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PCAP_FINDALLDEVS(3PCAP)                                                              PCAP_FINDALLDEVS(3PCAP)



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 ele-ment element
       ment 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

       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 corre-sponding corresponding
                     sponding 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 cor-responding corresponding
                     responding to the address pointed to by addr; may be null if the device isn't a  point-to-point pointto-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  inter-preting interpreting
       preting 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(), whch 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  con-sidered considered
       sidered  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)



                                               22 August 2010                        PCAP_FINDALLDEVS(3PCAP)