pcap_findalldevs(3pcap) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | BACKWARD COMPATIBILITY | SEE ALSO | COLOPHON

PCAP_FINDALLDEVS(3PCAP)                          PCAP_FINDALLDEVS(3PCAP)

NAME         top

       pcap_findalldevs, pcap_freealldevs - get a list of capture
       devices, and free that list

SYNOPSIS         top

       #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);

DESCRIPTION         top

       pcap_findalldevs() constructs a list of network devices that can
       be opened with pcap_create(3PCAP) and pcap_activate(3PCAP) or
       with pcap_open_live(3PCAP).  (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

                     PCAP_IF_WIRELESS
                            set if the device is a wireless interface;
                            this includes IrDA as well as radio-based
                            networks such as IEEE 802.15.4 and IEEE
                            802.11, so it doesn't just mean Wi-Fi

                     PCAP_IF_CONNECTION_STATUS
                            a bitmask for an indication of whether the
                            adapter is connected or not; for wireless
                            interfaces, "connected" means "associated
                            with a network"

                     The possible values for the connection status bits
                     are:

                     PCAP_IF_CONNECTION_STATUS_UNKNOWN
                            it's unknown whether the adapter is
                            connected or not

                     PCAP_IF_CONNECTION_STATUS_CONNECTED
                            the adapter is connected

                     PCAP_IF_CONNECTION_STATUS_DISCONNECTED
                            the adapter is disconnected

                     PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE
                            the notion of "connected" and "disconnected"
                            don't apply to this interface; for example,
                            it doesn't apply to a loopback device

       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(3PCAP),
       which frees the list pointed to by alldevs.

RETURN VALUE         top

       pcap_findalldevs() returns 0 on success and PCAP_ERROR on
       failure; as indicated, finding no devices is considered success,
       rather than failure, so 0 will be returned in that case. If
       PCAP_ERROR 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.

BACKWARD COMPATIBILITY         top

       The PCAP_IF_UP and PCAP_IF_RUNNING constants became available in
       libpcap release 1.6.1.  The PCAP_IF_WIRELESS,
       PCAP_IF_CONNECTION_STATUS, PCAP_IF_CONNECTION_STATUS_UNKNOWN,
       PCAP_IF_CONNECTION_STATUS_CONNECTED,
       PCAP_IF_CONNECTION_STATUS_DISCONNECTED, and
       PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE constants became
       available in libpcap release 1.9.0.

SEE ALSO         top

       pcap(3PCAP)

COLOPHON         top

       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 2021-08-27.
       (At that time, the date of the most recent commit that was found
       in the repository was 2021-08-17.)  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

                             23 August 2018      PCAP_FINDALLDEVS(3PCAP)