Stateful Inspection, a technology developed and patented by Check Point, incorporates layer 4 awareness into the standard packet-filter firewall architecture. Stateful Inspection examines a packet header, and also the contents of the packet up through the application layer, to determine more about the packet than just source and destination. The state of the connection is monitored, and a state table is compiled. As a result, filtering includes context that has been established by previous packets that have passed through the firewall.