CN113098949A

CN113098949A - Point-to-point communication method and system and server for point-to-point communication

Info

Publication number: CN113098949A
Application number: CN202110328227.9A
Authority: CN
Inventors: 王洪文
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-03-26
Filing date: 2021-03-26
Publication date: 2021-07-09
Anticipated expiration: 2041-03-26
Also published as: CN113098949B

Abstract

The invention relates to the technical field of internet communication, in particular to a point-to-point communication method and system and a server for point-to-point communication, aiming at improving the communication efficiency among various terminals. The point-to-point communication method of the present invention includes: the first terminal sends an assistance request to a V6F server; the first terminal and the second terminal establish connection with the assistance of the V6F server. In some cases, the V6F server also notifies the first terminal and the second terminal, respectively, that a connection needs to be established via the V4F server. The two terminals acquire the public network IPv6 address or the public network IPv4 address of the opposite side through the V6F server or the V4F server, so that connection is carried out, and point-to-point communication is completed. The invention avoids the problem that the data must be forwarded through the server due to different network protocols and the limitation of various firewalls among the terminals in the prior art, thereby greatly improving the efficiency of network communication.

Description

Point-to-point communication method and system and server for point-to-point communication

Technical Field

The invention relates to the technical field of internet communication, in particular to a point-to-point communication method and system and a server for point-to-point communication.

Background

IP is a Protocol of a network layer in a TCP/IP Protocol family, and among them, an IPv4 Protocol, i.e., Internet Protocol version 4(Internet Protocol version 4), is the most widely used Internet Protocol version so far. The number of bits of the IPv4 address is 32 bits, and in recent years, due to the explosion of the internet, the demand of IP addresses is increasing, and the exhaustion of IPv4 addresses is accelerated.

In order to deal with the problem, operators adopt a large number of NAT conversion devices, so that most of user terminals accessing the Internet through the IPv4 protocol are private network addresses. The problem with this is that such accessed user terminals can actively initiate access to the public network, but it is extremely difficult to access these user terminals from the public network. Although various penetration technologies are adopted, most of the flow of various current timely communication software still needs to be forwarded by a server, so that a large number of high-performance servers need to be deployed, the cost is high, the efficiency is low, and the energy conservation and emission reduction are not facilitated.

To fundamentally solve the problem of IPv4 address exhaustion, a solution that is currently widely accepted and standardized is a gradual migration to IPv6, Internet Protocol Version 6 (Internet Protocol Version 6). The address length of IPv6 is increased from 32 bits of IPv4 to 128 bits, so that an address can be coded for each sand all over the world. However, the process of migrating from IPv4 to IPv6 still requires a considerable amount of time and is far from meeting the demand of rapid development of the internet.

Therefore, how to implement peer-to-peer communication between IPv4 users and IPv6 users, IPv4 users and IPv4 users, and IPv6 users and IPv6 users at the transition stage from IPv4 to IPv6 is a problem to be solved. In view of the above, the present invention is particularly proposed.

Disclosure of Invention

In order to solve the above problems in the prior art, the present invention provides a peer-to-peer communication method and system, and a server for peer-to-peer communication, so as to improve communication efficiency between terminals.

In a first aspect of the present invention, a peer-to-peer communication method is provided, where the method includes:

the first terminal sends an assistance request to the V6F server, wherein the assistance request comprises: the ID number of the second terminal;

the first terminal and the second terminal establish connection through the assistance of the V6F server;

and the original IP address of the V6F server is a static public network IPv6 address.

Preferably, the first terminal and the second terminal are respectively: a first V6 terminal and a second V6 terminal;

the step of establishing connection between the first terminal and the second terminal through the assistance of the V6F server includes:

the first V6 terminal receives a public network IPv6 address corresponding to the second V6 terminal sent by the V6F server;

initiating a connection request to the second V6 terminal according to the public network IPv6 address corresponding to the second V6 terminal;

wherein the original IP addresses of the first V6 terminal and the second V6 terminal are both dynamic public network IPv6 addresses.

the first V6 terminal and the second V6 terminal respectively receive the public network IPv6 address of the opposite side through the V6F server side and respectively initiate a connection request to the opposite side according to the public network IPv6 address of the opposite side;

Preferably, the destination port number of the connection request initiated by the first V6 terminal is a first port number, and the source port number is a second port number;

the destination port number of the connection request initiated by the second V6 terminal is the second port number, and the source port number is the first port number;

the first port number and the second port number are both designated by the V6F service end, or the first port number and the second port number are the same and preset at both the first V6 terminal and the second V6 terminal.

Preferably, the step of establishing a connection between the first terminal and the second terminal with the assistance of the V6F server includes:

the first terminal and the second terminal respectively receive a notification which is sent by the V6F server and needs the assistance of the V4F server, respectively acquire the public network IPv4 address and the port number of the opposite side through the V4F server, and respectively initiate a connection request to the opposite side according to the public network IPv4 address and the port number of the opposite side;

and the original IP address of the V4F server is a static public network IPv4 address.

the step of "the first terminal and the second terminal respectively receiving the notification of the need of V4F server assistance from the V6F server" includes:

the first V6 terminal receives a first notice which is sent by the V6F server and needs V4F server assistance;

the second V6 terminal receives a second notice which is sent by the V6F server and needs V4F server assistance;

wherein the first notification requiring V4F server assistance comprises: the public network IPv4 address and the first IPv6 mapping address of the V4F server side; the first IPv6 mapping address of the V4F server comprises an IPv6 prefix of a first NAT64 device and an original IP address of the V4F server; the second notification that V4F server assistance is required includes: the public network IPv4 address and the second IPv6 mapping address of the V4F server side; the second IPv6 mapping address of the V4F server comprises an IPv6 prefix of a second NAT64 device and an original IP address of the V4F server;

the step of acquiring the public network IPv4 address and the port number of the opposite party through the V4F server respectively and initiating the connection request to the opposite party according to the public network IPv4 address and the port number of the opposite party respectively comprises the following steps:

the first V6 terminal initiates a connection request to the V4F server through the first NAT64 device according to a first IPv6 mapping address of the V4F server, so that the V4F server records a source address and a source port number of the connection request as a public network IPv4 address and a port number corresponding to the first V6 terminal;

the second V6 terminal initiates a connection request to the V4F server through the second NAT64 device according to the second IPv6 mapped address of the V4F server, so that the V4F server records the source address and the source port number of the connection request as the public network IPv4 address and the port number corresponding to the second V6 terminal;

the first V6 terminal and the second V6 terminal respectively receive the public network IPv4 address and port number of the opposite party sent by the V4F service terminal;

the first V6 terminal initiates a connection request to the second V6 terminal through the first NAT64 device according to the public network IPv4 address and the port number corresponding to the second V6 terminal, where a destination address of the connection request is an IPv6 mapping address of the second V6 terminal, and an IPv6 mapping address of the second V6 terminal includes an IPv6 prefix of the second NAT64 device and a public network IPv4 address corresponding to the second V6 terminal;

the second V6 terminal initiates a connection request to the first V6 terminal through the second NAT64 device according to the public network IPv4 address and the port number corresponding to the first V6 terminal; the destination address of the connection request is an IPv6 mapping address of the first V6 terminal, and the IPv6 mapping address of the first V6 terminal includes an IPv6 prefix of the first NAT64 device and a public network IPv4 address corresponding to the first V6 terminal; wherein the content of the first and second substances,

the original IP addresses of the first V6 terminal and the second V6 terminal are both dynamic public network IPv6 addresses.

Preferably, the first terminal is a first V4 terminal and the second terminal is a first V6 terminal; or, the first terminal is a first V6 terminal and the second terminal is a first V4 terminal;

the notification that V4F server assistance is needed comprises: the public network IPv4 address and IPv6 mapping address of the V4F server side; the IPv6 mapping address of the V4F server comprises an IPv6 prefix of a third NAT64 device and an original IP address of the V4F server;

the first V4 terminal initiates a connection request to the V4F server according to the public network IPv4 address of the V4F server, so that: the V4F server records the source address and the source port number of the connection request as the public network IPv4 address and the port number corresponding to the first V4 terminal;

the first V6 terminal initiates a connection request to the V4F server through the third NAT64 device according to the IPv6 mapped address of the V4F server, so that the V4F server records the source address and the source port number of the connection request as the public network IPv4 address and the port number corresponding to the first V6 terminal;

the first V6 terminal receives a public network IPv4 address and a port number corresponding to the first V4 terminal sent by the V4F service end;

the first V4 terminal receives a public network IPv4 address and a port number corresponding to the first V6 terminal sent by the V4F service end;

the first V4 terminal initiates a connection request to the first V6 terminal through the third NAT64 device; the destination address and the port number of the connection request are the public network IPv4 address and the port number corresponding to the first V6 terminal;

the first V6 terminal initiates a connection request to the first V4 terminal through the third NAT64 device; the destination address and the port number of the connection request are respectively set as an IPv6 mapping address and a port number of the first V4 terminal before passing through the third NAT64 device, and are converted into a public network IPv4 address and a port number corresponding to the first V4 terminal after passing through the third NAT64 device; the IPv6 mapping address of the first V4 terminal includes an IPv6 prefix of the third NAT64 device and a public network IPv4 address corresponding to the first V4 terminal;

wherein the original IP address of the first V4 terminal is a dynamic IPv4 address; the original IP address of the first V6 terminal is a dynamic public network IPv6 address.

Preferably, the first terminal and the second terminal are respectively: a first V4 terminal and a second V4 terminal;

the notification that V4F server assistance is needed comprises: the public network IPv4 address of the V4F server;

the first V4 terminal and the second V4 terminal respectively initiate connection requests to the V4F server according to the public network IPv4 address of the V4F server, so that the V4F server records the source address and the source port number of the connection requests as the public network IPv4 address and the port number corresponding to the first V4 terminal and the second V4 terminal respectively;

the first V4 terminal and the second V4 terminal respectively receive the public network IPv4 address and port number of the opposite party sent by the V4F service terminal;

the first V4 terminal and the second V4 terminal respectively initiate connection requests to the opposite side according to the public network IPv4 address and the port number of the opposite side;

wherein the original IP addresses of the first V4 terminal and the second V4 terminal are both dynamic IPv4 addresses.

Preferably, before "the first terminal sends the assistance request to the V6F server", the method further includes: the first terminal and the second terminal respectively send registration information to the V6F server, so that the V6F server records the registration information and records a source address in a TCP/IP packet header of the registration information as an IPv6 public network address corresponding to the terminal sending the information;

wherein the registration information includes: the ID number and original IP address corresponding to the terminal that sent the information.

In a second aspect of the present invention, a peer-to-peer communication method is provided, where the method includes:

the V6F server receives an assistance request sent by the first terminal, wherein the assistance request comprises: the ID number of the second terminal;

the V6F server assists the first terminal to establish connection with the second terminal;

the step of "the V6F server side assisting the first terminal to establish connection with the second terminal" includes:

the V6F server sends a public network IPv6 address corresponding to the second V6 terminal to the first V6 terminal, so that the first V6 terminal initiates a connection request to the second V6 terminal according to the public network IPv6 address corresponding to the second V6 terminal;

the V6F server sends the public network IPv6 addresses of the opposite party to the first V6 terminal and the second V6 terminal respectively, so that the first V6 terminal and the second V6 terminal initiate connection requests to the opposite party according to the public network IPv6 addresses of the opposite party respectively;

Preferably, the step of "the V6F server side assisting the first terminal to establish a connection with the second terminal" includes:

the V6F server sends a notification to the first terminal and the second terminal, respectively, that V4F server assistance is needed, such that: the first terminal and the second terminal respectively acquire the public network IPv4 address and the port number of the opposite party through the V4F server side, and respectively initiate a connection request to the opposite party according to the public network IPv4 address and the port number of the opposite party;

the step of the V6F server sending a notification that V4F server assistance is needed to the first terminal and the second terminal, respectively, comprises:

the V6F server sending a first notification to the first V6 terminal that V4F server assistance is required;

the V6F server sending a second notification to the second V6 terminal that V4F server assistance is required;

the steps that the first terminal and the second terminal respectively obtain the public network IPv4 address and the port number of the opposite party through the V4F server and respectively initiate a connection request to the opposite party according to the public network IPv4 address and the port number of the opposite party comprise:

the second V6 terminal initiates a connection request to the first V6 terminal through the second NAT64 device according to the public network IPv4 address and the port number corresponding to the first V6 terminal; the destination address of the connection request is an IPv6 mapping address of the first V6 terminal, and the IPv6 mapping address of the first V6 terminal includes an IPv6 prefix of the first NAT64 device and a public network IPv4 address corresponding to the first V6 terminal;

Preferably, before the "V6F server receives the assistance request from the first terminal", the method further includes:

the V6F server receives the registration information sent by the first terminal and the second terminal, records the registration information, and records the source address in the TCP/IP packet header of the registration information as the IPv6 public network address corresponding to the terminal sending the information;

Preferably, after receiving the assistance request sent by the first terminal, the V6F server sends, according to a preset rule, a notification that the V4F server needs to assist to the first terminal and the second terminal in the step of "the V6F server assists the first terminal to establish a connection with the second terminal", or returns, to the first terminal, a public network IPv6 address corresponding to the second terminal, or sends, to the first terminal and the second terminal, a public network IPv6 address of the other party, respectively.

In a third aspect of the present invention, a server for peer-to-peer communication is provided, where the server performs the peer-to-peer communication method described above.

In a fourth aspect of the present invention, a peer-to-peer communication system is provided, where the system implements communication between terminals by using the peer-to-peer communication method described above.

Compared with the closest prior art, the invention has the following beneficial effects:

the point-to-point communication method provided by the invention comprises the following steps: the first terminal sends an assistance request to a V6F server; the first terminal and the second terminal establish connection with the assistance of the V6F server. In some cases, the V6F server may also notify the first terminal and the second terminal, respectively, that the V4F server is needed to assist in establishing the connection. Therefore, the two terminals acquire the public network IPv6 address or the public network IPv4 address of the other party through the V6F server or the V4F server, so as to connect, and thus point-to-point communication is completed. The invention realizes point-to-point interconnection and intercommunication between IPv6 terminals by taking the large environment that the number of IPv6 terminals is increased sharply at present and fully utilizing the specific public network IP address of an IPv6 access terminal through a proper auxiliary means, and simultaneously considers that part of the terminals only support an IPv4 protocol at present, and the invention also provides a method for interconnection and intercommunication between IPv4 and IPv6 terminals and between two IPv4 terminals as a perfection and supplement means for giving consideration to the part of IPv4 terminals. The invention avoids the problem that the data must be forwarded through the server due to different network protocols and the limitation of various firewalls among the terminals in the prior art, thereby greatly improving the efficiency of network communication.

The existing instant communication system is built on the IPv4 technology, but the invention relies on the IPv6 technology, mainly adopts a network method to solve the connection problem in point-to-point communication, and can effectively promote the popularization and application of the IPv6 technology. In the application of point-to-point communication such as instant communication and the like, a large amount of server resources are saved, and the energy conservation and emission reduction of a data center are facilitated.

Drawings

FIG. 1 is a schematic diagram of the main steps of a first embodiment of a peer-to-peer communication method according to the present invention;

fig. 2 is a schematic information flow diagram illustrating a first method for establishing a connection between two V6 terminals according to an embodiment of the present invention;

fig. 3 is a schematic information flow diagram illustrating a second method for establishing a connection between two V6 terminals according to an embodiment of the present invention;

fig. 4 is a schematic information flow diagram of a third method for establishing a connection between two V6 terminals according to an embodiment of the present invention;

fig. 5 is a schematic information flow diagram of a fourth method for establishing a connection between two V6 terminals according to an embodiment of the present invention;

fig. 6 is a schematic information flow diagram illustrating a method for establishing a connection between a V4 terminal and a V6 terminal according to an embodiment of the present invention;

fig. 7 is a schematic information flow diagram illustrating a method for establishing a connection between two V4 terminals according to an embodiment of the present invention.

Detailed Description

Preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only for explaining the technical principle of the present invention, and are not intended to limit the scope of the present invention.

It should be noted that the terms "first" and "second" in the description of the present invention are used for convenience of description only and do not indicate or imply relative importance of the devices, elements or parameters, and therefore should not be construed as limiting the present invention.

The 'V6F server' mentioned in the embodiment of the invention is a server based on an IPv6 protocol, and the original IP address of the server is a static public network IPv6 address; the 'V4F server' is a server based on IPv4 protocol, and the original IP address is a static public network IPv4 address; the terminal refers to a computer host, a mobile phone, an IPAD or an Internet of things terminal and the like. In the following embodiments, terminals are divided into V6 terminals and V4 terminals according to different protocols of original IP addresses (addresses before being translated by devices such as NAT44 or NAT 64). The original IP address of the V6 terminal is a dynamic public network IPv6 address, and the original IP address of the V4 terminal is a dynamic IPv4 address.

The point-to-point communication method of the invention creatively solves the problem of point-to-point communication between two V6 terminals, between two V4 terminals and between a V6 terminal and a V4 terminal by means of a V6F service terminal and a V4F service terminal with static addresses in a public network.

The general idea of the peer-to-peer communication method in the following embodiments is: each terminal sends registration information to the V6F server in real time when the original IP address of the terminal changes, so that the V6F server records the ID number and the original IP address corresponding to the terminal, and the V6F server simultaneously obtains the source address (possibly an address after being converted by the NAT device) in the TCP/IP packet header of the registration information as the public network IPv6 address of the terminal. After the registration is completed, if a terminal (first terminal) wants to perform peer-to-peer communication with another terminal (second terminal), a supplementary request including at least the ID number of the second terminal may be sent to the V6F server. After the V6F server receives the request for assistance, it decides how to assist the two terminals to establish connection according to preset rules. If the V6F server considers that the V4F server is needed for assistance, the notification that the V4F server is needed is sent to the two terminals respectively, then the two terminals obtain the public network IPv4 address and the port number of the opposite party through the V4F server respectively (usually after being converted by equipment such as NAT44 and NAT 64), and then initiate a connection request to the opposite party according to the public network IPv4 address and the port number of the opposite party respectively. If the V6F server considers that the V4F server assistance is not needed, the public network IPv6 address of the second terminal is returned to the first terminal so that the first terminal can be connected with the second terminal according to the address, or the public network IPv6 addresses of the opposite party are respectively sent to the two terminals so that the two terminals respectively initiate connection to the opposite party.

The preset rule may be a rule preset in the V6F server for deciding what action to perform next, for example, a connection is to be established between the V4 terminal and the V4 terminal, or between the V4 terminal and the V6 terminal, and the V6F server notifies the two terminals that the V4F server is needed for assistance. For the case of establishing a connection between the V6 terminal and the V6 terminal, the present invention provides four different embodiments, one or more of which may be preset to be performed according to a specific network environment in practical applications.

Fig. 1 is a schematic diagram of main steps of a peer-to-peer communication method according to a first embodiment of the present invention. As shown in FIG. 1, the method of the present embodiment includes steps S10-S20:

step S10, the first terminal sends an assistance request to the V6F server, where the assistance request includes: the ID number of the second terminal;

and step S20, the first terminal and the second terminal establish connection with the assistance of the V6F server side.

Wherein, the original IP address of the V6F server is a static public network IPv6 address.

In an alternative embodiment, before step S10, the method further includes a step of sending, by the two terminals, registration information to the V6F server in real time when the original IP address changes:

and step S5, the first terminal and the second terminal respectively send the registration information to the V6F server, so that the V6F server records the registration information and records the source address in the TCP/IP packet header of the registration information as the IPv6 public network address corresponding to the terminal sending the information. Wherein, the registration information includes: the ID number and original IP address corresponding to the terminal that sent the information.

Specifically, the first terminal sends registration information to the V6F server, so that the V6F server records the registration information and records a source address in a TCP/IP packet header of the registration information as an IPv6 public network address corresponding to the first terminal; and the second terminal sends the registration information to the V6F server, so that the V6F server records the registration information and records the source address in the TCP/IP packet header of the registration information as the IPv6 public network address corresponding to the second terminal.

For clarity, the following description will be made on the communication methods between two V6 terminals, between two V4 terminals, and between a V6 terminal and a V4 terminal, respectively, and in fig. 2 to 7, arrows indicate the flow of information, where solid arrows indicate that information can be sent without passing through the NAT64 device, and dotted arrows indicate that information can be sent without passing through the NAT64 device. For simplicity, the specific content of the information is not indicated, and only the step number for delivering the information is indicated at the position of each arrow near the beginning.

Fig. 2 is a schematic information flow diagram of a first method for establishing a connection between two V6 terminals according to an embodiment of the present invention. As shown in fig. 2, the first terminal and the second terminal in the present embodiment are a first V6 terminal and a second V6 terminal, respectively. The communication method of the embodiment adopts a method for unidirectionally initiating connection by a first V6 terminal, and includes steps a10-a 30:

step a10, the first V6 terminal sends an assistance request to the V6F server, the assistance request includes: the ID number of the second V6 terminal;

step A20, the first V6 terminal receives the public network IPv6 address corresponding to the second V6 terminal sent by the V6F service end;

step A30, the first V6 terminal initiates a connection request to the second V6 terminal according to the public network IPv6 address corresponding to the second V6 terminal;

the original IP addresses of the first V6 terminal and the second V6 terminal are dynamic public network IPv6 addresses.

Fig. 3 is a schematic information flow diagram illustrating a second method for establishing a connection between two V6 terminals according to an embodiment of the present invention. As shown in fig. 3, the first terminal and the second terminal in the present embodiment are a first V6 terminal and a second V6 terminal, respectively. The communication method of this embodiment adopts a method of initiating connection bidirectionally, that is, two terminals respectively initiate connection to each other, and includes steps B10-B30:

step B10, the first V6 terminal sends an assistance request to the V6F server, the assistance request includes: ID number of the second V6 terminal.

And step B20, the first V6 terminal and the second V6 terminal respectively receive the public network IPv6 addresses of the opposite party through the V6F service terminal.

Specifically, a first V6 terminal receives a public network IPv6 address of a second V6 terminal through a V6F server; the second V6 terminal receives the public network IPv6 address of the first V6 terminal through the V6F service.

And step B30, the first V6 terminal and the second V6 terminal respectively initiate connection requests to the opposite side according to the public network IPv6 address of the opposite side.

Specifically, the first V6 terminal initiates a connection request to the second V6 terminal according to the public network IPv6 address of the second V6 terminal; the second V6 terminal initiates a connection request to the first V6 terminal according to the public network IPv6 address of the first V6 terminal.

Fig. 4 is a schematic information flow diagram of a third method for establishing a connection between two V6 terminals according to an embodiment of the present invention. As shown in fig. 4, the first terminal and the second terminal in the present embodiment are a first V6 terminal and a second V6 terminal, respectively. The communication method of the present embodiment adopts a bidirectional cross-connect initiation method, which includes steps C10-C30:

the specific contents of the steps C10-C30 are the same as the steps B10-B30 in the second method, and are not repeated herein. The difference is that the third method is a special case, or preferred embodiment, of the second method. In the face of a complex network environment, the third approach makes it easier to establish a connection between two terminals.

In this embodiment, a destination port number of a connection request initiated by a first V6 terminal is a first port number, and a source port number is a second port number; the destination port number of the connection request initiated by the second V6 terminal is the second port number, and the source port number is the first port number; the first port number and the second port number are both specified by the V6F server. For example, the destination port number and the source port number of the first V6 terminal are 2000 and 3000, respectively, and the destination port number and the source port number of the second terminal are 3000 and 2000, respectively. Alternatively, the first port number and the second port number are the same and are preset at both the first V6 terminal and the second V6 terminal. For example, the port numbers are both 5000, and thus, the port numbers can be preset in both terminals, or can be specified by the V6F server.

The embodiments of fig. 2-4 all rely on the assistance of the V6F server to establish a connection between two terminals. In some specific cases, the V6F server finds that it needs to rely on the assistance of the V4F server to establish a connection after receiving the assistance request from the first terminal. In this case, the first terminal and the second terminal respectively receive the notification that the V6F server needs the V4F server to assist, and respectively obtain the public network IPv4 address and the port number of the opposite party through the V4F server, and respectively initiate a connection request to the opposite party according to the public network IPv4 address and the port number of the opposite party. Since the V4F server has a static public network IPv4 address, the address can be preset in the V6F server to inform the terminal when needed. This is explained in more detail below with reference to the embodiments of fig. 5-7.

Fig. 5 is a schematic information flow diagram of a fourth method for establishing a connection between two V6 terminals according to an embodiment of the present invention. As shown in fig. 5, the first terminal and the second terminal in the present embodiment are a first V6 terminal and a second V6 terminal, respectively, and the communication method includes steps D10-D80:

step D10, the first V6 terminal sends an assistance request to the V6F server, where the assistance request includes: ID number of the second V6 terminal.

In step D20, the first V6 terminal receives the first notification from the V6F server that requires the V4F server to assist.

Wherein the first notification requiring V4F server assistance comprises: a public network IPv4 address and a first IPv6 mapping address of a V4F server side; the first IPv6 mapped address of the V4F service includes an IPv6 prefix of the first NAT64 device and the original IP address of the V4F service.

In step D30, the second V6 terminal receives the second notification from the V6F server that the V4F server is needed to assist.

Wherein, the second notification that the V4F server assistance is required comprises: a public network IPv4 address and a second IPv6 mapping address of the V4F server side; the second IPv6 mapped address of the V4F service includes the IPv6 prefix of the second NAT64 device and the original IP address of the V4F service.

It should be noted that the first NAT64 device and the second NAT64 device are both designated by the V6F service side, and may or may not be the same NAT64 device.

And D40, the first V6 terminal initiates a connection request to the V4F server through the first NAT64 device according to the first IPv6 mapping address of the V4F server, so that the V4F server records the source address and the source port number of the connection request as the public network IPv4 address and the port number corresponding to the first V6 terminal.

And D50, the second V6 terminal initiates a connection request to the V4F server through the second NAT64 device according to the second IPv6 mapping address of the V4F server, so that the V4F server records the source address and the source port number of the connection request as the public network IPv4 address and the port number corresponding to the second V6 terminal.

In step D60, the first V6 terminal and the second V6 terminal respectively receive the public network IPv4 address and port number of the opposite party from the V4F service end.

Specifically, the first V6 terminal receives the public network IPv4 address and port number of the second V6 terminal sent by the V4F service end; the second V6 terminal receives the public network IPv4 address and port number of the first V6 terminal from the V4F service end.

And D70, the first V6 terminal initiates a connection request to the second V6 terminal through the first NAT64 device according to the public network IPv4 address and the port number corresponding to the second V6 terminal.

The destination address of the connection request is an IPv6 mapping address of the second V6 terminal, and the IPv6 mapping address of the second V6 terminal includes an IPv6 prefix of the second NAT64 device and a public network IPv4 address corresponding to the second V6 terminal.

And D80, the second V6 terminal initiates a connection request to the first V6 terminal through the second NAT64 device according to the public network IPv4 address and the port number corresponding to the first V6 terminal.

The destination address of the connection request is an IPv6 mapping address of the first V6 terminal, and the IPv6 mapping address of the first V6 terminal includes an IPv6 prefix of the first NAT64 device and a public network IPv4 address corresponding to the first V6 terminal.

In this embodiment, the original IP addresses of the first V6 terminal and the second V6 terminal are both dynamic public network IPv6 addresses.

Fig. 6 is a schematic information flow diagram illustrating a method for establishing a connection between a V4 terminal and a V6 terminal according to an embodiment of the present invention. As shown in fig. 6, the first terminal in this embodiment is a first V4 terminal, and the second terminal is a first V6 terminal; alternatively, the first terminal is a first V6 terminal and the second terminal is a first V4 terminal. The communication method comprises steps E10-E80:

step E10, the first V4 terminal sends an assistance request to the V6F server, where the assistance request includes: the ID number of the first V6 terminal; alternatively, the first V6 terminal sends an assistance request (not shown in the figure) to the V6F server, where the assistance request includes: ID number of the first V4 terminal.

It is well known to those skilled in the art that the first V4 terminal needs to communicate with the V6F server through one NAT64 device, referred to herein as a fourth NAT64 device.

Step E20, the first V4 terminal and the first V6 terminal respectively receive the notification that the V4F server assistance is needed from the V6F server.

The notification that the V4F server assistance is needed includes: and the public network IPv4 address and the IPv6 mapping address of the V4F service end. The IPv6 mapped address of the V4F service includes the IPv6 prefix of the third NAT64 device and the original IP address of the V4F service.

The third NAT64 device is also designated by the V6F server, and may be the same as or different from the first NAT64 device and the second NAT64 device mentioned in the previous embodiments.

Step E30, the first V4 terminal initiates a connection request to the V4F server according to the public network IPv4 address of the V4F server, so that: and the V4F server records the source address and the source port number of the connection request as the public network IPv4 address and the port number corresponding to the first V4 terminal.

The first V4 terminal is usually going through several NAT44 devices when connecting to the V4F server, according to the actual network environment, so the source address and source port number recorded by the V4F server are usually translated.

Step E40, the first V6 terminal initiates a connection request to the V4F server through the third NAT64 device according to the IPv6 mapped address of the V4F server, so that the V4F server records the source address and the source port number of the connection request as the public network IPv4 address and the port number corresponding to the first V6 terminal.

In step E50, the first V6 terminal receives the public network IPv4 address and the port number corresponding to the first V4 terminal sent by the V4F service end.

In step E60, the first V4 terminal receives the public network IPv4 address and the port number corresponding to the first V6 terminal sent by the V4F service end.

In step E70, the first V4 terminal initiates a connection request to the first V6 terminal through the third NAT64 device.

The destination address and the port number of the connection request are the public network IPv4 address and the port number corresponding to the first V6 terminal. Here, "the public network IPv4 address and port number corresponding to the first V6 terminal" is converted from the original IP address and port in the third NAT64 device when the first V6 terminal is connected to the V4F service terminal. Therefore, the first V4 terminal may continue to initiate a connection to the first V6 terminal through the third NAT64 device using the mapping relationship.

In step E80, the first V6 terminal initiates a connection request to the first V4 terminal through the third NAT64 device.

The destination address and the port number of the connection request are respectively set as an IPv6 mapping address and a port number of the first V4 terminal before passing through the third NAT64 device, and are converted into a public network IPv4 address and a port number corresponding to the first V4 terminal after passing through the third NAT64 device; the IPv6 mapped address of the first V4 terminal includes an IPv6 prefix of the third NAT64 device and a public network IPv4 address corresponding to the first V4 terminal.

In this embodiment, the original IP address of the first V4 terminal is a dynamic IPv4 address; the original IP address of the first V6 terminal is a dynamic public network IPv6 address.

Fig. 7 is a schematic information flow diagram illustrating a method for establishing a connection between two V4 terminals according to an embodiment of the present invention. As shown in fig. 7, the first terminal and the second terminal in this embodiment are respectively: a first V4 terminal and a second V4 terminal. The communication method includes steps F10-F60:

in step F10, the first V4 terminal sends an assistance request to the V6F server, where the assistance request includes: ID number of the second V4 terminal. As is well known to those skilled in the art, communication between the first V4 terminal and the V6F server needs to go through one NAT64 device, referred to herein as the fifth NAT64 device.

In step F20, the first V4 terminal and the second V4 terminal respectively receive the notification of V4F server assistance from the V6F server.

Here, the notification that V4F server assistance is required includes: and the public network IPv4 address of the V4F server. It is well known to those skilled in the art that the communication between the second V4 terminal and the V6F server also needs to go through a NAT64 device, referred to herein as the sixth NAT64 device.

Step F30, the first V4 terminal initiates a connection request to the V4F server according to the public network IPv4 address of the V4F server, so that the V4F server records the source address and the source port number of the connection request as the public network IPv4 address and the port number corresponding to the first V4 terminal.

Step F40, the second V4 terminal initiates a connection request to the V4F server according to the public network IPv4 address of the V4F server, so that the V4F server records the source address and the source port number of the connection request as the public network IPv4 address and the port number corresponding to the second V4 terminal.

In step F50, the first V4 terminal and the second V4 terminal respectively receive the public network IPv4 address and port number of the opposite party from the V4F service side.

Specifically, a first V4 terminal receives a public network IPv4 address and a port number corresponding to a second V4 terminal sent by a V4F service end; and the second V4 terminal receives the public network IPv4 address and the port number corresponding to the first V4 terminal sent by the V4F service end.

And step F60, the first V4 terminal and the second V4 terminal respectively initiate connection requests to the opposite side according to the public network IPv4 address and the port number of the opposite side.

Specifically, the first V4 terminal initiates a connection request to the second V4 terminal according to the public network IPv4 address and port number corresponding to the second V4 terminal; and the second V4 terminal initiates a connection request to the first V4 terminal according to the public network IPv4 address and the port number corresponding to the first V4 terminal.

In this embodiment, the original IP addresses of the first V4 terminal and the second V4 terminal are both dynamic IPv4 addresses.

In the above embodiments of the peer-to-peer communication method, all terminals are used as execution subjects, and based on the same design concept, the present invention also provides an embodiment in which the V6F server is used as an execution subject, which is described in detail below.

The invention provides a second embodiment of a point-to-point communication method. The main steps of this embodiment include:

in SS10, the V6F server receives an assistance request from the first terminal, where the assistance request includes: the ID number of the second terminal.

In step SS20, the V6F server assists the first terminal to establish a connection with the second terminal.

In this embodiment, the original IP address of the V6F server is a static public network IPv6 address.

In an alternative embodiment, step SS10 is preceded by the step of receiving registration information of two terminals by the V6F server:

in step SS5, the V6F server receives the registration information from the first terminal and the second terminal, records the registration information, and records the source address in the TCP/IP header of the registration information as the IPv6 public network address corresponding to the terminal sending the information.

Wherein, the registration information includes: the ID number and original IP address corresponding to the terminal that sent the information.

Specifically, the V6F server receives registration information sent by the first terminal, records the registration information, and records a source address in a TCP/IP packet header of the registration information as an IPv6 public network address corresponding to the first terminal; the V6F server receives the registration information sent by the second terminal, records the registration information, and records the source address in the TCP/IP packet header of the registration information as the IPv6 public network address corresponding to the second terminal.

The invention also provides an embodiment of a first method for establishing connection between two V6 terminals in the point-to-point communication method. The first terminal and the second terminal in this embodiment are a first V6 terminal and a second V6 terminal, respectively, and the communication method in this embodiment adopts a method in which a first V6 terminal initiates a connection in a single direction, including steps AA10-AA 20:

in step AA10, the V6F server receives an assistance request from the first V6 terminal, where the assistance request includes: ID number of the second V6 terminal.

In step AA20, the V6F server sends the public network IPv6 address corresponding to the second V6 terminal to the first V6 terminal, so that the first V6 terminal initiates a connection request to the second V6 terminal according to the public network IPv6 address corresponding to the second V6 terminal.

The invention also provides an embodiment of a second method for establishing connection between two V6 terminals in the point-to-point communication method. The first terminal and the second terminal in this embodiment are the first V6 terminal and the second V6 terminal, respectively, and the communication method in this embodiment is a method of initiating connection bidirectionally, that is, two terminals initiate connection to each other, respectively, and includes steps BB10-BB 20:

in step BB10, the V6F server receives an assistance request from the first V6 terminal, where the assistance request includes: ID number of the second V6 terminal.

In step BB20, the V6F server sends the public network IPv6 addresses of the opposite party to the first V6 terminal and the second V6 terminal, respectively, so that the first V6 terminal and the second V6 terminal initiate connection requests to the opposite party according to the public network IPv6 addresses of the opposite party, respectively.

The invention also provides an embodiment of a third method for establishing connection between two V6 terminals in the point-to-point communication method. The first terminal and the second terminal in this embodiment are a first V6 terminal and a second V6 terminal, respectively, and the communication method in this embodiment adopts a bidirectional cross-originating connection method, which includes steps CC10-CC 20:

the specific contents of steps CC10-CC20 correspond to steps BB10-BB20 in the above second method, and are not described herein again.

Different from the second method, in this embodiment, the destination port number of the connection request initiated by the first V6 terminal is the first port number, and the source port number is the second port number; the destination port number of the connection request initiated by the second V6 terminal is the second port number, and the source port number is the first port number; the first port number and the second port number are both specified by the V6F server. Alternatively, the first port number and the second port number are the same and are preset at both the first V6 terminal and the second V6 terminal.

The above embodiments using the V6F server as the execution subject rely on the assistance of the V6F server to establish the connection between two terminals. In some specific cases, the V6F server finds that it needs to rely on the assistance of the V4F server to establish a connection after receiving the assistance request from the first terminal. In this case, the V6F server sends a notification to the first and second terminals, respectively, that V4F server assistance is needed, such that: the first terminal and the second terminal respectively acquire the public network IPv4 address and the port number of the opposite side through the V4F server side, and respectively initiate a connection request to the opposite side according to the public network IPv4 address and the port number of the opposite side. Since the V4F server has a static public network IPv4 address, the address can be preset in the V6F server to inform the terminal when needed. The following is a detailed description.

The invention also provides an embodiment of a fourth method for establishing connection between two V6 terminals in the point-to-point communication method. The first terminal and the second terminal in this embodiment are a first V6 terminal and a second V6 terminal, respectively, and the communication method of this embodiment requires V4F service side assistance, and includes steps DD10-DD 20:

in step DD10, the V6F server receives an assistance request from the first V6 terminal, where the assistance request includes: ID number of the second V6 terminal.

In step DD20, the V6F server sends a notification that V4F server assistance is needed to the first V6 terminal and the second V6 terminal, respectively, so that: the first V6 terminal and the second V6 terminal respectively acquire the public network IPv4 address and the port number of the opposite side through the V4F server side, and respectively initiate a connection request to the opposite side according to the public network IPv4 address and the port number of the opposite side. The method comprises the following specific steps:

(1) the V6F server sends a first notification that V4F server assistance is needed to a first V6 terminal, the notification comprising: a public network IPv4 address and a first IPv6 mapping address of a V4F server side; the first IPv6 mapped address of the V4F service includes an IPv6 prefix of the first NAT64 device and the original IP address of the V4F service.

(2) The V6F server sends a second notification that V4F server assistance is needed to a second V6 terminal, the notification comprising: a public network IPv4 address and a second IPv6 mapping address of the V4F server side; the second IPv6 mapped address of the V4F service includes the IPv6 prefix of the second NAT64 device and the original IP address of the V4F service.

(3) The first V6 terminal initiates a connection request to the V4F server through the first NAT64 device according to the first IPv6 mapping address of the V4F server, so that the V4F server records the source address and the source port number of the connection request as the public network IPv4 address and the port number corresponding to the first V6 terminal.

(4) And the second V6 terminal initiates a connection request to the V4F server through the second NAT64 device according to the second IPv6 mapping address of the V4F server, so that the V4F server records the source address and the source port number of the connection request as the public network IPv4 address and the port number corresponding to the second V6 terminal.

(5) The first V6 terminal and the second V6 terminal respectively receive the public network IPv4 address and the port number of the opposite party sent by the V4F service end.

(6) And the first V6 terminal initiates a connection request to the second V6 terminal through the first NAT64 device according to the public network IPv4 address and the port number corresponding to the second V6 terminal. The destination address of the connection request is an IPv6 mapping address of the second V6 terminal, and the IPv6 mapping address of the second V6 terminal includes an IPv6 prefix of the second NAT64 device and a public network IPv4 address corresponding to the second V6 terminal.

(7) The second V6 terminal initiates a connection request to the first V6 terminal through the second NAT64 device according to the public network IPv4 address and the port number corresponding to the first V6 terminal; the destination address of the connection request is an IPv6 mapping address of the first V6 terminal, and the IPv6 mapping address of the first V6 terminal includes an IPv6 prefix of the first NAT64 device and a public network IPv4 address corresponding to the first V6 terminal.

The invention also provides a method embodiment for establishing connection between the V6 terminal and the V4 terminal in the point-to-point communication method. The first terminal in this embodiment is a first V4 terminal and the second terminal is a first V6 terminal; alternatively, the first terminal is a first V6 terminal and the second terminal is a first V4 terminal. The communication method of the embodiment needs the assistance of the V4F server, and comprises the steps EE10-EE 20:

step EE10, the V6F server receives an assistance request from the first V6 terminal, where the assistance request includes: the ID number of the first V4 terminal; or, the V6F server receives an assistance request from the first V4 terminal, where the assistance request includes: ID number of the first V6 terminal.

Step EE20, the V6F server sends a notification to the first V6 terminal and the first V4 terminal, respectively, that V4F server assistance is required, so that: the first V6 terminal and the first V4 terminal respectively acquire the public network IPv4 address and the port number of the opposite side through the V4F server side, and respectively initiate a connection request to the opposite side according to the public network IPv4 address and the port number of the opposite side. The method comprises the following specific steps:

(1) the V6F server sends notifications to the first V6 terminal and the first V4 terminal, respectively, that V4F server assistance is needed. The notification includes: the public network IPv4 address and the IPv6 mapping address of the V4F server side, and the IPv6 mapping address of the V4F server side comprises an IPv6 prefix of the third NAT64 device and an original IP address of the V4F server side.

(2) The first V4 terminal initiates a connection request to the V4F server according to the public network IPv4 address of the V4F server, so that the V4F server records the source address and the source port number of the connection request as the public network IPv4 address and the port number corresponding to the first V4 terminal.

(3) And the first V6 terminal initiates a connection request to the V4F server through the third NAT64 device according to the IPv6 mapping address of the V4F server, so that the V4F server records the source address and the source port number of the connection request as the public network IPv4 address and the port number corresponding to the first V6 terminal.

(4) And the first V6 terminal receives the public network IPv4 address and the port number corresponding to the first V4 terminal sent by the V4F service end.

(5) And the first V4 terminal receives the public network IPv4 address and the port number corresponding to the first V6 terminal sent by the V4F service end.

(6) The first V4 terminal initiates a connection request to the first V6 terminal through the third NAT64 device. The destination address and the port number of the connection request are the public network IPv4 address and the port number corresponding to the first V6 terminal.

(7) The first V6 terminal initiates a connection request to the first V4 terminal through the third NAT64 device. The destination address and the port number of the connection request are respectively set as an IPv6 mapping address and a port number of the first V4 terminal before passing through the third NAT64 device, and are converted into a public network IPv4 address and a port number corresponding to the first V4 terminal after passing through the third NAT64 device; the IPv6 mapped address of the first V4 terminal includes an IPv6 prefix of the third NAT64 device and a public network IPv4 address corresponding to the first V4 terminal.

In this embodiment, the original IP address of the first V4 terminal is a dynamic IPv4 address, and the original IP address of the first V6 terminal is a dynamic public network IPv6 address.

The invention also provides a method embodiment for establishing connection between two V4 terminals in the point-to-point communication method. The first terminal and the second terminal in the present embodiment are a first V4 terminal and a second V4 terminal, respectively. The communication method of the embodiment requires V4F server side assistance, and comprises the steps FF10-FF 20:

in step FF10, the V6F server receives an assist request from the first V4 terminal, where the assist request includes: ID number of the second V4 terminal.

Step FF20, the V6F server sends notification to the first V4 terminal and the second V4 terminal, respectively, that V4F server assistance is needed, so that: the first V4 terminal and the second V4 terminal respectively acquire the public network IPv4 address and the port number of the opposite side through the V4F server side, and respectively initiate a connection request to the opposite side according to the public network IPv4 address and the port number of the opposite side. The method comprises the following specific steps:

(1) the V6F server sends notifications to the first V4 terminal and the second V4 terminal, respectively, that V4F server assistance is needed. The notification that the V4F server assistance is needed includes: and the public network IPv4 address of the V4F server.

(2) The first V4 terminal and the second V4 terminal respectively initiate connection requests to the V4F server according to the public network IPv4 address of the V4F server, so that the V4F server records the source address and the source port number of the connection requests as the public network IPv4 address and the port number corresponding to the first V4 terminal and the second V4 terminal respectively.

(3) The first V4 terminal and the second V4 terminal respectively receive the public network IPv4 address and the port number of the opposite party sent by the V4F service end.

(4) And the first V4 terminal and the second V4 terminal respectively initiate connection requests to the opposite side according to the public network IPv4 address and the port number of the opposite side.

In the invention, after the V6F server receives the auxiliary request sent by the first terminal, according to a preset rule, in the step of the V6F server assisting the first terminal to establish a connection with the second terminal, a notification that the V4F server is needed to assist is sent to the first terminal and the second terminal, or a public network IPv6 address corresponding to the second terminal is returned to the first terminal, or a public network IPv6 address of the other party is sent to the first terminal and the second terminal, respectively. The specific rule may be preset according to the network environment where each terminal is located.

Although the foregoing embodiments describe the steps in the above sequential order, those skilled in the art will understand that, in order to achieve the effect of the present embodiments, the steps may not be executed in such an order, and may be executed simultaneously (in parallel) or in an inverse order, and these simple variations are within the scope of the present invention.

Based on the above method embodiment taking the V6F server as the execution subject, the invention also provides an embodiment of the server for point-to-point communication. The server of this embodiment is configured to perform the peer-to-peer communication method described above.

The invention also provides an embodiment of a point-to-point communication system, based on the same technical idea as the above method embodiment. The system of the embodiment adopts the point-to-point communication method to realize the communication between the terminals.

Those of skill in the art will appreciate that the method steps of the examples described in connection with the embodiments disclosed herein may be embodied in electronic hardware, computer software, or combinations of both, and that the components and steps of the examples have been described above generally in terms of their functionality in order to clearly illustrate the interchangeability of electronic hardware and software. Whether such functionality is implemented as electronic hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

So far, the technical solutions of the present invention have been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can fall into the protection scope of the invention.

Claims

1. A method of point-to-point communication, the method comprising:

2. The method of point-to-point communication according to claim 1,

the first terminal and the second terminal are respectively: a first V6 terminal and a second V6 terminal;

wherein the content of the first and second substances,

3. The method of point-to-point communication according to claim 1,

wherein the content of the first and second substances,

4. The method of point-to-point communication according to claim 3,

the destination port number of the connection request initiated by the first V6 terminal is a first port number, and the source port number is a second port number;

5. The method of point-to-point communication according to claim 1,

6. The method of point-to-point communication according to claim 5,

wherein the content of the first and second substances,

the first notification requiring V4F server assistance comprises: the public network IPv4 address and the first IPv6 mapping address of the V4F server side; the first IPv6 mapping address of the V4F server comprises an IPv6 prefix of a first NAT64 device and an original IP address of the V4F server;

the second notification that V4F server assistance is required includes: the public network IPv4 address and the second IPv6 mapping address of the V4F server side; the second IPv6 mapping address of the V4F server comprises an IPv6 prefix of a second NAT64 device and an original IP address of the V4F server;

7. The method of point-to-point communication according to claim 5,

the first terminal is a first V4 terminal and the second terminal is a first V6 terminal; alternatively, the first and second electrodes may be,

the first terminal is a first V6 terminal and the second terminal is a first V4 terminal;

wherein the content of the first and second substances,

the original IP address of the first V4 terminal is a dynamic IPv4 address;

the original IP address of the first V6 terminal is a dynamic public network IPv6 address.

8. The method of point-to-point communication according to claim 5,

the first terminal and the second terminal are respectively: a first V4 terminal and a second V4 terminal;

wherein the content of the first and second substances,

the original IP addresses of the first V4 terminal and the second V4 terminal are both dynamic IPv4 addresses.

9. The peer-to-peer communication method according to any of claims 1-8, wherein before the first terminal sends the assistance request to the V6F server, the method further comprises:

the first terminal and the second terminal respectively send registration information to the V6F server, so that the V6F server records the registration information and records a source address in a TCP/IP packet header of the registration information as an IPv6 public network address corresponding to the terminal sending the information;

wherein the content of the first and second substances,

the registration information includes: the ID number and original IP address corresponding to the terminal that sent the information.

10. A method of point-to-point communication, the method comprising:

11. The method of point-to-point communication according to claim 10,

wherein the content of the first and second substances,

12. The method of point-to-point communication according to claim 10,

wherein the content of the first and second substances,

13. The method of point-to-point communication according to claim 12,

14. The method of point-to-point communication according to claim 10,

15. The method of point-to-point communication according to claim 14,

wherein the content of the first and second substances,

16. The method of point-to-point communication according to claim 14,

wherein the content of the first and second substances,

the original IP address of the first V4 terminal is a dynamic IPv4 address;

17. The method of point-to-point communication according to claim 14,

wherein the content of the first and second substances,

18. The peer-to-peer communication method according to any one of claims 10 to 17, wherein before the V6F server receives the assistance request from the first terminal, the method further comprises:

wherein the content of the first and second substances,

19. The peer-to-peer communication method according to any of claims 10-17, wherein after receiving the assistance request from the first terminal, the V6F server sends a notification that V4F server assistance is needed to the first terminal and the second terminal, respectively, in the step of "the V6F server assists the first terminal to establish connection with the second terminal", or returns a public network IPv6 address corresponding to the second terminal to the first terminal, or sends a public network IPv6 address of the other party to the first terminal and the second terminal, respectively, according to a preset rule.

20. A server for peer-to-peer communication, wherein the server performs the peer-to-peer communication method according to any one of claims 10 to 19.

21. A peer-to-peer communication system, characterized in that the system uses the peer-to-peer communication method according to any of claims 1-19 to realize communication between terminals.