Usually, in the world of network security, when we talk about Firewalls we mean the devices that help protect your computer systems and networks from attacks and provide a “wall” in front of servers and IT resources.
The above concept of a “Firewall” refers to the classic network hardware firewall such as the Cisco ASA, Checkpoint, Fortigate etc.
However, a firewall in the IT world can be also a software application that can be installed on any off-the-shelf physical server to transform it into a hardware firewall appliance or to protect the server itself as a local security program.
In this article we will be discussing briefly the best open source software firewalls that can be used as both home and enterprise security solutions.
Some of the following open source firewalls have features and capabilities that are comparable to expensive commercial firewall solutions so a lot of companies utilize them as their main protection solution at a fraction of the cost.
Let’s now have a look at the best open source software firewalls that you can download and use for free.
The ranking below is in no particular order.
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#1 pfSense (https://www.pfsense.org/)
Built on the FreeBSD system, pfSense is a free firewall and router that can be used at both home networks and large enterprise environments as well.
It was released in 2004 and remains a free and open source program. However, the company behind the product also provides a wide range of enterprise solutions as well.
The open source firewall is installed locally on a physical machine or on a virtual machine. Users can edit the settings through a web-based interface, making it easy for the typical home user or network admin to set up.
The main benefit of pfSense is the continual support. This software receives regular updates and support from the development team.
Based on a package system for expandability, pfsense can perform a multitude of network and security operations such as:
- Routing and Firewalling
- Load Balancing
- Site-to-Site VPNs
- Blocking of IP addresses based on Threat intelligence feeds, IP Reputation Threat Sources etc.
#2 OPNSense (https://opnsense.org/)
The OPNSense firewall is free to use and easy to install. It provides an effective way for professionals to secure their network, thanks to a streamlined user interface and searchable online documentation.
The software also includes features intended for advanced users. With OPNSense firewall, users can set up network flow monitoring, WAN load balancing, full mesh VPN routing, Stateful Firewall, HTTP load balancer and much more.
The software also provides built-in reporting and analysis. You can monitor network traffic and optimize the performance of your network. OPNSense was first released in 2015 and continues to build a large community with thousands of supporters.
#3 Untangle – NG Firewall (https://www.untangle.com/)
The Untangle FG Firewall provides advanced network security for enterprise networks. It can be installed on a server, a dedicated appliance, a virtual machine or on the public cloud and is used to keep your entire network secure, instead of installing on local machines.
The software is available as a free download in multiple formats to suit your deployment needs. You can download an ISO image, USB image, or OVA VMware image.
Besides the free software, the Untangle company offers the same software package installed as standalone hardware that you can connect to your network. The hardware saves users the hassle of setting up a server or router firewall.
#4 ClearOS (https://www.clearos.com/)
ClearOS is a Linux-based firewall designed for installation on Linux servers. It provides a solution for monitoring and controlling access to local services and applications of the machine as well as the rest of the network. Thus, it’s a local software firewall that protects the server on which it is installed but also it can act as network firewall as well.
The base features of ClearOS are easy to set up and provide a simplified option for adding an extra firewall. It is a lightweight program with a web-based interface. However, the developers also have a custom firewall tool that can be used to add IPTABLES rules to the machine therefore protecting more complex network environments.
For advanced users, there is an advanced firewall tool. Users can use this tool to establish special firewall rules or allow connections to webconfig.
#5 IPFire (https://www.ipfire.org/)
IPFire is a Linux-based firewall that provides advanced network security for companies. It offers protection from attacks through the internet and denial-of-service attacks among others.
The software is maintained by an online community that includes thousands of developers. The resulting open source program is lightweight and powerful. The software also uses an Intrusion Detection System (IDS) to analyze your network traffic and find potential exploits. If an attack gets detected, the attacker is immediately blocked.
Like many firewalls, IPFire uses a web-based management interface for changing settings. You can configure the network to suit your specific needs, whether you need basic firewall protection or advanced logging and graphical reports.
Here are some of the security and network functions that IPFire can perform (in addition to Stateful Packet Inspection device):
- Web Proxy
- VPN termination
- Wireless Access Point
- Tor node
- Proxy and Relay for various protocols
- Backup server, NFS, Samba, Mail Server etc
#6 Smoothwall Express (http://www.smoothwall.org/)
Smoothwall Express is an open source project that was first released in 2000. It includes its own GNU/Linux-based operating system and a web-based interface. The Linux OS is security-hardened to avoid any software vulnerabilities on the firewall itself.
The large development community includes over 17,000 forum members. While the program is Linux-based, it is designed to be easy enough for all professionals to install, even without any previous experience with Linux operating systems.
The OS is downloadable as an ISO image that can be deployed to your server. It works on both 32-bit and 64-bit systems. While the latest release was uploaded in 2014, the software still offers reliable security for home and enterprise users.
#7 IPCop (https://distrowatch.com/)
IPCop is a Linux-based OS that helps secure your home or company’s network. It does not include a graphical interface. It is operated entirely by command line, which may make it difficult for some users to install and set up.
While the software may require technical knowledge of servers and firewalls, it provides a lightweight option for more advanced users. The image size is just 60MB and designed for i486 architecture systems.
Unfortunately, the software is no longer supported. The last update was released in 2012. However, the software is still available for download through several distribution archive websites.
#8 ufw (https://help.ubuntu.com/community/UFW)
UFW is a configurable firewall designed for the Ubuntu Linux operating system. Uncomplicated Firewall (UFW) is the default configuration tool for Ubuntu. However, it is disabled by default.
When users turn on the UFW program, all incoming traffic is denied, other than a few exceptions that are included to make setup easier for home users.
Users can then choose to allow or deny traffic to suit their needs. You can quickly add or delete rules through the Linux terminal. For home users, a GNU frontend is available for download that provides a desktop graphical interface. However, most of its configuration in done using CLI commands.
This is a local firewall for protecting only the server it is installed on.
#9 Shorewall (http://www.shorewall.org/)
Shorewall is a free Linux firewall that can be installed on servers or routers. However, it is not designed for installation on virtual machines. It is categorized as IPtables configuration tool and can transform a server into a hardware firewall appliance.
With Shorewall, users can download the distribution that fits their requirements. There is a standalone Linux system for protecting one public IP address. Users may also download a two-interface Linux system that works as a firewall/router for a small home network.
With the three-interface system, users can set up the firewall/router and add a DMZ.
Installation options are also available for users that need to protect more than one public IP address. Complete documentation is available on the website for setting up the firewall for multiple IP addresses.
#10 Endian Firewall Community (https://www.endian.com/)
Endian Firewall Community (EFW) provides Linux-based security solutions for users. While the software is available for free, the developers do not offer support. It is simply offered as a convenient way to add extra firewall protection.
With this software, users can quickly set up basic web and email security. However, there are additional features to this open source software.
When using EFW, users also receive powerful open source antivirus protection and VPN features. There are quite a few different downloads available, including standalone distributions that are installed on servers or routers.
#11 VyOS (https://www.vyos.io/)
VyOS is an open-source network operating system based on GNU/Linux that provides a unified management interface for all functions like traditional hardware routers.
VyOS provides a free routing platform that competes directly with other commercially available solutions from well-known network providers.
Because VyOS is run on standard amd64, i586 and ARM systems, it is able to be used as a router and firewall platform for cloud deployments.
It runs on bare metal as well as major hypervisors and cloud platforms, so you can use the same OS everywhere and connect your on-premises networks with cloud sites without the limitations and costs of vendor-specific VPN solutions, or you can build inexpensive remote-access VPN for your remote workers. VyOS includes everything you would expect from a router:
- industry routing protocols (BGP, OSPF v2/v3, RIP).
- policy-based and multipath routing.
- VPN and tunneling protocols (IPsec, VTI, L2TP, OpenVPN, Wireguard, GRE, IPIP, SIT, VXLAN, L2TPv3).
- stateful and zone-based firewall.
- high availability (VRRP, connection table synchronization).
- QoS and shaping.
- NetFlow and sFlow traffic accounting.
Image-based update, stateful CLI with commit and rollback capabilities, and built-in config versioning and archiving provide simple and reliable system management.
Built-in SaltStack integration and official Ansible module allow automating configuration workflow. For custom automation solutions, an HTTP API is available.
#12 Sophos XG Home Edition
This product is another completely free and robust option for home users. The firewall is offered as software package that can be installed on a dedicated Intel based compatible computer/device.
For a free firewall it offers features and protections that are found in large commercial solutions. Some examples include URL filtering, malware protection, web security, application protection, VPN etc.
What I like also from this option is the dual-engine antivirus which scans files downloaded, attachments in emails, embedded content in websites etc.
The above means that you have AntiVirus protection on the network level which is over and above any AV solutions you have installed on the end-point devices.
The computer requirements to install Sophos XG are:
- Two network interface cards (NIC)
- Intel based
- Max 6 GB RAM
- Max 4 cores CPU
Before installing one of these free firewalls, ensure that it meets your needs. Some software installs locally while others are installed on separate devices and act as firewall/routers for the entire network.
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