Blocking Anonymous Web Proxies in Your Office

This is a big one for enterprises trying to control malware spread by reckless web surfing in the office. Many companies set up proxies with filters to control traffic, but there are still tools out there for circumventing proxies and bypassing web firewalls.

In this tip on TechTarget's SearchSecurity web site, John Strand provides some ways to prevent these practices. I had also written a tip for SearchSecurity on blocking web anonymizers in 2006.

Amazingly, little has changed since then. The basic defenses remain the same: a combination of web use policies (admittedly easily ignored but useful for HR), filtering traffic on known ports and IP addresses of proxy services and blocking downloads from the web.