Problem with source based policy routing

[Kim Attree]

> -----Original Message-----
> From: Giuliano Gavazzi [mailto:dev+lists at humph.com]
> Sent: 06 July 2009 06:54 PM
> To: Kim Attree
> Cc: freebsd-ipfw at freebsd.org
> Subject: Re: Problem with source based policy routing
> 
> 
> On M 6 Jul, 2009, at 15:35 , Kim Attree wrote:
> 
> > 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).
> >
> 
> 
> 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.
> 
> 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.


> 
> Giuliano

Thanks,

Kim