Legacy
Some firewall software are no longer being maintained. These are supported but NOT recommended.
ConfigServer
We have been using Configserver Security and Firewall for years, but the company behind it has recently shutdown:
Possible Future ?
Shorewall
Shorewall is a simple file wall that is no longer maintained but still being used extensively (especially behind CSF - inside system containers and virtual machines)
Easywall
Easywall is an easy to use firewall that is no longer maintained but has been popular in limited situations where maximum ease of use is required.