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How To Control Or Block Instant Messengers With SafeSquid Proxy Server

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.
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