noah is right, let me modify the configuration so that you can use real IP and masq_ip as well: ROUTER-------- Linux ------ | | | | Internal_IP | | ---------- ---------------- | HUB 2 | | HUB | __________ ---------------- |||||||||| | | | | | | | | Yes, you need another other hub, but you need one less network card. Many people use this arch. for home LAN. I could show you the ipchains rules for your reference but only upon your request.