The quest for the best open-source firewall takes centre stage in the ever-evolving cybersecurity landscape. Regarding firewalls, the choice between open-source and proprietary solutions does matter. Where cyber threats loom larger than ever, safeguarding your network against malicious intrusions is paramount. Open-source firewalls have captured attention for their transparency, cost-efficiency, and flexibility. But what truly makes the best open-source firewall stand out from the rest? This article will explore the world of open-source firewall solutions, uncovering the attributes that define the champions of network security.

What Is a Good Free Firewall?

An open-source firewall is a network security system built upon open-source software that monitors and controls network traffic. It is a network security solution that integrates the principles of open-source software with firewall functionality. It offers transparency, customisability, cost-efficiency, community support, and high control over network security policies. It is a compelling option for many organisations and individuals seeking robust network protection.

There are several good free firewall options available for personal use. The availability and quality of software can change over time, so we recommend checking the latest reviews and recommendations to ensure you’re using a firewall that meets your current needs.

Research and choose a firewall that best fits your requirements and operating system. A firewall’s effectiveness depends on the software, how well you configure it, and your overall security practices.

Which Is the Best Open-Source Firewall?

Open-Source Firewall

The “best” open-source firewall can vary depending on your needs and preferences, level of technical expertise, the size and complexity of the network, and your specific use case. Here are some notable open-source firewall options, each with its strengths:


pfSense is a highly regarded open-source firewall and router distribution based on FreeBSD. It is known for its flexibility, robust feature set, and user-friendly web interface. pfSense is suitable for both home users and small to medium-sized businesses. It offers features like VPN support, traffic shaping, intrusion detection, and more.


IPFire is another open-source firewall solution based on Linux. It focuses on security and ease of use and is designed for home and small businesses. IPFire includes proxy server capabilities, VPN support, intrusion detection, and content filtering.


OPNsense is a fork of pfSense and offers a similar feature set. It has gained popularity for its modern and user-friendly interface. OPNsense emphasises security, privacy, and ease of use. It includes firewall rule management, VPN support, and intrusion detection.

FirewallD (for Linux)

FirewallD is a dynamic firewall management tool for Linux systems, commonly used on distributions like CentOS, Fedora, and Red Hat Enterprise Linux (RHEL). It simplifies the management of firewall rules and supports both IPv4 and IPv6.

Shorewall (for Linux)

Shorewall is a high-level tool for configuring the Netfilter firewall on Linux systems. It uses configuration files to define firewall rules, making it suitable for more experienced users who prefer text-based configuration.

Smoothwall Express

Smoothwall Express is an open-source firewall and network security distribution based on Linux. It is designed for use in small and medium-sized networks. It provides web content filtering, VPN support, and intrusion detection.

Untangle NG Firewall

Untangle offers both open-source and paid versions of its NG Firewall. The open-source version provides essential firewall and network security features. In contrast, the paid versions offer advanced features like web filtering, application control, and more.

The open-source landscape evolves, so checking the latest reviews and documentation is always good practice.

Why Do You Need an Open-Source Firewall?

An open-source firewall can provide several advantages and may be the right choice for certain individuals, organisations, or scenarios. Here are some reasons why you might consider using an open-source firewall:

  1. Transparency and Trust: Open-source software allows you to inspect the source code, which means you can see how the firewall works and whether it contains any vulnerabilities or backdoors. This transparency can build trust in the security of the firewall.
  2. Customisation: Open-source firewalls are highly customisable. You can modify their configurations, add or remove features, and tailor them to your security requirements and network environment.
  3. Cost-Effective: Open-source firewalls are often cost-effective because you don’t have to pay licensing fees; this can be particularly beneficial for small businesses, educational institutions, or individuals with limited budgets.
  4. Community Support: Many open-source projects have active and supportive communities. You can access forums, wikis, and user groups to seek help, share experiences, and solve common issues.
  5. Flexibility: Open-source firewalls can run on various hardware, from dedicated appliances to repurposed older computers. This flexibility lets you choose the hardware that fits your needs and budget.
  6. Security Updates: Open-source projects often have a strong commitment to security. Updates and patches are typically released when vulnerabilities are discovered.
  7. No Vendor Lock-In: With proprietary firewalls, you are often locked into a particular vendor’s ecosystem. Open-source solutions provide more freedom to switch between vendors or adapt to changing needs without constraints.
  8. Education and Learning: Using open-source software can be a valuable learning experience for IT professionals and students. It allows them to gain hands-on experience with network security, firewall administration, and system management.
  9. Compliance Requirements: In some cases, open-source firewalls can be tailored to meet specific regulatory compliance requirements, such as those mandated by HIPAA, PCI DSS, or GDPR.
  10. Longevity: Open-source projects can have longer lifespans because they depend on a single company’s continued support. An open-source community may continue developing even if a commercial firewall vendor discontinues a product.

Open-source firewalls also have potential drawbacks, requiring more technical expertise to set up and configure than commercial solutions. The level of support may vary depending on the project and community involvement. The decision to use an open-source firewall should be based on your specific needs, technical capabilities, and the level of control and transparency you desire in your network security solution.

Why Is Free Open-Source Firewall Different From Another Types Of Firewalls?

Free, open-source firewalls differ from other types of firewalls, particularly in licensing, cost, source code availability, and customisability. Here are some key differences:

Free Open-Source FirewallsCommercial Firewalls
Licensing and CostOpen-source firewalls are typically distributed under open-source licenses (e.g., GNU General Public License).Commercial firewalls require the payment of licensing fees. Commercial firewalls often come with additional support and maintenance packages that may raise ongoing costs.
Source Code AvailabilityThe source code of open-source firewalls is openly available to the public. Users can review, modify, and contribute to the codebase, enhancing transparency and allowing for community-driven development.The source code of commercial firewalls is typically unavailable to customers. Vendors retain control over the code and may not provide transparency regarding their software’s inner workings.
CustomisabilityOpen-source firewalls are highly customisable. Users can adapt the firewall’s configurations, add or remove features, and integrate it with other open-source or proprietary tools. This flexibility makes open-source firewalls suitable for a wide range of network environments.Commercial firewalls may offer some level of customisation, but the extent and flexibility of customisation options can be limited compared to open-source alternatives. Vendors often provide pre-configured solutions designed to meet common use cases.
Community SupportOpen-source projects often have active and supportive communities. Users can seek help, share experiences, and find solutions to common issues through forums, mailing lists, wikis, and user groups.Commercial firewall vendors typically offer customer support as part of their service packages. While this support can be robust, it may require additional costs and is subject to the vendor’s terms and response times.
Vendor Lock-InOpen-source firewalls provide vendor independence. Users are not locked into a specific vendor’s ecosystem, allowing greater flexibility in choosing hardware and software components.Proprietary firewall solutions may lock users into a vendor’s proprietary ecosystem. Switching to a different vendor or platform can be more challenging and costly.

The choice between free open-source and commercial firewalls depends on an organisation’s specific requirements, budget, level of technical expertise, and preferences. Both types of firewalls have their strengths and weaknesses, and the decision should align with an organisation’s network security goals and resources.

These dynamic defenders of digital domains, characterised by transparency, customisation, cost-effectiveness, and vibrant community support, have proven their mettle in diverse network environments. While the ideal choice may vary based on specific needs and expertise, one thing is clear: open-source firewalls offer a powerful arsenal to protect networks, empowering you with the tools and knowledge needed to guard against cyber threats. In network security, the best open-source firewall stands as a beacon of trust, adaptability, and resilience, ready to shield your digital assets in an interconnected world.