COMMUNICATION APPARATUS, COMMUNICATION METHOD AND COMMUNICATION SYSTEM
First Claim
1. A communication apparatus which is connected to a server via a first relay apparatus having a NAT (Network Address Translation) function, comprising:
- an address information check request transmitting unit for transmitting a plurality of address information check request packets whose source port numbers are set to be local port numbers different from each other of the communication apparatus and whose destination port numbers are set to be the same port number as that of each other, the same port number being a port number of the server, to the server, on a one-by-one basis;
a communication preparation request transmitting unit for transmitting a communication preparation packet whose source port number is set to be the same port number as the source port number of any of the plurality of address information check request packets, to a destination different from the server, after the address information check request transmitting unit transmits the first address information check request packet and before the address information check request transmitting unit transmits the final address information check request packet; and
an address information receiving unit for receiving the same number of address information check response packets as the number of the address information check request packets, the address information check response packets being returned from the server in response to the address information check request packets, and including relay port numbers translated from the source port numbers of the address information check request packets in the first relay apparatus.
1 Assignment
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Accused Products
Abstract
A communication apparatus (10) transmits to a server (001) three address information, check requests 1 to 3 whose destination port numbers are set to be [SP1] and whose source port numbers are set to be respective [LP1] to [LP3] different from each other. The communication apparatus (10) also transmits a P2P communication preparation packet whose source port number is set to be one of [LP1] to [LP3], to a destination different from the server (001), between the address information check requests 1 and 3. The communication apparatus (10) determines the NAT characteristic of a router (101) based on port numbers [GP11], [GP12] and [GP14] of the router (101) notified of by address information check responses 1 to 3.
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Citations
14 Claims
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1. A communication apparatus which is connected to a server via a first relay apparatus having a NAT (Network Address Translation) function, comprising:
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an address information check request transmitting unit for transmitting a plurality of address information check request packets whose source port numbers are set to be local port numbers different from each other of the communication apparatus and whose destination port numbers are set to be the same port number as that of each other, the same port number being a port number of the server, to the server, on a one-by-one basis; a communication preparation request transmitting unit for transmitting a communication preparation packet whose source port number is set to be the same port number as the source port number of any of the plurality of address information check request packets, to a destination different from the server, after the address information check request transmitting unit transmits the first address information check request packet and before the address information check request transmitting unit transmits the final address information check request packet; and an address information receiving unit for receiving the same number of address information check response packets as the number of the address information check request packets, the address information check response packets being returned from the server in response to the address information check request packets, and including relay port numbers translated from the source port numbers of the address information check request packets in the first relay apparatus. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A communication method for allowing a communication apparatus which is connected to a server via a first relay apparatus having a NAT (Network Address Translation) function, to communicate with the server to determine a NAT characteristic of the first relay apparatus, the method comprising:
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an address information check request transmitting step of transmitting a plurality of address information check request packets whose source port numbers are set to be local port numbers different from each other of the communication apparatus and whose destination port numbers are set to be the same port number as that of each other, the same port number being a port number of the server, to the server, on a one-by-one basis; a communication preparation request transmitting step of transmitting a communication preparation packet whose source port number is set to be the same port number as the source port number of any of the plurality of address information check request packets, to a destination different from the server, after the first address information check request packet is transmitted and before the final address information check request packet is transmitted in the address information check request transmitting step; an address information receiving step of receiving the same number of address information check response packets as the number of the address information check request packets, the address information check response packets being returned from the server in response to the address information check request packets, and including relay port numbers translated from the source port numbers of the address information check request packets in the first relay apparatus; and a relay characteristic determining step of determining the NAT characteristic of the first relay apparatus based on the relay port numbers included in the respective address information check response packets received in the address information receiving step.
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13. A communication system comprising:
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a server; a first relay apparatus having a NAT (Network Address Translation) function; a second relay apparatus having the NAT function; a first communication apparatus connected via the first relay apparatus to the server; and a second communication apparatus connected via the second relay apparatus to the server, wherein each of the first and second communication apparatuses comprising; an address information check request transmitting unit for transmitting a plurality of address information check request packets whose source port numbers are set to be local port numbers different from each other of the each of the communication apparatuses and whose destination port numbers are set to be the same port number as that of each other, the same port number being a port number of the server, to the server, on a one-by-one basis; a communication preparation request transmitting unit for transmitting a communication preparation packet, whose source port number is set to be the same port number as the source port number of any of the plurality of address information check request packets, to a destination different from the server, after the address information check request transmitting unit transmits the first address information check request packet and before the address information check request transmitting unit transmits the final address information check request packet; an address information receiving unit for receiving the same number of address information check response packets as the number of the address information check request packets, the address information check response packets being returned from the server in response to the address information check request packets, and including relay port numbers translated from the source port numbers of the address information check request packets in the relay apparatus connected to the each of the communication apparatuses; and a relay characteristic determining unit for determining a NAT characteristic of the first relay apparatus based on the relay port numbers included in the respective address information check response packets received by the address information receiving unit, and the server comprises; an address information checking unit for extracting the relay port numbers included in the address information check request packets transmitted from the first and second respective communication apparatuses; and an address information transmitting unit for transmitting address information check request response packets including the extracted relay port numbers.
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14. A communication system comprising:
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a server; a first relay apparatus having a NAT (Network Address Translation) function; a second relay apparatus having the NAT function; a first communication apparatus connected via the first relay apparatus to the server; and a second communication apparatus connected via the second relay apparatus to the server, wherein each of the first and second communication apparatuses comprising; an address information check request transmitting unit for transmitting a plurality of address information check request packets whose source port numbers are set to be local port numbers different from each other of the each of the communication apparatuses and whose destination port numbers are set to be the same port number as that of each other, the same port number being a port number of the server, to the server, on a one-by-one basis; and a communication preparation request transmitting unit for transmitting a communication preparation packet whose source port number is set to be the same port number as the source port number of any of the plurality of address information check request packets, to a destination different from the server, after the address information check request transmitting unit transmits the first address information check request packet and before the address information check request transmitting unit transmits the final address information check request packet, and the server comprises an address information checking unit for determining NAT characteristics of the first and second respective relay apparatuses based on relay port numbers translated from the source port numbers of the address information check request packets in the first and second respective relay apparatuses.
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Specification