pcap_datalink(3) pcap_datalink(3)
NAME
pcap_datalink - get the link-layer header type
SYNOPSIS
#include <pcap/pcap.h>
pcap_datalink(3) *p);
DESCRIPTION
pcap_datalink() returns the link-layer header type for the live capture
or ``savefile'' specified by p.
It must not be called on a pcap descriptor created by
pcap_create(3) that has not yet been activated by
pcap_activate(3).
https://www.tcpdump.org/linktypes.html lists the values pcap_datalink()
can return and describes the packet formats that correspond to those
values.
Do NOT assume that the packets for a given capture or ``savefile`` will
have any given link-layer header type, such as DLT_EN10MB for Ethernet.
For example, the "any" device on Linux will have a link-layer header
type of DLT_LINUX_SLL or DLT_LINUX_SLL2 even if all devices on the
system at the time the "any" device is opened have some other data link
type, such as DLT_EN10MB for Ethernet.
RETURN VALUE
pcap_datalink() returns the link-layer header type on success and
PCAP_ERROR_NOT_ACTIVATED if called on a capture handle that has been
created but not activated.
SEE ALSO
pcap(3), pcap_datalink_val_to_name(3),
pcap_set_datalink(3), pcap_list_datalinks(3), pcap-linktype(7)
7 April 2014 pcap_datalink(3)
libpcap 1.11.0 - Generated Sun Sep 13 16:56:43 CDT 2026