Here's my scenario:
Going to install single exchange server behind a cisco router/ios firewall. Would like to be able to use OWA(outlook web access). Trying to do this as secure as possible. Do not want to put the server out on the DMZ as it belongs to the domain and do not want to put it on the internal network with holes punched in the firewall. Can't afford another server to put out on the DMZ as an SMTP gateway or to run ISA. MS has recommended that the best way to do this is with 2 nics installed in the exchange server. The external connected to the DMZ and the internal connected to the internal network. Then Co-locate both ISA and Exchange on the same server and create server publishing rules to allow the exchange server to be published to the internet via the external nic. ISA would then intercept incoming mail and connections to OWA on the external nic, filter the traffic and forward it on to the internal nic. I really do not want to use ISA though. Could I accomplish the same with the router/ios firewall or should I use ISA as an extra layer of security???
Thanks in advance,