Implementation algorithm of UDP filtering on stateful-inspection firewall
Lei Gong-wu · 2004
The principle of UDP(User Datagram Protocol) packets inspection on stateful-inspection firewall is analyzed; and a model, which could effectively prevent the DoS attacks, and its implementation algorithm are presented. With the method of dynamic configuring the life cycle for UDP virtual connections, the firewall can avoid exhausting its state-table resource. A hash table has been employed in the algorithm to manage UDP virtual connections, of which the average time complexity is controlled at Ο(λ); the space complexity is controlled at Ο(n); and in situation of less collisions, the time complexity is Ο (1), which does not varied with the number of connections.