How to block messangers
I have created a rule in firewall to block yahoo messanger and rediff even i put the block rule as the first rule even though it doesnt work i have blocked 5050 for yahoo and for rediff i blocked 1863 and blocked tcp and udp for both the ports could any body help me what might be the issue why it is not blocking
Blocking IM completely is near impossible thanks to the existence of sites like meebo.com. Meebo is also available via HTTPS.
You can try to block the messenger programs by destination IP, but even this can be extremely difficult as IPs change regularly. Googling the subject will give you an idea of the situation. In the meantime you could use IMSpector to make sure you're logging all the IM traffic and take action accordingly.
OpenDNS.com has a feature to block "chat", you could always give that a try and see if it works.