> The only other way to achieve what you want is proxy arp. I 
> don't know if NetBSD supports this out of the box, though.

As far as I recall, isn't there an "arp pub" entry one can make so that
when the gateway asks how to deliver this packet, the netbsd box answers
and takes the packet, then forwards it on to the separate host, which has
been added to the routing tables as a static host entry available through
the second ethernet card?

On a local firewall I had to "arp pub" every single internal machine to
the firewall's internet gateway itself. This was RedHat though..
I've only had experience with Linux; for instance, there to tell the
kernel to deliver the packet to a specific host you can:

route add -host a.b.c.d dev eth2

after turning on packet forwarding and so forth..

Or am I completely off the topic of what the guy is trying to do? (The man
pages tell me there is similar functionality in NetBSD..)

Marc Tooley
sudog@dcss.douglas.bc.ca