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.

The Pi-hole® is a DNS sinkhole that protects your devices from unwanted content without installing any client-side software.

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.

Controls individual app internet access without root, blocks Wi-Fi and mobile data, supports IPv4/IPv6, logging, privacy protection, and detailed notifications.

Standalone firewall for Windows 7 and newer with flexible network rules, SvcHost filtering, bandwidth graphs, speed limits, wildcards, and traffic statistics.

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.

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...

TrackerControl allows users to monitor and control the widespread, ongoing, hidden data collection in mobile apps about user behaviour ('tracking').

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...

AdGuard Home is a network-wide software for blocking ads & tracking. After you set it up, it'll cover ALL your home devices, and you don't need any client-side software for that.

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.

Firewall for Linux providing interactive outbound filtering, blocking ads and malware domains, configurable via GUI, with centralized node management.

Free macOS firewall blocking unknown outgoing connections until approved, detects unauthorized activity, open source, privacy-focused, audit-ready code.

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.

Block ads system-wide on Android using local VPN-based DNS filtering. No root needed. No data collection.

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.

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.

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).

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.

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