Firestarter is a personal firewall tool that uses the Netfilter (iptables/ipchains) system built into the Linux kernel.

Firestarter provides a graphical interface for configuring firewall rules and settings.

Firestarter also provides facilities for port forwarding, internet connection sharing and DHCP service.

Firestarter is free and open-source software and uses GUI widgets from GTK+.

Note that it uses GTK2 and has not been upgraded to use GTK3 so the last Linux distributions it will run on are Ubuntu 18, Debian 9, etc.