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the LIBpcap interface to various kernel packet capture mechanism
C Shell Assembly C++ Objective-C Perl
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ChmodBPF
SUNOS4
Win32
bpf/net
doc
lbl
missing
msdos
packaging
pcap
tests
.cvsignore
.gitattributes
.gitignore
CHANGES
CREDITS
INSTALL.txt
LICENSE
Makefile.in
README
README.Win32
README.aix
README.dag
README.hpux
README.linux
README.macosx
README.septel
README.sita
README.tru64
TODO
VERSION
aclocal.m4
arcnet.h
atmuni31.h
bpf_dump.c
bpf_image.c
chmod_bpf
config.guess
config.h.in
config.sub
configure
configure.in
dlpisubs.c
dlpisubs.h
etherent.c
ethertype.h
fad-getad.c
fad-gifc.c
fad-glifc.c
fad-null.c
fad-sita.c
fad-win32.c
gencode.c
gencode.h
grammar.y
ieee80211.h
inet.c
install-sh
llc.h
mkdep
nametoaddr.c
nlpid.h
optimize.c
org.tcpdump.chmod_bpf.plist
pcap-bpf.c
pcap-bpf.h
pcap-bt-linux.c
pcap-bt-linux.h
pcap-can-linux.c
pcap-can-linux.h
pcap-canusb-linux.c
pcap-canusb-linux.h
pcap-common.c
pcap-common.h
pcap-config.1
pcap-config.in
pcap-dag.c
pcap-dag.h
pcap-dlpi.c
pcap-dos.c
pcap-dos.h
pcap-enet.c
pcap-filter.manmisc.in
pcap-int.h
pcap-libdlpi.c
pcap-linktype.manmisc.in
pcap-linux.c
pcap-namedb.h
pcap-netfilter-linux.c
pcap-netfilter-linux.h
pcap-nit.c
pcap-null.c
pcap-pf.c
pcap-savefile.manfile.in
pcap-septel.c
pcap-septel.h
pcap-sita.c
pcap-sita.h
pcap-sita.html
pcap-snf.c
pcap-snf.h
pcap-snit.c
pcap-snoop.c
pcap-stdinc.h
pcap-tstamp.manmisc.in
pcap-usb-linux.c
pcap-usb-linux.h
pcap-win32.c
pcap.3pcap.in
pcap.c
pcap.h
pcap1.h
pcap_activate.3pcap
pcap_breakloop.3pcap
pcap_can_set_rfmon.3pcap
pcap_close.3pcap
pcap_compile.3pcap.in
pcap_create.3pcap
pcap_datalink.3pcap.in
pcap_datalink_name_to_val.3pcap
pcap_datalink_val_to_name.3pcap
pcap_dump.3pcap
pcap_dump_close.3pcap
pcap_dump_file.3pcap
pcap_dump_flush.3pcap
pcap_dump_ftell.3pcap
pcap_dump_open.3pcap.in
pcap_file.3pcap
pcap_fileno.3pcap
pcap_findalldevs.3pcap
pcap_freecode.3pcap
pcap_get_selectable_fd.3pcap
pcap_geterr.3pcap
pcap_inject.3pcap
pcap_is_swapped.3pcap
pcap_lib_version.3pcap
pcap_list_datalinks.3pcap.in
pcap_list_tstamp_types.3pcap.in
pcap_lookupdev.3pcap
pcap_lookupnet.3pcap
pcap_loop.3pcap
pcap_major_version.3pcap
pcap_next_ex.3pcap
pcap_offline_filter.3pcap
pcap_open_dead.3pcap.in
pcap_open_live.3pcap
pcap_open_offline.3pcap.in
pcap_set_buffer_size.3pcap
pcap_set_datalink.3pcap
pcap_set_promisc.3pcap
pcap_set_rfmon.3pcap
pcap_set_snaplen.3pcap
pcap_set_timeout.3pcap
pcap_set_tstamp_type.3pcap.in
pcap_setdirection.3pcap
pcap_setfilter.3pcap
pcap_setnonblock.3pcap
pcap_snapshot.3pcap
pcap_stats.3pcap
pcap_statustostr.3pcap
pcap_strerror.3pcap
pcap_tstamp_type_name_to_val.3pcap
pcap_tstamp_type_val_to_name.3pcap
ppp.h
runlex.sh
savefile.c
scanner.l
sf-pcap-ng.c
sf-pcap-ng.h
sf-pcap.c
sf-pcap.h
sunatmpos.h

README

@(#) $Header: /tcpdump/master/libpcap/README,v 1.34 2008-12-14 19:44:14 guy Exp $ (LBL)

LIBPCAP 1.x.y

www.tcpdump.org

Please send inquiries/comments/reports to:
	tcpdump-workers@lists.tcpdump.org

Anonymous Git is available via:
	git clone git://bpf.tcpdump.org/libpcap

Version 1.x.y of LIBPCAP can be retrieved with the CVS tag "libpcap_1_{x}rel{y}":
	cvs -d :pserver:tcpdump@cvs.tcpdump.org:/tcpdump/master checkout -r libpcap_1_{x}rel{y} libpcap

Please submit patches against the master copy to the libpcap project on
sourceforge.net.

formerly from 	Lawrence Berkeley National Laboratory
		Network Research Group <libpcap@ee.lbl.gov>
		ftp://ftp.ee.lbl.gov/libpcap.tar.Z (0.4)

This directory contains source code for libpcap, a system-independent
interface for user-level packet capture.  libpcap provides a portable
framework for low-level network monitoring.  Applications include
network statistics collection, security monitoring, network debugging,
etc.  Since almost every system vendor provides a different interface
for packet capture, and since we've developed several tools that
require this functionality, we've created this system-independent API
to ease in porting and to alleviate the need for several
system-dependent packet capture modules in each application.

For some platforms there are README.{system} files that discuss issues
with the OS's interface for packet capture on those platforms, such as
how to enable support for that interface in the OS, if it's not built in
by default.

The libpcap interface supports a filtering mechanism based on the
architecture in the BSD packet filter.  BPF is described in the 1993
Winter Usenix paper ``The BSD Packet Filter: A New Architecture for
User-level Packet Capture''.  A compressed PostScript version can be
found at

	ftp://ftp.ee.lbl.gov/papers/bpf-usenix93.ps.Z

or

	http://www.tcpdump.org/papers/bpf-usenix93.ps.Z

and a gzipped version can be found at

	http://www.tcpdump.org/papers/bpf-usenix93.ps.gz

A PDF version can be found at

	http://www.tcpdump.org/papers/bpf-usenix93.pdf

Although most packet capture interfaces support in-kernel filtering,
libpcap utilizes in-kernel filtering only for the BPF interface.
On systems that don't have BPF, all packets are read into user-space
and the BPF filters are evaluated in the libpcap library, incurring
added overhead (especially, for selective filters).  Ideally, libpcap
would translate BPF filters into a filter program that is compatible
with the underlying kernel subsystem, but this is not yet implemented.

BPF is standard in 4.4BSD, BSD/OS, NetBSD, FreeBSD, OpenBSD, DragonFly
BSD, and Mac OS X; an older, modified and undocumented version is
standard in AIX.  {DEC OSF/1, Digital UNIX, Tru64 UNIX} uses the
packetfilter interface but has been extended to accept BPF filters
(which libpcap utilizes).  Also, you can add BPF filter support to
Ultrix using the kernel source and/or object patches available in:

	http://www.tcpdump.org/other/bpfext42.tar.Z

Linux, in the 2.2 kernel and later kernels, has a "Socket Filter"
mechanism that accepts BPF filters; see the README.linux file for
information on configuring that option.

Note to Linux distributions and *BSD systems that include libpcap:

There's now a rule to make a shared library, which should work on Linux 
and *BSD, among other platforms.

It sets the soname of the library to "libpcap.so.1"; this is what it 
should be, *NOT* libpcap.so.1.x or libpcap.so.1.x.y or something such as 
that.

We've been maintaining binary compatibility between libpcap releases for 
quite a while; there's no reason to tie a binary linked with libpcap to 
a particular release of libpcap.

Problems, bugs, questions, desirable enhancements, etc. should be sent
to the address "tcpdump-workers@lists.tcpdump.org".  Bugs, support
requests, and feature requests may also be submitted on the SourceForge
site for libpcap at

	http://sourceforge.net/projects/libpcap/

Source code contributions, etc. should be sent to the email address
submitted as patches on the SourceForge site for libpcap.

Current versions can be found at www.tcpdump.org, or the SourceForge
site for libpcap.

 - The TCPdump team
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