PCAP_DATALINK(3PCAP) PCAP_DATALINK(3PCAP)

NAME

pcap_datalink - get the link-layer header type

SYNOPSIS

#include <pcap/pcap.h>

int pcap_datalink(pcap_t *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(3PCAP) that has not yet been activated by
pcap_activate(3PCAP).

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(3PCAP), pcap-linktype(5)

7 April 2014 PCAP_DATALINK(3PCAP)