I remember visiting this website once...
It was called Sucuri WebSite Firewall - CloudProxy - Access Denied
Here's some stuff I remembered seeing:
Sucuri WebSite Firewall - CloudProxy - Access Denied
You are not allowed to access the requested page. If you are the site owner, please open a ticket in our support page if you think it was caused by an error: https://support.sucuri.net. If you are not the owner of the web site, you can contact us at firstname.lastname@example.org. Also make sure to include the block details (displayed below), so we can better troubleshoot the error.
CloudProxy is the WebSite Firewall from Sucuri. It stands between your site and the rest of the world and protects against attacks, malware infections, DDOS, brute force attempts and mostly anything that can harm it.
Not only that, but your sites get cached, speeding it up quite a bit. Interested? Visit https://sucuri.net/website-firewall