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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO | COLOPHON |
PCAP_FINDALLDEVS(3PCAP) PCAP_FINDALLDEVS(3PCAP)
pcap_findalldevs, pcap_freealldevs - get a list of capture devices,
and free that list
#include <pcap/pcap.h>
char errbuf[PCAP_ERRBUF_SIZE];
int pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf);
void pcap_freealldevs(pcap_if_t *alldevs);
pcap_findalldevs() constructs a list of network devices that can be
opened with pcap_create() and pcap_activate() or with
pcap_open_live(). (Note that there may be network devices that
cannot be opened by the process calling pcap_findalldevs(), because,
for example, that process does not have sufficient privileges to open
them for capturing; if so, those devices will not appear on the
list.) If pcap_findalldevs() succeeds, the pointer pointed to by
alldevsp is set to point to the first element of the list, or to NULL
if no devices were found (this is considered success). Each element
of the list is of type pcap_if_t, and has the following members:
next if not NULL, a pointer to the next element in the list;
NULL for the last element of the list
name a pointer to a string giving a name for the device to
pass to pcap_open_live()
description
if not NULL, a pointer to a string giving a human-
readable description of the device
addresses
a pointer to the first element of a list of network
addresses for the device, or NULL if the device has no
addresses
flags device flags:
PCAP_IF_LOOPBACK
set if the device is a loopback interface
PCAP_IF_UP
set if the device is up
PCAP_IF_RUNNING
set if the device is running
Each element of the list of addresses is of type pcap_addr_t, and has
the following members:
next if not NULL, a pointer to the next element in the list;
NULL for the last element of the list
addr a pointer to a struct sockaddr containing an address
netmask
if not NULL, a pointer to a struct sockaddr that
contains the netmask corresponding to the address
pointed to by addr
broadaddr
if not NULL, a pointer to a struct sockaddr that
contains the broadcast address corresponding to the
address pointed to by addr; may be null if the device
doesn't support broadcasts
dstaddr
if not NULL, a pointer to a struct sockaddr that
contains the destination address corresponding to the
address pointed to by addr; may be null if the device
isn't a point-to-point interface
Note that the addresses in the list of addresses might be IPv4
addresses, IPv6 addresses, or some other type of addresses, so you
must check the sa_family member of the struct sockaddr before
interpreting the contents of the address; do not assume that the
addresses are all IPv4 addresses, or even all IPv4 or IPv6 addresses.
IPv4 addresses have the value AF_INET, IPv6 addresses have the value
AF_INET6 (which older operating systems that don't support IPv6 might
not define), and other addresses have other values. Whether other
addresses are returned, and what types they might have is platform-
dependent. For IPv4 addresses, the struct sockaddr pointer can be
interpreted as if it pointed to a struct sockaddr_in; for IPv6
addresses, it can be interpreted as if it pointed to a struct
sockaddr_in6.
The list of devices must be freed with pcap_freealldevs(), which
frees the list pointed to by alldevs.
pcap_findalldevs() returns 0 on success and -1 on failure; as
indicated, finding no devices is considered success, rather than
failure, so 0 will be returned in that case. If -1 is returned,
errbuf is filled in with an appropriate error message. errbuf is
assumed to be able to hold at least PCAP_ERRBUF_SIZE chars.
pcap(3PCAP), pcap_create(3PCAP), pcap_activate(3PCAP),
pcap_open_live(3PCAP)
This page is part of the libpcap (packet capture library) project.
Information about the project can be found at
⟨http://www.tcpdump.org/⟩. If you have a bug report for this manual
page, see ⟨http://www.tcpdump.org/#patches⟩. This page was obtained
from the project's upstream Git repository
⟨https://github.com/the-tcpdump-group/libpcap.git⟩ on 2017-07-05. If
you discover 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
7 April 2014 PCAP_FINDALLDEVS(3PCAP)