Web filtering

As the modern internet works on top of protocols such as HTTP and DNS, web filtering is one of network administrators' most desired features in their firewalls to keep network users under some control. On OPNsense, this feature doesn't have a dedicated functionality as a core feature or an official plugin; instead, the web proxy achieves web filtering by configuring it with some additional features the OPNsense team has added since the project started. As the web proxy functionality on OPNsense is Squid-based, let's take a closer look at the Squid web proxy project to better understand this filtering matter.

The Squid project website definition is reproduced here: "Squid is a caching proxy for the web supporting HTTP, HTTPS, FTP, and more. It reduces bandwidth and improves response times by caching and reusing frequently-requested web pages. Squid has extensive access controls and makes a great server accelerator." (http://www.squid-cache.org...