RE: Blocking IM

Many of the latest P2P and chat clients are capable of using any ports,
including 80, 443, etc.  In all likelihood you should be proxying all
outbound traffic through your content filter.  Most of these can inspect at
the application layer and can be configured to block IM, P2P, etc.

-Spyro Malaspinas

Yahoo! Messenger services uses a variety of ports. 


Service 

Ports 


Chat & Messenger 

TCP Port 5050: Client Access only 


Insider/Room Lists 

TCP Port 80: Client Access only 


File Transfer 

TCP Port 80: Server Access.
Your ISP may block this port, as its used for web hosting.
You can change port in Messenger, Preferences, File Transfer. 


Voice Chat 

UDP 5000-5010
TCP 5000-5001: Client Access
If UDP Fails, TCP will be used instead, see below. 


WebCam 

TCP Port 5100: Client Access 


Super Webcam 

TCP Port 5100: Server Access 


P2P Instant Messages 

TCP Port 5101: Server Access
PMs between Buddys may not use the Yahoo! Server, but this is not a
requirement.

 

 

 

  _____  

From: Morales, David (Seta) [mailto:David_Morales@onr.navy.mil] 
Sent: Tuesday, December 06, 2005 12:51 PM
To: firewalls@securityfocus.com
Cc: Amiryar, Edris (Seta)
Subject: Blocking IM

 

We are blocking IM at the Firewall (juniper 5200) and through Surf-control
(Web Filtering product, but we are still able to connect to Yahoo IM. Has
anyone been able to do this successfully? And, does anyone have a list of
ports to block so we cannot get to this IM?

Thanks in advance,

David Morales

moraled@onr.navy.mil