A Firewall is an essential tool for protecting a computer network from threats by filtering inbound and outbound traffic. Many open-source firewalls exist for this purpose. However, an Open-Source Firewall doesn’t necessarily mean it is entirely free.
Instead, it is distributed under a license that allows the user to access the source code. Users can use this source code to develop their Firewalls or even use pre-developed ones.
Whatever the theory is, an open-source firewall will save you money when you buy a paid variant. There are lots of such firewalls available to download from the internet.
However, Linux users may find it challenging to find one, as many Linux-based Firewalls have discontinued their services. To help you, we have listed the best open-source Firewalls for Linux users. If you are a Windows user, Look at the best Windows Firewalls.
List of Best Open-Source Linux Firewalls in 2025
1. Firewalld
This is a default Firewall management tool for RHEL, CanvO S, SUSE, and OpenSUSE. Firewalld is a popular firewall among Linux users. It has dynamic support for networks and a straightforward interface.
The main features of Firewalld include D-Bus API, IPV4, IPV6, bridge, and IPset support. Moreover, it allows users to configure its settings using the firewall end terminal.
2. UFW
If you are a new user of a Linux-based firewall, the UEF will be the perfect option for you. The main features of UFW include IPv6 support, status monitoring, etc. Additionally, it allows its user to add, remove, or alter Firewall rules.
UFW also includes GUI and GUFW for Ubuntu and Debian users.
3. Iptables
Iptables is the most famous name in the Firewall domain. It is a firewall that enables you to rearrange rulesets. Most advanced Linux admins trust this terminal-based Firewall for its efficiency and customization, but that doesn’t mean novice users cannot use it.
Iptables’ unique features include a packet filter ruleset, implementation and inspection of a packet header for fast output, an editable ruleset, and data backup and restoration.
4. pfSense
It is one of the most trusted open-source Firewalls based on the FreeBSD custom kernel. pfSense features high-level packet filtering that provides complete network security.
However, the most exciting aspect of the firewall is that it is available in many formats, from hardware devices to downloadable editions.
pfSense offers several advanced features, including load-balancing for inbound and outbound traffic, compatibility with DNS and DHCP servers, and more. In addition to its free version, pfSense has a premium commercial version.
5. IpCop Firewall
Another firewall that allows flexibility and scalability in the firewall ruleset is the IpCop Firewall. It is almost identical to Iptables and can be used interchangeably, but the features in IpCop Firewall are much more advanced than Iptables.
The advanced features of this Firewall include a network-specific virtual machine, enhanced performance through maps and connotations, etc. IpCop Firewall Also features a unified and consistent Syntax to support the protocol.
6. Endian
Endian is a high-security firewall for complete network protection and packet inspection. Its developers claim that the Firewall can convert a simple machine into robust security, spam alerts, etc.
As a result, users have also ensured network security, sent spam alerts, and provided web security through a URL blocklist.
Some of Endian’s best-in-class features include real-time network monitoring, bidirectional network security, spam alerts, and more.
7. IPFire
If you are looking for an easy-to-use firewall for small office or personal use, IPFire is a good option. The Firewall includes content filtering, multi-deployment facilitation, and a built-in intrusion detection system. Additionally, you can use it as a VPN gateway or proxy server.
Many Linux users trust the Firewall for its accessible and dynamic settings. Thus, IPFire is a perfect companion for providing network security.
8. OPNSense
It is another easy-to-use and easy-to-build Linux Firewall based on Hardened BSD. OPNSense offers most of the premium security features free of charge. Moreover, the Firewall receives weekly updates to ensure no deficiencies or loopholes are left behind.
Along with the general features, some additional features of offense include forward caching proxy, traffic shaping, intrusion detection, and VPN. The robust build and various features make it one of the most desirable firewalls for Linux users.
9. Untangle Firewall
Untangle is an open-source Firewall based on Debian 8.4. It provides all the functions through a well-managed web-based user interface. You get essential network functions for free. Untangle was initially named NG Firewall and is trusted by advanced Linux admins.
Untangle Firewall also features Spam, Phishing, viruses, Intrusion prevention, and ad blocking. It can be easily installed on any hardware or virtual machine or bought on a device with an NG Firewall preinstalled.
10. Shorewall – Iptables Made Easy
Another popular and well-known free and open-source Linux firewall option is Shorewall or Shoreline. An iptables/ipchains Netfilter system integrated into the Linux kernel provides this firewall protection. IPV6 is also supported.
Shorewall is an alternative to Iptables if you have trouble establishing rules or using the Firewall. It can run various gateway, router, and firewall applications.
11. Vuurmuur
With a clear and consistent interface, Vuurmuur surely deserves your attention when you’re looking for a firewall for Linux. Its highly configurable, stable, and secure firewall system allows you to manage everything seamlessly.
Installing and setting up could be a bit tricky, although it has easy configuration options, too. However, it supports traffic shaping and IPV6. Furthermore, it has many advanced features to monitor logs, connections, and bandwidth usage.
12. ClearOS
There is a lot to like about ClearOS; its firewall option is one of the best. The CentOS-based ClearOS distro can be used as a firewall and content filter. Moreover, it has an excellent ability to detect intrusion.
As its name suggests, ClearOS has a clean user interface. Thus, it is easy to install and use. It also offers options for setting up several networks. Overall, it’s a super easy distro that can be a firewall option for Linux.
Hopefully, you now have a better understanding of the significance of maintaining network security. With this Linux firewall, you can ensure your network will not be hacked. I hope this Linux firewall software list will help you get the best one.
