Zorp GPL has been discontinued. Similar apps include OPNsense, which is free and open source. Other options are pfSense, IPFire and Smoothwall. In total there are four Firewalls like Zorp GPL for Linux and self-hosting.
OPNsense includes most of the features available in expensive commercial firewalls, and more in many cases. It brings the rich feature set of commercial offerings with the benefits of open and verifiable sources.
Netherlands
EU
pfSense is a free and open source firewall and router that also features unified threat management, load balancing, multi WAN, and more.
United States
The SmoothWall Open Source Project was set up to develop and maintain SmoothWall Express - a Free firewall that includes its own security-hardened GNU/Linux operating system and an easy-to-use web interface.
United Kingdom
