pcap_fileno(3PCAP) man page

pcap_fileno(3PCAP) man page

Updated: 10 September 2026 • View in plain text • Return to Main Contents

NAME

pcap_fileno - get the file descriptor for a live capture

SYNOPSIS

#include <pcap/pcap.h>

int pcap_fileno(pcap_t *p);

DESCRIPTION

If p refers to a capture device that was opened for a live capture using a combination of pcap_create(3PCAP) and pcap_activate(3PCAP), or using pcap_open_live(3PCAP), pcap_fileno() returns the file descriptor from which captured packets are read.

A close(2) must not be performed on the file descriptor.

If p refers to a savefile'' that was opened using functions such as [**pcap\_open\_offline**](https://www.tcpdump.org/manpages/pcap_open_offline.3pcap.html)(3PCAP) or [**pcap\_fopen\_offline**](https://www.tcpdump.org/manpages/pcap_open_offline.3pcap.html)(3PCAP), adead'' pcap_t opened using pcap_open_dead(3PCAP), or a pcap_t that was created with pcap_create() but that has not yet been activated with pcap_activate(), it returns PCAP_ERROR.

SEE ALSO

pcap(3PCAP)

COLOPHON

This HTML man page was generated at 08:27:31 GMT, September 19, 2026 from a source man page in “The Tcpdump Group” git repositories using man2html and other tools.