Top 10 Open-Source Firewalls of 2021

Open-Source software is a type of software whose original source code is made freely available for anyone to see, modify and distribute the code as they see fit. Although, in some cases redistribution may not be allowed.

Firewall is a network security device/software which helps to scan and filter incoming and outgoing network traffics within a network. It basically runs on security policies and rules setup by a company or any people using it. There are basically three types of firewall:

Packet Filter : It control the network access by analyzing the outgoing and incoming packets.
Stateful inspection firewall: It examines the traffic streams from end to end and use an intelligent way to ward off the unauthorized traffic by analyzing the packet header and inspecting he state of the packet along with the providing proxy services.
Proxy server Firewalls: It filters messages at the application layer of network. It basically mask user’s IP and limit traffic types and they also provide protocol-aware security analysis for protocols they allow.

There are a large number of such open-source firewall that are developed. But only a few have functionalities and features that standout among others. Some of those firewall best suited for a complex network infrastructure as well as home network are provided below:

1. Pfsense

Pfsense is a free network firewall distribution, based on the FreeBSD operating system with a custom kernel and including third party free software packages for additional functionality. Pfsense software, with the help of the package system, can provide the same functionality or more of common commercial firewalls, without any of the artificial limitations.

It includes a web interface for the configuration of all included components. There is no need for any UNIX knowledge, no need to use the command line for anything, and no need to ever edit any rule sets manually. There is a learning curve for users not familiar with commercial-grade firewalls.

The Pfsense project is just the software portion of the firewall which means that users can tailor the hardware to meet the specific environment’s need. Although, they have the option of a purchasing a Security Gateway Appliance directly from Netgate®.

However, Pfsense firewall lacks some features such as web filtering and antivirus which can be easily mitigated by installing external add-ons through the package manager.

Key features of Pfsense:

  • Acting as a router. (you can disable firewall filter and make the Pfsense work as a pure router.)
  • NAT (Network Address Translation)
  • Multi-Wan
  • Load balancing
  • HA (High availability)
  • VPN
  • PPoE server
  • Graphics and log monitoring
  • Dynamic DNS
  • Captive portal
  • GeoIP blocking
  • Anti-spoofing

Even though the Pfsense firewall is free of cost, user have to pay for the firewall device or cloud firewall. It basically starts from $300 for a physical device, however there is an option for the cloud version starting at the rate of $0.08 per hour. But it is always possible to install it on your own hardware or VM.

2. OPNSense

OPNsense is an opensource, easy-to-use and easy-to-build HardenedBSD based firewall and routing platform. It includes most of the features available in expensive firewalls, and more in many cases. It brings the rich features of commercial offerings with the benefits of open and verifiable sources. This provides an effective way for professionals to secure their network due to the streamlined user interface and searchable online documentation of OPNSense.

Key features:

  • Forward-caching proxy
  • Two-factor authentication
  • VPN support
  • Network flow monitoring
  • Support of plugins
  • Dynamic DNS
  • Highly encrypted configuration backup
  • Capital portal
  • Support for plugins
  • Built-in and reporting and monitoring Tools
  • DHCP server and relay
  • Intrusion Exposure and Inline Prevention

3. Untangle firewall

Untangle firewall is based on debian OS. This firewall is easy-to -use, free, and ideal for infinite scalibilty. It supports both IPv4 and IPv6 live view on passed and blocked traffic. The basic network functions are provided with the free and paid applications to add additional functionalities, all managed through a web-based user interface. Two-factor authentication is also available as an additional functionality through the system, both for the user and services like VPN
Basically, the technical name of this firewall is NG firewall, and user can easily install this firewall system on any hardware or virtual machine or buy a device with NG firewall preinstalled. It also has multi-language support for various users, along with an intuitive user interface for easy access and development.

Key features:

  • Spam Blocker Lite
  • Phishing Blocker
  • Virus Blocker
  • OpenVPN
  • Intrusion prevention
  • Adblocker
  • Restricted portal
  • Web monitor
  • Access to remote sign-in

It also has both free and paid versions. Paid versions cost based on the usage, number of systems that are protected and the license term. Normally, prices start at $270 for 12 devices and increases with the increase in the device number and the usage type.

4. IpFire

IPFire developed on top of the Netfilter, is a lightweight and powerful firewall. It is one of the best open-source firewalls. It is generally modified and designed with both modularity and a high level of flexibility in mind. It provides and extensive protection from attacks through DDoS and internet connections. Users even get access to an IDS (Intrusion Detection System) for analyzing the network traffic and pinpointing potential exploits. If any attacks are detected with the IPFIre, users will be able to set the system up to automatically block the attacker. This software is maintained by online community that includes thousands of developers. Like many firewalls listed above, IPFire also has a web-based management interface for settings changes and can be used to configure the network to suite different needs such as advanced graphical and logging reports.

Key features:

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

5. Shorewall

Shorewall is a free Linux-based, new-generation firewall that can be installed on server or routers. It is classified as an Iptables configuration tool that can transform a server into a hardware firewall appliance. But it is not designed to be installed on virtual machines. To fit their demands and necessity, user can choose from the various distribution for shorewall. However, there is one standalone Linux system for protecting one public IP, there are also options to install multiple public IP address. But the user can also download a two-interface Linux system which can even work as a router/firewall for a small house network. On top of all this, User can even configure a DMZ by adding another interface in the two-interface system.

Key features:

  • No limitation on the number of network interface
  • Multiple zones per interface permitted
  • Completely customizable
  • Great interface
  • Multiple interfaces per zone.

6. SmoothWall Express

Smoothwall is a GNU/Linux based open-source firewall. It has its own Linux-based OS and a web based interface for the users to configure and see data. Users only need a little bit of Linux to install and use it and users can easily configure it via a web-based GUI interface. Its OS is security hardened in order to avoid any vulnerability within the firewall itself. Smoothwall supports LAN, DMZ, internal/external network firewall, Web proxy for acceleration, traffic stats, and many more.

It’s OS is available on both 32-bit and 64-bit systems and can be deployed to user’s server.

Key features:

  • Outbound filtering
  • UPnP support
  • Modified and Access time
  • IP blocking

7. Vyos

Vyos is an open-source network OS based on GNU/Linux that provides a unified management interface for all functions like traditional hardware routers. It provides a free platform which can easily match up to the level of the well-know network solution devices. It can run on standard amd64, i586 and ARM systems and can act as both router and firewall platform for cloud deployments. It runs on bare metal as well as hypervisors and cloud platforms which help us to save costs as we can use the same OS everywhere and connect to on-premises networks with cloud sites without the limitation and vendor-specific VPN.  Furthermore, the built-in SaltStack integration and official Ansible module allows automating configuration workflow and for custom automation solutions, a HTTP API is available.

Vyos routing features include:

  • Policy-based and multipath routing
  • VPN and tunneling protocols
  • Routing protocols (BGP, OSPF, RIP)
  • Stateful and zone-based
  • NET
  • QoS and shaping
  • NetFlow and slow traffic accounting.

8. Endian Firewall

Endian firewall provides a Linux-based security solution for users.  It is available both in free and paid version, major difference between them being, for free version there are no discount. IT provides users with multiple options so it can even add an extra firewall. In the Endian firewall we also have features like powerful open-source antivirus protection and VPN features and also basic setup of web and email security. Furthermore, there are additional features that users can download like standalone distribution that are installed on servers or routers.

Key features:

  • Extra firewall
  • Email and web security
  • Intrusion prevention
  • Multi-WAN

9. Clear OS

Clear OS a unified threat management solution (UTM) is a Linux-based firewall designed for installation on Linux servers. It provides features like monitoring and controlling access to local services and application of the machine as well as the rest of the network.  It basically acts as a local software firewall that protects the local network, however it also can as a network firewall. It provides upto 120 functions through applications known as add-ons.  This firewall can be configured by using web-interface. ClearOS developers have added a custom firewall tool that can be used to add IPTABLES rules to the machine therefore enabling it to protect more complex network environments. Furthermore, for advanced user the developers have developed an advanced firewall tool which can help establish special firewall rules or allow connections to webconfig. ClearOS can also be deployed on it own management solution that is called ClearVM. ClearVM can also deploy multiple ClearOS virtual machine as well as other Linux distros and even windows OS on their physical server.

Key features:

  • OpenVPN
  • Intrusion detection and prevention system
  • E-mail services
  • Web proxy
  • IPSEC
  • PPTP

10. Sophos Firewall Home edition

Sophos Firewall Home edition is a free software version of the Sophos XG firewall aimed for home users.  It contains its own operating system. It provides full protection to user’s home network, including anti-malware, web security and URL filtering, application control, IPS, traffic shaping, VPN, reporting and monitoring and much more.  It also provides easy configuration and monitoring from web interface so users can use the firewall easily although there is a learning curve unless you have prior experience to commercial-based firewall.

It however, requires a dedicated computer as it overwrite all/any content present on the computer during its installation and thus acts as a separate fully functional security appliance.

Key Features:

  • Policy Management
  • Access home network from anywhere using VPN
  • Application Gateway
  • Concurrent Sessions
  • Load Balancing
  • Intrusion Prevention and Detection
  • Antivirus and URL filtering

Written By:

Vedant Agrawal

Founder,LD CLoud

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