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

A packet filtering apparatus for selectively outputting packets out of a plurality of inputted packets, the packet filtering apparatus comprising:

• storage means for storing a plurality of type 2 conditions, each type 2 condition being composed of a plurality of type 1 conditions, each type 1 condition being specified by
• (1) a partial data position that indicates a position of a data part of a packet,
• (2) comparison data to which the data part is to be compared, and
• (3) a comparison criterion for comparing the data part and comparison data,
• and the type 2 conditions being composed such that the comparison criteria in the type 1 conditions differ, either between the type 1 conditions in a same type 2 condition or between the type 1 conditions in different type 2 conditions;
• selecting means for selecting one type 2 condition out of the stored plurality of type 2 conditions:
• and
• filtering means for comparing, by applying each type 1 condition in the selected type 2 condition one at a time, the data part of one inputted packet with the comparison data according to the comparison criterion and for selectively allowing the packet to pass only if a comparison result “true” is given for every type 1 condition in the selected type 2 condition.

A set-top box including a packet filtering unit for selectively outputting packets out of a plurality of inputted packets, the packet filtering unit comprising:

• storage means for storing a plurality of conditions, each condition being specified by
• (1) a partial data position that indicates a position of a data part of a packet,
• (2) comparison data to which the data part is to be compared, and
• (3) a comparison criterion for comparing the data part and comparison data,
• wherein different conditions include different comparison criteria;
• selecting means for selecting one of the stored plurality of conditions:
• and
• filtering means for comparing, based on the selected condition, the data part of one inputted packet with the comparison data according to the comparison criterion and for selectively allowing the packet to pass depending on a comparison result.

A set-top box including a packet filtering unit for selectively outputting packets out of a plurality of inputted packets, the packet filtering unit comprising:

• storage means for storing a plurality of conditions, each condition being specified by
• (1) a partial data position that indicates a position of a data part of a packet,
• (2) comparison data to which the data part is to be compared, and
• (3) a comparison criterion for comparing the data part and comparison data,
• wherein different conditions include different comparison criteria, one of the different comparison criteria being that the data part is not equal to the comparison data;
• selecting means for selecting one of the stored plurality of conditions;
• and
• filtering means for comparing, based on the selected condition, the data part of one inputted packet with the comparison data according to the comparison criterion and for selectively allowing the packet to pass depending on a comparison result.

A set-top box including a packet filtering unit for selectively outputting packets out of a plurality of inputted packets, the packet filtering unit comprising:

• storage means for storing a plurality of type 2 conditions, each type 2 condition being composed of a plurality of type 1 conditions, each type 1 condition being specified by
• (1) a partial data position that indicates a position of a data part of a packet,
• (2) comparison data to which the data part is to be compared, and
• (3) a comparison criterion for comparing the data part and comparison data,
• and the type 2 conditions being composed such that the comparison criteria in the type 1 conditions differ, either between the type 1 conditions in a same type 2 condition or between the type 1 conditions in different type 2 conditions;
• selecting means for selecting one type 2 condition out of the stored plurality of type 2 conditions;
• and
• filtering means for comparing, by applying each type 1 condition in the selected type 2 condition one at a time, the data part of one inputted packet with the comparison data in the applied type 1 condition according to the comparison criterion in the applied type 1 condition and for selectively allowing the packet to pass only if a comparison result “true” is given for every type 1 condition in the selected type 2 condition.

A packet filtering method for selectively outputting packets out of a plurality of inputted packets, the packet filtering method comprising:

• a storage step for storing a plurality of conditions, each condition being specified by
• (1) a partial data position that indicates a position of a data part of a packet,
• (2) comparison data to which the data part is to be compared, and
• (3) a comparison criterion for comparing the data part and comparison data,
• wherein different conditions include different comparison criteria;
• a selecting step for selecting one of the stored plurality of conditions;
• and
• a control step for comparing, based on the selected condition, the data part of one inputted packet with the comparison data according to the comparison criterion and for selectively allowing the packet to pass depending on a comparison result.