Block Yahoo Messenger

can anyone help me with the ACL to block yahoo messenger for my cisco 1841 router, we have about 20 users sharing the 128kbps connections.

some of the staff are typing the message none stop that why we are looking into blocking the yahoo messenger and google gtalk, thanks in advance!

u cant block the messenger using Router........for that u need to purchase any UTM deveice or websense software...................

u cant block the messenger using Router........for that u need to purchase any UTM deveice or websense software...................

This is because Messenger application (and many many more such as P2P applications) can now tunnel through open ports, more commonly port 80. With the addition of a UTM or something like Websense, it can monitor the HTTP traffic and block anything that is trying to tunnel through it.

A cheap solution to this problem could be something like ISA 2006. THis allows filtering of HTTP traffic so you can added different UserAgents to identify this type of traffic. For things like MS Messenger, its sends a UserAgent that identifies the traffic, this you can detect and block accordingly.

Here is a website i wrote (and unfortunatley haven't had time to develop it and maintain it) www.applicationsignatures.com/backend/index.php . I may actually do a little work on it at some point....who knows :) , it has some application signatures that can be used with MS ISA in this manor.

Cheers

Have you thought about blocking MS Messenger from the running in the first place? Maybe block the application from being installed/running?

Thanks everyone for the reply, look like I have to look into MS ISA server.