Routing With Two ISPs?

["." at babolo.ru]

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> I have a 4.8 box serving as a gateway with two connections to the
> Internet.  Is there some way to set the box up so that packets are
> routed out through the same interface from which they arrived?  For
> example, if a connection is initiated on port 80 from a packet arriving
> on one interface, is there a way to make the outgoing packets from my
> web server use that same interface as a gateway instead of the default
> interface?
> 
> Any suggestions appreciated.
It's easy IMHO

Each external iface with it's own natd,
each forwards 80 port incoming to two
http servers with different IP or port.

outgoing traffic can be forwarded to appropriate
natd via ipfw rules depending on src IP or port