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Old 09-13-2005
Help in extending netfilter
Hi everybody,
I have to write a module for matching in netfilter , extending the netfilter but I'm facing some problems can somebody guide me in that. I know that I need to write matching module working in kernel space and a program in userspace. I went through the HOWTO on netfilter-hacking but faced following problems :
1. In kernel module how is match function different from checkentry function (I got this confusion because a 0 return in checkentry and setting hotdrop to 1 seemed to do same thing). Please explain the meaning of each function elaborately.

2. As described in the HOWTO there is a structure in header file iptables.h that I need for program in userspace but I'm not able to locate this headerfile where can I find it.

If possible please send me an example of any module with both the kernel module and program for taking user input in userspace.

Thanks in advance.
Last edited by Trusted Penguin; 09-15-2005 at 11:59 AM..
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LEARN ABOUT DEBIAN

lire::firewall::iptablesdlfconverter

IptablesDlfConverter(3pm)				  LogReport's Lire Documentation				 IptablesDlfConverter(3pm)

NAME

       IptablesDlfConverter - convert netfilter/iptables syslog logs to firewall DLF

DESCRIPTION

       IptablesDlfConverter converts Linux 2.4 iptables packet log into firewall DLF format.

LIMITATIONS

       The netfilter logging modules don't log the status of the packet (drop, accept, reject) like the ipchains logging code. You can specify a
       prefix that will be used in the log. This converter will mark the packet as 'denied' whenever that prefix matches (case insensitive) the
       following regex: 'denied|deny|drop|reject|unallowed', it will mark the packet as 'permitted' whenever that prefix matches (case
       insensitive) the following regex: 'accept|permit', and all other packets will have '-' as the value of the 'action' field.

       So in order for this converter to detect 'denied' packets, you should use a prefix containing one of those substrings.

       For example:

	iptables -N lodrop
	iptables -A logdrop -j LOG --log-prefix "Packet-DENY: "
	iptables -A logdrop -j DROP

       or other similar prefixes: 'denied: ', 'Packet-REJECT: ', ...

       The prefix used will end up in the 'rule' field of the DLF record.

EXAMPLES

       IptablesDlfConvertor will be rarely used on its own, but is more likely called by lr_log2report:

	$ lr_log2report iptables < /var/log/iptables.log > report

SEE ALSO

       The Netfilter webpage at http://netfilter.samba.org/ .

AUTHORS

       Francis J. Lacoste <flacoste@logreport.org>

VERSION

       $Id: IptablesDlfConverter.pm,v 1.12 2006/07/23 13:16:35 vanbaal Exp $

COPYRIGHT

       Copyright (C) 2001, 2002, 2003, 2004 Stichting LogReport Foundation LogReport@LogReport.org

       This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by
       the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

       This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

       You should have received a copy of the GNU General Public License along with this program (see COPYING); if not, check with
       http://www.gnu.org/copyleft/gpl.html.

Lire 2.1.1							    2006-07-23						 IptablesDlfConverter(3pm)