Re: Blocking port 25 outbound

[CHARLES MORROW-JONES <morrow-jones.2 () OSU EDU>]

This is probably obvious, but find out who is using port 25 before you block it, and don't rely on a few weeks of flow 
data to tell you the whole story. We recently did a survey of our departmental network administrators asking them to 
list machines that send mail, and many hosts appeared on the list that only send mail occasionally (as an example, an 
administrative department that sends out quarterly satisfaction surveys).

Charles R. Morrow-Jones
Director, Security
Office of the CIO
The Ohio State University
morrow-jones.2 () osu edu -or- 614.292.1302

----- Original Message -----
From: "Lazor, Joseph" <JLazor () ADMIN FSU EDU>
Date: Monday, August 22, 2005 3:29 pm
Subject: [SECURITY] Blocking port 25 outbound

> Hello out there,
>
>
>
> We are considering blocking all port 25 traffic outbound.  We have
> notedvarious ISP's and others moving to block port 25 outbound to
> reduce"spamming".  We wish to be good "netizens"
>
> Have any of you done this already and what has been the push back of
> issues related to implementation on your campus?
>
>
>
> Regards,
>
>
>
> Joseph A. Lazor
>
> Florida Sate University