I currently have an issue with inability to reach my internal server from outside the firewall. here's my setup.
Internet client -> public IP on Adtran hardware firewall -> internal IP of WebServer1 (Windows 2008 R2)
If telnet from the internet client to public IP of WebServer1 (forwarded to the internal IP) on port 80, the connection times out. If I telnet from an internal client to the internal IP of WebServer1 on port 80, it works fine.
My first thought is a hardware firewall issue but I don't think that's the case. If I unplug WebServer1 and replace it with WebServer2 (give it WebServer1's internal IP and plug it into the same port on the switch) then telnet on port 80 from the internet works fine. Given that, there is something specific to WebServer1.
I can't figure out what is causing WebServer1 to be unavailable. I've validated that there is no software firewall running on the server (and besides, connections from internal IPs work fine).
The server is a new Dell T310 with a dual-nic broadcom netxtreme cpu. It's using the latest Broadcom drivers and firmware. It's running only the following software, none of which I think has a firewall:
1. Exchange 2010.
2. Microsoft forefront endpoint protection
3. Microsoft forefront for Exchange
4. symantec backup exec