pcap_open_live(3pcap) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | SEE ALSO | COLOPHON

PCAP_OPEN_LIVE(3PCAP)                               PCAP_OPEN_LIVE(3PCAP)

NAME         top

       pcap_open_live - open a device for capturing

SYNOPSIS         top

       #include <pcap/pcap.h>

       char errbuf[PCAP_ERRBUF_SIZE];

       pcap_t *pcap_open_live(const char *device, int snaplen,
           int promisc, int to_ms, char *errbuf);

DESCRIPTION         top

       pcap_open_live() is used to obtain a packet capture handle to
       capture packets on a device (typically a network interface, see
       pcap_findalldevs(3PCAP) for a more detailed explanation).  device
       is a string that specifies the capture device to open, in this
       function NULL means the same as the string "any".

       snaplen specifies the snapshot length to be set on the handle.  If
       the packet data should not be truncated at the end, a value of
       262144 should be sufficient for most devices, but D-Bus devices
       require a value of 128MiB (128*1024*1024).

       promisc specifies whether the device is to be put into promiscuous
       mode.  If promisc is non-zero, promiscuous mode will be set,
       otherwise it will not be set.

       to_ms specifies the packet buffer timeout, as a non-negative
       value, in milliseconds.  (See pcap(3PCAP) for an explanation of
       the packet buffer timeout.)

       errbuf is a buffer large enough to hold at least PCAP_ERRBUF_SIZE
       chars.

RETURN VALUE         top

       pcap_open_live() returns a pcap_t * on success and NULL on
       failure.  If NULL is returned, errbuf is filled in with an
       appropriate error message.  errbuf may also be set to warning text
       when pcap_open_live() succeeds; to detect this case the caller
       should store a zero-length string in errbuf before calling
       pcap_open_live() and display the warning to the user if errbuf is
       no longer a zero-length string.

SEE ALSO         top

       pcap_create(3PCAP), pcap_activate(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

                              11 March 2025         PCAP_OPEN_LIVE(3PCAP)