Stateful Inspection

Stateful inspection was introduced by Check Point Software Technologies in the early 90s. It has since replaced static packet filtering as the new firewall standard for computer networks. It offers strengthened security by keeping track of data packets being transmitted over a connection. Stateful inspection examines both outgoing and incoming packets. Outgoing packets requesting certain types of service are tracked, and only incoming packets that warrant an appropriate response are permitted through the firewall. Unlike static packet filtering, a stateful inspection examines packets down to the Application Layer instead of simply checking the packet headers. Network administrators using a firewall with stateful inspection capability can set parameters to meet their specific needs. In the average network that is connected to the internet, ports are typically closed unless they are specifically requested connection from an incoming packet. Even when this is the case, only that port will be opened to the packet. This part of stateful inspection prevents port scanning and reduces that chance of a hacker gaining unauthorized access to a network.