SYSTEMD.NETWORK(5) systemd.network SYSTEMD.NETWORK(5)
systemd.network - Network configuration
network.network
Network setup is performed by systemd-networkd(8).
The main network file must have the extension .network; other
extensions are ignored. Networks are applied to links whenever the
links appear.
The .network files are read from the files located in the system
network directory /usr/lib/systemd/network, the volatile runtime
network directory /run/systemd/network and the local administration
network directory /etc/systemd/network. All configuration files are
collectively sorted and processed in lexical order, regardless of the
directories in which they live. However, files with identical
filenames replace each other. Files in /etc have the highest
priority, files in /run take precedence over files with the same name
in /usr/lib. This can be used to override a system-supplied
configuration file with a local file if needed. As a special case, an
empty file (file size 0) or symlink with the same name pointing to
/dev/null disables the configuration file entirely (it is "masked").
Along with the network file foo.network, a "drop-in" directory
foo.network.d/ may exist. All files with the suffix ".conf" from this
directory will be parsed after the file itself is parsed. This is
useful to alter or add configuration settings, without having to
modify the main configuration file. Each drop-in file must have
appropriate section headers.
In addition to /etc/systemd/network, drop-in ".d" directories can be
placed in /usr/lib/systemd/network or /run/systemd/network
directories. Drop-in files in /etc take precedence over those in /run
which in turn take precedence over those in /usr/lib. Drop-in files
under any of these directories take precedence over the main netdev
file wherever located. (Of course, since /run is temporary and
/usr/lib is for vendors, it is unlikely drop-ins should be used in
either of those places.)
Note that an interface without any static IPv6 addresses configured,
and neither DHCPv6 nor IPv6LL enabled, shall be considered to have no
IPv6 support. IPv6 will be automatically disabled for that interface
by writing "1" to /proc/sys/net/ipv6/conf/ifname/disable_ipv6.
The network file contains a "[Match]" section, which determines if a
given network file may be applied to a given device; and a
"[Network]" section specifying how the device should be configured.
The first (in lexical order) of the network files that matches a
given device is applied, all later files are ignored, even if they
match as well.
A network file is said to match a device if each of the entries in
the "[Match]" section matches, or if the section is empty. The
following keys are accepted:
MACAddress=
The hardware address of the interface (use full colon-delimited
hexadecimal, e.g., 01:23:45:67:89:ab).
Path=
A whitespace-separated list of shell-style globs matching the
persistent path, as exposed by the udev property "ID_PATH". If
the list is prefixed with a "!", the test is inverted; i.e. it is
true when "ID_PATH" does not match any item in the list.
Driver=
A whitespace-separated list of shell-style globs matching the
driver currently bound to the device, as exposed by the udev
property "DRIVER" of its parent device, or if that is not set the
driver as exposed by "ethtool -i" of the device itself. If the
list is prefixed with a "!", the test is inverted.
Type=
A whitespace-separated list of shell-style globs matching the
device type, as exposed by the udev property "DEVTYPE". If the
list is prefixed with a "!", the test is inverted.
Name=
A whitespace-separated list of shell-style globs matching the
device name, as exposed by the udev property "INTERFACE". If the
list is prefixed with a "!", the test is inverted.
Host=
Matches against the hostname or machine ID of the host. See
"ConditionHost=" in systemd.unit(5) for details.
Virtualization=
Checks whether the system is executed in a virtualized
environment and optionally test whether it is a specific
implementation. See "ConditionVirtualization=" in systemd.unit(5)
for details.
KernelCommandLine=
Checks whether a specific kernel command line option is set (or
if prefixed with the exclamation mark unset). See
"ConditionKernelCommandLine=" in systemd.unit(5) for details.
Architecture=
Checks whether the system is running on a specific architecture.
See "ConditionArchitecture=" in systemd.unit(5) for details.
The "[Link]" section accepts the following keys:
MACAddress=
The hardware address to set for the device.
MTUBytes=
The maximum transmission unit in bytes to set for the device. The
usual suffixes K, M, G, are supported and are understood to the
base of 1024.
Note that if IPv6 is enabled on the interface, and the MTU is
chosen below 1280 (the minimum MTU for IPv6) it will
automatically be increased to this value.
ARP=
A boolean. Enables or disables the ARP (low-level Address
Resolution Protocol) for this interface. Defaults to unset, which
means that the kernel default will be used.
For example, disabling ARP is useful when creating multiple
MACVLAN or VLAN virtual interfaces atop a single lower-level
physical interface, which will then only serve as a link/"bridge"
device aggregating traffic to the same physical link and not
participate in the network otherwise.
Unmanaged=
A boolean. When "yes", no attempts are made to bring up or
configure matching links, equivalent to when there are no
matching network files. Defaults to "no".
This is useful for preventing later matching network files from
interfering with certain interfaces that are fully controlled by
other applications.
The "[Network]" section accepts the following keys:
Description=
A description of the device. This is only used for presentation
purposes.
DHCP=
Enables DHCPv4 and/or DHCPv6 client support. Accepts "yes", "no",
"ipv4", or "ipv6".
Note that DHCPv6 will by default be triggered by Router
Advertisement, if that is enabled, regardless of this parameter.
By enabling DHCPv6 support explicitly, the DHCPv6 client will be
started regardless of the presence of routers on the link, or
what flags the routers pass. See "IPv6AcceptRA=".
Furthermore, note that by default the domain name specified
through DHCP is not used for name resolution. See option
UseDomains= below.
See the "[DHCP]" section below for further configuration options
for the DHCP client support.
DHCPServer=
A boolean. Enables DHCPv4 server support. Defaults to "no".
Further settings for the DHCP server may be set in the
"[DHCPServer]" section described below.
LinkLocalAddressing=
Enables link-local address autoconfiguration. Accepts "yes",
"no", "ipv4", or "ipv6". Defaults to "ipv6".
IPv4LLRoute=
A boolean. When true, sets up the route needed for non-IPv4LL
hosts to communicate with IPv4LL-only hosts. Defaults to false.
IPv6Token=
An IPv6 address with the top 64 bits unset. When set, indicates
the 64-bit interface part of SLAAC IPv6 addresses for this link.
Note that the token is only ever used for SLAAC, and not for
DHCPv6 addresses, even in the case DHCP is requested by router
advertisement. By default, the token is autogenerated.
LLMNR=
A boolean or "resolve". When true, enables Link-Local Multicast
Name Resolution[1] on the link. When set to "resolve", only
resolution is enabled, but not host registration and
announcement. Defaults to true. This setting is read by
systemd-resolved.service(8).
MulticastDNS=
A boolean or "resolve". When true, enables Multicast DNS[2]
support on the link. When set to "resolve", only resolution is
enabled, but not host or service registration and announcement.
Defaults to false. This setting is read by
systemd-resolved.service(8).
DNSSEC=
A boolean or "allow-downgrade". When true, enables DNSSEC[3] DNS
validation support on the link. When set to "allow-downgrade",
compatibility with non-DNSSEC capable networks is increased, by
automatically turning off DNSEC in this case. This option defines
a per-interface setting for resolved.conf(5)'s global DNSSEC=
option. Defaults to false. This setting is read by
systemd-resolved.service(8).
DNSSECNegativeTrustAnchors=
A space-separated list of DNSSEC negative trust anchor domains.
If specified and DNSSEC is enabled, look-ups done via the
interface's DNS server will be subject to the list of negative
trust anchors, and not require authentication for the specified
domains, or anything below it. Use this to disable DNSSEC
authentication for specific private domains, that cannot be
proven valid using the Internet DNS hierarchy. Defaults to the
empty list. This setting is read by systemd-resolved.service(8).
LLDP=
Controls support for Ethernet LLDP packet reception. LLDP is a
link-layer protocol commonly implemented on professional routers
and bridges which announces which physical port a system is
connected to, as well as other related data. Accepts a boolean or
the special value "routers-only". When true, incoming LLDP
packets are accepted and a database of all LLDP neighbors
maintained. If "routers-only" is set only LLDP data of various
types of routers is collected and LLDP data about other types of
devices ignored (such as stations, telephones and others). If
false, LLDP reception is disabled. Defaults to "routers-only".
Use networkctl(1) to query the collected neighbor data. LLDP is
only available on Ethernet links. See EmitLLDP= below for
enabling LLDP packet emission from the local system.
EmitLLDP=
Controls support for Ethernet LLDP packet emission. Accepts a
boolean parameter or the special values "nearest-bridge",
"non-tpmr-bridge" and "customer-bridge". Defaults to false, which
turns off LLDP packet emission. If not false, a short LLDP packet
with information about the local system is sent out in regular
intervals on the link. The LLDP packet will contain information
about the local host name, the local machine ID (as stored in
machine-id(5)) and the local interface name, as well as the
pretty hostname of the system (as set in machine-info(5)). LLDP
emission is only available on Ethernet links. Note that this
setting passes data suitable for identification of host to the
network and should thus not be enabled on untrusted networks,
where such identification data should not be made available. Use
this option to permit other systems to identify on which
interfaces they are connected to this system. The three special
values control propagation of the LLDP packets. The
"nearest-bridge" setting permits propagation only to the nearest
connected bridge, "non-tpmr-bridge" permits propagation across
Two-Port MAC Relays, but not any other bridges, and
"customer-bridge" permits propagation until a customer bridge is
reached. For details about these concepts, see IEEE
802.1AB-2009[4]. Note that configuring this setting to true is
equivalent to "nearest-bridge", the recommended and most
restricted level of propagation. See LLDP= above for an option to
enable LLDP reception.
BindCarrier=
A link name or a list of link names. When set, controls the
behavior of the current link. When all links in the list are in
an operational down state, the current link is brought down. When
at least one link has carrier, the current interface is brought
up.
Address=
A static IPv4 or IPv6 address and its prefix length, separated by
a "/" character. Specify this key more than once to configure
several addresses. The format of the address must be as described
in inet_pton(3). This is a short-hand for an [Address] section
only containing an Address key (see below). This option may be
specified more than once.
If the specified address is 0.0.0.0 (for IPv4) or [::] (for
IPv6), a new address range of the requested size is automatically
allocated from a system-wide pool of unused ranges. The allocated
range is checked against all current network interfaces and all
known network configuration files to avoid address range
conflicts. The default system-wide pool consists of
192.168.0.0/16, 172.16.0.0/12 and 10.0.0.0/8 for IPv4, and
fc00::/7 for IPv6. This functionality is useful to manage a large
number of dynamically created network interfaces with the same
network configuration and automatic address range assignment.
Gateway=
The gateway address, which must be in the format described in
inet_pton(3). This is a short-hand for a [Route] section only
containing a Gateway key. This option may be specified more than
once.
DNS=
A DNS server address, which must be in the format described in
inet_pton(3). This option may be specified more than once. This
setting is read by systemd-resolved.service(8).
Domains=
A list of domains which should be resolved using the DNS servers
on this link. Each item in the list should be a domain name,
optionally prefixed with a tilde ("~"). The domains with the
prefix are called "routing-only domains". The domains without the
prefix are called "search domains" and are first used as search
suffixes for extending single-label host names (host names
containing no dots) to become fully qualified domain names
(FQDNs). If a single-label host name is resolved on this
interface, each of the specified search domains are appended to
it in turn, converting it into a fully qualified domain name,
until one of them may be successfully resolved.
Both "search" and "routing-only" domains are used for routing of
DNS queries: look-ups for host names ending in those domains
(hence also single label names, if any "search domains" are
listed), are routed to the DNS servers configured for this
interface. The domain routing logic is particularly useful on
multi-homed hosts with DNS servers serving particular private DNS
zones on each interface.
The "routing-only" domain "~." (the tilde indicating definition
of a routing domain, the dot referring to the DNS root domain
which is the implied suffix of all valid DNS names) has special
effect. It causes all DNS traffic which does not match another
configured domain routing entry to be routed to DNS servers
specified for this interface. This setting is useful to prefer a
certain set of DNS servers if a link on which they are connected
is available.
This setting is read by systemd-resolved.service(8). "Search
domains" correspond to the domain and search entries in
resolv.conf(5). Domain name routing has no equivalent in the
traditional glibc API, which has no concept of domain name
servers limited to a specific link.
NTP=
An NTP server address. This option may be specified more than
once. This setting is read by systemd-timesyncd.service(8).
IPForward=
Configures IP packet forwarding for the system. If enabled,
incoming packets on any network interface will be forwarded to
any other interfaces according to the routing table. Takes either
a boolean argument, or the values "ipv4" or "ipv6", which only
enable IP packet forwarding for the specified address family.
This controls the net.ipv4.ip_forward and
net.ipv6.conf.all.forwarding sysctl options of the network
interface (see ip-sysctl.txt[5] for details about sysctl
options). Defaults to "no".
Note: this setting controls a global kernel option, and does so
one way only: if a network that has this setting enabled is set
up the global setting is turned on. However, it is never turned
off again, even after all networks with this setting enabled are
shut down again.
To allow IP packet forwarding only between specific network
interfaces use a firewall.
IPMasquerade=
Configures IP masquerading for the network interface. If enabled,
packets forwarded from the network interface will be appear as
coming from the local host. Takes a boolean argument. Implies
IPForward=ipv4. Defaults to "no".
IPv6PrivacyExtensions=
Configures use of stateless temporary addresses that change over
time (see RFC 4941[6], Privacy Extensions for Stateless Address
Autoconfiguration in IPv6). Takes a boolean or the special values
"prefer-public" and "kernel". When true, enables the privacy
extensions and prefers temporary addresses over public addresses.
When "prefer-public", enables the privacy extensions, but prefers
public addresses over temporary addresses. When false, the
privacy extensions remain disabled. When "kernel", the kernel's
default setting will be left in place. Defaults to "no".
IPv6AcceptRA=
Enable or disable IPv6 Router Advertisement (RA) reception
support for the interface. Takes a boolean parameter. If true,
RAs are accepted; if false, RAs are ignored, independently of the
local forwarding state. When not set, the kernel default is used,
and RAs are accepted only when local forwarding is disabled for
that interface. When RAs are accepted, they may trigger the start
of the DHCPv6 client if the relevant flags are set in the RA
data, or if no routers are found on the link.
Further settings for the IPv6 RA support may be configured in the
"[IPv6AcceptRA]" section, see below.
Also see ip-sysctl.txt[5] in the kernel documentation regarding
"accept_ra", but note that systemd's setting of 1 (i.e. true)
corresponds to kernel's setting of 2.
IPv6DuplicateAddressDetection=
Configures the amount of IPv6 Duplicate Address Detection (DAD)
probes to send. Defaults to unset.
IPv6HopLimit=
Configures IPv6 Hop Limit. For each router that forwards the
packet, the hop limit is decremented by 1. When the hop limit
field reaches zero, the packet is discarded. Defaults to unset.
IPv4ProxyARP=
A boolean. Configures proxy ARP for IPv4. Proxy ARP is the
technique in which one host, usually a router, answers ARP
requests intended for another machine. By "faking" its identity,
the router accepts responsibility for routing packets to the
"real" destination. (see RFC 1027[7]. Defaults to unset.
IPv6ProxyNDP=
A boolean. Configures proxy NDP for IPv6. Proxy NDP (Neighbor
Discovery Protocol) is a technique for IPv6 to allow routing of
addresses to a different destination when peers expect them to be
present on a certain physical link. In this case a router answers
Neighbour Advertisement messages intended for another machine by
offering its own MAC address as destination. Unlike proxy ARP for
IPv4, it is not enabled globally, but will only send Neighbour
Advertisement messages for addresses in the IPv6 neighbor proxy
table, which can also be shown by ip -6 neighbour show proxy.
systemd-networkd will control the per-interface `proxy_ndp`
switch for each configured interface depending on this option.
Defautls to unset.
IPv6ProxyNDPAddress=
An IPv6 address, for which Neighbour Advertisement messages will
be proxied. This option may be specified more than once.
systemd-networkd will add the IPv6ProxyNDPAddress= entries to the
kernel's IPv6 neighbor proxy table. This option implies
IPv6ProxyNDP=true but has no effect if IPv6ProxyNDP has been set
to false. Defaults to unset.
Bridge=
The name of the bridge to add the link to. See systemd.netdev(5).
Bond=
The name of the bond to add the link to. See systemd.netdev(5).
VRF=
The name of the VRF to add the link to. See systemd.netdev(5).
VLAN=
The name of a VLAN to create on the link. See systemd.netdev(5).
This option may be specified more than once.
MACVLAN=
The name of a MACVLAN to create on the link. See
systemd.netdev(5). This option may be specified more than once.
VXLAN=
The name of a VXLAN to create on the link. See systemd.netdev(5).
This option may be specified more than once.
Tunnel=
The name of a Tunnel to create on the link. See
systemd.netdev(5). This option may be specified more than once.
An "[Address]" section accepts the following keys. Specify several
"[Address]" sections to configure several addresses.
Address=
As in the "[Network]" section. This key is mandatory.
Peer=
The peer address in a point-to-point connection. Accepts the same
format as the "Address" key.
Broadcast=
The broadcast address, which must be in the format described in
inet_pton(3). This key only applies to IPv4 addresses. If it is
not given, it is derived from the "Address" key.
Label=
An address label.
PreferredLifetime=
Allows the default "preferred lifetime" of the address to be
overridden. Only three settings are accepted: "forever" or
"infinity" which is the default and means that the address never
expires, and "0" which means that the address is considered
immediately "expired" and will not be used, unless explicitly
requested. A setting of PreferredLifetime=0 is useful for
addresses which are added to be used only by a specific
application, which is then configured to use them explicitly.
HomeAddress=
Takes a boolean argument. Designates this address the "home
address" as defined in RFC 6275[8]. Supported only on IPv6.
Defaults to false.
DuplicateAddressDetection=
Takes a boolean argument. Do not perform Duplicate Address
Detection RFC 4862[9] when adding this address. Supported only on
IPv6. Defaults to false.
ManageTemporaryAddress=
Takes a boolean argument. If true the kernel manage temporary
addresses created from this one as template on behalf of Privacy
Extensions RFC 3041[10]. For this to become active, the
use_tempaddr sysctl setting has to be set to a value greater than
zero. The given address needs to have a prefix length of 64. This
flag allows to use privacy extensions in a manually configured
network, just like if stateless auto-configuration was active.
Defaults to false.
PrefixRoute=
Takes a boolean argument. When adding or modifying an IPv6
address, the userspace application needs a way to suppress adding
a prefix route. This is for example relevant together with
IFA_F_MANAGERTEMPADDR, where userspace creates autoconf generated
addresses, but depending on on-link, no route for the prefix
should be added. Defaults to false.
AutoJoin=
Takes a boolean argument. Joining multicast group on ethernet
level via ip maddr command would not work if we have an Ethernet
switch that does IGMP snooping since the switch would not
replicate multicast packets on ports that did not have IGMP
reports for the multicast addresses. Linux vxlan interfaces
created via ip link add vxlan or networkd's netdev kind vxlan
have the group option that enables then to do the required join.
By extending ip address command with option "autojoin" we can get
similar functionality for openvswitch (OVS) vxlan interfaces as
well as other tunneling mechanisms that need to receive multicast
traffic. Defaults to "no".
An "[IPv6AddressLabel]" section accepts the following keys. Specify
several "[IPv6AddressLabel]" sections to configure several addresse
labels. IPv6 address labels are used for address selection. See RFC
3484[11]. Precedence is managed by userspace, and only the label
itself is stored in the kernel
Label=
The label for the prefix (an unsigned integer) ranges 0 to
4294967294. 0xffffffff is reserved. This key is mandatory.
Prefix=
IPv6 prefix is an address with a prefix length, separated by a
slash "/" character. This key is mandatory.
The "[Route]" section accepts the following keys. Specify several
"[Route]" sections to configure several routes.
Gateway=
As in the "[Network]" section.
GatewayOnlink=
The "GatewayOnlink" option tells the kernel that it does not have
to check if the gateway is reachable directly by the current
machine (i.e., the kernel does not need to check if the gateway
is attached to the local network), so that we can insert the
route in the kernel table without it being complained about. A
boolean, defaults to "no".
Destination=
The destination prefix of the route. Possibly followed by a slash
and the prefix length. If omitted, a full-length host route is
assumed.
Source=
The source prefix of the route. Possibly followed by a slash and
the prefix length. If omitted, a full-length host route is
assumed.
Metric=
The metric of the route (an unsigned integer).
IPv6Preference=
Specifies the route preference as defined in RFC4191[12] for
Router Discovery messages. Which can be one of "low" the route
has a lowest priority, "medium" the route has a default priority
or "high" the route has a highest priority.
Scope=
The scope of the route, which can be "global", "link" or "host".
Defaults to "global".
PreferredSource=
The preferred source address of the route. The address must be in
the format described in inet_pton(3).
Table=num
The table identifier for the route (a number between 1 and
4294967295, or 0 to unset). The table can be retrieved using ip
route show table num.
Protocol=
The Protocol identifier for the route. Takes a number between 0
and 255 or the special values "kernel", "boot" and "static".
Defaults to "static".
The "[DHCP]" section configures the DHCPv4 and DHCP6 client, if it is
enabled with the DHCP= setting described above:
UseDNS=
When true (the default), the DNS servers received from the DHCP
server will be used and take precedence over any statically
configured ones.
This corresponds to the nameserver option in resolv.conf(5).
UseNTP=
When true (the default), the NTP servers received from the DHCP
server will be used by systemd-timesyncd and take precedence over
any statically configured ones.
UseMTU=
When true, the interface maximum transmission unit from the DHCP
server will be used on the current link. Defaults to false.
SendHostname=
When true (the default), the machine's hostname will be sent to
the DHCP server.
UseHostname=
When true (the default), the hostname received from the DHCP
server will be set as the transient hostname of the system
Hostname=
Use this value for the hostname which is sent to the DHCP server,
instead of machine's hostname.
UseDomains=
Takes a boolean argument, or the special value "route". When
true, the domain name received from the DHCP server will be used
as DNS search domain over this link, similar to the effect of the
Domains= setting. If set to "route", the domain name received
from the DHCP server will be used for routing DNS queries only,
but not for searching, similar to the effect of the Domains=
setting when the argument is prefixed with "~". Defaults to
false.
It is recommended to enable this option only on trusted networks,
as setting this affects resolution of all host names, in
particular of single-label names. It is generally safer to use
the supplied domain only as routing domain, rather than as search
domain, in order to not have it affect local resolution of
single-label names.
When set to true, this setting corresponds to the domain option
in resolv.conf(5).
UseRoutes=
When true (the default), the static routes will be requested from
the DHCP server and added to the routing table with a metric of
1024, and a scope of "global", "link" or "host", depending on the
route's destination and gateway. If the destination is on the
local host, e.g., 127.x.x.x, or the same as the link's own
address, the scope will be set to "host". Otherwise if the
gateway is null (a direct route), a "link" scope will be used.
For anything else, scope defaults to "global".
UseTimezone=
When true, the timezone received from the DHCP server will be set
as timezone of the local system. Defaults to "no".
CriticalConnection=
When true, the connection will never be torn down even if the
DHCP lease expires. This is contrary to the DHCP specification,
but may be the best choice if, say, the root filesystem relies on
this connection. Defaults to false.
ClientIdentifier=
The DHCPv4 client identifier to use. Either "mac" to use the MAC
address of the link or "duid" (the default, see below) to use an
RFC4361-compliant Client ID.
VendorClassIdentifier=
The vendor class identifier used to identify vendor type and
configuration.
DUIDType=
Override the global DUIDType setting for this network. See
networkd.conf(5) for a description of possible values.
DUIDRawData=
Override the global DUIDRawData setting for this network. See
networkd.conf(5) for a description of possible values.
IAID=
The DHCP Identity Association Identifier (IAID) for the
interface, a 32-bit unsigned integer.
RequestBroadcast=
Request the server to use broadcast messages before the IP
address has been configured. This is necessary for devices that
cannot receive RAW packets, or that cannot receive packets at all
before an IP address has been configured. On the other hand, this
must not be enabled on networks where broadcasts are filtered
out.
RouteMetric=
Set the routing metric for routes specified by the DHCP server.
RouteTable=num
The table identifier for DHCP routes (a number between 1 and
4294967295, or 0 to unset). The table can be retrieved using ip
route show table num.
ListenPort=
Allow setting custom port for the DHCP client to listen on.
The "[IPv6AcceptRA]" section configures the IPv6 Router Advertisement
(RA) client, if it is enabled with the IPv6AcceptRA= setting
described above:
UseDNS=
When true (the default), the DNS servers received in the Router
Advertisement will be used and take precedence over any
statically configured ones.
This corresponds to the nameserver option in resolv.conf(5).
UseDomains=
Takes a boolean argument, or the special value "route". When
true, the domain name received via IPv6 Router Advertisement (RA)
will be used as DNS search domain over this link, similar to the
effect of the Domains= setting. If set to "route", the domain
name received via IPv6 RA will be used for routing DNS queries
only, but not for searching, similar to the effect of the
Domains= setting when the argument is prefixed with "~". Defaults
to false.
It is recommended to enable this option only on trusted networks,
as setting this affects resolution of all host names, in
particular of single-label names. It is generally safer to use
the supplied domain only as routing domain, rather than as search
domain, in order to not have it affect local resolution of
single-label names.
When set to true, this setting corresponds to the domain option
in resolv.conf(5).
RouteTable=num
The table identifier for the routes received in the Router
Advertisement (a number between 1 and 4294967295, or 0 to unset).
The table can be retrieved using ip route show table num.
The "[DHCPServer]" section contains settings for the DHCP server, if
enabled via the DHCPServer= option described above:
PoolOffset=, PoolSize=
Configures the pool of addresses to hand out. The pool is a
contiguous sequence of IP addresses in the subnet configured for
the server address, which does not include the subnet nor the
broadcast address. PoolOffset= takes the offset of the pool from
the start of subnet, or zero to use the default value. PoolSize=
takes the number of IP addresses in the pool or zero to use the
default value. By default, the pool starts at the first address
after the subnet address and takes up the rest of the subnet,
excluding the broadcast address. If the pool includes the server
address (the default), this is reserved and not handed out to
clients.
DefaultLeaseTimeSec=, MaxLeaseTimeSec=
Control the default and maximum DHCP lease time to pass to
clients. These settings take time values in seconds or another
common time unit, depending on the suffix. The default lease time
is used for clients that did not ask for a specific lease time.
If a client asks for a lease time longer than the maximum lease
time, it is automatically shortened to the specified time. The
default lease time defaults to 1h, the maximum lease time to 12h.
Shorter lease times are beneficial if the configuration data in
DHCP leases changes frequently and clients shall learn the new
settings with shorter latencies. Longer lease times reduce the
generated DHCP network traffic.
EmitDNS=, DNS=
Configures whether the DHCP leases handed out to clients shall
contain DNS server information. The EmitDNS= setting takes a
boolean argument and defaults to "yes". The DNS servers to pass
to clients may be configured with the DNS= option, which takes a
list of IPv4 addresses. If the EmitDNS= option is enabled but no
servers configured, the servers are automatically propagated from
an "uplink" interface that has appropriate servers set. The
"uplink" interface is determined by the default route of the
system with the highest priority. Note that this information is
acquired at the time the lease is handed out, and does not take
uplink interfaces into account that acquire DNS or NTP server
information at a later point. DNS server propagation does not
take /etc/resolv.conf into account. Also, note that the leases
are not refreshed if the uplink network configuration changes. To
ensure clients regularly acquire the most current uplink DNS
server information, it is thus advisable to shorten the DHCP
lease time via MaxLeaseTimeSec= described above.
EmitNTP=, NTP=
Similar to the EmitDNS= and DNS= settings described above, these
settings configure whether and what NTP server information shall
be emitted as part of the DHCP lease. The same syntax,
propagation semantics and defaults apply as for EmitDNS= and
DNS=.
EmitRouter=
Similar to the EmitDNS= setting described above, this setting
configures whether the DHCP lease should contain the router
option. The same syntax, propagation semantics and defaults apply
as for EmitDNS=.
EmitTimezone=, Timezone=
Configures whether the DHCP leases handed out to clients shall
contain timezone information. The EmitTimezone= setting takes a
boolean argument and defaults to "yes". The Timezone= setting
takes a timezone string (such as "Europe/Berlin" or "UTC") to
pass to clients. If no explicit timezone is set, the system
timezone of the local host is propagated, as determined by the
/etc/localtime symlink.
The "[Bridge]" section accepts the following keys.
UnicastFlood=
A boolean. Controls whether the bridge should flood traffic for
which an FDB entry is missing and the destination is unknown
through this port. Defaults to on.
HairPin=
A boolean. Configures whether traffic may be sent back out of the
port on which it was received. By default, this flag is false,
and the bridge will not forward traffic back out of the receiving
port.
UseBPDU=
A boolean. Configures whether STP Bridge Protocol Data Units will
be processed by the bridge port. Defaults to yes.
FastLeave=
A boolean. This flag allows the bridge to immediately stop
multicast traffic on a port that receives an IGMP Leave message.
It is only used with IGMP snooping if enabled on the bridge.
Defaults to off.
AllowPortToBeRoot=
A boolean. Configures whether a given port is allowed to become a
root port. Only used when STP is enabled on the bridge. Defaults
to on.
Cost=
Sets the "cost" of sending packets of this interface. Each port
in a bridge may have a different speed and the cost is used to
decide which link to use. Faster interfaces should have lower
costs. It is an interger value between 1 and 65535.
Priority=
Sets the "priority" of sending packets on this interface. Each
port in a bridge may have a different priority which is used to
decide which link to use. Lower value means higher priority. It
is an interger value between 0 to 63. Networkd does not set any
default, meaning the kernel default value of 32 is used.
The "[BridgeFDB]" section manages the forwarding database table of a
port and accepts the following keys. Specify several "[BridgeFDB]"
sections to configure several static MAC table entries.
MACAddress=
As in the "[Network]" section. This key is mandatory.
VLANId=
The VLAN ID for the new static MAC table entry. If omitted, no
VLAN ID info is appended to the new static MAC table entry.
The "[BridgeVLAN]" section manages the VLAN ID configuration of a
bridge port and accepts the following keys. Specify several
"[BridgeVLAN]" sections to configure several VLAN entries. The
VLANFiltering= option has to be enabled, see "[Bridge]" section in
systemd.netdev(5).
VLAN=
The VLAN ID allowed on the port. This can be either a single ID
or a range M-N. VLAN IDs are valid from 1 to 4094.
EgressUntagged=
The VLAN ID specified here will be used to untag frames on
egress. Configuring EgressUntagged= implicates the use of VLAN=
above and will enable the VLAN ID for ingress as well. This can
be either a single ID or a range M-N.
PVID=
The Port VLAN ID specified here is assigned to all untagged
frames at ingress. PVID= can be used only once. Configuring
PVID= implicates the use of VLAN= above and will enable the VLAN
ID for ingress as well.
Example 1. Static network configuration
# /etc/systemd/network/50-static.network
[Match]
Name=enp2s0
[Network]
Address=192.168.0.15/24
Gateway=192.168.0.1
This brings interface "enp2s0" up with a static address. The
specified gateway will be used for a default route.
Example 2. DHCP on ethernet links
# /etc/systemd/network/80-dhcp.network
[Match]
Name=en*
[Network]
DHCP=yes
This will enable DHCPv4 and DHCPv6 on all interfaces with names
starting with "en" (i.e. ethernet interfaces).
Example 3. A bridge with two enslaved links
# /etc/systemd/network/25-bridge-static.network
[Match]
Name=bridge0
[Network]
Address=192.168.0.15/24
Gateway=192.168.0.1
DNS=192.168.0.1
# /etc/systemd/network/25-bridge-slave-interface-1.network
[Match]
Name=enp2s0
[Network]
Bridge=bridge0
# /etc/systemd/network/25-bridge-slave-interface-2.network
[Match]
Name=wlp3s0
[Network]
Bridge=bridge0
This creates a bridge and attaches devices "enp2s0" and "wlp3s0" to
it. The bridge will have the specified static address and network
assigned, and a default route via the specified gateway will be
added. The specified DNS server will be added to the global list of
DNS resolvers.
Example 4.
# /etc/systemd/network/20-bridge-slave-interface-vlan.network
[Match]
Name=enp2s0
[Network]
Bridge=bridge0
[BridgeVLAN]
VLAN=1-32
PVID=42
EgressUntagged=42
[BridgeVLAN]
VLAN=100-200
[BridgeVLAN]
EgressUntagged=300-400
This overrides the configuration specified in the previous example
for the interface "enp2s0", and enables VLAN on that bridge port.
VLAN IDs 1-32, 42, 100-400 will be allowed. Packets tagged with VLAN
IDs 42, 300-400 will be untagged when they leave on this interface.
Untagged packets which arrive on this interface will be assigned VLAN
ID 42.
Example 5. Various tunnels
/etc/systemd/network/25-tunnels.network
[Match]
Name=ens1
[Network]
Tunnel=ipip-tun
Tunnel=sit-tun
Tunnel=gre-tun
Tunnel=vti-tun
/etc/systemd/network/25-tunnel-ipip.netdev
[NetDev]
Name=ipip-tun
Kind=ipip
/etc/systemd/network/25-tunnel-sit.netdev
[NetDev]
Name=sit-tun
Kind=sit
/etc/systemd/network/25-tunnel-gre.netdev
[NetDev]
Name=gre-tun
Kind=gre
/etc/systemd/network/25-tunnel-vti.netdev
[NetDev]
Name=vti-tun
Kind=vti
This will bring interface "ens1" up and create an IPIP tunnel, a SIT
tunnel, a GRE tunnel, and a VTI tunnel using it.
Example 6. A bond device
# /etc/systemd/network/30-bond1.network
[Match]
Name=bond1
[Network]
DHCP=ipv6
# /etc/systemd/network/30-bond1.netdev
[NetDev]
Name=bond1
Kind=bond
# /etc/systemd/network/30-bond1-dev1.network
[Match]
MACAddress=52:54:00:e9:64:41
[Network]
Bond=bond1
# /etc/systemd/network/30-bond1-dev2.network
[Match]
MACAddress=52:54:00:e9:64:42
[Network]
Bond=bond1
This will create a bond device "bond1" and enslave the two devices
with MAC addresses 52:54:00:e9:64:41 and 52:54:00:e9:64:42 to it.
IPv6 DHCP will be used to acquire an address.
Example 7. Virtual Routing and Forwarding (VRF)
Add the "bond1" interface to the VRF master interface "vrf1". This
will redirect routes generated on this interface to be within the
routing table defined during VRF creation. Traffic won't be
redirected towards the VRFs routing table unless specific ip-rules
are added.
# /etc/systemd/network/25-vrf.network
[Match]
Name=bond1
[Network]
VRF=vrf1
Example 8. MacVTap
This brings up a network interface "macvtap-test" and attaches it to
"enp0s25".
# /usr/lib/systemd/network/25-macvtap.network
[Match]
Name=enp0s25
[Network]
MACVTAP=macvtap-test
systemd(1), systemd-networkd.service(8), systemd.link(5),
systemd.netdev(5), systemd-resolved.service(8)
1. Link-Local Multicast Name Resolution
https://tools.ietf.org/html/rfc4795
2. Multicast DNS
https://tools.ietf.org/html/rfc6762
3. DNSSEC
https://tools.ietf.org/html/rfc4033
4. IEEE 802.1AB-2009
http://standards.ieee.org/getieee802/download/802.1AB-2009.pdf
5. ip-sysctl.txt
https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt
6. RFC 4941
https://tools.ietf.org/html/rfc4941
7. RFC 1027
https://tools.ietf.org/html/rfc1027
8. RFC 6275
https://tools.ietf.org/html/rfc6275
9. RFC 4862
https://tools.ietf.org/html/rfc4862
10. RFC 3041
https://tools.ietf.org/html/rfc3041
11. RFC 3484
https://tools.ietf.org/html/rfc3484
12. RFC4191
https://tools.ietf.org/html/rfc4191
This page is part of the systemd (systemd system and service manager)
project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a bug
report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩. This
page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2017-07-05. If you dis‐
cover any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page, or
you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
systemd 234 SYSTEMD.NETWORK(5)
Pages that refer to this page: networkctl(1), dnssec-trust-anchors.d(5), networkd.conf(5), systemd.link(5), systemd.netdev(5), systemd.directives(7), systemd.index(7), systemd-networkd.service(8), systemd-resolved.service(8), systemd-timesyncd.service(8)