The SINUS Firewall is a TCP/IP packet filter for Linux. Some of its features are stateful inspection of TCP communications, text-based configuration, graphical management interface for configuration of several firewalls, dynamic rules, prevention of packet and address spoofing, extensive logging, alerting, and counter intelligence.
The Seattle Firewall is an ipchains firewall that supports IP masquerading and can be used on a standalone system, on a dedicated firewall system, or on a multi-use gateway/server. It supports VPN via IPIP tunnels, IPSec, and PPTP. It is easily configurable by editing configuration files, and can be extended without modifying the base product. It also includes realtime monitoring with an audible alarm that sounds when suspect packets are detected.
pks-commands.php3 allows your Web server to search and add PGP/GPG keys from the public keys out there. It takes the TCP 11371 port connection and does it all on the web server. It is good in environments where the client machines are unable to get to arbitrary TCP ports (such as behind tightened firewalls).
PMFirewall is an Ipchains Firewall and Masquerading Configuration Utility for Linux. It is designed to allow a beginner to build a custom firewall with little or no ipchains experience. This firewall should work for most Workstations, Servers, and Dual NIC routers using either a dialup, DSL, Cable, or LAN setup. It is restrictive to outside attacks while still being as transparent as possible to those inside.
nstreams is a program that analyzes the networks streams occuring on a network and prints them in a human readable form. This is useful when you want to set up a firewall but do not know your needs/the needs of your customers. nstreams can read tcpdump output files or directly listen on a given interface, and may even produce ipchains (Linux) or ipfw (BSD) firewall rules instead of printing the streams, letting you build your firewall automagically.
The Linux dshield.org Perl Client package consists of an updated Linux dshield.org Perl client for submitting kernel firewall filter log entries to dshield.org. It has been written to implement tighter coding and better processing than the Perl client currently available on dshield.org.
JFwadmin is a Java 2 high-level X11 tool for ipchains. The GUI displays easy-to-understand services. Features include scripts generation, firewall save and restore, automatic interface and IP address and routes detection, current firewall configuration display, and handling of masq-modules and port-forwarding.