From owner-freebsd-net@FreeBSD.ORG  Tue May 31 11:07:49 2005
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
X-Original-To: freebsd-net@freebsd.org
Delivered-To: freebsd-net@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 6095916A42A
	for <freebsd-net@freebsd.org>; Tue, 31 May 2005 11:07:49 +0000 (GMT)
	(envelope-from french.linuxian@gmail.com)
Received: from zproxy.gmail.com (zproxy.gmail.com [64.233.162.193])
	by mx1.FreeBSD.org (Postfix) with ESMTP id E379143D1F
	for <freebsd-net@freebsd.org>; Tue, 31 May 2005 11:07:48 +0000 (GMT)
	(envelope-from french.linuxian@gmail.com)
Received: by zproxy.gmail.com with SMTP id 12so1826746nzp
	for <freebsd-net@freebsd.org>; Tue, 31 May 2005 04:07:48 -0700 (PDT)
DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com;
	h=received:message-id:date:from:reply-to:to:subject:mime-version:content-type:content-transfer-encoding:content-disposition;
	b=SWnkrFtY31o8WNPO+pjWacwrsFMVxKIjKA3E4CoBPow0w6kmdXlK2kB7Ku0P34F41eIInL2OXHTuawZLrHCV8WKru2lrrMy7ssIgqvQQkDjaEoj3reDfKj1xkPLPQuDKebHu0EGPRT6UJN1lYR3VlBzsHIim4049tASyFO6Dkd8=
Received: by 10.36.178.20 with SMTP id a20mr858234nzf;
	Tue, 31 May 2005 04:07:48 -0700 (PDT)
Received: by 10.36.58.12 with HTTP; Tue, 31 May 2005 04:07:48 -0700 (PDT)
Message-ID: <3727392705053104072e9547df@mail.gmail.com>
Date: Tue, 31 May 2005 07:07:48 -0400
From: Aziz Kezzou <french.linuxian@gmail.com>
To: freebsd-hackers <freebsd-hackers@freebsd.org>, 
	freebsd-net <freebsd-net@freebsd.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline
Cc: 
Subject: Routing loop + raw IP packets : looking for clues ...
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
Reply-To: Aziz Kezzou <french.linuxian@gmail.com>
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
	<mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
	<mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 31 May 2005 11:07:49 -0000

Hi all,
For the purpose of my project I am simpulating a 3-hop network with
QEMU on my workstation, as follows :

|---------------------------------|          =20
|-------------------------------|            =20
|-------------------------------------|
|Daemon1(user process)|---tun0---| Daemon 2 on QEMU |---tun1---|
Daemon 3 (user porcess) |
|---------------------------------|           =20
|-------------------------------|           =20
|-------------------------------------|

My workstation  is running FC3 and QEMU is running FreeBSD5.3
I am tryning to exchange raw IP packets between daemon 1 and 3 through
daemon 2. I've succeded to by pass  the system routing and get packets
sent from daemon 1 to daemon 2 and from daemon 2 to daemon 3. BUT, on
daemon 3 I can not receive them ??!!

However, when I listen with tcpdump on tun0 and tun1 I see the packets
travelling as expected :
daemon1(192.168.0.1)------>(192.168.0.2)daemon2(192.168.1.2)------>
daemon3(192.168.0.2)

What could prevent me from receiving packets intended for daemon 3? I
am suspecting some hard coded rule to prevent routing loops (which is
my case) in the Linux kernel, am I on the right track ?

Note : I disabled completely my firewalls, so this could not be the reason.

Any help is highly appreciated.

-aziz