A network-based firewall controls traffic going in and out of a network. It does this by filtering traffic based on firewall rules and allows only authorized traffic to pass through it. Most
organizations include at least one network-based firewall at the boundary between their internal network and the Internet.
The network-based firewall is usually a dedicated system with additional software installed to monitor, filter, and log traffic. For example, a popular network-based firewall used in many larger
environments is Sidewinder. This is a dedicated server with proprietary firewall software installed.
A network-based firewall would have two or more network interface cards (NICs) and all traffic passes through the firewall. Many network-based firewalls are dedicated servers or appliances.