NAME

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

SYNOPSIS

       #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

       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

       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

       pcap(3PCAP), pcap_create(3PCAP), pcap_activate(3PCAP), pcap_open_live(3PCAP)

                                           7 April 2014                   PCAP_FINDALLDEVS(3PCAP)