RE: NAT Configuration for Dual WAN Router


I've been trying over and over to figure this one out, but I'm just
the end of my wits. We have a remote office that can only get 768Kbps


which they've not totally maxed out. So management's solution now is


a second DSL line, but they won't let me buy a dual WAN router (in


add a 3rd DSL line).

Have you looked OpenBSD with pf? You can create rules that map outbound
session to a different DSL router, interface, and/or gateway based on
any number of rules. The man page pf.conf[1] and more precisely the
"ROUTING" and "POOL OPTIONS" section will allow you to create very
dynamic rules to define how to handle all outbound routing load sharing.
NATing also comes along for the ride.

A basic example is in their FAQ[2].

This type of setup is not the most common so a straight up HOWTO is most
likely not going to be found. Sorry I am not able to give a more direct
and Linux based answer.

[1]: pf.conf(5) - OpenBSD manual pages
[2]: OpenBSD PF: Address Pools and Load Balancing


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FreeBSD with IPF \ IPNAT [1] or PF as well.

You have a number of options but consider the long-term.

I guess you've already bought the second DSL line ? The cost of the lines ( and routers ) combined might not be far away from another type of carrier that may work with your future requirements. Look into bonding T1's.

If you don't already, it might help to start analyzing your traffic characteristics.