Question : How to block web proxys like ninjacloak.com?

Hi.

Recently, i installed a proxy on my Windows 2003 Server, and it's working fine... the only problem is that one of my users is using web proxy services like "ninjacloak.com" to avoid the security...

Is there a way to block such services?

Answer : How to block web proxys like ninjacloak.com?

Would be good if you can add content filter into the infra. E.g. bluecoat (they have a free agent called k9) and lockdown the user client proxy setting (assuming they are only user and has no admin privilege, shd not grant them anyway).

You can also check out my answer in  ID: 23295100, on the use of proxy.pac or wpad (but that also need user mode to restrict unauthorised changes)
@  http://www.experts-exchange.com/Networking/Security/Q_24024960.html