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With digital threats constantly evolving and becoming more sophisticated, the need for robust cybersecurity measures has never been more critical. 

One essential component of any cybersecurity strategy is a reliable firewall. Firewalls act as a barrier between your network and cyber threats, filtering and monitoring data to ensure only authorised users can gain access to your network, systems and assets.

The only problem is the price tag. Your average firewall can set you back between $1,500 and $15,000 for the product cost, installation fee, and subscription, and many organisations need more than one firewall to keep themselves secure. 

For those looking to protect themselves without breaking the bank, opting for an open-source firewall can provide a great balance between security, price and customisation. 

What are open-source firewalls?

Open-source firewalls are firewalls that are distributed under an open-source license. This means that the source code is freely available for anyone to modify and distribute, making the firewall a more affordable option than its commercial counterpart.

Open-source firewalls are a popular choice for businesses and organizations that need a cost-effective firewall solution. But they’re not just cheap.

They also provide transparency and extensive customisation as their source code is open and accessible to the public. This allows security experts and the community to review the code, identify vulnerabilities, and propose improvements, enhancing the overall security of the firewall.

Open-source firewalls vs commercial firewalls

Open-source firewalls and commercial firewalls both have their own pros and cons that you’ll need to consider when choosing a firewall for your business.

While open-source firewalls save you a significant amount of money, they may require more expertise to install and manage than commercial firewalls. Their commercial counterparts tend to have more features too, such as such as intrusion prevention systems (IPS) or web filtering.

Here are some of the other pros and cons of choosing an open-source firewall over a commercial one:

Pros of open-source firewalls

  • Free to use. Open-source firewalls are free to download and use, which can save you a significant amount of money.
  • Customisable. The source code of open-source firewalls can be modified to meet the specific needs of your network. This can be helpful for organizations that have unique security requirements.
  • Transparent. Open-source firewalls are subject to public scrutiny. This can help to ensure that the software is secure and bug-free.

Cons of open-source firewalls

  • May require more expertise to install and manage. Open-source firewalls may require more expertise to install and manage than commercial firewalls. This is because there may not be as much documentation or support available for open-source firewalls.
  • May not have all the features of commercial firewalls. Open-source firewalls may not have all the features of commercial firewalls, such as intrusion prevention systems (IPS) or web filtering.

The best type of firewall for your business will depend on your specific needs and budget. If you are looking for a cost-effective and customizable firewall solution, an open-source firewall may be a good option. If you need a firewall with a lot of features and vendor support, a commercial firewall may be a better choice.

Choosing an open-source firewall

Choosing an open-source firewall for your network can be a daunting task, as there are numerous options available, each with its own strengths and weaknesses. 

To make the best decision for your specific needs, it's important to consider several factors:

  • Network Size and Complexity. Assess the size and complexity of your network. If you have a small, straightforward network, a lightweight firewall like Shorewall or IPFire might suffice. For larger, more complex networks, consider pfSense or OPNsense, which offer more robust features and scalability.
  • Features and Functionality. Determine the specific features you require from your firewall. Do you need intrusion prevention, web filtering, application-level filtering, or other advanced security features? Compare the available features of different open-source firewalls to find the one that best matches your needs.
  • Ease of Use and Management. Consider your technical expertise and the resources available for managing the firewall. Some open-source firewalls, like pfSense, have web-based interfaces that make configuration and management easier. Others, like Shorewall, require more command-line knowledge.
  • Community and Support. Open-source firewalls often rely on community support and documentation. Check the online forums, wikis, and documentation for the firewalls you're considering to assess the level of support available.
  • Security and Updates. Open-source firewalls are generally considered secure due to their transparent nature and public scrutiny. However, it's crucial to ensure the firewall is actively maintained and receives regular security updates.

Best open-source firewalls

There are a variety of different open-source firewalls on the market, each with its own benefits, limitations,and unique set of features. 

In this article, we’re counting ten of the best open-source firewalls available today, exploring the capabilities, features customisation options that make them so popular.

Untangle NG 

Untangle NG is an open-source firewall and gateway security platform that helps keep networks safe while accessing the internet. It provides a free core firewall platform with paid add-ons and a cloud-based management platform with a variety of deployment options for smaller teams. You can install the firewall on a dedicated appliance, a server, a virtual machine, or even in the public cloud, and use it to keep your entire company safe. It also has a range of flexible deployment options, including third-party hardware, as a virtual machine, or as a turnkey appliance. 

The Untangle NG cloud-based management console for remote management can either be deployed on-premises or as SaaS, and virtualized or cloud-based. Because Untangle Firewall software is available as a free download in multiple formats, it can suit all kinds of deployment needs. You can download a USB image, ISO image, or VMware image, and the company offers the same software package as standalone hardware, which you can connect to your existing network.

Shorewall

A Linux-based open-source and new-generation firewall solution, Shorewall is an open-source firewalling tool that not only makes the task of network security easier but also allows for much easier handling of zones. It has a range of features ready to use out of the box, including a Netfilter system for tracking and monitoring potential threats. Say, for example, you want to create a private internal network that can only be accessed by specific machines, a guest network that can be accessed by anyone or a network that can be accessed from machines outside your. With Shorewall, all of this is easy. 

The Shorewall tool allows for network partitioning and role-based access management. There’s support for multiple systems, a high number of network interfaces, and complete customization for modifying the firewall according to your requirements Blacklisting is also available for IPs, and companies can access features for mapping and traffic accounting, with tools for ease of virtualisation also built-in. The latest version of Shorewall was released in 2020.

IPCop Firewall

Another Linux-based solution for open-source firewall protection, IPCop is a well-known solution for online security designed to help secure businesses and home networks alike. The platform’s sole purpose is to protect the networks it is installed on, implementing existing technology, outstanding new technology and secure programming practices IPCop to help those wanting to keep their computer networks safe do so. 

Though IPCop does demand some technical knowledge of firewalls and servers, it also provides a lightweight opportunity to enhance security for more advanced users. The image size is tiny at 60MB, and it’s suitable for a range of systems. Unfortunately, the last version of this product was released in 2019, but it’s still a great choice if you’re looking for heavily customisable firewall protection. 

Endian 

The Endian Firewall Community, or EFW, is a powerful, open-source UTM and Firewall solution offering a unique combination of capabilities and features to help you keep your network secure. It can transform a bare-metal hardware appliance into a powerful and effective threat prevention and management solution comprising of a firewall, an antivirus, VPN, and content filtering capabilities all in a single solution. The software is available to access for free, but you’ll need to handle it yourself, as there’s no support available from the developers. 

With Endian,, you can quickly establish web and email security with powerful analytics When you download EFW, you don’t just get a turnkey Linux firewall solution – you also get unified threat management and an open-source anti-virus protection system. You can even unlock extra support in the form of powerful VPN services.

Smoothwall

Available on its own or as part of a package, Smoothwall’s open-source firewall provides 7 layers of application control. The Smoothwall firewall combined with the Smoothwall filter offers companies a complete package for online protection. Alternatively, you can access the firewall on its own for bandwidth management, gateway anti-malware protection, and a real-time dynamic threat filter.

Focused on the UK education environment, the Smoothwall firewall is one of the most exciting tools on the market, with thousands of forum members contributing to the Linux and GNU-based solution at all times. The OS is even security-hardened to reduce the risk of firewall vulnerabilities for users. For those in need of extra help, UK support is available.

VyOS

The VyOS Open-source firewall network operates on the GNU/Linux environment, with a unified management interface for all functions. The solution comes with access to a free routing platform that competes directly with other commercially available solutions from leading network partners. The VyOS solution also runs on standard systems, so it’s suitable for use as a router and firewall platform for all kinds of cloud deployments. 

With VyOS, companies can access a comprehensive firewall system with access to industry routing protocols, multi-path and policy-based routing, and more. You can even set up the OS system on your specific VPN solutions for remote workers.

OPNSense

The OPNSense firewall is easy to use, free, and ideal for infinite scalability. This open-source project promises best-in-class virtual private networking, intrusion detection, and a powerful firewall with support for both IPv6 and IPv4 live views on passed and blocked traffic. Multi-WAN capability is included with hardware failover, state synchronization, and intrusion detection. 

Two-factor authentication is available throughout the system, both for the user and for services like VPN. Multi-language support is available for all kinds of customers, along with an intuitive user interface for easy access and development.

Ufw 

Otherwise known as an uncomplicated firewall, Ufx is a powerful program designed to make managing a netfilter firewall as easy as possible, The program provides a framework for managing netfilter, as well as a command-line interface for manipulating the firewall, to make navigating the complexity of firewall installation a breeze. Its easy-to-use interface is specially designed for people unfamiliar with firewall concepts, simplifying complicated iptables commands to help an administrator manage the complexity of setting up their firewall.

Ufw uses a command-line interface consisting of a small number of simple commands and uses iptables for configuration so that anyone can set up a netfilter firewall – no matter their skill level. It’s also the default configuration tool for UBunto and is developed to ease iptables firewall configuration and provide a user-friendly way to create an IPv4 or IPv6 host-based firewall. 

IPFire

A Linux-based firewall intended to offer advanced network security for businesses, IPFire provides extensive protection from attacks through DDoS and internet connections. The software comes from a dedicated online community featuring thousands of developers. Aside from being powerful, IPFire’s software is also lightweight and easy to implement. You even get access to an Intrusion Detection System for analysing your network traffic and pinpointing potential exploits.

If attacks are detected within IPFire, you’ll be able to set the system up to automatically block the attacker. Like many leading firewalls, IPFire comes with a web-based management interface for setting changes. You can also configure the network to suit different needs, like advanced graphical and logging reports.

PfSense

Widely regarded as the world’s most trustworthy open-source firewall, PfSense is a free-to-use solution for securing your business. Thousands of enterprises rely on this software to securely connect to the cloud and keep business data under wraps. The PfSense environment builds on the concept of stateful packet filtering, with a wide range of features you would generally only find in other, more expensive firewalls. 

With PfSense, companies can access a comprehensive network of security solutions for all kinds of environments. The platforms this company uses are among the most reliable in the world, engineered to deliver the best level of confidence, security, stability, and performance. PfSense also offers plenty of support in the form of a documentation tool, helping you navigate the complexities of installing your firewall.