Block the URL by using the third proxy

[faizan.mahmood]

Hi, 

We are using the cisco 5525-x (with firepower) featured. We have already made the SSL VPN and site to site VPN on it. We have blocked the URLs like (youtube and facebook) but when the user use the third party proxy like (zenmate etc) they access the youtube, facebook and some other sites. Kindlu suggest me how can can we block the URLS like this open by the third proxy. 

Kinldy help us in that. 

[Marvin Rhoads]

You can add another acess control policy rule to block access to proxy/anonymizer sites.