OPNsense is a HardenedBSD-based specialist operating system (and a fork of pfSense) designed for firewalls and routers. It is developed by Deciso B.V. in the Netherlands. Some of the features of OPNsense include forward caching proxy, traffic shaping, intrusion detection, two-factor authentication and easy OpenVPN client setup. The project's focus on security brings a number of unique features, such as the option to use LibreSSL instead of OpenSSL (selectable in the GUI). OPNsense also includes an update mechanism that delivers important security updates in a timely fashion.

https://opnsense.org/

https://distrowatch.com/table.php?distribution=opnsense