IP translator

[Hakan Thorngren <hth%iar.se@localhost>]

We have a small UNIX (Amiga and SUN sparcs) network at home with a dial up 
internet connection (single IP address, dynamically allocated each dial up).

At the moment, the modem is attached to an Amiga 3000 running NetBSD.
To access internet, we have to connect to the Amiga and make telnet/ftp 
connections to the outside world.
It works just fine, but we really would like to use Netscape which is
only available for SUN.

I see two solutions:

1. Move the modem to one of the SUNs.
2. Get some IP translator software for the Amiga so that it can relay
   IP between the nets properly.

I would prefer an IP translator as it would solve the problem, not cure
the symptom.
A firewall would probably do the job, but I am really only interested in 
the IP translator part and want something simple and free.

Where can I find an IP translator that can be used with NetBSD?