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How to Block Instant Messaging

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by chery

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Hi, I would like to know how to prevent or block the user in the company to access to Instant Messaging or any P2P software cause it takes up alot of the internet bandwidth. Currently, my company is using firewall to secure the incoming and outgoingcommunication. How do I log the record of user using IM or P2P software via firewall? Please help.

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by richard lane

The first step I would suggest is to get a copy of the white paper 'Risk Exposure Through Instant Messaging and Peer-To-Peer Networks' from Internet Security Systems' (ISS) X-Force. This paper gives a relatively comprehensive list of the various clients (IM and P2P) and how to block/monitor them. Although it is dated April 2002, it is still pretty accrate.

The main problem with trying to block the IM clients is that many of them automatically drop to using port 80 if their native port is blocked. For example, MSN Messenger 6 normally uses port 1863 for all communications (file transfers, IM, online games etc.). If you block this port, it switches to port 80, but with limited functionality (IM only basically). To block the use completely, you need to block access to the relevant sites that the clients connect to, as well as the ports that they normally use.

E-mail me directly if you cannot find a copy of the report anywhere. lane_ri@hotmail.com

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