pcap_datalink(3PCAP) man page

Updated: 7 April 2014 • View in plain textReturn to Main Contents

This man page documents libpcap version 1.10.4 (see also: git master branch, 1.10.2, 1.10.1, 1.10.0, 1.9.1, 1.8.1, 1.7.4, 1.6.2, 1.5.3).

Your system may have a different version installed, possibly with some local modifications. To achieve the best results, please make sure this version of this man page suits your needs. If necessary, try to look for a different version on this web site or in the man pages available in your installation.


pcap_datalink - get the link-layer header type


#include <pcap/pcap.h>

int pcap_datalink(pcap_t *p);


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.


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.


pcap(3PCAP), pcap-linktype(7)


This HTML man page was generated at 21:18:19 GMT, April 07, 2023 from a source man page in "The Tcpdump Group" git repositories using man2html and other tools.