troubleshooting Question

Port blocking problem

Avatar of ScorpioUltima
ScorpioUltima asked on
Windows Networking
17 Comments2 Solutions405 ViewsLast Modified:
Apologies if this is not the most appropriate area to post this but I have a problem with an SBS2003 network as follows:

Small network (Server & 5 workstations). Brand new Fujitsu server built using mostly the defaults, configured to be an Exchange server, allowed access from the Internet to Ourlook Web Access & RWW - the same as I have setup many servers for other clients. However, in this case the server does receive any communications from the outside world to any of the ports that are open, i.e. I can telnet to port 25 on the server from the LAN but not from the outside world. 1st thought was that the router was faulty (We had already identified another fault with it) so a replacement router (Netgear DG834PN) was installed and configured to port forward ports  25, 80, 443, 1723 & 3389 to the server IP address on the LAN. This did not change the situation though, I still cannot receive mail or RDP onto the server from the Internet, only from the LAN. 2nd thought was that the ISP is blocking the ports that they want to be able to access, unfortunately the ISP (BT)appears to have a technical helpdesk staffed by non nechnical people who simply refer to an FAQ and cannot understand the question :(

If it helps at all, the server *can* send mail to both internal and external recipients, however, the clients only receive mail that originated within the LAN. The router logs show a few connections on port 25 but nowhere near the expected number - i.e. in 2 hours the router showed 2 connections to port 25 but I had sent at least a dozen outbound mails to an autoresponder that I use to test email connectivity. There were no connections to port 3389 showing although I had tried to connect to RDP a couple of times.

Any ideas? Faulty router? ISP Port filtering/blocking? The couple of connections to port 25 bothers me, without those I would be confident that it was ISP port filtering :(
Keith Alabaster
Enterprise Architect
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