Top Ten Best Open Source Firewalls in 2023


By Jack Lin

Update on

Best Open Source Firewalls

This article will go through some of the best open-source firewalls available in the market.

The software included in the list covers a wide range of security, all the while providing the user comfort and reliability.

While there is a bridge that you can find between the expensive firewalls and the free-to-use ones, they share some of the core functions of a firewall.

Before we get into the list of best open-source firewalls that you should use, keep your network system safe.

First, we have to understand what a firewall is. And how is it going to help you keep your computer network safe?

What Is a Firewall?

Firewalls have become common inside the system, whether you are running a single desktop computer as your workstation or ten of them connected to the host server.

The firewall works as a layer between all the computers connected to a single router, LAN port, or even the internet.

The best open-source firewall makes sure every transaction of data or traffic from the internet that goes through the port is well analyzed before going to the destination address.

A firewall is a figurative wall that protects the computer from receiving harmful software from getting inside.

With that done, you are now ready to have a list of some of the best open-source firewalls in the market that you can get.

Besides, if you wish to know the function of a firewall, here you are.

Which Is the Best Open Source Firewall? – Top 10

1. pfSense

Best Open Source Firewalls - pfSense

Is pfSense firewall free?

pfSense is one of the most popularly used firewall systems by many users. The reason is to provide users with all the functions necessary in the firewall and for being free.

Is pfSense the best firewall?

Absolutely Yes! PfSenseTop is the number 1 Best Open Source Firewall. The program itself was released back in 2004 and still holds the market to this day. This open-source firewall is easy to use for beginners in networking or professional, experienced workers.

pfSense can be installed on a local machine or a virtual machine. Users will be in charge of every function in the firewall; pfSense comes with easier to navigate web-based interface.

Setting up pfSense is easy and simple. That is one of the reasons why there are so many active users of pf Sense. The devs pay attention to the software, as the software receives plenty of new updates to make things run smoothly.

Here is the List of Functions pfSense is Capable of Handling.

  • Routing and Firewall
  • VPN from one website to another
  • Blocking of the IP address
  • Load Maintenance
  • Proxy Settings
  • OpenVPN

2. OPNSense

Best Open Source Firewalls Opnsense

Here is another addition to the free-to-use best open-source firewall software. It is one of the beginner-friendly software on the list.

The user interface of this Best Open Source Firewall software is top-notch, with all the most used settings on the page, as the user interface looks simple and well-categorized.

Normally, the developer would fill the entire page with thousands of functions to show up the potential of the software, but that just shows how terrible the design quality is for the software.

But here, with OPNSense here, you will get a more streamlined user interface. Being beginner-friendly doesn’t make this software application for more advanced professional users.

This software has almost everything that you would expect out of paid software. Some of the function is meant for beginners, but some functions are intended for professionals.

Here are some of the functions you will receive with OPNSense:

  • Setting up the network
  • Monitoring any advancement in the network
  • WAN Load balance
  • VPN Routing
  • Stateful Firewall
  • HTTP load balancer
  • Build-in reporting
  • Up to Data Analysis

These functions help the user keep track of every little network activity. This can be vital for any business.

They have a large community with many active members helping out the newcomers.

PS: If you are wondering about the WSUS server, just read more here.

3. UnTangle

Best Open Source Firewalls - UpTangle

The untangle firewall takes the next step to network security, as they provide a more advanced version.

The Best Open Source Firewall software can be installed on a server, but it has to meet the requirement to use untangle to its full potential.

As I said, the app can be installed on a server, virtual machine, and the cloud. The software is free to download on your preferable format, iso image, USB image, or OVA–virtual machine.

Untangle also provides that software in a standalone hardware package. If you don’t want to deal with the initial stage of setting up the firewall, you can just skip all the hassle by picking the hardware version, which comes with the software package pre-installed.

4. ClearOS

Best Open Source Firewalls - ClearOS

ClearOS is a firewall based on the operating system Linux; that is why this firewall is designed to install only on Linux servers.

The firewall carries all the functions that you would expect from a normal firewall:

  • Monitors
  • Control access to Local services
  • Control the access to applications of the machine

But the clear design of this Best Open Source Firewall is designed to serve only the servers, but clears can also work as network firewalls as well.

The user interface looks friendly, as all of the functions in the software are well categorized into tabs. The firewall software is easier to install, and it follows the web-based interface.

If you want your firewall to handle more complex rules, a custom firewall tool lets the user add more complex rules, such as IPTABLES, to the machine.

If you think this piece of software is too beginner’s friendly, then there is an advanced version of the firewall, which means the server is the advanced user of the software.

It makes clearOs the best open source firewall for both beginners and professionals.

5. IPFire

Best Open Source Firewalls - IPFire

Here comes another Linux-based Best Open Source Firewall that provides network security.

It does all the basic functions that you would expect from a normal firewall. It protects the network from attacks from the internet and DoS attacks.

The best thing about IPFire is the services you will receive after downloading it. The software is backed by an active community with thousands of members and developers.

They always work hard to find new ways to improve the system for better functionality.

IPFire uses an intrusion detection system to evaluate the network’s traffic through the internet if the traffic matches all the things expected from an attack, that particular traffic gets blocked.

As you would expect from the firewall, this one also features a web-based UI for better user interaction with the software.

If you want to make some rules, you are allowed to do it. You can make the software work your way, not the other way around.

Here Are Some of the Functions It Can Perform:

  • Web Proxy
  • IDS
  • Proxy and Relay for various protocols
  • Backup server, NFS, Samba, Mail Server
  • VPN termination
  • QoS
  • Wireless Access Point
  • Tor node

When picking the best open-source firewall, you can’t go wrong with IPFire.

6. IPCop


IPCop is designed on a Linux-based operating system, which helps secure the network of the company and home.

One of the things that can be a little off-putting about this piece of software is the interface you have to deal with.

In short, there is no interface (GUI); you have to input command lines to make things possible with this software.

While it may require the user to have some coding knowledge to run it on their system, this firewall’s service is designed for advanced users.

The Best Open Source Firewall size is just 60 megabytes; if you want to download the software, you can still download it.

Its developers no longer support the software, but if you want to test it out, you can just visit their website. All these functions make this one of the best open-source firewalls.

7. Shorewall


Shorewall is another free Linux Best Open Source Firewall with a long line of features and functions for the users.

This software can only be installed on servers or routers; if you are planning to use your virtual machine or cloud-based service, then you won’t be able to do that.

As the firewall service will let the user have an Iptables configuration tool, and the software has enough power to turn the server into hardware firewall machinery.

8. Uncomplicated Firewall

An uncomplicated firewall is one of the most used firewall software by many users worldwide. It is because of the features that it comes with.

But the user has to navigate with codes with this Best Open Source Firewall, which can be a problem for most people.

It depends on the user configuration of how they want their firewall to run in their system. You can manage your Linux Kernel Packet filtering system with this software.

9. Smoothwall


Is Smoothwall open source?

Smoothwall is the best open-source firewall that was released back in 2000. This software comes with its very own Linux-based operating system.

For display, it has a web-based interface for the navigation of various functions. The operating system in this software is tough to withstand any software vulnerabilities on the firewall. It comes with,

  • Lan
  • DMZ
  • Firewalling Internal/ External
  • Web Proxy
  • Records of traffic

Is Smoothwall free?

Yes, it’s free. The Smoothwall community has over 17,000 members supporting the software and improving it.

10. CSF Configserver Security

CSF Configserver security

CSF is a stateful firewall, which means it will record everything about the connection for evaluation.

Such as the address of the IP, the destination of the address, port number, login detection, and many more to the Linux servers. One of the best things about CSF is the compatibility of the software. It can run on

RHEL/CentOS, Cloud Linux, Fedora, OpenSUSE, Debian, Ubuntu, Slackware, OpenVZ, KVM, VirtualBox, Xen, VMware, Virtuozzo, UML, and many more.

With that range of compatibility, you can run this Best Open Source Firewall on almost anything.

Factors to Consider When Choosing a Firewall

When selecting a firewall for your network, several factors should be taken into account:

  1. Security Requirements: Assess your specific security needs and choose a firewall that aligns with your requirements.
  2. Scalability: Consider the future growth of your network and ensure the firewall can accommodate increasing traffic and users.
  3. Usability: Evaluate the user interface and management capabilities of the firewall to ensure it fits your operational needs.
  4. Community and Support: Check the availability of community forums and support channels for troubleshooting and updates.
  5. Integration: Determine if the firewall integrates with your existing network infrastructure and other security tools.


Q1. Are open source firewalls as secure as commercial firewalls? Open source firewalls can provide a high level of security if properly configured and maintained. The active communities and frequent updates contribute to their robustness.

Q2. Can open source firewalls handle large networks? Yes, open source firewalls like pfSense and OPNsense are capable of handling large networks. However, proper hardware sizing and configuration are essential for optimal performance.

Q3. Do open source firewalls offer support and documentation? Yes, most open source firewall projects have active communities, forums, and extensive documentation that can assist users in deploying and managing their firewalls effectively.

Q4. Can I use open source firewalls for home networks? Absolutely! Open source firewalls are suitable for both small and large networks, including home networks. They provide a cost-effective and reliable option for enhancing network security.

Q5. Can open source firewalls be integrated with other security tools? Yes, open source firewalls can be integrated with various security tools and technologies, allowing you to create a comprehensive security ecosystem for your network.


Now you know some of the best open-source firewalls available in the market.

Seeing the list will make you wonder why there is so much firewall software in the market because the threat is too high in the climate that we live in today.

Each connection carries a lot of valuable information; if not evaluated, this information or the connection that carries the information can get attacked.

A stronger firewall provides an efficient solution to prevent such things from occurring.

That’s why you see so much firewall software in the market, with the active community making the software even stronger to prevent more harmful things on the internet.

Choose one of the best open-source firewalls that best suit you and your system.


10 years of experience in information and computer technology. Passionate about electronic devices, smartphones, computers, and modern technology.