Abstract: Embodiments described herein provide a dual-line FIFO structure without the use of any multiplexer. Instead, the dual-line FIFO described herein uses a selectively transparent latch and a flip-flop serially connected to the latch, such that the combination of the serially connected latch and the flip-flop can temporarily store up to two data units at two clock cycles.

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 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 to determine whether to allow or deny the packet.

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.