Abstract: A novel and useful virtual private network (VPN) mechanism and related security association processor for maintaining the necessary security related parameters to perform security functions such as encryption, decryption and authentication. A security association database (SAD) and related circuitry is adapted to provide the necessary parameters to implement the IPSec group of security specifications for encryption/decryption and authentication. Each security association (SA) entry in the database comprises all the parameters that are necessary to receive and transmit VPN packets according to the IPSec specification.

Abstract: A novel and useful dynamic packet filter that can be incorporated in a hardware based firewall suitable for use in portable computing devices such as cellular telephones and wireless connected PDAs that are adapted to connect to the Internet. The invention performs dynamic packet filtering on packets received over an input packet stream. The dynamic filter checks dynamic protocol behavior using information extracted from the received packet. Sessions are created and stored in a session database to track the state of communications between the source and destination. Recognition of a session is accelerated by use of a hash table to quickly determine the corresponding session record in the session database. Session related data is read from the session database and the received packet is checked against a set of rules for determination of whether to allow or deny the packet.