Packet filtering apparatus that applies a plurality of filtering conditions including different comparison criteria to a single packet

摘要

A packet filtering apparatus selectively outputs packets among a plurality of inputted packets. A plurality of conditions are stored, with each condition being specified by a partial data position that indicates a position of a data part of a packet, comparison data to which the data part is to be compared, and a comparison criterion for comparing the data part and comparison data. Different conditions contain different comparison criteria. When filtering packets, a condition in one of the stored conditions is selected, and a data part of an inputted packet is compared with the comparison data of the selected condition according to the comparison criterion in the selected condition. Packets are selectively outputted depending on the result of the comparison.