Even before computer viruses and network security became a concern, the idea of a firewall was familiar. We construct them to prevent certain unwanted “things” from passing through. The firewall in your car prevents an engine fire from passing into the passenger compartment. In IT systems, firewalls enhance network security by ensuring only certain types of network traffic is allowed. Firewall software can be configured in operating systems, including end user devices. The network administrators who manage organizational networks use much more sophisticated firewall tools that are integrated into unified threat management technology, but all firewalls operate on the same types of rules:
- Allow or disallow
- Types of traffic
- Network addresses (for example