The shorewall firewall is one of the most powerful firewalls, and most used in GNU/Linux servers.
However, in many Linux distributions (such as Debian or Ubuntu), when installing it, the configuration files are not installed (you have to create them by hand).
There is also no configuration tool installed.
The shorewall_config_online provides a online simple tool to conveniently configure the shorewall firewall, suitable for shorewall version 4 and 5 (IPv4).