MSN Messenger 6.0. How to block it?

[Bifa]

Hi people!

The scenario:

- Workstations using MSN Messenger 6.0.
- ISA Server running in Proxy mode only
- Symantec VPN Appliance model 200 working as hw firewall

The problem:

My lovely users were not happy enough using the chat facility in MSN. They discovered how to transfer files with the system. The result: our antivirus started flashing alarms everywhere.

The question:

How the hell can I prevent them from tranferring files considering the scenario above? I am trying several alternatives but nothing is working properly. I am starting to believe that uninstalling MSN from the ws is the best way out...

I would appreciate any suggestions you may have...



C ya!

Bif@
"Try to make the best even better"

 

[Knutern]

For filetransfer to work with MSN Messenger, you must have TCP 6891-6900 in- and outbound open. These are the ports that are necessary for filetransfer to work.

If you disable those, users will not be able to transfer files with remote users.

It will still be possible to transfer files within your LAN however. If you want to disable this too, then you need to create IP Filter rules on your switches/routers to stop TCP 6891-6900 traffic.

Cheers
Knutern