OSI-licensed only · self-hostable
OPNsense is itself open source: its repository is licensed BSD-2-Clause and the project says it is and will always be available under the 2-Clause BSD licence. Its docs describe an open-source firewall and routing platform built on FreeBSD with IDS/IPS, VPN, high availability and plugins. People look at other options when they want a Linux base, a CLI-driven router, or an embedded device.
Every tool below is under an OSI-approved licence, checked against its repository. They range from a FreeBSD firewall distribution to Linux router OSes and a firewall daemon.
Licences checked against each repository on November 7, 2026.
| Tool | Best for | Licence | Runs as |
|---|---|---|---|
| pfSense CE | Closest like-for-like FreeBSD firewall | Apache-2.0 | Server |
| OpenWrt | Firewalls and routers on embedded hardware | GPL-2.0 | Server |
| VyOS | CLI-driven routing and firewalling | GPL-2.0 | Server |
| NethSecurity | Linux firewall on OpenWrt | GPL-2.0 | Server |
| firewalld | Firewall on a Linux host | GPL-2.0 | Server |
Best for: Closest like-for-like FreeBSD firewall
A free network firewall distribution based on FreeBSD with a custom kernel, forked in 2004 from m0n0wall. The README notes the copyright belongs to Rubicon Communications (Netgate).
Best for: Firewalls and routers on embedded hardware
A Linux operating system for embedded devices with a fully writable filesystem and package management. The GitHub repository is a mirror and not active for check-ins.
Best for: CLI-driven routing and firewalling
The repository holds VyOS command definitions, configuration scripts and data. It carries GPL-2.0 and LGPL-2.1 licence files.
Best for: Linux firewall on OpenWrt
An open-source Linux firewall built as a downstream rebuild of OpenWrt, succeeding the NethServer 7 firewall suite and mainly aimed at x86_64 machines.
Best for: Firewall on a Linux host
A firewall daemon with a D-Bus interface for dynamic firewall management, using zones to set trust levels for connections and interfaces.
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| If you need… | Start with |
|---|---|
| A FreeBSD firewall like OPNsense | pfSense CE |
| Firewall on small embedded hardware | OpenWrt |
| Scripted routing and firewalling | VyOS |
| Linux firewall with a managed OpenWrt base | NethSecurity |
| Firewall zones on an existing Linux server | firewalld |
Quick answers to common questions
Yes. Its repository is licensed BSD-2-Clause and the project states it will always be available under that licence.
pfSense CE. Both are FreeBSD-based firewall distributions with a web interface, and pfSense's repository is Apache-2.0.
Yes. NethSecurity and OpenWrt are Linux based, and firewalld manages firewall zones on a Linux host.
VyOS keeps its configuration in command definitions and scripts. Check its project for the current release channels.
It can run firewalls on embedded devices, but it is positioned as an operating system for embedded hardware rather than a full appliance with the features OPNsense bundles.
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