.\" Copyright (c) 1987, 1988, 1989, 1990, 1991, 1992, 1994, 1995, 1996, 1997
.\"	The Regents of the University of California.  All rights reserved.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that: (1) source code distributions
.\" retain the above copyright notice and this paragraph in its entirety, (2)
.\" distributions including binary code include the above copyright notice and
.\" this paragraph in its entirety in the documentation or other materials
.\" provided with the distribution, and (3) all advertising materials mentioning
.\" features or use of this software display the following acknowledgement:
.\" ``This product includes software developed by the University of California,
.\" Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
.\" the University nor the names of its contributors may be used to endorse
.\" or promote products derived from this software without specific prior
.\" written permission.
.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
.\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
.\"
.TH PCAP-LINKTYPE @MAN_MISC_INFO@ "6 April 2020"
.SH NAME
pcap-linktype \- link-layer header types supported by libpcap
.SH DESCRIPTION
For a live capture or ``savefile'', libpcap supplies, as the return
value of the
.BR pcap_datalink (3PCAP)
routine, a value that indicates the type of link-layer header at the
beginning of the packets it provides.  This is not necessarily the type
of link-layer header that the packets being captured have on the network
from which they're being captured; for example, packets from an IEEE
802.11 network might be provided by libpcap with Ethernet headers that
the network adapter or the network adapter driver generates from the
802.11 headers.  The names for those values begin with
.BR DLT_ ,
so they are sometimes called "DLT_ values".
.PP
The values stored in the link-layer header type field in the savefile
header are, in most but not all cases, the same as the values returned
by
.BR pcap_datalink ().
The names for those values begin with
.BR LINKTYPE_ .
.PP
The link-layer header types supported by libpcap are described at
https://www.tcpdump.org/linktypes.html .
.SH SEE ALSO
.BR pcap (3PCAP)