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.

Visualizes network activity, alerts on suspicious behavior, manages firewall rules, reports new app connections, and identifies potential threats.

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...

An advanced Windows tool for internet traffic control and monitoring. Set speed limits for apps and connections, with real-time and long-term stats.

Firewall tool for monitoring, controlling, and alerting on outgoing network connections, with real-time user notifications and customizable rule-based access control.

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...

A powerful tool which extends the functionality of Windows Firewall and provides new extra features which makes Windows Firewall better.

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.

Comodo Internet Security is a free, very voluminous and multi-layered security application that keeps hackers out and personal information in.

Comodo Firewall is a personal firewall, a genre of security software that secures PCs by policing Internet traffic on an app by app basis. The most prominent feature of a personal firewall is generating popup notifications when an unknown program attempts to access the Internet...

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

Tiny Shield keeps your network safe by watching all connections and stopping bad stuff before it can harm your computer. Tiny Shield keeps an eye on everything your Mac connects to, making sure you can see all your internet activity in one place.

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.