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.
Intruders 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.
Here’s our verdict captured in a legendary LinuxLinks chart. 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.

Let’s explore the 5 firewall distros at hand. For each distro we have compiled its own portal page, a full description with an in-depth analysis of its features, together with links to relevant resources.
| Firewalls | |
|---|---|
| IPFire | Distro with a versatile and state of the art firewall engine |
| OPNsense | FreeBSD-based firewall and routing software |
| pfSense | Powerful firewall and routing platform based on FreeBSD |
| VyOS | Router and firewall platform |
| ClearOS | Dedicated firewall and Internet server/gateway |
This article has been revamped in line with our recent announcement.
Explore our comprehensive directory of recommended free and open source software. Our carefully curated collection spans every major software category.This directory is part of our ongoing series of informative articles for Linux enthusiasts. It features hundreds of detailed reviews, along with open source alternatives to proprietary solutions from major corporations such as Google, Microsoft, Apple, Adobe, IBM, Cisco, Oracle, and Autodesk. You’ll also find interesting projects to try, hardware coverage, free programming books and tutorials, and much more. Know a useful open source Linux program that we haven’t covered yet? Let us know by completing this form. |


Do you known the NETDEEP SECURE FIREWALL?
Is the first Next Generation Open Source Firewall and is available in Portuguese, English and Spanish.
I’m using pfSense. It’s Works perfectly. Thank you for sharing this firewall guide.
ClearOS, way to go 😀
It came last 🙂
Obsolete since 2022, not even a true firewall. Sure you can do better.
Why would *I* need to do better?
Probably a comment meant for Sayan’s message about pfSense, just above.
Or for Andre, honestly it’s hard to tell.
They all **** me off — local operations are quite delayed if the WAN is down.
Sounds like that’s your problem buddy.