pcap_setdirection(3pcap) — Linux manual page

PCAP_SETDIRECTION(3PCAP)                         PCAP_SETDIRECTION(3PCAP)

NAME         top

       pcap_setdirection - set the direction for which packets will be
       captured

SYNOPSIS         top

       #include <pcap/pcap.h>

       int pcap_setdirection(pcap_t *p, pcap_direction_t d);

DESCRIPTION         top

       pcap_setdirection() is used to specify a direction that packets
       will be captured.  d is one of the constants PCAP_D_IN, PCAP_D_OUT
       or PCAP_D_INOUT.  PCAP_D_IN will only capture packets received by
       the device, PCAP_D_OUT will only capture packets sent by the
       device and PCAP_D_INOUT will capture packets received by or sent
       by the device.  PCAP_D_INOUT is the default setting if this
       function is not called.

       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 PCAP_D_OUT.

       This operation is not supported if a ``savefile'' is being read.

RETURN VALUE         top

       pcap_setdirection() returns 0 on success, PCAP_ERROR_NOT_ACTIVATED
       if called on a capture handle that has been created but not
       activated, or PCAP_ERROR on other errors. If PCAP_ERROR is
       returned, pcap_geterr(3PCAP) or pcap_perror(3PCAP) may be called
       with p as an argument to fetch or display the error text.

SEE ALSO         top

       pcap(3PCAP)

COLOPHON         top

       This page is part of the libpcap (packet capture library) project.
       Information about the project can be found at 
       ⟨http://www.tcpdump.org/⟩.  If you have a bug report for this
       manual page, see ⟨http://www.tcpdump.org/#patches⟩.  This page was
       obtained from the project's upstream Git repository
       ⟨https://github.com/the-tcpdump-group/libpcap.git⟩ on 2025-08-11.
       (At that time, the date of the most recent commit that was found
       in the repository was 2025-08-10.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there is
       a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

                               5 March 2022      PCAP_SETDIRECTION(3PCAP)

HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH.