JP2012019361A - Communication device, server device, communication system, communicating method, and integrated circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication device for determining an NAT type of each of NAT devices when the NAT devices are connected in multiple stages.SOLUTION: A terminal device 405a includes: a determination cooperating request receiving portion 652 receiving a determination cooperating request for requesting cooperation in determining an NAT type of an NAT device 404b transmitted from an external server 401; a port forward instructing portion 653 instructing an NAT device 404a to execute port forward when receiving the determination cooperating request; a port information transmitting portion 654 transmitting port information including a port number used for the port forward to the external server 401; a determination packet transmitting/receiving portion 655 receiving a determination packet for determining the NAT type transmitted from the terminal device 405b connected to the NAT device 404b received the port information from the server device; and a determination information transmitting portion 656 transmitting determination information which is obtained on the basis of the received determination packet, and used for determining the NAT type.

Description

  The present invention relates to a communication apparatus and a communication system having a function of determining a type of an address conversion method in a network relay apparatus having a NAT (Network Address Translation) function.

  In a communication method using the conventional Internet technology, a global IPv4 address (hereinafter referred to as a global IP address), which is an address uniquely determined for each device, is assigned to a device directly connected to the Internet.

  However, the number of global IP addresses is limited, and in particular for home Internet connection services, only one global IP address is often assigned per service contract. That is, only one device can be directly connected to the Internet.

  Therefore, a private IP address and a router having a NAT function (hereinafter referred to as “NAT device”) are provided so that a plurality of devices exceeding the number of usable global addresses can simultaneously communicate with devices on the Internet. The network configuration used is widely used.

  A private IP address cannot be used as a source IP address or a destination IP address of a packet on the global Internet, but is intended for use in a closed (private) network such as debugging of a network device and an enterprise. IP address.

  The NAT device is a network relay device having a NAT function for performing mutual conversion between a global IP address and a private IP address.

  In the present specification, claims, and drawings, “NAT” is used to include NAPT (Network Address Port Translation) that also performs port translation.

  In a network configuration using a private IP address and a NAT device, as long as communication is started from a device under the NAT device, the device can directly communicate with other devices on the Internet.

  In addition, when starting communication from a terminal device on the Internet and directly communicating with a device under the NAT device, a method using a UPnP (Universal Plug and Play) compatible NAT device, and Non-Patent Document 1 A method using STUN (Simple Traversal of UDP through NATs) is used.

  According to an algorithm defined in RFC (Request For Comment) 3489 issued by IETF (Internet Engineering Task Force), NAT types are classified as follows.

  That is, the NAT type is classified into four types: a full cone type, a restricted cone type (Restricted Cone), a port restricted cone type (Port Restricted Cone), and a symmetric type (Symmetric). FIG. 1 summarizes the characteristics of the four NAT types.

  Here, an example of a NAT type determination flow according to the algorithm defined in RFC3489 is shown in FIG. 2, and an outline of a transmission test (4 types of I, I ′, II, and III) executed at the time of the determination is shown. Shown in FIGS. 3A-3D.

  As shown in FIG. 2, first, the terminal device that determines the NAT type executes the transmission test I (S101). As shown in FIG. 3A, the transmission test I includes an IP address a and a port number p (hereinafter referred to as a combination of an IP address and a port number) of the STUN server A that is the first destination from the terminal device via the NAT device. This is done by sending a Binding request to address (a, p) ”.

  In this case, the CHANGE-REQUEST (source information change request) attribute that requests the STUN server A to change the source IP address and port number of the Binding response is not specified.

  Subsequently, the terminal device determines whether or not there is a response from the STUN server A (S102). If there is no response (N in S102), “(1) there is a firewall that blocks UDP. Is determined.

  On the other hand, when the terminal device receives the Binding response from the STUN server A (Y in S102), the IP address added to the Binding response as the MAPPED-ADDRESS (mapping address) attribute (that is, received by the STUN server A) It is determined whether or not the binding request transmission source IP address is the same as the private IP address of the terminal device (S103).

  Therefore, if the IP addresses are the same (Y in S103), the terminal device determines that it is not under the control of the NAT device, and further executes a transmission test II (S104).

  In this transmission test II, as shown in FIG. 3C, a Binding request is transmitted to the same destination (address (a, p)) as in the transmission test I, but the STUN server A responds with the CHANGE-REQUEST attribute. As the transmission source, an IP address and a port number (address (b, q)) different from the receiving destination of the Binding request are set.

  Therefore, the terminal device determines whether or not there is a response having the address (b, q) as a transmission source, that is, a response from the STUN server B (S105), and if there is no response (N in S105). , “(2) There is a firewall that does not perform address translation but blocks UDP like a symmetric NAT device”.

  On the other hand, when a Binding response from the STUN server B is received (Y in S105), it is determined that the communication is “(3) Open Internet without access restriction”.

  On the other hand, when the IP addresses are not the same in S103 (the terminal device is under the control of the NAT device) (N in S103), the terminal device executes a transmission test II similar to S104 (S106), and the STUN server B It is determined whether or not there is a response (S107).

  Therefore, when there is a response (Y in S107), the response is returned from an IP address and port number (address (b, q)) different from the binding request receiving destination as instructed by the terminal device. Means. Therefore, the terminal device determines that the NAT type of the NAT device is “(4) Full cone type”.

  On the other hand, when there is no response (N in S107), the terminal device executes a transmission test I ′ (S108). As shown in FIG. 3B, the transmission test I ′ is performed by transmitting a Binding request from the terminal device to the address (b, q) of the STUN server B that is the second destination via the NAT device. . In this case, like the transmission test I, the CHANGE-REQUEST attribute is not specified.

  Next, when the terminal device receives the Binding response from the STUN server B in response to the Binding request of the transmission test I ′, the IP address and port number added as the MAPPED-ADDRESS attribute (that is, the Binding received by the STUN server B) It is determined whether or not the request source IP address and port number are the same as the IP address and port number added as the MAPPED-ADDRESS attribute in the previous transmission test I (S109).

  Therefore, if these two sets of IP addresses and port numbers are not the same (N in S109), the port number of the source NAT device may be changed when a Binding request is sent to the IP address of a different STUN server. Recognize. Therefore, the terminal device determines that the NAT type of the NAT device is “(5) Symmetric”.

  On the other hand, if the two sets of IP addresses and port numbers are the same in S109 (Y in S109), then the terminal device executes transmission test III (S110), and whether or not there is a response from STUN server A Is determined (S111).

  In the transmission test III, as shown in FIG. 3D, a Binding request is transmitted to the same destination (address (a, p)) as the transmission test I. However, in the transmission test III, in the CHANGE-REQUEST attribute, a port number (address (a, q)) different from the binding request reception destination is set as the transmission source when the STUN server A responds.

  Therefore, when there is a response (Y in S111), even if the port numbers are different, the response is returned if the IP address is the same, and therefore the terminal device sets the NAT type of the NAT device to “(6 ) Restricted Cone ”.

  On the other hand, when there is no response (N in S111), since the response from the same IP address and different port number is not returned, the terminal device sets the NAT type of the NAT device to “(7) cone with port restriction”. Type (Port Restricted Cone) ”.

  As described above, the terminal devices under the NAT apparatus can determine the NAT type of the NAT apparatus by appropriately executing the transmission tests I to III and the test I ′. Other terminal devices on the Internet select a NAT traversal method suitable for the NAT type obtained by using the NAT type determination method described above, and perform NAT traversal to establish a connection with the terminal device under the NAT device. Communication can be started.

  On the other hand, Patent Document 1 discloses a technique for selecting a NAT traversal method and realizing NAT traversal by using a NAT type determination method using STUN and UPnP in combination. Specifically, in Patent Document 1, in addition to the NAT type determination result information of the NAT device, UPnP-compatible presence / absence information is exchanged between the terminals via the external server, so that the NAT device is exchanged between the external server and the terminal device. In a multi-stage NAT environment in which two or more exist, a method for performing NAT traversal is described.

JP 2008-236278 A

J. et al. Rosenberg, et al. “RFC 3490, STUN-Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translats (NATs), [online], [3], [online]. ietf. org / rfc / rfc3389. txt>

  However, according to the above-described determination method using STUN, it is possible to determine the NAT type only when there is only one NAT device 202 between the STUN server 201 and the terminal device 203 as shown in FIG. 4A. That is, as shown in FIG. 4B, when two or more NAT devices are connected between the STUN server 204 and the terminal device 207 (in FIG. 4B, the NAT device 205 and the NAT device 206), a plurality of these NAT devices are connected. There is a problem that the NAT type of the NAT device cannot be individually determined.

  Specifically, in the network configuration shown in FIG. 4B, when the NAT type determination method using the STUN is used, the NAT type is determined using two NAT devices as one NAT device. As a result, of the NAT types of the NAT device 205 and the NAT device 206, the more restrictive NAT type is obtained as a determination result (see FIG. 5), and the individual NAT types of these NAT devices cannot be obtained. Had.

  For example, it is assumed that the NAT type of the NAT device 205 in FIG. 4B is a complete cone type and the NAT type of the NAT device 206 is a symmetric type. In this case, since the symmetric type is more restrictive than the complete cone type, the result of the NAT type determination using the STUN is “symmetric type”.

  The same applies to the case where the NAT type of the NAT device 205 is a symmetric type and the NAT type of the NAT device 206 is a complete cone type, and the determination result is “symmetric type”.

  The technique described in Patent Document 1 also has a similar problem. When NAT devices are connected in multiple stages, the NAT type of each of a plurality of NAT devices cannot be individually determined.

  Here, as a countermeasure for the global IPv4 address depletion problem, a NAT device at the ISP level (hereinafter referred to as “ISP-NAT device”) is installed in a facility managed by an ISP (Internet Service Provider) as shown in FIG. It is considered to install a device 302 or similar and assign a private IPv4 address to a service user. As a result, it is conceivable that the multi-stage NAT environment increases, and communication between terminals under each of a plurality of NAT devices connected to the same ISP-NAT device may occur.

  For example, in the case of the network configuration shown in FIG. 6, it is conceivable that communication is performed between the terminal device 304 under the NAT device 303 and the terminal device 306 under the NAT device 305.

  In this case, the NAT devices that should be exceeded in the communication between the terminal device 304 and the terminal device 306 are the NAT device 303 and the NAT device 305. In such a communication environment, when the conventional NAT type determination method is performed using the STUN server 301, the NAT type of each of the NAT device 303 and the NAT device 305 cannot be determined, and an appropriate NAT traversal method cannot be selected. The problem can occur.

  The present invention solves the above-described conventional problems, and a communication device, a server device, a communication system, a communication method, and an integrated circuit for determining the NAT type of each NAT device when NAT devices are connected in multiple stages The purpose is to provide.

  In order to solve the above-described conventional problems, a communication device according to an aspect of the present invention includes an upper NAT (Network Address Translation) device connected to the Internet, a first lower NAT device connected to the upper NAT device, and The communication device communicates with the server device connected to the Internet via the network, and cooperates in determining the NAT type of the second lower NAT device connected to the upper NAT device transmitted from the server device. A determination cooperation request receiving unit that receives a determination cooperation request to be requested; and when the determination cooperation request reception unit receives the determination cooperation request, the packet received by the first lower NAT device is transferred to the communication device. Port forward command unit for commanding the first lower NAT device to execute port forward of A port information transmitting unit for transmitting port information including a port number used for port forwarding to the server device, and a request terminal connected to the second lower NAT device, and receiving the port information from the server device A determination packet receiving unit that receives the determination packet for determining the NAT type transmitted from the requesting terminal, and a determination packet received based on the determination packet received by the determination packet receiving unit. A determination information transmission unit that transmits the determination information to be transmitted.

  According to this configuration, when the communication device is requested to determine the NAT type, the first lower NAT device immediately above the communication device is configured to transfer the determination packet from the requesting terminal requesting the NAT type determination. Is made. Further, since the port information which is the setting information is notified to the requesting terminal via the server device, the requesting terminal passes the determination packet for determining the NAT type through the first lower NAT device and the communication device. Can be reached.

  When the communication device responds to the determination packet received in this way, the response is communication in the direction from the internal network side to the external network side as the first lower NAT device. It is not blocked by the lower NAT device. Therefore, the response reaches the second lower NAT device immediately above the requesting terminal.

  In addition, the determination information transmission unit transmits determination information based on the determination packet received by the communication apparatus. Therefore, it is possible to cause a device (for example, a server device or a requesting terminal) that receives this determination information to appropriately determine the NAT type.

  As described above, the communication apparatus according to this aspect performs the operation as the cooperation terminal that cooperates with the determination of the NAT type, thereby enabling the determination of the individual NAT type in the multi-stage NAT environment.

  The communication device according to an aspect of the present invention further connects the IP address and port number of the second lower NAT device indicated in the determination packet received by the determination packet receiver to the upper NAT device. A determination target NAT information notification unit that notifies another communication device connected to the third lower NAT device via the third lower NAT device may be provided.

  According to this configuration, other communication devices are notified of destination information such as the IP address of the NAT device on the requesting terminal side. Therefore, the other communication device can be operated as a cooperation terminal.

  A server device according to an aspect of the present invention includes a first NAT device connected to the Internet, an upper NAT (Network Address Translation) device connected to the Internet, and a first lower NAT device connected to the upper NAT device. A server device that communicates with one communication device and communicates with a second communication device via the Internet, the upper NAT device, and a second lower NAT device connected to the upper NAT device, Connection environment information indicating a connection environment of the first communication device, the connection environment information receiving unit receiving connection environment information including information on the first lower NAT device, and transmitted from the second communication device, A determination request receiving unit for receiving a determination request for requesting determination of the NAT type of the second lower NAT device; and the determination request receiving unit When the determination request is received, the cooperation terminal selection unit that selects the first communication device that satisfies a predetermined standard as a cooperation terminal by referring to the connection environment information received by the connection environment information reception unit; A determination cooperation request transmission unit that transmits a determination cooperation request for requesting cooperation of determination of the NAT type to the first communication device selected by the cooperation terminal selection unit, and the first communication that has received the determination cooperation request Port information transmitted from a device, the port information including a port number used for port forwarding for transferring a packet received by the first lower NAT device to the first communication device, and receiving A port information transmission / reception unit for transmitting the port information thus transmitted to the second communication device.

  According to this configuration, when receiving the NAT type determination request, the server device according to the present aspect can request the NAT type determination cooperation from the communication device selected as the cooperation terminal. In addition, it is possible to receive port information for making a packet reach the cooperation terminal beyond the NAT device immediately above the cooperation terminal from the cooperation terminal that requested the cooperation, and send a determination request of the NAT type to this port information. Can be notified to the requested terminal.

  Therefore, the requesting terminal that has received the notification of the port information can cause the cooperating terminal to receive the determination packet, and can appropriately perform a test for determining the NAT type using the cooperating terminal.

  As described above, the server device according to this aspect provides the information necessary for communication with the cooperation terminal cooperating with this determination to the requesting terminal requesting the determination of the NAT type, thereby enabling the individual NAT in the multi-stage NAT environment. The type can be determined.

  The server device according to an aspect of the present invention may further include determination information based on a determination packet transmitted and received between the second communication device that has received the port information and the first communication device, Using the determination information received from each of the first communication device and the second communication device and the determination information received by the determination information receiving unit, the NAT information is used to determine the NAT type. A NAT type determination unit that performs type determination and a determination result transmission unit that transmits a determination result that is information indicating the NAT type determined by the NAT type determination unit to the second communication device may be provided.

  According to this configuration, the server device of this aspect can appropriately determine the NAT type by acquiring determination information from both the request terminal and the cooperation terminal and using the acquired determination information. In addition, the determination result transmission unit can notify the determination result to the request terminal.

  In the server device according to an aspect of the present invention, the connection environment information receiving unit receives the connection environment information including information indicating whether or not the first lower NAT device has a port forward function, The cooperation terminal selection unit may select the first lower NAT device as the cooperation terminal when the connection environment information indicates that the first lower NAT device has a port forward function.

  According to this configuration, the server device according to this aspect can select, for example, the communication device most suitable as the cooperation terminal as the cooperation terminal.

  The communication device according to an aspect of the present invention is connected to the Internet via an upper NAT (Network Address Translation) device connected to the Internet and a first lower NAT device connected to the upper NAT device. A communication apparatus that communicates with the server apparatus, a determination request unit that transmits a determination request for requesting determination of a NAT type of the first lower NAT apparatus to the server apparatus, and port information transmitted from the server apparatus Port information including a port number used for port forwarding for transferring a packet received by the second lower NAT device connected to the upper NAT device to a cooperative terminal connected to the second lower NAT device. Port information receiving unit for receiving the port, and the port received by the port information receiving unit Using the information, a determination packet transmitter that transmits a determination packet for determining the NAT type to the cooperation terminal, and the NAT type obtained based on the determination packet transmitted by the determination packet transmitter A determination result acquisition unit that acquires a determination result that is information to be displayed.

  According to this configuration, the communication device of this aspect can receive port information for causing a packet to reach the cooperation terminal beyond the NAT device immediately above the cooperation terminal from the server device connected to the Internet. .

  Thereby, the said communication apparatus can make a cooperation terminal receive a determination packet. That is, the communication device can appropriately execute a test for determining the NAT type of the NAT device immediately above itself using the cooperation terminal, and as a result, acquires the determination result of the NAT type. be able to.

  In the communication device according to one aspect of the present invention, the determination result acquisition unit is determination information based on the determination packet transmitted by the determination packet transmission unit, and is determination information used for determining the NAT type. A determination information transmission unit that transmits the determination result transmitted from the server device that has received the determination information transmitted by the determination information transmission unit.

  According to this configuration, the communication apparatus according to this aspect can cause the server apparatus having a function of determining the NAT type using the determination information based on the determination packet to perform the determination of the NAT type. That is, the communication apparatus does not need to process the determination information by itself and determine the NAT type, and can acquire the determination result of the NAT type from the server apparatus.

  In the communication device according to one aspect of the present invention, the determination result acquisition unit is determination information based on the determination packet transmitted by the determination packet transmission unit, and is determination information used for determining the NAT type. A determination information receiving unit that receives the port information from the cooperating terminal, and a NAT type determining unit that determines the NAT type using the determination information received by the determination information receiving unit.

  According to this configuration, the communication apparatus according to this aspect has a function of determining the NAT type using the determination information based on the determination packet.

  That is, the communication device uses other devices such as a server device for processing for NAT type determination such as transmission / reception of determination packets, and the processing for obtaining a final determination result is performed by the communication device. It can be carried out. Therefore, for example, the communication device can hide the NAT type from other devices.

  In addition, the present invention includes a server apparatus according to any one of the above aspects, a communication apparatus that functions as a request terminal according to any one of the above aspects, and a communication apparatus that functions as a cooperation terminal according to any one of the above aspects. It can be realized as a communication system.

  The present invention can also be realized as a communication method including characteristic processing executed by the communication apparatus according to any one of the above aspects.

  The present invention can also be realized as a communication method including characteristic processing executed by the server device according to any one of the above aspects.

  In addition, the present invention can be realized as a program for causing a computer to execute each process included in each of these communication methods, and as a recording medium on which the program is recorded. The program can be distributed via a transmission medium such as the Internet or a recording medium such as a DVD.

  In addition, the present invention can also be realized as an integrated circuit including characteristic components included in the communication device according to any one of the above aspects.

  Further, the present invention can also be realized as an integrated circuit including a characteristic component included in the server device according to any one of the above aspects.

  According to the present invention, even in a multi-stage NAT environment, that is, when NAT apparatuses are connected in multi-stages, the NAT type of each NAT apparatus can be individually determined.

  For example, in a communication environment having two-stage NAT devices, according to the present invention, the NAT type of the NAT device located in the lower stage can be individually determined. As described above, since the NAT type of the lower NAT device can be individually determined, the NAT type of the upper NAT device can be easily estimated.

  When the upper NAT device is an ISP-NAT device, the ISP-NAT device is commonly used by a plurality of users. Therefore, for example, if the NAT type of the upper NAT device (ISP-NAT device) can be determined by one of the multiple users by collecting and managing the NAT type determination results of a plurality of users, the upper NAT There is no need to determine the device. That is, each user can obtain the NAT type of the upper NAT device only by inquiring the external server or the like about the NAT type determination result of the upper NAT device.

The figure which shows the feature of NAT classification A flowchart showing a conventional NAT type determination method using STUN. Explanatory drawing of test I executed when determining NAT type using conventional STUN Explanatory drawing of test I 'performed in the case of determination of NAT classification using conventional STUN Explanatory drawing of Test II executed when determining NAT type using conventional STUN Explanatory drawing of test III executed when determining NAT type using conventional STUN The figure which shows the network structure in which NAT classification judgment using the conventional STUN is possible. The figure which shows the network structure which cannot perform NAT classification judgment using the conventional STUN The figure which shows the relationship between NAT classification and the severeness of restriction of the NAT classification concerned Figure showing an example of the network configuration expected in the future The figure which shows an example of a structure of the communication system in Embodiment 1 of this invention. The figure which shows the external server and the terminal device hardware configuration in Embodiment 1. The figure which shows an example of the functional block of the terminal device (request terminal) in Embodiment 1 The figure which shows an example of the functional block of the terminal device (cooperation terminal) in Embodiment 1 The figure which shows an example of the functional block of the external server in Embodiment 1 Flow chart showing the basic processing flow of the request terminal in the first embodiment Flow chart showing the basic processing flow of the external server in the first embodiment Flow chart showing the flow of basic processing of the cooperative terminal in the first embodiment The figure which shows the example of the IP address allocated to each apparatus in the communication system of Embodiment 1. The figure which shows an example of the communication sequence at the time of each terminal device in Embodiment 1 registering NAT information with an external server The figure which shows the data structural example of the NAT information stored in the NAT information management part in Embodiment 1. FIG. The figure which shows an example of the communication sequence after the request terminal in Embodiment 1 transmits a NAT classification determination request until it receives the determination result of a NAT classification. Explanatory drawing of test A for determination of NAT type in the first embodiment Explanatory drawing of test A 'for determination of NAT type in Embodiment 1 Explanatory drawing of test B for determination of NAT type in the first embodiment Explanatory drawing of test C for determination of NAT type in the first embodiment Flowchart showing an example of the NAT type determination flow in the first embodiment The figure which shows an example when the NAT classification of an upper stage NAT apparatus can be estimated in a two-stage NAT environment The figure which shows an example in case NAT type of an upper stage NAT apparatus can be estimated from the information of multiple terminal devices under the same upper stage NAT apparatus in a two-stage NAT environment The figure which shows an example of a structure of the communication system in Embodiment 2 of this invention. The figure which shows the example of the IP address allocated to each apparatus in the communication system of Embodiment 2. The figure which shows an example of a communication sequence after the request terminal in Embodiment 2 transmits a NAT classification determination request until it receives the determination result of a NAT classification. Flowchart showing an example of a NAT type determination flow in the second embodiment The figure which shows an example of a functional block in case the terminal device in Embodiment 1 or 2 is provided with the NAT classification determination function

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

(Embodiment 1)
In the first embodiment, when performing NAT type determination of a NAT device (hereinafter referred to as “determination target NAT device”) that is a target of NAT type determination, a terminal device (hereinafter referred to as “ An example of a configuration effective when there are two or more terminal devices suitable for the condition of “cooperating terminal”.

First, the configuration of the communication system in the first embodiment will be described.
FIG. 7 is a diagram showing an example of the configuration of the communication system 400 according to Embodiment 1 of the present invention.

The communication system 400 in Embodiment 1 is an example of the communication system of the present invention.
As shown in FIG. 7, the communication system 400 includes an external server 401 connected to the Internet 402 via a communication line, an ISP-NAT device 403 installed at the ISP level, NAT devices 404a, 404b, and 404c, and Terminal devices 405a, 405b, and 405c.

  The Internet 402 is a public communication network or a dedicated communication network configured by using, for example, a wired line constituted by an optical line, CATV, a telephone line, or the like, or a wireless line. Data can be exchanged between terminal devices connected to the Internet 402 according to a predetermined communication protocol.

  Each of the terminal devices 405a to 405c is an example of a communication device according to the present invention, has a function capable of communicating over a TCP / IP and UDP / IP network, and performs data communication according to each purpose. Each of the terminal devices 405a to 405c is an example of a communication device that operates as a first communication device or a second communication device that is a communication partner of the server device of the present invention.

  Each of the terminal devices 405 a to 405 c has a function of transmitting a NAT type determination request to the external server 401 (hereinafter, a terminal device that transmits a NAT type determination request is referred to as “request terminal”), and the external server 401. A function of receiving a determination cooperation request indicating a request for cooperation in NAT type determination (hereinafter, a terminal device receiving the determination cooperation request is referred to as a “cooperation terminal”).

  Further, each of the terminal devices 405a to 405c has a function capable of operating as a cooperation terminal. Specifically, each of the terminal devices 405a to 405c sets automatic port forwarding to a NAT device that directly controls the terminal device 405a to 405c, that is, a NAT device directly above itself (hereinafter referred to as “cooperative NAT device”). A function for transmitting / receiving a determination packet, and a function for transmitting determination information based on the determination packet, which is information used for NAT type determination, to the external server 401. Details of each function described above will be described later.

  The NAT devices 404a to 404c are routers having a NAT function, and have a packet routing function and constitute a LAN (Local Area Network).

  Each of the NAT devices 404a to 404c is an example of a device that functions as a first lower NAT device, a second lower NAT device, or a third lower NAT device that relays communication between the communication device and the server device of the present invention. .

  Each terminal connected to the LAN has a private IP address, and terminals existing in the same LAN can communicate with each other using the private IP address.

  The ISP-NAT device 403 is a router having a NAT function installed by the ISP, and performs IP address allocation management to each customer. The packet transfer function has a function equivalent to that of the NAT devices 404a to 404c. .

  The ISP-NAT device 403 is an example of a device that functions as an upper NAT device that relays communication between the communication device and the server device of the present invention.

  The external server 401 is an example of a server device of the present invention. The external server 401 has a function of receiving NAT type determination requests from the terminal devices 405a to 405c, and a function of selecting an appropriate cooperation terminal by referring to information held in the NAT information management unit in the external server 401. A function of transmitting a determination cooperation request to the selected cooperation terminal, a function of receiving port number information indicating a port number automatically mapped from the cooperation terminal, and the WAN side IP address information of the cooperation NAT device together with the port number information For receiving the determination information from the requesting terminal and the cooperation terminal, and a function for determining the NAT type of the determination target NAT device from the received determination information. Details of these functions will be described later.

  The external server 401 does not necessarily have to include the NAT information management unit. A NAT information management unit may be provided in a device different from the external server 401 to realize a function of holding and managing NAT information.

  Next, the hardware configuration of the external server 401 and the terminal devices 405a to 405c will be described.

  FIG. 8 is a diagram illustrating a hardware configuration of the external server 401 and the terminal devices 405a to 405c according to the first embodiment of the present invention.

  That is, the external server 401 and the terminal devices 405a to 405c can be realized by an information processing apparatus having a normal hardware configuration capable of executing software.

  Specifically, the external server 401 and the terminal devices 405a to 405c include a CPU (Central Processing Unit) 501, a main storage device 502, a communication control device 503, an external storage device 504, an input device 505, An output device 506.

  The devices are connected to each other via a bus 507 so that necessary information can be transmitted between the devices. Note that the hardware configuration shown in FIG. 8 is an example, and the hardware configuration of each of the external server 401 and the terminal devices 405a to 405c is not necessarily the same configuration.

  For example, the output device 506 may be realized by a device (such as a television) that is different from the external server or the terminal device. In this case, the external server or terminal device is separately provided with a television signal generation device such as a D / A converter, and the external server or terminal device and the output device 506 are connected by an AV cable, a coaxial cable, or the like.

  FIG. 9 is a diagram illustrating an example of functional blocks of the request terminal according to Embodiment 1 of the present invention.

  That is, FIG. 9 illustrates a functional configuration for functioning as a request terminal included in each of the terminal devices 405a to 405c.

  Each functional block is realized by the CPU 501 executing a program stored in the main storage device 502 or the external storage device 504 of the request terminal, for example.

  The NAT information registration unit 601 is a processing unit that registers all NAT device information (NAT information) between the requesting terminal and the external server 401 in the external server 401, and has a function of collecting information on the NAT devices. It also has.

  The “NAT information” is an example of connection environment information in the server device of the present invention, and is information registered in the external server 401 from each of the terminal devices 405a to 405c.

  The NAT information registered in the external server 401 includes the number of NAT devices between each terminal device and the external server 401, the WAN side IP address and LAN side IP address of each NAT device, UPnP and NAT- Examples thereof include information such as presence / absence information of an automatic port forward function such as PMP (NAT Port mapping Protocol). Note that information collected as NAT information is not limited to these.

  The NAT type determination request unit 602 transmits a NAT type determination request packet to the external server 401 for obtaining NAT type information of a NAT device in which the requesting terminal is higher than the own terminal (position closer to the Internet than the own terminal).

  At this time, for example, if the NAT information management unit provided in the external server 401 has the NAT type information of the determination target NAT device corresponding to the NAT type determination request, the external server 401 sends the NAT type information to the terminal device. You may reply to

  The port information receiving unit 603 receives port information corresponding to the automatic port forward command issued by the cooperating terminal (the port forward set in the NAT device when the cooperating terminal issues an automatic port forward command to the cooperating NAT device). Information indicating a port number to be performed) is received via the external server 401. At this time, the WAN side IP address of the cooperative NAT device is also received at the same time.

  The determination packet transmission / reception unit 604 transmits / receives a determination packet between the requesting terminal and the cooperation terminal in order to determine the NAT type of the determination target NAT device. The determination packet transmission / reception unit 604 transmits the determination packet by designating the port number and WAN side IP address of the cooperative NAT device obtained by the port information reception unit 603 as the destination port and destination address of the determination packet. Details of this function will be described later.

  The determination result acquisition unit 610 acquires the determination result of the NAT type of the determination target NAT device. In the present embodiment, NAT type determination processing is performed by the external server 401, and the determination result acquisition unit 610 acquires the result from the external server 401. The determination result acquisition unit 610 includes a determination information transmission unit 605 and a determination result reception unit 606 as functional configurations for acquiring such a determination result.

  The determination information transmitting unit 605 transmits determination information based on the determination packet transmitted by the determination packet transmitting / receiving unit 604 and used for determining the NAT type to the external server 401. This transmission processing is performed after transmission / reception of the determination packet.

  The determination result receiving unit 606 receives from the external server 401 a determination result indicating the NAT type of the determination target NAT device, which is determined by the external server 401 using the determination information transmitted from the requesting terminal and the cooperation terminal. Thereby, the requesting terminal can know the NAT type of the determination target NAT device.

  In addition, in FIG. 9 and each block diagram of FIG. 10 and FIG. 11 to be described later, the components indicated by dotted rectangles do not need to be included in the apparatus shown in each drawing.

  For example, the NAT information registration unit 601 in FIG. 9 may not be included in the request terminal. In this case, NAT information to be registered in the external server 401 by the NAT information registration unit 601 may be registered in the external server 401 by another device, for example.

  FIG. 10 is a diagram illustrating an example of functional blocks of the cooperation terminal according to Embodiment 1 of the present invention.

  That is, FIG. 10 illustrates a functional configuration for functioning as a cooperation terminal included in each of the terminal devices 405a to 405c.

  Each functional block is realized, for example, by the CPU 501 executing a program stored in the main storage device 502 or the external storage device 504 of the cooperation terminal.

  The NAT information registration unit 651 registers NAT information for all NAT devices between the requesting terminal and the external server 401 in the external server 401. The NAT information registration unit 651 also has a function of collecting information on these NAT devices. That is, the NAT information registration unit 651 has the same function as the NAT information registration unit 601 in the requesting terminal.

  The determination cooperation request receiving unit 652 receives from the external server 401 a determination cooperation request for requesting cooperation for determination of the NAT type. Specifically, the determination cooperation request reception unit 652 receives a determination cooperation request packet indicating the request content. That is, when the determination cooperation request receiving unit 652 included in a certain terminal device receives the determination cooperation request packet, the terminal device cooperates with the determination of the type of the determination target NAT device as the cooperation terminal, and transmits and receives the determination packet. become. Details of this function will be described later.

  The automatic port forward command unit 653 transmits an automatic port forward command using an arbitrary port number to the cooperative NAT device. This function is realized by UPnP or NAT-PMP. The automatic port forward command is executed when the terminal device is selected as a cooperation terminal from the external server 401 and receives a determination cooperation request packet.

  The port information transmission unit 654 notifies the requesting terminal via the external server 401 of the port number used by the automatic port forward command unit 653 and the WAN side IP address of the cooperative NAT device as port information.

  At this time, the cooperation terminal does not give the WAN side IP address of the cooperation NAT device to the port information, but the external server 401 acquires the WAN side IP address of the cooperation NAT device from the NAT information management unit and gives it. Good. Also, exchange of port information including the WAN-side IP address and port number information of the cooperative NAT device is also performed between the two cooperative terminals via the external server 401.

  The determination packet transmission / reception unit 655 transmits / receives a determination packet between the requesting terminal and the cooperation terminal in order to determine the NAT type of the determination target NAT device. The determination packet transmission / reception unit 655 receives the determination packet transmitted from the determination packet transmission / reception unit 604 included in the requesting terminal, obtains a transmission source address and a port number of the determination packet, and transmits a response packet to the transmission source address To do. Details of this function will be described later.

  The determination information transmission unit 656 transmits determination information based on the determination packet received by the determination packet transmission / reception unit 655 and used for determination of the NAT type to the external server 401. This transmission processing is performed after transmission / reception of the determination packet.

  The determination result receiving unit 657 receives a NAT type determination result from, for example, the external server 401. Note that the determination result received by the determination result receiving unit 657 is information indicating the NAT type of the NAT device directly above the requesting terminal, and this information is, as described above, the upper NAT device (ISP-NAT device 403). Can be used to determine the NAT type.

  The determination target NAT information notification unit 658 receives the determination cooperation NAT request from the external server 401 for the IP address and port number of the determination target NAT device indicated in the determination packet received by the determination packet transmission / reception unit 655. Notify the device.

  The NAT information registration unit 651 may not be included in the cooperation terminal. In this case, NAT information to be registered in the external server 401 by the NAT information registration unit 651 may be registered in the external server 401 by another device, for example.

  Further, the determination result receiving unit 657 may not be included in the cooperation terminal. The cooperating terminal only needs to have a function of cooperating in the determination of the NAT type of the determination target NAT device, and the function is not diminished by not including the determination result receiving unit 657.

  Further, the determination target NAT information notification unit 658 may not be included in the cooperation terminal. As will be described in the second embodiment to be described later, even when only one cooperation terminal exists, it may be possible to determine the NAT type of the determination target NAT device. Therefore, the determination target NAT information notification unit 658 for notifying other cooperation terminals of the port number of the determination target NAT device or the like may be omitted.

  FIG. 11 is a diagram illustrating an example of functional blocks of the external server 401 according to Embodiment 1 of the present invention.

  Each functional block is realized by the CPU 501 executing a program stored in the main storage device 502 or the external storage device 504 of the external server 401, for example.

  The NAT information receiving unit 701 is an example of a connection environment information receiving unit in the server device of the present invention, and includes information on the NAT device between the terminal device and the external server 401 transmitted from each terminal device. Receive NAT information.

  The NAT information received by the NAT information receiving unit 701 is stored and managed in the NAT information management unit 706.

  Note that the NAT information management unit 706 is not an essential component of the external server 401. For example, a server device different from the external server 401 may be installed and the server device may manage the NAT information. In this case, the NAT information receiving unit 701 may receive NAT information from the server device.

  The NAT information held and managed by the NAT information management unit 706 includes a unique terminal device name, the number of NAT devices, a WAN side IP address of each NAT device, and a LAN side IP address of each NAT device. The presence / absence information of the automatic port forward function of the NAT device such as UPnP or NAT-PMP is exemplified, but is not limited thereto. A management example of the NAT information management unit 706 will be described later in the description of the processing flow.

The determination request receiving unit 702 receives a NAT type determination request transmitted from the requesting terminal.
When the determination request reception unit 702 receives a NAT type determination request, the cooperation terminal selection unit 707 refers to the NAT information described above to select a terminal device that satisfies a predetermined standard as a cooperation terminal.

  The determination cooperation request transmission unit 703 transmits a determination cooperation request packet to the cooperation terminal selected by the cooperation terminal selection unit 707.

  The port information transmission / reception unit 704 receives the port information corresponding to the automatic port forward command issued by the cooperation terminal to the cooperation NAT device, and transmits the received port information to the request terminal, so that the port number and WAN of the cooperation NAT device are transmitted. To the requesting terminal.

  Note that the port information transmission / reception unit 704 may receive port information not including the WAN side IP address of the cooperative NAT device from the cooperative terminal and forward the packet to the requesting terminal including the WAN side IP address of the cooperative NAT device. .

  The determination unit 710 determines the NAT type of the determination target NAT device. The determination unit 710 includes a determination information reception unit 705 and a NAT type determination unit 708 as functional configurations for performing a NAT type determination process.

  The determination information receiving unit 705 receives determination information transmitted from the requesting terminal and the cooperation terminal. The NAT type determination unit 708 uses the determination information received by the determination information reception unit 705 to determine the NAT type of the determination target NAT device.

  The determination result transmission unit 709 notifies the request terminal of the determination result obtained from the determination unit 710.

  Note that the determination unit 710 and the determination information reception unit 705 are not essential components of the external server 401. For example, the request terminal or the cooperation terminal may be provided with a function corresponding to the determination unit 710, and the request terminal or the cooperation terminal may perform NAT type determination processing.

  A functional configuration when the request terminal has a function corresponding to the determination unit 710 will be described later with reference to FIG.

  Also, part or all of the functional configuration shown in each of FIGS. 9 to 11 can be realized as one integrated circuit. That is, the terminal device 405a (405b, 405c) that functions as at least one of the requesting terminal and the cooperation terminal, and the external server 401 can each be realized by an integrated circuit.

  Next, the basic processing flow of the external server 401 and the terminal devices 405a to 405c will be described with reference to FIGS. 12A to 12C.

  FIG. 12A is a flowchart showing a basic processing flow of the request terminal according to Embodiment 1 of the present invention.

  The basic processing flow when the terminal device 405a functions as a request terminal will be described with reference to FIG. 12A. The terminal devices 405b and 405c also function as a request terminal by executing the processing shown in FIG. 12A. be able to.

  The NAT type determination request unit 602 transmits a determination request for requesting determination of the NAT type of the NAT device 404a, which is the determination target NAT device, to the external server 401 (S10).

  The port information receiving unit 603 receives the port information transmitted from the external server 401 and including the port number used for port forwarding from the cooperative NAT device to the cooperative terminal (S11).

  The determination packet transmission / reception unit 604 transmits a determination packet to the cooperation terminal using the port information received by the port information reception unit 603 (S12). That is, a determination packet including the port number included in the port information as the destination port is generated and transmitted to the cooperation terminal.

  The determination result acquisition unit 610 acquires a determination result, which is information indicating the NAT type of the NAT device 404a, obtained using the transmission result of the determination packet (S13). In the present embodiment, the determination result acquisition unit 610 acquires the determination result transmitted from the external server 401.

  FIG. 12B is a flowchart showing a basic processing flow of the external server 401 according to Embodiment 1 of the present invention. A basic processing flow of the external server 401 will be described with reference to FIG. 12B.

  The NAT information receiving unit 701 receives connection environment information including information related to the NAT device from each terminal device (405a to 405c) (S20). In the present embodiment, the connection environment information is NAT information including the WAN side IP address and LAN side IP address of each NAT device as described above.

  In the present embodiment, the NAT information received by the NAT information receiving unit 701 is stored in the NAT information management unit 706.

  The determination request receiving unit 702 receives a NAT type determination request for requesting determination of the NAT type of the determination target NAT device transmitted from the requesting terminal (S21).

  When the determination request receiving unit 702 receives the NAT type determination request, the cooperating terminal selecting unit 707 refers to the NAT information received by the NAT information receiving unit 701 as a cooperating terminal. Select (S22).

  The determination cooperation request transmission unit 703 transmits a determination cooperation request for requesting cooperation of the NAT type determination to the cooperation terminal selected by the cooperation terminal selection unit 707 (S23).

  The port information transmission / reception unit 704 receives port information from the cooperation terminal that has received the determination cooperation request (S24). The port information transmission / reception unit 704 further transmits the received port information to the requesting terminal (S25).

  The port information includes a port number used for port forwarding for transferring a packet received by the cooperating NAT device to the cooperating terminal. In the present embodiment, the WAN of the cooperating NAT device is used. The side IP address is also included in the port information.

  FIG. 12C is a flowchart showing a basic processing flow of the cooperative terminal according to Embodiment 1 of the present invention.

  Although a basic processing flow when the terminal device 405a functions as a cooperation terminal will be described with reference to FIG. 12C, the terminal devices 405b and 405c also function as a cooperation terminal by executing the processing shown in FIG. 12C. be able to.

  The determination cooperation request receiving unit 652 receives the determination cooperation request transmitted from the external server 401 and requesting the cooperation of the NAT type determination of the upper NAT determination target NAT device (S30).

  When the determination cooperation request reception unit 652 receives the determination cooperation request, the NAT device 404a is instructed to execute port forwarding for transferring the packet received by the NAT device 404a, which is the cooperation NAT device, to the terminal device 405a (S31). ).

  The port information transmission unit 654 transmits port information including the port number used for the port forwarding to the external server 401 (S32). In the present embodiment, this port information includes the WAN side IP address of the NAT device 404a.

  The determination packet transmitting / receiving unit 655 receives a determination packet for determining the NAT type transmitted from the requesting terminal that has received the port information from the external server 401 (S33).

  The determination information transmission unit 656 transmits the determination information used for determining the NAT type obtained based on the determination packet received by the determination packet transmission / reception unit 655 to the external server 401 (S34).

  Next, the flow of processing of each device in the communication system 400 according to Embodiment 1 will be described with reference to FIGS.

  Specifically, the processing flow of each device included in the communication system 400 will be described using the environment illustrated in FIG. 13 as an example.

  FIG. 13 is a diagram illustrating an example of an IP address assigned to each device in the communication system 400 according to the first embodiment.

  Assume an environment in which one or two IP addresses are assigned to each device as shown in FIG.

  Further, assuming that CE_X that is the terminal device 405a transmits a NAT type determination request packet as a request terminal, the following description will be given. Further, it is assumed that the NAT devices 404b and 404c have an automatic port forward function and operate as a cooperative NAT device.

  That is, in this case, the terminal device 405b (CE_Y) and the terminal device 405c (CE_Z) operate as cooperative terminals.

  FIG. 14 is a diagram illustrating an example of a communication sequence when each terminal device according to the first embodiment registers NAT information in the external server 401.

  First, in each process of S201a to S201c, each terminal device (CE_X, CE_Y, CE_Z) acquires information on all NAT devices (NAT information) between itself and the external server 401.

  As described above, the NAT information to be acquired includes the WAN side IP address and the LAN side IP address of each NAT device, the presence / absence information of the automatic port forward function in UPnP, NAT-PMP, and the like.

  The WAN side IP address and LAN side IP address of each NAT device can be obtained by using ICMP packets such as traceroute or UPnP GetExternalIPAddress. Further, the presence / absence information of the automatic port forward function can be determined by using a function such as UPnP.

  For example, CE_X transmits a predetermined inquiry packet defined by UPnP or the like to the NAT device 404a (determination target NAT device_X) immediately above, thereby determining the LAN side IP address “192.168.8.1” of the determination target NAT device_X. .1 ”and WAN-side IP address“ 192.168.0.2 ”, and the presence / absence information of the automatic port forward function are acquired. CE_X also transmits an inquiry packet to the ISP-NAT device 403 in the same manner, whereby the LAN-side IP address “192.168.0.1” and the WAN-side IP address “10” of the ISP-NAT device 403 are transmitted. 0.0.2 "and the presence / absence information of the automatic port forward function.

  CE_Y acquires NAT information from the NAT device 404b (cooperating NAT device_Y) and ISP-NAT device 403 directly above, and CE_Z is the NAT device 404c (cooperating NAT device_Z) and ISP-NAT device directly above. NAT information is acquired from each of 403.

  14 is a process in which all terminal devices except for the external server 401 obtain information on NAT devices that are higher than the own terminal, and the information to be obtained is the LAN side of the NAT device. And the WAN side IP address, the presence / absence information of the automatic port forwarding function, etc., but other information may be acquired.

  In each process of S202a to S202c, each terminal device (CE_X, CE_Y, CE_Z) transmits the NAT information acquired in S201a to S201c to the external server 401. When the external server 401 receives the NAT information in S203a to S203c, the external server 401 registers and manages the NAT information in the NAT information management unit 706 in the external server 401.

  Note that the above-described processes of S201a to S201c, S202a to S202c, and S203a to S203c can also be performed when each terminal device (CE_X, CE_Y, CE_Z) is connected to the network or when the power is turned on. That is, these processes may be executed at any time as long as they are executed before the process flow of FIG. 16 described later is performed.

  FIG. 15 is a diagram illustrating a data configuration example of NAT information stored in the NAT information management unit 706 according to the first embodiment.

  Here, “NAT1” shown in FIG. 15 means the upper NAT device for each terminal device that communicates with the external server 401 via the two-stage NAT device. That is, in this embodiment, NAT1 is the ISP-NAT device 403 for all terminal devices.

  “NAT2” means the lower NAT device for each terminal device. That is, in the present embodiment, as shown in FIG. 13, NAT2 for CE_X is the determination target NAT device_X. Further, NAT2 for CE_Y is a cooperative NAT device_Y, and NAT2 for CE_Z is a cooperative NAT device_Z.

  Further, “1” in the automatic port forward function column means that there is an automatic port forward function, and “0” in the automatic port forward function column means that there is no automatic port forward function.

  That is, FIG. 15 shows that the ISP-NAT device 403 does not have an automatic port forward function. Further, FIG. 15 shows that the determination target NAT device_X does not have an automatic port forward function, and the cooperative NAT device_Y and the cooperative NAT device_Z have an automatic port forward function.

  The correspondence between each NAT device and the presence or absence of the automatic port forward function is an example. In the present embodiment, a NAT device having an automatic port forward function may be selected as a cooperative NAT device.

  FIG. 16 is a diagram illustrating an example of a communication sequence from when a request terminal according to the first embodiment transmits a NAT type determination request to when a NAT type determination result is received.

  In S251 of FIG. 16, CE_X that is the requesting terminal transmits a NAT type determination request that requests the external server 401 to determine the NAT type of the determination target NAT device_X.

  When the external server 401 receives the NAT type determination request in S252, the external server 401 proceeds to the execution of the cooperation terminal selection process S253.

  In the process S253, the external server 401 that has received the NAT type determination request selects a cooperation terminal by referring to the NAT information stored in the NAT information management unit 706.

  In the present embodiment, the criteria to be selected at this time are the following (1) and (2).

  (1) The LAN side IP address of the NAT device that is one level higher than the determination target NAT device (close to the Internet) and the LAN side IP of the NAT device that is one level higher than the NAT device immediately above the selected target terminal device The address is the same.

  (2) The NAT device immediately above the terminal device to be selected supports the automatic port forward function.

  When the terminal device to be selected satisfies the criteria (1) and (2), the terminal device is selected as a cooperation terminal.

  In the case of this example, as shown in FIG. 13, the ISP-NAT device 403 that is one level higher than the determination target NAT device_X is one level higher for both the NAT device 404b and the NAT device 404c immediately above CE_Y and CE_Z. This also applies to the NAT device. Therefore, both CE_Y and CE_Z satisfy the above criterion (1).

  Further, since both the NAT device 404b and the NAT device 404c have an automatic port forward function as shown in FIG. 15, both CE_Y and CE_Z also satisfy the above criterion (2).

  Accordingly, both CE_Y and CE_Z are selected as cooperation terminals by the cooperation terminal selection unit 707 provided in the external server 401.

  In this embodiment, two terminal devices are selected as cooperation terminals. However, when there are three or more terminal devices that satisfy the criteria for cooperation terminals, the selection method of two of these is arbitrary. The selection method may be used.

  In S254, after S253 is executed, the determination cooperation request packet is transmitted to the two cooperation terminals (CE_Y, CE_Z) selected by the external server 401.

  Each terminal device (CE_Y, CE_Z) that has received the determination cooperation request packet in S255c and S255b executes processing S256b, S256c, S257b, and S257c as a cooperation terminal.

  The terminal device that has received the determination cooperation request packet may be provided with a function of rejecting the cooperation request to the external server 401 in the terminal device. In this case, the external server 401 executes again the process of selecting the cooperation terminal by referring to the NAT information.

  In S256b and S256c, the cooperation terminals CE_Y and CE_Z transmit an automatic port forward command to any two ports, using a function such as UPnP or NAT-PMP, to each of the cooperation NAT devices directly above.

  That is, CE_Y transmits an automatic port forward command to the cooperative NAT device_Y and CE_Z transmits to the cooperative NAT device_Z.

  After execution of the automatic port forward instruction, CE_Y and CE_Z execute S257b and S257c.

  Hereinafter, CE_Y issues an automatic port forward command to cooperative NAT device_Y to port p and port q, and CE_Z issues an automatic port forward command to cooperative NAT device_Z to port r and port s. Assuming that

  In S257b and S257c, the two cooperating terminals (CE_Y, CE_Z) transmit the port number information set in S256b and S256c and the WAN side IP address information of the cooperating NAT device to the external server 401 as port information. .

  Upon receiving the port information from the cooperation terminals (CE_Y, CE_Z), the external server 401 transmits the received port information to the requesting terminal CE_X in S258.

  Further, the mutual port information is also exchanged between the two cooperating terminals, that is, between CE_Y and CE_Z, via the external server 401.

  Note that the port information transmitted from the two cooperating terminals to the external server 401 in S257b and S257c may not include the WAN-side IP of each cooperating NAT device. In this case, the external server 401 may acquire the WAN-side IP address of each cooperative NAT device, for example, from the NAT information management unit 706, give it to each port information, and transmit it to the requesting terminal CE_X.

  In this way, the port information transmitted from the external server 401 is received by the request terminal CE_X in S259.

  In the processes S260a to S260c, a determination packet for determining the NAT type of the determination target NAT device_X is transmitted and received between the requesting terminal CE_X and the two cooperating terminals CE_Y and CE_Z.

  Here, the request terminal CE_X, in S259, the WAN side IP address (192.168.0.3) of the cooperative NAT device_Y, the two port number information (port p and port q) automatically mapped, and , The WAN side IP address (192.168.0.4) of the cooperative NAT device_Z, and two port number information (port r and port s) that are automatically mapped are obtained.

  Also, CE_Y and CE_Z, which are cooperating terminals, obtain the WAN side IP address of the NAT device immediately above the other and two port number information that are automatically mapped.

Therefore, CE_X, CE_Y, and CE_Z can communicate with each other.
The test for determining the NAT type is executed by performing the four tests shown in FIGS. 17A to 17D in an arbitrary order.

  The test A shown in FIG. 17A corresponds to the NAT type determination test I using STUN, which is the prior art shown in FIG. 3A.

  The request terminal CE_X transmits a determination packet with the WAN-side IP address 192.168.0.3 and the port p of the cooperative NAT device_Y as destinations. The cooperation terminal CE_Y that has received the determination packet obtains the WAN-side IP address 192.168.0.2 and the port number of the determination target NAT device_X. Also, the cooperation terminal CE_Y returns a packet in which the WAN-side IP address 192.168.0.2 and the port number of the obtained determination target NAT device_X are set as the destination and the transmission source port is specified as the port p. That is, the cooperation terminal CE_Y transmits a response packet to the determination packet.

  When a response packet to the determination packet is transmitted, the request terminal CE_X receives the response packet. The WAN address IP address 192.168.0.2 of the determination target NAT device_X included in the received response packet; The port number of the determination target NAT device_X used in the determination packet to the cooperation terminal CE_Y is obtained. Further, the request terminal CE_X determines that there is no response when it does not receive a response packet.

  The test A ′ shown in FIG. 17B corresponds to the NAT type determination test I ′ using STUN, which is the conventional technique shown in FIG. 3B.

  The request terminal CE_X transmits a determination packet with the WAN-side IP address 192.168.0.4 and the port s of the cooperative NAT device_Z as destinations.

  The cooperative terminal CE_Z that has received the determination packet obtains the WAN-side IP address 192.168.0.2 and the port number of the determination target NAT device_X. The cooperating terminal CE_Z returns a response packet in which the obtained WAN-side IP address 192.168.0.2 and port number of the determination target NAT device are set as destinations and the transmission source port is designated as port q.

  When a response packet is returned, the request terminal CE_X receives the response packet, and the WAN-side IP address 192.168.0.2 of the determination target NAT device_X included in the received response packet and the cooperation terminal The port number of the determination target NAT device_X used in the determination packet to CE_Z is obtained. Further, the request terminal CE_X determines that there is no response when it does not receive a response packet.

  Test B shown in FIG. 17C corresponds to NAT type determination test II using STUN, which is the prior art shown in FIG. 3C.

  The request terminal CE_X transmits a determination packet with the WAN-side IP address 192.168.0.3 and the port p of the cooperative NAT device_Y as destinations.

  The cooperation terminal CE_Y that has received the determination packet obtains the WAN-side IP address 192.168.0.2 and the port number of the determination target NAT device_X. The determination target NAT information notification unit 658 of the cooperation terminal CE_Y notifies the cooperation terminal CE_Z of the IP address information and the port number. The port number used for communication between the cooperative terminals at this time is exchanged between the cooperative terminals as described above. That is, each cooperation terminal uses an arbitrary port number of the other port numbers obtained by this exchange for communication between the cooperation terminals.

  The cooperating terminal CE_Z returns a response packet in which the WAN-side IP address 192.168.0.2 and the port number of the determination target NAT device_X obtained from the cooperating terminal CE_Y are set as destinations and the transmission source port is designated as port s .

  The request terminal CE_X receives the response packet when a response packet is returned, and determines that there is no response when there is no response.

  The test C shown in FIG. 17D corresponds to the NAT type determination test III using STUN, which is the prior art shown in FIG. 3D.

  The request terminal CE_X transmits a determination packet with the WAN-side IP address 192.168.0.3 and the port p of the cooperative NAT device_Y as destinations.

  The cooperative terminal CE_Y that has received the determination packet obtains the WAN-side IP address 192.168.0.2 and port information of the determination target NAT device_X. The cooperating terminal CE_Y returns a response packet in which the WAN-side IP address 192.168.0.2 and the port number of the obtained determination target NAT device_X are set as the destination and the transmission source port is specified as the port q.

  The requesting terminal CE_X receives when a response packet is returned, and determines that there is no response when there is no response.

  Next, in S261a to S261c shown in FIG. 16, the request terminal CE_X, the cooperation terminal CE_Y, and the cooperation terminal CE_Z obtain the determination information indicating the results of the tests A to C and A ′ obtained in the above S260a to S260c. Send to server 401.

  The determination information includes, for example, information indicating the IP address and port number included in the determination packet received by the cooperation terminal from the request terminal, or information indicating whether the request terminal has received a response packet from the cooperation terminal, or the like. Is included.

  The external server 401 receives the determination information in S262, and executes NAT type determination processing in S263.

  In steps S262 and S263, the apparatus that receives the determination information and executes the NAT type determination process may not be the external server 401. Even if it is a request terminal, a cooperation terminal, or another apparatus, if the apparatus has a NAT type determination function, the apparatus may receive determination information and execute a NAT type determination process.

  In the present embodiment, using the determination information received by the external server 401 in S262, the NAT type determination unit 708 provided in the external server 401 determines the NAT type of the determination target NAT device_X (S263). FIG. 18 shows a NAT type determination flow.

  First, the NAT type determination unit 708 determines whether there is a response as a result of the test A (S301). If there is no response (N in S301), “(1) there is a firewall that blocks UDP. Is determined.

  On the other hand, if a response is received (Y in S301), the NAT type determination unit 708 determines whether or not the transmission source IP address of the determination packet received by the cooperation terminal CE_Y is the same as the IP address of the request terminal CE_X. (S302).

  As a result of this determination, if these IP addresses are the same (Y in S302), the NAT type determination unit 708 determines that the determination target NAT device_X does not actually have the NAT function, and further performs the test B. Result determination is executed (S303).

  Specifically, the NAT type determination unit 708 determines whether the request terminal CE_X has received a response from the cooperation terminal CE_Z from the result of the test B (S303). When there is no response (N in S303), the NAT type determination unit 708 determines that “(2) There is a firewall that blocks UDP but does not perform address conversion, like a symmetric NAT device”. On the other hand, when the request terminal CE_X receives a response from the cooperation terminal CE_Z (Y in S303), the NAT type determination unit 708 determines that “(3) no NAT function”.

  In S302, if the source IP address of the determination packet received by the cooperation terminal CE_Y is not the same as the IP address of the request terminal CE_X (the request terminal CE_X is under the NAT device) (N in S302), test B Then, it is determined whether or not there is a response from the cooperation terminal CE_Z (S304). Therefore, when there is a response (Y in S304), the NAT type determination unit 708 determines that the NAT type is “(4) Full cone type”.

  On the other hand, when there is no response (N in S304), the source IP address and port number of the determination packet received by the cooperative terminal CE_Y obtained from the result of the test A and the result of the test A ′ are obtained. Then, it is determined whether or not the transmission source IP address and the port number of the determination packet received by the cooperative terminal CE_Z are the same (S305).

  Therefore, if these two sets of IP addresses and port numbers are not the same (N in S305), the NAT type determination unit 708 determines that the NAT type is “(5) Symmetric”.

  On the other hand, if the combination of these two sets of IP addresses and port numbers is the same in S305 (Y in S305), it is subsequently determined from the result of test C whether there is a response from the cooperating terminal CE_Y. (S306). When there is a response (Y in S306), even if the destination port number of the transmission packet and the transmission source port number of the reception packet are different from each other, the transmission source IP address and the reception packet If the destination IP address is the same, it means that a response is returned. Therefore, the NAT type determination unit 708 determines that the NAT type is “(6) Restricted Cone type”.

  On the other hand, if there is no response (N in S 306), even if the two IP addresses are the same, if the two port numbers are different from each other, no response is returned. The NAT type is determined to be “(7) Port Restricted Cone”.

  Next, in S264 shown in FIG. 16, the external server 401 transmits the determination result regarding the NAT type of the determination target NAT device_X obtained in S263 to the request terminal CE_X. The request terminal CE_X receives the determination result in S265.

  As described above, in the communication system 400 according to the present embodiment, it is possible to individually determine the NAT type of the lower NAT device in the two-stage NAT environment.

  It is also possible to determine the NAT type of the upper NAT device (the ISP-NAT device 403 in this embodiment) by determining the NAT type of the lower NAT device.

  As an example, in FIG. 19, in a two-stage NAT environment, the NAT type determination result (hereinafter referred to as “lower NAT type”) of the lower NAT device 404a is a perfect cone type, and two stages (ISP-NAT). An example in which the type determination result obtained by integrating the NAT types of the device 403 and the NAT device 404a (hereinafter referred to as “integrated NAT type”) is a symmetric type is shown.

  Here, for example, when obtaining an integrated NAT type for a multi-stage NAT device using a STUN server, the NAT type with the most severe restriction among the NAT types of the multi-stage NAT devices is obtained as the integrated NAT type. It has the nature of

  Accordingly, in the example shown in FIG. 19, the integrated NAT type (symmetric type) is more restrictive than the lower NAT type (complete cone type), and therefore the terminal device 405a has the NAT type of the upper ISP-NAT device 403 as It can be estimated that it is equal to the integrated NAT type. That is, the terminal device 405a can specifically determine that the NAT type of the ISP-NAT device 403 is symmetric.

  Further, it is assumed that the restriction of the upper NAT device is easier than the restriction of the lower NAT device, and the NAT type of the upper NAT device cannot be estimated.

  Even in this case, it is possible to estimate the NAT type of the upper NAT device by totaling the determination results of the NAT types acquired by the plurality of terminal devices under the upper NAT device.

  As an example, FIG. 20 shows a communication system in which the upper NAT device is easier to limit than the lower NAT device.

  Specifically, in FIG. 20, the NAT type of the upper ISP-NA device 403 is a complete cone type, and the NAT type of the NAT device 404a is limited among the two lower NAT devices (404a, 404b). A case in which the NAT type of the NAT device 404b is a complete cone type is shown.

  In the example shown in FIG. 20, the lower NAT type (limited cone type) for the NAT device 404 a and the ISP-NAT device 403 is more restrictive than the NAT type (complete cone type) of the upper ISP-NAT device 403.

  Therefore, even if the terminal device 405a under the NAT device 404a acquires the integrated NAT type for these two-stage NAT devices, the integrated NAT type is the same type (restricted cone type) as the lower NAT type. is there. Therefore, the terminal device 405a cannot estimate the NAT type of the upper ISP-NAT device 403.

  However, when the terminal device 405b under the same upper NAT device as the terminal device 405a uses the present invention, the terminal device 405a can acquire the NAT type of the upper ISP-NAT device 403.

  Specifically, first, the terminal device 405b operates as a request terminal in the present embodiment, thereby acquiring that the NAT type of the NAT device 404b directly above is a complete cone type. In addition, the terminal device 405b acquires that the integrated NAT type for the NAT device 404b and the ISP-NAT device 403 is a complete cone type by a method using a STUN server, for example.

  In this case, since the lower NAT type is a complete cone type and the integrated NAT type is also a complete cone type, the terminal device 405b determines that the NAT type of the upper ISP-NAT device 403 is a complete cone type. Judgment can be made.

  The terminal device 405b registers information indicating the determination result in, for example, the NAT information management unit 706 provided in the external server 401. Accordingly, the terminal device 405a can acquire from the external server 401 that the NAT type of the upper ISP-NAT device 403 is a complete cone type.

(Embodiment 2)
In the second embodiment, an example of a configuration effective when there is only one terminal device that satisfies the criteria as a cooperation terminal when determining the NAT type of the determination target NAT device is shown.

First, the configuration of the communication system in the second embodiment will be described.
FIG. 21 is a diagram illustrating an example of a configuration of the communication system 900 according to the second embodiment.

  A communication system 900 according to Embodiment 2 is another example of the communication system of the present invention.

  As shown in FIG. 21, the communication system 900 includes an external server 901 connected to the Internet 402 via a communication line, an ISP-NAT device 902 installed at the ISP level, NAT devices 903a and 903b, and a terminal device. 904a and 904b.

  As in the first embodiment, the Internet 402 is a public communication network or a dedicated communication network configured by using, for example, a wired line constituted by an optical line, CATV, a telephone line, or the like, or a wireless line. Data can be exchanged between terminal devices connected to the Internet 402 according to a predetermined communication protocol.

  The hardware configuration and functional blocks provided in the external server 901 and the terminal devices 904a and 904b are the same as those in the first embodiment (see FIGS. 8 to 11), and thus illustration and description thereof are omitted. .

  That is, each of the terminal devices 904a and 904b can function as a request terminal and a cooperation terminal. Further, the external server 901 has the same functions as the external server 401 in the first embodiment, such as a function of transferring port information transmitted from the cooperation terminal to the requesting terminal.

  Further, each of the terminal devices 904a and 904b and the external server 901 can also be realized by an integrated circuit, like the terminal device 405a and the like in the first embodiment.

  The ISP-NAT device 902 and the NAT devices 903a and 903b are also routers having a NAT function, similar to the ISP-NAT device 403 and the NAT device 404a in the first embodiment.

  Here, the flow of processing of each device included in the communication system 900 will be described using the environment illustrated in FIG. 22 as an example.

  Assume an environment in which one or two IP addresses are assigned to each device as shown in FIG.

  Further, assuming that CE_X that is the terminal device 904a transmits a determination NAT type determination request packet as a request terminal, the following description will be given. Further, it is assumed that the NAT device 903b has an automatic port forward function and operates as a cooperative NAT device. That is, in this case, the terminal device 904b (CE_Y) operates as a cooperation terminal.

  The terminal device 904a has a functional configuration for operating as a requesting terminal shown in FIG. 9, and the terminal device 904b has a functional configuration for operating as a cooperation terminal shown in FIG. Yes. The external server 901 has a functional configuration shown in FIG.

  Also, in the communication system 900 according to the second embodiment, as in the first embodiment, registration of NAT information from each terminal device to the external server 901 is performed. However, since the processing flow related to this registration is the same as the processing flow shown in FIG. 14 of the first embodiment, illustration and description thereof are omitted.

  FIG. 23 is a diagram illustrating an example of a communication sequence from when a request terminal according to the second embodiment transmits a NAT type determination request to when a NAT type determination result is received.

  In S351 in FIG. 23, CE_X, which is the requesting terminal, transmits a NAT type determination request for requesting determination of the NAT type of the NAT device 903a (determination target NAT device_X) to the external server 901.

  The external server 901 receives the NAT type determination request in S352, and shifts to the execution of the cooperation terminal selection process S353.

  In the process S353, the external server 901 that has received the NAT type determination request selects one cooperation terminal by referring to the NAT information stored in the NAT information management unit 706 provided in the external server 901.

  The criteria to be selected at this time are the same as those in the first embodiment. In this example, only CE_Y satisfies the criteria, and only CE_Y is selected as the cooperation terminal.

  In S354, after S353 is executed, a determination cooperation request packet is transmitted to the cooperation terminal CE_Y selected by the external server 901.

  The terminal device CE_Y that has received the determination cooperation request packet in S355 executes S356 and S357 as a cooperation terminal.

  In S356, the cooperation terminal CE_Y transmits an automatic port forward command to any two ports using a function such as UPnP or NAT-PMP to the NAT device 903b (cooperation NAT device_Y) directly above. The cooperation terminal CE_Y executes S357 after executing the automatic port forward command.

  Hereinafter, the cooperation terminal CE_Y will be described assuming that an automatic port forward command to the cooperation NAT device_Y is issued to the port p and the port q.

  In S357, the cooperation terminal CE_Y transmits the port number information set in S356 and the WAN side IP address information of the cooperation NAT device_Y to the external server 901 as port information.

  When receiving the port information from the cooperation terminal CE_Y, the external server 901 transmits the received port information to the requesting terminal CE_X in S358.

  Note that. The port information transmitted from the cooperation terminal CE_Y to the external server 901 in S357 may not include the WAN side IP of the cooperation NAT device_Y. In this case, the external server 901 may acquire the WAN-side IP address of the cooperative NAT device_Y from, for example, the NAT information management unit 706, give it to the port information, and transmit it to the requesting terminal CE_X.

  In the processes S360a and S360b, a determination packet for determining the type of the determination target NAT device_X is transmitted and received between the requesting terminal CE_X and the cooperation terminal CE_Y.

  The request terminal CE_X obtains the WAN side IP address (192.168.0.3) of the cooperative NAT device_Y and the two port information (port p and port q) automatically mapped by the above S357, S358, and S359. It has gained. Therefore, the request terminal CE_X and the cooperation terminal CE_Y can communicate with each other.

  The test performed by transmission / reception of the determination packet is executed by performing two tests (test A and test C) illustrated in FIGS. 17A and 17D in an arbitrary order. Note that the details of the test A and the test C are the same as those in the first embodiment, and thus the description thereof is omitted here.

  In S361a and S361b, the request terminal CE_X and the cooperation terminal CE_Y transmit the determination information obtained as a result of the test A and the test C obtained in S360a and S360b to the external server 901.

  The external server 901 receives the determination information in S362, and executes NAT type determination in S363.

  In S362 and S363, the device that receives the determination information and executes the NAT type determination process may not be the external server 901. Even if it is a request terminal, a cooperation terminal, or another apparatus, if the apparatus has a NAT type determination function, the apparatus may receive determination information and execute a NAT type determination process.

  In S363, using the determination information received by the external server 901 in S362, the NAT type determining unit 708 of the external server 901 determines the NAT type of the determination target NAT device_X. FIG. 24 shows a NAT type determination flow.

  First, the NAT type determination unit 708 determines whether or not there is a response as a result of the test A (S401). If there is no response (N in S401), “(1) there is a firewall that blocks UDP. Is determined.

  On the other hand, if a response is received (Y in S401), the NAT type determination unit 708 determines whether or not the transmission source IP address of the determination packet received by the cooperation terminal CE_Y is the same as the IP address of the requesting terminal CE_X. (S402).

  As a result of the determination, if these IP addresses are the same (Y in S402), the NAT type determination unit 708 determines that the determination target NAT device_X does not actually have the NAT function, and “(2) Address conversion” However, it is determined that there is a firewall that blocks UDP like a symmetric NAT device ”or“ (3) No NAT function ”.

  On the other hand, if the source IP address of the determination packet received by the cooperation terminal CE_Y is not the same as the IP address of the request terminal CE_X in S402 (the request terminal CE_X is under the NAT device) (N in S402), the NAT type determination Subsequently, the unit 708 determines from the result of the test C whether or not there is a response from the cooperation terminal CE_Y (S403).

  If there is a response as a result of this determination (Y in S403), the NAT type determination unit 708 sets the NAT type to “(4) Full cone type” or “(6) Restricted cone type”. (Restricted Cone) ”.

  On the other hand, when there is no response (N in S403), the NAT type determination unit 708 sets the NAT type to “(5) Symmetric” or “(7) Cone type with port restriction (Port Restricted Cone)”. Is determined.

  Next, in S364 illustrated in FIG. 23, the external server 901 transmits the determination result regarding the NAT type of the determination target NAT device_X obtained in S363 to the request terminal CE_X. The request terminal CE_X receives the determination result in S365.

  As described above, according to the communication system 900 according to the second embodiment, even if there is only one terminal device suitable for NAT type determination cooperation in the two-stage NAT environment, the lower-stage NAT apparatus. It is possible to narrow the range of the NAT type.

  The communication device, server device, communication system, communication method, and integrated circuit of the present invention have been described based on the first and second embodiments. However, the present invention is not limited to these embodiments. Unless it deviates from the gist of the present invention, various modifications conceived by those skilled in the art have been made in the present embodiment, or forms constructed by combining a plurality of the above-described constituent elements are within the scope of the present invention. include.

  For example, as described above, the function of determining the NAT type may be provided not in the external server 401 (901) but in a terminal device such as the terminal device 405a.

  FIG. 25 is a diagram illustrating an example of functional blocks when the terminal device according to the first or second embodiment has a NAT type determination function.

  A terminal device 405a illustrated in FIG. 25 is a device that functions as a request terminal, and a basic functional configuration is the same as the functional configuration illustrated in FIG.

  However, the terminal device 405a illustrated in FIG. 25 includes a determination result acquisition unit 610b, and the determination result acquisition unit 610b includes a determination information reception unit 705 and a NAT type determination unit 708. That is, the determination result acquisition unit 610b includes a determination unit 710 illustrated in FIG.

  The determination information receiving unit 705 and the NAT type determining unit 708 are processing units that receive the determination information and determine the NAT type from the received determination information, as described in the explanation of FIG.

  Specifically, the determination information receiving unit 705 included in the determination result acquisition unit 610b receives the determination information transmitted from the cooperation terminal (such as 405b). Further, the determination information of the terminal itself (whether there is a response to the determination packet or the like) is acquired from the determination packet transmission / reception unit 604.

  The NAT type determination unit 708 included in the determination result acquisition unit 610b executes the NAT type determination process using the determination information from the cooperation terminal and the own terminal acquired by the determination information reception unit 705. As a result, the terminal device 405a that is the requesting terminal can acquire the NAT type of the NAT device 404a that is the determination target NAT device.

  Further, the determination result by the NAT type determination unit 708 is registered in the external server 401, for example, so that other terminal devices can use the determination result.

  According to the communication apparatus and the like according to the present invention, it is possible to individually determine the NAT type of each NAT apparatus even in a multi-stage NAT environment. As a result, even when a certain terminal device performs P2P communication with any partner in a multi-stage NAT environment, it is possible to individually determine the NAT type of the NAT device. A method can be selected. For this reason, the present invention is useful as a technology for improving connectivity during P2P communication.

  The present invention is also applicable to applications such as pinpointing NAT devices that are problematic in NAT traversal as support to customers who cannot connect to P2P because NAT traversal is not possible in a multi-stage NAT environment. Can be applied.

201, 204, 301 STUN server 202, 205, 206, 303, 305, 404a, 404b, 404c, 903a, 903b NAT device 203, 207, 304, 306, 405a, 405b, 405c, 904a, 904b Terminal device 302, 403 902 ISP-NAT device 400, 900 Communication system 401, 901 External server 402 Internet 501 CPU
502 Main storage device 503 Communication control device 504 External storage device 505 Input device 506 Output device 507 Bus 601 and 651 NAT information registration unit 602 NAT type determination request unit 603 Port information reception unit 604 and 655 Determination packet transmission and reception unit 605 Determination information transmission unit 606 Judgment result reception unit 610, 610b Judgment result acquisition unit 652 Judgment cooperation request reception unit 653 Automatic port forward command unit 654 Port information transmission unit 656 Judgment information transmission unit 657 Judgment result reception unit 658 Judgment target NAT information notification unit 701 NAT information reception Unit 702 Determination Request Reception Unit 703 Determination Cooperation Request Transmission Unit 704 Port Information Transmission / Reception Unit 705 Determination Information Reception Unit 706 NAT Information Management Unit 707 Cooperation Terminal Selection Unit 708 NAT Type Determination Unit 709 Determination Result Transmission Unit 710 Determination Unit

Claims (15)

A communication device that communicates with a server device connected to the Internet via an upper NAT (Network Address Translation) device connected to the Internet and a first lower NAT device connected to the upper NAT device,
A determination cooperation request receiving unit that receives a determination cooperation request for requesting cooperation for determining the NAT type of the second lower NAT device connected to the upper NAT device, transmitted from the server device;
When the determination cooperation request reception unit receives the determination cooperation request, the first lower NAT device is instructed to execute port forwarding for transferring a packet received by the first lower NAT device to the communication device. A port forward command,
A port information transmission unit that transmits port information including a port number used for the port forwarding to the server device;
A determination terminal that is connected to the second lower NAT device and receives a determination packet for determining the NAT type transmitted from the request terminal that has received the port information from the server device; ,
A determination information transmitting unit configured to transmit determination information used for determination of the NAT type obtained based on the determination packet received by the determination packet receiving unit; Further, the IP address and port number of the second lower NAT device indicated in the determination packet received by the determination packet receiving unit are passed through the third lower NAT device connected to the upper NAT device. The communication apparatus according to claim 1, further comprising: a determination target NAT information notification unit that notifies another communication apparatus connected to the third lower NAT apparatus. Communicating with the first communication device via the Internet, an upper NAT (Network Address Translation) device connected to the Internet, and a first lower NAT device connected to the upper NAT device, and the Internet A server device that communicates with a second communication device via the upper NAT device and a second lower NAT device connected to the upper NAT device;
A connection environment information receiving unit for receiving connection environment information indicating connection environment information of the first communication device, the connection environment information including information on the first lower NAT device;
A determination request receiving unit that receives a determination request for requesting determination of the NAT type of the second lower NAT device, transmitted from the second communication device;
When the determination request is received by the determination request receiving unit, the first communication device that satisfies a predetermined standard is selected as a cooperation terminal by referring to the connection environment information received by the connection environment information receiving unit. A terminal selector,
A determination cooperation request transmission unit that transmits a determination cooperation request for requesting cooperation of determination of the NAT type to the first communication device selected by the cooperation terminal selection unit;
Port number transmitted from the first communication device that has received the request for cooperation for determination, and used for port forwarding for transferring a packet received by the first lower NAT device to the first communication device. And a port information transmitting / receiving unit that receives the received port information and transmits the received port information to the second communication device. further,
Determination information based on a determination packet transmitted / received between the second communication device that has received the port information and the first communication device, the determination information used for determining the NAT type being the first information A determination information receiving unit that receives from each of the communication device and the second communication device;
Using the determination information received by the determination information receiving unit, a NAT type determination unit for determining the NAT type;
The server apparatus according to claim 3, further comprising: a determination result transmission unit that transmits a determination result that is information indicating the NAT type determined by the NAT type determination unit to the second communication device. The connection environment information receiving unit receives the connection environment information including information indicating whether the first lower NAT device has a port forward function;
The cooperation terminal selection unit selects the first lower NAT apparatus as a cooperation terminal when the connection environment information indicates that the first lower NAT apparatus has a port forward function. Server device. A communication device that communicates with a server device connected to the Internet via an upper NAT (Network Address Translation) device connected to the Internet and a first lower NAT device connected to the upper NAT device,
A determination requesting unit for transmitting a determination request for requesting determination of the NAT type of the first lower NAT device to the server device;
Port forward for transmitting a packet received by the second lower NAT device connected to the upper NAT device to a cooperating terminal connected to the second lower NAT device, which is port information transmitted from the server device A port information receiving unit for receiving port information including a port number used for
A determination packet transmitting unit that transmits a determination packet for determining the NAT type to the cooperating terminal using the port information received by the port information receiving unit;
A determination result acquisition unit that acquires a determination result that is information indicating the NAT type obtained based on the determination packet transmitted by the determination packet transmission unit. The determination result acquisition unit
Determination information based on the determination packet transmitted by the determination packet transmitter, and a determination information transmitter for transmitting determination information used for determination of the NAT type to the server device;
The communication apparatus according to claim 6, further comprising: a determination result receiving unit that receives the determination result transmitted from the server device that has received the determination information transmitted by the determination information transmitting unit. The determination result acquisition unit
Determination information based on the determination packet transmitted by the determination packet transmission unit, the determination information used for determining the NAT type from the cooperation terminal that has received the port information, a determination information receiving unit,
The communication apparatus according to claim 6, further comprising: a NAT type determination unit configured to determine the NAT type using the determination information received by the determination information receiving unit. An upper NAT (Network Address Translation) device connected to the Internet, a first lower NAT device and a second lower NAT device connected to the upper NAT device, and a first communication device connected to the first lower NAT device A communication system comprising: a second communication device connected to the second lower NAT device; and a server device connected to the Internet,
The second communication device is
A determination requesting unit for transmitting a determination request for requesting determination of the NAT type of the second lower NAT device to the server device;
Port information transmitted from the server device, the port information receiving port information including a port number used for port forwarding for transferring a packet received by the first lower NAT device to the first communication device. A receiver,
A determination packet transmitting unit that transmits a determination packet for determining the NAT type to the first communication device using the port information received by the port information receiving unit;
A determination result acquisition unit that acquires a determination result that is information indicating the NAT type obtained based on the determination packet transmitted by the determination packet transmission unit;
The server device
Connection environment information indicating connection environments of the first communication device and the second communication device, and connection environment information for receiving connection environment information including information on the first lower NAT device and the second lower NAT device A receiver,
A determination request receiving unit that receives the determination request from the second communication device;
When the determination request is received by the determination request receiving unit, the first communication device that satisfies a predetermined standard is selected as a cooperation terminal by referring to the connection environment information received by the connection environment information receiving unit. A terminal selector,
A determination cooperation request transmission unit that transmits a determination cooperation request for requesting cooperation of determination of the NAT type to the first communication device selected by the cooperation terminal selection unit;
A port information transmission / reception unit that receives the port information transmitted from the first communication device that has received the determination cooperation request, and transmits the received port information to the second communication device;
The first communication device is
A determination cooperation request receiving unit that receives the determination cooperation request transmitted from the server device;
When the determination cooperation request is received by the determination cooperation request reception unit, a port forward instruction unit that instructs the first lower NAT device to execute the port forward;
A port information transmission unit for transmitting the port information to the server device;
A determination packet receiving unit that receives the determination packet transmitted from the second communication device that has received the port information from the server device;
A determination information transmission unit that transmits determination information used for determination of the NAT type obtained based on the determination packet received by the determination packet reception unit;
The communication system further includes a determination unit that receives the determination information transmitted from the determination information transmission unit and obtains the determination result by determining the NAT type using the received determination information,
The determination result acquisition unit acquires the determination result from the determination unit. Executed by a communication device that communicates with the server device connected to the Internet via an upper NAT (Network Address Translation) device connected to the Internet and a first lower NAT device connected to the upper NAT device. A communication method,
A determination cooperation request receiving step for receiving a determination cooperation request for requesting cooperation for determining the NAT type of the second lower NAT device connected to the upper NAT device, transmitted from the server device;
When the determination cooperation request is received in the determination cooperation request reception step, the first lower NAT device is instructed to execute port forwarding for transferring the packet received by the first lower NAT device to the communication device. A port forward instruction step;
A port information transmission step of transmitting port information including a port number used for the port forwarding to the server device;
A determination packet receiving step connected to the second lower NAT device, and receiving a determination packet for determining the NAT type transmitted from the request terminal that has received the port information from the server device; ,
A determination information transmission step of transmitting determination information used for determination of the NAT type obtained based on the determination packet received in the determination packet reception step. Communicating with the first communication device via the Internet, a Network Address Translation NAT device connected to the Internet, and a first lower NAT device connected to the upper NAT device; and the Internet; A communication method executed by a server device that communicates with a second communication device via the upper NAT device and a second lower NAT device connected to the upper NAT device,
Connection environment information indicating connection environments of the first communication device and the second communication device, and connection environment information for receiving connection environment information including information on the first lower NAT device and the second lower NAT device Receiving step;
A determination request receiving step of receiving a determination request for requesting determination of the NAT type of the second lower NAT device, transmitted from the second communication device;
When the determination request is received in the determination request reception step, the first communication device that satisfies the predetermined standard is selected as a cooperation terminal by referring to the connection environment information received in the connection environment information reception step. A terminal selection step;
A determination cooperation request transmission step of transmitting a determination cooperation request for requesting cooperation of the determination of the NAT type to the first communication device selected in the cooperation terminal selection step;
Port number transmitted from the first communication device that has received the request for cooperation for determination, and used for port forwarding for transferring a packet received by the first lower NAT device to the first communication device. A port information receiving step for receiving port information including:
A port information transmitting step of transmitting the port information received in the port information receiving step to the second communication device. Executed by a communication device that communicates with the server device connected to the Internet via an upper NAT (Network Address Translation) device connected to the Internet and a first lower NAT device connected to the upper NAT device. A communication method,
A determination requesting step for transmitting a determination request for requesting determination of the NAT type of the first lower NAT device to the server device;
Port forward for transmitting a packet received by the second lower NAT device connected to the upper NAT device to a cooperating terminal connected to the second lower NAT device, which is port information transmitted from the server device A port information receiving step for receiving port information including a port number used for
A determination packet transmission step of transmitting a determination packet for determination of the NAT type to the cooperation terminal using the port information received in the port information reception step;
A determination result acquisition step of acquiring a determination result which is information indicating the NAT type obtained based on the determination packet transmitted in the determination packet transmission step. An integrated circuit that communicates with a server device connected to the Internet via an upper NAT (Network Address Translation) device connected to the Internet and a first lower NAT device connected to the upper NAT device,
A determination cooperation request receiving unit that receives a determination cooperation request for requesting cooperation for determining the NAT type of the second lower NAT device connected to the upper NAT device, transmitted from the server device;
When the determination cooperation request reception unit receives the determination cooperation request, the first lower NAT device is instructed to execute port forwarding for transferring a packet received by the first lower NAT device to the communication device. A port forward command,
A port information transmission unit that transmits port information including a port number used for the port forwarding to the server device;
A determination terminal that is connected to the second lower NAT device and receives a determination packet for determining the NAT type transmitted from the request terminal that has received the port information from the server device; ,
An integrated circuit comprising: a determination information transmitting unit that transmits determination information used for determining the NAT type obtained based on the determination packet received by the determination packet receiving unit. Communicating with the first communication device via the Internet, an upper NAT (Network Address Translation) device connected to the Internet, and a first lower NAT device connected to the upper NAT device, and the Internet An integrated circuit that communicates with a second communication device via the upper NAT device and a second lower NAT device connected to the upper NAT device;
A connection environment information receiving unit for receiving connection environment information indicating connection environment information of the first communication device, the connection environment information including information on the first lower NAT device;
A determination request receiving unit that receives a determination request for requesting determination of the NAT type of the second lower NAT device, transmitted from the second communication device;
When the determination request is received by the determination request receiving unit, the first communication device that satisfies a predetermined standard is selected as a cooperation terminal by referring to the connection environment information received by the connection environment information receiving unit. A terminal selector,
A determination cooperation request transmission unit that transmits a determination cooperation request for requesting cooperation of determination of the NAT type to the first communication device selected by the cooperation terminal selection unit;
Port number transmitted from the first communication device that has received the request for cooperation for determination, and used for port forwarding for transferring a packet received by the first lower NAT device to the first communication device. An integrated circuit comprising: a port information transmission / reception unit that receives port information including the port information and transmits the received port information to the second communication device. An integrated circuit that communicates with a server device connected to the Internet via an upper NAT (Network Address Translation) device connected to the Internet and a first lower NAT device connected to the upper NAT device,
A determination requesting unit for transmitting a determination request for requesting determination of the NAT type of the first lower NAT device to the server device;
Port forward for transmitting a packet received by the second lower NAT device connected to the upper NAT device to a cooperating terminal connected to the second lower NAT device, which is port information transmitted from the server device A port information receiving unit for receiving port information including a port number used for
A determination packet transmitting unit that transmits a determination packet for determining the NAT type to the cooperating terminal using the port information received by the port information receiving unit;
An integrated circuit comprising: a determination result acquisition unit that acquires a determination result that is information indicating the NAT type obtained based on the determination packet transmitted by the determination packet transmission unit.

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