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Date:      Tue, 7 Jul 2009 09:20:30 +0200
From:      Kim Attree <kim.attree@playsafesa.com>
To:        Giuliano Gavazzi <dev+lists@humph.com>
Cc:        "freebsd-ipfw@freebsd.org" <freebsd-ipfw@freebsd.org>
Subject:   RE: Problem with source based policy routing
Message-ID:  <00265389C30B444288C246DF37651D0C37698F395A@server-02.playsafesa.com>
In-Reply-To: <D99BAF63-5F9C-49BC-AE5B-2652B1F6BDC7@humph.com>
References:  <00265389C30B444288C246DF37651D0C37637A1893@server-02.playsafesa.com> <E5834FA3-2CC4-4192-9A26-0C4914B782A2@humph.com> <00265389C30B444288C246DF37651D0C37698F3933@server-02.playsafesa.com> <D99BAF63-5F9C-49BC-AE5B-2652B1F6BDC7@humph.com>

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> -----Original Message-----
> From: Giuliano Gavazzi [mailto:dev+lists@humph.com]
> Sent: 06 July 2009 06:54 PM
> To: Kim Attree
> Cc: freebsd-ipfw@freebsd.org
> Subject: Re: Problem with source based policy routing
>=20
>=20
> On M 6 Jul, 2009, at 15:35 , Kim Attree wrote:
>=20
> > I have one Internal Exchange server (don't laugh), and NAT handles
> > the static mapping of IP/Port to that server. The original point
> > here is to have two mapped NAT port 25's to the same internal Mail
> > server, hence the addition of the NAT before and during the forward
> > logic (obviously wrong though).
> >
>=20
>=20
> ah, if you want to have an internal server to be reachable on both
> public addresses, via the corresponding two firewall interfaces, you
> must have a way to tell the firewall how to distinguish the return
> packets in order to use the correct natd instance. If the internal
> exchange server port is the same, there is no way telling that. At
> most you could use the peer port, but even that would not be
> failproof, and I would not know how to proceed (I think dynamic rules
> can only establish holes - allow action - in the firewall, not a fwd
> action). So you must use two different ports or alias addresses on the
> exchange server, and divert to the appropriate outgoing natd instance
> on the basis of that.
>=20
> I have not enough time at the moment to write down a complete
> workflow, but I hope this, with the remarks in my previous post, gives
> you enough hints.

It has, I realised that the return traffic needs differing source IP's - I'=
ve added another IP and SMTP Connector to exchange and will test the theory=
 out today.


>=20
> Giuliano

Thanks,

Kim



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