[OT] Port 25 vulnerability

Matt Laney mdlaney at MOREHOUSE.EDU
Fri Jan 30 16:13:48 GMT 2004


> Try doing an nslookup with type=mx on amazon or microsoft or even
> weldre5j.k12.co.us and then try telneting to port 25 of one of those servers

As others have shown, this works just fine, as well it should since telnet
and your MTA's SMTP are doing the same thing when they contact a remote
mail server.

Any chance you're behind a firewall that lets you connect to port 25 of
your ISP's mail servers but denies connections to other ports 25?

If your mail servers send mail out via your ISP's mail systems, that
would produce the behaviour you're seeing.


Matt Laney, mdlaney at morehouse.edu
Network and Unix Systems Engineer
Morehouse College --- Atlanta, GA

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