If
p refers to a network device that was opened for a live capture using
a combination of
pcap_create(3) and
pcap_activate(3) ,
or using
pcap_open_live(3) ,
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(3)
or
pcap_fopen_offline(3) ,
a ``dead''
pcap_t opened using
pcap_open_dead(3) ,
or a
pcap_t that was created with
pcap_create() but that has not yet been activated with
pcap_activate(), it returns
PCAP_ERROR.
