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PCAP_DATALINK

Section: Misc. Reference Manual Pages (3PCAP)
Updated: 7 April 2014
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NAME

pcap_datalink - get the lin-layer header type

SYNOPSIS

#include <pcap/pcap.h>

int pcap_datalink(pcap_t *p);

DESCRIPTION

pcap_datalink() returns the lin-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 lin-layer header type, such as DLT_EN10MB for Ethernet. For example, the "any" device on Linux will have a lin-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 lin-layer header type on success and PCAP_ERROR_NOT_ACTIVATED if called on a capture handle that has been created but not activated.