IPFire : A Linux firewall distribution that is built from source and comes with lots of additional features

IPFire is a Linux firewall distribution that is built from source and comes with lots of additional features. It is easy to set up and administer. It features a firewall with stateful inspection, a content filtering engine, traffic control (QoS), VPN technology, and a lot of logging.

• Licenses : GPLv3
• Operating Systems : POSIX, Linux

NuFW is an authenticating firewal

NuFW is an authenticating firewall. It adds strict and secure identity-based filtering capabilities to enterprise-grade firewalls. It can also set quality of service on a per-user basis and log user activities into an SQL database. Furthermore, it can use multiple external authentication sources via PAM and be the key of a Single Sign On solution.

• Licenses : GPLv3
• Operating Systems : POSIX, Linux
• Implementation : C

Firewall Builder consists of a GUI and set of policy compilers for various firewall platforms

Firewall Builder consists of a GUI and set of policy compilers for various firewall platforms. It helps users maintain a database of objects and allows policy editing using simple drag-and-drop operations. The GUI and policy compilers are completely independent, which provides for a consistent abstract model and the same GUI for different firewall platforms. It currently supports iptables, ipfilter, ipfw, OpenBSD pf, Cisco PIX and FWSM, and Cisco routers access lists.

• Licenses : GPL
• Operating Systems : POSIX Linux BSD FreeBSD
• Implementation : C, C++

Vyatta : A Linux-based routing and security distribution

Vyatta is a Linux-based routing and security distribution. It is meant to deliver a flexible, affordable alternative to Cisco 1800 through 7200 series routers. Vyatta is also a great virtual router, virtual firewall, virtual security solution for VMware, Xen, XenServer, and KVM virtualization projects.

• Licenses : GPLv2
• Implementation : C, C++

Service Guardian aims to protect servers against various things such as resource exhaustion and connection floods

Service Guardian aims to protect servers against various things such as resource exhaustion and connection floods. It can measure the number of connections to servers' ports and, after a grace time period, compares and sees if the host is still in violation of the specified settings. If a host is in violation of the settings, it will be filtered out and dropped via netfilter/iptables.

• Licenses : GPLv3
• Operating Systems : POSIX, Linux
• Implementation : C

Sshguard monitors services through their logging activit

Sshguard monitors services through their logging activity. It reacts to messages about dangerous activity by blocking the source address with the local firewall. Sshguard employs a clever parser that can transparently recognize several logging formats at once (syslog, syslog-ng, metalog, multilog, raw messages), and detects attacks for many services out of the box, including SSH, several ftpds, and dovecot. It can operate all the major firewalling systems, and features support for IPv6, whitelisting, suspension, and log message authentication.

Licenses	BSD Revised
Operating Systems	POSIX
Implementation	C

SafeSquid : A content filtering proxy server

SafeSquid is a content filtering proxy server. It supports 'profiled' Internet access, a browser based interface, very fast throughput, DNS caching, content caching, pre-fetching, bandwidth control, virus scanning, ICP, CARP, and ICAP clients, source, target, and time-based granular firewall style rules to allow or deny content like music, videos, Flash and Java applets, messengers, chats, cookies, ActiveX, scripts, etc., remote authentication, real-time text and image analysis for blocking pornography, and an URL filter.

• Operating Systems : POSIX Linux

DeleGate : A multi-purpose application level gateway or proxy server

DeleGate is a multi-purpose application level gateway or proxy server that mediates communication of various protocols, applying cache and conversion for mediated data, controlling access from clients, and routing toward servers. It translates protocols between clients and servers, converting between IPv4 and IPv6, applying SSL (TLS) to arbitrary protocols, merging several servers into a single server view with aliasing and filtering. It can be used as a simple origin server for some protocols (HTTP, FTP, and NNTP).

• Licenses : Free for non-commercial use
• Operating Systems : Unix, Mac OS X, Windows, Mobile
• Implementation : C

Sshguard monitors services through their logging activity

Sshguard monitors services through their logging activity. It reacts to messages about dangerous activity by blocking the source address with the local firewall. Sshguard employs a clever parser that can transparently recognize several logging formats at once (syslog, syslog-ng, metalog, multilog, raw messages), and detects attacks for many services out of the box, including SSH, several ftpds, and dovecot. It can operate all the major firewalling systems, and features support for IPv6, whitelisting, suspension, and log message authentication.

• Licenses : BSD Revised
• Operating Systems : POSIX
• Implementation : C

Endian Firewall : An all-in-on Linux security distribution that turns any system into a full-featured security appliance

Endian Firewall is an all-in-on Linux security distribution that turns any system into a full-featured security appliance. It features a stateful packet inspection firewall, application-level proxies for various protocols (HTTP, POP3, SMTP), anti-virus support, virus and spam filtering for email traffic (POP and SMTP), content filtering of Web traffic, and a "hassle free" VPN system based on OpenVPN.

• Licenses : GPL
• Implementation : Perl, Python, C

NuFW : An authenticating firewall. It adds strict and secure identity-based filtering capabilities to enterprise-grade firewalls

NuFW is an authenticating firewall. It adds strict and secure identity-based filtering capabilities to enterprise-grade firewalls. It can also set quality of service on a per-user basis and log user activities into an SQL database. Furthermore, it can use multiple external authentication sources via PAM and be the key of a Single Sign On solution.

• Licenses : GPLv2
• Operating Systems : POSIX, Linux
• Implementation : C