(also stateful packet inspection, dynamic packet filtering)
A stateful inspection is a type of firewall technology frequently used in computing. Stateful firewalls use a stateful inspection to monitor all the active connections on the network and decide which network packets can go through the firewall and which cannot. Another type of firewall technology that is closely related to stateful inspection is stateless or packet filtering. And out of the two, stateful inspection is the more advanced option and allows you to block unwanted and suspicious network packets with 100% certainty. A stateful inspection uses predefined rules to decide which network packets can go through the firewall and which cannot.
See also: firewall, data packet