[OT] Source Based Routing

["Martin Marcher" <martin.marcher@gmail.com>]

Hello,

i have a setup where i have a borderline box that has 5 public IP
Addresses (this is for the sake of example: 192.0.2.8/29), all is
NATed to 10.200.10.0/24. Now the IP the provider uses as gateway is
192.0.2.9 which makes me have 192.0.2.10-14 as a usable range.

The default gateway on my borderline box is 192.10.2.10.10 which makes
all traffic from my network look like it came from this address which
was fine until now.

Say I want 10.200.10.50 to look like it came from 192.0.2.11 how do I do that?

I found http://www.wlug.org.nz/SourceBasedRouting which seems to do
what I want the approach also seems easily extensible since I could
easily add more addresses to a certain routing table, or maybe even
add more routing tables so that I could use the full range as outgoing
IP addresses depending on the source IP address.

Am I on the right track?

FYI: The purpose is that I want to have an outbound mail server and a
seperate inbound one. And I want to have them use 2 different IP
Addresses - if you know a simpler approach to this (the constraint is
to keep a single borderline box) I'm very much open to suggestions

thanks
martin