Hi all. I'm currently experiencing a weird issue with one of our servers. The server suddenly stopped to response to telnet on port 25. Affected server is running DC, Exchange, DNS and DHCP. The functionality hasn't been lost completely, it's only when we try to telnet on port 25 to 10.0.0.1 or server name from the server itself or any other network location within the subnet. However, affected server still can telnet on port 25 to 127.0.0.1 and own server name, also all emails still being sent and received on the Exchange server installed on that box. We can also ping and telnet on any other port to this machine from the entire subnet. Port 25 has stopped to respond to telnet last week, out of sudden, without any other symptoms. No changes has been made to any of the servers and firewalls. Also the host file looks absolutelly normal and the only record in file is set to 127.0.0.1 localhost. Apart of rising the alerts in our monitoring software it doesn't seems to affect anything else and no problems was reported by the end users. However, this seems to be a bit worrying as without working telnet on port 25 we can't monitor the Exchange server. I would appreciate if anyone could advise or help.

Hi Santosh. Thank you for your post. As far as we know there was no changes made to the server and firewall configuration especially that telnet traffic on port 25 has stopped at 2AM. Apart of us no one else have the access to the server. The server is in deed SBS box so if I'll have no luck with netstat I'll move the thread on to SBS forum. Thanks a lot!

At the end of a day this problem was resolved by server reboot.

At the end of a day this problem was resolved by server reboot. Good to hear that. Thanks for sharing the information.I do not represent the organisation I work for, all the opinions expressed here are my own. This posting is provided "AS IS" with no warranties or guarantees and confers no rights.