Communication system, router, method of communication, method of routing, and computer program product

Abstract

A communication system includes a server and a router which are both connected to a first network. The server grants to a response packet destined for an anycast address sent from a communication apparatus connected to a second network, anycast address option information indicating that an anycast address of a sender of the response packet, puts a signature field for a setting of an electronic signature in the response packet; and transmits to the communication apparatus the response packet. The router receives the response packet, validates whether the response packet is sent from a legitimate server based on the anycast address option information if the response packet includes the anycast address option information. The router also sets an electronic signature based on information related with the response packet in the signature field if the response packet is sent from the legitimate server, and transmits the response packet.

1 .- 19 . (canceled) 
   
   
       20 . A communication method, comprising:
 in a server, connected to a first network, granting to a response packet that is a response to a packet which is destined for an anycast address and which is sent from a communication apparatus connected to a second network different from the first network, anycast address option information which indicates that an anycast address is allocated to a sender of the response packet;   in the server, putting a signature field for a setting of an electronic signature in the response packet;   in the server, transmitting to the communication apparatus the response packet in which the anycast address option information has been set and the signature field has been put;   in a router connected to the first network, receiving the response packet sent from the server to the communication apparatus;   in the router, validating whether the response packet is sent from a legitimate server based on the anycast address option information if the response packet includes the anycast address option information;   in the router, setting an electronic signature based on information related with the response packet in the signature field put in the response packet, when the response packet is validated to be sent from the legitimate server;   in the router, transferring the response packet in which the electronic signature has been set;   in the server, the field putting unit further puts a time field in the response packet; and   in the router, setting a time of transfer of the response packet in the time field of the response packet.   
   
   
       21 . The communication method according to  claim 20 , further including:
 in the router, setting the electronic signature using a predetermined key information for the anycast address option information in the signature field of the response packet.   
   
   
       22 . The communication system according to  claim 20 , further including:
 in the server, putting the signature field and the time field in a field of the anycast address option information.   
   
   
       23 . A communication method, comprising:
 in a server connected to a first network, granting to a response packet that is a response to a packet which is destined for an anycast address and which is sent from a communication apparatus connected to a second network different from the first network, anycast address option information which indicates that an anycast address is allocated to a sender of the response packet;   in the server, putting a signature field for a setting of an electronic signature in the response packet;   in the server, transmitting to the communication apparatus the response packet in which the anycast address option information has been set and the signature field has been put;   in a router connected to the first network receiving the response packet sent from the server to the communication apparatus;   in the router, validating whether the response packet is sent from a legitimate server based on the anycast address option information if the response packet includes the anycast address option information;   in the router, setting an electronic signature based on information related with the response packet in the signature field put in the response packet, when the response packet is validated to be sent from the legitimate server;   in the router, transferring the response packet in which the electronic signature has been set;   in the server, setting an anycast address allocated to the server in the anycast address option information of the response packet;   in the router, storing anycast address correspondence information which includes a unicast address of the server that is present in the first network and the anycast address allocated to the server in association with each other; and   in the router, when the response packet includes the anycast address option information, determining whether the anycast address of the anycast address option information matches with a unicast address corresponding to the anycast address registered in the anycast address correspondence information, and when the anycast address matches with the unicast address, determining that the response packet is sent from a legitimate server.   
   
   
       24 . The communication method according to  claim 23 , further including:
 in the router, setting the electronic signature using a predetermined key information for the anycast address option information in the signature field of the response packet.   
   
   
       25 . The communication system according to  claim 23 , further including:
 in the server, putting the signature field and the time field in a field of the anycast address option information.   
   
   
       26 . A computer program product having a computer readable medium including programmed instructions, wherein the instructions, when executed by a computer, cause the computer to perform:
 in a server, connected to a first network, granting to a response packet that is a response to a packet which is destined for an anycast address and which is sent from a communication apparatus connected to a second network different from the first network, anycast address option information which indicates that an anycast address is allocated to a sender of the response packet;   in the server, putting a signature field for a setting of an electronic signature in the response packet;   in the server, transmitting to the communication apparatus the response packet in which the anycast address option information has been set and the signature field has been put;   in a router connected to the first network, receiving the response packet sent from the server to the communication apparatus;   in the router, validating whether the response packet is sent from a legitimate server based on the anycast address option information if the response packet includes the anycast address option information;   in the router, setting an electronic signature based on information related with the response packet in the signature field put in the response packet, when the response packet is validated to be sent from the legitimate server;   in the router, transferring the response packet in which the electronic signature has been set;   in the server, the field putting unit further puts a time field in the response packet; and   in the router, setting a time of transfer of the response packet in the time field of the response packet.   
   
   
       27 . The computer program product according to  claim 26 , the instructions further causing the computer to perform:
 in the router, setting the electronic signature using a predetermined key information for the anycast address option information in the signature field of the response packet.   
   
   
       28 . The computer program product according to  claim 26 , the instructions further causing the computer to perform:
 in the server, putting the signature field and the time field in a field of the anycast address option information.   
   
   
       29 . A computer program product having a computer readable medium including programmed instructions, wherein the instructions, when executed by a computer, cause the computer to perform:
 in a server connected to a first network, granting to a response packet that is a response to a packet which is destined for an anycast address and which is sent from a communication apparatus connected to a second network different from the first network, anycast address option information which indicates that an anycast address is allocated to a sender of the response packet;   in the server, putting a signature field for a setting of an electronic signature in the response packet;   in the server, transmitting to the communication apparatus the response packet in which the anycast address option information has been set and the signature field has been put;   in a router connected to the first network receiving the response packet sent from the server to the communication apparatus;   in the router, validating whether the response packet is sent from a legitimate server based on the anycast address option information if the response packet includes the anycast address option information;   in the router, setting an electronic signature based on information related with the response packet in the signature field put in the response packet, when the response packet is validated to be sent from the legitimate server;   in the router, transferring the response packet in which the electronic signature has been set;   in the server, setting an anycast address allocated to the server in the anycast address option information of the response packet;   in the router, storing anycast address correspondence information which includes a unicast address of the server that is present in the first network and the anycast address allocated to the server in association with each other; and   in the router, when the response packet includes the anycast address option information, determining whether the anycast address of the anycast address option information matches with a unicast address corresponding to the anycast address registered in the anycast address correspondence information, and when the anycast address matches with the unicast address, determining that the response packet is sent from a legitimate server.   
   
   
       30 . The computer program product according to  claim 29 , the instructions further causing the computer to perform:
 in the router, setting the electronic signature using a predetermined key information for the anycast address option information in the signature field of the response packet.   
   
   
       31 . The computer program product according to  claim 29 , the instructions further causing the computer to perform:
 in the server, putting the signature field and the time field in a field of the anycast address option information.