Definition - What does Stateful Inspection mean?
Stateful inspection is a type of packet filtering that helps to control how data packets move through a firewall.
This type of assessment is also called dynamic packet filtering, and represents a progression in how systems monitor packets in order to prevent dangerous incoming traffic from getting through firewall technologies.
Techopedia explains Stateful Inspection
Experts contrast stateful inspection or dynamic packet filtering with a prior method called static packet filtering. In static packet filtering, the system only looked at packet headers and IP addresses. Static packet filtering did not address application state information and could not determine whether a packet was an initial message or a response.
In the 1990s, some firms began using dynamic packet filtering. Here, the initial outgoing packets are tracked, in order to create a specialized response access that ensures the response is coming from the host and particular port where the original message was sent. This stricter method for packet filtering ensures a safer environment for firewall-equipped systems.