.htm
)
acpi(4), acpi_thermal(4), acpidump(8), iasl(8), and acpidb(8)
[2] The auto-tuning algorithm sets
maxusers
equal to the amount of
memory in the system, with a minimum of
32
, and a maximum of
384
.
The process of starting a computer and loading the operating system is referred to as “the bootstrap process”, or “booting”. FreeBSD's boot process provides a great deal of flexibility in customizing what happens when the system starts, including the ability to select from different operating systems installed on the same computer, different versions of the same operating system, or a different installed kernel.
This chapter details the configuration options that can be set. It demonstrates how to customize the FreeBSD boot process, including everything that happens until the FreeBSD kernel has started, probed for devices, and started init(8). This occurs when the text color of the boot messages changes from bright white to grey.
After reading this chapter, you will recognize:
The components of the FreeBSD bootstrap system and how they interact.
The options that can be passed to the components in the FreeBSD bootstrap in order to control the boot process.
How to configure a customized boot splash screen.
The basics of setting device hints.
How to boot into single- and multi-user mode and how to properly shut down a FreeBSD system.
This chapter only describes the boot process for FreeBSD running on x86 and amd64 systems.
Turning on a computer and starting the operating system poses an interesting dilemma. By definition, the computer does not know how to do anything until the operating system is started. This includes running programs from the disk. If the computer can not run a program from the disk without the operating system, and the operating system programs are on the disk, how is the operating system started?
This problem parallels one in the book The Adventures of Baron Munchausen. A character had fallen part way down a manhole, and pulled himself out by grabbing his bootstraps and lifting. In the early days of computing, the term bootstrap was applied to the mechanism used to load the operating system. It has since become shortened to “booting”.
On x86 hardware, the Basic Input/Output System (BIOS) is responsible for loading the operating system. The BIOS looks on the hard disk for the Master Boot Record (MBR), which must be located in a specific place on the disk. The BIOS has enough knowledge to load and run the MBR, and assumes that the MBR can then carry out the rest of the tasks involved in loading the operating system, possibly with the help of the BIOS.
FreeBSD provides for booting from both the older MBR standard, and the newer GUID Partition Table (GPT). GPT partitioning is often found on computers with the Unified Extensible Firmware Interface (UEFI). However, FreeBSD can boot from GPT partitions even on machines with only a legacy BIOS with gptboot(8). Work is under way to provide direct UEFI booting.
The code within the MBR is typically referred to as a boot manager, especially when it interacts with the user. The boot manager usually has more code in the first track of the disk or within the file system. Examples of boot managers include the standard FreeBSD boot manager boot0, also called Boot Easy, and Grub, which is used by many Linux® distributions.
If only one operating system is installed, the MBR searches for the first bootable (active) slice on the disk, and then runs the code on that slice to load the remainder of the operating system. When multiple operating systems are present, a different boot manager can be installed to display a list of operating systems so the user can select one to boot.
The remainder of the FreeBSD bootstrap system is divided into three stages. The first stage knows just enough to get the computer into a specific state and run the second stage. The second stage can do a little bit more, before running the third stage. The third stage finishes the task of loading the operating system. The work is split into three stages because the MBR puts limits on the size of the programs that can be run at stages one and two. Chaining the tasks together allows FreeBSD to provide a more flexible loader.
The kernel is then started and begins to probe for devices and initialize them for use. Once the kernel boot process is finished, the kernel passes control to the user process init(8), which makes sure the disks are in a usable state, starts the user-level resource configuration which mounts file systems, sets up network cards to communicate on the network, and starts the processes which have been configured to run at startup.
This section describes these stages in more detail and demonstrates how to interact with the FreeBSD boot process.
The boot manager code in the MBR is sometimes referred to as stage zero of the boot process. By default, FreeBSD uses the boot0 boot manager.
The MBR installed by the FreeBSD installer
is based on /boot/boot0
. The size and
capability of boot0 is restricted
to 446 bytes due to the slice table and
0x55AA
identifier at the end of the
MBR. If boot0
and multiple operating systems are installed, a message
similar to this example will be displayed at boot time:
Other operating systems will overwrite an existing MBR if they are installed after FreeBSD. If this happens, or to replace the existing MBR with the FreeBSD MBR, use the following command:
#
fdisk -B -b /boot/boot0
device
where device
is the boot disk,
such as ad0
for the first
IDE disk, ad2
for the
first IDE disk on a second
IDE controller, or da0
for the first SCSI disk. To create a
custom configuration of the MBR, refer to
boot0cfg(8).
Conceptually, the first and second stages are part of the
same program on the same area of the disk. Because of space
constraints, they have been split into two, but are always
installed together. They are copied from the combined
/boot/boot
by the FreeBSD installer or
bsdlabel
.
These two stages are located outside file systems, in the first track of the boot slice, starting with the first sector. This is where boot0, or any other boot manager, expects to find a program to run which will continue the boot process.
The first stage, boot1
, is very
simple, since it can only be 512 bytes in size. It knows just
enough about the FreeBSD bsdlabel, which
stores information about the slice, to find and execute
boot2
.
Stage two, boot2
, is slightly more
sophisticated, and understands the FreeBSD file system enough to
find files. It can provide a simple interface to choose the
kernel or loader to run. It runs
loader, which is much more
sophisticated and provides a boot configuration file. If the
boot process is interrupted at stage two, the following
interactive screen is displayed:
To replace the installed boot1
and
boot2
, use bsdlabel
,
where diskslice
is the disk and
slice to boot from, such as ad0s1
for the
first slice on the first IDE disk:
#
bsdlabel -B
diskslice
If just the disk name is used, such as
ad0
, bsdlabel
will
create the disk in “dangerously dedicated
mode”, without slices. This is probably not the
desired action, so double check the
diskslice
before pressing
Return.
The loader is the final stage
of the three-stage bootstrap process. It is located on the
file system, usually as
/boot/loader
.
The loader is intended as an interactive method for configuration, using a built-in command set, backed up by a more powerful interpreter which has a more complex command set.
During initialization, loader will probe for a console and for disks, and figure out which disk it is booting from. It will set variables accordingly, and an interpreter is started where user commands can be passed from a script or interactively.
The loader will then read
/boot/loader.rc
, which by default reads
in /boot/defaults/loader.conf
which sets
reasonable defaults for variables and reads
/boot/loader.conf
for local changes to
those variables. loader.rc
then acts on
these variables, loading whichever modules and kernel are
selected.
Finally, by default, loader issues a 10 second wait for key presses, and boots the kernel if it is not interrupted. If interrupted, the user is presented with a prompt which understands the command set, where the user may adjust variables, unload all modules, load modules, and then finally boot or reboot. Table 12.1, “Loader Built-In Commands” lists the most commonly used loader commands. For a complete discussion of all available commands, refer to loader(8).
Variable | Description |
---|---|
autoboot
seconds | Proceeds to boot the kernel if not interrupted within the time span given, in seconds. It displays a countdown, and the default time span is 10 seconds. |
boot
[-options ]
[kernelname ] | Immediately proceeds to boot the kernel, with
any specified options or kernel name. Providing a
kernel name on the command-line is only applicable
after an unload has been issued.
Otherwise, the previously-loaded kernel will be
used. If kernelname is not
qualified, it will be searched under
/boot/kernel and
/boot/modules. |
boot-conf | Goes through the same automatic configuration of
modules based on specified variables, most commonly
kernel . This only makes sense if
unload is used first, before
changing some variables. |
help
[topic ] | Shows help messages read from
/boot/loader.help . If the topic
given is index , the list of
available topics is displayed. |
include filename
… | Reads the specified file and interprets it line
by line. An error immediately stops the
include . |
load [-t
type ]
filename | Loads the kernel, kernel module, or file of the
type given, with the specified filename. Any
arguments after filename
are passed to the file. If
filename is not qualified, it
will be searched under
/boot/kernel
and /boot/modules. |
ls [-l]
[path ] | Displays a listing of files in the given path, or
the root directory, if the path is not specified. If
-l is specified, file sizes will
also be shown. |
lsdev [-v] | Lists all of the devices from which it may be
possible to load modules. If -v is
specified, more details are printed. |
lsmod [-v] | Displays loaded modules. If -v
is specified, more details are shown. |
more filename | Displays the files specified, with a pause at
each LINES displayed. |
reboot | Immediately reboots the system. |
set variable , set
variable =value | Sets the specified environment variables. |
unload | Removes all loaded modules. |
Here are some practical examples of loader usage. To boot the usual kernel in single-user mode :
boot -s
To unload the usual kernel and modules and then load the previous or another, specified kernel:
unload
load
kernel.old
Use kernel.GENERIC
to refer to the
default kernel that comes with an installation, or
kernel.old
, to refer to the previously
installed kernel before a system upgrade or before configuring
a custom kernel.
Use the following to load the usual modules with another kernel:
unload
set kernel="
kernel.old
"boot-conf
To load an automated kernel configuration script:
load -t userconfig_script /boot/kernel.conf
Once the kernel is loaded by either loader or by boot2, which bypasses loader, it examines any boot flags and adjusts its behavior as necessary. Table 12.2, “Kernel Interaction During Boot” lists the commonly used boot flags. Refer to boot(8) for more information on the other boot flags.
Option | Description |
---|---|
-a | During kernel initialization, ask for the device to mount as the root file system. |
-C | Boot the root file system from a CDROM. |
-s | Boot into single-user mode. |
-v | Be more verbose during kernel startup. |
Once the kernel has finished booting, it passes control to
the user process init(8), which is located at
/sbin/init
, or the program path specified
in the init_path
variable in
loader
. This is the last stage of the boot
process.
The boot sequence makes sure that the file systems
available on the system are consistent. If a
UFS file system is not, and
fsck
cannot fix the inconsistencies,
init drops the system into
single-user mode so that the system administrator can resolve
the problem directly. Otherwise, the system boots into
multi-user mode.
A user can specify this mode by booting with
-s
or by setting the
boot_single
variable in
loader. It can also be reached
by running shutdown now
from multi-user
mode. Single-user mode begins with this message:
Enter full pathname of shell or RETURN for /bin/sh:
If the user presses Enter, the system will enter the default Bourne shell. To specify a different shell, input the full path to the shell.
Single-user mode is usually used to repair a system that
will not boot due to an inconsistent file system or an error
in a boot configuration file. It can also be used to reset
the root
password
when it is unknown. These actions are possible as the
single-user mode prompt gives full, local access to the
system and its configuration files. There is no networking
in this mode.
While single-user mode is useful for repairing a system, it poses a security risk unless the system is in a physically secure location. By default, any user who can gain physical access to a system will have full control of that system after booting into single-user mode.
If the system console
is changed to
insecure
in
/etc/ttys
, the system will first prompt
for the root
password before initiating single-user mode. This adds a
measure of security while removing the ability to reset the
root
password when
it is unknown.
/etc/ttys
# name getty type status comments
#
# If console is marked "insecure", then init will ask for the root password
# when going to single-user mode.
console none unknown off insecure
An insecure
console means that
physical security to the console is considered to be
insecure, so only someone who knows the root
password may use
single-user mode.
If init finds the file
systems to be in order, or once the user has finished their
commands in single-user mode and has typed
exit
to leave single-user mode, the
system enters multi-user mode, in which it starts the
resource configuration of the system.
The resource configuration system reads in configuration
defaults from /etc/defaults/rc.conf
and
system-specific details from
/etc/rc.conf
. It then proceeds to
mount the system file systems listed in
/etc/fstab
. It starts up networking
services, miscellaneous system daemons, then the startup
scripts of locally installed packages.
To learn more about the resource configuration system,
refer to rc(8) and examine the scripts located in
/etc/rc.d
.
Typically when a FreeBSD system boots, it displays its progress as a series of messages at the console. A boot splash screen creates an alternate boot screen that hides all of the boot probe and service startup messages. A few boot loader messages, including the boot options menu and a timed wait countdown prompt, are displayed at boot time, even when the splash screen is enabled. The display of the splash screen can be turned off by hitting any key on the keyboard during the boot process.
There are two basic environments available in FreeBSD. The first is the default legacy virtual console command line environment. After the system finishes booting, a console login prompt is presented. The second environment is a configured graphical environment. Refer to Chapter 5, The X Window System for more information on how to install and configure a graphical display manager and a graphical login manager.
Once the system has booted, the splash screen defaults to
being a screen saver. After a time period of non-use, the
splash screen will display and will cycle through steps of
changing intensity of the image, from bright to very dark and
over again. The configuration of the splash screen saver can be
overridden by adding a saver=
line to
/etc/rc.conf
. Several built-in screen
savers are available and described in splash(4). The
saver=
option only applies to virtual
consoles and has no effect on graphical display managers.
By installing the
sysutils/bsd-splash-changer package or port,
a random splash image from a collection will display at boot.
The splash screen function supports 256-colors in the
bitmap (.bmp
), ZSoft
PCX (.pcx
), or
TheDraw (.bin
) formats. The
.bmp
, .pcx
, or
.bin
image has to be placed on the root
partition, for example in /boot
. The
splash image files must have a resolution of 320 by 200 pixels
or less in order to work on standard VGA
adapters. For the default boot display resolution of 256-colors
and 320 by 200 pixels or less, add the following lines to
/boot/loader.conf
. Replace
splash.bmp
with the name of the
bitmap file to use:
splash_bmp_load="YES"
bitmap_load="YES"
bitmap_name="/boot/splash.bmp
"
To use a PCX file instead of a bitmap file:
splash_pcx_load="YES"
bitmap_load="YES"
bitmap_name="/boot/splash.pcx
"
To instead use ASCII art in the https://en.wikipedia.org/wiki/TheDraw format:
splash_txt="YES"
bitmap_load="YES"
bitmap_name="/boot/splash.bin
"
To use larger images that fill the whole display screen, up
to the maximum resolution of 1024 by 768 pixels, the
VESA module must also be loaded during system
boot. If using a custom kernel, ensure that the custom kernel
configuration file includes the VESA
kernel
configuration option. To load the VESA
module for the splash screen, add this line to
/boot/loader.conf
before the three lines
mentioned in the above examples:
vesa_load="YES"
Other interesting loader.conf
options
include:
beastie_disable="YES"
This will stop the boot options menu from being displayed, but the timed wait count down prompt will still be present. Even with the display of the boot options menu disabled, entering an option selection at the timed wait count down prompt will enact the corresponding boot option.
loader_logo="beastie"
This will replace the default words “FreeBSD”, which are displayed to the right of the boot options menu, with the colored beastie logo.
For more information, refer to splash(4), loader.conf(5), and vga(4).
During initial system startup, the boot loader(8) reads device.hints(5). This file stores kernel boot information known as variables, sometimes referred to as “device hints”. These “device hints” are used by device drivers for device configuration.
Device hints may also be specified at the Stage 3 boot
loader prompt, as demonstrated in Section 12.2.3, “Stage Three”.
Variables can be added using set
, removed
with unset
, and viewed
show
. Variables set in
/boot/device.hints
can also be overridden.
Device hints entered at the boot loader are not permanent and
will not be applied on the next reboot.
Once the system is booted, kenv(1) can be used to dump all of the variables.
The syntax for /boot/device.hints
is one variable per line, using the hash
“#” as comment markers. Lines are constructed as
follows:
hint.driver.unit.keyword="value
"
The syntax for the Stage 3 boot loader is:
set hint.driver.unit.keyword=value
where driver
is the device driver name,
unit
is the device driver unit number, and
keyword
is the hint keyword. The keyword may
consist of the following options:
at
: specifies the bus which the
device is attached to.
port
: specifies the start address of
the I/O to be used.
irq
: specifies the interrupt request
number to be used.
drq
: specifies the DMA channel
number.
maddr
: specifies the physical memory
address occupied by the device.
flags
: sets various flag bits for the
device.
disabled
: if set to
1
the device is disabled.
Since device drivers may accept or require more hints not listed here, viewing a driver's manual page is recommended. For more information, refer to device.hints(5), kenv(1), loader.conf(5), and loader(8).
Upon controlled shutdown using shutdown(8),
init(8) will attempt to run the script
/etc/rc.shutdown
, and then proceed to send
all processes the TERM
signal, and
subsequently the KILL
signal to any that do
not terminate in a timely manner.
To power down a FreeBSD machine on architectures and systems
that support power management, use
shutdown -p now
to turn the power off
immediately. To reboot a FreeBSD system, use
shutdown -r now
. One must be
root
or a member of
operator
in order to
run shutdown(8). One can also use halt(8) and
reboot(8). Refer to their manual pages and to
shutdown(8) for more information.
Modify group membership by referring to Section 3.3, “Users and Basic Account Management”.
Power management requires acpi(4) to be loaded as a module or statically compiled into a custom kernel.
Security, whether physical or virtual, is a topic so broad that an entire industry has evolved around it. Hundreds of standard practices have been authored about how to secure systems and networks, and as a user of FreeBSD, understanding how to protect against attacks and intruders is a must.
In this chapter, several fundamentals and techniques will be discussed. The FreeBSD system comes with multiple layers of security, and many more third party utilities may be added to enhance security.
After reading this chapter, you will know:
Basic FreeBSD system security concepts.
The various crypt mechanisms available in FreeBSD.
How to set up one-time password authentication.
How to configure TCP Wrapper for use with inetd(8).
How to set up Kerberos on FreeBSD.
How to configure IPsec and create a VPN.
How to configure and use OpenSSH on FreeBSD.
How to use file system ACLs.
How to use pkg to audit third party software packages installed from the Ports Collection.
How to utilize FreeBSD security advisories.
What Process Accounting is and how to enable it on FreeBSD.
How to control user resources using login classes or the resource limits database.
Before reading this chapter, you should:
Understand basic FreeBSD and Internet concepts.
Additional security topics are covered elsewhere in this Handbook. For example, Mandatory Access Control is discussed in Chapter 15, Mandatory Access Control and Internet firewalls are discussed in Chapter 30, Firewalls.
Security is everyone's responsibility. A weak entry point in any system could allow intruders to gain access to critical information and cause havoc on an entire network. One of the core principles of information security is the CIA triad, which stands for the Confidentiality, Integrity, and Availability of information systems.
The CIA triad is a bedrock concept of computer security as customers and users expect their data to be protected. For example, a customer expects that their credit card information is securely stored (confidentiality), that their orders are not changed behind the scenes (integrity), and that they have access to their order information at all times (availablility).
To provide CIA, security professionals apply a defense in depth strategy. The idea of defense in depth is to add several layers of security to prevent one single layer failing and the entire security system collapsing. For example, a system administrator cannot simply turn on a firewall and consider the network or system secure. One must also audit accounts, check the integrity of binaries, and ensure malicious tools are not installed. To implement an effective security strategy, one must understand threats and how to defend against them.
What is a threat as it pertains to computer security? Threats are not limited to remote attackers who attempt to access a system without permission from a remote location. Threats also include employees, malicious software, unauthorized network devices, natural disasters, security vulnerabilities, and even competing corporations.
Systems and networks can be accessed without permission, sometimes by accident, or by remote attackers, and in some cases, via corporate espionage or former employees. As a user, it is important to prepare for and admit when a mistake has led to a security breach and report possible issues to the security team. As an administrator, it is important to know of the threats and be prepared to mitigate them.
When applying security to systems, it is recommended to start by securing the basic accounts and system configuration, and then to secure the network layer so that it adheres to the system policy and the organization's security procedures. Many organizations already have a security policy that covers the configuration of technology devices. The policy should include the security configuration of workstations, desktops, mobile devices, phones, production servers, and development servers. In many cases, standard operating procedures (SOPs) already exist. When in doubt, ask the security team.
The rest of this introduction describes how some of these basic security configurations are performed on a FreeBSD system. The rest of this chapter describes some specific tools which can be used when implementing a security policy on a FreeBSD system.
In securing a system, a good starting point is an audit of
accounts. Ensure that root
has a strong password and
that this password is not shared. Disable any accounts that
do not need login access.
To deny login access to accounts, two methods exist. The
first is to lock the account. This example locks the
toor
account:
#
pw lock
toor
The second method is to prevent login access by changing
the shell to /usr/sbin/nologin
. Only the
superuser can change the shell for other users:
#
chsh -s /usr/sbin/nologin
toor
The /usr/sbin/nologin
shell prevents
the system from assigning a shell to the user when they
attempt to login.
In some cases, system administration needs to be shared
with other users. FreeBSD has two methods to handle this. The
first one, which is not recommended, is a shared root password
used by members of the wheel
group. With this
method, a user types su
and enters the
password for wheel
whenever superuser access is needed. The user should then
type exit
to leave privileged access after
finishing the commands that required administrative access.
To add a user to this group, edit
/etc/group
and add the user to the end of
the wheel
entry. The user must be
separated by a comma character with no space.
The second, and recommended, method to permit privilege escalation is to install the security/sudo package or port. This software provides additional auditing, more fine-grained user control, and can be configured to lock users into running only the specified privileged commands.
After installation, use visudo
to edit
/usr/local/etc/sudoers
. This example
creates a new webadmin
group, adds the
trhodes
account to
that group, and configures that group access to restart
apache24:
#
pw groupadd webadmin -M trhodes -g 6000
#
visudo
%webadmin ALL=(ALL) /usr/sbin/service apache24 *
Passwords are a necessary evil of technology. When they
must be used, they should be complex and a powerful hash
mechanism should be used to encrypt the version that is stored
in the password database. FreeBSD supports the
DES, MD5,
SHA256, SHA512, and
Blowfish hash algorithms in its crypt()
library. The default of SHA512 should not
be changed to a less secure hashing algorithm, but can be
changed to the more secure Blowfish algorithm.
Blowfish is not part of AES and is not considered compliant with any Federal Information Processing Standards (FIPS). Its use may not be permitted in some environments.
To determine which hash algorithm is used to encrypt a
user's password, the superuser can view the hash for the user
in the FreeBSD password database. Each hash starts with a symbol
which indicates the type of hash mechanism used to encrypt the
password. If DES is used, there is no
beginning symbol. For MD5, the symbol is
$
. For SHA256 and
SHA512, the symbol is
$6$
. For Blowfish, the symbol is
$2a$
. In this example, the password for
dru
is hashed using
the default SHA512 algorithm as the hash
starts with $6$
. Note that the encrypted
hash, not the password itself, is stored in the password
database:
#
grep dru /etc/master.passwd
dru:$6$pzIjSvCAn.PBYQBA$PXpSeWPx3g5kscj3IMiM7tUEUSPmGexxta.8Lt9TGSi2lNQqYGKszsBPuGME0:1001:1001::0:0:dru:/usr/home/dru:/bin/csh
The hash mechanism is set in the user's login class. For
this example, the user is in the default
login class and the hash algorithm is set with this line in
/etc/login.conf
:
:passwd_format=sha512:\
To change the algorithm to Blowfish, modify that line to look like this:
:passwd_format=blf:\
Then run cap_mkdb /etc/login.conf
as
described in Section 13.13.1, “Configuring Login Classes”. Note that this
change will not affect any existing password hashes. This
means that all passwords should be re-hashed by asking users
to run passwd
in order to change their
password.
For remote logins, two-factor authentication should be used. An example of two-factor authentication is “something you have”, such as a key, and “something you know”, such as the passphrase for that key. Since OpenSSH is part of the FreeBSD base system, all network logins should be over an encrypted connection and use key-based authentication instead of passwords. For more information, refer to Section 13.8, “OpenSSH”. Kerberos users may need to make additional changes to implement OpenSSH in their network. These changes are described in Section 13.5, “Kerberos”.
Enforcing a strong password policy for local accounts is a fundamental aspect of system security. In FreeBSD, password length, password strength, and password complexity can be implemented using built-in Pluggable Authentication Modules (PAM).
This section demonstrates how to configure the minimum and
maximum password length and the enforcement of mixed
characters using the pam_passwdqc.so
module. This module is enforced when a user changes their
password.
To configure this module, become the superuser and
uncomment the line containing
pam_passwdqc.so
in
/etc/pam.d/passwd
. Then, edit that line
to match the password policy:
password requisite pam_passwdqc.so min=disabled,disabled,disabled,12,10 similar=deny retry=3
enforce=users
This example sets several requirements for new passwords.
The min
setting controls the minimum
password length. It has five values because this module
defines five different types of passwords based on their
complexity. Complexity is defined by the type of characters
that must exist in a password, such as letters, numbers,
symbols, and case. The types of passwords are described in
pam_passwdqc(8). In this example, the first three types
of passwords are disabled, meaning that passwords that meet
those complexity requirements will not be accepted, regardless
of their length. The 12
sets a minimum
password policy of at least twelve characters, if the password
also contains characters with three types of complexity. The
10
sets the password policy to also allow
passwords of at least ten characters, if the password contains
characters with four types of complexity.
The similar
setting denies passwords
that are similar to the user's previous password. The
retry
setting provides a user with three
opportunities to enter a new password.
Once this file is saved, a user changing their password will see a message similar to the following:
%
passwd
Changing local password for trhodes Old Password: You can now choose the new password. A valid password should be a mix of upper and lower case letters, digits and other characters. You can use a 12 character long password with characters from at least 3 of these 4 classes, or a 10 character long password containing characters from all the classes. Characters that form a common pattern are discarded by the check. Alternatively, if no one else can see your terminal now, you can pick this as your password: "trait-useful&knob". Enter new password:
If a password that does not match the policy is entered, it will be rejected with a warning and the user will have an opportunity to try again, up to the configured number of retries.
Most password policies require passwords to expire after
so many days. To set a password age time in FreeBSD, set
passwordtime
for the user's login class in
/etc/login.conf
. The
default
login class contains an
example:
# :passwordtime=90d:\
So, to set an expiry of 90 days for this login class,
remove the comment symbol (#
), save the
edit, and run cap_mkdb
/etc/login.conf
.
To set the expiration on individual users, pass an
expiration date or the number of days to expiry and a username
to pw
:
#
pw usermod -p
30-apr-2015
-ntrhodes
As seen here, an expiration date is set in the form of day, month, and year. For more information, see pw(8).
A rootkit is any unauthorized
software that attempts to gain root
access to a system. Once
installed, this malicious software will normally open up
another avenue of entry for an attacker. Realistically, once
a system has been compromised by a rootkit and an
investigation has been performed, the system should be
reinstalled from scratch. There is tremendous risk that even
the most prudent security or systems engineer will miss
something an attacker left behind.
A rootkit does do one thing useful for administrators: once detected, it is a sign that a compromise happened at some point. But, these types of applications tend to be very well hidden. This section demonstrates a tool that can be used to detect rootkits, security/rkhunter.
After installation of this package or port, the system may be checked using the following command. It will produce a lot of information and will require some manual pressing of ENTER:
#
rkhunter -c
After the process completes, a status message will be printed to the screen. This message will include the amount of files checked, suspect files, possible rootkits, and more. During the check, some generic security warnings may be produced about hidden files, the OpenSSH protocol selection, and known vulnerable versions of installed software. These can be handled now or after a more detailed analysis has been performed.
Every administrator should know what is running on the
systems they are responsible for. Third-party tools like
rkhunter and
sysutils/lsof, and native commands such
as netstat
and ps
, can
show a great deal of information on the system. Take notes on
what is normal, ask questions when something seems out of
place, and be paranoid. While preventing a compromise is
ideal, detecting a compromise is a must.
Verification of system files and binaries is important because it provides the system administration and security teams information about system changes. A software application that monitors the system for changes is called an Intrusion Detection System (IDS).
FreeBSD provides native support for a basic IDS system. While the nightly security emails will notify an administrator of changes, the information is stored locally and there is a chance that a malicious user could modify this information in order to hide their changes to the system. As such, it is recommended to create a separate set of binary signatures and store them on a read-only, root-owned directory or, preferably, on a removable USB disk or remote rsync server.
The built-in mtree
utility can be used
to generate a specification of the contents of a directory. A
seed, or a numeric constant, is used to generate the
specification and is required to check that the specification
has not changed. This makes it possible to determine if a
file or binary has been modified. Since the seed value is
unknown by an attacker, faking or checking the checksum values
of files will be difficult to impossible. The following
example generates a set of SHA256 hashes,
one for each system binary in /bin
, and
saves those values to a hidden file in root
's home directory,
/root/.bin_chksum_mtree
:
#
mtree -s
3483151339707503
-c -K cksum,sha256digest -p/bin
>/root/.bin_chksum_mtree
#
mtree: /bin checksum: 3427012225
The 3483151339707503
represents
the seed. This value should be remembered, but not
shared.
Viewing /root/.bin_cksum_mtree
should
yield output similar to the following:
# user: root # machine: dreadnaught # tree: /bin # date: Mon Feb 3 10:19:53 2014 # . /set type=file uid=0 gid=0 mode=0555 nlink=1 flags=none . type=dir mode=0755 nlink=2 size=1024 \ time=1380277977.000000000 \133 nlink=2 size=11704 time=1380277977.000000000 \ cksum=484492447 \ sha256digest=6207490fbdb5ed1904441fbfa941279055c3e24d3a4049aeb45094596400662a cat size=12096 time=1380277975.000000000 cksum=3909216944 \ sha256digest=65ea347b9418760b247ab10244f47a7ca2a569c9836d77f074e7a306900c1e69 chflags size=8168 time=1380277975.000000000 cksum=3949425175 \ sha256digest=c99eb6fc1c92cac335c08be004a0a5b4c24a0c0ef3712017b12c89a978b2dac3 chio size=18520 time=1380277975.000000000 cksum=2208263309 \ sha256digest=ddf7c8cb92a58750a675328345560d8cc7fe14fb3ccd3690c34954cbe69fc964 chmod size=8640 time=1380277975.000000000 cksum=2214429708 \ sha256digest=a435972263bf814ad8df082c0752aa2a7bdd8b74ff01431ccbd52ed1e490bbe7
The machine's hostname, the date and time the specification was created, and the name of the user who created the specification are included in this report. There is a checksum, size, time, and SHA256 digest for each binary in the directory.
To verify that the binary signatures have not changed, compare the current contents of the directory to the previously generated specification, and save the results to a file. This command requires the seed that was used to generate the original specification:
#
mtree -s
3483151339707503
-p/bin
</root/.bin_chksum_mtree
>>/root/.bin_chksum_output
#
mtree: /bin checksum: 3427012225
This should produce the same checksum for
/bin
that was produced when the
specification was created. If no changes have occurred to the
binaries in this directory, the
/root/.bin_chksum_output
output file will
be empty. To simulate a change, change the date on
/bin/cat
using touch
and run the verification command again:
#
touch /bin/cat
#
mtree -s
3483151339707503
-p/bin
</root/.bin_chksum_mtree
>>/root/.bin_chksum_output
#
more /root/.bin_chksum_output
cat changed modification time expected Fri Sep 27 06:32:55 2013 found Mon Feb 3 10:28:43 2014
It is recommended to create specifications for the
directories which contain binaries and configuration files, as
well as any directories containing sensitive data. Typically,
specifications are created for /bin
,
/sbin
, /usr/bin
,
/usr/sbin
,
/usr/local/bin
,
/etc
, and
/usr/local/etc
.
More advanced IDS systems exist, such
as security/aide. In most cases,
mtree
provides the functionality
administrators need. It is important to keep the seed value
and the checksum output hidden from malicious users. More
information about mtree
can be found in
mtree(8).
In FreeBSD, many system features can be tuned using
sysctl
. A few of the security features
which can be tuned to prevent Denial of Service
(DoS) attacks will be covered in this
section. More information about using
sysctl
, including how to temporarily change
values and how to make the changes permanent after testing,
can be found in Section 11.9, “Tuning with sysctl(8)”.
Any time a setting is changed with
sysctl
, the chance to cause undesired
harm is increased, affecting the availability of the system.
All changes should be monitored and, if possible, tried on a
testing system before being used on a production
system.
By default, the FreeBSD kernel boots with a security level of
-1
. This is called “insecure
mode” because immutable file flags may be turned off
and all devices may be read from or written to. The security
level will remain at -1
unless it is
altered through sysctl
or by a setting in
the startup scripts. The security level may be increased
during system startup by setting
kern_securelevel_enable
to
YES
in /etc/rc.conf
,
and the value of kern_securelevel
to the
desired security level. See security(7) and init(8)
for more information on these settings and the available
security levels.
Increasing the securelevel
can break
Xorg and cause other issues. Be
prepared to do some debugging.
The net.inet.tcp.blackhole
and
net.inet.udp.blackhole
settings can be used
to drop incoming SYN packets on closed
ports without sending a return RST
response. The default behavior is to return an
RST to show a port is closed. Changing the
default provides some level of protection against ports scans,
which are used to determine which applications are running on
a system. Set net.inet.tcp.blackhole
to
2
and
net.inet.udp.blackhole
to
1
. Refer to blackhole(4) for more
information about these settings.
The net.inet.icmp.drop_redirect
and
net.inet.ip.redirect
settings help prevent
against redirect attacks. A redirect
attack is a type of DoS which sends mass
numbers of ICMP type 5 packets. Since
these packets are not required, set
net.inet.icmp.drop_redirect
to
1
and set
net.inet.ip.redirect
to
0
.
Source routing is a method for detecting and accessing
non-routable addresses on the internal network. This should
be disabled as non-routable addresses are normally not
routable on purpose. To disable this feature, set
net.inet.ip.sourceroute
and
net.inet.ip.accept_sourceroute
to
0
.
When a machine on the network needs to send messages to
all hosts on a subnet, an ICMP echo request
message is sent to the broadcast address. However, there is
no reason for an external host to perform such an action. To
reject all external broadcast requests, set
net.inet.icmp.bmcastecho
to
0
.
Some additional settings are documented in security(7).
By default, FreeBSD includes support for One-time Passwords In Everything (OPIE). OPIE is designed to prevent replay attacks, in which an attacker discovers a user's password and uses it to access a system. Since a password is only used once in OPIE, a discovered password is of little use to an attacker. OPIE uses a secure hash and a challenge/response system to manage passwords. The FreeBSD implementation uses the MD5 hash by default.
OPIE uses three different types of
passwords. The first is the usual UNIX® or Kerberos password.
The second is the one-time password which is generated by
opiekey
. The third type of password is the
“secret password” which is used to generate
one-time passwords. The secret password has nothing to do with,
and should be different from, the UNIX® password.
There are two other pieces of data that are important to
OPIE. One is the “seed” or
“key”, consisting of two letters and five digits.
The other is the “iteration count”, a number
between 1 and 100. OPIE creates the one-time
password by concatenating the seed and the secret password,
applying the MD5 hash as many times as
specified by the iteration count, and turning the result into
six short English words which represent the one-time password.
The authentication system keeps track of the last one-time
password used, and the user is authenticated if the hash of the
user-provided password is equal to the previous password.
Because a one-way hash is used, it is impossible to generate
future one-time passwords if a successfully used password is
captured. The iteration count is decremented after each
successful login to keep the user and the login program in sync.
When the iteration count gets down to 1
,
OPIE must be reinitialized.
There are a few programs involved in this process. A
one-time password, or a consecutive list of one-time passwords,
is generated by passing an iteration count, a seed, and a secret
password to opiekey(1). In addition to initializing
OPIE, opiepasswd(1) is used to change
passwords, iteration counts, or seeds. The relevant credential
files in /etc/opiekeys
are examined by
opieinfo(1) which prints out the invoking user's current
iteration count and seed.
This section describes four different sorts of operations.
The first is how to set up one-time-passwords for the first time
over a secure connection. The second is how to use
opiepasswd
over an insecure connection. The
third is how to log in over an insecure connection. The fourth
is how to generate a number of keys which can be written down or
printed out to use at insecure locations.
To initialize OPIE for the first time, run this command from a secure location:
%
opiepasswd -c
Adding unfurl: Only use this method from the console; NEVER from remote. If you are using telnet, xterm, or a dial-in, type ^C now or exit with no password. Then run opiepasswd without the -c parameter. Using MD5 to compute responses. Enter new secret pass phrase: Again new secret pass phrase: ID unfurl OTP key is 499 to4268 MOS MALL GOAT ARM AVID COED
The -c
sets console mode which assumes
that the command is being run from a secure location, such as
a computer under the user's control or a
SSH session to a computer under the user's
control.
When prompted, enter the secret password which will be used to generate the one-time login keys. This password should be difficult to guess and should be different than the password which is associated with the user's login account. It must be between 10 and 127 characters long. Remember this password.
The ID
line lists the login name
(unfurl
), default iteration count
(499
), and default seed
(to4268
). When logging in, the system will
remember these parameters and display them, meaning that they
do not have to be memorized. The last line lists the
generated one-time password which corresponds to those
parameters and the secret password. At the next login, use
this one-time password.
To initialize or change the secret password on an
insecure system, a secure connection is needed to some place
where opiekey
can be run. This might be a
shell prompt on a trusted machine. An iteration count is
needed, where 100 is probably a good value, and the seed can
either be specified or the randomly-generated one used. On
the insecure connection, the machine being initialized, use
opiepasswd(1):
%
opiepasswd
Updating unfurl: You need the response from an OTP generator. Old secret pass phrase: otp-md5 498 to4268 ext Response: GAME GAG WELT OUT DOWN CHAT New secret pass phrase: otp-md5 499 to4269 Response: LINE PAP MILK NELL BUOY TROY ID mark OTP key is 499 gr4269 LINE PAP MILK NELL BUOY TROY
To accept the default seed, press Return. Before entering an access password, move over to the secure connection and give it the same parameters:
%
opiekey 498 to4268
Using the MD5 algorithm to compute response. Reminder: Do not use opiekey from telnet or dial-in sessions. Enter secret pass phrase: GAME GAG WELT OUT DOWN CHAT
Switch back over to the insecure connection, and copy the generated one-time password over to the relevant program.
After initializing OPIE and logging in, a prompt like this will be displayed:
%
telnet example.com
Trying 10.0.0.1... Connected to example.com Escape character is '^]'. FreeBSD/i386 (example.com) (ttypa) login:<username>
otp-md5 498 gr4269 ext Password:
The OPIE prompts provides a useful feature. If Return is pressed at the password prompt, the prompt will turn echo on and display what is typed. This can be useful when attempting to type in a password by hand from a printout.
At this point, generate the one-time password to answer this login prompt. This must be done on a trusted system where it is safe to run opiekey(1). There are versions of this command for Windows®, Mac OS® and FreeBSD. This command needs the iteration count and the seed as command line options. Use cut-and-paste from the login prompt on the machine being logged in to.
On the trusted system:
%
opiekey 498 to4268
Using the MD5 algorithm to compute response. Reminder: Do not use opiekey from telnet or dial-in sessions. Enter secret pass phrase: GAME GAG WELT OUT DOWN CHAT
Once the one-time password is generated, continue to log in.
Sometimes there is no access to a trusted machine or secure connection. In this case, it is possible to use opiekey(1) to generate a number of one-time passwords beforehand. For example:
%
opiekey -n 5 30 zz99999
Using the MD5 algorithm to compute response. Reminder: Do not use opiekey from telnet or dial-in sessions. Enter secret pass phrase:<secret password>
26: JOAN BORE FOSS DES NAY QUIT 27: LATE BIAS SLAY FOLK MUCH TRIG 28: SALT TIN ANTI LOON NEAL USE 29: RIO ODIN GO BYE FURY TIC 30: GREW JIVE SAN GIRD BOIL PHI
The -n 5
requests five keys in sequence,
and 30
specifies what the last iteration
number should be. Note that these are printed out in
reverse order of use. The really
paranoid might want to write the results down by hand;
otherwise, print the list. Each line shows both the iteration
count and the one-time password. Scratch off the passwords as
they are used.
OPIE can restrict the use of UNIX®
passwords based on the IP address of a login session. The
relevant file is /etc/opieaccess
, which
is present by default. Refer to opieaccess(5) for more
information on this file and which security considerations to
be aware of when using it.
Here is a sample opieaccess
:
permit 192.168.0.0 255.255.0.0
This line allows users whose IP source address (which is vulnerable to spoofing) matches the specified value and mask, to use UNIX® passwords at any time.
If no rules in opieaccess
are
matched, the default is to deny non-OPIE
logins.
TCP Wrapper is a host-based access control system which extends the abilities of Section 29.2, “The inetd Super-Server”. It can be configured to provide logging support, return messages, and connection restrictions for the server daemons under the control of inetd. Refer to tcpd(8) for more information about TCP Wrapper and its features.
TCP Wrapper should not be considered a replacement for a properly configured firewall. Instead, TCP Wrapper should be used in conjunction with a firewall and other security enhancements in order to provide another layer of protection in the implementation of a security policy.
To enable TCP Wrapper in FreeBSD,
add the following lines to
/etc/rc.conf
:
inetd_enable="YES" inetd_flags="-Ww"
Then, properly configure
/etc/hosts.allow
.
Unlike other implementations of
TCP Wrapper, the use of
hosts.deny
is deprecated in FreeBSD. All
configuration options should be placed in
/etc/hosts.allow
.
In the simplest configuration, daemon connection policies
are set to either permit or block, depending on the options in
/etc/hosts.allow
. The default
configuration in FreeBSD is to allow all connections to the
daemons started with inetd.
Basic configuration usually takes the form of
daemon : address : action
, where
daemon
is the daemon which
inetd started,
address
is a valid hostname,
IP address, or an IPv6 address enclosed in
brackets ([ ]), and action
is either
allow
or deny
.
TCP Wrapper uses a first rule match
semantic, meaning that the configuration file is scanned from
the beginning for a matching rule. When a match is found, the
rule is applied and the search process stops.
For example, to allow POP3 connections
via the mail/qpopper daemon, the following
lines should be appended to
hosts.allow
:
# This line is required for POP3 connections: qpopper : ALL : allow
Whenever this file is edited, restart inetd:
#
service inetd restart
TCP Wrapper provides advanced options to allow more control over the way connections are handled. In some cases, it may be appropriate to return a comment to certain hosts or daemon connections. In other cases, a log entry should be recorded or an email sent to the administrator. Other situations may require the use of a service for local connections only. This is all possible through the use of configuration options known as wildcards, expansion characters, and external command execution.
Suppose that a situation occurs where a connection should
be denied yet a reason should be sent to the host who
attempted to establish that connection. That action is
possible with twist
. When a connection
attempt is made, twist
executes a shell
command or script. An example exists in
hosts.allow
:
# The rest of the daemons are protected. ALL : ALL \ : severity auth.info \ : twist /bin/echo "You are not welcome to use %d from %h."
In this example, the message “You are not allowed to
use daemon name
from
hostname
.” will be
returned for any daemon not configured in
hosts.allow
. This is useful for sending
a reply back to the connection initiator right after the
established connection is dropped. Any message returned
must be wrapped in quote
("
) characters.
It may be possible to launch a denial of service attack on the server if an attacker floods these daemons with connection requests.
Another possibility is to use spawn
.
Like twist
, spawn
implicitly
denies the connection and may be used to run external shell
commands or scripts. Unlike twist
,
spawn
will not send a reply back to the host
who established the connection. For example, consider the
following configuration:
# We do not allow connections from example.com: ALL : .example.com \ : spawn (/bin/echo %a from %h attempted to access %d >> \ /var/log/connections.log) \ : deny
This will deny all connection attempts from *.example.com
and log the
hostname, IP address, and the daemon to
which access was attempted to
/var/log/connections.log
. This example
uses the substitution characters %a
and
%h
. Refer to hosts_access(5) for the
complete list.
To match every instance of a daemon, domain, or
IP address, use ALL
.
Another wildcard is PARANOID
which may be
used to match any host which provides an IP
address that may be forged because the IP
address differs from its resolved hostname. In this example,
all connection requests to Sendmail
which have an IP address that varies from
its hostname will be denied:
# Block possibly spoofed requests to sendmail: sendmail : PARANOID : deny
Using the PARANOID
wildcard will
result in denied connections if the client or server has a
broken DNS setup.
To learn more about wildcards and their associated functionality, refer to hosts_access(5).
When adding new configuration lines, make sure that any
unneeded entries for that daemon are commented out in
hosts.allow
.
Kerberos is a network authentication protocol which was originally created by the Massachusetts Institute of Technology (MIT) as a way to securely provide authentication across a potentially hostile network. The Kerberos protocol uses strong cryptography so that both a client and server can prove their identity without sending any unencrypted secrets over the network. Kerberos can be described as an identity-verifying proxy system and as a trusted third-party authentication system. After a user authenticates with Kerberos, their communications can be encrypted to assure privacy and data integrity.
The only function of Kerberos is to provide the secure authentication of users and servers on the network. It does not provide authorization or auditing functions. It is recommended that Kerberos be used with other security methods which provide authorization and audit services.
The current version of the protocol is version 5, described in RFC 4120. Several free implementations of this protocol are available, covering a wide range of operating systems. MIT continues to develop their Kerberos package. It is commonly used in the US as a cryptography product, and has historically been subject to US export regulations. In FreeBSD, MIT Kerberos is available as the security/krb5 package or port. The Heimdal Kerberos implementation was explicitly developed outside of the US to avoid export regulations. The Heimdal Kerberos distribution is included in the base FreeBSD installation, and another distribution with more configurable options is available as security/heimdal in the Ports Collection.
In Kerberos users and services
are identified as “principals” which are contained
within an administrative grouping, called a
“realm”. A typical user principal would be of the
form
(realms are traditionally uppercase).user
@REALM
This section provides a guide on how to set up Kerberos using the Heimdal distribution included in FreeBSD.
For purposes of demonstrating a Kerberos installation, the name spaces will be as follows:
The DNS domain (zone) will be
example.org
.
The Kerberos realm will be
EXAMPLE.ORG
.
Use real domain names when setting up Kerberos, even if it will run internally. This avoids DNS problems and assures inter-operation with other Kerberos realms.
The Key Distribution Center (KDC) is the centralized authentication service that Kerberos provides, the “trusted third party” of the system. It is the computer that issues Kerberos tickets, which are used for clients to authenticate to servers. Because the KDC is considered trusted by all other computers in the Kerberos realm, it has heightened security concerns. Direct access to the KDC should be limited.
While running a KDC requires few computing resources, a dedicated machine acting only as a KDC is recommended for security reasons.
To begin setting up a KDC, add these
lines to /etc/rc.conf
:
kdc_enable="YES" kadmind_enable="YES"
Next, edit /etc/krb5.conf
as
follows:
[libdefaults] default_realm =EXAMPLE.ORG
[realms]EXAMPLE.ORG
= { kdc =kerberos.example.org
admin_server =kerberos.example.org
} [domain_realm].example.org
=EXAMPLE.ORG
In this example, the KDC will use the
fully-qualified hostname kerberos.example.org
. The
hostname of the KDC must be resolvable in the
DNS.
Kerberos can also use the
DNS to locate KDCs, instead of a
[realms]
section in
/etc/krb5.conf
. For large organizations
that have their own DNS servers, the above
example could be trimmed to:
[libdefaults] default_realm =EXAMPLE.ORG
[domain_realm].example.org
=EXAMPLE.ORG
With the following lines being included in the
example.org
zone
file:
_kerberos._udp IN SRV 01 00 88kerberos.example.org
. _kerberos._tcp IN SRV 01 00 88kerberos.example.org
. _kpasswd._udp IN SRV 01 00 464kerberos.example.org
. _kerberos-adm._tcp IN SRV 01 00 749kerberos.example.org
. _kerberos IN TXTEXAMPLE.ORG
In order for clients to be able to find the
Kerberos services, they
must have either
a fully configured /etc/krb5.conf
or a
minimally configured /etc/krb5.conf
and a properly configured
DNS server.
Next, create the Kerberos
database which contains the keys of all principals (users and
hosts) encrypted with a master password. It is not required
to remember this password as it will be stored in
/var/heimdal/m-key
; it would be
reasonable to use a 45-character random password for this
purpose. To create the master key, run
kstash
and enter a password:
#
kstash
Master key:Verifying password - Master key:
xxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxxxxxxxxxxxxxx
Once the master key has been created, the database should
be initialized. The Kerberos
administrative tool kadmin(8) can be used on the KDC in a
mode that operates directly on the database, without using the
kadmind(8) network service, as
kadmin -l
. This resolves the
chicken-and-egg problem of trying to connect to the database
before it is created. At the kadmin
prompt, use init
to create the realm's
initial database:
#
kadmin -l
kadmin>init
Realm max ticket life [unlimited]:EXAMPLE.ORG
Lastly, while still in kadmin
, create
the first principal using add
. Stick to
the default options for the principal for now, as these can be
changed later with modify
. Type
?
at the prompt to see the available
options.
kadmin>add
Max ticket life [unlimited]: Max renewable life [unlimited]: Attributes []: Password:tillman
Verifying password - Password:
xxxxxxxx
xxxxxxxx
Next, start the KDC services by running
service kdc start
and
service kadmind start
. While there will
not be any kerberized daemons running at this point, it is
possible to confirm that the KDC is
functioning by obtaining a ticket for the
principal that was just created:
%
kinit
tillman@EXAMPLE.ORG's Password:tillman
Confirm that a ticket was successfully obtained using
klist
:
%
klist
Credentials cache: FILE:/tmp/krb5cc_1001 Principal: tillman@EXAMPLE.ORG Issued Expires Principal Aug 27 15:37:58 2013 Aug 28 01:37:58 2013 krbtgt/EXAMPLE.ORG@EXAMPLE.ORG
The temporary ticket can be destroyed when the test is finished:
%
kdestroy
The first step in configuring a server to use
Kerberos authentication is to
ensure that it has the correct configuration in
/etc/krb5.conf
. The version from the
KDC can be used as-is, or it can be
regenerated on the new system.
Next, create /etc/krb5.keytab
on the
server. This is the main part of “Kerberizing” a
service — it corresponds to generating a secret shared
between the service and the KDC. The
secret is a cryptographic key, stored in a
“keytab”. The keytab contains the server's host
key, which allows it and the KDC to verify
each others' identity. It must be transmitted to the server
in a secure fashion, as the security of the server can be
broken if the key is made public. Typically, the
keytab
is generated on an administrator's
trusted machine using kadmin
, then securely
transferred to the server, e.g., with scp(1); it can also
be created directly on the server if that is consistent with
the desired security policy. It is very important that the
keytab is transmitted to the server in a secure fashion: if
the key is known by some other party, that party can
impersonate any user to the server! Using
kadmin
on the server directly is
convenient, because the entry for the host principal in the
KDC database is also created using
kadmin
.
Of course, kadmin
is a kerberized
service; a Kerberos ticket is
needed to authenticate to the network service, but to ensure
that the user running kadmin
is actually
present (and their session has not been hijacked),
kadmin
will prompt for the password to get
a fresh ticket. The principal authenticating to the kadmin
service must be permitted to use the kadmin
interface, as specified in kadmind.acl
.
See the section titled “Remote administration” in
info heimdal
for details on designing
access control lists. Instead of enabling remote
kadmin
access, the administrator could
securely connect to the KDC via the local
console or ssh(1), and perform administration locally
using kadmin -l
.
After installing /etc/krb5.conf
,
use add --random-key
in
kadmin
. This adds the server's host
principal to the database, but does not extract a copy of the
host principal key to a keytab. To generate the keytab, use
ext
to extract the server's host principal
key to its own keytab:
#
kadmin
kadmin>add --random-key host/myserver.example.org
Max ticket life [unlimited]: Max renewable life [unlimited]: Principal expiration time [never]: Password expiration time [never]: Attributes []: kadmin>ext_keytab
kadmin>host/myserver.example.org
exit
Note that ext_keytab
stores the
extracted key in /etc/krb5.keytab
by
default. This is good when being run on the server being
kerberized, but the --keytab
argument
should be used when the keytab is being extracted
elsewhere:path/to/file
#
kadmin
kadmin>ext_keytab --keytab=/tmp/example.keytab
kadmin>host/myserver.example.org
exit
The keytab can then be securely copied to the server using scp(1) or a removable media. Be sure to specify a non-default keytab name to avoid inserting unneeded keys into the system's keytab.
At this point, the server can read encrypted messages from
the KDC using its shared key, stored in
krb5.keytab
. It is now ready for the
Kerberos-using services to be
enabled. One of the most common such services is
sshd(8), which supports
Kerberos via the
GSS-API. In
/etc/ssh/sshd_config
, add the
line:
GSSAPIAuthentication yes
After making this change, sshd(8) must be restarted
for the new configuration to take effect:
service sshd restart
.
As it was for the server, the client requires
configuration in /etc/krb5.conf
. Copy
the file in place (securely) or re-enter it as needed.
Test the client by using kinit
,
klist
, and kdestroy
from
the client to obtain, show, and then delete a ticket for an
existing principal. Kerberos
applications should also be able to connect to
Kerberos enabled servers. If that
does not work but obtaining a ticket does, the problem is
likely with the server and not with the client or the
KDC. In the case of kerberized
ssh(1), GSS-API is disabled by
default, so test using ssh -o
GSSAPIAuthentication=yes
.hostname
When testing a Kerberized application, try using a packet
sniffer such as tcpdump
to confirm that no
sensitive information is sent in the clear.
Various Kerberos client applications are available. With the advent of a bridge so that applications using SASL for authentication can use GSS-API mechanisms as well, large classes of client applications can use Kerberos for authentication, from Jabber clients to IMAP clients.
Users within a realm typically have their
Kerberos principal mapped to a
local user account. Occasionally, one needs to grant access
to a local user account to someone who does not have a
matching Kerberos principal. For
example, tillman@EXAMPLE.ORG
may need
access to the local user account webdevelopers
. Other
principals may also need access to that local account.
The .k5login
and
.k5users
files, placed in a user's home
directory, can be used to solve this problem. For example, if
the following .k5login
is placed in the
home directory of webdevelopers
, both principals
listed will have access to that account without requiring a
shared password:
tillman@example.org jdoe@example.org
Refer to ksu(1) for more information about
.k5users
.
The major difference between the MIT
and Heimdal implementations is that kadmin
has a different, but equivalent, set of commands and uses a
different protocol. If the KDC is
MIT, the Heimdal version of
kadmin
cannot be used to administer the
KDC remotely, and vice versa.
Client applications may also use slightly different
command line options to accomplish the same tasks. Following
the instructions at http://web.mit.edu/Kerberos/www/
is recommended. Be careful of path issues: the
MIT port installs into
/usr/local/
by default, and the FreeBSD
system applications run instead of the
MIT versions if PATH
lists
the system directories first.
When using MIT Kerberos as a KDC on
FreeBSD, the following edits should also be made to
rc.conf
:
kerberos5_server="/usr/local/sbin/krb5kdc" kadmind5_server="/usr/local/sbin/kadmind" kerberos5_server_flags="" kerberos5_server_enable="YES" kadmind5_server_enable="YES"
When configuring and troubleshooting Kerberos, keep the following points in mind:
When using either Heimdal or MIT
Kerberos from ports, ensure
that the PATH
lists the port's versions of
the client applications before the system versions.
If all the computers in the realm do not have synchronized time settings, authentication may fail. Section 29.11, “Clock Synchronization with NTP” describes how to synchronize clocks using NTP.
If the hostname is changed, the host/
principal must be
changed and the keytab updated. This also applies to
special keytab entries like the HTTP/
principal used for
Apache's www/mod_auth_kerb.
All hosts in the realm must be both forward and
reverse resolvable in DNS or, at a
minimum, exist in /etc/hosts
. CNAMEs
will work, but the A and PTR records must be correct and
in place. The error message for unresolvable hosts is not
intuitive: Kerberos5 refuses authentication
because Read req failed: Key table entry not
found.
Some operating systems that act as clients to the
KDC do not set the permissions for
ksu
to be setuid root
. This means that
ksu
does not work. This is a
permissions problem, not a KDC
error.
With MIT
Kerberos, to allow a principal
to have a ticket life longer than the default lifetime of
ten hours, use modify_principal
at the
kadmin(8) prompt to change the
maxlife
of both the principal in
question and the
krbtgt
principal. The principal can then use
kinit -l
to request a ticket with a
longer lifetime.
When running a packet sniffer on the
KDC to aid in troubleshooting while
running kinit
from a workstation, the
Ticket Granting Ticket (TGT) is sent
immediately, even before the password is typed. This is
because the Kerberos server
freely transmits a TGT to any
unauthorized request. However, every
TGT is encrypted in a key derived from
the user's password. When a user types their password, it
is not sent to the KDC, it is instead
used to decrypt the TGT that
kinit
already obtained. If the
decryption process results in a valid ticket with a valid
time stamp, the user has valid
Kerberos credentials. These
credentials include a session key for establishing secure
communications with the
Kerberos server in the future,
as well as the actual TGT, which is
encrypted with the Kerberos
server's own key. This second layer of encryption allows
the Kerberos server to verify
the authenticity of each TGT.
Host principals can have a longer ticket lifetime. If the user principal has a lifetime of a week but the host being connected to has a lifetime of nine hours, the user cache will have an expired host principal and the ticket cache will not work as expected.
When setting up krb5.dict
to
prevent specific bad passwords from being used as
described in kadmind(8), remember that it only
applies to principals that have a password policy assigned
to them. The format used in
krb5.dict
is one string per line.
Creating a symbolic link to
/usr/share/dict/words
might be
useful.
Since Kerberos is an all or nothing approach, every service enabled on the network must either be modified to work with Kerberos or be otherwise secured against network attacks. This is to prevent user credentials from being stolen and re-used. An example is when Kerberos is enabled on all remote shells but the non-Kerberized POP3 mail server sends passwords in plain text.
The KDC is a single point of failure. By design, the KDC must be as secure as its master password database. The KDC should have absolutely no other services running on it and should be physically secure. The danger is high because Kerberos stores all passwords encrypted with the same master key which is stored as a file on the KDC.
A compromised master key is not quite as bad as one might fear. The master key is only used to encrypt the Kerberos database and as a seed for the random number generator. As long as access to the KDC is secure, an attacker cannot do much with the master key.
If the KDC is unavailable, network services are unusable as authentication cannot be performed. This can be alleviated with a single master KDC and one or more slaves, and with careful implementation of secondary or fall-back authentication using PAM.
Kerberos allows users, hosts
and services to authenticate between themselves. It does not
have a mechanism to authenticate the
KDC to the users, hosts, or services. This
means that a trojanned kinit
could record
all user names and passwords. File system integrity checking
tools like security/tripwire can
alleviate this.
OpenSSL is an open source implementation of the SSL and TLS protocols. It provides an encryption transport layer on top of the normal communications layer, allowing it to be intertwined with many network applications and services.
The version of OpenSSL included in FreeBSD supports the Secure Sockets Layer 3.0 (SSLv3) and Transport Layer Security 1.0/1.1/1.2 (TLSv1/TLSv1.1/TLSv1.2) network security protocols and can be used as a general cryptographic library. In FreeBSD 12.0-RELEASE and above, OpenSSL also supports Transport Layer Security 1.3 (TLSv1.3).
OpenSSL is often used to encrypt
authentication of mail clients and to secure web based
transactions such as credit card payments. Some ports, such as
www/apache24 and
databases/postgresql11-server, include a
compile option for building with
OpenSSL. If selected, the port will
add support using OpenSSL from the
base system. To instead have the port compile against
OpenSSL from the
security/openssl port, add the following to
/etc/make.conf
:
DEFAULT_VERSIONS+= ssl=openssl
Another common use of OpenSSL is to provide certificates for use with software applications. Certificates can be used to verify the credentials of a company or individual. If a certificate has not been signed by an external Certificate Authority (CA), such as http://www.verisign.com, the application that uses the certificate will produce a warning. There is a cost associated with obtaining a signed certificate and using a signed certificate is not mandatory as certificates can be self-signed. However, using an external authority will prevent warnings and can put users at ease.
This section demonstrates how to create and use certificates on a FreeBSD system. Refer to Section 29.5.2, “Configuring an LDAP Server” for an example of how to create a CA for signing one's own certificates.
For more information about SSL, read the free OpenSSL Cookbook.
To generate a certificate that will be signed by an
external CA, issue the following command
and input the information requested at the prompts. This
input information will be written to the certificate. At the
Common Name
prompt, input the fully
qualified name for the system that will use the certificate.
If this name does not match the server, the application
verifying the certificate will issue a warning to the user,
rendering the verification provided by the certificate as
useless.
#
openssl req -new -nodes -out req.pem -keyout cert.key -sha256 -newkey rsa:2048
Generating a 2048 bit RSA private key ..................+++ .............................................................+++ writing new private key to 'cert.key' ----- You are about to be asked to enter information that will be incorporated into your certificate request. What you are about to enter is what is called a Distinguished Name or a DN. There are quite a few fields but you can leave some blank For some fields there will be a default value, If you enter '.', the field will be left blank. ----- Country Name (2 letter code) [AU]:State or Province Name (full name) [Some-State]:
US
Locality Name (eg, city) []:
PA
Organization Name (eg, company) [Internet Widgits Pty Ltd]:
Pittsburgh
Organizational Unit Name (eg, section) []:
My Company
Common Name (eg, YOUR name) []:
Systems Administrator
Email Address []:
localhost.example.org
Please enter the following 'extra' attributes to be sent with your certificate request A challenge password []: An optional company name []:
trhodes@FreeBSD.org
Another Name
Other options, such as the expire time and alternate encryption algorithms, are available when creating a certificate. A complete list of options is described in openssl(1).
This command will create two files in the current
directory. The certificate request,
req.pem
, can be sent to a
CA who will validate the entered
credentials, sign the request, and return the signed
certificate. The second file,
cert.key
, is the private key for the
certificate and should be stored in a secure location. If
this falls in the hands of others, it can be used to
impersonate the user or the server.
Alternately, if a signature from a CA is not required, a self-signed certificate can be created. First, generate the RSA key:
#
openssl genrsa -rand -genkey -out cert.key 2048
0 semi-random bytes loaded Generating RSA private key, 2048 bit long modulus .............................................+++ .................................................................................................................+++ e is 65537 (0x10001)
Use this key to create a self-signed certificate. Follow the usual prompts for creating a certificate:
#
openssl req -new -x509 -days 365 -key cert.key -out cert.crt -sha256
You are about to be asked to enter information that will be incorporated into your certificate request. What you are about to enter is what is called a Distinguished Name or a DN. There are quite a few fields but you can leave some blank For some fields there will be a default value, If you enter '.', the field will be left blank. ----- Country Name (2 letter code) [AU]:State or Province Name (full name) [Some-State]:
US
Locality Name (eg, city) []:
PA
Organization Name (eg, company) [Internet Widgits Pty Ltd]:
Pittsburgh
Organizational Unit Name (eg, section) []:
My Company
Common Name (e.g. server FQDN or YOUR name) []:
Systems Administrator
Email Address []:
localhost.example.org
trhodes@FreeBSD.org
This will create two new files in the current directory: a
private key file
cert.key
, and the certificate itself,
cert.crt
. These should be placed in a
directory, preferably under /etc/ssl/
,
which is readable only by root
. Permissions of
0700
are appropriate for these files and
can be set using chmod
.
One use for a certificate is to encrypt connections to the Sendmail mail server in order to prevent the use of clear text authentication.
Some mail clients will display an error if the user has not installed a local copy of the certificate. Refer to the documentation included with the software for more information on certificate installation.
In FreeBSD 10.0-RELEASE and above, it is possible to create a
self-signed certificate for
Sendmail automatically. To enable
this, add the following lines to
/etc/rc.conf
:
sendmail_enable="YES"
sendmail_cert_create="YES"
sendmail_cert_cn="localhost.example.org
"
This will automatically create a self-signed certificate,
/etc/mail/certs/host.cert
, a signing key,
/etc/mail/certs/host.key
, and a
CA certificate,
/etc/mail/certs/cacert.pem
. The
certificate will use the Common Name
specified in sendmail_cert_cn
. After saving
the edits, restart Sendmail:
#
service sendmail restart
If all went well, there will be no error messages in
/var/log/maillog
. For a simple test,
connect to the mail server's listening port using
telnet
:
#
telnet
Trying 192.0.34.166... Connected to example.com. Escape character is '^]'. 220 example.com ESMTP Sendmail 8.14.7/8.14.7; Fri, 18 Apr 2014 11:50:32 -0400 (EDT)example.com
25ehlo
250-example.com Hello example.com [192.0.34.166], pleased to meet you 250-ENHANCEDSTATUSCODES 250-PIPELINING 250-8BITMIME 250-SIZE 250-DSN 250-ETRN 250-AUTH LOGIN PLAIN 250-STARTTLS 250-DELIVERBY 250 HELPexample.com
quit
221 2.0.0 example.com closing connection Connection closed by foreign host.
If the STARTTLS
line appears in the
output, everything is working correctly.
Internet Protocol Security (IPsec) is a set of protocols which sit on top of the Internet Protocol (IP) layer. It allows two or more hosts to communicate in a secure manner by authenticating and encrypting each IP packet of a communication session. The FreeBSD IPsec network stack is based on the http://www.kame.net/ implementation and supports both IPv4 and IPv6 sessions.
IPsec is comprised of the following sub-protocols:
Encapsulated Security Payload (ESP): this protocol protects the IP packet data from third party interference by encrypting the contents using symmetric cryptography algorithms such as Blowfish and 3DES.
Authentication Header (AH): this protocol protects the IP packet header from third party interference and spoofing by computing a cryptographic checksum and hashing the IP packet header fields with a secure hashing function. This is then followed by an additional header that contains the hash, to allow the information in the packet to be authenticated.
IP Payload Compression Protocol (IPComp): this protocol tries to increase communication performance by compressing the IP payload in order to reduce the amount of data sent.
These protocols can either be used together or separately, depending on the environment.
IPsec supports two modes of operation. The first mode, Transport Mode, protects communications between two hosts. The second mode, Tunnel Mode, is used to build virtual tunnels, commonly known as Virtual Private Networks (VPNs). Consult ipsec(4) for detailed information on the IPsec subsystem in FreeBSD.
IPsec support is enabled by default on FreeBSD 11 and later. For previous versions of FreeBSD, add these options to a custom kernel configuration file and rebuild the kernel using the instructions in Chapter 8, Configuring the FreeBSD Kernel:
options IPSEC #IP security device crypto
If IPsec debugging support is desired, the following kernel option should also be added:
options IPSEC_DEBUG #debug for IP security
This rest of this chapter demonstrates the process of setting up an IPsec VPN between a home network and a corporate network. In the example scenario:
Both sites are connected to the Internet through a gateway that is running FreeBSD.
The gateway on each network has at least one external
IP address. In this example, the
corporate LAN's external
IP address is 172.16.5.4
and the home
LAN's external IP
address is 192.168.1.12
.
The internal addresses of the two networks can be either
public or private IP addresses. However,
the address space must not collide. For example, both
networks cannot use 192.168.1.x
. In this
example, the corporate LAN's internal
IP address is 10.246.38.1
and the home
LAN's internal IP
address is 10.0.0.5
.
To begin, security/ipsec-tools must be installed from the Ports Collection. This software provides a number of applications which support the configuration.
The next requirement is to create two gif(4)
pseudo-devices which will be used to tunnel packets and allow
both networks to communicate properly. As root
, run the following
commands, replacing internal
and
external
with the real IP
addresses of the internal and external interfaces of the two
gateways:
#
ifconfig gif0 create
#
ifconfig gif0
internal1 internal2
#
ifconfig gif0 tunnel
external1 external2
Verify the setup on each gateway, using
ifconfig
. Here is the output from Gateway
1:
gif0: flags=8051 mtu 1280 tunnel inet 172.16.5.4 --> 192.168.1.12 inet6 fe80::2e0:81ff:fe02:5881%gif0 prefixlen 64 scopeid 0x6 inet 10.246.38.1 --> 10.0.0.5 netmask 0xffffff00
Here is the output from Gateway 2:
gif0: flags=8051 mtu 1280 tunnel inet 192.168.1.12 --> 172.16.5.4 inet 10.0.0.5 --> 10.246.38.1 netmask 0xffffff00 inet6 fe80::250:bfff:fe3a:c1f%gif0 prefixlen 64 scopeid 0x4
Once complete, both internal IP addresses should be reachable using ping(8):
priv-net# ping 10.0.0.5 PING 10.0.0.5 (10.0.0.5): 56 data bytes 64 bytes from 10.0.0.5: icmp_seq=0 ttl=64 time=42.786 ms 64 bytes from 10.0.0.5: icmp_seq=1 ttl=64 time=19.255 ms 64 bytes from 10.0.0.5: icmp_seq=2 ttl=64 time=20.440 ms 64 bytes from 10.0.0.5: icmp_seq=3 ttl=64 time=21.036 ms --- 10.0.0.5 ping statistics --- 4 packets transmitted, 4 packets received, 0% packet loss round-trip min/avg/max/stddev = 19.255/25.879/42.786/9.782 ms corp-net# ping 10.246.38.1 PING 10.246.38.1 (10.246.38.1): 56 data bytes 64 bytes from 10.246.38.1: icmp_seq=0 ttl=64 time=28.106 ms 64 bytes from 10.246.38.1: icmp_seq=1 ttl=64 time=42.917 ms 64 bytes from 10.246.38.1: icmp_seq=2 ttl=64 time=127.525 ms 64 bytes from 10.246.38.1: icmp_seq=3 ttl=64 time=119.896 ms 64 bytes from 10.246.38.1: icmp_seq=4 ttl=64 time=154.524 ms --- 10.246.38.1 ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max/stddev = 28.106/94.594/154.524/49.814 ms
As expected, both sides have the ability to send and receive ICMP packets from the privately configured addresses. Next, both gateways must be told how to route packets in order to correctly send traffic from either network. The following commands will achieve this goal:
corp-net#
route add
corp-net10.0.0.0 10.0.0.5 255.255.255.0
#
route add net
priv-net10.0.0.0: gateway 10.0.0.5
#
route add
priv-net10.246.38.0 10.246.38.1 255.255.255.0
#
route add host
10.246.38.0: gateway 10.246.38.1
At this point, internal machines should be reachable from each gateway as well as from machines behind the gateways. Again, use ping(8) to confirm:
corp-net# ping 10.0.0.8 PING 10.0.0.8 (10.0.0.8): 56 data bytes 64 bytes from 10.0.0.8: icmp_seq=0 ttl=63 time=92.391 ms 64 bytes from 10.0.0.8: icmp_seq=1 ttl=63 time=21.870 ms 64 bytes from 10.0.0.8: icmp_seq=2 ttl=63 time=198.022 ms 64 bytes from 10.0.0.8: icmp_seq=3 ttl=63 time=22.241 ms 64 bytes from 10.0.0.8: icmp_seq=4 ttl=63 time=174.705 ms --- 10.0.0.8 ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max/stddev = 21.870/101.846/198.022/74.001 ms priv-net# ping 10.246.38.107 PING 10.246.38.1 (10.246.38.107): 56 data bytes 64 bytes from 10.246.38.107: icmp_seq=0 ttl=64 time=53.491 ms 64 bytes from 10.246.38.107: icmp_seq=1 ttl=64 time=23.395 ms 64 bytes from 10.246.38.107: icmp_seq=2 ttl=64 time=23.865 ms 64 bytes from 10.246.38.107: icmp_seq=3 ttl=64 time=21.145 ms 64 bytes from 10.246.38.107: icmp_seq=4 ttl=64 time=36.708 ms --- 10.246.38.107 ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max/stddev = 21.145/31.721/53.491/12.179 ms
Setting up the tunnels is the easy part. Configuring a
secure link is a more in depth process. The following
configuration uses pre-shared (PSK)
RSA keys. Other than the
IP addresses, the
/usr/local/etc/racoon/racoon.conf
on both
gateways will be identical and look similar to:
path pre_shared_key "/usr/local/etc/racoon/psk.txt"; #location of pre-shared key file log debug; #log verbosity setting: set to 'notify' when testing and debugging is complete padding # options are not to be changed { maximum_length 20; randomize off; strict_check off; exclusive_tail off; } timer # timing options. change as needed { counter 5; interval 20 sec; persend 1; # natt_keepalive 15 sec; phase1 30 sec; phase2 15 sec; } listen # address [port] that racoon will listen on { isakmp 172.16.5.4 [500]; isakmp_natt 172.16.5.4 [4500]; } remote 192.168.1.12 [500] { exchange_mode main,aggressive; doi ipsec_doi; situation identity_only; my_identifier address 172.16.5.4; peers_identifier address 192.168.1.12; lifetime time 8 hour; passive off; proposal_check obey; # nat_traversal off; generate_policy off; proposal { encryption_algorithm blowfish; hash_algorithm md5; authentication_method pre_shared_key; lifetime time 30 sec; dh_group 1; } } sainfo (address 10.246.38.0/24 any address 10.0.0.0/24 any) # address $network/$netmask $type address $network/$netmask $type ( $type being any or esp) { # $network must be the two internal networks you are joining. pfs_group 1; lifetime time 36000 sec; encryption_algorithm blowfish,3des; authentication_algorithm hmac_md5,hmac_sha1; compression_algorithm deflate; }
For descriptions of each available option, refer to the
manual page for racoon.conf
.
The Security Policy Database (SPD) needs to be configured so that FreeBSD and racoon are able to encrypt and decrypt network traffic between the hosts.
This can be achieved with a shell script, similar to the
following, on the corporate gateway. This file will be used
during system initialization and should be saved as
/usr/local/etc/racoon/setkey.conf
.
flush; spdflush; # To the home network spdadd 10.246.38.0/24 10.0.0.0/24 any -P out ipsec esp/tunnel/172.16.5.4-192.168.1.12/use; spdadd 10.0.0.0/24 10.246.38.0/24 any -P in ipsec esp/tunnel/192.168.1.12-172.16.5.4/use;
Once in place, racoon may be started on both gateways using the following command:
#
/usr/local/sbin/racoon -F -f /usr/local/etc/racoon/racoon.conf -l /var/log/racoon.log
The output should be similar to the following:
corp-net# /usr/local/sbin/racoon -F -f /usr/local/etc/racoon/racoon.conf Foreground mode. 2006-01-30 01:35:47: INFO: begin Identity Protection mode. 2006-01-30 01:35:48: INFO: received Vendor ID: KAME/racoon 2006-01-30 01:35:55: INFO: received Vendor ID: KAME/racoon 2006-01-30 01:36:04: INFO: ISAKMP-SA established 172.16.5.4[500]-192.168.1.12[500] spi:623b9b3bd2492452:7deab82d54ff704a 2006-01-30 01:36:05: INFO: initiate new phase 2 negotiation: 172.16.5.4[0]192.168.1.12[0] 2006-01-30 01:36:09: INFO: IPsec-SA established: ESP/Tunnel 192.168.1.12[0]->172.16.5.4[0] spi=28496098(0x1b2d0e2) 2006-01-30 01:36:09: INFO: IPsec-SA established: ESP/Tunnel 172.16.5.4[0]->192.168.1.12[0] spi=47784998(0x2d92426) 2006-01-30 01:36:13: INFO: respond new phase 2 negotiation: 172.16.5.4[0]192.168.1.12[0] 2006-01-30 01:36:18: INFO: IPsec-SA established: ESP/Tunnel 192.168.1.12[0]->172.16.5.4[0] spi=124397467(0x76a279b) 2006-01-30 01:36:18: INFO: IPsec-SA established: ESP/Tunnel 172.16.5.4[0]->192.168.1.12[0] spi=175852902(0xa7b4d66)
To ensure the tunnel is working properly, switch to
another console and use tcpdump(1) to view network
traffic using the following command. Replace
em0
with the network interface card as
required:
#
tcpdump -i em0 host
172.16.5.4 and dst 192.168.1.12
Data similar to the following should appear on the console. If not, there is an issue and debugging the returned data will be required.
01:47:32.021683 IP corporatenetwork.com > 192.168.1.12.privatenetwork.com: ESP(spi=0x02acbf9f,seq=0xa) 01:47:33.022442 IP corporatenetwork.com > 192.168.1.12.privatenetwork.com: ESP(spi=0x02acbf9f,seq=0xb) 01:47:34.024218 IP corporatenetwork.com > 192.168.1.12.privatenetwork.com: ESP(spi=0x02acbf9f,seq=0xc)
At this point, both networks should be available and seem to be part of the same network. Most likely both networks are protected by a firewall. To allow traffic to flow between them, rules need to be added to pass packets. For the ipfw(8) firewall, add the following lines to the firewall configuration file:
ipfw add 00201 allow log esp from any to any ipfw add 00202 allow log ah from any to any ipfw add 00203 allow log ipencap from any to any ipfw add 00204 allow log udp from any 500 to any
The rule numbers may need to be altered depending on the current host configuration.
For users of pf(4) or ipf(8), the following rules should do the trick:
pass in quick proto esp from any to any pass in quick proto ah from any to any pass in quick proto ipencap from any to any pass in quick proto udp from any port = 500 to any port = 500 pass in quick on gif0 from any to any pass out quick proto esp from any to any pass out quick proto ah from any to any pass out quick proto ipencap from any to any pass out quick proto udp from any port = 500 to any port = 500 pass out quick on gif0 from any to any
Finally, to allow the machine to start support for the
VPN during system initialization, add the
following lines to /etc/rc.conf
:
ipsec_enable="YES" ipsec_program="/usr/local/sbin/setkey" ipsec_file="/usr/local/etc/racoon/setkey.conf" # allows setting up spd policies on boot racoon_enable="yes"
OpenSSH is a set of network connectivity tools used to provide secure access to remote machines. Additionally, TCP/IP connections can be tunneled or forwarded securely through SSH connections. OpenSSH encrypts all traffic to effectively eliminate eavesdropping, connection hijacking, and other network-level attacks.
OpenSSH is maintained by the OpenBSD project and is installed by default in FreeBSD. It is compatible with both SSH version 1 and 2 protocols.
When data is sent over the network in an unencrypted form, network sniffers anywhere in between the client and server can steal user/password information or data transferred during the session. OpenSSH offers a variety of authentication and encryption methods to prevent this from happening. More information about OpenSSH is available from http://www.openssh.com/.
This section provides an overview of the built-in client utilities to securely access other systems and securely transfer files from a FreeBSD system. It then describes how to configure a SSH server on a FreeBSD system. More information is available in the man pages mentioned in this chapter.
To log into a SSH server, use
ssh
and specify a username that exists on
that server and the IP address or hostname
of the server. If this is the first time a connection has
been made to the specified server, the user will be prompted
to first verify the server's fingerprint:
#
ssh
The authenticity of host 'example.com (10.0.0.1)' can't be established. ECDSA key fingerprint is 25:cc:73:b5:b3:96:75:3d:56:19:49:d2:5c:1f:91:3b. Are you sure you want to continue connecting (yes/no)?user@example.com
yes
Permanently added 'example.com' (ECDSA) to the list of known hosts. Password for user@example.com:
user_password
SSH utilizes a key fingerprint system
to verify the authenticity of the server when the client
connects. When the user accepts the key's fingerprint by
typing yes
when connecting for the first
time, a copy of the key is saved to
.ssh/known_hosts
in the user's home
directory. Future attempts to login are verified against the
saved key and ssh
will display an alert if
the server's key does not match the saved key. If this
occurs, the user should first verify why the key has changed
before continuing with the connection.
By default, recent versions of
OpenSSH only accept
SSHv2 connections. By default, the client
will use version 2 if possible and will fall back to version 1
if the server does not support version 2. To force
ssh
to only use the specified protocol,
include -1
or -2
.
Additional options are described in ssh(1).
Use scp(1) to securely copy a file to or from a
remote machine. This example copies
COPYRIGHT
on the remote system to a file
of the same name in the current directory of the local
system:
#
scp
Password for user@example.com:user@example.com:/COPYRIGHT COPYRIGHT
COPYRIGHT 100% |*****************************| 4735 00:00
*******
#
Since the fingerprint was already verified for this host, the server's key is automatically checked before prompting for the user's password.
The arguments passed to scp
are similar
to cp
. The file or files to copy is the
first argument and the destination to copy to is the second.
Since the file is fetched over the network, one or more of the
file arguments takes the form
user@host:<path_to_remote_file>
. Be
aware when copying directories recursively that
scp
uses -r
, whereas
cp
uses -R
.
To open an interactive session for copying files, use
sftp
. Refer to sftp(1) for a list of
available commands while in an sftp
session.
Instead of using passwords, a client can be configured
to connect to the remote machine using keys. To generate
RSA
authentication keys, use ssh-keygen
. To
generate a public and private key pair, specify the type of
key and follow the prompts. It is recommended to protect
the keys with a memorable, but hard to guess
passphrase.
%
ssh-keygen -t rsa
Generating public/private rsa key pair. Enter file in which to save the key (/home/user/.ssh/id_rsa): Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /home/user/.ssh/id_rsa. Your public key has been saved in /home/user/.ssh/id_rsa.pub. The key fingerprint is: SHA256:54Xm9Uvtv6H4NOo6yjP/YCfODryvUU7yWHzMqeXwhq8 user@host.example.com The key's randomart image is: +---[RSA 2048]----+ | | | | | | | . o.. | | .S*+*o | | . O=Oo . . | | = Oo= oo..| | .oB.* +.oo.| | =OE**.o..=| +----[SHA256]-----+
The private key
is stored in ~/.ssh/id_rsa
and the public key
is stored in ~/.ssh/id_rsa.pub
.
The
public key must be copied to
~/.ssh/authorized_keys
on the remote
machine for key-based authentication to
work.
Many users believe that keys are secure by design and
will use a key without a passphrase. This is
dangerous behavior. An
administrator can verify that a key pair is protected by a
passphrase by viewing the private key manually. If the
private key file contains the word
ENCRYPTED
, the key owner is using a
passphrase. In addition, to better secure end users,
from
may be placed in the public key
file. For example, adding
from="192.168.10.5"
in front of the
ssh-rsa
prefix will only allow that specific user to log in from
that IP address.
The options and files vary with different versions of OpenSSH. To avoid problems, consult ssh-keygen(1).
If a passphrase is used, the user is prompted for the passphrase each time a connection is made to the server. To load SSH keys into memory and remove the need to type the passphrase each time, use ssh-agent(1) and ssh-add(1).
Authentication is handled by
ssh-agent
, using the private keys that
are loaded into it. ssh-agent
can be used to launch another application like a
shell or a window manager.
To use ssh-agent
in a shell, start it
with a shell as an argument. Add the identity by
running ssh-add
and entering the
passphrase for the private key.
The user will then be able to ssh
to any host that has the corresponding public key installed.
For example:
%
ssh-agent
csh
%
ssh-add
Enter passphrase for key '/usr/home/user/.ssh/id_rsa': Identity added: /usr/home/user/.ssh/id_rsa (/usr/home/user/.ssh/id_rsa)%
To use ssh-agent
in
Xorg, add an entry for it in
~/.xinitrc
. This provides the
ssh-agent
services to all programs
launched in Xorg. An example
~/.xinitrc
might look like this:
exec ssh-agent startxfce4
This launches ssh-agent
, which in
turn launches XFCE, every time
Xorg starts. Once
Xorg has been restarted so that
the changes can take effect, run ssh-add
to load all of the SSH keys.
OpenSSH has the ability to create a tunnel to encapsulate another protocol in an encrypted session.
The following command tells ssh
to
create a tunnel for
telnet:
%
ssh -2 -N -f -L
5023:localhost:23 user@foo.example.com
%
This example uses the following options:
-2
Forces ssh
to use version 2 to
connect to the server.
-N
Indicates no command, or tunnel only. If omitted,
ssh
initiates a normal
session.
-f
Forces ssh
to run in the
background.
-L
Indicates a local tunnel in
localport:remotehost:remoteport
format.
user@foo.example.com
The login name to use on the specified remote SSH server.
An SSH tunnel works by creating a
listen socket on localhost
on the
specified localport
. It then forwards
any connections received on localport
via
the SSH connection to the specified
remotehost:remoteport
. In the example,
port 5023
on the client is forwarded to
port 23
on the remote machine. Since
port 23 is used by telnet, this
creates an encrypted telnet
session through an SSH tunnel.
This method can be used to wrap any number of insecure TCP protocols such as SMTP, POP3, and FTP, as seen in the following examples.
%
ssh -2 -N -f -L
user@mailserver.example.com's password:5025:localhost:25 user@mailserver.example.com
*****
%
telnet localhost 5025
Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. 220 mailserver.example.com ESMTP
This can be used in conjunction with
ssh-keygen
and additional user accounts
to create a more seamless SSH tunneling
environment. Keys can be used in place of typing a
password, and the tunnels can be run as a separate
user.
In this example, there is an SSH server that accepts connections from the outside. On the same network resides a mail server running a POP3 server. To check email in a secure manner, create an SSH connection to the SSH server and tunnel through to the mail server:
%
ssh -2 -N -f -L
user@ssh-server.example.com's password:2110:mail.example.com:110 user@ssh-server.example.com
******
Once the tunnel is up and running, point the email
client to send POP3 requests to
localhost
on port 2110. This
connection will be forwarded securely across the tunnel to
mail.example.com
.
Some firewalls filter both incoming and outgoing connections. For example, a firewall might limit access from remote machines to ports 22 and 80 to only allow SSH and web surfing. This prevents access to any other service which uses a port other than 22 or 80.
The solution is to create an SSH connection to a machine outside of the network's firewall and use it to tunnel to the desired service:
%
ssh -2 -N -f -L
user@unfirewalled-system.example.org's password:8888:music.example.com:8000 user@unfirewalled-system.example.org
*******
In this example, a streaming Ogg Vorbis client can now
be pointed to localhost
port
8888, which will be forwarded over to
music.example.com
on port 8000,
successfully bypassing the firewall.
In addition to providing built-in SSH client utilities, a FreeBSD system can be configured as an SSH server, accepting connections from other SSH clients.
To see if sshd is operating, use the service(8) command:
#
service sshd status
If the service is not running, add the following line to
/etc/rc.conf
.
sshd_enable="YES"
This will start sshd, the daemon program for OpenSSH, the next time the system boots. To start it now:
#
service sshd start
The first time sshd starts on a FreeBSD system, the system's host keys will be automatically created and the fingerprint will be displayed on the console. Provide users with the fingerprint so that they can verify it the first time they connect to the server.
Refer to sshd(8) for the list of available options when starting sshd and a more complete discussion about authentication, the login process, and the various configuration files.
At this point, the sshd should be available to all users with a username and password on the system.
While sshd is the most widely used remote administration facility for FreeBSD, brute force and drive by attacks are common to any system exposed to public networks. Several additional parameters are available to prevent the success of these attacks and will be described in this section.
It is a good idea to limit which users can log into the
SSH server and from where using the
AllowUsers
keyword in the
OpenSSH server configuration file.
For example, to only allow root
to log in from
192.168.1.32
, add
this line to /etc/ssh/sshd_config
:
AllowUsers root@192.168.1.32
To allow admin
to log in from anywhere, list that user without specifying an
IP address:
AllowUsers admin
Multiple users should be listed on the same line, like so:
AllowUsers root@192.168.1.32 admin
After making changes to
/etc/ssh/sshd_config
,
tell sshd to reload its
configuration file by running:
#
service sshd reload
When this keyword is used, it is important to list each user that needs to log into this machine. Any user that is not specified in that line will be locked out. Also, the keywords used in the OpenSSH server configuration file are case-sensitive. If the keyword is not spelled correctly, including its case, it will be ignored. Always test changes to this file to make sure that the edits are working as expected. Refer to sshd_config(5) to verify the spelling and use of the available keywords.
In addition, users may be forced to use two factor
authentication via the use of a public and private key. When
required, the user may generate a key pair through the use
of ssh-keygen(1) and send the administrator the public
key. This key file will be placed in the
authorized_keys
as described above in
the client section. To force the users to use keys only,
the following option may be configured:
AuthenticationMethods publickey
Do not confuse /etc/ssh/sshd_config
with /etc/ssh/ssh_config
(note the
extra d
in the first filename). The
first file configures the server and the second file
configures the client. Refer to ssh_config(5) for a
listing of the available client settings.
Access Control Lists (ACLs) extend the standard UNIX® permission model in a POSIX®.1e compatible way. This permits an administrator to take advantage of a more fine-grained permissions model.
The FreeBSD GENERIC
kernel provides
ACL support for UFS file
systems. Users who prefer to compile a custom kernel must
include the following option in their custom kernel
configuration file:
options UFS_ACL
If this option is not compiled in, a warning message will be displayed when attempting to mount a file system with ACL support. ACLs rely on extended attributes which are natively supported in UFS2.
This chapter describes how to enable ACL support and provides some usage examples.
ACLs are enabled by the mount-time
administrative flag, acls
, which may be added
to /etc/fstab
. The mount-time flag can
also be automatically set in a persistent manner using
tunefs(8) to modify a superblock ACLs
flag in the file system header. In general, it is preferred
to use the superblock flag for several reasons:
The superblock flag cannot be changed by a remount
using mount -u
as it requires a complete
umount
and fresh
mount
. This means that
ACLs cannot be enabled on the root file
system after boot. It also means that
ACL support on a file system cannot be
changed while the system is in use.
Setting the superblock flag causes the file system to
always be mounted with ACLs enabled,
even if there is not an fstab
entry
or if the devices re-order. This prevents accidental
mounting of the file system without ACL
support.
It is desirable to discourage accidental mounting without ACLs enabled because nasty things can happen if ACLs are enabled, then disabled, then re-enabled without flushing the extended attributes. In general, once ACLs are enabled on a file system, they should not be disabled, as the resulting file protections may not be compatible with those intended by the users of the system, and re-enabling ACLs may re-attach the previous ACLs to files that have since had their permissions changed, resulting in unpredictable behavior.
File systems with ACLs enabled will
show a plus (+
) sign in their permission
settings:
drwx------ 2 robert robert 512 Dec 27 11:54 private drwxrwx---+ 2 robert robert 512 Dec 23 10:57 directory1 drwxrwx---+ 2 robert robert 512 Dec 22 10:20 directory2 drwxrwx---+ 2 robert robert 512 Dec 27 11:57 directory3 drwxr-xr-x 2 robert robert 512 Nov 10 11:54 public_html
In this example, directory1
,
directory2
, and
directory3
are all taking advantage of
ACLs, whereas
public_html
is not.
File system ACLs can be viewed using
getfacl
. For instance, to view the
ACL settings on
test
:
%
getfacl test
#file:test #owner:1001 #group:1001 user::rw- group::r-- other::r--
To change the ACL settings on this
file, use setfacl
. To remove all of the
currently defined ACLs from a file or file
system, include -k
. However, the preferred
method is to use -b
as it leaves the basic
fields required for ACLs to work.
%
setfacl -k test
To modify the default ACL entries, use
-m
:
%
setfacl -m u:trhodes:rwx,group:web:r--,o::--- test
In this example, there were no pre-defined entries, as they were removed by the previous command. This command restores the default options and assigns the options listed. If a user or group is added which does not exist on the system, an Invalid argument error will be displayed.
Refer to getfacl(1) and setfacl(1) for more information about the options available for these commands.
In recent years, the security world has made many improvements to how vulnerability assessment is handled. The threat of system intrusion increases as third party utilities are installed and configured for virtually any operating system available today.
Vulnerability assessment is a key factor in security. While FreeBSD releases advisories for the base system, doing so for every third party utility is beyond the FreeBSD Project's capability. There is a way to mitigate third party vulnerabilities and warn administrators of known security issues. A FreeBSD add on utility known as pkg includes options explicitly for this purpose.
pkg polls a database for security issues. The database is updated and maintained by the FreeBSD Security Team and ports developers.
Please refer to instructions for installing pkg.
Installation provides periodic(8) configuration files
for maintaining the pkg audit
database, and provides a programmatic method of keeping it
updated. This functionality is enabled if
daily_status_security_pkgaudit_enable
is set to YES
in periodic.conf(5).
Ensure that daily security run emails, which are sent to
root
's email account,
are being read.
After installation, and to audit third party utilities as part of the Ports Collection at any time, an administrator may choose to update the database and view known vulnerabilities of installed packages by invoking:
#
pkg audit -F
pkg displays messages any published vulnerabilities in installed packages:
Affected package: cups-base-1.1.22.0_1 Type of problem: cups-base -- HPGL buffer overflow vulnerability. Reference: <https://www.FreeBSD.org/ports/portaudit/40a3bca2-6809-11d9-a9e7-0001020eed82.html> 1 problem(s) in your installed packages found. You are advised to update or deinstall the affected package(s) immediately.
By pointing a web browser to the displayed URL, an administrator may obtain more information about the vulnerability. This will include the versions affected, by FreeBSD port version, along with other web sites which may contain security advisories.
pkg is a powerful utility and is extremely useful when coupled with ports-mgmt/portmaster.
Like many producers of quality operating systems, the FreeBSD Project has a security team which is responsible for determining the End-of-Life (EoL) date for each FreeBSD release and to provide security updates for supported releases which have not yet reached their EoL. More information about the FreeBSD security team and the supported releases is available on the FreeBSD security page.
One task of the security team is to respond to reported security vulnerabilities in the FreeBSD operating system. Once a vulnerability is confirmed, the security team verifies the steps necessary to fix the vulnerability and updates the source code with the fix. It then publishes the details as a “Security Advisory”. Security advisories are published on the FreeBSD website and mailed to the freebsd-security-notifications, freebsd-security, and freebsd-announce mailing lists.
This section describes the format of a FreeBSD security advisory.
Here is an example of a FreeBSD security advisory:
============================================================================= -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 ============================================================================= FreeBSD-SA-14:04.bind Security Advisory The FreeBSD Project Topic: BIND remote denial of service vulnerability Category: contrib Module: bind Announced: 2014-01-14 Credits: ISC Affects: FreeBSD 8.x and FreeBSD 9.x Corrected: 2014-01-14 19:38:37 UTC (stable/9, 9.2-STABLE) 2014-01-14 19:42:28 UTC (releng/9.2, 9.2-RELEASE-p3) 2014-01-14 19:42:28 UTC (releng/9.1, 9.1-RELEASE-p10) 2014-01-14 19:38:37 UTC (stable/8, 8.4-STABLE) 2014-01-14 19:42:28 UTC (releng/8.4, 8.4-RELEASE-p7) 2014-01-14 19:42:28 UTC (releng/8.3, 8.3-RELEASE-p14) CVE Name: CVE-2014-0591 For general information regarding FreeBSD Security Advisories, including descriptions of the fields above, security branches, and the following sections, please visit <URL:http://security.FreeBSD.org/>. I. Background BIND 9 is an implementation of the Domain Name System (DNS) protocols. The named(8) daemon is an Internet Domain Name Server. II. Problem Description Because of a defect in handling queries for NSEC3-signed zones, BIND can crash with an "INSIST" failure in name.c when processing queries possessing certain properties. This issue only affects authoritative nameservers with at least one NSEC3-signed zone. Recursive-only servers are not at risk. III. Impact An attacker who can send a specially crafted query could cause named(8) to crash, resulting in a denial of service. IV. Workaround No workaround is available, but systems not running authoritative DNS service with at least one NSEC3-signed zone using named(8) are not vulnerable. V. Solution Perform one of the following: 1) Upgrade your vulnerable system to a supported FreeBSD stable or release / security branch (releng) dated after the correction date. 2) To update your vulnerable system via a source code patch: The following patches have been verified to apply to the applicable FreeBSD release branches. a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility. [FreeBSD 8.3, 8.4, 9.1, 9.2-RELEASE and 8.4-STABLE] # fetch http://security.FreeBSD.org/patches/SA-14:04/bind-release.patch # fetch http://security.FreeBSD.org/patches/SA-14:04/bind-release.patch.asc # gpg --verify bind-release.patch.asc [FreeBSD 9.2-STABLE] # fetch http://security.FreeBSD.org/patches/SA-14:04/bind-stable-9.patch # fetch http://security.FreeBSD.org/patches/SA-14:04/bind-stable-9.patch.asc # gpg --verify bind-stable-9.patch.asc b) Execute the following commands as root: # cd /usr/src # patch < /path/to/patch Recompile the operating system using buildworld and installworld as described in <URL:https://www.FreeBSD.org/handbook/makeworld.html>. Restart the applicable daemons, or reboot the system. 3) To update your vulnerable system via a binary patch: Systems running a RELEASE version of FreeBSD on the i386 or amd64 platforms can be updated via the freebsd-update(8) utility: # freebsd-update fetch # freebsd-update install VI. Correction details The following list contains the correction revision numbers for each affected branch. Branch/path Revision - ------------------------------------------------------------------------- stable/8/ r260646 releng/8.3/ r260647 releng/8.4/ r260647 stable/9/ r260646 releng/9.1/ r260647 releng/9.2/ r260647 - ------------------------------------------------------------------------- To see which files were modified by a particular revision, run the following command, replacing NNNNNN with the revision number, on a machine with Subversion installed: # svn diff -cNNNNNN --summarize svn://svn.freebsd.org/base Or visit the following URL, replacing NNNNNN with the revision number: <URL:https://svnweb.freebsd.org/base?view=revision&revision=NNNNNN> VII. References <URL:https://kb.isc.org/article/AA-01078> <URL:http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-0591> The latest revision of this advisory is available at <URL:http://security.FreeBSD.org/advisories/FreeBSD-SA-14:04.bind.asc> -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJS1ZTYAAoJEO1n7NZdz2rnOvQP/2/68/s9Cu35PmqNtSZVVxVG ZSQP5EGWx/lramNf9566iKxOrLRMq/h3XWcC4goVd+gZFrvITJSVOWSa7ntDQ7TO XcinfRZ/iyiJbs/Rg2wLHc/t5oVSyeouyccqODYFbOwOlk35JjOTMUG1YcX+Zasg ax8RV+7Zt1QSBkMlOz/myBLXUjlTZ3Xg2FXVsfFQW5/g2CjuHpRSFx1bVNX6ysoG 9DT58EQcYxIS8WfkHRbbXKh9I1nSfZ7/Hky/kTafRdRMrjAgbqFgHkYTYsBZeav5 fYWKGQRJulYfeZQ90yMTvlpF42DjCC3uJYamJnwDIu8OhS1WRBI8fQfr9DRzmRua OK3BK9hUiScDZOJB6OqeVzUTfe7MAA4/UwrDtTYQ+PqAenv1PK8DZqwXyxA9ThHb zKO3OwuKOVHJnKvpOcr+eNwo7jbnHlis0oBksj/mrq2P9m2ueF9gzCiq5Ri5Syag Wssb1HUoMGwqU0roS8+pRpNC8YgsWpsttvUWSZ8u6Vj/FLeHpiV3mYXPVMaKRhVm 067BA2uj4Th1JKtGleox+Em0R7OFbCc/9aWC67wiqI6KRyit9pYiF3npph+7D5Eq 7zPsUdDd+qc+UTiLp3liCRp5w6484wWdhZO6wRtmUgxGjNkxFoNnX8CitzF8AaqO UWWemqWuz3lAZuORQ9KX =OQzQ -----END PGP SIGNATURE-----
Every security advisory uses the following format:
Each security advisory is signed by the PGP key of the Security Officer. The public key for the Security Officer can be verified at Appendix D, OpenPGP Keys.
The name of the security advisory always begins with
FreeBSD-SA-
(for FreeBSD Security
Advisory), followed by the year in two digit format
(14:
), followed by the advisory number
for that year (04.
), followed by the
name of the affected application or subsystem
(bind
). The advisory shown here is the
fourth advisory for 2014 and it affects
BIND.
The Topic
field summarizes the
vulnerability.
The Category
refers to the
affected part of the system which may be one of
core
, contrib
, or
ports
. The core
category means that the vulnerability affects a core
component of the FreeBSD operating system. The
contrib
category means that the
vulnerability affects software included with FreeBSD,
such as BIND. The
ports
category indicates that the
vulnerability affects software available through the Ports
Collection.
The Module
field refers to the
component location. In this example, the
bind
module is affected; therefore,
this vulnerability affects an application installed with
the operating system.
The Announced
field reflects the
date the security advisory was published. This means
that the security team has verified that the problem
exists and that a patch has been committed to the FreeBSD
source code repository.
The Credits
field gives credit to
the individual or organization who noticed the
vulnerability and reported it.
The Affects
field explains which
releases of FreeBSD are affected by this
vulnerability.
The Corrected
field indicates the
date, time, time offset, and releases that were
corrected. The section in parentheses shows each branch
for which the fix has been merged, and the version number
of the corresponding release from that branch. The
release identifier itself includes the version number
and, if appropriate, the patch level. The patch level is
the letter p
followed by a number,
indicating the sequence number of the patch, allowing
users to track which patches have already been applied to
the system.
The CVE Name
field lists the
advisory number, if one exists, in the public cve.mitre.org
security vulnerabilities database.
The Background
field provides a
description of the affected module.
The Problem Description
field
explains the vulnerability. This can include
information about the flawed code and how the utility
could be maliciously used.
The Impact
field describes what
type of impact the problem could have on a system.
The Workaround
field indicates if
a workaround is available to system administrators who
cannot immediately patch the system .
The Solution
field provides the
instructions for patching the affected system. This is a
step by step tested and verified method for getting a
system patched and working securely.
The Correction Details
field
displays each affected Subversion branch with the revision
number that contains the corrected code.
The References
field offers sources
of additional information regarding the
vulnerability.
Process accounting is a security method in which an administrator may keep track of system resources used and their allocation among users, provide for system monitoring, and minimally track a user's commands.
Process accounting has both positive and negative points. One of the positives is that an intrusion may be narrowed down to the point of entry. A negative is the amount of logs generated by process accounting, and the disk space they may require. This section walks an administrator through the basics of process accounting.
If more fine-grained accounting is needed, refer to Chapter 16, Security Event Auditing.
Before using process accounting, it must be enabled using the following commands:
#
sysrc accounting_enable=yes
#
service accounting start
The accounting information is stored in files located in
/var/account
, which is automatically created,
if necessary, the first time the accounting service starts.
These files contain sensitive information, including all the
commands issued by all users. Write access to the files is
limited to root
,
and read access is limited to root
and members of the
wheel
group.
To also prevent members of wheel
from reading the files,
change the mode of the /var/account
directory to allow access only by root
.
Once enabled, accounting will begin to track information
such as CPU statistics and executed
commands. All accounting logs are in a non-human readable
format which can be viewed using sa
. If
issued without any options, sa
prints
information relating to the number of per-user calls, the
total elapsed time in minutes, total CPU
and user time in minutes, and the average number of
I/O operations. Refer to sa(8) for
the list of available options which control the output.
To display the commands issued by users, use
lastcomm
. For example, this command
prints out all usage of ls
by trhodes
on the
ttyp1
terminal:
#
lastcomm ls trhodes ttyp1
Many other useful options exist and are explained in lastcomm(1), acct(5), and sa(8).
FreeBSD provides several methods for an administrator to limit the amount of system resources an individual may use. Disk quotas limit the amount of disk space available to users. Quotas are discussed in Section 17.11, “Disk Quotas”.
Limits to other resources, such as CPU
and memory, can be set using either a flat file or a command to
configure a resource limits database. The traditional method
defines login classes by editing
/etc/login.conf
. While this method is
still supported, any changes require a multi-step process of
editing this file, rebuilding the resource database, making
necessary changes to /etc/master.passwd
,
and rebuilding the password database. This can become time
consuming, depending upon the number of users to
configure.
rctl
can be used to provide a more
fine-grained method for controlling resource limits. This
command supports more than user limits as it can also be used to
set resource constraints on processes and jails.
This section demonstrates both methods for controlling resources, beginning with the traditional method.
In the traditional method, login classes and the resource
limits to apply to a login class are defined in
/etc/login.conf
. Each user account can
be assigned to a login class, where default
is the default login class. Each login class has a set of
login capabilities associated with it. A login capability is
a
pair, where name
=value
name
is a well-known
identifier and value
is an
arbitrary string which is processed accordingly depending on
the name
.
Whenever /etc/login.conf
is edited,
the /etc/login.conf.db
must be updated
by executing the following command:
#
cap_mkdb /etc/login.conf
Resource limits differ from the default login capabilities in two ways. First, for every limit, there is a soft and hard limit. A soft limit may be adjusted by the user or application, but may not be set higher than the hard limit. The hard limit may be lowered by the user, but can only be raised by the superuser. Second, most resource limits apply per process to a specific user.
Table 13.1, “Login Class Resource Limits” lists the most commonly used resource limits. All of the available resource limits and capabilities are described in detail in login.conf(5).
Resource Limit | Description |
---|---|
coredumpsize | The limit on the size of a core file generated by
a program is subordinate to other limits on disk
usage, such as filesize or disk
quotas. This limit is often used as a less severe
method of controlling disk space consumption. Since
users do not generate core files and often do not
delete them, this setting may save them from running
out of disk space should a large program
crash. |
cputime | The maximum amount of CPU time
a user's process may consume. Offending processes
will be killed by the kernel. This is a limit on
CPU time
consumed, not the percentage of the
CPU as displayed in some of the
fields generated by top and
ps . |
filesize | The maximum size of a file the user may own. Unlike disk quotas (Section 17.11, “Disk Quotas”), this limit is enforced on individual files, not the set of all files a user owns. |
maxproc | The maximum number of foreground and background
processes a user can run. This limit may not be
larger than the system limit specified by
kern.maxproc . Setting this limit
too small may hinder a user's productivity as some
tasks, such as compiling a large program, start lots
of processes. |
memorylocked | The maximum amount of memory a process may request to be locked into main memory using mlock(2). Some system-critical programs, such as amd(8), lock into main memory so that if the system begins to swap, they do not contribute to disk thrashing. |
memoryuse | The maximum amount of memory a process may consume at any given time. It includes both core memory and swap usage. This is not a catch-all limit for restricting memory consumption, but is a good start. |
openfiles | The maximum number of files a process may have
open. In FreeBSD, files are used to represent sockets
and IPC channels, so be careful not
to set this too low. The system-wide limit for this
is defined by
kern.maxfiles . |
sbsize | The limit on the amount of network memory a user may consume. This can be generally used to limit network communications. |
stacksize | The maximum size of a process stack. This alone is not sufficient to limit the amount of memory a program may use, so it should be used in conjunction with other limits. |
There are a few other things to remember when setting resource limits:
Processes started at system startup by
/etc/rc
are assigned to the
daemon
login class.
Although the default
/etc/login.conf
is a good source of
reasonable values for most limits, they may not be
appropriate for every system. Setting a limit too high
may open the system up to abuse, while setting it too low
may put a strain on productivity.
Xorg takes a lot of resources and encourages users to run more programs simultaneously.
Many limits apply to individual processes, not the
user as a whole. For example, setting
openfiles
to 50
means that each process the user runs may open up to
50
files. The total amount of files a
user may open is the value of openfiles
multiplied by the value of maxproc
.
This also applies to memory consumption.
For further information on resource limits and login classes and capabilities in general, refer to cap_mkdb(1), getrlimit(2), and login.conf(5).
The kern.racct.enable
tunable must be
set to a non-zero value. Custom kernels require specific
configuration:
options RACCT options RCTL
Once the system has rebooted into the new kernel,
rctl
may be used to set rules for the
system.
Rule syntax is controlled through the use of a subject, subject-id, resource, and action, as seen in this example rule:
user:trhodes:maxproc:deny=10/user
In this rule, the subject is user
, the
subject-id is trhodes
, the resource,
maxproc
, is the maximum number of
processes, and the action is deny
, which
blocks any new processes from being created. This means that
the user, trhodes
, will be constrained to
no greater than 10
processes. Other
possible actions include logging to the console, passing a
notification to devd(8), or sending a sigterm to the
process.
Some care must be taken when adding rules. Since this
user is constrained to 10
processes, this
example will prevent the user from performing other tasks
after logging in and executing a
screen
session. Once a resource limit has
been hit, an error will be printed, as in this example:
%
man test
/usr/bin/man: Cannot fork: Resource temporarily unavailable eval: Cannot fork: Resource temporarily unavailable
As another example, a jail can be prevented from exceeding a memory limit. This rule could be written as:
#
rctl -a jail:httpd:memoryuse:deny=2G/jail
Rules will persist across reboots if they have been added
to /etc/rctl.conf
. The format is a rule,
without the preceding command. For example, the previous rule
could be added as:
# Block jail from using more than 2G memory: jail:httpd:memoryuse:deny=2G/jail
To remove a rule, use rctl
to remove it
from the list:
#
rctl -r user:trhodes:maxproc:deny=10/user
A method for removing all rules is documented in rctl(8). However, if removing all rules for a single user is required, this command may be issued:
#
rctl -r user:trhodes
Many other resources exist which can be used to exert
additional control over various subjects
.
See rctl(8) to learn about them.
System administrators often need the ability to grant enhanced permissions to users so they may perform privileged tasks. The idea that team members are provided access to a FreeBSD system to perform their specific tasks opens up unique challenges to every administrator. These team members only need a subset of access beyond normal end user levels; however, they almost always tell management they are unable to perform their tasks without superuser access. Thankfully, there is no reason to provide such access to end users because tools exist to manage this exact requirement.
Up to this point, the security chapter has covered permitting access to authorized users and attempting to prevent unauthorized access. Another problem arises once authorized users have access to the system resources. In many cases, some users may need access to application startup scripts, or a team of administrators need to maintain the system. Traditionally, the standard users and groups, file permissions, and even the su(1) command would manage this access. And as applications required more access, as more users needed to use system resources, a better solution was required. The most used application is currently Sudo.
Sudo allows administrators to configure more rigid access to system commands and provide for some advanced logging features. As a tool, it is available from the Ports Collection as security/sudo or by use of the pkg(8) utility. To use the pkg(8) tool:
#
pkg install sudo
After the installation is complete, the installed
visudo
will open the configuration file with
a text editor. Using visudo
is highly
recommended as it comes with a built in syntax checker to verify
there are no errors before the file is saved.
The configuration file is made up of several small sections
which allow for extensive configuration. In the following
example, web application maintainer, user1, needs to start,
stop, and restart the web application known as
webservice
. To
grant this user permission to perform these tasks, add
this line to the end of
/usr/local/etc/sudoers
:
user1 ALL=(ALL) /usr/sbin/service webservice *
The user may now start webservice
using this command:
%
sudo /usr/sbin/service
webservice
start
While this configuration allows a single user access to the webservice service; however, in most organizations, there is an entire web team in charge of managing the service. A single line can also give access to an entire group. These steps will create a web group, add a user to this group, and allow all members of the group to manage the service:
#
pw groupadd -g 6001 -n webteam
Using the same pw(8) command, the user is added to the webteam group:
#
pw groupmod -m user1 -n webteam
Finally, this line in
/usr/local/etc/sudoers
allows any
member of the webteam group to manage
webservice
:
%webteam ALL=(ALL) /usr/sbin/service webservice *
Unlike su(1), Sudo only requires the end user password. This adds an advantage where users will not need shared passwords, a finding in most security audits and just bad all the way around.
Users permitted to run applications with
Sudo only enter their own passwords.
This is more secure and gives better control than su(1),
where the root
password is entered and the user acquires all
root
permissions.
Most organizations are moving or have moved toward a two
factor authentication model. In these cases, the user may not
have a password to enter. Sudo
provides for these cases with the NOPASSWD
variable. Adding it to the configuration above will allow all
members of the webteam
group to
manage the service without the password requirement:
%webteam ALL=(ALL) NOPASSWD: /usr/sbin/service webservice *
An advantage to implementing Sudo is the ability to enable session logging. Using the built in log mechanisms and the included sudoreplay command, all commands initiated through Sudo are logged for later verification. To enable this feature, add a default log directory entry, this example uses a user variable. Several other log filename conventions exist, consult the manual page for sudoreplay for additional information.
Defaults iolog_dir=/var/log/sudo-io/%{user}
This directory will be created automatically after the
logging is configured. It is best to let the system create
directory with default permissions just to be safe. In
addition, this entry will also log administrators who use
the sudoreplay command. To
change this behavior, read and uncomment the logging options
inside sudoers
.
Once this directive has been added to the
sudoers
file, any user configuration can
be updated with the request to log access. In the example
shown, the updated webteam
entry
would have the following additional changes:
%webteam ALL=(ALL) NOPASSWD: LOG_INPUT: LOG_OUTPUT: /usr/sbin/service webservice *
From this point on, all webteam
members altering the status of the
webservice
application
will be logged. The list of previous and current sessions
can be displayed with:
#
sudoreplay -l
In the output, to replay a specific session, search for
the TSID=
entry, and pass that to
sudoreplay with no other options to
replay the session at normal speed. For example:
#
sudoreplay user1/00/00/02
While sessions are logged, any administrator is able to remove sessions and leave only a question of why they had done so. It is worthwhile to add a daily check through an intrusion detection system (IDS) or similar software so that other administrators are alerted to manual alterations.
The sudoreplay
is extremely extendable.
Consult the documentation for more information.
Since system administration is a difficult task, many tools have been developed to make life easier for the administrator. These tools often enhance the way systems are installed, configured, and maintained. One of the tools which can be used to enhance the security of a FreeBSD system is jails. Jails have been available since FreeBSD 4.X and continue to be enhanced in their usefulness, performance, reliability, and security.
Jails build upon the chroot(2) concept, which is used to change the root directory of a set of processes. This creates a safe environment, separate from the rest of the system. Processes created in the chrooted environment can not access files or resources outside of it. For that reason, compromising a service running in a chrooted environment should not allow the attacker to compromise the entire system. However, a chroot has several limitations. It is suited to easy tasks which do not require much flexibility or complex, advanced features. Over time, many ways have been found to escape from a chrooted environment, making it a less than ideal solution for securing services.
Jails improve on the concept of the traditional chroot environment in several ways. In a traditional chroot environment, processes are only limited in the part of the file system they can access. The rest of the system resources, system users, running processes, and the networking subsystem are shared by the chrooted processes and the processes of the host system. Jails expand this model by virtualizing access to the file system, the set of users, and the networking subsystem. More fine-grained controls are available for tuning the access of a jailed environment. Jails can be considered as a type of operating system-level virtualization.
A jail is characterized by four elements:
A directory subtree: the starting point from which a jail is entered. Once inside the jail, a process is not permitted to escape outside of this subtree.
A hostname: which will be used by the jail.
An IP address: which is assigned to the jail. The IP address of a jail is often an alias address for an existing network interface.
A command: the path name of an executable to run inside the jail. The path is relative to the root directory of the jail environment.
Jails have their own set of users and their own root
account which are limited
to the jail environment. The root
account of a jail is not
allowed to perform operations to the system outside of the
associated jail environment.
This chapter provides an overview of the terminology and commands for managing FreeBSD jails. Jails are a powerful tool for both system administrators, and advanced users.
After reading this chapter, you will know:
What a jail is and what purpose it may serve in FreeBSD installations.
How to build, start, and stop a jail.
The basics of jail administration, both from inside and outside the jail.
Jails are a powerful tool, but they are not a security panacea. While it is not possible for a jailed process to break out on its own, there are several ways in which an unprivileged user outside the jail can cooperate with a privileged user inside the jail to obtain elevated privileges in the host environment.
Most of these attacks can be mitigated by ensuring that the jail root is not accessible to unprivileged users in the host environment. As a general rule, untrusted users with privileged access to a jail should not be given access to the host environment.
To facilitate better understanding of parts of the FreeBSD system related to jails, their internals and the way they interact with the rest of FreeBSD, the following terms are used further in this chapter:
Utility, which uses chroot(2) FreeBSD system call to change the root directory of a process and all its descendants.
The environment of processes running in a “chroot”. This includes resources such as the part of the file system which is visible, user and group IDs which are available, network interfaces and other IPC mechanisms, etc.
The system administration utility which allows launching of processes within a jail environment.
The controlling system of a jail environment. The host system has access to all the hardware resources available, and can control processes both outside of and inside a jail environment. One of the important differences of the host system from a jail is that the limitations which apply to superuser processes inside a jail are not enforced for processes of the host system.
A process, user or other entity, whose access to resources is restricted by a FreeBSD jail.
Some administrators divide jails into the following two types: “complete” jails, which resemble a real FreeBSD system, and “service” jails, dedicated to one application or service, possibly running with privileges. This is only a conceptual division and the process of building a jail is not affected by it. When creating a “complete” jail there are two options for the source of the userland: use prebuilt binaries (such as those supplied on an install media) or build from source.
To install the userland from installation media, first
create the root directory for the jail. This can be done by
setting the DESTDIR
variable to the proper
location.
Start a shell and define DESTDIR
:
#
sh
#
export DESTDIR=
/here/is/the/jail
Mount the install media as covered in mdconfig(8) when using the install ISO:
#
mount -t cd9660 /dev/`mdconfig -f cdimage.iso` /mnt
#
cd /mnt/usr/freebsd-dist/
Alternatively, download the tarballs from a mirror:
#
sh
#
export DESTRELEASE=
12.0-RELEASE
#
export DESTARCH=
`uname -m`
#
export SOURCEURL=
http://ftp.freebsd.org/pub/
FreeBSD/releases/$DESTARCH/$DESTRELEASE/#
for set in base ports; do fetch $SOURCEURL/$set.txz ; done
Extract the binaries from the tarballs on the install media into the declared destination. Minimally, only the base set needs to be extracted, but a complete install can be performed when preferred.
To install just the base system:
#
tar -xf base.txz -C $DESTDIR
To install everything except the kernel:
#
for set in base ports; do tar -xf $set.txz -C $DESTDIR ; done
The jail(8) manual page explains the procedure for building a jail:
#
setenv D
/here/is/the/jail
#
mkdir -p $D
#
cd /usr/src
#
make buildworld
#
make installworld DESTDIR=$D
#
make distribution DESTDIR=$D
#
mount -t devfs devfs $D/dev
Selecting a location for a jail is the best starting
point. This is where the jail will physically reside within
the file system of the jail's host. A good choice can be
| |
If you have already rebuilt your userland using
| |
This command will populate the directory subtree chosen as jail's physical location on the file system with the necessary binaries, libraries, manual pages and so on. | |
The | |
Mounting the devfs(8) file system inside a jail is not required. On the other hand, any, or almost any application requires access to at least one device, depending on the purpose of the given application. It is very important to control access to devices from inside a jail, as improper settings could permit an attacker to do nasty things in the jail. Control over devfs(8) is managed through rulesets which are described in the devfs(8) and devfs.conf(5) manual pages. |
Once a jail is installed, it can be started by using the
jail(8) utility. The jail(8) utility takes four
mandatory arguments which are described in the Section 14.1, “Synopsis”. Other arguments may be specified
too, e.g., to run the jailed process with the credentials of a
specific user. The
argument
depends on the type of the jail; for a
virtual system,
command
/etc/rc
is a good choice, since it will
replicate the startup sequence of a real FreeBSD system. For a
service jail, it depends on the service or
application that will run within the jail.
Jails are often started at boot time and the FreeBSD
rc
mechanism provides an easy way to do
this.
Configure jail parameters in
jail.conf
:
www
{ host.hostname =www.example.org
; # Hostname ip4.addr =192.168.0.10
; # IP address of the jail path ="/usr/jail/www
"; # Path to the jail devfs_ruleset = "www_ruleset
"; # devfs ruleset mount.devfs; # Mount devfs inside the jail exec.start = "/bin/sh /etc/rc"; # Start command exec.stop = "/bin/sh /etc/rc.shutdown"; # Stop command }
Configure jails to start at boot time in
rc.conf
:
jail_enable="YES" # Set to NO to disable starting of any jails
The default startup of jails configured in
jail.conf(5), will run the /etc/rc
script of the jail, which assumes the jail is a complete
virtual system. For service jails, the default startup
command of the jail should be changed, by setting the
exec.start
option appropriately.
For a full list of available options, please see the jail.conf(5) manual page.
service(8) can be used to start or stop a jail by hand,
if an entry for it exists in
jail.conf
:
#
service jail start
www
#
service jail stop
www
Jails can be shut down with jexec(8). Use jls(8)
to identify the jail's JID
, then use
jexec(8) to run the shutdown script in that jail.
#
jls
JID IP Address Hostname Path 3 192.168.0.10 www /usr/jail/www#
jexec
3
/etc/rc.shutdown
More information about this can be found in the jail(8) manual page.
There are several options which can be set for any jail, and various ways of combining a host FreeBSD system with jails, to produce higher level applications. This section presents:
Some of the options available for tuning the behavior and security restrictions implemented by a jail installation.
Some of the high-level applications for jail management, which are available through the FreeBSD Ports Collection, and can be used to implement overall jail-based solutions.
Fine tuning of a jail's configuration is mostly done by
setting sysctl(8) variables. A special subtree of sysctl
exists as a basis for organizing all the relevant options: the
security.jail.*
hierarchy of FreeBSD kernel
options. Here is a list of the main jail-related sysctls,
complete with their default value. Names should be
self-explanatory, but for more information about them, please
refer to the jail(8) and sysctl(8) manual
pages.
security.jail.set_hostname_allowed:
1
security.jail.socket_unixiproute_only:
1
security.jail.sysvipc_allowed:
0
security.jail.enforce_statfs:
2
security.jail.allow_raw_sockets:
0
security.jail.chflags_allowed:
0
security.jail.jailed: 0
These variables can be used by the system administrator of
the host system to add or remove some of
the limitations imposed by default on the root
user. Note that there
are some limitations which cannot be removed. The
root
user is not
allowed to mount or unmount file systems from within a
jail(8). The root
inside a jail may not
load or unload devfs(8) rulesets, set firewall rules, or
do many other administrative tasks which require modifications
of in-kernel data, such as setting the
securelevel
of the kernel.
The base system of FreeBSD contains a basic set of tools for viewing information about the active jails, and attaching to a jail to run administrative commands. The jls(8) and jexec(8) commands are part of the base FreeBSD system, and can be used to perform the following simple tasks:
Print a list of active jails and their corresponding jail identifier (JID), IP address, hostname and path.
Attach to a running jail, from its host system, and
run a command inside the jail or perform administrative
tasks inside the jail itself. This is especially useful
when the root
user wants to cleanly shut down a jail. The jexec(8)
utility can also be used to start a shell in a jail to do
administration in it; for example:
#
jexec
1
tcsh
Among the many third-party utilities for jail administration, one of the most complete and useful is sysutils/ezjail. It is a set of scripts that contribute to jail(8) management. Please refer to the handbook section on ezjail for more information.
Jails should be kept up to date from the host operating
system as attempting to patch userland from within the jail
may likely fail as the default behavior in FreeBSD is to
disallow the use of chflags(1) in a jail which prevents
the replacement of some files. It is possible to change this
behavior but it is recommended to use freebsd-update(8)
to maintain jails instead. Use -b
to specify
the path of the jail to be updated.
#
freebsd-update -b
/here/is/the/jail
fetch#
freebsd-update -b
/here/is/the/jail
install
The management of multiple jails can become problematic because every jail has to be rebuilt from scratch whenever it is upgraded. This can be time consuming and tedious if a lot of jails are created and manually updated.
This section demonstrates one method to resolve this issue by safely sharing as much as is possible between jails using read-only mount_nullfs(8) mounts, so that updating is simpler. This makes it more attractive to put single services, such as HTTP, DNS, and SMTP, into individual jails. Additionally, it provides a simple way to add, remove, and upgrade jails.
Simpler solutions exist, such as ezjail, which provides an easier method of administering FreeBSD jails but is less versatile than this setup. ezjail is covered in more detail in Section 14.6, “Managing Jails with ezjail”.
The goals of the setup described in this section are:
Create a simple and easy to understand jail structure that does not require running a full installworld on each and every jail.
Make it easy to add new jails or remove existing ones.
Make it easy to update or upgrade existing jails.
Make it possible to run a customized FreeBSD branch.
Be paranoid about security, reducing as much as possible the possibility of compromise.
Save space and inodes, as much as possible.
This design relies on a single, read-only master template which is mounted into each jail and one read-write device per jail. A device can be a separate physical disc, a partition, or a vnode backed memory device. This example uses read-write nullfs mounts.
The file system layout is as follows:
The jails are based under the
/home
partition.
Each jail will be mounted under the
/home/j
directory.
The template for each jail and the read-only partition
for all of the jails is
/home/j/mroot
.
A blank directory will be created for each jail under
the /home/j
directory.
Each jail will have a /s
directory
that will be linked to the read-write portion of the
system.
Each jail will have its own read-write system that is
based upon /home/j/skel
.
The read-write portion of each jail will be created in
/home/js
.
This section describes the steps needed to create the master template.
It is recommended to first update the host FreeBSD system to the latest -RELEASE branch using the instructions in Section 23.5, “Updating FreeBSD from Source”. Additionally, this template uses the sysutils/cpdup package or port and portsnap will be used to download the FreeBSD Ports Collection.
First, create a directory structure for the read-only file system which will contain the FreeBSD binaries for the jails. Then, change directory to the FreeBSD source tree and install the read-only file system to the jail template:
#
mkdir /home/j /home/j/mroot
#
cd /usr/src
#
make installworld DESTDIR=/home/j/mroot
Next, prepare a FreeBSD Ports Collection for the jails as well as a FreeBSD source tree, which is required for mergemaster:
#
cd /home/j/mroot
#
mkdir usr/ports
#
portsnap -p /home/j/mroot/usr/ports fetch extract
#
cpdup /usr/src /home/j/mroot/usr/src
Create a skeleton for the read-write portion of the system:
#
mkdir /home/j/skel /home/j/skel/home /home/j/skel/usr-X11R6 /home/j/skel/distfiles
#
mv etc /home/j/skel
#
mv usr/local /home/j/skel/usr-local
#
mv tmp /home/j/skel
#
mv var /home/j/skel
#
mv root /home/j/skel
Use mergemaster to install missing configuration files. Then, remove the extra directories that mergemaster creates:
#
mergemaster -t /home/j/skel/var/tmp/temproot -D /home/j/skel -i
#
cd /home/j/skel
#
rm -R bin boot lib libexec mnt proc rescue sbin sys usr dev
Now, symlink the read-write file system to the
read-only file system. Ensure that the symlinks are
created in the correct s/
locations
as the creation of directories in the wrong locations will
cause the installation to fail.
#
cd /home/j/mroot
#
mkdir s
#
ln -s s/etc etc
#
ln -s s/home home
#
ln -s s/root root
#
ln -s ../s/usr-local usr/local
#
ln -s ../s/usr-X11R6 usr/X11R6
#
ln -s ../../s/distfiles usr/ports/distfiles
#
ln -s s/tmp tmp
#
ln -s s/var var
As a last step, create a generic
/home/j/skel/etc/make.conf
containing
this line:
WRKDIRPREFIX?= /s/portbuild
This makes it possible to compile FreeBSD ports inside
each jail. Remember that the ports directory is part of
the read-only system. The custom path for
WRKDIRPREFIX
allows builds to be done
in the read-write portion of every jail.
The jail template can now be used to setup and configure
the jails in /etc/rc.conf
. This example
demonstrates the creation of 3 jails: NS
,
MAIL
and WWW
.
Add the following lines to
/etc/fstab
, so that the read-only
template for the jails and the read-write space will be
available in the respective jails:
/home/j/mroot /home/j/ns nullfs ro 0 0 /home/j/mroot /home/j/mail nullfs ro 0 0 /home/j/mroot /home/j/www nullfs ro 0 0 /home/js/ns /home/j/ns/s nullfs rw 0 0 /home/js/mail /home/j/mail/s nullfs rw 0 0 /home/js/www /home/j/www/s nullfs rw 0 0
To prevent
fsck from checking
nullfs mounts during boot and
dump from backing up the
read-only nullfs mounts of the jails, the last two
columns are both set to 0
.
Configure the jails in
/etc/rc.conf
:
jail_enable="YES" jail_set_hostname_allow="NO" jail_list="ns mail www" jail_ns_hostname="ns.example.org" jail_ns_ip="192.168.3.17" jail_ns_rootdir="/usr/home/j/ns" jail_ns_devfs_enable="YES" jail_mail_hostname="mail.example.org" jail_mail_ip="192.168.3.18" jail_mail_rootdir="/usr/home/j/mail" jail_mail_devfs_enable="YES" jail_www_hostname="www.example.org" jail_www_ip="62.123.43.14" jail_www_rootdir="/usr/home/j/www" jail_www_devfs_enable="YES"
The
jail_
variable is set to
name
_rootdir/usr/home
instead
of /home
because
the physical path of /home
on a default FreeBSD
installation is /usr/home
. The
jail_
variable must not be set to a path
which includes a symbolic link, otherwise the jails will
refuse to start.name
_rootdir
Create the required mount points for the read-only file system of each jail:
#
mkdir /home/j/ns /home/j/mail /home/j/www
Install the read-write template into each jail using sysutils/cpdup:
#
mkdir /home/js
#
cpdup /home/j/skel /home/js/ns
#
cpdup /home/j/skel /home/js/mail
#
cpdup /home/j/skel /home/js/www
In this phase, the jails are built and prepared to run. First, mount the required file systems for each jail, and then start them:
#
mount -a
#
service jail start
The jails should be running now. To check if they have
started correctly, use jls
. Its output
should be similar to the following:
#
jls
JID IP Address Hostname Path 3 192.168.3.17 ns.example.org /home/j/ns 2 192.168.3.18 mail.example.org /home/j/mail 1 62.123.43.14 www.example.org /home/j/www
At this point, it should be possible to log onto each
jail, add new users, or configure daemons. The
JID
column indicates the jail
identification number of each running jail. Use the following
command to perform administrative tasks in the jail whose
JID is 3
:
#
jexec 3 tcsh
The design of this setup provides an easy way to upgrade existing jails while minimizing their downtime. Also, it provides a way to roll back to the older version should a problem occur.
The first step is to upgrade the host system. Then,
create a new temporary read-only template in
/home/j/mroot2
.
#
mkdir /home/j/mroot2
#
cd /usr/src
#
make installworld DESTDIR=/home/j/mroot2
#
cd /home/j/mroot2
#
cpdup /usr/src usr/src
#
mkdir s
The installworld
creates a
few unnecessary directories, which should be
removed:
#
chflags -R 0 var
#
rm -R etc var root usr/local tmp
Recreate the read-write symlinks for the master file system:
#
ln -s s/etc etc
#
ln -s s/root root
#
ln -s s/home home
#
ln -s ../s/usr-local usr/local
#
ln -s ../s/usr-X11R6 usr/X11R6
#
ln -s s/tmp tmp
#
ln -s s/var var
Next, stop the jails:
#
service jail stop
Unmount the original file systems as the read-write
systems are attached to the read-only system
(/s
):
#
umount /home/j/ns/s
#
umount /home/j/ns
#
umount /home/j/mail/s
#
umount /home/j/mail
#
umount /home/j/www/s
#
umount /home/j/www
Move the old read-only file system and replace it with the new one. This will serve as a backup and archive of the old read-only file system should something go wrong. The naming convention used here corresponds to when a new read-only file system has been created. Move the original FreeBSD Ports Collection over to the new file system to save some space and inodes:
#
cd /home/j
#
mv mroot mroot.20060601
#
mv mroot2 mroot
#
mv mroot.20060601/usr/ports mroot/usr
At this point the new read-only template is ready, so the only remaining task is to remount the file systems and start the jails:
#
mount -a
#
service jail start
Use jls
to check if the jails started
correctly. Run mergemaster
in each jail to
update the configuration files.
Creating and managing multiple jails can quickly become tedious and error-prone. Dirk Engling's ezjail automates and greatly simplifies many jail tasks. A basejail is created as a template. Additional jails use mount_nullfs(8) to share many of the basejail directories without using additional disk space. Each additional jail takes only a few megabytes of disk space before applications are installed. Upgrading the copy of the userland in the basejail automatically upgrades all of the other jails.
Additional benefits and features are described in detail on the ezjail web site, https://erdgeist.org/arts/software/ezjail/.
Installing ezjail consists of adding a loopback interface for use in jails, installing the port or package, and enabling the service.
To keep jail loopback traffic off the host's loopback
network interface lo0
, a second
loopback interface is created by adding an entry to
/etc/rc.conf
:
cloned_interfaces="lo1"
The second loopback interface lo1
will be created when the system starts. It can also be
created manually without a restart:
#
service netif cloneup
Created clone interfaces: lo1.
Jails can be allowed to use aliases of this secondary loopback interface without interfering with the host.
Inside a jail, access to the loopback address
127.0.0.1
is
redirected to the first IP address
assigned to the jail. To make the jail loopback
correspond with the new lo1
interface,
that interface must be specified first in the list of
interfaces and IP addresses given when
creating a new jail.
Give each jail a unique loopback address in the
127.0.0.0
/8
netblock.
Install sysutils/ezjail:
#
cd /usr/ports/sysutils/ezjail
#
make install clean
Enable ezjail by adding
this line to /etc/rc.conf
:
ezjail_enable="YES"
The service will automatically start on system boot. It can be started immediately for the current session:
#
service ezjail start
With ezjail installed, the basejail directory structure can be created and populated. This step is only needed once on the jail host computer.
In both of these examples, -p
causes the
ports tree to be retrieved with portsnap(8) into the
basejail. That single copy of the ports directory will be
shared by all the jails. Using a separate copy of the ports
directory for jails isolates them from the host. The
ezjail FAQ
explains in more detail: http://erdgeist.org/arts/software/ezjail/#FAQ.
To Populate the Jail with FreeBSD-RELEASE
For a basejail based on the FreeBSD RELEASE matching
that of the host computer, use
install
. For example, on a host
computer running FreeBSD 10-STABLE, the latest
RELEASE version of FreeBSD -10 will be installed in
the jail):
#
ezjail-admin install -p
To Populate the Jail with
installworld
The basejail can be installed from binaries
created by buildworld
on
the host with
ezjail-admin update
.
In this example, FreeBSD 10-STABLE has been
built from source. The jail directories are created.
Then installworld
is
executed, installing the host's
/usr/obj
into the
basejail.
#
ezjail-admin update -i -p
The host's /usr/src
is used
by default. A different source directory on the host
can be specified with -s
and a path,
or set with ezjail_sourcetree
in
/usr/local/etc/ezjail.conf
.
The basejail's ports tree is shared by other jails.
However, downloaded distfiles are stored in the jail that
downloaded them. By default, these files are stored in
/var/ports/distfiles
within each
jail. /var/ports
inside each jail is
also used as a work directory when building ports.
The FTP protocol is used by default
to download packages for the installation of the basejail.
Firewall or proxy configurations can prevent or interfere
with FTP transfers. The
HTTP protocol works differently and
avoids these problems. It can be chosen by specifying a
full URL for a particular download mirror
in /usr/local/etc/ezjail.conf
:
ezjail_ftphost=http://ftp.FreeBSD.org
See Section A.2, “FTP Sites” for a list of sites.
New jails are created with
ezjail-admin create
. In these examples,
the lo1
loopback interface is used as
described above.
Create the jail, specifying a name and the loopback
and network interfaces to use, along with their
IP addresses. In this example, the
jail is named dnsjail
.
#
ezjail-admin create
dnsjail
'lo1|127.0.1.1
,em0
|192.168.1.50
'
Most network services run in jails without problems. A few network services, most notably ping(8), use raw network sockets. In jails, raw network sockets are disabled by default for security. Services that require them will not work.
Occasionally, a jail genuinely needs raw sockets.
For example, network monitoring applications often use
ping(8) to check the availability of other
computers. When raw network sockets are actually needed
in a jail, they can be enabled by editing the
ezjail
configuration file for the individual jail,
/usr/local/etc/ezjail/
.
Modify the jailname
parameters
entry:
export jail_jailname
_parameters="allow.raw_sockets=1"
Do not enable raw network sockets unless services in the jail actually require them.
Start the jail:
#
ezjail-admin start
dnsjail
Use a console on the jail:
#
ezjail-admin console
dnsjail
The jail is operating and additional configuration can be completed. Typical settings added at this point include:
Set the
root
Password
Connect to the jail and set the
root
user's
password:
#
ezjail-admin console
dnsjail
#
passwd
Changing local password for root New Password: Retype New Password:
Time Zone Configuration
The jail's time zone can be set with tzsetup(8).
To avoid spurious error messages, the adjkerntz(8)
entry in /etc/crontab
can be
commented or removed. This job attempts to update the
computer's hardware clock with time zone changes, but
jails are not allowed to access that hardware.
DNS Servers
Enter domain name server lines in
/etc/resolv.conf
so
DNS works in the jail.
Edit /etc/hosts
Change the address and add the jail name to the
localhost
entries in
/etc/hosts
.
Configure /etc/rc.conf
Enter configuration settings in
/etc/rc.conf
. This is much like
configuring a full computer. The host name and
IP address are not set here. Those
values are already provided by the jail
configuration.
With the jail configured, the applications for which the jail was created can be installed.
Some ports must be built with special options to be used
in a jail. For example, both of the network monitoring
plugin packages
net-mgmt/nagios-plugins and
net-mgmt/monitoring-plugins
have a JAIL
option which must be enabled
for them to work correctly inside a jail.
Because the basejail's copy of the userland is shared by the other jails, updating the basejail automatically updates all of the other jails. Either source or binary updates can be used.
To build the world from source on the host, then install it in the basejail, use:
#
ezjail-admin update -b
If the world has already been compiled on the host, install it in the basejail with:
#
ezjail-admin update -i
Binary updates use freebsd-update(8). These updates have the same limitations as if freebsd-update(8) were being run directly. The most important one is that only -RELEASE versions of FreeBSD are available with this method.
Update the basejail to the latest patched release of the version of FreeBSD on the host. For example, updating from RELEASE-p1 to RELEASE-p2.
#
ezjail-admin update -u
To upgrade the basejail to a new version, first upgrade the host system as described in Section 23.2.3, “Performing Major and Minor Version Upgrades”. Once the host has been upgraded and rebooted, the basejail can then be upgraded. freebsd-update(8) has no way of determining which version is currently installed in the basejail, so the original version must be specified. Use file(1) to determine the original version in the basejail:
#
file /usr/jails/basejail/bin/sh
/usr/jails/basejail/bin/sh: ELF 64-bit LSB executable, x86-64, version 1 (FreeBSD), dynamically linked (uses shared libs), for FreeBSD 9.3, stripped
Now use this information to perform the upgrade from
9.3-RELEASE
to the current version of
the host system:
#
ezjail-admin update -U -s
9.3-RELEASE
After updating the basejail, mergemaster(8) must be run to update each jail's configuration files.
How to use mergemaster(8) depends on the purpose and trustworthiness of a jail. If a jail's services or users are not trusted, then mergemaster(8) should only be run from within that jail:
Delete the link from the jail's
/usr/src
into the basejail and
create a new /usr/src
in the jail
as a mountpoint. Mount the host computer's
/usr/src
read-only on the jail's
new /usr/src
mountpoint:
#
rm /usr/jails/
jailname
/usr/src#
mkdir /usr/jails/
jailname
/usr/src#
mount -t nullfs -o ro /usr/src /usr/jails/
jailname
/usr/src
Get a console in the jail:
#
ezjail-admin console
jailname
Inside the jail, run mergemaster
.
Then exit the jail console:
#
cd /usr/src
#
mergemaster -U
#
exit
Finally, unmount the jail's
/usr/src
:
#
umount /usr/jails/
jailname
/usr/src
If the users and services in a jail are trusted, mergemaster(8) can be run from the host:
#
mergemaster -U -D /usr/jails/
jailname
The ports tree in the basejail is shared by the other jails. Updating that copy of the ports tree gives the other jails the updated version also.
The basejail ports tree is updated with portsnap(8):
#
ezjail-admin update -P
ezjail automatically starts
jails when the computer is started. Jails can be manually
stopped and restarted with stop
and
start
:
#
ezjail-admin stop
Stopping jails: sambajail.sambajail
By default, jails are started automatically when the
host computer starts. Autostarting can be disabled
with config
:
#
ezjail-admin config -r norun
seldomjail
This takes effect the next time the host computer is started. A jail that is already running will not be stopped.
Enabling autostart is very similar:
#
ezjail-admin config -r run
oftenjail
Use archive
to create a
.tar.gz
archive of a jail. The file
name is composed from the name of the jail and the current
date. Archive files are written to the archive directory,
/usr/jails/ezjail_archives
. A
different archive directory can be chosen by setting
ezjail_archivedir
in the configuration
file.
The archive file can be copied elsewhere as a backup, or
an existing jail can be restored from it with
restore
. A new jail can be created from
the archive, providing a convenient way to clone existing
jails.
Stop and archive a jail named
wwwserver
:
#
ezjail-admin stop
Stopping jails: wwwserver.wwwserver
#
ezjail-admin archive
wwwserver
#
ls /usr/jails/ezjail-archives/
wwwserver-201407271153.13.tar.gz
Create a new jail named
wwwserver-clone
from the archive created
in the previous step. Use the em1
interface and assign a new IP address to
avoid conflict with the original:
#
ezjail-admin create -a /usr/jails/ezjail_archives/wwwserver-201407271153.13.tar.gz
wwwserver-clone
'lo1|127.0.3.1,em1|192.168.1.51'
Putting the BIND DNS server in a jail improves security by isolating it. This example creates a simple caching-only name server.
The jail will be called
dns1
.
The jail will use IP address
192.168.1.240
on the host's
re0
interface.
The upstream ISP's DNS servers are
at 10.0.0.62
and
10.0.0.61
.
The basejail has already been created and a ports tree installed as shown in Section 14.6.2, “Initial Setup”.
Create a cloned loopback interface by adding a line to
/etc/rc.conf
:
cloned_interfaces="lo1"
Immediately create the new loopback interface:
#
service netif cloneup
Created clone interfaces: lo1.
Create the jail:
#
ezjail-admin create dns1 'lo1|127.0.2.1,re0|192.168.1.240'
Start the jail, connect to a console running on it, and perform some basic configuration:
#
ezjail-admin start dns1
#
ezjail-admin console dns1
#
passwd
Changing local password for root New Password: Retype New Password:#
tzsetup
#
sed -i .bak -e '/adjkerntz/ s/^/#/' /etc/crontab
#
sed -i .bak -e 's/127.0.0.1/127.0.2.1/g; s/localhost.my.domain/dns1.my.domain dns1/' /etc/hosts
Temporarily set the upstream DNS
servers in /etc/resolv.conf
so ports
can be downloaded:
nameserver 10.0.0.62 nameserver 10.0.0.61
Still using the jail console, install dns/bind99.
#
make -C /usr/ports/dns/bind99 install clean
Configure the name server by editing
/usr/local/etc/namedb/named.conf
.
Create an Access Control List (ACL)
of addresses and networks that are permitted to send
DNS queries to this name server. This
section is added just before the options
section already in the file:
... // or cause huge amounts of useless Internet traffic. acl "trusted" { 192.168.1.0/24; localhost; localnets; }; options { ...
Use the jail IP address in the
listen-on
setting to accept
DNS queries from other computers on the
network:
listen-on { 192.168.1.240; };
A simple caching-only DNS name server
is created by changing the forwarders
section. The original file contains:
/* forwarders { 127.0.0.1; }; */
Uncomment the section by removing the
/*
and */
lines.
Enter the IP addresses of the upstream
DNS servers. Immediately after the
forwarders
section, add references to the
trusted
ACL defined
earlier:
forwarders { 10.0.0.62; 10.0.0.61; }; allow-query { any; }; allow-recursion { trusted; }; allow-query-cache { trusted; };
Enable the service in
/etc/rc.conf
:
named_enable="YES"
Start and test the name server:
#
service named start
wrote key file "/usr/local/etc/namedb/rndc.key" Starting named.#
/usr/local/bin/dig @192.168.1.240 freebsd.org
A response that includes
;; Got answer;
shows that the new DNS server is working. A long delay followed by a response including
;; connection timed out; no servers could be reached
shows a problem. Check the configuration settings and make sure any local firewalls allow the new DNS access to the upstream DNS servers.
The new DNS server can use itself for
local name resolution, just like other local computers. Set
the address of the DNS server in the
client computer's
/etc/resolv.conf
:
nameserver 192.168.1.240
A local DHCP server can be configured to provide this address for a local DNS server, providing automatic configuration on DHCP clients.
FreeBSD supports security extensions based on the POSIX®.1e draft. These security mechanisms include file system Access Control Lists (Section 13.9, “Access Control Lists”) and Mandatory Access Control (MAC). MAC allows access control modules to be loaded in order to implement security policies. Some modules provide protections for a narrow subset of the system, hardening a particular service. Others provide comprehensive labeled security across all subjects and objects. The mandatory part of the definition indicates that enforcement of controls is performed by administrators and the operating system. This is in contrast to the default security mechanism of Discretionary Access Control (DAC) where enforcement is left to the discretion of users.
This chapter focuses on the MAC framework and the set of pluggable security policy modules FreeBSD provides for enabling various security mechanisms.
After reading this chapter, you will know:
The terminology associated with the MAC framework.
The capabilities of MAC security policy modules as well as the difference between a labeled and non-labeled policy.
The considerations to take into account before configuring a system to use the MAC framework.
Which MAC security policy modules are included in FreeBSD and how to configure them.
How to implement a more secure environment using the MAC framework.
How to test the MAC configuration to ensure the framework has been properly implemented.
Before reading this chapter, you should:
Understand UNIX® and FreeBSD basics (Chapter 3, FreeBSD Basics).
Have some familiarity with security and how it pertains to FreeBSD (Chapter 13, Security).
Improper MAC configuration may cause loss of system access, aggravation of users, or inability to access the features provided by Xorg. More importantly, MAC should not be relied upon to completely secure a system. The MAC framework only augments an existing security policy. Without sound security practices and regular security checks, the system will never be completely secure.
The examples contained within this chapter are for demonstration purposes and the example settings should not be implemented on a production system. Implementing any security policy takes a good deal of understanding, proper design, and thorough testing.
While this chapter covers a broad range of security issues relating to the MAC framework, the development of new MAC security policy modules will not be covered. A number of security policy modules included with the MAC framework have specific characteristics which are provided for both testing and new module development. Refer to mac_test(4), mac_stub(4) and mac_none(4) for more information on these security policy modules and the various mechanisms they provide.
The following key terms are used when referring to the MAC framework:
compartment: a set of programs and data to be partitioned or separated, where users are given explicit access to specific component of a system. A compartment represents a grouping, such as a work group, department, project, or topic. Compartments make it possible to implement a need-to-know-basis security policy.
integrity: the level of trust which can be placed on data. As the integrity of the data is elevated, so does the ability to trust that data.
level: the increased or decreased setting of a security attribute. As the level increases, its security is considered to elevate as well.
label: a security attribute which can be applied to files, directories, or other items in the system. It could be considered a confidentiality stamp. When a label is placed on a file, it describes the security properties of that file and will only permit access by files, users, and resources with a similar security setting. The meaning and interpretation of label values depends on the policy configuration. Some policies treat a label as representing the integrity or secrecy of an object while other policies might use labels to hold rules for access.
multilabel: this property is a file system option which can be set in single-user mode using tunefs(8), during boot using fstab(5), or during the creation of a new file system. This option permits an administrator to apply different MAC labels on different objects. This option only applies to security policy modules which support labeling.
single label: a policy where the
entire file system uses one label to enforce access control
over the flow of data. Whenever multilabel
is not set, all files will conform to the same label
setting.
object: an entity through which information flows under the direction of a subject. This includes directories, files, fields, screens, keyboards, memory, magnetic storage, printers or any other data storage or moving device. An object is a data container or a system resource. Access to an object effectively means access to its data.
subject: any active entity that causes information to flow between objects such as a user, user process, or system process. On FreeBSD, this is almost always a thread acting in a process on behalf of a user.
policy: a collection of rules which defines how objectives are to be achieved. A policy usually documents how certain items are to be handled. This chapter considers a policy to be a collection of rules which controls the flow of data and information and defines who has access to that data and information.
high-watermark: this type of policy permits the raising of security levels for the purpose of accessing higher level information. In most cases, the original level is restored after the process is complete. Currently, the FreeBSD MAC framework does not include this type of policy.
low-watermark: this type of policy permits lowering security levels for the purpose of accessing information which is less secure. In most cases, the original security level of the user is restored after the process is complete. The only security policy module in FreeBSD to use this is mac_lomac(4).
sensitivity: usually used when discussing Multilevel Security (MLS). A sensitivity level describes how important or secret the data should be. As the sensitivity level increases, so does the importance of the secrecy, or confidentiality, of the data.
A MAC label is a security attribute which may be applied to subjects and objects throughout the system. When setting a label, the administrator must understand its implications in order to prevent unexpected or undesired behavior of the system. The attributes available on an object depend on the loaded policy module, as policy modules interpret their attributes in different ways.
The security label on an object is used as a part of a security access control decision by a policy. With some policies, the label contains all of the information necessary to make a decision. In other policies, the labels may be processed as part of a larger rule set.
There are two types of label policies: single label and multi label. By default, the system will use single label. The administrator should be aware of the pros and cons of each in order to implement policies which meet the requirements of the system's security model.
A single label security policy only permits one label to be used for every subject or object. Since a single label policy enforces one set of access permissions across the entire system, it provides lower administration overhead, but decreases the flexibility of policies which support labeling. However, in many environments, a single label policy may be all that is required.
A single label policy is somewhat similar to
DAC as root
configures the policies so
that users are placed in the appropriate categories and access
levels. A notable difference is that many policy modules can
also restrict root
.
Basic control over objects will then be released to the group,
but root
may revoke or
modify the settings at any time.
When appropriate, a multi label policy can be set on a
UFS file system by passing
multilabel
to tunefs(8). A multi label
policy permits each subject or object to have its own
independent MAC label. The decision to use a
multi label or single label policy is only required for policies
which implement the labeling feature, such as
biba
, lomac
, and
mls
. Some policies, such as
seeotheruids
, portacl
and
partition
, do not use labels at all.
Using a multi label policy on a partition and establishing a multi label security model can increase administrative overhead as everything in that file system has a label. This includes directories, files, and even device nodes.
The following command will set multilabel
on the specified UFS file system. This may
only be done in single-user mode and is not a requirement for
the swap file system:
#
tunefs -l enable /
Some users have experienced problems with setting the
multilabel
flag on the root partition. If
this is the case, please review Section 15.8, “Troubleshooting the MAC Framework”.
Since the multi label policy is set on a per-file system
basis, a multi label policy may not be needed if the file system
layout is well designed. Consider an example security
MAC model for a FreeBSD web server. This
machine uses the single label, biba/high
, for
everything in the default file systems. If the web server needs
to run at biba/low
to prevent write up
capabilities, it could be installed to a separate
UFS /usr/local
file
system set at biba/low
.
Virtually all aspects of label policy module configuration will be performed using the base system utilities. These commands provide a simple interface for object or subject configuration or the manipulation and verification of the configuration.
All configuration may be done using
setfmac
, which is used to set
MAC labels on system objects, and
setpmac
, which is used to set the labels on
system subjects. For example, to set the
biba
MAC label to
high
on test
:
#
setfmac biba/high test
If the configuration is successful, the prompt will be returned without error. A common error is Permission denied which usually occurs when the label is being set or modified on a restricted object. Other conditions may produce different failures. For instance, the file may not be owned by the user attempting to relabel the object, the object may not exist, or the object may be read-only. A mandatory policy will not allow the process to relabel the file, maybe because of a property of the file, a property of the process, or a property of the proposed new label value. For example, if a user running at low integrity tries to change the label of a high integrity file, or a user running at low integrity tries to change the label of a low integrity file to a high integrity label, these operations will fail.
The system administrator may use
setpmac
to override the policy module's
settings by assigning a different label to the invoked
process:
#
setfmac biba/high test
Permission denied#
setpmac biba/low setfmac biba/high test
#
getfmac test
test: biba/high
For currently running processes, such as
sendmail,
getpmac
is usually used instead. This
command takes a process ID (PID) in place
of a command name. If users attempt to manipulate a file not
in their access, subject to the rules of the loaded policy
modules, the Operation not permitted
error will be displayed.
A few FreeBSD policy modules which support the labeling
feature offer three predefined labels: low
,
equal
, and high
,
where:
low
is considered the lowest label
setting an object or subject may have. Setting this on
objects or subjects blocks their access to objects or
subjects marked high.
equal
sets the subject or object to
be disabled or unaffected and should only be placed on
objects considered to be exempt from the policy.
high
grants an object or subject
the highest setting available in the Biba and
MLS policy modules.
Such policy modules include mac_biba(4), mac_mls(4) and mac_lomac(4). Each of the predefined labels establishes a different information flow directive. Refer to the manual page of the module to determine the traits of the generic label configurations.
The Biba and MLS policy modules support a numeric label which may be set to indicate the precise level of hierarchical control. This numeric level is used to partition or sort information into different groups of classification, only permitting access to that group or a higher group level. For example:
biba/10:2+3+6(5:2+3-20:2+3+4+5+6)
may be interpreted as “Biba Policy Label/Grade 10:Compartments 2, 3 and 6: (grade 5 ...”)
In this example, the first grade would be considered the effective grade with effective compartments, the second grade is the low grade, and the last one is the high grade. In most configurations, such fine-grained settings are not needed as they are considered to be advanced configurations.
System objects only have a current grade and compartment. System subjects reflect the range of available rights in the system, and network interfaces, where they are used for access control.
The grade and compartments in a subject and object pair
are used to construct a relationship known as
dominance, in which a subject dominates
an object, the object dominates the subject, neither dominates
the other, or both dominate each other. The “both
dominate” case occurs when the two labels are equal.
Due to the information flow nature of Biba, a user has rights
to a set of compartments that might correspond to projects,
but objects also have a set of compartments. Users may have
to subset their rights using su
or
setpmac
in order to access objects in a
compartment from which they are not restricted.
Users are required to have labels so that their files and
processes properly interact with the security policy defined
on the system. This is configured in
/etc/login.conf
using login classes.
Every policy module that uses labels will implement the user
class setting.
To set the user class default label which will be enforced
by MAC, add a label
entry.
An example label
entry containing every
policy module is displayed below. Note that in a real
configuration, the administrator would never enable every
policy module. It is recommended that the rest of this
chapter be reviewed before any configuration is
implemented.
default:\ :copyright=/etc/COPYRIGHT:\ :welcome=/etc/motd:\ :setenv=MAIL=/var/mail/$,BLOCKSIZE=K:\ :path=~/bin:/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin:\ :manpath=/usr/share/man /usr/local/man:\ :nologin=/usr/sbin/nologin:\ :cputime=1h30m:\ :datasize=8M:\ :vmemoryuse=100M:\ :stacksize=2M:\ :memorylocked=4M:\ :memoryuse=8M:\ :filesize=8M:\ :coredumpsize=8M:\ :openfiles=24:\ :maxproc=32:\ :priority=0:\ :requirehome:\ :passwordtime=91d:\ :umask=022:\ :ignoretime@:\ :label=partition/13,mls/5,biba/10(5-15),lomac/10[2]:
While users can not modify the default value, they may
change their label after they login, subject to the
constraints of the policy. The example above tells the Biba
policy that a process's minimum integrity is
5
, its maximum is 15
,
and the default effective label is 10
. The
process will run at 10
until it chooses to
change label, perhaps due to the user using
setpmac
, which will be constrained by Biba
to the configured range.
After any change to login.conf
, the
login class capability database must be rebuilt using
cap_mkdb
.
Many sites have a large number of users requiring several different user classes. In depth planning is required as this can become difficult to manage.
Labels may be set on network interfaces to help control
the flow of data across the network. Policies using network
interface labels function in the same way that policies
function with respect to objects. Users at high settings in
Biba, for example, will not be permitted to access network
interfaces with a label of low
.
When setting the MAC label on network
interfaces, maclabel
may be passed to
ifconfig
:
#
ifconfig bge0 maclabel biba/equal
This example will set the MAC label of
biba/equal
on the bge0
interface. When using a setting similar to
biba/high(low-high)
, the entire label
should be quoted to prevent an error from being
returned.
Each policy module which supports labeling has a tunable
which may be used to disable the MAC label
on network interfaces. Setting the label to
equal
will have a similar effect. Review
the output of sysctl
, the policy manual
pages, and the information in the rest of this chapter for
more information on those tunables.
Before implementing any MAC policies, a planning phase is recommended. During the planning stages, an administrator should consider the implementation requirements and goals, such as:
How to classify information and resources available on the target systems.
Which information or resources to restrict access to along with the type of restrictions that should be applied.
Which MAC modules will be required to achieve this goal.
A trial run of the trusted system and its configuration should occur before a MAC implementation is used on production systems. Since different environments have different needs and requirements, establishing a complete security profile will decrease the need of changes once the system goes live.
Consider how the MAC framework augments the security of the system as a whole. The various security policy modules provided by the MAC framework could be used to protect the network and file systems or to block users from accessing certain ports and sockets. Perhaps the best use of the policy modules is to load several security policy modules at a time in order to provide a MLS environment. This approach differs from a hardening policy, which typically hardens elements of a system which are used only for specific purposes. The downside to MLS is increased administrative overhead.
The overhead is minimal when compared to the lasting effect of a framework which provides the ability to pick and choose which policies are required for a specific configuration and which keeps performance overhead down. The reduction of support for unneeded policies can increase the overall performance of the system as well as offer flexibility of choice. A good implementation would consider the overall security requirements and effectively implement the various security policy modules offered by the framework.
A system utilizing MAC guarantees that a user will not be permitted to change security attributes at will. All user utilities, programs, and scripts must work within the constraints of the access rules provided by the selected security policy modules and control of the MAC access rules is in the hands of the system administrator.
It is the duty of the system administrator to carefully select the correct security policy modules. For an environment that needs to limit access control over the network, the mac_portacl(4), mac_ifoff(4), and mac_biba(4) policy modules make good starting points. For an environment where strict confidentiality of file system objects is required, consider the mac_bsdextended(4) and mac_mls(4) policy modules.
Policy decisions could be made based on network configuration. If only certain users should be permitted access to ssh(1), the mac_portacl(4) policy module is a good choice. In the case of file systems, access to objects might be considered confidential to some users, but not to others. As an example, a large development team might be broken off into smaller projects where developers in project A might not be permitted to access objects written by developers in project B. Yet both projects might need to access objects created by developers in project C. Using the different security policy modules provided by the MAC framework, users could be divided into these groups and then given access to the appropriate objects.
Each security policy module has a unique way of dealing with the overall security of a system. Module selection should be based on a well thought out security policy which may require revision and reimplementation. Understanding the different security policy modules offered by the MAC framework will help administrators choose the best policies for their situations.
The rest of this chapter covers the available modules, describes their use and configuration, and in some cases, provides insight on applicable situations.
Implementing MAC is much like implementing a firewall since care must be taken to prevent being completely locked out of the system. The ability to revert back to a previous configuration should be considered and the implementation of MAC over a remote connection should be done with extreme caution.
The default FreeBSD kernel
includes options MAC
. This means that every
module included with the MAC framework can be
loaded with kldload
as a run-time kernel
module. After testing the module, add the module name to
/boot/loader.conf
so that it will load
during boot. Each module also provides a kernel option for
those administrators who choose to compile their own custom
kernel.
FreeBSD includes a group of policies that will cover most security requirements. Each policy is summarized below. The last three policies support integer settings in place of the three default labels.
Module name:
mac_seeotheruids.ko
Kernel configuration line:
options MAC_SEEOTHERUIDS
Boot option:
mac_seeotheruids_load="YES"
The mac_seeotheruids(4) module extends the
security.bsd.see_other_uids
and
security.bsd.see_other_gids
sysctl
tunables. This option does not
require any labels to be set before configuration and can
operate transparently with other modules.
After loading the module, the following
sysctl
tunables may be used to control its
features:
security.mac.seeotheruids.enabled
enables the module and implements the default settings
which deny users the ability to view processes and sockets
owned by other users.
security.mac.seeotheruids.specificgid_enabled
allows specified groups to be exempt from this policy. To
exempt specific groups, use the
security.mac.seeotheruids.specificgid=
XXX
sysctl
tunable, replacing
XXX
with the numeric group ID
to be exempted.
security.mac.seeotheruids.primarygroup_enabled
is used to exempt specific primary groups from this
policy. When using this tunable,
security.mac.seeotheruids.specificgid_enabled
may not be set.
Module name:
mac_bsdextended.ko
Kernel configuration line:
options MAC_BSDEXTENDED
Boot option:
mac_bsdextended_load="YES"
The mac_bsdextended(4) module enforces a file system
firewall. It provides an extension to the standard file
system permissions model, permitting an administrator to
create a firewall-like ruleset to protect files, utilities,
and directories in the file system hierarchy. When access to
a file system object is attempted, the list of rules is
iterated until either a matching rule is located or the end is
reached. This behavior may be changed using
security.mac.bsdextended.firstmatch_enabled
.
Similar to other firewall modules in FreeBSD, a file containing
the access control rules can be created and read by the system
at boot time using an rc.conf(5) variable.
The rule list may be entered using ugidfw(8) which has a syntax similar to ipfw(8). More tools can be written by using the functions in the libugidfw(3) library.
After the mac_bsdextended(4) module has been loaded, the following command may be used to list the current rule configuration:
#
ugidfw list
0 slots, 0 rules
By default, no rules are defined and everything is
completely accessible. To create a rule which blocks all
access by users but leaves root
unaffected:
#
ugidfw add subject not uid root new object not uid root mode n
While this rule is simple to implement, it is a very bad
idea as it blocks all users from issuing any commands. A
more realistic example blocks user1
all access, including
directory listings, to
's
home directory:user2
#
ugidfw set 2 subject uid
user1
object uiduser2
mode n#
ugidfw set 3 subject uid
user1
object giduser2
mode n
Instead of user1
, not
uid
could be used
in order to enforce the same access restrictions for all
users. However, the user2
root
user is unaffected by
these rules.
Extreme caution should be taken when working with this module as incorrect use could block access to certain parts of the file system.
Module name: mac_ifoff.ko
Kernel configuration line: options
MAC_IFOFF
Boot option:
mac_ifoff_load="YES"
The mac_ifoff(4) module is used to disable network interfaces on the fly and to keep network interfaces from being brought up during system boot. It does not use labels and does not depend on any other MAC modules.
Most of this module's control is performed through these
sysctl
tunables:
One of the most common uses of mac_ifoff(4) is network monitoring in an environment where network traffic should not be permitted during the boot sequence. Another use would be to write a script which uses an application such as security/aide to automatically block network traffic if it finds new or altered files in protected directories.
Module name: mac_portacl.ko
Kernel configuration line:
MAC_PORTACL
Boot option:
mac_portacl_load="YES"
The mac_portacl(4) module is used to limit binding to
local TCP and UDP ports,
making it possible to allow non-root
users to bind to
specified privileged ports below 1024.
Once loaded, this module enables the MAC policy on all sockets. The following tunables are available:
security.mac.portacl.enabled
enables or disables the policy completely.
security.mac.portacl.port_high
sets the highest port number that mac_portacl(4)
protects.
security.mac.portacl.suser_exempt
,
when set to a non-zero value, exempts the root
user from this
policy.
security.mac.portacl.rules
specifies the policy as a text string of the form
rule[,rule,...]
, with as many rules as
needed, and where each rule is of the form
idtype:id:protocol:port
. The
idtype
is either
uid
or gid
. The
protocol
parameter can be
tcp
or udp
. The
port
parameter is the port number
to allow the specified user or group to bind to. Only
numeric values can be used for the user ID, group ID,
and port parameters.
By default, ports below 1024 can only be used by
privileged processes which run as root
. For mac_portacl(4)
to allow non-privileged processes to bind to ports below 1024,
set the following tunables as
follows:
#
sysctl security.mac.portacl.port_high=1023
#
sysctl net.inet.ip.portrange.reservedlow=0
#
sysctl net.inet.ip.portrange.reservedhigh=0
To prevent the root
user from being affected
by this policy, set
security.mac.portacl.suser_exempt
to a
non-zero value.
#
sysctl security.mac.portacl.suser_exempt=1
To allow the www
user with UID 80 to bind to port 80
without ever needing root
privilege:
#
sysctl security.mac.portacl.rules=uid:80:tcp:80
This next example permits the user with the UID of 1001 to bind to TCP ports 110 (POP3) and 995 (POP3s):
#
sysctl security.mac.portacl.rules=uid:1001:tcp:110,uid:1001:tcp:995
Module name: mac_partition.ko
Kernel configuration line:
options MAC_PARTITION
Boot option:
mac_partition_load="YES"
The mac_partition(4) policy drops processes into
specific “partitions” based on their
MAC label. Most configuration for this
policy is done using setpmac(8). One
sysctl
tunable is available for this
policy:
security.mac.partition.enabled
enables the enforcement of MAC process
partitions.
When this policy is enabled, users will only be permitted
to see their processes, and any others within their partition,
but will not be permitted to work with utilities outside the
scope of this partition. For instance, a user in the
insecure
class will not be permitted to
access top
as well as many other commands
that must spawn a process.
This example adds top
to the label set
on users in the insecure
class. All
processes spawned by users in the insecure
class will stay in the partition/13
label.
#
setpmac partition/13 top
This command displays the partition label and the process list:
#
ps Zax
This command displays another user's process partition label and that user's currently running processes:
#
ps -ZU trhodes
Users can see processes in root
's label unless the
mac_seeotheruids(4) policy is loaded.
Module name: mac_mls.ko
Kernel configuration line:
options MAC_MLS
Boot option: mac_mls_load="YES"
The mac_mls(4) policy controls access between subjects and objects in the system by enforcing a strict information flow policy.
In MLS environments, a
“clearance” level is set in the label of each
subject or object, along with compartments. Since these
clearance levels can reach numbers greater than several
thousand, it would be a daunting task to thoroughly configure
every subject or object. To ease this administrative
overhead, three labels are included in this policy:
mls/low
, mls/equal
, and
mls/high
, where:
Anything labeled with mls/low
will
have a low clearance level and not be permitted to access
information of a higher level. This label also prevents
objects of a higher clearance level from writing or
passing information to a lower level.
mls/equal
should be placed on
objects which should be exempt from the policy.
mls/high
is the highest level of
clearance possible. Objects assigned this label will hold
dominance over all other objects in the system; however,
they will not permit the leaking of information to objects
of a lower class.
MLS provides:
A hierarchical security level with a set of non-hierarchical categories.
Fixed rules of no read up, no write
down
. This means that a subject can have read
access to objects on its own level or below, but not
above. Similarly, a subject can have write access to
objects on its own level or above, but not beneath.
Secrecy, or the prevention of inappropriate disclosure of data.
A basis for the design of systems that concurrently handle data at multiple sensitivity levels without leaking information between secret and confidential.
The following sysctl
tunables are
available:
security.mac.mls.enabled
is used to
enable or disable the MLS
policy.
security.mac.mls.ptys_equal
labels all pty(4) devices as
mls/equal
during creation.
security.mac.mls.revocation_enabled
revokes access to objects after their label changes to a
label of a lower grade.
security.mac.mls.max_compartments
sets the maximum number of compartment levels allowed on a
system.
To manipulate MLS labels, use setfmac(8). To assign a label to an object:
#
setfmac mls/5 test
To get the MLS label for the file
test
:
#
getfmac test
Another approach is to create a master policy file in
/etc/
which specifies the
MLS policy information and to feed that
file to setfmac
.
When using the MLS policy module, an
administrator plans to control the flow of sensitive
information. The default block read up block write
down
sets everything to a low state. Everything
is accessible and an administrator slowly augments the
confidentiality of the information.
Beyond the three basic label options, an administrator
may group users and groups as required to block the
information flow between them. It might be easier to look at
the information in clearance levels using descriptive words,
such as classifications of Confidential
,
Secret
, and Top Secret
.
Some administrators instead create different groups based on
project levels. Regardless of the classification method, a
well thought out plan must exist before implementing a
restrictive policy.
Some example situations for the MLS policy module include an e-commerce web server, a file server holding critical company information, and financial institution environments.
Module name: mac_biba.ko
Kernel configuration line: options
MAC_BIBA
Boot option: mac_biba_load="YES"
The mac_biba(4) module loads the MAC Biba policy. This policy is similar to the MLS policy with the exception that the rules for information flow are slightly reversed. This is to prevent the downward flow of sensitive information whereas the MLS policy prevents the upward flow of sensitive information.
In Biba environments, an “integrity” label is set on each subject or object. These labels are made up of hierarchical grades and non-hierarchical components. As a grade ascends, so does its integrity.
Supported labels are biba/low
,
biba/equal
, and
biba/high
, where:
biba/low
is considered the lowest
integrity an object or subject may have. Setting this on
objects or subjects blocks their write access to objects
or subjects marked as biba/high
, but
will not prevent read access.
biba/equal
should only be placed on
objects considered to be exempt from the policy.
biba/high
permits writing to
objects set at a lower label, but does not permit reading
that object. It is recommended that this label be
placed on objects that affect the integrity of the entire
system.
Biba provides:
Hierarchical integrity levels with a set of non-hierarchical integrity categories.
Fixed rules are no write up, no read
down
, the opposite of
MLS. A subject can have write access
to objects on its own level or below, but not above.
Similarly, a subject can have read access to objects on
its own level or above, but not below.
Integrity by preventing inappropriate modification of data.
Integrity levels instead of MLS sensitivity levels.
The following tunables can be used to manipulate the Biba policy:
security.mac.biba.enabled
is used
to enable or disable enforcement of the Biba policy on the
target machine.
security.mac.biba.ptys_equal
is
used to disable the Biba policy on pty(4)
devices.
security.mac.biba.revocation_enabled
forces the revocation of access to objects if the label is
changed to dominate the subject.
To access the Biba policy setting on system objects, use
setfmac
and
getfmac
:
#
setfmac biba/low test
#
getfmac test
test: biba/low
Integrity, which is different from sensitivity, is used to guarantee that information is not manipulated by untrusted parties. This includes information passed between subjects and objects. It ensures that users will only be able to modify or access information they have been given explicit access to. The mac_biba(4) security policy module permits an administrator to configure which files and programs a user may see and invoke while assuring that the programs and files are trusted by the system for that user.
During the initial planning phase, an administrator must be prepared to partition users into grades, levels, and areas. The system will default to a high label once this policy module is enabled, and it is up to the administrator to configure the different grades and levels for users. Instead of using clearance levels, a good planning method could include topics. For instance, only allow developers modification access to the source code repository, source code compiler, and other development utilities. Other users would be grouped into other categories such as testers, designers, or end users and would only be permitted read access.
A lower integrity subject is unable to write to a higher integrity subject and a higher integrity subject cannot list or read a lower integrity object. Setting a label at the lowest possible grade could make it inaccessible to subjects. Some prospective environments for this security policy module would include a constrained web server, a development and test machine, and a source code repository. A less useful implementation would be a personal workstation, a machine used as a router, or a network firewall.
Module name: mac_lomac.ko
Kernel configuration line: options
MAC_LOMAC
Boot option:
mac_lomac_load="YES"
Unlike the MAC Biba policy, the mac_lomac(4) policy permits access to lower integrity objects only after decreasing the integrity level to not disrupt any integrity rules.
The Low-watermark integrity policy works almost
identically to Biba, with the exception of using floating
labels to support subject demotion via an auxiliary grade
compartment. This secondary compartment takes the form
[auxgrade]
. When assigning a policy with
an auxiliary grade, use the syntax
lomac/10[2]
, where
2
is the auxiliary grade.
This policy relies on the ubiquitous labeling of all
system objects with integrity labels, permitting subjects to
read from low integrity objects and then downgrading the label
on the subject to prevent future writes to high integrity
objects using [auxgrade]
. The policy may
provide greater compatibility and require less initial
configuration than Biba.
Like the Biba and MLS policies,
setfmac
and setpmac
are used to place labels on system objects:
#
setfmac /usr/home/trhodes lomac/high[low]
#
getfmac /usr/home/trhodes lomac/high[low]
The auxiliary grade low
is a feature
provided only by the MAC
LOMAC policy.
This example considers a relatively small storage system with fewer than fifty users. Users will have login capabilities and are permitted to store data and access resources.
For this scenario, the mac_bsdextended(4) and mac_seeotheruids(4) policy modules could co-exist and block access to system objects while hiding user processes.
Begin by adding the following line to
/boot/loader.conf
:
mac_seeotheruids_load="YES"
The mac_bsdextended(4) security policy module may be
activated by adding this line to
/etc/rc.conf
:
ugidfw_enable="YES"
Default rules stored in
/etc/rc.bsdextended
will be loaded at
system initialization. However, the default entries may need
modification. Since this machine is expected only to service
users, everything may be left commented out except the last
two lines in order to force the loading of user owned system
objects by default.
Add the required users to this machine and reboot. For
testing purposes, try logging in as a different user across
two consoles. Run ps aux
to see if processes
of other users are visible. Verify that running ls(1) on
another user's home directory fails.
Do not try to test with the root
user unless the specific
sysctl
s have been modified to block super
user access.
When a new user is added, their mac_bsdextended(4) rule will not be in the ruleset list. To update the ruleset quickly, unload the security policy module and reload it again using kldunload(8) and kldload(8).
This section demonstrates the steps that are needed to implement the Nagios network monitoring system in a MAC environment. This is meant as an example which still requires the administrator to test that the implemented policy meets the security requirements of the network before using in a production environment.
This example requires multilabel
to be set
on each file system. It also assumes that
net-mgmt/nagios-plugins,
net-mgmt/nagios, and
www/apache22 are all installed, configured,
and working correctly before attempting the integration into the
MAC framework.
Begin the procedure by adding the following user class
to /etc/login.conf
:
insecure:\ :copyright=/etc/COPYRIGHT:\ :welcome=/etc/motd:\ :setenv=MAIL=/var/mail/$,BLOCKSIZE=K:\ :path=~/bin:/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin :manpath=/usr/share/man /usr/local/man:\ :nologin=/usr/sbin/nologin:\ :cputime=1h30m:\ :datasize=8M:\ :vmemoryuse=100M:\ :stacksize=2M:\ :memorylocked=4M:\ :memoryuse=8M:\ :filesize=8M:\ :coredumpsize=8M:\ :openfiles=24:\ :maxproc=32:\ :priority=0:\ :requirehome:\ :passwordtime=91d:\ :umask=022:\ :ignoretime@:\ :label=biba/10(10-10):
Then, add the following line to the default user class section:
:label=biba/high:
Save the edits and issue the following command to rebuild the database:
#
cap_mkdb /etc/login.conf
Set the root
user to the default class using:
#
pw usermod root -L default
All user accounts that are not root
will now require a login
class. The login class is required, otherwise users will be
refused access to common commands. The following
sh
script should do the trick:
#
for x in `awk -F: '($3 >= 1001) && ($3 != 65534) { print $1 }' \
/etc/passwd`; do pw usermod $x -L default; done;
Next, drop the nagios
and www
accounts into the insecure
class:
#
pw usermod nagios -L insecure
#
pw usermod www -L insecure
A contexts file should now be created as
/etc/policy.contexts
:
# This is the default BIBA policy for this system. # System: /var/run(/.*)? biba/equal /dev/(/.*)? biba/equal /var biba/equal /var/spool(/.*)? biba/equal /var/log(/.*)? biba/equal /tmp(/.*)? biba/equal /var/tmp(/.*)? biba/equal /var/spool/mqueue biba/equal /var/spool/clientmqueue biba/equal # For Nagios: /usr/local/etc/nagios(/.*)? biba/10 /var/spool/nagios(/.*)? biba/10 # For apache /usr/local/etc/apache(/.*)? biba/10
This policy enforces security by setting restrictions on
the flow of information. In this specific configuration,
users, including root
, should never be
allowed to access Nagios.
Configuration files and processes that are a part of
Nagios will be completely self
contained or jailed.
This file will be read after running
setfsmac
on every file system. This
example sets the policy on the root file system:
#
setfsmac -ef /etc/policy.contexts /
Next, add these edits to the main section of
/etc/mac.conf
:
default_labels file ?biba default_labels ifnet ?biba default_labels process ?biba default_labels socket ?biba
To finish the configuration, add the following lines to
/boot/loader.conf
:
mac_biba_load="YES" mac_seeotheruids_load="YES" security.mac.biba.trust_all_interfaces=1
And the following line to the network card configuration
stored in /etc/rc.conf
. If the primary
network configuration is done via DHCP,
this may need to be configured manually after every system
boot:
maclabel biba/equal
First, ensure that the web server and
Nagios will not be started on
system initialization and reboot. Ensure that root
cannot access any of the
files in the Nagios configuration
directory. If root
can list the contents of
/var/spool/nagios
, something is wrong.
Instead, a “permission denied” error should be
returned.
If all seems well, Nagios, Apache, and Sendmail can now be started:
#
cd /etc/mail && make stop && \ setpmac biba/equal make start && setpmac biba/10\(10-10\) apachectl start && \ setpmac biba/10\(10-10\) /usr/local/etc/rc.d/nagios.sh forcestart
Double check to ensure that everything is working properly. If not, check the log files for error messages. If needed, use sysctl(8) to disable the mac_biba(4) security policy module and try starting everything again as usual.
The root
user
can still change the security enforcement and edit its
configuration files. The following command will permit the
degradation of the security policy to a lower grade for a
newly spawned shell:
#
setpmac biba/10 csh
To block this from happening, force the user into a
range using login.conf(5). If setpmac(8) attempts
to run a command outside of the compartment's range, an
error will be returned and the command will not be executed.
In this case, set root to
biba/high(high-high)
.
This section discusses common configuration errors and how to resolve them.
multilabel
flag does not stay
enabled on the root (/
)
partition:The following steps may resolve this transient error:
Edit /etc/fstab
and set the
root partition to ro
for
read-only.
Reboot into single user mode.
Run tunefs
-l
enable
on /
.
Reboot the system.
Run mount
-urw
/
and change the
ro
back to rw
in
/etc/fstab
and reboot the system
again.
Double-check the output from
mount
to ensure that
multilabel
has been properly set on
the root file system.
This could be caused by the MAC
partition
policy or by a mislabeling
in one of the MAC labeling policies.
To debug, try the following:
Check the error message. If the user is in the
insecure
class, the
partition
policy may be the
culprit. Try setting the user's class back to the
default
class and rebuild the
database with cap_mkdb
. If this
does not alleviate the problem, go to step two.
Double-check that the label policies are set
correctly for the user,
Xorg, and the
/dev
entries.
If neither of these resolve the problem, send the error message and a description of the environment to the FreeBSD general questions mailing list.
This error can appear when a user attempts to switch
from the root
user to another user in the system. This message
usually occurs when the user has a higher label setting
than that of the user they are attempting to become.
For instance, if joe
has a default label
of biba/low
and root
has a label of
biba/high
, root
cannot view
joe
's home
directory. This will happen whether or not root
has used
su
to become joe
as the Biba
integrity model will not permit root
to view objects set
at a lower integrity level.
root
:When this occurs, whoami
returns
0
and su
returns
who are you?.
This can happen if a labeling policy has been
disabled by sysctl(8) or the policy module was
unloaded. If the policy is disabled, the login
capabilities database needs to be reconfigured. Double
check /etc/login.conf
to ensure
that all label
options have been
removed and rebuild the database with
cap_mkdb
.
This may also happen if a policy restricts access to
master.passwd
. This is usually
caused by an administrator altering the file under a
label which conflicts with the general policy being used
by the system. In these cases, the user information
would be read by the system and access would be blocked
as the file has inherited the new label. Disable the
policy using sysctl(8) and everything should return
to normal.
The FreeBSD operating system includes support for security event auditing. Event auditing supports reliable, fine-grained, and configurable logging of a variety of security-relevant system events, including logins, configuration changes, and file and network access. These log records can be invaluable for live system monitoring, intrusion detection, and postmortem analysis. FreeBSD implements Sun™'s published Basic Security Module (BSM) Application Programming Interface (API) and file format, and is interoperable with the Solaris™ and Mac OS® X audit implementations.
This chapter focuses on the installation and configuration of event auditing. It explains audit policies and provides an example audit configuration.
After reading this chapter, you will know:
What event auditing is and how it works.
How to configure event auditing on FreeBSD for users and processes.
How to review the audit trail using the audit reduction and review tools.
Before reading this chapter, you should:
Understand UNIX® and FreeBSD basics (Chapter 3, FreeBSD Basics).
Be familiar with the basics of kernel configuration/compilation (Chapter 8, Configuring the FreeBSD Kernel).
Have some familiarity with security and how it pertains to FreeBSD (Chapter 13, Security).
The audit facility has some known limitations. Not all security-relevant system events are auditable and some login mechanisms, such as Xorg-based display managers and third-party daemons, do not properly configure auditing for user login sessions.
The security event auditing facility is able to generate
very detailed logs of system activity. On a busy system,
trail file data can be very large when configured for high
detail, exceeding gigabytes a week in some configurations.
Administrators should take into account the disk space
requirements associated with high volume audit configurations.
For example, it may be desirable to dedicate a file system to
/var/audit
so that other file systems are
not affected if the audit file system becomes full.
The following terms are related to security event auditing:
event: an auditable event is any event that can be logged using the audit subsystem. Examples of security-relevant events include the creation of a file, the building of a network connection, or a user logging in. Events are either “attributable”, meaning that they can be traced to an authenticated user, or “non-attributable”. Examples of non-attributable events are any events that occur before authentication in the login process, such as bad password attempts.
class: a named set of related events which are used in selection expressions. Commonly used classes of events include “file creation” (fc), “exec” (ex), and “login_logout” (lo).
record: an audit log entry describing a security event. Records contain a record event type, information on the subject (user) performing the action, date and time information, information on any objects or arguments, and a success or failure condition.
trail: a log file consisting of a series of audit records describing security events. Trails are in roughly chronological order with respect to the time events completed. Only authorized processes are allowed to commit records to the audit trail.
selection expression: a string containing a list of prefixes and audit event class names used to match events.
preselection: the process by which the system identifies which events are of interest to the administrator. The preselection configuration uses a series of selection expressions to identify which classes of events to audit for which users, as well as global settings that apply to both authenticated and unauthenticated processes.
reduction: the process by which records from existing audit trails are selected for preservation, printing, or analysis. Likewise, the process by which undesired audit records are removed from the audit trail. Using reduction, administrators can implement policies for the preservation of audit data. For example, detailed audit trails might be kept for one month, but after that, trails might be reduced in order to preserve only login information for archival purposes.
User space support for event auditing is installed as part
of the base FreeBSD operating system. Kernel support is available
in the GENERIC
kernel by default,
and auditd(8) can be enabled
by adding the following line to
/etc/rc.conf
:
auditd_enable="YES"
Then, start the audit daemon:
#
service auditd start
Users who prefer to compile a custom kernel must include the following line in their custom kernel configuration file:
options AUDIT
Selection expressions are used in a number of places in the audit configuration to determine which events should be audited. Expressions contain a list of event classes to match. Selection expressions are evaluated from left to right, and two expressions are combined by appending one onto the other.
Table 16.1, “Default Audit Event Classes” summarizes the default audit event classes:
Class Name | Description | Action |
---|---|---|
all | all | Match all event classes. |
aa | authentication and authorization | |
ad | administrative | Administrative actions performed on the system as a whole. |
ap | application | Application defined action. |
cl | file close | Audit calls to the
close system call. |
ex | exec | Audit program execution. Auditing of command
line arguments and environmental variables is
controlled via audit_control(5) using the
argv and envv
parameters to the policy
setting. |
fa | file attribute access | Audit the access of object attributes such as stat(1) and pathconf(2). |
fc | file create | Audit events where a file is created as a result. |
fd | file delete | Audit events where file deletion occurs. |
fm | file attribute modify | Audit events where file attribute modification occurs, such as by chown(8), chflags(1), and flock(2). |
fr | file read | Audit events in which data is read or files are opened for reading. |
fw | file write | Audit events in which data is written or files are written or modified. |
io | ioctl | Audit use of the ioctl
system call. |
ip | ipc | Audit various forms of Inter-Process Communication, including POSIX pipes and System V IPC operations. |
lo | login_logout | Audit login(1) and logout(1) events. |
na | non attributable | Audit non-attributable events. |
no | invalid class | Match no audit events. |
nt | network | Audit events related to network actions such as connect(2) and accept(2). |
ot | other | Audit miscellaneous events. |
pc | process | Audit process operations such as exec(3) and exit(3). |
These audit event classes may be customized by modifying
the audit_class
and
audit_event
configuration files.
Each audit event class may be combined with a prefix indicating whether successful/failed operations are matched, and whether the entry is adding or removing matching for the class and type. Table 16.2, “Prefixes for Audit Event Classes” summarizes the available prefixes:
Prefix | Action |
---|---|
+ | Audit successful events in this class. |
- | Audit failed events in this class. |
^ | Audit neither successful nor failed events in this class. |
^+ | Do not audit successful events in this class. |
^- | Do not audit failed events in this class. |
If no prefix is present, both successful and failed instances of the event will be audited.
The following example selection string selects both successful and failed login/logout events, but only successful execution events:
lo,+ex
The following configuration files for security event
auditing are found in
/etc/security
:
audit_class
: contains the
definitions of the audit classes.
audit_control
: controls aspects
of the audit subsystem, such as default audit classes,
minimum disk space to leave on the audit log volume, and
maximum audit trail size.
audit_event
: textual names and
descriptions of system audit events and a list of which
classes each event is in.
audit_user
: user-specific audit
requirements to be combined with the global defaults at
login.
audit_warn
: a customizable shell
script used by auditd(8) to generate warning messages
in exceptional situations, such as when space for audit
records is running low or when the audit trail file has
been rotated.
Audit configuration files should be edited and maintained carefully, as errors in configuration may result in improper logging of events.
In most cases, administrators will only need to modify
audit_control
and
audit_user
. The first file controls
system-wide audit properties and policies and the second file
may be used to fine-tune auditing by user.
A number of defaults for the audit subsystem are
specified in audit_control
:
dir:/var/audit dist:off flags:lo,aa minfree:5 naflags:lo,aa policy:cnt,argv filesz:2M expire-after:10M
The dir
entry is used to set one or
more directories where audit logs will be stored. If more
than one directory entry appears, they will be used in order
as they fill. It is common to configure audit so that audit
logs are stored on a dedicated file system, in order to
prevent interference between the audit subsystem and other
subsystems if the file system fills.
If the dist
field is set to
on
or yes
, hard links
will be created to all trail files in
/var/audit/dist
.
The flags
field sets the system-wide
default preselection mask for attributable events. In the
example above, successful and failed login/logout events as
well as authentication and authorization are audited for all
users.
The minfree
entry defines the minimum
percentage of free space for the file system where the audit
trail is stored.
The naflags
entry specifies audit
classes to be audited for non-attributed events, such as the
login/logout process and authentication and
authorization.
The policy
entry specifies a
comma-separated list of policy flags controlling various
aspects of audit behavior. The cnt
indicates that the system should continue running despite an
auditing failure (this flag is highly recommended). The
other flag, argv
, causes command line
arguments to the execve(2) system call to be audited as
part of command execution.
The filesz
entry specifies the maximum
size for an audit trail before automatically terminating and
rotating the trail file. A value of 0
disables automatic log rotation. If the requested file size
is below the minimum of 512k, it will be ignored and a log
message will be generated.
The expire-after
field specifies when
audit log files will expire and be removed.
The administrator can specify further audit requirements
for specific users in audit_user
.
Each line configures auditing for a user via two fields:
the alwaysaudit
field specifies a set of
events that should always be audited for the user, and the
neveraudit
field specifies a set of
events that should never be audited for the user.
The following example entries audit login/logout events
and successful command execution for root
and file creation and
successful command execution for www
. If used with the
default audit_control
, the
lo
entry for root
is redundant, and
login/logout events will also be audited for www
.
root:lo,+ex:no www:fc,+ex:no
Since audit trails are stored in the BSM
binary format, several built-in tools are available to modify or
convert these trails to text. To convert trail files to a
simple text format, use praudit
. To reduce
the audit trail file for analysis, archiving, or printing
purposes, use auditreduce
. This utility
supports a variety of selection parameters, including event
type, event class, user, date or time of the event, and the file
path or object acted on.
For example, to dump the entire contents of a specified audit log in plain text:
#
praudit /var/audit/
AUDITFILE
Where AUDITFILE
is the audit log
to dump.
Audit trails consist of a series of audit records made up of
tokens, which praudit
prints sequentially,
one per line. Each token is of a specific type, such as
header
(an audit record header) or
path
(a file path from a name lookup). The
following is an example of an
execve
event:
header,133,10,execve(2),0,Mon Sep 25 15:58:03 2006, + 384 msec exec arg,finger,doug path,/usr/bin/finger attribute,555,root,wheel,90,24918,104944 subject,robert,root,wheel,root,wheel,38439,38032,42086,128.232.9.100 return,success,0 trailer,133
This audit represents a successful
execve
call, in which the command
finger doug
has been run. The
exec arg
token contains the processed command
line presented by the shell to the kernel. The
path
token holds the path to the executable
as looked up by the kernel. The attribute
token describes the binary and includes the file mode. The
subject
token stores the audit user ID,
effective user ID and group ID, real user ID and group ID,
process ID, session ID, port ID, and login address. Notice that
the audit user ID and real user ID differ as the user
robert
switched to the
root
account before
running this command, but it is audited using the original
authenticated user. The return
token
indicates the successful execution and the
trailer
concludes the record.
XML output format is also supported and
can be selected by including -x
.
Since audit logs may be very large, a subset of records can
be selected using auditreduce
. This example
selects all audit records produced for the user
trhodes
stored in
AUDITFILE
:
#
auditreduce -u
trhodes
/var/audit/AUDITFILE
| praudit
Members of the audit
group have permission to
read audit trails in /var/audit
. By
default, this group is empty, so only the root
user can read audit trails.
Users may be added to the audit
group in order to
delegate audit review rights. As the ability to track audit log
contents provides significant insight into the behavior of users
and processes, it is recommended that the delegation of audit
review rights be performed with caution.
Audit pipes are cloning pseudo-devices which allow applications to tap the live audit record stream. This is primarily of interest to authors of intrusion detection and system monitoring applications. However, the audit pipe device is a convenient way for the administrator to allow live monitoring without running into problems with audit trail file ownership or log rotation interrupting the event stream. To track the live audit event stream:
#
praudit /dev/auditpipe
By default, audit pipe device nodes are accessible only to
the root
user. To
make them accessible to the members of the audit
group, add a
devfs
rule to
/etc/devfs.rules
:
add path 'auditpipe*' mode 0440 group audit
See devfs.rules(5) for more information on configuring the devfs file system.
It is easy to produce audit event feedback cycles, in
which the viewing of each audit event results in the
generation of more audit events. For example, if all
network I/O is audited, and
praudit
is run from an
SSH session, a continuous stream of audit
events will be generated at a high rate, as each event being
printed will generate another event. For this reason, it is
advisable to run praudit
on an audit pipe
device from sessions without fine-grained
I/O auditing.
Audit trails are written to by the kernel and
managed by the audit daemon, auditd(8).
Administrators should not attempt to use
newsyslog.conf(5) or other tools to directly rotate
audit logs. Instead, audit
should
be used to shut down auditing, reconfigure the audit system,
and perform log rotation. The following command causes the
audit daemon to create a new audit log and signal the kernel
to switch to using the new log. The old log will be
terminated and renamed, at which point it may then be
manipulated by the administrator:
#
audit -n
If auditd(8) is not currently running, this command will fail and an error message will be produced.
Adding the following line to
/etc/crontab
will schedule this rotation
every twelve hours:
0 */12 * * * root /usr/sbin/audit -n
The change will take effect once
/etc/crontab
is saved.
Automatic rotation of the audit trail file based on file
size is possible using filesz
in
audit_control
as described in Section 16.3.2.1, “The audit_control
File”.
As audit trail files can become very large, it is often
desirable to compress or otherwise archive trails once they
have been closed by the audit daemon. The
audit_warn
script can be used to perform
customized operations for a variety of audit-related events,
including the clean termination of audit trails when they are
rotated. For example, the following may be added to
/etc/security/audit_warn
to compress
audit trails on close:
# # Compress audit trail files on close. # if [ "$1" = closefile ]; then gzip -9 $2 fi
Other archiving activities might include copying trail files to a centralized server, deleting old trail files, or reducing the audit trail to remove unneeded records. This script will be run only when audit trail files are cleanly terminated, so will not be run on trails left unterminated following an improper shutdown.
This chapter covers the use of disks and storage media in FreeBSD. This includes SCSI and IDE disks, CD and DVD media, memory-backed disks, and USB storage devices.
After reading this chapter, you will know:
How to add additional hard disks to a FreeBSD system.
How to grow the size of a disk's partition on FreeBSD.
How to configure FreeBSD to use USB storage devices.
How to use CD and DVD media on a FreeBSD system.
How to use the backup programs available under FreeBSD.
How to set up memory disks.
What file system snapshots are and how to use them efficiently.
How to use quotas to limit disk space usage.
How to encrypt disks and swap to secure them against attackers.
How to configure a highly available storage network.
Before reading this chapter, you should:
Know how to configure and install a new FreeBSD kernel.
This section describes how to add a new
SATA disk to a machine that currently only
has a single drive. First, turn off the computer and install
the drive in the computer following the instructions of the
computer, controller, and drive manufacturers. Reboot the
system and become
root
.
Inspect /var/run/dmesg.boot
to ensure
the new disk was found. In this example, the newly added
SATA drive will appear as
ada1
.
For this example, a single large partition will be created on the new disk. The GPT partitioning scheme will be used in preference to the older and less versatile MBR scheme.
If the disk to be added is not blank, old partition
information can be removed with
gpart delete
. See gpart(8) for
details.
The partition scheme is created, and then a single partition is added. To improve performance on newer disks with larger hardware block sizes, the partition is aligned to one megabyte boundaries:
#
gpart create -s GPT ada1
#
gpart add -t freebsd-ufs -a 1M ada1
Depending on use, several smaller partitions may be desired. See gpart(8) for options to create partitions smaller than a whole disk.
The disk partition information can be viewed with
gpart show
:
%
gpart show ada1
=> 34 1465146988 ada1 GPT (699G) 34 2014 - free - (1.0M) 2048 1465143296 1 freebsd-ufs (699G) 1465145344 1678 - free - (839K)
A file system is created in the new partition on the new disk:
#
newfs -U /dev/ada1p1
An empty directory is created as a mountpoint, a location for mounting the new disk in the original disk's file system:
#
mkdir /newdisk
Finally, an entry is added to
/etc/fstab
so the new disk will be mounted
automatically at startup:
/dev/ada1p1 /newdisk ufs rw 2 2
The new disk can be mounted manually, without restarting the system:
#
mount /newdisk
A disk's capacity can increase without any changes to the data already present. This happens commonly with virtual machines, when the virtual disk turns out to be too small and is enlarged. Sometimes a disk image is written to a USB memory stick, but does not use the full capacity. Here we describe how to resize or grow disk contents to take advantage of increased capacity.
Determine the device name of the disk to be resized by
inspecting /var/run/dmesg.boot
. In this
example, there is only one SATA disk in the
system, so the drive will appear as
ada0
.
List the partitions on the disk to see the current configuration:
#
gpart show
=> 34 83886013 ada0 GPT (48G) [CORRUPT] 34 128 1 freebsd-boot (64k) 162 79691648 2 freebsd-ufs (38G) 79691810 4194236 3 freebsd-swap (2G) 83886046 1 - free - (512B)ada0
If the disk was formatted with the
GPT partitioning scheme, it may show
as “corrupted” because the GPT
backup partition table is no longer at the end of the
drive. Fix the backup
partition table with
gpart
:
#
gpart recover
ada0 recoveredada0
Now the additional space on the disk is available for use by a new partition, or an existing partition can be expanded:
#
gpart show
=> 34 102399933 ada0 GPT (48G) 34 128 1 freebsd-boot (64k) 162 79691648 2 freebsd-ufs (38G) 79691810 4194236 3 freebsd-swap (2G) 83886046 18513921 - free - (8.8G)ada0
Partitions can only be resized into contiguous free space. Here, the last partition on the disk is the swap partition, but the second partition is the one that needs to be resized. Swap partitions only contain temporary data, so it can safely be unmounted, deleted, and then recreate the third partition after resizing the second partition.
Disable the swap partition:
#
swapoff
/dev/ada0p3
Delete the third partition, specified by the
-i
flag, from the disk
ada0
.
#
gpart delete -i
ada0p3 deleted3
ada0
#
gpart show
=> 34 102399933 ada0 GPT (48G) 34 128 1 freebsd-boot (64k) 162 79691648 2 freebsd-ufs (38G) 79691810 22708157 - free - (10G)ada0
There is risk of data loss when modifying the partition table of a mounted file system. It is best to perform the following steps on an unmounted file system while running from a live CD-ROM or USB device. However, if absolutely necessary, a mounted file system can be resized after disabling GEOM safety features:
#
sysctl kern.geom.debugflags=16
Resize the partition, leaving room to recreate a swap
partition of the desired size. The partition to resize is
specified with -i
, and the new desired size
with -s
. Optionally, alignment of the
partition is controlled with -a
. This only
modifies the size of the partition. The file system in the
partition will be expanded in a separate step.
#
gpart resize -i
ada0p2 resized2
-s47G
-a 4kada0
#
gpart show
=> 34 102399933 ada0 GPT (48G) 34 128 1 freebsd-boot (64k) 162 98566144 2 freebsd-ufs (47G) 98566306 3833661 - free - (1.8G)ada0
Recreate the swap partition and activate it. If no size
is specified with -s
, all remaining space is
used:
#
gpart add -t freebsd-swap -a 4k
ada0p3 addedada0
#
gpart show
=> 34 102399933 ada0 GPT (48G) 34 128 1 freebsd-boot (64k) 162 98566144 2 freebsd-ufs (47G) 98566306 3833661 3 freebsd-swap (1.8G)ada0
#
swapon
/dev/ada0p3
Grow the UFS file system to use the new capacity of the resized partition:
#
growfs
Device is mounted read-write; resizing will result in temporary write suspension for /. It's strongly recommended to make a backup before growing the file system. OK to grow file system on /dev/ada0p2, mounted on /, from 38GB to 47GB? [Yes/No]/dev/ada0p2
Yes
super-block backups (for fsck -b #) at: 80781312, 82063552, 83345792, 84628032, 85910272, 87192512, 88474752, 89756992, 91039232, 92321472, 93603712, 94885952, 96168192, 97450432
If the file system is ZFS, the resize is
triggered by running the online
subcommand with
-e
:
#
zpool online -e
zroot
/dev/ada0p2
Both the partition and the file system on it have now been resized to use the newly-available disk space.
Many external storage solutions, such as hard drives, USB thumbdrives, and CD and DVD burners, use the Universal Serial Bus (USB). FreeBSD provides support for USB 1.x, 2.0, and 3.0 devices.
USB 3.0 support is not compatible with some hardware, including Haswell (Lynx point) chipsets. If FreeBSD boots with a failed with error 19 message, disable xHCI/USB3 in the system BIOS.
Support for USB storage devices is built
into the GENERIC
kernel. For a custom
kernel, be sure that the following lines are present in the
kernel configuration file:
device scbus # SCSI bus (required for ATA/SCSI) device da # Direct Access (disks) device pass # Passthrough device (direct ATA/SCSI access) device uhci # provides USB 1.x support device ohci # provides USB 1.x support device ehci # provides USB 2.0 support device xhci # provides USB 3.0 support device usb # USB Bus (required) device umass # Disks/Mass storage - Requires scbus and da device cd # needed for CD and DVD burners
FreeBSD uses the umass(4) driver which uses the
SCSI subsystem to access
USB storage devices. Since any
USB device will be seen as a
SCSI device by the system, if the
USB device is a CD or
DVD burner, do not
include device atapicam
in a custom kernel
configuration file.
The rest of this section demonstrates how to verify that a USB storage device is recognized by FreeBSD and how to configure the device so that it can be used.
To test the USB configuration, plug in
the USB device. Use
dmesg
to confirm that the drive appears in
the system message buffer. It should look something like
this:
umass0: <STECH Simple Drive, class 0/0, rev 2.00/1.04, addr 3> on usbus0 umass0: SCSI over Bulk-Only; quirks = 0x0100 umass0:4:0:-1: Attached to scbus4 da0 at umass-sim0 bus 0 scbus4 target 0 lun 0 da0: <STECH Simple Drive 1.04> Fixed Direct Access SCSI-4 device da0: Serial Number WD-WXE508CAN263 da0: 40.000MB/s transfers da0: 152627MB (312581808 512 byte sectors: 255H 63S/T 19457C) da0: quirks=0x2<NO_6_BYTE>
The brand, device node (da0
), speed,
and size will differ according to the device.
Since the USB device is seen as a
SCSI one, camcontrol
can
be used to list the USB storage devices
attached to the system:
#
camcontrol devlist
<STECH Simple Drive 1.04> at scbus4 target 0 lun 0 (pass3,da0)
Alternately, usbconfig
can be used to
list the device. Refer to usbconfig(8) for more
information about this command.
#
usbconfig
ugen0.3: <Simple Drive STECH> at usbus0, cfg=0 md=HOST spd=HIGH (480Mbps) pwr=ON (2mA)
If the device has not been formatted, refer to Section 17.2, “Adding Disks” for instructions on how to format
and create partitions on the USB drive. If
the drive comes with a file system, it can be mounted by
root
using the
instructions in Section 3.7, “Mounting and Unmounting File Systems”.
Allowing untrusted users to mount arbitrary media, by
enabling vfs.usermount
as described
below, should not be considered safe from a security point
of view. Most file systems were not built to safeguard
against malicious devices.
To make the device mountable as a normal user, one
solution is to make all users of the device a member of the
operator
group
using pw(8). Next, ensure that operator
is able to read and
write the device by adding these lines to
/etc/devfs.rules
:
[localrules=5] add path 'da*' mode 0660 group operator
If internal SCSI disks are also installed in the system, change the second line as follows:
add path 'da[3
-9]*' mode 0660 group operator
This will exclude the first three
SCSI disks (da0
to
da2
)from belonging to the operator
group. Replace
3
with the number of internal
SCSI disks. Refer to devfs.rules(5)
for more information about this file.
Next, enable the ruleset in
/etc/rc.conf
:
devfs_system_ruleset="localrules"
Then, instruct the system to allow regular users to mount
file systems by adding the following line to
/etc/sysctl.conf
:
vfs.usermount=1
Since this only takes effect after the next reboot, use
sysctl
to set this variable now:
#
sysctl vfs.usermount=1
vfs.usermount: 0 -> 1
The final step is to create a directory where the file
system is to be mounted. This directory needs to be owned by
the user that is to mount the file system. One way to do that
is for root
to
create a subdirectory owned by that user as /mnt/
.
In the following example, replace
username
username
with the login name of the
user and usergroup
with the user's
primary group:
#
mkdir /mnt/
username
#
chown
username
:usergroup
/mnt/username
Suppose a USB thumbdrive is plugged in,
and a device /dev/da0s1
appears. If the
device is formatted with a FAT file system,
the user can mount it using:
%
mount -t msdosfs -o -m=644,-M=755 /dev/da0s1 /mnt/
username
Before the device can be unplugged, it must be unmounted first:
%
umount /mnt/
username
After device removal, the system message buffer will show messages similar to the following:
umass0: at uhub3, port 2, addr 3 (disconnected) da0 at umass-sim0 bus 0 scbus4 target 0 lun 0 da0: <STECH Simple Drive 1.04> s/n WD-WXE508CAN263 detached (da0:umass-sim0:0:0:0): Periph destroyed
USB devices can be automatically
mounted by uncommenting this line in
/etc/auto_master
:
/media -media -nosuid
Then add these lines to
/etc/devd.conf
:
notify 100 { match "system" "GEOM"; match "subsystem" "DEV"; action "/usr/sbin/automount -c"; };
Reload the configuration if autofs(5) and devd(8) are already running:
#
service automount restart
#
service devd restart
autofs(5) can be set to start at boot by adding this
line to /etc/rc.conf
:
autofs_enable="YES"
autofs(5) requires devd(8) to be enabled, as it is by default.
Start the services immediately with:
#
service automount start
#
service automountd start
#
service autounmountd start
#
service devd start
Each file system that can be automatically mounted appears
as a directory in /media/
. The directory
is named after the file system label. If the label is
missing, the directory is named after the device node.
The file system is transparently mounted on the first access, and unmounted after a period of inactivity. Automounted drives can also be unmounted manually:
#
automount -fu
This mechanism is typically used for memory cards and USB memory sticks. It can be used with any block device, including optical drives or iSCSI LUNs.
Compact Disc (CD) media provide a number of features that differentiate them from conventional disks. They are designed so that they can be read continuously without delays to move the head between tracks. While CD media do have tracks, these refer to a section of data to be read continuously, and not a physical property of the disk. The ISO 9660 file system was designed to deal with these differences.
The FreeBSD Ports Collection provides several utilities for burning and duplicating audio and data CDs. This chapter demonstrates the use of several command line utilities. For CD burning software with a graphical utility, consider installing the sysutils/xcdroast or sysutils/k3b packages or ports.
The GENERIC
kernel provides support
for SCSI, USB, and
ATAPI CD readers and
burners. If a custom kernel is used, the options that need to
be present in the kernel configuration file vary by the type
of device.
For a SCSI burner, make sure these options are present:
device scbus # SCSI bus (required for ATA/SCSI) device da # Direct Access (disks) device pass # Passthrough device (direct ATA/SCSI access) device cd # needed for CD and DVD burners
For a USB burner, make sure these options are present:
device scbus # SCSI bus (required for ATA/SCSI) device da # Direct Access (disks) device pass # Passthrough device (direct ATA/SCSI access) device cd # needed for CD and DVD burners device uhci # provides USB 1.x support device ohci # provides USB 1.x support device ehci # provides USB 2.0 support device xhci # provides USB 3.0 support device usb # USB Bus (required) device umass # Disks/Mass storage - Requires scbus and da
For an ATAPI burner, make sure these options are present:
device ata # Legacy ATA/SATA controllers device scbus # SCSI bus (required for ATA/SCSI) device pass # Passthrough device (direct ATA/SCSI access) device cd # needed for CD and DVD burners
On FreeBSD versions prior to 10.x, this line is also needed in the kernel configuration file if the burner is an ATAPI device:
device atapicam
Alternately, this driver can be loaded at boot time by
adding the following line to
/boot/loader.conf
:
atapicam_load="YES"
This will require a reboot of the system as this driver can only be loaded at boot time.
To verify that FreeBSD recognizes the device, run
dmesg
and look for an entry for the device.
On systems prior to 10.x, the device name in the first line of
the output will be acd0
instead of
cd0
.
%
dmesg | grep cd
cd0 at ahcich1 bus 0 scbus1 target 0 lun 0 cd0: <HL-DT-ST DVDRAM GU70N LT20> Removable CD-ROM SCSI-0 device cd0: Serial Number M3OD3S34152 cd0: 150.000MB/s transfers (SATA 1.x, UDMA6, ATAPI 12bytes, PIO 8192bytes) cd0: Attempt to query device size failed: NOT READY, Medium not present - tray closed
In FreeBSD, cdrecord
can be used to burn
CDs. This command is installed with the
sysutils/cdrtools package or port.
While cdrecord
has many options, basic
usage is simple. Specify the name of the
ISO file to burn and, if the system has
multiple burner devices, specify the name of the device to
use:
#
cdrecord
dev=device
imagefile.iso
To determine the device name of the burner, use
-scanbus
which might produce results like
this:
#
cdrecord -scanbus
ProDVD-ProBD-Clone 3.00 (amd64-unknown-freebsd10.0) Copyright (C) 1995-2010 Jörg Schilling Using libscg version 'schily-0.9' scsibus0: 0,0,0 0) 'SEAGATE ' 'ST39236LW ' '0004' Disk 0,1,0 1) 'SEAGATE ' 'ST39173W ' '5958' Disk 0,2,0 2) * 0,3,0 3) 'iomega ' 'jaz 1GB ' 'J.86' Removable Disk 0,4,0 4) 'NEC ' 'CD-ROM DRIVE:466' '1.26' Removable CD-ROM 0,5,0 5) * 0,6,0 6) * 0,7,0 7) * scsibus1: 1,0,0 100) * 1,1,0 101) * 1,2,0 102) * 1,3,0 103) * 1,4,0 104) * 1,5,0 105) 'YAMAHA ' 'CRW4260 ' '1.0q' Removable CD-ROM 1,6,0 106) 'ARTEC ' 'AM12S ' '1.06' Scanner 1,7,0 107) *
Locate the entry for the CD burner and
use the three numbers separated by commas as the value for
dev
. In this case, the Yamaha burner device
is 1,5,0
, so the appropriate input to
specify that device is dev=1,5,0
. Refer to
the manual page for cdrecord
for other ways
to specify this value and for information on writing audio
tracks and controlling the write speed.
Alternately, run the following command to get the device address of the burner:
#
camcontrol devlist
<MATSHITA CDRW/DVD UJDA740 1.00> at scbus1 target 0 lun 0 (cd0,pass0)
Use the numeric values for scbus
,
target
, and lun
. For
this example, 1,0,0
is the device name to
use.
In order to produce a data CD, the data
files that are going to make up the tracks on the
CD must be prepared before they can be
burned to the CD. In FreeBSD,
sysutils/cdrtools installs
mkisofs
, which can be used to produce an
ISO 9660 file system that is an image of a
directory tree within a UNIX® file system. The simplest
usage is to specify the name of the ISO
file to create and the path to the files to place into the
ISO 9660 file system:
#
mkisofs -o
imagefile.iso
/path/to/tree
This command maps the file names in the specified path to names that fit the limitations of the standard ISO 9660 file system, and will exclude files that do not meet the standard for ISO file systems.
A number of options are available to overcome the
restrictions imposed by the standard. In particular,
-R
enables the Rock Ridge extensions common
to UNIX® systems and -J
enables Joliet
extensions used by Microsoft® systems.
For CDs that are going to be used only
on FreeBSD systems, -U
can be used to disable
all filename restrictions. When used with
-R
, it produces a file system image that is
identical to the specified FreeBSD tree, even if it violates the
ISO 9660 standard.
The last option of general use is -b
.
This is used to specify the location of a boot image for use
in producing an “El Torito” bootable
CD. This option takes an argument which is
the path to a boot image from the top of the tree being
written to the CD. By default,
mkisofs
creates an ISO
image in “floppy disk emulation” mode, and thus
expects the boot image to be exactly 1200, 1440 or
2880 KB in size. Some boot loaders, like the one used by
the FreeBSD distribution media, do not use emulation mode. In
this case, -no-emul-boot
should be used. So,
if /tmp/myboot
holds a bootable FreeBSD
system with the boot image in
/tmp/myboot/boot/cdboot
, this command
would produce
/tmp/bootable.iso
:
#
mkisofs -R -no-emul-boot -b boot/cdboot -o /tmp/bootable.iso /tmp/myboot
The resulting ISO image can be mounted as a memory disk with:
#
mdconfig -a -t vnode -f /tmp/bootable.iso -u 0
#
mount -t cd9660 /dev/md0 /mnt
One can then verify that /mnt
and
/tmp/myboot
are identical.
There are many other options available for
mkisofs
to fine-tune its behavior. Refer
to mkisofs(8) for details.
It is possible to copy a data CD to
an image file that is functionally equivalent to the image
file created with mkisofs
. To do so, use
dd
with the device name as the input
file and the name of the ISO to create as
the output file:
#
dd if=/dev/
cd0
of=file.iso
bs=2048
The resulting image file can be burned to CD as described in Section 17.5.2, “Burning a CD”.
Once an ISO has been burned to a CD, it can be mounted by specifying the file system type, the name of the device containing the CD, and an existing mount point:
#
mount -t cd9660
/dev/cd0
/mnt
Since mount
assumes that a file system
is of type ufs
, a Incorrect
super block error will occur if -t
cd9660
is not included when mounting a data
CD.
While any data CD can be mounted this
way, disks with certain ISO 9660 extensions
might behave oddly. For example, Joliet disks store all
filenames in two-byte Unicode characters. If some non-English
characters show up as question marks, specify the local
charset with -C
. For more information, refer
to mount_cd9660(8).
In order to do this character conversion with the help
of -C
, the kernel requires the
cd9660_iconv.ko
module to be loaded.
This can be done either by adding this line to
loader.conf
:
cd9660_iconv_load="YES"
and then rebooting the machine, or by directly loading
the module with kldload
.
Occasionally, Device not configured will be displayed when trying to mount a data CD. This usually means that the CD drive has not detected a disk in the tray, or that the drive is not visible on the bus. It can take a couple of seconds for a CD drive to detect media, so be patient.
Sometimes, a SCSI CD drive may be missed because it did not have enough time to answer the bus reset. To resolve this, a custom kernel can be created which increases the default SCSI delay. Add the following option to the custom kernel configuration file and rebuild the kernel using the instructions in Section 8.5, “Building and Installing a Custom Kernel”:
options SCSI_DELAY=15000
This tells the SCSI bus to pause 15 seconds during boot, to give the CD drive every possible chance to answer the bus reset.
It is possible to burn a file directly to CD, without creating an ISO 9660 file system. This is known as burning a raw data CD and some people do this for backup purposes.
This type of disk can not be mounted as a normal data CD. In order to retrieve the data burned to such a CD, the data must be read from the raw device node. For example, this command will extract a compressed tar file located on the second CD device into the current working directory:
#
tar xzvf /dev/
cd1
In order to mount a data CD, the
data must be written using
mkisofs
.
To duplicate an audio CD, extract the audio data from the CD to a series of files, then write these files to a blank CD.
Procedure 17.1, “Duplicating an Audio CD” describes how to
duplicate and burn an audio CD. If the
FreeBSD version is less than 10.0 and the device is
ATAPI, the atapicam
module
must be first loaded using the instructions in Section 17.5.1, “Supported Devices”.
The sysutils/cdrtools package or
port installs cdda2wav
. This command
can be used to extract all of the audio tracks, with each
track written to a separate WAV file in
the current working directory:
%
cdda2wav -vall -B -Owav
A device name does not need to be specified if there
is only one CD device on the system.
Refer to the cdda2wav
manual page for
instructions on how to specify a device and to learn more
about the other options available for this command.
Use cdrecord
to write the
.wav
files:
%
cdrecord -v dev=
2,0
-dao -useinfo *.wav
Make sure that 2,0
is set
appropriately, as described in Section 17.5.2, “Burning a CD”.
Compared to the CD, the DVD is the next generation of optical media storage technology. The DVD can hold more data than any CD and is the standard for video publishing.
Five physical recordable formats can be defined for a recordable DVD:
DVD-R: This was the first DVD recordable format available. The DVD-R standard is defined by the DVD Forum. This format is write once.
DVD-RW: This is the rewritable version of the DVD-R standard. A DVD-RW can be rewritten about 1000 times.
DVD-RAM: This is a rewritable format which can be seen as a removable hard drive. However, this media is not compatible with most DVD-ROM drives and DVD-Video players as only a few DVD writers support the DVD-RAM format. Refer to Section 17.6.8, “Using a DVD-RAM” for more information on DVD-RAM use.
DVD+RW: This is a rewritable format defined by the DVD+RW Alliance. A DVD+RW can be rewritten about 1000 times.
DVD+R: This format is the write once variation of the DVD+RW format.
A single layer recordable DVD can hold up to 4,700,000,000 bytes which is actually 4.38 GB or 4485 MB as 1 kilobyte is 1024 bytes.
A distinction must be made between the physical media and the application. For example, a DVD-Video is a specific file layout that can be written on any recordable DVD physical media such as DVD-R, DVD+R, or DVD-RW. Before choosing the type of media, ensure that both the burner and the DVD-Video player are compatible with the media under consideration.
To perform DVD recording, use growisofs(1). This command is part of the sysutils/dvd+rw-tools utilities which support all DVD media types.
These tools use the SCSI subsystem to access the devices, therefore ATAPI/CAM support must be loaded or statically compiled into the kernel. This support is not needed if the burner uses the USB interface. Refer to Section 17.4, “USB Storage Devices” for more details on USB device configuration.
DMA access must also be enabled for
ATAPI devices, by adding the following line
to /boot/loader.conf
:
hw.ata.atapi_dma="1"
Before attempting to use dvd+rw-tools, consult the Hardware Compatibility Notes.
For a graphical user interface, consider using sysutils/k3b which provides a user friendly interface to growisofs(1) and many other burning tools.
Since growisofs(1) is a front-end to mkisofs, it will invoke mkisofs(8) to create the file system layout and perform the write on the DVD. This means that an image of the data does not need to be created before the burning process.
To burn to a DVD+R or a DVD-R the data in
/path/to/data
, use the following
command:
#
growisofs -dvd-compat -Z
/dev/cd0
-J -R/path/to/data
In this example, -J -R
is passed to
mkisofs(8) to create an ISO 9660 file system with Joliet
and Rock Ridge extensions. Refer to mkisofs(8) for more
details.
For the initial session recording, -Z
is
used for both single and multiple sessions. Replace
/dev/cd0
, with the name of the
DVD device. Using
-dvd-compat
indicates that the disk will be
closed and that the recording will be unappendable. This
should also provide better media compatibility with
DVD-ROM drives.
To burn a pre-mastered image, such as
imagefile.iso
, use:
#
growisofs -dvd-compat -Z
/dev/cd0
=imagefile.iso
The write speed should be detected and automatically set
according to the media and the drive being used. To force the
write speed, use -speed=
. Refer to
growisofs(1) for example usage.
In order to support working files larger than 4.38GB, an
UDF/ISO-9660 hybrid file system must be created by passing
-udf -iso-level 3
to mkisofs(8) and
all related programs, such as growisofs(1). This is
required only when creating an ISO image file or when
writing files directly to a disk. Since a disk created this
way must be mounted as an UDF file system with
mount_udf(8), it will be usable only on an UDF aware
operating system. Otherwise it will look as if it contains
corrupted files.
To create this type of ISO file:
%
mkisofs -R -J -udf -iso-level 3 -o
imagefile.iso
/path/to/data
To burn files directly to a disk:
#
growisofs -dvd-compat -udf -iso-level 3 -Z
/dev/cd0
-J -R/path/to/data
When an ISO image already contains large files, no additional options are required for growisofs(1) to burn that image on a disk.
Be sure to use an up-to-date version of sysutils/cdrtools, which contains mkisofs(8), as an older version may not contain large files support. If the latest version does not work, install sysutils/cdrtools-devel and read its mkisofs(8).
A DVD-Video is a specific file layout based on the ISO 9660 and micro-UDF (M-UDF) specifications. Since DVD-Video presents a specific data structure hierarchy, a particular program such as multimedia/dvdauthor is needed to author the DVD.
If an image of the DVD-Video file system already exists,
it can be burned in the same way as any other image. If
dvdauthor
was used to make the
DVD and the result is in
/path/to/video
, the following command
should be used to burn the DVD-Video:
#
growisofs -Z
/dev/cd0
-dvd-video/path/to/video
-dvd-video
is passed to mkisofs(8)
to instruct it to create a DVD-Video file system layout.
This option implies the -dvd-compat
growisofs(1) option.
Unlike CD-RW, a virgin DVD+RW needs to
be formatted before first use. It is
recommended to let growisofs(1) take
care of this automatically whenever appropriate. However, it
is possible to use dvd+rw-format
to format
the DVD+RW:
#
dvd+rw-format
/dev/cd0
Only perform this operation once and keep in mind that only virgin DVD+RW medias need to be formatted. Once formatted, the DVD+RW can be burned as usual.
To burn a totally new file system and not just append some data onto a DVD+RW, the media does not need to be blanked first. Instead, write over the previous recording like this:
#
growisofs -Z
/dev/cd0
-J -R/path/to/newdata
The DVD+RW format supports appending data to a previous recording. This operation consists of merging a new session to the existing one as it is not considered to be multi-session writing. growisofs(1) will grow the ISO 9660 file system present on the media.
For example, to append data to a DVD+RW, use the following:
#
growisofs -M
/dev/cd0
-J -R/path/to/nextdata
The same mkisofs(8) options used to burn the initial session should be used during next writes.
Use -dvd-compat
for better media
compatibility with DVD-ROM drives. When
using DVD+RW, this option will not
prevent the addition of data.
To blank the media, use:
#
growisofs -Z
/dev/cd0
=/dev/zero
A DVD-RW accepts two disc formats: incremental sequential and restricted overwrite. By default, DVD-RW discs are in sequential format.
A virgin DVD-RW can be directly written without being formatted. However, a non-virgin DVD-RW in sequential format needs to be blanked before writing a new initial session.
To blank a DVD-RW in sequential mode:
#
dvd+rw-format -blank=full
/dev/cd0
A full blanking using -blank=full
will
take about one hour on a 1x media. A fast blanking can be
performed using -blank
, if the
DVD-RW will be recorded in Disk-At-Once
(DAO) mode. To burn the DVD-RW in DAO
mode, use the command:
#
growisofs -use-the-force-luke=dao -Z
/dev/cd0
=imagefile.iso
Since growisofs(1) automatically attempts to detect
fast blanked media and engage DAO write,
-use-the-force-luke=dao
should not be
required.
One should instead use restricted overwrite mode with any DVD-RW as this format is more flexible than the default of incremental sequential.
To write data on a sequential DVD-RW, use the same instructions as for the other DVD formats:
#
growisofs -Z
/dev/cd0
-J -R/path/to/data
To append some data to a previous recording, use
-M
with growisofs(1). However, if data
is appended on a DVD-RW in incremental
sequential mode, a new session will be created on the disc and
the result will be a multi-session disc.
A DVD-RW in restricted overwrite format
does not need to be blanked before a new initial session.
Instead, overwrite the disc with -Z
. It is
also possible to grow an existing ISO 9660 file system written
on the disc with -M
. The result will be a
one-session DVD.
To put a DVD-RW in restricted overwrite format, the following command must be used:
#
dvd+rw-format
/dev/cd0
To change back to sequential format, use:
#
dvd+rw-format -blank=full
/dev/cd0
Few DVD-ROM drives support multi-session DVDs and most of the time only read the first session. DVD+R, DVD-R and DVD-RW in sequential format can accept multiple sessions. The notion of multiple sessions does not exist for the DVD+RW and the DVD-RW restricted overwrite formats.
Using the following command after an initial non-closed session on a DVD+R, DVD-R, or DVD-RW in sequential format, will add a new session to the disc:
#
growisofs -M
/dev/cd0
-J -R/path/to/nextdata
Using this command with a DVD+RW or a DVD-RW in restricted overwrite mode will append data while merging the new session to the existing one. The result will be a single-session disc. Use this method to add data after an initial write on these types of media.
Since some space on the media is used between each session to mark the end and start of sessions, one should add sessions with a large amount of data to optimize media space. The number of sessions is limited to 154 for a DVD+R, about 2000 for a DVD-R, and 127 for a DVD+R Double Layer.
To obtain more information about a DVD,
use dvd+rw-mediainfo
while the
disc in the specified drive./dev/cd0
More information about dvd+rw-tools can be found in growisofs(1), on the dvd+rw-tools web site, and in the cdwrite mailing list archives.
When creating a problem report related to the use of
dvd+rw-tools, always include the
output of dvd+rw-mediainfo
.
DVD-RAM writers can use either a
SCSI or ATAPI interface.
For ATAPI devices, DMA access has to be
enabled by adding the following line to
/boot/loader.conf
:
hw.ata.atapi_dma="1"
A DVD-RAM can be seen as a removable hard drive. Like any other hard drive, the DVD-RAM must be formatted before it can be used. In this example, the whole disk space will be formatted with a standard UFS2 file system:
#
dd if=/dev/zero of=
/dev/acd0
bs=2k count=1#
bsdlabel -Bw
acd0
#
newfs
/dev/acd0
The DVD device,
acd0
, must be changed according to the
configuration.
Once the DVD-RAM has been formatted, it can be mounted as a normal hard drive:
#
mount
/dev/acd0
/mnt
Once mounted, the DVD-RAM will be both readable and writeable.
This section explains how to format a 3.5 inch floppy disk in FreeBSD.
A floppy disk needs to be low-level formatted before it can be used. This is usually done by the vendor, but formatting is a good way to check media integrity. To low-level format the floppy disk on FreeBSD, use fdformat(1). When using this utility, make note of any error messages, as these can help determine if the disk is good or bad.
To format the floppy, insert a new 3.5 inch floppy disk into the first floppy drive and issue:
#
/usr/sbin/fdformat -f 1440 /dev/fd0
After low-level formatting the disk, create a disk label
as it is needed by the system to determine the size of the
disk and its geometry. The supported geometry values are
listed in /etc/disktab
.
To write the disk label, use bsdlabel(8):
#
/sbin/bsdlabel -B -w /dev/fd0 fd1440
The floppy is now ready to be high-level formatted with a file system. The floppy's file system can be either UFS or FAT, where FAT is generally a better choice for floppies.
To format the floppy with FAT, issue:
#
/sbin/newfs_msdos /dev/fd0
The disk is now ready for use. To use the floppy, mount it with mount_msdosfs(8). One can also install and use emulators/mtools from the Ports Collection.
Implementing a backup plan is essential in order to have the ability to recover from disk failure, accidental file deletion, random file corruption, or complete machine destruction, including destruction of on-site backups.
The backup type and schedule will vary, depending upon the importance of the data, the granularity needed for file restores, and the amount of acceptable downtime. Some possible backup techniques include:
Archives of the whole system, backed up onto permanent, off-site media. This provides protection against all of the problems listed above, but is slow and inconvenient to restore from, especially for non-privileged users.
File system snapshots, which are useful for restoring deleted files or previous versions of files.
Copies of whole file systems or disks which are synchronized with another system on the network using a scheduled net/rsync.
Hardware or software RAID, which minimizes or avoids downtime when a disk fails.
Typically, a mix of backup techniques is used. For example, one could create a schedule to automate a weekly, full system backup that is stored off-site and to supplement this backup with hourly ZFS snapshots. In addition, one could make a manual backup of individual directories or files before making file edits or deletions.
This section describes some of the utilities which can be used to create and manage backups on a FreeBSD system.
The traditional UNIX® programs for backing up a file
system are dump(8), which creates the backup, and
restore(8), which restores the backup. These utilities
work at the disk block level, below the abstractions of the
files, links, and directories that are created by file
systems. Unlike other backup software,
dump
backs up an entire file system and is
unable to backup only part of a file system or a directory
tree that spans multiple file systems. Instead of writing
files and directories, dump
writes the raw
data blocks that comprise files and directories.
If dump
is used on the root
directory, it will not back up /home
,
/usr
or many other directories since
these are typically mount points for other file systems or
symbolic links into those file systems.
When used to restore data, restore
stores temporary files in /tmp/
by
default. When using a recovery disk with a small
/tmp
, set TMPDIR
to a
directory with more free space in order for the restore to
succeed.
When using dump
, be aware that some
quirks remain from its early days in Version 6 of
AT&T UNIX®,circa 1975. The default parameters assume a
backup to a 9-track tape, rather than to another type of media
or to the high-density tapes available today. These defaults
must be overridden on the command line.
It is possible to backup a file system across the network to a another system or to a tape drive attached to another computer. While the rdump(8) and rrestore(8) utilities can be used for this purpose, they are not considered to be secure.
Instead, one can use dump
and
restore
in a more secure fashion over an
SSH connection. This example creates a
full, compressed backup of /usr
and sends
the backup file to the specified host over a
SSH connection.
dump
over
ssh#
/sbin/dump -0uan -f - /usr | gzip -2 | ssh -c blowfish \ targetuser@targetmachine.example.com dd of=/mybigfiles/dump-usr-l0.gz
This example sets RSH
in order to write the
backup to a tape drive on a remote system over a
SSH connection:
dump
over
ssh with RSH
Set#
env RSH=/usr/bin/ssh /sbin/dump -0uan -f targetuser@targetmachine.example.com:/dev/sa0 /usr
Several built-in utilities are available for backing up and restoring specified files and directories as needed.
A good choice for making a backup of all of the files in a directory is tar(1). This utility dates back to Version 6 of AT&T UNIX® and by default assumes a recursive backup to a local tape device. Switches can be used to instead specify the name of a backup file.
This example creates a compressed backup of the current
directory and saves it to
/tmp/mybackup.tgz
. When creating a
backup file, make sure that the backup is not saved to the
same directory that is being backed up.
To restore the entire backup, cd
into
the directory to restore into and specify the name of the
backup. Note that this will overwrite any newer versions of
files in the restore directory. When in doubt, restore to a
temporary directory or specify the name of the file within the
backup to restore.
There are dozens of available switches which are described in tar(1). This utility also supports the use of exclude patterns to specify which files should not be included when backing up the specified directory or restoring files from a backup.
To create a backup using a specified list of files and
directories, cpio(1) is a good choice. Unlike
tar
, cpio
does not know
how to walk the directory tree and it must be provided the
list of files to backup.
For example, a list of files can be created using
ls
or find
. This
example creates a recursive listing of the current directory
which is then piped to cpio
in order to
create an output backup file named
/tmp/mybackup.cpio
.
ls
and cpio
to Make a Recursive Backup of the Current Directory#
ls -R | cpio -ovF
/tmp/mybackup.cpio
A backup utility which tries to bridge the features
provided by tar
and cpio
is pax(1). Over the years, the various versions of
tar
and cpio
became
slightly incompatible. POSIX® created pax
which attempts to read and write many of the various
cpio
and tar
formats,
plus new formats of its own.
The pax
equivalent to the previous
examples would be:
While tape technology has continued to evolve, modern backup systems tend to combine off-site backups with local removable media. FreeBSD supports any tape drive that uses SCSI, such as LTO or DAT. There is limited support for SATA and USB tape drives.
For SCSI tape devices, FreeBSD uses the
sa(4) driver and the /dev/sa0
,
/dev/nsa0
, and
/dev/esa0
devices. The physical device
name is /dev/sa0
. When
/dev/nsa0
is used, the backup application
will not rewind the tape after writing a file, which allows
writing more than one file to a tape. Using
/dev/esa0
ejects the tape after the
device is closed.
In FreeBSD, mt
is used to control
operations of the tape drive, such as seeking through files on
a tape or writing tape control marks to the tape. For
example, the first three files on a tape can be preserved by
skipping past them before writing a new file:
#
mt -f /dev/nsa0 fsf 3
This utility supports many operations. Refer to mt(1) for details.
To write a single file to tape using
tar
, specify the name of the tape device
and the file to backup:
#
tar cvf /dev/sa0
file
To recover files from a tar
archive
on tape into the current directory:
#
tar xvf /dev/sa0
To backup a UFS file system, use
dump
. This examples backs up
/usr
without rewinding the tape when
finished:
#
dump -0aL -b64 -f /dev/nsa0 /usr
To interactively restore files from a
dump
file on tape into the current
directory:
#
restore -i -f /dev/nsa0
The FreeBSD Ports Collection provides many third-party utilities which can be used to schedule the creation of backups, simplify tape backup, and make backups easier and more convenient. Many of these applications are client/server based and can be used to automate the backups of a single system or all of the computers in a network.
Popular utilities include Amanda, Bacula, rsync, and duplicity.
In addition to regular backups, it is recommended to perform the following steps as part of an emergency preparedness plan.
Create a print copy of the output of the following commands:
gpart show
more /etc/fstab
dmesg
Store this printout and a copy of the installation media
in a secure location. Should an emergency restore be
needed, boot into the installation media and select
Live CD
to access a rescue shell. This
rescue mode can be used to view the current state of the
system, and if needed, to reformat disks and restore data
from backups.
The installation media for
FreeBSD/i386 11.2-RELEASE does not
include a rescue shell. For this version, instead
download and burn a Livefs CD image from
ftp://ftp.FreeBSD.org/pub/FreeBSD/releases/i386/ISO-IMAGES/11.2/FreeBSD-11.2-RELEASE-i386-livefs.iso
.
Next, test the rescue shell and the backups. Make notes of the procedure. Store these notes with the media, the printouts, and the backups. These notes may prevent the inadvertent destruction of the backups while under the stress of performing an emergency recovery.
For an added measure of security, store the latest backup at a remote location which is physically separated from the computers and disk drives by a significant distance.
In addition to physical disks, FreeBSD also supports the creation and use of memory disks. One possible use for a memory disk is to access the contents of an ISO file system without the overhead of first burning it to a CD or DVD, then mounting the CD/DVD media.
In FreeBSD, the md(4) driver is used to provide support
for memory disks. The GENERIC
kernel
includes this driver. When using a custom kernel configuration
file, ensure it includes this line:
device md
To mount an existing file system image, use
mdconfig
to specify the name of the
ISO file and a free unit number. Then,
refer to that unit number to mount it on an existing mount
point. Once mounted, the files in the ISO
will appear in the mount point. This example attaches
diskimage.iso
to the memory device
/dev/md0
then mounts that memory device
on /mnt
:
#
mdconfig -f
diskimage.iso
-u0
#
mount -t cd9660 /dev/md
0
/mnt
Notice that -t cd9660
was used to mount
an ISO format. If a unit number is not specified with
-u
, mdconfig
will
automatically allocate an unused memory device and output
the name of the allocated unit, such as
md4
. Refer to mdconfig(8) for more
details about this command and its options.
When a memory disk is no longer in use, its resources
should be released back to the system. First, unmount the
file system, then use mdconfig
to detach
the disk from the system and release its resources. To
continue this example:
#
umount /mnt
#
mdconfig -d -u
0
To determine if any memory disks are still attached to the
system, type mdconfig -l
.
FreeBSD also supports memory disks where the storage to use
is allocated from either a hard disk or an area of memory.
The first method is commonly referred to as a file-backed file
system and the second method as a memory-backed file system.
Both types can be created using
mdconfig
.
To create a new memory-backed file system, specify a type
of swap
and the size of the memory disk to
create. Then, format the memory disk with a file system and
mount as usual. This example creates a 5M memory disk on unit
1
. That memory disk is then formatted with
the UFS file system before it is
mounted:
#
mdconfig -a -t swap -s
5
m -u1
#
newfs -U md
/dev/md1: 5.0MB (10240 sectors) block size 16384, fragment size 2048 using 4 cylinder groups of 1.27MB, 81 blks, 192 inodes. with soft updates super-block backups (for fsck -b #) at: 160, 2752, 5344, 79361
#
mount /dev/md
1
/mnt
#
df
Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/md1 4718 4 4338 0% /mnt/mnt
To create a new file-backed memory disk, first allocate an
area of disk to use. This example creates an empty 5MB file
named newimage
:
#
dd if=/dev/zero of=
5120+0 records in 5120+0 records outnewimage
bs=1k count=5
k
Next, attach that file to a memory disk, label the memory disk and format it with the UFS file system, mount the memory disk, and verify the size of the file-backed disk:
#
mdconfig -f
newimage
-u0
#
bsdlabel -w md
0
auto#
newfs -U md
/dev/md0a: 5.0MB (10224 sectors) block size 16384, fragment size 2048 using 4 cylinder groups of 1.25MB, 80 blks, 192 inodes. super-block backups (for fsck -b #) at: 160, 2720, 5280, 78400
a#
mount /dev/md
0
a/mnt
#
df
Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/md0a 4710 4 4330 0% /mnt/mnt
It takes several commands to create a file- or
memory-backed file system using mdconfig
.
FreeBSD also comes with mdmfs
which
automatically configures a memory disk, formats it with the
UFS file system, and mounts it. For
example, after creating newimage
with dd
, this one command is equivalent to
running the bsdlabel
,
newfs
, and mount
commands shown above:
#
mdmfs -F
newimage
-s5
m md0
/mnt
To instead create a new memory-based memory disk with
mdmfs
, use this one command:
#
mdmfs -s
5
m md1
/mnt
If the unit number is not specified,
mdmfs
will automatically select an unused
memory device. For more details about
mdmfs
, refer to mdmfs(8).
FreeBSD offers a feature in conjunction with Soft Updates: file system snapshots.
UFS snapshots allow a user to create images of specified file systems, and treat them as a file. Snapshot files must be created in the file system that the action is performed on, and a user may create no more than 20 snapshots per file system. Active snapshots are recorded in the superblock so they are persistent across unmount and remount operations along with system reboots. When a snapshot is no longer required, it can be removed using rm(1). While snapshots may be removed in any order, all the used space may not be acquired because another snapshot will possibly claim some of the released blocks.
The un-alterable snapshot
file flag is set
by mksnap_ffs(8) after initial creation of a snapshot file.
unlink(1) makes an exception for snapshot files since it
allows them to be removed.
Snapshots are created using mount(8). To place a
snapshot of /var
in the
file /var/snapshot/snap
, use the following
command:
#
mount -u -o snapshot /var/snapshot/snap /var
Alternatively, use mksnap_ffs(8) to create the snapshot:
#
mksnap_ffs /var /var/snapshot/snap
One can find snapshot files on a file system, such as
/var
, using
find(1):
#
find /var -flags snapshot
Once a snapshot has been created, it has several uses:
Some administrators will use a snapshot file for backup purposes, because the snapshot can be transferred to CDs or tape.
The file system integrity checker, fsck(8), may be run on the snapshot. Assuming that the file system was clean when it was mounted, this should always provide a clean and unchanging result.
Running dump(8) on the snapshot will produce a dump
file that is consistent with the file system and the
timestamp of the snapshot. dump(8) can also take a
snapshot, create a dump image, and then remove the snapshot
in one command by using -L
.
The snapshot can be mounted as a frozen image of the
file system. To mount(8) the snapshot
/var/snapshot/snap
run:
#
mdconfig -a -t vnode -o readonly -f /var/snapshot/snap -u 4
#
mount -r /dev/md4 /mnt
The frozen /var
is now available
through /mnt
. Everything will initially be
in the same state it was during the snapshot creation time. The
only exception is that any earlier snapshots will appear as zero
length files. To unmount the snapshot, use:
#
umount /mnt
#
mdconfig -d -u 4
For more information about softupdates
and
file system snapshots, including technical papers, visit
Marshall Kirk McKusick's website at http://www.mckusick.com/
.
Disk quotas can be used to limit the amount of disk space or the number of files a user or members of a group may allocate on a per-file system basis. This prevents one user or group of users from consuming all of the available disk space.
This section describes how to configure disk quotas for the UFS file system. To configure quotas on the ZFS file system, refer to Section 19.4.8, “Dataset, User, and Group Quotas”
To determine if the FreeBSD kernel provides support for disk quotas:
%
sysctl kern.features.ufs_quota
kern.features.ufs_quota: 1
In this example, the 1
indicates quota
support. If the value is instead 0
, add
the following line to a custom kernel configuration file and
rebuild the kernel using the instructions in Chapter 8, Configuring the FreeBSD Kernel:
options QUOTA
Next, enable disk quotas in
/etc/rc.conf
:
quota_enable="YES"
Normally on bootup, the quota integrity of each file
system is checked by quotacheck(8). This program insures
that the data in the quota database properly reflects the data
on the file system. This is a time consuming process that
will significantly affect the time the system takes to boot.
To skip this step, add this variable to
/etc/rc.conf
:
check_quotas="NO"
Finally, edit /etc/fstab
to enable
disk quotas on a per-file system basis. To enable per-user
quotas on a file system, add userquota
to the
options field in the /etc/fstab
entry for
the file system to enable quotas on. For example:
/dev/da1s2g /home ufs rw,userquota 1 2
To enable group quotas, use groupquota
instead. To enable both user and group quotas, separate the
options with a comma:
/dev/da1s2g /home ufs rw,userquota,groupquota 1 2
By default, quota files are stored in the root directory
of the file system as quota.user
and
quota.group
. Refer to fstab(5) for
more information. Specifying an alternate location for the
quota files is not recommended.
Once the configuration is complete, reboot the system and
/etc/rc
will automatically run the
appropriate commands to create the initial quota files for all
of the quotas enabled in
/etc/fstab
.
In the normal course of operations, there should be no need to manually run quotacheck(8), quotaon(8), or quotaoff(8). However, one should read these manual pages to be familiar with their operation.
To verify that quotas are enabled, run:
#
quota -v
There should be a one line summary of disk usage and current quota limits for each file system that quotas are enabled on.
The system is now ready to be assigned quota limits with
edquota
.
Several options are available to enforce limits on the amount of disk space a user or group may allocate, and how many files they may create. Allocations can be limited based on disk space (block quotas), number of files (inode quotas), or a combination of both. Each limit is further broken down into two categories: hard and soft limits.
A hard limit may not be exceeded. Once a user reaches a hard limit, no further allocations can be made on that file system by that user. For example, if the user has a hard limit of 500 kbytes on a file system and is currently using 490 kbytes, the user can only allocate an additional 10 kbytes. Attempting to allocate an additional 11 kbytes will fail.
Soft limits can be exceeded for a limited amount of time, known as the grace period, which is one week by default. If a user stays over their limit longer than the grace period, the soft limit turns into a hard limit and no further allocations are allowed. When the user drops back below the soft limit, the grace period is reset.
In the following example, the quota for the test
account is being edited.
When edquota
is invoked, the editor
specified by EDITOR
is opened in order to edit
the quota limits. The default editor is set to
vi.
#
edquota -u test
Quotas for user test: /usr: kbytes in use: 65, limits (soft = 50, hard = 75) inodes in use: 7, limits (soft = 50, hard = 60) /usr/var: kbytes in use: 0, limits (soft = 50, hard = 75) inodes in use: 0, limits (soft = 50, hard = 60)
There are normally two lines for each file system that has
quotas enabled. One line represents the block limits and the
other represents the inode limits. Change the value to modify
the quota limit. For example, to raise the block limit on
/usr
to a soft limit of
500
and a hard limit of
600
, change the values in that line as
follows:
/usr: kbytes in use: 65, limits (soft = 500, hard = 600)
The new quota limits take effect upon exiting the editor.
Sometimes it is desirable to set quota limits on a range
of users. This can be done by first assigning the desired
quota limit to a user. Then, use -p
to
duplicate that quota to a specified range of user IDs
(UIDs). The following command will
duplicate those quota limits for UIDs
10,000
through
19,999
:
#
edquota -p test 10000-19999
For more information, refer to edquota(8).
To check individual user or group quotas and disk usage, use quota(1). A user may only examine their own quota and the quota of a group they are a member of. Only the superuser may view all user and group quotas. To get a summary of all quotas and disk usage for file systems with quotas enabled, use repquota(8).
Normally, file systems that the user is not using any disk
space on will not show in the output of
quota
, even if the user has a quota limit
assigned for that file system. Use -v
to
display those file systems. The following is sample output
from quota -v
for a user that has quota
limits on two file systems.
Disk quotas for user test (uid 1002): Filesystem usage quota limit grace files quota limit grace /usr 65* 50 75 5days 7 50 60 /usr/var 0 50 75 0 50 60
In this example, the user is currently 15 kbytes over the
soft limit of 50 kbytes on /usr
and has 5
days of grace period left. The asterisk *
indicates that the user is currently over the quota
limit.
Quotas are enforced by the quota subsystem on the
NFS server. The rpc.rquotad(8) daemon
makes quota information available to quota
on NFS clients, allowing users on those
machines to see their quota statistics.
On the NFS server, enable
rpc.rquotad
by removing the
#
from this line in
/etc/inetd.conf
:
rquotad/1 dgram rpc/udp wait root /usr/libexec/rpc.rquotad rpc.rquotad
Then, restart inetd
:
#
service inetd restart
FreeBSD offers excellent online protections against unauthorized data access. File permissions and Mandatory Access Control (MAC) help prevent unauthorized users from accessing data while the operating system is active and the computer is powered up. However, the permissions enforced by the operating system are irrelevant if an attacker has physical access to a computer and can move the computer's hard drive to another system to copy and analyze the data.
Regardless of how an attacker may have come into possession
of a hard drive or powered-down computer, the
GEOM-based cryptographic subsystems built
into FreeBSD are able to protect the data on the computer's file
systems against even highly-motivated attackers with significant
resources. Unlike encryption methods that encrypt individual
files, the built-in gbde
and
geli
utilities can be used to transparently
encrypt entire file systems. No cleartext ever touches the hard
drive's platter.
This chapter demonstrates how to create an encrypted file
system on FreeBSD. It first demonstrates the process using
gbde
and then demonstrates the same example
using geli
.
The objective of the gbde(4) facility is to provide a formidable challenge for an attacker to gain access to the contents of a cold storage device. However, if the computer is compromised while up and running and the storage device is actively attached, or the attacker has access to a valid passphrase, it offers no protection to the contents of the storage device. Thus, it is important to provide physical security while the system is running and to protect the passphrase used by the encryption mechanism.
This facility provides several barriers to protect the data stored in each disk sector. It encrypts the contents of a disk sector using 128-bit AES in CBC mode. Each sector on the disk is encrypted with a different AES key. For more information on the cryptographic design, including how the sector keys are derived from the user-supplied passphrase, refer to gbde(4).
FreeBSD provides a kernel module for gbde which can be loaded with this command:
#
kldload geom_bde
If using a custom kernel configuration file, ensure it contains this line:
options GEOM_BDE
The following example demonstrates adding a new hard drive
to a system that will hold a single encrypted partition that
will be mounted as /private
.
Add the New Hard Drive
Install the new drive to the system as explained in
Section 17.2, “Adding Disks”. For the purposes of this
example, a new hard drive partition has been added as
/dev/ad4s1c
and
/dev/ad0s1
represents the existing standard FreeBSD partitions.*
#
ls /dev/ad*
/dev/ad0 /dev/ad0s1b /dev/ad0s1e /dev/ad4s1 /dev/ad0s1 /dev/ad0s1c /dev/ad0s1f /dev/ad4s1c /dev/ad0s1a /dev/ad0s1d /dev/ad4
Create a Directory to Hold gbde
Lock Files
#
mkdir /etc/gbde
The gbde lock file contains information that gbde requires to access encrypted partitions. Without access to the lock file, gbde will not be able to decrypt the data contained in the encrypted partition without significant manual intervention which is not supported by the software. Each encrypted partition uses a separate lock file.
Initialize the gbde
Partition
A gbde partition must be initialized before it can be used. This initialization needs to be performed only once. This command will open the default editor, in order to set various configuration options in a template. For use with the UFS file system, set the sector_size to 2048:
#
gbde init /dev/ad4s1c -i -L /etc/gbde/ad4s1c.lock
# $FreeBSD: src/sbin/gbde/template.txt,v 1.1.36.1 2009/08/03 08:13:06 kensmith Exp $ # # Sector size is the smallest unit of data which can be read or written. # Making it too small decreases performance and decreases available space. # Making it too large may prevent filesystems from working. 512 is the # minimum and always safe. For UFS, use the fragment size # sector_size = 2048 [...]
Once the edit is saved, the user will be asked twice to type the passphrase used to secure the data. The passphrase must be the same both times. The ability of gbde to protect data depends entirely on the quality of the passphrase. For tips on how to select a secure passphrase that is easy to remember, see http://world.std.com/~reinhold/diceware.htm.
This initialization creates a lock file for the
gbde partition. In this
example, it is stored as
/etc/gbde/ad4s1c.lock
. Lock files
must end in “.lock” in order to be correctly
detected by the /etc/rc.d/gbde
start
up script.
Lock files must be backed up together with the contents of any encrypted partitions. Without the lock file, the legitimate owner will be unable to access the data on the encrypted partition.
Attach the Encrypted Partition to the Kernel
#
gbde attach /dev/ad4s1c -l /etc/gbde/ad4s1c.lock
This command will prompt to input the passphrase that
was selected during the initialization of the encrypted
partition. The new encrypted device will appear in
/dev
as
/dev/device_name.bde
:
#
ls /dev/ad*
/dev/ad0 /dev/ad0s1b /dev/ad0s1e /dev/ad4s1 /dev/ad0s1 /dev/ad0s1c /dev/ad0s1f /dev/ad4s1c /dev/ad0s1a /dev/ad0s1d /dev/ad4 /dev/ad4s1c.bde
Create a File System on the Encrypted Device
Once the encrypted device has been attached to the
kernel, a file system can be created on the device. This
example creates a UFS file system with
soft updates enabled. Be sure to specify the partition
which has a
extension:*
.bde
#
newfs -U /dev/ad4s1c.bde
Mount the Encrypted Partition
Create a mount point and mount the encrypted file system:
#
mkdir /private
#
mount /dev/ad4s1c.bde /private
Verify That the Encrypted File System is Available
The encrypted file system should now be visible and available for use:
%
df -H
Filesystem Size Used Avail Capacity Mounted on /dev/ad0s1a 1037M 72M 883M 8% / /devfs 1.0K 1.0K 0B 100% /dev /dev/ad0s1f 8.1G 55K 7.5G 0% /home /dev/ad0s1e 1037M 1.1M 953M 0% /tmp /dev/ad0s1d 6.1G 1.9G 3.7G 35% /usr /dev/ad4s1c.bde 150G 4.1K 138G 0% /private
After each boot, any encrypted file systems must be
manually re-attached to the kernel, checked for errors, and
mounted, before the file systems can be used. To configure
these steps, add the following lines to
/etc/rc.conf
:
gbde_autoattach_all="YES"
gbde_devices="ad4s1c
"
gbde_lockdir="/etc/gbde"
This requires that the passphrase be entered at the console at boot time. After typing the correct passphrase, the encrypted partition will be mounted automatically. Additional gbde boot options are available and listed in rc.conf(5).
sysinstall is incompatible
with gbde-encrypted devices. All
*.bde
devices must be detached from the
kernel before starting sysinstall
or it will crash during its initial probing for devices. To
detach the encrypted device used in the example, use the
following command:
#
gbde detach /dev/
ad4s1c
An alternative cryptographic GEOM class
is available using geli
. This control
utility adds some features and uses a different scheme for
doing cryptographic work. It provides the following
features:
Utilizes the crypto(9) framework and automatically uses cryptographic hardware when it is available.
Supports multiple cryptographic algorithms such as AES, Blowfish, and 3DES.
Allows the root partition to be encrypted. The passphrase used to access the encrypted root partition will be requested during system boot.
Allows the use of two independent keys.
It is fast as it performs simple sector-to-sector encryption.
Allows backup and restore of master keys. If a user destroys their keys, it is still possible to get access to the data by restoring keys from the backup.
Allows a disk to attach with a random, one-time key which is useful for swap partitions and temporary file systems.
More features and usage examples can be found in geli(8).
The following example describes how to generate a key file
which will be used as part of the master key for the encrypted
provider mounted under /private
. The key
file will provide some random data used to encrypt the master
key. The master key will also be protected by a passphrase.
The provider's sector size will be 4kB. The example describes
how to attach to the geli
provider, create
a file system on it, mount it, work with it, and finally, how
to detach it.
geli
Load geli
Support
Support for geli
is available as a
loadable kernel module. To configure the system to
automatically load the module at boot time, add the
following line to
/boot/loader.conf
:
geom_eli_load="YES"
To load the kernel module now:
#
kldload geom_eli
For a custom kernel, ensure the kernel configuration file contains these lines:
options GEOM_ELI device crypto
Generate the Master Key
The following commands generate a master key
(/root/da2.key
) that is protected
with a passphrase. The data source for the key file is
/dev/random
and the sector size of
the provider (/dev/da2.eli
) is 4kB as
a bigger sector size provides better performance:
#
dd if=/dev/random of=/root/da2.key bs=64 count=1
#
geli init -s 4096 -K /root/da2.key /dev/da2
Enter new passphrase: Reenter new passphrase:
It is not mandatory to use both a passphrase and a key file as either method of securing the master key can be used in isolation.
If the key file is given as “-”, standard input will be used. For example, this command generates three key files:
#
cat keyfile1 keyfile2 keyfile3 | geli init -K - /dev/da2
Attach the Provider with the Generated Key
To attach the provider, specify the key file, the name of the disk, and the passphrase:
#
geli attach -k /root/da2.key /dev/da2
Enter passphrase:
This creates a new device with an
.eli
extension:
#
ls /dev/da2*
/dev/da2 /dev/da2.eli
Create the New File System
Next, format the device with the UFS file system and mount it on an existing mount point:
#
dd if=/dev/random of=/dev/da2.eli bs=1m
#
newfs /dev/da2.eli
#
mount /dev/da2.eli
/private
The encrypted file system should now be available for use:
#
df -H
Filesystem Size Used Avail Capacity Mounted on /dev/ad0s1a 248M 89M 139M 38% / /devfs 1.0K 1.0K 0B 100% /dev /dev/ad0s1f 7.7G 2.3G 4.9G 32% /usr /dev/ad0s1d 989M 1.5M 909M 0% /tmp /dev/ad0s1e 3.9G 1.3G 2.3G 35% /var /dev/da2.eli 150G 4.1K 138G 0% /private
Once the work on the encrypted partition is done, and the
/private
partition is no longer needed,
it is prudent to put the device into cold storage by
unmounting and detaching the geli
encrypted
partition from the kernel:
#
umount /private
#
geli detach da2.eli
A rc.d
script is provided to
simplify the mounting of geli
-encrypted
devices at boot time. For this example, add these lines to
/etc/rc.conf
:
geli_devices="da2
" geli_da2_flags="-k /root/da2.key
"
This configures /dev/da2
as a
geli
provider with a master key of
/root/da2.key
. The system will
automatically detach the provider from the kernel before the
system shuts down. During the startup process, the script
will prompt for the passphrase before attaching the provider.
Other kernel messages might be shown before and after the
password prompt. If the boot process seems to stall, look
carefully for the password prompt among the other messages.
Once the correct passphrase is entered, the provider is
attached. The file system is then mounted, typically by an
entry in /etc/fstab
. Refer to Section 3.7, “Mounting and Unmounting File Systems” for instructions on how to
configure a file system to mount at boot time.
Like the encryption of disk partitions, encryption of swap space is used to protect sensitive information. Consider an application that deals with passwords. As long as these passwords stay in physical memory, they are not written to disk and will be cleared after a reboot. However, if FreeBSD starts swapping out memory pages to free space, the passwords may be written to the disk unencrypted. Encrypting swap space can be a solution for this scenario.
This section demonstrates how to configure an encrypted
swap partition using gbde(8) or geli(8) encryption.
It assumes that
/dev/ada0s1b
is the swap partition.
Swap partitions are not encrypted by default and should be cleared of any sensitive data before continuing. To overwrite the current swap partition with random garbage, execute the following command:
#
dd if=/dev/random of=/dev/
ada0s1b
bs=1m
To encrypt the swap partition using gbde(8), add the
.bde
suffix to the swap line in
/etc/fstab
:
# Device Mountpoint FStype Options Dump Pass# /dev/ada0s1b.bde none swap sw 0 0
To instead encrypt the swap partition using geli(8),
use the
.eli
suffix:
# Device Mountpoint FStype Options Dump Pass# /dev/ada0s1b.eli none swap sw 0 0
By default, geli(8) uses the AES
algorithm with a key length of 128 bits. Normally the default
settings will suffice. If desired, these defaults can be
altered in the options field in
/etc/fstab
. The possible flags
are:
Data integrity verification algorithm used to ensure that the encrypted data has not been tampered with. See geli(8) for a list of supported algorithms.
Encryption algorithm used to protect the data. See geli(8) for a list of supported algorithms.
The length of the key used for the encryption algorithm. See geli(8) for the key lengths that are supported by each encryption algorithm.
The size of the blocks data is broken into before it is encrypted. Larger sector sizes increase performance at the cost of higher storage overhead. The recommended size is 4096 bytes.
This example configures an encrypted swap partition using the Blowfish algorithm with a key length of 128 bits and a sectorsize of 4 kilobytes:
# Device Mountpoint FStype Options Dump Pass# /dev/ada0s1b.eli none swap sw,ealgo=blowfish,keylen=128,sectorsize=4096 0 0
Once the system has rebooted, proper operation of the
encrypted swap can be verified using
swapinfo
.
If gbde(8) is being used:
%
swapinfo
Device 1K-blocks Used Avail Capacity /dev/ada0s1b.bde 542720 0 542720 0%
If geli(8) is being used:
%
swapinfo
Device 1K-blocks Used Avail Capacity /dev/ada0s1b.eli 542720 0 542720 0%
High availability is one of the main requirements in serious business applications and highly-available storage is a key component in such environments. In FreeBSD, the Highly Available STorage (HAST) framework allows transparent storage of the same data across several physically separated machines connected by a TCP/IP network. HAST can be understood as a network-based RAID1 (mirror), and is similar to the DRBD® storage system used in the GNU/Linux® platform. In combination with other high-availability features of FreeBSD like CARP, HAST makes it possible to build a highly-available storage cluster that is resistant to hardware failures.
The following are the main features of HAST:
Can be used to mask I/O errors on local hard drives.
File system agnostic as it works with any file system supported by FreeBSD.
Efficient and quick resynchronization as only the blocks that were modified during the downtime of a node are synchronized.
Can be used in an already deployed environment to add additional redundancy.
Together with CARP, Heartbeat, or other tools, it can be used to build a robust and durable storage system.
After reading this section, you will know:
What HAST is, how it works, and which features it provides.
How to set up and use HAST on FreeBSD.
How to integrate CARP and devd(8) to build a robust storage system.
Before reading this section, you should:
Understand UNIX® and FreeBSD basics (Chapter 3, FreeBSD Basics).
Know how to configure network interfaces and other core FreeBSD subsystems (Chapter 11, Configuration and Tuning).
Have a good understanding of FreeBSD networking (Part IV, “Network Communication”).
The HAST project was sponsored by The FreeBSD Foundation with support from http://www.omc.net/ and http://www.transip.nl/.
HAST provides synchronous block-level replication between two physical machines: the primary, also known as the master node, and the secondary, or slave node. These two machines together are referred to as a cluster.
Since HAST works in a primary-secondary configuration, it allows only one of the cluster nodes to be active at any given time. The primary node, also called active, is the one which will handle all the I/O requests to HAST-managed devices. The secondary node is automatically synchronized from the primary node.
The physical components of the HAST system are the local disk on primary node, and the disk on the remote, secondary node.
HAST operates synchronously on a block
level, making it transparent to file systems and applications.
HAST provides regular GEOM providers in
/dev/hast/
for use by other tools or
applications. There is no difference between using
HAST-provided devices and raw disks or
partitions.
Each write, delete, or flush operation is sent to both the local disk and to the remote disk over TCP/IP. Each read operation is served from the local disk, unless the local disk is not up-to-date or an I/O error occurs. In such cases, the read operation is sent to the secondary node.
HAST tries to provide fast failure recovery. For this reason, it is important to reduce synchronization time after a node's outage. To provide fast synchronization, HAST manages an on-disk bitmap of dirty extents and only synchronizes those during a regular synchronization, with an exception of the initial sync.
There are many ways to handle synchronization. HAST implements several replication modes to handle different synchronization methods:
memsync: This mode reports a write operation as completed when the local write operation is finished and when the remote node acknowledges data arrival, but before actually storing the data. The data on the remote node will be stored directly after sending the acknowledgement. This mode is intended to reduce latency, but still provides good reliability. This mode is the default.
fullsync: This mode reports a write operation as completed when both the local write and the remote write complete. This is the safest and the slowest replication mode.
async: This mode reports a write operation as completed when the local write completes. This is the fastest and the most dangerous replication mode. It should only be used when replicating to a distant node where latency is too high for other modes.
The HAST framework consists of several components:
The hastd(8) daemon which provides data
synchronization. When this daemon is started, it will
automatically load geom_gate.ko
.
The userland management utility, hastctl(8).
The hast.conf(5) configuration file. This file must exist before starting hastd.
Users who prefer to statically build
GEOM_GATE
support into the kernel should
add this line to the custom kernel configuration file, then
rebuild the kernel using the instructions in Chapter 8, Configuring the FreeBSD Kernel:
options GEOM_GATE
The following example describes how to configure two nodes
in master-slave/primary-secondary operation using
HAST to replicate the data between the two.
The nodes will be called hasta
, with an
IP address of
172.16.0.1
, and hastb
,
with an IP address of
172.16.0.2
. Both nodes will have a
dedicated hard drive /dev/ad6
of the same
size for HAST operation. The
HAST pool, sometimes referred to as a
resource or the GEOM provider in /dev/hast/
, will be called
test
.
Configuration of HAST is done using
/etc/hast.conf
. This file should be
identical on both nodes. The simplest configuration
is:
resourcetest
{ onhasta
{ local/dev/ad6
remote172.16.0.2
} onhastb
{ local/dev/ad6
remote172.16.0.1
} }
For more advanced configuration, refer to hast.conf(5).
It is also possible to use host names in the
remote
statements if the hosts are
resolvable and defined either in
/etc/hosts
or in the local
DNS.
Once the configuration exists on both nodes, the HAST pool can be created. Run these commands on both nodes to place the initial metadata onto the local disk and to start hastd(8):
#
hastctl create
test
#
service hastd onestart
It is not possible to use GEOM providers with an existing file system or to convert an existing storage to a HAST-managed pool. This procedure needs to store some metadata on the provider and there will not be enough required space available on an existing provider.
A HAST node's primary
or
secondary
role is selected by an
administrator, or software like
Heartbeat, using hastctl(8).
On the primary node, hasta
, issue this
command:
#
hastctl role primary
test
Run this command on the secondary node,
hastb
:
#
hastctl role secondary
test
Verify the result by running hastctl
on
each node:
#
hastctl status
test
Check the status
line in the output.
If it says degraded
, something is wrong
with the configuration file. It should say
complete
on each node, meaning that the
synchronization between the nodes has started. The
synchronization completes when hastctl
status
reports 0 bytes of dirty
extents.
The next step is to create a file system on the
GEOM provider and mount it. This must be
done on the primary
node. Creating the
file system can take a few minutes, depending on the size of
the hard drive. This example creates a UFS
file system on /dev/hast/test
:
#
newfs -U /dev/hast/
test
#
mkdir /hast/
test
#
mount /dev/hast/
test
/hast/test
Once the HAST framework is configured
properly, the final step is to make sure that
HAST is started automatically during
system boot. Add this line to
/etc/rc.conf
:
hastd_enable="YES"
The goal of this example is to build a robust storage system which is resistant to the failure of any given node. If the primary node fails, the secondary node is there to take over seamlessly, check and mount the file system, and continue to work without missing a single bit of data.
To accomplish this task, the Common Address Redundancy
Protocol (CARP) is used to provide for
automatic failover at the IP layer.
CARP allows multiple hosts on the same
network segment to share an IP address.
Set up CARP on both nodes of the cluster
according to the documentation available in Section 31.10, “Common Address Redundancy Protocol
(CARP)”. In this example, each node will have
its own management IP address and a
shared IP address of
172.16.0.254
. The primary
HAST node of the cluster must be the
master CARP node.
The HAST pool created in the previous
section is now ready to be exported to the other hosts on
the network. This can be accomplished by exporting it
through NFS or
Samba, using the shared
IP address
172.16.0.254
. The only problem
which remains unresolved is an automatic failover should the
primary node fail.
In the event of CARP interfaces going up or down, the FreeBSD operating system generates a devd(8) event, making it possible to watch for state changes on the CARP interfaces. A state change on the CARP interface is an indication that one of the nodes failed or came back online. These state change events make it possible to run a script which will automatically handle the HAST failover.
To catch state changes on the
CARP interfaces, add this configuration
to /etc/devd.conf
on each node:
notify 30 { match "system" "IFNET"; match "subsystem" "carp0"; match "type" "LINK_UP"; action "/usr/local/sbin/carp-hast-switch master"; }; notify 30 { match "system" "IFNET"; match "subsystem" "carp0"; match "type" "LINK_DOWN"; action "/usr/local/sbin/carp-hast-switch slave"; };
If the systems are running FreeBSD 10 or higher,
replace carp0
with the name of the
CARP-configured interface.
Restart devd(8) on both nodes to put the new configuration into effect:
#
service devd restart
When the specified interface state changes by going up
or down , the system generates a notification, allowing the
devd(8) subsystem to run the specified automatic
failover script,
/usr/local/sbin/carp-hast-switch
.
For further clarification about this configuration, refer to
devd.conf(5).
Here is an example of an automated failover script:
#!/bin/sh
# Original script by Freddie Cash <fjwcash@gmail.com>
# Modified by Michael W. Lucas <mwlucas@BlackHelicopters.org>
# and Viktor Petersson <vpetersson@wireload.net>
# The names of the HAST resources, as listed in /etc/hast.conf
resources="test
"
# delay in mounting HAST resource after becoming master
# make your best guess
delay=3
# logging
log="local0.debug"
name="carp-hast"
# end of user configurable stuff
case "$1" in
master)
logger -p $log -t $name "Switching to primary provider for ${resources}."
sleep ${delay}
# Wait for any "hastd secondary" processes to stop
for disk in ${resources}; do
while $( pgrep -lf "hastd: ${disk} \(secondary\)" > /dev/null 2>&1 ); do
sleep 1
done
# Switch role for each disk
hastctl role primary ${disk}
if [ $? -ne 0 ]; then
logger -p $log -t $name "Unable to change role to primary for resource ${disk}."
exit 1
fi
done
# Wait for the /dev/hast/* devices to appear
for disk in ${resources}; do
for I in $( jot 60 ); do
[ -c "/dev/hast/${disk}" ] && break
sleep 0.5
done
if [ ! -c "/dev/hast/${disk}" ]; then
logger -p $log -t $name "GEOM provider /dev/hast/${disk} did not appear."
exit 1
fi
done
logger -p $log -t $name "Role for HAST resources ${resources} switched to primary."
logger -p $log -t $name "Mounting disks."
for disk in ${resources}; do
mkdir -p /hast/${disk}
fsck -p -y -t ufs /dev/hast/${disk}
mount /dev/hast/${disk} /hast/${disk}
done
;;
slave)
logger -p $log -t $name "Switching to secondary provider for ${resources}."
# Switch roles for the HAST resources
for disk in ${resources}; do
if ! mount | grep -q "^/dev/hast/${disk} on "
then
else
umount -f /hast/${disk}
fi
sleep $delay
hastctl role secondary ${disk} 2>&1
if [ $? -ne 0 ]; then
logger -p $log -t $name "Unable to switch role to secondary for resource ${disk}."
exit 1
fi
logger -p $log -t $name "Role switched to secondary for resource ${disk}."
done
;;
esac
In a nutshell, the script takes these actions when a node becomes master:
Promotes the HAST pool to primary on the other node.
Checks the file system under the HAST pool.
Mounts the pool.
When a node becomes secondary:
Unmounts the HAST pool.
Degrades the HAST pool to secondary.
This is just an example script which serves as a proof of concept. It does not handle all the possible scenarios and can be extended or altered in any way, for example, to start or stop required services.
For this example, a standard UFS file system was used. To reduce the time needed for recovery, a journal-enabled UFS or ZFS file system can be used instead.
More detailed information with additional examples can be found at http://wiki.FreeBSD.org/HAST.
HAST should generally work without issues. However, as with any other software product, there may be times when it does not work as supposed. The sources of the problems may be different, but the rule of thumb is to ensure that the time is synchronized between the nodes of the cluster.
When troubleshooting HAST, the
debugging level of hastd(8) should be increased by
starting hastd
with -d
.
This argument may be specified multiple times to further
increase the debugging level. Consider also using
-F
, which starts hastd
in the foreground.
Split-brain occurs when the nodes of the cluster are unable to communicate with each other, and both are configured as primary. This is a dangerous condition because it allows both nodes to make incompatible changes to the data. This problem must be corrected manually by the system administrator.
The administrator must either decide which node has more important changes, or perform the merge manually. Then, let HAST perform full synchronization of the node which has the broken data. To do this, issue these commands on the node which needs to be resynchronized:
#
hastctl role init
test
#
hastctl create
test
#
hastctl role secondary
test
In FreeBSD, the GEOM framework permits
access and control to classes, such as Master Boot Records and
BSD labels, through the use of providers, or
the disk devices in /dev
. By supporting
various software RAID configurations,
GEOM transparently provides access to the
operating system and operating system utilities.
This chapter covers the use of disks under the GEOM framework in FreeBSD. This includes the major RAID control utilities which use the framework for configuration. This chapter is not a definitive guide to RAID configurations and only GEOM-supported RAID classifications are discussed.
After reading this chapter, you will know:
What type of RAID support is available through GEOM.
How to use the base utilities to configure, maintain, and manipulate the various RAID levels.
How to mirror, stripe, encrypt, and remotely connect disk devices through GEOM.
How to troubleshoot disks attached to the GEOM framework.
Before reading this chapter, you should:
Understand how FreeBSD treats disk devices (Chapter 17, Storage).
Know how to configure and install a new kernel (Chapter 8, Configuring the FreeBSD Kernel).
Striping combines several disk drives into a single volume. Striping can be performed through the use of hardware RAID controllers. The GEOM disk subsystem provides software support for disk striping, also known as RAID0, without the need for a RAID disk controller.
In RAID0, data is split into blocks that are written across all the drives in the array. As seen in the following illustration, instead of having to wait on the system to write 256k to one disk, RAID0 can simultaneously write 64k to each of the four disks in the array, offering superior I/O performance. This performance can be enhanced further by using multiple disk controllers.
Each disk in a RAID0 stripe must be of the same size, since I/O requests are interleaved to read or write to multiple disks in parallel.
RAID0 does not provide any redundancy. This means that if one disk in the array fails, all of the data on the disks is lost. If the data is important, implement a backup strategy that regularly saves backups to a remote system or device.
The process for creating a software, GEOM-based RAID0 on a FreeBSD system using commodity disks is as follows. Once the stripe is created, refer to gstripe(8) for more information on how to control an existing stripe.
Load the geom_stripe.ko
module:
#
kldload geom_stripe
Ensure that a suitable mount point exists. If this
volume will become a root partition, then temporarily use
another mount point such as
/mnt
.
Determine the device names for the disks which will
be striped, and create the new stripe device. For example,
to stripe two unused and unpartitioned
ATA disks with device names of
/dev/ad2
and
/dev/ad3
:
#
gstripe label -v st0 /dev/ad2 /dev/ad3
Metadata value stored on /dev/ad2. Metadata value stored on /dev/ad3. Done.
Write a standard label, also known as a partition table, on the new volume and install the default bootstrap code:
#
bsdlabel -wB /dev/stripe/st0
This process should create two other devices in
/dev/stripe
in addition to
st0
. Those include
st0a
and st0c
. At
this point, a UFS file system can be
created on st0a
using
newfs
:
#
newfs -U /dev/stripe/st0a
Many numbers will glide across the screen, and after a few seconds, the process will be complete. The volume has been created and is ready to be mounted.
To manually mount the created disk stripe:
#
mount /dev/stripe/st0a /mnt
To mount this striped file system automatically during
the boot process, place the volume information in
/etc/fstab
. In this example, a
permanent mount point, named stripe
, is
created:
#
mkdir /stripe
#
echo "/dev/stripe/st0a /stripe ufs rw 2 2" \
>> /etc/fstab
The geom_stripe.ko
module must also
be automatically loaded during system initialization, by
adding a line to
/boot/loader.conf
:
#
sysrc -f /boot/loader.conf geom_stripe_load=YES
RAID1, or mirroring, is the technique of writing the same data to more than one disk drive. Mirrors are usually used to guard against data loss due to drive failure. Each drive in a mirror contains an identical copy of the data. When an individual drive fails, the mirror continues to work, providing data from the drives that are still functioning. The computer keeps running, and the administrator has time to replace the failed drive without user interruption.
Two common situations are illustrated in these examples. The first creates a mirror out of two new drives and uses it as a replacement for an existing single drive. The second example creates a mirror on a single new drive, copies the old drive's data to it, then inserts the old drive into the mirror. While this procedure is slightly more complicated, it only requires one new drive.
Traditionally, the two drives in a mirror are identical in model and capacity, but gmirror(8) does not require that. Mirrors created with dissimilar drives will have a capacity equal to that of the smallest drive in the mirror. Extra space on larger drives will be unused. Drives inserted into the mirror later must have at least as much capacity as the smallest drive already in the mirror.
The mirroring procedures shown here are non-destructive, but as with any major disk operation, make a full backup first.
While dump(8) is used in these procedures to copy file systems, it does not work on file systems with soft updates journaling. See tunefs(8) for information on detecting and disabling soft updates journaling.
Many disk systems store metadata at the end of each disk. Old metadata should be erased before reusing the disk for a mirror. Most problems are caused by two particular types of leftover metadata: GPT partition tables and old metadata from a previous mirror.
GPT metadata can be erased with
gpart(8). This example erases both primary and backup
GPT partition tables from disk
ada8
:
#
gpart destroy -F ada8
A disk can be removed from an active mirror and the
metadata erased in one step using gmirror(8). Here, the
example disk ada8
is removed from the
active mirror gm4
:
#
gmirror remove gm4 ada8
If the mirror is not running, but old mirror metadata is
still on the disk, use gmirror clear
to
remove it:
#
gmirror clear ada8
gmirror(8) stores one block of metadata at the end of the disk. Because GPT partition schemes also store metadata at the end of the disk, mirroring entire GPT disks with gmirror(8) is not recommended. MBR partitioning is used here because it only stores a partition table at the start of the disk and does not conflict with the mirror metadata.
In this example, FreeBSD has already been installed on a
single disk, ada0
. Two new disks,
ada1
and ada2
, have
been connected to the system. A new mirror will be created on
these two disks and used to replace the old single
disk.
The geom_mirror.ko
kernel module must
either be built into the kernel or loaded at boot- or
run-time. Manually load the kernel module now:
#
gmirror load
Create the mirror with the two new drives:
#
gmirror label -v gm0 /dev/ada1 /dev/ada2
gm0
is a user-chosen device name
assigned to the new mirror. After the mirror has been
started, this device name appears in
/dev/mirror/
.
MBR and
bsdlabel partition tables can now
be created on the mirror with gpart(8). This example
uses a traditional file system layout, with partitions for
/
, swap, /var
,
/tmp
, and /usr
. A
single /
and a swap partition
will also work.
Partitions on the mirror do not have to be the same size
as those on the existing disk, but they must be large enough
to hold all the data already present on
ada0
.
#
gpart create -s MBR mirror/gm0
#
gpart add -t freebsd -a 4k mirror/gm0
#
gpart show mirror/gm0
=> 63 156301423 mirror/gm0 MBR (74G) 63 63 - free - (31k) 126 156301299 1 freebsd (74G) 156301425 61 - free - (30k)
#
gpart create -s BSD mirror/gm0s1
#
gpart add -t freebsd-ufs -a 4k -s 2g mirror/gm0s1
#
gpart add -t freebsd-swap -a 4k -s 4g mirror/gm0s1
#
gpart add -t freebsd-ufs -a 4k -s 2g mirror/gm0s1
#
gpart add -t freebsd-ufs -a 4k -s 1g mirror/gm0s1
#
gpart add -t freebsd-ufs -a 4k mirror/gm0s1
#
gpart show mirror/gm0s1
=> 0 156301299 mirror/gm0s1 BSD (74G) 0 2 - free - (1.0k) 2 4194304 1 freebsd-ufs (2.0G) 4194306 8388608 2 freebsd-swap (4.0G) 12582914 4194304 4 freebsd-ufs (2.0G) 16777218 2097152 5 freebsd-ufs (1.0G) 18874370 137426928 6 freebsd-ufs (65G) 156301298 1 - free - (512B)
Make the mirror bootable by installing bootcode in the MBR and bsdlabel and setting the active slice:
#
gpart bootcode -b /boot/mbr mirror/gm0
#
gpart set -a active -i 1 mirror/gm0
#
gpart bootcode -b /boot/boot mirror/gm0s1
Format the file systems on the new mirror, enabling soft-updates.
#
newfs -U /dev/mirror/gm0s1a
#
newfs -U /dev/mirror/gm0s1d
#
newfs -U /dev/mirror/gm0s1e
#
newfs -U /dev/mirror/gm0s1f
File systems from the original ada0
disk can now be copied onto the mirror with dump(8) and
restore(8).
#
mount /dev/mirror/gm0s1a /mnt
#
dump -C16 -b64 -0aL -f - / | (cd /mnt && restore -rf -)
#
mount /dev/mirror/gm0s1d /mnt/var
#
mount /dev/mirror/gm0s1e /mnt/tmp
#
mount /dev/mirror/gm0s1f /mnt/usr
#
dump -C16 -b64 -0aL -f - /var | (cd /mnt/var && restore -rf -)
#
dump -C16 -b64 -0aL -f - /tmp | (cd /mnt/tmp && restore -rf -)
#
dump -C16 -b64 -0aL -f - /usr | (cd /mnt/usr && restore -rf -)
Edit /mnt/etc/fstab
to point to
the new mirror file systems:
# Device Mountpoint FStype Options Dump Pass# /dev/mirror/gm0s1a / ufs rw 1 1 /dev/mirror/gm0s1b none swap sw 0 0 /dev/mirror/gm0s1d /var ufs rw 2 2 /dev/mirror/gm0s1e /tmp ufs rw 2 2 /dev/mirror/gm0s1f /usr ufs rw 2 2
If the geom_mirror.ko
kernel module
has not been built into the kernel,
/mnt/boot/loader.conf
is edited to load
the module at boot:
geom_mirror_load="YES"
Reboot the system to test the new mirror and verify that all data has been copied. The BIOS will see the mirror as two individual drives rather than a mirror. Because the drives are identical, it does not matter which is selected to boot.
See Section 18.3.4, “Troubleshooting” if there are
problems booting. Powering down and disconnecting the
original ada0
disk will allow it to be
kept as an offline backup.
In use, the mirror will behave just like the original single drive.
In this example, FreeBSD has already been installed on a
single disk, ada0
. A new disk,
ada1
, has been connected to the system.
A one-disk mirror will be created on the new disk, the
existing system copied onto it, and then the old disk will be
inserted into the mirror. This slightly complex procedure is
required because gmirror
needs to put a
512-byte block of metadata at the end of each disk, and the
existing ada0
has usually had all of its
space already allocated.
Load the geom_mirror.ko
kernel
module:
#
gmirror load
Check the media size of the original disk with
diskinfo
:
#
diskinfo -v ada0 | head -n3
/dev/ada0 512 # sectorsize 1000204821504 # mediasize in bytes (931G)
Create a mirror on the new disk. To make certain that the
mirror capacity is not any larger than the original
ada0
drive, gnop(8) is used to
create a fake drive of the exact same size. This drive does
not store any data, but is used only to limit the size of the
mirror. When gmirror(8) creates the mirror, it will
restrict the capacity to the size of
gzero.nop
, even if the new
ada1
drive has more space. Note that the
1000204821504
in the second line is
equal to ada0
's media size as shown by
diskinfo
above.
#
geom zero load
#
gnop create -s 1000204821504 gzero
#
gmirror label -v gm0 gzero.nop ada1
#
gmirror forget gm0
Since gzero.nop
does not store any
data, the mirror does not see it as connected. The mirror is
told to “forget” unconnected components, removing
references to gzero.nop
. The result is a
mirror device containing only a single disk,
ada1
.
After creating gm0
, view the
partition table on ada0
. This output is
from a 1 TB drive. If there is some unallocated space at
the end of the drive, the contents may be copied directly from
ada0
to the new mirror.
However, if the output shows that all of the space on the disk is allocated, as in the following listing, there is no space available for the 512-byte mirror metadata at the end of the disk.
#
gpart show ada0
=> 63 1953525105 ada0 MBR (931G) 63 1953525105 1 freebsd [active] (931G)
In this case, the partition table must be edited to reduce
the capacity by one sector on mirror/gm0
.
The procedure will be explained later.
In either case, partition tables on the primary disk
should be first copied using gpart backup
and gpart restore
.
#
gpart backup ada0 > table.ada0
#
gpart backup ada0s1 > table.ada0s1
These commands create two files,
table.ada0
and
table.ada0s1
. This example is from a
1 TB drive:
#
cat table.ada0
MBR 4 1 freebsd 63 1953525105 [active]
#
cat table.ada0s1
BSD 8 1 freebsd-ufs 0 4194304 2 freebsd-swap 4194304 33554432 4 freebsd-ufs 37748736 50331648 5 freebsd-ufs 88080384 41943040 6 freebsd-ufs 130023424 838860800 7 freebsd-ufs 968884224 984640881
If no free space is shown at the end of the disk, the size of both the slice and the last partition must be reduced by one sector. Edit the two files, reducing the size of both the slice and last partition by one. These are the last numbers in each listing.
#
cat table.ada0
MBR 4 1 freebsd 63 1953525104 [active]
#
cat table.ada0s1
BSD 8 1 freebsd-ufs 0 4194304 2 freebsd-swap 4194304 33554432 4 freebsd-ufs 37748736 50331648 5 freebsd-ufs 88080384 41943040 6 freebsd-ufs 130023424 838860800 7 freebsd-ufs 968884224 984640880
If at least one sector was unallocated at the end of the disk, these two files can be used without modification.
Now restore the partition table into
mirror/gm0
:
#
gpart restore mirror/gm0 < table.ada0
#
gpart restore mirror/gm0s1 < table.ada0s1
Check the partition table with
gpart show
. This example has
gm0s1a
for /
,
gm0s1d
for /var
,
gm0s1e
for /usr
,
gm0s1f
for /data1
,
and gm0s1g
for
/data2
.
#
gpart show mirror/gm0
=> 63 1953525104 mirror/gm0 MBR (931G) 63 1953525042 1 freebsd [active] (931G) 1953525105 62 - free - (31k)#
gpart show mirror/gm0s1
=> 0 1953525042 mirror/gm0s1 BSD (931G) 0 2097152 1 freebsd-ufs (1.0G) 2097152 16777216 2 freebsd-swap (8.0G) 18874368 41943040 4 freebsd-ufs (20G) 60817408 20971520 5 freebsd-ufs (10G) 81788928 629145600 6 freebsd-ufs (300G) 710934528 1242590514 7 freebsd-ufs (592G) 1953525042 63 - free - (31k)
Both the slice and the last partition must have at least one free block at the end of the disk.
Create file systems on these new partitions. The number
of partitions will vary to match the original disk,
ada0
.
#
newfs -U /dev/mirror/gm0s1a
#
newfs -U /dev/mirror/gm0s1d
#
newfs -U /dev/mirror/gm0s1e
#
newfs -U /dev/mirror/gm0s1f
#
newfs -U /dev/mirror/gm0s1g
Make the mirror bootable by installing bootcode in the MBR and bsdlabel and setting the active slice:
#
gpart bootcode -b /boot/mbr mirror/gm0
#
gpart set -a active -i 1 mirror/gm0
#
gpart bootcode -b /boot/boot mirror/gm0s1
Adjust /etc/fstab
to use the new
partitions on the mirror. Back up this file first by copying
it to /etc/fstab.orig
.
#
cp /etc/fstab /etc/fstab.orig
Edit /etc/fstab
, replacing
/dev/ada0
with
mirror/gm0
.
# Device Mountpoint FStype Options Dump Pass# /dev/mirror/gm0s1a / ufs rw 1 1 /dev/mirror/gm0s1b none swap sw 0 0 /dev/mirror/gm0s1d /var ufs rw 2 2 /dev/mirror/gm0s1e /usr ufs rw 2 2 /dev/mirror/gm0s1f /data1 ufs rw 2 2 /dev/mirror/gm0s1g /data2 ufs rw 2 2
If the geom_mirror.ko
kernel module
has not been built into the kernel, edit
/boot/loader.conf
to load it at
boot:
geom_mirror_load="YES"
File systems from the original disk can now be copied onto
the mirror with dump(8) and restore(8). Each file
system dumped with dump -L
will create a
snapshot first, which can take some time.
#
mount /dev/mirror/gm0s1a /mnt
#
dump -C16 -b64 -0aL -f - / | (cd /mnt && restore -rf -)
#
mount /dev/mirror/gm0s1d /mnt/var
#
mount /dev/mirror/gm0s1e /mnt/usr
#
mount /dev/mirror/gm0s1f /mnt/data1
#
mount /dev/mirror/gm0s1g /mnt/data2
#
dump -C16 -b64 -0aL -f - /usr | (cd /mnt/usr && restore -rf -)
#
dump -C16 -b64 -0aL -f - /var | (cd /mnt/var && restore -rf -)
#
dump -C16 -b64 -0aL -f - /data1 | (cd /mnt/data1 && restore -rf -)
#
dump -C16 -b64 -0aL -f - /data2 | (cd /mnt/data2 && restore -rf -)
Restart the system, booting from
ada1
. If everything is working, the
system will boot from mirror/gm0
, which
now contains the same data as ada0
had
previously. See Section 18.3.4, “Troubleshooting” if
there are problems booting.
At this point, the mirror still consists of only the
single ada1
disk.
After booting from mirror/gm0
successfully, the final step is inserting
ada0
into the mirror.
When ada0
is inserted into the
mirror, its former contents will be overwritten by data from
the mirror. Make certain that
mirror/gm0
has the same contents as
ada0
before adding
ada0
to the mirror. If the contents
previously copied by dump(8) and restore(8) are
not identical to what was on ada0
,
revert /etc/fstab
to mount the file
systems on ada0
, reboot, and start the
whole procedure again.
#
gmirror insert gm0 ada0
GEOM_MIRROR: Device gm0: rebuilding provider ada0
Synchronization between the two disks will start
immediately. Use gmirror status
to view
the progress.
#
gmirror status
Name Status Components mirror/gm0 DEGRADED ada1 (ACTIVE) ada0 (SYNCHRONIZING, 64%)
After a while, synchronization will finish.
GEOM_MIRROR: Device gm0: rebuilding provider ada0 finished.#
gmirror status
Name Status Components mirror/gm0 COMPLETE ada1 (ACTIVE) ada0 (ACTIVE)
mirror/gm0
now consists
of the two disks ada0
and
ada1
, and the contents are automatically
synchronized with each other. In use,
mirror/gm0
will behave just like the
original single drive.
If the system no longer boots, BIOS settings may have to be changed to boot from one of the new mirrored drives. Either mirror drive can be used for booting, as they contain identical data.
If the boot stops with this message, something is wrong with the mirror device:
Mounting from ufs:/dev/mirror/gm0s1a failed with error 19. Loader variables: vfs.root.mountfrom=ufs:/dev/mirror/gm0s1a vfs.root.mountfrom.options=rw Manual root filesystem specification: <fstype>:<device> [options] Mount <device> using filesystem <fstype> and with the specified (optional) option list. eg. ufs:/dev/da0s1a zfs:tank cd9660:/dev/acd0 ro (which is equivalent to: mount -t cd9660 -o ro /dev/acd0 /) ? List valid disk boot devices . Yield 1 second (for background tasks) <empty line> Abort manual input mountroot>
Forgetting to load the geom_mirror.ko
module in /boot/loader.conf
can cause
this problem. To fix it, boot from a FreeBSD
installation media and choose Shell
at the
first prompt. Then load the mirror module and mount the
mirror device:
#
gmirror load
#
mount /dev/mirror/gm0s1a /mnt
Edit /mnt/boot/loader.conf
, adding a
line to load the mirror module:
geom_mirror_load="YES"
Save the file and reboot.
Other problems that cause error 19
require more effort to fix. Although the system should boot
from ada0
, another prompt to select a
shell will appear if /etc/fstab
is
incorrect. Enter ufs:/dev/ada0s1a
at the
boot loader prompt and press Enter. Undo the
edits in /etc/fstab
then mount the file
systems from the original disk (ada0
)
instead of the mirror. Reboot the system and try the
procedure again.
Enter full pathname of shell or RETURN for /bin/sh:#
cp /etc/fstab.orig /etc/fstab
#
reboot
The benefit of disk mirroring is that an individual disk
can fail without causing the mirror to lose any data. In the
above example, if ada0
fails, the mirror
will continue to work, providing data from the remaining
working drive, ada1
.
To replace the failed drive, shut down the system and
physically replace the failed drive with a new drive of equal
or greater capacity. Manufacturers use somewhat arbitrary
values when rating drives in gigabytes, and the only way to
really be sure is to compare the total count of sectors shown
by diskinfo -v
. A drive with larger
capacity than the mirror will work, although the extra space
on the new drive will not be used.
After the computer is powered back up, the mirror will be running in a “degraded” mode with only one drive. The mirror is told to forget drives that are not currently connected:
#
gmirror forget gm0
Any old metadata should be cleared from the replacement
disk using the instructions in
Section 18.3.1, “Metadata Issues”. Then the replacement
disk, ada4
for this example, is inserted
into the mirror:
#
gmirror insert gm0 /dev/ada4
Resynchronization begins when the new drive is inserted into the mirror. This process of copying mirror data to a new drive can take a while. Performance of the mirror will be greatly reduced during the copy, so inserting new drives is best done when there is low demand on the computer.
Progress can be monitored with gmirror
status
, which shows drives that are being
synchronized and the percentage of completion. During
resynchronization, the status will be
DEGRADED
, changing to
COMPLETE
when the process is
finished.
RAID3 is a method used to combine several disk drives into a single volume with a dedicated parity disk. In a RAID3 system, data is split up into a number of bytes that are written across all the drives in the array except for one disk which acts as a dedicated parity disk. This means that disk reads from a RAID3 implementation access all disks in the array. Performance can be enhanced by using multiple disk controllers. The RAID3 array provides a fault tolerance of 1 drive, while providing a capacity of 1 - 1/n times the total capacity of all drives in the array, where n is the number of hard drives in the array. Such a configuration is mostly suitable for storing data of larger sizes such as multimedia files.
At least 3 physical hard drives are required to build a RAID3 array. Each disk must be of the same size, since I/O requests are interleaved to read or write to multiple disks in parallel. Also, due to the nature of RAID3, the number of drives must be equal to 3, 5, 9, 17, and so on, or 2^n + 1.
This section demonstrates how to create a software RAID3 on a FreeBSD system.
While it is theoretically possible to boot from a RAID3 array on FreeBSD, that configuration is uncommon and is not advised.
In FreeBSD, support for RAID3 is implemented by the graid3(8) GEOM class. Creating a dedicated RAID3 array on FreeBSD requires the following steps.
First, load the geom_raid3.ko
kernel module by issuing one of the following
commands:
#
graid3 load
or:
#
kldload geom_raid3
Ensure that a suitable mount point exists. This command creates a new directory to use as the mount point:
#
mkdir
/multimedia
Determine the device names for the disks which will be
added to the array, and create the new
RAID3 device. The final device listed
will act as the dedicated parity disk. This example uses
three unpartitioned ATA drives:
and
ada1
for
data, and
ada2
for
parity.ada3
#
graid3 label -v gr0 /dev/ada1 /dev/ada2 /dev/ada3
Metadata value stored on /dev/ada1. Metadata value stored on /dev/ada2. Metadata value stored on /dev/ada3. Done.
Partition the newly created gr0
device and put a UFS file system on
it:
#
gpart create -s GPT /dev/raid3/gr0
#
gpart add -t freebsd-ufs /dev/raid3/gr0
#
newfs -j /dev/raid3/gr0p1
Many numbers will glide across the screen, and after a bit of time, the process will be complete. The volume has been created and is ready to be mounted:
#
mount /dev/raid3/gr0p1 /multimedia/
The RAID3 array is now ready to use.
Additional configuration is needed to retain this setup across system reboots.
The geom_raid3.ko
module must be
loaded before the array can be mounted. To automatically
load the kernel module during system initialization, add
the following line to
/boot/loader.conf
:
geom_raid3_load="YES"
The following volume information must be added to
/etc/fstab
in order to
automatically mount the array's file system during the
system boot process:
/dev/raid3/gr0p1 /multimedia ufs rw 2 2
Some motherboards and expansion cards add some simple hardware, usually just a ROM, that allows the computer to boot from a RAID array. After booting, access to the RAID array is handled by software running on the computer's main processor. This “hardware-assisted software RAID” gives RAID arrays that are not dependent on any particular operating system, and which are functional even before an operating system is loaded.
Several levels of RAID are supported, depending on the hardware in use. See graid(8) for a complete list.
graid(8) requires the geom_raid.ko
kernel module, which is included in the
GENERIC
kernel starting with FreeBSD 9.1.
If needed, it can be loaded manually with
graid load
.
Software RAID devices often have a menu that can be entered by pressing special keys when the computer is booting. The menu can be used to create and delete RAID arrays. graid(8) can also create arrays directly from the command line.
graid label
is used to create a new
array. The motherboard used for this example has an Intel
software RAID chipset, so the Intel
metadata format is specified. The new array is given a label
of gm0
, it is a mirror
(RAID1), and uses drives
ada0
and
ada1
.
Some space on the drives will be overwritten when they are made into a new array. Back up existing data first!
#
graid label Intel gm0 RAID1 ada0 ada1
GEOM_RAID: Intel-a29ea104: Array Intel-a29ea104 created. GEOM_RAID: Intel-a29ea104: Disk ada0 state changed from NONE to ACTIVE. GEOM_RAID: Intel-a29ea104: Subdisk gm0:0-ada0 state changed from NONE to ACTIVE. GEOM_RAID: Intel-a29ea104: Disk ada1 state changed from NONE to ACTIVE. GEOM_RAID: Intel-a29ea104: Subdisk gm0:1-ada1 state changed from NONE to ACTIVE. GEOM_RAID: Intel-a29ea104: Array started. GEOM_RAID: Intel-a29ea104: Volume gm0 state changed from STARTING to OPTIMAL. Intel-a29ea104 created GEOM_RAID: Intel-a29ea104: Provider raid/r0 for volume gm0 created.
A status check shows the new mirror is ready for use:
#
graid status
Name Status Components raid/r0 OPTIMAL ada0 (ACTIVE (ACTIVE)) ada1 (ACTIVE (ACTIVE))
The array device appears in
/dev/raid/
. The first array is called
r0
. Additional arrays, if present, will
be r1
, r2
, and so
on.
The BIOS menu on some of these devices
can create arrays with special characters in their names. To
avoid problems with those special characters, arrays are given
simple numbered names like r0
. To show
the actual labels, like gm0
in the
example above, use sysctl(8):
#
sysctl kern.geom.raid.name_format=1
Some software RAID devices support more than one volume on an array. Volumes work like partitions, allowing space on the physical drives to be split and used in different ways. For example, Intel software RAID devices support two volumes. This example creates a 40 G mirror for safely storing the operating system, followed by a 20 G RAID0 (stripe) volume for fast temporary storage:
#
graid label -S 40G Intel gm0 RAID1 ada0 ada1
#
graid add -S 20G gm0 RAID0
Volumes appear as additional
r
entries
in X
/dev/raid/
. An array with two volumes
will show r0
and
r1
.
See graid(8) for the number of volumes supported by different software RAID devices.
Under certain specific conditions, it is possible to convert an existing single drive to a graid(8) array without reformatting. To avoid data loss during the conversion, the existing drive must meet these minimum requirements:
The drive must be partitioned with the MBR partitioning scheme. GPT or other partitioning schemes with metadata at the end of the drive will be overwritten and corrupted by the graid(8) metadata.
There must be enough unpartitioned and unused space at the end of the drive to hold the graid(8) metadata. This metadata varies in size, but the largest occupies 64 M, so at least that much free space is recommended.
If the drive meets these requirements, start by making a full backup. Then create a single-drive mirror with that drive:
#
graid label Intel gm0 RAID1 ada0 NONE
graid(8) metadata was written to the end of the drive in the unused space. A second drive can now be inserted into the mirror:
#
graid insert raid/r0 ada1
Data from the original drive will immediately begin to be copied to the second drive. The mirror will operate in degraded status until the copy is complete.
Drives can be inserted into an array as replacements for drives that have failed or are missing. If there are no failed or missing drives, the new drive becomes a spare. For example, inserting a new drive into a working two-drive mirror results in a two-drive mirror with one spare drive, not a three-drive mirror.
In the example mirror array, data immediately begins to be copied to the newly-inserted drive. Any existing information on the new drive will be overwritten.
#
graid insert raid/r0 ada1
GEOM_RAID: Intel-a29ea104: Disk ada1 state changed from NONE to ACTIVE. GEOM_RAID: Intel-a29ea104: Subdisk gm0:1-ada1 state changed from NONE to NEW. GEOM_RAID: Intel-a29ea104: Subdisk gm0:1-ada1 state changed from NEW to REBUILD. GEOM_RAID: Intel-a29ea104: Subdisk gm0:1-ada1 rebuild start at 0.
Individual drives can be permanently removed from a from an array and their metadata erased:
#
graid remove raid/r0 ada1
GEOM_RAID: Intel-a29ea104: Disk ada1 state changed from ACTIVE to OFFLINE. GEOM_RAID: Intel-a29ea104: Subdisk gm0:1-[unknown] state changed from ACTIVE to NONE. GEOM_RAID: Intel-a29ea104: Volume gm0 state changed from OPTIMAL to DEGRADED.
An array can be stopped without removing metadata from the drives. The array will be restarted when the system is booted.
#
graid stop raid/r0
Array status can be checked at any time. After a drive was added to the mirror in the example above, data is being copied from the original drive to the new drive:
#
graid status
Name Status Components raid/r0 DEGRADED ada0 (ACTIVE (ACTIVE)) ada1 (ACTIVE (REBUILD 28%))
Some types of arrays, like RAID0
or
CONCAT
, may not be shown in the status
report if disks have failed. To see these partially-failed
arrays, add -ga
:
#
graid status -ga
Name Status Components Intel-e2d07d9a BROKEN ada6 (ACTIVE (ACTIVE))
Arrays are destroyed by deleting all of the volumes from them. When the last volume present is deleted, the array is stopped and metadata is removed from the drives:
#
graid delete raid/r0
Drives may unexpectedly contain graid(8) metadata, either from previous use or manufacturer testing. graid(8) will detect these drives and create an array, interfering with access to the individual drive. To remove the unwanted metadata:
Boot the system. At the boot menu, select
2
for the loader prompt. Enter:
OKset kern.geom.raid.enable=0
OKboot
The system will boot with graid(8) disabled.
Back up all data on the affected drive.
As a workaround, graid(8) array detection can be disabled by adding
kern.geom.raid.enable=0
to /boot/loader.conf
.
To permanently remove the graid(8) metadata
from the affected drive, boot a FreeBSD installation
CD-ROM or memory stick, and select
Shell
. Use status
to find the name of the array, typically
raid/r0
:
#
graid status
Name Status Components raid/r0 OPTIMAL ada0 (ACTIVE (ACTIVE)) ada1 (ACTIVE (ACTIVE))
Delete the volume by name:
#
graid delete raid/r0
If there is more than one volume shown, repeat the process for each volume. After the last array has been deleted, the volume will be destroyed.
Reboot and verify data, restoring from backup if
necessary. After the metadata has been removed, the
kern.geom.raid.enable=0
entry in
/boot/loader.conf
can also be
removed.
GEOM provides a simple mechanism for providing remote access to devices such as disks, CDs, and file systems through the use of the GEOM Gate network daemon, ggated. The system with the device runs the server daemon which handles requests made by clients using ggatec. The devices should not contain any sensitive data as the connection between the client and the server is not encrypted.
Similar to NFS, which is discussed in
Section 29.3, “Network File System (NFS)”, ggated
is configured using an exports file. This file specifies which
systems are permitted to access the exported resources and what
level of access they are offered. For example, to give the
client 192.168.1.5
read and write access to the fourth slice on the first
SCSI disk, create
/etc/gg.exports
with this line:
192.168.1.5 RW /dev/da0s4d
Before exporting the device, ensure it is not currently mounted. Then, start ggated:
#
ggated
Several options are available for specifying an alternate listening port or changing the default location of the exports file. Refer to ggated(8) for details.
To access the exported device on the client machine, first
use ggatec
to specify the
IP address of the server and the device name
of the exported device. If successful, this command will
display a ggate
device name to mount. Mount
that specified device name on a free mount point. This example
connects to the /dev/da0s4d
partition on
192.168.1.1
, then mounts
/dev/ggate0
on
/mnt
:
#
ggatec create -o rw 192.168.1.1 /dev/da0s4d
ggate0#
mount /dev/ggate0 /mnt
The device on the server may now be accessed through
/mnt
on the client. For more details about
ggatec
and a few usage examples, refer to
ggatec(8).
The mount will fail if the device is currently mounted on either the server or any other client on the network. If simultaneous access is needed to network resources, use NFS instead.
When the device is no longer needed, unmount it with
umount
so that the resource is available to
other clients.
During system initialization, the FreeBSD kernel creates
device nodes as devices are found. This method of probing for
devices raises some issues. For instance, what if a new disk
device is added via USB? It is likely that
a flash device may be handed the device name of
da0
and the original
da0
shifted to
da1
. This will cause issues mounting
file systems if they are listed in
/etc/fstab
which may also prevent the
system from booting.
One solution is to chain SCSI devices
in order so a new device added to the SCSI
card will be issued unused device numbers. But what about
USB devices which may replace the primary
SCSI disk? This happens because
USB devices are usually probed before the
SCSI card. One solution is to only insert
these devices after the system has been booted. Another method
is to use only a single ATA drive and never
list the SCSI devices in
/etc/fstab
.
A better solution is to use glabel
to
label the disk devices and use the labels in
/etc/fstab
. Because
glabel
stores the label in the last sector of
a given provider, the label will remain persistent across
reboots. By using this label as a device, the file system may
always be mounted regardless of what device node it is accessed
through.
glabel
can create both transient and
permanent labels. Only permanent labels are consistent across
reboots. Refer to glabel(8) for more information on the
differences between labels.
Permanent labels can be a generic or a file system label.
Permanent file system labels can be created with
tunefs(8) or newfs(8). These types of labels are
created in a sub-directory of /dev
, and
will be named according to the file system type. For example,
UFS2 file system labels will be created in
/dev/ufs
. Generic permanent labels can
be created with glabel label
. These are
not file system specific and will be created in
/dev/label
.
Temporary labels are destroyed at the next reboot. These
labels are created in /dev/label
and are
suited to experimentation. A temporary label can be created
using glabel create
.
To create a permanent label for a UFS2 file system without destroying any data, issue the following command:
#
tunefs -L
home
/dev/da3
A label should now exist in /dev/ufs
which may be added to /etc/fstab
:
/dev/ufs/home /home ufs rw 2 2
The file system must not be mounted while attempting
to run tunefs
.
Now the file system may be mounted:
#
mount /home
From this point on, so long as the
geom_label.ko
kernel module is loaded at
boot with /boot/loader.conf
or the
GEOM_LABEL
kernel option is present,
the device node may change without any ill effect on the
system.
File systems may also be created with a default label
by using the -L
flag with
newfs
. Refer to newfs(8) for
more information.
The following command can be used to destroy the label:
#
glabel destroy home
The following example shows how to label the partitions of a boot disk.
By permanently labeling the partitions on the boot disk,
the system should be able to continue to boot normally, even
if the disk is moved to another controller or transferred to
a different system. For this example, it is assumed that a
single ATA disk is used, which is
currently recognized by the system as
ad0
. It is also assumed that the
standard FreeBSD partition scheme is used, with
/
,
/var
,
/usr
and
/tmp
, as
well as a swap partition.
Reboot the system, and at the loader(8) prompt, press 4 to boot into single user mode. Then enter the following commands:
#
glabel label rootfs /dev/ad0s1a
GEOM_LABEL: Label for provider /dev/ad0s1a is label/rootfs#
glabel label var /dev/ad0s1d
GEOM_LABEL: Label for provider /dev/ad0s1d is label/var#
glabel label usr /dev/ad0s1f
GEOM_LABEL: Label for provider /dev/ad0s1f is label/usr#
glabel label tmp /dev/ad0s1e
GEOM_LABEL: Label for provider /dev/ad0s1e is label/tmp#
glabel label swap /dev/ad0s1b
GEOM_LABEL: Label for provider /dev/ad0s1b is label/swap#
exit
The system will continue with multi-user boot. After
the boot completes, edit /etc/fstab
and
replace the conventional device names, with their respective
labels. The final /etc/fstab
will
look like this:
# Device Mountpoint FStype Options Dump Pass# /dev/label/swap none swap sw 0 0 /dev/label/rootfs / ufs rw 1 1 /dev/label/tmp /tmp ufs rw 2 2 /dev/label/usr /usr ufs rw 2 2 /dev/label/var /var ufs rw 2 2
The system can now be rebooted. If everything went
well, it will come up normally and mount
will show:
#
mount
/dev/label/rootfs on / (ufs, local) devfs on /dev (devfs, local) /dev/label/tmp on /tmp (ufs, local, soft-updates) /dev/label/usr on /usr (ufs, local, soft-updates) /dev/label/var on /var (ufs, local, soft-updates)
The glabel(8) class
supports a label type for UFS file
systems, based on the unique file system id,
ufsid
. These labels may be found in
/dev/ufsid
and are
created automatically during system startup. It is possible
to use ufsid
labels to mount partitions
using /etc/fstab
. Use glabel
status
to receive a list of file systems and their
corresponding ufsid
labels:
%
glabel status
Name Status Components ufsid/486b6fc38d330916 N/A ad4s1d ufsid/486b6fc16926168e N/A ad4s1f
In the above example, ad4s1d
represents /var
,
while ad4s1f
represents
/usr
.
Using the ufsid
values shown, these
partitions may now be mounted with the following entries in
/etc/fstab
:
/dev/ufsid/486b6fc38d330916 /var ufs rw 2 2 /dev/ufsid/486b6fc16926168e /usr ufs rw 2 2
Any partitions with ufsid
labels can be
mounted in this way, eliminating the need to manually create
permanent labels, while still enjoying the benefits of device
name independent mounting.
Support for journals on
UFS file systems is available on FreeBSD. The
implementation is provided through the GEOM
subsystem and is configured using gjournal
.
Unlike other file system journaling implementations, the
gjournal
method is block based and not
implemented as part of the file system. It is a
GEOM extension.
Journaling stores a log of file system transactions, such as changes that make up a complete disk write operation, before meta-data and file writes are committed to the disk. This transaction log can later be replayed to redo file system transactions, preventing file system inconsistencies.
This method provides another mechanism to protect against data loss and inconsistencies of the file system. Unlike Soft Updates, which tracks and enforces meta-data updates, and snapshots, which create an image of the file system, a log is stored in disk space specifically for this task. For better performance, the journal may be stored on another disk. In this configuration, the journal provider or storage device should be listed after the device to enable journaling on.
The GENERIC
kernel provides support for
gjournal
. To automatically load the
geom_journal.ko
kernel module at boot time,
add the following line to
/boot/loader.conf
:
geom_journal_load="YES"
If a custom kernel is used, ensure the following line is in the kernel configuration file:
options GEOM_JOURNAL
Once the module is loaded, a journal can be created on a new
file system using the following steps. In this example,
da4
is a new SCSI
disk:
#
gjournal load
#
gjournal label /dev/
da4
This will load the module and create a
/dev/da4.journal
device node on
/dev/da4
.
A UFS file system may now be created on the journaled device, then mounted on an existing mount point:
#
newfs -O 2 -J /dev/
da4
.journal#
mount /dev/
da4
.journal/mnt
In the case of several slices, a journal will be created
for each individual slice. For instance, if
ad4s1
and ad4s2
are
both slices, then gjournal
will create
ad4s1.journal
and
ad4s2.journal
.
Journaling may also be enabled on current file systems by
using tunefs
. However,
always make a backup before attempting to
alter an existing file system. In most cases,
gjournal
will fail if it is unable to create
the journal, but this does not protect against data loss
incurred as a result of misusing tunefs
.
Refer to gjournal(8) and tunefs(8) for more
information about these commands.
It is possible to journal the boot disk of a FreeBSD system. Refer to the article Implementing UFS Journaling on a Desktop PC for detailed instructions.
The Z File System, or ZFS, is an advanced file system designed to overcome many of the major problems found in previous designs.
Originally developed at Sun™, ongoing open source ZFS development has moved to the OpenZFS Project.
ZFS has three major design goals:
Data integrity: All data includes a checksum of the data. When data is written, the checksum is calculated and written along with it. When that data is later read back, the checksum is calculated again. If the checksums do not match, a data error has been detected. ZFS will attempt to automatically correct errors when data redundancy is available.
Pooled storage: physical storage devices are added to a pool, and storage space is allocated from that shared pool. Space is available to all file systems, and can be increased by adding new storage devices to the pool.
Performance: multiple caching mechanisms provide increased performance. ARC is an advanced memory-based read cache. A second level of disk-based read cache can be added with L2ARC, and disk-based synchronous write cache is available with ZIL.
A complete list of features and terminology is shown in Section 19.8, “ZFS Features and Terminology”.
ZFS is significantly different from any previous file system because it is more than just a file system. Combining the traditionally separate roles of volume manager and file system provides ZFS with unique advantages. The file system is now aware of the underlying structure of the disks. Traditional file systems could only be created on a single disk at a time. If there were two disks then two separate file systems would have to be created. In a traditional hardware RAID configuration, this problem was avoided by presenting the operating system with a single logical disk made up of the space provided by a number of physical disks, on top of which the operating system placed a file system. Even in the case of software RAID solutions like those provided by GEOM, the UFS file system living on top of the RAID transform believed that it was dealing with a single device. ZFS's combination of the volume manager and the file system solves this and allows the creation of many file systems all sharing a pool of available storage. One of the biggest advantages to ZFS's awareness of the physical layout of the disks is that existing file systems can be grown automatically when additional disks are added to the pool. This new space is then made available to all of the file systems. ZFS also has a number of different properties that can be applied to each file system, giving many advantages to creating a number of different file systems and datasets rather than a single monolithic file system.
There is a startup mechanism that allows FreeBSD to mount
ZFS pools during system initialization. To
enable it, add this line to
/etc/rc.conf
:
zfs_enable="YES"
Then start the service:
#
service zfs start
The examples in this section assume three
SCSI disks with the device names
,
da0
, and
da1
. Users
of SATA hardware should instead use
da2
device
names.ada
To create a simple, non-redundant pool using a single disk device:
#
zpool create
example
/dev/da0
To view the new pool, review the output of
df
:
#
df
Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/ad0s1a 2026030 235230 1628718 13% / devfs 1 1 0 100% /dev /dev/ad0s1d 54098308 1032846 48737598 2% /usr example 17547136 0 17547136 0% /example
This output shows that the example
pool
has been created and mounted. It is now accessible as a file
system. Files can be created on it and users can browse
it:
#
cd /example
#
ls
#
touch testfile
#
ls -al
total 4 drwxr-xr-x 2 root wheel 3 Aug 29 23:15 . drwxr-xr-x 21 root wheel 512 Aug 29 23:12 .. -rw-r--r-- 1 root wheel 0 Aug 29 23:15 testfile
However, this pool is not taking advantage of any ZFS features. To create a dataset on this pool with compression enabled:
#
zfs create example/compressed
#
zfs set compression=gzip example/compressed
The example/compressed
dataset is now a
ZFS compressed file system. Try copying
some large files to
/example/compressed
.
Compression can be disabled with:
#
zfs set compression=off example/compressed
To unmount a file system, use
zfs umount
and then verify with
df
:
#
zfs umount example/compressed
#
df
Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/ad0s1a 2026030 235232 1628716 13% / devfs 1 1 0 100% /dev /dev/ad0s1d 54098308 1032864 48737580 2% /usr example 17547008 0 17547008 0% /example
To re-mount the file system to make it accessible again,
use zfs mount
and verify with
df
:
#
zfs mount example/compressed
#
df
Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/ad0s1a 2026030 235234 1628714 13% / devfs 1 1 0 100% /dev /dev/ad0s1d 54098308 1032864 48737580 2% /usr example 17547008 0 17547008 0% /example example/compressed 17547008 0 17547008 0% /example/compressed
The pool and file system may also be observed by viewing
the output from mount
:
#
mount
/dev/ad0s1a on / (ufs, local) devfs on /dev (devfs, local) /dev/ad0s1d on /usr (ufs, local, soft-updates) example on /example (zfs, local) example/compressed on /example/compressed (zfs, local)
After creation, ZFS datasets can be
used like any file systems. However, many other features are
available which can be set on a per-dataset basis. In the
example below, a new file system called
data
is created. Important files will be
stored here, so it is configured to keep two copies of each
data block:
#
zfs create example/data
#
zfs set copies=2 example/data
It is now possible to see the data and space utilization
by issuing df
:
#
df
Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/ad0s1a 2026030 235234 1628714 13% / devfs 1 1 0 100% /dev /dev/ad0s1d 54098308 1032864 48737580 2% /usr example 17547008 0 17547008 0% /example example/compressed 17547008 0 17547008 0% /example/compressed example/data 17547008 0 17547008 0% /example/data
Notice that each file system on the pool has the same
amount of available space. This is the reason for using
df
in these examples, to show that the file
systems use only the amount of space they need and all draw
from the same pool. ZFS eliminates
concepts such as volumes and partitions, and allows multiple
file systems to occupy the same pool.
To destroy the file systems and then destroy the pool as it is no longer needed:
#
zfs destroy example/compressed
#
zfs destroy example/data
#
zpool destroy example
Disks fail. One method of avoiding data loss from disk failure is to implement RAID. ZFS supports this feature in its pool design. RAID-Z pools require three or more disks but provide more usable space than mirrored pools.
This example creates a RAID-Z pool, specifying the disks to add to the pool:
#
zpool create storage raidz da0 da1 da2
Sun™ recommends that the number of devices used in a RAID-Z configuration be between three and nine. For environments requiring a single pool consisting of 10 disks or more, consider breaking it up into smaller RAID-Z groups. If only two disks are available and redundancy is a requirement, consider using a ZFS mirror. Refer to zpool(8) for more details.
The previous example created the
storage
zpool. This example makes a new
file system called home
in that
pool:
#
zfs create storage/home
Compression and keeping extra copies of directories and files can be enabled:
#
zfs set copies=2 storage/home
#
zfs set compression=gzip storage/home
To make this the new home directory for users, copy the user data to this directory and create the appropriate symbolic links:
#
cp -rp /home/* /storage/home
#
rm -rf /home /usr/home
#
ln -s /storage/home /home
#
ln -s /storage/home /usr/home
Users data is now stored on the freshly-created
/storage/home
. Test by adding a new user
and logging in as that user.
Try creating a file system snapshot which can be rolled back later:
#
zfs snapshot storage/home@08-30-08
Snapshots can only be made of a full file system, not a single directory or file.
The @
character is a delimiter between
the file system name or the volume name. If an important
directory has been accidentally deleted, the file system can
be backed up, then rolled back to an earlier snapshot when the
directory still existed:
#
zfs rollback storage/home@08-30-08
To list all available snapshots, run
ls
in the file system's
.zfs/snapshot
directory. For example, to
see the previously taken snapshot:
#
ls /storage/home/.zfs/snapshot
It is possible to write a script to perform regular snapshots on user data. However, over time, snapshots can consume a great deal of disk space. The previous snapshot can be removed using the command:
#
zfs destroy storage/home@08-30-08
After testing, /storage/home
can be
made the real /home
using this
command:
#
zfs set mountpoint=/home storage/home
Run df
and mount
to
confirm that the system now treats the file system as the real
/home
:
#
mount
/dev/ad0s1a on / (ufs, local) devfs on /dev (devfs, local) /dev/ad0s1d on /usr (ufs, local, soft-updates) storage on /storage (zfs, local) storage/home on /home (zfs, local)#
df
Filesystem 1K-blocks Used Avail Capacity Mounted on /dev/ad0s1a 2026030 235240 1628708 13% / devfs 1 1 0 100% /dev /dev/ad0s1d 54098308 1032826 48737618 2% /usr storage 26320512 0 26320512 0% /storage storage/home 26320512 0 26320512 0% /home
This completes the RAID-Z
configuration. Daily status updates about the file systems
created can be generated as part of the nightly
periodic(8) runs. Add this line to
/etc/periodic.conf
:
daily_status_zfs_enable="YES"
Every software RAID has a method of
monitoring its state
. The status of
RAID-Z devices may be viewed with this
command:
#
zpool status -x
If all pools are Online and everything is normal, the message shows:
all pools are healthy
If there is an issue, perhaps a disk is in the Offline state, the pool state will look similar to:
pool: storage state: DEGRADED status: One or more devices has been taken offline by the administrator. Sufficient replicas exist for the pool to continue functioning in a degraded state. action: Online the device using 'zpool online' or replace the device with 'zpool replace'. scrub: none requested config: NAME STATE READ WRITE CKSUM storage DEGRADED 0 0 0 raidz1 DEGRADED 0 0 0 da0 ONLINE 0 0 0 da1 OFFLINE 0 0 0 da2 ONLINE 0 0 0 errors: No known data errors
This indicates that the device was previously taken offline by the administrator with this command:
#
zpool offline storage da1
Now the system can be powered down to replace
da1
. When the system is back online,
the failed disk can replaced in the pool:
#
zpool replace storage da1
From here, the status may be checked again, this time
without -x
so that all pools are
shown:
#
zpool status storage
pool: storage state: ONLINE scrub: resilver completed with 0 errors on Sat Aug 30 19:44:11 2008 config: NAME STATE READ WRITE CKSUM storage ONLINE 0 0 0 raidz1 ONLINE 0 0 0 da0 ONLINE 0 0 0 da1 ONLINE 0 0 0 da2 ONLINE 0 0 0 errors: No known data errors
In this example, everything is normal.
ZFS uses checksums to verify the integrity of stored data. These are enabled automatically upon creation of file systems.
Checksums can be disabled, but it is not recommended! Checksums take very little storage space and provide data integrity. Many ZFS features will not work properly with checksums disabled. There is no noticeable performance gain from disabling these checksums.
Checksum verification is known as
scrubbing. Verify the data integrity of
the storage
pool with this command:
#
zpool scrub storage
The duration of a scrub depends on the amount of data
stored. Larger amounts of data will take proportionally
longer to verify. Scrubs are very I/O
intensive, and only one scrub is allowed to run at a time.
After the scrub completes, the status can be viewed with
status
:
#
zpool status storage
pool: storage state: ONLINE scrub: scrub completed with 0 errors on Sat Jan 26 19:57:37 2013 config: NAME STATE READ WRITE CKSUM storage ONLINE 0 0 0 raidz1 ONLINE 0 0 0 da0 ONLINE 0 0 0 da1 ONLINE 0 0 0 da2 ONLINE 0 0 0 errors: No known data errors
The completion date of the last scrub operation is displayed to help track when another scrub is required. Routine scrubs help protect data from silent corruption and ensure the integrity of the pool.
ZFS administration is divided between two
main utilities. The zpool
utility controls
the operation of the pool and deals with adding, removing,
replacing, and managing disks. The
zfs
utility
deals with creating, destroying, and managing datasets,
both file systems and
volumes.
Creating a ZFS storage pool (zpool) involves making a number of decisions that are relatively permanent because the structure of the pool cannot be changed after the pool has been created. The most important decision is what types of vdevs into which to group the physical disks. See the list of vdev types for details about the possible options. After the pool has been created, most vdev types do not allow additional disks to be added to the vdev. The exceptions are mirrors, which allow additional disks to be added to the vdev, and stripes, which can be upgraded to mirrors by attaching an additional disk to the vdev. Although additional vdevs can be added to expand a pool, the layout of the pool cannot be changed after pool creation. Instead, the data must be backed up and the pool destroyed and recreated.
Create a simple mirror pool:
#
zpool create
mypool
mirror/dev/ada1
/dev/ada2
#
zpool status
pool: mypool state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada1 ONLINE 0 0 0 ada2 ONLINE 0 0 0 errors: No known data errors
Multiple vdevs can be created at once. Specify multiple
groups of disks separated by the vdev type keyword,
mirror
in this example:
#
zpool create
pool: mypool state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada1 ONLINE 0 0 0 ada2 ONLINE 0 0 0 mirror-1 ONLINE 0 0 0 ada3 ONLINE 0 0 0 ada4 ONLINE 0 0 0 errors: No known data errorsmypool
mirror/dev/ada1
/dev/ada2
mirror/dev/ada3
/dev/ada4
Pools can also be constructed using partitions rather than whole disks. Putting ZFS in a separate partition allows the same disk to have other partitions for other purposes. In particular, partitions with bootcode and file systems needed for booting can be added. This allows booting from disks that are also members of a pool. There is no performance penalty on FreeBSD when using a partition rather than a whole disk. Using partitions also allows the administrator to under-provision the disks, using less than the full capacity. If a future replacement disk of the same nominal size as the original actually has a slightly smaller capacity, the smaller partition will still fit, and the replacement disk can still be used.
Create a RAID-Z2 pool using partitions:
#
zpool create
mypool
raidz2/dev/ada0p3
/dev/ada1p3
/dev/ada2p3
/dev/ada3p3
/dev/ada4p3
/dev/ada5p3
#
zpool status
pool: mypool state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 raidz2-0 ONLINE 0 0 0 ada0p3 ONLINE 0 0 0 ada1p3 ONLINE 0 0 0 ada2p3 ONLINE 0 0 0 ada3p3 ONLINE 0 0 0 ada4p3 ONLINE 0 0 0 ada5p3 ONLINE 0 0 0 errors: No known data errors
A pool that is no longer needed can be destroyed so that
the disks can be reused. Destroying a pool involves first
unmounting all of the datasets in that pool. If the datasets
are in use, the unmount operation will fail and the pool will
not be destroyed. The destruction of the pool can be forced
with -f
, but this can cause undefined
behavior in applications which had open files on those
datasets.
There are two cases for adding disks to a zpool: attaching
a disk to an existing vdev with
zpool attach
, or adding vdevs to the pool
with zpool add
. Only some
vdev types allow disks to
be added to the vdev after creation.
A pool created with a single disk lacks redundancy.
Corruption can be detected but
not repaired, because there is no other copy of the data.
The copies property may
be able to recover from a small failure such as a bad sector,
but does not provide the same level of protection as mirroring
or RAID-Z. Starting with a pool consisting
of a single disk vdev, zpool attach
can be
used to add an additional disk to the vdev, creating a mirror.
zpool attach
can also be used to add
additional disks to a mirror group, increasing redundancy and
read performance. If the disks being used for the pool are
partitioned, replicate the layout of the first disk on to the
second, gpart backup
and
gpart restore
can be used to make this
process easier.
Upgrade the single disk (stripe) vdev
ada0p3
to a mirror by attaching
ada1p3
:
#
zpool status
pool: mypool state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 ada0p3 ONLINE 0 0 0 errors: No known data errors#
zpool attach
Make sure to wait until resilver is done before rebooting. If you boot from pool 'mypool', you may need to update boot code on newly attached disk 'ada1p3'. Assuming you use GPT partitioning and 'da0' is your new boot disk you may use the following command: gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 da0mypool
ada0p3
ada1p3
#
gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1
bootcode written to ada1ada1
#
zpool status
pool: mypool state: ONLINE status: One or more devices is currently being resilvered. The pool will continue to function, possibly in a degraded state. action: Wait for the resilver to complete. scan: resilver in progress since Fri May 30 08:19:19 2014 527M scanned out of 781M at 47.9M/s, 0h0m to go 527M resilvered, 67.53% done config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0p3 ONLINE 0 0 0 ada1p3 ONLINE 0 0 0 (resilvering) errors: No known data errors#
zpool status
pool: mypool state: ONLINE scan: resilvered 781M in 0h0m with 0 errors on Fri May 30 08:15:58 2014 config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0p3 ONLINE 0 0 0 ada1p3 ONLINE 0 0 0 errors: No known data errors
When adding disks to the existing vdev is not an option,
as for RAID-Z, an alternative method is to
add another vdev to the pool. Additional vdevs provide higher
performance, distributing writes across the vdevs. Each vdev
is responsible for providing its own redundancy. It is
possible, but discouraged, to mix vdev types, like
mirror
and RAID-Z
.
Adding a non-redundant vdev to a pool containing mirror or
RAID-Z vdevs risks the data on the entire
pool. Writes are distributed, so the failure of the
non-redundant disk will result in the loss of a fraction of
every block that has been written to the pool.
Data is striped across each of the vdevs. For example, with two mirror vdevs, this is effectively a RAID 10 that stripes writes across two sets of mirrors. Space is allocated so that each vdev reaches 100% full at the same time. There is a performance penalty if the vdevs have different amounts of free space, as a disproportionate amount of the data is written to the less full vdev.
When attaching additional devices to a boot pool, remember to update the bootcode.
Attach a second mirror group (ada2p3
and ada3p3
) to the existing
mirror:
#
zpool status
pool: mypool state: ONLINE scan: resilvered 781M in 0h0m with 0 errors on Fri May 30 08:19:35 2014 config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0p3 ONLINE 0 0 0 ada1p3 ONLINE 0 0 0 errors: No known data errors#
zpool add
mypool
mirrorada2p3
ada3p3
#
gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1
bootcode written to ada2ada2
#
gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1
bootcode written to ada3ada3
#
zpool status
pool: mypool state: ONLINE scan: scrub repaired 0 in 0h0m with 0 errors on Fri May 30 08:29:51 2014 config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0p3 ONLINE 0 0 0 ada1p3 ONLINE 0 0 0 mirror-1 ONLINE 0 0 0 ada2p3 ONLINE 0 0 0 ada3p3 ONLINE 0 0 0 errors: No known data errors
Currently, vdevs cannot be removed from a pool, and disks can only be removed from a mirror if there is enough remaining redundancy. If only one disk in a mirror group remains, it ceases to be a mirror and reverts to being a stripe, risking the entire pool if that remaining disk fails.
Remove a disk from a three-way mirror group:
#
zpool status
pool: mypool state: ONLINE scan: scrub repaired 0 in 0h0m with 0 errors on Fri May 30 08:29:51 2014 config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0p3 ONLINE 0 0 0 ada1p3 ONLINE 0 0 0 ada2p3 ONLINE 0 0 0 errors: No known data errors#
zpool detach
mypool
ada2p3
#
zpool status
pool: mypool state: ONLINE scan: scrub repaired 0 in 0h0m with 0 errors on Fri May 30 08:29:51 2014 config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0p3 ONLINE 0 0 0 ada1p3 ONLINE 0 0 0 errors: No known data errors
Pool status is important. If a drive goes offline or a
read, write, or checksum error is detected, the corresponding
error count increases. The status
output
shows the configuration and status of each device in the pool
and the status of the entire pool. Actions that need to be
taken and details about the last scrub
are also shown.
#
zpool status
pool: mypool state: ONLINE scan: scrub repaired 0 in 2h25m with 0 errors on Sat Sep 14 04:25:50 2013 config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 raidz2-0 ONLINE 0 0 0 ada0p3 ONLINE 0 0 0 ada1p3 ONLINE 0 0 0 ada2p3 ONLINE 0 0 0 ada3p3 ONLINE 0 0 0 ada4p3 ONLINE 0 0 0 ada5p3 ONLINE 0 0 0 errors: No known data errors
When an error is detected, the read, write, or checksum
counts are incremented. The error message can be cleared and
the counts reset with zpool clear
. Clearing the
error state can be important for automated scripts that alert
the administrator when the pool encounters an error. Further
errors may not be reported if the old errors are not
cleared.mypool
There are a number of situations where it may be
desirable to replace one disk with a different disk. When
replacing a working disk, the process keeps the old disk
online during the replacement. The pool never enters a
degraded state,
reducing the risk of data loss.
zpool replace
copies all of the data from
the old disk to the new one. After the operation completes,
the old disk is disconnected from the vdev. If the new disk
is larger than the old disk, it may be possible to grow the
zpool, using the new space. See Growing a Pool.
Replace a functioning device in the pool:
#
zpool status
pool: mypool state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0p3 ONLINE 0 0 0 ada1p3 ONLINE 0 0 0 errors: No known data errors#
zpool replace
Make sure to wait until resilver is done before rebooting. If you boot from pool 'zroot', you may need to update boot code on newly attached disk 'ada2p3'. Assuming you use GPT partitioning and 'da0' is your new boot disk you may use the following command: gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 da0mypool
ada1p3
ada2p3
#
gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1
ada2
#
zpool status
pool: mypool state: ONLINE status: One or more devices is currently being resilvered. The pool will continue to function, possibly in a degraded state. action: Wait for the resilver to complete. scan: resilver in progress since Mon Jun 2 14:21:35 2014 604M scanned out of 781M at 46.5M/s, 0h0m to go 604M resilvered, 77.39% done config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0p3 ONLINE 0 0 0 replacing-1 ONLINE 0 0 0 ada1p3 ONLINE 0 0 0 ada2p3 ONLINE 0 0 0 (resilvering) errors: No known data errors#
zpool status
pool: mypool state: ONLINE scan: resilvered 781M in 0h0m with 0 errors on Mon Jun 2 14:21:52 2014 config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0p3 ONLINE 0 0 0 ada2p3 ONLINE 0 0 0 errors: No known data errors
When a disk in a pool fails, the vdev to which the disk belongs enters the degraded state. All of the data is still available, but performance may be reduced because missing data must be calculated from the available redundancy. To restore the vdev to a fully functional state, the failed physical device must be replaced. ZFS is then instructed to begin the resilver operation. Data that was on the failed device is recalculated from available redundancy and written to the replacement device. After completion, the vdev returns to online status.
If the vdev does not have any redundancy, or if multiple devices have failed and there is not enough redundancy to compensate, the pool enters the faulted state. If a sufficient number of devices cannot be reconnected to the pool, the pool becomes inoperative and data must be restored from backups.
When replacing a failed disk, the name of the failed disk
is replaced with the GUID of the device.
A new device name parameter for
zpool replace
is not required if the
replacement device has the same device name.
Replace a failed disk using
zpool replace
:
#
zpool status
pool: mypool state: DEGRADED status: One or more devices could not be opened. Sufficient replicas exist for the pool to continue functioning in a degraded state. action: Attach the missing device and online it using 'zpool online'. see: http://illumos.org/msg/ZFS-8000-2Q scan: none requested config: NAME STATE READ WRITE CKSUM mypool DEGRADED 0 0 0 mirror-0 DEGRADED 0 0 0 ada0p3 ONLINE 0 0 0 316502962686821739 UNAVAIL 0 0 0 was /dev/ada1p3 errors: No known data errors#
zpool replace
mypool
316502962686821739
ada2p3
#
zpool status
pool: mypool state: DEGRADED status: One or more devices is currently being resilvered. The pool will continue to function, possibly in a degraded state. action: Wait for the resilver to complete. scan: resilver in progress since Mon Jun 2 14:52:21 2014 641M scanned out of 781M at 49.3M/s, 0h0m to go 640M resilvered, 82.04% done config: NAME STATE READ WRITE CKSUM mypool DEGRADED 0 0 0 mirror-0 DEGRADED 0 0 0 ada0p3 ONLINE 0 0 0 replacing-1 UNAVAIL 0 0 0 15732067398082357289 UNAVAIL 0 0 0 was /dev/ada1p3/old ada2p3 ONLINE 0 0 0 (resilvering) errors: No known data errors#
zpool status
pool: mypool state: ONLINE scan: resilvered 781M in 0h0m with 0 errors on Mon Jun 2 14:52:38 2014 config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0p3 ONLINE 0 0 0 ada2p3 ONLINE 0 0 0 errors: No known data errors
It is recommended that pools be
scrubbed regularly,
ideally at least once every month. The
scrub
operation is very disk-intensive and
will reduce performance while running. Avoid high-demand
periods when scheduling scrub
or use vfs.zfs.scrub_delay
to adjust the relative priority of the
scrub
to prevent it interfering with other
workloads.
#
zpool scrub
mypool
#
zpool status
pool: mypool state: ONLINE scan: scrub in progress since Wed Feb 19 20:52:54 2014 116G scanned out of 8.60T at 649M/s, 3h48m to go 0 repaired, 1.32% done config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 raidz2-0 ONLINE 0 0 0 ada0p3 ONLINE 0 0 0 ada1p3 ONLINE 0 0 0 ada2p3 ONLINE 0 0 0 ada3p3 ONLINE 0 0 0 ada4p3 ONLINE 0 0 0 ada5p3 ONLINE 0 0 0 errors: No known data errors
In the event that a scrub operation needs to be cancelled,
issue zpool scrub -s
.mypool
The checksums stored with data blocks enable the file system to self-heal. This feature will automatically repair data whose checksum does not match the one recorded on another device that is part of the storage pool. For example, a mirror with two disks where one drive is starting to malfunction and cannot properly store the data any more. This is even worse when the data has not been accessed for a long time, as with long term archive storage. Traditional file systems need to run algorithms that check and repair the data like fsck(8). These commands take time, and in severe cases, an administrator has to manually decide which repair operation must be performed. When ZFS detects a data block with a checksum that does not match, it tries to read the data from the mirror disk. If that disk can provide the correct data, it will not only give that data to the application requesting it, but also correct the wrong data on the disk that had the bad checksum. This happens without any interaction from a system administrator during normal pool operation.
The next example demonstrates this self-healing behavior.
A mirrored pool of disks /dev/ada0
and
/dev/ada1
is created.
#
zpool create
healer
mirror/dev/ada0
/dev/ada1
#
zpool status
pool: healer state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM healer ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0 ONLINE 0 0 0 ada1 ONLINE 0 0 0 errors: No known data errorshealer
#
zpool list
NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT healer 960M 92.5K 960M - - 0% 0% 1.00x ONLINE -
Some important data that to be protected from data errors using the self-healing feature is copied to the pool. A checksum of the pool is created for later comparison.
#
cp /some/important/data /healer
#
zfs list
NAME SIZE ALLOC FREE CAP DEDUP HEALTH ALTROOT healer 960M 67.7M 892M 7% 1.00x ONLINE -#
sha1 /healer > checksum.txt
#
cat checksum.txt
SHA1 (/healer) = 2753eff56d77d9a536ece6694bf0a82740344d1f
Data corruption is simulated by writing random data to the beginning of one of the disks in the mirror. To prevent ZFS from healing the data as soon as it is detected, the pool is exported before the corruption and imported again afterwards.
This is a dangerous operation that can destroy vital data. It is shown here for demonstrational purposes only and should not be attempted during normal operation of a storage pool. Nor should this intentional corruption example be run on any disk with a different file system on it. Do not use any other disk device names other than the ones that are part of the pool. Make certain that proper backups of the pool are created before running the command!
#
zpool export
healer
#
dd if=/dev/random of=/dev/ada1 bs=1m count=200
200+0 records in 200+0 records out 209715200 bytes transferred in 62.992162 secs (3329227 bytes/sec)#
zpool import healer
The pool status shows that one device has experienced an
error. Note that applications reading data from the pool did
not receive any incorrect data. ZFS
provided data from the ada0
device with
the correct checksums. The device with the wrong checksum can
be found easily as the CKSUM
column
contains a nonzero value.
#
zpool status
pool: healer state: ONLINE status: One or more devices has experienced an unrecoverable error. An attempt was made to correct the error. Applications are unaffected. action: Determine if the device needs to be replaced, and clear the errors using 'zpool clear' or replace the device with 'zpool replace'. see: http://illumos.org/msg/ZFS-8000-4J scan: none requested config: NAME STATE READ WRITE CKSUM healer ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0 ONLINE 0 0 0 ada1 ONLINE 0 0 1 errors: No known data errorshealer
The error was detected and handled by using the redundancy
present in the unaffected ada0
mirror
disk. A checksum comparison with the original one will reveal
whether the pool is consistent again.
#
sha1 /healer >> checksum.txt
#
cat checksum.txt
SHA1 (/healer) = 2753eff56d77d9a536ece6694bf0a82740344d1f SHA1 (/healer) = 2753eff56d77d9a536ece6694bf0a82740344d1f
The two checksums that were generated before and after the
intentional tampering with the pool data still match. This
shows how ZFS is capable of detecting and
correcting any errors automatically when the checksums differ.
Note that this is only possible when there is enough
redundancy present in the pool. A pool consisting of a single
device has no self-healing capabilities. That is also the
reason why checksums are so important in
ZFS and should not be disabled for any
reason. No fsck(8) or similar file system consistency
check program is required to detect and correct this and the
pool was still available during the time there was a problem.
A scrub operation is now required to overwrite the corrupted
data on ada1
.
#
zpool scrub
healer
#
zpool status
pool: healer state: ONLINE status: One or more devices has experienced an unrecoverable error. An attempt was made to correct the error. Applications are unaffected. action: Determine if the device needs to be replaced, and clear the errors using 'zpool clear' or replace the device with 'zpool replace'. see: http://illumos.org/msg/ZFS-8000-4J scan: scrub in progress since Mon Dec 10 12:23:30 2012 10.4M scanned out of 67.0M at 267K/s, 0h3m to go 9.63M repaired, 15.56% done config: NAME STATE READ WRITE CKSUM healer ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0 ONLINE 0 0 0 ada1 ONLINE 0 0 627 (repairing) errors: No known data errorshealer
The scrub operation reads data from
ada0
and rewrites any data with an
incorrect checksum on ada1
. This is
indicated by the (repairing)
output from
zpool status
. After the operation is
complete, the pool status changes to:
#
zpool status
pool: healer state: ONLINE status: One or more devices has experienced an unrecoverable error. An attempt was made to correct the error. Applications are unaffected. action: Determine if the device needs to be replaced, and clear the errors using 'zpool clear' or replace the device with 'zpool replace'. see: http://illumos.org/msg/ZFS-8000-4J scan: scrub repaired 66.5M in 0h2m with 0 errors on Mon Dec 10 12:26:25 2012 config: NAME STATE READ WRITE CKSUM healer ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0 ONLINE 0 0 0 ada1 ONLINE 0 0 2.72K errors: No known data errorshealer
After the scrub operation completes and all the data
has been synchronized from ada0
to
ada1
, the error messages can be
cleared from the pool
status by running zpool clear
.
#
zpool clear
healer
#
zpool status
pool: healer state: ONLINE scan: scrub repaired 66.5M in 0h2m with 0 errors on Mon Dec 10 12:26:25 2012 config: NAME STATE READ WRITE CKSUM healer ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0 ONLINE 0 0 0 ada1 ONLINE 0 0 0 errors: No known data errorshealer
The pool is now back to a fully working state and all the errors have been cleared.
The usable size of a redundant pool is limited by the capacity of the smallest device in each vdev. The smallest device can be replaced with a larger device. After completing a replace or resilver operation, the pool can grow to use the capacity of the new device. For example, consider a mirror of a 1 TB drive and a 2 TB drive. The usable space is 1 TB. When the 1 TB drive is replaced with another 2 TB drive, the resilvering process copies the existing data onto the new drive. Because both of the devices now have 2 TB capacity, the mirror's available space can be grown to 2 TB.
Expansion is triggered by using
zpool online -e
on each device. After
expansion of all devices, the additional space becomes
available to the pool.
Pools are exported before moving them
to another system. All datasets are unmounted, and each
device is marked as exported but still locked so it cannot be
used by other disk subsystems. This allows pools to be
imported on other machines, other
operating systems that support ZFS, and
even different hardware architectures (with some caveats, see
zpool(8)). When a dataset has open files,
zpool export -f
can be used to force the
export of a pool. Use this with caution. The datasets are
forcibly unmounted, potentially resulting in unexpected
behavior by the applications which had open files on those
datasets.
Export a pool that is not in use:
#
zpool export mypool
Importing a pool automatically mounts the datasets. This
may not be the desired behavior, and can be prevented with
zpool import -N
.
zpool import -o
sets temporary properties
for this import only.
zpool import altroot=
allows importing a
pool with a base mount point instead of the root of the file
system. If the pool was last used on a different system and
was not properly exported, an import might have to be forced
with zpool import -f
.
zpool import -a
imports all pools that do
not appear to be in use by another system.
List all available pools for import:
#
zpool import
pool: mypool id: 9930174748043525076 state: ONLINE action: The pool can be imported using its name or numeric identifier. config: mypool ONLINE ada2p3 ONLINE
Import the pool with an alternative root directory:
#
zpool import -o altroot=
/mnt
mypool
#
zfs list
zfs list NAME USED AVAIL REFER MOUNTPOINT mypool 110K 47.0G 31K /mnt/mypool
After upgrading FreeBSD, or if a pool has been imported from a system using an older version of ZFS, the pool can be manually upgraded to the latest version of ZFS to support newer features. Consider whether the pool may ever need to be imported on an older system before upgrading. Upgrading is a one-way process. Older pools can be upgraded, but pools with newer features cannot be downgraded.
Upgrade a v28 pool to support
Feature Flags
:
#
zpool status
pool: mypool state: ONLINE status: The pool is formatted using a legacy on-disk format. The pool can still be used, but some features are unavailable. action: Upgrade the pool using 'zpool upgrade'. Once this is done, the pool will no longer be accessible on software that does not support feat flags. scan: none requested config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0 ONLINE 0 0 0 ada1 ONLINE 0 0 0 errors: No known data errors#
zpool upgrade
This system supports ZFS pool feature flags. The following pools are formatted with legacy version numbers and can be upgraded to use feature flags. After being upgraded, these pools will no longer be accessible by software that does not support feature flags. VER POOL --- ------------ 28 mypool Use 'zpool upgrade -v' for a list of available legacy versions. Every feature flags pool has all supported features enabled.#
zpool upgrade mypool
This system supports ZFS pool feature flags. Successfully upgraded 'mypool' from version 28 to feature flags. Enabled the following features on 'mypool': async_destroy empty_bpobj lz4_compress multi_vdev_crash_dump
The newer features of ZFS will not be
available until zpool upgrade
has
completed. zpool upgrade -v
can be used to
see what new features will be provided by upgrading, as well
as which features are already supported.
Upgrade a pool to support additional feature flags:
#
zpool status
pool: mypool state: ONLINE status: Some supported features are not enabled on the pool. The pool can still be used, but some features are unavailable. action: Enable all features using 'zpool upgrade'. Once this is done, the pool may no longer be accessible by software that does not support the features. See zpool-features(7) for details. scan: none requested config: NAME STATE READ WRITE CKSUM mypool ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 ada0 ONLINE 0 0 0 ada1 ONLINE 0 0 0 errors: No known data errors#
zpool upgrade
This system supports ZFS pool feature flags. All pools are formatted using feature flags. Some supported features are not enabled on the following pools. Once a feature is enabled the pool may become incompatible with software that does not support the feature. See zpool-features(7) for details. POOL FEATURE --------------- zstore multi_vdev_crash_dump spacemap_histogram enabled_txg hole_birth extensible_dataset bookmarks filesystem_limits#
zpool upgrade mypool
This system supports ZFS pool feature flags. Enabled the following features on 'mypool': spacemap_histogram enabled_txg hole_birth extensible_dataset bookmarks filesystem_limits
The boot code on systems that boot from a pool must be
updated to support the new pool version. Use
gpart bootcode
on the partition that
contains the boot code. There are two types of bootcode
available, depending on way the system boots:
GPT (the most common option) and
EFI (for more modern systems).
For legacy boot using GPT, use the following command:
#
gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i
1
ada1
For systems using EFI to boot, execute the following command:
#
gpart bootcode -p /boot/boot1.efifat -i
1
ada1
Apply the bootcode to all bootable disks in the pool. See gpart(8) for more information.
Commands that modify the pool are recorded. Recorded
actions include the creation of datasets, changing properties,
or replacement of a disk. This history is useful for
reviewing how a pool was created and which user performed a
specific action and when. History is not kept in a log file,
but is part of the pool itself. The command to review this
history is aptly named
zpool history
:
#
zpool history
History for 'tank': 2013-02-26.23:02:35 zpool create tank mirror /dev/ada0 /dev/ada1 2013-02-27.18:50:58 zfs set atime=off tank 2013-02-27.18:51:09 zfs set checksum=fletcher4 tank 2013-02-27.18:51:18 zfs create tank/backup
The output shows zpool
and
zfs
commands that were executed on the pool
along with a timestamp. Only commands that alter the pool in
some way are recorded. Commands like
zfs list
are not included. When no pool
name is specified, the history of all pools is
displayed.
zpool history
can show even more
information when the options -i
or
-l
are provided. -i
displays user-initiated events as well as internally logged
ZFS events.
#
zpool history -i
History for 'tank': 2013-02-26.23:02:35 [internal pool create txg:5] pool spa 28; zfs spa 28; zpl 5;uts 9.1-RELEASE 901000 amd64 2013-02-27.18:50:53 [internal property set txg:50] atime=0 dataset = 21 2013-02-27.18:50:58 zfs set atime=off tank 2013-02-27.18:51:04 [internal property set txg:53] checksum=7 dataset = 21 2013-02-27.18:51:09 zfs set checksum=fletcher4 tank 2013-02-27.18:51:13 [internal create txg:55] dataset = 39 2013-02-27.18:51:18 zfs create tank/backup
More details can be shown by adding -l
.
History records are shown in a long format, including
information like the name of the user who issued the command
and the hostname on which the change was made.
#
zpool history -l
History for 'tank': 2013-02-26.23:02:35 zpool create tank mirror /dev/ada0 /dev/ada1 [user 0 (root) on :global] 2013-02-27.18:50:58 zfs set atime=off tank [user 0 (root) on myzfsbox:global] 2013-02-27.18:51:09 zfs set checksum=fletcher4 tank [user 0 (root) on myzfsbox:global] 2013-02-27.18:51:18 zfs create tank/backup [user 0 (root) on myzfsbox:global]
The output shows that the
root
user created
the mirrored pool with disks
/dev/ada0
and
/dev/ada1
. The hostname
myzfsbox
is also
shown in the commands after the pool's creation. The hostname
display becomes important when the pool is exported from one
system and imported on another. The commands that are issued
on the other system can clearly be distinguished by the
hostname that is recorded for each command.
Both options to zpool history
can be
combined to give the most detailed information possible for
any given pool. Pool history provides valuable information
when tracking down the actions that were performed or when
more detailed output is needed for debugging.
A built-in monitoring system can display pool I/O statistics in real time. It shows the amount of free and used space on the pool, how many read and write operations are being performed per second, and how much I/O bandwidth is currently being utilized. By default, all pools in the system are monitored and displayed. A pool name can be provided to limit monitoring to just that pool. A basic example:
#
zpool iostat
capacity operations bandwidth pool alloc free read write read write ---------- ----- ----- ----- ----- ----- ----- data 288G 1.53T 2 11 11.3K 57.1K
To continuously monitor I/O activity, a number can be specified as the last parameter, indicating a interval in seconds to wait between updates. The next statistic line is printed after each interval. Press Ctrl+C to stop this continuous monitoring. Alternatively, give a second number on the command line after the interval to specify the total number of statistics to display.
Even more detailed I/O statistics can
be displayed with -v
. Each device in the
pool is shown with a statistics line. This is useful in
seeing how many read and write operations are being performed
on each device, and can help determine if any individual
device is slowing down the pool. This example shows a
mirrored pool with two devices:
#
zpool iostat -v
capacity operations bandwidth pool alloc free read write read write ----------------------- ----- ----- ----- ----- ----- ----- data 288G 1.53T 2 12 9.23K 61.5K mirror 288G 1.53T 2 12 9.23K 61.5K ada1 - - 0 4 5.61K 61.7K ada2 - - 1 4 5.04K 61.7K ----------------------- ----- ----- ----- ----- ----- -----
A pool consisting of one or more mirror vdevs can be split
into two pools. Unless otherwise specified, the last member
of each mirror is detached and used to create a new pool
containing the same data. The operation should first be
attempted with -n
. The details of the
proposed operation are displayed without it actually being
performed. This helps confirm that the operation will do what
the user intends.
The zfs
utility is responsible for
creating, destroying, and managing all ZFS
datasets that exist within a pool. The pool is managed using
zpool
.
Unlike traditional disks and volume managers, space in
ZFS is not
preallocated. With traditional file systems, after all of the
space is partitioned and assigned, there is no way to add an
additional file system without adding a new disk. With
ZFS, new file systems can be created at any
time. Each dataset
has properties including features like compression,
deduplication, caching, and quotas, as well as other useful
properties like readonly, case sensitivity, network file
sharing, and a mount point. Datasets can be nested inside
each other, and child datasets will inherit properties from
their parents. Each dataset can be administered,
delegated,
replicated,
snapshotted,
jailed, and destroyed as a
unit. There are many advantages to creating a separate
dataset for each different type or set of files. The only
drawbacks to having an extremely large number of datasets is
that some commands like zfs list
will be
slower, and the mounting of hundreds or even thousands of
datasets can slow the FreeBSD boot process.
Create a new dataset and enable LZ4 compression on it:
#
zfs list
NAME USED AVAIL REFER MOUNTPOINT mypool 781M 93.2G 144K none mypool/ROOT 777M 93.2G 144K none mypool/ROOT/default 777M 93.2G 777M / mypool/tmp 176K 93.2G 176K /tmp mypool/usr 616K 93.2G 144K /usr mypool/usr/home 184K 93.2G 184K /usr/home mypool/usr/ports 144K 93.2G 144K /usr/ports mypool/usr/src 144K 93.2G 144K /usr/src mypool/var 1.20M 93.2G 608K /var mypool/var/crash 148K 93.2G 148K /var/crash mypool/var/log 178K 93.2G 178K /var/log mypool/var/mail 144K 93.2G 144K /var/mail mypool/var/tmp 152K 93.2G 152K /var/tmp#
zfs create -o compress=lz4
mypool/usr/mydataset
#
zfs list
NAME USED AVAIL REFER MOUNTPOINT mypool 781M 93.2G 144K none mypool/ROOT 777M 93.2G 144K none mypool/ROOT/default 777M 93.2G 777M / mypool/tmp 176K 93.2G 176K /tmp mypool/usr 704K 93.2G 144K /usr mypool/usr/home 184K 93.2G 184K /usr/home mypool/usr/mydataset 87.5K 93.2G 87.5K /usr/mydataset mypool/usr/ports 144K 93.2G 144K /usr/ports mypool/usr/src 144K 93.2G 144K /usr/src mypool/var 1.20M 93.2G 610K /var mypool/var/crash 148K 93.2G 148K /var/crash mypool/var/log 178K 93.2G 178K /var/log mypool/var/mail 144K 93.2G 144K /var/mail mypool/var/tmp 152K 93.2G 152K /var/tmp
Destroying a dataset is much quicker than deleting all of the files that reside on the dataset, as it does not involve scanning all of the files and updating all of the corresponding metadata.
Destroy the previously-created dataset:
#
zfs list
NAME USED AVAIL REFER MOUNTPOINT mypool 880M 93.1G 144K none mypool/ROOT 777M 93.1G 144K none mypool/ROOT/default 777M 93.1G 777M / mypool/tmp 176K 93.1G 176K /tmp mypool/usr 101M 93.1G 144K /usr mypool/usr/home 184K 93.1G 184K /usr/home mypool/usr/mydataset 100M 93.1G 100M /usr/mydataset mypool/usr/ports 144K 93.1G 144K /usr/ports mypool/usr/src 144K 93.1G 144K /usr/src mypool/var 1.20M 93.1G 610K /var mypool/var/crash 148K 93.1G 148K /var/crash mypool/var/log 178K 93.1G 178K /var/log mypool/var/mail 144K 93.1G 144K /var/mail mypool/var/tmp 152K 93.1G 152K /var/tmp#
zfs destroy
mypool/usr/mydataset
#
zfs list
NAME USED AVAIL REFER MOUNTPOINT mypool 781M 93.2G 144K none mypool/ROOT 777M 93.2G 144K none mypool/ROOT/default 777M 93.2G 777M / mypool/tmp 176K 93.2G 176K /tmp mypool/usr 616K 93.2G 144K /usr mypool/usr/home 184K 93.2G 184K /usr/home mypool/usr/ports 144K 93.2G 144K /usr/ports mypool/usr/src 144K 93.2G 144K /usr/src mypool/var 1.21M 93.2G 612K /var mypool/var/crash 148K 93.2G 148K /var/crash mypool/var/log 178K 93.2G 178K /var/log mypool/var/mail 144K 93.2G 144K /var/mail mypool/var/tmp 152K 93.2G 152K /var/tmp
In modern versions of ZFS,
zfs destroy
is asynchronous, and the free
space might take several minutes to appear in the pool. Use
zpool get freeing
to see the
poolname
freeing
property, indicating how many
datasets are having their blocks freed in the background.
If there are child datasets, like
snapshots or other
datasets, then the parent cannot be destroyed. To destroy a
dataset and all of its children, use -r
to
recursively destroy the dataset and all of its children.
Use -n
-v
to list datasets
and snapshots that would be destroyed by this operation, but
do not actually destroy anything. Space that would be
reclaimed by destruction of snapshots is also shown.
A volume is a special type of dataset. Rather than being
mounted as a file system, it is exposed as a block device
under
/dev/zvol/
.
This allows the volume to be used for other file systems, to
back the disks of a virtual machine, or to be exported using
protocols like iSCSI or
HAST.poolname
/dataset
A volume can be formatted with any file system, or used without a file system to store raw data. To the user, a volume appears to be a regular disk. Putting ordinary file systems on these zvols provides features that ordinary disks or file systems do not normally have. For example, using the compression property on a 250 MB volume allows creation of a compressed FAT file system.
#
zfs create -V 250m -o compression=on tank/fat32
#
zfs list tank
NAME USED AVAIL REFER MOUNTPOINT tank 258M 670M 31K /tank#
newfs_msdos -F32 /dev/zvol/tank/fat32
#
mount -t msdosfs /dev/zvol/tank/fat32 /mnt
#
df -h /mnt | grep fat32
Filesystem Size Used Avail Capacity Mounted on /dev/zvol/tank/fat32 249M 24k 249M 0% /mnt#
mount | grep fat32
/dev/zvol/tank/fat32 on /mnt (msdosfs, local)
Destroying a volume is much the same as destroying a regular file system dataset. The operation is nearly instantaneous, but it may take several minutes for the free space to be reclaimed in the background.
The name of a dataset can be changed with
zfs rename
. The parent of a dataset can
also be changed with this command. Renaming a dataset to be
under a different parent dataset will change the value of
those properties that are inherited from the parent dataset.
When a dataset is renamed, it is unmounted and then remounted
in the new location (which is inherited from the new parent
dataset). This behavior can be prevented with
-u
.
Rename a dataset and move it to be under a different parent dataset:
#
zfs list
NAME USED AVAIL REFER MOUNTPOINT mypool 780M 93.2G 144K none mypool/ROOT 777M 93.2G 144K none mypool/ROOT/default 777M 93.2G 777M / mypool/tmp 176K 93.2G 176K /tmp mypool/usr 704K 93.2G 144K /usr mypool/usr/home 184K 93.2G 184K /usr/home mypool/usr/mydataset 87.5K 93.2G 87.5K /usr/mydataset mypool/usr/ports 144K 93.2G 144K /usr/ports mypool/usr/src 144K 93.2G 144K /usr/src mypool/var 1.21M 93.2G 614K /var mypool/var/crash 148K 93.2G 148K /var/crash mypool/var/log 178K 93.2G 178K /var/log mypool/var/mail 144K 93.2G 144K /var/mail mypool/var/tmp 152K 93.2G 152K /var/tmp#
zfs rename
mypool/usr/mydataset
mypool/var/newname
#
zfs list
NAME USED AVAIL REFER MOUNTPOINT mypool 780M 93.2G 144K none mypool/ROOT 777M 93.2G 144K none mypool/ROOT/default 777M 93.2G 777M / mypool/tmp 176K 93.2G 176K /tmp mypool/usr 616K 93.2G 144K /usr mypool/usr/home 184K 93.2G 184K /usr/home mypool/usr/ports 144K 93.2G 144K /usr/ports mypool/usr/src 144K 93.2G 144K /usr/src mypool/var 1.29M 93.2G 614K /var mypool/var/crash 148K 93.2G 148K /var/crash mypool/var/log 178K 93.2G 178K /var/log mypool/var/mail 144K 93.2G 144K /var/mail mypool/var/newname 87.5K 93.2G 87.5K /var/newname mypool/var/tmp 152K 93.2G 152K /var/tmp
Snapshots can also be renamed like this. Due to the
nature of snapshots, they cannot be renamed into a different
parent dataset. To rename a recursive snapshot, specify
-r
, and all snapshots with the same name in
child datasets with also be renamed.
#
zfs list -t snapshot
NAME USED AVAIL REFER MOUNTPOINT mypool/var/newname@first_snapshot 0 - 87.5K -#
zfs rename
mypool/var/newname@first_snapshot
new_snapshot_name
#
zfs list -t snapshot
NAME USED AVAIL REFER MOUNTPOINT mypool/var/newname@new_snapshot_name 0 - 87.5K -
Each ZFS dataset has a number of
properties that control its behavior. Most properties are
automatically inherited from the parent dataset, but can be
overridden locally. Set a property on a dataset with
zfs set
. Most
properties have a limited set of valid values,
property
=value
dataset
zfs get
will display each possible property
and valid values. Most properties can be reverted to their
inherited values using zfs inherit
.
User-defined properties can also be set. They become part
of the dataset configuration and can be used to provide
additional information about the dataset or its contents. To
distinguish these custom properties from the ones supplied as
part of ZFS, a colon (:
)
is used to create a custom namespace for the property.
#
zfs set
custom
:costcenter
=1234
tank
#
zfs get
NAME PROPERTY VALUE SOURCE tank custom:costcenter 1234 localcustom
:costcenter
tank
To remove a custom property, use
zfs inherit
with -r
. If
the custom property is not defined in any of the parent
datasets, it will be removed completely (although the changes
are still recorded in the pool's history).
#
zfs inherit -r
custom
:costcenter
tank
#
zfs get
NAME PROPERTY VALUE SOURCE tank custom:costcenter - -custom
:costcenter
tank
#
zfs get all
tank
| grepcustom
:costcenter
#
Two commonly used and useful dataset properties are the NFS and SMB share options. Setting these define if and how ZFS datasets may be shared on the network. At present, only setting sharing via NFS is supported on FreeBSD. To get the current status of a share, enter:
#
zfs get sharenfs
NAME PROPERTY VALUE SOURCE mypool/usr/home sharenfs on localmypool/usr/home
#
zfs get sharesmb
NAME PROPERTY VALUE SOURCE mypool/usr/home sharesmb off localmypool/usr/home
To enable sharing of a dataset, enter:
#
zfs set sharenfs=on
mypool/usr/home
It is also possible to set additional options for sharing
datasets through NFS, such as
-alldirs
, -maproot
and
-network
. To set additional options to a
dataset shared through NFS, enter:
#
zfs set sharenfs="-alldirs,-maproot=
root
,-network=192.168.1.0/24
"mypool/usr/home
Snapshots are one
of the most powerful features of ZFS. A
snapshot provides a read-only, point-in-time copy of the
dataset. With Copy-On-Write (COW),
snapshots can be created quickly by preserving the older
version of the data on disk. If no snapshots exist, space is
reclaimed for future use when data is rewritten or deleted.
Snapshots preserve disk space by recording only the
differences between the current dataset and a previous
version. Snapshots are allowed only on whole datasets, not on
individual files or directories. When a snapshot is created
from a dataset, everything contained in it is duplicated.
This includes the file system properties, files, directories,
permissions, and so on. Snapshots use no additional space
when they are first created, only consuming space as the
blocks they reference are changed. Recursive snapshots taken
with -r
create a snapshot with the same name
on the dataset and all of its children, providing a consistent
moment-in-time snapshot of all of the file systems. This can
be important when an application has files on multiple
datasets that are related or dependent upon each other.
Without snapshots, a backup would have copies of the files
from different points in time.
Snapshots in ZFS provide a variety of features that even other file systems with snapshot functionality lack. A typical example of snapshot use is to have a quick way of backing up the current state of the file system when a risky action like a software installation or a system upgrade is performed. If the action fails, the snapshot can be rolled back and the system has the same state as when the snapshot was created. If the upgrade was successful, the snapshot can be deleted to free up space. Without snapshots, a failed upgrade often requires a restore from backup, which is tedious, time consuming, and may require downtime during which the system cannot be used. Snapshots can be rolled back quickly, even while the system is running in normal operation, with little or no downtime. The time savings are enormous with multi-terabyte storage systems and the time required to copy the data from backup. Snapshots are not a replacement for a complete backup of a pool, but can be used as a quick and easy way to store a copy of the dataset at a specific point in time.
Snapshots are created with zfs snapshot
.
Adding dataset
@snapshotname
-r
creates a snapshot recursively,
with the same name on all child datasets.
Create a recursive snapshot of the entire pool:
#
zfs list -t all
NAME USED AVAIL REFER MOUNTPOINT mypool 780M 93.2G 144K none mypool/ROOT 777M 93.2G 144K none mypool/ROOT/default 777M 93.2G 777M / mypool/tmp 176K 93.2G 176K /tmp mypool/usr 616K 93.2G 144K /usr mypool/usr/home 184K 93.2G 184K /usr/home mypool/usr/ports 144K 93.2G 144K /usr/ports mypool/usr/src 144K 93.2G 144K /usr/src mypool/var 1.29M 93.2G 616K /var mypool/var/crash 148K 93.2G 148K /var/crash mypool/var/log 178K 93.2G 178K /var/log mypool/var/mail 144K 93.2G 144K /var/mail mypool/var/newname 87.5K 93.2G 87.5K /var/newname mypool/var/newname@new_snapshot_name 0 - 87.5K - mypool/var/tmp 152K 93.2G 152K /var/tmp#
zfs snapshot -r
mypool@my_recursive_snapshot
#
zfs list -t snapshot
NAME USED AVAIL REFER MOUNTPOINT mypool@my_recursive_snapshot 0 - 144K - mypool/ROOT@my_recursive_snapshot 0 - 144K - mypool/ROOT/default@my_recursive_snapshot 0 - 777M - mypool/tmp@my_recursive_snapshot 0 - 176K - mypool/usr@my_recursive_snapshot 0 - 144K - mypool/usr/home@my_recursive_snapshot 0 - 184K - mypool/usr/ports@my_recursive_snapshot 0 - 144K - mypool/usr/src@my_recursive_snapshot 0 - 144K - mypool/var@my_recursive_snapshot 0 - 616K - mypool/var/crash@my_recursive_snapshot 0 - 148K - mypool/var/log@my_recursive_snapshot 0 - 178K - mypool/var/mail@my_recursive_snapshot 0 - 144K - mypool/var/newname@new_snapshot_name 0 - 87.5K - mypool/var/newname@my_recursive_snapshot 0 - 87.5K - mypool/var/tmp@my_recursive_snapshot 0 - 152K -
Snapshots are not shown by a normal
zfs list
operation. To list snapshots,
-t snapshot
is appended to
zfs list
. -t all
displays both file systems and snapshots.
Snapshots are not mounted directly, so path is shown in
the MOUNTPOINT
column. There is no
mention of available disk space in the
AVAIL
column, as snapshots cannot be
written to after they are created. Compare the snapshot
to the original dataset from which it was created:
#
zfs list -rt all
NAME USED AVAIL REFER MOUNTPOINT mypool/usr/home 184K 93.2G 184K /usr/home mypool/usr/home@my_recursive_snapshot 0 - 184K -mypool/usr/home
Displaying both the dataset and the snapshot together reveals how snapshots work in COW fashion. They save only the changes (delta) that were made and not the complete file system contents all over again. This means that snapshots take little space when few changes are made. Space usage can be made even more apparent by copying a file to the dataset, then making a second snapshot:
#
cp
/etc/passwd
/var/tmp
#
zfs snapshot
mypool/var/tmp
@after_cp
#
zfs list -rt all
NAME USED AVAIL REFER MOUNTPOINT mypool/var/tmp 206K 93.2G 118K /var/tmp mypool/var/tmp@my_recursive_snapshot 88K - 152K - mypool/var/tmp@after_cp 0 - 118K -mypool/var/tmp
The second snapshot contains only the changes to the
dataset after the copy operation. This yields enormous
space savings. Notice that the size of the snapshot
mypool/var/tmp@my_recursive_snapshot
also changed in the USED
column to indicate the changes between itself and the
snapshot taken afterwards.
ZFS provides a built-in command to compare the
differences in content between two snapshots. This is
helpful when many snapshots were taken over time and the
user wants to see how the file system has changed over time.
For example, zfs diff
lets a user find
the latest snapshot that still contains a file that was
accidentally deleted. Doing this for the two snapshots that
were created in the previous section yields this
output:
#
zfs list -rt all
NAME USED AVAIL REFER MOUNTPOINT mypool/var/tmp 206K 93.2G 118K /var/tmp mypool/var/tmp@my_recursive_snapshot 88K - 152K - mypool/var/tmp@after_cp 0 - 118K -mypool/var/tmp
#
zfs diff
M /var/tmp/ + /var/tmp/passwdmypool/var/tmp@my_recursive_snapshot
The command lists the changes between the specified
snapshot (in this case
)
and the live file system. The first column shows the
type of change:mypool/var/tmp@my_recursive_snapshot
+ | The path or file was added. |
- | The path or file was deleted. |
M | The path or file was modified. |
R | The path or file was renamed. |
Comparing the output with the table, it becomes clear
that
was added after the snapshot
passwd
was created. This also resulted in a modification to the
parent directory mounted at
mypool/var/tmp@my_recursive_snapshot
./var/tmp
Comparing two snapshots is helpful when using the ZFS replication feature to transfer a dataset to a different host for backup purposes.
Compare two snapshots by providing the full dataset name and snapshot name of both datasets:
#
cp /var/tmp/passwd /var/tmp/passwd.copy
#
zfs snapshot
mypool/var/tmp@diff_snapshot
#
zfs diff
M /var/tmp/ + /var/tmp/passwd + /var/tmp/passwd.copymypool/var/tmp@my_recursive_snapshot
mypool/var/tmp@diff_snapshot
#
zfs diff
M /var/tmp/ + /var/tmp/passwdmypool/var/tmp@my_recursive_snapshot
mypool/var/tmp@after_cp
A backup administrator can compare two snapshots received from the sending host and determine the actual changes in the dataset. See the Replication section for more information.
When at least one snapshot is available, it can be
rolled back to at any time. Most of the time this is the
case when the current state of the dataset is no longer
required and an older version is preferred. Scenarios such
as local development tests have gone wrong, botched system
updates hampering the system's overall functionality, or the
requirement to restore accidentally deleted files or
directories are all too common occurrences. Luckily,
rolling back a snapshot is just as easy as typing
zfs rollback
.
Depending on how many changes are involved, the operation
will finish in a certain amount of time. During that time,
the dataset always remains in a consistent state, much like
a database that conforms to ACID principles is performing a
rollback. This is happening while the dataset is live and
accessible without requiring a downtime. Once the snapshot
has been rolled back, the dataset has the same state as it
had when the snapshot was originally taken. All other data
in that dataset that was not part of the snapshot is
discarded. Taking a snapshot of the current state of the
dataset before rolling back to a previous one is a good idea
when some data is required later. This way, the user can
roll back and forth between snapshots without losing data
that is still valuable.snapshotname
In the first example, a snapshot is rolled back because
of a careless rm
operation that removes
too much data than was intended.
#
zfs list -rt all
NAME USED AVAIL REFER MOUNTPOINT mypool/var/tmp 262K 93.2G 120K /var/tmp mypool/var/tmp@my_recursive_snapshot 88K - 152K - mypool/var/tmp@after_cp 53.5K - 118K - mypool/var/tmp@diff_snapshot 0 - 120K -mypool/var/tmp
#
ls /var/tmp
passwd passwd.copy vi.recover#
rm /var/tmp/passwd*
#
ls /var/tmp
vi.recover
At this point, the user realized that too many files were deleted and wants them back. ZFS provides an easy way to get them back using rollbacks, but only when snapshots of important data are performed on a regular basis. To get the files back and start over from the last snapshot, issue the command:
#
zfs rollback
mypool/var/tmp@diff_snapshot
#
ls /var/tmp
passwd passwd.copy vi.recover
The rollback operation restored the dataset to the state of the last snapshot. It is also possible to roll back to a snapshot that was taken much earlier and has other snapshots that were created after it. When trying to do this, ZFS will issue this warning:
#
zfs list -rt snapshot
AME USED AVAIL REFER MOUNTPOINT mypool/var/tmp@my_recursive_snapshot 88K - 152K - mypool/var/tmp@after_cp 53.5K - 118K - mypool/var/tmp@diff_snapshot 0 - 120K -mypool/var/tmp
#
zfs rollback
cannot rollback to 'mypool/var/tmp@my_recursive_snapshot': more recent snapshots exist use '-r' to force deletion of the following snapshots: mypool/var/tmp@after_cp mypool/var/tmp@diff_snapshotmypool/var/tmp@my_recursive_snapshot
This warning means that snapshots exist between the
current state of the dataset and the snapshot to which the
user wants to roll back. To complete the rollback, these
snapshots must be deleted. ZFS cannot
track all the changes between different states of the
dataset, because snapshots are read-only.
ZFS will not delete the affected
snapshots unless the user specifies -r
to
indicate that this is the desired action. If that is the
intention, and the consequences of losing all intermediate
snapshots is understood, the command can be issued:
#
zfs rollback -r
mypool/var/tmp@my_recursive_snapshot
#
zfs list -rt snapshot
NAME USED AVAIL REFER MOUNTPOINT mypool/var/tmp@my_recursive_snapshot 8K - 152K -mypool/var/tmp
#
ls /var/tmp
vi.recover
The output from zfs list -t snapshot
confirms that the intermediate snapshots
were removed as a result of
zfs rollback -r
.
Snapshots are mounted in a hidden directory under the
parent dataset:
.zfs/snapshots/
.
By default, these directories will not be displayed even
when a standard snapshotname
ls -a
is issued.
Although the directory is not displayed, it is there
nevertheless and can be accessed like any normal directory.
The property named snapdir
controls
whether these hidden directories show up in a directory
listing. Setting the property to visible
allows them to appear in the output of ls
and other commands that deal with directory contents.
#
zfs get snapdir
NAME PROPERTY VALUE SOURCE mypool/var/tmp snapdir hidden defaultmypool/var/tmp
#
ls -a /var/tmp
. .. passwd vi.recover#
zfs set snapdir=visible
mypool/var/tmp
#
ls -a /var/tmp
. .. .zfs passwd vi.recover
Individual files can easily be restored to a previous
state by copying them from the snapshot back to the parent
dataset. The directory structure below
.zfs/snapshot
has a directory named
exactly like the snapshots taken earlier to make it easier
to identify them. In the next example, it is assumed that a
file is to be restored from the hidden
.zfs
directory by copying it from the
snapshot that contained the latest version of the
file:
#
rm /var/tmp/passwd
#
ls -a /var/tmp
. .. .zfs vi.recover#
ls /var/tmp/.zfs/snapshot
after_cp my_recursive_snapshot#
ls /var/tmp/.zfs/snapshot/
passwd vi.recoverafter_cp
#
cp /var/tmp/.zfs/snapshot/
after_cp/passwd
/var/tmp
When ls .zfs/snapshot
was issued, the
snapdir
property might have been set to
hidden, but it would still be possible to list the contents
of that directory. It is up to the administrator to decide
whether these directories will be displayed. It is possible
to display these for certain datasets and prevent it for
others. Copying files or directories from this hidden
.zfs/snapshot
is simple enough. Trying
it the other way around results in this error:
#
cp
cp: /var/tmp/.zfs/snapshot/after_cp/rc.conf: Read-only file system/etc/rc.conf
/var/tmp/.zfs/snapshot/after_cp/
The error reminds the user that snapshots are read-only and cannot be changed after creation. Files cannot be copied into or removed from snapshot directories because that would change the state of the dataset they represent.
Snapshots consume space based on how much the parent
file system has changed since the time of the snapshot. The
written
property of a snapshot tracks how
much space is being used by the snapshot.
Snapshots are destroyed and the space reclaimed with
zfs destroy
.
Adding dataset
@snapshot
-r
recursively removes all snapshots
with the same name under the parent dataset. Adding
-n -v
to the command displays a list of the
snapshots that would be deleted and an estimate of how much
space would be reclaimed without performing the actual
destroy operation.
A clone is a copy of a snapshot that is treated more like
a regular dataset. Unlike a snapshot, a clone is not read
only, is mounted, and can have its own properties. Once a
clone has been created using zfs clone
, the
snapshot it was created from cannot be destroyed. The
child/parent relationship between the clone and the snapshot
can be reversed using zfs promote
. After a
clone has been promoted, the snapshot becomes a child of the
clone, rather than of the original parent dataset. This will
change how the space is accounted, but not actually change the
amount of space consumed. The clone can be mounted at any
point within the ZFS file system hierarchy,
not just below the original location of the snapshot.
To demonstrate the clone feature, this example dataset is used:
#
zfs list -rt all
NAME USED AVAIL REFER MOUNTPOINT camino/home/joe 108K 1.3G 87K /usr/home/joe camino/home/joe@plans 21K - 85.5K - camino/home/joe@backup 0K - 87K -camino/home/joe
A typical use for clones is to experiment with a specific dataset while keeping the snapshot around to fall back to in case something goes wrong. Since snapshots cannot be changed, a read/write clone of a snapshot is created. After the desired result is achieved in the clone, the clone can be promoted to a dataset and the old file system removed. This is not strictly necessary, as the clone and dataset can coexist without problems.
#
zfs clone
camino/home/joe
@backup
camino/home/joenew
#
ls /usr/home/joe*
/usr/home/joe: backup.txz plans.txt /usr/home/joenew: backup.txz plans.txt#
df -h /usr/home
Filesystem Size Used Avail Capacity Mounted on usr/home/joe 1.3G 31k 1.3G 0% /usr/home/joe usr/home/joenew 1.3G 31k 1.3G 0% /usr/home/joenew
After a clone is created it is an exact copy of the state
the dataset was in when the snapshot was taken. The clone can
now be changed independently from its originating dataset.
The only connection between the two is the snapshot.
ZFS records this connection in the property
origin
. Once the dependency between the
snapshot and the clone has been removed by promoting the clone
using zfs promote
, the
origin
of the clone is removed as it is now
an independent dataset. This example demonstrates it:
#
zfs get origin
NAME PROPERTY VALUE SOURCE camino/home/joenew origin camino/home/joe@backup -camino/home/joenew
#
zfs promote
camino/home/joenew
#
zfs get origin
NAME PROPERTY VALUE SOURCE camino/home/joenew origin - -camino/home/joenew
After making some changes like copying
loader.conf
to the promoted clone, for
example, the old directory becomes obsolete in this case.
Instead, the promoted clone can replace it. This can be
achieved by two consecutive commands: zfs
destroy
on the old dataset and zfs
rename
on the clone to name it like the old
dataset (it could also get an entirely different name).
#
cp
/boot/defaults/loader.conf
/usr/home/joenew
#
zfs destroy -f
camino/home/joe
#
zfs rename
camino/home/joenew
camino/home/joe
#
ls /usr/home/joe
backup.txz loader.conf plans.txt#
df -h
Filesystem Size Used Avail Capacity Mounted on usr/home/joe 1.3G 128k 1.3G 0% /usr/home/joe/usr/home
The cloned snapshot is now handled like an ordinary
dataset. It contains all the data from the original snapshot
plus the files that were added to it like
loader.conf
. Clones can be used in
different scenarios to provide useful features to ZFS users.
For example, jails could be provided as snapshots containing
different sets of installed applications. Users can clone
these snapshots and add their own applications as they see
fit. Once they are satisfied with the changes, the clones can
be promoted to full datasets and provided to end users to work
with like they would with a real dataset. This saves time and
administrative overhead when providing these jails.
Keeping data on a single pool in one location exposes
it to risks like theft and natural or human disasters. Making
regular backups of the entire pool is vital.
ZFS provides a built-in serialization
feature that can send a stream representation of the data to
standard output. Using this technique, it is possible to not
only store the data on another pool connected to the local
system, but also to send it over a network to another system.
Snapshots are the basis for this replication (see the section
on ZFS
snapshots). The commands used for replicating data
are zfs send
and
zfs receive
.
These examples demonstrate ZFS replication with these two pools:
#
zpool list
NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT backup 960M 77K 896M - - 0% 0% 1.00x ONLINE - mypool 984M 43.7M 940M - - 0% 4% 1.00x ONLINE -
The pool named mypool
is the
primary pool where data is written to and read from on a
regular basis. A second pool,
backup
is used as a standby in case
the primary pool becomes unavailable. Note that this
fail-over is not done automatically by ZFS,
but must be manually done by a system administrator when
needed. A snapshot is used to provide a consistent version of
the file system to be replicated. Once a snapshot of
mypool
has been created, it can be
copied to the backup
pool. Only
snapshots can be replicated. Changes made since the most
recent snapshot will not be included.
#
zfs snapshot
mypool
@backup1
#
zfs list -t snapshot
NAME USED AVAIL REFER MOUNTPOINT mypool@backup1 0 - 43.6M -
Now that a snapshot exists, zfs send
can be used to create a stream representing the contents of
the snapshot. This stream can be stored as a file or received
by another pool. The stream is written to standard output,
but must be redirected to a file or pipe or an error is
produced:
#
zfs send
Error: Stream can not be written to a terminal. You must redirect standard output.mypool
@backup1
To back up a dataset with zfs send
,
redirect to a file located on the mounted backup pool. Ensure
that the pool has enough free space to accommodate the size of
the snapshot being sent, which means all of the data contained
in the snapshot, not just the changes from the previous
snapshot.
#
zfs send
mypool
@backup1
>/backup/backup1
#
zpool list
NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT backup 960M 63.7M 896M - - 0% 6% 1.00x ONLINE - mypool 984M 43.7M 940M - - 0% 4% 1.00x ONLINE -
The zfs send
transferred all the data
in the snapshot called backup1
to
the pool named backup
. Creating
and sending these snapshots can be done automatically with a
cron(8) job.
Instead of storing the backups as archive files,
ZFS can receive them as a live file system,
allowing the backed up data to be accessed directly. To get
to the actual data contained in those streams,
zfs receive
is used to transform the
streams back into files and directories. The example below
combines zfs send
and
zfs receive
using a pipe to copy the data
from one pool to another. The data can be used directly on
the receiving pool after the transfer is complete. A dataset
can only be replicated to an empty dataset.
#
zfs snapshot
mypool
@replica1
#
zfs send -v
send from @ to mypool@replica1 estimated size is 50.1M total estimated size is 50.1M TIME SENT SNAPSHOTmypool
@replica1
| zfs receivebackup/mypool
#
zpool list
NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT backup 960M 63.7M 896M - - 0% 6% 1.00x ONLINE - mypool 984M 43.7M 940M - - 0% 4% 1.00x ONLINE -
zfs send
can also determine the
difference between two snapshots and send only the
differences between the two. This saves disk space and
transfer time. For example:
#
zfs snapshot
mypool
@replica2
#
zfs list -t snapshot
NAME USED AVAIL REFER MOUNTPOINT mypool@replica1 5.72M - 43.6M - mypool@replica2 0 - 44.1M -#
zpool list
NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT backup 960M 61.7M 898M - - 0% 6% 1.00x ONLINE - mypool 960M 50.2M 910M - - 0% 5% 1.00x ONLINE -
A second snapshot called
replica2
was created. This
second snapshot contains only the changes that were made to
the file system between now and the previous snapshot,
replica1
. Using
zfs send -i
and indicating the pair of
snapshots generates an incremental replica stream containing
only the data that has changed. This can only succeed if
the initial snapshot already exists on the receiving
side.
#
zfs send -v -i
send from @replica1 to mypool@replica2 estimated size is 5.02M total estimated size is 5.02M TIME SENT SNAPSHOTmypool
@replica1
mypool
@replica2
| zfs receive/backup/mypool
#
zpool list
NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT backup 960M 80.8M 879M - - 0% 8% 1.00x ONLINE - mypool 960M 50.2M 910M - - 0% 5% 1.00x ONLINE -#
zfs list
NAME USED AVAIL REFER MOUNTPOINT backup 55.4M 240G 152K /backup backup/mypool 55.3M 240G 55.2M /backup/mypool mypool 55.6M 11.6G 55.0M /mypool#
zfs list -t snapshot
NAME USED AVAIL REFER MOUNTPOINT backup/mypool@replica1 104K - 50.2M - backup/mypool@replica2 0 - 55.2M - mypool@replica1 29.9K - 50.0M - mypool@replica2 0 - 55.0M -
The incremental stream was successfully transferred.
Only the data that had changed was replicated, rather than
the entirety of replica1
. Only
the differences were sent, which took much less time to
transfer and saved disk space by not copying the complete
pool each time. This is useful when having to rely on slow
networks or when costs per transferred byte must be
considered.
A new file system,
backup/mypool
, is available with
all of the files and data from the pool
mypool
. If -P
is specified, the properties of the dataset will be copied,
including compression settings, quotas, and mount points.
When -R
is specified, all child datasets of
the indicated dataset will be copied, along with all of
their properties. Sending and receiving can be automated so
that regular backups are created on the second pool.
Sending streams over the network is a good way to keep a remote backup, but it does come with a drawback. Data sent over the network link is not encrypted, allowing anyone to intercept and transform the streams back into data without the knowledge of the sending user. This is undesirable, especially when sending the streams over the internet to a remote host. SSH can be used to securely encrypt data send over a network connection. Since ZFS only requires the stream to be redirected from standard output, it is relatively easy to pipe it through SSH. To keep the contents of the file system encrypted in transit and on the remote system, consider using PEFS.
A few settings and security precautions must be
completed first. Only the necessary steps required for the
zfs send
operation are shown here. For
more information on SSH, see
Section 13.8, “OpenSSH”.
This configuration is required:
Passwordless SSH access between sending and receiving host using SSH keys
Normally, the privileges of the
root
user are
needed to send and receive streams. This requires
logging in to the receiving system as
root
.
However, logging in as
root
is
disabled by default for security reasons. The
ZFS Delegation
system can be used to allow a
non-root
user
on each system to perform the respective send and
receive operations.
On the sending system:
#
zfs allow -u someuser send,snapshot
mypool
To mount the pool, the unprivileged user must own the directory, and regular users must be allowed to mount file systems. On the receiving system:
#
sysctl vfs.usermount=1
vfs.usermount: 0 -> 1#
sysrc -f /etc/sysctl.conf vfs.usermount=1
#
zfs create
recvpool/backup
#
zfs allow -u
someuser
create,mount,receiverecvpool/backup
#
chown
someuser
/recvpool/backup
The unprivileged user now has the ability to receive and
mount datasets, and the home
dataset can be replicated to the remote system:
%
zfs snapshot -r
mypool/home
@monday
%
zfs send -R
mypool/home
@monday
| sshsomeuser@backuphost
zfs recv -dvurecvpool/backup
A recursive snapshot called
monday
is made of the file system
dataset home
that resides on the
pool mypool
. Then it is sent
with zfs send -R
to include the dataset,
all child datasets, snapshots, clones, and settings in the
stream. The output is piped to the waiting
zfs receive
on the remote host
backuphost
through
SSH. Using a fully qualified
domain name or IP address is recommended. The receiving
machine writes the data to the
backup
dataset on the
recvpool
pool. Adding
-d
to zfs recv
overwrites the name of the pool on the receiving side with
the name of the snapshot. -u
causes the
file systems to not be mounted on the receiving side. When
-v
is included, more detail about the
transfer is shown, including elapsed time and the amount of
data transferred.
Dataset quotas are used to restrict the amount of space that can be consumed by a particular dataset. Reference Quotas work in very much the same way, but only count the space used by the dataset itself, excluding snapshots and child datasets. Similarly, user and group quotas can be used to prevent users or groups from using all of the space in the pool or dataset.
To enforce a dataset quota of 10 GB for
storage/home/bob
:
#
zfs set quota=10G storage/home/bob
To enforce a reference quota of 10 GB for
storage/home/bob
:
#
zfs set refquota=10G storage/home/bob
To remove a quota of 10 GB for
storage/home/bob
:
#
zfs set quota=none storage/home/bob
The general format is
userquota@
,
and the user's name must be in one of these formats:user
=size
POSIX compatible name such as
joe
.
POSIX numeric ID such as
789
.
SID name
such as
joe.bloggs@example.com
.
SID
numeric ID such as
S-1-123-456-789
.
For example, to enforce a user quota of 50 GB for the
user named joe
:
#
zfs set userquota@joe=50G
To remove any quota:
#
zfs set userquota@joe=none
User quota properties are not displayed by
zfs get all
.
Non-root
users can
only see their own quotas unless they have been granted the
userquota
privilege. Users with this
privilege are able to view and set everyone's quota.
The general format for setting a group quota is:
groupquota@
.group
=size
To set the quota for the group
firstgroup
to 50 GB,
use:
#
zfs set groupquota@firstgroup=50G
To remove the quota for the group
firstgroup
, or to make sure that
one is not set, instead use:
#
zfs set groupquota@firstgroup=none
As with the user quota property,
non-root
users can
only see the quotas associated with the groups to which they
belong. However,
root
or a user with
the groupquota
privilege can view and set
all quotas for all groups.
To display the amount of space used by each user on
a file system or snapshot along with any quotas, use
zfs userspace
. For group information, use
zfs groupspace
. For more information about
supported options or how to display only specific options,
refer to zfs(1).
Users with sufficient privileges, and
root
, can list the
quota for storage/home/bob
using:
#
zfs get quota storage/home/bob
Reservations guarantee a minimum amount of space will always be available on a dataset. The reserved space will not be available to any other dataset. This feature can be especially useful to ensure that free space is available for an important dataset or log files.
The general format of the reservation
property is
reservation=
,
so to set a reservation of 10 GB on
size
storage/home/bob
, use:
#
zfs set reservation=10G storage/home/bob
To clear any reservation:
#
zfs set reservation=none storage/home/bob
The same principle can be applied to the
refreservation
property for setting a
Reference
Reservation, with the general format
refreservation=
.size
This command shows any reservations or refreservations
that exist on storage/home/bob
:
#
zfs get reservation storage/home/bob
#
zfs get refreservation storage/home/bob
ZFS provides transparent compression. Compressing data at the block level as it is written not only saves space, but can also increase disk throughput. If data is compressed by 25%, but the compressed data is written to the disk at the same rate as the uncompressed version, resulting in an effective write speed of 125%. Compression can also be a great alternative to Deduplication because it does not require additional memory.
ZFS offers several different compression algorithms, each with different trade-offs. With the introduction of LZ4 compression in ZFS v5000, it is possible to enable compression for the entire pool without the large performance trade-off of other algorithms. The biggest advantage to LZ4 is the early abort feature. If LZ4 does not achieve at least 12.5% compression in the first part of the data, the block is written uncompressed to avoid wasting CPU cycles trying to compress data that is either already compressed or uncompressible. For details about the different compression algorithms available in ZFS, see the Compression entry in the terminology section.
The administrator can monitor the effectiveness of compression using a number of dataset properties.
#
zfs get used,compressratio,compression,logicalused
NAME PROPERTY VALUE SOURCE mypool/compressed_dataset used 449G - mypool/compressed_dataset compressratio 1.11x - mypool/compressed_dataset compression lz4 local mypool/compressed_dataset logicalused 496G -mypool/compressed_dataset
The dataset is currently using 449 GB of space (the
used property). Without compression, it would have taken
496 GB of space (the logicalused
property). This results in the 1.11:1 compression
ratio.
Compression can have an unexpected side effect when
combined with
User Quotas.
User quotas restrict how much space a user can consume on a
dataset, but the measurements are based on how much space is
used after compression. So if a user has
a quota of 10 GB, and writes 10 GB of compressible
data, they will still be able to store additional data. If
they later update a file, say a database, with more or less
compressible data, the amount of space available to them will
change. This can result in the odd situation where a user did
not increase the actual amount of data (the
logicalused
property), but the change in
compression caused them to reach their quota limit.
Compression can have a similar unexpected interaction with backups. Quotas are often used to limit how much data can be stored to ensure there is sufficient backup space available. However since quotas do not consider compression, more data may be written than would fit with uncompressed backups.
When enabled, deduplication uses the checksum of each block to detect duplicate blocks. When a new block is a duplicate of an existing block, ZFS writes an additional reference to the existing data instead of the whole duplicate block. Tremendous space savings are possible if the data contains many duplicated files or repeated information. Be warned: deduplication requires an extremely large amount of memory, and most of the space savings can be had without the extra cost by enabling compression instead.
To activate deduplication, set the
dedup
property on the target pool:
#
zfs set dedup=on
pool
Only new data being written to the pool will be deduplicated. Data that has already been written to the pool will not be deduplicated merely by activating this option. A pool with a freshly activated deduplication property will look like this example:
#
zpool list
NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT pool 2.84G 2.19M 2.83G - - 0% 0% 1.00x ONLINE -
The DEDUP
column shows the actual rate
of deduplication for the pool. A value of
1.00x
shows that data has not been
deduplicated yet. In the next example, the ports tree is
copied three times into different directories on the
deduplicated pool created above.
#
for d in dir1 dir2 dir3; do
>mkdir $d && cp -R /usr/ports $d &
>done
Redundant data is detected and deduplicated:
#
zpool list
NAME SIZE ALLOC FREE CKPOINT EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT pool 2.84G 20.9M 2.82G - - 0% 0% 3.00x ONLINE -
The DEDUP
column shows a factor of
3.00x
. Multiple copies of the ports tree
data was detected and deduplicated, using only a third of the
space. The potential for space savings can be enormous, but
comes at the cost of having enough memory to keep track of the
deduplicated blocks.
Deduplication is not always beneficial, especially when the data on a pool is not redundant. ZFS can show potential space savings by simulating deduplication on an existing pool:
#
zdb -S
Simulated DDT histogram: bucket allocated referenced ______ ______________________________ ______________________________ refcnt blocks LSIZE PSIZE DSIZE blocks LSIZE PSIZE DSIZE ------ ------ ----- ----- ----- ------ ----- ----- ----- 1 2.58M 289G 264G 264G 2.58M 289G 264G 264G 2 206K 12.6G 10.4G 10.4G 430K 26.4G 21.6G 21.6G 4 37.6K 692M 276M 276M 170K 3.04G 1.26G 1.26G 8 2.18K 45.2M 19.4M 19.4M 20.0K 425M 176M 176M 16 174 2.83M 1.20M 1.20M 3.33K 48.4M 20.4M 20.4M 32 40 2.17M 222K 222K 1.70K 97.2M 9.91M 9.91M 64 9 56K 10.5K 10.5K 865 4.96M 948K 948K 128 2 9.50K 2K 2K 419 2.11M 438K 438K 256 5 61.5K 12K 12K 1.90K 23.0M 4.47M 4.47M 1K 2 1K 1K 1K 2.98K 1.49M 1.49M 1.49M Total 2.82M 303G 275G 275G 3.20M 319G 287G 287G dedup = 1.05, compress = 1.11, copies = 1.00, dedup * compress / copies = 1.16pool
After zdb -S
finishes analyzing the
pool, it shows the space reduction ratio that would be
achieved by activating deduplication. In this case,
1.16
is a very poor space saving ratio that
is mostly provided by compression. Activating deduplication
on this pool would not save any significant amount of space,
and is not worth the amount of memory required to enable
deduplication. Using the formula
ratio = dedup * compress / copies,
system administrators can plan the storage allocation,
deciding whether the workload will contain enough duplicate
blocks to justify the memory requirements. If the data is
reasonably compressible, the space savings may be very good.
Enabling compression first is recommended, and compression can
also provide greatly increased performance. Only enable
deduplication in cases where the additional savings will be
considerable and there is sufficient memory for the DDT.
zfs jail
and the corresponding
jailed
property are used to delegate a
ZFS dataset to a
Jail.
zfs jail
attaches a dataset to the specified jail, and
jailid
zfs unjail
detaches it. For the dataset to
be controlled from within a jail, the
jailed
property must be set. Once a
dataset is jailed, it can no longer be mounted on the
host because it may have mount points that would compromise
the security of the host.
A comprehensive permission delegation system allows unprivileged users to perform ZFS administration functions. For example, if each user's home directory is a dataset, users can be given permission to create and destroy snapshots of their home directories. A backup user can be given permission to use replication features. A usage statistics script can be allowed to run with access only to the space utilization data for all users. It is even possible to delegate the ability to delegate permissions. Permission delegation is possible for each subcommand and most properties.
zfs allow
gives the
specified user permission to create child datasets under the
selected parent dataset. There is a caveat: creating a new
dataset involves mounting it. That requires setting the
FreeBSD someuser
create
mydataset
vfs.usermount
sysctl(8) to
1
to allow non-root users to mount a
file system. There is another restriction aimed at preventing
abuse: non-root
users must own the mountpoint where the file system is to be
mounted.
zfs allow
gives the
specified user the ability to assign any permission they have
on the target dataset, or its children, to other users. If a
user has the someuser
allow
mydataset
snapshot
permission and the
allow
permission, that user can then grant
the snapshot
permission to other
users.
There are a number of tunables that can be adjusted to make ZFS perform best for different workloads.
vfs.zfs.arc_max
- Maximum size of the ARC.
The default is all RAM but 1 GB,
or 5/8 of all RAM, whichever is more.
However, a lower value should be used if the system will
be running any other daemons or processes that may require
memory. This value can be adjusted at runtime with
sysctl(8) and can be set in
/boot/loader.conf
or
/etc/sysctl.conf
.
vfs.zfs.arc_meta_limit
- Limit the portion of the
ARC
that can be used to store metadata. The default is one
fourth of vfs.zfs.arc_max
. Increasing
this value will improve performance if the workload
involves operations on a large number of files and
directories, or frequent metadata operations, at the cost
of less file data fitting in the ARC.
This value can be adjusted at runtime with sysctl(8)
and can be set in
/boot/loader.conf
or
/etc/sysctl.conf
.
vfs.zfs.arc_min
- Minimum size of the ARC.
The default is one half of
vfs.zfs.arc_meta_limit
. Adjust this
value to prevent other applications from pressuring out
the entire ARC.
This value can be adjusted at runtime with sysctl(8)
and can be set in
/boot/loader.conf
or
/etc/sysctl.conf
.
vfs.zfs.vdev.cache.size
- A preallocated amount of memory reserved as a cache for
each device in the pool. The total amount of memory used
will be this value multiplied by the number of devices.
This value can only be adjusted at boot time, and is set
in /boot/loader.conf
.
vfs.zfs.min_auto_ashift
- Minimum ashift
(sector size) that
will be used automatically at pool creation time. The
value is a power of two. The default value of
9
represents
2^9 = 512
, a sector size of 512 bytes.
To avoid write amplification and get
the best performance, set this value to the largest sector
size used by a device in the pool.
Many drives have 4 KB sectors. Using the default
ashift
of 9
with
these drives results in write amplification on these
devices. Data that could be contained in a single
4 KB write must instead be written in eight 512-byte
writes. ZFS tries to read the native
sector size from all devices when creating a pool, but
many drives with 4 KB sectors report that their
sectors are 512 bytes for compatibility. Setting
vfs.zfs.min_auto_ashift
to
12
(2^12 = 4096
)
before creating a pool forces ZFS to
use 4 KB blocks for best performance on these
drives.
Forcing 4 KB blocks is also useful on pools where
disk upgrades are planned. Future disks are likely to use
4 KB sectors, and ashift
values
cannot be changed after a pool is created.
In some specific cases, the smaller 512-byte block size might be preferable. When used with 512-byte disks for databases, or as storage for virtual machines, less data is transferred during small random reads. This can provide better performance, especially when using a smaller ZFS record size.
vfs.zfs.prefetch_disable
- Disable prefetch. A value of 0
is
enabled and 1
is disabled. The default
is 0
, unless the system has less than
4 GB of RAM. Prefetch works by
reading larger blocks than were requested into the
ARC
in hopes that the data will be needed soon. If the
workload has a large number of random reads, disabling
prefetch may actually improve performance by reducing
unnecessary reads. This value can be adjusted at any time
with sysctl(8).
vfs.zfs.vdev.trim_on_init
- Control whether new devices added to the pool have the
TRIM
command run on them. This ensures
the best performance and longevity for
SSDs, but takes extra time. If the
device has already been secure erased, disabling this
setting will make the addition of the new device faster.
This value can be adjusted at any time with
sysctl(8).
vfs.zfs.vdev.max_pending
- Limit the number of pending I/O requests per device.
A higher value will keep the device command queue full
and may give higher throughput. A lower value will reduce
latency. This value can be adjusted at any time with
sysctl(8).
vfs.zfs.top_maxinflight
- Maxmimum number of outstanding I/Os per top-level
vdev. Limits the
depth of the command queue to prevent high latency. The
limit is per top-level vdev, meaning the limit applies to
each mirror,
RAID-Z, or
other vdev independently. This value can be adjusted at
any time with sysctl(8).
vfs.zfs.l2arc_write_max
- Limit the amount of data written to the L2ARC
per second. This tunable is designed to extend the
longevity of SSDs by limiting the
amount of data written to the device. This value can be
adjusted at any time with sysctl(8).
vfs.zfs.l2arc_write_boost
- The value of this tunable is added to vfs.zfs.l2arc_write_max
and increases the write speed to the
SSD until the first block is evicted
from the L2ARC.
This “Turbo Warmup Phase” is designed to
reduce the performance loss from an empty L2ARC
after a reboot. This value can be adjusted at any time
with sysctl(8).
vfs.zfs.scrub_delay
- Number of ticks to delay between each I/O during a
scrub
.
To ensure that a scrub
does not
interfere with the normal operation of the pool, if any
other I/O is happening the
scrub
will delay between each command.
This value controls the limit on the total
IOPS (I/Os Per Second) generated by the
scrub
. The granularity of the setting
is determined by the value of kern.hz
which defaults to 1000 ticks per second. This setting may
be changed, resulting in a different effective
IOPS limit. The default value is
4
, resulting in a limit of:
1000 ticks/sec / 4 =
250 IOPS. Using a value of
20
would give a limit of:
1000 ticks/sec / 20 =
50 IOPS. The speed of
scrub
is only limited when there has
been recent activity on the pool, as determined by vfs.zfs.scan_idle
.
This value can be adjusted at any time with
sysctl(8).
vfs.zfs.resilver_delay
- Number of milliseconds of delay inserted between
each I/O during a
resilver. To
ensure that a resilver does not interfere with the normal
operation of the pool, if any other I/O is happening the
resilver will delay between each command. This value
controls the limit of total IOPS (I/Os
Per Second) generated by the resilver. The granularity of
the setting is determined by the value of
kern.hz
which defaults to 1000 ticks
per second. This setting may be changed, resulting in a
different effective IOPS limit. The
default value is 2, resulting in a limit of:
1000 ticks/sec / 2 =
500 IOPS. Returning the pool to
an Online state may
be more important if another device failing could
Fault the pool,
causing data loss. A value of 0 will give the resilver
operation the same priority as other operations, speeding
the healing process. The speed of resilver is only
limited when there has been other recent activity on the
pool, as determined by vfs.zfs.scan_idle
.
This value can be adjusted at any time with
sysctl(8).
vfs.zfs.scan_idle
- Number of milliseconds since the last operation before
the pool is considered idle. When the pool is idle the
rate limiting for scrub
and
resilver are
disabled. This value can be adjusted at any time with
sysctl(8).
vfs.zfs.txg.timeout
- Maximum number of seconds between
transaction groups.
The current transaction group will be written to the pool
and a fresh transaction group started if this amount of
time has elapsed since the previous transaction group. A
transaction group my be triggered earlier if enough data
is written. The default value is 5 seconds. A larger
value may improve read performance by delaying
asynchronous writes, but this may cause uneven performance
when the transaction group is written. This value can be
adjusted at any time with sysctl(8).
Some of the features provided by ZFS are memory intensive, and may require tuning for maximum efficiency on systems with limited RAM.
As a bare minimum, the total system memory should be at least one gigabyte. The amount of recommended RAM depends upon the size of the pool and which ZFS features are used. A general rule of thumb is 1 GB of RAM for every 1 TB of storage. If the deduplication feature is used, a general rule of thumb is 5 GB of RAM per TB of storage to be deduplicated. While some users successfully use ZFS with less RAM, systems under heavy load may panic due to memory exhaustion. Further tuning may be required for systems with less than the recommended RAM requirements.
Due to the address space limitations of the i386™ platform, ZFS users on the i386™ architecture must add this option to a custom kernel configuration file, rebuild the kernel, and reboot:
options KVA_PAGES=512
This expands the kernel address space, allowing
the vm.kvm_size
tunable to be pushed
beyond the currently imposed limit of 1 GB, or the
limit of 2 GB for PAE. To find the
most suitable value for this option, divide the desired
address space in megabytes by four. In this example, it
is 512
for 2 GB.
The kmem
address space can be
increased on all FreeBSD architectures. On a test system with
1 GB of physical memory, success was achieved with
these options added to
/boot/loader.conf
, and the system
restarted:
vm.kmem_size="330M" vm.kmem_size_max="330M" vfs.zfs.arc_max="40M" vfs.zfs.vdev.cache.size="5M"
For a more detailed list of recommendations for ZFS-related tuning, see https://wiki.freebsd.org/ZFSTuningGuide.
ZFS is a fundamentally different file system because it is more than just a file system. ZFS combines the roles of file system and volume manager, enabling additional storage devices to be added to a live system and having the new space available on all of the existing file systems in that pool immediately. By combining the traditionally separate roles, ZFS is able to overcome previous limitations that prevented RAID groups being able to grow. Each top level device in a pool is called a vdev, which can be a simple disk or a RAID transformation such as a mirror or RAID-Z array. ZFS file systems (called datasets) each have access to the combined free space of the entire pool. As blocks are allocated from the pool, the space available to each file system decreases. This approach avoids the common pitfall with extensive partitioning where free space becomes fragmented across the partitions.
pool | A storage pool is the most basic building block of ZFS. A pool is made up of one or more vdevs, the underlying devices that store the data. A pool is then used to create one or more file systems (datasets) or block devices (volumes). These datasets and volumes share the pool of remaining free space. Each pool is uniquely identified by a name and a GUID. The features available are determined by the ZFS version number on the pool. |
vdev Types | A pool is made up of one or more vdevs, which
themselves can be a single disk or a group of disks, in
the case of a RAID transform. When
multiple vdevs are used, ZFS spreads
data across the vdevs to increase performance and
maximize usable space.
|
Transaction Group (TXG) | Transaction Groups are the way changed blocks are
grouped together and eventually written to the pool.
Transaction groups are the atomic unit that
ZFS uses to assert consistency. Each
transaction group is assigned a unique 64-bit
consecutive identifier. There can be up to three active
transaction groups at a time, one in each of these three
states:
snapshot
are written as part of the transaction group. When a
synctask is created, it is added to the currently open
transaction group, and that group is advanced as quickly
as possible to the syncing state to reduce the
latency of administrative commands. |
Adaptive Replacement Cache (ARC) | ZFS uses an Adaptive Replacement Cache (ARC), rather than a more traditional Least Recently Used (LRU) cache. An LRU cache is a simple list of items in the cache, sorted by when each object was most recently used. New items are added to the top of the list. When the cache is full, items from the bottom of the list are evicted to make room for more active objects. An ARC consists of four lists; the Most Recently Used (MRU) and Most Frequently Used (MFU) objects, plus a ghost list for each. These ghost lists track recently evicted objects to prevent them from being added back to the cache. This increases the cache hit ratio by avoiding objects that have a history of only being used occasionally. Another advantage of using both an MRU and MFU is that scanning an entire file system would normally evict all data from an MRU or LRU cache in favor of this freshly accessed content. With ZFS, there is also an MFU that only tracks the most frequently used objects, and the cache of the most commonly accessed blocks remains. |
L2ARC | L2ARC is the second level
of the ZFS caching system. The
primary ARC is stored in
RAM. Since the amount of
available RAM is often limited,
ZFS can also use
cache vdevs.
Solid State Disks (SSDs) are often
used as these cache devices due to their higher speed
and lower latency compared to traditional spinning
disks. L2ARC is entirely optional,
but having one will significantly increase read speeds
for files that are cached on the SSD
instead of having to be read from the regular disks.
L2ARC can also speed up deduplication
because a DDT that does not fit in
RAM but does fit in the
L2ARC will be much faster than a
DDT that must be read from disk. The
rate at which data is added to the cache devices is
limited to prevent prematurely wearing out
SSDs with too many writes. Until the
cache is full (the first block has been evicted to make
room), writing to the L2ARC is
limited to the sum of the write limit and the boost
limit, and afterwards limited to the write limit. A
pair of sysctl(8) values control these rate limits.
vfs.zfs.l2arc_write_max
controls how many bytes are written to the cache per
second, while vfs.zfs.l2arc_write_boost
adds to this limit during the
“Turbo Warmup Phase” (Write Boost). |
ZIL | ZIL accelerates synchronous transactions by using storage devices like SSDs that are faster than those used in the main storage pool. When an application requests a synchronous write (a guarantee that the data has been safely stored to disk rather than merely cached to be written later), the data is written to the faster ZIL storage, then later flushed out to the regular disks. This greatly reduces latency and improves performance. Only synchronous workloads like databases will benefit from a ZIL. Regular asynchronous writes such as copying files will not use the ZIL at all. |
Copy-On-Write | Unlike a traditional file system, when data is overwritten on ZFS, the new data is written to a different block rather than overwriting the old data in place. Only when this write is complete is the metadata then updated to point to the new location. In the event of a shorn write (a system crash or power loss in the middle of writing a file), the entire original contents of the file are still available and the incomplete write is discarded. This also means that ZFS does not require a fsck(8) after an unexpected shutdown. |
Dataset | Dataset is the generic term
for a ZFS file system, volume,
snapshot or clone. Each dataset has a unique name in
the format
poolname/path@snapshot .
The root of the pool is technically a dataset as well.
Child datasets are named hierarchically like
directories. For example,
mypool/home , the home
dataset, is a child of mypool
and inherits properties from it. This can be expanded
further by creating
mypool/home/user . This
grandchild dataset will inherit properties from the
parent and grandparent. Properties on a child can be
set to override the defaults inherited from the parents
and grandparents. Administration of datasets and their
children can be
delegated. |
File system | A ZFS dataset is most often used as a file system. Like most other file systems, a ZFS file system is mounted somewhere in the systems directory hierarchy and contains files and directories of its own with permissions, flags, and other metadata. |
Volume | In additional to regular file system datasets, ZFS can also create volumes, which are block devices. Volumes have many of the same features, including copy-on-write, snapshots, clones, and checksumming. Volumes can be useful for running other file system formats on top of ZFS, such as UFS virtualization, or exporting iSCSI extents. |
Snapshot | The
copy-on-write
(COW) design of
ZFS allows for nearly instantaneous,
consistent snapshots with arbitrary names. After taking
a snapshot of a dataset, or a recursive snapshot of a
parent dataset that will include all child datasets, new
data is written to new blocks, but the old blocks are
not reclaimed as free space. The snapshot contains
the original version of the file system, and the live
file system contains any changes made since the snapshot
was taken. No additional space is used. As new data is
written to the live file system, new blocks are
allocated to store this data. The apparent size of the
snapshot will grow as the blocks are no longer used in
the live file system, but only in the snapshot. These
snapshots can be mounted read only to allow for the
recovery of previous versions of files. It is also
possible to
rollback a live
file system to a specific snapshot, undoing any changes
that took place after the snapshot was taken. Each
block in the pool has a reference counter which keeps
track of how many snapshots, clones, datasets, or
volumes make use of that block. As files and snapshots
are deleted, the reference count is decremented. When a
block is no longer referenced, it is reclaimed as free
space. Snapshots can also be marked with a
hold. When a
snapshot is held, any attempt to destroy it will return
an EBUSY error. Each snapshot can
have multiple holds, each with a unique name. The
release command
removes the hold so the snapshot can deleted. Snapshots
can be taken on volumes, but they can only be cloned or
rolled back, not mounted independently. |
Clone | Snapshots can also be cloned. A clone is a writable version of a snapshot, allowing the file system to be forked as a new dataset. As with a snapshot, a clone initially consumes no additional space. As new data is written to a clone and new blocks are allocated, the apparent size of the clone grows. When blocks are overwritten in the cloned file system or volume, the reference count on the previous block is decremented. The snapshot upon which a clone is based cannot be deleted because the clone depends on it. The snapshot is the parent, and the clone is the child. Clones can be promoted, reversing this dependency and making the clone the parent and the previous parent the child. This operation requires no additional space. Because the amount of space used by the parent and child is reversed, existing quotas and reservations might be affected. |
Checksum | Every block that is allocated is also checksummed.
The checksum algorithm used is a per-dataset property,
see set .
The checksum of each block is transparently validated as
it is read, allowing ZFS to detect
silent corruption. If the data that is read does not
match the expected checksum, ZFS will
attempt to recover the data from any available
redundancy, like mirrors or RAID-Z).
Validation of all checksums can be triggered with scrub .
Checksum algorithms include:
fletcher algorithms are faster,
but sha256 is a strong cryptographic
hash and has a much lower chance of collisions at the
cost of some performance. Checksums can be disabled,
but it is not recommended. |
Compression | Each dataset has a compression property, which
defaults to off. This property can be set to one of a
number of compression algorithms. This will cause all
new data that is written to the dataset to be
compressed. Beyond a reduction in space used, read and
write throughput often increases because fewer blocks
are read or written.
|
Copies | When set to a value greater than 1, the
copies property instructs
ZFS to maintain multiple copies of
each block in the
File System
or
Volume. Setting
this property on important datasets provides additional
redundancy from which to recover a block that does not
match its checksum. In pools without redundancy, the
copies feature is the only form of redundancy. The
copies feature can recover from a single bad sector or
other forms of minor corruption, but it does not protect
the pool from the loss of an entire disk. |
Deduplication | Checksums make it possible to detect duplicate
blocks of data as they are written. With deduplication,
the reference count of an existing, identical block is
increased, saving storage space. To detect duplicate
blocks, a deduplication table (DDT)
is kept in memory. The table contains a list of unique
checksums, the location of those blocks, and a reference
count. When new data is written, the checksum is
calculated and compared to the list. If a match is
found, the existing block is used. The
SHA256 checksum algorithm is used
with deduplication to provide a secure cryptographic
hash. Deduplication is tunable. If
dedup is on , then
a matching checksum is assumed to mean that the data is
identical. If dedup is set to
verify , then the data in the two
blocks will be checked byte-for-byte to ensure it is
actually identical. If the data is not identical, the
hash collision will be noted and the two blocks will be
stored separately. Because DDT must
store the hash of each unique block, it consumes a very
large amount of memory. A general rule of thumb is
5-6 GB of ram per 1 TB of deduplicated data).
In situations where it is not practical to have enough
RAM to keep the entire
DDT in memory, performance will
suffer greatly as the DDT must be
read from disk before each new block is written.
Deduplication can use L2ARC to store
the DDT, providing a middle ground
between fast system memory and slower disks. Consider
using compression instead, which often provides nearly
as much space savings without the additional memory
requirement. |
Scrub | Instead of a consistency check like fsck(8),
ZFS has scrub .
scrub reads all data blocks stored on
the pool and verifies their checksums against the known
good checksums stored in the metadata. A periodic check
of all the data stored on the pool ensures the recovery
of any corrupted blocks before they are needed. A scrub
is not required after an unclean shutdown, but is
recommended at least once every three months. The
checksum of each block is verified as blocks are read
during normal use, but a scrub makes certain that even
infrequently used blocks are checked for silent
corruption. Data security is improved, especially in
archival storage situations. The relative priority of
scrub can be adjusted with vfs.zfs.scrub_delay
to prevent the scrub from degrading the performance of
other workloads on the pool. |
Dataset Quota | ZFS provides very fast and
accurate dataset, user, and group space accounting in
addition to quotas and space reservations. This gives
the administrator fine grained control over how space is
allocated and allows space to be reserved for critical
file systems.
ZFS supports different types of quotas: the dataset quota, the reference quota (refquota), the user quota, and the group quota. Quotas limit the amount of space that a dataset and all of its descendants, including snapshots of the dataset, child datasets, and the snapshots of those datasets, can consume. Note:Quotas cannot be set on volumes, as the
|
Reference Quota | A reference quota limits the amount of space a dataset can consume by enforcing a hard limit. However, this hard limit includes only space that the dataset references and does not include space used by descendants, such as file systems or snapshots. |
User Quota | User quotas are useful to limit the amount of space that can be used by the specified user. |
Group Quota | The group quota limits the amount of space that a specified group can consume. |
Dataset Reservation | The reservation property makes
it possible to guarantee a minimum amount of space for a
specific dataset and its descendants. If a 10 GB
reservation is set on
storage/home/bob , and another
dataset tries to use all of the free space, at least
10 GB of space is reserved for this dataset. If a
snapshot is taken of
storage/home/bob , the space used by
that snapshot is counted against the reservation. The
refreservation
property works in a similar way, but it
excludes descendants like
snapshots.
Reservations of any sort are useful in many situations, such as planning and testing the suitability of disk space allocation in a new system, or ensuring that enough space is available on file systems for audio logs or system recovery procedures and files. |
Reference Reservation | The refreservation property
makes it possible to guarantee a minimum amount of
space for the use of a specific dataset
excluding its descendants. This
means that if a 10 GB reservation is set on
storage/home/bob , and another
dataset tries to use all of the free space, at least
10 GB of space is reserved for this dataset. In
contrast to a regular
reservation,
space used by snapshots and descendant datasets is not
counted against the reservation. For example, if a
snapshot is taken of
storage/home/bob , enough disk space
must exist outside of the
refreservation amount for the
operation to succeed. Descendants of the main data set
are not counted in the refreservation
amount and so do not encroach on the space set. |
Resilver | When a disk fails and is replaced, the new disk must be filled with the data that was lost. The process of using the parity information distributed across the remaining drives to calculate and write the missing data to the new drive is called resilvering. |
Online | A pool or vdev in the Online
state has all of its member devices connected and fully
operational. Individual devices in the
Online state are functioning
normally. |
Offline | Individual devices can be put in an
Offline state by the administrator if
there is sufficient redundancy to avoid putting the pool
or vdev into a
Faulted state.
An administrator may choose to offline a disk in
preparation for replacing it, or to make it easier to
identify. |
Degraded | A pool or vdev in the Degraded
state has one or more disks that have been disconnected
or have failed. The pool is still usable, but if
additional devices fail, the pool could become
unrecoverable. Reconnecting the missing devices or
replacing the failed disks will return the pool to an
Online state
after the reconnected or new device has completed the
Resilver
process. |
Faulted | A pool or vdev in the Faulted
state is no longer operational. The data on it can no
longer be accessed. A pool or vdev enters the
Faulted state when the number of
missing or failed devices exceeds the level of
redundancy in the vdev. If missing devices can be
reconnected, the pool will return to a
Online state. If
there is insufficient redundancy to compensate for the
number of failed disks, then the contents of the pool
are lost and must be restored from backups. |
File systems are an integral part of any operating system. They allow users to upload and store files, provide access to data, and make hard drives useful. Different operating systems differ in their native file system. Traditionally, the native FreeBSD file system has been the Unix File System UFS which has been modernized as UFS2. Since FreeBSD 7.0, the Z File System (ZFS) is also available as a native file system. See Chapter 19, The Z File System (ZFS) for more information.
In addition to its native file systems, FreeBSD supports a multitude of other file systems so that data from other operating systems can be accessed locally, such as data stored on locally attached USB storage devices, flash drives, and hard disks. This includes support for the Linux® Extended File System (EXT).
There are different levels of FreeBSD support for the various file systems. Some require a kernel module to be loaded and others may require a toolset to be installed. Some non-native file system support is full read-write while others are read-only.
After reading this chapter, you will know:
The difference between native and supported file systems.
Which file systems are supported by FreeBSD.
How to enable, configure, access, and make use of non-native file systems.
Before reading this chapter, you should:
Understand UNIX® and FreeBSD basics.
Be familiar with the basics of kernel configuration and compilation.
Feel comfortable installing software in FreeBSD.
Have some familiarity with disks, storage, and device names in FreeBSD.
FreeBSD provides built-in support for several Linux® file systems. This section demonstrates how to load support for and how to mount the supported Linux® file systems.
Kernel support for ext2 file systems has been available since FreeBSD 2.2. In FreeBSD 8.x and earlier, the code is licensed under the GPL. Since FreeBSD 9.0, the code has been rewritten and is now BSD licensed.
The ext2fs(5) driver allows the FreeBSD kernel to both read and write to ext2 file systems.
This driver can also be used to access ext3 and ext4 file systems. The ext2fs(5) filesystem has full read and write support for ext4 as of FreeBSD 12.0-RELEASE. Additionally, extended attributes and ACLs are also supported, while journalling and encryption are not. Starting with FreeBSD 12.1-RELEASE, a DTrace provider will be available as well. Prior versions of FreeBSD can access ext4 in read and write mode using sysutils/fusefs-ext2.
To access an ext file system, first load the kernel loadable module:
#
kldload ext2fs
Then, mount the ext volume by specifying its FreeBSD
partition name and an existing mount point. This example
mounts /dev/ad1s1
on
/mnt
:
#
mount -t ext2fs
/dev/ad1s1
/mnt
Virtualization software allows multiple operating systems to run simultaneously on the same computer. Such software systems for PCs often involve a host operating system which runs the virtualization software and supports any number of guest operating systems.
After reading this chapter, you will know:
The difference between a host operating system and a guest operating system.
How to install FreeBSD on an Intel®-based Apple® Mac® computer.
How to install FreeBSD on Microsoft® Windows® with Virtual PC.
How to install FreeBSD as a guest in bhyve.
How to tune a FreeBSD system for best performance under virtualization.
Before reading this chapter, you should:
Understand the basics of UNIX® and FreeBSD.
Know how to install FreeBSD.
Know how to set up a network connection.
Know how to install additional third-party software.
Parallels Desktop for Mac® is a commercial software product available for Intel® based Apple® Mac® computers running Mac OS® 10.4.6 or higher. FreeBSD is a fully supported guest operating system. Once Parallels has been installed on Mac OS® X, the user must configure a virtual machine and then install the desired guest operating system.
The first step in installing FreeBSD on Parallels is to create a new virtual machine for installing FreeBSD. Select as the when prompted:
Choose a reasonable amount of disk and memory depending on the plans for this virtual FreeBSD instance. 4GB of disk space and 512MB of RAM work well for most uses of FreeBSD under Parallels:
Select the type of networking and a network interface:
Save and finish the configuration:
After the FreeBSD virtual machine has been created, FreeBSD can be installed on it. This is best done with an official FreeBSD CD/DVD or with an ISO image downloaded from an official FTP site. Copy the appropriate ISO image to the local Mac® filesystem or insert a CD/DVD in the Mac®'s CD-ROM drive. Click on the disc icon in the bottom right corner of the FreeBSD Parallels window. This will bring up a window that can be used to associate the CD-ROM drive in the virtual machine with the ISO file on disk or with the real CD-ROM drive.
Once this association with the CD-ROM source has been made, reboot the FreeBSD virtual machine by clicking the reboot icon. Parallels will reboot with a special BIOS that first checks if there is a CD-ROM.
In this case it will find the FreeBSD installation media and begin a normal FreeBSD installation. Perform the installation, but do not attempt to configure Xorg at this time.
When the installation is finished, reboot into the newly installed FreeBSD virtual machine.
After FreeBSD has been successfully installed on Mac OS® X with Parallels, there are a number of configuration steps that can be taken to optimize the system for virtualized operation.
Set Boot Loader Variables
The most important step is to reduce the
kern.hz
tunable to reduce the CPU
utilization of FreeBSD under the
Parallels environment. This is
accomplished by adding the following line to
/boot/loader.conf
:
kern.hz=100
Without this setting, an idle FreeBSD Parallels guest will use roughly 15% of the CPU of a single processor iMac®. After this change the usage will be closer to 5%.
Create a New Kernel Configuration File
All of the SCSI, FireWire, and USB device drivers can be removed from a custom kernel configuration file. Parallels provides a virtual network adapter used by the ed(4) driver, so all network devices except for ed(4) and miibus(4) can be removed from the kernel.
Configure Networking
The most basic networking setup uses DHCP to connect
the virtual machine to the same local area network as the
host Mac®. This can be accomplished by adding
ifconfig_ed0="DHCP"
to
/etc/rc.conf
. More advanced
networking setups are described in
Chapter 31, Advanced Networking.
Virtual PC for Windows® is a Microsoft® software product available for free download. See this website for the system requirements. Once Virtual PC has been installed on Microsoft® Windows®, the user can configure a virtual machine and then install the desired guest operating system.
The first step in installing FreeBSD on Virtual PC is to create a new virtual machine for installing FreeBSD. Select when prompted:
Select
as the when prompted:Then, choose a reasonable amount of disk and memory depending on the plans for this virtual FreeBSD instance. 4GB of disk space and 512MB of RAM work well for most uses of FreeBSD under Virtual PC:
Save and finish the configuration:
Select the FreeBSD virtual machine and click
, then set the type of networking and a network interface:After the FreeBSD virtual machine has been created, FreeBSD can be installed on it. This is best done with an official FreeBSD CD/DVD or with an ISO image downloaded from an official FTP site. Copy the appropriate ISO image to the local Windows® filesystem or insert a CD/DVD in the CD drive, then double click on the FreeBSD virtual machine to boot. Then, click and choose on the Virtual PC window. This will bring up a window where the CD-ROM drive in the virtual machine can be associated with an ISO file on disk or with the real CD-ROM drive.
Once this association with the CD-ROM source has been made, reboot the FreeBSD virtual machine by clicking Virtual PC will reboot with a special BIOS that first checks for a CD-ROM.
and .In this case it will find the FreeBSD installation media and begin a normal FreeBSD installation. Continue with the installation, but do not attempt to configure Xorg at this time.
When the installation is finished, remember to eject the CD/DVD or release the ISO image. Finally, reboot into the newly installed FreeBSD virtual machine.
After FreeBSD has been successfully installed on Microsoft® Windows® with Virtual PC, there are a number of configuration steps that can be taken to optimize the system for virtualized operation.
Set Boot Loader Variables
The most important step is to reduce the
kern.hz
tunable to reduce the CPU
utilization of FreeBSD under the
Virtual PC environment. This
is accomplished by adding the following line to
/boot/loader.conf
:
kern.hz=100
Without this setting, an idle FreeBSD Virtual PC guest OS will use roughly 40% of the CPU of a single processor computer. After this change, the usage will be closer to 3%.
Create a New Kernel Configuration File
All of the SCSI, FireWire, and USB device drivers can be removed from a custom kernel configuration file. Virtual PC provides a virtual network adapter used by the de(4) driver, so all network devices except for de(4) and miibus(4) can be removed from the kernel.
Configure Networking
The most basic networking setup uses DHCP to connect
the virtual machine to the same local area network as the
Microsoft® Windows® host. This can be accomplished by
adding ifconfig_de0="DHCP"
to
/etc/rc.conf
. More advanced
networking setups are described in
Chapter 31, Advanced Networking.
VMware Fusion for Mac® is a commercial software product available for Intel® based Apple® Mac® computers running Mac OS® 10.4.9 or higher. FreeBSD is a fully supported guest operating system. Once VMware Fusion has been installed on Mac OS® X, the user can configure a virtual machine and then install the desired guest operating system.
The first step is to start VMware Fusion which will load the Virtual Machine Library. Click to create the virtual machine:
This will load the New Virtual Machine Assistant. Click
to proceed:Select
as the and either or , as the when prompted:Choose the name of the virtual machine and the directory where it should be saved:
Choose the size of the Virtual Hard Disk for the virtual machine:
Choose the method to install the virtual machine, either from an ISO image or from a CD/DVD:
Click
and the virtual machine will boot:Install FreeBSD as usual:
Once the install is complete, the settings of the virtual machine can be modified, such as memory usage:
The System Hardware settings of the virtual machine cannot be modified while the virtual machine is running.
The number of CPUs the virtual machine will have access to:
The status of the CD-ROM device. Normally the CD/DVD/ISO is disconnected from the virtual machine when it is no longer needed.
The last thing to change is how the virtual machine will connect to the network. To allow connections to the virtual machine from other machines besides the host, choose
. Otherwise, is preferred so that the virtual machine can have access to the Internet, but the network cannot access the virtual machine.After modifying the settings, boot the newly installed FreeBSD virtual machine.
After FreeBSD has been successfully installed on Mac OS® X with VMware Fusion, there are a number of configuration steps that can be taken to optimize the system for virtualized operation.
Set Boot Loader Variables
The most important step is to reduce the
kern.hz
tunable to reduce the CPU
utilization of FreeBSD under the
VMware Fusion environment.
This is accomplished by adding the following line to
/boot/loader.conf
:
kern.hz=100
Without this setting, an idle FreeBSD VMware Fusion guest will use roughly 15% of the CPU of a single processor iMac®. After this change, the usage will be closer to 5%.
Create a New Kernel Configuration File
All of the FireWire, and USB device drivers can be removed from a custom kernel configuration file. VMware Fusion provides a virtual network adapter used by the em(4) driver, so all network devices except for em(4) can be removed from the kernel.
Configure Networking
The most basic networking setup uses DHCP to connect
the virtual machine to the same local area network as the
host Mac®. This can be accomplished by adding
ifconfig_em0="DHCP"
to
/etc/rc.conf
. More advanced
networking setups are described in
Chapter 31, Advanced Networking.
FreeBSD works well as a guest in VirtualBox™. The virtualization software is available for most common operating systems, including FreeBSD itself.
The VirtualBox™ guest additions provide support for:
Clipboard sharing.
Mouse pointer integration.
Host time synchronization.
Window scaling.
Seamless mode.
These commands are run in the FreeBSD guest.
First, install the emulators/virtualbox-ose-additions package or port in the FreeBSD guest. This will install the port:
#
cd /usr/ports/emulators/virtualbox-ose-additions && make install clean
Add these lines to /etc/rc.conf
:
vboxguest_enable="YES" vboxservice_enable="YES"
If ntpd(8) or ntpdate(8) is used, disable host time synchronization:
vboxservice_flags="--disable-timesync"
Xorg will automatically recognize
the vboxvideo
driver. It can also be
manually entered in
/etc/X11/xorg.conf
:
Section "Device" Identifier "Card0" Driver "vboxvideo" VendorName "InnoTek Systemberatung GmbH" BoardName "VirtualBox Graphics Adapter" EndSection
To use the vboxmouse
driver, adjust the
mouse section in /etc/X11/xorg.conf
:
Section "InputDevice" Identifier "Mouse0" Driver "vboxmouse" EndSection
HAL users should create the following
/usr/local/etc/hal/fdi/policy/90-vboxguest.fdi
or copy it from
/usr/local/share/hal/fdi/policy/10osvendor/90-vboxguest.fdi
:
<?xml version="1.0" encoding="utf-8"?> <!-- # Sun VirtualBox # Hal driver description for the vboxmouse driver # $Id: chapter.xml,v 1.33 2012-03-17 04:53:52 eadler Exp $ Copyright (C) 2008-2009 Sun Microsystems, Inc. This file is part of VirtualBox Open Source Edition (OSE, as available from http://www.virtualbox.org. This file is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License (GPL) as published by the Free Software Foundation, in version 2 as it comes in the "COPYING" file of the VirtualBox OSE distribution. VirtualBox OSE is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY of any kind. Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, CA 95054 USA or visit http://www.sun.com if you need additional information or have any questions. --> <deviceinfo version="0.2"> <device> <match key="info.subsystem" string="pci"> <match key="info.product" string="VirtualBox guest Service"> <append key="info.capabilities" type="strlist">input</append> <append key="info.capabilities" type="strlist">input.mouse</append> <merge key="input.x11_driver" type="string">vboxmouse</merge> <merge key="input.device" type="string">/dev/vboxguest</merge> </match> </match> </device> </deviceinfo>
Shared folders for file transfers between host and VM are
accessible by mounting them using
mount_vboxvfs
. A shared folder can be created
on the host using the VirtualBox GUI or via
vboxmanage
. For example, to create a shared
folder called myshare
under
for the VM named /mnt/bsdboxshare
BSDBox
, run:
#
vboxmanage sharedfolder add '
BSDBox
' --namemyshare
--hostpath/mnt/bsdboxshare
Note that the shared folder name must not contain spaces. Mount the shared folder from within the guest system like this:
#
mount_vboxvfs -w
myshare
/mnt
VirtualBox™ is an actively developed, complete virtualization package, that is available for most operating systems including Windows®, Mac OS®, Linux® and FreeBSD. It is equally capable of running Windows® or UNIX®-like guests. It is released as open source software, but with closed-source components available in a separate extension pack. These components include support for USB 2.0 devices. More information may be found on the “Downloads” page of the VirtualBox™ wiki. Currently, these extensions are not available for FreeBSD.
VirtualBox™ is available as a FreeBSD package or port in emulators/virtualbox-ose. The port can be installed using these commands:
#
cd /usr/ports/emulators/virtualbox-ose
#
make install clean
One useful option in the port's configuration menu is the
GuestAdditions
suite of programs. These
provide a number of useful features in guest operating
systems, like mouse pointer integration (allowing the mouse to
be shared between host and guest without the need to press a
special keyboard shortcut to switch) and faster video
rendering, especially in Windows® guests. The guest
additions are available in the
menu, after the installation of the guest is finished.
A few configuration changes are needed before
VirtualBox™ is started for the
first time. The port installs a kernel module in
/boot/modules
which
must be loaded into the running kernel:
#
kldload vboxdrv
To ensure the module is always loaded after a reboot,
add this line to
/boot/loader.conf
:
vboxdrv_load="YES"
To use the kernel modules that allow bridged or host-only
networking, add this line to
/etc/rc.conf
and reboot the
computer:
vboxnet_enable="YES"
The vboxusers
group is created during installation of
VirtualBox™. All users that need
access to VirtualBox™ will have to
be added as members of this group. pw
can
be used to add new members:
#
pw groupmod vboxusers -m
yourusername
The default permissions for
/dev/vboxnetctl
are restrictive and need
to be changed for bridged networking:
#
chown root:vboxusers /dev/vboxnetctl
#
chmod 0660 /dev/vboxnetctl
To make this permissions change permanent, add these
lines to /etc/devfs.conf
:
own vboxnetctl root:vboxusers perm vboxnetctl 0660
To launch VirtualBox™, type from a Xorg session:
%
VirtualBox
For more information on configuring and using VirtualBox™, refer to the official website. For FreeBSD-specific information and troubleshooting instructions, refer to the relevant page in the FreeBSD wiki.
VirtualBox™ can be configured to pass USB devices through to the guest operating system. The host controller of the OSE version is limited to emulating USB 1.1 devices until the extension pack supporting USB 2.0 and 3.0 devices becomes available on FreeBSD.
For VirtualBox™ to be aware of
USB devices attached to the machine, the
user needs to be a member of the operator
group.
#
pw groupmod operator -m
yourusername
Then, add the following to
/etc/devfs.rules
, or create this file if
it does not exist yet:
[system=10] add path 'usb/*' mode 0660 group operator
To load these new rules, add the following to
/etc/rc.conf
:
devfs_system_ruleset="system"
Then, restart devfs:
#
service devfs restart
Restart the login session and VirtualBox™ for these changes to take effect, and create USB filters as necessary.
Access to the host
DVD/CD drives from
guests is achieved through the sharing of the physical drives.
Within VirtualBox™, this is set up from the Storage window in
the Settings of the virtual machine. If needed, create an
empty IDE
CD/DVD device first.
Then choose the Host Drive from the popup menu for the virtual
CD/DVD drive selection.
A checkbox labeled Passthrough
will appear.
This allows the virtual machine to use the hardware directly.
For example, audio CDs or the burner will
only function if this option is selected.
HAL needs to run for
VirtualBox™
DVD/CD functions to
work, so enable it in /etc/rc.conf
and
start it if it is not already running:
hald_enable="YES"
#
service hald start
In order for users to be able to use
VirtualBox™
DVD/CD functions, they
need access to /dev/xpt0
,
/dev/cd
, and
N
/dev/pass
.
This is usually achieved by making the user a member of
N
operator
.
Permissions to these devices have to be corrected by adding
these lines to /etc/devfs.conf
:
perm cd* 0660 perm xpt0 0660 perm pass* 0660
#
service devfs restart
The bhyve BSD-licensed hypervisor became part of the base system with FreeBSD 10.0-RELEASE. This hypervisor supports a number of guests, including FreeBSD, OpenBSD, and many Linux® distributions. By default, bhyve provides access to serial console and does not emulate a graphical console. Virtualization offload features of newer CPUs are used to avoid the legacy methods of translating instructions and manually managing memory mappings.
The bhyve design requires a
processor that supports Intel® Extended Page Tables
(EPT) or AMD® Rapid Virtualization Indexing
(RVI) or Nested Page Tables
(NPT). Hosting Linux® guests or FreeBSD guests
with more than one vCPU requires
VMX unrestricted mode support
(UG). Most newer processors, specifically
the Intel® Core™ i3/i5/i7 and Intel® Xeon™
E3/E5/E7, support these features. UG support
was introduced with Intel's Westmere micro-architecture. For a
complete list of Intel® processors that support
EPT, refer to https://ark.intel.com/content/www/us/en/ark/search/featurefilter.html?productType=873&0_ExtendedPageTables=True.
RVI is found on the third generation and
later of the AMD Opteron™ (Barcelona) processors. The easiest
way to tell if a processor supports
bhyve is to run
dmesg
or look in
/var/run/dmesg.boot
for the
POPCNT
processor feature flag on the
Features2
line for AMD® processors or
EPT
and UG
on the
VT-x
line for Intel® processors.
The first step to creating a virtual machine in bhyve is configuring the host system. First, load the bhyve kernel module:
#
kldload vmm
Then, create a tap
interface for the
network device in the virtual machine to attach to. In order
for the network device to participate in the network, also
create a bridge interface containing the
tap
interface and the physical interface
as members. In this example, the physical interface is
igb0
:
#
ifconfig
tap0
create#
sysctl net.link.tap.up_on_open=1
net.link.tap.up_on_open: 0 -> 1#
ifconfig
bridge0
create#
ifconfig
bridge0
addmigb0
addmtap0
#
ifconfig
bridge0
up
Create a file to use as the virtual disk for the guest machine. Specify the size and name of the virtual disk:
#
truncate -s
16G
guest.img
Download an installation image of FreeBSD to install:
#
fetch
FreeBSD-10.3-RELEASE-amd64-bootonly.iso 100% of 230 MB 570 kBps 06m17sftp://ftp.freebsd.org/pub/FreeBSD/releases/ISO-IMAGES/10.3/FreeBSD-10.3-RELEASE-amd64-bootonly.iso
FreeBSD comes with an example script for running a virtual
machine in bhyve. The script will
start the virtual machine and run it in a loop, so it will
automatically restart if it crashes. The script takes a
number of options to control the configuration of the machine:
-c
controls the number of virtual CPUs,
-m
limits the amount of memory available to
the guest, -t
defines which
tap
device to use, -d
indicates which disk image to use, -i
tells
bhyve to boot from the
CD image instead of the disk, and
-I
defines which CD image
to use. The last parameter is the name of the virtual
machine, used to track the running machines. This example
starts the virtual machine in installation mode:
#
sh /usr/share/examples/bhyve/vmrun.sh -c
1
-m1024M
-ttap0
-dguest.img
-i -IFreeBSD-10.3-RELEASE-amd64-bootonly.iso
guestname
The virtual machine will boot and start the installer. After installing a system in the virtual machine, when the system asks about dropping in to a shell at the end of the installation, choose
.Reboot the virtual machine. While rebooting the virtual
machine causes bhyve to exit, the
vmrun.sh
script runs
bhyve
in a loop and will automatically
restart it. When this happens, choose the reboot option from
the boot loader menu in order to escape the loop. Now the
guest can be started from the virtual disk:
#
sh /usr/share/examples/bhyve/vmrun.sh -c
4
-m1024M
-ttap0
-dguest.img
guestname
In order to boot operating systems other than FreeBSD, the sysutils/grub2-bhyve port must be first installed.
Next, create a file to use as the virtual disk for the guest machine:
#
truncate -s
16G
linux.img
Starting a virtual machine with
bhyve is a two step process. First
a kernel must be loaded, then the guest can be started. The
Linux® kernel is loaded with
sysutils/grub2-bhyve. Create a
device.map
that
grub will use to map the virtual
devices to the files on the host system:
(hd0) ./linux.img (cd0) ./somelinux.iso
Use sysutils/grub2-bhyve to load the Linux® kernel from the ISO image:
#
grub-bhyve -m device.map -r cd0 -M
1024M
linuxguest
This will start grub. If the installation
CD contains a
grub.cfg
, a menu will be displayed.
If not, the vmlinuz
and
initrd
files must be located and loaded
manually:
grub>ls
(hd0) (cd0) (cd0,msdos1) (host) grub>ls (cd0)/isolinux
boot.cat boot.msg grub.conf initrd.img isolinux.bin isolinux.cfg memtest splash.jpg TRANS.TBL vesamenu.c32 vmlinuz grub>linux (cd0)/isolinux/vmlinuz
grub>initrd (cd0)/isolinux/initrd.img
grub>boot
Now that the Linux® kernel is loaded, the guest can be started:
#
bhyve -A -H -P -s 0:0,hostbridge -s 1:0,lpc -s 2:0,virtio-net,
tap0
-s 3:0,virtio-blk,./linux.img
\ -s 4:0,ahci-cd,./somelinux.iso
-l com1,stdio -c4
-m1024M
linuxguest
The system will boot and start the installer. After installing a system in the virtual machine, reboot the virtual machine. This will cause bhyve to exit. The instance of the virtual machine needs to be destroyed before it can be started again:
#
bhyvectl --destroy --vm=
linuxguest
Now the guest can be started directly from the virtual disk. Load the kernel:
#
grub-bhyve -m device.map -r hd0,msdos1 -M
grub>1024M
linuxguest
ls
(hd0) (hd0,msdos2) (hd0,msdos1) (cd0) (cd0,msdos1) (host) (lvm/VolGroup-lv_swap) (lvm/VolGroup-lv_root) grub>ls (hd0,msdos1)/
lost+found/ grub/ efi/ System.map-2.6.32-431.el6.x86_64 config-2.6.32-431.el6.x 86_64 symvers-2.6.32-431.el6.x86_64.gz vmlinuz-2.6.32-431.el6.x86_64 initramfs-2.6.32-431.el6.x86_64.img grub>linux (hd0,msdos1)/vmlinuz-2.6.32-431.el6.x86_64 root=/dev/mapper/VolGroup-lv_root
grub>initrd (hd0,msdos1)/initramfs-2.6.32-431.el6.x86_64.img
grub>boot
Boot the virtual machine:
#
bhyve -A -H -P -s 0:0,hostbridge -s 1:0,lpc -s 2:0,virtio-net,
tap0
\ -s 3:0,virtio-blk,./linux.img
-l com1,stdio -c4
-m1024M
linuxguest
Linux® will now boot in the virtual machine and eventually present you with the login prompt. Login and use the virtual machine. When you are finished, reboot the virtual machine to exit bhyve. Destroy the virtual machine instance:
#
bhyvectl --destroy --vm=
linuxguest
In addition to bhyveload and grub-bhyve, the bhyve hypervisor can also boot virtual machines using the UEFI userspace firmware. This option may support guest operating systems that are not supported by the other loaders.
In order to make use of the UEFI support in bhyve, first obtain the UEFI firmware images. This can be done by installing sysutils/bhyve-firmware port or package.
With the firmware in place, add the flags -l
bootrom,
to your bhyve command line. The
actual bhyve command may look like
this:/path/to/firmware
#
bhyve -AHP -s 0:0,hostbridge -s 1:0,lpc \ -s 2:0,virtio-net,
tap1
-s 3:0,virtio-blk,./disk.img
\ -s 4:0,ahci-cd,./install.iso
-c4
-m1024M
\ -l bootrom,/usr/local/share/uefi-firmware/BHYVE_UEFI.fd
\guest
sysutils/bhyve-firmware also contains a CSM-enabled firmware, to boot guests with no UEFI support in legacy BIOS mode:
#
bhyve -AHP -s 0:0,hostbridge -s 1:0,lpc \ -s 2:0,virtio-net,
tap1
-s 3:0,virtio-blk,./disk.img
\ -s 4:0,ahci-cd,./install.iso
-c4
-m1024M
\ -l bootrom,/usr/local/share/uefi-firmware/BHYVE_UEFI_CSM.fd
\guest
The UEFI firmware support is particularly useful with predominantly graphical guest operating systems such as Microsoft Windows®.
Support for the UEFI-GOP framebuffer may also be enabled
with the -s
29,fbuf,tcp=
flags. The framebuffer resolution may be configured with
0.0.0.0:5900
w=
and
800
h=
, and
bhyve can be instructed to wait for
a VNC connection before booting the guest
by adding 600
wait
. The framebuffer may be
accessed from the host or over the network via the
VNC protocol.
The resulting bhyve command would look like this:
#
bhyve -AHP -s 0:0,hostbridge -s 31:0,lpc \ -s 2:0,virtio-net,
tap1
-s 3:0,virtio-blk,./disk.img
\ -s 4:0,ahci-cd,./install.iso
-c4
-m1024M
\ -s 29,fbuf,tcp=0.0.0.0:5900
,w=800
,h=600
,wait \ -l bootrom,/usr/local/share/uefi-firmware/BHYVE_UEFI.fd
\guest
Note, in BIOS emulation mode, the framebuffer will cease receiving updates once control is passed from firmware to guest operating system.
If ZFS is available on the host machine, using ZFS volumes instead of disk image files can provide significant performance benefits for the guest VMs. A ZFS volume can be created by:
#
zfs create -V
16G
-o volmode=devzroot/linuxdisk0
When starting the VM, specify the ZFS volume as the disk drive:
#
bhyve -A -H -P -s 0:0,hostbridge -s 1:0,lpc -s 2:0,virtio-net,
tap0
-s3:0,virtio-blk,/dev/zvol/zroot/linuxdisk0
\ -l com1,stdio
-c4
-m1024M
linuxguest
It is advantageous to wrap the
bhyve console in a session
management tool such as sysutils/tmux or
sysutils/screen in order to detach and
reattach to the console. It is also possible to have the
console of bhyve be a null modem
device that can be accessed with cu
. To do
this, load the nmdm
kernel module and
replace -l com1,stdio
with
-l com1,/dev/nmdm0A
. The
/dev/nmdm
devices are created
automatically as needed, where each is a pair, corresponding
to the two ends of the null modem cable
(/dev/nmdm0A
and
/dev/nmdm0B
). See nmdm(4) for more
information.
#
kldload nmdm
#
bhyve -A -H -P -s 0:0,hostbridge -s 1:0,lpc -s 2:0,virtio-net,
tap0
-s 3:0,virtio-blk,./linux.img
\ -l com1,/dev/nmdm0A
-c4
-m1024M
linuxguest
#
cu -l
Connected Ubuntu 13.10 handbook ttyS0 handbook login:/dev/nmdm0B
A device node is created in /dev/vmm
for each virtual
machine. This allows the administrator to easily see a list
of the running virtual machines:
#
ls -al /dev/vmm
total 1 dr-xr-xr-x 2 root wheel 512 Mar 17 12:19 ./ dr-xr-xr-x 14 root wheel 512 Mar 17 06:38 ../ crw------- 1 root wheel 0x1a2 Mar 17 12:20 guestname crw------- 1 root wheel 0x19f Mar 17 12:19 linuxguest crw------- 1 root wheel 0x1a1 Mar 17 12:19 otherguest
A specified virtual machine can be destroyed using
bhyvectl
:
#
bhyvectl --destroy --vm=
guestname
In order to configure the system to start bhyve guests at boot time, the following configurations must be made in the specified files:
/etc/sysctl.conf
net.link.tap.up_on_open=1
/etc/rc.conf
cloned_interfaces="bridge0
tap0
" ifconfig_bridge0="addmigb0
addmtap0
" kld_list="nmdm vmm"
Xen is a GPLv2-licensed type 1 hypervisor for Intel® and ARM® architectures. FreeBSD has included i386™ and AMD® 64-Bit DomU and Amazon EC2 unprivileged domain (virtual machine) support since FreeBSD 8.0 and includes Dom0 control domain (host) support in FreeBSD 11.0. Support for para-virtualized (PV) domains has been removed from FreeBSD 11 in favor of hardware virtualized (HVM) domains, which provides better performance.
Xen™ is a bare-metal hypervisor, which means that it is the
first program loaded after the BIOS. A special privileged guest
called the Domain-0 (Dom0
for short) is then
started. The Dom0 uses its special privileges to directly
access the underlying physical hardware, making it a
high-performance solution. It is able to access the disk
controllers and network adapters directly. The Xen™ management
tools to manage and control the Xen™ hypervisor are also used
by the Dom0 to create, list, and destroy VMs. Dom0 provides
virtual disks and networking for unprivileged domains, often
called DomU
. Xen™ Dom0 can be compared to
the service console of other hypervisor solutions, while the
DomU is where individual guest VMs are run.
Xen™ can migrate VMs between different Xen™ servers. When the two xen hosts share the same underlying storage, the migration can be done without having to shut the VM down first. Instead, the migration is performed live while the DomU is running and there is no need to restart it or plan a downtime. This is useful in maintenance scenarios or upgrade windows to ensure that the services provided by the DomU are still provided. Many more features of Xen™ are listed on the Xen Wiki Overview page. Note that not all features are supported on FreeBSD yet.
To run the Xen™ hypervisor on a host, certain hardware functionality is required. Hardware virtualized domains require Extended Page Table (EPT) and Input/Output Memory Management Unit (IOMMU) support in the host processor.
In order to run a FreeBSD Xen™ Dom0 the box must be booted using legacy boot (BIOS).
Users of FreeBSD 11 should install the emulators/xen-kernel47 and sysutils/xen-tools47 packages that are based on Xen version 4.7. Systems running on FreeBSD-12.0 or newer can use Xen 4.11 provided by emulators/xen-kernel411 and sysutils/xen-tools411, respectively.
Configuration files must be edited to prepare the host
for the Dom0 integration after the Xen packages are installed.
An entry to /etc/sysctl.conf
disables the
limit on how many pages of memory are allowed to be wired.
Otherwise, DomU VMs with higher memory requirements will not
run.
#
echo 'vm.max_wired=-1' >> /etc/sysctl.conf
Another memory-related setting involves changing
/etc/login.conf
, setting the
memorylocked
option to
unlimited
. Otherwise, creating DomU
domains may fail with Cannot allocate
memory errors. After making the change to
/etc/login.conf
, run
cap_mkdb
to update the capability database.
See Section 13.13, “Resource Limits” for
details.
#
sed -i '' -e 's/memorylocked=64K/memorylocked=unlimited/' /etc/login.conf
#
cap_mkdb /etc/login.conf
Add an entry for the Xen™ console to
/etc/ttys
:
#
echo 'xc0 "/usr/libexec/getty Pc" xterm onifconsole secure' >> /etc/ttys
Selecting a Xen™ kernel in
/boot/loader.conf
activates the Dom0.
Xen™ also requires resources like CPU and memory from the
host machine for itself and other DomU domains. How much CPU
and memory depends on the individual requirements and hardware
capabilities. In this example, 8 GB of memory and 4
virtual CPUs are made available for the Dom0. The serial
console is also activated and logging options are
defined.
The following command is used for Xen 4.7 packages:
#
sysrc -f /boot/loader.conf hw.pci.mcfg=0
#
sysrc -f /boot/loader.conf if_tap_load="YES"
#
sysrc -f /boot/loader.conf xen_kernel="/boot/xen"
#
sysrc -f /boot/loader.conf xen_cmdline="dom0_mem=
8192M
dom0_max_vcpus=4
dom0pvh=1 console=com1,vga com1=115200,8n1 guest_loglvl=all loglvl=all"
For Xen versions 4.11 and higher, the following command should be used instead:
#
sysrc -f /boot/loader.conf if_tap_load="YES"
#
sysrc -f /boot/loader.conf xen_kernel="/boot/xen"
#
sysrc -f /boot/loader.conf xen_cmdline="dom0_mem=
8192M
dom0_max_vcpus=4
dom0=pvh console=com1,vga com1=115200,8n1 guest_loglvl=all loglvl=all"
Log files that Xen™ creates for the DomU VMs
are stored in /var/log/xen
. Please
be sure to check the contents of that directory if
experiencing issues.
Activate the xencommons service during system startup:
#
sysrc xencommons_enable=yes
These settings are enough to start a Dom0-enabled
system. However, it lacks network functionality for the
DomU machines. To fix that, define a bridged interface with
the main NIC of the system which the DomU VMs can use to
connect to the network. Replace
em0
with the host network
interface name.
#
sysrc cloned_interfaces="bridge0"
#
sysrc ifconfig_bridge0="addm
em0
SYNCDHCP"#
sysrc ifconfig_
em0
="up"
Restart the host to load the Xen™ kernel and start the Dom0.
#
reboot
After successfully booting the Xen™ kernel and logging
into the system again, the Xen™ management tool
xl
is used to show information about the
domains.
#
xl list
Name ID Mem VCPUs State Time(s) Domain-0 0 8192 4 r----- 962.0
The output confirms that the Dom0 (called
Domain-0
) has the ID 0
and is running. It also has the memory and virtual CPUs
that were defined in /boot/loader.conf
earlier. More information can be found in the Xen™
Documentation. DomU guest VMs can now be
created.
Unprivileged domains consist of a configuration file and
virtual or physical hard disks. Virtual disk storage for
the DomU can be files created by truncate(1) or ZFS
volumes as described in Section 19.4.2, “Creating and Destroying Volumes”.
In this example, a 20 GB volume is used. A VM is
created with the ZFS volume, a FreeBSD ISO image, 1 GB of
RAM and two virtual CPUs. The ISO installation file is
retrieved with fetch(1) and saved locally in a file
called freebsd.iso
.
#
fetch
ftp://ftp.freebsd.org/pub/FreeBSD/releases/ISO-IMAGES/
-o12.0
/FreeBSD-12.0
-RELEASE-amd64-bootonly.isofreebsd.iso
A ZFS volume of 20 GB called
xendisk0
is created to serve as the disk
space for the VM.
#
zfs create -V20G -o volmode=dev zroot/xendisk0
The new DomU guest VM is defined in a file. Some specific
definitions like name, keymap, and VNC connection details are
also defined. The following freebsd.cfg
contains a minimum DomU configuration for this example:
#
cat freebsd.cfg
builder = "hvm" name = "freebsd" memory = 1024 vcpus = 2 vif = [ 'mac=00:16:3E:74:34:32,bridge=bridge0' ] disk = [ '/dev/zvol/tank/xendisk0,raw,hda,rw', '/root/freebsd.iso,raw,hdc:cdrom,r' ] vnc = 1 vnclisten = "0.0.0.0" serial = "pty" usbdevice = "tablet"
These lines are explained in more detail:
This defines what kind of virtualization to use.
| |
Name of this virtual machine to distinguish it from others running on the same Dom0. Required. | |
Quantity of RAM in megabytes to make available to the VM. This amount is subtracted from the hypervisor's total available memory, not the memory of the Dom0. | |
Number of virtual CPUs available to the guest VM. For best performance, do not create guests with more virtual CPUs than the number of physical CPUs on the host. | |
Virtual network adapter. This is the bridge connected
to the network interface of the host. The
| |
Full path to the disk, file, or ZFS volume of the disk storage for this VM. Options and multiple disk definitions are separated by commas. | |
Defines the Boot medium from which the initial operating system is installed. In this example, it is the ISO imaged downloaded earlier. Consult the Xen™ documentation for other kinds of devices and options to set. | |
Options controlling VNC connectivity to the serial
console of the DomU. In order, these are: active VNC
support, define IP address on which to listen, device node
for the serial console, and the input method for precise
positioning of the mouse and other input methods.
|
After the file has been created with all the necessary
options, the DomU is created by passing it to xl
create
as a parameter.
#
xl create freebsd.cfg
Each time the Dom0 is restarted, the configuration file
must be passed to xl create
again to
re-create the DomU. By default, only the Dom0 is created
after a reboot, not the individual VMs. The VMs can
continue where they left off as they stored the operating
system on the virtual disk. The virtual machine
configuration can change over time (for example, when adding
more memory). The virtual machine configuration files must
be properly backed up and kept available to be able to
re-create the guest VM when needed.
The output of xl list
confirms that the
DomU has been created.
#
xl list
Name ID Mem VCPUs State Time(s) Domain-0 0 8192 4 r----- 1653.4 freebsd 1 1024 1 -b---- 663.9
To begin the installation of the base operating system,
start the VNC client, directing it to the main network address
of the host or to the IP address defined on the
vnclisten
line of
freebsd.cfg
. After the operating system
has been installed, shut down the DomU and disconnect the VNC
viewer. Edit freebsd.cfg
, removing the
line with the cdrom
definition or
commenting it out by inserting a #
character at the beginning of the line. To load this new
configuration, it is necessary to remove the old DomU with
xl destroy
, passing either the name or the
id as the parameter. Afterwards, recreate it using the
modified freebsd.cfg
.
#
xl destroy freebsd
#
xl create freebsd.cfg
The machine can then be accessed again using the VNC viewer. This time, it will boot from the virtual disk where the operating system has been installed and can be used as a virtual machine.
This section contains basic information in order to help troubleshoot issues found when using FreeBSD as a Xen™ host or guest.
Please note that the following troubleshooting tips are intended for Xen™ 4.11 or newer. If you are still using Xen™ 4.7 and having issues consider migrating to a newer version of Xen™.
In order to troubleshoot host boot issues you will
likely need a serial cable, or a debug USB cable. Verbose
Xen™ boot output can be obtained by adding options to the
xen_cmdline
option found in
loader.conf
. A couple of relevant
debug options are:
iommu=debug
: can be used to print
additional diagnostic information about the
iommu.
dom0=verbose
: can be used to
print additional diagnostic information about the
dom0 build process.
sync_console
: flag to force
synchronous console output. Useful for debugging to
avoid losing messages due to rate limiting.
Never use this option in production environments since
it can allow malicious guests to perform DoS attacks
against Xen™ using the console.
FreeBSD should also be booted in verbose mode in order to identify any issues. To activate verbose booting, run this command:
#
sysrc -f /boot/loader.conf boot_verbose="YES"
If none of these options help solving the problem,
please send the serial boot log to
<freebsd-xen@FreeBSD.org>
and
<xen-devel@lists.xenproject.org>
for further analysis.
Issues can also arise when creating guests, the following attempts to provide some help for those trying to diagnose guest creation issues.
The most common cause of guest creation failures is the
xl
command spitting some error and
exiting with a return code different than 0. If the error
provided is not enough to help identify the issue, more
verbose output can also be obtained from
xl
by using the v
option repeatedly.
#
xl -vvv create freebsd.cfg
Parsing config from freebsd.cfg libxl: debug: libxl_create.c:1693:do_domain_create: Domain 0:ao 0x800d750a0: create: how=0x0 callback=0x0 poller=0x800d6f0f0 libxl: debug: libxl_device.c:397:libxl__device_disk_set_backend: Disk vdev=xvda spec.backend=unknown libxl: debug: libxl_device.c:432:libxl__device_disk_set_backend: Disk vdev=xvda, using backend phy libxl: debug: libxl_create.c:1018:initiate_domain_create: Domain 1:running bootloader libxl: debug: libxl_bootloader.c:328:libxl__bootloader_run: Domain 1:not a PV/PVH domain, skipping bootloader libxl: debug: libxl_event.c:689:libxl__ev_xswatch_deregister: watch w=0x800d96b98: deregister unregistered domainbuilder: detail: xc_dom_allocate: cmdline="", features="" domainbuilder: detail: xc_dom_kernel_file: filename="/usr/local/lib/xen/boot/hvmloader" domainbuilder: detail: xc_dom_malloc_filemap : 326 kB libxl: debug: libxl_dom.c:988:libxl__load_hvm_firmware_module: Loading BIOS: /usr/local/share/seabios/bios.bin ...
If the verbose output does not help diagnose the issue
there are also QEMU and Xen™ toolstack logs in
/var/log/xen
. Note that the name of
the domain is appended to the log name, so if the domain
is named freebsd
you should find a
/var/log/xen/xl-freebsd.log
and likely
a /var/log/xen/qemu-dm-freebsd.log
.
Both log files can contain useful information for debugging.
If none of this helps solve the issue, please send the
description of the issue you are facing and as much
information as possible to
<freebsd-xen@FreeBSD.org>
and
<xen-devel@lists.xenproject.org>
in order to
get help.
FreeBSD is a distributed project with users and contributors located all over the world. As such, FreeBSD supports localization into many languages, allowing users to view, input, or process data in non-English languages. One can choose from most of the major languages, including, but not limited to: Chinese, German, Japanese, Korean, French, Russian, and Vietnamese.
The term internationalization has been shortened to
i18n, which represents the number of letters
between the first and the last letters of
internationalization
.
L10n uses the same naming scheme, but from
localization
. The
i18n/L10n methods,
protocols, and applications allow users to use languages of
their choice.
This chapter discusses the internationalization and localization features of FreeBSD. After reading this chapter, you will know:
How locale names are constructed.
How to set the locale for a login shell.
How to configure the console for non-English languages.
How to configure Xorg for different languages.
How to find i18n-compliant applications.
Where to find more information for configuring specific languages.
Before reading this chapter, you should:
Know how to install additional third-party applications.
Localization settings are based on three components: the language code, country code, and encoding. Locale names are constructed from these parts as follows:
LanguageCode
_CountryCode
.Encoding
The LanguageCode
and
CountryCode
are used to determine
the country and the specific language variation. Table 22.1, “Common Language and Country Codes” provides some examples of
LanguageCode
_CountryCode
:
LanguageCode_Country Code | Description |
---|---|
en_US | English, United States |
ru_RU | Russian, Russia |
zh_TW | Traditional Chinese, Taiwan |
A complete listing of available locales can be found by typing:
%
locale -a | more
To determine the current locale setting:
%
locale
Language specific character sets, such as ISO8859-1, ISO8859-15, KOI8-R, and CP437, are described in multibyte(3). The active list of character sets can be found at the IANA Registry.
Some languages, such as Chinese or Japanese, cannot be represented using ASCII characters and require an extended language encoding using either wide or multibyte characters. Examples of wide or multibyte encodings include EUC and Big5. Older applications may mistake these encodings for control characters while newer applications usually recognize these characters. Depending on the implementation, users may be required to compile an application with wide or multibyte character support, or to configure it correctly.
FreeBSD uses Xorg-compatible locale encodings.
The rest of this section describes the various methods for configuring the locale on a FreeBSD system. The next section will discuss the considerations for finding and compiling applications with i18n support.
Locale settings are configured either in a user's
~/.login_conf
or in the startup file of the user's shell:
~/.profile
,
~/.bashrc
, or
~/.cshrc
.
Two environment variables should be set:
In addition to the user's shell configuration, these variables should also be set for specific application configuration and Xorg configuration.
Two methods are available for making the needed variable assignments: the login class method, which is the recommended method, and the startup file method. The next two sections demonstrate how to use both methods.
This first method is the recommended method as it assigns the required environment variables for locale name and MIME character sets for every possible shell. This setup can either be performed by each user or it can be configured for all users by the superuser.
This minimal example sets both variables for Latin-1
encoding in the .login_conf
of an
individual user's home directory:
me:\ :charset=ISO-8859-1:\ :lang=de_DE.ISO8859-1:
Here is an example of a user's
~/.login_conf
that sets the variables
for Traditional Chinese in BIG-5 encoding. More variables
are needed because some applications do not correctly
respect locale variables for Chinese, Japanese, and
Korean:
#Users who do not wish to use monetary units or time formats #of Taiwan can manually change each variable me:\ :lang=zh_TW.Big5:\ :setenv=LC_ALL=zh_TW.Big5,LC_COLLATE=zh_TW.Big5,LC_CTYPE=zh_TW.Big5,LC_MESSAGES=zh_TW.Big5,LC_MONETARY=zh_TW.Big5,LC_NUMERIC=zh_TW.Big5,LC_TIME=zh_TW.Big5:\ :charset=big5:\ :xmodifiers="@im=gcin": #Set gcin as the XIM Input Server
Alternately, the superuser can configure all users of
the system for localization. The following variables in
/etc/login.conf
are used to set the
locale and MIME character set:
language_name
|Account Type Description
:\ :charset=MIME_charset
:\ :lang=locale_name
:\ :tc=default:
So, the previous Latin-1 example would look like this:
german|German Users Accounts:\ :charset=ISO-8859-1:\ :lang=de_DE.ISO8859-1:\ :tc=default:
See login.conf(5) for more details about these
variables. Note that it already contains pre-defined
russian
class.
Whenever /etc/login.conf
is edited,
remember to execute the following command to update the
capability database:
#
cap_mkdb /etc/login.conf
In addition to manually editing
/etc/login.conf
, several utilities
are available for setting the locale for newly created
users.
When using vipw
to add new users,
specify the language
to set the
locale:
user:password:1111:11:language
:0:0:User Name:/home/user:/bin/sh
When using adduser
to add new
users, the default language can be pre-configured for all
new users or specified for an individual user.
If all new users use the same language, set
defaultclass=
in
language
/etc/adduser.conf
.
To override this setting when creating a user, either input the required locale at this prompt:
Enter login class: default []:
or specify the locale to set when invoking
adduser
:
#
adduser -class
language
If pw
is used to add new users,
specify the locale as follows:
#
pw useradd
user_name
-Llanguage
To change the login class of an existing user,
chpass
can be used. Invoke it as
superuser and provide the username to edit as the
argument.
#
chpass
user_name
This second method is not recommended as each shell
that is used requires manual configuration, where each
shell has a different configuration file and differing
syntax. As an example, to set the German language for the
sh
shell, these lines could be added to
~/.profile
to set the shell for that
user only. These lines could also be added to
/etc/profile
or
/usr/share/skel/dot.profile
to set
that shell for all users:
LANG
=de_DE.ISO8859-1; exportLANG
MM_CHARSET
=ISO-8859-1; exportMM_CHARSET
However, the name of the configuration file and the
syntax used differs for the csh
shell.
These are the equivalent settings for
~/.csh.login
,
/etc/csh.login
, or
/usr/share/skel/dot.login
:
setenvLANG
de_DE.ISO8859-1 setenvMM_CHARSET
ISO-8859-1
To complicate matters, the syntax needed to configure
Xorg in
~/.xinitrc
also depends upon the
shell. The first example is for the sh
shell and the second is for the csh
shell:
LANG
=de_DE.ISO8859-1; exportLANG
setenv LANG
de_DE.ISO8859-1
Several localized fonts are available for the console. To
see a listing of available fonts, type
ls /usr/share/syscons/fonts
. To configure
the console font, specify the
font_name
,
without the .fnt
suffix, in
/etc/rc.conf
:
font8x16=font_name
font8x14=font_name
font8x8=font_name
The keymap and screenmap can be set by adding the
following to /etc/rc.conf
:
scrnmap=screenmap_name
keymap=keymap_name
keychange="fkey_number sequence
"
To see the list of available screenmaps, type
ls /usr/share/syscons/scrnmaps
. Do not
include the .scm
suffix when specifying
screenmap_name
. A screenmap with a
corresponding mapped font is usually needed as a workaround
for expanding bit 8 to bit 9 on a VGA adapter's font character
matrix so that letters are moved out of the pseudographics
area if the screen font uses a bit 8 column.
To see the list of available keymaps, type
ls /usr/share/syscons/keymaps
. When
specifying the keymap_name
, do not
include the .kbd
suffix. To test
keymaps without rebooting,
use kbdmap(1).
The keychange
entry is usually needed
to program function keys to match the selected terminal type
because function key sequences cannot be defined in the
keymap.
Next, set the correct console terminal type in
/etc/ttys
for all virtual terminal
entries. Table 22.2, “Defined Terminal Types for Character Sets” summarizes the
available terminal types.:
Character Set | Terminal Type |
---|---|
ISO8859-1 or ISO8859-15 | cons25l1 |
ISO8859-2 | cons25l2 |
ISO8859-7 | cons25l7 |
KOI8-R | cons25r |
KOI8-U | cons25u |
CP437 (VGA default) | cons25 |
US-ASCII | cons25w |
For languages with wide or multibyte characters, install a
console for that language from the FreeBSD Ports Collection. The
available ports are summarized in Table 22.3, “Available Console from Ports Collection”. Once installed, refer to the
port's pkg-message
or man pages for
configuration and usage instructions.
Language | Port Location |
---|---|
Traditional Chinese (BIG-5) | chinese/big5con |
Chinese/Japanese/Korean | chinese/cce |
Chinese/Japanese/Korean | chinese/zhcon |
Japanese | chinese/kon2 |
Japanese | japanese/kon2-14dot |
Japanese | japanese/kon2-16dot |
If moused is enabled in
/etc/rc.conf
, additional configuration
may be required. By default, the mouse cursor of the
syscons(4) driver occupies the
0xd0
-0xd3
range in the
character set. If the language uses this range, move the
cursor's range by adding the
following line to /etc/rc.conf
:
mousechar_start=3
Chapter 5, The X Window System describes how to install and
configure Xorg. When configuring
Xorg for localization, additional
fonts and input methods are available from the FreeBSD Ports
Collection. Application specific i18n
settings such as fonts and menus can be tuned in
~/.Xresources
and should allow users to
view their selected language in graphical application
menus.
The X Input Method (XIM) protocol is an Xorg standard for inputting non-English characters. Table 22.4, “Available Input Methods” summarizes the input method applications which are available in the FreeBSD Ports Collection. Additional Fcitx and Uim applications are also available.
Language | Input Method |
---|---|
Chinese | chinese/gcin |
Chinese | chinese/ibus-chewing |
Chinese | chinese/ibus-pinyin |
Chinese | chinese/oxim |
Chinese | chinese/scim-fcitx |
Chinese | chinese/scim-pinyin |
Chinese | chinese/scim-tables |
Japanese | japanese/ibus-anthy |
Japanese | japanese/ibus-mozc |
Japanese | japanese/ibus-skk |
Japanese | japanese/im-ja |
Japanese | japanese/kinput2 |
Japanese | japanese/scim-anthy |
Japanese | japanese/scim-canna |
Japanese | japanese/scim-honoka |
Japanese | japanese/scim-honoka-plugin-romkan |
Japanese | japanese/scim-honoka-plugin-wnn |
Japanese | japanese/scim-prime |
Japanese | japanese/scim-skk |
Japanese | japanese/scim-tables |
Japanese | japanese/scim-tomoe |
Japanese | japanese/scim-uim |
Japanese | japanese/skkinput |
Japanese | japanese/skkinput3 |
Japanese | japanese/uim-anthy |
Korean | korean/ibus-hangul |
Korean | korean/imhangul |
Korean | korean/nabi |
Korean | korean/scim-hangul |
Korean | korean/scim-tables |
Vietnamese | vietnamese/xvnkb |
Vietnamese | vietnamese/x-unikey |
i18n applications are programmed using i18n kits under libraries. These allow developers to write a simple file and translate displayed menus and texts to each language.
The FreeBSD
Ports Collection contains many applications with
built-in support for wide or multibyte characters for several
languages. Such applications include i18n
in
their names for easy identification. However, they do not
always support the language needed.
Some applications can be compiled with the specific
charset. This is usually done in the port's
Makefile
or by passing a value to
configure. Refer to the
i18n documentation in the respective FreeBSD
port's source for more information on how to determine the
needed configure value or the port's
Makefile
to determine which compile options
to use when building the port.
This section provides configuration examples for localizing a FreeBSD system for the Russian language. It then provides some additional resources for localizing other languages.
This section shows the specific settings needed to localize a FreeBSD system for the Russian language. Refer to Using Localization for a more complete description of each type of setting.
To set this locale for the login shell, add the following
lines to each user's
~/.login_conf
:
me:My Account:\ :charset=KOI8-R:\ :lang=ru_RU.KOI8-R:
To configure the console, add the following lines to
/etc/rc.conf
:
keymap="ru.koi8-r" scrnmap="koi8-r2cp866" font8x16="cp866b-8x16" font8x14="cp866-8x14" font8x8="cp866-8x8" mousechar_start=3
For each ttyv
entry in
/etc/ttys
, use
cons25r
as the terminal type.
To configure printing, a special output filter is needed
to convert from KOI8-R to CP866 since most printers with
Russian characters come with hardware code page CP866. FreeBSD
includes a default filter for this purpose,
/usr/libexec/lpr/ru/koi2alt
. To use this
filter, add this entry to
/etc/printcap
:
lp|Russian local line printer:\ :sh:of=/usr/libexec/lpr/ru/koi2alt:\ :lp=/dev/lpt0:sd=/var/spool/output/lpd:lf=/var/log/lpd-errs:
Refer to printcap(5) for a more detailed explanation.
To configure support for Russian filenames in mounted
MS-DOS® file systems, include -L
and the
locale name when adding an entry to
/etc/fstab
:
/dev/ad0s2 /dos/c msdos rw,-Lru_RU.KOI8-R 0 0
Refer to mount_msdosfs(8) for more details.
To configure Russian fonts for
Xorg, install the
x11-fonts/xorg-fonts-cyrillic package.
Then, check the "Files"
section in
/etc/X11/xorg.conf
. The following line
must be added before any other
FontPath
entries:
FontPath "/usr/local/lib/X11/fonts/cyrillic"
Additional Cyrillic fonts are available in the Ports Collection.
To activate a Russian keyboard, add the following to the
"Keyboard"
section of
/etc/xorg.conf
:
Option "XkbLayout" "us,ru" Option "XkbOptions" "grp:toggle"
Make sure that XkbDisable
is
commented out in that file.
For grp:toggle
use
Right Alt, for
grp:ctrl_shift_toggle
use Ctrl+Shift.
For grp:caps_toggle
use
CapsLock. The old
CapsLock function is still available in LAT
mode only using Shift+CapsLock.
grp:caps_toggle
does not work in
Xorg for some unknown
reason.
If the keyboard has “Windows®” keys, and
some non-alphabetical keys are mapped incorrectly, add the
following line to /etc/xorg.conf
:
Option "XkbVariant" ",winkeys"
The Russian XKB keyboard may not work with
non-localized applications. Minimally localized
applications should call a XtSetLanguageProc
(NULL, NULL, NULL);
function early in the
program.
See http://koi8.pp.ru/xwin.html
for more instructions on localizing
Xorg applications. For more
general information about KOI8-R encoding, refer to http://koi8.pp.ru/
.
This section lists some additional resources for configuring other locales.
The FreeBSD-Taiwan Project has a Chinese HOWTO for FreeBSD
at http://netlab.cse.yzu.edu.tw/~statue/freebsd/zh-tut/
.
A complete article on Greek support in FreeBSD is available here, in Greek only, as part of the official FreeBSD Greek documentation.
For Japanese, refer to http://www.jp.FreeBSD.org/
,
and for Korean, refer to http://www.kr.FreeBSD.org/
.
Some FreeBSD contributors have translated parts of the
FreeBSD documentation to other languages. They are
available through links on the FreeBSD web
site or in
/usr/share/doc
.
FreeBSD is under constant development between releases. Some people prefer to use the officially released versions, while others prefer to keep in sync with the latest developments. However, even official releases are often updated with security and other critical fixes. Regardless of the version used, FreeBSD provides all the necessary tools to keep the system updated, and allows for easy upgrades between versions. This chapter describes how to track the development system and the basic tools for keeping a FreeBSD system up-to-date.
After reading this chapter, you will know:
How to keep a FreeBSD system up-to-date with freebsd-update or Subversion.
How to compare the state of an installed system against a known pristine copy.
How to keep the installed documentation up-to-date with Subversion or documentation ports.
The difference between the two development branches: FreeBSD-STABLE and FreeBSD-CURRENT.
How to rebuild and reinstall the entire base system.
Before reading this chapter, you should:
Properly set up the network connection (Chapter 31, Advanced Networking).
Know how to install additional third-party software (Chapter 4, Installing Applications: Packages and Ports).
Throughout this chapter, svnlite
is used to
obtain and update FreeBSD sources. Optionally, the
devel/subversion port or
package may be used.
Applying security patches in a timely manner and upgrading
to a newer release of an operating system are important aspects
of ongoing system administration. FreeBSD includes a utility
called freebsd-update
which can be used to
perform both these tasks.
This utility supports binary security and errata updates to
FreeBSD, without the need to manually compile and install the patch
or a new kernel. Binary updates are available for all
architectures and releases currently supported by the security
team. The list of supported releases and their estimated
end-of-life dates are listed at https://www.FreeBSD.org/security/
.
This utility also supports operating system upgrades to
minor point releases as well as upgrades to another release
branch. Before upgrading to a new release, review its release
announcement as it contains important information pertinent to
the release. Release announcements are available from https://www.FreeBSD.org/releases/
.
If a crontab
utilizing the features of
freebsd-update(8) exists, it must be disabled before
upgrading the operating system.
This section describes the configuration file used by
freebsd-update
, demonstrates how to apply a
security patch and how to upgrade to a minor or major operating
system release, and discusses some of the considerations when
upgrading the operating system.
The default configuration file for
freebsd-update
works as-is. Some users may
wish to tweak the default configuration in
/etc/freebsd-update.conf
, allowing
better control of the process. The comments in this file
explain the available options, but the following may require a
bit more explanation:
# Components of the base system which should be kept updated. Components world kernel
This parameter controls which parts of FreeBSD will be kept
up-to-date. The default is to update the entire base system
and the kernel. Individual components can instead be
specified, such as src/base
or
src/sys
. However, the best option is to
leave this at the default as changing it to include specific
items requires every needed item to be listed. Over time,
this could have disastrous consequences as source code and
binaries may become out of sync.
# Paths which start with anything matching an entry in an IgnorePaths # statement will be ignored. IgnorePaths /boot/kernel/linker.hints
To leave specified directories, such as
/bin
or /sbin
,
untouched during the update process, add their paths to this
statement. This option may be used to prevent
freebsd-update
from overwriting local
modifications.
# Paths which start with anything matching an entry in an UpdateIfUnmodified # statement will only be updated if the contents of the file have not been # modified by the user (unless changes are merged; see below). UpdateIfUnmodified /etc/ /var/ /root/ /.cshrc /.profile
This option will only update unmodified configuration
files in the specified directories. Any changes made by the
user will prevent the automatic updating of these files.
There is another option,
KeepModifiedMetadata
, which will instruct
freebsd-update
to save the changes during
the merge.
# When upgrading to a new FreeBSD release, files which match MergeChanges # will have any local changes merged into the version from the new release. MergeChanges /etc/ /var/named/etc/ /boot/device.hints
List of directories with configuration files that
freebsd-update
should attempt to merge.
The file merge process is a series of diff(1) patches
similar to mergemaster(8), but with fewer options.
Merges are either accepted, open an editor, or cause
freebsd-update
to abort. When in doubt,
backup /etc
and just accept the merges.
See mergemaster(8) for more information about
mergemaster
.
# Directory in which to store downloaded updates and temporary # files used by FreeBSD Update. # WorkDir /var/db/freebsd-update
This directory is where all patches and temporary files are placed. In cases where the user is doing a version upgrade, this location should have at least a gigabyte of disk space available.
# When upgrading between releases, should the list of Components be # read strictly (StrictComponents yes) or merely as a list of components # which *might* be installed of which FreeBSD Update should figure out # which actually are installed and upgrade those (StrictComponents no)? # StrictComponents no
When this option is set to yes
,
freebsd-update
will assume that the
Components
list is complete and will not
attempt to make changes outside of the list. Effectively,
freebsd-update
will attempt to update
every file which belongs to the Components
list.
The process of applying FreeBSD security patches has been
simplified, allowing an administrator to keep a system fully
patched using freebsd-update
. More
information about FreeBSD security advisories can be found in
Section 13.11, “FreeBSD Security Advisories”.
FreeBSD security patches may be downloaded and installed using the following commands. The first command will determine if any outstanding patches are available, and if so, will list the files that will be modifed if the patches are applied. The second command will apply the patches.
#
freebsd-update fetch
#
freebsd-update install
If the update applies any kernel patches, the system will need a reboot in order to boot into the patched kernel. If the patch was applied to any running binaries, the affected applications should be restarted so that the patched version of the binary is used.
The system can be configured to automatically check for
updates once every day by adding this entry to
/etc/crontab
:
@daily root freebsd-update cron
If patches exist, they will automatically be downloaded
but will not be applied. The root
user will be sent an
email so that the patches may be reviewed and manually
installed with
freebsd-update install
.
If anything goes wrong, freebsd-update
has the ability to roll back the last set of changes with the
following command:
#
freebsd-update rollback
Uninstalling updates... done.
Again, the system should be restarted if the kernel or any kernel modules were modified and any affected binaries should be restarted.
Only the GENERIC
kernel can be
automatically updated by freebsd-update
.
If a custom kernel is installed, it will have to be rebuilt
and reinstalled after freebsd-update
finishes installing the updates. The default kernel name
is GENERIC. The uname(1) command
may be used to verify its installation.
Always keep a copy of the GENERIC
kernel in /boot/GENERIC
. It will be
helpful in diagnosing a variety of problems and in
performing version upgrades. Refer to Section 23.2.3.1, “Custom Kernels with FreeBSD 9.X and Later” for
instructions on how to get a copy of the
GENERIC
kernel.
Unless the default configuration in
/etc/freebsd-update.conf
has been
changed, freebsd-update
will install the
updated kernel sources along with the rest of the updates.
Rebuilding and reinstalling a new custom kernel can then be
performed in the usual way.
The updates distributed by
freebsd-update
do not always involve the
kernel. It is not necessary to rebuild a custom kernel if the
kernel sources have not been modified by
freebsd-update install
. However,
freebsd-update
will always update
/usr/src/sys/conf/newvers.sh
. The
current patch level, as indicated by the -p
number reported by uname -r
, is obtained
from this file. Rebuilding a custom kernel, even if nothing
else changed, allows uname
to accurately
report the current patch level of the system. This is
particularly helpful when maintaining multiple systems, as it
allows for a quick assessment of the updates installed in each
one.
Upgrades from one minor version of FreeBSD to another, like
from FreeBSD 9.0 to FreeBSD 9.1, are called
minor version upgrades.
Major version upgrades occur when FreeBSD
is upgraded from one major version to another, like from
FreeBSD 9.X to FreeBSD 10.X. Both types of upgrades can
be performed by providing freebsd-update
with a release version target.
If the system is running a custom kernel, make sure that
a copy of the GENERIC
kernel exists in
/boot/GENERIC
before starting the
upgrade. Refer to Section 23.2.3.1, “Custom Kernels with FreeBSD 9.X and Later” for
instructions on how to get a copy of the
GENERIC
kernel.
The following command, when run on a FreeBSD 9.0 system, will upgrade it to FreeBSD 9.1:
#
freebsd-update -r 9.1-RELEASE upgrade
After the command has been received,
freebsd-update
will evaluate the
configuration file and current system in an attempt to gather
the information necessary to perform the upgrade. A screen
listing will display which components have and have not been
detected. For example:
Looking up update.FreeBSD.org mirrors... 1 mirrors found.
Fetching metadata signature for 9.0-RELEASE from update1.FreeBSD.org... done.
Fetching metadata index... done.
Inspecting system... done.
The following components of FreeBSD seem to be installed:
kernel/smp src/base src/bin src/contrib src/crypto src/etc src/games
src/gnu src/include src/krb5 src/lib src/libexec src/release src/rescue
src/sbin src/secure src/share src/sys src/tools src/ubin src/usbin
world/base world/info world/lib32 world/manpages
The following components of FreeBSD do not seem to be installed:
kernel/generic world/catpages world/dict world/doc world/games
world/proflibs
Does this look reasonable (y/n)? y
At this point, freebsd-update
will
attempt to download all files required for the upgrade. In
some cases, the user may be prompted with questions regarding
what to install or how to proceed.
When using a custom kernel, the above step will produce a warning similar to the following:
WARNING: This system is running a "MYKERNEL
" kernel, which is not a
kernel configuration distributed as part of FreeBSD 9.0-RELEASE.
This kernel will not be updated: you MUST update the kernel manually
before running "/usr/sbin/freebsd-update install"
This warning may be safely ignored at this point. The
updated GENERIC
kernel will be used as an
intermediate step in the upgrade process.
Once all the patches have been downloaded to the local
system, they will be applied. This process may take a while,
depending on the speed and workload of the machine.
Configuration files will then be merged. The merging process
requires some user intervention as a file may be merged or an
editor may appear on screen for a manual merge. The results
of every successful merge will be shown to the user as the
process continues. A failed or ignored merge will cause the
process to abort. Users may wish to make a backup of
/etc
and manually merge important files,
such as master.passwd
or
group
at a later time.
The system is not being altered yet as all patching and merging is happening in another directory. Once all patches have been applied successfully, all configuration files have been merged and it seems the process will go smoothly, the changes can be committed to disk by the user using the following command:
#
freebsd-update install
The kernel and kernel modules will be patched first. If
the system is running with a custom kernel, use
nextboot(8) to set the kernel for the next boot to the
updated /boot/GENERIC
:
#
nextboot -k GENERIC
Before rebooting with the GENERIC
kernel, make sure it contains all the drivers required for
the system to boot properly and connect to the network, if
the machine being updated is accessed remotely. In
particular, if the running custom kernel contains built-in
functionality usually provided by kernel modules, make sure
to temporarily load these modules into the
GENERIC
kernel using the
/boot/loader.conf
facility. It is
recommended to disable non-essential services as well as any
disk and network mounts until the upgrade process is
complete.
The machine should now be restarted with the updated kernel:
#
shutdown -r now
Once the system has come back online, restart
freebsd-update
using the following command.
Since the state of the process has been saved,
freebsd-update
will not start from the
beginning, but will instead move on to the next phase and
remove all old shared libraries and object files.
#
freebsd-update install
Depending upon whether any library version numbers were bumped, there may only be two install phases instead of three.
The upgrade is now complete. If this was a major version upgrade, reinstall all ports and packages as described in Section 23.2.3.2, “Upgrading Packages After a Major Version Upgrade”.
Before using freebsd-update
, ensure
that a copy of the GENERIC
kernel
exists in /boot/GENERIC
. If a custom
kernel has only been built once, the kernel in
/boot/kernel.old
is the
GENERIC
kernel. Simply rename this
directory to /boot/kernel
.
If a custom kernel has been built more than once or if
it is unknown how many times the custom kernel has been
built, obtain a copy of the GENERIC
kernel that matches the current version of the operating
system. If physical access to the system is available, a
copy of the GENERIC
kernel can be
installed from the installation media:
#
mount /cdrom
#
cd /cdrom/usr/freebsd-dist
#
tar -C/ -xvf kernel.txz boot/kernel/kernel
Alternately, the GENERIC
kernel may
be rebuilt and installed from source:
#
cd /usr/src
#
make kernel __MAKE_CONF=/dev/null SRCCONF=/dev/null
For this kernel to be identified as the
GENERIC
kernel by
freebsd-update
, the
GENERIC
configuration file must not
have been modified in any way. It is also suggested that
the kernel is built without any other special
options.
Rebooting into the GENERIC
kernel
is not required as freebsd-update
only
needs /boot/GENERIC
to exist.
Generally, installed applications will continue to work
without problems after minor version upgrades. Major
versions use different Application Binary Interfaces
(ABIs), which will break most
third-party applications. After a major version upgrade,
all installed packages and ports need to be upgraded.
Packages can be upgraded using pkg
upgrade
. To upgrade installed ports, use a
utility such as
ports-mgmt/portmaster.
A forced upgrade of all installed packages will replace the packages with fresh versions from the repository even if the version number has not increased. This is required because of the ABI version change when upgrading between major versions of FreeBSD. The forced upgrade can be accomplished by performing:
#
pkg-static upgrade -f
A rebuild of all installed applications can be accomplished with this command:
#
portmaster -af
This command will display the configuration screens for
each application that has configurable options and wait for
the user to interact with those screens. To prevent this
behavior, and use only the default options, include
-G
in the above command.
Once the software upgrades are complete, finish the
upgrade process with a final call to
freebsd-update
in order to tie up all the
loose ends in the upgrade process:
#
freebsd-update install
If the GENERIC
kernel was
temporarily used, this is the time to build and install a
new custom kernel using the instructions in Chapter 8, Configuring the FreeBSD Kernel.
Reboot the machine into the new FreeBSD version. The upgrade process is now complete.
The state of the installed FreeBSD version against a known
good copy can be tested using
freebsd-update IDS
. This command evaluates
the current version of system utilities, libraries, and
configuration files and can be used as a built-in Intrusion
Detection System (IDS).
This command is not a replacement for a real
IDS such as
security/snort. As
freebsd-update
stores data on disk, the
possibility of tampering is evident. While this possibility
may be reduced using kern.securelevel
and
by storing the freebsd-update
data on a
read-only file system when not in use, a better solution
would be to compare the system against a secure disk, such
as a DVD or securely stored external
USB disk device. An alternative method
for providing IDS functionality using a
built-in utility is described in Section 13.2.6, “Binary Verification”
To begin the comparison, specify the output file to save the results to:
#
freebsd-update IDS >> outfile.ids
The system will now be inspected and a lengthy listing of files, along with the SHA256 hash values for both the known value in the release and the current installation, will be sent to the specified output file.
The entries in the listing are extremely long, but the output format may be easily parsed. For instance, to obtain a list of all files which differ from those in the release, issue the following command:
#
cat outfile.ids | awk '{ print $1 }' | more
/etc/master.passwd /etc/motd /etc/passwd /etc/pf.conf
This sample output has been truncated as many more files
exist. Some files have natural modifications. For example,
/etc/passwd
will be modified if users
have been added to the system. Kernel modules may differ as
freebsd-update
may have updated them. To
exclude specific files or directories, add them to the
IDSIgnorePaths
option in
/etc/freebsd-update.conf
.
Documentation is an integral part of the FreeBSD operating system. While an up-to-date version of the FreeBSD documentation is always available on the FreeBSD web site (https://www.freebsd.org/doc/), it can be handy to have an up-to-date, local copy of the FreeBSD website, handbooks, FAQ, and articles.
This section describes how to use either source or the FreeBSD Ports Collection to keep a local copy of the FreeBSD documentation up-to-date.
For information on editing and submitting corrections to the documentation, refer to the FreeBSD Documentation Project Primer for New Contributors (https://www.freebsd.org/doc/en_US.ISO8859-1/books/fdp-primer/).
Rebuilding the FreeBSD documentation from source requires a collection of tools which are not part of the FreeBSD base system. The required tools can be installed from the textproc/docproj package or port developed by the FreeBSD Documentation Project.
Once installed, use svnlite to fetch a clean copy of the documentation source:
#
svnlite checkout https://svn.FreeBSD.org/doc/head /usr/doc
The initial download of the documentation sources may take a while. Let it run until it completes.
Future updates of the documentation sources may be fetched by running:
#
svnlite update /usr/doc
Once an up-to-date snapshot of the documentation sources
has been fetched to /usr/doc
, everything
is ready for an update of the installed documentation.
A full update of all available languages may be performed by typing:
#
cd /usr/doc
#
make install clean
If an update of only a specific language is desired,
make
can be invoked in a language-specific
subdirectory of
/usr/doc
:
#
cd /usr/doc/en_US.ISO8859-1
#
make install clean
An alternative way of updating the documentation is to run
this command from /usr/doc
or the desired
language-specific subdirectory:
#
make update
The output formats that will be installed may be specified
by setting FORMATS
:
#
cd /usr/doc
#
make FORMATS='html html-split' install clean
Several options are available to ease the process of
updating only parts of the documentation, or the build of
specific translations. These options can be set either as
system-wide options in /etc/make.conf
, or
as command-line options passed to
make
.
The options include:
DOC_LANG
The list of languages and encodings to build and
install, such as en_US.ISO8859-1
for
English documentation.
FORMATS
A single format or a list of output formats to be
built. Currently, html
,
html-split
, txt
,
ps
, and pdf
are
supported.
DOCDIR
Where to install the documentation. It defaults to
/usr/share/doc
.
For more make
variables supported as
system-wide options in FreeBSD, refer to
make.conf(5).
The previous section presented a method for updating the FreeBSD documentation from sources. This section describes an alternative method which uses the Ports Collection and makes it possible to:
Install pre-built packages of the documentation, without having to locally build anything or install the documentation toolchain.
Build the documentation sources through the ports framework, making the checkout and build steps a bit easier.
This method of updating the FreeBSD documentation is
supported by a set of documentation ports and packages which
are updated by the Documentation Engineering Team <doceng@FreeBSD.org>
on a monthly basis. These are
listed in the FreeBSD Ports Collection, under the docs
category (http://www.freshports.org/docs/).
Organization of the documentation ports is as follows:
The misc/freebsd-doc-en package or port installs all of the English documentation.
The misc/freebsd-doc-all meta-package or port installs all documentation in all available languages.
There is a package and port for each translation, such as misc/freebsd-doc-hu for the Hungarian documentation.
When binary packages are used, the FreeBSD documentation will be installed in all available formats for the given language. For example, the following command will install the latest package of the Hungarian documentation:
#
pkg install hu-freebsd-doc
Packages use a format that differs from the
corresponding port's name:
,
where lang
-freebsd-doclang
is the short format of
the language code, such as hu
for
Hungarian, or zh_cn
for Simplified
Chinese.
To specify the format of the documentation, build the port instead of installing the package. For example, to build and install the English documentation:
#
cd /usr/ports/misc/freebsd-doc-en
#
make install clean
The port provides a configuration menu where the format to
build and install can be specified. By default, split
HTML, similar to the format used on http://www.FreeBSD.org
,
and PDF are selected.
Alternately, several make
options can
be specified when building a documentation port,
including:
WITH_HTML
Builds the HTML format with a single HTML file per
document. The formatted documentation is saved to a
file called article.html
, or
book.html
.
WITH_PDF
The formatted documentation is saved to a file
called article.pdf
or
book.pdf
.
DOCBASE
Specifies where to install the documentation. It
defaults to
/usr/local/share/doc/freebsd
.
This example uses variables to install the Hungarian documentation as a PDF in the specified directory:
#
cd /usr/ports/misc/freebsd-doc-hu
#
make -DWITH_PDF DOCBASE=share/doc/freebsd/hu install clean
Documentation packages or ports can be updated using the instructions in Chapter 4, Installing Applications: Packages and Ports. For example, the following command updates the installed Hungarian documentation using ports-mgmt/portmaster by using packages only:
#
portmaster -PP hu-freebsd-doc
FreeBSD has two development branches: FreeBSD-CURRENT and FreeBSD-STABLE.
This section provides an explanation of each branch and its intended audience, as well as how to keep a system up-to-date with each respective branch.
FreeBSD-CURRENT is the “bleeding edge” of FreeBSD development and FreeBSD-CURRENT users are expected to have a high degree of technical skill. Less technical users who wish to track a development branch should track FreeBSD-STABLE instead.
FreeBSD-CURRENT is the very latest source code for FreeBSD and includes works in progress, experimental changes, and transitional mechanisms that might or might not be present in the next official release. While many FreeBSD developers compile the FreeBSD-CURRENT source code daily, there are short periods of time when the source may not be buildable. These problems are resolved as quickly as possible, but whether or not FreeBSD-CURRENT brings disaster or new functionality can be a matter of when the source code was synced.
FreeBSD-CURRENT is made available for three primary interest groups:
Members of the FreeBSD community who are actively working on some part of the source tree.
Members of the FreeBSD community who are active testers. They are willing to spend time solving problems, making topical suggestions on changes and the general direction of FreeBSD, and submitting patches.
Users who wish to keep an eye on things, use the current source for reference purposes, or make the occasional comment or code contribution.
FreeBSD-CURRENT should not be considered a fast-track to getting new features before the next release as pre-release features are not yet fully tested and most likely contain bugs. It is not a quick way of getting bug fixes as any given commit is just as likely to introduce new bugs as to fix existing ones. FreeBSD-CURRENT is not in any way “officially supported”.
To track FreeBSD-CURRENT:
Join the freebsd-current and the svn-src-head lists. This is essential in order to see the comments that people are making about the current state of the system and to receive important bulletins about the current state of FreeBSD-CURRENT.
The svn-src-head list records the commit log entry for each change as it is made, along with any pertinent information on possible side effects.
To join these lists, go to http://lists.FreeBSD.org/mailman/listinfo, click on the list to subscribe to, and follow the instructions. In order to track changes to the whole source tree, not just the changes to FreeBSD-CURRENT, subscribe to the svn-src-all list.
Synchronize with the FreeBSD-CURRENT sources. Typically,
svnlite is used to check out the
-CURRENT code from the head
branch of
one of the Subversion mirror sites listed in
Section A.3.6, “Subversion Mirror
Sites”.
Due to the size of the repository, some users choose to only synchronize the sections of source that interest them or which they are contributing patches to. However, users that plan to compile the operating system from source must download all of FreeBSD-CURRENT, not just selected portions.
Before compiling FreeBSD-CURRENT
, read /usr/src/Makefile
very carefully and follow the instructions in
Section 23.5, “Updating FreeBSD from Source”.
Read the FreeBSD-CURRENT mailing list and
/usr/src/UPDATING
to stay
up-to-date on other bootstrapping procedures that
sometimes become necessary on the road to the next
release.
Be active! FreeBSD-CURRENT users are encouraged to submit their suggestions for enhancements or bug fixes. Suggestions with accompanying code are always welcome.
FreeBSD-STABLE is the development branch from which major releases are made. Changes go into this branch at a slower pace and with the general assumption that they have first been tested in FreeBSD-CURRENT. This is still a development branch and, at any given time, the sources for FreeBSD-STABLE may or may not be suitable for general use. It is simply another engineering development track, not a resource for end-users. Users who do not have the resources to perform testing should instead run the most recent release of FreeBSD.
Those interested in tracking or contributing to the FreeBSD development process, especially as it relates to the next release of FreeBSD, should consider following FreeBSD-STABLE.
While the FreeBSD-STABLE branch should compile and run at all times, this cannot be guaranteed. Since more people run FreeBSD-STABLE than FreeBSD-CURRENT, it is inevitable that bugs and corner cases will sometimes be found in FreeBSD-STABLE that were not apparent in FreeBSD-CURRENT. For this reason, one should not blindly track FreeBSD-STABLE. It is particularly important not to update any production servers to FreeBSD-STABLE without thoroughly testing the code in a development or testing environment.
To track FreeBSD-STABLE:
Join the freebsd-stable list in order to stay informed of build dependencies that may appear in FreeBSD-STABLE or any other issues requiring special attention. Developers will also make announcements in this mailing list when they are contemplating some controversial fix or update, giving the users a chance to respond if they have any issues to raise concerning the proposed change.
Join the relevant svn list for the branch being tracked. For example, users tracking the 9-STABLE branch should join the svn-src-stable-9 list. This list records the commit log entry for each change as it is made, along with any pertinent information on possible side effects.
To join these lists, go to http://lists.FreeBSD.org/mailman/listinfo, click on the list to subscribe to, and follow the instructions. In order to track changes for the whole source tree, subscribe to svn-src-all.
To install a new FreeBSD-STABLE system, install the most recent FreeBSD-STABLE release from the FreeBSD mirror sites or use a monthly snapshot built from FreeBSD-STABLE. Refer to www.freebsd.org/snapshots for more information about snapshots.
To compile or upgrade to an existing FreeBSD system to
FreeBSD-STABLE, use svn
to check out the source for the desired
branch. Branch names, such as
stable/9
, are listed at www.freebsd.org/releng.
Before compiling or upgrading to FreeBSD-STABLE
, read /usr/src/Makefile
carefully and follow the instructions in Section 23.5, “Updating FreeBSD from Source”. Read the FreeBSD-STABLE mailing list and
/usr/src/UPDATING
to keep up-to-date
on other bootstrapping procedures that sometimes become
necessary on the road to the next release.
Updating FreeBSD by compiling from source offers several advantages over binary updates. Code can be built with options to take advantage of specific hardware. Parts of the base system can be built with non-default settings, or left out entirely where they are not needed or desired. The build process takes longer to update a system than just installing binary updates, but allows complete customization to produce a tailored version of FreeBSD.
This is a quick reference for the typical steps used to update FreeBSD by building from source. Later sections describe the process in more detail.
Update and Build
#
svnlite update /usr/src
check/usr/src/UPDATING
#
cd /usr/src
#
make -j
4
buildworld#
make -j
4
kernel#
shutdown -r now
#
cd /usr/src
#
make installworld
#
mergemaster -Ui
#
shutdown -r now
Get the latest version of the source. See Section 23.5.3, “Updating the Source” for more information on obtaining and updating source. | |
Check | |
Go to the source directory. | |
Compile the world, everything except the kernel. | |
Compile and install the kernel. This is
equivalent to | |
Reboot the system to the new kernel. | |
Go to the source directory. | |
Install the world. | |
Update and merge configuration files in
| |
Restart the system to use the newly-built world and kernel. |
Read /usr/src/UPDATING
. Any manual
steps that must be performed before or after an update are
described in this file.
FreeBSD source code is located in
/usr/src/
. The preferred method of
updating this source is through the
Subversion version control system.
Verify that the source code is under version control:
#
svnlite info /usr/src
Path: /usr/src Working Copy Root Path: /usr/src ...
This indicates that /usr/src/
is under version control and can be updated with
svnlite(1):
#
svnlite update /usr/src
The update process can take some time if the directory has not been updated recently. After it finishes, the source code is up to date and the build process described in the next section can begin.
If the output says
'/usr/src' is not a working copy
, the
files there are missing or were installed with a different
method. A new checkout of the source is required.
Determine which version of FreeBSD is being used with uname(1):
#
uname -r
10.3-RELEASE
Based on
Table 23.1, “FreeBSD Versions and Repository Paths”, the
source used to update 10.3-RELEASE
has
a repository path of base/releng/10.3
.
That path is used when checking out the source:
#
mv /usr/src /usr/src.bak
#
svnlite checkout https://svn.freebsd.org/base/
releng/10.3
/usr/src
Move the old directory out of the way. If there are no local modifications in this directory, it can be deleted. | |
The path from Table 23.1, “FreeBSD Versions and Repository Paths” is added to the repository URL. The third parameter is the destination directory for the source code on the local system. |
The world, or all of the operating system except the kernel, is compiled. This is done first to provide up-to-date tools to build the kernel. Then the kernel itself is built:
#
cd /usr/src
#
make buildworld
#
make buildkernel
The compiled code is written to
/usr/obj
.
These are the basic steps. Additional options to control the build are described below.
Some versions of the FreeBSD build system leave
previously-compiled code in the temporary object directory,
/usr/obj
. This can speed up later
builds by avoiding recompiling code that has not changed.
To force a clean rebuild of everything, use
cleanworld
before starting
a build:
#
make cleanworld
Increasing the number of build jobs on multi-core
processors can improve build speed. Determine the number of
cores with sysctl hw.ncpu
. Processors
vary, as do the build systems used with different versions
of FreeBSD, so testing is the only sure method to tell how a
different number of jobs affects the build speed. For a
starting point, consider values between half and double the
number of cores. The number of jobs is specified with
-j
.
Building the world and kernel with four jobs:
#
make -j4 buildworld buildkernel
A buildworld
must be
completed if the source code has changed. After that, a
buildkernel
to build a kernel can
be run at any time. To build just the kernel:
#
cd /usr/src
#
make buildkernel
The standard FreeBSD kernel is based on a
kernel config file called
GENERIC
. The
GENERIC
kernel includes the most
commonly-needed device drivers and options. Sometimes it
is useful or necessary to build a custom kernel, adding or
removing device drivers or options to fit a specific
need.
For example, someone developing a small embedded computer with severely limited RAM could remove unneeded device drivers or options to make the kernel slightly smaller.
Kernel config files are located in
/usr/src/sys/
,
where arch
/conf/arch
is the output from
uname -m
. On most computers, that is
amd64
, giving a config file directory of
/usr/src/sys/
.amd64
/conf/
/usr/src
can be deleted or
recreated, so it is preferable to keep custom kernel
config files in a separate directory, like
/root
. Link the kernel config file
into the conf
directory. If that
directory is deleted or overwritten, the kernel config
can be re-linked into the new one.
A custom config file can be created by copying the
GENERIC
config file. In this example,
the new custom kernel is for a storage server, so is named
STORAGESERVER
:
#
cp /usr/src/sys/amd64/conf/GENERIC /root/STORAGESERVER
#
cd /usr/src/sys/amd64/conf
#
ln -s /root/STORAGESERVER .
/root/STORAGESERVER
is then edited,
adding or removing devices or options as shown in
config(5).
The custom kernel is built by setting
KERNCONF
to the kernel config file on the
command line:
#
make buildkernel KERNCONF=STORAGESERVER
After the buildworld
and
buildkernel
steps have been
completed, the new kernel and world are installed:
#
cd /usr/src
#
make installkernel
#
shutdown -r now
#
cd /usr/src
#
make installworld
#
shutdown -r now
If a custom kernel was built, KERNCONF
must also be set to use the new custom kernel:
#
cd /usr/src
#
make installkernel KERNCONF=STORAGESERVER
#
shutdown -r now
#
cd /usr/src
#
make installworld
#
shutdown -r now
A few final tasks complete the update. Any modified configuration files are merged with the new versions, outdated libraries are located and removed, then the system is restarted.
mergemaster(8) provides an easy way to merge changes that have been made to system configuration files with new versions of those files.
With -Ui
, mergemaster(8)
automatically updates files that have not been user-modified
and installs new files that are not already present:
#
mergemaster -Ui
If a file must be manually merged, an interactive display allows the user to choose which portions of the files are kept. See mergemaster(8) for more information.
Some obsolete files or directories can remain after an update. These files can be located:
#
make check-old
and deleted:
#
make delete-old
Some obsolete libraries can also remain. These can be detected with:
#
make check-old-libs
and deleted with
#
make delete-old-libs
Programs which were still using those old libraries will stop working when the library has been deleted. These programs must be rebuilt or replaced after deleting the old libraries.
When all the old files or directories are known to be
safe to delete, pressing y and
Enter to delete each file can be avoided
by setting BATCH_DELETE_OLD_FILES
in
the command. For example:
#
make BATCH_DELETE_OLD_FILES=yes delete-old-libs
When multiple machines need to track the same source tree, it is a waste of disk space, network bandwidth, and CPU cycles to have each system download the sources and rebuild everything. The solution is to have one machine do most of the work, while the rest of the machines mount that work via NFS. This section outlines a method of doing so. For more information about using NFS, refer to Section 29.3, “Network File System (NFS)”.
First, identify a set of machines which will run the same
set of binaries, known as a build set.
Each machine can have a custom kernel, but will run the same
userland binaries. From that set, choose a machine to be the
build machine that the world and kernel
are built on. Ideally, this is a fast machine that has
sufficient spare CPU to run make
buildworld
and make
buildkernel
.
Select a machine to be the test machine, which will test software updates before they are put into production. This must be a machine that can afford to be down for an extended period of time. It can be the build machine, but need not be.
All the machines in this build set need to mount
/usr/obj
and /usr/src
from the build machine via NFS. For multiple
build sets, /usr/src
should be on one build
machine, and NFS mounted on the rest.
Ensure that /etc/make.conf
and
/etc/src.conf
on all the machines in the
build set agree with the build machine. That means that the
build machine must build all the parts of the base system that
any machine in the build set is going to install. Also, each
build machine should have its kernel name set with
KERNCONF
in
/etc/make.conf
, and the build machine
should list them all in its KERNCONF
,
listing its own kernel first. The build machine must have the
kernel configuration files for each machine in its /usr/src/sys/
.arch
/conf
On the build machine, build the kernel and world as
described in Section 23.5, “Updating FreeBSD from Source”, but do not install
anything on the build machine. Instead, install the built
kernel on the test machine. On the test machine, mount
/usr/src
and
/usr/obj
via NFS. Then,
run shutdown now
to go to single-user mode in
order to install the new kernel and world and run
mergemaster
as usual. When done, reboot to
return to normal multi-user operations.
After verifying that everything on the test machine is working properly, use the same procedure to install the new software on each of the other machines in the build set.
The same methodology can be used for the ports tree. The
first step is to share /usr/ports
via
NFS to all the machines in the build set. To
configure /etc/make.conf
to share
distfiles, set DISTDIR
to a common shared
directory that is writable by whichever user root
is mapped to by the
NFS mount. Each machine should set
WRKDIRPREFIX
to a local build directory, if
ports are to be built locally. Alternately, if the build system
is to build and distribute packages to the machines in the build
set, set PACKAGES
on the build system to a
directory similar to DISTDIR
.
DTrace, also known as Dynamic Tracing, was developed by Sun™ as a tool for locating performance bottlenecks in production and pre-production systems. In addition to diagnosing performance problems, DTrace can be used to help investigate and debug unexpected behavior in both the FreeBSD kernel and in userland programs.
DTrace is a remarkable profiling tool, with an impressive array of features for diagnosing system issues. It may also be used to run pre-written scripts to take advantage of its capabilities. Users can author their own utilities using the DTrace D Language, allowing them to customize their profiling based on specific needs.
The FreeBSD implementation provides full support for kernel
DTrace and experimental support for userland DTrace.
Userland DTrace allows users to perform function boundary
tracing for userland programs using the pid
provider, and to insert static probes into userland programs for
later tracing. Some ports, such as
databases/postgres-server and
lang/php56 have a DTrace option to enable
static probes. FreeBSD 10.0-RELEASE has reasonably good userland
DTrace support, but it is not considered production ready. In
particular, it is possible to crash traced programs.
The official guide to DTrace is maintained by the Illumos
project at DTrace
Guide
.
After reading this chapter, you will know:
What DTrace is and what features it provides.
Differences between the Solaris™ DTrace implementation and the one provided by FreeBSD.
How to enable and use DTrace on FreeBSD.
Before reading this chapter, you should:
Understand UNIX® and FreeBSD basics (Chapter 3, FreeBSD Basics).
Have some familiarity with security and how it pertains to FreeBSD (Chapter 13, Security).
While the DTrace in FreeBSD is similar to that found in Solaris™, differences do exist. The primary difference is that in FreeBSD, DTrace is implemented as a set of kernel modules and DTrace can not be used until the modules are loaded. To load all of the necessary modules:
#
kldload dtraceall
Beginning with FreeBSD 10.0-RELEASE, the modules are
automatically loaded when dtrace
is
run.
FreeBSD uses the DDB_CTF
kernel option to
enable support for loading CTF data from
kernel modules and the kernel itself. CTF is
the Solaris™ Compact C Type Format which encapsulates a reduced
form of debugging information similar to
DWARF and the venerable stabs.
CTF data is added to binaries by the
ctfconvert
and ctfmerge
build tools. The ctfconvert
utility parses
DWARF ELF debug sections
created by the compiler and ctfmerge
merges
CTF ELF sections from
objects into either executables or shared libraries.
Some different providers exist for FreeBSD than for Solaris™.
Most notable is the dtmalloc
provider, which
allows tracing malloc()
by type in the FreeBSD
kernel. Some of the providers found in Solaris™, such as
cpc
and mib
, are not
present in FreeBSD. These may appear in future versions of FreeBSD.
Moreover, some of the providers available in both operating
systems are not compatible, in the sense that their probes have
different argument types. Thus, D scripts
written on Solaris™ may or may not work unmodified on FreeBSD, and
vice versa.
Due to security differences, only root
may use DTrace on FreeBSD.
Solaris™ has a few low level security checks which do not yet
exist in FreeBSD. As such, the
/dev/dtrace/dtrace
is strictly limited to
root
.
DTrace falls under the Common Development and Distribution
License (CDDL) license. To view this license
on FreeBSD, see
/usr/src/cddl/contrib/opensolaris/OPENSOLARIS.LICENSE
or view it online at http://opensource.org/licenses/CDDL-1.0
.
While a FreeBSD kernel with DTrace support is
BSD licensed, the CDDL is
used when the modules are distributed in binary form or the
binaries are loaded.
In FreeBSD 9.2 and 10.0, DTrace support is built into the
GENERIC
kernel. Users of earlier versions
of FreeBSD or who prefer to statically compile in DTrace support
should add the following lines to a custom kernel configuration
file and recompile the kernel using the instructions in Chapter 8, Configuring the FreeBSD Kernel:
options KDTRACE_HOOKS options DDB_CTF makeoptions DEBUG=-g makeoptions WITH_CTF=1
Users of the AMD64 architecture should also add this line:
options KDTRACE_FRAME
This option provides support for FBT. While DTrace will work without this option, there will be limited support for function boundary tracing.
Once the FreeBSD system has rebooted into the new kernel, or
the DTrace kernel modules have been loaded using
kldload dtraceall
, the system will need
support for the Korn shell as the DTrace
Toolkit has several utilities written in ksh
.
Make sure that the shells/ksh93 package or
port is installed. It is also possible to run these tools under
shells/pdksh or
shells/mksh.
Finally, install the current DTrace Toolkit,
a collection of ready-made scripts
for collecting system information. There are scripts to check
open files, memory, CPU usage, and a lot
more. FreeBSD 10
installs a few of these scripts into
/usr/share/dtrace
. On other FreeBSD versions,
or to install the full
DTrace Toolkit, use the
sysutils/DTraceToolkit package or
port.
The scripts found in
/usr/share/dtrace
have been specifically
ported to FreeBSD. Not all of the scripts found in the DTrace
Toolkit will work as-is on FreeBSD and some scripts may require
some effort in order for them to work on FreeBSD.
The DTrace Toolkit includes many scripts in the special
language of DTrace. This language is called the D language
and it is very similar to C++. An in depth discussion of the
language is beyond the scope of this document. It is
covered extensively in the Illumos Dynamic
Tracing Guide
.
DTrace scripts consist of a list of one or more probes, or instrumentation points, where each probe is associated with an action. Whenever the condition for a probe is met, the associated action is executed. For example, an action may occur when a file is opened, a process is started, or a line of code is executed. The action might be to log some information or to modify context variables. The reading and writing of context variables allows probes to share information and to cooperatively analyze the correlation of different events.
To view all probes, the administrator can execute the following command:
#
dtrace -l | more
Each probe has an ID
, a
PROVIDER
(dtrace or fbt), a
MODULE
, and a
FUNCTION NAME
. Refer to dtrace(1) for
more information about this command.
The examples in this section provide an overview of how to
use two of the fully supported scripts from the
DTrace Toolkit: the
hotkernel
and
procsystime
scripts.
The hotkernel
script is designed to
identify which function is using the most kernel time. It will
produce output similar to the following:
#
cd /usr/share/dtrace/toolkit
#
./hotkernel
Sampling... Hit Ctrl-C to end.
As instructed, use the Ctrl+C key combination to stop the process. Upon termination, the script will display a list of kernel functions and timing information, sorting the output in increasing order of time:
kernel`_thread_lock_flags 2 0.0% 0xc1097063 2 0.0% kernel`sched_userret 2 0.0% kernel`kern_select 2 0.0% kernel`generic_copyin 3 0.0% kernel`_mtx_assert 3 0.0% kernel`vm_fault 3 0.0% kernel`sopoll_generic 3 0.0% kernel`fixup_filename 4 0.0% kernel`_isitmyx 4 0.0% kernel`find_instance 4 0.0% kernel`_mtx_unlock_flags 5 0.0% kernel`syscall 5 0.0% kernel`DELAY 5 0.0% 0xc108a253 6 0.0% kernel`witness_lock 7 0.0% kernel`read_aux_data_no_wait 7 0.0% kernel`Xint0x80_syscall 7 0.0% kernel`witness_checkorder 7 0.0% kernel`sse2_pagezero 8 0.0% kernel`strncmp 9 0.0% kernel`spinlock_exit 10 0.0% kernel`_mtx_lock_flags 11 0.0% kernel`witness_unlock 15 0.0% kernel`sched_idletd 137 0.3% 0xc10981a5 42139 99.3%
This script will also work with kernel modules. To use this
feature, run the script with -m
:
#
./hotkernel -m
Sampling... Hit Ctrl-C to end. ^C MODULE COUNT PCNT 0xc107882e 1 0.0% 0xc10e6aa4 1 0.0% 0xc1076983 1 0.0% 0xc109708a 1 0.0% 0xc1075a5d 1 0.0% 0xc1077325 1 0.0% 0xc108a245 1 0.0% 0xc107730d 1 0.0% 0xc1097063 2 0.0% 0xc108a253 73 0.0% kernel 874 0.4% 0xc10981a5 213781 99.6%
The procsystime
script captures and
prints the system call time usage for a given process
ID (PID) or process name.
In the following example, a new instance of
/bin/csh
was spawned. Then,
procsystime
was executed and remained
waiting while a few commands were typed on the other incarnation
of csh
. These are the results of this
test:
#
./procsystime -n csh
Tracing... Hit Ctrl-C to end... ^C Elapsed Times for processes csh, SYSCALL TIME (ns) getpid 6131 sigreturn 8121 close 19127 fcntl 19959 dup 26955 setpgid 28070 stat 31899 setitimer 40938 wait4 62717 sigaction 67372 sigprocmask 119091 gettimeofday 183710 write 263242 execve 492547 ioctl 770073 vfork 3258923 sigsuspend 6985124 read 3988049784
As shown, the read()
system call used
the most time in nanoseconds while the
getpid()
system call used the least amount
of time.
This chapter covers the use of USB Device Mode and USB On The Go (USB OTG) in FreeBSD. This includes virtual serial consoles, virtual network interfaces, and virtual USB drives.
When running on hardware that supports USB device mode or USB OTG, like that built into many embedded boards, the FreeBSD USB stack can run in device mode. Device mode makes it possible for the computer to present itself as different kinds of USB device classes, including serial ports, network adapters, and mass storage, or a combination thereof. A USB host like a laptop or desktop computer is able to access them just like physical USB devices. Device mode is sometimes called the “USB gadget mode”.
There are two basic ways the hardware can provide the device mode functionality: with a separate "client port", which only supports the device mode, and with a USB OTG port, which can provide both device and host mode. For USB OTG ports, the USB stack switches between host-side and device-side automatically, depending on what is connected to the port. Connecting a USB device like a memory stick to the port causes FreeBSD to switch to host mode. Connecting a USB host like a computer causes FreeBSD to switch to device mode. Single purpose "client ports" always work in device mode.
What FreeBSD presents to the USB host
depends on the hw.usb.template
sysctl. Some
templates provide a single device, such as a serial terminal;
others provide multiple ones, which can all be used at the same
time. An example is the template 10, which provides a mass
storage device, a serial console, and a network interface.
See usb_template(4) for the list of available
values.
Note that in some cases, depending on the hardware and the
hosts operating system, for the host to notice the configuration
change, it must be either physically disconnected and
reconnected, or forced to rescan the USB
bus in a system-specific way. When FreeBSD is running on the host,
usbconfig(8) reset
can be used.
This also must be done after loading
usb_template.ko
if the
USB host was already connected to the
USB OTG socket.
After reading this chapter, you will know:
How to set up USB Device Mode functionality on FreeBSD.
How to configure the virtual serial port on FreeBSD.
How to connect to the virtual serial port from various operating systems.
How to configure FreeBSD to provide a virtual USB network interface.
How to configure FreeBSD to provide a virtual USB storage device.
Virtual serial port support is provided by templates number 3, 8, and 10. Note that template 3 works with Microsoft Windows 10 without the need for special drivers and INF files. Other host operating systems work with all three templates. Both usb_template(4) and umodem(4) kernel modules must be loaded.
To enable USB device mode serial ports, add those lines
to /etc/ttys
:
ttyU0 "/usr/libexec/getty 3wire" vt100 onifconsole secure ttyU1 "/usr/libexec/getty 3wire" vt100 onifconsole secure
Then add these lines to
/etc/devd.conf
:
notify 100 { match "system" "DEVFS"; match "subsystem" "CDEV"; match "type" "CREATE"; match "cdev" "ttyU[0-9]+"; action "/sbin/init q"; };
Reload the configuration if devd(8) is already running:
#
service devd restart
Make sure the necessary modules are loaded and the
correct template is set at boot by adding
those lines to /boot/loader.conf
,
creating it if it does not already exist:
umodem_load="YES" hw.usb.template=3
To load the module and set the template without rebooting use:
#
kldload umodem
#
sysctl hw.usb.template=3
To connect to a board configured to provide USB device
mode serial ports, connect the USB host, such as a laptop, to
the boards USB OTG or USB client port. Use
pstat -t
on the host to list the terminal
lines. Near the end of the list you should see a USB serial
port, eg "ttyU0". To open the connection, use:
#
cu -l /dev/ttyU0
After pressing the Enter key a few times you will see a login prompt.
To connect to a board configured to provide USB device mode serial ports, connect the USB host, such as a laptop, to the boards USB OTG or USB client port. To open the connection, use:
#
cu -l /dev/cu.usbmodemFreeBSD1
To connect to a board configured to provide USB device mode serial ports, connect the USB host, such as a laptop, to the boards USB OTG or USB client port. To open the connection, use:
#
minicom -D /dev/ttyACM0
To connect to a board configured to provide USB device mode serial ports, connect the USB host, such as a laptop, to the boards USB OTG or USB client port. To open a connection you will need a serial terminal program, such as PuTTY. To check the COM port name used by Windows, run Device Manager, expand "Ports (COM & LPT)". You will see a name similar to "USB Serial Device (COM4)". Run serial terminal program of your choice, for example PuTTY. In the PuTTY dialog set "Connection type" to "Serial", type the COMx obtained from Device Manager in the "Serial line" dialog box and click Open.
Virtual network interfaces support is provided by templates number 1, 8, and 10. Note that none of them works with Microsoft Windows. Other host operating systems work with all three templates. Both usb_template(4) and if_cdce(4) kernel modules must be loaded.
Make sure the necessary modules are loaded and the correct
template is set at boot by adding
those lines to /boot/loader.conf
, creating
it if it does not already exist:
if_cdce_load="YES" hw.usb.template=1
To load the module and set the template without rebooting use:
#
kldload if_cdce
#
sysctl hw.usb.template=1
The cfumass(4) driver is a USB device mode driver first available in FreeBSD 12.0.
Mass Storage target is provided by templates 0 and 10. Both usb_template(4) and cfumass(4) kernel modules must be loaded. cfumass(4) interfaces to the CTL subsystem, the same one that is used for iSCSI or Fibre Channel targets. On the host side, USB Mass Storage initiators can only access a single LUN, LUN 0.
The simplest way to set up a read-only USB storage target
is to use the cfumass
rc script. To
configure it this way, copy the files to be presented to the
USB host machine into the /var/cfumass
directory, and add this line to
/etc/rc.conf
:
cfumass_enable="YES"
To configure the target without restarting, run this command:
#
service cfumass start
Differently from serial and network functionality, the
template should not be set to 0 or 10 in
/boot/loader.conf
. This is because the
LUN must be set up before setting the template. The cfumass
startup script sets the correct template number automatically
when started.
The rest of this chapter provides detailed description of setting the target without using the cfumass rc file. This is necessary if eg one wants to provide a writeable LUN.
USB Mass Storage does not require the
ctld(8) daemon to be running, although it can be used if
desired. This is different from iSCSI.
Thus, there are two ways to configure the target:
ctladm(8), or ctld(8). Both require the
cfumass.ko
kernel module to be loaded.
The module can be loaded manually:
#
kldload cfumass
If cfumass.ko
has not been built into
the kernel, /boot/loader.conf
can be set
to load the module at boot:
cfumass_load="YES"
A LUN can be created without the ctld(8) daemon:
#
ctladm create -b block -o file=/data/target0
This presents the contents of the image file
/data/target0
as a LUN
to the USB host. The file must exist
before executing the command. To configure the
LUN at system startup, add the command to
/etc/rc.local
.
ctld(8) can also be used to manage
LUNs. Create
/etc/ctl.conf
, add a line to
/etc/rc.conf
to make sure ctld(8) is
automatically started at boot, and then start the
daemon.
This is an example of a simple
/etc/ctl.conf
configuration file. Refer
to ctl.conf(5) for a more complete description of the
options.
target naa.50015178f369f092 { lun 0 { path /data/target0 size 4G } }
The example creates a single target with a single
LUN. The
naa.50015178f369f092
is a device identifier
composed of 32 random hexadecimal digits. The
path
line defines the full path to a file
or zvol backing the LUN. That file must
exist before starting ctld(8). The second line is
optional and specifies the size of the
LUN.
To make sure the ctld(8) daemon is started at
boot, add this line to
/etc/rc.conf
:
ctld_enable="YES"
To start ctld(8) now, run this command:
#
service ctld start
As the ctld(8) daemon is started, it reads
/etc/ctl.conf
. If this file is edited
after the daemon starts, reload the changes so they take
effect immediately:
#
service ctld reload
FreeBSD is one of the most widely deployed operating systems for high performance network servers. The chapters in this part cover:
Serial communication
PPP and PPP over Ethernet
Electronic Mail
Running Network Servers
Firewalls
Other Advanced Networking Topics
These chapters are designed to be read when the information is needed. They do not need to be read in any particular order, nor is it necessary to read all of them before using FreeBSD in a network environment.
UNIX® has always had support for serial communications as the very first UNIX® machines relied on serial lines for user input and output. Things have changed a lot from the days when the average terminal consisted of a 10-character-per-second serial printer and a keyboard. This chapter covers some of the ways serial communications can be used on FreeBSD.
After reading this chapter, you will know:
How to connect terminals to a FreeBSD system.
How to use a modem to dial out to remote hosts.
How to allow remote users to login to a FreeBSD system with a modem.
How to boot a FreeBSD system from a serial console.
Before reading this chapter, you should:
Know how to configure and install a custom kernel.
Understand FreeBSD permissions and processes.
Have access to the technical manual for the serial hardware to be used with FreeBSD.
The following terms are often used in serial communications:
Bits per Second (bps) is the rate at which data is transmitted.
Data Terminal Equipment (DTE) is one of two endpoints in a serial communication. An example would be a computer.
Data Communications Equipment (DTE) is the other endpoint in a serial communication. Typically, it is a modem or serial terminal.
The original standard which defined hardware serial communications. It has since been renamed to TIA-232.
When referring to communication data rates, this section does not use the term baud. Baud refers to the number of electrical state transitions made in a period of time, while bps is the correct term to use.
To connect a serial terminal to a FreeBSD system, a serial port on the computer and the proper cable to connect to the serial device are needed. Users who are already familiar with serial hardware and cabling can safely skip this section.
There are several different kinds of serial cables. The two most common types are null-modem cables and standard RS-232 cables. The documentation for the hardware should describe the type of cable required.
These two types of cables differ in how the wires are connected to the connector. Each wire represents a signal, with the defined signals summarized in Table 26.1, “RS-232C Signal Names”. A standard serial cable passes all of the RS-232C signals straight through. For example, the “Transmitted Data” pin on one end of the cable goes to the “Transmitted Data” pin on the other end. This is the type of cable used to connect a modem to the FreeBSD system, and is also appropriate for some terminals.
A null-modem cable switches the “Transmitted Data” pin of the connector on one end with the “Received Data” pin on the other end. The connector can be either a DB-25 or a DB-9.
A null-modem cable can be constructed using the pin connections summarized in Table 26.2, “DB-25 to DB-25 Null-Modem Cable”, Table 26.3, “DB-9 to DB-9 Null-Modem Cable”, and Table 26.4, “DB-9 to DB-25 Null-Modem Cable”. While the standard calls for a straight-through pin 1 to pin 1 “Protective Ground” line, it is often omitted. Some terminals work using only pins 2, 3, and 7, while others require different configurations. When in doubt, refer to the documentation for the hardware.
Acronyms | Names |
---|---|
RD | Received Data |
TD | Transmitted Data |
DTR | Data Terminal Ready |
DSR | Data Set Ready |
DCD | Data Carrier Detect |
SG | Signal Ground |
RTS | Request to Send |
CTS | Clear to Send |
Signal | Pin # | Pin # | Signal | |
---|---|---|---|---|
SG | 7 | connects to | 7 | SG |
TD | 2 | connects to | 3 | RD |
RD | 3 | connects to | 2 | TD |
RTS | 4 | connects to | 5 | CTS |
CTS | 5 | connects to | 4 | RTS |
DTR | 20 | connects to | 6 | DSR |
DTR | 20 | connects to | 8 | DCD |
DSR | 6 | connects to | 20 | DTR |
DCD | 8 | connects to | 20 | DTR |
Signal | Pin # | Pin # | Signal | |
---|---|---|---|---|
RD | 2 | connects to | 3 | TD |
TD | 3 | connects to | 2 | RD |
DTR | 4 | connects to | 6 | DSR |
DTR | 4 | connects to | 1 | DCD |
SG | 5 | connects to | 5 | SG |
DSR | 6 | connects to | 4 | DTR |
DCD | 1 | connects to | 4 | DTR |
RTS | 7 | connects to | 8 | CTS |
CTS | 8 | connects to | 7 | RTS |
Signal | Pin # | Pin # | Signal | |
---|---|---|---|---|
RD | 2 | connects to | 2 | TD |
TD | 3 | connects to | 3 | RD |
DTR | 4 | connects to | 6 | DSR |
DTR | 4 | connects to | 8 | DCD |
SG | 5 | connects to | 7 | SG |
DSR | 6 | connects to | 20 | DTR |
DCD | 1 | connects to | 20 | DTR |
RTS | 7 | connects to | 5 | CTS |
CTS | 8 | connects to | 4 | RTS |
When one pin at one end connects to a pair of pins at the other end, it is usually implemented with one short wire between the pair of pins in their connector and a long wire to the other single pin.
Serial ports are the devices through which data is transferred between the FreeBSD host computer and the terminal. Several kinds of serial ports exist. Before purchasing or constructing a cable, make sure it will fit the ports on the terminal and on the FreeBSD system.
Most terminals have DB-25 ports. Personal computers may have DB-25 or DB-9 ports. A multiport serial card may have RJ-12 or RJ-45/ ports. See the documentation that accompanied the hardware for specifications on the kind of port or visually verify the type of port.
In FreeBSD, each serial port is accessed through an entry in
/dev
. There are two different kinds of
entries:
Call-in ports are named
/dev/ttyu
where N
N
is the port number,
starting from zero. If a terminal is connected to the
first serial port (COM1
), use
/dev/ttyu0
to refer to the terminal.
If the terminal is on the second serial port
(COM2
), use
/dev/ttyu1
, and so forth. Generally,
the call-in port is used for terminals. Call-in ports
require that the serial line assert the “Data
Carrier Detect” signal to work correctly.
Call-out ports are named
/dev/cuau
on FreeBSD versions 8.X and higher and
N
/dev/cuad
on FreeBSD versions 7.X and lower. Call-out ports are
usually not used for terminals, but are used for modems.
The call-out port can be used if the serial cable or the
terminal does not support the “Data Carrier
Detect” signal.N
FreeBSD also provides initialization devices
(/dev/ttyu
and
N
.init/dev/cuau
or
N
.init/dev/cuad
)
and locking devices
(N
.init/dev/ttyu
and
N
.lock/dev/cuau
or
N
.lock/dev/cuad
).
The initialization devices are used to initialize
communications port parameters each time a port is opened,
such as N
.lockcrtscts
for modems which use
RTS/CTS
signaling for flow control. The
locking devices are used to lock flags on ports to prevent
users or programs changing certain parameters. Refer to
termios(4), sio(4), and stty(1) for information
on terminal settings, locking and initializing devices, and
setting terminal options, respectively.
By default, FreeBSD supports four serial ports which are
commonly known as COM1
,
COM2
, COM3
, and
COM4
. FreeBSD also supports dumb multi-port
serial interface cards, such as the BocaBoard 1008 and 2016,
as well as more intelligent multi-port cards such as those
made by Digiboard. However, the default kernel only looks for
the standard COM
ports.
To see if the system recognizes the serial ports, look for
system boot messages that start with
uart
:
#
grep uart /var/run/dmesg.boot
If the system does not recognize all of the needed serial
ports, additional entries can be added to
/boot/device.hints
. This file already
contains hint.uart.0.*
entries for
COM1
and hint.uart.1.*
entries for COM2
. When adding a port
entry for COM3
use
0x3E8
, and for COM4
use 0x2E8
. Common IRQ
addresses are 5
for
COM3
and 9
for
COM4
.
To determine the default set of terminal
I/O settings used by the port, specify its
device name. This example determines the settings for the
call-in port on COM2
:
#
stty -a -f /dev/
ttyu1
System-wide initialization of serial devices is controlled
by /etc/rc.d/serial
. This file affects
the default settings of serial devices. To change the
settings for a device, use stty
. By
default, the changed settings are in effect until the device
is closed and when the device is reopened, it goes back to the
default set. To permanently change the default set, open and
adjust the settings of the initialization device. For
example, to turn on CLOCAL
mode, 8 bit
communication, and XON/XOFF
flow control for
ttyu5
, type:
#
stty -f /dev/ttyu5.init clocal cs8 ixon ixoff
To prevent certain settings from being changed by an
application, make adjustments to the locking device. For
example, to lock the speed of ttyu5
to
57600 bps, type:
#
stty -f /dev/ttyu5.lock 57600
Now, any application that opens ttyu5
and tries to change the speed of the port will be stuck with
57600 bps.
Terminals provide a convenient and low-cost way to access a FreeBSD system when not at the computer's console or on a connected network. This section describes how to use terminals with FreeBSD.
The original UNIX® systems did not have consoles. Instead, users logged in and ran programs through terminals that were connected to the computer's serial ports.
The ability to establish a login session on a serial port
still exists in nearly every UNIX®-like operating system
today, including FreeBSD. By using a terminal attached to an
unused serial port, a user can log in and run any text program
that can normally be run on the console or in an
xterm
window.
Many terminals can be attached to a FreeBSD system. An older spare computer can be used as a terminal wired into a more powerful computer running FreeBSD. This can turn what might otherwise be a single-user computer into a powerful multiple-user system.
FreeBSD supports three types of terminals:
Dumb terminals are specialized hardware that connect to computers over serial lines. They are called “dumb” because they have only enough computational power to display, send, and receive text. No programs can be run on these devices. Instead, dumb terminals connect to a computer that runs the needed programs.
There are hundreds of kinds of dumb terminals made by many manufacturers, and just about any kind will work with FreeBSD. Some high-end terminals can even display graphics, but only certain software packages can take advantage of these advanced features.
Dumb terminals are popular in work environments where workers do not need access to graphical applications.
Since a dumb terminal has just enough ability to display, send, and receive text, any spare computer can be a dumb terminal. All that is needed is the proper cable and some terminal emulation software to run on the computer.
This configuration can be useful. For example, if one user is busy working at the FreeBSD system's console, another user can do some text-only work at the same time from a less powerful personal computer hooked up as a terminal to the FreeBSD system.
There are at least two utilities in the base-system of FreeBSD that can be used to work through a serial connection: cu(1) and tip(1).
For example, to connect from a client system that runs FreeBSD to the serial connection of another system:
#
cu -l /dev/cuau
N
Ports are numbered starting from zero. This means that
COM1
is
/dev/cuau0
.
Additional programs are available through the Ports Collection, such as comms/minicom.
X terminals are the most sophisticated kind of terminal available. Instead of connecting to a serial port, they usually connect to a network like Ethernet. Instead of being relegated to text-only applications, they can display any Xorg application.
This chapter does not cover the setup, configuration, or use of X terminals.
This section describes how to configure a FreeBSD system to enable a login session on a serial terminal. It assumes that the system recognizes the serial port to which the terminal is connected and that the terminal is connected with the correct cable.
In FreeBSD, init
reads
/etc/ttys
and starts a
getty
process on the available terminals.
The getty
process is responsible for
reading a login name and starting the login
program. The ports on the FreeBSD system which allow logins are
listed in /etc/ttys
. For example, the
first virtual console, ttyv0
, has an
entry in this file, allowing logins on the console. This file
also contains entries for the other virtual consoles, serial
ports, and pseudo-ttys. For a hardwired terminal, the serial
port's /dev
entry is listed without the
/dev
part. For example,
/dev/ttyv0
is listed as
ttyv0
.
The default /etc/ttys
configures
support for the first four serial ports,
ttyu0
through
ttyu3
:
ttyu0 "/usr/libexec/getty std.9600" dialup off secure ttyu1 "/usr/libexec/getty std.9600" dialup off secure ttyu2 "/usr/libexec/getty std.9600" dialup off secure ttyu3 "/usr/libexec/getty std.9600" dialup off secure
When attaching a terminal to one of those ports, modify
the default entry to set the required speed and terminal type,
to turn the device on
and, if needed, to
change the port's secure
setting. If the
terminal is connected to another port, add an entry for the
port.
Example 26.1, “Configuring Terminal Entries” configures two terminals in
/etc/ttys
. The first entry configures a
Wyse-50 connected to COM2
. The second
entry configures an old computer running
Procomm terminal software emulating
a VT-100 terminal. The computer is connected to the sixth
serial port on a multi-port serial card.
ttyu1 "/usr/libexec/getty std.38400" wy50 on insecure ttyu5 "/usr/libexec/getty std.19200" vt100 on insecure
The first field specifies the device name of the serial terminal. | |
The second field tells When setting the getty type, make sure to match the communications settings used by the terminal. For this example, the Wyse-50 uses no parity and connects at 38400 bps. The computer uses no parity and connects at 19200 bps. | |
The third field is the type of terminal. For
dial-up ports, | |
The fourth field specifies if the port should be
enabled. To enable logins on this port, this field must
be set to | |
The final field is used to specify whether the port
is secure. Marking a port as |
After making any changes to
/etc/ttys
, send a SIGHUP (hangup) signal
to the init
process to force it to re-read
its configuration file:
#
kill -HUP 1
Since init
is always the first process
run on a system, it always has a process ID
of 1
.
If everything is set up correctly, all cables are in
place, and the terminals are powered up, a
getty
process should now be running on each
terminal and login prompts should be available on each
terminal.
Even with the most meticulous attention to detail, something could still go wrong while setting up a terminal. Here is a list of common symptoms and some suggested fixes.
If no login prompt appears, make sure the terminal is plugged in and powered up. If it is a personal computer acting as a terminal, make sure it is running terminal emulation software on the correct serial port.
Make sure the cable is connected firmly to both the terminal and the FreeBSD computer. Make sure it is the right kind of cable.
Make sure the terminal and FreeBSD agree on the bps rate and parity settings. For a video display terminal, make sure the contrast and brightness controls are turned up. If it is a printing terminal, make sure paper and ink are in good supply.
Use ps
to make sure that a
getty
process is running and serving the
terminal. For example, the following listing shows that a
getty
is running on the second serial port,
ttyu1
, and is using the
std.38400
entry in
/etc/gettytab
:
#
ps -axww|grep ttyu
22189 d1 Is+ 0:00.03 /usr/libexec/getty std.38400 ttyu1
If no getty
process is running, make
sure the port is enabled in /etc/ttys
.
Remember to run kill -HUP 1
after modifying
/etc/ttys
.
If the getty
process is running but the
terminal still does not display a login prompt, or if it
displays a prompt but will not accept typed input, the
terminal or cable may not support hardware handshaking. Try
changing the entry in /etc/ttys
from
std.38400
to
3wire.38400
, then run kill -HUP
1
after modifying /etc/ttys
.
The 3wire
entry is similar to
std
, but ignores hardware handshaking. The
baud rate may need to be reduced or software flow control
enabled when using 3wire
to prevent buffer
overflows.
If garbage appears instead of a login prompt, make sure
the terminal and FreeBSD agree on the bps rate
and parity settings. Check the getty
processes to make sure the correct
getty
type is in use. If not, edit
/etc/ttys
and run kill
-HUP 1
.
If characters appear doubled and the password appears when typed, switch the terminal, or the terminal emulation software, from “half duplex” or “local echo” to “full duplex.”
Configuring a FreeBSD system for dial-in service is similar to configuring terminals, except that modems are used instead of terminal devices. FreeBSD supports both external and internal modems.
External modems are more convenient because they often can be configured via parameters stored in non-volatile RAM and they usually provide lighted indicators that display the state of important RS-232 signals, indicating whether the modem is operating properly.
Internal modems usually lack non-volatile RAM, so their configuration may be limited to setting DIP switches. If the internal modem has any signal indicator lights, they are difficult to view when the system's cover is in place.
When using an external modem, a proper cable is needed. A standard RS-232C serial cable should suffice.
FreeBSD needs the RTS and CTS signals for flow control at speeds above 2400 bps, the CD signal to detect when a call has been answered or the line has been hung up, and the DTR signal to reset the modem after a session is complete. Some cables are wired without all of the needed signals, so if a login session does not go away when the line hangs up, there may be a problem with the cable. Refer to Section 26.2.1, “Serial Cables and Ports” for more information about these signals.
Like other UNIX®-like operating systems, FreeBSD uses the hardware signals to find out when a call has been answered or a line has been hung up and to hangup and reset the modem after a call. FreeBSD avoids sending commands to the modem or watching for status reports from the modem.
FreeBSD supports the NS8250, NS16450, NS16550, and NS16550A-based RS-232C (CCITT V.24) communications interfaces. The 8250 and 16450 devices have single-character buffers. The 16550 device provides a 16-character buffer, which allows for better system performance. Bugs in plain 16550 devices prevent the use of the 16-character buffer, so use 16550A devices if possible. Because single-character-buffer devices require more work by the operating system than the 16-character-buffer devices, 16550A-based serial interface cards are preferred. If the system has many active serial ports or will have a heavy load, 16550A-based cards are better for low-error-rate communications.
The rest of this section demonstrates how to configure a modem to receive incoming connections, how to communicate with the modem, and offers some troubleshooting tips.
As with terminals, init
spawns a
getty
process for each configured serial
port used for dial-in connections. When a user dials the
modem's line and the modems connect, the “Carrier
Detect” signal is reported by the modem. The kernel
notices that the carrier has been detected and instructs
getty
to open the port and display a
login:
prompt at the specified initial line
speed. In a typical configuration, if garbage characters are
received, usually due to the modem's connection speed being
different than the configured speed, getty
tries adjusting the line speeds until it receives reasonable
characters. After the user enters their login name,
getty
executes login
,
which completes the login process by asking for the user's
password and then starting the user's shell.
There are two schools of thought regarding dial-up modems. One configuration method is to set the modems and systems so that no matter at what speed a remote user dials in, the dial-in RS-232 interface runs at a locked speed. The benefit of this configuration is that the remote user always sees a system login prompt immediately. The downside is that the system does not know what a user's true data rate is, so full-screen programs like Emacs will not adjust their screen-painting methods to make their response better for slower connections.
The second method is to configure the
RS-232 interface to vary its speed based on
the remote user's connection speed. Because
getty
does not understand any particular
modem's connection speed reporting, it gives a
login:
message at an initial speed and
watches the characters that come back in response. If the
user sees junk, they should press Enter until
they see a recognizable prompt. If the data rates do not
match, getty
sees anything the user types
as junk, tries the next speed, and gives the
login:
prompt again. This procedure normally
only takes a keystroke or two before the user sees a good
prompt. This login sequence does not look as clean as the
locked-speed method, but a user on a low-speed connection
should receive better interactive response from full-screen
programs.
When locking a modem's data communications rate at a
particular speed, no changes to
/etc/gettytab
should be needed. However,
for a matching-speed configuration, additional entries may be
required in order to define the speeds to use for the modem.
This example configures a 14.4 Kbps modem with a top
interface speed of 19.2 Kbps using 8-bit, no parity
connections. It configures getty
to start
the communications rate for a V.32bis connection at
19.2 Kbps, then cycles through 9600 bps,
2400 bps, 1200 bps, 300 bps, and back to
19.2 Kbps. Communications rate cycling is implemented
with the nx=
(next table) capability. Each
line uses a tc=
(table continuation) entry
to pick up the rest of the settings for a particular data
rate.
# # Additions for a V.32bis Modem # um|V300|High Speed Modem at 300,8-bit:\ :nx=V19200:tc=std.300: un|V1200|High Speed Modem at 1200,8-bit:\ :nx=V300:tc=std.1200: uo|V2400|High Speed Modem at 2400,8-bit:\ :nx=V1200:tc=std.2400: up|V9600|High Speed Modem at 9600,8-bit:\ :nx=V2400:tc=std.9600: uq|V19200|High Speed Modem at 19200,8-bit:\ :nx=V9600:tc=std.19200:
For a 28.8 Kbps modem, or to take advantage of compression on a 14.4 Kbps modem, use a higher communications rate, as seen in this example:
# # Additions for a V.32bis or V.34 Modem # Starting at 57.6 Kbps # vm|VH300|Very High Speed Modem at 300,8-bit:\ :nx=VH57600:tc=std.300: vn|VH1200|Very High Speed Modem at 1200,8-bit:\ :nx=VH300:tc=std.1200: vo|VH2400|Very High Speed Modem at 2400,8-bit:\ :nx=VH1200:tc=std.2400: vp|VH9600|Very High Speed Modem at 9600,8-bit:\ :nx=VH2400:tc=std.9600: vq|VH57600|Very High Speed Modem at 57600,8-bit:\ :nx=VH9600:tc=std.57600:
For a slow CPU or a heavily loaded system without 16550A-based serial ports, this configuration may produce sio “silo” errors at 57.6 Kbps.
The configuration of /etc/ttys
is
similar to Example 26.1, “Configuring Terminal Entries”, but a different
argument is passed to getty
and
dialup
is used for the terminal type.
Replace xxx
with the process
init
will run on the device:
ttyu0 "/usr/libexec/getty xxx
" dialup on
The dialup
terminal type can be
changed. For example, setting vt102
as the
default terminal type allows users to use
VT102 emulation on their remote
systems.
For a locked-speed configuration, specify the speed with
a valid type listed in /etc/gettytab
.
This example is for a modem whose port speed is locked at
19.2 Kbps:
ttyu0 "/usr/libexec/getty std.19200
" dialup on
In a matching-speed configuration, the entry needs to
reference the appropriate beginning “auto-baud”
entry in /etc/gettytab
. To continue the
example for a matching-speed modem that starts at
19.2 Kbps, use this entry:
ttyu0 "/usr/libexec/getty V19200" dialup on
After editing /etc/ttys
, wait until
the modem is properly configured and connected before
signaling init
:
#
kill -HUP 1
High-speed modems, like V.32,
V.32bis, and V.34
modems, use hardware (RTS/CTS
) flow
control. Use stty
to set the hardware flow
control flag for the modem port. This example sets the
crtscts
flag on COM2
's
dial-in and dial-out initialization devices:
#
stty -f /dev/ttyu1.init crtscts
#
stty -f /dev/cuau1.init crtscts
This section provides a few tips for troubleshooting a dial-up modem that will not connect to a FreeBSD system.
Hook up the modem to the FreeBSD system and boot the system.
If the modem has status indication lights, watch to see
whether the modem's DTR indicator lights
when the login:
prompt appears on the
system's console. If it lights up, that should mean that FreeBSD
has started a getty
process on the
appropriate communications port and is waiting for the modem
to accept a call.
If the DTR indicator does not light,
login to the FreeBSD system through the console and type
ps ax
to see if FreeBSD is running a
getty
process on the correct port:
114 ?? I 0:00.10 /usr/libexec/getty V19200 ttyu0
If the second column contains a d0
instead of a ??
and the modem has not
accepted a call yet, this means that getty
has completed its open on the communications port. This could
indicate a problem with the cabling or a misconfigured modem
because getty
should not be able to open
the communications port until the carrier detect signal has
been asserted by the modem.
If no getty
processes are waiting to
open the port, double-check that the entry for the port is
correct in /etc/ttys
. Also, check
/var/log/messages
to see if there are
any log messages from init
or
getty
.
Next, try dialing into the system. Be sure to use 8 bits,
no parity, and 1 stop bit on the remote system. If a prompt
does not appear right away, or the prompt shows garbage, try
pressing Enter about once per second. If
there is still no login:
prompt,
try sending a BREAK
. When using a
high-speed modem, try dialing again after locking the
dialing modem's interface speed.
If there is still no login:
prompt, check
/etc/gettytab
again and double-check
that:
The initial capability name specified in the entry in
/etc/ttys
matches the name of a
capability in /etc/gettytab
.
Each nx=
entry matches another
gettytab
capability name.
Each tc=
entry matches another
gettytab
capability name.
If the modem on the FreeBSD system will not answer, make sure that the modem is configured to answer the phone when DTR is asserted. If the modem seems to be configured correctly, verify that the DTR line is asserted by checking the modem's indicator lights.
If it still does not work, try sending an email to the FreeBSD general questions mailing list describing the modem and the problem.
The following are tips for getting the host to connect over the modem to another computer. This is appropriate for establishing a terminal session with a remote host.
This kind of connection can be helpful to get a file on the Internet if there are problems using PPP. If PPP is not working, use the terminal session to FTP the needed file. Then use zmodem to transfer it to the machine.
A generic Hayes dialer is built into
tip
. Use at=hayes
in
/etc/remote
.
The Hayes driver is not smart enough to recognize some of
the advanced features of newer modems messages like
BUSY
, NO DIALTONE
, or
CONNECT 115200
. Turn those messages off
when using tip
with
ATX0&W
.
The dial timeout for tip
is 60
seconds. The modem should use something less, or else
tip
will think there is a communication
problem. Try ATS7=45&W
.
Create a “direct” entry in
/etc/remote
. For example, if the modem
is hooked up to the first serial port,
/dev/cuau0
, use the following
line:
cuau0:dv=/dev/cuau0:br#19200:pa=none
Use the highest bps rate the modem
supports in the br
capability. Then, type
tip cuau0
to connect to the modem.
Or, use cu
as root
with the following
command:
#
cu -l
line
-sspeed
line
is the serial port, such
as /dev/cuau0
, and
speed
is the speed, such as
57600
. When finished entering the AT
commands, type ~.
to exit.
The @
sign in the phone number
capability tells tip
to look in
/etc/phones
for a phone number. But, the
@
sign is also a special character in
capability files like /etc/remote
, so it
needs to be escaped with a backslash:
pn=\@
Put a “generic” entry in
/etc/remote
. For example:
tip115200|Dial any phone number at 115200 bps:\ :dv=/dev/cuau0:br#115200:at=hayes:pa=none:du: tip57600|Dial any phone number at 57600 bps:\ :dv=/dev/cuau0:br#57600:at=hayes:pa=none:du:
This should now work:
#
tip -115200 5551234
Users who prefer cu
over
tip
, can use a generic
cu
entry:
cu115200|Use cu to dial any number at 115200bps:\ :dv=/dev/cuau1:br#57600:at=hayes:pa=none:du:
and type:
#
cu 5551234 -s 115200
Put in an entry for tip1200
or
cu1200
, but go ahead and use whatever
bps rate is appropriate with the
br
capability.
tip
thinks a good default is 1200 bps
which is why it looks for a tip1200
entry.
1200 bps does not have to be used, though.
Rather than waiting until connected and typing
CONNECT
each time, use host
tip
's cm
capability. For example, these entries in
/etc/remote
will let you type
tip pain
or tip muffin
to connect to the hosts pain
or
muffin
, and tip
deep13
to connect to the terminal server.
pain|pain.deep13.com|Forrester's machine:\ :cm=CONNECT pain\n:tc=deep13: muffin|muffin.deep13.com|Frank's machine:\ :cm=CONNECT muffin\n:tc=deep13: deep13:Gizmonics Institute terminal server:\ :dv=/dev/cuau2:br#38400:at=hayes:du:pa=none:pn=5551234:
This is often a problem where a university has several modem lines and several thousand students trying to use them.
Make an entry in /etc/remote
and use
@
for the pn
capability:
big-university:\ :pn=\@:tc=dialout dialout:\ :dv=/dev/cuau3:br#9600:at=courier:du:pa=none:
Then, list the phone numbers in
/etc/phones
:
big-university 5551111 big-university 5551112 big-university 5551113 big-university 5551114
tip
will try each number in the listed
order, then give up. To keep retrying, run
tip
in a while
loop.
Ctrl+P is the default “force” character,
used to tell tip
that the next character is
literal data. The force character can be set to any other
character with the ~s
escape, which means
“set a variable.”
Type
~sforce=
followed by a newline. single-char
single-char
is any single character. If
single-char
is left out, then the
force character is the null character, which is accessed by
typing
Ctrl+2
or Ctrl+Space. A pretty good value for
single-char
is
Shift+Ctrl+6, which is only used on some terminal
servers.
To change the force character, specify the following in
~/.tiprc
:
force=single-char
This happens when
Ctrl+A is pressed, which is tip
's
“raise character”, specially designed for people
with broken caps-lock keys. Use ~s
to set
raisechar
to something reasonable. It can
be set to be the same as the force character, if neither
feature is used.
Here is a sample ~/.tiprc
for
Emacs users who need to type
Ctrl+2 and Ctrl+A:
force=^^ raisechar=^^
The ^^
is
Shift+Ctrl+6.
When talking to another UNIX®-like operating system,
files can be sent and received using ~p
(put) and ~t
(take). These commands run
cat
and echo
on the
remote system to accept and send files. The syntax is:
~p
local-file [remote-file]
~t
remote-file [local-file]
There is no error checking, so another protocol, like zmodem, should probably be used.
FreeBSD has the ability to boot a system with a dumb terminal on a serial port as a console. This configuration is useful for system administrators who wish to install FreeBSD on machines that have no keyboard or monitor attached, and developers who want to debug the kernel or device drivers.
As described in Chapter 12, The FreeBSD Booting Process, FreeBSD employs a three stage bootstrap. The first two stages are in the boot block code which is stored at the beginning of the FreeBSD slice on the boot disk. The boot block then loads and runs the boot loader as the third stage code.
In order to set up booting from a serial console, the boot block code, the boot loader code, and the kernel need to be configured.
This section provides a fast overview of setting up the
serial console. This procedure can be used when the dumb
terminal is connected to COM1
.
COM1
Connect the serial cable to
COM1
and the controlling
terminal.
To configure boot messages to display on the serial console, issue the following command as the superuser:
#
sysrc -f /boot/loader.conf console=comconsole
Edit /etc/ttys
and change
off
to on
and
dialup
to vt100
for
the ttyu0
entry. Otherwise, a
password will not be required to connect via the serial
console, resulting in a potential security hole.
Reboot the system to see if the changes took effect.
If a different configuration is required, see the next section for a more in-depth configuration explanation.
This section provides a more detailed explanation of the steps needed to setup a serial console in FreeBSD.
Prepare a serial cable.
Use either a null-modem cable or a standard serial cable and a null-modem adapter. See Section 26.2.1, “Serial Cables and Ports” for a discussion on serial cables.
Unplug the keyboard.
Many systems probe for the keyboard during the Power-On Self-Test (POST) and will generate an error if the keyboard is not detected. Some machines will refuse to boot until the keyboard is plugged in.
If the computer complains about the error, but boots anyway, no further configuration is needed.
If the computer refuses to boot without a keyboard attached, configure the BIOS so that it ignores this error. Consult the motherboard's manual for details on how to do this.
Try setting the keyboard to “Not installed” in the BIOS. This setting tells the BIOS not to probe for a keyboard at power-on so it should not complain if the keyboard is absent. If that option is not present in the BIOS, look for an “Halt on Error” option instead. Setting this to “All but Keyboard” or to “No Errors” will have the same effect.
If the system has a PS/2® mouse, unplug it as well. PS/2® mice share some hardware with the keyboard and leaving the mouse plugged in can fool the keyboard probe into thinking the keyboard is still there.
While most systems will boot without a keyboard, quite a few will not boot without a graphics adapter. Some systems can be configured to boot with no graphics adapter by changing the “graphics adapter” setting in the BIOS configuration to “Not installed”. Other systems do not support this option and will refuse to boot if there is no display hardware in the system. With these machines, leave some kind of graphics card plugged in, even if it is just a junky mono board. A monitor does not need to be attached.
Plug a dumb terminal, an old computer with a modem program, or the serial port on another UNIX® box into the serial port.
Add the appropriate hint.sio.*
entries to /boot/device.hints
for the
serial port. Some multi-port cards also require kernel
configuration options. Refer to sio(4) for the
required options and device hints for each supported
serial port.
Create boot.config
in the root
directory of the a
partition on the
boot drive.
This file instructs the boot block code how to boot the system. In order to activate the serial console, one or more of the following options are needed. When using multiple options, include them all on the same line:
-h
Toggles between the internal and serial
consoles. Use this to switch console devices. For
instance, to boot from the internal (video) console,
use -h
to direct the boot loader
and the kernel to use the serial port as its console
device. Alternatively, to boot from the serial
port, use -h
to tell the boot
loader and the kernel to use the video display as
the console instead.
-D
Toggles between the single and dual console
configurations. In the single configuration, the
console will be either the internal console (video
display) or the serial port, depending on the state
of -h
. In the dual console
configuration, both the video display and the
serial port will become the console at the same
time, regardless of the state of
-h
. However, the dual console
configuration takes effect only while the boot
block is running. Once the boot loader gets
control, the console specified by
-h
becomes the only
console.
-P
Makes the boot block probe the keyboard. If no
keyboard is found, the -D
and
-h
options are automatically
set.
Due to space constraints in the current
version of the boot blocks, -P
is
capable of detecting extended keyboards only.
Keyboards with less than 101 keys and without F11
and F12 keys may not be detected. Keyboards on
some laptops may not be properly found because of
this limitation. If this is the case, do not use
-P
.
Use either -P
to select the console
automatically or -h
to activate the
serial console. Refer to boot(8) and
boot.config(5) for more details.
The options, except for -P
, are
passed to the boot loader. The boot loader will
determine whether the internal video or the serial port
should become the console by examining the state of
-h
. This means that if
-D
is specified but -h
is not specified in /boot.config
, the
serial port can be used as the console only during the
boot block as the boot loader will use the internal video
display as the console.
Boot the machine.
When FreeBSD starts, the boot blocks echo the contents of
/boot.config
to the console. For
example:
/boot.config: -P Keyboard: no
The second line appears only if -P
is
in /boot.config
and indicates the
presence or absence of the keyboard. These messages go
to either the serial or internal console, or both,
depending on the option in
/boot.config
:
Options | Message goes to |
---|---|
none | internal console |
-h | serial console |
-D | serial and internal consoles |
-Dh | serial and internal consoles |
-P , keyboard present | internal console |
-P , keyboard absent | serial console |
After the message, there will be a small pause before the boot blocks continue loading the boot loader and before any further messages are printed to the console. Under normal circumstances, there is no need to interrupt the boot blocks, but one can do so in order to make sure things are set up correctly.
Press any key, other than Enter, at the console to interrupt the boot process. The boot blocks will then prompt for further action:
>> FreeBSD/i386 BOOT Default: 0:ad(0,a)/boot/loader boot:
Verify that the above message appears on either the
serial or internal console, or both, according to the
options in /boot.config
. If the
message appears in the correct console, press
Enter to continue the boot
process.
If there is no prompt on the serial terminal,
something is wrong with the settings. Enter
-h
then Enter or
Return to tell the boot block (and then
the boot loader and the kernel) to choose the serial port
for the console. Once the system is up, go back and check
what went wrong.
During the third stage of the boot process, one can still switch between the internal console and the serial console by setting appropriate environment variables in the boot loader. See loader(8) for more information.
This line in /boot/loader.conf
or
/boot/loader.conf.local
configures the
boot loader and the kernel to send their boot messages to
the serial console, regardless of the options in
/boot.config
:
console="comconsole"
That line should be the first line of
/boot/loader.conf
so that boot messages
are displayed on the serial console as early as
possible.
If that line does not exist, or if it is set to
console="vidconsole"
, the boot loader and
the kernel will use whichever console is indicated by
-h
in the boot block. See
loader.conf(5) for more information.
At the moment, the boot loader has no option
equivalent to -P
in the boot block, and
there is no provision to automatically select the internal
console and the serial console based on the presence of the
keyboard.
While it is not required, it is possible to provide a
login
prompt over the serial line. To
configure this, edit the entry for the serial port in
/etc/ttys
using the instructions in
Section 26.3.1, “Terminal Configuration”. If the speed of the serial
port has been changed, change std.9600
to
match the new setting.
By default, the serial port settings are 9600 baud, 8 bits, no parity, and 1 stop bit. To change the default console speed, use one of the following options:
Edit /etc/make.conf
and set
BOOT_COMCONSOLE_SPEED
to the new
console speed. Then, recompile and install the boot
blocks and the boot loader:
#
cd /sys/boot
#
make clean
#
make
#
make install
If the serial console is configured in some other way
than by booting with -h
, or if the serial
console used by the kernel is different from the one used
by the boot blocks, add the following option, with the
desired speed, to a custom kernel configuration file and
compile a new kernel:
options CONSPEED=19200
Add the
-S
boot
option to 19200
/boot.config
, replacing
19200
with the speed to
use.
Add the following options to
/boot/loader.conf
. Replace
115200
with the speed to
use.
boot_multicons="YES"
boot_serial="YES"
comconsole_speed="115200
"
console="comconsole,vidconsole"
To configure the ability to drop into the kernel debugger from the serial console, add the following options to a custom kernel configuration file and compile the kernel using the instructions in Chapter 8, Configuring the FreeBSD Kernel. Note that while this is useful for remote diagnostics, it is also dangerous if a spurious BREAK is generated on the serial port. Refer to ddb(4) and ddb(8) for more information about the kernel debugger.
options BREAK_TO_DEBUGGER options DDB
FreeBSD supports the Point-to-Point (PPP) protocol which can be used to establish a network or Internet connection using a dial-up modem. This chapter describes how to configure modem-based communication services in FreeBSD.
After reading this chapter, you will know:
How to configure, use, and troubleshoot a PPP connection.
How to set up PPP over Ethernet (PPPoE).
How to set up PPP over ATM (PPPoA).
Before reading this chapter, you should:
Be familiar with basic network terminology.
Understand the basics and purpose of a dial-up connection and PPP.
FreeBSD provides built-in support for managing dial-up
PPP connections using ppp(8). The
default FreeBSD kernel provides support for
tun
which is used to interact with a
modem hardware. Configuration is performed by editing at least
one configuration file, and configuration files containing
examples are provided. Finally, ppp
is
used to start and manage connections.
In order to use a PPP connection, the following items are needed:
A dial-up account with an Internet Service Provider (ISP).
A dial-up modem.
The dial-up number for the ISP.
The login name and password assigned by the ISP.
The IP address of one or more DNS servers. Normally, the ISP provides these addresses. If it did not, FreeBSD can be configured to use DNS negotiation.
If any of the required information is missing, contact the ISP.
The following information may be supplied by the ISP, but is not necessary:
The IP address of the default
gateway. If this information is unknown, the
ISP will automatically provide the
correct value during connection setup. When configuring
PPP on FreeBSD, this address is referred to
as HISADDR
.
The subnet mask. If the ISP has not
provided one, 255.255.255.255
will be used
in the ppp(8) configuration file.
If the ISP has assigned a static IP address and hostname, it should be input into the configuration file. Otherwise, this information will be automatically provided during connection setup.
The rest of this section demonstrates how to configure FreeBSD
for common PPP connection scenarios. The
required configuration file is
/etc/ppp/ppp.conf
and additional files and
examples are available in
/usr/share/examples/ppp/
.
Throughout this section, many of the file examples display line numbers. These line numbers have been added to make it easier to follow the discussion and are not meant to be placed in the actual file.
When editing a configuration file, proper indentation is
important. Lines that end in a :
start in
the first column (beginning of the line) while all other lines
should be indented as shown using spaces or tabs.
In order to configure a PPP connection,
first edit /etc/ppp/ppp.conf
with the
dial-in information for the ISP. This file
is described as follows:
1 default: 2 set log Phase Chat LCP IPCP CCP tun command 3 ident user-ppp VERSION 4 set device /dev/cuau0 5 set speed 115200 6 set dial "ABORT BUSY ABORT NO\\sCARRIER TIMEOUT 5 \ 7 \"\" AT OK-AT-OK ATE1Q0 OK \\dATDT\\T TIMEOUT 40 CONNECT" 8 set timeout 180 9 enable dns 10 11 provider: 12 set phone "(123) 456 7890" 13 set authname foo 14 set authkey bar 15 set timeout 300 16 set ifaddrx.x.x.x
/0y.y.y.y
/0 255.255.255.255 0.0.0.0 17 add default HISADDR
Identifies the default
entry.
Commands in this entry (lines 2 through 9) are
executed automatically when ppp
is run.
Enables verbose logging parameters for testing the connection. Once the configuration is working satisfactorily, this line should be reduced to:
set log phase tun
Displays the version of ppp(8) to the PPP software running on the other side of the connection.
Identifies the device to which the modem is
connected, where COM1
is
/dev/cuau0
and
COM2
is
/dev/cuau1
.
Sets the connection speed. If
115200
does not work on an older
modem, try 38400
instead.
The dial string written as an expect-send syntax. Refer to chat(8) for more information.
Note that this command continues onto the next
line for readability. Any command in
ppp.conf
may do this if the
last character on the line is
\
.
Sets the idle timeout for the link in seconds.
Instructs the peer to confirm the
DNS settings. If the local
network is running its own DNS
server, this line should be commented out, by adding
a #
at the beginning of the line,
or removed.
A blank line for readability. Blank lines are ignored by ppp(8).
Identifies an entry called
provider
. This could be changed
to the name of the ISP so that
load
can be
used to start the connection.ISP
Use the phone number for the
ISP. Multiple phone numbers may
be specified using the colon (:
)
or pipe character (|
) as a
separator. To rotate through the numbers, use a
colon. To always attempt to dial the first number
first and only use the other numbers if the first
number fails, use the pipe character. Always
enclose the entire set of phone numbers between
quotation marks ("
) to prevent
dialing failures.
Use the user name and password for the ISP.
Sets the default idle timeout in seconds for the connection. In this example, the connection will be closed automatically after 300 seconds of inactivity. To prevent a timeout, set this value to zero.
Sets the interface addresses. The values used depend upon whether a static IP address has been obtained from the ISP or if it instead negotiates a dynamic IP address during connection.
If the ISP has allocated a
static IP address and default
gateway, replace x.x.x.x
with the static IP address and
replace y.y.y.y
with the
IP address of the default
gateway. If the ISP has only
provided a static IP address
without a gateway address, replace
y.y.y.y
with 10.0.0.2/0
.
If the IP address changes whenever a connection is made, change this line to the following value. This tells ppp(8) to use the IP Configuration Protocol (IPCP) to negotiate a dynamic IP address:
set ifaddr 10.0.0.1/0 10.0.0.2/0 255.255.255.255 0.0.0.0
Keep this line as-is as it adds a default route
to the gateway. The HISADDR
will
automatically be replaced with the gateway address
specified on line 16. It is important that this
line appears after line 16.
Depending upon whether ppp(8) is started
manually or automatically, a
/etc/ppp/ppp.linkup
may also need to
be created which contains the following lines. This file
is required when running ppp
in
-auto
mode. This file is used after the
connection has been established. At this point, the
IP address will have been assigned and
it is now be possible to add the routing table entries.
When creating this file, make sure that
provider
matches the value
demonstrated in line 11 of
ppp.conf
.
provider: add default HISADDR
This file is also needed when the default gateway
address is “guessed” in a static
IP address configuration. In this case,
remove line 17 from ppp.conf
and
create /etc/ppp/ppp.linkup
with the
above two lines. More examples for this file can be found
in /usr/share/examples/ppp/
.
By default, ppp
must be
run as root
.
To change this default, add the account of the user
who should run ppp
to the network
group in
/etc/group
.
Then, give the user access to one or more entries in
/etc/ppp/ppp.conf
with
allow
. For example, to give
fred
and
mary
permission to only the provider:
entry,
add this line to the provider:
section:
allow users fred mary
To give the specified users access to all entries, put
that line in the default
section
instead.
It is possible to configure PPP to supply DNS and NetBIOS nameserver addresses on demand.
To enable these extensions with
PPP version 1.x, the following lines
might be added to the relevant section of
/etc/ppp/ppp.conf
.
enable msext set ns 203.14.100.1 203.14.100.2 set nbns 203.14.100.5
And for PPP version 2 and above:
accept dns set dns 203.14.100.1 203.14.100.2 set nbns 203.14.100.5
This will tell the clients the primary and secondary name server addresses, and a NetBIOS nameserver host.
In version 2 and above, if the set
dns
line is omitted,
PPP will use the values found in
/etc/resolv.conf
.
Some ISPs set their system up so
that the authentication part of the connection is done
using either of the PAP or CHAP authentication mechanisms.
If this is the case, the ISP will not
give a login:
prompt at connection, but
will start talking PPP
immediately.
PAP is less secure than CHAP, but security is not normally an issue here as passwords, although being sent as plain text with PAP, are being transmitted down a serial line only. There is not much room for crackers to “eavesdrop”.
The following alterations must be made:
13 set authnameMyUserName
14 set authkeyMyPassword
15 set login
This line specifies the PAP/CHAP user name.
Insert the correct value for
MyUserName
.
This line specifies the PAP/CHAP
password.
Insert the correct value for
MyPassword
. You may
want to add an additional line, such as:
16 accept PAP
or
16 accept CHAP
to make it obvious that this is the intention, but PAP and CHAP are both accepted by default.
The ISP will not normally require a login to the server when using PAP or CHAP. Therefore, disable the “set login” string.
PPP has ability to use internal NAT without kernel
diverting capabilities. This functionality may be enabled
by the following line in
/etc/ppp/ppp.conf
:
nat enable yes
Alternatively, NAT may be enabled by command-line
option -nat
. There is also
/etc/rc.conf
knob named
ppp_nat
, which is enabled by
default.
When using this feature, it may be useful to include
the following /etc/ppp/ppp.conf
options
to enable incoming connections forwarding:
nat port tcp 10.0.0.2:ftp ftp nat port tcp 10.0.0.2:http http
or do not trust the outside at all
nat deny_incoming yes
While ppp
is now configured,
some edits still need to be made to
/etc/rc.conf
.
Working from the top down in this file, make sure the
hostname=
line is set:
hostname="foo.example.com"
If the ISP has supplied a static IP address and name, use this name as the host name.
Look for the network_interfaces
variable. To configure the system to dial the
ISP on demand, make sure the
tun0
device is added to the list,
otherwise remove it.
network_interfaces="lo0 tun0" ifconfig_tun0=
The ifconfig_tun0
variable should
be empty, and a file called
/etc/start_if.tun0
should be created.
This file should contain the line:
ppp -auto mysystem
This script is executed at network configuration time,
starting the ppp daemon in automatic mode. If this
machine acts as a gateway, consider including
-alias
. Refer to the manual page for
further details.
Make sure that the router program is set to
NO
with the following line in
/etc/rc.conf
:
router_enable="NO"
It is important that the routed
daemon is not started, as routed
tends
to delete the default routing table entries created by
ppp
.
It is probably a good idea to ensure that the
sendmail_flags
line does not include the
-q
option, otherwise
sendmail
will attempt to do a network
lookup every now and then, possibly causing your machine
to dial out. You may try:
sendmail_flags="-bd"
The downside is that sendmail
is
forced to re-examine the mail queue whenever the ppp link.
To automate this, include !bg
in
ppp.linkup
:
1 provider: 2 delete ALL 3 add 0 0 HISADDR 4 !bg sendmail -bd -q30m
An alternative is to set up a “dfilter” to block SMTP traffic. Refer to the sample files for further details.
All that is left is to reboot the machine. After rebooting, either type:
#
ppp
and then dial provider
to start the
PPP session, or, to configure
ppp
to establish sessions automatically
when there is outbound traffic and
start_if.tun0
does not exist,
type:
#
ppp -auto provider
It is possible to talk to the ppp
program while it is running in the background, but only
if a suitable diagnostic port has been set up. To do
this, add the following line to the configuration:
set server /var/run/ppp-tun%d
DiagnosticPassword 0177
This will tell PPP to listen to the specified
UNIX® domain socket, asking clients for the specified
password before allowing access. The
%d
in the name is replaced with the
tun
device number that is in
use.
Once a socket has been set up, the pppctl(8) program may be used in scripts that wish to manipulate the running program.
Section 26.4, “Dial-in Service” provides a good description on enabling dial-up services using getty(8).
An alternative to getty
is
comms/mgetty+sendfax
port), a smarter version of getty
designed with dial-up lines in mind.
The advantages of using mgetty
is
that it actively talks to modems,
meaning if port is turned off in
/etc/ttys
then the modem will not
answer the phone.
Later versions of mgetty
(from
0.99beta onwards) also support the automatic detection of
PPP streams, allowing clients
scriptless access to the server.
Refer to http://mgetty.greenie.net/doc/mgetty_toc.html
for more information on mgetty
.
By default the comms/mgetty+sendfax
port comes with the AUTO_PPP
option
enabled allowing mgetty
to detect the
LCP phase of PPP connections and
automatically spawn off a ppp shell. However, since the
default login/password sequence does not occur it is
necessary to authenticate users using either PAP or
CHAP.
This section assumes the user has successfully compiled, and installed the comms/mgetty+sendfax port on his system.
Ensure that
/usr/local/etc/mgetty+sendfax/login.config
has the following:
/AutoPPP/ - - /etc/ppp/ppp-pap-dialup
This tells mgetty
to run
ppp-pap-dialup
for detected
PPP connections.
Create an executable file called
/etc/ppp/ppp-pap-dialup
containing
the following:
#!/bin/sh exec /usr/sbin/ppp -direct pap$IDENT
For each dial-up line enabled in
/etc/ttys
, create a corresponding
entry in /etc/ppp/ppp.conf
. This
will happily co-exist with the definitions we created
above.
pap: enable pap set ifaddr 203.14.100.1 203.14.100.20-203.14.100.40 enable proxy
Each user logging in with this method will need to
have a username/password in
/etc/ppp/ppp.secret
, or
alternatively add the following option to authenticate
users via PAP from
/etc/passwd
.
enable passwdauth
To assign some users a static IP
number, specify the number as the third argument in
/etc/ppp/ppp.secret
. See
/usr/share/examples/ppp/ppp.secret.sample
for examples.
This section covers a few issues which may arise when
using PPP over a modem connection. Some
ISPs present the
ssword
prompt while others present
password
. If the ppp
script is not written accordingly, the login attempt will
fail. The most common way to debug ppp
connections is by connecting manually as described in this
section.
When using a custom kernel, make sure to include the following line in the kernel configuration file:
device uart
The uart
device is already
included in the GENERIC
kernel, so no
additional steps are necessary in this case. Just
check the dmesg
output for the modem
device with:
#
dmesg | grep uart
This should display some pertinent output about the
uart
devices. These are the COM
ports we need. If the modem acts like a standard serial port,
it should be listed on uart1
, or
COM2
. If so, a kernel rebuild is not
required. When matching up, if the modem is on
uart1
, the modem device would be
/dev/cuau1
.
Connecting to the Internet by manually controlling
ppp
is quick, easy, and a great way to
debug a connection or just get information on how the
ISP treats ppp
client
connections. Lets start PPP from
the command line. Note that in all of our examples we will
use example as the hostname of the
machine running PPP. To start
ppp
:
#
ppp
ppp ON example> set device /dev/cuau1
This second command sets the modem device to
cuau1
.
ppp ON example> set speed 115200
This sets the connection speed to 115,200 kbps.
ppp ON example> enable dns
This tells ppp
to configure the
resolver and add the nameserver lines to
/etc/resolv.conf
. If
ppp
cannot determine the hostname, it can
manually be set later.
ppp ON example> term
This switches to “terminal” mode in order to manually control the modem.
deflink: Entering terminal mode on /dev/cuau1
type '~h' for help
at
OKatdt
123456789
Use at
to initialize the modem, then
use atdt
and the number for the
ISP to begin the dial in process.
CONNECT
Confirmation of the connection, if we are going to have any connection problems, unrelated to hardware, here is where we will attempt to resolve them.
ISP Login:myusername
At this prompt, return the prompt with the username that was provided by the ISP.
ISP Pass:mypassword
At this prompt, reply with the password that was provided by the ISP. Just like logging into FreeBSD, the password will not echo.
Shell or PPP:ppp
Depending on the ISP, this prompt
might not appear. If it does, it is asking whether to use a
shell on the provider or to start
ppp
. In this example,
ppp
was selected in order to establish an
Internet connection.
Ppp ON example>
Notice that in this example the first p
has been capitalized. This shows that we have successfully
connected to the ISP.
PPp ON example>
We have successfully authenticated with our ISP and are waiting for the assigned IP address.
PPP ON example>
We have made an agreement on an IP address and successfully completed our connection.
PPP ON example>add default HISADDR
Here we add our default route, we need to do this before
we can talk to the outside world as currently the only
established connection is with the peer. If this fails due to
existing routes, put a bang character
!
in front of the add
.
Alternatively, set this before making the actual
connection and it will negotiate a new route
accordingly.
If everything went good we should now have an active
connection to the Internet, which could be thrown into the
background using CTRL+z If PPP
returns to ppp
then the connection has bee
lost. This is good to know because it shows the connection
status. Capital P's represent a connection to the
ISP and lowercase p's show that the
connection has been lost.
If a connection cannot be established, turn hardware
flow CTS/RTS to off using set
ctsrts off
. This is mainly the case when
connected to some PPP-capable
terminal servers, where PPP hangs
when it tries to write data to the communication link, and
waits for a Clear To Send (CTS) signal
which may never come. When using this option, include
set accmap
as it may be required to defeat
hardware dependent on passing certain characters from end to
end, most of the time XON/XOFF. Refer to ppp(8) for
more information on this option and how it is used.
An older modem may need set parity
even
. Parity is set at none be default, but is
used for error checking with a large increase in traffic,
on older modems.
PPP may not return to the
command mode, which is usually a negotiation error where the
ISP is waiting for negotiating to begin.
At this point, using ~p
will force ppp
to start sending the configuration information.
If a login prompt never appears, PAP or CHAP authentication is most likely required. To use PAP or CHAP, add the following options to PPP before going into terminal mode:
ppp ON example> set authname myusername
Where myusername
should be
replaced with the username that was assigned by the
ISP.
ppp ON example> set authkey mypassword
Where mypassword
should be
replaced with the password that was assigned by the
ISP.
If a connection is established, but cannot seem to find
any domain name, try to ping(8) an
IP address. If there is 100 percent
(100%) packet loss, it is likely that a default route was
not assigned. Double check that add default
HISADDR
was set during the connection. If a
connection can be made to a remote IP
address, it is possible that a resolver address has not been
added to /etc/resolv.conf
. This file
should look like:
domainexample.com
nameserverx.x.x.x
nameservery.y.y.y
Where x.x.x.x
and
y.y.y.y
should be replaced with
the IP address of the
ISP's DNS servers.
To configure syslog(3) to provide logging for the
PPP connection, make sure this
line exists in /etc/syslog.conf
:
!ppp *.* /var/log/ppp.log
This section describes how to set up PPP over Ethernet (PPPoE).
Here is an example of a working
ppp.conf
:
default:
set log Phase tun command # you can add more detailed logging if you wish
set ifaddr 10.0.0.1/0 10.0.0.2/0
name_of_service_provider:
set device PPPoE:xl1
# replace xl1 with your Ethernet device
set authname YOURLOGINNAME
set authkey YOURPASSWORD
set dial
set login
add default HISADDR
As root
,
run:
#
ppp -ddial name_of_service_provider
Add the following to
/etc/rc.conf
:
ppp_enable="YES" ppp_mode="ddial" ppp_nat="YES" # if you want to enable nat for your local network, otherwise NO ppp_profile="name_of_service_provider"
Sometimes it will be necessary to use a service tag to establish the connection. Service tags are used to distinguish between different PPPoE servers attached to a given network.
Any required service tag information should be in the documentation provided by the ISP.
As a last resort, one could try installing the net/rr-pppoe package or port. Bear in mind however, this may de-program your modem and render it useless, so think twice before doing it. Simply install the program shipped with the modem. Then, access the menu from the program. The name of the profile should be listed there. It is usually ISP.
The profile name (service tag) will be used in the PPPoE
configuration entry in ppp.conf
as the
provider part for set device
. Refer to
ppp(8) for full details. It should look like
this:
set device PPPoE:xl1
:ISP
Do not forget to change xl1
to
the proper device for the Ethernet card.
Do not forget to change ISP
to
the profile.
For additional information, refer to Cheaper Broadband with FreeBSD on DSL by Renaud Waldura.
This modem does not follow the PPPoE specification defined in RFC 2516.
In order to make FreeBSD capable of communicating with this
device, a sysctl must be set. This can be done automatically
at boot time by updating
/etc/sysctl.conf
:
net.graph.nonstandard_pppoe=1
or can be done immediately with the command:
#
sysctl net.graph.nonstandard_pppoe=1
Unfortunately, because this is a system-wide setting, it is not possible to talk to a normal PPPoE client or server and a 3Com® HomeConnect® ADSL Modem at the same time.
The following describes how to set up PPP over ATM (PPPoA). PPPoA is a popular choice among European DSL providers.
The mpd application can be used to connect to a variety of services, in particular PPTP services. It can be installed using the net/mpd5 package or port. Many ADSL modems require that a PPTP tunnel is created between the modem and computer.
Once installed, configure mpd
to suit the provider's settings. The port places a set of
sample configuration files which are well documented in
/usr/local/etc/mpd/
. A complete guide to
configure mpd is available in HTML
format in /usr/ports/share/doc/mpd/
.
Here is a sample configuration for connecting to an ADSL
service with mpd. The
configuration is spread over two files, first the
mpd.conf
:
This example mpd.conf
only works
with mpd 4.x.
default: load adsl adsl: new -i ng0 adsl adsl set bundle authnameusername
set bundle passwordpassword
set bundle disable multilink set link no pap acfcomp protocomp set link disable chap set link accept chap set link keep-alive 30 10 set ipcp no vjcomp set ipcp ranges 0.0.0.0/0 0.0.0.0/0 set iface route default set iface disable on-demand set iface enable proxy-arp set iface idle 0 open
Information about the link, or links, to establish is found
in mpd.links
. An example
mpd.links
to accompany the above example
is given beneath:
adsl: set link type pptp set pptp mode active set pptp enable originate outcall set pptp self10.0.0.1
set pptp peer10.0.0.138
The IP address of FreeBSD computer running mpd. | |
The IP address of the ADSL modem.
The Alcatel SpeedTouch™ Home defaults to |
It is possible to initialize the connection easily by
issuing the following command as
root
:
#
mpd -b
adsl
To view the status of the connection:
%
ifconfig
ng0: flags=88d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST> mtu 1500 inet 216.136.204.117 --> 204.152.186.171 netmask 0xffffffffng0
Using mpd is the recommended way to connect to an ADSL service with FreeBSD.
It is also possible to use FreeBSD to connect to other PPPoA services using net/pptpclient.
To use net/pptpclient
to connect to a DSL service, install the port or package, then
edit /etc/ppp/ppp.conf
. An example section
of ppp.conf
is given below. For further
information on ppp.conf
options consult
ppp(8).
adsl: set log phase chat lcp ipcp ccp tun command set timeout 0 enable dns set authnameusername
set authkeypassword
set ifaddr 0 0 add default HISADDR
Since the account's password is added to
ppp.conf
in plain text form, make sure
nobody can read the contents of this file:
#
chown root:wheel /etc/ppp/ppp.conf
#
chmod 600 /etc/ppp/ppp.conf
This will open a tunnel for a PPP
session to the DSL router. Ethernet DSL modems have a
preconfigured LAN IP address to connect to.
In the case of the Alcatel SpeedTouch™ Home, this address is
10.0.0.138
. The
router's documentation should list the address the device
uses. To open the tunnel and start a PPP
session:
#
pptp
address
adsl
If an ampersand (“&”) is added to the end of this command, pptp will return the prompt.
A tun
virtual tunnel device
will be created for interaction between the
pptp and
ppp processes. Once the
prompt is returned, or the
pptp process has confirmed a
connection, examine the tunnel:
%
ifconfig
tun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1500 inet 216.136.204.21 --> 204.152.186.171 netmask 0xffffff00 Opened by PID 918tun0
If the connection fails, check the configuration of
the router, which is usually accessible using
a web browser. Also, examine the output of
pptp
and the contents of the
log file,
/var/log/ppp.log
for clues.
“Electronic Mail”, better known as email, is one of the most widely used forms of communication today. This chapter provides a basic introduction to running a mail server on FreeBSD, as well as an introduction to sending and receiving email using FreeBSD. For more complete coverage of this subject, refer to the books listed in Appendix B, Bibliography.
After reading this chapter, you will know:
Which software components are involved in sending and receiving electronic mail.
Where basic Sendmail configuration files are located in FreeBSD.
The difference between remote and local mailboxes.
How to block spammers from illegally using a mail server as a relay.
How to install and configure an alternate Mail Transfer Agent, replacing Sendmail.
How to troubleshoot common mail server problems.
How to set up the system to send mail only.
How to use mail with a dialup connection.
How to configure SMTP authentication for added security.
How to install and use a Mail User Agent, such as mutt, to send and receive email.
How to download mail from a remote POP or IMAP server.
How to automatically apply filters and rules to incoming email.
Before reading this chapter, you should:
Properly set up a network connection (Chapter 31, Advanced Networking).
Properly set up the DNS information for a mail host (Chapter 29, Network Servers).
Know how to install additional third-party software (Chapter 4, Installing Applications: Packages and Ports).
There are five major parts involved in an email exchange: the Mail User Agent (MUA), the Mail Transfer Agent (MTA), a mail host, a remote or local mailbox, and DNS. This section provides an overview of these components.
The Mail User Agent (MUA) is an
application which is used to compose, send, and receive
emails. This application can be a command line program,
such as the built-in mail
utility or a
third-party application from the Ports Collection, such as
mutt,
alpine, or
elm. Dozens of graphical
programs are also available in the Ports Collection,
including Claws Mail,
Evolution, and
Thunderbird. Some
organizations provide a web mail program which can be
accessed through a web browser. More information about
installing and using a MUA on FreeBSD can
be found in Section 28.10, “Mail User Agents”.
The Mail Transfer Agent (MTA) is responsible for receiving incoming mail and delivering outgoing mail. FreeBSD ships with Sendmail as the default MTA, but it also supports numerous other mail server daemons, including Exim, Postfix, and qmail. Sendmail configuration is described in Section 28.3, “Sendmail Configuration Files”. If another MTA is installed using the Ports Collection, refer to its post-installation message for FreeBSD-specific configuration details and the application's website for more general configuration instructions.
The mail host is a server that is responsible for
delivering and receiving mail for a host or a network.
The mail host collects all mail sent to the domain and
stores it either in the default mbox
or the alternative Maildir format, depending on the
configuration. Once mail has been stored, it may either
be read locally using a MUA or remotely
accessed and collected using protocols such as
POP or IMAP. If
mail is read locally, a POP or
IMAP server does not need to be
installed.
To access mailboxes remotely, a POP or IMAP server is required as these protocols allow users to connect to their mailboxes from remote locations. IMAP offers several advantages over POP. These include the ability to store a copy of messages on a remote server after they are downloaded and concurrent updates. IMAP can be useful over low-speed links as it allows users to fetch the structure of messages without downloading them. It can also perform tasks such as searching on the server in order to minimize data transfer between clients and servers.
Several POP and IMAP servers are available in the Ports Collection. These include mail/qpopper, mail/imap-uw, mail/courier-imap, and mail/dovecot2.
It should be noted that both POP and IMAP transmit information, including username and password credentials, in clear-text. To secure the transmission of information across these protocols, consider tunneling sessions over ssh(1) (Section 13.8.1.2, “SSH Tunneling”) or using SSL (Section 13.6, “OpenSSL”).
The Domain Name System (DNS) and
its daemon named
play a large role in
the delivery of email. In order to deliver mail from one
site to another, the MTA will look up
the remote site in DNS to determine
which host will receive mail for the destination. This
process also occurs when mail is sent from a remote host
to the MTA.
In addition to mapping hostnames to IP addresses, DNS is responsible for storing information specific to mail delivery, known as Mail eXchanger MX records. The MX record specifies which hosts will receive mail for a particular domain.
To view the MX records for a domain, specify the type of record. Refer to host(1), for more details about this command:
%
host -t mx FreeBSD.org
FreeBSD.org mail is handled by 10 mx1.FreeBSD.org
Refer to Section 29.7, “Domain Name System (DNS)” for more information about DNS and its configuration.
Sendmail is the default MTA installed with FreeBSD. It accepts mail from MUAs and delivers it to the appropriate mail host, as defined by its configuration. Sendmail can also accept network connections and deliver mail to local mailboxes or to another program.
The configuration files for
Sendmail are located in
/etc/mail
. This section describes these
files in more detail.
/etc/mail/access
This access database file defines which hosts or
IP addresses have access to the local
mail server and what kind of access they have. Hosts
listed as OK
, which is the default
option, are allowed to send mail to this host as long as
the mail's final destination is the local machine. Hosts
listed as REJECT
are rejected for all
mail connections. Hosts listed as RELAY
are allowed to send mail for any destination using this
mail server. Hosts listed as ERROR
will
have their mail returned with the specified mail error.
If a host is listed as SKIP
,
Sendmail will abort the current
search for this entry without accepting or rejecting the
mail. Hosts listed as QUARANTINE
will
have their messages held and will receive the specified
text as the reason for the hold.
Examples of using these options for both
IPv4 and IPv6
addresses can be found in the FreeBSD sample configuration,
/etc/mail/access.sample
:
# $FreeBSD$
#
# Mail relay access control list. Default is to reject mail unless the
# destination is local, or listed in /etc/mail/local-host-names
#
## Examples (commented out for safety)
#From:cyberspammer.com ERROR:"550 We don't accept mail from spammers"
#From:okay.cyberspammer.com OK
#Connect:sendmail.org RELAY
#To:sendmail.org RELAY
#Connect:128.32 RELAY
#Connect:128.32.2 SKIP
#Connect:IPv6:1:2:3:4:5:6:7 RELAY
#Connect:suspicious.example.com QUARANTINE:Mail from suspicious host
#Connect:[127.0.0.3] OK
#Connect:[IPv6:1:2:3:4:5:6:7:8] OK
To configure the access database, use the format shown
in the sample to make entries in
/etc/mail/access
, but do not put a
comment symbol (#
) in front of the
entries. Create an entry for each host or network whose
access should be configured. Mail senders that match the
left side of the table are affected by the action on the
right side of the table.
Whenever this file is updated, update its database and restart Sendmail:
#
makemap hash /etc/mail/access < /etc/mail/access
#
service sendmail restart
/etc/mail/aliases
This database file contains a list of virtual mailboxes that are expanded to users, files, programs, or other aliases. Here are a few entries to illustrate the file format:
root: localuser ftp-bugs: joe,eric,paul bit.bucket: /dev/null procmail: "|/usr/local/bin/procmail"
The mailbox name on the left side of the colon is
expanded to the target(s) on the right. The first entry
expands the root
mailbox to the localuser
mailbox, which
is then looked up in the
/etc/mail/aliases
database. If no
match is found, the message is delivered to localuser
. The second
entry shows a mail list. Mail to ftp-bugs
is expanded to
the three local mailboxes joe
, eric
, and paul
. A remote mailbox
could be specified as
user@example.com
. The third
entry shows how to write mail to a file, in this case
/dev/null
. The last entry
demonstrates how to send mail to a program,
/usr/local/bin/procmail
, through a
UNIX® pipe. Refer to aliases(5) for more
information about the format of this file.
Whenever this file is updated, run
newaliases
to update and initialize the
aliases database.
/etc/mail/sendmail.cf
This is the master configuration file for Sendmail. It controls the overall behavior of Sendmail, including everything from rewriting email addresses to printing rejection messages to remote mail servers. Accordingly, this configuration file is quite complex. Fortunately, this file rarely needs to be changed for standard mail servers.
The master Sendmail
configuration file can be built from m4(1) macros
that define the features and behavior of
Sendmail. Refer to
/usr/src/contrib/sendmail/cf/README
for some of the details.
Whenever changes to this file are made, Sendmail needs to be restarted for the changes to take effect.
/etc/mail/virtusertable
This database file maps mail addresses for virtual
domains and users to real mailboxes. These mailboxes can
be local, remote, aliases defined in
/etc/mail/aliases
, or files. This
allows multiple virtual domains to be hosted on one
machine.
FreeBSD provides a sample configuration file in
/etc/mail/virtusertable.sample
to
further demonstrate its format. The following example
demonstrates how to create custom entries using that
format:
root@example.com root postmaster@example.com postmaster@noc.example.net @example.com joe
This file is processed in a first match order. When
an email address matches the address on the left, it is
mapped to the local mailbox listed on the right. The
format of the first entry in this example maps a specific
email address to a local mailbox, whereas the format of
the second entry maps a specific email address to a remote
mailbox. Finally, any email address from
example.com
which has not matched any
of the previous entries will match the last mapping and be
sent to the local mailbox joe
. When
creating custom entries, use this format and add them to
/etc/mail/virtusertable
. Whenever
this file is edited, update its database and restart
Sendmail:
#
makemap hash /etc/mail/virtusertable < /etc/mail/virtusertable
#
service sendmail restart
/etc/mail/relay-domains
In a default FreeBSD installation,
Sendmail is configured to only
send mail from the host it is running on. For example, if
a POP server is available, users will
be able to check mail from remote locations but they will
not be able to send outgoing emails from outside
locations. Typically, a few moments after the attempt, an
email will be sent from MAILER-DAEMON
with a 5.7 Relaying Denied
message.
The most straightforward solution is to add the
ISP's FQDN to
/etc/mail/relay-domains
. If multiple
addresses are needed, add them one per
line:
your.isp.example.com other.isp.example.net users-isp.example.org www.example.org
After creating or editing this file, restart
Sendmail with
service sendmail restart
.
Now any mail sent through the system by any host in this list, provided the user has an account on the system, will succeed. This allows users to send mail from the system remotely without opening the system up to relaying SPAM from the Internet.
FreeBSD comes with Sendmail already
installed as the MTA which is in charge of
outgoing and incoming mail. However, the system administrator
can change the system's MTA. A wide choice
of alternative MTAs is available from the
mail
category of the FreeBSD Ports
Collection.
Once a new MTA is installed, configure and test the new software before replacing Sendmail. Refer to the documentation of the new MTA for information on how to configure the software.
Once the new MTA is working, use the instructions in this section to disable Sendmail and configure FreeBSD to use the replacement MTA.
If Sendmail's outgoing mail service is disabled, it is important that it is replaced with an alternative mail delivery system. Otherwise, system functions such as periodic(8) will be unable to deliver their results by email. Many parts of the system expect a functional MTA. If applications continue to use Sendmail's binaries to try to send email after they are disabled, mail could go into an inactive Sendmail queue and never be delivered.
In order to completely disable
Sendmail, add or edit the following
lines in /etc/rc.conf
:
sendmail_enable="NO" sendmail_submit_enable="NO" sendmail_outbound_enable="NO" sendmail_msp_queue_enable="NO"
To only disable Sendmail's
incoming mail service, use only this entry in
/etc/rc.conf
:
sendmail_enable="NO"
More information on Sendmail's startup options is available in rc.sendmail(8).
When a new MTA is installed using the Ports Collection, its startup script is also installed and startup instructions are mentioned in its package message. Before starting the new MTA, stop the running Sendmail processes. This example stops all of these services, then starts the Postfix service:
#
service sendmail stop
#
service postfix start
To start the replacement MTA at system
boot, add its configuration line to
/etc/rc.conf
. This entry enables the
Postfix MTA:
postfix_enable="YES"
Some extra configuration is needed as
Sendmail is so ubiquitous that some
software assumes it is already installed and configured.
Check /etc/periodic.conf
and make sure
that these values are set to NO
. If this
file does not exist, create it with these entries:
daily_clean_hoststat_enable="NO" daily_status_mail_rejects_enable="NO" daily_status_include_submit_mailq="NO" daily_submit_queuerun="NO"
Some alternative MTAs provide their own
compatible implementations of the
Sendmail command-line interface in
order to facilitate using them as drop-in replacements for
Sendmail. However, some
MUAs may try to execute standard
Sendmail binaries instead of the
new MTA's binaries. FreeBSD uses
/etc/mail/mailer.conf
to map the expected
Sendmail binaries to the location
of the new binaries. More information about this mapping can
be found in mailwrapper(8).
The default /etc/mail/mailer.conf
looks like this:
# $FreeBSD$
#
# Execute the "real" sendmail program, named /usr/libexec/sendmail/sendmail
#
sendmail /usr/libexec/sendmail/sendmail
send-mail /usr/libexec/sendmail/sendmail
mailq /usr/libexec/sendmail/sendmail
newaliases /usr/libexec/sendmail/sendmail
hoststat /usr/libexec/sendmail/sendmail
purgestat /usr/libexec/sendmail/sendmail
When any of the commands listed on the left are run, the system actually executes the associated command shown on the right. This system makes it easy to change what binaries are executed when these default binaries are invoked.
Some MTAs, when installed using the Ports Collection, will prompt to update this file for the new binaries. For example, Postfix will update the file like this:
# # Execute the Postfix sendmail program, named /usr/local/sbin/sendmail # sendmail /usr/local/sbin/sendmail send-mail /usr/local/sbin/sendmail mailq /usr/local/sbin/sendmail newaliases /usr/local/sbin/sendmail
If the installation of the MTA does
not automatically update
/etc/mail/mailer.conf
, edit this file in
a text editor so that it points to the new binaries. This
example points to the binaries installed by
mail/ssmtp:
sendmail /usr/local/sbin/ssmtp send-mail /usr/local/sbin/ssmtp mailq /usr/local/sbin/ssmtp newaliases /usr/local/sbin/ssmtp hoststat /usr/bin/true purgestat /usr/bin/true
Once everything is configured, it is recommended to reboot the system. Rebooting provides the opportunity to ensure that the system is correctly configured to start the new MTA automatically on boot.
28.5.1. | Why do I have to use the FQDN for hosts on my site? |
The host may actually be in a different domain. For
example, in order for a host in This is because the version of
BIND which ships with FreeBSD
no longer provides default abbreviations for non-FQDNs
other than the local domain. An unqualified host such as
In older versions of BIND,
the search continued across As a good workaround, place the line: search foo.bar.edu bar.edu instead of the previous: domain foo.bar.edu into | |
28.5.2. | How can I run a mail server on a dial-up PPP host? |
Connect to a FreeBSD mail gateway on the LAN. The PPP connection is non-dedicated. One way to do this is to get a full-time Internet
server to provide secondary
MX
services for the domain. In this example, the domain is
example.com. MX 10 example.com. MX 20 example.net. Only one host should be specified as the final
recipient. For Sendmail, add
When the sending MTA attempts
to deliver mail, it will try to connect to the system,
Use something like this as a login script: #!/bin/sh # Put me in /usr/local/bin/pppmyisp ( sleep 60 ; /usr/sbin/sendmail -q ) & /usr/sbin/ppp -direct pppmyisp When creating a separate login script for users,
instead use A further refinement of the situation can be seen from this example from the FreeBSD Internet service provider's mailing list: > we provide the secondary MX for a customer. The customer connects to > our services several times a day automatically to get the mails to > his primary MX (We do not call his site when a mail for his domains > arrived). Our sendmail sends the mailqueue every 30 minutes. At the > moment he has to stay 30 minutes online to be sure that all mail is > gone to the primary MX. > > Is there a command that would initiate sendmail to send all the mails > now? The user has not root-privileges on our machine of course. In the “privacy flags” section of sendmail.cf, there is a definition Opgoaway,restrictqrun Remove restrictqrun to allow non-root users to start the queue processing. You might also like to rearrange the MXs. We are the 1st MX for our customers like this, and we have defined: # If we are the best MX for a host, try directly instead of generating # local config error. OwTrue That way a remote site will deliver straight to you, without trying the customer connection. You then send to your customer. Only works for “hosts”, so you need to get your customer to name their mail machine “customer.com” as well as “hostname.customer.com” in the DNS. Just put an A record in the DNS for “customer.com”. |
This section covers more involved topics such as mail configuration and setting up mail for an entire domain.
Out of the box, one can send email to external hosts as
long as /etc/resolv.conf
is configured or
the network has access to a configured DNS
server. To have email delivered to the MTA
on the FreeBSD host, do one of the following:
Run a DNS server for the domain.
Get mail delivered directly to the FQDN for the machine.
In order to have mail delivered directly to a host, it must have a permanent static IP address, not a dynamic IP address. If the system is behind a firewall, it must be configured to allow SMTP traffic. To receive mail directly at a host, one of these two must be configured:
Either of the above will allow mail to be received directly at the host.
Try this:
#
hostname
example.FreeBSD.org#
host example.FreeBSD.org
example.FreeBSD.org has address 204.216.27.XX
In this example, mail sent directly to
<yourlogin@example.FreeBSD.org>
should work without problems, assuming
Sendmail is running correctly on
example.FreeBSD.org
.
For this example:
#
host example.FreeBSD.org
example.FreeBSD.org has address 204.216.27.XX example.FreeBSD.org mail is handled (pri=10) by nevdull.FreeBSD.org
All mail sent to example.FreeBSD.org
will
be collected on hub
under the same
username instead of being sent directly to your host.
The above information is handled by the DNS server. The DNS record that carries mail routing information is the MX entry. If no MX record exists, mail will be delivered directly to the host by way of its IP address.
The MX entry for freefall.FreeBSD.org
at
one time looked like this:
freefall MX 30 mail.crl.net freefall MX 40 agora.rdrop.com freefall MX 10 freefall.FreeBSD.org freefall MX 20 who.cdrom.com
freefall
had many
MX entries. The lowest
MX number is the host that receives mail
directly, if available. If it is not accessible for some
reason, the next lower-numbered host will accept messages
temporarily, and pass it along when a lower-numbered host
becomes available.
Alternate MX sites should have separate Internet connections in order to be most useful. Your ISP can provide this service.
When configuring a MTA for a network, any mail sent to hosts in its domain should be diverted to the MTA so that users can receive their mail on the master mail server.
To make life easiest, a user account with the same username should exist on both the MTA and the system with the MUA. Use adduser(8) to create the user accounts.
The MTA must be the designated mail exchanger for each workstation on the network. This is done in theDNS configuration with an MX record:
example.FreeBSD.org A 204.216.27.XX ; Workstation MX 10 nevdull.FreeBSD.org ; Mailhost
This will redirect mail for the workstation to the MTA no matter where the A record points. The mail is sent to the MX host.
This must be configured on a DNS server. If the network does not run its own DNS server, talk to the ISP or DNS provider.
The following is an example of virtual email hosting.
Consider a customer with the domain customer1.org
, where all
the mail for customer1.org
should be
sent to mail.myhost.com
. The
DNS entry should look like this:
customer1.org MX 10 mail.myhost.com
An A
> record is
not needed for customer1.org
in order to
only handle email for that domain. However, running
ping
against customer1.org
will not
work unless an A
record exists for
it.
Tell the MTA which domains and/or hostnames it should accept mail for. Either of the following will work for Sendmail:
Add the hosts to
/etc/mail/local-host-names
when
using the FEATURE(use_cw_file)
.
Add a Cwyour.host.com
line to
/etc/sendmail.cf
.
There are many instances where one may only want to send mail through a relay. Some examples are:
The computer is a desktop machine that needs to use programs such as mail(1), using the ISP's mail relay.
The computer is a server that does not handle mail locally, but needs to pass off all mail to a relay for processing.
While any MTA is capable of filling this particular niche, it can be difficult to properly configure a full-featured MTA just to handle offloading mail. Programs such as Sendmail and Postfix are overkill for this use.
Additionally, a typical Internet access service agreement may forbid one from running a “mail server”.
The easiest way to fulfill those needs is to install the mail/ssmtp port:
#
cd /usr/ports/mail/ssmtp
#
make install replace clean
Once installed, mail/ssmtp can be
configured with
/usr/local/etc/ssmtp/ssmtp.conf
:
root=yourrealemail@example.com mailhub=mail.example.com rewriteDomain=example.com hostname=_HOSTNAME_
Use the real email address for root
. Enter the
ISP's outgoing mail relay in place of
mail.example.com
.
Some ISPs call this the “outgoing mail
server” or “SMTP server”.
Make sure to disable Sendmail, including the outgoing mail service. See Section 28.4.1, “Disable Sendmail” for details.
mail/ssmtp has some other options
available. Refer to the examples in
/usr/local/etc/ssmtp
or the manual page
of ssmtp for more information.
Setting up ssmtp in this manner allows any software on the computer that needs to send mail to function properly, while not violating the ISP's usage policy or allowing the computer to be hijacked for spamming.
When using a static IP address, one should not need to adjust the default configuration. Set the hostname to the assigned Internet name and Sendmail will do the rest.
When using a dynamically assigned IP address and a dialup
PPP connection to the Internet, one usually has a mailbox on the
ISP's mail server. In this example, the
ISP's domain is example.net
, the user name
is user
, the hostname
is bsd.home
, and
the ISP has allowed relay.example.net
as a mail
relay.
In order to retrieve mail from the ISP's
mailbox, install a retrieval agent from the Ports Collection.
mail/fetchmail is a good choice as it
supports many different protocols. Usually, the
ISP will provide POP.
When using user PPP, email can be
automatically fetched when an Internet connection is established
with the following entry in
/etc/ppp/ppp.linkup
:
MYADDR: !bg su user -c fetchmail
When using Sendmail to deliver
mail to non-local accounts, configure
Sendmail to process the mail queue as
soon as the Internet connection is established. To do this, add
this line after the above fetchmail
entry in
/etc/ppp/ppp.linkup
:
!bg su user -c "sendmail -q"
In this example, there is an account for
user
on bsd.home
. In the home
directory of user
on
bsd.home
, create a
.fetchmailrc
which contains this
line:
poll example.net protocol pop3 fetchall pass MySecret
This file should not be readable by anyone except
user
as it contains
the password MySecret
.
In order to send mail with the correct
from:
header, configure
Sendmail to use
<user@example.net>
rather than <user@bsd.home>
and to send all mail via
relay.example.net
,
allowing quicker mail transmission.
The following .mc
should
suffice:
VERSIONID(`bsd.home.mc version 1.0') OSTYPE(bsd4.4)dnl FEATURE(nouucp)dnl MAILER(local)dnl MAILER(smtp)dnl Cwlocalhost Cwbsd.home MASQUERADE_AS(`example.net')dnl FEATURE(allmasquerade)dnl FEATURE(masquerade_envelope)dnl FEATURE(nocanonify)dnl FEATURE(nodns)dnl define(`SMART_HOST', `relay.example.net') Dmbsd.home define(`confDOMAIN_NAME',`bsd.home')dnl define(`confDELIVERY_MODE',`deferred')dnl
Refer to the previous section for details of how to convert
this file into the sendmail.cf
format. Do
not forget to restart Sendmail after
updating sendmail.cf
.
Configuring SMTP authentication on the MTA provides a number of benefits. SMTP authentication adds a layer of security to Sendmail, and provides mobile users who switch hosts the ability to use the same MTA without the need to reconfigure their mail client's settings each time.
Install security/cyrus-sasl2
from the Ports Collection. This port supports a number of
compile-time options. For the SMTP authentication method
demonstrated in this example, make sure that
LOGIN
is not disabled.
After installing
security/cyrus-sasl2, edit
/usr/local/lib/sasl2/Sendmail.conf
,
or create it if it does not exist, and add the following
line:
pwcheck_method: saslauthd
Next, install
security/cyrus-sasl2-saslauthd and add
the following line to
/etc/rc.conf
:
saslauthd_enable="YES"
Finally, start the saslauthd daemon:
#
service saslauthd start
This daemon serves as a broker for Sendmail to authenticate against the FreeBSD passwd(5) database. This saves the trouble of creating a new set of usernames and passwords for each user that needs to use SMTP authentication, and keeps the login and mail password the same.
Next, edit /etc/make.conf
and add
the following lines:
SENDMAIL_CFLAGS=-I/usr/local/include/sasl -DSASL SENDMAIL_LDFLAGS=-L/usr/local/lib SENDMAIL_LDADD=-lsasl2
These lines provide Sendmail the proper configuration options for linking to cyrus-sasl2 at compile time. Make sure that cyrus-sasl2 has been installed before recompiling Sendmail.
Recompile Sendmail by executing the following commands:
#
cd /usr/src/lib/libsmutil
#
make cleandir && make obj && make
#
cd /usr/src/lib/libsm
#
make cleandir && make obj && make
#
cd /usr/src/usr.sbin/sendmail
#
make cleandir && make obj && make && make install
This compile should not have any problems if
/usr/src
has not changed extensively
and the shared libraries it needs are available.
After Sendmail has been
compiled and reinstalled, edit
/etc/mail/freebsd.mc
or the local
.mc
. Many administrators choose
to use the output from hostname(1) as the name of
.mc
for uniqueness. Add these
lines:
dnl set SASL options TRUST_AUTH_MECH(`GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN')dnl define(`confAUTH_MECHANISMS', `GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN')dnl
These options configure the different methods available to Sendmail for authenticating users. To use a method other than pwcheck, refer to the Sendmail documentation.
Finally, run make(1) while in
/etc/mail
. That will run the new
.mc
and create a
.cf
named either
freebsd.cf
or the name used for the
local .mc
. Then, run make
install restart
, which will copy the file to
sendmail.cf
, and properly restart
Sendmail. For more information
about this process, refer to
/etc/mail/Makefile
.
To test the configuration, use a MUA to
send a test message. For further investigation, set the
LogLevel
of Sendmail
to 13
and watch
/var/log/maillog
for any errors.
For more information, refer to SMTP authentication.
A MUA is an application that is used to
send and receive email. As email “evolves” and
becomes more complex, MUAs are becoming
increasingly powerful and provide users increased functionality
and flexibility. The mail
category of the
FreeBSD Ports Collection contains numerous MUAs.
These include graphical email clients such as
Evolution or
Balsa and console based clients such
as mutt or
alpine.
mail(1) is the default MUA installed with FreeBSD. It is a console based MUA that offers the basic functionality required to send and receive text-based email. It provides limited attachment support and can only access local mailboxes.
Although mail
does not natively support
interaction with POP or
IMAP servers, these mailboxes may be
downloaded to a local mbox
using an
application such as
fetchmail.
In order to send and receive email, run
mail
:
%
The contents of the user's mailbox in
/var/mail
are automatically read by
mail
. Should the mailbox be empty, the
utility exits with a message indicating that no mail could
be found. If mail exists, the application interface starts,
and a list of messages will be displayed. Messages are
automatically numbered, as can be seen in the following
example:
Mail version 8.1 6/6/93. Type ? for help. "/var/mail/marcs": 3 messages 3 new >N 1 root@localhost Mon Mar 8 14:05 14/510 "test" N 2 root@localhost Mon Mar 8 14:05 14/509 "user account" N 3 root@localhost Mon Mar 8 14:05 14/509 "sample"
Messages can now be read by typing t followed by the message number. This example reads the first email:
& t 1
Message 1:
From root@localhost Mon Mar 8 14:05:52 2004
X-Original-To: marcs@localhost
Delivered-To: marcs@localhost
To: marcs@localhost
Subject: test
Date: Mon, 8 Mar 2004 14:05:52 +0200 (SAST)
From: root@localhost (Charlie Root)
This is a test message, please reply if you receive it.
As seen in this example, the message will be displayed with full headers. To display the list of messages again, press h.
If the email requires a reply, press either
R or r
mail
keys. R instructs
mail
to reply only to the sender of the
email, while r replies to all other
recipients of the message. These commands can be suffixed
with the mail number of the message to reply to. After typing
the response, the end of the message should be marked by a
single . on its own line. An example can be
seen below:
&R 1
To: root@localhost Subject: Re: testThank you, I did get your email. .
EOT
In order to send a new email, press m, followed by the recipient email address. Multiple recipients may be specified by separating each address with the , delimiter. The subject of the message may then be entered, followed by the message contents. The end of the message should be specified by putting a single . on its own line.
&mail root@localhost
Subject:I mastered mail Now I can send and receive email using mail ... :) .
EOT
While using mail
, press
? to display help at any time. Refer to
mail(1) for more help on how to use
mail
.
mail(1) was not designed to handle attachments and
thus deals with them poorly. Newer MUAs
handle attachments in a more intelligent way. Users who
prefer to use mail
may find the
converters/mpack port to be of
considerable use.
mutt is a powerful MUA, with many features, including:
The ability to thread messages.
PGP support for digital signing and encryption of email.
MIME support.
Maildir support.
Highly customizable.
Refer to http://www.mutt.org
for more information on
mutt.
mutt may be installed using the mail/mutt port. After the port has been installed, mutt can be started by issuing the following command:
%
mutt
mutt will automatically read
and display the contents of the user mailbox in
/var/mail
. If no mails are found,
mutt will wait for commands from
the user. The example below shows
mutt displaying a list of
messages:
To read an email, select it using the cursor keys and press Enter. An example of mutt displaying email can be seen below:
Similar to mail(1), mutt can be used to reply only to the sender of the message as well as to all recipients. To reply only to the sender of the email, press r. To send a group reply to the original sender as well as all the message recipients, press g.
By default, mutt uses the
vi(1) editor for creating and replying to emails. Each
user can customize this by creating or editing the
.muttrc
in their home directory and
setting the editor
variable or by setting
the EDITOR
environment variable. Refer to
http://www.mutt.org/
for more information about configuring
mutt.
To compose a new mail message, press
m. After a valid subject has been given,
mutt will start vi(1) so the
email can be written. Once the contents of the email are
complete, save and quit from vi
.
mutt will resume, displaying a
summary screen of the mail that is to be delivered. In
order to send the mail, press y. An example
of the summary screen can be seen below:
mutt contains extensive help which can be accessed from most of the menus by pressing ?. The top line also displays the keyboard shortcuts where appropriate.
alpine is aimed at a beginner user, but also includes some advanced features.
alpine has had several remote vulnerabilities discovered in the past, which allowed remote attackers to execute arbitrary code as users on the local system, by the action of sending a specially-prepared email. While known problems have been fixed, alpine code is written in an insecure style and the FreeBSD Security Officer believes there are likely to be other undiscovered vulnerabilities. Users install alpine at their own risk.
The current version of alpine may be installed using the mail/alpine port. Once the port has installed, alpine can be started by issuing the following command:
%
alpine
The first time alpine runs, it displays a greeting page with a brief introduction, as well as a request from the alpine development team to send an anonymous email message allowing them to judge how many users are using their client. To send this anonymous message, press Enter. Alternatively, press E to exit the greeting without sending an anonymous message. An example of the greeting page is shown below:
The main menu is then presented, which can be navigated using the cursor keys. This main menu provides shortcuts for the composing new mails, browsing mail directories, and administering address book entries. Below the main menu, relevant keyboard shortcuts to perform functions specific to the task at hand are shown.
The default directory opened by
alpine is
inbox
. To view the message index, press
I, or select the
option shown
below:
The message index shows messages in the current directory and can be navigated by using the cursor keys. Highlighted messages can be read by pressing Enter.
In the screenshot below, a sample message is displayed by alpine. Contextual keyboard shortcuts are displayed at the bottom of the screen. An example of one of a shortcut is r, which tells the MUA to reply to the current message being displayed.
Replying to an email in alpine is done using the pico editor, which is installed by default with alpine. pico makes it easy to navigate the message and is easier for novice users to use than vi(1) or mail(1). Once the reply is complete, the message can be sent by pressing Ctrl+X. alpine will ask for confirmation before sending the message.
alpine can be customized using
the option from the main
menu. Consult http://www.washington.edu/alpine/
for more information.
fetchmail is a full-featured IMAP and POP client. It allows users to automatically download mail from remote IMAP and POP servers and save it into local mailboxes where it can be accessed more easily. fetchmail can be installed using the mail/fetchmail port, and offers various features, including:
Support for the POP3, APOP, KPOP, IMAP, ETRN and ODMR protocols.
Ability to forward mail using SMTP, which allows filtering, forwarding, and aliasing to function normally.
May be run in daemon mode to check periodically for new messages.
Can retrieve multiple mailboxes and forward them, based on configuration, to different local users.
This section explains some of the basic features of
fetchmail. This utility requires a
.fetchmailrc
configuration in the user's
home directory in order to run correctly. This file includes
server information as well as login credentials. Due to the
sensitive nature of the contents of this file, it is advisable
to make it readable only by the user, with the following
command:
%
chmod 600 .fetchmailrc
The following .fetchmailrc
serves as an
example for downloading a single user mailbox using
POP. It tells
fetchmail to connect to
example.com
using
a username of joesoap
and a password of XXX
. This example assumes
that the user joesoap
exists on the local system.
poll example.com protocol pop3 username "joesoap" password "XXX"
The next example connects to multiple POP and IMAP servers and redirects to different local usernames where applicable:
poll example.com proto pop3: user "joesoap", with password "XXX", is "jsoap" here; user "andrea", with password "XXXX"; poll example2.net proto imap: user "john", with password "XXXXX", is "myth" here;
fetchmail can be run in daemon
mode by running it with -d
, followed by the
interval (in seconds) that fetchmail
should poll servers listed in .fetchmailrc
.
The following example configures
fetchmail to poll every 600
seconds:
%
fetchmail -d 600
More information on fetchmail can
be found at http://www.fetchmail.info/
.
procmail is a powerful
application used to filter incoming mail. It allows users to
define “rules” which can be matched to incoming
mails to perform specific functions or to reroute mail to
alternative mailboxes or email addresses.
procmail can be installed using the
mail/procmail port. Once installed, it can
be directly integrated into most MTAs.
Consult the MTA documentation for more
information. Alternatively, procmail
can be integrated by adding the following line to a
.forward
in the home directory of the
user:
"|exec /usr/local/bin/procmail || exit 75"
The following section displays some basic
procmail rules, as well as brief
descriptions of what they do. Rules must be inserted into a
.procmailrc
, which must reside in the
user's home directory.
The majority of these rules can be found in procmailex(5).
To forward all mail from <user@example.com>
to
an external address of <goodmail@example2.com>
:
:0 * ^From.*user@example.com ! goodmail@example2.com
To forward all mails shorter than 1000 bytes to an external
address of <goodmail@example2.com>
:
:0 * < 1000 ! goodmail@example2.com
To send all mail sent to
<alternate@example.com>
to a mailbox called
alternate
:
:0 * ^TOalternate@example.com alternate
To send all mail with a subject of “Spam” to
/dev/null
:
:0 ^Subject:.*Spam /dev/null
A useful recipe that parses incoming FreeBSD.org
mailing lists and
places each list in its own mailbox:
:0 * ^Sender:.owner-freebsd-\/[^@]+@FreeBSD.ORG { LISTNAME=${MATCH} :0 * LISTNAME??^\/[^@]+ FreeBSD-${MATCH} }
This chapter covers some of the more frequently used network services on UNIX® systems. This includes installing, configuring, testing, and maintaining many different types of network services. Example configuration files are included throughout this chapter for reference.
By the end of this chapter, readers will know:
How to manage the inetd daemon.
How to set up the Network File System (NFS).
How to set up the Network Information Server (NIS) for centralizing and sharing user accounts.
How to set FreeBSD up to act as an LDAP server or client
How to set up automatic network settings using DHCP.
How to set up a Domain Name Server (DNS).
How to set up the Apache HTTP Server.
How to set up a File Transfer Protocol (FTP) server.
How to set up a file and print server for Windows® clients using Samba.
How to synchronize the time and date, and set up a time server using the Network Time Protocol (NTP).
How to set up iSCSI.
This chapter assumes a basic knowledge of:
/etc/rc
scripts.
Network terminology.
Installation of additional third-party software (Chapter 4, Installing Applications: Packages and Ports).
The inetd(8) daemon is sometimes referred to as a Super-Server because it manages connections for many services. Instead of starting multiple applications, only the inetd service needs to be started. When a connection is received for a service that is managed by inetd, it determines which program the connection is destined for, spawns a process for that program, and delegates the program a socket. Using inetd for services that are not heavily used can reduce system load, when compared to running each daemon individually in stand-alone mode.
Primarily, inetd is used to spawn other daemons, but several trivial protocols are handled internally, such as chargen, auth, time, echo, discard, and daytime.
This section covers the basics of configuring inetd.
Configuration of inetd is
done by editing /etc/inetd.conf
. Each
line of this configuration file represents an application
which can be started by inetd. By
default, every line starts with a comment
(#
), meaning that
inetd is not listening for any
applications. To configure inetd
to listen for an application's connections, remove the
#
at the beginning of the line for that
application.
After saving your edits, configure
inetd to start at system boot by
editing /etc/rc.conf
:
inetd_enable="YES"
To start inetd now, so that it listens for the service you configured, type:
#
service inetd start
Once inetd is started, it needs
to be notified whenever a modification is made to
/etc/inetd.conf
:
Typically, the default entry for an application does not
need to be edited beyond removing the #
.
In some situations, it may be appropriate to edit the default
entry.
As an example, this is the default entry for ftpd(8) over IPv4:
ftp stream tcp nowait root /usr/libexec/ftpd ftpd -l
The seven columns in an entry are as follows:
service-name socket-type protocol {wait|nowait}[/max-child[/max-connections-per-ip-per-minute[/max-child-per-ip]]] user[:group][/login-class] server-program server-program-arguments
where:
The service name of the daemon to start. It must
correspond to a service listed in
/etc/services
. This determines
which port inetd listens on
for incoming connections to that service. When using a
custom service, it must first be added to
/etc/services
.
Either stream
,
dgram
, raw
, or
seqpacket
. Use
stream
for TCP connections and
dgram
for
UDP services.
Use one of the following protocol names:
Protocol Name | Explanation |
---|---|
tcp or tcp4 | TCP IPv4 |
udp or udp4 | UDP IPv4 |
tcp6 | TCP IPv6 |
udp6 | UDP IPv6 |
tcp46 | Both TCP IPv4 and IPv6 |
udp46 | Both UDP IPv4 and IPv6 |
In this field, wait
or
nowait
must be specified.
max-child
,
max-connections-per-ip-per-minute
and
max-child-per-ip
are optional.
wait|nowait
indicates whether or
not the service is able to handle its own socket.
dgram
socket types must use
wait
while
stream
daemons, which are usually
multi-threaded, should use nowait
.
wait
usually hands off multiple sockets
to a single daemon, while nowait
spawns
a child daemon for each new socket.
The maximum number of child daemons
inetd may spawn is set by
max-child
. For example, to limit ten
instances of the daemon, place a /10
after nowait
. Specifying
/0
allows an unlimited number of
children.
max-connections-per-ip-per-minute
limits the number of connections from any particular
IP address per minute. Once the
limit is reached, further connections from this IP
address will be dropped until the end of the minute.
For example, a value of /10
would
limit any particular IP address to
ten connection attempts per minute.
max-child-per-ip
limits the number of
child processes that can be started on behalf on any
single IP address at any moment.
These options can limit excessive resource consumption
and help to prevent Denial of Service attacks.
An example can be seen in the default settings for fingerd(8):
finger stream tcp nowait/3/10 nobody /usr/libexec/fingerd fingerd -k -s
The username the daemon
will run as. Daemons typically run as
root
,
daemon
, or
nobody
.
The full path to the daemon. If the daemon is a
service provided by inetd
internally, use internal
.
Used to specify any command arguments to be passed
to the daemon on invocation. If the daemon is an
internal service, use
internal
.
Like most server daemons, inetd
has a number of options that can be used to modify its
behavior. By default, inetd is
started with -wW -C 60
. These options
enable TCP wrappers for all services, including internal
services, and prevent any IP address from
requesting any service more than 60 times per minute.
To change the default options which are passed to
inetd, add an entry for
inetd_flags
in
/etc/rc.conf
. If
inetd is already running, restart
it with service inetd restart
.
The available rate limiting options are:
Specify the default maximum number of simultaneous
invocations of each service, where the default is
unlimited. May be overridden on a per-service basis by
using max-child
in
/etc/inetd.conf
.
Specify the default maximum number of times a
service can be invoked from a single
IP address per minute. May be
overridden on a per-service basis by using
max-connections-per-ip-per-minute
in
/etc/inetd.conf
.
Specify the maximum number of times a service can be
invoked in one minute, where the default is
256
. A rate of 0
allows an unlimited number.
Specify the maximum number of times a service can be
invoked from a single IP address at
any one time, where the default is unlimited. May be
overridden on a per-service basis by using
max-child-per-ip
in
/etc/inetd.conf
.
Additional options are available. Refer to inetd(8) for the full list of options.
Many of the daemons which can be managed by
inetd are not security-conscious.
Some daemons, such as fingerd, can
provide information that may be useful to an attacker. Only
enable the services which are needed and monitor the system
for excessive connection attempts.
max-connections-per-ip-per-minute
,
max-child
and
max-child-per-ip
can be used to limit such
attacks.
By default, TCP wrappers is enabled. Consult hosts_access(5) for more information on placing TCP restrictions on various inetd invoked daemons.
FreeBSD supports the Network File System (NFS), which allows a server to share directories and files with clients over a network. With NFS, users and programs can access files on remote systems as if they were stored locally.
NFS has many practical uses. Some of the more common uses include:
Data that would otherwise be duplicated on each client can be kept in a single location and accessed by clients on the network.
Several clients may need access to the
/usr/ports/distfiles
directory.
Sharing that directory allows for quick access to the
source files without having to download them to each
client.
On large networks, it is often more convenient to configure a central NFS server on which all user home directories are stored. Users can log into a client anywhere on the network and have access to their home directories.
Administration of NFS exports is simplified. For example, there is only one file system where security or backup policies must be set.
Removable media storage devices can be used by other machines on the network. This reduces the number of devices throughout the network and provides a centralized location to manage their security. It is often more convenient to install software on multiple machines from a centralized installation media.
NFS consists of a server and one or more clients. The client remotely accesses the data that is stored on the server machine. In order for this to function properly, a few processes have to be configured and running.
These daemons must be running on the server:
Daemon | Description |
---|---|
nfsd | The NFS daemon which services requests from NFS clients. |
mountd | The NFS mount daemon which carries out requests received from nfsd. |
rpcbind | This daemon allows NFS clients to discover which port the NFS server is using. |
Running nfsiod(8) on the client can improve performance, but is not required.
The file systems which the NFS server
will share are specified in /etc/exports
.
Each line in this file specifies a file system to be exported,
which clients have access to that file system, and any access
options. When adding entries to this file, each exported file
system, its properties, and allowed hosts must occur on a
single line. If no clients are listed in the entry, then any
client on the network can mount that file system.
The following /etc/exports
entries
demonstrate how to export file systems. The examples can be
modified to match the file systems and client names on the
reader's network. There are many options that can be used in
this file, but only a few will be mentioned here. See
exports(5) for the full list of options.
This example shows how to export
/cdrom
to three hosts named
alpha
,
bravo
, and
charlie
:
/cdrom -roalpha
bravo
charlie
The -ro
flag makes the file system
read-only, preventing clients from making any changes to the
exported file system. This example assumes that the host
names are either in DNS or in
/etc/hosts
. Refer to hosts(5) if
the network does not have a DNS
server.
The next example exports /home
to
three clients by IP address. This can be
useful for networks without DNS or
/etc/hosts
entries. The
-alldirs
flag allows subdirectories to be
mount points. In other words, it will not automatically mount
the subdirectories, but will permit the client to mount the
directories that are required as needed.
/usr/home -alldirs 10.0.0.2 10.0.0.3 10.0.0.4
This next example exports /a
so that
two clients from different domains may access that file
system. The -maproot=root
allows root
on the remote system to
write data on the exported file system as root
. If
-maproot=root
is not specified, the
client's root
user
will be mapped to the server's nobody
account and will be
subject to the access limitations defined for nobody
.
/a -maproot=root host.example.com box.example.org
A client can only be specified once per file system. For
example, if /usr
is a single file system,
these entries would be invalid as both entries specify the
same host:
# Invalid when /usr is one file system /usr/src client /usr/ports client
The correct format for this situation is to use one entry:
/usr/src /usr/ports client
The following is an example of a valid export list, where
/usr
and /exports
are local file systems:
# Export src and ports to client01 and client02, but only # client01 has root privileges on it /usr/src /usr/ports -maproot=root client01 /usr/src /usr/ports client02 # The client machines have root and can mount anywhere # on /exports. Anyone in the world can mount /exports/obj read-only /exports -alldirs -maproot=root client01 client02 /exports/obj -ro
To enable the processes required by the
NFS server at boot time, add these options
to /etc/rc.conf
:
rpcbind_enable="YES" nfs_server_enable="YES" mountd_flags="-r"
The server can be started now by running this command:
#
service nfsd start
Whenever the NFS server is started,
mountd also starts automatically.
However, mountd only reads
/etc/exports
when it is started. To make
subsequent /etc/exports
edits take effect
immediately, force mountd to reread
it:
#
service mountd reload
To enable NFS clients, set this option
in each client's /etc/rc.conf
:
nfs_client_enable="YES"
Then, run this command on each NFS client:
#
service nfsclient start
The client now has everything it needs to mount a remote
file system. In these examples, the server's name is
server
and the client's name is
client
. To mount
/home
on
server
to the
/mnt
mount point on
client
:
#
mount server:/home /mnt
The files and directories in
/home
will now be available on
client
, in the
/mnt
directory.
To mount a remote file system each time the client boots,
add it to /etc/fstab
:
server:/home /mnt nfs rw 0 0
Refer to fstab(5) for a description of all available options.
Some applications require file locking to operate
correctly. To enable locking, add these lines to
/etc/rc.conf
on both the client and
server:
rpc_lockd_enable="YES" rpc_statd_enable="YES"
Then start the applications:
#
service lockd start
#
service statd start
If locking is not required on the server, the
NFS client can be configured to lock
locally by including -L
when running
mount. Refer to mount_nfs(8)
for further details.
The automatic mounter daemon, amd, automatically mounts a remote file system whenever a file or directory within that file system is accessed. File systems that are inactive for a period of time will be automatically unmounted by amd.
This daemon provides an alternative to modifying
/etc/fstab
to list every client. It
operates by attaching itself as an NFS
server to the /host
and
/net
directories. When a file is
accessed within one of these directories,
amd looks up the corresponding
remote mount and automatically mounts it.
/net
is used to mount an exported file
system from an IP address while
/host
is used to mount an export from a
remote hostname. For instance, an attempt to access a file
within /host/foobar/usr
would tell
amd to mount the
/usr
export on the host
foobar
.
In this example, showmount -e
shows
the exported file systems that can be mounted from the
NFS server,
foobar
:
%
showmount -e foobar
Exports list on foobar: /usr 10.10.10.0 /a 10.10.10.0%
cd /host/foobar/usr
The output from showmount
shows
/usr
as an export. When changing
directories to /host/foobar/usr
,
amd intercepts the request and
attempts to resolve the hostname
foobar
. If successful,
amd automatically mounts the
desired export.
To enable amd at boot time, add
this line to /etc/rc.conf
:
amd_enable="YES"
To start amd now:
#
service amd start
Custom flags can be passed to
amd from the
amd_flags
environment variable. By
default, amd_flags
is set to:
amd_flags="-a /.amd_mnt -l syslog /host /etc/amd.map /net /etc/amd.map"
The default options with which exports are mounted are
defined in /etc/amd.map
. Some of the
more advanced features of amd are
defined in /etc/amd.conf
.
Consult amd(8) and amd.conf(5) for more information.
The autofs(5) automount facility is supported starting with FreeBSD 10.1-RELEASE. To use the automounter functionality in older versions of FreeBSD, use amd(8) instead. This chapter only describes the autofs(5) automounter.
The autofs(5) facility is a common name for several components that, together, allow for automatic mounting of remote and local filesystems whenever a file or directory within that file system is accessed. It consists of the kernel component, autofs(5), and several userspace applications: automount(8), automountd(8) and autounmountd(8). It serves as an alternative for amd(8) from previous FreeBSD releases. Amd is still provided for backward compatibility purposes, as the two use different map format; the one used by autofs is the same as with other SVR4 automounters, such as the ones in Solaris, MacOS X, and Linux.
The autofs(5) virtual filesystem is mounted on specified mountpoints by automount(8), usually invoked during boot.
Whenever a process attempts to access file within the autofs(5) mountpoint, the kernel will notify automountd(8) daemon and pause the triggering process. The automountd(8) daemon will handle kernel requests by finding the proper map and mounting the filesystem according to it, then signal the kernel to release blocked process. The autounmountd(8) daemon automatically unmounts automounted filesystems after some time, unless they are still being used.
The primary autofs configuration file is
/etc/auto_master
. It assigns individual
maps to top-level mounts. For an explanation of
auto_master
and the map syntax, refer to
auto_master(5).
There is a special automounter map mounted on
/net
. When a file is accessed within
this directory, autofs(5) looks up the corresponding
remote mount and automatically mounts it. For instance, an
attempt to access a file within
/net/foobar/usr
would tell
automountd(8) to mount the /usr
export from the host
foobar
.
In this example, showmount -e
shows
the exported file systems that can be mounted from the
NFS server,
foobar
:
%
showmount -e foobar
Exports list on foobar: /usr 10.10.10.0 /a 10.10.10.0%
cd /net/foobar/usr
The output from showmount
shows
/usr
as an export.
When changing directories to /host/foobar/usr
,
automountd(8) intercepts the request and attempts to
resolve the hostname foobar
. If successful,
automountd(8) automatically mounts the source
export.
To enable autofs(5) at boot time, add this line to
/etc/rc.conf
:
autofs_enable="YES"
Then autofs(5) can be started by running:
#
service automount start
#
service automountd start
#
service autounmountd start
The autofs(5) map format is the same as in other operating systems. Information about this format from other sources can be useful, like the Mac OS X document.
Consult the automount(8), automountd(8), autounmountd(8), and auto_master(5) manual pages for more information.
Network Information System (NIS) is
designed to centralize administration of UNIX®-like systems
such as Solaris™, HP-UX, AIX®, Linux, NetBSD, OpenBSD, and
FreeBSD. NIS was originally known as Yellow
Pages but the name was changed due to trademark issues. This
is the reason why NIS commands begin with
yp
.
NIS is a Remote Procedure Call (RPC)-based client/server system that allows a group of machines within an NIS domain to share a common set of configuration files. This permits a system administrator to set up NIS client systems with only minimal configuration data and to add, remove, or modify configuration data from a single location.
FreeBSD uses version 2 of the NIS protocol.
Table 28.1 summarizes the terms and important processes used by NIS:
Term | Description |
---|---|
NIS domain name | NIS servers and clients share an NIS domain name. Typically, this name does not have anything to do with DNS. |
rpcbind(8) | This service enables RPC and must be running in order to run an NIS server or act as an NIS client. |
ypbind(8) | This service binds an NIS client to its NIS server. It will take the NIS domain name and use RPC to connect to the server. It is the core of client/server communication in an NIS environment. If this service is not running on a client machine, it will not be able to access the NIS server. |
ypserv(8) | This is the process for the NIS server. If this service stops running, the server will no longer be able to respond to NIS requests so hopefully, there is a slave server to take over. Some non-FreeBSD clients will not try to reconnect using a slave server and the ypbind process may need to be restarted on these clients. |
rpc.yppasswdd(8) | This process only runs on NIS master servers. This daemon allows NIS clients to change their NIS passwords. If this daemon is not running, users will have to login to the NIS master server and change their passwords there. |
There are three types of hosts in an NIS environment:
NIS master server
This server acts as a central repository for host
configuration information and maintains the
authoritative copy of the files used by all of the
NIS clients. The
passwd
, group
,
and other various files used by NIS
clients are stored on the master server. While it is
possible for one machine to be an NIS
master server for more than one NIS
domain, this type of configuration will not be covered in
this chapter as it assumes a relatively small-scale
NIS environment.
NIS slave servers
NIS slave servers maintain copies of the NIS master's data files in order to provide redundancy. Slave servers also help to balance the load of the master server as NIS clients always attach to the NIS server which responds first.
NIS clients
NIS clients authenticate against the NIS server during log on.
Information in many files can be shared using
NIS. The
master.passwd
,
group
, and hosts
files are commonly shared via NIS.
Whenever a process on a client needs information that would
normally be found in these files locally, it makes a query to
the NIS server that it is bound to
instead.
This section describes a sample NIS
environment which consists of 15 FreeBSD machines with no
centralized point of administration. Each machine has its own
/etc/passwd
and
/etc/master.passwd
. These files are kept
in sync with each other only through manual intervention.
Currently, when a user is added to the lab, the process must
be repeated on all 15 machines.
The configuration of the lab will be as follows:
Machine name | IP address | Machine role |
---|---|---|
ellington | 10.0.0.2 | NIS master |
coltrane | 10.0.0.3 | NIS slave |
basie | 10.0.0.4 | Faculty workstation |
bird | 10.0.0.5 | Client machine |
cli[1-11] |
10.0.0.[6-17] | Other client machines |
If this is the first time an NIS scheme is being developed, it should be thoroughly planned ahead of time. Regardless of network size, several decisions need to be made as part of the planning process.
When a client broadcasts its requests for info, it includes the name of the NIS domain that it is part of. This is how multiple servers on one network can tell which server should answer which request. Think of the NIS domain name as the name for a group of hosts.
Some organizations choose to use their Internet domain
name for their NIS domain name. This is
not recommended as it can cause confusion when trying to
debug network problems. The NIS domain
name should be unique within the network and it is helpful
if it describes the group of machines it represents. For
example, the Art department at Acme Inc. might be in the
“acme-art” NIS domain. This
example will use the domain name
test-domain
.
However, some non-FreeBSD operating systems require the NIS domain name to be the same as the Internet domain name. If one or more machines on the network have this restriction, the Internet domain name must be used as the NIS domain name.
There are several things to keep in mind when choosing a machine to use as a NIS server. Since NIS clients depend upon the availability of the server, choose a machine that is not rebooted frequently. The NIS server should ideally be a stand alone machine whose sole purpose is to be an NIS server. If the network is not heavily used, it is acceptable to put the NIS server on a machine running other services. However, if the NIS server becomes unavailable, it will adversely affect all NIS clients.
The canonical copies of all NIS files
are stored on the master server. The databases used to store
the information are called NIS maps. In
FreeBSD, these maps are stored in
/var/yp/[domainname]
where
[domainname]
is the name of the
NIS domain. Since multiple domains are
supported, it is possible to have several directories, one for
each domain. Each domain will have its own independent set of
maps.
NIS master and slave servers handle all NIS requests through ypserv(8). This daemon is responsible for receiving incoming requests from NIS clients, translating the requested domain and map name to a path to the corresponding database file, and transmitting data from the database back to the client.
Setting up a master NIS server can be
relatively straight forward, depending on environmental needs.
Since FreeBSD provides built-in NIS support,
it only needs to be enabled by adding the following lines to
/etc/rc.conf
:
nisdomainname="test-domain" nis_server_enable="YES" nis_yppasswdd_enable="YES"
This line sets the NIS domain name
to | |
This automates the start up of the NIS server processes when the system boots. | |
This enables the rpc.yppasswdd(8) daemon so that users can change their NIS password from a client machine. |
Care must be taken in a multi-server domain where the server machines are also NIS clients. It is generally a good idea to force the servers to bind to themselves rather than allowing them to broadcast bind requests and possibly become bound to each other. Strange failure modes can result if one server goes down and others are dependent upon it. Eventually, all the clients will time out and attempt to bind to other servers, but the delay involved can be considerable and the failure mode is still present since the servers might bind to each other all over again.
A server that is also a client can be forced to bind to a
particular server by adding these additional lines to
/etc/rc.conf
:
nis_client_enable="YES" # run client stuff as well nis_client_flags="-SNIS domain
,server
"
After saving the edits, type
/etc/netstart
to restart the network and
apply the values defined in /etc/rc.conf
.
Before initializing the NIS maps, start
ypserv(8):
#
service ypserv start
NIS maps are generated from the
configuration files in /etc
on the
NIS master, with one exception:
/etc/master.passwd
. This is to prevent
the propagation of passwords to all the servers in the
NIS domain. Therefore, before the
NIS maps are initialized, configure the
primary password files:
#
cp /etc/master.passwd /var/yp/master.passwd
#
cd /var/yp
#
vi master.passwd
It is advisable to remove all entries for system
accounts as well as any user accounts that do not need to be
propagated to the NIS clients, such as
the root
and any
other administrative accounts.
Ensure that the
/var/yp/master.passwd
is neither
group or world readable by setting its permissions to
600
.
After completing this task, initialize the
NIS maps. FreeBSD includes the
ypinit(8) script to do this. When generating maps
for the master server, include -m
and
specify the NIS domain name:
ellington#
ypinit -m test-domain
Server Type: MASTER Domain: test-domain Creating an YP server will require that you answer a few questions. Questions will all be asked at the beginning of the procedure. Do you want this procedure to quit on non-fatal errors? [y/n: n]n
Ok, please remember to go back and redo manually whatever fails. If not, something might not work. At this point, we have to construct a list of this domains YP servers. rod.darktech.org is already known as master server. Please continue to add any slave servers, one per line. When you are done with the list, type a <control D>. master server : ellington next host to add:coltrane
next host to add:^D
The current list of NIS servers looks like this: ellington coltrane Is this correct? [y/n: y]y
[..output from map generation..] NIS Map update completed. ellington has been setup as an YP master server without any errors.
This will create /var/yp/Makefile
from /var/yp/Makefile.dist
. By
default, this file assumes that the environment has a
single NIS server with only FreeBSD clients.
Since test-domain
has a slave server,
edit this line in /var/yp/Makefile
so
that it begins with a comment
(#
):
NOPUSH = "True"
Every time a new user is created, the user account must
be added to the master NIS server and the
NIS maps rebuilt. Until this occurs, the
new user will not be able to login anywhere except on the
NIS master. For example, to add the new
user jsmith
to the
test-domain
domain, run these commands on
the master server:
#
pw useradd jsmith
#
cd /var/yp
#
make test-domain
The user could also be added using adduser
jsmith
instead of pw useradd
smith
.
To set up an NIS slave server, log on
to the slave server and edit /etc/rc.conf
as for the master server. Do not generate any
NIS maps, as these already exist on the
master server. When running ypinit
on the
slave server, use -s
(for slave) instead of
-m
(for master). This option requires the
name of the NIS master in addition to the
domain name, as seen in this example:
coltrane#
ypinit -s ellington test-domain
Server Type: SLAVE Domain: test-domain Master: ellington Creating an YP server will require that you answer a few questions. Questions will all be asked at the beginning of the procedure. Do you want this procedure to quit on non-fatal errors? [y/n: n]n
Ok, please remember to go back and redo manually whatever fails. If not, something might not work. There will be no further questions. The remainder of the procedure should take a few minutes, to copy the databases from ellington. Transferring netgroup... ypxfr: Exiting: Map successfully transferred Transferring netgroup.byuser... ypxfr: Exiting: Map successfully transferred Transferring netgroup.byhost... ypxfr: Exiting: Map successfully transferred Transferring master.passwd.byuid... ypxfr: Exiting: Map successfully transferred Transferring passwd.byuid... ypxfr: Exiting: Map successfully transferred Transferring passwd.byname... ypxfr: Exiting: Map successfully transferred Transferring group.bygid... ypxfr: Exiting: Map successfully transferred Transferring group.byname... ypxfr: Exiting: Map successfully transferred Transferring services.byname... ypxfr: Exiting: Map successfully transferred Transferring rpc.bynumber... ypxfr: Exiting: Map successfully transferred Transferring rpc.byname... ypxfr: Exiting: Map successfully transferred Transferring protocols.byname... ypxfr: Exiting: Map successfully transferred Transferring master.passwd.byname... ypxfr: Exiting: Map successfully transferred Transferring networks.byname... ypxfr: Exiting: Map successfully transferred Transferring networks.byaddr... ypxfr: Exiting: Map successfully transferred Transferring netid.byname... ypxfr: Exiting: Map successfully transferred Transferring hosts.byaddr... ypxfr: Exiting: Map successfully transferred Transferring protocols.bynumber... ypxfr: Exiting: Map successfully transferred Transferring ypservers... ypxfr: Exiting: Map successfully transferred Transferring hosts.byname... ypxfr: Exiting: Map successfully transferred coltrane has been setup as an YP slave server without any errors. Remember to update map ypservers on ellington.
This will generate a directory on the slave server called
/var/yp/test-domain
which contains copies
of the NIS master server's maps. Adding
these /etc/crontab
entries on each slave
server will force the slaves to sync their maps with the maps
on the master server:
20 * * * * root /usr/libexec/ypxfr passwd.byname 21 * * * * root /usr/libexec/ypxfr passwd.byuid
These entries are not mandatory because the master server automatically attempts to push any map changes to its slaves. However, since clients may depend upon the slave server to provide correct password information, it is recommended to force frequent password map updates. This is especially important on busy networks where map updates might not always complete.
To finish the configuration, run
/etc/netstart
on the slave server in order
to start the NIS services.
An NIS client binds to an NIS server using ypbind(8). This daemon broadcasts RPC requests on the local network. These requests specify the domain name configured on the client. If an NIS server in the same domain receives one of the broadcasts, it will respond to ypbind, which will record the server's address. If there are several servers available, the client will use the address of the first server to respond and will direct all of its NIS requests to that server. The client will automatically ping the server on a regular basis to make sure it is still available. If it fails to receive a reply within a reasonable amount of time, ypbind will mark the domain as unbound and begin broadcasting again in the hopes of locating another server.
To configure a FreeBSD machine to be an NIS client:
Edit /etc/rc.conf
and add the
following lines in order to set the
NIS domain name and start
ypbind(8) during network startup:
nisdomainname="test-domain" nis_client_enable="YES"
To import all possible password entries from the
NIS server, use
vipw
to remove all user accounts
except one from /etc/master.passwd
.
When removing the accounts, keep in mind that at least one
local account should remain and this account should be a
member of wheel
. If there is a
problem with NIS, this local account
can be used to log in remotely, become the superuser, and
fix the problem. Before saving the edits, add the
following line to the end of the file:
+:::::::::
This line configures the client to provide anyone with
a valid account in the NIS server's
password maps an account on the client. There are many
ways to configure the NIS client by
modifying this line. One method is described in Section 29.4.8, “Using Netgroups”. For more detailed
reading, refer to the book
Managing NFS and NIS
, published by
O'Reilly Media.
To import all possible group entries from the
NIS server, add this line to
/etc/group
:
+:*::
To start the NIS client immediately, execute the following commands as the superuser:
#
/etc/netstart
#
service ypbind start
After completing these steps, running
ypcat passwd
on the client should show
the server's passwd
map.
Since RPC is a broadcast-based service,
any system running ypbind within
the same domain can retrieve the contents of the
NIS maps. To prevent unauthorized
transactions, ypserv(8) supports a feature called
“securenets” which can be used to restrict access
to a given set of hosts. By default, this information is
stored in /var/yp/securenets
, unless
ypserv(8) is started with -p
and an
alternate path. This file contains entries that consist of a
network specification and a network mask separated by white
space. Lines starting with #
are
considered to be comments. A sample
securenets
might look like this:
# allow connections from local host -- mandatory 127.0.0.1 255.255.255.255 # allow connections from any host # on the 192.168.128.0 network 192.168.128.0 255.255.255.0 # allow connections from any host # between 10.0.0.0 to 10.0.15.255 # this includes the machines in the testlab 10.0.0.0 255.255.240.0
If ypserv(8) receives a request from an address that
matches one of these rules, it will process the request
normally. If the address fails to match a rule, the request
will be ignored and a warning message will be logged. If the
securenets
does not exist,
ypserv
will allow connections from any
host.
Section 13.4, “TCP Wrapper” is an alternate mechanism
for providing access control instead of
securenets
. While either access control
mechanism adds some security, they are both vulnerable to
“IP spoofing” attacks. All
NIS-related traffic should be blocked at
the firewall.
Servers using securenets
may fail to serve legitimate NIS clients
with archaic TCP/IP implementations. Some of these
implementations set all host bits to zero when doing
broadcasts or fail to observe the subnet mask when
calculating the broadcast address. While some of these
problems can be fixed by changing the client configuration,
other problems may force the retirement of these client
systems or the abandonment of
securenets
.
The use of TCP Wrapper increases the latency of the NIS server. The additional delay may be long enough to cause timeouts in client programs, especially in busy networks with slow NIS servers. If one or more clients suffer from latency, convert those clients into NIS slave servers and force them to bind to themselves.
In this example, the basie
system is a faculty workstation within the
NIS domain. The
passwd
map on the master
NIS server contains accounts for both
faculty and students. This section demonstrates how to
allow faculty logins on this system while refusing student
logins.
To prevent specified users from logging on to a system,
even if they are present in the NIS
database, use vipw
to add
-
with
the correct number of colons towards the end of
username
/etc/master.passwd
on the client,
where username
is the username of
a user to bar from logging in. The line with the blocked
user must be before the +
line that
allows NIS users. In this example,
bill
is barred
from logging on to basie
:
basie#
cat /etc/master.passwd
root:[password]:0:0::0:0:The super-user:/root:/bin/csh toor:[password]:0:0::0:0:The other super-user:/root:/bin/sh daemon:*:1:1::0:0:Owner of many system processes:/root:/usr/sbin/nologin operator:*:2:5::0:0:System &:/:/usr/sbin/nologin bin:*:3:7::0:0:Binaries Commands and Source,,,:/:/usr/sbin/nologin tty:*:4:65533::0:0:Tty Sandbox:/:/usr/sbin/nologin kmem:*:5:65533::0:0:KMem Sandbox:/:/usr/sbin/nologin games:*:7:13::0:0:Games pseudo-user:/usr/games:/usr/sbin/nologin news:*:8:8::0:0:News Subsystem:/:/usr/sbin/nologin man:*:9:9::0:0:Mister Man Pages:/usr/share/man:/usr/sbin/nologin bind:*:53:53::0:0:Bind Sandbox:/:/usr/sbin/nologin uucp:*:66:66::0:0:UUCP pseudo-user:/var/spool/uucppublic:/usr/libexec/uucp/uucico xten:*:67:67::0:0:X-10 daemon:/usr/local/xten:/usr/sbin/nologin pop:*:68:6::0:0:Post Office Owner:/nonexistent:/usr/sbin/nologin nobody:*:65534:65534::0:0:Unprivileged user:/nonexistent:/usr/sbin/nologin -bill::::::::: +::::::::: basie#
Barring specified users from logging on to individual systems becomes unscaleable on larger networks and quickly loses the main benefit of NIS: centralized administration.
Netgroups were developed to handle large, complex networks with hundreds of users and machines. Their use is comparable to UNIX® groups, where the main difference is the lack of a numeric ID and the ability to define a netgroup by including both user accounts and other netgroups.
To expand on the example used in this chapter, the NIS domain will be extended to add the users and systems shown in Tables 28.2 and 28.3:
User Name(s) | Description |
---|---|
alpha ,
beta | IT department employees |
charlie , delta | IT department apprentices |
echo ,
foxtrott ,
golf ,
... | employees |
able ,
baker ,
... | interns |
Machine Name(s) | Description |
---|---|
war ,
death ,
famine ,
pollution | Only IT employees are allowed to log onto these servers. |
pride ,
greed ,
envy ,
wrath ,
lust ,
sloth | All members of the IT department are allowed to login onto these servers. |
one ,
two ,
three ,
four ,
... | Ordinary workstations used by employees. |
trashcan | A very old machine without any critical data. Even interns are allowed to use this system. |
When using netgroups to configure this scenario, each user is assigned to one or more netgroups and logins are then allowed or forbidden for all members of the netgroup. When adding a new machine, login restrictions must be defined for all netgroups. When a new user is added, the account must be added to one or more netgroups. If the NIS setup is planned carefully, only one central configuration file needs modification to grant or deny access to machines.
The first step is the initialization of the
NIS netgroup
map. In
FreeBSD, this map is not created by default. On the
NIS master server, use an editor to create
a map named /var/yp/netgroup
.
This example creates four netgroups to represent IT employees, IT apprentices, employees, and interns:
IT_EMP (,alpha,test-domain) (,beta,test-domain) IT_APP (,charlie,test-domain) (,delta,test-domain) USERS (,echo,test-domain) (,foxtrott,test-domain) \ (,golf,test-domain) INTERNS (,able,test-domain) (,baker,test-domain)
Each entry configures a netgroup. The first column in an entry is the name of the netgroup. Each set of brackets represents either a group of one or more users or the name of another netgroup. When specifying a user, the three comma-delimited fields inside each group represent:
The name of the host(s) where the other fields representing the user are valid. If a hostname is not specified, the entry is valid on all hosts.
The name of the account that belongs to this netgroup.
The NIS domain for the account. Accounts may be imported from other NIS domains into a netgroup.
If a group contains multiple users, separate each user with whitespace. Additionally, each field may contain wildcards. See netgroup(5) for details.
Netgroup names longer than 8 characters should not be used. The names are case sensitive and using capital letters for netgroup names is an easy way to distinguish between user, machine and netgroup names.
Some non-FreeBSD NIS clients cannot handle netgroups containing more than 15 entries. This limit may be circumvented by creating several sub-netgroups with 15 users or fewer and a real netgroup consisting of the sub-netgroups, as seen in this example:
BIGGRP1 (,joe1,domain) (,joe2,domain) (,joe3,domain) [...] BIGGRP2 (,joe16,domain) (,joe17,domain) [...] BIGGRP3 (,joe31,domain) (,joe32,domain) BIGGROUP BIGGRP1 BIGGRP2 BIGGRP3
Repeat this process if more than 225 (15 times 15) users exist within a single netgroup.
To activate and distribute the new NIS map:
ellington#
cd /var/yp
ellington#
make
This will generate the three NIS maps
netgroup
,
netgroup.byhost
and
netgroup.byuser
. Use the map key option
of ypcat(1) to check if the new NIS
maps are available:
ellington%
ypcat -k netgroup
ellington%
ypcat -k netgroup.byhost
ellington%
ypcat -k netgroup.byuser
The output of the first command should resemble the
contents of /var/yp/netgroup
. The second
command only produces output if host-specific netgroups were
created. The third command is used to get the list of
netgroups for a user.
To configure a client, use vipw(8) to specify the
name of the netgroup. For example, on the server named
war
, replace this line:
+:::::::::
with
+@IT_EMP:::::::::
This specifies that only the users defined in the netgroup
IT_EMP
will be imported into this system's
password database and only those users are allowed to login to
this system.
This configuration also applies to the
~
function of the shell and all routines
which convert between user names and numerical user IDs. In
other words,
cd ~
will
not work, user
ls -l
will show the numerical ID
instead of the username, and find . -user joe
-print
will fail with the message
No such user. To fix this, import all
user entries without allowing them to login into the servers.
This can be achieved by adding an extra line:
+:::::::::/usr/sbin/nologin
This line configures the client to import all entries but
to replace the shell in those entries with
/usr/sbin/nologin
.
Make sure that extra line is placed
after
+@IT_EMP:::::::::
. Otherwise, all user
accounts imported from NIS will have
/usr/sbin/nologin
as their login
shell and no one will be able to login to the system.
To configure the less important servers, replace the old
+:::::::::
on the servers with these
lines:
+@IT_EMP::::::::: +@IT_APP::::::::: +:::::::::/usr/sbin/nologin
The corresponding lines for the workstations would be:
+@IT_EMP::::::::: +@USERS::::::::: +:::::::::/usr/sbin/nologin
NIS supports the creation of netgroups from other
netgroups which can be useful if the policy regarding user
access changes. One possibility is the creation of role-based
netgroups. For example, one might create a netgroup called
BIGSRV
to define the login restrictions for
the important servers, another netgroup called
SMALLSRV
for the less important servers,
and a third netgroup called USERBOX
for the
workstations. Each of these netgroups contains the netgroups
that are allowed to login onto these machines. The new
entries for the NIS
netgroup
map would look like this:
BIGSRV IT_EMP IT_APP SMALLSRV IT_EMP IT_APP ITINTERN USERBOX IT_EMP ITINTERN USERS
This method of defining login restrictions works reasonably well when it is possible to define groups of machines with identical restrictions. Unfortunately, this is the exception and not the rule. Most of the time, the ability to define login restrictions on a per-machine basis is required.
Machine-specific netgroup definitions are another
possibility to deal with the policy changes. In this
scenario, the /etc/master.passwd
of each
system contains two lines starting with “+”.
The first line adds a netgroup with the accounts allowed to
login onto this machine and the second line adds all other
accounts with /usr/sbin/nologin
as shell.
It is recommended to use the “ALL-CAPS” version
of the hostname as the name of the netgroup:
+@BOXNAME
:::::::::
+:::::::::/usr/sbin/nologin
Once this task is completed on all the machines, there is
no longer a need to modify the local versions of
/etc/master.passwd
ever again. All
further changes can be handled by modifying the
NIS map. Here is an example of a possible
netgroup
map for this scenario:
# Define groups of users first IT_EMP (,alpha,test-domain) (,beta,test-domain) IT_APP (,charlie,test-domain) (,delta,test-domain) DEPT1 (,echo,test-domain) (,foxtrott,test-domain) DEPT2 (,golf,test-domain) (,hotel,test-domain) DEPT3 (,india,test-domain) (,juliet,test-domain) ITINTERN (,kilo,test-domain) (,lima,test-domain) D_INTERNS (,able,test-domain) (,baker,test-domain) # # Now, define some groups based on roles USERS DEPT1 DEPT2 DEPT3 BIGSRV IT_EMP IT_APP SMALLSRV IT_EMP IT_APP ITINTERN USERBOX IT_EMP ITINTERN USERS # # And a groups for a special tasks # Allow echo and golf to access our anti-virus-machine SECURITY IT_EMP (,echo,test-domain) (,golf,test-domain) # # machine-based netgroups # Our main servers WAR BIGSRV FAMINE BIGSRV # User india needs access to this server POLLUTION BIGSRV (,india,test-domain) # # This one is really important and needs more access restrictions DEATH IT_EMP # # The anti-virus-machine mentioned above ONE SECURITY # # Restrict a machine to a single user TWO (,hotel,test-domain) # [...more groups to follow]
It may not always be advisable to use machine-based netgroups. When deploying a couple of dozen or hundreds of systems, role-based netgroups instead of machine-based netgroups may be used to keep the size of the NIS map within reasonable limits.
NIS requires that all hosts within an NIS domain use the same format for encrypting passwords. If users have trouble authenticating on an NIS client, it may be due to a differing password format. In a heterogeneous network, the format must be supported by all operating systems, where DES is the lowest common standard.
To check which format a server or client is using, look
at this section of
/etc/login.conf
:
default:\ :passwd_format=des:\ :copyright=/etc/COPYRIGHT:\ [Further entries elided]
In this example, the system is using the
DES format. Other possible values are
blf
for Blowfish and md5
for MD5 encrypted passwords.
If the format on a host needs to be edited to match the one being used in the NIS domain, the login capability database must be rebuilt after saving the change:
#
cap_mkdb /etc/login.conf
The format of passwords for existing user accounts will not be updated until each user changes their password after the login capability database is rebuilt.
The Lightweight Directory Access Protocol (LDAP) is an application layer protocol used to access, modify, and authenticate objects using a distributed directory information service. Think of it as a phone or record book which stores several levels of hierarchical, homogeneous information. It is used in Active Directory and OpenLDAP networks and allows users to access to several levels of internal information utilizing a single account. For example, email authentication, pulling employee contact information, and internal website authentication might all make use of a single user account in the LDAP server's record base.
This section provides a quick start guide for configuring an LDAP server on a FreeBSD system. It assumes that the administrator already has a design plan which includes the type of information to store, what that information will be used for, which users should have access to that information, and how to secure this information from unauthorized access.
LDAP uses several terms which should be understood before starting the configuration. All directory entries consist of a group of attributes. Each of these attribute sets contains a unique identifier known as a Distinguished Name (DN) which is normally built from several other attributes such as the common or Relative Distinguished Name (RDN). Similar to how directories have absolute and relative paths, consider a DN as an absolute path and the RDN as the relative path.
An example LDAP entry looks like the
following. This example searches for the entry for the
specified user account (uid
),
organizational unit (ou
), and organization
(o
):
%
ldapsearch -xb "uid=
# extended LDIF # # LDAPv3 # base <uid=trhodes,ou=users,o=example.com> with scope subtree # filter: (objectclass=*) # requesting: ALL # # trhodes, users, example.com dn: uid=trhodes,ou=users,o=example.com mail: trhodes@example.com cn: Tom Rhodes uid: trhodes telephoneNumber: (123) 456-7890 # search result search: 2 result: 0 Success # numResponses: 2 # numEntries: 1trhodes
,ou=users
,o=example.com
"
This example entry shows the values for the
dn
, mail
,
cn
, uid
, and
telephoneNumber
attributes. The
cn attribute is the
RDN.
More information about LDAP and its
terminology can be found at http://www.openldap.org/doc/admin24/intro.html
.
FreeBSD does not provide a built-in LDAP server. Begin the configuration by installing net/openldap-server package or port:
#
pkg install openldap-server
There is a large set of default options enabled in the
package. Review them by running
pkg info openldap-server
. If they are not
sufficient (for example if SQL support is needed), please
consider recompiling the port using the appropriate framework.
The installation creates the directory
/var/db/openldap-data
to hold the data.
The directory to store the certificates must be
created:
#
mkdir /usr/local/etc/openldap/private
The next phase is to configure the Certificate Authority.
The following commands must be executed from
/usr/local/etc/openldap/private
. This is
important as the file permissions need to be restrictive and
users should not have access to these files. More detailed
information about certificates and their parameters can be
found in Section 13.6, “OpenSSL”. To create the
Certificate Authority, start with this command and follow the
prompts:
#
openssl req -days
365
-nodes -new -x509 -keyout ca.key -out ../ca.crt
The entries for the prompts may be generic
except for the
Common Name
. This entry must be
different than the system hostname. If
this will be a self signed certificate, prefix the hostname
with CA
for Certificate Authority.
The next task is to create a certificate signing request and a private key. Input this command and follow the prompts:
#
openssl req -days
365
-nodes -new -keyout server.key -out server.csr
During the certificate generation process, be sure to
correctly set the Common Name
attribute.
The Certificate Signing Request must be signed with the
Certificate Authority in order to be used as a valid
certificate:
#
openssl x509 -req -days
365
-in server.csr -out ../server.crt -CA ../ca.crt -CAkey ca.key -CAcreateserial
The final part of the certificate generation process is to generate and sign the client certificates:
#
openssl req -days
365
-nodes -new -keyout client.key -out client.csr#
openssl x509 -req -days 3650 -in client.csr -out ../client.crt -CA ../ca.crt -CAkey ca.key
Remember to use the same Common Name
attribute when prompted. When finished, ensure that a total
of eight (8) new files have been generated through the
proceeding commands.
The daemon running the OpenLDAP server is
slapd
. Its configuration is performed
through slapd.ldif
: the old
slapd.conf
has been deprecated by
OpenLDAP.
Configuration
examples for slapd.ldif
are
available and can also be found in
/usr/local/etc/openldap/slapd.ldif.sample
.
Options are documented in slapd-config(5). Each section
of slapd.ldif
, like all the other LDAP
attribute sets, is uniquely identified through a DN. Be sure
that no blank lines are left between the
dn:
statement and the desired end of the
section. In the following example, TLS will be used to
implement a secure channel. The first section represents the
global configuration:
# # See slapd-config(5) for details on configuration options. # This file should NOT be world readable. # dn: cn=config objectClass: olcGlobal cn: config # # # Define global ACLs to disable default read access. # olcArgsFile: /var/run/openldap/slapd.args olcPidFile: /var/run/openldap/slapd.pid olcTLSCertificateFile: /usr/local/etc/openldap/server.crt olcTLSCertificateKeyFile: /usr/local/etc/openldap/private/server.key olcTLSCACertificateFile: /usr/local/etc/openldap/ca.crt #olcTLSCipherSuite: HIGH olcTLSProtocolMin: 3.1 olcTLSVerifyClient: never
The Certificate Authority, server certificate and server
private key files must be specified here. It is recommended
to let the clients choose the security cipher and omit option
olcTLSCipherSuite
(incompatible with TLS
clients other than openssl
). Option
olcTLSProtocolMin
lets the server require a
minimum security level: it is recommended. While
verification is mandatory for the server, it is not for the
client: olcTLSVerifyClient: never
.
The second section is about the backend modules and can be configured as follows:
# # Load dynamic backend modules: # dn: cn=module,cn=config objectClass: olcModuleList cn: module olcModulepath: /usr/local/libexec/openldap olcModuleload: back_mdb.la #olcModuleload: back_bdb.la #olcModuleload: back_hdb.la #olcModuleload: back_ldap.la #olcModuleload: back_passwd.la #olcModuleload: back_shell.la
The third section is devoted to load the needed
ldif
schemas to be used by the databases:
they are essential.
dn: cn=schema,cn=config objectClass: olcSchemaConfig cn: schema include: file:///usr/local/etc/openldap/schema/core.ldif include: file:///usr/local/etc/openldap/schema/cosine.ldif include: file:///usr/local/etc/openldap/schema/inetorgperson.ldif include: file:///usr/local/etc/openldap/schema/nis.ldif
Next, the frontend configuration section:
# Frontend settings # dn: olcDatabase={-1}frontend,cn=config objectClass: olcDatabaseConfig objectClass: olcFrontendConfig olcDatabase: {-1}frontend olcAccess: to * by * read # # Sample global access control policy: # Root DSE: allow anyone to read it # Subschema (sub)entry DSE: allow anyone to read it # Other DSEs: # Allow self write access # Allow authenticated users read access # Allow anonymous users to authenticate # #olcAccess: to dn.base="" by * read #olcAccess: to dn.base="cn=Subschema" by * read #olcAccess: to * # by self write # by users read # by anonymous auth # # if no access controls are present, the default policy # allows anyone and everyone to read anything but restricts # updates to rootdn. (e.g., "access to * by * read") # # rootdn can always read and write EVERYTHING! # olcPasswordHash: {SSHA} # {SSHA} is already the default for olcPasswordHash
Another section is devoted to the configuration backend, the only way to later access the OpenLDAP server configuration is as a global super-user.
dn: olcDatabase={0}config,cn=config objectClass: olcDatabaseConfig olcDatabase: {0}config olcAccess: to * by * none olcRootPW: {SSHA}iae+lrQZILpiUdf16Z9KmDmSwT77Dj4U
The default administrator username is
cn=config
. Type
slappasswd
in a shell, choose a password
and use its hash in olcRootPW
. If this
option is not specified now, before
slapd.ldif
is imported, no one will be
later able to modify the
global configuration section.
The last section is about the database backend:
####################################################################### # LMDB database definitions ####################################################################### # dn: olcDatabase=mdb,cn=config objectClass: olcDatabaseConfig objectClass: olcMdbConfig olcDatabase: mdb olcDbMaxSize: 1073741824 olcSuffix: dc=domain,dc=example olcRootDN: cn=mdbadmin,dc=domain,dc=example # Cleartext passwords, especially for the rootdn, should # be avoided. See slappasswd(8) and slapd-config(5) for details. # Use of strong authentication encouraged. olcRootPW: {SSHA}X2wHvIWDk6G76CQyCMS1vDCvtICWgn0+ # The database directory MUST exist prior to running slapd AND # should only be accessible by the slapd and slap tools. # Mode 700 recommended. olcDbDirectory: /var/db/openldap-data # Indices to maintain olcDbIndex: objectClass eq
This database hosts the actual
contents of the LDAP
directory. Types other than mdb
are
available. Its super-user, not to be confused with the global
one, is configured here: a (possibly custom) username in
olcRootDN
and the password hash in
olcRootPW
; slappasswd
can be used as before.
This repository
contains four examples of slapd.ldif
. To
convert an existing slapd.conf
into
slapd.ldif
, refer to this
page (please note that this may introduce some
unuseful options).
When the configuration is completed,
slapd.ldif
must be placed in an empty
directory. It is recommended to create it as:
#
mkdir /usr/local/etc/openldap/slapd.d/
Import the configuration database:
#
/usr/local/sbin/slapadd -n0 -F /usr/local/etc/openldap/slapd.d/ -l /usr/local/etc/openldap/slapd.ldif
Start the slapd
daemon:
#
/usr/local/libexec/slapd -F /usr/local/etc/openldap/slapd.d/
Option -d
can be used for debugging,
as specified in slapd(8). To verify that the server is
running and working:
#
ldapsearch -x -b '' -s base '(objectclass=*)' namingContexts
# extended LDIF # # LDAPv3 # base <> with scope baseObject # filter: (objectclass=*) # requesting: namingContexts # # dn: namingContexts: dc=domain,dc=example # search result search: 2 result: 0 Success # numResponses: 2 # numEntries: 1
The server must still be trusted. If that has never been done before, follow these instructions. Install the OpenSSL package or port:
#
pkg install openssl
From the directory where ca.crt
is
stored (in this example,
/usr/local/etc/openldap
), run:
#
c_rehash .
Both the CA and the server certificate are now correctly
recognized in their respective roles. To verify this, run
this command from the server.crt
directory:
#
openssl verify -verbose -CApath . server.crt
If slapd
was running, restart it. As
stated in /usr/local/etc/rc.d/slapd
, to
properly run slapd
at boot the
following lines must be added to
/etc/rc.conf
:
lapd_enable="YES" slapd_flags='-h "ldapi://%2fvar%2frun%2fopenldap%2fldapi/ ldap://0.0.0.0/"' slapd_sockets="/var/run/openldap/ldapi" slapd_cn_config="YES"
slapd
does not provide debugging at
boot. Check /var/log/debug.log
,
dmesg -a
and
/var/log/messages
for this
purpose.
The following example adds the group
team
and the user john
to the domain.example
LDAP database, which is still empty.
First, create the file
domain.ldif
:
#
cat domain.ldif
dn: dc=domain,dc=example objectClass: dcObject objectClass: organization o: domain.example dc: domain dn: ou=groups,dc=domain,dc=example objectClass: top objectClass: organizationalunit ou: groups dn: ou=users,dc=domain,dc=example objectClass: top objectClass: organizationalunit ou: users dn: cn=team,ou=groups,dc=domain,dc=example objectClass: top objectClass: posixGroup cn: team gidNumber: 10001 dn: uid=john,ou=users,dc=domain,dc=example objectClass: top objectClass: account objectClass: posixAccount objectClass: shadowAccount cn: John McUser uid: john uidNumber: 10001 gidNumber: 10001 homeDirectory: /home/john/ loginShell: /usr/bin/bash userPassword: secret
See the OpenLDAP documentation for more details. Use
slappasswd
to replace the plain text
password secret
with a hash in
userPassword
. The path specified as
loginShell
must exist in all the systems
where john
is allowed to login. Finally,
use the mdb
administrator to modify the
database:
#
ldapadd -W -D "cn=mdbadmin,dc=domain,dc=example" -f domain.ldif
Modifications to the global
configuration section can only be performed by
the global super-user. For example, assume that the option
olcTLSCipherSuite: HIGH:MEDIUM:SSLv3
was
initially specified and must now be deleted. First, create a
file that contains the following:
#
cat
dn: cn=config changetype: modify delete: olcTLSCipherSuiteglobal_mod
Then, apply the modifications:
#
ldapmodify -f global_mod -x -D "cn=config" -W
When asked, provide the password chosen in the
configuration backend section. The
username is not required: here, cn=config
represents the DN of the database section to be modified.
Alternatively, use ldapmodify
to delete a
single line of the database, ldapdelete
to
delete a whole entry.
If something goes wrong, or if the global super-user cannot access the configuration backend, it is possible to delete and re-write the whole configuration:
#
rm -rf /usr/local/etc/openldap/slapd.d/
slapd.ldif
can then be edited and
imported again. Please, follow this procedure only when no
other solution is available.
This is the configuration of the server only. The same machine can also host an LDAP client, with its own separate configuration.
The Dynamic Host Configuration Protocol
(DHCP) allows a system to connect to a
network in order to be assigned the necessary addressing
information for communication on that network. FreeBSD includes
the OpenBSD version of dhclient
which is used
by the client to obtain the addressing information. FreeBSD does
not install a DHCP server, but several
servers are available in the FreeBSD Ports Collection. The
DHCP protocol is fully described in RFC
2131.
Informational resources are also available at isc.org/downloads/dhcp/.
This section describes how to use the built-in DHCP client. It then describes how to install and configure a DHCP server.
In FreeBSD, the bpf(4) device is needed by both the
DHCP server and DHCP
client. This device is included in the
GENERIC
kernel that is installed with
FreeBSD. Users who prefer to create a custom kernel need to keep
this device if DHCP is used.
It should be noted that bpf
also
allows privileged users to run network packet sniffers on
that system.
DHCP client support is included in the FreeBSD installer, making it easy to configure a newly installed system to automatically receive its networking addressing information from an existing DHCP server. Refer to Section 2.8, “Post-Installation” for examples of network configuration.
When dhclient
is executed on the client
machine, it begins broadcasting requests for configuration
information. By default, these requests use
UDP port 68. The server replies on
UDP port 67, giving the client an
IP address and other relevant network
information such as a subnet mask, default gateway, and
DNS server addresses. This information is
in the form of a DHCP
“lease” and is valid for a configurable time.
This allows stale IP addresses for clients
no longer connected to the network to automatically be reused.
DHCP clients can obtain a great deal of
information from the server. An exhaustive list may be found
in dhcp-options(5).
By default, when a FreeBSD system boots, its DHCP client runs in the background, or asynchronously. Other startup scripts continue to run while the DHCP process completes, which speeds up system startup.
Background DHCP works well when the DHCP server responds quickly to the client's requests. However, DHCP may take a long time to complete on some systems. If network services attempt to run before DHCP has assigned the network addressing information, they will fail. Using DHCP in synchronous mode prevents this problem as it pauses startup until the DHCP configuration has completed.
This line in /etc/rc.conf
is used to
configure background or asynchronous mode:
ifconfig_fxp0
="DHCP"
This line may already exist if the system was configured
to use DHCP during installation. Replace
the fxp0
shown in these examples
with the name of the interface to be dynamically configured,
as described in Section 11.5, “Setting Up Network Interface Cards”.
To instead configure the system to use synchronous mode,
and to pause during startup while DHCP
completes, use
“SYNCDHCP
”:
ifconfig_fxp0
="SYNCDHCP"
Additional client options are available. Search for
dhclient
in rc.conf(5) for
details.
The DHCP client uses the following files:
/etc/dhclient.conf
The configuration file used by
dhclient
. Typically, this file
contains only comments as the defaults are suitable for
most clients. This configuration file is described in
dhclient.conf(5).
/sbin/dhclient
More information about the command itself can be found in dhclient(8).
/sbin/dhclient-script
The FreeBSD-specific DHCP client configuration script. It is described in dhclient-script(8), but should not need any user modification to function properly.
/var/db/dhclient.leases.
interface
The DHCP client keeps a database of valid leases in this file, which is written as a log and is described in dhclient.leases(5).
This section demonstrates how to configure a FreeBSD system to act as a DHCP server using the Internet Systems Consortium (ISC) implementation of the DHCP server. This implementation and its documentation can be installed using the net/isc-dhcp43-server package or port.
The installation of
net/isc-dhcp43-server installs a sample
configuration file. Copy
/usr/local/etc/dhcpd.conf.example
to
/usr/local/etc/dhcpd.conf
and make any
edits to this new file.
The configuration file is comprised of declarations for subnets and hosts which define the information that is provided to DHCP clients. For example, these lines configure the following:
option domain-name "example.org"; option domain-name-servers ns1.example.org; option subnet-mask 255.255.255.0; default-lease-time 600; max-lease-time 72400; ddns-update-style none; subnet 10.254.239.0 netmask 255.255.255.224 { range 10.254.239.10 10.254.239.20; option routers rtr-239-0-1.example.org, rtr-239-0-2.example.org; } host fantasia { hardware ethernet 08:00:07:26:c0:a5; fixed-address fantasia.fugue.com; }
This option specifies the default search domain that will be provided to clients. Refer to resolv.conf(5) for more information. | |
This option specifies a comma separated list of DNS servers that the client should use. They can be listed by their Fully Qualified Domain Names (FQDN), as seen in the example, or by their IP addresses. | |
The subnet mask that will be provided to clients. | |
The default lease expiry time in seconds. A client can be configured to override this value. | |
The maximum allowed length of time, in seconds, for a
lease. Should a client request a longer lease, a lease
will still be issued, but it will only be valid for
| |
The default of | |
This line creates a pool of available IP addresses which are reserved for allocation to DHCP clients. The range of addresses must be valid for the network or subnet specified in the previous line. | |
Declares the default gateway that is valid for the
network or subnet specified before the opening
| |
Specifies the hardware MAC address of a client so that the DHCP server can recognize the client when it makes a request. | |
Specifies that this host should always be given the same IP address. Using the hostname is correct, since the DHCP server will resolve the hostname before returning the lease information. |
This configuration file supports many more options. Refer to dhcpd.conf(5), installed with the server, for details and examples.
Once the configuration of dhcpd.conf
is complete, enable the DHCP server in
/etc/rc.conf
:
dhcpd_enable="YES" dhcpd_ifaces="dc0"
Replace the dc0
with the interface (or
interfaces, separated by whitespace) that the
DHCP server should listen on for
DHCP client requests.
Start the server by issuing the following command:
#
service isc-dhcpd start
Any future changes to the configuration of the server will require the dhcpd service to be stopped and then started using service(8).
The DHCP server uses the following files. Note that the manual pages are installed with the server software.
/usr/local/sbin/dhcpd
More information about the dhcpd server can be found in dhcpd(8).
/usr/local/etc/dhcpd.conf
The server configuration file needs to contain all the information that should be provided to clients, along with information regarding the operation of the server. This configuration file is described in dhcpd.conf(5).
/var/db/dhcpd.leases
The DHCP server keeps a database of leases it has issued in this file, which is written as a log. Refer to dhcpd.leases(5), which gives a slightly longer description.
/usr/local/sbin/dhcrelay
This daemon is used in advanced environments where one DHCP server forwards a request from a client to another DHCP server on a separate network. If this functionality is required, install the net/isc-dhcp43-relay package or port. The installation includes dhcrelay(8) which provides more detail.
Domain Name System (DNS) is the protocol through which domain names are mapped to IP addresses, and vice versa. DNS is coordinated across the Internet through a somewhat complex system of authoritative root, Top Level Domain (TLD), and other smaller-scale name servers, which host and cache individual domain information. It is not necessary to run a name server to perform DNS lookups on a system.
The following table describes some of the terms associated with DNS:
Term | Definition |
---|---|
Forward DNS | Mapping of hostnames to IP addresses. |
Origin | Refers to the domain covered in a particular zone file. |
Resolver | A system process through which a machine queries a name server for zone information. |
Reverse DNS | Mapping of IP addresses to hostnames. |
Root zone | The beginning of the Internet zone hierarchy. All zones fall under the root zone, similar to how all files in a file system fall under the root directory. |
Zone | An individual domain, subdomain, or portion of the DNS administered by the same authority. |
Examples of zones:
.
is how the root zone is
usually referred to in documentation.
org.
is a Top Level Domain
(TLD) under the root zone.
example.org.
is a zone
under the org.
TLD.
1.168.192.in-addr.arpa
is a
zone referencing all IP addresses which
fall under the 192.168.1.*
IP address space.
As one can see, the more specific part of a hostname
appears to its left. For example, example.org.
is more
specific than org.
, as
org.
is more specific than the root
zone. The layout of each part of a hostname is much like a file
system: the /dev
directory falls within the
root, and so on.
Name servers generally come in two forms: authoritative name servers, and caching (also known as resolving) name servers.
An authoritative name server is needed when:
One wants to serve DNS information to the world, replying authoritatively to queries.
A domain, such as example.org
, is
registered and IP addresses need to be
assigned to hostnames under it.
An IP address block requires reverse DNS entries (IP to hostname).
A backup or second name server, called a slave, will reply to queries.
A caching name server is needed when:
A local DNS server may cache and respond more quickly than querying an outside name server.
When one queries for www.FreeBSD.org
, the
resolver usually queries the uplink ISP's
name server, and retrieves the reply. With a local, caching
DNS server, the query only has to be made
once to the outside world by the caching
DNS server. Additional queries will not
have to go outside the local network, since the information is
cached locally.
Unbound is provided in the FreeBSD base system. By default, it will provide DNS resolution to the local machine only. While the base system package can be configured to provide resolution services beyond the local machine, it is recommended that such requirements be addressed by installing Unbound from the FreeBSD Ports Collection.
To enable Unbound, add the
following to /etc/rc.conf
:
local_unbound_enable="YES"
Any existing nameservers in
/etc/resolv.conf
will be configured as
forwarders in the new Unbound
configuration.
If any of the listed nameservers do not support
DNSSEC, local DNS
resolution will fail. Be sure to test each nameserver and
remove any that fail the test. The following command will
show the trust tree or a failure for a nameserver running on
192.168.1.1
:
%
drill -S FreeBSD.org @
192.168.1.1
Once each nameserver is confirmed to support DNSSEC, start Unbound:
#
service local_unbound onestart
This will take care of updating
/etc/resolv.conf
so that queries for
DNSSEC secured domains will now work. For
example, run the following to validate the FreeBSD.org
DNSSEC trust tree:
%
drill -S FreeBSD.org
;; Number of trusted keys: 1 ;; Chasing: freebsd.org. A DNSSEC Trust tree: freebsd.org. (A) |---freebsd.org. (DNSKEY keytag: 36786 alg: 8 flags: 256) |---freebsd.org. (DNSKEY keytag: 32659 alg: 8 flags: 257) |---freebsd.org. (DS keytag: 32659 digest type: 2) |---org. (DNSKEY keytag: 49587 alg: 7 flags: 256) |---org. (DNSKEY keytag: 9795 alg: 7 flags: 257) |---org. (DNSKEY keytag: 21366 alg: 7 flags: 257) |---org. (DS keytag: 21366 digest type: 1) | |---. (DNSKEY keytag: 40926 alg: 8 flags: 256) | |---. (DNSKEY keytag: 19036 alg: 8 flags: 257) |---org. (DS keytag: 21366 digest type: 2) |---. (DNSKEY keytag: 40926 alg: 8 flags: 256) |---. (DNSKEY keytag: 19036 alg: 8 flags: 257) ;; Chase successful
The open source Apache HTTP Server is the most widely used web server. FreeBSD does not install this web server by default, but it can be installed from the www/apache24 package or port.
This section summarizes how to configure and start version
2.x
of the Apache HTTP
Server on FreeBSD. For more detailed information
about Apache 2.X and its
configuration directives, refer to httpd.apache.org.
In FreeBSD, the main Apache HTTP
Server configuration file is installed as
/usr/local/etc/apache2
,
where x
/httpd.confx
represents the version
number. This ASCII text file begins
comment lines with a #
. The most
frequently modified directives are:
ServerRoot "/usr/local"
Specifies the default directory hierarchy for the
Apache installation.
Binaries are stored in the bin
and
sbin
subdirectories of the server
root and configuration files are stored in the etc/apache2
subdirectory.x
ServerAdmin you@example.com
Change this to the email address to receive problems with the server. This address also appears on some server-generated pages, such as error documents.
ServerName
www.example.com:80
Allows an administrator to set a hostname which is
sent back to clients for the server. For example,
www
can be used instead of the
actual hostname. If the system does not have a
registered DNS name, enter its
IP address instead. If the server
will listen on an alternate report, change
80
to the alternate port
number.
DocumentRoot
"/usr/local/www/apache2x
/data"
The directory where documents will be served from. By default, all requests are taken from this directory, but symbolic links and aliases may be used to point to other locations.
It is always a good idea to make a backup copy of the
default Apache configuration file
before making changes. When the configuration of
Apache is complete, save the file
and verify the configuration using
apachectl
. Running apachectl
configtest
should return Syntax
OK
.
To launch Apache at system
startup, add the following line to
/etc/rc.conf
:
apache24
_enable="YES"
If Apache should be started
with non-default options, the following line may be added to
/etc/rc.conf
to specify the needed
flags:
apache24
_flags=""
If apachectl does not report
configuration errors, start httpd
now:
#
service apache
24
start
The httpd
service can be tested by
entering
http://
in a web browser, replacing
localhost
localhost
with the fully-qualified
domain name of the machine running httpd
.
The default web page that is displayed is
/usr/local/www/apache
.24
/data/index.html
The Apache configuration can be
tested for errors after making subsequent configuration
changes while httpd
is running using the
following command:
#
service apache
24
configtest
It is important to note that
configtest
is not an rc(8) standard,
and should not be expected to work for all startup
scripts.
Virtual hosting allows multiple websites to run on one Apache server. The virtual hosts can be IP-based or name-based. IP-based virtual hosting uses a different IP address for each website. Name-based virtual hosting uses the clients HTTP/1.1 headers to figure out the hostname, which allows the websites to share the same IP address.
To setup Apache to use
name-based virtual hosting, add a
VirtualHost
block for each website. For
example, for the webserver named www.domain.tld
with a
virtual domain of www.someotherdomain.tld
,
add the following entries to
httpd.conf
:
<VirtualHost *> ServerNamewww.domain.tld
DocumentRoot/www/domain.tld
</VirtualHost> <VirtualHost *> ServerNamewww.someotherdomain.tld
DocumentRoot/www/someotherdomain.tld
</VirtualHost>
For each virtual host, replace the values for
ServerName
and
DocumentRoot
with the values to be
used.
For more information about setting up virtual hosts,
consult the official Apache
documentation at: http://httpd.apache.org/docs/vhosts/
.
Apache uses modules to augment
the functionality provided by the basic server. Refer to http://httpd.apache.org/docs/current/mod/
for a complete listing of and the configuration details for
the available modules.
In FreeBSD, some modules can be compiled with the
www/apache24 port. Type make
config
within
/usr/ports/www/apache24
to see which
modules are available and which are enabled by default. If
the module is not compiled with the port, the FreeBSD Ports
Collection provides an easy way to install many modules. This
section describes three of the most commonly used
modules.
The mod_ssl
module uses the
OpenSSL library to provide strong
cryptography via the Secure Sockets Layer
(SSLv3) and Transport Layer Security
(TLSv1) protocols. This module provides
everything necessary to request a signed certificate from a
trusted certificate signing authority to run a secure web
server on FreeBSD.
In FreeBSD, mod_ssl
module is enabled
by default in both the package and the port. The available
configuration directives are explained at http://httpd.apache.org/docs/current/mod/mod_ssl.html
.
The
mod_perl
module makes it possible to
write Apache modules in
Perl. In addition, the
persistent interpreter embedded in the server avoids the
overhead of starting an external interpreter and the penalty
of Perl start-up time.
The mod_perl
can be installed using
the www/mod_perl2 package or port.
Documentation for using this module can be found at http://perl.apache.org/docs/2.0/index.html
.
PHP: Hypertext Preprocessor (PHP) is a general-purpose scripting language that is especially suited for web development. Capable of being embedded into HTML, its syntax draws upon C, Java™, and Perl with the intention of allowing web developers to write dynamically generated webpages quickly.
To gain support for PHP5 for the
Apache web server, install the
www/mod_php56 package or port. This will
install and configure the modules required to support
dynamic PHP applications. The
installation will automatically add this line to
/usr/local/etc/apache2
:4
/httpd.conf
LoadModule php5_module libexec/apache24/libphp5.so
Then, perform a graceful restart to load the PHP module:
#
apachectl graceful
The PHP support provided by www/mod_php56 is limited. Additional support can be installed using the lang/php56-extensions port which provides a menu driven interface to the available PHP extensions.
Alternatively, individual extensions can be installed using the appropriate port. For instance, to add PHP support for the MySQL database server, install databases/php56-mysql.
After installing an extension, the Apache server must be reloaded to pick up the new configuration changes:
#
apachectl graceful
In addition to mod_perl and mod_php, other languages are available for creating dynamic web content. These include Django and Ruby on Rails.
Django is a BSD-licensed framework designed to allow developers to write high performance, elegant web applications quickly. It provides an object-relational mapper so that data types are developed as Python objects. A rich dynamic database-access API is provided for those objects without the developer ever having to write SQL. It also provides an extensible template system so that the logic of the application is separated from the HTML presentation.
Django depends on mod_python
, and
an SQL database engine. In FreeBSD, the
www/py-django port automatically installs
mod_python
and supports the
PostgreSQL,
MySQL, or
SQLite databases, with the
default being SQLite. To change
the database engine, type make config
within /usr/ports/www/py-django
, then
install the port.
Once Django is installed, the application will need a project directory along with the Apache configuration in order to use the embedded Python interpreter. This interpreter is used to call the application for specific URLs on the site.
To configure Apache to pass
requests for certain URLs to the web
application, add the following to
httpd.conf
, specifying the full path to
the project directory:
<Location "/">
SetHandler python-program
PythonPath "['/dir/to/the/django/packages/
'] + sys.path"
PythonHandler django.core.handlers.modpython
SetEnv DJANGO_SETTINGS_MODULE mysite.settings
PythonAutoReload On
PythonDebug On
</Location>
Refer to https://docs.djangoproject.com
for more information on how to use
Django.
Ruby on Rails is another open source web framework that provides a full development stack. It is optimized to make web developers more productive and capable of writing powerful applications quickly. On FreeBSD, it can be installed using the www/rubygem-rails package or port.
Refer to http://guides.rubyonrails.org
for more information on how to use Ruby on
Rails.
The File Transfer Protocol (FTP) provides users with a simple way to transfer files to and from an FTP server. FreeBSD includes FTP server software, ftpd, in the base system.
FreeBSD provides several configuration files for controlling access to the FTP server. This section summarizes these files. Refer to ftpd(8) for more details about the built-in FTP server.
The most important configuration step is deciding which
accounts will be allowed access to the FTP
server. A FreeBSD system has a number of system accounts which
should not be allowed FTP access. The list
of users disallowed any FTP access can be
found in /etc/ftpusers
. By default, it
includes system accounts. Additional users that should not be
allowed access to FTP can be added.
In some cases it may be desirable to restrict the access
of some users without preventing them completely from using
FTP. This can be accomplished be creating
/etc/ftpchroot
as described in
ftpchroot(5). This file lists users and groups subject
to FTP access restrictions.
To enable anonymous FTP access to the
server, create a user named ftp
on the FreeBSD system. Users
will then be able to log on to the
FTP server with a username of
ftp
or anonymous
. When prompted for
the password, any input will be accepted, but by convention,
an email address should be used as the password. The
FTP server will call chroot(2) when an
anonymous user logs in, to restrict access to only the home
directory of the ftp
user.
There are two text files that can be created to specify
welcome messages to be displayed to FTP
clients. The contents of
/etc/ftpwelcome
will be displayed to
users before they reach the login prompt. After a successful
login, the contents of
/etc/ftpmotd
will be displayed. Note
that the path to this file is relative to the login
environment, so the contents of
~ftp/etc/ftpmotd
would be displayed for
anonymous users.
Once the FTP server has been
configured, set the appropriate variable in
/etc/rc.conf
to start the service during
boot:
ftpd_enable="YES"
To start the service now:
#
service ftpd start
Test the connection to the FTP server by typing:
%
ftp localhost
The ftpd daemon uses
syslog(3) to log messages. By default, the system log
daemon will write messages related to FTP
in /var/log/xferlog
. The location of
the FTP log can be modified by changing the
following line in
/etc/syslog.conf
:
ftp.info /var/log/xferlog
Be aware of the potential problems involved with running an anonymous FTP server. In particular, think twice about allowing anonymous users to upload files. It may turn out that the FTP site becomes a forum for the trade of unlicensed commercial software or worse. If anonymous FTP uploads are required, then verify the permissions so that these files cannot be read by other anonymous users until they have been reviewed by an administrator.
Samba is a popular open source software package that provides file and print services using the SMB/CIFS protocol. This protocol is built into Microsoft® Windows® systems. It can be added to non-Microsoft® Windows® systems by installing the Samba client libraries. The protocol allows clients to access shared data and printers. These shares can be mapped as a local disk drive and shared printers can be used as if they were local printers.
On FreeBSD, the Samba client libraries can be installed using the net/samba48 port or package. The client provides the ability for a FreeBSD system to access SMB/CIFS shares in a Microsoft® Windows® network.
A FreeBSD system can also be configured to act as a Samba server by installing the same net/samba48 port or package. This allows the administrator to create SMB/CIFS shares on the FreeBSD system which can be accessed by clients running Microsoft® Windows® or the Samba client libraries.
Samba is configured in
/usr/local/etc/smb4.conf
. This file must
be created before Samba
can be used.
A simple smb4.conf
to share
directories and printers with Windows® clients in a
workgroup is shown here. For more complex setups
involving LDAP or Active Directory, it is easier to use
samba-tool(8) to create the initial
smb4.conf
.
[global] workgroup = WORKGROUP server string = Samba Server Version %v netbios name = ExampleMachine wins support = Yes security = user passdb backend = tdbsam # Example: share /usr/src accessible only to 'developer' user [src] path = /usr/src valid users = developer writable = yes browsable = yes read only = no guest ok = no public = no create mask = 0666 directory mask = 0755
Settings that describe the network are added in
/usr/local/etc/smb4.conf
:
workgroup
The name of the workgroup to be served.
netbios name
The NetBIOS name by which a Samba server is known. By default, it is the same as the first component of the host's DNS name.
server string
The string that will be displayed in the output of
net view
and some other
networking tools that seek to display descriptive text
about the server.
wins support
Whether Samba will act as a WINS server. Do not enable support for WINS on more than one server on the network.
The most important settings in
/usr/local/etc/smb4.conf
are the
security model and the backend password format. These
directives control the options:
security
The most common settings are
security = share
and
security = user
. If the clients
use usernames that are the same as their usernames on
the FreeBSD machine, user level security should be
used. This is the default security policy and it
requires clients to first log on before they can
access shared resources.
In share level security, clients do not need to log onto the server with a valid username and password before attempting to connect to a shared resource. This was the default security model for older versions of Samba.
passdb backend
Samba has several
different backend authentication models. Clients may
be authenticated with LDAP, NIS+, an SQL database,
or a modified password file. The recommended
authentication method, tdbsam
,
is ideal for simple networks and is covered here.
For larger or more complex networks,
ldapsam
is recommended.
smbpasswd
was the former default and is now obsolete.
FreeBSD user accounts must be mapped to the
SambaSAMAccount
database for
Windows® clients to access the share.
Map existing FreeBSD user accounts using
pdbedit(8):
#
pdbedit -a
username
This section has only mentioned the most commonly used settings. Refer to the Official Samba HOWTO for additional information about the available configuration options.
To enable Samba at boot time,
add the following line to
/etc/rc.conf
:
samba_server_enable="YES"
To start Samba now:
#
service samba_server start
Performing sanity check on Samba configuration: OK Starting nmbd. Starting smbd.
Samba consists of three
separate daemons. Both the nmbd
and smbd daemons are started by
samba_enable
. If winbind name resolution
is also required, set:
winbindd_enable="YES"
Samba can be stopped at any time by typing:
#
service samba_server stop
Samba is a complex software
suite with functionality that allows broad integration with
Microsoft® Windows® networks. For more information about
functionality beyond the basic configuration described here,
refer to http://www.samba.org
.
Over time, a computer's clock is prone to drift. This is problematic as many network services require the computers on a network to share the same accurate time. Accurate time is also needed to ensure that file timestamps stay consistent. The Network Time Protocol (NTP) is one way to provide clock accuracy in a network.
FreeBSD includes ntpd(8) which can be configured to query other NTP servers to synchronize the clock on that machine or to provide time services to other computers in the network.
This section describes how to configure
ntpd on FreeBSD. Further documentation
can be found in /usr/share/doc/ntp/
in HTML
format.
On FreeBSD, the built-in ntpd can
be used to synchronize a system's clock.
Ntpd is configured using rc.conf(5)
variables and /etc/ntp.conf
, as detailed
in the following sections.
Ntpd communicates with its network peers using UDP packets. Any firewalls between your machine and its NTP peers must be configured to allow UDP packets in and out on port 123.
Ntpd reads
/etc/ntp.conf
to determine which NTP servers to query.
Choosing several NTP servers is recommended
in case one of the servers becomes unreachable or its clock proves
unreliable. As ntpd receives responses,
it favors reliable servers over the less reliable ones. The servers
which are queried can be local to the network, provided by an
ISP, or selected from an
online list of publicly accessible NTP
servers.
When choosing a public NTP server, select one
that is geographically close and review its usage policy. The
pool
configuration keyword selects one or more
servers from a pool of servers. An
online list of publicly accessible NTP
pools
is available, organized by geographic area. In addition, FreeBSD
provides a project-sponsored pool,
0.freebsd.pool.ntp.org
.
/etc/ntp.conf
This is a simple example of an ntp.conf
file. It can safely be used as-is; it contains the recommended
restrict
options for operation on a
publicly-accessible network connection.
# Disallow ntpq control/query access. Allow peers to be added only # based on pool and server statements in this file. restrict default limited kod nomodify notrap noquery nopeer restrict source limited kod nomodify notrap noquery # Allow unrestricted access from localhost for queries and control. restrict 127.0.0.1 restrict ::1 # Add a specific server. server ntplocal.example.com iburst # Add FreeBSD pool servers until 3-6 good servers are available. tos minclock 3 maxclock 6 pool 0.freebsd.pool.ntp.org iburst # Use a local leap-seconds file. leapfile "/var/db/ntpd.leap-seconds.list"
The format of this file is described in ntp.conf(5). The descriptions below provide a quick overview of just the keywords used in the sample file above.
By default, an NTP server is accessible
to any network host. The restrict
keyword
controls which systems can access the server. Multiple
restrict
entries are supported, each one
refining the restrictions given in previous statements. The
values shown in the example grant the local system full query
and control access, while allowing remote systems only the
ability to query the time. For more details, refer to the
Access Control Support
subsection of
ntp.conf(5).
The server
keyword specifies a single
server to query. The file can contain multiple server keywords,
with one server listed on each line. The pool
keyword specifies a pool of servers.
Ntpd will add one or more
servers from this pool as needed to reach the number of peers
specified using the tos minclock
value. The
iburst
keyword directs
ntpd to perform a burst of eight quick
packet exchanges with a server when contact is first established,
to help quickly synchronize system time.
The leapfile
keyword specifies the location
of a file containing information about leap seconds. The file is
updated automatically by periodic(8). The file location
specified by this keyword must match the location set in the
ntp_db_leapfile
variable in
/etc/rc.conf
.
Set ntpd_enable=YES
to start
ntpd at boot time. Once
ntpd_enable=YES
has been added
to /etc/rc.conf
,
ntpd can be started immediately without
rebooting the system by typing:
#
service ntpd start
Only ntpd_enable
must be set to use ntpd.
The rc.conf
variables listed below may also be
set as needed.
Set ntpd_sync_on_start=YES
to allow
ntpd to step the clock any amount, one
time at startup. Normally ntpd will
log an error message and exit if the clock is off by more than
1000 seconds. This option is especially useful on systems without
a battery-backed realtime clock.
Set ntpd_oomprotect=YES
to protect the
ntpd daemon from being killed by
the system attempting to recover from an Out Of Memory
(OOM) condition.
Set ntpd_config=
to the location of
an alternate ntp.conf
file.
Set ntpd_flags=
to contain any other
ntpd flags as needed, but avoid using
these flags which are managed internally by
/etc/rc.d/ntpd
:
-p
(pid file location)
-c
(set ntpd_config=
instead)
Ntpd on FreeBSD can start and
run as an unpriveleged user. Doing so requires the
mac_ntpd(4) policy module. The
/etc/rc.d/ntpd
startup script first
examines the NTP configuration. If possible, it loads the
mac_ntpd
module, then starts
ntpd as unpriveleged user
ntpd
(user id 123).
To avoid problems with file and directory access, the startup
script will not automatically start
ntpd as ntpd
when the configuration contains any file-related options.
The presence of any of the following in
ntpd_flags
requires manual configuration
as described below to run as the ntpd
user:
-f or --driftfile
-i or --jaildir
-k or --keyfile
-l or --logfile
-s or --statsdir
The presence of any of the following keywords in
ntp.conf
requires manual configuration
as described below to run as the ntpd
user:
crypto
driftfile
key
logdir
statsdir
To manually configure ntpd
to run as user ntpd
you must:
Ensure that the ntpd
user has access to all the files and directories specified
in the configuration.
Arrange for the mac_ntpd
module to be loaded or compiled into the kernel. See
mac_ntpd(4) for details.
Set ntpd_user="ntpd"
in
/etc/rc.conf
ntpd does not need a permanent
connection to the Internet to function properly. However, if
a PPP connection is configured to dial out
on demand, NTP traffic should be prevented
from triggering a dial out or keeping the connection alive.
This can be configured with filter
directives in /etc/ppp/ppp.conf
. For
example:
set filter dial 0 deny udp src eq 123 # Prevent NTP traffic from initiating dial out set filter dial 1 permit 0 0 set filter alive 0 deny udp src eq 123 # Prevent incoming NTP traffic from keeping the connection open set filter alive 1 deny udp dst eq 123 # Prevent outgoing NTP traffic from keeping the connection open set filter alive 2 permit 0/0 0/0
For more details, refer to the
PACKET FILTERING
section in ppp(8) and
the examples in
/usr/share/examples/ppp/
.
Some Internet access providers block low-numbered ports, preventing NTP from functioning since replies never reach the machine.
iSCSI is a way to share storage over a network. Unlike NFS, which works at the file system level, iSCSI works at the block device level.
In iSCSI terminology, the system that shares the storage is known as the target. The storage can be a physical disk, or an area representing multiple disks or a portion of a physical disk. For example, if the disk(s) are formatted with ZFS, a zvol can be created to use as the iSCSI storage.
The clients which access the iSCSI
storage are called initiators. To
initiators, the storage available through
iSCSI appears as a raw, unformatted disk
known as a LUN. Device nodes for the disk
appear in /dev/
and the device must be
separately formatted and mounted.
FreeBSD provides a native, kernel-based iSCSI target and initiator. This section describes how to configure a FreeBSD system as a target or an initiator.
To configure an iSCSI target, create
the /etc/ctl.conf
configuration file, add
a line to /etc/rc.conf
to make sure the
ctld(8) daemon is automatically started at boot, and then
start the daemon.
The following is an example of a simple
/etc/ctl.conf
configuration file. Refer
to ctl.conf(5) for a more complete description of this
file's available options.
portal-group pg0 { discovery-auth-group no-authentication listen 0.0.0.0 listen [::] } target iqn.2012-06.com.example:target0 { auth-group no-authentication portal-group pg0 lun 0 { path /data/target0-0 size 4G } }
The first entry defines the pg0
portal
group. Portal groups define which network addresses the
ctld(8) daemon will listen on. The
discovery-auth-group no-authentication
entry indicates that any initiator is allowed to perform
iSCSI target discovery without
authentication. Lines three and four configure ctld(8)
to listen on all IPv4
(listen 0.0.0.0
) and
IPv6 (listen [::]
)
addresses on the default port of 3260.
It is not necessary to define a portal group as there is a
built-in portal group called default
. In
this case, the difference between default
and pg0
is that with
default
, target discovery is always denied,
while with pg0
, it is always
allowed.
The second entry defines a single target. Target has two
possible meanings: a machine serving iSCSI
or a named group of LUNs. This example
uses the latter meaning, where
iqn.2012-06.com.example:target0
is the
target name. This target name is suitable for testing
purposes. For actual use, change
com.example
to the real domain name,
reversed. The 2012-06
represents the year
and month of acquiring control of that domain name, and
target0
can be any value. Any number of
targets can be defined in this configuration file.
The auth-group no-authentication
line
allows all initiators to connect to the specified target and
portal-group pg0
makes the target reachable
through the pg0
portal group.
The next section defines the LUN. To
the initiator, each LUN will be visible as
a separate disk device. Multiple LUNs can
be defined for each target. Each LUN is
identified by a number, where LUN 0 is
mandatory. The path /data/target0-0
line
defines the full path to a file or zvol backing the
LUN. That path must exist before starting
ctld(8). The second line is optional and specifies the
size of the LUN.
Next, to make sure the ctld(8) daemon is started at
boot, add this line to
/etc/rc.conf
:
ctld_enable="YES"
To start ctld(8) now, run this command:
#
service ctld start
As the ctld(8) daemon is started, it reads
/etc/ctl.conf
. If this file is edited
after the daemon starts, use this command so that the changes
take effect immediately:
#
service ctld reload
The previous example is inherently insecure as it uses no authentication, granting anyone full access to all targets. To require a username and password to access targets, modify the configuration as follows:
auth-group ag0 { chap username1 secretsecret chap username2 anothersecret } portal-group pg0 { discovery-auth-group no-authentication listen 0.0.0.0 listen [::] } target iqn.2012-06.com.example:target0 { auth-group ag0 portal-group pg0 lun 0 { path /data/target0-0 size 4G } }
The auth-group
section defines
username and password pairs. An initiator trying to connect
to iqn.2012-06.com.example:target0
must
first specify a defined username and secret. However,
target discovery is still permitted without authentication.
To require target discovery authentication, set
discovery-auth-group
to a defined
auth-group
name instead of
no-authentication
.
It is common to define a single exported target for every initiator. As a shorthand for the syntax above, the username and password can be specified directly in the target entry:
target iqn.2012-06.com.example:target0 { portal-group pg0 chap username1 secretsecret lun 0 { path /data/target0-0 size 4G } }
The iSCSI initiator described in this section is supported starting with FreeBSD 10.0-RELEASE. To use the iSCSI initiator available in older versions, refer to iscontrol(8).
The iSCSI initiator requires that the
iscsid(8) daemon is running. This daemon does not use a
configuration file. To start it automatically at boot, add
this line to /etc/rc.conf
:
iscsid_enable="YES"
To start iscsid(8) now, run this command:
#
service iscsid start
Connecting to a target can be done with or without an
/etc/iscsi.conf
configuration file. This
section demonstrates both types of connections.
To connect an initiator to a single target, specify the IP address of the portal and the name of the target:
#
iscsictl -A -p
10.10.10.10
-tiqn.2012-06.com.example:target0
To verify if the connection succeeded, run
iscsictl
without any arguments. The
output should look similar to this:
Target name Target portal State iqn.2012-06.com.example:target0 10.10.10.10 Connected: da0
In this example, the iSCSI session
was successfully established, with
/dev/da0
representing the attached
LUN. If the
iqn.2012-06.com.example:target0
target
exports more than one LUN, multiple
device nodes will be shown in that section of the
output:
Connected: da0 da1 da2.
Any errors will be reported in the output, as well as the system logs. For example, this message usually means that the iscsid(8) daemon is not running:
Target name Target portal State iqn.2012-06.com.example:target0 10.10.10.10 Waiting for iscsid(8)
The following message suggests a networking problem, such as a wrong IP address or port:
Target name Target portal State iqn.2012-06.com.example:target0 10.10.10.11 Connection refused
This message means that the specified target name is wrong:
Target name Target portal State iqn.2012-06.com.example:target0 10.10.10.10 Not found
This message means that the target requires authentication:
Target name Target portal State iqn.2012-06.com.example:target0 10.10.10.10 Authentication failed
To specify a CHAP username and secret, use this syntax:
#
iscsictl -A -p
10.10.10.10
-tiqn.2012-06.com.example:target0
-uuser
-ssecretsecret
To connect using a configuration file, create
/etc/iscsi.conf
with contents like
this:
t0 { TargetAddress = 10.10.10.10 TargetName = iqn.2012-06.com.example:target0 AuthMethod = CHAP chapIName = user chapSecret = secretsecret }
The t0
specifies a nickname for the
configuration file section. It will be used by the
initiator to specify which configuration to use. The other
lines specify the parameters to use during connection. The
TargetAddress
and
TargetName
are mandatory, whereas the
other options are optional. In this example, the
CHAP username and secret are
shown.
To connect to the defined target, specify the nickname:
#
iscsictl -An
t0
Alternately, to connect to all targets defined in the configuration file, use:
#
iscsictl -Aa
To make the initiator automatically connect to all
targets in /etc/iscsi.conf
, add the
following to /etc/rc.conf
:
iscsictl_enable="YES" iscsictl_flags="-Aa"
Firewalls make it possible to filter the incoming and outgoing traffic that flows through a system. A firewall can use one or more sets of “rules” to inspect network packets as they come in or go out of network connections and either allows the traffic through or blocks it. The rules of a firewall can inspect one or more characteristics of the packets such as the protocol type, source or destination host address, and source or destination port.
Firewalls can enhance the security of a host or a network. They can be used to do one or more of the following:
Protect and insulate the applications, services, and machines of an internal network from unwanted traffic from the public Internet.
Limit or disable access from hosts of the internal network to services of the public Internet.
Support network address translation (NAT), which allows an internal network to use private IP addresses and share a single connection to the public Internet using either a single IP address or a shared pool of automatically assigned public addresses.
FreeBSD has three firewalls built into the base system: PF, IPFW, and IPFILTER, also known as IPF. FreeBSD also provides two traffic shapers for controlling bandwidth usage: altq(4) and dummynet(4). ALTQ has traditionally been closely tied with PF and dummynet with IPFW. Each firewall uses rules to control the access of packets to and from a FreeBSD system, although they go about it in different ways and each has a different rule syntax.
FreeBSD provides multiple firewalls in order to meet the different requirements and preferences for a wide variety of users. Each user should evaluate which firewall best meets their needs.
After reading this chapter, you will know:
How to define packet filtering rules.
The differences between the firewalls built into FreeBSD.
How to use and configure the PF firewall.
How to use and configure the IPFW firewall.
How to use and configure the IPFILTER firewall.
Before reading this chapter, you should:
Understand basic FreeBSD and Internet concepts.
Since all firewalls are based on inspecting the values of selected packet control fields, the creator of the firewall ruleset must have an understanding of how TCP/IP works, what the different values in the packet control fields are, and how these values are used in a normal session conversation. For a good introduction, refer to Daryl's TCP/IP Primer.
A ruleset contains a group of rules which pass or block packets based on the values contained in the packet. The bi-directional exchange of packets between hosts comprises a session conversation. The firewall ruleset processes both the packets arriving from the public Internet, as well as the packets produced by the system as a response to them. Each TCP/IP service is predefined by its protocol and listening port. Packets destined for a specific service originate from the source address using an unprivileged port and target the specific service port on the destination address. All the above parameters can be used as selection criteria to create rules which will pass or block services.
To lookup unknown port numbers, refer to
/etc/services
. Alternatively, visit http://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers
and do a port number lookup to find the purpose of a particular
port number.
Check out this link for port numbers used by Trojans
.
FTP has two modes: active mode and passive mode. The
difference is in how the data channel is acquired. Passive
mode is more secure as the data channel is acquired by the
ordinal ftp session requester. For a good explanation of FTP
and the different modes, see http://www.slacksite.com/other/ftp.html
.
A firewall ruleset can be either “exclusive” or “inclusive”. An exclusive firewall allows all traffic through except for the traffic matching the ruleset. An inclusive firewall does the reverse as it only allows traffic matching the rules through and blocks everything else.
An inclusive firewall offers better control of the outgoing traffic, making it a better choice for systems that offer services to the public Internet. It also controls the type of traffic originating from the public Internet that can gain access to a private network. All traffic that does not match the rules is blocked and logged. Inclusive firewalls are generally safer than exclusive firewalls because they significantly reduce the risk of allowing unwanted traffic.
Unless noted otherwise, all configuration and example rulesets in this chapter create inclusive firewall rulesets.
Security can be tightened further using a “stateful firewall”. This type of firewall keeps track of open connections and only allows traffic which either matches an existing connection or opens a new, allowed connection.
Stateful filtering treats traffic as a bi-directional exchange of packets comprising a session. When state is specified on a matching rule the firewall dynamically generates internal rules for each anticipated packet being exchanged during the session. It has sufficient matching capabilities to determine if a packet is valid for a session. Any packets that do not properly fit the session template are automatically rejected.
When the session completes, it is removed from the dynamic state table.
Stateful filtering allows one to focus on blocking/passing new sessions. If the new session is passed, all its subsequent packets are allowed automatically and any impostor packets are automatically rejected. If a new session is blocked, none of its subsequent packets are allowed. Stateful filtering provides advanced matching abilities capable of defending against the flood of different attack methods employed by attackers.
NAT stands for Network Address Translation. NAT function enables the private LAN behind the firewall to share a single ISP-assigned IP address, even if that address is dynamically assigned. NAT allows each computer in the LAN to have Internet access, without having to pay the ISP for multiple Internet accounts or IP addresses.
NAT will automatically translate the private LAN IP address for each system on the LAN to the single public IP address as packets exit the firewall bound for the public Internet. It also performs the reverse translation for returning packets.
According to RFC 1918, the following IP address ranges are reserved for private networks which will never be routed directly to the public Internet, and therefore are available for use with NAT:
10.0.0.0/8
.
172.16.0.0/12
.
192.168.0.0/16
.
When working with the firewall rules, be very careful. Some configurations can lock the administrator out of the server. To be on the safe side, consider performing the initial firewall configuration from the local console rather than doing it remotely over ssh.
Since FreeBSD 5.3, a ported version of OpenBSD's PF firewall has been included as an integrated part of the base system. PF is a complete, full-featured firewall that has optional support for ALTQ (Alternate Queuing), which provides Quality of Service (QoS).
The OpenBSD Project maintains the definitive reference for PF in the PF FAQ. Peter Hansteen maintains a thorough PF tutorial at http://home.nuug.no/~peter/pf/.
When reading the PF FAQ, keep in mind that FreeBSD's version of PF has diverged substantially from the upstream OpenBSD version over the years. Not all features work the same way on FreeBSD as they do in OpenBSD and vice versa.
The FreeBSD packet filter mailing list is a good place to ask questions about configuring and running the PF firewall. Check the mailing list archives before asking a question as it may have already been answered.
This section of the Handbook focuses on PF as it pertains to FreeBSD. It demonstrates how to enable PF and ALTQ. It also provides several examples for creating rulesets on a FreeBSD system.
To use PF, its kernel
module must be first loaded. This section describes the
entries that can be added to /etc/rc.conf
to enable PF.
Start by adding pf_enable=yes
to
/etc/rc.conf
:
#
sysrc pf_enable=yes
Additional options, described in pfctl(8), can be
passed to PF when it is started.
Add or change this entry in /etc/rc.conf
and specify any required flags between the two quotes
(""
):
pf_flags="" # additional flags for pfctl startup
PF will not start if it cannot
find its ruleset configuration file. By default, FreeBSD does
not ship with a ruleset and there is no
/etc/pf.conf
. Example rulesets can be
found in /usr/share/examples/pf/
. If a
custom ruleset has been saved somewhere else, add a line to
/etc/rc.conf
which specifies the full
path to the file:
pf_rules="/path/to/pf.conf
"
Logging support for PF is
provided by pflog(4). To enable logging support, add
pflog_enable=yes
to
/etc/rc.conf
:
#
sysrc pflog_enable=yes
The following lines can also be added to change the default location of the log file or to specify any additional flags to pass to pflog(4) when it is started:
pflog_logfile="/var/log/pflog" # where pflogd should store the logfile pflog_flags="" # additional flags for pflogd startup
Finally, if there is a LAN behind the firewall and packets need to be forwarded for the computers on the LAN, or NAT is required, enable the following option:
gateway_enable="YES" # Enable as LAN gateway
After saving the needed edits, PF can be started with logging support by typing:
#
service pf start
#
service pflog start
By default, PF reads its
configuration rules from /etc/pf.conf
and
modifies, drops, or passes packets according to the rules or
definitions specified in this file. The FreeBSD installation
includes several sample files located in
/usr/share/examples/pf/
. Refer to the
PF
FAQ for complete coverage
of PF rulesets.
To control PF, use
pfctl
. Table 30.1, “Useful pfctl
Options” summarizes
some useful options to this command. Refer to pfctl(8)
for a description of all available options:
pfctl
OptionsCommand | Purpose |
---|---|
pfctl
-e | Enable PF. |
pfctl
-d | Disable PF. |
pfctl -F all
-f /etc/pf.conf | Flush all NAT, filter, state,
and table rules and reload
/etc/pf.conf . |
pfctl -s [ rules | nat |
states ] | Report on the filter rules, NAT rules, or state table. |
pfctl -vnf
/etc/pf.conf | Check /etc/pf.conf for
errors, but do not load ruleset. |
security/sudo is useful for running
commands like pfctl
that require elevated
privileges. It can be installed from the Ports
Collection.
To keep an eye on the traffic that passes through the PF firewall, consider installing the sysutils/pftop package or port. Once installed, pftop can be run to view a running snapshot of traffic in a format which is similar to top(1).
This section demonstrates how to create a customized ruleset. It starts with the simplest of rulesets and builds upon its concepts using several examples to demonstrate real-world usage of PF's many features.
The simplest possible ruleset is for a single machine
that does not run any services and which needs access to one
network, which may be the Internet. To create this minimal
ruleset, edit /etc/pf.conf
so it looks
like this:
block in all pass out all keep state
The first rule denies all incoming traffic by default. The second rule allows connections created by this system to pass out, while retaining state information on those connections. This state information allows return traffic for those connections to pass back and should only be used on machines that can be trusted. The ruleset can be loaded with:
#
pfctl -e ; pfctl -f /etc/pf.conf
In addition to keeping state, PF provides lists and macros which can be defined for use when creating rules. Macros can include lists and need to be defined before use. As an example, insert these lines at the very top of the ruleset:
tcp_services = "{ ssh, smtp, domain, www, pop3, auth, pop3s }" udp_services = "{ domain }"
PF understands port names as
well as port numbers, as long as the names are listed in
/etc/services
. This example creates two
macros. The first is a list of seven
TCP port names and the second is one
UDP port name. Once defined, macros can be
used in rules. In this example, all traffic is blocked except
for the connections initiated by this system for the seven
specified TCP services and the one
specified UDP service:
tcp_services = "{ ssh, smtp, domain, www, pop3, auth, pop3s }" udp_services = "{ domain }" block all pass out proto tcp to any port $tcp_services keep state pass proto udp to any port $udp_services keep state
Even though UDP is considered to be a stateless protocol, PF is able to track some state information. For example, when a UDP request is passed which asks a name server about a domain name, PF will watch for the response to pass it back.
Whenever an edit is made to a ruleset, the new rules must be loaded so they can be used:
#
pfctl -f /etc/pf.conf
If there are no syntax errors, pfctl
will not output any messages during the rule load. Rules can
also be tested before attempting to load them:
#
pfctl -nf /etc/pf.conf
Including -n
causes the rules to be
interpreted only, but not loaded. This provides an
opportunity to correct any errors. At all times, the last
valid ruleset loaded will be enforced until either
PF is disabled or a new ruleset is
loaded.
Adding -v
to a pfctl
ruleset verify or load will display the fully parsed rules
exactly the way they will be loaded. This is extremely
useful when debugging rules.
This section demonstrates how to configure a FreeBSD system
running PF to act as a gateway
for at least one other machine. The gateway needs at least
two network interfaces, each connected to a separate
network. In this example, xl1
is
connected to the Internet and xl0
is
connected to the internal network.
First, enable the gateway to let the machine forward the network traffic it receives on one interface to another interface. This sysctl setting will forward IPv4 packets:
#
sysctl net.inet.ip.forwarding=1
To forward IPv6 traffic, use:
#
sysctl net.inet6.ip6.forwarding=1
To enable these settings at system boot, use
sysrc(8) to add them to
/etc/rc.conf
:
#
sysrc gateway_enable=yes
#
sysrc ipv6_gateway_enable=yes
Verify with ifconfig
that both of the
interfaces are up and running.
Next, create the PF rules to
allow the gateway to pass traffic. While the following rule
allows stateful traffic to pass from the Internet to hosts
on the network, the to
keyword does not
guarantee passage all the way from source to
destination:
pass in on xl1 from xl1:network to xl0:network port $ports keep state
That rule only lets the traffic pass in to the gateway on the internal interface. To let the packets go further, a matching rule is needed:
pass out on xl0 from xl1:network to xl0:network port $ports keep state
While these two rules will work, rules this specific are rarely needed. For a busy network admin, a readable ruleset is a safer ruleset. The remainder of this section demonstrates how to keep the rules as simple as possible for readability. For example, those two rules could be replaced with one rule:
pass from xl1:network to any port $ports keep state
The interface:network
notation can be
replaced with a macro to make the ruleset even more
readable. For example, a $localnet
macro
could be defined as the network directly attached to the
internal interface ($xl1:network
).
Alternatively, the definition of
$localnet
could be changed to an
IP address/netmask notation to denote
a network, such as 192.168.100.1/24
for a
subnet of private addresses.
If required, $localnet
could even be
defined as a list of networks. Whatever the specific needs,
a sensible $localnet
definition could be
used in a typical pass rule as follows:
pass from $localnet to any port $ports keep state
The following sample ruleset allows all traffic initiated by machines on the internal network. It first defines two macros to represent the external and internal 3COM interfaces of the gateway.
For dialup users, the external interface will use
tun0
. For an
ADSL connection, specifically those
using PPP over Ethernet
(PPPoE), the correct external
interface is tun0
, not the physical
Ethernet interface.
ext_if = "xl0" # macro for external interface - use tun0 for PPPoE int_if = "xl1" # macro for internal interface localnet = $int_if:network # ext_if IP address could be dynamic, hence ($ext_if) nat on $ext_if from $localnet to any -> ($ext_if) block all pass from { lo0, $localnet } to any keep state
This ruleset introduces the nat
rule
which is used to handle the network address translation from
the non-routable addresses inside the internal network to
the IP address assigned to the external
interface. The parentheses surrounding the last part of the
nat rule ($ext_if)
is included when the
IP address of the external interface is
dynamically assigned. It ensures that network traffic runs
without serious interruptions even if the external
IP address changes.
Note that this ruleset probably allows more traffic to pass out of the network than is needed. One reasonable setup could create this macro:
client_out = "{ ftp-data, ftp, ssh, domain, pop3, auth, nntp, http, \ https, cvspserver, 2628, 5999, 8000, 8080 }"
to use in the main pass rule:
pass inet proto tcp from $localnet to any port $client_out \ flags S/SA keep state
A few other pass rules may be needed. This one enables SSH on the external interface:
pass in inet proto tcp to $ext_if port ssh
This macro definition and rule allows DNS and NTP for internal clients:
udp_services = "{ domain, ntp }" pass quick inet proto { tcp, udp } to any port $udp_services keep state
Note the quick
keyword in this rule.
Since the ruleset consists of several rules, it is important
to understand the relationships between the rules in a
ruleset. Rules are evaluated from top to bottom, in the
sequence they are written. For each packet or connection
evaluated by PF,
the last matching rule in the ruleset
is the one which is applied. However, when a packet matches
a rule which contains the quick
keyword,
the rule processing stops and the packet is treated
according to that rule. This is very useful when an
exception to the general rules is needed.
Configuring working FTP rules can be problematic due to the nature of the FTP protocol. FTP pre-dates firewalls by several decades and is insecure in its design. The most common points against using FTP include:
Passwords are transferred in the clear.
The protocol demands the use of at least two TCP connections (control and data) on separate ports.
When a session is established, data is communicated using randomly selected ports.
All of these points present security challenges, even before considering any potential security weaknesses in client or server software. More secure alternatives for file transfer exist, such as sftp(1) or scp(1), which both feature authentication and data transfer over encrypted connections..
For those situations when FTP is required, PF provides redirection of FTP traffic to a small proxy program called ftp-proxy(8), which is included in the base system of FreeBSD. The role of the proxy is to dynamically insert and delete rules in the ruleset, using a set of anchors, to correctly handle FTP traffic.
To enable the FTP proxy, add this
line to /etc/rc.conf
:
ftpproxy_enable="YES"
Then start the proxy by running service
ftp-proxy start
.
For a basic configuration, three elements need to be
added to /etc/pf.conf
. First, the
anchors which the proxy will use to insert the rules it
generates for the FTP sessions:
nat-anchor "ftp-proxy/*" rdr-anchor "ftp-proxy/*"
Second, a pass rule is needed to allow FTP traffic in to the proxy.
Third, redirection and NAT rules need
to be defined before the filtering rules. Insert this
rdr
rule immediately after the
nat
rule:
rdr pass on $int_if proto tcp from any to any port ftp -> 127.0.0.1 port 8021
Finally, allow the redirected traffic to pass:
pass out proto tcp from $proxy to any port ftp
where $proxy
expands to the address
the proxy daemon is bound to.
Save /etc/pf.conf
, load the new
rules, and verify from a client that FTP
connections are working:
#
pfctl -f /etc/pf.conf
This example covers a basic setup where the clients in
the local network need to contact FTP
servers elsewhere. This basic configuration should
work well with most combinations of FTP
clients and servers. As shown in ftp-proxy(8), the
proxy's behavior can be changed in various ways by adding
options to the ftpproxy_flags=
line.
Some clients or servers may have specific quirks that must
be compensated for in the configuration, or there may be a
need to integrate the proxy in specific ways such as
assigning FTP traffic to a specific
queue.
For ways to run an FTP server
protected by PF and
ftp-proxy(8), configure a separate
ftp-proxy
in reverse mode, using
-R
, on a separate port with its own
redirecting pass rule.
Many of the tools used for debugging or troubleshooting a TCP/IP network rely on the Internet Control Message Protocol (ICMP), which was designed specifically with debugging in mind.
The ICMP protocol sends and receives control messages between hosts and gateways, mainly to provide feedback to a sender about any unusual or difficult conditions enroute to the target host. Routers use ICMP to negotiate packet sizes and other transmission parameters in a process often referred to as path MTU discovery.
From a firewall perspective, some ICMP control messages are vulnerable to known attack vectors. Also, letting all diagnostic traffic pass unconditionally makes debugging easier, but it also makes it easier for others to extract information about the network. For these reasons, the following rule may not be optimal:
pass inet proto icmp from any to any
One solution is to let all ICMP traffic from the local network through while stopping all probes from outside the network:
pass inet proto icmp from $localnet to any keep state pass inet proto icmp from any to $ext_if keep state
Additional options are available which demonstrate some of PF's flexibility. For example, rather than allowing all ICMP messages, one can specify the messages used by ping(8) and traceroute(8). Start by defining a macro for that type of message:
icmp_types = "echoreq"
and a rule which uses the macro:
pass inet proto icmp all icmp-type $icmp_types keep state
If other types of ICMP packets are
needed, expand icmp_types
to a list of
those packet types. Type more
/usr/src/sbin/pfctl/pfctl_parser.c
to see
the list of ICMP message types supported
by PF. Refer to http://www.iana.org/assignments/icmp-parameters/icmp-parameters.xhtml
for an explanation of each message type.
Since Unix traceroute
uses
UDP by default, another rule is needed to
allow Unix traceroute
:
# allow out the default range for traceroute(8): pass out on $ext_if inet proto udp from any to any port 33433 >< 33626 keep state
Since TRACERT.EXE
on Microsoft
Windows systems uses ICMP echo request
messages, only the first rule is needed to allow network
traces from those systems. Unix
traceroute
can be instructed to use other
protocols as well, and will use ICMP echo
request messages if -I
is used. Check the
traceroute(8) man page for details.
Internet protocols are designed to be device
independent, and one consequence of device independence is
that the optimal packet size for a given connection cannot
always be predicted reliably. The main constraint on
packet size is the Maximum Transmission
Unit (MTU) which sets the
upper limit on the packet size for an interface. Type
ifconfig
to view the
MTUs for a system's network
interfaces.
TCP/IP uses a process known as path
MTU discovery to determine the right
packet size for a connection. This process sends packets
of varying sizes with the “Do not fragment”
flag set, expecting an ICMP return
packet of “type 3, code 4” when the upper
limit has been reached. Type 3 means “destination
unreachable”, and code 4 is short for
“fragmentation needed, but the do-not-fragment flag
is set”. To allow path MTU discovery in order
to support connections to other MTUs,
add the destination unreachable
type to
the icmp_types
macro:
icmp_types = "{ echoreq, unreach }"
Since the pass rule already uses that macro, it does not need to be modified to support the new ICMP type:
pass inet proto icmp all icmp-type $icmp_types keep state
PF allows filtering on all variations of ICMP types and codes. The list of possible types and codes are documented in icmp(4) and icmp6(4).
Some types of data are relevant to filtering and
redirection at a given time, but their definition is too
long to be included in the ruleset file.
PF supports the use of tables,
which are defined lists that can be manipulated without
needing to reload the entire ruleset, and which can provide
fast lookups. Table names are always enclosed within
< >
, like this:
table <clients> { 192.168.2.0/24, !192.168.2.5 }
In this example, the 192.168.2.0/24
network is part of the table, except for the address
192.168.2.5
, which is excluded using the
!
operator. It is also possible to load
tables from files where each item is on a separate line, as
seen in this example
/etc/clients
:
192.168.2.0/24 !192.168.2.5
To refer to the file, define the table like this:
table <clients> persist file "/etc/clients"
Once the table is defined, it can be referenced by a rule:
pass inet proto tcp from <clients> to any port $client_out flags S/SA keep state
A table's contents can be manipulated live, using
pfctl
. This example adds another network
to the table:
#
pfctl -t clients -T add 192.168.1.0/16
Note that any changes made this way will take affect
now, making them ideal for testing, but will not survive a
power failure or reboot. To make the changes permanent,
modify the definition of the table in the ruleset or edit
the file that the table refers to. One can maintain the
on-disk copy of the table using a cron(8) job which
dumps the table's contents to disk at regular intervals,
using a command such as pfctl -t clients -T show
>/etc/clients
. Alternatively,
/etc/clients
can be updated with the
in-memory table contents:
#
pfctl -t clients -T replace -f /etc/clients
Those who run SSH on an external interface have probably seen something like this in the authentication logs:
Sep 26 03:12:34 skapet sshd[25771]: Failed password for root from 200.72.41.31 port 40992 ssh2 Sep 26 03:12:34 skapet sshd[5279]: Failed password for root from 200.72.41.31 port 40992 ssh2 Sep 26 03:12:35 skapet sshd[5279]: Received disconnect from 200.72.41.31: 11: Bye Bye Sep 26 03:12:44 skapet sshd[29635]: Invalid user admin from 200.72.41.31 Sep 26 03:12:44 skapet sshd[24703]: input_userauth_request: invalid user admin Sep 26 03:12:44 skapet sshd[24703]: Failed password for invalid user admin from 200.72.41.31 port 41484 ssh2
This is indicative of a brute force attack where somebody or some program is trying to discover the user name and password which will let them into the system.
If external SSH access is needed for legitimate users, changing the default port used by SSH can offer some protection. However, PF provides a more elegant solution. Pass rules can contain limits on what connecting hosts can do and violators can be banished to a table of addresses which are denied some or all access. It is even possible to drop all existing connections from machines which overreach the limits.
To configure this, create this table in the tables section of the ruleset:
table <bruteforce> persist
Then, somewhere early in the ruleset, add rules to block brute access while allowing legitimate access:
block quick from <bruteforce> pass inet proto tcp from any to $localnet port $tcp_services \ flags S/SA keep state \ (max-src-conn100
, max-src-conn-rate15/5
, \ overload <bruteforce> flush global)
The part in parentheses defines the limits and the numbers should be changed to meet local requirements. It can be read as follows:
max-src-conn
is the number of
simultaneous connections allowed from one host.
max-src-conn-rate
is the rate of new
connections allowed from any single host
(15
) per number of seconds
(5
).
overload <bruteforce>
means
that any host which exceeds these limits gets its address
added to the bruteforce
table. The
ruleset blocks all traffic from addresses in the
bruteforce
table.
Finally, flush global
says that when
a host reaches the limit, that all
(global
) of that host's connections will
be terminated (flush
).
These rules will not block slow bruteforcers, as described in http://home.nuug.no/~peter/hailmary2013/.
This example ruleset is intended mainly as an illustration. For example, if a generous number of connections in general are wanted, but the desire is to be more restrictive when it comes to ssh, supplement the rule above with something like the one below, early on in the rule set:
pass quick proto { tcp, udp } from any to any port ssh \ flags S/SA keep state \ (max-src-conn 15, max-src-conn-rate 5/3, \ overload <bruteforce> flush global)
It is worth noting that the overload mechanism is a general technique which does not apply exclusively to SSH, and it is not always optimal to entirely block all traffic from offenders.
For example, an overload rule could be used to protect a mail service or a web service, and the overload table could be used in a rule to assign offenders to a queue with a minimal bandwidth allocation or to redirect to a specific web page.
Over time, tables will be filled by overload rules and their size will grow incrementally, taking up more memory. Sometimes an IP address that is blocked is a dynamically assigned one, which has since been assigned to a host who has a legitimate reason to communicate with hosts in the local network.
For situations like these,
pfctl provides the ability to
expire table entries. For example, this command will remove
<bruteforce>
table entries which
have not been referenced for 86400
seconds:
#
pfctl -t bruteforce -T expire 86400
Similar functionality is provided by security/expiretable, which removes table entries which have not been accessed for a specified period of time.
Once installed, expiretable
can be run to remove <bruteforce>
table entries older than a specified age. This example
removes all entries older than 24 hours:
/usr/local/sbin/expiretable -v -d -t 24h bruteforce
Not to be confused with the spamd daemon which comes bundled with spamassassin, mail/spamd can be configured with PF to provide an outer defense against SPAM. This spamd hooks into the PF configuration using a set of redirections.
Spammers tend to send a large number of messages, and SPAM is mainly sent from a few spammer friendly networks and a large number of hijacked machines, both of which are reported to blacklists fairly quickly.
When an SMTP connection from an address in a blacklist is received, spamd presents its banner and immediately switches to a mode where it answers SMTP traffic one byte at a time. This technique, which is intended to waste as much time as possible on the spammer's end, is called tarpitting. The specific implementation which uses one byte SMTP replies is often referred to as stuttering.
This example demonstrates the basic procedure for setting up spamd with automatically updated blacklists. Refer to the man pages which are installed with mail/spamd for more information.
Install the mail/spamd package
or port. To use spamd's
greylisting features, fdescfs(5) must be mounted at
/dev/fd
. Add the following line to
/etc/fstab
:
fdescfs /dev/fd fdescfs rw 0 0
Then, mount the filesystem:
#
mount fdescfs
Next, edit the PF ruleset to include:
table <spamd> persist table <spamd-white> persist rdr pass on $ext_if inet proto tcp from <spamd> to \ { $ext_if, $localnet } port smtp -> 127.0.0.1 port 8025 rdr pass on $ext_if inet proto tcp from !<spamd-white> to \ { $ext_if, $localnet } port smtp -> 127.0.0.1 port 8025
The two tables <spamd>
and
<spamd-white>
are essential.
SMTP traffic from an address listed
in <spamd>
but not in
<spamd-white>
is redirected to
the spamd daemon listening at
port 8025.
The next step is to configure
spamd in
/usr/local/etc/spamd.conf
and to
add some rc.conf
parameters.
The installation of mail/spamd
includes a sample configuration file
(/usr/local/etc/spamd.conf.sample
)
and a man page for spamd.conf
.
Refer to these for additional configuration options
beyond those shown in this example.
One of the first lines in the configuration file
that does not begin with a #
comment
sign contains the block which defines the
all
list, which specifies the lists
to use:
all:\ :traplist:whitelist:
This entry adds the desired blacklists, separated by
colons (:
). To use a whitelist to
subtract addresses from a blacklist, add the name of the
whitelist immediately after the
name of that blacklist. For example:
:blacklist:whitelist:
.
This is followed by the specified blacklist's definition:
traplist:\ :black:\ :msg="SPAM. Your address %A has sent spam within the last 24 hours":\ :method=http:\ :file=www.openbsd.org/spamd/traplist.gz
where the first line is the name of the blacklist
and the second line specifies the list type. The
msg
field contains the message to
display to blacklisted senders during the
SMTP dialogue. The
method
field specifies how
spamd-setup fetches the list
data; supported methods are http
,
ftp
, from a
file
in a mounted file system, and
via exec
of an external program.
Finally, the file
field specifies
the name of the file spamd
expects to receive.
The definition of the specified whitelist is
similar, but omits the msg
field
since a message is not needed:
whitelist:\ :white:\ :method=file:\ :file=/var/mail/whitelist.txt
Using all the blacklists in the sample
spamd.conf
will blacklist large
blocks of the Internet. Administrators need to edit
the file to create an optimal configuration which uses
applicable data sources and, when necessary, uses
custom lists.
Next, add this entry to
/etc/rc.conf
. Additional flags are
described in the man page specified by the
comment:
spamd_flags="-v" # use "" and see spamd-setup(8) for flags
When finished, reload the ruleset, start
spamd by typing
service obspamd start
, and complete
the configuration using spamd-setup
.
Finally, create a cron(8) job which calls
spamd-setup
to update the tables at
reasonable intervals.
On a typical gateway in front of a mail server, hosts will soon start getting trapped within a few seconds to several minutes.
PF also supports
greylisting, which temporarily
rejects messages from unknown hosts with
45n
codes. Messages from
greylisted hosts which try again within a reasonable time
are let through. Traffic from senders which are set up to
behave within the limits set by RFC 1123 and RFC 2821 are
immediately let through.
More information about greylisting as a technique can be found at the greylisting.org web site. The most amazing thing about greylisting, apart from its simplicity, is that it still works. Spammers and malware writers have been very slow to adapt to bypass this technique.
The basic procedure for configuring greylisting is as follows:
Make sure that fdescfs(5) is mounted as described in Step 1 of the previous Procedure.
To run spamd in
greylisting mode, add this line to
/etc/rc.conf
:
spamd_grey="YES" # use spamd greylisting if YES
Refer to the spamd man page for descriptions of additional related parameters.
To complete the greylisting setup:
#
service obspamd restart
#
service obspamlogd start
Behind the scenes, the spamdb
database tool and the spamlogd
whitelist updater perform essential functions for the
greylisting feature. spamdb is
the administrator's main interface to managing the black,
grey, and white lists via the contents of the
/var/db/spamdb
database.
This section describes how
block-policy
, scrub
,
and antispoof
can be used to make the
ruleset behave sanely.
The block-policy
is an option which
can be set in the options
part of the
ruleset, which precedes the redirection and filtering rules.
This option determines which feedback, if any,
PF sends to hosts that are
blocked by a rule. The option has two possible values:
drop
drops blocked packets with no
feedback, and return
returns a status
code such as
Connection refused
.
If not set, the default policy is
drop
. To change the
block-policy
, specify the desired
value:
set block-policy return
In PF,
scrub
is a keyword which enables network
packet normalization. This process reassembles fragmented
packets and drops TCP packets that have invalid flag
combinations. Enabling scrub
provides a
measure of protection against certain kinds of attacks
based on incorrect handling of packet fragments. A number
of options are available, but the simplest form is suitable
for most configurations:
scrub in all
Some services, such as NFS, require specific fragment handling options. Refer to https://home.nuug.no/~peter/pf/en/scrub.html for more information.
This example reassembles fragments, clears the “do not fragment” bit, and sets the maximum segment size to 1440 bytes:
scrub in all fragment reassemble no-df max-mss 1440
The antispoof
mechanism protects
against activity from spoofed or forged
IP addresses, mainly by blocking packets
appearing on interfaces and in directions which are
logically not possible.
These rules weed out spoofed traffic coming in from the rest of the world as well as any spoofed packets which originate in the local network:
antispoof for $ext_if antispoof for $int_if
Even with a properly configured gateway to handle network address translation, one may have to compensate for other people's misconfigurations. A common misconfiguration is to let traffic with non-routable addresses out to the Internet. Since traffic from non-routeable addresses can play a part in several DoS attack techniques, consider explicitly blocking traffic from non-routeable addresses from entering the network through the external interface.
In this example, a macro containing non-routable addresses is defined, then used in blocking rules. Traffic to and from these addresses is quietly dropped on the gateway's external interface.
martians = "{ 127.0.0.0/8, 192.168.0.0/16, 172.16.0.0/12, \ 10.0.0.0/8, 169.254.0.0/16, 192.0.2.0/24, \ 0.0.0.0/8, 240.0.0.0/4 }" block drop in quick on $ext_if from $martians to any block drop out quick on $ext_if from any to $martians
On FreeBSD, ALTQ can be used with PF to provide Quality of Service (QOS). Once ALTQ is enabled, queues can be defined in the ruleset which determine the processing priority of outbound packets.
Before enabling ALTQ, refer to altq(4) to determine if the drivers for the network cards installed on the system support it.
ALTQ is not available as a loadable kernel module. If the system's interfaces support ALTQ, create a custom kernel using the instructions in Chapter 8, Configuring the FreeBSD Kernel. The following kernel options are available. The first is needed to enable ALTQ. At least one of the other options is necessary to specify the queueing scheduler algorithm:
options ALTQ options ALTQ_CBQ # Class Based Queuing (CBQ) options ALTQ_RED # Random Early Detection (RED) options ALTQ_RIO # RED In/Out options ALTQ_HFSC # Hierarchical Packet Scheduler (HFSC) options ALTQ_PRIQ # Priority Queuing (PRIQ)
The following scheduler algorithms are available:
Class Based Queuing (CBQ) is used to divide a connection's bandwidth into different classes or queues to prioritize traffic based on filter rules.
Random Early Detection (RED) is used to avoid network congestion by measuring the length of the queue and comparing it to the minimum and maximum thresholds for the queue. When the queue is over the maximum, all new packets are randomly dropped.
In Random Early Detection In and Out (RIO) mode, RED maintains multiple average queue lengths and multiple threshold values, one for each QOS level.
Hierarchical Fair Service Curve Packet Scheduler
(HFSC) is described in http://www-2.cs.cmu.edu/~hzhang/HFSC/main.html
.
Priority Queuing (PRIQ) always passes traffic that is in a higher queue first.
More information about the scheduling
algorithms and example rulesets are available at the OpenBSD's web archive
.
IPFW is a stateful firewall written for FreeBSD which supports both IPv4 and IPv6. It is comprised of several components: the kernel firewall filter rule processor and its integrated packet accounting facility, the logging facility, NAT, the dummynet(4) traffic shaper, a forward facility, a bridge facility, and an ipstealth facility.
FreeBSD provides a sample ruleset in
/etc/rc.firewall
which defines several
firewall types for common scenarios to assist novice users in
generating an appropriate ruleset.
IPFW provides a powerful syntax which
advanced users can use to craft customized rulesets that meet
the security requirements of a given environment.
This section describes how to enable IPFW, provides an overview of its rule syntax, and demonstrates several rulesets for common configuration scenarios.
IPFW is included in the basic FreeBSD install as a kernel loadable module, meaning that a custom kernel is not needed in order to enable IPFW.
For those users who wish to statically compile IPFW support into a custom kernel, see Section 30.4.6, “IPFW Kernel Options”.
To configure the system to enable
IPFW at boot time, add
firewall_enable="YES"
to
/etc/rc.conf
:
#
sysrc firewall_enable="YES"
To use one of the default firewall types provided by FreeBSD, add another line which specifies the type:
#
sysrc firewall_type="open"
The available types are:
open
: passes all traffic.
client
: protects only this
machine.
simple
: protects the whole
network.
closed
: entirely disables IP
traffic except for the loopback interface.
workstation
: protects only this
machine using stateful rules.
UNKNOWN
: disables the loading of
firewall rules.
:
full path of the file containing the firewall
ruleset.filename
If firewall_type
is set to either
client
or simple
,
modify the default rules found in
/etc/rc.firewall
to fit the
configuration of the system.
Note that the filename
type is used to
load a custom ruleset.
An alternate way to load a custom ruleset is to set the
firewall_script
variable to the absolute
path of an executable script that
includes IPFW commands. The
examples used in this section assume that the
firewall_script
is set to
/etc/ipfw.rules
:
#
sysrc firewall_script="/etc/ipfw.rules"
To enable logging through syslogd(8), include this line:
#
sysrc firewall_logging="YES"
Only firewall rules with the log
option will
be logged. The default rules do not include this option and it
must be manually added. Therefore it is advisable that the default
ruleset is edited for logging. In addition, log rotation may be
desired if the logs are stored in a separate file.
There is no /etc/rc.conf
variable to
set logging limits. To limit the number of times a rule is
logged per connection attempt, specify the number using this
line in /etc/sysctl.conf
:
#
echo "net.inet.ip.fw.verbose_limit=
5
" >> /etc/sysctl.conf
To enable logging through a dedicated interface named
ipfw0
, add this line to
/etc/rc.conf
instead:
#
sysrc firewall_logif="YES"
Then use tcpdump to see what is being logged:
#
tcpdump -t -n -i ipfw0
There is no overhead due to logging unless tcpdump is attached.
After saving the needed edits, start the firewall. To
enable logging limits now, also set the
sysctl
value specified above:
#
service ipfw start
#
sysctl net.inet.ip.fw.verbose_limit=
5
When a packet enters the IPFW
firewall, it is compared against the first rule in the ruleset
and progresses one rule at a time, moving from top to bottom
in sequence. When the packet matches the selection parameters
of a rule, the rule's action is executed and the search of the
ruleset terminates for that packet. This is referred to as
“first match wins”. If the packet does not match
any of the rules, it gets caught by the mandatory
IPFW default rule number 65535,
which denies all packets and silently discards them. However,
if the packet matches a rule that contains the
count
, skipto
, or
tee
keywords, the search continues. Refer
to ipfw(8) for details on how these keywords affect rule
processing.
When creating an
IPFW rule, keywords must be
written in the following order. Some keywords are mandatory
while other keywords are optional. The words shown in
uppercase represent a variable and the words shown in
lowercase must precede the variable that follows it. The
#
symbol is used to mark the start of a
comment and may appear at the end of a rule or on its own
line. Blank lines are ignored.
CMD RULE_NUMBER set SET_NUMBER ACTION log
LOG_AMOUNT PROTO from SRC SRC_PORT to DST DST_PORT
OPTIONS
This section provides an overview of these keywords and their options. It is not an exhaustive list of every possible option. Refer to ipfw(8) for a complete description of the rule syntax that can be used when creating IPFW rules.
Every rule must start with
ipfw add
.
Each rule is associated with a number from
1
to
65534
. The number is used to
indicate the order of rule processing. Multiple rules
can have the same number, in which case they are applied
according to the order in which they have been
added.
Each rule is associated with a set number from
0
to 31
.
Sets can be individually disabled or enabled, making it
possible to quickly add or delete a set of rules. If a
SET_NUMBER is not specified, the rule will be added to
set 0
.
A rule can be associated with one of the following actions. The specified action will be executed when the packet matches the selection criterion of the rule.
allow | accept | pass |
permit
: these keywords are equivalent and
allow packets that match the rule.
check-state
: checks the
packet against the dynamic state table. If a match is
found, execute the action associated with the rule which
generated this dynamic rule, otherwise move to the next
rule. A check-state
rule does not
have selection criterion. If no
check-state
rule is present in the
ruleset, the dynamic rules table is checked at the first
keep-state
or
limit
rule.
count
: updates counters for
all packets that match the rule. The search continues
with the next rule.
deny | drop
: either word
silently discards packets that match this rule.
Additional actions are available. Refer to ipfw(8) for details.
When a packet matches a rule with the
log
keyword, a message will be logged
to syslogd(8) with a facility name of
SECURITY
. Logging only occurs if the
number of packets logged for that particular rule does
not exceed a specified LOG_AMOUNT. If no
LOG_AMOUNT is specified, the limit is taken from the
value of
net.inet.ip.fw.verbose_limit
. A
value of zero removes the logging limit. Once the limit
is reached, logging can be re-enabled by clearing the
logging counter or the packet counter for that rule,
using ipfw resetlog
.
Logging is done after all other packet matching conditions have been met, and before performing the final action on the packet. The administrator decides which rules to enable logging on.
This optional value can be used to specify any
protocol name or number found in
/etc/protocols
.
The from
keyword must be followed
by the source address or a keyword that represents the
source address. An address can be represented by
any
, me
(any
address configured on an interface on this system),
me6
, (any IPv6
address configured on an interface on this system), or
table
followed by the number of a
lookup table which contains a list of addresses. When
specifying an IP address, it can be
optionally followed by its CIDR mask
or subnet mask. For example,
1.2.3.4/25
or
1.2.3.4:255.255.255.128
.
An optional source port can be specified using the
port number or name from
/etc/services
.
The to
keyword must be followed
by the destination address or a keyword that represents
the destination address. The same keywords and
addresses described in the SRC section can be used to
describe the destination.
An optional destination port can be specified using
the port number or name from
/etc/services
.
Several keywords can follow the source and
destination. As the name suggests, OPTIONS are
optional. Commonly used options include
in
or out
, which
specify the direction of packet flow,
icmptypes
followed by the type of
ICMP message, and
keep-state
.
When a keep-state
rule is
matched, the firewall will create a dynamic rule which
matches bidirectional traffic between the source and
destination addresses and ports using the same
protocol.
The dynamic rules facility is vulnerable to resource
depletion from a SYN-flood attack which would open a
huge number of dynamic rules. To counter this type of
attack with IPFW, use
limit
. This option limits the number
of simultaneous sessions by checking the open dynamic
rules, counting the number of times this rule and
IP address combination occurred. If
this count is greater than the value specified by
limit
, the packet is
discarded.
Dozens of OPTIONS are available. Refer to ipfw(8) for a description of each available option.
This section demonstrates how to create an example
stateful firewall ruleset script named
/etc/ipfw.rules
. In this example, all
connection rules use in
or
out
to clarify the direction. They also
use via
interface-name
to specify
the interface the packet is traveling over.
When first creating or testing a firewall ruleset, consider temporarily setting this tunable:
net.inet.ip.fw.default_to_accept="1"
This sets the default policy of ipfw(8) to be more
permissive than the default deny ip from any to
any
, making it slightly more difficult to get
locked out of the system right after a reboot.
The firewall script begins by indicating that it is a
Bourne shell script and flushes any existing rules. It then
creates the cmd
variable so that
ipfw add
does not have to be typed at the
beginning of every rule. It also defines the
pif
variable which represents the name of
the interface that is attached to the Internet.
#!/bin/sh # Flush out the list before we begin. ipfw -q -f flush # Set rules command prefix cmd="ipfw -q add" pif="dc0" # interface name of NIC attached to Internet
The first two rules allow all traffic on the trusted internal interface and on the loopback interface:
# Change xl0 to LAN NIC interface name $cmd 00005 allow all from any to any via xl0 # No restrictions on Loopback Interface $cmd 00010 allow all from any to any via lo0
The next rule allows the packet through if it matches an existing entry in the dynamic rules table:
$cmd 00101 check-state
The next set of rules defines which stateful connections internal systems can create to hosts on the Internet:
# Allow access to public DNS # Replace x.x.x.x with the IP address of a public DNS server # and repeat for each DNS server in /etc/resolv.conf $cmd 00110 allow tcp from any to x.x.x.x 53 out via $pif setup keep-state $cmd 00111 allow udp from any to x.x.x.x 53 out via $pif keep-state # Allow access to ISP's DHCP server for cable/DSL configurations. # Use the first rule and check log for IP address. # Then, uncomment the second rule, input the IP address, and delete the first rule $cmd 00120 allow log udp from any to any 67 out via $pif keep-state #$cmd 00120 allow udp from any to x.x.x.x 67 out via $pif keep-state # Allow outbound HTTP and HTTPS connections $cmd 00200 allow tcp from any to any 80 out via $pif setup keep-state $cmd 00220 allow tcp from any to any 443 out via $pif setup keep-state # Allow outbound email connections $cmd 00230 allow tcp from any to any 25 out via $pif setup keep-state $cmd 00231 allow tcp from any to any 110 out via $pif setup keep-state # Allow outbound ping $cmd 00250 allow icmp from any to any out via $pif keep-state # Allow outbound NTP $cmd 00260 allow udp from any to any 123 out via $pif keep-state # Allow outbound SSH $cmd 00280 allow tcp from any to any 22 out via $pif setup keep-state # deny and log all other outbound connections $cmd 00299 deny log all from any to any out via $pif
The next set of rules controls connections from Internet
hosts to the internal network. It starts by denying packets
typically associated with attacks and then explicitly allows
specific types of connections. All the authorized services
that originate from the Internet use limit
to prevent flooding.
# Deny all inbound traffic from non-routable reserved address spaces $cmd 00300 deny all from 192.168.0.0/16 to any in via $pif #RFC 1918 private IP $cmd 00301 deny all from 172.16.0.0/12 to any in via $pif #RFC 1918 private IP $cmd 00302 deny all from 10.0.0.0/8 to any in via $pif #RFC 1918 private IP $cmd 00303 deny all from 127.0.0.0/8 to any in via $pif #loopback $cmd 00304 deny all from 0.0.0.0/8 to any in via $pif #loopback $cmd 00305 deny all from 169.254.0.0/16 to any in via $pif #DHCP auto-config $cmd 00306 deny all from 192.0.2.0/24 to any in via $pif #reserved for docs $cmd 00307 deny all from 204.152.64.0/23 to any in via $pif #Sun cluster interconnect $cmd 00308 deny all from 224.0.0.0/3 to any in via $pif #Class D & E multicast # Deny public pings $cmd 00310 deny icmp from any to any in via $pif # Deny ident $cmd 00315 deny tcp from any to any 113 in via $pif # Deny all Netbios services. $cmd 00320 deny tcp from any to any 137 in via $pif $cmd 00321 deny tcp from any to any 138 in via $pif $cmd 00322 deny tcp from any to any 139 in via $pif $cmd 00323 deny tcp from any to any 81 in via $pif # Deny fragments $cmd 00330 deny all from any to any frag in via $pif # Deny ACK packets that did not match the dynamic rule table $cmd 00332 deny tcp from any to any established in via $pif # Allow traffic from ISP's DHCP server. # Replace x.x.x.x with the same IP address used in rule 00120. #$cmd 00360 allow udp from any to x.x.x.x 67 in via $pif keep-state # Allow HTTP connections to internal web server $cmd 00400 allow tcp from any to me 80 in via $pif setup limit src-addr 2 # Allow inbound SSH connections $cmd 00410 allow tcp from any to me 22 in via $pif setup limit src-addr 2 # Reject and log all other incoming connections $cmd 00499 deny log all from any to any in via $pif
The last rule logs all packets that do not match any of the rules in the ruleset:
# Everything else is denied and logged $cmd 00999 deny log all from any to any
FreeBSD's IPFW firewall has two implementations of NAT: one being the userland natd(8) daemon, and the more recent IPFW's built-in NAT facility also known as in-kernel NAT. Both work in conjunction with IPFW to provide network address translation. This can be used to provide an Internet Connection Sharing solution so that several internal computers can connect to the Internet using a single public IP address.
To do this, the FreeBSD machine connected to the Internet must act as a gateway. This system must have two NICs, where one is connected to the Internet and the other is connected to the internal LAN. Each machine connected to the LAN should be assigned an IP address in the private network space, as defined by RFC 1918.
Some additional configuration is needed in order to enable
the in-kernel NAT function of
IPFW. To enable in-kernel
NAT support at boot time, the following
must be set in /etc/rc.conf
:
gateway_enable="YES" firewall_enable="YES" firewall_nat_enable="YES"
When firewall_enable
is not set,
but firewall_nat_enable
is, it will have
no effect and do nothing, because the in-kernel
NAT implementation is only compatible
with IPFW.
When the ruleset contains stateful rules, the positioning
of the NAT rule is critical and the
skipto
action is used. The
skipto
action requires a rule number so
that it knows which rule to jump to. Furthermore, because
of the architecture of libalias(3), a library implemented
as a kernel module used for the in-kernel
NAT facility of
IPFW, it is necessary to disable
TCP segmentation offloading, or in short
TSO. TSO can be
disabled on a per network interface basis by using
ifconfig(8) or on a system wide basis using
sysctl(8). To disable TSO system
wide, the following must be set in
/etc/sysctl.conf
:
net.inet.tcp.tso="0"
The example below builds upon the firewall ruleset
shown in the previous section. It adds some additional
entries and modifies some existing rules in order to configure
the firewall for in-kernel NAT. It starts
by adding some additional variables which represent the rule
number to skip to, the keep-state
option,
and a list of TCP ports which will be used
to reduce the number of rules.
#!/bin/sh ipfw -q -f flush cmd="ipfw -q add" skip="skipto 1000" pif=dc0 ks="keep-state" good_tcpo="22,25,37,53,80,443,110"
A NAT instance will also be
configured. With in-kernel NAT it is
possible to have multiple NAT instances
each with their own configuration. Although, for this example
only one NAT instance is needed;
NAT instance number 1. The configuration
takes a few arguments and flags such as: if
which indicates the public interface,
same_ports
which takes care that alliased
ports and local port numbers are mapped the same,
unreg_only
will result in only unregistered
(private) address spaces to be processed by the
NAT instance, and reset
which will help to keep a functioning NAT
instance even when the public IP address of
the IPFW machine changes. For all
possible options that can be passed to a single
NAT instance configuration consult
ipfw(8). Furthermore, because of the nature of a
stateful NATing firewall, it is neseccary
to allow translated packets to be reinjected in the firewall
for further processing, this can be achieved by disabling
one_pass
behavior at the start of the
firewall script.
ipfw disable one_pass ipfw -q nat 1 config if $pif same_ports unreg_only reset
The inbound NAT rule is inserted
after the two rules which allow all
traffic on the trusted and loopback interfaces and after the
reassamble rule but before the
check-state
rule. It is important that the
rule number selected for this NAT rule, in
this example 100
, is higher than the first
three rules and lower than the check-state
rule. Furthermore, because of the behavior of in-kernel
NAT it is advised to place a reassamble
rule just before the first NAT rule and
after the rules that allow traffic on trusted interface.
Normally, IP fragmentation should not
happen, but when dealing with IPSEC/ESP/GRE
tunneling traffic it might and the reassmabling of fragments
is necessary before handing the complete packet over to the
in-kernel NAT engine.
The reassemble rule was not needed with userland
natd(8) because the internal workings of the
IPFW divert
action already takes care of this automatically as also
stated in ipfw(8).
The current NAT instance number and
NAT rule number does not match with the
default NAT instance number and rule
number created by rc.firewall
which is
a script to set up the baked-in default firewall rulesets
present in FreeBSD.
$cmd 005 allow all from any to any via xl0 # exclude LAN traffic $cmd 010 allow all from any to any via lo0 # exclude loopback traffic $cmd 099 reass all from any to any in # reassamble inbound packets $cmd 100 nat 1 ip from any to any in via $pif # NAT any inbound packets # Allow the packet through if it has an existing entry in the dynamic rules table $cmd 101 check-state
The outbound rules are modified to replace the
allow
action with the
$skip
variable, indicating that rule
processing will continue at rule 1000
. The
seven tcp
rules have been replaced by rule
125
as the
$good_tcpo
variable contains the
seven allowed outbound ports.
Remember that IPFW's firewall performance is largely determined by the number of rules present in the ruleset.
# Authorized outbound packets $cmd 120 $skip udp from any to x.x.x.x 53 out via $pif $ks $cmd 121 $skip udp from any to x.x.x.x 67 out via $pif $ks $cmd 125 $skip tcp from any to any $good_tcpo out via $pif setup $ks $cmd 130 $skip icmp from any to any out via $pif $ks
The inbound rules remain the same, except for the very
last rule which removes the via $pif
in
order to catch both inbound and outbound rules. The
NAT rule must follow this last outbound
rule, must have a higher number than that last rule, and the
rule number must be referenced by the
skipto
action. In this ruleset, rule
number 1000
handles passing all packets to
our configured instance for NAT processing.
The next rule allows any packet which has undergone
NAT processing to pass.
$cmd 999 deny log all from any to any $cmd 1000 nat 1 ip from any to any out via $pif # skipto location for outbound stateful rules $cmd 1001 allow ip from any to any
In this example, rules 100
,
101
, 125
,
1000
, and 1001
control
the address translation of the outbound and inbound packets so
that the entries in the dynamic state table always register
the private LAN IP
address.
Consider an internal web browser which initializes a new
outbound HTTP session over port 80. When
the first outbound packet enters the firewall, it does not
match rule 100
because it is headed out
rather than in. It passes rule 101
because
this is the first packet and it has not been posted to the
dynamic state table yet. The packet finally matches rule
125
as it is outbound on an allowed port
and has a source IP address from the
internal LAN. On matching this rule, two
actions take place. First, the keep-state
action adds an entry to the dynamic state table and the
specified action, skipto rule 1000
, is
executed. Next, the packet undergoes NAT
and is sent out to the Internet. This packet makes its way to
the destination web server, where a response packet is
generated and sent back. This new packet enters the top of
the ruleset. It matches rule 100
and has
its destination IP address mapped back to
the original internal address. It then is processed by the
check-state
rule, is found in the table as
an existing session, and is released to the
LAN.
On the inbound side, the ruleset has to deny bad packets
and allow only authorized services. A packet which matches an
inbound rule is posted to the dynamic state table and the
packet is released to the LAN. The packet
generated as a response is recognized by the
check-state
rule as belonging to an
existing session. It is then sent to rule
1000
to undergo
NAT before being released to the outbound
interface.
Transition from userland natd(8) to in-kernel
NAT might seem seamless at first but
there is small catch. When using the GENERIC kernel,
IPFW will load the
libalias.ko
kernel module, when firewall_nat_enable
is enabled in rc.conf
. Although, the
loaded module only provides basic NAT
functionality, whereas the userland implementation
natd(8) has all functionality available without any
extra configuration from its userland library. All
functionality refers to the following kernel modules that
can additionally be loaded when needed besides the standard
libalias.ko
kernel module:
alias_cuseeme.ko
,
alias_ftp.ko
,
alias_bbt.ko
,
skinny.ko
, irc.ko
,
alias_pptp.ko
and
alias_smedia.ko
using the
kld_list
directive in
rc.conf
to mimic the full functionality
of the userland implementation. If a custom kernel is used,
the full functionality of the userland library can be
compiled in, in the kernel, using the option
LIBALIAS
.
The drawback with NAT in general is that the LAN clients are not accessible from the Internet. Clients on the LAN can make outgoing connections to the world but cannot receive incoming ones. This presents a problem if trying to run Internet services on one of the LAN client machines. A simple way around this is to redirect selected Internet ports on the NAT providing machine to a LAN client.
For example, an IRC server runs on
client A
and a web server runs on
client B
. For this to work
properly, connections received on ports 6667
(IRC) and 80 (HTTP)
must be redirected to the respective machines.
With in-kernel NAT all configuration
is done in the NAT instance
configuration. For a full list of options that an in-kernel
NAT instance can use, consult
ipfw(8). The IPFW syntax
follows the syntax of natd. The
syntax for redirect_port
is as
follows:
redirect_port proto targetIP:targetPORT[-targetPORT] [aliasIP:]aliasPORT[-aliasPORT] [remoteIP[:remotePORT[-remotePORT]]]
To configure the above example setup, the arguments should be:
redirect_port tcp 192.168.0.2:6667 6667 redirect_port tcp 192.168.0.3:80 80
After adding these arguments to the configuration of NAT instance 1 in the above ruleset, the TCP ports will be port forwarded to the LAN client machines running the IRC and HTTP services.
ipfw -q nat 1 config if $pif same_ports unreg_only reset \ redirect_port tcp 192.168.0.2:6667 6667 \ redirect_port tcp 192.1683.0.3:80 80
Port ranges over individual ports can be indicated with
redirect_port
. For example,
tcp 192.168.0.2:2000-3000
2000-3000
would redirect all connections
received on ports 2000 to 3000 to ports 2000 to 3000 on
client A
.
Address redirection is useful if more than one
IP address is available. Each
LAN client can be assigned its own
external IP address by ipfw(8),
which will then rewrite outgoing packets from the
LAN clients with the proper external
IP address and redirects all traffic
incoming on that particular IP address
back to the specific LAN client. This is
also known as static NAT. For example,
if IP addresses 128.1.1.1
, 128.1.1.2
, and 128.1.1.3
are available,
128.1.1.1
can be
used as the ipfw(8) machine's external
IP address, while 128.1.1.2
and 128.1.1.3
are forwarded
back to LAN clients
A
and
B
.
The redirect_address
syntax is as
below, where localIP
is the internal
IP address of the LAN
client, and publicIP
the external
IP address corresponding to the
LAN client.
redirect_address localIP publicIP
In the example, the arguments would read:
redirect_address 192.168.0.2 128.1.1.2 redirect_address 192.168.0.3 128.1.1.3
Like redirect_port
, these arguments
are placed in a NAT instance
configuration. With address redirection, there is no
need for port redirection, as all data received on a
particular IP address is
redirected.
The external IP addresses on the ipfw(8) machine must be active and aliased to the external interface. Refer to rc.conf(5) for details.
Let us start with a statement: the userspace NAT implementation: natd(8), has more overhead than in-kernel NAT. For natd(8) to translate packets, the packets have to be copied from the kernel to userspace and back which brings in extra overhead that is not present with in-kernel NAT.
To enable the userpace NAT daemon
natd(8) at boot time, the following is a minimum
configuration in /etc/rc.conf
. Where
natd_interface
is set to the name of the
NIC attached to the Internet. The
rc(8) script of natd(8) will automatically check
if a dynamic IP address is used and
configure itself to handle that.
gateway_enable="YES" natd_enable="YES" natd_interface="rl0"
In general, the above ruleset as explained for in-kernel
NAT can also be used together with
natd(8). The only exceptions are the configuration of
the in-kernel NAT instance (ipfw
-q nat 1 config ...)
not being applicable any
more, rule number 100 and 1000 will have to change sligthly
as below, and reassemble rule 99 is not needed anymore
as the divert
action is used which covers
fragmentation.
$cmd 100 divert natd ip from any to any in via $pif $cmd 1000 divert natd ip from any to any out via $pif
To configure port or address redirection, a similar
syntax as with in-kernel NAT is used.
Although, now, instead of specifying the configuration in
our ruleset script like with in-kernel
NAT, configuration of natd(8) is
best done in a configuration file. To do this, an extra
flag must be passed via /etc/rc.conf
which specifies the path of the configuration file.
natd_flags="-f /etc/natd.conf"
The specified file must contain a list of configuration options, one per line. For more information about the configuration file and possible variables, consult natd(8). Below are two example entries, one per line:
redirect_port tcp 192.168.0.2:6667 6667 redirect_address 192.168.0.3 128.1.1.3
ipfw
can be used to make manual,
single rule additions or deletions to the active firewall
while it is running. The problem with using this method is
that all the changes are lost when the system reboots. It is
recommended to instead write all the rules in a file and to
use that file to load the rules at boot time and to replace
the currently running firewall rules whenever that file
changes.
ipfw
is a useful way to display the
running firewall rules to the console screen. The
IPFW accounting facility
dynamically creates a counter for each rule that counts each
packet that matches the rule. During the process of testing a
rule, listing the rule with its counter is one way to
determine if the rule is functioning as expected.
To list all the running rules in sequence:
#
ipfw list
To list all the running rules with a time stamp of when the last time the rule was matched:
#
ipfw -t list
The next example lists accounting information and the packet count for matched rules along with the rules themselves. The first column is the rule number, followed by the number of matched packets and bytes, followed by the rule itself.
#
ipfw -a list
To list dynamic rules in addition to static rules:
#
ipfw -d list
To also show the expired dynamic rules:
#
ipfw -d -e list
To zero the counters:
#
ipfw zero
To zero the counters for just the rule with number
NUM
:
#
ipfw zero
NUM
Even with the logging facility enabled,
IPFW will not generate any rule
logging on its own. The firewall administrator decides
which rules in the ruleset will be logged, and adds the
log
keyword to those rules. Normally
only deny rules are logged. It is customary to duplicate
the “ipfw default deny everything” rule with
the log
keyword included as the last rule
in the ruleset. This way, it is possible to see all the
packets that did not match any of the rules in the
ruleset.
Logging is a two edged sword. If one is not careful, an over abundance of log data or a DoS attack can fill the disk with log files. Log messages are not only written to syslogd, but also are displayed on the root console screen and soon become annoying.
The IPFIREWALL_VERBOSE_LIMIT=5
kernel option limits the number of consecutive messages
sent to syslogd(8), concerning the packet matching of a
given rule. When this option is enabled in the kernel, the
number of consecutive messages concerning a particular rule
is capped at the number specified. There is nothing to be
gained from 200 identical log messages. With this option
set to five,
five consecutive messages concerning a particular rule
would be logged to syslogd and
the remainder identical consecutive messages would be
counted and posted to syslogd
with a phrase like the following:
last message repeated 45 times
All logged packets messages are written by default to
/var/log/security
, which is
defined in /etc/syslog.conf
.
Most experienced IPFW users create a file containing the rules and code them in a manner compatible with running them as a script. The major benefit of doing this is the firewall rules can be refreshed in mass without the need of rebooting the system to activate them. This method is convenient in testing new rules as the procedure can be executed as many times as needed. Being a script, symbolic substitution can be used for frequently used values to be substituted into multiple rules.
This example script is compatible with the syntax used by the sh(1), csh(1), and tcsh(1) shells. Symbolic substitution fields are prefixed with a dollar sign ($). Symbolic fields do not have the $ prefix. The value to populate the symbolic field must be enclosed in double quotes ("").
Start the rules file like this:
############### start of example ipfw rules script ############# # ipfw -q -f flush # Delete all rules # Set defaults oif="tun0" # out interface odns="192.0.2.11" # ISP's DNS server IP address cmd="ipfw -q add " # build rule prefix ks="keep-state" # just too lazy to key this each time $cmd 00500 check-state $cmd 00502 deny all from any to any frag $cmd 00501 deny tcp from any to any established $cmd 00600 allow tcp from any to any 80 out via $oif setup $ks $cmd 00610 allow tcp from any to $odns 53 out via $oif setup $ks $cmd 00611 allow udp from any to $odns 53 out via $oif $ks ################### End of example ipfw rules script ############
The rules are not important as the focus of this example is how the symbolic substitution fields are populated.
If the above example was in
/etc/ipfw.rules
, the rules could be
reloaded by the following command:
#
sh /etc/ipfw.rules
/etc/ipfw.rules
can be located
anywhere and the file can have any name.
The same thing could be accomplished by running these commands by hand:
#
ipfw -q -f flush
#
ipfw -q add check-state
#
ipfw -q add deny all from any to any frag
#
ipfw -q add deny tcp from any to any established
#
ipfw -q add allow tcp from any to any 80 out via tun0 setup keep-state
#
ipfw -q add allow tcp from any to 192.0.2.11 53 out via tun0 setup keep-state
#
ipfw -q add 00611 allow udp from any to 192.0.2.11 53 out via tun0 keep-state
In order to statically compile IPFW support into a custom kernel, refer to the instructions in Chapter 8, Configuring the FreeBSD Kernel. The following options are available for the custom kernel configuration file:
options IPFIREWALL # enables IPFW options IPFIREWALL_VERBOSE # enables logging for rules with log keyword to syslogd(8) options IPFIREWALL_VERBOSE_LIMIT=5 # limits number of logged packets per-entry options IPFIREWALL_DEFAULT_TO_ACCEPT # sets default policy to pass what is not explicitly denied options IPFIREWALL_NAT # enables in-kernel NAT support options IPFIREWALL_NAT64 # enables in-kernel NAT64 support options IPFIREWALL_NPTV6 # enables in-kernel IPv6 NPT support options IPFIREWALL_PMOD # enables protocols modification module support options IPDIVERT # enables NAT through natd(8)
IPFW can be loaded as a kernel module: options above are built by default as modules or can be set at runtime using tunables.
IPFILTER, also known as IPF, is a cross-platform, open source firewall which has been ported to several operating systems, including FreeBSD, NetBSD, OpenBSD, and Solaris™.
IPFILTER is a kernel-side firewall and NAT mechanism that can be controlled and monitored by userland programs. Firewall rules can be set or deleted using ipf, NAT rules can be set or deleted using ipnat, run-time statistics for the kernel parts of IPFILTER can be printed using ipfstat, and ipmon can be used to log IPFILTER actions to the system log files.
IPF was originally written using
a rule processing logic of “the last matching rule
wins” and only used stateless rules. Since then,
IPF has been enhanced to include the
quick
and keep state
options.
The IPF FAQ is at http://www.phildev.net/ipf/index.html
.
A searchable archive of the IPFilter mailing list is available
at http://marc.info/?l=ipfilter
.
This section of the Handbook focuses on
IPF as it pertains to FreeBSD. It
provides examples of rules that contain the
quick
and keep state
options.
IPF is included in the basic FreeBSD install as a kernel loadable module, meaning that a custom kernel is not needed in order to enable IPF.
For users who prefer to statically compile IPF support into a custom kernel, refer to the instructions in Chapter 8, Configuring the FreeBSD Kernel. The following kernel options are available:
options IPFILTER options IPFILTER_LOG options IPFILTER_LOOKUP options IPFILTER_DEFAULT_BLOCK
where options IPFILTER
enables support
for IPFILTER,
options IPFILTER_LOG
enables
IPF logging using the
ipl
packet logging pseudo-device for
every rule that has the log
keyword,
IPFILTER_LOOKUP
enables
IP pools in order to speed up
IP lookups, and options
IPFILTER_DEFAULT_BLOCK
changes the default
behavior so that any packet not matching a firewall
pass
rule gets blocked.
To configure the system to enable
IPF at boot time, add the following
entries to /etc/rc.conf
. These entries
will also enable logging and default pass
all
. To change the default policy to
block all
without compiling a custom
kernel, remember to add a block all
rule at
the end of the ruleset.
ipfilter_enable="YES" # Start ipf firewall ipfilter_rules="/etc/ipf.rules" # loads rules definition text file ipmon_enable="YES" # Start IP monitor log ipmon_flags="-Ds" # D = start as daemon # s = log to syslog # v = log tcp window, ack, seq # n = map IP & port to names
If NAT functionality is needed, also add these lines:
gateway_enable="YES" # Enable as LAN gateway ipnat_enable="YES" # Start ipnat function ipnat_rules="/etc/ipnat.rules" # rules definition file for ipnat
Then, to start IPF now:
#
service ipfilter start
To load the firewall rules, specify the name of the
ruleset file using ipf
. The following
command can be used to replace the currently running firewall
rules:
#
ipf -Fa -f /etc/ipf.rules
where -Fa
flushes all the internal rules
tables and -f
specifies the file containing
the rules to load.
This provides the ability to make changes to a custom ruleset and update the running firewall with a fresh copy of the rules without having to reboot the system. This method is convenient for testing new rules as the procedure can be executed as many times as needed.
Refer to ipf(8) for details on the other flags available with this command.
This section describes the IPF
rule syntax used to create stateful rules. When creating
rules, keep in mind that unless the quick
keyword appears in a rule, every rule is read in order, with
the last matching rule being the one
that is applied. This means that even if the first rule to
match a packet is a pass
, if there is a
later matching rule that is a block
, the
packet will be dropped. Sample rulesets can be found in
/usr/share/examples/ipfilter
.
When creating rules, a #
character is
used to mark the start of a comment and may appear at the end
of a rule, to explain that rule's function, or on its own
line. Any blank lines are ignored.
The keywords which are used in rules must be written in a specific order, from left to right. Some keywords are mandatory while others are optional. Some keywords have sub-options which may be keywords themselves and also include more sub-options. The keyword order is as follows, where the words shown in uppercase represent a variable and the words shown in lowercase must precede the variable that follows it:
ACTION DIRECTION OPTIONS proto PROTO_TYPE
from SRC_ADDR SRC_PORT to DST_ADDR DST_PORT
TCP_FLAG|ICMP_TYPE keep state STATE
This section describes each of these keywords and their options. It is not an exhaustive list of every possible option. Refer to ipf(5) for a complete description of the rule syntax that can be used when creating IPF rules and examples for using each keyword.
The action keyword indicates what to do with the packet if it matches that rule. Every rule must have an action. The following actions are recognized:
block
: drops the packet.
pass
: allows the packet.
log
: generates a log
record.
count
: counts the number of
packets and bytes which can provide an indication of
how often a rule is used.
auth
: queues the packet for
further processing by another program.
call
: provides access to
functions built into IPF that
allow more complex actions.
decapsulate
: removes any headers
in order to process the contents of the packet.
Next, each rule must explicitly state the direction of traffic using one of these keywords:
in
: the rule is applied against
an inbound packet.
out
: the rule is applied against
an outbound packet.
all
: the rule applies to either
direction.
If the system has multiple interfaces, the interface
can be specified along with the direction. An example
would be in on fxp0
.
Options are optional. However, if multiple options are specified, they must be used in the order shown here.
log
: when performing the
specified ACTION, the contents of the packet's headers
will be written to the ipl(4) packet log
pseudo-device.
quick
: if a packet matches this
rule, the ACTION specified by the rule occurs and no
further processing of any following rules will occur for
this packet.
on
: must be followed by the
interface name as displayed by ifconfig(8). The
rule will only match if the packet is going through the
specified interface in the specified direction.
When using the
log
keyword, the following qualifiers
may be used in this order:
body
: indicates that the first
128 bytes of the packet contents will be logged after
the headers.
first
: if the
log
keyword is being used in
conjunction with a keep state
option,
this option is recommended so that only the triggering
packet is logged and not every packet which matches the
stateful connection.
Additional options are available to specify error return messages. Refer to ipf(5) for more details.
The protocol type is optional. However, it is
mandatory if the rule needs to specify a SRC_PORT or
a DST_PORT as it defines the type of protocol. When
specifying the type of protocol, use the
proto
keyword followed by either a
protocol number or name from
/etc/protocols
.
Example protocol names include tcp
,
udp
, or icmp
. If
PROTO_TYPE is specified but no SRC_PORT or DST_PORT is
specified, all port numbers for that protocol will match
that rule.
The from
keyword is mandatory and
is followed by a keyword which represents the source of
the packet. The source can be a hostname, an
IP address followed by the
CIDR mask, an address pool, or the
keyword all
. Refer to ipf(5)
for examples.
There is no way to match ranges of
IP addresses which do not express
themselves easily using the dotted numeric form /
mask-length notation. The
net-mgmt/ipcalc package or port may
be used to ease the calculation of the
CIDR mask. Additional information is
available at the utility's web page: http://jodies.de/ipcalc
.
The port number of the source is optional. However,
if it is used, it requires PROTO_TYPE to be first
defined in the rule. The port number must also be
preceded by the proto
keyword.
A number of different comparison operators are
supported: =
(equal to),
!=
(not equal to),
<
(less than),
>
(greater than),
<=
(less than or equal to), and
>=
(greater than or equal
to).
To specify port ranges, place the two port numbers
between <>
(less than and
greater than ), ><
(greater
than and less than ), or :
(greater
than or equal to and less than or equal to).
The to
keyword is mandatory and
is followed by a keyword which represents the
destination of the packet. Similar to SRC_ADDR, it can
be a hostname, an IP address
followed by the CIDR mask, an address
pool, or the keyword all
.
Similar to SRC_PORT, the port number of the
destination is optional. However, if it is used, it
requires PROTO_TYPE to be first defined in the rule.
The port number must also be preceded by the
proto
keyword.
If tcp
is specified as the
PROTO_TYPE, flags can be specified as letters, where
each letter represents one of the possible
TCP flags used to determine the state
of a connection. Possible values are:
S
(SYN),
A
(ACK),
P
(PSH),
F
(FIN),
U
(URG),
R
(RST),
C
(CWN), and
E
(ECN).
If icmp
is specified as the
PROTO_TYPE, the ICMP type to match
can be specified. Refer to ipf(5) for the
allowable types.
If a pass
rule contains
keep state
,
IPF will add an entry to its
dynamic state table and allow subsequent packets that
match the connection.
IPF can track state for
TCP, UDP, and
ICMP sessions. Any packet that
IPF can be certain is part of
an active session, even if it is a different protocol,
will be allowed.
In IPF, packets destined to go out through the interface connected to the public Internet are first checked against the dynamic state table. If the packet matches the next expected packet comprising an active session conversation, it exits the firewall and the state of the session conversation flow is updated in the dynamic state table. Packets that do not belong to an already active session are checked against the outbound ruleset. Packets coming in from the interface connected to the public Internet are first checked against the dynamic state table. If the packet matches the next expected packet comprising an active session, it exits the firewall and the state of the session conversation flow is updated in the dynamic state table. Packets that do not belong to an already active session are checked against the inbound ruleset.
Several keywords can be added after
keep state
. If used, these keywords
set various options that control stateful filtering,
such as setting connection limits or connection age.
Refer to ipf(5) for the list of available options
and their descriptions.
This section demonstrates how to create an example ruleset
which only allows services matching
pass
rules and blocks all others.
FreeBSD uses the loopback interface
(lo0
) and the IP
address 127.0.0.1
for internal communication. The firewall ruleset must contain
rules to allow free movement of these internally used
packets:
# no restrictions on loopback interface pass in quick on lo0 all pass out quick on lo0 all
The public interface connected to the Internet is used to authorize and control access of all outbound and inbound connections. If one or more interfaces are cabled to private networks, those internal interfaces may require rules to allow packets originating from the LAN to flow between the internal networks or to the interface attached to the Internet. The ruleset should be organized into three major sections: any trusted internal interfaces, outbound connections through the public interface, and inbound connections through the public interface.
These two rules allow all traffic to pass through a
trusted LAN interface named
xl0
:
# no restrictions on inside LAN interface for private network pass out quick on xl0 all pass in quick on xl0 all
The rules for the public interface's outbound and inbound sections should have the most frequently matched rules placed before less commonly matched rules, with the last rule in the section blocking and logging all packets for that interface and direction.
This set of rules defines the outbound section of the
public interface named dc0
. These rules
keep state and identify the specific services that internal
systems are authorized for public Internet access. All the
rules use quick
and specify the
appropriate port numbers and, where applicable, destination
addresses.
# interface facing Internet (outbound) # Matches session start requests originating from or behind the # firewall, destined for the Internet. # Allow outbound access to public DNS servers. # Replace x.x.x. with address listed in /etc/resolv.conf. # Repeat for each DNS server. pass out quick on dc0 proto tcp from any to x.x.x. port = 53 flags S keep state pass out quick on dc0 proto udp from any to xxx port = 53 keep state # Allow access to ISP's specified DHCP server for cable or DSL networks. # Use the first rule, then check log for the IP address of DHCP server. # Then, uncomment the second rule, replace z.z.z.z with the IP address, # and comment out the first rule pass out log quick on dc0 proto udp from any to any port = 67 keep state #pass out quick on dc0 proto udp from any to z.z.z.z port = 67 keep state # Allow HTTP and HTTPS pass out quick on dc0 proto tcp from any to any port = 80 flags S keep state pass out quick on dc0 proto tcp from any to any port = 443 flags S keep state # Allow email pass out quick on dc0 proto tcp from any to any port = 110 flags S keep state pass out quick on dc0 proto tcp from any to any port = 25 flags S keep state # Allow NTP pass out quick on dc0 proto tcp from any to any port = 37 flags S keep state # Allow FTP pass out quick on dc0 proto tcp from any to any port = 21 flags S keep state # Allow SSH pass out quick on dc0 proto tcp from any to any port = 22 flags S keep state # Allow ping pass out quick on dc0 proto icmp from any to any icmp-type 8 keep state # Block and log everything else block out log first quick on dc0 all
This example of the rules in the inbound section of the public interface blocks all undesirable packets first. This reduces the number of packets that are logged by the last rule.
# interface facing Internet (inbound) # Block all inbound traffic from non-routable or reserved address spaces block in quick on dc0 from 192.168.0.0/16 to any #RFC 1918 private IP block in quick on dc0 from 172.16.0.0/12 to any #RFC 1918 private IP block in quick on dc0 from 10.0.0.0/8 to any #RFC 1918 private IP block in quick on dc0 from 127.0.0.0/8 to any #loopback block in quick on dc0 from 0.0.0.0/8 to any #loopback block in quick on dc0 from 169.254.0.0/16 to any #DHCP auto-config block in quick on dc0 from 192.0.2.0/24 to any #reserved for docs block in quick on dc0 from 204.152.64.0/23 to any #Sun cluster interconnect block in quick on dc0 from 224.0.0.0/3 to any #Class D & E multicast # Block fragments and too short tcp packets block in quick on dc0 all with frags block in quick on dc0 proto tcp all with short # block source routed packets block in quick on dc0 all with opt lsrr block in quick on dc0 all with opt ssrr # Block OS fingerprint attempts and log first occurrence block in log first quick on dc0 proto tcp from any to any flags FUP # Block anything with special options block in quick on dc0 all with ipopts # Block public pings and ident block in quick on dc0 proto icmp all icmp-type 8 block in quick on dc0 proto tcp from any to any port = 113 # Block incoming Netbios services block in log first quick on dc0 proto tcp/udp from any to any port = 137 block in log first quick on dc0 proto tcp/udp from any to any port = 138 block in log first quick on dc0 proto tcp/udp from any to any port = 139 block in log first quick on dc0 proto tcp/udp from any to any port = 81
Any time there are logged messages on a rule with
the log first
option, run
ipfstat -hio
to evaluate how many times the
rule has been matched. A large number of matches may indicate
that the system is under attack.
The rest of the rules in the inbound section define which connections are allowed to be initiated from the Internet. The last rule denies all connections which were not explicitly allowed by previous rules in this section.
# Allow traffic in from ISP's DHCP server. Replace z.z.z.z with # the same IP address used in the outbound section. pass in quick on dc0 proto udp from z.z.z.z to any port = 68 keep state # Allow public connections to specified internal web server pass in quick on dc0 proto tcp from any to x.x.x.x port = 80 flags S keep state # Block and log only first occurrence of all remaining traffic. block in log first quick on dc0 all
To enable NAT, add these statements
to /etc/rc.conf
and specify the name of
the file containing the NAT rules:
gateway_enable="YES" ipnat_enable="YES" ipnat_rules="/etc/ipnat.rules"
NAT rules are flexible and can accomplish many different things to fit the needs of both commercial and home users. The rule syntax presented here has been simplified to demonstrate common usage. For a complete rule syntax description, refer to ipnat(5).
The basic syntax for a NAT rule is as
follows, where map
starts the rule and
IF
should be replaced with the
name of the external interface:
mapIF
LAN_IP_RANGE
->PUBLIC_ADDRESS
The LAN_IP_RANGE
is the range
of IP addresses used by internal clients.
Usually, it is a private address range such as 192.168.1.0/24
. The
PUBLIC_ADDRESS
can either be the
static external IP address or the keyword
0/32
which represents the
IP address assigned to
IF
.
In IPF, when a packet arrives
at the firewall from the LAN with a public
destination, it first passes through the outbound rules of the
firewall ruleset. Then, the packet is passed to the
NAT ruleset which is read from the top
down, where the first matching rule wins.
IPF tests each
NAT rule against the packet's interface
name and source IP address. When a
packet's interface name matches a NAT rule,
the packet's source IP address in the
private LAN is checked to see if it falls
within the IP address range specified in
LAN_IP_RANGE
. On a match, the
packet has its source IP address rewritten
with the public IP address specified by
PUBLIC_ADDRESS
.
IPF posts an entry in its internal
NAT table so that when the packet returns
from the Internet, it can be mapped back to its original
private IP address before being passed to
the firewall rules for further processing.
For networks that have large numbers of internal systems or multiple subnets, the process of funneling every private IP address into a single public IP address becomes a resource problem. Two methods are available to relieve this issue.
The first method is to assign a range of ports to use as
source ports. By adding the portmap
keyword, NAT can be directed to only use
source ports in the specified range:
map dc0 192.168.1.0/24 -> 0/32 portmap tcp/udp 20000:60000
Alternately, use the auto
keyword
which tells NAT to determine the ports
that are available for use:
map dc0 192.168.1.0/24 -> 0/32 portmap tcp/udp auto
The second method is to use a pool of public addresses. This is useful when there are too many LAN addresses to fit into a single public address and a block of public IP addresses is available. These public addresses can be used as a pool from which NAT selects an IP address as a packet's address is mapped on its way out.
The range of public IP addresses can be specified using a netmask or CIDR notation. These two rules are equivalent:
map dc0 192.168.1.0/24 -> 204.134.75.0/255.255.255.0 map dc0 192.168.1.0/24 -> 204.134.75.0/24
A common practice is to have a publically accessible web
server or mail server segregated to an internal network
segment. The traffic from these servers still has to undergo
NAT, but port redirection is needed to
direct inbound traffic to the correct server. For example, to
map a web server using the internal address 10.0.10.25
to its public
IP address of 20.20.20.5
, use this
rule:
rdr dc0 20.20.20.5/32 port 80 -> 10.0.10.25 port 80
If it is the only web server, this rule would also work as
it redirects all external HTTP requests to
10.0.10.25
:
rdr dc0 0.0.0.0/0 port 80 -> 10.0.10.25 port 80
IPF has a built in FTP proxy which can be used with NAT. It monitors all outbound traffic for active or passive FTP connection requests and dynamically creates temporary filter rules containing the port number used by the FTP data channel. This eliminates the need to open large ranges of high order ports for FTP connections.
In this example, the first rule calls the proxy for outbound FTP traffic from the internal LAN. The second rule passes the FTP traffic from the firewall to the Internet, and the third rule handles all non-FTP traffic from the internal LAN:
map dc0 10.0.10.0/29 -> 0/32 proxy port 21 ftp/tcp map dc0 0.0.0.0/0 -> 0/32 proxy port 21 ftp/tcp map dc0 10.0.10.0/29 -> 0/32
The FTP map
rules go
before the NAT rule so that when a packet
matches an FTP rule, the
FTP proxy creates temporary filter rules to
let the FTP session packets pass and
undergo NAT. All LAN packets that are not
FTP will not match the
FTP rules but will undergo
NAT if they match the third rule.
Without the FTP proxy, the following
firewall rules would instead be needed. Note that without the
proxy, all ports above 1024
need to be
allowed:
# Allow out LAN PC client FTP to public Internet # Active and passive modes pass out quick on rl0 proto tcp from any to any port = 21 flags S keep state # Allow out passive mode data channel high order port numbers pass out quick on rl0 proto tcp from any to any port > 1024 flags S keep state # Active mode let data channel in from FTP server pass in quick on rl0 proto tcp from any to any port = 20 flags S keep state
Whenever the file containing the NAT
rules is edited, run ipnat
with
-CF
to delete the current
NAT rules and flush the contents of the
dynamic translation table. Include -f
and
specify the name of the NAT ruleset to
load:
#
ipnat -CF -f /etc/ipnat.rules
To display the NAT statistics:
#
ipnat -s
To list the NAT table's current mappings:
#
ipnat -l
To turn verbose mode on and display information relating to rule processing and active rules and table entries:
#
ipnat -v
IPF includes ipfstat(8)
which can be used to retrieve
and display statistics which are gathered
as packets match rules as they go through the
firewall. Statistics are accumulated since the firewall was
last started or since the last time they
were reset to zero using ipf
-Z
.
The default ipfstat
output looks
like this:
input packets: blocked 99286 passed 1255609 nomatch 14686 counted 0 output packets: blocked 4200 passed 1284345 nomatch 14687 counted 0 input packets logged: blocked 99286 passed 0 output packets logged: blocked 0 passed 0 packets logged: input 0 output 0 log failures: input 3898 output 0 fragment state(in): kept 0 lost 0 fragment state(out): kept 0 lost 0 packet state(in): kept 169364 lost 0 packet state(out): kept 431395 lost 0 ICMP replies: 0 TCP RSTs sent: 0 Result cache hits(in): 1215208 (out): 1098963 IN Pullups succeeded: 2 failed: 0 OUT Pullups succeeded: 0 failed: 0 Fastroute successes: 0 failures: 0 TCP cksum fails(in): 0 (out): 0 Packet log flags set: (0)
Several options are available. When supplied with either
-i
for inbound or -o
for
outbound, the command will retrieve and display the
appropriate list of filter rules currently installed and in
use by the kernel. To also see the rule numbers, include
-n
. For example, ipfstat
-on
displays the outbound rules table with rule
numbers:
@1 pass out on xl0 from any to any @2 block out on dc0 from any to any @3 pass out quick on dc0 proto tcp/udp from any to any keep state
Include -h
to prefix each rule with a
count of how many times the rule was matched. For example,
ipfstat -oh
displays the outbound internal
rules table, prefixing each rule with its usage count:
2451423 pass out on xl0 from any to any 354727 block out on dc0 from any to any 430918 pass out quick on dc0 proto tcp/udp from any to any keep state
To display the state table in a format similar to
top(1), use ipfstat -t
. When the
firewall is under attack, this option provides the ability to
identify and see the attacking packets. The optional
sub-flags give the ability to select the destination or source
IP, port, or protocol to be monitored in
real time. Refer to ipfstat(8) for details.
IPF provides
ipmon
, which can be used to write the
firewall's logging information in a human readable format. It
requires that options IPFILTER_LOG
be first
added to a custom kernel using the instructions in Chapter 8, Configuring the FreeBSD Kernel.
This command is typically run in daemon mode in order to
provide a continuous system log file so that logging of past
events may be reviewed. Since FreeBSD has a built in
syslogd(8) facility to automatically rotate system logs,
the default rc.conf
ipmon_flags
statement uses
-Ds
:
ipmon_flags="-Ds" # D = start as daemon # s = log to syslog # v = log tcp window, ack, seq # n = map IP & port to names
Logging provides the ability to review, after the fact, information such as which packets were dropped, what addresses they came from, and where they were going. This information is useful in tracking down attackers.
Once the logging facility is enabled in
rc.conf
and started with service
ipmon start
, IPF will
only log the rules which contain the log
keyword. The firewall administrator decides which rules in
the ruleset should be logged and normally only deny rules are
logged. It is customary to include the
log
keyword in the last rule in the
ruleset. This makes it possible to see all the packets that
did not match any of the rules in the ruleset.
By default, ipmon -Ds
mode uses
local0
as the logging facility. The
following logging levels can be used to further segregate the
logged data:
LOG_INFO - packets logged using the "log" keyword as the action rather than pass or block. LOG_NOTICE - packets logged which are also passed LOG_WARNING - packets logged which are also blocked LOG_ERR - packets which have been logged and which can be considered short due to an incomplete header
In order to setup IPF to
log all data to /var/log/ipfilter.log
,
first create the empty file:
#
touch /var/log/ipfilter.log
Then, to write all logged messages to the specified file,
add the following statement to
/etc/syslog.conf
:
local0.* /var/log/ipfilter.log
To activate the changes and instruct syslogd(8)
to read the modified /etc/syslog.conf
,
run service syslogd reload
.
Do not forget to edit
/etc/newsyslog.conf
to rotate the new
log file.
Messages generated by ipmon
consist
of data fields separated by white space. Fields common to
all messages are:
The date of packet receipt.
The time of packet receipt. This is in the form HH:MM:SS.F, for hours, minutes, seconds, and fractions of a second.
The name of the interface that processed the packet.
The group and rule number of the rule in the format
@0:17
.
The action: p
for passed,
b
for blocked, S
for
a short packet, n
did not match any
rules, and L
for a log rule.
The addresses written as three fields: the source
address and port separated by a comma, the -> symbol,
and the destination address and port. For example:
209.53.17.22,80 ->
198.73.220.17,1722
.
PR
followed by the protocol name
or number: for example, PR tcp
.
len
followed by the header length
and total length of the packet: for example,
len 20 40
.
If the packet is a TCP packet, there will be an additional field starting with a hyphen followed by letters corresponding to any flags that were set. Refer to ipf(5) for a list of letters and their flags.
If the packet is an ICMP packet, there
will be two fields at the end: the first always being
“icmp” and the next being the
ICMP message and sub-message type,
separated by a slash. For example:
icmp 3/3
for a port unreachable
message.
Blacklistd is a daemon listening to sockets to receive notifications from other daemons about connection attempts that failed or were successful. It is most widely used in blocking too many connection attempts on open ports. A prime example is SSH running on the internet getting a lot of requests from bots or scripts trying to guess passwords and gain access. Using blacklistd, the daemon can notify the firewall to create a filter rule to block excessive connection attempts from a single source after a number of tries. Blacklistd was first developed on NetBSD and appeared there in version 7. FreeBSD 11 imported blacklistd from NetBSD.
This chapter describes how to set up blacklistd, configure it, and provides examples on how to use it. Readers should be familiar with basic firewall concepts like rules. For details, refer to the firewall chapter. PF is used in the examples, but other firewalls available on FreeBSD should be able to work with blacklistd, too.
The main configuration for blacklistd is stored in
blacklistd.conf(5). Various command line options are
also available to change blacklistd's run-time behavior.
Persistent configuration across reboots should be stored
in /etc/blacklistd.conf
. To enable
the daemon during system boot, add a
blacklistd_enable
line to
/etc/rc.conf
like this:
#
sysrc blacklistd_enable=yes
To start the service manually, run this command:
#
service blacklistd start
Rules for blacklistd are configured in
blacklistd.conf(5) with one entry per line. Each
rule contains a tuple separated by spaces or tabs. Rules
either belong to a local
or a
remote
, which applies to the machine
where blacklistd is running or an outside source,
respectively.
An example blacklistd.conf entry for a local rule looks like this:
[local] ssh stream * * * 3 24h
All rules that follow the [local]
section are treated as local rules (which is the
default), applying to the local machine. When a
[remote]
section is encountered, all
rules that follow it are handled as remote machine
rules.
Seven fields define a rule separated by either tabs
or spaces. The first four fields identify the traffic
that should be blacklisted. The three fields that
follow define backlistd's behavior. Wildcards are
denoted as asterisks (*
), matching
anything in this field. The first field defines the
location. In local rules, these are the network ports.
The syntax for the location field is as follows:
[address
|interface
][/mask
][:port
]
Adressses can be specified as IPv4 in numeric format
or IPv6 in square brackets. An interface name like
can also
be used.em0
The socket type is defined by the second field. TCP
sockets are of type stream
, whereas UDP
is denoted as dgram
. The example above
uses TCP, since SSH is using that protocol.
A protocol can be used in the third field of a
blacklistd rule. The following protocols can be used:
tcp
, udp
,
tcp6
, udp6
, or
numeric. A wildcard, like in the example, is typically
used to match all protocols unless there is a reason to
distinguish traffic by a certain protocol.
In the fourth field, the effective user or owner of the daemon process that is reporting the event is defined. The username or UID can be used here, as well as a wildcard (see example rule above).
The packet filter rule name is declared by the fifth
field, which starts the behavior part of the rule. By
default, blacklistd puts all blocks under a pf anchor
called blacklistd
in
pf.conf
like this:
anchor "blacklistd/*" in on $ext_if block in pass out
For separate blacklists, an anchor name can be used in
this field. In other cases, the wildcard will suffice.
When a name starts with a hyphen (-
) it
means that an anchor with the default rule name prepended
should be used. A modified example from the above using
the hyphen would look like this:
ssh stream * * -ssh 3 24h
With such a rule, any new blacklist rules are added to
an anchor called blacklistd-ssh
.
To block whole subnets for a single rule violation, a
/
in the rule name can be used. This
causes the remaining portion of the name to be interpreted
as the mask to be applied to the address specified in
the rule. For example, this rule would block every
address adjoining /24
.
22 stream tcp * */24 3 24h
It is important to specify the proper
protocol here. IPv4 and IPv6 treat /24 differently,
that is the reason why *
cannot be
used in the third field for this rule.
This rule defines that if any one host in that network is misbehaving, everything else on that network will be blocked, too.
The sixth field, called nfail
, sets
the number of login failures required to blacklist the
remote IP in question. When a wildcard is used at this
position, it means that blocks will never happen. In the
example rule above, a limit of three is defined meaning
that after three attempts to log into
SSH on one connection, the IP
is blocked.
The last field in a blacklistd rule definition
specifies how long a host is blacklisted. The default
unit is seconds, but suffixes like m
,
h
, and d
can also be
specified for minutes, hours, and days,
respectively.
The example rule in its entirety means that after
three times authenticating to
SSH will result in a new PF
block rule for that host. Rule matches are performed by
first checking local rules one after another, from most
specific to least specific. When a match occurs, the
remote
rules are applied and the name,
nfail
, and disable fields are changed
by the remote
rule that matched.
Remote rules are used to specify how blacklistd changes its behavior depending on the remote host currently being evaluated. Each field in a remote rule is the same as in a local rule. The only difference is in the way blacklistd is using them. To explain it, this example rule is used:
[remote] 203.0.113.128/25 * * * =/25 = 48h
The address field can be an IP address (either v4 or v6), a port or both. This allows setting special rules for a specific remote address range like in this example. The fields for type, protocol and owner are identically interpreted as in the local rule.
The name fields is different though: the equal sign
(=
) in a remote rule tells blacklistd
to use the value from the matching local rule. It means
that the firewall rule entry is taken and the
/25
prefix (a
netmask of 255.255.255.128
) is added.
When a connection from that address range is blacklisted,
the entire subnet is affected. A PF anchor name can also
be used here, in which case blacklistd will add rules for
this address block to the anchor of that name. The
default table is used when a wildcard is specified.
A custom number of failures in the
nfail
column can be defined for an
address. This is useful for exceptions to a specific
rule, to maybe allow someone a less strict application
of rules or a bit more leniency in login tries.
Blocking is disabled when an asterisk is used in this
sixth field.
Remote rules allow a stricter enforcement of limits on attempts to log in compared to attempts coming from a local network like an office.
There are a few software packages in FreeBSD that can
utilize blacklistd's functionality. The two most
prominent ones are ftpd(8) and sshd(8) to block
excessive connection attempts. To activate blacklistd in
the SSH daemon, add the following line to
/etc/ssh/sshd_config
:
UseBlacklist yes
Restart sshd afterwards to make these changes take effect.
Blacklisting for ftpd(8) is enabled using
-B
, either in
/etc/inetd.conf
or as a
flag in /etc/rc.conf
like
this:
ftpd_flags="-B"
That is all that is needed to make these programs talk to blacklistd.
Blacklistd provides the user with a management utility
called blacklistctl(8). It displays blocked
addresses and networks that are blacklisted by the rules
defined in blacklistd.conf(5). To see the
list of currently blocked hosts, use
dump
combined with -b
like this.
#
blacklistctl dump -b
address/ma:port id nfail last access 213.0.123.128/25:22 OK 6/3 2019/06/08 14:30:19
This example shows that there were 6 out of three
permitted attempts on port 22 coming from the address
range 213.0.123.128/25
. There
are more attempts listed than are allowed because SSH
allows a client to try multiple logins on a single TCP
connection. A connection that is currently going on is
not stopped by blacklistd. The last connection attempt is
listed in the last access
column of the
output.
To see the remaining time that this host will be on
the blacklist, add -r
to the previous
command.
#
blacklistctl dump -br
address/ma:port id nfail remaining time 213.0.123.128/25:22 OK 6/3 36s
In this example, there are 36s seconds left until this host will not be blocked any more.
Sometimes it is necessary to remove a host from the
block list before the remaining time expires.
Unfortunately, there is no functionality in blacklistd to
do that. However, it is possible to remove the address
from the PF table using pfctl. For each blocked port,
there is a child anchor inside the blacklistd anchor
defined in /etc/pf.conf
. For
example, if there is a child anchor for blocking port 22
it is called blacklistd/22
. There is a
table inside that child anchor that contains the blocked
addresses. This table is called port followed by the port
number. In this example, it would be called
port22
. With that information at hand,
it is now possible to use pfctl(8) to display all
addresses listed like this:
#
pfctl -a
... 213.0.123.128/25 ...blacklistd/22
-tport22
-T show
After identifying the address to be unblocked from the list, the following command removes it from the list:
#
pfctl -a
blacklistd/22
-T delete213.0.123.128/25
The address is now removed from PF, but will still show up in the blacklistctl list, since it does not know about any changes made in PF. The entry in blacklistd's database will eventually expire and be removed from its output eventually. The entry will be added again if the host is matching one of the block rules in blacklistd again.
This chapter covers a number of advanced networking topics.
After reading this chapter, you will know:
The basics of gateways and routes.
How to set up USB tethering.
How to set up IEEE® 802.11 and Bluetooth® devices.
How to make FreeBSD act as a bridge.
How to set up network PXE booting.
How to set up IPv6 on a FreeBSD machine.
How to enable and utilize the features of the Common Address Redundancy Protocol (CARP) in FreeBSD.
How to configure multiple VLANs on FreeBSD.
Configure bluetooth headset.
Before reading this chapter, you should:
Understand the basics of the
/etc/rc
scripts.
Be familiar with basic network terminology.
Know how to configure and install a new FreeBSD kernel (Chapter 8, Configuring the FreeBSD Kernel).
Know how to install additional third-party software (Chapter 4, Installing Applications: Packages and Ports).
Routing is the mechanism that allows a system to find the network path to another system. A route is a defined pair of addresses which represent the “destination” and a “gateway”. The route indicates that when trying to get to the specified destination, send the packets through the specified gateway. There are three types of destinations: individual hosts, subnets, and “default”. The “default route” is used if no other routes apply. There are also three types of gateways: individual hosts, interfaces, also called links, and Ethernet hardware (MAC) addresses. Known routes are stored in a routing table.
This section provides an overview of routing basics. It then demonstrates how to configure a FreeBSD system as a router and offers some troubleshooting tips.
To view the routing table of a FreeBSD system, use netstat(1):
%
netstat -r
Routing tables Internet: Destination Gateway Flags Refs Use Netif Expire default outside-gw UGS 37 418 em0 localhost localhost UH 0 181 lo0 test0 0:e0:b5:36:cf:4f UHLW 5 63288 re0 77 10.20.30.255 link#1 UHLW 1 2421 example.com link#1 UC 0 0 host1 0:e0:a8:37:8:1e UHLW 3 4601 lo0 host2 0:e0:a8:37:8:1e UHLW 0 5 lo0 => host2.example.com link#1 UC 0 0 224 link#1 UC 0 0
The entries in this example are as follows:
The first route in this table specifies the
default
route. When the local system
needs to make a connection to a remote host, it checks
the routing table to determine if a known path exists.
If the remote host matches an entry in the table, the
system checks to see if it can connect using the
interface specified in that entry.
If the destination does not match an entry, or if
all known paths fail, the system uses the entry for the
default route. For hosts on a local area network, the
Gateway
field in the default route is
set to the system which has a direct connection to the
Internet. When reading this entry, verify that the
Flags
column indicates that the
gateway is usable (UG
).
The default route for a machine which itself is functioning as the gateway to the outside world will be the gateway machine at the Internet Service Provider (ISP).
The second route is the localhost
route. The interface specified in the
Netif
column for
localhost
is
lo0
, also known as the loopback
device. This indicates that all traffic for this
destination should be internal, rather than sending it
out over the network.
The addresses beginning with 0:e0:
are
MAC addresses. FreeBSD will
automatically identify any hosts,
test0
in the example, on the
local Ethernet and add a route for that host over the
Ethernet interface, re0
. This type
of route has a timeout, seen in the
Expire
column, which is used if the
host does not respond in a specific amount of time.
When this happens, the route to this host will be
automatically deleted. These hosts are identified using
the Routing Information Protocol
(RIP), which calculates routes to
local hosts based upon a shortest path
determination.
FreeBSD will automatically add subnet routes for the
local subnet. In this example, 10.20.30.255
is the
broadcast address for the subnet 10.20.30
and
example.com
is the
domain name associated with that subnet. The
designation link#1
refers to the
first Ethernet card in the machine.
Local network hosts and local subnets have their routes automatically configured by a daemon called routed(8). If it is not running, only routes which are statically defined by the administrator will exist.
The host1
line refers to the host
by its Ethernet address. Since it is the sending host,
FreeBSD knows to use the loopback interface
(lo0
) rather than the Ethernet
interface.
The two host2
lines represent
aliases which were created using ifconfig(8). The
=>
symbol after the
lo0
interface says that an alias
has been set in addition to the loopback address. Such
routes only show up on the host that supports the alias
and all other hosts on the local network will have a
link#1
line for such routes.
The final line (destination subnet 224
) deals with
multicasting.
Various attributes of each route can be seen in the
Flags
column. Table 31.1, “Commonly Seen Routing Table Flags”
summarizes some of these flags and their meanings:
Command | Purpose |
---|---|
U | The route is active (up). |
H | The route destination is a single host. |
G | Send anything for this destination on to this gateway, which will figure out from there where to send it. |
S | This route was statically configured. |
C | Clones a new route based upon this route for machines to connect to. This type of route is normally used for local networks. |
W | The route was auto-configured based upon a local area network (clone) route. |
L | Route involves references to Ethernet (link) hardware. |
On a FreeBSD system, the default route can defined in
/etc/rc.conf
by specifying the
IP address of the default gateway:
defaultrouter="10.20.30.1"
It is also possible to manually add the route using
route
:
#
route add default 10.20.30.1
Note that manually added routes will not survive a reboot. For more information on manual manipulation of network routing tables, refer to route(8).
A FreeBSD system can be configured as the default gateway, or router, for a network if it is a dual-homed system. A dual-homed system is a host which resides on at least two different networks. Typically, each network is connected to a separate network interface, though IP aliasing can be used to bind multiple addresses, each on a different subnet, to one physical interface.
In order for the system to forward packets between
interfaces, FreeBSD must be configured as a router. Internet
standards and good engineering practice prevent the FreeBSD
Project from enabling this feature by default, but it can be
configured to start at boot by adding this line to
/etc/rc.conf
:
gateway_enable="YES" # Set to YES if this host will be a gateway
To enable routing now, set the sysctl(8) variable
net.inet.ip.forwarding
to
1
. To stop routing, reset this variable to
0
.
The routing table of a router needs additional routes so it knows how to reach other networks. Routes can be either added manually using static routes or routes can be automatically learned using a routing protocol. Static routes are appropriate for small networks and this section describes how to add a static routing entry for a small network.
For large networks, static routes quickly become unscalable. FreeBSD comes with the standard BSD routing daemon routed(8), which provides the routing protocols RIP, versions 1 and 2, and IRDP. Support for the BGP and OSPF routing protocols can be installed using the net/zebra package or port.
Consider the following network:
In this scenario, RouterA
is a
FreeBSD machine that is acting as a router to the rest of the
Internet. It has a default route set to 10.0.0.1
which allows it to
connect with the outside world.
RouterB
is already configured to use
192.168.1.1
as its
default gateway.
Before adding any static routes, the routing table on
RouterA
looks like this:
%
netstat -nr
Routing tables Internet: Destination Gateway Flags Refs Use Netif Expire default 10.0.0.1 UGS 0 49378 xl0 127.0.0.1 127.0.0.1 UH 0 6 lo0 10.0.0.0/24 link#1 UC 0 0 xl0 192.168.1.0/24 link#2 UC 0 0 xl1
With the current routing table,
RouterA
does not have a route to the
192.168.2.0/24
network. The following command adds the Internal Net
2
network to RouterA
's
routing table using 192.168.1.2
as the next
hop:
#
route add -net 192.168.2.0/24 192.168.1.2
Now, RouterA
can reach any host
on the 192.168.2.0/24
network.
However, the routing information will not persist if the FreeBSD
system reboots. If a static route needs to be persistent, add
it to /etc/rc.conf
:
# Add Internal Net 2 as a persistent static route static_routes="internalnet2" route_internalnet2="-net 192.168.2.0/24 192.168.1.2"
The static_routes
configuration
variable is a list of strings separated by a space, where each
string references a route name. The variable
route_
contains the static route for that route name.internalnet2
Using more than one string in
static_routes
creates multiple static
routes. The following shows an example of adding static
routes for the 192.168.0.0/24
and
192.168.1.0/24
networks:
static_routes="net1 net2" route_net1="-net 192.168.0.0/24 192.168.0.1" route_net2="-net 192.168.1.0/24 192.168.1.1"
When an address space is assigned to a network, the service provider configures their routing tables so that all traffic for the network will be sent to the link for the site. But how do external sites know to send their packets to the network's ISP?
There is a system that keeps track of all assigned address spaces and defines their point of connection to the Internet backbone, or the main trunk lines that carry Internet traffic across the country and around the world. Each backbone machine has a copy of a master set of tables, which direct traffic for a particular network to a specific backbone carrier, and from there down the chain of service providers until it reaches a particular network.
It is the task of the service provider to advertise to the backbone sites that they are the point of connection, and thus the path inward, for a site. This is known as route propagation.
Sometimes, there is a problem with route propagation and
some sites are unable to connect. Perhaps the most useful
command for trying to figure out where routing is breaking
down is traceroute
. It is useful when
ping
fails.
When using traceroute
, include the
address of the remote host to connect to. The output will
show the gateway hosts along the path of the attempt,
eventually either reaching the target host, or terminating
because of a lack of connection. For more information, refer
to traceroute(8).
FreeBSD natively supports both multicast applications and multicast routing. Multicast applications do not require any special configuration in order to run on FreeBSD. Support for multicast routing requires that the following option be compiled into a custom kernel:
options MROUTING
The multicast routing daemon,
mrouted can be installed using the
net/mrouted package or port. This daemon
implements the DVMRP multicast routing
protocol and is configured by editing
/usr/local/etc/mrouted.conf
in order to
set up the tunnels and DVMRP. The
installation of mrouted also
installs map-mbone and
mrinfo, as well as their associated
man pages. Refer to these for configuration examples.
DVMRP has largely been replaced by the PIM protocol in many multicast installations. Refer to pim(4) for more information.
Most wireless networks are based on the IEEE® 802.11 standards. A basic wireless network consists of multiple stations communicating with radios that broadcast in either the 2.4GHz or 5GHz band, though this varies according to the locale and is also changing to enable communication in the 2.3GHz and 4.9GHz ranges.
802.11 networks are organized in two ways. In infrastructure mode, one station acts as a master with all the other stations associating to it, the network is known as a BSS, and the master station is termed an access point (AP). In a BSS, all communication passes through the AP; even when one station wants to communicate with another wireless station, messages must go through the AP. In the second form of network, there is no master and stations communicate directly. This form of network is termed an IBSS and is commonly known as an ad-hoc network.
802.11 networks were first deployed in the 2.4GHz band using protocols defined by the IEEE® 802.11 and 802.11b standard. These specifications include the operating frequencies and the MAC layer characteristics, including framing and transmission rates, as communication can occur at various rates. Later, the 802.11a standard defined operation in the 5GHz band, including different signaling mechanisms and higher transmission rates. Still later, the 802.11g standard defined the use of 802.11a signaling and transmission mechanisms in the 2.4GHz band in such a way as to be backwards compatible with 802.11b networks.
Separate from the underlying transmission techniques, 802.11 networks have a variety of security mechanisms. The original 802.11 specifications defined a simple security protocol called WEP. This protocol uses a fixed pre-shared key and the RC4 cryptographic cipher to encode data transmitted on a network. Stations must all agree on the fixed key in order to communicate. This scheme was shown to be easily broken and is now rarely used except to discourage transient users from joining networks. Current security practice is given by the IEEE® 802.11i specification that defines new cryptographic ciphers and an additional protocol to authenticate stations to an access point and exchange keys for data communication. Cryptographic keys are periodically refreshed and there are mechanisms for detecting and countering intrusion attempts. Another security protocol specification commonly used in wireless networks is termed WPA, which was a precursor to 802.11i. WPA specifies a subset of the requirements found in 802.11i and is designed for implementation on legacy hardware. Specifically, WPA requires only the TKIP cipher that is derived from the original WEP cipher. 802.11i permits use of TKIP but also requires support for a stronger cipher, AES-CCM, for encrypting data. The AES cipher was not required in WPA because it was deemed too computationally costly to be implemented on legacy hardware.
The other standard to be aware of is 802.11e. It defines protocols for deploying multimedia applications, such as streaming video and voice over IP (VoIP), in an 802.11 network. Like 802.11i, 802.11e also has a precursor specification termed WME (later renamed WMM) that has been defined by an industry group as a subset of 802.11e that can be deployed now to enable multimedia applications while waiting for the final ratification of 802.11e. The most important thing to know about 802.11e and WME/WMM is that it enables prioritized traffic over a wireless network through Quality of Service (QoS) protocols and enhanced media access protocols. Proper implementation of these protocols enables high speed bursting of data and prioritized traffic flow.
FreeBSD supports networks that operate using 802.11a, 802.11b, and 802.11g. The WPA and 802.11i security protocols are likewise supported (in conjunction with any of 11a, 11b, and 11g) and QoS and traffic prioritization required by the WME/WMM protocols are supported for a limited set of wireless devices.
Connecting a computer to an existing wireless network is a very common situation. This procedure shows the steps required.
Obtain the SSID (Service Set Identifier) and PSK (Pre-Shared Key) for the wireless network from the network administrator.
Identify the wireless adapter. The FreeBSD
GENERIC
kernel includes drivers for
many common wireless adapters. If the wireless adapter is
one of those models, it will be shown in the output from
ifconfig(8):
%
ifconfig | grep -B3 -i wireless
On FreeBSD 11 or higher, use this command instead:
%
sysctl net.wlan.devices
If a wireless adapter is not listed, an additional kernel module might be required, or it might be a model not supported by FreeBSD.
This example shows the Atheros ath0
wireless adapter.
Add an entry for this network to
/etc/wpa_supplicant.conf
. If the
file does not exist, create it. Replace
myssid
and
mypsk
with the
SSID and PSK
provided by the network administrator.
network={ ssid="myssid
" psk="mypsk
" }
Add entries to /etc/rc.conf
to
configure the network on startup:
wlans_ath0
="wlan0"
ifconfig_wlan0="WPA SYNCDHCP"
Restart the computer, or restart the network service to connect to the network:
#
service netif restart
To use wireless networking, a wireless networking card is needed and the kernel needs to be configured with the appropriate wireless networking support. The kernel is separated into multiple modules so that only the required support needs to be configured.
The most
commonly used wireless devices are those that use parts made
by Atheros. These devices are supported by ath(4)
and require the following line to be added to
/boot/loader.conf
:
if_ath_load="YES"
The Atheros driver is split up into three separate pieces: the driver (ath(4)), the hardware support layer that handles chip-specific functions (ath_hal(4)), and an algorithm for selecting the rate for transmitting frames. When this support is loaded as kernel modules, any dependencies are automatically handled. To load support for a different type of wireless device, specify the module for that device. This example is for devices based on the Intersil Prism parts (wi(4)) driver:
if_wi_load="YES"
The examples in this section use an ath(4) device and the device name in the examples must be changed according to the configuration. A list of available wireless drivers and supported adapters can be found in the FreeBSD Hardware Notes, available on the Release Information page of the FreeBSD website. If a native FreeBSD driver for the wireless device does not exist, it may be possible to use the Windows® driver with the help of the NDIS driver wrapper.
In addition, the modules that implement cryptographic
support for the security protocols to use must be loaded.
These are intended to be dynamically loaded on demand by
the wlan(4) module, but for now they must be manually
configured. The following modules are available:
wlan_wep(4), wlan_ccmp(4), and wlan_tkip(4).
The wlan_ccmp(4) and wlan_tkip(4) drivers are
only needed when using the WPA or
802.11i security protocols. If the network does not use
encryption, wlan_wep(4) support is not needed. To
load these modules at boot time, add the following lines to
/boot/loader.conf
:
wlan_wep_load="YES" wlan_ccmp_load="YES" wlan_tkip_load="YES"
Once this information has been added to
/boot/loader.conf
, reboot the FreeBSD
box. Alternately, load the modules by hand using
kldload(8).
For users who do not want to use modules, it is possible to compile these drivers into the kernel by adding the following lines to a custom kernel configuration file:
device wlan # 802.11 support device wlan_wep # 802.11 WEP support device wlan_ccmp # 802.11 CCMP support device wlan_tkip # 802.11 TKIP support device wlan_amrr # AMRR transmit rate control algorithm device ath # Atheros pci/cardbus NIC's device ath_hal # pci/cardbus chip support options AH_SUPPORT_AR5416 # enable AR5416 tx/rx descriptors device ath_rate_sample # SampleRate tx rate control for ath
With this information in the kernel configuration file, recompile the kernel and reboot the FreeBSD machine.
Information about the wireless device should appear in the boot messages, like this:
ath0: <Atheros 5212> mem 0x88000000-0x8800ffff irq 11 at device 0.0 on cardbus1 ath0: [ITHREAD] ath0: AR2413 mac 7.9 RF2413 phy 4.5
Since the regulatory situation is different in various parts of the world, it is necessary to correctly set the domains that apply to your location to have the correct information about what channels can be used.
The available region definitions can be found in
/etc/regdomain.xml
. To set the data at
runtime, use ifconfig
:
#
ifconfig
wlan0
regdomainETSI
countryAT
To persist the settings, add it to
/etc/rc.conf
:
#
sysrc create_args_wlan0="country
AT
regdomainETSI
"
Infrastructure (BSS) mode is the mode that is typically used. In this mode, a number of wireless access points are connected to a wired network. Each wireless network has its own name, called the SSID. Wireless clients connect to the wireless access points.
To scan for available networks, use ifconfig(8). This request may take a few moments to complete as it requires the system to switch to each available wireless frequency and probe for available access points. Only the superuser can initiate a scan:
#
ifconfig
wlan0
create wlandevath0
#
ifconfig
SSID/MESH ID BSSID CHAN RATE S:N INT CAPS dlinkap 00:13:46:49:41:76 11 54M -90:96 100 EPS WPA WME freebsdap 00:11:95:c3:0d:ac 1 54M -83:96 100 EPS WPAwlan0
up scan
The interface must be up
before
it can scan. Subsequent scan requests do not require
the interface to be marked as up again.
The output of a scan request lists each
BSS/IBSS network
found. Besides listing the name of the network, the
SSID
, the output also shows the
BSSID
, which is the
MAC address of the access point. The
CAPS
field identifies the type of
each network and the capabilities of the stations
operating there:
Capability Code | Meaning |
---|---|
E | Extended Service Set (ESS). Indicates that the station is part of an infrastructure network rather than an IBSS/ad-hoc network. |
I | IBSS/ad-hoc network. Indicates that the station is part of an ad-hoc network rather than an ESS network. |
P | Privacy. Encryption is required for all data frames exchanged within the BSS using cryptographic means such as WEP, TKIP or AES-CCMP. |
S | Short Preamble. Indicates that the network is using short preambles, defined in 802.11b High Rate/DSSS PHY, and utilizes a 56 bit sync field rather than the 128 bit field used in long preamble mode. |
s | Short slot time. Indicates that the 802.11g network is using a short slot time because there are no legacy (802.11b) stations present. |
One can also display the current list of known networks with:
#
ifconfig
wlan0
list scan
This information may be updated automatically by the
adapter or manually with a scan
request.
Old data is automatically removed from the cache, so over
time this list may shrink unless more scans are
done.
This section provides a simple example of how to make the wireless network adapter work in FreeBSD without encryption. Once familiar with these concepts, it is strongly recommend to use WPA to set up the wireless network.
There are three basic steps to configure a wireless network: select an access point, authenticate the station, and configure an IP address. The following sections discuss each step.
Most of the time, it is sufficient to let the system
choose an access point using the builtin heuristics.
This is the default behavior when an interface is
marked as up or it is listed in
/etc/rc.conf
:
wlans_ath0="wlan0" ifconfig_wlan0="DHCP"
If there are multiple access points, a specific one can be selected by its SSID:
wlans_ath0="wlan0"
ifconfig_wlan0="ssid your_ssid_here
DHCP"
In an environment where there are multiple access points with the same SSID, which is often done to simplify roaming, it may be necessary to associate to one specific device. In this case, the BSSID of the access point can be specified, with or without the SSID:
wlans_ath0="wlan0" ifconfig_wlan0="ssidyour_ssid_here
bssidxx:xx:xx:xx:xx:xx
DHCP"
There are other ways to constrain the choice of an
access point, such as limiting the set of frequencies
the system will scan on. This may be useful for a
multi-band wireless card as scanning all the possible
channels can be time-consuming. To limit operation to a
specific band, use the mode
parameter:
wlans_ath0="wlan0" ifconfig_wlan0="mode11g
ssidyour_ssid_here
DHCP"
This example will force the card to operate in
802.11g, which is defined only for 2.4GHz frequencies
so any 5GHz channels will not be considered. This can
also be achieved with the
channel
parameter, which locks
operation to one specific frequency, and the
chanlist
parameter, to specify a list
of channels for scanning. More information about these
parameters can be found in ifconfig(8).
Once an access point is selected, the station needs to authenticate before it can pass data. Authentication can happen in several ways. The most common scheme, open authentication, allows any station to join the network and communicate. This is the authentication to use for test purposes the first time a wireless network is setup. Other schemes require cryptographic handshakes to be completed before data traffic can flow, either using pre-shared keys or secrets, or more complex schemes that involve backend services such as RADIUS. Open authentication is the default setting. The next most common setup is WPA-PSK, also known as WPA Personal, which is described in Section 31.3.4.1.3.1, “WPA-PSK”.
If using an Apple® AirPort® Extreme base
station for an access point, shared-key authentication
together with a WEP key needs to
be configured. This can be configured in
/etc/rc.conf
or by using
wpa_supplicant(8). For a single AirPort® base
station, access can be configured with:
wlans_ath0="wlan0" ifconfig_wlan0="authmode shared wepmode on weptxkey1
wepkey01234567
DHCP"
In general, shared key authentication should be
avoided because it uses the WEP key
material in a highly-constrained manner, making it
even easier to crack the key. If
WEP must be used for compatibility
with legacy devices, it is better to use
WEP with open
authentication. More information regarding
WEP can be found in Section 31.3.4.1.4, “WEP”.
Once an access point is selected and the
authentication parameters are set, an
IP address must be obtained in
order to communicate. Most of the time, the
IP address is obtained via
DHCP. To achieve that, edit
/etc/rc.conf
and add
DHCP
to the configuration for the
device:
wlans_ath0="wlan0" ifconfig_wlan0="DHCP"
The wireless interface is now ready to bring up:
#
service netif start
Once the interface is running, use ifconfig(8)
to see the status of the interface
ath0
:
#
ifconfig
wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 ether 00:11:95:d5:43:62 inet 192.168.1.100 netmask 0xffffff00 broadcast 192.168.1.255 media: IEEE 802.11 Wireless Ethernet OFDM/54Mbps mode 11g status: associated ssid dlinkap channel 11 (2462 Mhz 11g) bssid 00:13:46:49:41:76 country US ecm authmode OPEN privacy OFF txpower 21.5 bmiss 7 scanvalid 60 bgscan bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS wme burstwlan0
The status: associated
line means
that it is connected to the wireless network. The
bssid 00:13:46:49:41:76
is the
MAC address of the access point and
authmode OPEN
indicates that the
communication is not encrypted.
If an IP address cannot be
obtained from a DHCP server, set a
fixed IP address. Replace the
DHCP
keyword shown above with the
address information. Be sure to retain any other
parameters for selecting the access point:
wlans_ath0="wlan0" ifconfig_wlan0="inet192.168.1.100
netmask255.255.255.0
ssidyour_ssid_here
"
Wi-Fi Protected Access (WPA) is a security protocol used together with 802.11 networks to address the lack of proper authentication and the weakness of WEP. WPA leverages the 802.1X authentication protocol and uses one of several ciphers instead of WEP for data integrity. The only cipher required by WPA is the Temporary Key Integrity Protocol (TKIP). TKIP is a cipher that extends the basic RC4 cipher used by WEP by adding integrity checking, tamper detection, and measures for responding to detected intrusions. TKIP is designed to work on legacy hardware with only software modification. It represents a compromise that improves security but is still not entirely immune to attack. WPA also specifies the AES-CCMP cipher as an alternative to TKIP, and that is preferred when possible. For this specification, the term WPA2 or RSN is commonly used.
WPA defines authentication and encryption protocols. Authentication is most commonly done using one of two techniques: by 802.1X and a backend authentication service such as RADIUS, or by a minimal handshake between the station and the access point using a pre-shared secret. The former is commonly termed WPA Enterprise and the latter is known as WPA Personal. Since most people will not set up a RADIUS backend server for their wireless network, WPA-PSK is by far the most commonly encountered configuration for WPA.
The control of the wireless connection and the key
negotiation or authentication with a server is done using
wpa_supplicant(8). This program requires a
configuration file,
/etc/wpa_supplicant.conf
, to run.
More information regarding this file can be found in
wpa_supplicant.conf(5).
WPA-PSK, also known as WPA Personal, is based on a pre-shared key (PSK) which is generated from a given password and used as the master key in the wireless network. This means every wireless user will share the same key. WPA-PSK is intended for small networks where the use of an authentication server is not possible or desired.
Always use strong passwords that are sufficiently long and made from a rich alphabet so that they will not be easily guessed or attacked.
The first step is the configuration of
/etc/wpa_supplicant.conf
with
the SSID and the pre-shared key of
the network:
network={ ssid="freebsdap" psk="freebsdmall" }
Then, in /etc/rc.conf
,
indicate that the wireless device configuration will be
done with WPA and the
IP address will be obtained with
DHCP:
wlans_ath0="wlan0" ifconfig_wlan0="WPA DHCP"
Then, bring up the interface:
#
service netif start
Starting wpa_supplicant. DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 5 DHCPDISCOVER on wlan0 to 255.255.255.255 port 67 interval 6 DHCPOFFER from 192.168.0.1 DHCPREQUEST on wlan0 to 255.255.255.255 port 67 DHCPACK from 192.168.0.1 bound to 192.168.0.254 -- renewal in 300 seconds. wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 ether 00:11:95:d5:43:62 inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255 media: IEEE 802.11 Wireless Ethernet OFDM/36Mbps mode 11g status: associated ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS wme burst roaming MANUAL
Or, try to configure the interface manually using
the information in
/etc/wpa_supplicant.conf
:
#
wpa_supplicant -i
Trying to associate with 00:11:95:c3:0d:ac (SSID='freebsdap' freq=2412 MHz) Associated with 00:11:95:c3:0d:ac WPA: Key negotiation completed with 00:11:95:c3:0d:ac [PTK=CCMP GTK=CCMP] CTRL-EVENT-CONNECTED - Connection to 00:11:95:c3:0d:ac completed (auth) [id=0 id_str=]wlan0
-c /etc/wpa_supplicant.conf
The next operation is to launch dhclient(8) to get the IP address from the DHCP server:
#
dhclient
DHCPREQUEST on wlan0 to 255.255.255.255 port 67 DHCPACK from 192.168.0.1 bound to 192.168.0.254 -- renewal in 300 seconds.wlan0
#
ifconfig
wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 ether 00:11:95:d5:43:62 inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255 media: IEEE 802.11 Wireless Ethernet OFDM/36Mbps mode 11g status: associated ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS wme burst roaming MANUALwlan0
If /etc/rc.conf
has an
ifconfig_wlan0="DHCP"
entry,
dhclient(8) will be launched automatically after
wpa_supplicant(8) associates with the access
point.
If DHCP is not possible or desired, set a static IP address after wpa_supplicant(8) has authenticated the station:
#
ifconfig
wlan0
inet192.168.0.100
netmask255.255.255.0
#
ifconfig
wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 ether 00:11:95:d5:43:62 inet 192.168.0.100 netmask 0xffffff00 broadcast 192.168.0.255 media: IEEE 802.11 Wireless Ethernet OFDM/36Mbps mode 11g status: associated ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS wme burst roaming MANUALwlan0
When DHCP is not used, the default gateway and the nameserver also have to be manually set:
#
route add default
your_default_router
#
echo "nameserver
your_DNS_server
" >> /etc/resolv.conf
The second way to use WPA is with an 802.1X backend authentication server. In this case, WPA is called WPA Enterprise to differentiate it from the less secure WPA Personal. Authentication in WPA Enterprise is based on the Extensible Authentication Protocol (EAP).
EAP does not come with an encryption method. Instead, EAP is embedded inside an encrypted tunnel. There are many EAP authentication methods, but EAP-TLS, EAP-TTLS, and EAP-PEAP are the most common.
EAP with Transport Layer Security (EAP-TLS) is a well-supported wireless authentication protocol since it was the first EAP method to be certified by the Wi-Fi Alliance. EAP-TLS requires three certificates to run: the certificate of the Certificate Authority (CA) installed on all machines, the server certificate for the authentication server, and one client certificate for each wireless client. In this EAP method, both the authentication server and wireless client authenticate each other by presenting their respective certificates, and then verify that these certificates were signed by the organization's CA.
As previously, the configuration is done via
/etc/wpa_supplicant.conf
:
network={ ssid="freebsdap" proto=RSN key_mgmt=WPA-EAP eap=TLS identity="loader" ca_cert="/etc/certs/cacert.pem" client_cert="/etc/certs/clientcert.pem" private_key="/etc/certs/clientkey.pem" private_key_passwd="freebsdmallclient" }
This field indicates the network name (SSID). | |
This example uses the RSN IEEE® 802.11i protocol, also known as WPA2. | |
The | |
This field indicates the EAP method for the connection. | |
The | |
The | |
The | |
The | |
The |
Then, add the following lines to
/etc/rc.conf
:
wlans_ath0="wlan0" ifconfig_wlan0="WPA DHCP"
The next step is to bring up the interface:
#
service netif start
Starting wpa_supplicant. DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 7 DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 15 DHCPACK from 192.168.0.20 bound to 192.168.0.254 -- renewal in 300 seconds. wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 ether 00:11:95:d5:43:62 inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255 media: IEEE 802.11 Wireless Ethernet DS/11Mbps mode 11g status: associated ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS wme burst roaming MANUAL
It is also possible to bring up the interface manually using wpa_supplicant(8) and ifconfig(8).
With EAP-TLS, both the authentication server and the client need a certificate. With EAP-TTLS, a client certificate is optional. This method is similar to a web server which creates a secure SSL tunnel even if visitors do not have client-side certificates. EAP-TTLS uses an encrypted TLS tunnel for safe transport of the authentication data.
The required configuration can be added to
/etc/wpa_supplicant.conf
:
network={ ssid="freebsdap" proto=RSN key_mgmt=WPA-EAP eap=TTLS identity="test" password="test" ca_cert="/etc/certs/cacert.pem" phase2="auth=MD5" }
This field specifies the EAP method for the connection. | |
The | |
The | |
The | |
This field specifies the authentication method used in the encrypted TLS tunnel. In this example, EAP with MD5-Challenge is used. The “inner authentication” phase is often called “phase2”. |
Next, add the following lines to
/etc/rc.conf
:
wlans_ath0="wlan0" ifconfig_wlan0="WPA DHCP"
The next step is to bring up the interface:
#
service netif start
Starting wpa_supplicant. DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 7 DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 15 DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 21 DHCPACK from 192.168.0.20 bound to 192.168.0.254 -- renewal in 300 seconds. wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 ether 00:11:95:d5:43:62 inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255 media: IEEE 802.11 Wireless Ethernet DS/11Mbps mode 11g status: associated ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS wme burst roaming MANUAL
PEAPv0/EAP-MSCHAPv2 is the most common PEAP method. In this chapter, the term PEAP is used to refer to that method.
Protected EAP (PEAP) is designed as an alternative to EAP-TTLS and is the most used EAP standard after EAP-TLS. In a network with mixed operating systems, PEAP should be the most supported standard after EAP-TLS.
PEAP is similar to EAP-TTLS as it uses a server-side certificate to authenticate clients by creating an encrypted TLS tunnel between the client and the authentication server, which protects the ensuing exchange of authentication information. PEAP authentication differs from EAP-TTLS as it broadcasts the username in the clear and only the password is sent in the encrypted TLS tunnel. EAP-TTLS will use the TLS tunnel for both the username and password.
Add the following lines to
/etc/wpa_supplicant.conf
to
configure the EAP-PEAP related
settings:
network={ ssid="freebsdap" proto=RSN key_mgmt=WPA-EAP eap=PEAP identity="test" password="test" ca_cert="/etc/certs/cacert.pem" phase1="peaplabel=0" phase2="auth=MSCHAPV2" }
This field specifies the EAP method for the connection. | |
The | |
The | |
The | |
This field contains the parameters for the
first phase of authentication, the
TLS tunnel. According to the
authentication server used, specify a specific
label for authentication. Most of the time, the
label will be “client EAP
encryption” which is set by using
| |
This field specifies the authentication
protocol used in the encrypted
TLS tunnel. In the
case of PEAP, it is
|
Add the following to
/etc/rc.conf
:
wlans_ath0="wlan0" ifconfig_wlan0="WPA DHCP"
Then, bring up the interface:
#
service netif start
Starting wpa_supplicant. DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 7 DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 15 DHCPREQUEST on wlan0 to 255.255.255.255 port 67 interval 21 DHCPACK from 192.168.0.20 bound to 192.168.0.254 -- renewal in 300 seconds. wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500 ether 00:11:95:d5:43:62 inet 192.168.0.254 netmask 0xffffff00 broadcast 192.168.0.255 media: IEEE 802.11 Wireless Ethernet DS/11Mbps mode 11g status: associated ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac country US ecm authmode WPA2/802.11i privacy ON deftxkey UNDEF AES-CCM 3:128-bit txpower 21.5 bmiss 7 scanvalid 450 bgscan bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS wme burst roaming MANUAL
Wired Equivalent Privacy (WEP) is part of the original 802.11 standard. There is no authentication mechanism, only a weak form of access control which is easily cracked.
WEP can be set up using ifconfig(8):
#
ifconfig
wlan0
create wlandevath0
#
ifconfig
wlan0
inet192.168.1.100
netmask255.255.255.0
\ ssidmy_net
wepmode on weptxkey3
wepkey3:0x3456789012
The weptxkey
specifies which
WEP key will be used in the
transmission. This example uses the third key.
This must match the setting on the access point.
When unsure which key is used by the access point,
try 1
(the first key) for this
value.
The wepkey
selects one of the
WEP keys. It should be in the
format index:key
. Key
1
is used by default; the index
only needs to be set when using a key other than the
first key.
Replace the 0x3456789012
with the key configured for use on the access
point.
Refer to ifconfig(8) for further information.
The wpa_supplicant(8) facility can be used to
configure a wireless interface with
WEP. The example above can be set up
by adding the following lines to
/etc/wpa_supplicant.conf
:
network={ ssid="my_net" key_mgmt=NONE wep_key3=3456789012 wep_tx_keyidx=3 }
Then:
#
wpa_supplicant -i
Trying to associate with 00:13:46:49:41:76 (SSID='dlinkap' freq=2437 MHz) Associated with 00:13:46:49:41:76wlan0
-c /etc/wpa_supplicant.conf
IBSS mode, also called ad-hoc mode, is
designed for point to point connections. For example, to
establish an ad-hoc network between the machines
A
and B
,
choose two IP addresses and a
SSID.
On A
:
#
ifconfig
wlan0
create wlandevath0
wlanmode adhoc#
ifconfig
wlan0
inet192.168.0.1
netmask255.255.255.0
ssidfreebsdap
#
ifconfig
wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 ether 00:11:95:c3:0d:ac inet 192.168.0.1 netmask 0xffffff00 broadcast 192.168.0.255 media: IEEE 802.11 Wireless Ethernet autoselect mode 11g <adhoc> status: running ssid freebsdap channel 2 (2417 Mhz 11g) bssid 02:11:95:c3:0d:ac country US ecm authmode OPEN privacy OFF txpower 21.5 scanvalid 60 protmode CTS wme burstwlan0
The adhoc
parameter indicates that the
interface is running in IBSS mode.
B
should now be able to detect
A
:
#
ifconfig
wlan0
create wlandevath0
wlanmode adhoc#
ifconfig
SSID/MESH ID BSSID CHAN RATE S:N INT CAPS freebsdap 02:11:95:c3:0d:ac 2 54M -64:-96 100 IS WMEwlan0
up scan
The I
in the output confirms that
A
is in ad-hoc mode. Now, configure
B
with a different
IP address:
#
ifconfig
wlan0
inet192.168.0.2
netmask255.255.255.0
ssidfreebsdap
#
ifconfig
wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 ether 00:11:95:d5:43:62 inet 192.168.0.2 netmask 0xffffff00 broadcast 192.168.0.255 media: IEEE 802.11 Wireless Ethernet autoselect mode 11g <adhoc> status: running ssid freebsdap channel 2 (2417 Mhz 11g) bssid 02:11:95:c3:0d:ac country US ecm authmode OPEN privacy OFF txpower 21.5 scanvalid 60 protmode CTS wme burstwlan0
Both A
and
B
are now ready to exchange
information.
FreeBSD can act as an Access Point (AP) which eliminates the need to buy a hardware AP or run an ad-hoc network. This can be particularly useful when a FreeBSD machine is acting as a gateway to another network such as the Internet.
Before configuring a FreeBSD machine as an AP, the kernel must be configured with the appropriate networking support for the wireless card as well as the security protocols being used. For more details, see Section 31.3.3, “Basic Setup”.
The NDIS driver wrapper for Windows® drivers does not currently support AP operation. Only native FreeBSD wireless drivers support AP mode.
Once wireless networking support is loaded, check if the wireless device supports the host-based access point mode, also known as hostap mode:
#
ifconfig
wlan0
create wlandevath0
#
ifconfig
drivercaps=6f85edc1<STA,FF,TURBOP,IBSS,HOSTAP,AHDEMO,TXPMGT,SHSLOT,SHPREAMBLE,MONITOR,MBSS,WPA1,WPA2,BURST,WME,WDS,BGSCAN,TXFRAG> cryptocaps=1f<WEP,TKIP,AES,AES_CCM,TKIPMIC>wlan0
list caps
This output displays the card's capabilities. The
HOSTAP
word confirms that this wireless
card can act as an AP. Various supported
ciphers are also listed: WEP,
TKIP, and AES. This
information indicates which security protocols can be used
on the AP.
The wireless device can only be put into hostap mode during the creation of the network pseudo-device, so a previously created device must be destroyed first:
#
ifconfig
wlan0
destroy
then regenerated with the correct option before setting the other parameters:
#
ifconfig
wlan0
create wlandevath0
wlanmode hostap#
ifconfig
wlan0
inet192.168.0.1
netmask255.255.255.0
ssidfreebsdap
mode 11g channel 1
Use ifconfig(8) again to see the status of the
wlan0
interface:
#
ifconfig
wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 ether 00:11:95:c3:0d:ac inet 192.168.0.1 netmask 0xffffff00 broadcast 192.168.0.255 media: IEEE 802.11 Wireless Ethernet autoselect mode 11g <hostap> status: running ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac country US ecm authmode OPEN privacy OFF txpower 21.5 scanvalid 60 protmode CTS wme burst dtimperiod 1 -dfswlan0
The hostap
parameter indicates the
interface is running in the host-based access point
mode.
The interface configuration can be done automatically at
boot time by adding the following lines to
/etc/rc.conf
:
wlans_ath0="wlan0" create_args_wlan0="wlanmode hostap" ifconfig_wlan0="inet192.168.0.1
netmask255.255.255.0
ssidfreebsdap
mode 11g channel1
"
Although it is not recommended to run an AP without any authentication or encryption, this is a simple way to check if the AP is working. This configuration is also important for debugging client issues.
Once the AP is configured, initiate a scan from another wireless machine to find the AP:
#
ifconfig
wlan0
create wlandevath0
#
ifconfig
SSID/MESH ID BSSID CHAN RATE S:N INT CAPS freebsdap 00:11:95:c3:0d:ac 1 54M -66:-96 100 ES WMEwlan0
up scan
The client machine found the AP and can be associated with it:
#
ifconfig
wlan0
inet192.168.0.2
netmask255.255.255.0
ssidfreebsdap
#
ifconfig
wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 ether 00:11:95:d5:43:62 inet 192.168.0.2 netmask 0xffffff00 broadcast 192.168.0.255 media: IEEE 802.11 Wireless Ethernet OFDM/54Mbps mode 11g status: associated ssid freebsdap channel 1 (2412 Mhz 11g) bssid 00:11:95:c3:0d:ac country US ecm authmode OPEN privacy OFF txpower 21.5 bmiss 7 scanvalid 60 bgscan bgscanintvl 300 bgscanidle 250 roam:rssi 7 roam:rate 5 protmode CTS wme burstwlan0
This section focuses on setting up a FreeBSD access point using the WPA2 security protocol. More details regarding WPA and the configuration of WPA-based wireless clients can be found in Section 31.3.4.1.3, “WPA”.
The hostapd(8) daemon is used to deal with client authentication and key management on the WPA2-enabled AP.
The following configuration operations are performed
on the FreeBSD machine acting as the AP.
Once the AP is correctly working,
hostapd(8) can be automatically started at boot
with this line in
/etc/rc.conf
:
hostapd_enable="YES"
Before trying to configure hostapd(8), first configure the basic settings introduced in Section 31.3.6.1, “Basic Settings”.
WPA2-PSK is intended for small networks where the use of a backend authentication server is not possible or desired.
The configuration is done in
/etc/hostapd.conf
:
interface=wlan0 debug=1 ctrl_interface=/var/run/hostapd ctrl_interface_group=wheel ssid=freebsdap wpa=2 wpa_passphrase=freebsdmall wpa_key_mgmt=WPA-PSK wpa_pairwise=CCMP
Wireless interface used for the access point. | |
Level of verbosity used during the
execution of hostapd(8). A value of
| |
Pathname of the directory used by hostapd(8) to store domain socket files for communication with external programs such as hostapd_cli(8). The default value is used in this example. | |
The group allowed to access the control interface files. | |
The wireless network name, or SSID, that will appear in wireless scans. | |
Enable
WPA and specify which
WPA authentication protocol will
be required. A value of | |
ASCII passphrase for WPA authentication. Warning:Always use strong passwords that are at least 8 characters long and made from a rich alphabet so that they will not be easily guessed or attacked. | |
The key management protocol to use. This example sets WPA-PSK. | |
Encryption algorithms accepted by the access point. In this example, only the CCMP (AES) cipher is accepted. CCMP is an alternative to TKIP and is strongly preferred when possible. TKIP should be allowed only when there are stations incapable of using CCMP. |
The next step is to start hostapd(8):
#
service hostapd forcestart
#
ifconfig
wlan0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> metric 0 mtu 1500 ether 04:f0:21:16:8e:10 inet6 fe80::6f0:21ff:fe16:8e10%wlan0 prefixlen 64 scopeid 0x9 nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL> media: IEEE 802.11 Wireless Ethernet autoselect mode 11na <hostap> status: running ssid No5ignal channel 36 (5180 MHz 11a ht/40+) bssid 04:f0:21:16:8e:10 country US ecm authmode WPA2/802.11i privacy MIXED deftxkey 2 AES-CCM 2:128-bit AES-CCM 3:128-bit txpower 17 mcastrate 6 mgmtrate 6 scanvalid 60 ampdulimit 64k ampdudensity 8 shortgi wme burst dtimperiod 1 -dfs groups: wlanwlan0
Once the AP is running, the
clients can associate with it. See Section 31.3.4.1.3, “WPA” for more details. It
is possible to see the stations associated with the
AP using ifconfig
.wlan0
list
sta
It is not recommended to use WEP for setting up an AP since there is no authentication mechanism and the encryption is easily cracked. Some legacy wireless cards only support WEP and these cards will only support an AP without authentication or encryption.
The wireless device can now be put into hostap mode and configured with the correct SSID and IP address:
#
ifconfig
wlan0
create wlandevath0
wlanmode hostap#
ifconfig
wlan0
inet192.168.0.1
netmask255.255.255.0
\ ssidfreebsdap
wepmode on weptxkey3
wepkey3:0x3456789012
mode 11g
The weptxkey
indicates which
WEP key will be used in the
transmission. This example uses the third key as key
numbering starts with 1
. This
parameter must be specified in order to encrypt the
data.
The wepkey
sets the selected
WEP key. It should be in the format
index:key
. If the index is
not given, key 1
is set. The index
needs to be set when using keys other than the first
key.
Use ifconfig(8) to see the status of the
wlan0
interface:
#
ifconfig
wlan0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 ether 00:11:95:c3:0d:ac inet 192.168.0.1 netmask 0xffffff00 broadcast 192.168.0.255 media: IEEE 802.11 Wireless Ethernet autoselect mode 11g <hostap> status: running ssid freebsdap channel 4 (2427 Mhz 11g) bssid 00:11:95:c3:0d:ac country US ecm authmode OPEN privacy ON deftxkey 3 wepkey 3:40-bit txpower 21.5 scanvalid 60 protmode CTS wme burst dtimperiod 1 -dfswlan0
From another wireless machine, it is now possible to initiate a scan to find the AP:
#
ifconfig
wlan0
create wlandevath0
#
ifconfig
SSID BSSID CHAN RATE S:N INT CAPS freebsdap 00:11:95:c3:0d:ac 1 54M 22:1 100 EPSwlan0
up scan
In this example, the client machine found the AP and can associate with it using the correct parameters. See Section 31.3.4.1.4, “WEP” for more details.
A wired connection provides better performance and reliability, while a wireless connection provides flexibility and mobility. Laptop users typically want to roam seamlessly between the two types of connections.
On FreeBSD, it is possible to combine two or even more network interfaces together in a “failover” fashion. This type of configuration uses the most preferred and available connection from a group of network interfaces, and the operating system switches automatically when the link state changes.
Link aggregation and failover is covered in Section 31.7, “Link Aggregation and Failover” and an example for using both wired and wireless connections is provided at Example 31.3, “Failover Mode Between Ethernet and Wireless Interfaces”.
This section describes a number of steps to help troubleshoot common wireless networking problems.
If the access point is not listed when scanning, check that the configuration has not limited the wireless device to a limited set of channels.
If the device cannot associate with an access point, verify that the configuration matches the settings on the access point. This includes the authentication scheme and any security protocols. Simplify the configuration as much as possible. If using a security protocol such as WPA or WEP, configure the access point for open authentication and no security to see if traffic will pass.
Debugging support is provided by
wpa_supplicant(8). Try running this utility manually
with -dd
and look at the
system logs.
Once the system can associate with the access point, diagnose the network configuration using tools like ping(8).
There are many lower-level debugging tools. Debugging messages can be enabled in the 802.11 protocol support layer using wlandebug(8). For example, to enable console messages related to scanning for access points and the 802.11 protocol handshakes required to arrange communication:
#
wlandebug -i
net.wlan.0.debug: 0 => 0xc80000<assoc,auth,scan>wlan0
+scan+auth+debug+assoc
Many useful statistics are maintained by the 802.11
layer and wlanstats
, found in /usr/src/tools/tools/net80211
,
will dump this information. These statistics should
display all errors identified by the 802.11 layer.
However, some errors are identified in the device drivers
that lie below the 802.11 layer so they may not show up.
To diagnose device-specific problems, refer to the
drivers' documentation.
If the above information does not help to clarify the problem, submit a problem report and include output from the above tools.
Many cellphones provide the option to share their data connection over USB (often called "tethering"). This feature uses either the RNDIS, CDC or a custom Apple® iPhone®/iPad® protocol.
Before attaching a device, load the appropriate driver into the kernel:
#
kldload if_urndis
#
kldload if_cdce#
kldload if_ipheth
Once the device is attached
ue
0
will be
available for use like a normal network device. Be sure that
the “USB tethering” option is enabled on the
device.
Bluetooth is a wireless technology for creating personal networks operating in the 2.4 GHz unlicensed band, with a range of 10 meters. Networks are usually formed ad-hoc from portable devices such as cellular phones, handhelds, and laptops. Unlike Wi-Fi wireless technology, Bluetooth offers higher level service profiles, such as FTP-like file servers, file pushing, voice transport, serial line emulation, and more.
This section describes the use of a USB Bluetooth dongle on a FreeBSD system. It then describes the various Bluetooth protocols and utilities.
The Bluetooth stack in FreeBSD is implemented using the netgraph(4) framework. A broad variety of Bluetooth USB dongles is supported by ng_ubt(4). Broadcom BCM2033 based Bluetooth devices are supported by the ubtbcmfw(4) and ng_ubt(4) drivers. The 3Com Bluetooth PC Card 3CRWB60-A is supported by the ng_bt3c(4) driver. Serial and UART based Bluetooth devices are supported by sio(4), ng_h4(4), and hcseriald(8).
Before attaching a device, determine which of the above drivers it uses, then load the driver. For example, if the device uses the ng_ubt(4) driver:
#
kldload ng_ubt
If the Bluetooth device will be attached to the system
during system startup, the system can be configured to load
the module at boot time by adding the driver to
/boot/loader.conf
:
ng_ubt_load="YES"
Once the driver is loaded, plug in the
USB dongle. If the driver load was
successful, output similar to the following should appear on
the console and in
/var/log/messages
:
ubt0: vendor 0x0a12 product 0x0001, rev 1.10/5.25, addr 2 ubt0: Interface 0 endpoints: interrupt=0x81, bulk-in=0x82, bulk-out=0x2 ubt0: Interface 1 (alt.config 5) endpoints: isoc-in=0x83, isoc-out=0x3, wMaxPacketSize=49, nframes=6, buffer size=294
To start and stop the Bluetooth stack, use its startup script. It is a good idea to stop the stack before unplugging the device. Starting the bluetooth stack might require hcsecd(8) to be started. When starting the stack, the output should be similar to the following:
#
service bluetooth start ubt0
BD_ADDR: 00:02:72:00:d4:1a Features: 0xff 0xff 0xf 00 00 00 00 00 <3-Slot> <5-Slot> <Encryption> <Slot offset> <Timing accuracy> <Switch> <Hold mode> <Sniff mode> <Park mode> <RSSI> <Channel quality> <SCO link> <HV2 packets> <HV3 packets> <u-law log> <A-law log> <CVSD> <Paging scheme> <Power control> <Transparent SCO data> Max. ACL packet size: 192 bytes Number of ACL packets: 8 Max. SCO packet size: 64 bytes Number of SCO packets: 8
The Host Controller Interface (HCI) provides a uniform method for accessing Bluetooth baseband capabilities. In FreeBSD, a netgraph HCI node is created for each Bluetooth device. For more details, refer to ng_hci(4).
One of the most common tasks is discovery of Bluetooth devices within RF proximity. This operation is called inquiry. Inquiry and other HCI related operations are done using hccontrol(8). The example below shows how to find out which Bluetooth devices are in range. The list of devices should be displayed in a few seconds. Note that a remote device will only answer the inquiry if it is set to discoverable mode.
%
hccontrol -n ubt0hci inquiry
Inquiry result, num_responses=1 Inquiry result #0 BD_ADDR: 00:80:37:29:19:a4 Page Scan Rep. Mode: 0x1 Page Scan Period Mode: 00 Page Scan Mode: 00 Class: 52:02:04 Clock offset: 0x78ef Inquiry complete. Status: No error [00]
The BD_ADDR
is the unique address of a
Bluetooth device, similar to the MAC
address of a network card. This address is needed for further
communication with a device and it is possible to assign a
human readable name to a BD_ADDR
.
Information regarding the known Bluetooth hosts is contained
in /etc/bluetooth/hosts
. The following
example shows how to obtain the human readable name that was
assigned to the remote device:
%
hccontrol -n ubt0hci remote_name_request 00:80:37:29:19:a4
BD_ADDR: 00:80:37:29:19:a4 Name: Pav's T39
If an inquiry is performed on a remote Bluetooth device, it will find the computer as “your.host.name (ubt0)”. The name assigned to the local device can be changed at any time.
Remote devices can be assigned aliases in
/etc/bluetooth/hosts
. More information
about /etc/bluetooth/hosts
file might be
found in bluetooth.hosts(5).
The Bluetooth system provides a point-to-point connection between two Bluetooth units, or a point-to-multipoint connection which is shared among several Bluetooth devices. The following example shows how to create a connection to a remote device:
%
hccontrol -n ubt0hci create_connection
BT_ADDR
create_connection
accepts
BT_ADDR
as well as host aliases in
/etc/bluetooth/hosts
.
The following example shows how to obtain the list of active baseband connections for the local device:
%
hccontrol -n ubt0hci read_connection_list
Remote BD_ADDR Handle Type Mode Role Encrypt Pending Queue State 00:80:37:29:19:a4 41 ACL 0 MAST NONE 0 0 OPEN
A connection handle is useful when termination of the baseband connection is required, though it is normally not required to do this by hand. The stack will automatically terminate inactive baseband connections.
#
hccontrol -n ubt0hci disconnect 41
Connection handle: 41 Reason: Connection terminated by local host [0x16]
Type hccontrol help
for a complete
listing of available HCI commands. Most
of the HCI commands do not require
superuser privileges.
By default, Bluetooth communication is not authenticated, and any device can talk to any other device. A Bluetooth device, such as a cellular phone, may choose to require authentication to provide a particular service. Bluetooth authentication is normally done with a PIN code, an ASCII string up to 16 characters in length. The user is required to enter the same PIN code on both devices. Once the user has entered the PIN code, both devices will generate a link key. After that, the link key can be stored either in the devices or in a persistent storage. Next time, both devices will use the previously generated link key. This procedure is called pairing. Note that if the link key is lost by either device, the pairing must be repeated.
The hcsecd(8) daemon is responsible for handling
Bluetooth authentication requests. The default configuration
file is /etc/bluetooth/hcsecd.conf
. An
example section for a cellular phone with the
PIN code set to 1234
is
shown below:
device { bdaddr 00:80:37:29:19:a4; name "Pav's T39"; key nokey; pin "1234"; }
The only limitation on PIN codes is
length. Some devices, such as Bluetooth headsets, may have
a fixed PIN code built in. The
-d
switch forces hcsecd(8) to stay in
the foreground, so it is easy to see what is happening. Set
the remote device to receive pairing and initiate the
Bluetooth connection to the remote device. The remote device
should indicate that pairing was accepted and request the
PIN code. Enter the same
PIN code listed in
hcsecd.conf
. Now the computer and the
remote device are paired. Alternatively, pairing can be
initiated on the remote device.
The following line can be added to
/etc/rc.conf
to configure hcsecd(8)
to start automatically on system start:
hcsecd_enable="YES"
The following is a sample of the hcsecd(8) daemon output:
hcsecd[16484]: Got Link_Key_Request event from 'ubt0hci', remote bdaddr 0:80:37:29:19:a4 hcsecd[16484]: Found matching entry, remote bdaddr 0:80:37:29:19:a4, name 'Pav's T39', link key doesn't exist hcsecd[16484]: Sending Link_Key_Negative_Reply to 'ubt0hci' for remote bdaddr 0:80:37:29:19:a4 hcsecd[16484]: Got PIN_Code_Request event from 'ubt0hci', remote bdaddr 0:80:37:29:19:a4 hcsecd[16484]: Found matching entry, remote bdaddr 0:80:37:29:19:a4, name 'Pav's T39', PIN code exists hcsecd[16484]: Sending PIN_Code_Reply to 'ubt0hci' for remote bdaddr 0:80:37:29:19:a4
A Dial-Up Networking (DUN) profile can be used to configure a cellular phone as a wireless modem for connecting to a dial-up Internet access server. It can also be used to configure a computer to receive data calls from a cellular phone.
Network access with a PPP profile can be used to provide LAN access for a single Bluetooth device or multiple Bluetooth devices. It can also provide PC to PC connection using PPP networking over serial cable emulation.
In FreeBSD, these profiles are implemented with ppp(8)
and the rfcomm_pppd(8) wrapper which converts a
Bluetooth connection into something
PPP can use. Before a profile can be used,
a new PPP label must be created in
/etc/ppp/ppp.conf
. Consult
rfcomm_pppd(8) for examples.
In this example, rfcomm_pppd(8) is used to open a
connection to a remote device with a
BD_ADDR
of
00:80:37:29:19:a4
on a
DUN RFCOMM
channel:
#
rfcomm_pppd -a 00:80:37:29:19:a4 -c -C dun -l rfcomm-dialup
The actual channel number will be obtained from the remote device using the SDP protocol. It is possible to specify the RFCOMM channel by hand, and in this case rfcomm_pppd(8) will not perform the SDP query. Use sdpcontrol(8) to find out the RFCOMM channel on the remote device.
In order to provide network access with the
PPP LAN service,
sdpd(8) must be running and a new entry for
LAN clients must be created in
/etc/ppp/ppp.conf
. Consult
rfcomm_pppd(8) for examples. Finally, start the
RFCOMM PPP server on a
valid RFCOMM channel number. The
RFCOMM PPP server will
automatically register the Bluetooth LAN
service with the local SDP daemon. The
example below shows how to start the RFCOMM
PPP server.
#
rfcomm_pppd -s -C 7 -l rfcomm-server
This section provides an overview of the various Bluetooth protocols, their function, and associated utilities.
The Logical Link Control and Adaptation Protocol (L2CAP) provides connection-oriented and connectionless data services to upper layer protocols. L2CAP permits higher level protocols and applications to transmit and receive L2CAP data packets up to 64 kilobytes in length.
L2CAP is based around the concept of channels. A channel is a logical connection on top of a baseband connection, where each channel is bound to a single protocol in a many-to-one fashion. Multiple channels can be bound to the same protocol, but a channel cannot be bound to multiple protocols. Each L2CAP packet received on a channel is directed to the appropriate higher level protocol. Multiple channels can share the same baseband connection.
In FreeBSD, a netgraph L2CAP node is created for each Bluetooth device. This node is normally connected to the downstream Bluetooth HCI node and upstream Bluetooth socket nodes. The default name for the L2CAP node is “devicel2cap”. For more details refer to ng_l2cap(4).
A useful command is l2ping(8), which can be used to
ping other devices. Some Bluetooth implementations might
not return all of the data sent to them, so 0
bytes
in the following example is normal.
#
l2ping -a 00:80:37:29:19:a4
0 bytes from 0:80:37:29:19:a4 seq_no=0 time=48.633 ms result=0 0 bytes from 0:80:37:29:19:a4 seq_no=1 time=37.551 ms result=0 0 bytes from 0:80:37:29:19:a4 seq_no=2 time=28.324 ms result=0 0 bytes from 0:80:37:29:19:a4 seq_no=3 time=46.150 ms result=0
The l2control(8) utility is used to perform various operations on L2CAP nodes. This example shows how to obtain the list of logical connections (channels) and the list of baseband connections for the local device:
%
l2control -a 00:02:72:00:d4:1a read_channel_list
L2CAP channels: Remote BD_ADDR SCID/ DCID PSM IMTU/ OMTU State 00:07:e0:00:0b:ca 66/ 64 3 132/ 672 OPEN%
l2control -a 00:02:72:00:d4:1a read_connection_list
L2CAP connections: Remote BD_ADDR Handle Flags Pending State 00:07:e0:00:0b:ca 41 O 0 OPEN
Another diagnostic tool is btsockstat(1). It is similar to netstat(1), but for Bluetooth network-related data structures. The example below shows the same logical connection as l2control(8) above.
%
btsockstat
Active L2CAP sockets PCB Recv-Q Send-Q Local address/PSM Foreign address CID State c2afe900 0 0 00:02:72:00:d4:1a/3 00:07:e0:00:0b:ca 66 OPEN Active RFCOMM sessions L2PCB PCB Flag MTU Out-Q DLCs State c2afe900 c2b53380 1 127 0 Yes OPEN Active RFCOMM sockets PCB Recv-Q Send-Q Local address Foreign address Chan DLCI State c2e8bc80 0 250 00:02:72:00:d4:1a 00:07:e0:00:0b:ca 3 6 OPEN
The RFCOMM protocol provides emulation of serial ports over the L2CAP protocol. RFCOMM is a simple transport protocol, with additional provisions for emulating the 9 circuits of RS-232 (EIATIA-232-E) serial ports. It supports up to 60 simultaneous connections (RFCOMM channels) between two Bluetooth devices.
For the purposes of RFCOMM, a complete communication path involves two applications running on the communication endpoints with a communication segment between them. RFCOMM is intended to cover applications that make use of the serial ports of the devices in which they reside. The communication segment is a direct connect Bluetooth link from one device to another.
RFCOMM is only concerned with the connection between the devices in the direct connect case, or between the device and a modem in the network case. RFCOMM can support other configurations, such as modules that communicate via Bluetooth wireless technology on one side and provide a wired interface on the other side.
In FreeBSD, RFCOMM is implemented at the Bluetooth sockets layer.
The Service Discovery Protocol (SDP) provides the means for client applications to discover the existence of services provided by server applications as well as the attributes of those services. The attributes of a service include the type or class of service offered and the mechanism or protocol information needed to utilize the service.
SDP involves communication between a SDP server and a SDP client. The server maintains a list of service records that describe the characteristics of services associated with the server. Each service record contains information about a single service. A client may retrieve information from a service record maintained by the SDP server by issuing a SDP request. If the client, or an application associated with the client, decides to use a service, it must open a separate connection to the service provider in order to utilize the service. SDP provides a mechanism for discovering services and their attributes, but it does not provide a mechanism for utilizing those services.
Normally, a SDP client searches for services based on some desired characteristics of the services. However, there are times when it is desirable to discover which types of services are described by an SDP server's service records without any prior information about the services. This process of looking for any offered services is called browsing.
The Bluetooth SDP server, sdpd(8), and command line client, sdpcontrol(8), are included in the standard FreeBSD installation. The following example shows how to perform a SDP browse query.
%
sdpcontrol -a 00:01:03:fc:6e:ec browse
Record Handle: 00000000 Service Class ID List: Service Discovery Server (0x1000) Protocol Descriptor List: L2CAP (0x0100) Protocol specific parameter #1: u/int/uuid16 1 Protocol specific parameter #2: u/int/uuid16 1 Record Handle: 0x00000001 Service Class ID List: Browse Group Descriptor (0x1001) Record Handle: 0x00000002 Service Class ID List: LAN Access Using PPP (0x1102) Protocol Descriptor List: L2CAP (0x0100) RFCOMM (0x0003) Protocol specific parameter #1: u/int8/bool 1 Bluetooth Profile Descriptor List: LAN Access Using PPP (0x1102) ver. 1.0
Note that each service has a list of attributes, such as the RFCOMM channel. Depending on the service, the user might need to make note of some of the attributes. Some Bluetooth implementations do not support service browsing and may return an empty list. In this case, it is possible to search for the specific service. The example below shows how to search for the OBEX Object Push (OPUSH) service:
%
sdpcontrol -a 00:01:03:fc:6e:ec search OPUSH
Offering services on FreeBSD to Bluetooth clients is done
with the sdpd(8) server. The following line can be
added to /etc/rc.conf
:
sdpd_enable="YES"
Then the sdpd(8) daemon can be started with:
#
service sdpd start
The local server application that wants to provide a Bluetooth service to remote clients will register the service with the local SDP daemon. An example of such an application is rfcomm_pppd(8). Once started, it will register the Bluetooth LAN service with the local SDP daemon.
The list of services registered with the local SDP server can be obtained by issuing a SDP browse query via the local control channel:
#
sdpcontrol -l browse
Object Exchange (OBEX) is a widely used protocol for simple file transfers between mobile devices. Its main use is in infrared communication, where it is used for generic file transfers between notebooks or PDAs, and for sending business cards or calendar entries between cellular phones and other devices with Personal Information Manager (PIM) applications.
The OBEX server and client are implemented by obexapp, which can be installed using the comms/obexapp package or port.
The OBEX client is used to push
and/or pull objects from the OBEX server.
An example object is a business card or an appointment.
The OBEX client can obtain the
RFCOMM channel number from the remote
device via SDP. This can be done by
specifying the service name instead of the
RFCOMM channel number. Supported service
names are: IrMC
, FTRN
,
and OPUSH
. It is also possible to
specify the RFCOMM channel as a number.
Below is an example of an OBEX session
where the device information object is pulled from the
cellular phone, and a new object, the business card, is
pushed into the phone's directory.
%
obexapp -a 00:80:37:29:19:a4 -C IrMC
obex> get telecom/devinfo.txt devinfo-t39.txt Success, response: OK, Success (0x20) obex> put new.vcf Success, response: OK, Success (0x20) obex> di Success, response: OK, Success (0x20)
In order to provide the OPUSH
service, sdpd(8) must be running and a root folder,
where all incoming objects will be stored, must be created.
The default path to the root folder is
/var/spool/obex
. Finally, start the
OBEX server on a valid
RFCOMM channel number. The
OBEX server will automatically register
the OPUSH service with the local
SDP daemon. The example below shows how
to start the OBEX server.
#
obexapp -s -C 10
The Serial Port Profile (SPP) allows Bluetooth devices to perform serial cable emulation. This profile allows legacy applications to use Bluetooth as a cable replacement, through a virtual serial port abstraction.
In FreeBSD, rfcomm_sppd(1) implements SPP and a pseudo tty is used as a virtual serial port abstraction. The example below shows how to connect to a remote device's serial port service. A RFCOMM channel does not have to be specified as rfcomm_sppd(1) can obtain it from the remote device via SDP. To override this, specify a RFCOMM channel on the command line.
#
rfcomm_sppd -a 00:07:E0:00:0B:CA -t
rfcomm_sppd[94692]: Starting on /dev/pts/6... /dev/pts/6
Once connected, the pseudo tty can be used as serial port:
#
cu -l /dev/pts/6
The pseudo tty is printed on stdout and can be read by wrapper scripts:
PTS=`rfcomm_sppd -a 00:07:E0:00:0B:CA -t` cu -l $PTS
By default, when FreeBSD is accepting a new connection, it tries to perform a role switch and become master. Some older Bluetooth devices which do not support role switching will not be able to connect. Since role switching is performed when a new connection is being established, it is not possible to ask the remote device if it supports role switching. However, there is a HCI option to disable role switching on the local side:
#
hccontrol -n ubt0hci write_node_role_switch 0
To display Bluetooth packets, use the third-party package hcidump, which can be installed using the comms/hcidump package or port. This utility is similar to tcpdump(1) and can be used to display the contents of Bluetooth packets on the terminal and to dump the Bluetooth packets to a file.
It is sometimes useful to divide a network, such as an Ethernet segment, into network segments without having to create IP subnets and use a router to connect the segments together. A device that connects two networks together in this fashion is called a “bridge”.
A bridge works by learning the MAC addresses of the devices on each of its network interfaces. It forwards traffic between networks only when the source and destination MAC addresses are on different networks. In many respects, a bridge is like an Ethernet switch with very few ports. A FreeBSD system with multiple network interfaces can be configured to act as a bridge.
Bridging can be useful in the following situations:
The basic operation of a bridge is to join two or more network segments. There are many reasons to use a host-based bridge instead of networking equipment, such as cabling constraints or firewalling. A bridge can also connect a wireless interface running in hostap mode to a wired network and act as an access point.
A bridge can be used when firewall functionality is needed without routing or Network Address Translation (NAT).
An example is a small company that is connected via DSL or ISDN to an ISP. There are thirteen public IP addresses from the ISP and ten computers on the network. In this situation, using a router-based firewall is difficult because of subnetting issues. A bridge-based firewall can be configured without any IP addressing issues.
A bridge can join two network segments in order to inspect all Ethernet frames that pass between them using bpf(4) and tcpdump(1) on the bridge interface or by sending a copy of all frames out an additional interface known as a span port.
Two Ethernet networks can be joined across an IP link by bridging the networks to an EtherIP tunnel or a tap(4) based solution such as OpenVPN.
A network can be connected together with multiple links and use the Spanning Tree Protocol (STP) to block redundant paths.
This section describes how to configure a FreeBSD system as a bridge using if_bridge(4). A netgraph bridging driver is also available, and is described in ng_bridge(4).
Packet filtering can be used with any firewall package that hooks into the pfil(9) framework. The bridge can be used as a traffic shaper with altq(4) or dummynet(4).
In FreeBSD, if_bridge(4) is a kernel module which is
automatically loaded by ifconfig(8) when creating a
bridge interface. It is also possible to compile bridge
support into a custom kernel by adding
device if_bridge
to the custom kernel
configuration file.
The bridge is created using interface cloning. To create the bridge interface:
#
ifconfig bridge create
bridge0#
ifconfig bridge0
bridge0: flags=8802<BROADCAST,SIMPLEX,MULTICAST> metric 0 mtu 1500 ether 96:3d:4b:f1:79:7a id 00:00:00:00:00:00 priority 32768 hellotime 2 fwddelay 15 maxage 20 holdcnt 6 proto rstp maxaddr 100 timeout 1200 root id 00:00:00:00:00:00 priority 0 ifcost 0 port 0
When a bridge interface is created, it is automatically
assigned a randomly generated Ethernet address. The
maxaddr
and timeout
parameters control how many MAC addresses
the bridge will keep in its forwarding table and how many
seconds before each entry is removed after it is last seen.
The other parameters control how STP
operates.
Next, specify which network interfaces to add as members of the bridge. For the bridge to forward packets, all member interfaces and the bridge need to be up:
#
ifconfig bridge0 addm fxp0 addm fxp1 up
#
ifconfig fxp0 up
#
ifconfig fxp1 up
The bridge can now forward Ethernet frames between
fxp0
and fxp1
. Add
the following lines to /etc/rc.conf
so
the bridge is created at startup:
cloned_interfaces="bridge0" ifconfig_bridge0="addm fxp0 addm fxp1 up" ifconfig_fxp0="up" ifconfig_fxp1="up"
If the bridge host needs an IP address, set it on the bridge interface, not on the member interfaces. The address can be set statically or via DHCP. This example sets a static IP address:
#
ifconfig bridge0 inet 192.168.0.1/24
It is also possible to assign an IPv6
address to a bridge interface. To make the changes permanent,
add the addressing information to
/etc/rc.conf
.
When packet filtering is enabled, bridged packets will pass through the filter inbound on the originating interface on the bridge interface, and outbound on the appropriate interfaces. Either stage can be disabled. When direction of the packet flow is important, it is best to firewall on the member interfaces rather than the bridge itself.
The bridge has several configurable settings for passing non-IP and IP packets, and layer2 firewalling with ipfw(8). See if_bridge(4) for more information.
For an Ethernet network to function properly, only one active path can exist between two devices. The STP protocol detects loops and puts redundant links into a blocked state. Should one of the active links fail, STP calculates a different tree and enables one of the blocked paths to restore connectivity to all points in the network.
The Rapid Spanning Tree Protocol (RSTP or 802.1w) provides backwards compatibility with legacy STP. RSTP provides faster convergence and exchanges information with neighboring switches to quickly transition to forwarding mode without creating loops. FreeBSD supports RSTP and STP as operating modes, with RSTP being the default mode.
STP can be enabled on member interfaces
using ifconfig(8). For a bridge with
fxp0
and fxp1
as the
current interfaces, enable STP with:
#
ifconfig bridge0 stp fxp0 stp fxp1
bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 ether d6:cf:d5:a0:94:6d id 00:01:02:4b:d4:50 priority 32768 hellotime 2 fwddelay 15 maxage 20 holdcnt 6 proto rstp maxaddr 100 timeout 1200 root id 00:01:02:4b:d4:50 priority 32768 ifcost 0 port 0 member: fxp0 flags=1c7<LEARNING,DISCOVER,STP,AUTOEDGE,PTP,AUTOPTP> port 3 priority 128 path cost 200000 proto rstp role designated state forwarding member: fxp1 flags=1c7<LEARNING,DISCOVER,STP,AUTOEDGE,PTP,AUTOPTP> port 4 priority 128 path cost 200000 proto rstp role designated state forwarding
This bridge has a spanning tree ID of
00:01:02:4b:d4:50
and a priority of
32768
. As the root id
is the same, it indicates that this is the root bridge for the
tree.
Another bridge on the network also has STP enabled:
bridge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 ether 96:3d:4b:f1:79:7a id 00:13:d4:9a:06:7a priority 32768 hellotime 2 fwddelay 15 maxage 20 holdcnt 6 proto rstp maxaddr 100 timeout 1200 root id 00:01:02:4b:d4:50 priority 32768 ifcost 400000 port 4 member: fxp0 flags=1c7<LEARNING,DISCOVER,STP,AUTOEDGE,PTP,AUTOPTP> port 4 priority 128 path cost 200000 proto rstp role root state forwarding member: fxp1 flags=1c7<LEARNING,DISCOVER,STP,AUTOEDGE,PTP,AUTOPTP> port 5 priority 128 path cost 200000 proto rstp role designated state forwarding
The line root id 00:01:02:4b:d4:50 priority 32768
ifcost 400000 port 4
shows that the root bridge is
00:01:02:4b:d4:50
and has a path cost of
400000
from this bridge. The path to the
root bridge is via port 4
which is
fxp0
.
Several ifconfig
parameters are unique
to bridge interfaces. This section summarizes some common
uses for these parameters. The complete list of available
parameters is described in ifconfig(8).
A private interface does not forward any traffic to any other port that is also designated as a private interface. The traffic is blocked unconditionally so no Ethernet frames will be forwarded, including ARP packets. If traffic needs to be selectively blocked, a firewall should be used instead.
A span port transmits a copy of every Ethernet frame
received by the bridge. The number of span ports
configured on a bridge is unlimited, but if an
interface is designated as a span port, it cannot also
be used as a regular bridge port. This is most useful
for snooping a bridged network passively on another host
connected to one of the span ports of the bridge. For
example, to send a copy of all frames out the interface
named fxp4
:
#
ifconfig bridge0 span fxp4
If a bridge member interface is marked as sticky, dynamically learned address entries are treated as static entries in the forwarding cache. Sticky entries are never aged out of the cache or replaced, even if the address is seen on a different interface. This gives the benefit of static address entries without the need to pre-populate the forwarding table. Clients learned on a particular segment of the bridge cannot roam to another segment.
An example of using sticky addresses is to combine
the bridge with VLANs in order to
isolate customer networks without wasting
IP address space. Consider that
CustomerA
is on vlan100
, CustomerB
is on
vlan101
, and the bridge has the
address 192.168.0.1
:
#
ifconfig bridge0 addm vlan100 sticky vlan100 addm vlan101 sticky vlan101
#
ifconfig bridge0 inet 192.168.0.1/24
In this example, both clients see 192.168.0.1
as their
default gateway. Since the bridge cache is sticky, one
host cannot spoof the MAC address of
the other customer in order to intercept their
traffic.
Any communication between the VLANs can be blocked using a firewall or, as seen in this example, private interfaces:
#
ifconfig bridge0 private vlan100 private vlan101
The customers are completely isolated from each
other and the full /24
address range can be
allocated without subnetting.
The number of unique source MAC addresses behind an interface can be limited. Once the limit is reached, packets with unknown source addresses are dropped until an existing host cache entry expires or is removed.
The following example sets the maximum number of
Ethernet devices for CustomerA
on
vlan100
to 10:
#
ifconfig bridge0 ifmaxaddr vlan100 10
Bridge interfaces also support monitor mode, where the packets are discarded after bpf(4) processing and are not processed or forwarded further. This can be used to multiplex the input of two or more interfaces into a single bpf(4) stream. This is useful for reconstructing the traffic for network taps that transmit the RX/TX signals out through two separate interfaces. For example, to read the input from four network interfaces as one stream:
#
ifconfig bridge0 addm fxp0 addm fxp1 addm fxp2 addm fxp3 monitor up
#
tcpdump -i bridge0
The bridge interface and STP parameters can be monitored via bsnmpd(1) which is included in the FreeBSD base system. The exported bridge MIBs conform to IETF standards so any SNMP client or monitoring package can be used to retrieve the data.
To enable monitoring on the bridge, uncomment this line in
/etc/snmpd.config
by removing the
beginning #
symbol:
begemotSnmpdModulePath."bridge" = "/usr/lib/snmp_bridge.so"
Other configuration settings, such as community names and
access lists, may need to be modified in this file. See
bsnmpd(1) and snmp_bridge(3) for more information.
Once these edits are saved, add this line to
/etc/rc.conf
:
bsnmpd_enable="YES"
Then, start bsnmpd(1):
#
service bsnmpd start
The following examples use the
Net-SNMP software
(net-mgmt/net-snmp) to query a bridge
from a client system. The
net-mgmt/bsnmptools port can also be used.
From the SNMP client which is running
Net-SNMP, add the following lines
to $HOME/.snmp/snmp.conf
in order to
import the bridge MIB definitions:
mibdirs +/usr/share/snmp/mibs mibs +BRIDGE-MIB:RSTP-MIB:BEGEMOT-MIB:BEGEMOT-BRIDGE-MIB
To monitor a single bridge using the IETF BRIDGE-MIB (RFC4188):
%
snmpwalk -v 2c -c public bridge1.example.com mib-2.dot1dBridge
BRIDGE-MIB::dot1dBaseBridgeAddress.0 = STRING: 66:fb:9b:6e:5c:44 BRIDGE-MIB::dot1dBaseNumPorts.0 = INTEGER: 1 ports BRIDGE-MIB::dot1dStpTimeSinceTopologyChange.0 = Timeticks: (189959) 0:31:39.59 centi-seconds BRIDGE-MIB::dot1dStpTopChanges.0 = Counter32: 2 BRIDGE-MIB::dot1dStpDesignatedRoot.0 = Hex-STRING: 80 00 00 01 02 4B D4 50 ... BRIDGE-MIB::dot1dStpPortState.3 = INTEGER: forwarding(5) BRIDGE-MIB::dot1dStpPortEnable.3 = INTEGER: enabled(1) BRIDGE-MIB::dot1dStpPortPathCost.3 = INTEGER: 200000 BRIDGE-MIB::dot1dStpPortDesignatedRoot.3 = Hex-STRING: 80 00 00 01 02 4B D4 50 BRIDGE-MIB::dot1dStpPortDesignatedCost.3 = INTEGER: 0 BRIDGE-MIB::dot1dStpPortDesignatedBridge.3 = Hex-STRING: 80 00 00 01 02 4B D4 50 BRIDGE-MIB::dot1dStpPortDesignatedPort.3 = Hex-STRING: 03 80 BRIDGE-MIB::dot1dStpPortForwardTransitions.3 = Counter32: 1 RSTP-MIB::dot1dStpVersion.0 = INTEGER: rstp(2)
The dot1dStpTopChanges.0
value is two,
indicating that the STP bridge topology has
changed twice. A topology change means that one or more links
in the network have changed or failed and a new tree has been
calculated. The
dot1dStpTimeSinceTopologyChange.0
value
will show when this happened.
To monitor multiple bridge interfaces, the private BEGEMOT-BRIDGE-MIB can be used:
%
snmpwalk -v 2c -c public bridge1.example.com
enterprises.fokus.begemot.begemotBridge BEGEMOT-BRIDGE-MIB::begemotBridgeBaseName."bridge0" = STRING: bridge0 BEGEMOT-BRIDGE-MIB::begemotBridgeBaseName."bridge2" = STRING: bridge2 BEGEMOT-BRIDGE-MIB::begemotBridgeBaseAddress."bridge0" = STRING: e:ce:3b:5a:9e:13 BEGEMOT-BRIDGE-MIB::begemotBridgeBaseAddress."bridge2" = STRING: 12:5e:4d:74:d:fc BEGEMOT-BRIDGE-MIB::begemotBridgeBaseNumPorts."bridge0" = INTEGER: 1 BEGEMOT-BRIDGE-MIB::begemotBridgeBaseNumPorts."bridge2" = INTEGER: 1 ... BEGEMOT-BRIDGE-MIB::begemotBridgeStpTimeSinceTopologyChange."bridge0" = Timeticks: (116927) 0:19:29.27 centi-seconds BEGEMOT-BRIDGE-MIB::begemotBridgeStpTimeSinceTopologyChange."bridge2" = Timeticks: (82773) 0:13:47.73 centi-seconds BEGEMOT-BRIDGE-MIB::begemotBridgeStpTopChanges."bridge0" = Counter32: 1 BEGEMOT-BRIDGE-MIB::begemotBridgeStpTopChanges."bridge2" = Counter32: 1 BEGEMOT-BRIDGE-MIB::begemotBridgeStpDesignatedRoot."bridge0" = Hex-STRING: 80 00 00 40 95 30 5E 31 BEGEMOT-BRIDGE-MIB::begemotBridgeStpDesignatedRoot."bridge2" = Hex-STRING: 80 00 00 50 8B B8 C6 A9
To change the bridge interface being monitored via the
mib-2.dot1dBridge
subtree:
%
snmpset -v 2c -c private bridge1.example.com
BEGEMOT-BRIDGE-MIB::begemotBridgeDefaultBridgeIf.0 s bridge2
FreeBSD provides the lagg(4) interface which can be used to aggregate multiple network interfaces into one virtual interface in order to provide failover and link aggregation. Failover allows traffic to continue to flow as long as at least one aggregated network interface has an established link. Link aggregation works best on switches which support LACP, as this protocol distributes traffic bi-directionally while responding to the failure of individual links.
The aggregation protocols supported by the lagg interface determine which ports are used for outgoing traffic and whether or not a specific port accepts incoming traffic. The following protocols are supported by lagg(4):
This mode sends and receives traffic only through the master port. If the master port becomes unavailable, the next active port is used. The first interface added to the virtual interface is the master port and all subsequently added interfaces are used as failover devices. If failover to a non-master port occurs, the original port becomes master once it becomes available again.
Cisco® Fast EtherChannel® (FEC) is found on older Cisco® switches. It provides a static setup and does not negotiate aggregation with the peer or exchange frames to monitor the link. If the switch supports LACP, that should be used instead.
The IEEE® 802.3ad Link Aggregation Control Protocol (LACP) negotiates a set of aggregable links with the peer into one or more Link Aggregated Groups (LAGs). Each LAG is composed of ports of the same speed, set to full-duplex operation, and traffic is balanced across the ports in the LAG with the greatest total speed. Typically, there is only one LAG which contains all the ports. In the event of changes in physical connectivity, LACP will quickly converge to a new configuration.
LACP balances outgoing traffic across the active ports based on hashed protocol header information and accepts incoming traffic from any active port. The hash includes the Ethernet source and destination address and, if available, the VLAN tag, and the IPv4 or IPv6 source and destination address.
This mode distributes outgoing traffic using a round-robin scheduler through all active ports and accepts incoming traffic from any active port. Since this mode violates Ethernet frame ordering, it should be used with caution.
This section demonstrates how to configure a Cisco® switch and a FreeBSD system for LACP load balancing. It then shows how to configure two Ethernet interfaces in failover mode as well as how to configure failover mode between an Ethernet and a wireless interface.
This example connects two fxp(4) Ethernet interfaces on a FreeBSD machine to the first two Ethernet ports on a Cisco® switch as a single load balanced and fault tolerant link. More interfaces can be added to increase throughput and fault tolerance. Replace the names of the Cisco® ports, Ethernet devices, channel group number, and IP address shown in the example to match the local configuration.
Frame ordering is mandatory on Ethernet links and any traffic between two stations always flows over the same physical link, limiting the maximum speed to that of one interface. The transmit algorithm attempts to use as much information as it can to distinguish different traffic flows and balance the flows across the available interfaces.
On the Cisco® switch, add the
FastEthernet0/1
and
FastEthernet0/2
interfaces to
channel group 1
:
interface
!FastEthernet0/1
channel-group1
mode active channel-protocol lacpinterface
FastEthernet0/2
channel-group1
mode active channel-protocol lacp
On the FreeBSD system, create the lagg(4) interface
using the physical interfaces
fxp0
and
fxp1
and bring the interfaces up
with an IP address of
10.0.0.3/24
:
#
ifconfig
fxp0
up#
ifconfig
fxp1
up#
ifconfig
lagg
create0
#
ifconfig
lagg
up laggproto lacp laggport0
fxp0
laggportfxp1
10.0.0.3/24
Next, verify the status of the virtual interface:
#
ifconfig
lagg0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 options=8<VLAN_MTU> ether 00:05:5d:71:8d:b8 inet 10.0.0.3 netmask 0xffffff00 broadcast 10.0.0.255 media: Ethernet autoselect status: active laggproto lacp laggport: fxp1 flags=1c<ACTIVE,COLLECTING,DISTRIBUTING> laggport: fxp0 flags=1c<ACTIVE,COLLECTING,DISTRIBUTING>lagg
0
Ports
marked as ACTIVE
are part of the
LAG that has been negotiated with the
remote switch. Traffic will be transmitted and received
through these active ports. Add -v
to the
above command to view the LAG
identifiers.
To see the port status on the Cisco® switch:
switch# show lacp neighbor
Flags: S - Device is requesting Slow LACPDUs
F - Device is requesting Fast LACPDUs
A - Device is in Active mode P - Device is in Passive mode
Channel group 1 neighbors
Partner's information:
LACP port Oper Port Port
Port Flags Priority Dev ID Age Key Number State
Fa0/1 SA 32768 0005.5d71.8db8 29s 0x146 0x3 0x3D
Fa0/2 SA 32768 0005.5d71.8db8 29s 0x146 0x4 0x3D
For more detail, type show lacp neighbor
detail
.
To retain this configuration across reboots, add the
following entries to
/etc/rc.conf
on the FreeBSD system:
ifconfig_fxp0
="up" ifconfig_fxp1
="up" cloned_interfaces="lagg
" ifconfig_0
lagg
="laggproto lacp laggport0
fxp0
laggportfxp1
10.0.0.3/24
"
Failover mode can be used to switch over to a secondary
interface if the link is lost on the master interface. To
configure failover, make sure that the underlying physical
interfaces are up, then create the lagg(4) interface.
In this example, fxp0
is the
master interface, fxp1
is the
secondary interface, and the virtual interface is assigned
an IP address of
10.0.0.15/24
:
#
ifconfig
fxp0
up#
ifconfig
fxp1
up#
ifconfig
lagg
create0
#
ifconfig
lagg
up laggproto failover laggport0
fxp0
laggportfxp1
10.0.0.15/24
The virtual interface should look something like this:
#
ifconfig
lagg0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 options=8<VLAN_MTU> ether 00:05:5d:71:8d:b8 inet 10.0.0.15 netmask 0xffffff00 broadcast 10.0.0.255 media: Ethernet autoselect status: active laggproto failover laggport: fxp1 flags=0<> laggport: fxp0 flags=5<MASTER,ACTIVE>lagg
0
Traffic will be transmitted and received on
fxp0
. If the link is lost on
fxp0
,
fxp1
will become the active link.
If the link is restored on the master interface, it will
once again become the active link.
To retain this configuration across reboots, add the
following entries to
/etc/rc.conf
:
ifconfig_fxp0
="up" ifconfig_fxp1
="up" cloned_interfaces="lagg
" ifconfig_0
lagg
="laggproto failover laggport0
fxp0
laggportfxp1
10.0.0.15/24
"
For laptop users, it is usually desirable to configure the wireless device as a secondary which is only used when the Ethernet connection is not available. With lagg(4), it is possible to configure a failover which prefers the Ethernet connection for both performance and security reasons, while maintaining the ability to transfer data over the wireless connection.
This is achieved by overriding the physical wireless interface's MAC address with that of the Ethernet interface.
In this example, the Ethernet interface,
bge0
, is the master and the
wireless interface, wlan0
, is
the failover. The wlan0
device
was created from iwn0
wireless
interface, which will be configured with the
MAC address of the Ethernet interface.
First, determine the MAC address of the
Ethernet interface:
#
ifconfig
bge0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 options=19b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4> ether 00:21:70:da:ae:37 inet6 fe80::221:70ff:feda:ae37%bge0 prefixlen 64 scopeid 0x2 nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> media: Ethernet autoselect (1000baseT <full-duplex>) status: activebge0
Replace bge0
to match the
system's Ethernet interface name. The
ether
line will contain the
MAC address of the specified interface.
Now, change the MAC address of the
underlying wireless interface:
#
ifconfig
iwn0
ether00:21:70:da:ae:37
Bring the wireless interface up, but do not set an IP address:
#
ifconfig
wlan0
create wlandeviwn0
ssidmy_router
up
Make sure the bge0
interface
is up, then create the lagg(4) interface with
bge0
as master with failover to
wlan0
:
#
ifconfig
bge0
up#
ifconfig
lagg
create0
#
ifconfig
lagg
up laggproto failover laggport0
bge0
laggportwlan0
The virtual interface should look something like this:
#
ifconfig
lagg0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 options=8<VLAN_MTU> ether 00:21:70:da:ae:37 media: Ethernet autoselect status: active laggproto failover laggport: wlan0 flags=0<> laggport: bge0 flags=5<MASTER,ACTIVE>lagg
0
Then, start the DHCP client to obtain an IP address:
#
dhclient
lagg
0
To retain this configuration across reboots, add the
following entries to
/etc/rc.conf
:
ifconfig_bge0="up" wlans_iwn0
="wlan0" ifconfig_wlan0="WPA" create_args_wlan0="wlanaddr 00:21:70:da:ae:37
" cloned_interfaces="lagg
" ifconfig_0
lagg
="up laggproto failover laggport bge0 laggport wlan0 DHCP"0
The Intel® Preboot eXecution Environment
(PXE) allows an operating system to boot over
the network. For example, a FreeBSD system can boot over the
network and operate without a local disk, using file systems
mounted from an NFS server.
PXE support is usually available in the
BIOS. To use PXE when the
machine starts, select the Boot from network
option in the BIOS setup or type a function
key during system initialization.
In order to provide the files needed for an operating system to boot over the network, a PXE setup also requires properly configured DHCP, TFTP, and NFS servers, where:
Initial parameters, such as an IP address, executable boot filename and location, server name, and root path are obtained from the DHCP server.
The operating system loader file is booted using TFTP.
The file systems are loaded using NFS.
When a computer PXE boots, it receives
information over DHCP about where to obtain
the initial boot loader file. After the host computer receives
this information, it downloads the boot loader via
TFTP and then executes the boot loader. In
FreeBSD, the boot loader file is
/boot/pxeboot
. After
/boot/pxeboot
executes, the FreeBSD kernel is
loaded and the rest of the FreeBSD bootup sequence proceeds, as
described in Chapter 12, The FreeBSD Booting Process.
This section describes how to configure these services on a FreeBSD system so that other systems can PXE boot into FreeBSD. Refer to diskless(8) for more information.
As described, the system providing these services is insecure. It should live in a protected area of a network and be untrusted by other hosts.
The steps shown in this section configure the built-in
NFS and TFTP servers.
The next section demonstrates how to install and configure the
DHCP server. In this example, the
directory which will contain the files used by
PXE users is
/b/tftpboot/FreeBSD/install
. It is
important that this directory exists and that the same
directory name is set in both
/etc/inetd.conf
and
/usr/local/etc/dhcpd.conf
.
Create the root directory which will contain a FreeBSD installation to be NFS mounted:
#
export NFSROOTDIR=/b/tftpboot/FreeBSD/install
#
mkdir -p ${NFSROOTDIR}
Enable the NFS server by adding
this line to /etc/rc.conf
:
nfs_server_enable="YES"
Export the diskless root directory via
NFS by adding the following to
/etc/exports
:
/b -ro -alldirs -maproot=root
Start the NFS server:
#
service nfsd start
Enable inetd(8) by adding the following line to
/etc/rc.conf
:
inetd_enable="YES"
Uncomment the following line in
/etc/inetd.conf
by making sure it
does not start with a #
symbol:
tftp dgram udp wait root /usr/libexec/tftpd tftpd -l -s /b/tftpboot
Some PXE versions require the
TCP version of
TFTP. In this case, uncomment the
second tftp
line which contains
stream tcp
.
Start inetd(8):
#
service inetd start
Install the base system into
${NFSROOTDIR}
, either by
decompressing the official archives or by rebuilding
the FreeBSD kernel and userland (refer to
Section 23.5, “Updating FreeBSD from Source” for more detailed
instructions, but do not forget to add
DESTDIR=
when running the
${NFSROOTDIR}
make installkernel
and
make installworld
commands.
Test that the TFTP server works and can download the boot loader which will be obtained via PXE:
#
tftp localhost
tftp>get FreeBSD/install/boot/pxeboot
Received 264951 bytes in 0.1 seconds
Edit ${NFSROOTDIR}/etc/fstab
and
create an entry to mount the root file system over
NFS:
# Device Mountpoint FSType Options Dump Pass
myhost.example.com
:/b/tftpboot/FreeBSD/install / nfs ro 0 0
Replace myhost.example.com
with the hostname or IP address of the
NFS server. In this example, the root
file system is mounted read-only in order to prevent
NFS clients from potentially deleting
the contents of the root file system.
Set the root password in the PXE environment for client machines which are PXE booting :
#
chroot ${NFSROOTDIR}
#
passwd
If needed, enable ssh(1) root logins for client
machines which are PXE booting by
editing
${NFSROOTDIR}/etc/ssh/sshd_config
and
enabling PermitRootLogin
. This option
is documented in sshd_config(5).
Perform any other needed customizations of the
PXE environment in
${NFSROOTDIR}
. These customizations
could include things like installing packages or editing
the password file with vipw(8).
When booting from an NFS root volume,
/etc/rc
detects the
NFS boot and runs
/etc/rc.initdiskless
. In this case,
/etc
and /var
need
to be memory backed file systems so that these directories are
writable but the NFS root directory is
read-only:
#
chroot ${NFSROOTDIR}
#
mkdir -p conf/base
#
tar -c -v -f conf/base/etc.cpio.gz --format cpio --gzip etc
#
tar -c -v -f conf/base/var.cpio.gz --format cpio --gzip var
When the system boots, memory file systems for
/etc
and /var
will
be created and mounted and the contents of the
cpio.gz
files will be copied into
them. By default, these file systems have a maximum capacity
of 5 megabytes. If your archives do not fit, which is
usually the case for /var
when binary
packages have been installed, request a larger size by putting
the number of 512 byte sectors needed (e.g., 5 megabytes
is 10240 sectors) in
${NFSROOTDIR}/conf/base/etc/md_size
and
${NFSROOTDIR}/conf/base/var/md_size
files for /etc
and
/var
file systems respectively.
The DHCP server does not need to be the same machine as the TFTP and NFS server, but it needs to be accessible in the network.
DHCP is not part of the FreeBSD base system but can be installed using the net/isc-dhcp43-server port or package.
Once installed, edit the configuration file,
/usr/local/etc/dhcpd.conf
. Configure
the next-server
,
filename
, and
root-path
settings as seen in this
example:
subnet 192.168.0.0 netmask 255.255.255.0 { range 192.168.0.2 192.168.0.3 ; option subnet-mask 255.255.255.0 ; option routers 192.168.0.1 ; option broadcast-address 192.168.0.255 ; option domain-name-servers 192.168.35.35, 192.168.35.36 ; option domain-name "example.com"; # IP address of TFTP server next-server192.168.0.1
; # path of boot loader obtained via tftp filename "FreeBSD/install/boot/pxeboot
" ; # pxeboot boot loader will try to NFS mount this directory for root FS option root-path "192.168.0.1:/b/tftpboot/FreeBSD/install/
" ; }
The next-server
directive is used to
specify the IP address of the
TFTP server.
The filename
directive defines the path
to /boot/pxeboot
. A relative filename is
used, meaning that /b/tftpboot
is not
included in the path.
The root-path
option defines the path
to the NFS root file system.
Once the edits are saved, enable DHCP
at boot time by adding the following line to
/etc/rc.conf
:
dhcpd_enable="YES"
Then start the DHCP service:
#
service isc-dhcpd start
Once all of the services are configured and started, PXE clients should be able to automatically load FreeBSD over the network. If a particular client is unable to connect, when that client machine boots up, enter the BIOS configuration menu and confirm that it is set to boot from the network.
This section describes some troubleshooting tips for isolating the source of the configuration problem should no clients be able to PXE boot.
Use the net/wireshark package or port to debug the network traffic involved during the PXE booting process, which is illustrated in the diagram below.
Client broadcasts a
| |
The DHCP server responds
with the IP address,
| |
The client sends a TFTP
request to | |
The TFTP server responds
and sends | |
The client executes
|
On the
TFTP server, read
/var/log/xferlog
to ensure that
pxeboot
is being retrieved from
the correct location. To test this example
configuration:
#
tftp 192.168.0.1
tftp>get FreeBSD/install/boot/pxeboot
Received 264951 bytes in 0.1 seconds
The BUGS
sections in tftpd(8)
and tftp(1) document some limitations with
TFTP.
Make sure that the root file system can be mounted via NFS. To test this example configuration:
#
mount -t nfs 192.168.0.1:/b/tftpboot/FreeBSD/install /mnt
IPv6 is the new version of the well known IP protocol, also known as IPv4. IPv6 provides several advantages over IPv4 as well as many new features:
Its 128-bit address space allows for 340,282,366,920,938,463,463,374,607,431,768,211,456 addresses. This addresses the IPv4 address shortage and eventual IPv4 address exhaustion.
Routers only store network aggregation addresses in their routing tables, thus reducing the average space of a routing table to 8192 entries. This addresses the scalability issues associated with IPv4, which required every allocated block of IPv4 addresses to be exchanged between Internet routers, causing their routing tables to become too large to allow efficient routing.
Address autoconfiguration (RFC2462).
Mandatory multicast addresses.
Built-in IPsec (IP security).
Simplified header structure.
Support for mobile IP.
IPv6-to-IPv4 transition mechanisms.
FreeBSD includes the http://www.kame.net/ IPv6 reference implementation and comes with everything needed to use IPv6. This section focuses on getting IPv6 configured and running.
There are three different types of IPv6 addresses:
A packet sent to a unicast address arrives at the interface belonging to the address.
These addresses are syntactically indistinguishable from unicast addresses but they address a group of interfaces. The packet destined for an anycast address will arrive at the nearest router interface. Anycast addresses are only used by routers.
These addresses identify a group of interfaces. A
packet destined for a multicast address will arrive at
all interfaces belonging to the multicast group. The
IPv4 broadcast address, usually
xxx.xxx.xxx.255
, is
expressed by multicast addresses in
IPv6.
When reading an IPv6 address, the
canonical form is represented as
x:x:x:x:x:x:x:x
, where each
x
represents a 16 bit hex value. An
example is
FEBC:A574:382B:23C1:AA49:4592:4EFE:9982
.
Often, an address will have long substrings of all zeros.
A ::
(double colon) can be used to replace
one substring per address. Also, up to three leading
0
s per hex value can be omitted. For
example, fe80::1
corresponds to the
canonical form
fe80:0000:0000:0000:0000:0000:0000:0001
.
A third form is to write the last 32 bits using the well
known IPv4 notation. For example,
2002::10.0.0.1
corresponds to the
hexadecimal canonical representation
2002:0000:0000:0000:0000:0000:0a00:0001
,
which in turn is equivalent to
2002::a00:1
.
To view a FreeBSD system's IPv6 address, use ifconfig(8):
#
ifconfig
rl0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500 inet 10.0.0.10 netmask 0xffffff00 broadcast 10.0.0.255 inet6 fe80::200:21ff:fe03:8e1%rl0 prefixlen 64 scopeid 0x1 ether 00:00:21:03:08:e1 media: Ethernet autoselect (100baseTX ) status: active
In this example, the rl0
interface is
using fe80::200:21ff:fe03:8e1%rl0
, an
auto-configured link-local address which was automatically
generated from the MAC address.
Some IPv6 addresses are reserved. A summary of these reserved addresses is seen in Table 31.3, “Reserved IPv6 Addresses”:
IPv6 address | Prefixlength (Bits) | Description | Notes |
---|---|---|---|
:: | 128 bits | unspecified | Equivalent to 0.0.0.0 in
IPv4. |
::1 | 128 bits | loopback address | Equivalent to 127.0.0.1 in
IPv4. |
::00:xx:xx:xx:xx | 96 bits | embedded IPv4 | The lower 32 bits are the compatible IPv4 address. |
::ff:xx:xx:xx:xx | 96 bits | IPv4 mapped IPv6 address | The lower 32 bits are the IPv4 address for hosts which do not support IPv6. |
fe80::/10 | 10 bits | link-local | Equivalent to 169.254.0.0/16 in IPv4. |
fc00::/7 | 7 bits | unique-local | Unique local addresses are intended for local communication and are only routable within a set of cooperating sites. |
ff00:: | 8 bits | multicast | |
2000::-3fff:: | 3 bits | global unicast | All global unicast addresses are assigned from
this pool. The first 3 bits are
001 . |
For further information on the structure of IPv6 addresses, refer to RFC3513.
To configure a FreeBSD system as an IPv6
client, add these two lines to
rc.conf
:
ifconfig_rl0
_ipv6="inet6 accept_rtadv"
rtsold_enable="YES"
The first line enables the specified interface to receive router advertisement messages. The second line enables the router solicitation daemon, rtsol(8).
If the interface needs a statically assigned IPv6 address, add an entry to specify the static address and associated prefix length:
ifconfig_rl0
_ipv6="inet62001:db8:4672:6565:2026:5043:2d42:5344
prefixlen64
"
To assign a default router, specify its address:
ipv6_defaultrouter="2001:db8:4672:6565::1
"
In order to connect to other IPv6 networks, one must have a provider or a tunnel that supports IPv6:
Contact an Internet Service Provider to see if they offer IPv6.
Hurricane Electric offers tunnels with end-points all around the globe.
Install the net/freenet6 package or port for a dial-up connection.
This section demonstrates how to take the directions from
a tunnel provider and convert them into
/etc/rc.conf
settings that will persist
through reboots.
The first /etc/rc.conf
entry creates
the generic tunneling interface
:gif0
cloned_interfaces="gif0
"
Next, configure that interface with the
IPv4 addresses of the local and remote
endpoints. Replace MY_IPv4_ADDR
and REMOTE_IPv4_ADDR
with the
actual IPv4 addresses:
create_args_gif0="tunnel MY_IPv4_ADDR REMOTE_IPv4_ADDR
"
To apply the IPv6 address that has been
assigned for use as the IPv6 tunnel
endpoint, add this line, replacing
MY_ASSIGNED_IPv6_TUNNEL_ENDPOINT_ADDR
with the assigned address:
ifconfig_gif0_ipv6="inet6 MY_ASSIGNED_IPv6_TUNNEL_ENDPOINT_ADDR
"
Then, set the default route for the other side of the
IPv6 tunnel. Replace
MY_IPv6_REMOTE_TUNNEL_ENDPOINT_ADDR
with the default gateway address assigned by the
provider:
ipv6_defaultrouter="MY_IPv6_REMOTE_TUNNEL_ENDPOINT_ADDR
"
If the FreeBSD system will route IPv6 packets between the rest of the network and the world, enable the gateway using this line:
ipv6_gateway_enable="YES"
This section demonstrates how to setup rtadvd(8) to advertise the IPv6 default route.
To enable rtadvd(8), add the following to
/etc/rc.conf
:
rtadvd_enable="YES"
It is important to specify the interface on which to
do IPv6 router advertisement. For example,
to tell rtadvd(8) to use
rl0
:
rtadvd_interfaces="rl0"
Next, create the configuration file,
/etc/rtadvd.conf
as seen in this
example:
rl0:\ :addrs#1:addr="2001:db8:1f11:246::":prefixlen#64:tc=ether:
Replace rl0
with the interface
to be used and 2001:db8:1f11:246::
with the prefix of the allocation.
For a dedicated /64
subnet, nothing else needs
to be changed. Otherwise, change the
prefixlen#
to the correct value.
When IPv6 is enabled on a server, there may be a need to enable IPv4 mapped IPv6 address communication. This compatibility option allows for IPv4 addresses to be represented as IPv6 addresses. Permitting IPv6 applications to communicate with IPv4 and vice versa may be a security issue.
This option may not be required in most cases and is
available only for compatibility. This option will allow
IPv6-only applications to work with
IPv4 in a dual stack environment. This
is most useful for third party applications which may not
support an IPv6-only environment. To
enable this feature,
add the following to /etc/rc.conf
:
ipv6_ipv4mapping="YES"
Reviewing the information in RFC 3493, section 3.6 and 3.7 as well as RFC 4038 section 4.2 may be useful to some administrators.
The Common Address Redundancy Protocol (CARP) allows multiple hosts to share the same IP address and Virtual Host ID (VHID) in order to provide high availability for one or more services. This means that one or more hosts can fail, and the other hosts will transparently take over so that users do not see a service failure.
In addition to the shared IP address, each host has its own IP address for management and configuration. All of the machines that share an IP address have the same VHID. The VHID for each virtual IP address must be unique across the broadcast domain of the network interface.
High availability using CARP is built into FreeBSD, though the steps to configure it vary slightly depending upon the FreeBSD version. This section provides the same example configuration for versions before and equal to or after FreeBSD 10.
This example configures failover support with three hosts,
all with unique IP addresses, but providing
the same web content. It has two different masters named
hosta.example.org
and
hostb.example.org
, with a shared backup
named hostc.example.org
.
These machines are load balanced with a Round Robin DNS configuration. The master and backup machines are configured identically except for their hostnames and management IP addresses. These servers must have the same configuration and run the same services. When the failover occurs, requests to the service on the shared IP address can only be answered correctly if the backup server has access to the same content. The backup machine has two additional CARP interfaces, one for each of the master content server's IP addresses. When a failure occurs, the backup server will pick up the failed master machine's IP address.
Enable boot-time support for CARP by
adding an entry for the carp.ko
kernel
module in /boot/loader.conf
:
carp_load="YES"
To load the module now without rebooting:
#
kldload carp
For users who prefer to use a custom kernel, include the following line in the custom kernel configuration file and compile the kernel as described in Chapter 8, Configuring the FreeBSD Kernel:
device carp
The hostname, management IP address and
subnet mask, shared IP address, and
VHID are all set by adding entries to
/etc/rc.conf
. This example is for
hosta.example.org
:
hostname="hosta.example.org
" ifconfig_em0
="inet192.168.1.3
netmask255.255.255.0
" ifconfig_em0
_alias0="inet vhid1
passtestpass
alias192.168.1.50
/32"
The next set of entries are for
hostb.example.org
. Since it
represents a second master, it uses a different shared
IP address and VHID.
However, the passwords specified with pass
must be identical as CARP will only listen
to and accept advertisements from machines with the correct
password.
hostname="hostb.example.org
" ifconfig_em0
="inet192.168.1.4
netmask255.255.255.0
" ifconfig_em0
_alias0="inet vhid2
passtestpass
alias192.168.1.51
/32"
The third machine,
hostc.example.org
, is configured to
handle failover from either master. This machine is
configured with two CARP
VHIDs, one to handle the virtual
IP address for each of the master hosts.
The CARP advertising skew,
advskew
, is set to ensure that the backup
host advertises later than the master, since
advskew
controls the order of precedence when
there are multiple backup servers.
hostname="hostc.example.org" ifconfig_em0
="inet192.168.1.5
netmask255.255.255.0
" ifconfig_em0
_alias0="inet vhid1
advskew100
passtestpass
alias192.168.1.50
/32" ifconfig_em0
_alias1="inet vhid2
advskew100
passtestpass
alias192.168.1.51
/32"
Having two CARP
VHIDs configured means that
hostc.example.org
will notice if
either of the master servers becomes unavailable. If a master
fails to advertise before the backup server, the backup server
will pick up the shared IP address until
the master becomes available again.
If the original master server becomes available again,
hostc.example.org
will not release
the virtual IP address back to it
automatically. For this to happen, preemption has to be
enabled. The feature is disabled by default,
it is controlled via the sysctl(8) variable
net.inet.carp.preempt
. The administrator
can force the backup server to return the
IP address to the master:
#
ifconfig em0 vhid 1 state backup
Once the configuration is complete, either restart networking or reboot each system. High availability is now enabled.
CARP functionality can be controlled via several sysctl(8) variables documented in the carp(4) manual pages. Other actions can be triggered from CARP events by using devd(8).
The configuration for these versions of FreeBSD is similar to the one described in the previous section, except that a CARP device must first be created and referred to in the configuration.
Enable boot-time support for CARP by
loading the if_carp.ko
kernel module in
/boot/loader.conf
:
if_carp_load="YES"
To load the module now without rebooting:
#
kldload carp
For users who prefer to use a custom kernel, include the following line in the custom kernel configuration file and compile the kernel as described in Chapter 8, Configuring the FreeBSD Kernel:
device carp
Next, on each host, create a CARP device:
#
ifconfig carp0 create
Set the hostname, management IP
address, the shared IP address, and
VHID by adding the required lines to
/etc/rc.conf
. Since a virtual
CARP device is used instead of an alias,
the actual subnet mask of /24
is used
instead of /32
. Here are the entries for
hosta.example.org
:
hostname="hosta.example.org
" ifconfig_fxp0
="inet192.168.1.3
netmask255.255.255.0
" cloned_interfaces="carp0" ifconfig_carp0="vhid1
passtestpass
192.168.1.50/24
"
On hostb.example.org
:
hostname="hostb.example.org
" ifconfig_fxp0
="inet192.168.1.4
netmask255.255.255.0
" cloned_interfaces="carp0" ifconfig_carp0="vhid2
passtestpass
192.168.1.51/24
"
The third machine,
hostc.example.org
, is configured to
handle failover from either of the master hosts:
hostname="hostc.example.org
" ifconfig_fxp0
="inet192.168.1.5
netmask255.255.255.0
" cloned_interfaces="carp0 carp1" ifconfig_carp0="vhid1
advskew100
passtestpass
192.168.1.50/24
" ifconfig_carp1="vhid2
advskew100
passtestpass
192.168.1.51/24
"
Preemption is disabled in the
GENERIC
FreeBSD kernel. If
preemption has been enabled with a custom kernel,
hostc.example.org
may not release
the IP address back to the original
content server. The administrator can force the backup
server to return the IP address to the
master with the command:
#
ifconfig carp0 down && ifconfig carp0 up
This should be done on the carp
interface which corresponds to the correct host.
Once the configuration is complete, either restart networking or reboot each system. High availability is now enabled.
VLANs are a way of virtually dividing up a network into many different subnetworks, also referred to as segmenting. Each segment will have its own broadcast domain and be isolated from other VLANs.
On FreeBSD, VLANs must be supported by the network card driver. To see which drivers support vlans, refer to the vlan(4) manual page.
When configuring a VLAN, a couple pieces of information must be known. First, which network interface? Second, what is the VLAN tag?
To configure VLANs at run time, with a
NIC of em0
and a
VLAN tag of 5
the
command would look like this:
#
ifconfig
em0.5
create vlan5
vlandevem0
inet 192.168.20.20/24
See how the interface name includes the NIC driver name and the VLAN tag, separated by a period? This is a best practice to make maintaining the VLAN configuration easy when many VLANs are present on a machine.
To configure VLANs at boot time,
/etc/rc.conf
must be updated. To duplicate
the configuration above, the following will need to be
added:
vlans_em0
="5
" ifconfig_em0
_5
="inet 192.168.20.20/24"
Additional VLANs may be added, by simply
adding the tag to the
vlans_
field and adding an additional line configuring the network on
that VLAN tag's interface.em0
It is useful to assign a symbolic name to an interface so
that when the associated hardware is changed, only a few
configuration variables need to be updated. For example,
security cameras need to be run over VLAN 1 on
em0
. Later, if the em0
card is replaced with a card that uses the ixgb(4) driver,
all references to em0.1
will not have to
change to ixgb0.1
.
To configure VLAN
5
, on the
NIC em0
, assign the
interface name cameras
, and assign the
interface an IP address of
with a 192.168.20.20
24
-bit prefix,
use this command:
#
ifconfig
em0.5
create vlan5
vlandevem0
namecameras
inet192.168.20.20/24
For an interface named video
, use the
following:
#
ifconfig
video.5
create vlan5
vlandevvideo
namecameras inet 192.168.20.20/24
To apply the changes at boot time, add the following lines to
/etc/rc.conf
:
vlans_video
="camera
" create_args_camera
="vlan5
" ifconfig_camera
="inet192.168.20.20/24
"
FreeBSD CD and DVD sets are available from several online retailers:
FreeBSD Mall, Inc.
2420 Sand Creek Rd C-1 #347
Brentwood, CA
94513
USA
Phone: +1 925 240-6652
Fax: +1 925 674-0821
Email: <info@freebsdmall.com>
WWW: https://www.freebsdmall.com
Getlinux
78 Rue de la Croix Rochopt
Épinay-sous-Sénart
91860
France
Email: <contact@getlinux.fr>
WWW: http://www.getlinux.fr/
Dr. Hinner EDV
Kochelseestr. 11
D-81371 München
Germany
Phone: (0177) 428 419 0
Email: <infow@hinner.de>
WWW: http://www.hinner.de/linux/freebsd.html
Linux Center
Galernaya Street, 55
Saint-Petersburg
190000
Russia
Phone: +7-812-309-06-86
Email: <info@linuxcenter.ru>
WWW: http://linuxcenter.ru/shop/freebsd
The official sources for FreeBSD are available via anonymous
FTP from a worldwide set of mirror sites.
The site ftp://ftp.FreeBSD.org/pub/FreeBSD/
is available via HTTP and
FTP. It is made up of many machines operated
by the project cluster administrators and behind GeoDNS to
direct users to the closest available mirror.
Additionally, FreeBSD is available via anonymous FTP from the following mirror sites. When obtaining FreeBSD via anonymous FTP, please try to use a nearby site. The mirror sites listed as “Primary Mirror Sites” typically have the entire FreeBSD archive (all the currently available versions for each of the architectures) but faster download speeds are probably available from a site that is in your country or region. The regional sites carry the most recent versions for the most popular architecture(s) but might not carry the entire FreeBSD archive. All sites provide access via anonymous FTP but some sites also provide access via other methods. The access methods available for each site are provided in parentheses after the hostname.
Central Servers, Primary Mirror Sites, Armenia, Australia, Austria, Brazil, China, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hong Kong, Ireland, Japan, Korea, Latvia, Lithuania, Netherlands, New Zealand, Norway, Poland, Russia, Saudi Arabia, Slovenia, South Africa, Spain, Sweden, Switzerland, Taiwan, Ukraine, United Kingdom, USA.
(as of UTC)
In case of problems, please contact the hostmaster
<mirror-admin@FreeBSD.org>
for this domain.
ftp://ftp4.FreeBSD.org/pub/FreeBSD/ (ftp / ftpv6 / http://ftp4.FreeBSD.org/pub/FreeBSD/ / http://ftp4.FreeBSD.org/pub/FreeBSD/)
ftp://ftp10.FreeBSD.org/pub/FreeBSD/ (ftp / ftpv6 / http://ftp10.FreeBSD.org/pub/FreeBSD/ / http://ftp10.FreeBSD.org/pub/FreeBSD/)
ftp://ftp14.FreeBSD.org/pub/FreeBSD/ (ftp / http://ftp14.FreeBSD.org/pub/FreeBSD/)
In case of problems, please contact the hostmaster
<hostmaster@am.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@au.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@at.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@br.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@cn.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@cz.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@dk.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@ee.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@fi.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@fr.FreeBSD.org>
for this domain.
ftp://ftp1.fr.FreeBSD.org/pub/FreeBSD/ (ftp / http://ftp1.fr.FreeBSD.org/pub/FreeBSD/ / rsync)
ftp://ftp6.fr.FreeBSD.org/pub/FreeBSD/ (ftp / rsync)
In case of problems, please contact the hostmaster
<de-bsd-hubs@de.FreeBSD.org>
for this domain.
ftp://ftp1.de.FreeBSD.org/freebsd/ (ftp / http://www1.de.FreeBSD.org/freebsd/ / rsync://rsync3.de.FreeBSD.org/freebsd/)
ftp://ftp2.de.FreeBSD.org/pub/FreeBSD/ (ftp / http://ftp2.de.FreeBSD.org/pub/FreeBSD/ / rsync)
ftp://ftp4.de.FreeBSD.org/FreeBSD/ (ftp / http://ftp4.de.FreeBSD.org/pub/FreeBSD/)
ftp://ftp7.de.FreeBSD.org/pub/FreeBSD/ (ftp / http://ftp7.de.FreeBSD.org/pub/FreeBSD/)
In case of problems, please contact the hostmaster
<hostmaster@gr.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@ie.FreeBSD.org>
for this domain.
ftp://ftp3.ie.FreeBSD.org/pub/FreeBSD/ (ftp / rsync)
In case of problems, please contact the hostmaster
<hostmaster@jp.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@kr.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@lv.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@lt.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@nl.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@no.FreeBSD.org>
for this domain.
ftp://ftp.no.FreeBSD.org/pub/FreeBSD/ (ftp / rsync)
In case of problems, please contact the hostmaster
<hostmaster@pl.FreeBSD.org>
for this domain.
ftp2.pl.FreeBSD.org
In case of problems, please contact the hostmaster
<hostmaster@ru.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<ftpadmin@isu.net.sa>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@si.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@za.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@es.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@se.FreeBSD.org>
for this domain.
ftp://ftp2.se.FreeBSD.org/pub/FreeBSD/ (ftp / rsync://ftp2.se.FreeBSD.org/)
ftp://ftp4.se.FreeBSD.org/pub/FreeBSD/ (ftp / ftp://ftp4.se.FreeBSD.org/pub/FreeBSD/ / http://ftp4.se.FreeBSD.org/pub/FreeBSD/ / http://ftp4.se.FreeBSD.org/pub/FreeBSD/ / rsync://ftp4.se.FreeBSD.org/pub/FreeBSD/ / rsync://ftp4.se.FreeBSD.org/pub/FreeBSD/)
ftp://ftp6.se.FreeBSD.org/pub/FreeBSD/ (ftp / http://ftp6.se.FreeBSD.org/pub/FreeBSD/)
In case of problems, please contact the hostmaster
<hostmaster@ch.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@tw.FreeBSD.org>
for this domain.
ftp://ftp.tw.FreeBSD.org/pub/FreeBSD/ (ftp / ftp://ftp.tw.FreeBSD.org/pub/FreeBSD/ / rsync / rsyncv6)
ftp://ftp2.tw.FreeBSD.org/pub/FreeBSD/ (ftp / ftp://ftp2.tw.FreeBSD.org/pub/FreeBSD/ / http://ftp2.tw.FreeBSD.org/pub/FreeBSD/ / http://ftp2.tw.FreeBSD.org/pub/FreeBSD/ / rsync / rsyncv6)
ftp://ftp6.tw.FreeBSD.org/pub/FreeBSD/ (ftp / http://ftp6.tw.FreeBSD.org/ / rsync)
ftp://ftp11.tw.FreeBSD.org/pub/FreeBSD/ (ftp / http://ftp11.tw.FreeBSD.org/FreeBSD/)
In case of problems, please contact the hostmaster
<hostmaster@uk.FreeBSD.org>
for this domain.
In case of problems, please contact the hostmaster
<hostmaster@us.FreeBSD.org>
for this domain.
ftp://ftp4.us.FreeBSD.org/pub/FreeBSD/ (ftp / ftpv6 / http://ftp4.us.FreeBSD.org/pub/FreeBSD/ / http://ftp4.us.FreeBSD.org/pub/FreeBSD/)
ftp://ftp13.us.FreeBSD.org/pub/FreeBSD/ (ftp / http://ftp13.us.FreeBSD.org/pub/FreeBSD/ / rsync)
ftp://ftp14.us.FreeBSD.org/pub/FreeBSD/ (ftp / http://ftp14.us.FreeBSD.org/pub/FreeBSD/)
As of July 2012, FreeBSD uses Subversion as the only version control system for storing all of FreeBSD's source code, documentation, and the Ports Collection.
Subversion is generally a
developer tool. Users may prefer to use
freebsd-update
(Section 23.2, “FreeBSD Update”) to update
the FreeBSD base system, and portsnap
(Section 4.5, “Using the Ports Collection”) to update the FreeBSD Ports
Collection.
This section demonstrates how to install Subversion on a FreeBSD system and use it to create a local copy of a FreeBSD repository. Additional information on the use of Subversion is included.
Installing security/ca_root_nss allows Subversion to verify the identity of HTTPS repository servers. The root SSL certificates can be installed from a port:
#
cd /usr/ports/security/ca_root_nss
#
make install clean
or as a package:
#
pkg install ca_root_nss
A lightweight version of
Subversion is already installed
on FreeBSD as svnlite
. The port or package
version of Subversion is only
needed if the Python or Perl API is needed,
or if a later version of Subversion is desired.
The only difference from normal
Subversion use is that the command
name is svnlite
.
If svnlite
is unavailable or the full
version of Subversion is needed,
then it must be installed.
Subversion can be installed from the Ports Collection:
#
cd /usr/ports/devel/subversion
#
make install clean
Subversion can also be installed as a package:
#
pkg install subversion
To fetch a clean copy of the sources into a local
directory, use svn
. The files in this
directory are called a local working
copy.
Move or delete an existing destination directory before
using checkout
for the first time.
Checkout over an existing
non-svn
directory can cause conflicts
between the existing files and those brought in from the
repository.
Subversion uses
URLs to designate a repository, taking the
form of protocol://hostname/path
.
The first component of the path is the FreeBSD repository to
access. There are three different repositories,
base
for the FreeBSD base system source code,
ports
for the Ports Collection, and
doc
for documentation. For example, the
URL
https://svn.FreeBSD.org/ports/head/
specifies the main branch of the ports repository,
using the https
protocol.
A checkout from a given repository is performed with a command like this:
#
svn checkout https://svn.FreeBSD.org/
repository
/branch
lwcdir
where:
repository
is one of the
Project repositories: base
,
ports
, or
doc
.
branch
depends on the
repository used. ports
and
doc
are mostly updated in the
head
branch, while
base
maintains the latest version of
-CURRENT under head
and the respective
latest versions of the -STABLE branches under
stable/9
(9.x
) and
stable/10
(10.x
).
lwcdir
is the target
directory where the contents of the specified branch
should be placed. This is usually
/usr/ports
for
ports
,
/usr/src
for
base
, and
/usr/doc
for
doc
.
This example checks out the Ports Collection from the
FreeBSD repository using the HTTPS
protocol, placing the local working copy in
/usr/ports
. If
/usr/ports
is already
present but was not created by svn
,
remember to rename or delete it before the checkout.
#
svn checkout https://svn.FreeBSD.org/ports/head /usr/ports
Because the initial checkout must download the full branch of the remote repository, it can take a while. Please be patient.
After the initial checkout, the local working copy can be updated by running:
#
svn update
lwcdir
To update
/usr/ports
created in
the example above, use:
#
svn update /usr/ports
The update is much quicker than a checkout, only transferring files that have changed.
An alternate way of updating the local working copy after
checkout is provided by the Makefile
in
the /usr/ports
,
/usr/src
, and
/usr/doc
directories.
Set SVN_UPDATE
and use the
update
target. For example, to
update /usr/src
:
#
cd /usr/src
#
make update SVN_UPDATE=yes
The FreeBSD Subversion repository is:
svn.FreeBSD.org
This is a publicly accessible mirror network that uses GeoDNS to select an appropriate back end server. To view the FreeBSD Subversion repositories through a browser, use https://svnweb.FreeBSD.org/.
HTTPS is the preferred protocol, but the
security/ca_root_nss
package will need to be installed in order to automatically
validate certificates.
For other information about using Subversion, please see the “Subversion Book”, titled Version Control with Subversion, or the Subversion Documentation.
These sites make FreeBSD available through the rsync protocol. The rsync utility transfers only the differences between two sets of files. This is useful for mirror sites of the FreeBSD FTP server. The rsync suite is available for many operating systems, on FreeBSD, see the net/rsync port or use the package.
rsync://ftp.cz.FreeBSD.org/
Available collections:
ftp: A partial mirror of the FreeBSD FTP server.
FreeBSD: A full mirror of the FreeBSD FTP server.
rsync://ftp.nl.FreeBSD.org/
Available collections:
FreeBSD: A full mirror of the FreeBSD FTP server.
rsync://ftp.mtu.ru/
Available collections:
FreeBSD: A full mirror of the FreeBSD FTP server.
FreeBSD-Archive: The mirror of FreeBSD Archive FTP server.
rsync://ftp4.se.freebsd.org/
Available collections:
FreeBSD: A full mirror of the FreeBSD FTP server.
rsync://ftp.tw.FreeBSD.org/
rsync://ftp2.tw.FreeBSD.org/
rsync://ftp6.tw.FreeBSD.org/
Available collections:
FreeBSD: A full mirror of the FreeBSD FTP server.
rsync://rsync.mirrorservice.org/
Available collections:
ftp.freebsd.org: A full mirror of the FreeBSD FTP server.
rsync://ftp-master.FreeBSD.org/
This server may only be used by FreeBSD primary mirror sites.
Available collections:
FreeBSD: The master archive of the FreeBSD FTP server.
acl: The FreeBSD master ACL list.
rsync://ftp13.FreeBSD.org/
Available collections:
FreeBSD: A full mirror of the FreeBSD FTP server.
While manual pages provide a definitive reference for individual pieces of the FreeBSD operating system, they seldom illustrate how to put the pieces together to make the whole operating system run smoothly. For this, there is no substitute for a good book or users' manual on UNIX® system administration.
International books:
Using FreeBSD (in Traditional Chinese), published by Drmaster, 1997. ISBN 9-578-39435-7.
FreeBSD Unleashed (Simplified Chinese translation), published by China Machine Press. ISBN 7-111-10201-0.
FreeBSD From Scratch Second Edition (in Simplified Chinese), published by China Machine Press. ISBN 7-111-10286-X.
FreeBSD Handbook Second Edition (Simplified Chinese translation), published by Posts & Telecom Press. ISBN 7-115-10541-3.
FreeBSD & Windows (in Simplified Chinese), published by China Railway Publishing House. ISBN 7-113-03845-X
FreeBSD Internet Services HOWTO (in Simplified Chinese), published by China Railway Publishing House. ISBN 7-113-03423-3
FreeBSD (in Japanese), published by CUTT. ISBN 4-906391-22-2 C3055 P2400E.
Complete Introduction to FreeBSD (in Japanese), published by Shoeisha Co., Ltd. ISBN 4-88135-473-6 P3600E.
Personal UNIX Starter Kit FreeBSD (in Japanese), published by ASCII. ISBN 4-7561-1733-3 P3000E.
FreeBSD Handbook (Japanese translation), published by ASCII. ISBN 4-7561-1580-2 P3800E.
FreeBSD mit Methode (in German), published by Computer und Literatur Verlag/Vertrieb Hanser, 1998. ISBN 3-932311-31-0.
FreeBSD de Luxe (in German), published by Verlag Modere Industrie, 2003. ISBN 3-8266-1343-0.
FreeBSD Install and Utilization Manual (in Japanese), published by Mainichi Communications Inc., 1998. ISBN 4-8399-0112-0.
Onno W Purbo, Dodi Maryanto, Syahrial Hubbany, Widjil Widodo Building Internet Server with FreeBSD (in Indonesia Language), published by Elex Media Komputindo.
Absolute BSD: The Ultimate Guide to FreeBSD (Traditional Chinese translation), published by GrandTech Press, 2003. ISBN 986-7944-92-5.
The FreeBSD 6.0 Book (in Traditional Chinese), published by Drmaster, 2006. ISBN 9-575-27878-X.
English language books:
Absolute FreeBSD, 2nd Edition: The Complete Guide to FreeBSD, published by No Starch Press, 2007. ISBN: 978-1-59327-151-0
The Complete FreeBSD, published by O'Reilly, 2003. ISBN: 0596005164
The FreeBSD Corporate Networker's Guide, published by Addison-Wesley, 2000. ISBN: 0201704811
FreeBSD: An Open-Source Operating System for Your Personal Computer, published by The Bit Tree Press, 2001. ISBN: 0971204500
Teach Yourself FreeBSD in 24 Hours, published by Sams, 2002. ISBN: 0672324245
FreeBSD 6 Unleashed, published by Sams, 2006. ISBN: 0672328755
FreeBSD: The Complete Reference, published by McGrawHill, 2003. ISBN: 0072224096
Ohio State University has written a UNIX Introductory Course which is available online in HTML and PostScript format.
An Italian translation of this document is available as part of the FreeBSD Italian Documentation Project.
Edinburgh University has written an Online Guide for newcomers to the UNIX environment.
Jpman Project, Japan FreeBSD Users Group. FreeBSD System Administrator's Manual (Japanese translation). Mainichi Communications Inc., 1998. ISBN4-8399-0109-0 P3300E.
Dreyfus, Emmanuel. Cahiers de l'Admin: BSD 2nd Ed. (in French), Eyrolles, 2004. ISBN 2-212-11463-X
Computer Systems Research Group, UC Berkeley. 4.4BSD Programmer's Reference Manual. O'Reilly & Associates, Inc., 1994. ISBN 1-56592-078-3
Computer Systems Research Group, UC Berkeley. 4.4BSD Programmer's Supplementary Documents. O'Reilly & Associates, Inc., 1994. ISBN 1-56592-079-1
Harbison, Samuel P. and Steele, Guy L. Jr. C: A Reference Manual. 4th Ed. Prentice Hall, 1995. ISBN 0-13-326224-3
Kernighan, Brian and Dennis M. Ritchie. The C Programming Language. 2nd Ed. PTR Prentice Hall, 1988. ISBN 0-13-110362-8
Lehey, Greg. Porting UNIX Software. O'Reilly & Associates, Inc., 1995. ISBN 1-56592-126-7
Plauger, P. J. The Standard C Library. Prentice Hall, 1992. ISBN 0-13-131509-9
Spinellis, Diomidis. Code Reading: The Open Source Perspective. Addison-Wesley, 2003. ISBN 0-201-79940-5
Spinellis, Diomidis. Code Quality: The Open Source Perspective. Addison-Wesley, 2006. ISBN 0-321-16607-8
Stevens, W. Richard and Stephen A. Rago. Advanced Programming in the UNIX Environment. 2nd Ed. Reading, Mass. : Addison-Wesley, 2005. ISBN 0-201-43307-9
Stevens, W. Richard. UNIX Network Programming. 2nd Ed, PTR Prentice Hall, 1998. ISBN 0-13-490012-X
Andleigh, Prabhat K. UNIX System Architecture. Prentice-Hall, Inc., 1990. ISBN 0-13-949843-5
Jolitz, William. “Porting UNIX to the 386”. Dr. Dobb's Journal. January 1991-July 1992.
Leffler, Samuel J., Marshall Kirk McKusick, Michael J Karels and John Quarterman The Design and Implementation of the 4.3BSD UNIX Operating System. Reading, Mass. : Addison-Wesley, 1989. ISBN 0-201-06196-1
Leffler, Samuel J., Marshall Kirk McKusick, The Design and Implementation of the 4.3BSD UNIX Operating System: Answer Book. Reading, Mass. : Addison-Wesley, 1991. ISBN 0-201-54629-9
McKusick, Marshall Kirk, Keith Bostic, Michael J Karels, and John Quarterman. The Design and Implementation of the 4.4BSD Operating System. Reading, Mass. : Addison-Wesley, 1996. ISBN 0-201-54979-4
(Chapter 2 of this book is available online as part of the FreeBSD Documentation Project.)
Marshall Kirk McKusick, George V. Neville-Neil The Design and Implementation of the FreeBSD Operating System. Boston, Mass. : Addison-Wesley, 2004. ISBN 0-201-70245-2
Marshall Kirk McKusick, George V. Neville-Neil, Robert N. M. Watson The Design and Implementation of the FreeBSD Operating System, 2nd Ed.. Westford, Mass. : Pearson Education, Inc., 2014. ISBN 0-321-96897-2
Stevens, W. Richard. TCP/IP Illustrated, Volume 1: The Protocols. Reading, Mass. : Addison-Wesley, 1996. ISBN 0-201-63346-9
Schimmel, Curt. Unix Systems for Modern Architectures. Reading, Mass. : Addison-Wesley, 1994. ISBN 0-201-63338-8
Stevens, W. Richard. TCP/IP Illustrated, Volume 3: TCP for Transactions, HTTP, NNTP and the UNIX Domain Protocols. Reading, Mass. : Addison-Wesley, 1996. ISBN 0-201-63495-3
Vahalia, Uresh. UNIX Internals -- The New Frontiers. Prentice Hall, 1996. ISBN 0-13-101908-2
Wright, Gary R. and W. Richard Stevens. TCP/IP Illustrated, Volume 2: The Implementation. Reading, Mass. : Addison-Wesley, 1995. ISBN 0-201-63354-X
Cheswick, William R. and Steven M. Bellovin. Firewalls and Internet Security: Repelling the Wily Hacker. Reading, Mass. : Addison-Wesley, 1995. ISBN 0-201-63357-4
Garfinkel, Simson. PGP Pretty Good Privacy O'Reilly & Associates, Inc., 1995. ISBN 1-56592-098-8
Anderson, Don and Tom Shanley. Pentium Processor System Architecture. 2nd Ed. Reading, Mass. : Addison-Wesley, 1995. ISBN 0-201-40992-5
Ferraro, Richard F. Programmer's Guide to the EGA, VGA, and Super VGA Cards. 3rd ed. Reading, Mass. : Addison-Wesley, 1995. ISBN 0-201-62490-7
Intel Corporation publishes documentation on their CPUs, chipsets and standards on their developer web site, usually as PDF files.
Shanley, Tom. 80486 System Architecture. 3rd Ed. Reading, Mass. : Addison-Wesley, 1995. ISBN 0-201-40994-1
Shanley, Tom. ISA System Architecture. 3rd Ed. Reading, Mass. : Addison-Wesley, 1995. ISBN 0-201-40996-8
Shanley, Tom. PCI System Architecture. 4th Ed. Reading, Mass. : Addison-Wesley, 1999. ISBN 0-201-30974-2
Van Gilluwe, Frank. The Undocumented PC, 2nd Ed. Reading, Mass: Addison-Wesley Pub. Co., 1996. ISBN 0-201-47950-8
Messmer, Hans-Peter. The Indispensable PC Hardware Book, 4th Ed. Reading, Mass : Addison-Wesley Pub. Co., 2002. ISBN 0-201-59616-4
Lion, John Lion's Commentary on UNIX, 6th Ed. With Source Code. ITP Media Group, 1996. ISBN 1573980137
Raymond, Eric S. The New Hacker's Dictionary, 3rd edition. MIT Press, 1996. ISBN 0-262-68092-0. Also known as the Jargon File
Salus, Peter H. A quarter century of UNIX. Addison-Wesley Publishing Company, Inc., 1994. ISBN 0-201-54777-5
Simon Garfinkel, Daniel Weise, Steven Strassmann. The UNIX-HATERS Handbook. IDG Books Worldwide, Inc., 1994. ISBN 1-56884-203-1. Out of print, but available online.
Don Libes, Sandy Ressler Life with UNIX — special edition. Prentice-Hall, Inc., 1989. ISBN 0-13-536657-7
The BSD family tree.
https://svnweb.freebsd.org/base/head/share/misc/bsd-family-tree?view=co
or /usr/share/misc/bsd-family-tree
on a FreeBSD machine.
Networked Computer Science Technical Reports
Library. http://www.ncstrl.org/
Old BSD releases from the Computer Systems
Research group (CSRG). http://www.mckusick.com/csrg/
:
The 4CD set covers all BSD versions from 1BSD to 4.4BSD and
4.4BSD-Lite2 (but not 2.11BSD, unfortunately). The last
disk also holds the final sources plus the SCCS
files.
Admin Magazin (in German), published by Medialinx AG. ISSN: 2190-1066
BSD Magazine, published by Software Press Sp. z o.o. SK. ISSN: 1898-9144
BSD Now — Video Podcast, published by Jupiter Broadcasting LLC
BSD Talk Podcast, by Will Backman
FreeBSD Journal, published by S&W Publishing, sponsored by The FreeBSD Foundation. ISBN: 978-0-615-88479-0
The rapid pace of FreeBSD progress makes print media impractical as a means of following the latest developments. Electronic resources are the best, if not often the only, way to stay informed of the latest advances. Since FreeBSD is a volunteer effort, the user community itself also generally serves as a “technical support department” of sorts, with electronic mail, web forums, and USENET news being the most effective way of reaching that community.
The most important points of contact with the FreeBSD user community are outlined below. Please send other resources not mentioned here to the FreeBSD documentation project mailing list so that they may also be included.
The FreeBSD Forums provide a web based discussion forum for FreeBSD questions and technical discussion.
Planet FreeBSD offers an aggregation feed of dozens of blogs written by FreeBSD developers. Many developers use this to post quick notes about what they are working on, new patches, and other works in progress.
The BSDConferences YouTube Channel provides a collection of high quality videos from BSD conferences around the world. This is a great way to watch key developers give presentations about new work in FreeBSD.
The mailing lists are the most direct way of addressing questions or opening a technical discussion to a concentrated FreeBSD audience. There are a wide variety of lists on a number of different FreeBSD topics. Sending questions to the most appropriate mailing list will invariably assure a faster and more accurate response.
The charters for the various lists are given at the bottom of this document. Please read the charter before joining or sending mail to any list. Most list subscribers receive many hundreds of FreeBSD related messages every day, and the charters and rules for use are meant to keep the signal-to-noise ratio of the lists high. To do less would see the mailing lists ultimately fail as an effective communications medium for the Project.
To test the ability to send email to FreeBSD lists, send a test message to freebsd-test. Please do not send test messages to any other list.
When in doubt about what list to post a question to, see How to get best results from the FreeBSD-questions mailing list.
Before posting to any list, please learn about how to best use the mailing lists, such as how to help avoid frequently-repeated discussions, by reading the Mailing List Frequently Asked Questions (FAQ) document.
Archives are kept for all of the mailing lists and can be searched using the FreeBSD World Wide Web server. The keyword searchable archive offers an excellent way of finding answers to frequently asked questions and should be consulted before posting a question. Note that this also means that messages sent to FreeBSD mailing lists are archived in perpetuity. When protecting privacy is a concern, consider using a disposable secondary email address and posting only public information.
General lists: The following are general lists which anyone is free (and encouraged) to join:
List | Purpose |
---|---|
freebsd-advocacy | FreeBSD Evangelism |
freebsd-announce | Important events and Project milestones (moderated) |
freebsd-arch | Architecture and design discussions |
freebsd-bugbusters | Discussions pertaining to the maintenance of the FreeBSD problem report database and related tools |
freebsd-bugs | Bug reports |
freebsd-chat | Non-technical items related to the FreeBSD community |
freebsd-chromium | FreeBSD-specific Chromium issues |
freebsd-current | Discussion concerning the use of FreeBSD-CURRENT |
freebsd-isp | Issues for Internet Service Providers using FreeBSD |
freebsd-jobs | FreeBSD employment and consulting opportunities |
freebsd-questions | User questions and technical support |
freebsd-security-notifications | Security notifications (moderated) |
freebsd-stable | Discussion concerning the use of FreeBSD-STABLE |
freebsd-test | Where to send test messages instead of to one of the actual lists |
freebsd-women | FreeBSD advocacy for women |
Technical lists: The following lists are for technical discussion. Read the charter for each list carefully before joining or sending mail to one as there are firm guidelines for their use and content.
List | Purpose |
---|---|
freebsd-acpi | ACPI and power management development |
freebsd-afs | Porting AFS to FreeBSD |
freebsd-amd64 | Porting FreeBSD to AMD64 systems (moderated) |
freebsd-apache | Discussion about Apache related ports |
freebsd-arm | Porting FreeBSD to ARM® processors |
freebsd-atm | Using ATM networking with FreeBSD |
freebsd-bluetooth | Using Bluetooth® technology in FreeBSD |
freebsd-cloud | FreeBSD on cloud platforms (EC2, GCE, Azure, etc.) |
freebsd-cluster | Using FreeBSD in a clustered environment |
freebsd-database | Discussing database use and development under FreeBSD |
freebsd-desktop | Using and improving FreeBSD on the desktop |
dev-ci | Build and test reports from the Continuous Integration servers |
dev-reviews | Notifications of the FreeBSD review system |
freebsd-doc | Creating FreeBSD related documents |
freebsd-drivers | Writing device drivers for FreeBSD |
freebsd-dtrace | Using and working on DTrace in FreeBSD |
freebsd-eclipse | FreeBSD users of Eclipse IDE, tools, rich client applications and ports. |
freebsd-elastic | FreeBSD-specific ElasticSearch discussions |
freebsd-embedded | Using FreeBSD in embedded applications |
freebsd-eol | Peer support of FreeBSD-related software that is no longer supported by the FreeBSD Project. |
freebsd-emulation | Emulation of other systems such as Linux/MS-DOS®/Windows® |
freebsd-enlightenment | Porting Enlightenment and Enlightenment applications |
freebsd-erlang | FreeBSD-specific Erlang discussions |
freebsd-firewire | FreeBSD FireWire® (iLink, IEEE 1394) technical discussion |
freebsd-fortran | Fortran on FreeBSD |
freebsd-fs | File systems |
freebsd-games | Support for Games on FreeBSD |
freebsd-gecko | Gecko Rendering Engine issues |
freebsd-geom | GEOM-specific discussions and implementations |
freebsd-git | Discussion of git use in the FreeBSD project |
freebsd-gnome | Porting GNOME and GNOME applications |
freebsd-hackers | General technical discussion |
freebsd-haskell | FreeBSD-specific Haskell issues and discussions |
freebsd-hardware | General discussion of hardware for running FreeBSD |
freebsd-i18n | FreeBSD Internationalization |
freebsd-ia32 | FreeBSD on the IA-32 (Intel® x86) platform |
freebsd-ia64 | Porting FreeBSD to Intel®'s upcoming IA64 systems |
freebsd-infiniband | Infiniband on FreeBSD |
freebsd-ipfw | Technical discussion concerning the redesign of the IP firewall code |
freebsd-isdn | ISDN developers |
freebsd-jail | Discussion about the jail(8) facility |
freebsd-java | Java™ developers and people porting JDK™s to FreeBSD |
freebsd-kde | Porting KDE and KDE applications |
freebsd-lfs | Porting LFS to FreeBSD |
freebsd-mips | Porting FreeBSD to MIPS® |
freebsd-mobile | Discussions about mobile computing |
freebsd-mono | Mono and C# applications on FreeBSD |
freebsd-multimedia | Multimedia applications |
freebsd-new-bus | Technical discussions about bus architecture |
freebsd-net | Networking discussion and TCP/IP source code |
freebsd-numerics | Discussions of high quality implementation of libm functions |
freebsd-ocaml | FreeBSD-specific OCaml discussions |
freebsd-office | Office applications on FreeBSD |
freebsd-performance | Performance tuning questions for high performance/load installations |
freebsd-perl | Maintenance of a number of Perl-related ports |
freebsd-pf | Discussion and questions about the packet filter firewall system |
freebsd-pkg | Binary package management and package tools discussion |
freebsd-pkg-fallout | Fallout logs from package building |
freebsd-pkgbase | Packaging the FreeBSD base system |
freebsd-platforms | Concerning ports to non Intel® architecture platforms |
freebsd-ports | Discussion of the Ports Collection |
freebsd-ports-announce | Important news and instructions about the Ports Collection (moderated) |
freebsd-ports-bugs | Discussion of the ports bugs/PRs |
freebsd-ppc | Porting FreeBSD to the PowerPC® |
freebsd-proliant | Technical discussion of FreeBSD on HP ProLiant server platforms |
freebsd-python | FreeBSD-specific Python issues |
freebsd-rc | Discussion related to the
rc.d system and its
development |
freebsd-realtime | Development of realtime extensions to FreeBSD |
freebsd-ruby | FreeBSD-specific Ruby discussions |
freebsd-scsi | The SCSI subsystem |
freebsd-security | Security issues affecting FreeBSD |
freebsd-small | Using FreeBSD in embedded applications (obsolete; use freebsd-embedded instead) |
freebsd-snapshots | FreeBSD Development Snapshot Announcements |
freebsd-sparc64 | Porting FreeBSD to SPARC® based systems |
freebsd-standards | FreeBSD's conformance to the C99 and the POSIX® standards |
freebsd-sysinstall | sysinstall(8) development |
freebsd-tcltk | FreeBSD-specific Tcl/Tk discussions |
freebsd-testing | Testing on FreeBSD |
freebsd-tex | Porting TeX and its applications to FreeBSD |
freebsd-threads | Threading in FreeBSD |
freebsd-tilera | Porting FreeBSD to the Tilera family of CPUs |
freebsd-tokenring | Support Token Ring in FreeBSD |
freebsd-toolchain | Maintenance of FreeBSD's integrated toolchain |
freebsd-translators | Translating FreeBSD documents and programs |
freebsd-transport | Discussions of transport level network protocols in FreeBSD |
freebsd-usb | Discussing FreeBSD support for USB |
freebsd-virtualization | Discussion of various virtualization techniques supported by FreeBSD |
freebsd-vuxml | Discussion on VuXML infrastructure |
freebsd-x11 | Maintenance and support of X11 on FreeBSD |
freebsd-xen | Discussion of the FreeBSD port to Xen™ — implementation and usage |
freebsd-xfce | XFCE for FreeBSD — porting and maintaining |
freebsd-zope | Zope for FreeBSD — porting and maintaining |
Limited lists: The following lists are for more specialized (and demanding) audiences and are probably not of interest to the general public. It is also a good idea to establish a presence in the technical lists before joining one of these limited lists in order to understand the communications etiquette involved.
List | Purpose |
---|---|
freebsd-hubs | People running mirror sites (infrastructural support) |
freebsd-user-groups | User group coordination |
freebsd-wip-status | FreeBSD Work-In-Progress Status |
freebsd-wireless | Discussions of 802.11 stack, tools, device driver development |
Digest lists: All of the above lists are available in a digest format. Once subscribed to a list, the digest options can be changed in the account options section.
SVN lists: The following lists are for people interested in seeing the log messages for changes to various areas of the source tree. They are Read-Only lists and should not have mail sent to them.
List | Source area | Area Description (source for) |
---|---|---|
svn-doc-all | /usr/doc | All changes to the doc Subversion repository
(except for user ,
projects and
translations ) |
svn-doc-head | /usr/doc | All changes to the “head” branch of the doc Subversion repository |
svn-doc-projects | /usr/doc/projects | All changes to the projects
area of the doc Subversion repository |
svn-doc-svnadmin | /usr/doc | All changes to the administrative scripts, hooks, and other configuration data of the doc Subversion repository |
svn-ports-all | /usr/ports | All changes to the ports Subversion repository |
svn-ports-head | /usr/ports | All changes to the “head” branch of the ports Subversion repository |
svn-ports-svnadmin | /usr/ports | All changes to the administrative scripts, hooks, and other configuration data of the ports Subversion repository |
svn-src-all | /usr/src | All changes to the src Subversion repository
(except for user
and projects ) |
svn-src-head | /usr/src | All changes to the “head” branch of the src Subversion repository (the FreeBSD-CURRENT branch) |
svn-src-projects | /usr/projects | All changes to the projects
area of the src Subversion repository |
svn-src-release | /usr/src | All changes to the releases
area of the src Subversion repository |
svn-src-releng | /usr/src | All changes to the releng
branches of the src Subversion repository (the
security / release engineering branches) |
svn-src-stable | /usr/src | All changes to the all stable branches of the src Subversion repository |
svn-src-stable-6 | /usr/src | All changes to the stable/6
branch of the src Subversion repository |
svn-src-stable-7 | /usr/src | All changes to the stable/7
branch of the src Subversion repository |
svn-src-stable-8 | /usr/src | All changes to the stable/8
branch of the src Subversion repository |
svn-src-stable-9 | /usr/src | All changes to the stable/9
branch of the src Subversion repository |
svn-src-stable-10 | /usr/src | All changes to the stable/10
branch of the src Subversion repository |
svn-src-stable-11 | /usr/src | All changes to the stable/11
branch of the src Subversion repository |
svn-src-stable-12 | /usr/src | All changes to the stable/12
branch of the src Subversion repository |
svn-src-stable-other | /usr/src | All changes to the
older stable branches of the src
Subversion repository |
svn-src-svnadmin | /usr/src | All changes to the administrative scripts, hooks, and other configuration data of the src Subversion repository |
svn-src-user | /usr/src | All changes to the
experimental user area of the src
Subversion repository |
svn-src-vendor | /usr/src | All changes to the vendor work area of the src Subversion repository |
To subscribe to a list, click the list name at http://lists.FreeBSD.org/mailman/listinfo. The page that is displayed should contain all of the necessary subscription instructions for that list.
To actually post to a given list, send mail to
<
.
It will then be redistributed to mailing list members
world-wide.listname
@FreeBSD.org>
To unsubscribe from a list, click on the URL found at the
bottom of every email received from the list. It is also
possible to send an email to
<
to unsubscribe.listname
-unsubscribe@FreeBSD.org>
It is important to keep discussion in the technical mailing lists on a technical track. To only receive important announcements, instead join the FreeBSD announcements mailing list, which is intended for infrequent traffic.
All FreeBSD mailing lists have certain
basic rules which must be adhered to by anyone using them.
Failure to comply with these guidelines will result in two (2)
written warnings from the FreeBSD Postmaster
<postmaster@FreeBSD.org>
, after which, on a third
offense, the poster will removed from all FreeBSD mailing lists
and filtered from further posting to them. We regret that
such rules and measures are necessary at all, but today's
Internet is a pretty harsh environment, it would seem, and
many fail to appreciate just how fragile some of its
mechanisms are.
Rules of the road:
The topic of any posting should adhere to the basic charter of the list it is posted to. If the list is about technical issues, the posting should contain technical discussion. Ongoing irrelevant chatter or flaming only detracts from the value of the mailing list for everyone on it and will not be tolerated. For free-form discussion on no particular topic, the FreeBSD chat mailing list is freely available and should be used instead.
No posting should be made to more than 2 mailing
lists, and only to 2 when a clear and obvious need to post
to both lists exists. For most lists, there is already a
great deal of subscriber overlap and except for the most
esoteric mixes (say “-stable & -scsi”),
there really is no reason to post to more than one list at
a time. If a message is received with multiple mailing
lists on the Cc
line, trim the
Cc
line before replying. The
person who replies is still responsible for
cross-posting, no matter who the originator might have
been.
Personal attacks and profanity (in the context of an argument) are not allowed, and that includes users and developers alike. Gross breaches of netiquette, like excerpting or reposting private mail when permission to do so was not and would not be forthcoming, are frowned upon but not specifically enforced. However, there are also very few cases where such content would fit within the charter of a list and it would therefore probably rate a warning (or ban) on that basis alone.
Advertising of non-FreeBSD related products or services is strictly prohibited and will result in an immediate ban if it is clear that the offender is advertising by spam.
Individual list charters:
ACPI and power management development
Andrew File System
This list is for discussion on porting and using AFS from CMU/Transarc
Important events / milestones
This is the mailing list for people interested only in occasional announcements of significant FreeBSD events. This includes announcements about snapshots and other releases. It contains announcements of new FreeBSD capabilities. It may contain calls for volunteers etc. This is a low volume, strictly moderated mailing list.
Architecture and design discussions
This list is for discussion of the FreeBSD architecture. Messages will mostly be kept strictly technical in nature. Examples of suitable topics are:
How to re-vamp the build system to have several customized builds running at the same time.
What needs to be fixed with VFS to make Heidemann layers work.
How do we change the device driver interface to be able to use the same drivers cleanly on many buses and architectures.
How to write a network driver.
Bluetooth® in FreeBSD
This is the forum where FreeBSD's Bluetooth® users congregate. Design issues, implementation details, patches, bug reports, status reports, feature requests, and all matters related to Bluetooth® are fair game.
Coordination of the Problem Report handling effort
The purpose of this list is to serve as a coordination and discussion forum for the Bugmeister, his Bugbusters, and any other parties who have a genuine interest in the PR database. This list is not for discussions about specific bugs, patches or PRs.
Bug reports
This is the mailing list for reporting bugs in FreeBSD. Whenever possible, bugs should be submitted using the web interface to it.
Non technical items related to the FreeBSD community
This list contains the overflow from the other lists about non-technical, social information. It includes discussion about whether Jordan looks like a toon ferret or not, whether or not to type in capitals, who is drinking too much coffee, where the best beer is brewed, who is brewing beer in their basement, and so on. Occasional announcements of important events (such as upcoming parties, weddings, births, new jobs, etc) can be made to the technical lists, but the follow ups should be directed to this -chat list.
FreeBSD-specific Chromium issues
This is a list for the discussion of Chromium support for FreeBSD. This is a technical list to discuss development and installation of Chromium.
Running FreeBSD on various cloud platforms
This list discusses running FreeBSD on Amazon EC2, Google Compute Engine, Microsoft Azure, and other cloud computing platforms.
FreeBSD core team
This is an internal mailing list for use by the core members. Messages can be sent to it when a serious FreeBSD-related matter requires arbitration or high-level scrutiny.
Discussions about the use of FreeBSD-CURRENT
This is the mailing list for users of FreeBSD-CURRENT. It includes warnings about new features coming out in -CURRENT that will affect the users, and instructions on steps that must be taken to remain -CURRENT. Anyone running “CURRENT” must subscribe to this list. This is a technical mailing list for which strictly technical content is expected.
Using and improving FreeBSD on the desktop
This is a forum for discussion of FreeBSD on the desktop. It is primarily a place for desktop porters and users to discuss issues and improve FreeBSD's desktop support.
Continuous Integration reports of build and test results
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Automated notifications of work in progress for review in FreeBSD's review tools, including patches.
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Using and working on DTrace in FreeBSD
DTrace is an integrated component of FreeBSD that provides a framework for understanding the kernel as well as user space programs at run time. The mailing list is an archived discussion for developers of the code as well as those using it.
FreeBSD users of Eclipse IDE, tools, rich client applications and ports.
The intention of this list is to provide mutual support for everything to do with choosing, installing, using, developing and maintaining the Eclipse IDE, tools, rich client applications on the FreeBSD platform and assisting with the porting of Eclipse IDE and plugins to the FreeBSD environment.
The intention is also to facilitate exchange of information between the Eclipse community and the FreeBSD community to the mutual benefit of both.
Although this list is focused primarily on the needs of Eclipse users it will also provide a forum for those who would like to develop FreeBSD specific applications using the Eclipse framework.
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Emulation of other systems such as Linux/MS-DOS®/Windows®
This is a forum for technical discussions related to running programs written for other operating systems on FreeBSD.
Enlightenment
Discussions concerning the Enlightenment Desktop Environment for FreeBSD systems. This is a technical mailing list for which strictly technical content is expected.
Peer support of FreeBSD-related software that is no longer supported by the FreeBSD Project.
This list is for those interested in providing or making use of peer support of FreeBSD-related software for which the FreeBSD Project no longer provides official support in the form of security advisories and patches.
FireWire® (iLink, IEEE 1394)
This is a mailing list for discussion of the design and implementation of a FireWire® (aka IEEE 1394 aka iLink) subsystem for FreeBSD. Relevant topics specifically include the standards, bus devices and their protocols, adapter boards/cards/chips sets, and the architecture and implementation of code for their proper support.
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This is the mailing list for discussion of Fortran related ports on FreeBSD: compilers, libraries, scientific and engineering applications from laptops to HPC clusters.
File systems
Discussions concerning FreeBSD filesystems. This is a technical mailing list for which strictly technical content is expected.
Games on FreeBSD
This is a technical list for discussions related to bringing games to FreeBSD. It is for individuals actively working on porting games to FreeBSD, to bring up problems or discuss alternative solutions. Individuals interested in following the technical discussion are also welcome.
Gecko Rendering Engine
This is a forum about Gecko applications using FreeBSD.
Discussion centers around Gecko Ports applications, their installation, their development and their support within FreeBSD.
GEOM
Discussions specific to GEOM and related implementations. This is a technical mailing list for which strictly technical content is expected.
Use of git in the FreeBSD project
Discussions of how to use git in FreeBSD infrastructure including the github mirror and other uses of git for project collaboration. Discussion area for people using git against the FreeBSD github mirror. People wanting to get started with the mirror or git in general on FreeBSD can ask here.
GNOME
Discussions concerning The GNOME Desktop Environment for FreeBSD systems. This is a technical mailing list for which strictly technical content is expected.
Infiniband on FreeBSD
Technical mailing list discussing Infiniband, OFED, and OpenSM on FreeBSD.
IP Firewall
This is the forum for technical discussions concerning the redesign of the IP firewall code in FreeBSD. This is a technical mailing list for which strictly technical content is expected.
Porting FreeBSD to IA64
This is a technical mailing list for individuals actively working on porting FreeBSD to the IA-64 platform from Intel®, to bring up problems or discuss alternative solutions. Individuals interested in following the technical discussion are also welcome.
ISDN Communications
This is the mailing list for people discussing the development of ISDN support for FreeBSD.
Java™ Development
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Jobs offered and sought
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KDE
Discussions concerning KDE on FreeBSD systems. This is a technical mailing list for which strictly technical content is expected.
Technical discussions
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Mirror sites
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FreeBSD-specific OCaml discussions
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Office applications on FreeBSD
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Discussion and questions about the packet filter firewall system
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Binary package management and package tools discussion
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Porting to Non Intel® platforms
Cross-platform FreeBSD issues, general discussion and proposals for non Intel® FreeBSD ports. This is a technical mailing list for which strictly technical content is expected.
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Important news and instructions about the FreeBSD “Ports Collection”
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Technical discussion of FreeBSD on HP ProLiant server platforms
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Python on FreeBSD
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User questions
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FreeBSD-specific Ruby discussions
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SCSI subsystem
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Security issues
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Using FreeBSD in embedded applications
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This list has been obsoleted by freebsd-embedded.
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This is the mailing list for users of FreeBSD-STABLE. “STABLE” is the branch where development continues after a RELEASE, including bug fixes and new features. The ABI is kept stable for binary compatibility. It includes warnings about new features coming out in -STABLE that will affect the users, and instructions on steps that must be taken to remain -STABLE. Anyone running “STABLE” should subscribe to this list. This is a technical mailing list for which strictly technical content is expected.
C99 & POSIX Conformance
This is a forum for technical discussions related to FreeBSD Conformance to the C99 and the POSIX standards.
Teaching with FreeBSD
Non technical mailing list discussing teaching with FreeBSD.
Testing on FreeBSD
Technical mailing list discussing testing on FreeBSD, including ATF/Kyua, test build infrastructure, port tests to FreeBSD from other operating systems (NetBSD, ...), etc.
Porting TeX and its applications to FreeBSD
This is a technical mailing list for discussions related to TeX and its applications on FreeBSD. It is for individuals actively working on porting TeX to FreeBSD, to bring up problems or discuss alternative solutions. Individuals interested in following the technical discussion are also welcome.
Maintenance of FreeBSD's integrated toolchain
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Discussions of transport level network protocols in FreeBSD
The transport mailing list exists for the discussion of issues and designs around the transport level protocols in the FreeBSD network stack, including TCP, SCTP and UDP. Other networking topics, including driver specific and network protocol issues should be discussed on the FreeBSD networking mailing list.
Translating FreeBSD documents and programs
A discussion list where translators of FreeBSD documents from English into other languages can talk about translation methods and tools. New members are asked to introduce themselves and mention the languages they are interested in translating.
Discussing FreeBSD support for USB
This is a mailing list for technical discussions related to FreeBSD support for USB.
User Group Coordination List
This is the mailing list for the coordinators from each of the local area Users Groups to discuss matters with each other and a designated individual from the Core Team. This mail list should be limited to meeting synopsis and coordination of projects that span User Groups.
Discussion of various virtualization techniques supported by FreeBSD
A list to discuss the various virtualization techniques supported by FreeBSD. On one hand the focus will be on the implementation of the basic functionality as well as adding new features. On the other hand users will have a forum to ask for help in case of problems or to discuss their use cases.
FreeBSD Work-In-Progress Status
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Look inside the archives for examples of suitable messages.
An editorial digest of the messages to this list might be posted to the FreeBSD website every few months as part of the Status Reports [3]. Past reports are archived.
Discussions of 802.11 stack, tools device driver development
The FreeBSD-wireless list focuses on 802.11 stack (sys/net80211), device driver and tools development. This includes bugs, new features and maintenance.
Discussion of the FreeBSD port to Xen™ — implementation and usage
A list that focuses on the FreeBSD Xen™ port. The anticipated traffic level is small enough that it is intended as a forum for both technical discussions of the implementation and design details as well as administrative deployment issues.
XFCE
This is a forum for discussions related to bring the XFCE environment to FreeBSD. This is a technical mailing list. It is for individuals actively working on porting XFCE to FreeBSD, to bring up problems or discuss alternative solutions. Individuals interested in following the technical discussion are also welcome.
Zope
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(as of UTC)
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The OpenPGP keys of the
FreeBSD.org
officers
are shown here. These keys can be used to verify a signature or
send encrypted email to one of the officers. A full list of FreeBSD
OpenPGP keys is available in the
PGP
Keys article. The complete keyring can be downloaded
at https://www.FreeBSD.org/doc/pgpkeyring.txt.
<security-officer@FreeBSD.org>
pub rsa4096/D39792F49EA7E5C2 2017-08-16 [SC] [expires: 2023-01-02] Key fingerprint = FC0E 878A E5AF E788 028D 6355 D397 92F4 9EA7 E5C2 uid FreeBSD Security Officer <security-officer@FreeBSD.org> sub rsa4096/6DD0A349F26ADEFD 2017-08-16 [E] [expires: 2023-01-02]
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<secteam-secretary@FreeBSD.org>
pub 4096R/3CB2EAFCC3D6C666 2013-09-24 [expires: 2018-01-01] Key fingerprint = FA97 AA04 4DF9 0969 D5EF 4ADA 3CB2 EAFC C3D6 C666 uid FreeBSD Security Team Secretary <secteam-secretary@FreeBSD.org> sub 4096R/509B26612335EB65 2013-09-24 [expires: 2018-01-01]
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<core-secretary@FreeBSD.org>
pub rsa2048/0CB403E4E95B96EC 2018-06-30 [SC] [expires: 2020-06-29] Key fingerprint = 9F02 836F 50D3 AD5A B75A C588 0CB4 03E4 E95B 96EC uid FreeBSD Core Team Secretary <core-secretary@freebsd.org> sub rsa2048/133C3338A5B95A60 2018-06-30 [E] [expires: 2020-06-29] Key fingerprint = FA37 B8AA C667 C3AA D310 751D 133C 3338 A5B9 5A60
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<portmgr-secretary@FreeBSD.org>
pub rsa2048/D8294EC3BBC4D7D5 2012-07-24 [SC] Key fingerprint = FB37 45C8 6F15 E8ED AC81 32FC D829 4EC3 BBC4 D7D5 uid FreeBSD Ports Management Team Secretary <portmgr-secretary@FreeBSD.org> sub rsa2048/5CC117965F65CFE7 2012-07-24 [E]
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This glossary contains terms and acronyms used within the FreeBSD community and documentation.
See Access Control List.
See ACPI Source Language.
Pseudocode, interpreted by a virtual machine within an ACPI-compliant operating system, providing a layer between the underlying hardware and the documented interface presented to the OS.
The programming language AML is written in.
A list of permissions attached to an object, usually either a file or a network device.
A specification which provides an abstraction of the interface the hardware presents to the operating system, so that the operating system should need to know nothing about the underlying hardware to make the most of it. ACPI evolves and supersedes the functionality provided previously by APM, PNPBIOS and other technologies, and provides facilities for controlling power consumption, machine suspension, device enabling and disabling, etc.
A set of procedures, protocols and tools that specify the canonical interaction of one or more program parts; how, when and why they do work together, and what data they share or operate on.
An API enabling the operating system to work in conjunction with the BIOS in order to achieve power management. APM has been superseded by the much more generic and powerful ACPI specification for most applications.
A daemon that automatically mounts a filesystem when a file or directory within that filesystem is accessed.
The registers that determine which address range a PCI device will respond to.
The definition of BIOS depends a bit on the context. Some people refer to it as the ROM chip with a basic set of routines to provide an interface between software and hardware. Others refer to it as the set of routines contained in the chip that help in bootstrapping the system. Some might also refer to it as the screen used to configure the bootstrapping process. The BIOS is PC-specific but other systems have something similar.
An implementation of the DNS protocols.
This is the name that the Computer Systems Research Group (CSRG) at The University of California at Berkeley gave to their improvements and modifications to AT&T's 32V UNIX®. FreeBSD is a descendant of the CSRG work.
A phenomenon whereby many people will give an opinion on an uncomplicated topic, whilst a complex topic receives little or no discussion. See the FAQ for the origin of the term.
See Carrier Detect.
See Clear To Send.
An RS232C signal indicating that a carrier has been detected.
Also known as the processor. This is the brain of the computer where all calculations take place. There are a number of different architectures with different instruction sets. Among the more well-known are the Intel-x86 and derivatives, Sun SPARC, PowerPC, and Alpha.
A method of authenticating a user, based on a secret shared between client and server.
An RS232C signal giving the remote system permission to send data.
See Also Request To Send.
See Debugger.
See Domain Name System.
See Data Set Ready.
See Data Terminal Ready.
A method of encrypting information, traditionally used as the method of encryption for UNIX® passwords and the crypt(3) function.
An RS232C signal sent from the modem to the computer or terminal indicating a readiness to send and receive data.
See Also Data Terminal Ready.
An RS232C signal sent from the computer or terminal to the modem indicating a readiness to send and receive data.
An interactive in-kernel facility for examining the status of a system, often used after a system has crashed to establish the events surrounding the failure.
An ACPI table, supplying basic configuration information about the base system.
The system that converts humanly readable hostnames (i.e., mail.example.net) to Internet addresses and vice versa.
A protocol that dynamically assigns IP addresses to a computer (host) when it requests one from the server. The address assignment is called a “lease”.
See Extended COFF.
The name of a mutual exclusion mechanism
(a sleep mutex
) that protects a large
set of kernel resources. Although a simple locking mechanism
was adequate in the days where a machine might have only
a few dozen processes, one networking card, and certainly
only one processor, in current times it is an unacceptable
performance bottleneck. FreeBSD developers are actively working
to replace it with locks that protect individual resources,
which will allow a much greater degree of parallelism for
both single-processor and multi-processor machines.
A system where the user and computer interact with graphics.
See HangUp.
The markup language used to create web pages.
See Input/Output.
See Intel’s ASL compiler.
See Internet Protocol.
See IP Firewall.
See IP Version 4.
See IP Version 6.
The IP protocol version 4, which uses 32 bits for addressing. This version is still the most widely used, but it is slowly being replaced with IPv6.
See Also IP Version 6.
The new IP protocol. Invented because the address space in IPv4 is running out. Uses 128 bits for addressing.
Intel’s compiler for converting ASL into AML.
A protocol for accessing email messages on a mail server, characterised by the messages usually being kept on the server as opposed to being downloaded to the mail reader client.
See Also Post Office Protocol Version 3.
The packet transmitting protocol that is the basic protocol on the Internet. Originally developed at the U.S. Department of Defense and an extremely important part of the TCP/IP stack. Without the Internet Protocol, the Internet would not have become what it is today. For more information, see RFC 791.
A company that provides access to the Internet.
Japanese for “turtle”, the term KAME is used in computing circles to refer to the KAME Project, who work on an implementation of IPv6.
See Kernel ld(1).
See Kilo Bits Per Second.
A method of dynamically loading functionality into a FreeBSD kernel without rebooting the system.
A kernel-supported threading system. See the project home page for further details.
Used to measure bandwidth (how much data can pass a given point at a specified amount of time). Alternates to the Kilo prefix include Mega, Giga, Tera, and so forth.
See Local Area Network.
See Lock Order Reversal.
See Line Printer Daemon.
A network used on a local area, e.g. office, home, or so forth.
The FreeBSD kernel uses a number of resource locks to arbitrate contention for those resources. A run-time lock diagnostic system found in FreeBSD-CURRENT kernels (but removed for releases), called witness(4), detects the potential for deadlocks due to locking errors. (witness(4) is actually slightly conservative, so it is possible to get false positives.) A true positive report indicates that “if you were unlucky, a deadlock would have happened here”.
True positive LORs tend to get fixed quickly, so check http://lists.FreeBSD.org/mailman/listinfo/freebsd-current and the LORs Seen page before posting to the mailing lists.
See Merge From Current.
See Merge From Head.
See Merge From Stable.
See Multi-Level Security.
See Message Of The Day.
See Mail Transfer Agent.
See Mail User Agent.
An application used to transfer email. An MTA has traditionally been part of the BSD base system. Today Sendmail is included in the base system, but there are many other MTAs, such as postfix, qmail and Exim.
An application used by users to display and write email.
To merge functionality or a patch from the -CURRENT branch to another, most often -STABLE.
To merge functionality or a patch from a repository HEAD to an earlier branch.
In the normal course of FreeBSD development, a change will be committed to the -CURRENT branch for testing before being merged to -STABLE. On rare occasions, a change will go into -STABLE first and then be merged to -CURRENT.
This term is also used when a patch is merged from -STABLE to a security branch.
See Also Merge From Current.
A message, usually shown on login, often used to distribute information to users of the system.
See Project Evil.
See Network File System.
A technique where IP packets are rewritten on the way through a gateway, enabling many machines behind the gateway to effectively share a single IP address.
A filesystem developed by Microsoft and available in its “New Technology” operating systems, such as Windows® 2000, Windows NT® and Windows® XP.
A means of synchronizing clocks over a network.
See Overtaken By Events.
See On-Demand Mail Relay.
See Operating System.
A set of programs, libraries and tools that provide access to the hardware resources of a computer. Operating systems range today from simplistic designs that support only one program running at a time, accessing only one device to fully multi-user, multi-tasking and multi-process systems that can serve thousands of users simultaneously, each of them running dozens of different applications.
Indicates a suggested change (such as a Problem Report or a feature request) which is no longer relevant or applicable due to such things as later changes to FreeBSD, changes in networking standards, the affected hardware having since become obsolete, and so forth.
See Personal Computer.
See Process ID.
See Post Office Protocol.
See PPP over ATM.
See PPP over Ethernet.
See Problem Report.
A method of enabling access to up to 64 GB of RAM on systems which only physically have a 32-bit wide address space (and would therefore be limited to 4 GB without PAE).
A mythical piece of headgear, much like a
dunce cap
, awarded to any FreeBSD
committer who breaks the build, makes revision numbers
go backwards, or creates any other kind of havoc in
the source base. Any committer worth his or her salt
will soon accumulate a large collection. The usage is
(almost always?) humorous.
See Also Post Office Protocol Version 3.
A protocol for accessing email messages on a mail server, characterised by the messages usually being downloaded from the server to the client, as opposed to remaining on the server.
See Also Internet Message Access Protocol.
As FreeBSD evolves, changes visible to the user should be
kept as unsurprising as possible. For example, arbitrarily
rearranging system startup variables in
/etc/defaults/rc.conf
violates
POLA. Developers consider
POLA when contemplating user-visible
system changes.
A description of some kind of problem that has been found in either the FreeBSD source or documentation. See Writing FreeBSD Problem Reports.
A number, unique to a particular process on a system, which identifies it and allows actions to be taken against it.
The working title for the NDISulator,
written by Bill Paul, who named it referring to how awful
it is (from a philosophical standpoint) to need to have
something like this in the first place. The
NDISulator is a special compatibility
module to allow Microsoft Windows™ NDIS miniport
network drivers to be used with FreeBSD/i386. This is usually
the only way to use cards where the driver is closed-source.
See src/sys/compat/ndis/subr_ndis.c
.
See Router Advertisement.
See Random Access Memory.
See Received Data.
See Request For Comments.
See Request To Send.
The Revision Control System (RCS) is one of the oldest software suites that implement “revision control” for plain files. It allows the storage, retrieval, archival, logging, identification and merging of multiple revisions for each file. RCS consists of many small tools that work together. It lacks some of the features found in more modern revision control systems, like Git, but it is very simple to install, configure, and start using for a small set of files.
See Also Subversion.
An RS232C pin or wire that data is received on.
See Also Transmitted Data.
A standard for communications between serial devices.
An approach to processor design where the operations the hardware can perform are simplified but made as general purpose as possible. This can lead to lower power consumption, fewer transistors and in some cases, better performance and increased code density. Examples of RISC processors include the Alpha, SPARC®, ARM® and PowerPC®.
A set of documents defining Internet standards, protocols, and so forth. See www.rfc-editor.org.
Also used as a general term when someone has a suggested change and wants feedback.
An RS232C signal requesting that the remote system commences transmission of data.
See Also Clear To Send.
See Signal Ground.
See Server Message Block.
See SMTP Authentication.
See Secure Shell.
See Suspend To RAM.
See Subversion.
An RS232 pin or wire that is the ground reference for the signal.
Subversion is a version control system currently used by the FreeBSD project.
See Transmitted Data.
See Trivial FTP.
See Time Stamp Counter.
A profiling counter internal to modern Pentium® processors that counts core frequency clock ticks.
A protocol that sits on top of (e.g.) the IP protocol and guarantees that packets are delivered in a reliable, ordered, fashion.
The term for the combination of the TCP protocol running over the IP protocol. Much of the Internet runs over TCP/IP.
An RS232C pin or wire that data is transmitted on.
See Also Received Data.
See User ID.
See Universal Serial Bus.
A method of locating a resource, such as a document on the Internet and a means to identify that resource.
The original UNIX® file system, sometimes called the Berkeley Fast File System.
An extension to UFS1, introduced in FreeBSD 5-CURRENT. UFS2 adds 64 bit block pointers (breaking the 1T barrier), support for extended file storage and other features.
A hardware standard used to connect a wide variety of computer peripherals to a universal interface.
A unique number assigned to each user of a computer, by which the resources and permissions assigned to that user can be identified.
A simple, unreliable datagram protocol which is used for exchanging data on a TCP/IP network. UDP does not provide error checking and correction like TCP.
This book is the combined work of hundreds of contributors to “The FreeBSD Documentation Project”. The text is authored in XML according to the DocBook DTD and is formatted from XML into many different presentation formats using XSLT. The printed version of this document would not be possible without Donald Knuth's TeX typesetting language, Leslie Lamport's LaTeX, or Sebastian Rahtz's JadeTeX macro package.