5 Open Source Security Firewalls for Linux System

Iptables
Iptables is an open-source firewall utility for Linux based operating system. Iptables is a very flexible tool based on the command line. It is used for maintenance, set up, and inspect the table of IP packet and filer rules. These tables consist of many user-defined chains. Most Linux administrator uses it for tuning of their server. Iptables use three different types of chains. These chains are input, forward, and output chains. Input chain is used to control the behavior of incoming connections. Forward chain is used for incoming connections that are not actually being delivered locally. Output chains are used for outgoing connections. Its provide different features to user like provide backup support and file restoration, filter the content of the list, provide flexibility to add, remove, modify rules per your needs, etc.

IPCop
IPCop is an open-source firewall tool for Linux. It is built on the Linux Netfilter framework. The main purpose of this firewall tool is to provide simple to manage firewall appliances on PC hardware. It provides a simple user management update mechanism to install security updates when needed. The team of IPCop is very professional and its aims to provide a secure, stable, and user-friendly management system to their users. This firewall provides a very highly configurable tool. This firewall tool provides a web-based interface to manage the task. This firewall tool is mostly used in small businesses and local PCs. It provides multiple features to their user like It provides auto-rotate logs, Supported Multiple languages and its provide secure stable and easily implementable add on patches.

Shorewall
Shorewall is an open-source firewall tool for Linux-based operating systems. It is built on the Netfilter system into the Linux kernel. It also supported IPV6. I cannot provide a Graphical User Interface for configuration. By using a simple text file you can configure this. By using Shorewall you can watch the status of the system and provide support for testing. This tool is mainly used in network installations. It can be used in a wide range of the router, firewall, and gateway applications easily. It provides the freedom of customization by using its files. This tool provides no limit on the number of network interfaces. It also provides the support of nested and overlapping zones.

Vuurmuur
Vuurmuur is an open-source firewall tool for Linux-based operating systems. This firewall tool built on the top of tables. The configuration of this firewall tool is very easy. It can allow you complex and simple configuration. The configuration configures through Ncurses Graphical User Interface. It also facilitates their user through remote administration for monitoring the logs, bandwidth, and connection in real-time. This firewall tool is very easy to use even new users can easily use this tool. It provides human-readable rule syntax and traffic shaping. It provides a secure default policy and provides anti-spoofing features. It can be configured with NAT very easily.

pfSense
pfSense is a free and open-source firewall tool. This firewall tool distribution based on FreeBSD. It is a very reliable firewall network tool. It provides a web-based interface that can easily configure it through a web-based interface. This software can deploy on the router, DHCP server, perimeter firewall, wireless access point, and VPN endpoint. It provides RRD graph reporting and multi-language support. By using this you can shape your traffic and can get real-time information through Ajax. It provides the functionality of Outbound and inbound load balancing, high availability clustering, and quality of Service.