Software

Ask something
Question Locked

port 25

0 helpful
3 replies

by cheryl

Closed to new repliesThis discussion is closed. It stays readable, but it takes no new replies.
We had to block port 25 using our firewall to protect our mail server. We had a root.kit on a computer that was sending mass emails. To prevent mass mailing to happend again we blocked port 25. Now we cannot email hotmail, msn or other pop accounts. How can we get around this & still block port 25 for protection.

3 replies

by forum surfer

We don't allow anything outside of our exchange server in our shop, per policy. Allowing users access to webmail is a very dangerous thing to do IMO. We did stop blocking port 25 however, now we simply don't allow access to webmail through security appliances.

by digitalfrog

but port 25 is for SMTP traffic, not POP3.
unclear if the infected machine was inside your network or outside the firewall or was your server itself?

A proper configuration would be to have an MTA (Message Transfer Agent) in a DMZ zone that has port 25 open to the outside internet. Your internal mail server should then be set to only accept port 25 from the MTA. If you are using MS Exchange you can do this through the relay access controls.

If you don't have the budget or facilities to setup an MTA, have your network person configure your routers to only allow your server to use outbound port 25 and still setup the relay access controls to deny all. This will prevent mailer viruses on your workstations from sending mail to the outside directly, or via your mail server.

This discussion is closed to new replies.