pcap_open_dead — Npcap API

Name

pcap_open_dead, pcap_open_dead_with_tstamp_precision - open a fake pcap_t for compiling filters or opening a capture for output

Synopsis

#include <pcap/pcap.h>
pcap_t *pcap_open_dead(int linktype, int snaplen);
pcap_t *pcap_open_dead_with_tstamp_precision(int linktype, int snaplen,
    u_int precision);

Description

pcap_open_dead() and pcap_open_dead_with_tstamp_precision() are used for creating a pcap_t structure to use when calling the other functions in libpcap. It is typically used when just using libpcap for compiling BPF code; it can also be used if using pcap_dump_open(3PCAP), pcap_dump(3PCAP), and pcap_dump_close(3PCAP) to write a savefile if there is no pcap_t that supplies the packets to be written.

linktype specifies the link-layer type for the pcap_t.

snaplen specifies the snapshot length for the pcap_t.

When pcap_open_dead_with_tstamp_precision(), is used to create a pcap_t for use with pcap_dump_open(), precision specifies the time stamp precision for packets; PCAP_TSTAMP_PRECISION_MICRO should be specified if the packets to be written have time stamps in seconds and microseconds, and PCAP_TSTAMP_PRECISION_NANO should be specified if the packets to be written have time stamps in seconds and nanoseconds. Its value does not affect pcap_compile(3PCAP).

Backward compatibility

The pcap_open_dead_with_tstamp_precision() function became available in libpcap release 1.5.1. In previous releases, there was no mechanism to open a savefile for writing with time stamps given in seconds and nanoseconds.