used to clean up after a failed pcap_activate() call. Convert the
existing close_op routines to cleanup_op routines, and use them to clean
up; rename pcap_close_common() to pcap_cleanup_live_common(), and use it
directly if there's no platform-dependent cleanup needed. That means we
don't have to write the same cleanup code twice (and possibly forget
stuff in the version done on a failed pcap_activate() call).
Have the cleanup routines do whatever is necessary to indicate that
cleanup has been done, and not do any particular cleaning up if it's
already been done (i.e., don't free something if the pointer to it is
null and null out the pointer once it's been freed, don't close an FD if
it's -1 and set it to -1 once it's been closed, etc.).
For device types/platforms where we don't support monitor mode, check
for it and return PCAP_ERROR_RFMON_NOTSUP - but do so after we've
checked whether we can open the device, so we return "no such device" or
"permission denied" rather than "that device doesn't support monitor
mode" if we can't open the device in the first place.
Fix a comment.
@(#) $Header: /tcpdump/master/libpcap/README,v 1.30 2004-10-12 02:02:28 guy Exp $ (LBL)
LIBPCAP 0.9
Now maintained by "The Tcpdump Group"
See www.tcpdump.org
Please send inquiries/comments/reports to tcpdump-workers@tcpdump.org
Anonymous CVS is available via:
cvs -d :pserver:tcpdump@cvs.tcpdump.org:/tcpdump/master login
(password "anoncvs")
cvs -d :pserver:tcpdump@cvs.tcpdump.org:/tcpdump/master checkout libpcap
Version 0.9 of LIBPCAP can be retrieved with the CVS tag "libpcap_0_9rel1":
cvs -d :pserver:tcpdump@cvs.tcpdump.org:/tcpdump/master checkout -r libpcap_0_9rel1 libpcap
Please send patches against the master copy to patches@tcpdump.org.
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.
Note well: this interface is new and is likely to change.
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, and OpenBSD. 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:
ftp://gatekeeper.dec.com/pub/DEC/net/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.
Problems, bugs, questions, desirable enhancements, etc. should be sent
to the address "tcpdump-workers@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
"patches@tcpdump.org", or 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