Open Source Firewalls

Free and open-source tool that monitors all network activity, blocks unwanted connections, uses filter lists for ads and malware, enforces DNS-over-TLS, and sets custom app rules.

Simple tool to configure Windows Filtering Platform (WFP) which can configure network activity on your computer.

An OpenSnitch-inspired firewall and network monitor + a pi-hole-inspired DNS over HTTPS client with blocklists.

Athena is a Material You (Material 3) firewall and ad blocker that works seamlessly on both rooted and non-rooted devices.

Simple firewall for MS Windows.

OPNsense includes most of the features available in expensive commercial firewalls, and more in many cases. It brings the rich feature set of commercial offerings with the benefits of open and verifiable sources.

pfSense is a free and open source firewall and router that also features unified threat management, load balancing, multi WAN, and more.

NetGuard provides simple and advanced ways to block access to the internet - no root required.

PeerBlock lets you control who your computer "talks to" on the Internet. By selecting appropriate lists of "known bad" computers, you can block communication with advertising or spyware oriented servers, computers monitoring your p2p activities, computers...

TinyWall is a free software to harden and control the advanced firewall built into Windows Vista, Windows 7 and Windows 8. TinyWall includes a combination of features that sets it apart from both commercial and freeware firewalls: TinyWall does not annoy you with popups at all...

LuLu is the free, shared-source macOS firewall that aims to block unknown outgoing connections unless explicitly approved by the user.

OpenSnitch is a GNU/Linux application firewall.

Minimal Firewall is a portable Windows firewall frontend that alerts users to internet connections without requiring custom kernel modifications or disabling core isolation, striking a balance between TinyWall's security and SimpleWall's functionality.

CrowdSec is a security automation engine, using both local IP behavior detection & our community-driven IP reputation database.

Fail2ban scans log files (e.g. /var/log/apache/error_log) and bans IPs that show the malicious signs -- too many password failures, seeking for exploits, etc. Generally Fail2Ban is then used to update firewall rules to reject the IP addresses for a specified amount of time...

Firewall (iptables frontend), based on DroidWall which is no longer being developed. A paid "donate"-version with more features it advertised within the app.

IPFire is a server distribution with intended to use as a firewall. It focuses on flexibility, and scales from small to middle sized business networks and home networks.

ClearOS is a family of operating systems for the enterprise, small business, and home. There are three editions to choose from depending on your needs and suitable to your abilities. They are: ClearOS Enterprise, ClearOS Home, and ClearOS Core.

Gufw is an easy, intuitive way to manage your Linux firewall. It supports common tasks such as allowing or blocking pre-configured, common p2p, or individual ports port(s), and many others! Gufw is powered by Uncomplicated Firewall (ufw).

Windows Firewall Notifier (WFN) extends the default Windows embedded firewall behavior, allowing to visualize and handle incoming or outgoing connections.

Ufw stands for Uncomplicated Firewall, and is program for managing a netfilter firewall. It provides a command line interface and aims to be uncomplicated and easy to use.

A lightweight, privacy focused Android firewall application that blocks network connections for selected apps without requiring root access or VPN. ShizuWall leverages Shizuku to provide powerful network control capabilities. Requires Android 11 (API 30) or higher.

Privacy isn’t default. Take it back with De1984 Firewall and Package Control.

SSHGuard monitors services through their logging activity. It reacts to messages about dangerous activity by blocking the source address with the local firewall. SSHGuard employs a clever parser that can transparently recognize several logging formats at once (syslog, syslog-ng...

Blocker is a component controller for Android applications that currently supports using PackageManager and Intent Firewall to manage the state of components. It can be seamlessly switched between these controllers, and for application rules, you can export and import them.