It has a simple and easy to learn configuration that allows both simple and complex configurations. It blocks connections to and from hosts specified in huge block lists (thousands or millions of IP ranges).

PeerGuardian (pglcmd) - Privacy oriented firewall application.

Uncomplicated Firewall - Simple front-end for iptables.

You describe your firewall/gateway requirements using entries in a set of configuration files.

Shorewall - High-level tool for configuring Netfilter.

firewalld (firewall-cmd) - Daemon and console interface for configuring network and firewall zones as well as setting up and configuring firewall rules.

Each interface can be configured separately via its own configuration file, which holds an easy and human readable syntax.

Firetable - Tool to maintain an IPtables firewall.

It makes building even sophisticated firewalls easy - the way you want it.

FireHOL - Language to express firewalling rules, not just a script that produces some kind of a firewall.

The firewall configuration resembles structured programming-like language, which can contain levels and lists. It allows the entire firewall rule set to be stored in a separate file, and to be loaded with one command.

ferm - Tool to maintain complex firewalls, without having the trouble to rewrite the complex rules over and over again.

Supports: NAT and SNAT, port forwarding, ADSL ethernet modems with both static and dynamically assigned IPs, MAC address filtering, stealth port scan detection, DMZ and DMZ-2-LAN forwarding, protection against SYN/ICMP flooding, extensive user definable logging with rate limiting to prevent log flooding, all IP protocols and VPNs such as IPsec, plugin support to add extra features. Very easy to configure, handy to manage and highly customizable.

Arno's firewall - Secure firewall for both single and multi-homed machines.

The iptables package is an indirect dependency of the base meta package, so it should be installed on your system by default. You will only need to install the userland utilities, which are provided by the package iptables. The stock Arch Linux kernel is compiled with iptables support. Note: iptables is a legacy framework, nftables aims to provide a modern replacement including a compatibility layer.

Iptables linux