What ports do I need to block to attempt to prevent IM on my network?
To prevent IM, try the following:AOL: In and outbound TCP port 4443
AOL: *ALL access to login.oscar.aol.com on all port .NET: In and outbound TCP 6891
.NET: UDP Ports 13324 & 13325
.NET: TCP Port 1503
.NET: msgr.hotmail.com Yahoo: Block all in and outbound TCP Port 5010
Yahoo: *ALL *.msg.*Yahoo.com AOL.ICQ: Block In and out TCP Ports 5190 & 4001, UDP 4000
AOL.ICQ: Block ports 3474 and 7320 for TCP
AOL.ICQ: Block all TCP 5190, 4001 & UDP 4001 & 4000 to login.icq.com Further information can be found at http://www.infosecuritymag.com/2002/aug/cover.shtml.
For more information on this topic, visit these other SearchSecurity.com resources:
Best Web Links: Secure messaging
News & Analysis: The risk and intrigue of IM to the enterprise
Web Security Tip: Prevent hackers from sneaking in through IM