From owner-freebsd-questions@FreeBSD.ORG  Tue Feb 20 23:30:33 2007
Return-Path: <owner-freebsd-questions@FreeBSD.ORG>
X-Original-To: freebsd-questions@freebsd.org
Delivered-To: freebsd-questions@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id BE62216B677
	for <freebsd-questions@freebsd.org>;
	Tue, 20 Feb 2007 23:30:33 +0000 (UTC)
	(envelope-from julian@elischer.org)
Received: from outK.internet-mail-service.net (outK.internet-mail-service.net
	[216.240.47.234])
	by mx1.freebsd.org (Postfix) with ESMTP id 9CACE13C491
	for <freebsd-questions@freebsd.org>;
	Tue, 20 Feb 2007 23:30:33 +0000 (UTC)
	(envelope-from julian@elischer.org)
Received: from mx0.idiom.com (HELO idiom.com) (216.240.32.160)
	by out.internet-mail-service.net (qpsmtpd/0.32) with ESMTP;
	Tue, 20 Feb 2007 14:55:47 -0800
Received: from [10.251.22.38] (nat.ironport.com [63.251.108.100])
	by idiom.com (Postfix) with ESMTP id DF12E125B2B;
	Tue, 20 Feb 2007 15:19:58 -0800 (PST)
Message-ID: <45DB821D.4050508@elischer.org>
Date: Tue, 20 Feb 2007 15:19:57 -0800
From: Julian Elischer <julian@elischer.org>
User-Agent: Thunderbird 1.5.0.9 (Macintosh/20061207)
MIME-Version: 1.0
To: admin <admin@azuni.net>
References: <Pine.BSF.3.96.1070219235025.26249C-100000@gaia.nimnet.asn.au>
	<45D9D25E.1050007@azuni.net>
In-Reply-To: <45D9D25E.1050007@azuni.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: freebsd-net@freebsd.org, Ian Smith <smithi@nimnet.asn.au>,
	freebsd-questions@freebsd.org
Subject: Re: ipfw limit src-addr woes
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions>
List-Post: <mailto:freebsd-questions@freebsd.org>
List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 20 Feb 2007 23:30:33 -0000

admin wrote:

> 
> Wrong: the implied "check-state" done by the "limit" lets the connection 
> through (i.e. performs the action) iff there's state recorded for it 
> (src-addr+src-port+dst-addr+dst-port). If however it's a SYN packet 
> incoming and the number of current states is trying to cross the limit, 
> the SYN packet is implicitly dropped and the search terminates.
> 
> This is not to say that I completely understand the things going on when 
> the connections start building up (different timeouts?) but the above 
> conclusion is based on what simulation has shown. The whole ruleset fits 
> on one screen, there's an "allow ip from any to any" in the end, so I'm 
> pretty sure I'm not crazy :-)

One thing to keep in mind is that a 'check-state' rule works by effectively 
jumping to the rule that did the 'keep-state' and re-executing it..
(and incrementing its stats).