pcap_compile(3pcap) — Linux manual page


PCAP_COMPILE(3PCAP)                                  PCAP_COMPILE(3PCAP)

NAME         top

       pcap_compile - compile a filter expression

SYNOPSIS         top

       #include <pcap/pcap.h>

       int pcap_compile(pcap_t *p, struct bpf_program *fp,
               const char *str, int optimize, bpf_u_int32 netmask);

DESCRIPTION         top

       pcap_compile() is used to compile the string str into a filter
       program.  See pcap-filter(7) for the syntax of that string.  fp
       is a pointer to a bpf_program struct and is filled in by
       pcap_compile().  optimize controls whether optimization on the
       resulting code is performed.  netmask specifies the IPv4 netmask
       of the network on which packets are being captured; it is used
       only when checking for IPv4 broadcast addresses in the filter
       program.  If the netmask of the network on which packets are
       being captured isn't known to the program, or if packets are
       being captured on the Linux "any" pseudo-interface that can
       capture on more than one network, a value of PCAP_NETMASK_UNKNOWN
       can be supplied; tests for IPv4 broadcast addresses will fail to
       compile, but all other tests in the filter program will be OK.

       NOTE: in libpcap 1.8.0 and later, pcap_compile() can be used in
       multiple threads within a single process.  However, in earlier
       versions of libpcap, it is not safe to use pcap_compile() in
       multiple threads in a single process without some form of mutual
       exclusion allowing only one thread to call it at any given time.

RETURN VALUE         top

       pcap_compile() returns 0 on success and PCAP_ERROR on failure. 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


       The PCAP_NETMASK_UNKNOWN constant became available in libpcap
       release 1.1.0.

SEE ALSO         top

       pcap(3PCAP), pcap_setfilter(3PCAP), pcap_freecode(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 2022-12-17.
       (At that time, the date of the most recent commit that was found
       in the repository was 2022-12-13.)  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

                             22 August 2018          PCAP_COMPILE(3PCAP)