In our school we have a isa 2006 firewall and we have more then 300 users. They are managed in groups which are teachers they have access to youtube and fb. But the other students group there are many students that are able to use facebook for some unknown reason. I have created a rule which is able to block but he managed to join facebook via https and i have also managed to lock this damn site but he still is able to do it. I have also in our isa server installed GFI webmonitor which is in a group where people cannot use facebook but he still got access to that. I saw his user and he is no administrator or something else. Any ide how to lock this person using facebook?