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(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

       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

       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

       pcap(3PCAP)

                                                 23 August 2018                          PCAP_FINDALLDEVS(3PCAP)