Multiroute question

[Juan José Sánchez Mesa]

Hi!

(sorry for my bad english)

I have a FreeBSD machine (8.2-RELEASE-p3). The machine has two ethernet 
cards, configured in this way:

- Card A: internet IP address
- Card B: intranet IP address

Default route goes via card A.

Now, on the intranet I have a "normal" DSL router. Then, using NAT i've 
forewarded a simple port from the DSL to the intranet IP of this machine.

The incoming packets from the DSL comes ok to the machine (via card B), 
but the outgoing packet goes to card A, due to the default route.

There is a way to configure the network so that outgoing packets goes to 
the card from where the incoming packets was arrived ?

Or is this impossible to configure ?

Thanks!!!