Just a heads up.
Depending on how your filtering is setup, seems someone over at Facebook is having some fun.
You can type as many www you like in front of facebook.com and it will work.
So if you just have facebook.com and www.facebook.com blocked it’s possible your users now have Facebook access.
However if your keyword blocking you should be ok!
As a test without keyword blocking http://www.www.www.www.www.www.www.www.www.www.www.facebook.com/home.php
Was actually valid!
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