Shorewall (shell-based compiler for Shoreline Firewall)

The Shoreline Firewall, more commonly known as "Shorewall", is a
Netfilter (iptables) based firewall that can be used on a dedicated
firewall system, a multi-function gateway/router/server or on a
standalone GNU/Linux system.

This is the shell compiler part of Shorewall that allows running
Shorewall with legacy configurations, but shorewall-perl is the
preferred compiler, please use it for new installations.

You will also need the shorewall-common package.