l7-filter(1)							   User's Manual						      l7-filter(1)

NAME

       l7-filter - classifies packets by their application layer data

SYNOPSIS

       l7-filter -f configuration_file [options]

DESCRIPTION

       l7-filter reads packets that are queued by Netfilter/iptables and marks them based on what application layer protocol they appear to be.

OPTIONS

       -f configuration_file
	      Mandatory option.  This file consists of pairs of protocol names and mark numbers.

       -q queue_number
	      What queue to read packets from.	Default is 0.

       -b bytes
	      Match on up to this many bytes of application layer data.  The default is 12000.

       -n packets
	      Examine  up to this many packets in each connection.  If no match has been made after this, l7-filter gives up.  The number of pack-
	      ets counts all packets, including the TCP handshake and ACK packets (XXX but not any UDP packets that l7-filter didn't manage to get
	      the conntrack for in time XXX). The default is 10.

       -p path
	      Look  for  patterns in path instead of the default /etc/l7-protocols.  The path and its subdirectories are searched, non-recursively
	      (subsubdirectories are not searched).

       -m mask
	      Use only the bits of the packet mark specified by the given mask.  By default, l7-filter uses the whole 32 bit mark, so this is use-
	      ful  if you use other classifiers that set marks. For instance, if you give the mask 0xff000000, l7-filter will only use the first 8
	      bits of the mark and will completely ignore the rest of it.  In this case, the mark numbers given  in  the  configuration  file  are
	      mapped  onto the mask automatically.  So if the configuration file says 2 and you've given the mask 0x00ff0000, l7-filter will actu-
	      ally use 0x00020000.

	      The mask must be contiguous (not, for instance, 0x00000f0f) and it must be at least 2 bits  long.   The  number  of  protocols  that
	      l7-filter  can  handle  is  2^(mask length)-3 since it uses the value 0 to detect when a packet has not been examined yet, 1 to mark
	      packets in connections which are unmatched but still being examined, and 2 to mark packets which it has given up trying to identify.

       -c     l7-filter expects its portion of the packet mark (see -m above) to be unmodified by other  classifiers.	Normally,  if  it  gets  a
	      packet  whose  mark  has	already been modified (that is, is non-zero) in this region, it will send the packet on with the same mark
	      without trying to classify it and print an error message.  This option causes l7-filter instead to clobber  the  existing  mark  and
	      classify as if it hadn't been there.

       -s     Be silent (don't print anything) except in the case of warnings or errors.

       -v     Be  verbose.   Gives more information about what l7-filter is doing.  Multiple -v options increase the verbosity, up to a maximum of
	      4.

       -d     Allow inadvisable configurations.  You must give this option before the option which is inadvisable.

UPGRADES

       The latest version is always at http://sf.net/projects/l7-filter

SEE ALSO

       iptables(1)

COPYRIGHT

       Copyright (C) 2006-2007 Ethan Sommer <sommereAusers.sf.net> and Matthew Strait <quadongAusers.sf.net>.  This is	free  software.   You  may
       redistribute  copies  of it under the terms of the GNU General Public License <http://www.gnu.org/licenses/gpl.html>. There is NO WARRANTY,
       to the extent permitted by law.

l7-filter v0.3							   January 2007 						      l7-filter(1)