JP2004080703A - Inter-network communication method, and gate apparatus and terminal to be used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inter-network communication method by which the same private IP address is not allocated to a plurality of terminals in communications between private networks. <P>SOLUTION: A terminal 2 of a private network 1 requests a connection to a gateway 8 of a virtual private network (VPN) 7. The gateway 8 transmits a private IP address which is stored in a memory beforehand and is not used for communications at present to the terminal 2 of the private network 1. The terminal 2 transmits a packet to a server 9 within the VPN 7 by using the private IP address received from the gateway 8 as a transmission source address. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inter-network communication method suitable for connecting private networks via the Internet.
[0002]
[Prior art]
2. Description of the Related Art In recent years, with the advance of Internet technology, connection from a wireless (or wired) network of hot spots such as coffee shops and convenience stores to a company's VPN (Virtual Private Network) has often been made. FIG. 6 is an explanatory diagram for explaining a conventional communication method between private networks. In this figure, reference numeral 1 denotes a private network in a hot spot. In the private network 1, reference numeral 2 denotes a user terminal, 3 denotes an access point, and 4 denotes a router. Reference numeral 6 denotes a public line network (Internet), and reference numeral 7 denotes a company VPN. In the VPN 7, reference numeral 8 denotes a gateway, and reference numeral 9 denotes a server.
[0003]
Now, when user A of private network 1 accesses server 9 of VPN 7 from terminal 2,
Destination: Private IP address pS in VPN 7 of server 9
Source: Private IP address pUA of private network 1
Encapsulates the packet
Destination: Global IP address gV of gateway 8
Source: Private IP address pUA
Is transmitted from the terminal 2 (see reference numeral {circle around (1)}).
[0004]
The packet transmitted from the terminal 2 is input to the router 4 via the access point 3, and the router 4 changes the source address of the packet by the NAT function.
Source: Global IP address gR of router 4
And transmits it to the public line network 6 (see symbol {circle around (2)}). This packet is received by the gateway 8 via the public line network 6, disassembles the capsule received by the gateway 8, and transmits the packet to the server 9 indicated by the destination pS (see reference numeral {circle around (3)}).
[0005]
[Problems to be solved by the invention]
By the way, usually, the private network 1 can only access the VPN 7 via the Internet, so that security measures such as IPSec (IP Security) are required. However, since the private IP address (pUA in the figure) allocated to the user terminal 2 in the private network 1 is a private IP address unique to the store in which the network 1 is provided, when communicating using IPSec, There are the following problems:
The private IP address allocated to the user terminal may overlap with the private IP address in the VPN 7.
○ The same private IP address may be assigned to a plurality of user terminals in different private networks.
[0006]
The present invention has been made in view of such circumstances, and an object thereof is to provide an inter-network communication method in which the same private IP address is not assigned to a plurality of terminals in communication between private networks. It is in.
[0007]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and the invention according to claim 1 is a system in which a computer in a first network and a computer in a second network communicate via a public network. In the inter-network communication method used when the communication is performed, a computer of the first network makes a connection request to a gate device of the second network, and the gate device stores a private IP address stored in a memory in advance. Transmitting a private IP address that is not currently used for communication to a computer of the first network, and using the private IP address received from the gate device by the computer of the first network as a source address. Sending a packet to a computer in the second network A network communication method according to symptoms.
[0008]
According to a second aspect of the present invention, in the inter-network communication method according to the first aspect, the gate device includes a private IP address and a destination to which communication is established using the private IP address. And an address table in which the other party's global address is registered. Based on the address table, a private IP address that is not currently used for communication is detected and transmitted to a computer on the first network. Features.
[0009]
According to a third aspect of the present invention, there is provided a gate device for connecting a private network to a public line network, wherein the gate device receives a connection request from another network and has a private IP address stored in a memory in advance. A means for transmitting a private IP address which is not currently used for communication to a computer on the other network; and a means for writing a destination of the private IP address in the memory. is there.
[0010]
According to a fourth aspect of the present invention, there is provided a terminal device in a first network for transmitting data to a computer in a second network, wherein the terminal device requests a private IP address from a gate device of the second network. And a transmitting means for transmitting a packet having the private IP address received from the gate device of the second network as a source private IP address to a computer in the second network. It is.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an inter-network communication method according to an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 and 2 are explanatory diagrams for explaining an inter-network communication method according to the embodiment. In these figures, the same reference numerals are given to parts corresponding to the respective parts in FIG. 3 to 5 are flowcharts for explaining the communication method.
[0012]
If the user A of the private network 1 intends to transmit data from the terminal 2 to the server 9 of the VPN 7 (step Sa1 in FIG. 3), and if communication by IPSec has not been established (step Sa2), the VPN 7 In response, a private IP address payout request is transmitted (step Sa3; (1) in FIG. 1). This request is received by the gateway 8 (step Sb1 in FIG. 4). The gateway 8 has an address table AT (see FIG. 4) in an internal memory in advance. The address table AT stores a plurality of private IP addresses that do not overlap with the private IP addresses in the VPN 7, a user name using the address, and a destination of the address.
[0013]
Upon receiving the request from the terminal 2 of the user A, the gateway 8 selects a currently unused private IP address p1 from the address table AT (step Sb2), and pays out the selected address p1 to the user A (step Sb3; FIG. 1 (2)). Next, the gateway 8 establishes communication by the IPSec with the terminal 2 of the user A, and writes in the address table AT that the address p1 has been paid out to the user A and that the destination is the global address gR (step Sb4). ).
[0014]
The private IP address p1 transmitted from the gateway 8 is received by the terminal 2 of the user A (step Sa4 in FIG. 3). The user A receiving the address p1
Source: Private IP address p1
Destination: Private IP address pS
Is generated (step Sa5). Next, user A encapsulates packet A,
Source: Private IP address pUA
Destination: Global address gV
(Step Sa6; {circle around (3)} in FIG. 1). Then, the packet B is transmitted to the router 4 via the access point 3 (step Sa7). The router 4 changes the transmission source of the packet B to the global address gR, and transmits the packet B to the gateway 8 via the public network 6. The gateway 8 decapsulates the received packet B and transmits the packet A to the server 9 ((4) in FIG. 1).
[0015]
Next, a process in which the server 9 receiving the above-described packet A transmits a response packet to the user A will be described with reference to FIGS.
First, the server 9
Destination: Private IP address p1
Source: Private IP address pS
Is generated and transmitted to the gateway 8 ((5) in FIG. 2). The gateway 8 receives the packet A (step Sc1 in FIG. 5) and encapsulates the packet. In this case, the gateway 8 searches the address table AT to detect the destination global address gR of the private IP address p1 (Step Sc2). And
Destination: Global address gR
Source: Global address gV
Then, a packet B in which the packet A is embedded is generated (step Sc3), and transmitted to the router 4 via the public network 6 (step Sc4; (6) in FIG. 2). The router 4 changes the destination of the received packet B to the private IP address pUA, and transmits the packet B to the terminal 2 of the user A. The terminal 2 of the user A releases the encapsulation of the packet B and acquires the packet A ((7) in FIG. 2).
[0016]
Thereafter, communication is performed between the terminal 2 and the server 9 using the source address of the terminal 2 as p1. When the communication between the terminal 2 and the server 9 is completed, the gateway 8 returns the communication partner and the destination of the address p1 in the address table AT to “unused”.
[0017]
According to the above-described inter-network communication method, even when the same private IP address (for example, pUA) is assigned to a terminal in a plurality of different private networks, the same private IP address (pUA) is transmitted from the gateway instead of the assigned address. Since communication is performed using the address (p1 in the above example), communication protected by IPSec can be performed without interference. Further, even when the private IP address of a terminal accessing from another network and the private IP address of a VPN terminal or server overlap, communication can be performed without interference.
[0018]
Further, according to the communication method according to the above-described embodiment, high-speed access can be performed without concern for communication charges as compared with dial-up communication. Further, it can communicate with any server in the company using an arbitrary IP protocol.
[0019]
Note that the terminal 2, the gateway 8, and the server 9 described above are configured by a computer. The process of the operation described above is stored in a computer-readable recording medium in the form of a program, and the above-described processing is performed by reading and executing the program by the computer. The computer mentioned here includes an OS and hardware such as peripheral devices.
[0020]
【The invention's effect】
As described above, according to the present invention, there is provided an inter-network communication method used when a computer in a first network and a computer in a second network communicate via a public line network. Makes a connection request to the gate device of the second network, and the gate device is a private IP address that is stored in advance in a memory and is not currently used for communication. To the computer in the first network, and the computer in the first network transmits a packet to the computer in the network using the private IP address received from the gate device as a source address. , Same private IP Dress advantage that is never allocated to a plurality of computers are obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram for explaining an inter-network communication method according to an embodiment of the present invention, for explaining a process of transmitting data from a terminal 2 to a server 9;
FIG. 2 is an explanatory diagram for explaining the inter-network communication method, and is a diagram for explaining a process of transmitting data from a server 9 to a terminal 2;
FIG. 3 is a flowchart for explaining the inter-network communication method, and is a flowchart showing a process when the terminal 2 transmits data.
FIG. 4 is a flowchart for explaining the inter-network communication method, and is a flowchart showing an address transmission process of the gateway 8;
FIG. 5 is a flowchart for explaining the inter-network communication method, and is a flowchart showing a process in which the gateway 8 transmits data to the terminal 2;
FIG. 6 is an explanatory diagram for describing a conventional inter-network communication method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Private network 2 ... Terminal 4 ... Router 6 ... Public line network 7 ... VPN
8 ... Gateway 9 ... Server

Claims (4)

An inter-network communication method used when a computer in a first network and a computer in a second network communicate via a public line network,
A computer of the first network makes a connection request to a gate device of the second network;
The gate device transmits a private IP address that is stored in a memory in advance and is not currently used for communication to a computer of the first network;
An inter-network communication method, wherein a computer in the first network transmits a packet to a computer in the second network using a private IP address received from the gate device as a source address. The gate device has an address table in which a private IP address, a destination with which communication is established using the private IP address, and a global address of the destination are registered, and based on the address table, 2. The method according to claim 1, further comprising detecting a private IP address not currently used for communication and transmitting the detected private IP address to a computer on the first network. A gate device for connecting a private network to a public network,
Means for receiving a connection request from another network and transmitting a private IP address that is stored in advance in a memory and is not currently used for communication to a computer on the other network;
Means for writing the destination of the private IP address in the memory;
A gate device comprising: A terminal device in a first network for transmitting data to a computer in a second network,
Means for requesting a private IP address from the gate device of the second network;
Transmitting means for transmitting a packet having the private IP address received from the gate device of the second network as a source private IP address to a computer in the second network;
A terminal device comprising:

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