JP2012133494A - P2p communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To overcome a problem of NAT when making a P2P connection available using general protocols such as a mail protocol and HTTP.SOLUTION: A P2P communication system achieves a P2P connection between an external terminal and a first internal terminal which cannot traverse an NAT of the P2P connection which is connected to an external network through the NAT, through a second internal terminal which can traverse the NAT of the P2P connection. When the second internal terminal receives a request or a response from the external terminal by lamination recognition information which is recognition information in the external network of the second internal terminal to which recognition information in the internal network of the first terminal is added, it forwards the request or the response to the first internal terminal. On the other hand, when the second internal terminal receives a response or a request to the request or the response from the first internal terminal, it forwards the response or the request to the external terminal.

Description

  The present invention relates to a communication system for connecting terminals to each other by peer-to-peer (hereinafter also referred to as P2P).

  In realizing the P2P connection, the problem of NAT traversal must be cleared. In a hybrid type existing P2P connection method such as STUN or TURN, a server or super node manages terminal information and teaches each terminal information necessary for P2P connection to realize NAT-over-P2P connection.

  In addition, when a terminal such as UPnP / IGD, which can open a NAT traversal communication path only by a terminal, tries to connect using P2P that is not a server type, the user manually prepares the communication path and stores the information. Connect using it. For example, as disclosed in Patent Document 1, there is a technology that exceeds NAT using a mail protocol.

Japanese Patent Laid-Open No. 2008-300239

  However, since the server-type P2P connection described above needs to implement a dedicated protocol that can interact with the server in all terminals, like a PC, DTV, recorder, etc. that can communicate using the above protocol, It can only be used with digital network terminals that allow manufacturers and users to use free communication software. In other words, it is difficult for a terminal such as a mobile phone whose communication is restricted by a carrier mainly for security (hereinafter also referred to as a restricted terminal) to use a P2P-specific protocol or application as a service. .

In addition, among the above examples, the P2P connection method using a server such as STUN or TURN is impossible in principle when a failure occurs in the server network or the server provider terminates the service for some reason. become. For this time, a serverless (pure) P2P connection service capable of P2P connection only on the user side is also provided, but there is a drawback that it is not possible to exceed multi-stage NAT.
Further, in the server type P2P connection, it is necessary to register a certain amount of unique information on the terminal side in the server, which is not preferable in terms of information leakage.

  The present invention has been made in order to solve such problems. For example, the restricted terminal can be configured to be able to connect to P2P using a general-purpose protocol such as a mail protocol or HTTP. It is intended to provide a communication system that can be overcome.

  That is, according to the present invention, there is provided a first terminal configured on an external terminal on an external network and on an internal network connected to the external network via a NAT, so that NAT traversal with the default protocol in a P2P connection is impossible. This is for P2P connection with an internal terminal using the predetermined protocol.

  A second internal terminal on the internal network and configured to allow NAT traversal with the default protocol in the P2P connection includes a relay agent, and the relay agent is connected to the external network of the second internal terminal. When the request or response from the external terminal is received by the stack identification information obtained by adding the identification information in the internal network of the first terminal to the identification information of the first terminal, the request or response is transferred to the first internal terminal, When a response or request to the request or response is received from the first internal terminal, the external terminal and the first internal terminal are connected by P2P connection by transferring the response or request to the external terminal. It is a communication system.

  According to the present invention, there is provided a first terminal configured on an external terminal on an external network and on an internal network connected to the external network via a NAT so that NAT traversal with the default protocol in a P2P connection is impossible. A P2P connection with an internal terminal via the second internal terminal on the internal network and configured to allow NAT traversal with the default protocol in a P2P connection; When the second internal terminal receives a request or response from the external terminal by means of layered identification information obtained by adding identification information in the internal network of the first terminal to identification information in the external network of the second internal terminal, While transferring the request or response to the first internal terminal, the response to the request or response from the first internal terminal Upon receiving the request, the by transferring the response or the request to an external terminal, a P2P communication method characterized by P2P connection between the external terminal and the first internal terminal.

  In addition, the present invention is a computer program for P2P communication that exhibits the function as the relay agent.

  In this case, since a standard protocol such as http can be used as it is for the terminal, P2P connection is possible even with a mobile terminal in which communication at a special port is blocked or a terminal under a firewall. Further, in a P2P connection method that does not use a server, P2P connectivity can be ensured even in an environment where UPnPNAT traversal cannot be used.

  In order to share the stack identification information, the second internal terminal transmits identification information in its external network to the external terminal and the internal terminal using a mail protocol different from the default protocol, and the first internal terminal May generate the stack identification information based on the identification information, and transmit the stack identification information to the external terminal by a mail protocol.

According to the present invention described above, since the P2P connection can be established between the first internal terminal and the external terminal that cannot traverse NAT without using a server by a predetermined protocol, it is not necessary to implement a dedicated protocol. It can also be used on restricted terminals such as.
Further, unlike server type P2P connection, it is close to pure type P2P connection, which is preferable in terms of information leakage, and the effect is remarkable when applied to a small scale P2P connection system.

1 is an overall configuration diagram of a P2P communication system in an embodiment of the present invention. It is a functional block diagram of the normal terminal in the same embodiment. It is a functional block diagram of a restriction terminal in the embodiment. FIG. 7 is a scheduling diagram illustrating a procedure in which restricted terminal 600 and normal terminal 400 perform P2P communication in the embodiment. In the embodiment, it is the conceptual diagram which showed notionally the state in which the restriction | limiting terminal 600 and the normal terminal 400 are performing P2P communication. FIG. 7 is a scheduling diagram illustrating a procedure in which the normal terminal 500 and the normal terminal 400 perform P2P communication in the embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the communication system according to the present embodiment is configured such that terminals 300, 400, 500, and 600 can be connected via an external network (WAN, for example, the Internet). Each part will be described below.

  As shown in FIG. 2, the terminals 300, 400, and 500 are IP network terminals that can install and operate various communication applications such as personal computers and digital network devices. Hereinafter, these three types of terminals are also referred to as normal terminals.

  The normal terminals 300, 400, 500 physically include a CPU, a memory, a communication device, a display device, an input unit (not shown), etc., and according to a program installed in the memory, the CPU and others The peripheral devices cooperate with each other to perform functions as the server function unit 101, the client function unit 102, the relay agent 103, and the like.

  The server function unit 101 is a software component that plays a server-like role of receiving a connection from a communication partner when performing P2P communication.

  The client function unit 102 is a software component that requests connection to the communication partner server program 101 and performs a client role when performing P2P communication.

  The relay agent 103 is a software component having a function of providing a connection path as if the P2P connection is possible instead when the normal P2P connection cannot be performed.

  Among these normal terminals, the terminal 300 is connected to the Internet via, for example, a NAT router 310 that supports the UPnP / IGD function and the Internet service provider 320, and is connected to the outside of the router 310 by its own UPnP / IGD function. It is possible to acquire an address and generate a URL in an external network (Internet) and to perform NAT setting, that is, NAT traversal is possible.

  The terminal 500 is directly connected to the Internet via the Internet service provider 520, and can originally grasp its own IP address without using NAT. The terminal 500 corresponds to an external terminal referred to in the claims.

  Although the terminal 400 is connected to the Internet via the NAT router 410 and the Internet service provider 420 that do not support the UPnP / IGD function, the terminal 400 cannot generate the URL of the Internet and cannot perform the NAT setting. That is, it is impossible to cross NAT.

  Note that the terminal 300 and the terminal 400 have local addresses and are configured to be connectable via an internal network (LAN). The terminal 300 corresponds to the second internal terminal referred to in the claims, and the terminal 400 corresponds to the first internal terminal referred to in the claims.

  The terminal 600 is, for example, a mobile phone, and has substantially the same configuration as the normal terminal. However, the terminal 600 is a terminal that cannot perform free packet communication due to carrier and manufacturer restrictions. Specifically, data communication is possible only with a network using a WEB standard protocol such as HTTP or a standard mail protocol. The terminal 600 corresponds to an external terminal in the claims, and is also referred to as a restricted terminal 600 below in order to distinguish it from the terminal 500.

  In this restricted terminal 600, as shown in FIG. 3, a restricted client function unit 201 is installed. The restricted client function unit 201 is a software component that can perform standard communication, such as a WEB browser that performs communication instead, in the restricted terminal 600 that cannot operate a client software component dedicated to P2P.

  Thus, in the present embodiment, by using the relay agent 103, the restricted terminal 600 or the normal terminal 500 and the normal terminal 400 that cannot traverse the NAT are connected by the P2P connection via the normal terminal 300 that can traverse the NAT. I can do it. This will be specifically described below with reference to FIG.

  Here, as a premise, it is assumed that each normal terminal has a GUI based on WEB content that can be accessed from a portable terminal such as the restricted terminal 600 having only a WEB browser. Also, it is assumed that the e-mail addresses of the terminals are known to each other, and communication via e-mail using a mail protocol is possible between the terminals.

(1) First, the normal terminal 300 sets a NAT setting that reaches the router 310, for example, using the UPnP / IGD function, and generates a URL. Specifically, the terminal 300 acquires the external address of the router 310 by the UPnP / IGD function. Then, “http (s): // IP address of router 310 (or DDNS name): NAT set port number” is generated as the URL. Then, this terminal 300 transmits this URL, which is connection information to itself, to other terminals by e-mail. As a result, connection from another terminal to the terminal 300 by using the HTTP protocol which is a standard protocol becomes possible.

(2) The terminal 400 that cannot set NAT and cannot generate its own URL makes P2P connection based on the URL address information received from the terminal 300.

(3) Then, the terminal 400 requests the terminal 300 to transfer for connection to the restricted terminal 600. The direction of the TCP connection at this time is the direction from the terminal 400 to the terminal 300 as shown in the figure.

(4) Upon receiving this transfer request, the relay agent 103 of the terminal 400 generates a URL for transfer for the terminal 400. For example, assuming that the DDNS name of the router 310 is “foo.ne.jp” and the port number of the NAT setting is “80”, the terminal 400 grasps the URL of the terminal 300 by the e-mail in (1). Therefore, when the host name of the terminal 400 is “hoge”, the relay agent of the terminal 400 adds its own identification information to the URL of the terminal 300, for example, “http (s): // foo. A transfer URL such as “ne.jp:80/hoge/” is generated.

(5) The relay agent 103 in the terminal 400 connects to the server function unit 101 of the terminal 400 and the relay agent 103 of the terminal 300, and prepares for transfer by notifying the transfer URL. Note that the transfer URL may be generated by the terminal 300 and notified to the terminal 400.

(6) Then, the terminal 400 transmits the transfer URL generated in the above (4) to the restricted terminal 600 by e-mail.

(7) The restricted terminal 600 connects to the relay agent of the terminal 300 according to the transfer URL received from the terminal 400 and issues a GET request or the like.

(8) The relay agent of the terminal 300 sees the transfer URL “hoge”, determines that the request is for the terminal 400, and transfers the request to the relay agent 103 of the terminal 400.

(9) The relay agent of the terminal 400 transfers the request to the server of the terminal 400 and receives a response. Thereafter, the response is transferred to the restricted terminal 600 via the relay agent of the terminal 300.

  FIG. 5 schematically shows the above-described configuration. The terminal 300 interposed between the terminal 600 and the terminal 400 mediates the P2P connection between the terminal 600 and the terminal 400, but the direction of the TCP connection of the connection is directed toward both terminals 300. It can be seen that the terminal 300 has a completely different function from a proxy server or the like that is an existing mediation server.

Next, P2P connection between the terminal 500 and the terminal 400 will be described with reference to FIG.
(1) The terminals 300 and 500 transmit their own P2P connectable IP address or DDNS name and port number to each terminal using electronic mail.

(2) Since the terminal 400 cannot provide NAT traversal by itself, the terminal 400 performs relay setting in the same manner as (2) to (6) in FIG. That is, the relay agent of terminal 300 prepares a port for transfer of terminal 400. The terminal 400 again notifies the address of the router 310 and the port number prepared by the relay agent of the terminal 400 as a pair of P2P connectable IP address (DDNS name) and port.

(3) At this time, when the terminal 300 requests connection to the terminal 400, since the connection between the relay agents has already been completed, the communication path is used.

(4) When the terminal 500 requests connection to the terminal 600, the relay agent of the terminal 500 connects to the relay agent of the terminal 300.

(5) Since the relay agent of the terminal 300 can determine that the port connected from the terminal 500 is prepared for the transfer of the terminal 400, all requests using this connection are transferred to the relay agent of the terminal 400. To do.

(6) The relay agent of the terminal 400 transfers the transferred request to its own server and returns a response to the relay agent of the terminal 300. The relay agent of terminal 300 further returns a response to terminal 500 to complete the transfer.

Thus, according to the present embodiment configured as described above, since a standard protocol such as http can be used as it is for the terminal, a P2P connection can be established even with a mobile terminal that is blocked from communication at a special port or a terminal under a firewall. Is possible.
Further, in a P2P connection method that does not use a server, P2P connectivity can be ensured even in an environment where UPnPNAT traversal cannot be used.
Moreover, it is not necessary to modify the existing server and client software (the server function unit and the client function unit) in each terminal, and it can be realized simply by adding a relay agent. For example, in the case of HTTP, from the WEB browser (restricted client function unit) 201 installed in the restricted terminal 600 and the server function unit 101 installed in the normal terminals 300, 400, 500, the connection direction is Since there is no change from normal communication, existing software can be used as it is.

  The present invention is not limited to the above embodiment. For example, the default protocol may be a general-purpose or standard protocol other than the HTTP protocol, and various modifications can be made without departing from the spirit of the protocol.

500, 600 ... external terminal 400 ... first internal terminal 300 ... second internal terminal 103 ... relay agent

Claims (5)

An external terminal on an external network and a first internal terminal on the internal network connected to the external network via NAT and configured to be unable to traverse NAT with the default protocol in a P2P connection For P2P connection with protocol,
A second internal terminal on the internal network and configured to allow NAT traversal with the default protocol in a P2P connection comprises a relay agent;
This relay agent
When a request or response from the external terminal is received by stacking identification information obtained by adding identification information in the internal network of the first terminal to identification information in the external network of the second internal terminal, the first internal terminal While transferring a request or response, when receiving a response or request to the request or response from the first internal terminal, the external terminal and the first internal terminal are transferred by transferring the response or request to the external terminal. A P2P communication system characterized by P2P connection.   The P2P communication system according to claim 1, wherein the external terminal is a portable terminal that is restricted to only a mail protocol and the default protocol as data communication. An external terminal on an external network, and a first internal terminal on an internal network connected to the external network via a NAT and configured so that NAT traversal in the default protocol in a P2P connection is impossible. A P2P connection with the default protocol via a second internal terminal on the internal network and configured to allow NAT traversal with the default protocol in the P2P connection;
The second internal terminal is
When a request or response from the external terminal is received by stacking identification information obtained by adding identification information in the internal network of the first terminal to identification information in the external network of the second internal terminal, the first internal terminal While transferring a request or response, when receiving a response or request to the request or response from the first internal terminal, the external terminal and the first internal terminal are transferred by transferring the response or request to the external terminal. A P2P communication method characterized by performing P2P connection. The second internal terminal transmits identification information on its external network to the external terminal and the internal terminal using a mail protocol different from the default protocol,
4. The P2P communication method according to claim 3, wherein the first internal terminal generates the stack identification information based on the identification information, and transmits the stack identification information to the external terminal by a mail protocol.   A computer program for P2P communication that exhibits the function as a relay agent according to claim 1.