An open-source firewall is a network security solution designed to monitor and control traffic based on predefined rules.
It provides transparency, flexibility, and cost-effectiveness by granting users access to its source code, enabling them to modify and customize it to meet specific requirements. Open-source firewalls operate through several key mechanisms.
They monitor traffic by analyzing incoming and outgoing data, applying security rules to allow or block packets.
Through packet filtering, they inspect data at various layers of the OSI model to ensure compliance with security policies.
Network Address Translation (NAT) modifies IP addresses in packets, facilitating secure communication between internal and external networks.
Many open-source firewalls also integrate Intrusion Detection/Prevention Systems (IDS/IPS) to identify and mitigate threats in real time.
Users can manage rules for specific protocols, IP ranges, or ports to control traffic flow effectively. Additionally, these firewalls log activities, providing detailed insights into network traffic and potential security incidents.
Open-source firewalls offer several key features that make them advantageous. They ensure transparency by allowing users to inspect the source code for hidden vulnerabilities.
Their customizability enables organizations to tailor the firewall to their unique needs. Being free of licensing fees, they are cost-effective solutions for enterprises.
Advanced security features such as stateful inspection, deep packet inspection (DPI), VPN support, and web filtering provide robust protection against threats.
Lastly, active community support ensures regular updates, plugins, and troubleshooting assistance, enhancing their reliability and functionality.
What is Open Source Firewall?
What are the benefits of open source firewall?
10 Best Open Source Firewalls 2025
Open Source Firewall Features
1. PfSense
2. Untangle Firewall
3. OPNsense Firewall
4. Endian
5. IPFire
6. IPCop Firewall
7. Perimeter 81
8. Shorewall
9. SmoothWall
10. ClearOS
Conclusion
The Open Source Firewall belongs to the community; hence, its development and updates depend mainly on the community.However, this also increases confidence in the continuity of the program.
Hence, in this post, we will show you the 10 best open-source firewalls to protect your infrastructure.Just after the arrival of Windows XP Service Pack 1, Windows, by default, offered all its users a very basic and simple firewall.
Generally, with this Windows firewall, we can control the use of our internet connection tools and apps. Not only that even, but it also protects us from all the possible computer attacks that may arrive through the network.
With the arrival of the Windows 10 Creators Update and the excellent operation of Windows Defender and its firewall, this basic security software has gained great importance and has made more and more users trust it.
But, the fact is that this system couldn’t offer you the whole thing and features that you are finding to secure your infrastructure.
Generally, open-source software offers an economical and adjustable option to deploy basic networking for the infrastructure and home.
Not only that even, but the open-source products also provide us with simple routing and networking functions like DCHP and DNS.
Open-source firewalls are usually free, eliminating the need for expensive licenses or subscriptions. The source code is publicly available, enabling users to audit it for vulnerabilities or backdoors.
Users can modify and adapt the software to meet specific network security needs. Backed by active developer communities offering assistance, updates, and documentation.
Regular security patches and feature updates ensure the firewall stays up-to-date. Provides full freedom to switch tools or platforms without being tied to a specific vendor.
“Security through transparency” ensures vulnerabilities are quickly identified and fixed. Suitable for small home networks, large enterprises, or anything in between.
Works seamlessly with other open-source tools like VPNs and intrusion detection systems. Offers opportunities for IT professionals to grow their knowledge and expertise in network security.
Open source firewalls offer numerous benefits, making them a compelling choice for organizations and individuals seeking cost-effective and customizable network security solutions. Here are the key advantages:
These benefits make open source firewalls an excellent choice for organizations seeking affordable, transparent, and adaptable network security solutions. However, they may require technical expertise for installation and management, which could be a consideration for less experienced users.
| Open Source Firewall | Key Features |
|---|---|
| 1. PfSense | 1. Spam Blocker Lite 2. Phishing blocker 3. Virus blocker 4. OpenVPN 5. Blocking a country |
| 2. Untangle Firewall | 1. Forward Proxy Caching 2. Capital portal 3 Traffic Shaper 4. Virtual Private Network 5. Help with wireless networks |
| 3. OPNsense Firewall | 1. Email security 2. Multi-WAN 3. Intrusion Prevention 4. Quality of service 5. How to Forward Ports |
| 4. Endian | 1. interfaces with typical behavior 2. VLAN available 3. Indirect installation to a flash device 4. Web interface 5. Add-ons and extensions that are flexible |
| 5. IPFire | 1. Time server 2. DHCP server 3. Dynamic DNS 4. Catching name server 5. Help for OpenVPN and IPsec |
| 6. IPCop Firewall | 1. Great interface 2. Multiple interfaces per zone 3. Multiple zones per interface permitted 4. Different rules for proper access 5. Setting up a stateless firewall |
| 7. Perimeter 81 | 1. Secure remote access 2. Cloud agnostic integration 3. Easy to configure & maintain 4. Granular user segmentation 5. Checks for Endpoint Compliance |
| 8. Shorewall | 1. Great interface 2. Multiple interfaces per zone 3. Multiple zones per interface permitted 4. Different rules for proper access 5. Setting up a stateless firewall |
| 9. SmoothWall | 1. Outbound Filtering 2. Modified time and Accessed time 3. Simple to use and offers a great quality of service 4. UPnP support 5. Gateway for the Application Layer |
| 10. ClearOS | 1. Help with files and prints 2. Managing users and groups 3. List of Servers 4. Intrusion detection and prevention system 5. Market for Applications |
All these products can be easily downloaded and deployed on any hardware, on a virtual platform, or in the cloud as well.
However, many also sell them with pre-configured appliances if you like their functions or support and don’t want to build your own machine.
Here in this article, we have mentioned the best open-source firewalls for infrastructure and homes.
However, apart from all these things, we found pfSense and Untangle are some of the best firewalls that could be used in various environments.
The pfSense open source firewall is quite similar to Untangle, although it doesn’t have as many bells and whistles as Untangle does, such as web filtering and antivirus.
With the CD image (.iso), USB image (.usb), or Embedded image (.img) of pfSense, you can install it on your own hardware or virtual machines; it is based on FreeBSD with a modified kernel.
In addition, you can purchase hardware with pfSense already installed on it. To clarify, a yearly membership to access all of the features and support is available for $99.
In addition, you can get a digital book on pfSense, automatic backups, and a video collection with the most relevant developer tutorials.
Key features
| What is Good? | What Could Be Better? |
|---|---|
| Open-Source and Free | Complexity for Small Deployments |
| Customizable and Extensible | Hardware Requirements |
| Comprehensive Security Features | |
| High Performance and Stability |
Untangle Open Source Firewall is based on Debian 8.4 and is quite similar to ClearOS. The core features of the network are supplied, and users can access both free and paid applications to expand its capabilities.
Technically known as NG Firewall, this firewall system may be readily installed on any physical or virtual machine, or you can purchase a device with NG Firewall preconfigured, as we discussed earlier with PfSense.
Key Features
| What is Good? | What Could Be Better? |
|---|---|
| User-Friendly Interface | Complexity for Small Deployments |
| Comprehensive Security Features | Limited Advanced Networking Features |
| Extensive Reporting and Logging | |
| App Store for Additional Functionality |
OPNsense is a comprehensive Open Source Firewall that is based on FreeBSD and is superior to Deciso’s firewall software. A Dutch firm designs and manufactures a variety of networking devices and offers paid customer service plans for OPNsense.
It is a fork of PfSense, originally developed by the m0n0wall team, and is based on FreeBSD. The m0n0wall development team was transferred to OPNsense by its creator, Manuel Kasper, after the project collapsed in February 2015.
OPNsense supports both i386 and x86-64 architectures and features a web-based user interface.
Key Features
| What is Good? | What Could Be Better? |
|---|---|
| Open-Source and Free | Limited Commercial Support |
| Customizable and Extensible | System Updates and Compatibility |
| Comprehensive Security Features | |
| Active Community and Support |
Endian Firewall is one of the best open-source firewall security solutions based on Linux are available from the Endian Firewall Community (EFW).
There is no need to give or provide assistance, as the software can be obtained without cost. It provides a wide variety of customization options for enhancing existing firewall security.
Users and developers alike will find this program useful for setting up even the most fundamental forms of web and email security with minimal effort.
However, there are more features available, such as robust open-source antivirus protection and VPN capabilities while running EFW.
Key Features
| What is Good? | What Could Be Better? |
|---|---|
| Interface that is easy to use | Not enough community and documentation |
| What is good? | Changes in Feature Set |
| Help with VPNs | |
| Filtering the web and proxy |
IPFire is the top open-source firewall since it was built on top of Netfilter. It is often modified and created with both modularity and a high level of flexibility in mind.
Simple configuration allows for usage as a VPN gateway, proxy server, or firewall. Thousands of developers from across the world work together in an online community to update and improve this program.
When scanning your network for vulnerabilities, this program also employs an Intrusion Detection System (IDS). In other words, it will immediately stop the attacker if it detects an attack.
Key features
| What is good? | What could be better? |
|---|---|
| Security-Focused Features | Dependency on Open-Source Components |
| User-Friendly Web Interface | Limited Commercial Support |
| Modular and Extensible | |
| Performance and Stability |
IPCop, an open-source firewall distribution based on Linux, allows us to keep our network at home and in the office safe and secure.
It lacks a graphical user interface and is only accessible via the command line, which may make it challenging for some users to install and set up the application.
In addition, you might need to have some server and firewall expertise to use the software properly. This means that sophisticated users have a lightweight option to choose from.
This program is under 60MB in size and was primarily developed for computers with an i486 processor.
Key features
| What is good? | What could be better? |
|---|---|
| Open-source | Limited scalability |
| User-friendly interface | Software updates |
| Security features | |
| Community support |
Firewall as a Service (FWaaS) from Perimeter 81 can be set up in minutes, providing safe, off-site access to cloud based firewall services for businesses.
Additionally, it enables administrators to restrict access to certain network resources based on the identities of individual users or groups.
This means that administrators can simply regulate who in the organization can access which resource. Unlike physical firewalls, the FWaaS from Perimeter 81 can be set up in minutes.
FWaaS’s user segmentation and fine-grained permission-based controls are powerful tools for protecting corporate data and mobile employees.
It works with every platform (Windows, Mac, iOS, Android, and even Linux servers) and any device.
Key Features
| What is Good? | What Could Be Better? |
| Secure Remote Access | Dependency on Internet Connectivit |
| User-Friendly Interface | Performance Impact |
| Scalability and Flexibility | |
| Granular Access Control |
Shorewall Linux is a free open-source firewall for servers and routers. This means its applicability is not restricted to VMs alone. It is classified as an IPtables setup tool that may transform a server into a hardware firewall appliance.
Shorewall customers can pick a distribution that best suits their requirements. There is also a Linux distribution with two network interfaces that can function as a router and firewall for a private network.
The firewall/router and DMZ setup can be customized per user thanks to the router’s three separate interfaces. The installation options are useful for users who need to conceal many public IP addresses.
Key features
| What is good? | What could be better? |
|---|---|
| Flexible configuration | Command-line interface |
| Extensive documentation and resources | Dependency on Netfilter |
| Support for complex networks | |
| Logging and reporting |
Smoothwall is an open-source firewall program written in the Python programming language and based on the Linux operating system.
Installation and use required minimal familiarity with Linux, and configuration and maintenance were handled using a web-based graphical user interface.
Local area networks, virtual private networks, firewalls (internal and external), Web proxy acceleration, and traffic monitoring and analysis are just a few of the features that this program supports.
Key Features
| What is good? | What could be better? |
|---|---|
| Security-focused | Dependency on SmoothWall hardware |
| User-friendly web interface | Commercial support options |
| Bandwidth management | |
| Add-on modules |
More than simply a router firewall, ClearOS is a full-fledged open-source firewall and unified threat management (UTM) system with more than 120 customizable features available as applications. The web-based interface allows for customization of each and every one of them.
In addition, they have ClearVM, a management solution that allows them to install many instances of ClearOS, in addition to other Linux distributions and even Windows, on a single physical server.
Key Features
| What is good? | What could be better? |
|---|---|
| Easy to Use | Third-Party Software Availability |
| Modular Design | Customization Constraints |
| Extensive Feature Set | |
| Community Support |
Conclusion
According to Cyber Security News research, these are some of the best open-source firewalls available in the open-source world to protect your infrastructure.
We have chosen them because they are cost-effective and user-friendly applications.
So here, we have provided all the information about the top 10 open-source firewall lists to protect your infrastructure.
So, try them and see which one is better for you and more helpful. Hence, if you have any other open-source firewall application that you have used and think is most suitable, then please let us know in the comment section below.
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