Please help and give advice: My company has 2 different models of PIX,one is 515E (UR) & 515 (R). 515E has 5 interfaces (but only 3 in use, which are eth1, eth2, eth3. It is used for Internal network only. The other one 515 has only 3 interfaces (which is eth0, eth1, eth2). It was used for Internet connection. Now I have replaced firewall to Juniper. So the old PIX is now spare and I was asked to change as reduntant PIX for 515E. I know 515 cannot be a failover due to HW limitation. My boss asks me to make 515 as reduntant backup firewall in case primary one fail, I can manually switch to second one. Now I need to make exact config as 515E on 515. However, one thing I concern the interface 0, is this interface hardcoded set to outside interface? Can I change interface 0 to any like DMZ, inside, or whatever I name it?

PIX's interface 0 is always outside/unTrusted interface. Thanks.

I understand that if0 is always set to untrust interface by default, however, the expansion card has only one interface on PIX, how do I use if0 as perimeter interface?