Denial-of-service-attack protecting method, denial-of-service attack protecting system, denial-of-service attack protecting device, repeater, denial-of-service attack protecting program, and program for repeater

A denial-of-service attack protecting system that protects a communication device against a denial of service attack using a gate device connected to the communication device or a repeater device connected to the gate device and that is a part of a network, wherein the gate device comprises:

• an authorized address information acquiring unit that acquires authorized address information indicative of a source address of a non-attacking packet transmitted by an authorized device on the network;
• a normal condition information generating unit that generates normal condition information indicative of conditions for the non-attacking packet, based on the authorized address information acquired by the authorized address information acquiring unit;
• and
• a packet controlling unit that controls passage of packets on the network, wherein the packet controlling unit restricts passage of an attacking packet that do not satisfy the conditions in the normal condition information while allowing passage of a non-attacking packet that satisfies the conditions in the normal condition information.

A denial-of-service attack protecting system that protects a communication device against a denial of service attack using a gate device connected to the communication device or a repeater device connected to the gate device and that is a part of a network, wherein the gate device comprises:

• an attack detecting unit that detects an attack on the communication device by an attacking packet;
• an authorized address information receiving unit that, upon the gate device detecting the attack, receives authorized address information from the repeater device, the authorized address information indicative of a source address of a non-attacking packet which is received from an authorized device on the network;
• and
• a passage controlling unit that controls passage of a packet based on normal condition information indicative of conditions for the non-attacking packet, wherein the normal condition information is generated from the authorized address information received by the authorized address information receiving unit.

A gate device that protects a communication device against a denial of service attack, the gate device being connected to the communication device or a repeater device connected to the gate device and that is a part of a network, comprising:

• an authorized address information acquiring unit that acquires authorized address information indicative of a source address of a non-attacking packet transmitted by an authorized device on the network;
• a normal condition information generating unit that generates normal condition information indicative of conditions for the non-attacking packet, based on the authorized address information acquired by the authorized address information acquiring unit;
• and
• a packet controlling unit that controls passage of packets on the network, wherein the packet controlling unit restricts passage of an attacking packet that do not satisfy the conditions in the normal condition information while allowing passage of a non-attacking packet that satisfies the conditions in the normal condition information.

A gate device that protects a communication device against a denial of service attack, the gate device being connected to the communication device or a repeater device connected to the gate device and that is a part of a network, comprising:

• an attack detecting unit that detects an attack on the communication device by the attacking packet;
• an authorized address information receiving unit that, upon the gate device detecting the attack, receives authorized address information from the repeater device, the authorized address information indicative of a source address of a non-attacking packet which is received from an authorized device on the network;
• and
• a passage controlling unit that controls passage of a packet based on normal condition information indicative of conditions for the non-attacking packet, wherein the normal condition information is generated from the authorized address information received by the authorized address information receiving unit.

A computer-readable recording medium that stores therein a computer program that causes a gate device to protect a communication device against a denial of service attack, the gate device being connected to the communication device or a repeater device connected to the gate device and that is a part of a network, the computer program causing the gate device to execute:

• acquiring authorized address information indicative of a source address of a non-attacking packet transmitted by an authorized device on the network;
• generating normal condition information indicative of conditions for the non-attacking packet, based on the authorized address information acquired by the authorized address information acquiring unit;
• and
• controlling passage of packets on the network, wherein the packet controlling unit restricts passage of an attacking packet that do not satisfy the conditions in the normal condition information while allowing passage of a non-attacking packet that satisfies the conditions in the normal condition information.

A computer-readable recording medium that stores therein a computer program that causes a gate device to protect a communication device against a denial of service attack, the gate device being connected to the communication device or a repeater device connected to the gate device and that is a part of a network, the computer program causing the gate device to execute:

• detecting detects an attack on the communication device by the attacking packet;
• receiving, upon detecting the attack at the detecting, authorized address information from the repeater device, the authorized address information indicative of a source address of a non-attacking packet which is received from an authorized device on the network;
• and
• controlling passage of a packet based on normal condition information indicative of conditions for the non-attacking packet, wherein the normal condition information is generated from the authorized address information received by the authorized address information receiving unit.