6 Best Open Source Firewall Solutions

Security is paramount. Security involves defense in depth. Approaching security one step at a time, with consistency and rigour, you can mitigate threats, and keep intruders at bay.

FirewallIntruders use a variety of different techniques in an attempt to compromise a system. For example, systems can be attacked by denial of service, cracking, intrusion, snooping (intercepting the data of another user), or viruses/worms/Trojan horses. To have a secure box, a system therefore needs a variety of defenses.

One important step to protect a system is using a firewall. Essentially, this is a network security system, acting like a security guard between internal and external networks. The firewall controls incoming and outgoing network traffic using security rules. The rules specify which connections you want to allow and the ports and zones through which the connection can be established.

All of the software featured in this article is released under an open source license. Each of the solutions offer a comparable set of features to many expensive commercial firewall solutions.

There are dozens of open source firewalls to download. To provide an insight into the quality of software that is available, we have hunted high and low for the finest firewall solutions. All 6 open source firewall solutions below are worthy of recommendation, but if we had to recommend a single solution, our award would go to pfSense – this is based on FreeBSD not Linux.

pfSensePowerful firewall and routing platform based on FreeBSD
ClearOSDedicated firewall and Internet server/gateway
UntangleQuality open source alternative to SonicWALL and WatchGuard
IPFireDistro with a versatile and state of the art firewall engine
Smoothwall ExpressFirewall with its own security-hardened Linux distro
ShorewallHigh-level tool for configuring Netfilter

Read our complete collection of recommended free and open source software. The collection covers all categories of software.

The software collection forms part of our series of informative articles for Linux enthusiasts. There's tons of in-depth reviews, alternatives to Google, fun things to try, hardware, free programming books and tutorials, and much more.
Share this article


  1. Do you known the NETDEEP SECURE FIREWALL?
    Is the first Next Generation Open Source Firewall and is available in Portuguese, English and Spanish.

Share your Thoughts

This site uses Akismet to reduce spam. Learn how your comment data is processed.