NAT+RDR vs ROUTING problem

[Koen Maes <kmaes_(_at_)_bru-hub_(_dot_)_dhl_(_dot_)_com>]

Hi,

  My problem:

  -ext0 x1.y1.z1.w1->
  -------------------OpenBSD 3.1. -->int0 10.0.1.x
  -ext1 x2.y2.z2.w2->

  * Two external interfaces connected to Internet.: ext0 and ext1
  * One internal interface connected to LAN : int0

  Nat to give access from Lan to internet : OK
  I want to be able to have a primary MX with port forwarding from ext0
to point to internal mail server, and a secondary MX with port
forwarding  from ext1 to point to the same internal mail server.  I use
'rdr' in nat.conf for this.

BUT:
* ext0 has gateway x1.w1.y1.V1
* ext1 has gateway x2.w2.y2.V2
If I define the gateway of ext0 as my default route then the mail works
for ext0 but ext1 doesnt (timeout, no connection)
And if I define the gateway of ext1 as my default route then mail only
works using ext1 but not for ext0 (same prob)

Question:
How do I tell the box to route the incoming connections back to where
they originated ???  I already tried addding additional routes voor the
external ip of ext0 and ext1 but doesnt make sense and it doesnt work !
I think I should use the "dest dest_addr" in the hostname.ext0 and
hostname.ext1 files but I dont find much info on how this works. I have
clearly have a routing problem and I am looking for clues on how to
solve this....

Any help welcome.. thx in advance.

  Koen

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