I have an FTP server configured on an '08 R2 box behind a Cisco ASA 5505. I have no problems accessing the server internally. I can telnet from outside into the server on port 21. When I try to use the web browser (IE8 or Firefox) it prompts me for the credentials and then fails to connect. I have used both IIS7 and FileZilla (I even tried the FileZilla client) and nothing will connect. To me, this thing is screaming firewall issue and I think NAT might be getting underfoot, but I cannot find any reason for it. I have ports 20 and 21 open from outside and they are forwarded right to the server. I have tried passive and active mode with no avail...any ideas?