From owner-freebsd-ipfw@FreeBSD.ORG  Tue Mar 17 09:06:51 2009
Return-Path: <owner-freebsd-ipfw@FreeBSD.ORG>
Delivered-To: freebsd-ipfw@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 57A721065672
	for <freebsd-ipfw@freebsd.org>; Tue, 17 Mar 2009 09:06:51 +0000 (UTC)
	(envelope-from ale@FreeBSD.org)
Received: from andxor.it (relay.andxor.it [195.223.2.3])
	by mx1.freebsd.org (Postfix) with SMTP id 990748FC14
	for <freebsd-ipfw@freebsd.org>; Tue, 17 Mar 2009 09:06:50 +0000 (UTC)
	(envelope-from ale@FreeBSD.org)
Received: (qmail 51854 invoked from network); 17 Mar 2009 08:40:08 -0000
Received: from unknown (HELO ale.andxor.it) (192.168.2.5)
	by andxor.it with SMTP; 17 Mar 2009 08:40:08 -0000
Message-ID: <49BF61E7.7020305@FreeBSD.org>
Date: Tue, 17 Mar 2009 09:40:07 +0100
From: Alex Dupre <ale@FreeBSD.org>
User-Agent: Thunderbird 2.0.0.17 (X11/20080929)
MIME-Version: 1.0
To: Luigi Rizzo <rizzo@iet.unipi.it>
References: <200903132246.49159.dima_bsd@inbox.lv>
	<20090313214327.GA1675@onelab2.iet.unipi.it>
In-Reply-To: <20090313214327.GA1675@onelab2.iet.unipi.it>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: freebsd-ipfw@freebsd.org, Dmitriy Demidov <dima_bsd@inbox.lv>
Subject: Re: keep-state rules inadequately handles big UDP packets
 or	fragmented IP packets?
X-BeenThere: freebsd-ipfw@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: IPFW Technical Discussions <freebsd-ipfw.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-ipfw>,
	<mailto:freebsd-ipfw-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-ipfw>
List-Post: <mailto:freebsd-ipfw@freebsd.org>
List-Help: <mailto:freebsd-ipfw-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-ipfw>,
	<mailto:freebsd-ipfw-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 17 Mar 2009 09:06:51 -0000

Luigi Rizzo ha scritto:
> it is not related to dynamic rules, but to the fact that
> that the firewall is called before reassembling packets.
> The info (port numbers especially) is not available
> in the fragments so the firewall cannot do anything.
> The only solution would be to call the firewall
> after reassembly. I am not sure if there is any work in progress
> for that.

FWIW pf has "traffic normalization" feature ("scrub" keyword), that 
reassembles packets before inspection. Unfortunately, it works with IPv4 
packets, but lacks IPv6 support.

-- 
Alex Dupre