Open Source Linux Firewall Software
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Firewall Software for Linux
View 15 business solutionsBrowse free open source Firewall software and projects for Linux below. Use the toggles on the left to filter open source Firewall software by OS, license, language, programming language, and project status.
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VTun is the easiest way to create Virtual Tunnels over TCP/IP networks with traffic shaping, compression, and encryption. It supports IP, Ethernet, PPP and other tunnel types. VTun is easily and highly configurable. VPN, Mobile IP, Shaping, etc
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Smoothwall is a best-of-breed Internet firewall/router, designed to run on commodity hardware and to provide an easy-to-use administration interface to those using it. Built using open source and Free software, it's distributed under the GNU Public License.
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Privoxy
HTTP proxy to block ads and customize webpages
Privoxy is a non-caching web proxy with advanced filtering capabilities for enhancing privacy, modifying web page data and HTTP headers, controlling access, and removing ads and other obnoxious Internet junk. Privoxy has a flexible configuration and can be customized to suit individual needs and tastes. It has application for both stand-alone systems and multi-user networks. -
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UPnP PortMapper
Manage port forwardings via UPnP
The UPnP PortMapper can be used to easily manage the port mappings/port forwarding of a UPnP enabled internet gateway/router in the local network. -
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IPCop Firewall
Linux firewall distribution geared towards home and SOHO users.
The IPCop Firewall is a Linux firewall distribution. It is geared towards home and SOHO users. The IPCop web-interface is very user-friendly and makes usage easy. -
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OpenSnitch
OpenSnitch is a GNU/Linux port of the Little Snitch firewall
OpenSnitch is a GNU/Linux port of the Little Snitch firewall. You can launch the GUI from the icon or from the system menu. The daemon will start intercepting connections, prompting you to allow or deny them. If you don't apply an action, after 15 seconds (configurable) it'll apply the default action configured. When you open the GUI, you'll see all the connections and processes that the daemon has intercepted. Double click on a row to view the details of a process, rule, host or user. Once you know which are the common processes, IPs and hosts that your machine is connecting to, you can start creating permanent rules (Duration: always) to deny or allow them. You can also convert temporary rules to permanent by right-clicking on a temporary rule or by double-clicking on it, and then edit it. By default OpenSnitch UI listens on a local Unix socket in /tmp/osui.sock. -
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CacheGuard Gateway
Free UTM appliance: firewall, VPN, WAF and antivirus in one ISO.
Securing your network should not require an enterprise budget. CacheGuard is a free open-source network security appliance for startups and growing businesses that need serious protection without the complexity. Install CacheGuard-OS on any x86 machine or VM and get a complete security gateway in under an hour. No plug-ins, no compatibility issues. Everything works out of the box. CacheGuard-OS is not an app, it IS the OS. A fully custom network appliance operating system built from scratch over 20 years, now fully open source. One ISO includes: firewall, VPN, web antivirus, URL filtering, SSL inspection, WAF, reverse proxy, load balancer and QoS. Free for any number of users. Optional paid support available. Source code: https://github.com/cacheguard/CacheGuard-OS Website: https://www.cacheguard.com/ -
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Those who have read past the "Malware" warning can be assured there is absolutely no malware in this OS or in the download. This warning comes from the "netcat" binary included in the download as a DOS time client. Unfortunately netcat has code that is flagged as malware. FREESCO, a NAT/firewall router/server based on Linux and runs on a single 1.44MB floppy. Freesco is very powerful and versatile and can connect multiple home or small office networks to most types of Internet connections including dialup.
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Endian Firewall Community (EFW) is a "turn-key" linux security distribution that makes your system a full featured security appliance with Unified Threat Management (UTM) functionalities. The software has been designed for the best usability: very easy to install, use and manage and still greatly flexible. The feature suite includes stateful packet inspection firewall, application-level proxies for various protocols (HTTP, FTP, POP3, SMTP) with antivirus support, virus and spam-filtering for email traffic (POP and SMTP), content filtering of Web traffic and a "hassle free" VPN solution (based on both OpenVPN and IPsec).
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MongoDB Atlas runs apps anywhereMongoDB Atlas gives you the freedom to build and run modern applications anywhere—across AWS, Azure, and Google Cloud. With global availability in over 115 regions, Atlas lets you deploy close to your users, meet compliance needs, and scale with confidence across any geography.
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SS5 is a socks server for Linux, Solaris and FreeBSD environment, that implements the SOCKS v4 and v5 protocol.
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SafeLine
Serve as a reverse proxy to protect your web services from attacks
SafeLine is a self-hosted WAF(Web Application Firewall) to protect your web apps from attacks and exploits. A web application firewall helps protect web apps by filtering and monitoring HTTP traffic between a web application and the Internet. It typically protects web apps from attacks such as SQL injection, XSS, code injection, os command injection, CRLF injection, LDAP injection, XPath injection, RCE, XXE, SSRF, path traversal, backdoor, brute force, HTTP-flood, bot abuse, among others. By deploying a WAF in front of a web application, a shield is placed between the web application and the Internet. While a proxy server protects a client machine’s identity by using an intermediary, a WAF is a type of reverse-proxy, protecting the server from exposure by having clients pass through the WAF before reaching the server. A WAF protects your web apps by filtering, monitoring, and blocking any malicious HTTP/S traffic traveling to the web application. -
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OPNsense
OPNsense is an open source, easy to use firewall and routing platform
OPNsense is an open source, easy to use and easy to build FreeBSD based firewall and routing platform. OPNsense includes most of the features available in expensive commercial firewalls, and more in many cases. Mission statement of the project: "Give users, developers and businesses a friendly, stable and transparent environment. Make OPNsense the most widely used open source security platform." -
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Firewall Builder is a GUI firewall management application for iptables, PF, Cisco ASA/PIX/FWSM, Cisco router ACL and more. Firewall configuration data is stored in a central file that can scale to hundreds of firewalls managed from a single UI. A message from project maintainers: After working on Firewall Builder for many years it is with some sadness that Vadim and I are announcing that we have suspended all development activity for this project. Firewall Builder has been a great project to work on and we have truly appreciated all the support and positive feedback that the user community has provided. Without you we wouldn’t have been able to keep things going this long. You might be wondering why we are doing this... We had an exciting opportunity come up to start a company developing advanced security automation solutions. This was a chance of a lifetime that we just couldn’t pass up and unfortunately it means that we no longer have time available to work on improv
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PeerGuardian
PeerGuardian - a privacy oriented firewall application
PeerGuardian is a privacy oriented firewall application. It blocks connections to and from hosts specified in huge blocklists (thousands or millions of IP ranges). Its origin seeds in targeting aggressive IPs while you use P2P. PeerGuardian Linux: Not developed actively anymore. Team might still be around. Some unreleased changes on git. Outdated technology. Peerguardian OS X: Not developed anymore. We've lost contact with the OS X developer. PeerGuardian Windows: Not developed anymore. It's highly recommended to use PeerBlock instead, which is a continuation of PeerGuardian's development in Windows, with bug fixes and support for Windows Vista and Windows 7. Collaboration with peerblock.com is welcome! PeerGuardian is an open project. Not only is its source code open for you to read, use, and modify - but the project is open for you to join and contribute in any form (code, documentation, bug reports, web and support). -
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CrowdSec
Firewall able to analyze visitor behavior & provide adapted response
CrowdSec - an open-source massively multiplayer firewall able to analyze visitor behavior & provide an adapted response to all kinds of attacks. It also leverages the crowd power to generate a global IP reputation database to protect the user network. Crowdsec shouldn't, and didn't crash any production so far we know, but some features might be missing or undergo evolutions. IP Blocklists are limited to very-safe-to-ban IPs only (~5% of the global database so far, will grow soon). A modern behavior detection system, written in Go. It stacks on Fail2ban's philosophy, but uses Grok patterns & YAML grammar to analyse logs, a modern decoupled approach (detect here, remedy there) for Cloud/Containers/VM based infrastructures. Once detected you can remedy threats with various bouncers (block, 403, Captchas, etc.) and blocked IPs are shared among all users to further improve their security. Crowdsec is an open-source, lightweight software, detecting peers with aggressive behaviors. -
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Siproxd is a proxy/masquerading daemon for the SIP protocol. It allows SIP clients (softphones & hardphones) to work behind an IP masquerading firewall or router.
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SSHGuard
Intelligently block brute-force attacks by aggregating system logs
SSHGuard protects hosts from brute-force attacks against SSH and other services. It aggregates system logs and blocks repeat offenders using several firewall backends, including iptables, ipfw, and pf. -
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jNetPcap - A Libpcap Java Binding
A java PCAP and DPI library
A java wrapper for popular "libpcap" and "WinPcap" libraries. Accurate full API translation. Packet buffers delivered with no copies. Send custom packets, gather statistics. Comprehensive and easily extensible DPI engine. -
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ModSecurity is a web application firewall that can work either embedded or as a reverse proxy. It provides protection from a range of attacks against web applications and allows for HTTP traffic monitoring, logging and real-time analysis.
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BASE is the Basic Analysis and Security Engine. It is based on the code from the Analysis Console for Intrusion Databases (ACID) project. This application provides a web front-end to query and analyze the alerts coming from a SNORT IDS system.
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Netdeep Secure Firewall
Next Generation Open Source Firewall
Netdeep Secure is a Linux distribution with focus on network security. Is a Next Generation Open Source Firewall, which provides virtually all perimeter security features that your company may need. It offers Web content filters, ensuring better performance of the network, allowing users to use the service efficiently and securely, providing a deep control of the use of the Web access service, blocking access to unwanted websites, Virus, Spam, Applications and intrusion attempts. Its configuration is made entirely by the web interface. -
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AgentGuard
AgentGuard is a firewall for AI agents
AgentGuard is a real-time protection layer designed to safeguard AI agents and applications from runaway execution, excessive costs, and unsafe behavior during interaction with large language model APIs. It works by intercepting API calls made by an AI system and continuously monitoring usage, including token consumption and associated costs, allowing developers to enforce strict budget limits. When predefined thresholds are reached, the system can automatically halt execution, trigger alerts, or gracefully terminate processes depending on the configured mode. This makes it particularly valuable in environments where agents operate autonomously and may enter unintended loops or inefficient workflows. The tool integrates directly into existing applications with minimal changes, often requiring only a few lines of code to activate protection. It also supports advanced configurations such as distributed tracking through Redis and webhook notifications for real-time monitoring. -
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Coraza
OWASP Coraza WAF is a golang modsecurity compatible firewall library
Coraza is an open-source, enterprise-grade, high-performance Web Application Firewall (WAF) ready to protect your beloved applications. It is written in Go, supports ModSecurity SecLang rulesets and is 100% compatible with the OWASP Core Rule Set. Coraza is a drop-in alternative to replace the soon-to-be abandoned Trustwave ModSecurity Engine and supports industry-standard SecLang rule sets. Coraza runs the OWASP Core Rule Set (CRS) to protect your web applications from a wide range of attacks, including the OWASP Top Ten, with a minimum of false alerts. CRS protects from many common attack categories including: SQL Injection (SQLi), Cross Site Scripting (XSS), PHP & Java Code Injection, HTTPoxy, Shellshock, Scripting/Scanner/Bot Detection & Metadata & Error Leakages. Coraza is a library at its core, with many integrations to deploy on-premise Web Application Firewall instances. -
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Enables tunneling of network connections through restrictive HTTP proxies. Features: Portmapping, SOCKS4, SOCKS5, web-based admin interface, possibility to use standalone server (perl) or hosted server (PHP), optional authorization from LDAP or MySQL
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OWASP ModSecurity CRS
OWASP ModSecurity Core Rule Set (CRS) Project
The OWASP ModSecurity Core Rule Set (CRS) is a curated, generic Web Application Firewall rule set that detects and blocks common attack categories across most web apps. It focuses on broad protection—SQL injection, cross-site scripting, local/remote file inclusion, command injection, and protocol violations—without requiring app-specific knowledge. Rules are organized into paranoia levels so operators can tune detection aggressiveness and balance false positives against coverage. An anomaly-scoring model accumulates rule hits per request, enabling nuanced blocking thresholds and easier incident triage. The project ships with extensive documentation, exclusion packages, and testing tools to help tailor deployment for frameworks, CDNs, and APIs. Deployed on engines such as ModSecurity or compatible WAFs, CRS is a widely used baseline for HTTP security in reverse proxies and gateways.
