pcap_lookupnet.3pcap - Man Page

#include <pcap/pcap.h>

char errbuf[PCAP_ERRBUF_SIZE];

int pcap_lookupnet(const char *device, bpf_u_int32 *netp,
    bpf_u_int32 *maskp, char *errbuf);

pcap_lookupnet() is used to determine the IPv4 network number and mask associated with the network device device. Both netp and maskp are bpf_u_int32 pointers. errbuf is a buffer large enough to hold at least PCAP_ERRBUF_SIZE chars.

This function is not available on Windows.  It supports neither IPv6 nor multiple IPv4 addresses per interface, which obviously is not practical in modern networks.  See pcap_findalldevs(3PCAP) for a more elaborate solution to the problem.

pcap_lookupnet() returns 0 on success and PCAP_ERROR on failure. If PCAP_ERROR is returned, errbuf is filled in with an appropriate error message.

pcap(3PCAP)