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.TH PCAP_SET_PROTOCOL_LINUX 3PCAP "24 August 2017"

.SH NAME

pcap_set_protocol_linux \- set capture protocol for a not-yet-activated

capture handle

.SH SYNOPSIS

.nf

.ft B

#include <pcap/pcap.h>

.LP

.ft B

int pcap_set_protocol_linux(pcap_t *p, int protocol);

.ft

.fi

.SH DESCRIPTION

On network interface devices on Linux,

.B pcap_set_protocol_linux()

sets the protocol to be used in the

.BR socket (2)

call to create a capture socket when the handle is activated.  The

argument is a link-layer protocol value, such as the values in the

.B <linux/if_ether.h>

header file, specified in host byte order.

If

.I protocol

is non-zero, packets of that protocol will be captured when the

handle is activated, otherwise, all packets will be captured.  This

function is only provided on Linux, and, if it is used on any device

other than a network interface, it will have no effect.

.LP

It should not be used in portable code; instead, a filter should be

specified with

.BR pcap_setfilter(3PCAP) .

.LP

If a given network interface provides a standard link-layer header, with

a standard packet type, but provides some packet types with a different

socket-layer protocol type from the one in the link-layer header, that

packet type cannot be filtered with a filter specified with

.B pcap_setfilter()

but can be filtered by specifying the socket-layer protocol type using

.BR pcap_set_protocol_linux() .

.SH RETURN VALUE

.B pcap_set_protocol_linux()

returns 0 on success or

.B PCAP_ERROR_ACTIVATED

if called on a capture handle that has been activated.

.SH BACKWARD COMPATIBILITY

This function became available in libpcap release 1.9.0.

.SH SEE ALSO

pcap(3PCAP), pcap_create(3PCAP), pcap_activate(3PCAP)