Manual Pages  — PCAP_LOOKUPDEV

#include <pcap/pcap.h>

char errbuf[PCAP_ERRBUF_SIZE];

[DEPRECATED] char *pcap_lookupdev(char *errbuf);

This interface is obsoleted by pcap_findalldevs(3). To find a default device on which to capture, call pcap_findalldevs() and, if the list it returns is not empty, use the first device in the list. (If the list is empty, there are no devices on which capture is possible.) errbuf is a buffer large enough to hold at least PCAP_ERRBUF_SIZE chars.

If pcap_init(3) has been called, this interface always returns NULL.

pcap_lookupdev() returns a pointer to a string giving the name of a network device suitable for use with pcap_create(3) and  pcap_activate(3), or with pcap_open_live(3), and with pcap_lookupnet(3). If there is an error, or if pcap_init(3) has been called, NULL is returned and errbuf is filled in with an appropriate error message.

pcap(3)