Urgent help required please Cisco Pix506e & ISA2004

Dear network experts,

Im in the middle of re-designing my works network, and I would like to implement a DMZ. We have a cisco PIX 506e which does not have a third interface for a DMZ so I was thinking of using ISA in conjunction with my cisco firewall.

The cisco f/w does NAT at the moment and handles at least 5 public facing IPs for mail, ftp etc

The ISA server supports 3 interfaces to my knowledge, Public, Private and DMZ. I was thinking of having the LAN connected to the Private Interface, the DMZ interface connected to the CISCO, so the cisco will still handle the public facing IPS and do NAT to the DMZ, i'm not sure however what I would use the Public interface for?

I haven't implemented anythign yet but I need to produce a plan wthin the next few days so if anyone has a ccna and knows ISA server very well, and can help me, i would be greatly appreciated.

Kind Regards,

Wayne.

Help from the cisco side would be great, we just need an MS expert now

Yep a DMZ is a must, NAT is ok but it's not that secure, if any of my servers get compromised while the network is on a NAT topology, then the whole network is at risk, if a server gets compromised in the DMZ, there will be another few layers of security the hacker would need to get through.

I was thinking of using the PIX for purely packet inspection, and allowing the ports I allow open to pass to the ISA Server, and then setup ISA server to do NAT, this may not be the best config, it may need a mixture of both, not sure yet as I do have 5 public facing IPs which the pix uses for NAT, i may let the pix continue doing that, not sure need to get advice and real quick

Unfortunatly I lack the pix experience, i can do things through the pdm but it has its limatations, really i need to use the command line to have full control over it, but i don't have those skills, so i was also thinking of moving that part of the network config onto ISA server, as i have better ISA admin skills then I do with the pix.

Kind Regards,

Wayne