In this tutorial I will explain how you can control or completely block access to a few instant messengers with SafeSquid, like Google Talk, Google chat within Gmail, MSN Messenger, Yahoo Messenger and Skype. Once you are familiar with the method of blocking these messengers, you should be able to block other messengers. Please note that these methods will only be effective, if you block all direct access to the router and firewall, except required ports like 25 & 110, so that users are able to access the net only through the proxy server. When all higher ports are blocked, most messenger try to communicate on port 80 and 443, which will have to go through the proxy, and thus allow you to control them. Most messengers also allow you to define proxy settings and username / password for authenticating Proxies.