Firewalls are designed for both single computer and for a network. Host-based Firewall and Network-based Firewall. A network-based firewall could be a hardware, application or both. A network-based firewall can be installed on administrator’s system for monitoring incoming and outgoing activities between computers in the network.
Best Free Network-based Firewalls for Windows & Unix
The following free network-based firewall:
An open source security solution with a custom kernel based on FreeBSD OS. pfSense is one of the leading network firewalls with a commercial level of features.
pfSense is available as a hardware device, virtual appliance, and downloadable binary (community edition).
IPFire is built on top of netfilter and trusted of companies worldwide.
OPNSense is a fork of pfSense and m0n0wall. GUI is available in multiple languages.
4. NG Firewall
NG Firewall by untangle is a single platform where you can get everything you need to protect your organization network.
Smoothwall express is a free solution with a simple web interface to configure, manage the firewall.
ufw (uncomplicated firewall) works with Ubuntu. It provides a command line interface to manage the Linux kernel packet filtering system (netfilter).
csf (ConfigServer security) is supported and work on many OS and virtual servers. csf is a stateful firewall, login detection and security solution for Linux servers.