NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | 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() 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.

RETURN VALUE         top

       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.

SEE ALSO         top

       pcap(3PCAP), pcap_create(3PCAP), pcap_activate(3PCAP),
       pcap_open_live(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 2017-05-03.  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)