If p refers to a network 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.
If p refers to a ``savefile'' that was opened using functions
such as pcap_open_offline(3PCAP) or pcap_fopen_offline(3PCAP), a
``dead'' 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.
This page is part of the libpcap (packet capture library)
project. Information about the project can be found at
⟨http://www.tcpdump.org/⟩. If you have a bug report for this
manual page, see ⟨http://www.tcpdump.org/#patches⟩. This page
was obtained from the project's upstream Git repository
⟨https://github.com/the-tcpdump-group/libpcap.git⟩ on 2021-04-01.
(At that time, the date of the most recent commit that was found
in the repository was 2021-03-31.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
25 July 2018 PCAP_FILENO(3PCAP)