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.TH PCAP_SETDIRECTION 3PCAP "5 March 2022"
.SH NAME
pcap_setdirection \- set the direction for which packets will be captured
.SH SYNOPSIS
.nf
.ft B
#include <pcap/pcap.h>
.ft
.LP
.ft B
int pcap_setdirection(pcap_t *p, pcap_direction_t d);
.ft
.fi
.SH DESCRIPTION
.BR pcap_setdirection ()
is used to specify a direction that packets will be captured.
.I d
is one of the constants
.BR PCAP_D_IN ,
.B PCAP_D_OUT
or
.BR PCAP_D_INOUT .
.B PCAP_D_IN
will only capture packets received by the device,
.B PCAP_D_OUT
will only capture packets sent by the device and
.B PCAP_D_INOUT
will capture packets received by or sent by the device.
.B PCAP_D_INOUT
is the default setting if this function is not called.
.PP
.BR pcap_setdirection ()
isn't necessarily fully supported on all platforms; some platforms might
return an error for all values, and some other platforms might not
support
.BR PCAP_D_OUT .
.PP
This operation is not supported if a ``savefile'' is being read.
.SH RETURN VALUE
.BR pcap_setdirection ()
returns
.B 0
on success,
.B PCAP_ERROR_NOT_ACTIVATED
if called on a capture handle that has been created but not activated, or
.B PCAP_ERROR
on other errors. If
.B PCAP_ERROR
is returned,
.BR pcap_geterr (3PCAP)
or
.BR pcap_perror (3PCAP)
may be called with
.I p
as an argument to fetch or display the error text.
.SH SEE ALSO
.BR pcap (3PCAP)