pcap_set_timeout.3pcap man page
pcap_set_timeout — set the read timeout for a not-yet-activated capture handle
#include <pcap/pcap.h> int pcap_set_timeout(pcap_t *p, int to_ms);
pcap_set_timeout() sets the read timeout that will be used on a capture handle when the handle is activated to to_ms, which is in units of milliseconds.
The behavior, if the timeout isn't specified, is undefined. We recommend always setting the timeout to a non-zero value unless immediate mode is set, in which case the timeout has no effect.
pcap_set_timeout() returns 0 on success or PCAP_ERROR_ACTIVATED if called on a capture handle that has been activated.
pcap(3PCAP), pcap_create(3PCAP), pcap_activate(3PCAP), pcap_set_immediate_mode(3PCAP)