Man page of PCAP_COMPILE
Section: Misc. Reference Manual Pages (3PCAP)
Updated: 24 March 2017
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This man page documents libpcap version 1.9.0.
Your system may have a different version installed, possibly with some
local modifications. To achieve the best results, please make sure this
version of this man page suits your needs. If necessary, try to look for
a different version on this web site or in the man pages available in your
pcap_compile - compile a filter expression
int pcap_compile(pcap_t *p, struct bpf_program *fp,
const char *str, int optimize, bpf_u_int32 netmask);
is used to compile the string
into a filter program. See
for the syntax of that string.
is a pointer to a
struct and is filled in by
controls whether optimization on the resulting code is performed.
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,
can be used in multiple threads within a single process. However, in
earlier versions of libpcap, it is
safe to use
in multiple threads in a single process without some form of mutual
exclusion allowing only one thread to call it at any given time.
returns 0 on success and -1 on failure.
If -1 is returned,
may be called with
as an argument to fetch or display the error text.
pcap(3PCAP), pcap_setfilter(3PCAP), pcap_freecode(3PCAP),
This document was created by
using the manual pages from "The Tcpdump Group" git repositories.
Time: 12:21:39 GMT, October 07, 2021
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