JP4631531B2 - Network system, connection establishment method, node device, etc. - Google Patents

Description

  The present invention relates to a network system including a plurality of node devices that can be connected to each other via a network, and more particularly to a technical field such as a method in which one node device establishes a connection with another node device.

  In order for a terminal such as a personal computer to connect to a target server and receive provision of information on a network constructed by the Internet or the like, generally, the server's IP (Internet Protocol) address and port number (listening) Port number).

  Here, the port number is an auxiliary address provided below the IP address on the network. In order to distinguish the type of application (software) (that is, the connection port from the application layer to the transport layer). Meaning) used.

  Patent Document 1 discloses that a terminal acquires in advance an IP address and port number of a target server from a connection mediation server, and connects to the server using the IP address and port number of the server.

  By the way, in recent years, a peer-to-peer (P2P) type network system in which clients (node devices) are interconnected via a network and exchange information is attracting attention. Examples are Napster and Gnutella, which are famous for music distribution.

In such a P2P type network system, various content data such as movies and music are distributed and stored in many node devices, and for example, a known distributed hash table (hereinafter referred to as DHT (Distributed Hash Table)). A node device can acquire the content data by acquiring the location of the desired content data, that is, the IP address of the node device storing the content data. It has become.
JP 2004-194016 A

  However, in the conventional P2P type network system, the IP address of the node device storing the desired content data can be efficiently acquired by the search method using DHT, but the standby port number is efficiently acquired. The method to do is not established.

  As an example of a method of acquiring the port number, a method in which a node device connects to a port number introduction (inquiry) server such as the connection mediation server and inquires and acquires a standby port number of the target node device is considered. However, with this method, every time content data is searched, an inquiry is made to the port number introduction server, and it takes time to acquire the standby port number, and the port number introduction server is burdened. growing.

  On the other hand, if the standby port numbers of all the node devices are the same, the port number introduction server is not necessary, but this is not desirable in terms of security.

  The present invention has been made in view of the above problems and the like, and does not require a port number introduction server, and can improve the security and obtain a standby port number more efficiently. It is an object to provide a connection establishment method, a node device, and the like.

In order to solve the above problem, the invention according to claim 1 is a network system including a plurality of node devices that can be connected to each other via a network. uniquely assigned identification information to the relay equipment required for connection, and the identification information storage means for storing a common function in the network system, and the common function assigned thereto or the relay device with a first port number generating means for generating a first port number, and the listener port setting means for setting a port number waiting a first port number that the generated, to connect to the other of the node device The other node device or the relay device necessary for the other node device to connect to the network. An identification information acquisition unit for acquiring identification information assigned to the common function, using the acquired identification information, and the second port number generating means for generating a second port number, which is the product Connection establishment means for establishing a connection with the other node device based on a second port number.

  According to the present invention, the standby port number of each node device is generated by setting the identification information uniquely assigned to each node device using a common function, so that security can be improved, and each The node device can efficiently obtain the standby port number of the node device of the connection partner using the common function without referring to the port number introduction server.

  According to a second aspect of the present invention, in the network system according to the first aspect, the first port number generation means and the second port number generation means are the ports generated using the common function. When the number overlaps with a well-known port number, the port number is a number obtained as a result of performing a predetermined operation on the generated port number so as not to overlap with the well-known port number. And

  According to the present invention, an appropriate standby port number can be set without overlapping with the well-known port number.

  According to a third aspect of the present invention, in the network system according to the first aspect, common functions in the respective node devices are periodically updated, and standby port numbers in the respective node devices are periodically set. It is characterized by being reworked.

  According to the present invention, security can be further improved.

  According to a fourth aspect of the present invention, in the network system according to the first aspect, a plurality of the common functions are stored in advance in the storage means of each of the node devices, and the plurality of common functions are stored in the respective node devices. The first port number generation means obtains one common function among a plurality of common functions stored in the storage means at regular time intervals, and generates the first port number using the same function, The standby port setting means resets the generated first port number as the standby port number, and the second port number generation means in each of the node devices sets the standby port number by the standby port setting means. The common function to be used is changed in synchronization with resetting.

  According to the present invention, since the common function used is changed at regular time intervals, the security can be further improved.

According to a fifth aspect of the present invention, in the network system according to the first aspect, the common function is periodically distributed to the respective node devices via the network and stored in the storage unit. The first port number generation means in each of the node devices generates the first port number using the distributed common function, and the standby port setting means has the generated first port number. Is set as the standby port setting means, and the second port number generation means in each of the node devices is used in synchronization with the resetting of the standby port number by the standby port setting means. It is characterized by changing the function.

  According to the present invention, since the common function used is changed at regular time intervals, the security can be further improved.

  According to a sixth aspect of the present invention, in the network system according to any one of the first to fifth aspects, the common function is a hash function.

  According to the present invention, the standby port numbers of the respective node devices are as different as possible and are distributed, so that the security can be further improved.

  According to a seventh aspect of the present invention, in the network system according to any one of the first to sixth aspects, the identification information is an IP address or a node ID.

  According to the present invention, in an environment where each node device can easily acquire the IP address or node ID of the node device to which it is connected (for example, a network system using a DHT in which the IP address and node ID of the node device are registered). It is particularly effective.

The invention according to claim 8 is a node device in a network system including a plurality of node devices that can be connected to each other via a network, and is unique to a relay device necessary for itself or itself to connect to the network. assigned identification information, and storage means for storing a common function in the network system, and the common function, using said identification information assigned to itself or the relay device, the first port number A first port number generating means to be generated; a standby port setting means for setting the generated first port number as a standby port number; and when connecting to another node device, the other node device or the other The identification information uniquely assigned to the relay device necessary for connecting the node device to the network is collected. An identification information acquiring means for, with the common function, using said acquired identification information, and the second port number generating means for generating a second port number, based on the second port number the generated Connection establishing means for establishing a connection with the other node device.

A program according to a ninth aspect causes a computer to function as the node device according to the eighth aspect.

The invention according to claim 10 is a connection establishment method in a network system including a plurality of node devices connectable to each other via a network, and each of the node devices is connected to the network by itself or by itself. Storing the identification information uniquely assigned to the relay device necessary for this purpose and the common function in the network system, and the respective node devices are assigned to the common function and to itself or the relay device. Generating a first port number using the identification information , a step in which each of the node devices sets the generated first port number as a standby port number, and the other node devices. When connecting, the other node device or the relay device necessary for the other node device to connect to the network A step of acquiring a uniquely assigned identification information to the first node apparatus by using said common functions, and the acquired identification information, and generating a second port number, the 1 The node device comprises a step of establishing a connection with the other node device based on the generated second port number.

  According to the present invention, the standby port number of each node device is generated by setting the identification information uniquely assigned to each node device by a common function, so that security can be improved and each The node device can efficiently obtain the standby port number of the node device of the connection partner using the common function without referring to the port number introduction server.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, the best embodiment of the invention will be described based on the drawings. The embodiment described below is an embodiment when the present invention is applied to a content distribution system.

[1. Content distribution system configuration]
First, a schematic configuration and the like of the content distribution system will be described with reference to FIG.

  FIG. 1 is a diagram illustrating an example of a connection mode of each node device in the content distribution system according to the present embodiment.

  As shown in the lower frame 101 of FIG. 1, IX (Internet eXchange) 3, ISP (Internet Service Provider) 4, DSL (Digital Subscriber Line) line operator (device) 5, FTTH (Fiber To The Home) line A network (real-world network) 8 such as the Internet is constructed by a business operator (device) 6, a router (not shown), a communication line (for example, a telephone line, an optical cable, etc.) 7, and the like.

  The content distribution system S includes a plurality of node devices 1a, 1b, 1c... 1x, 1y, 1z... That can be connected to each other via such a network 8, and is peer-to-peer. Network system.

  Each node device 1a, 1b, 1c... 1x, 1y, 1z... Has a unique manufacturing number and IP (Internet Protocol) address (hereinafter simply referred to as “IP address” as identification information). Indicating an IP address). Note that the serial number and IP address are not duplicated among the plurality of node devices 1. In the following description, the node devices 1a, 1b, 1c... 1x, 1y, 1z.

  In the content distribution system S, an overlay network 9 as shown in the upper frame 100 of FIG. 1 is constructed by a specific algorithm, for example, an algorithm using DHT. That is, the overlay network 9 means a network that forms a virtual link formed by using the existing network 8.

  In the present embodiment, it is assumed that the overlay network 9 is constructed by an algorithm using DHT, and the node 1 arranged on the overlay network 9 is referred to as a node 1 participating in the overlay network 9. Participation in the overlay network 9 is performed when a node 1 that has not yet participated sends a participation request to an arbitrary node 1 that has already participated.

  Each node 1 participating in the overlay network 9 has a node ID, and the node ID is, for example, a common hash function (for example, a hash function such as SHA-1) using an IP address or a serial number. (Hereinafter, referred to as “node ID hash function”) is a hashed value (for example, the bit length is 160 bits), and is distributed in a uniform manner in one ID space. The node ID obtained (hashed) by the hash function has a very low probability of having the same value if the IP address or the manufacturing number is different. Description is omitted.

  Further, each node 1 participating in the overlay network 9 holds a DHT. In this DHT, a plurality of pieces of route information to other nodes 1, that is, node IDs and IP addresses of other nodes 1 that are appropriately separated in the node ID space are registered. Such DHT is given when the node 1 participates in the overlay network 9. In the content distribution system S, since the node 1 participates in or leaves the overlay network 9, it is confirmed whether or not the DHT needs to be updated regularly (for example, at intervals of several tens of minutes to several hours). The update information is transmitted via a route registered in the DHT of the other node 1. This makes it possible to keep the DHT up to date. Since the DHT generation method is known, detailed description thereof is omitted.

  Further, content (for example, movies, music, etc.) data as distribution information is distributed and stored (stored) in any of the plurality of nodes 1 participating in the overlay network 9. For example, content data of a movie with a title XXX is stored in the node 1a, while content data of a movie with a title YYY is stored in the node 1b. Distributed and stored in a plurality of nodes 1. Certain content data is not necessarily stored in one node 1, and the same content data can be stored in a plurality of nodes 1. Each of these content data is given a content name (title) and the like.

  Further, location information (for example, IP address of a node (hereinafter referred to as “content holder”) where content data is stored) indicating the location of each content data distributed and stored in this way is also displayed in the overlay network 9. Are distributed and stored in a plurality of nodes 1 participating in. For example, the content name of some content data (or the first few bytes of the content data may be hashed) by the above-mentioned hash function for node ID (that is, in the same ID space as the hash value of the IP address of node 1) Arrangement), the content data in the node 1 (hereinafter referred to as “root node”) having the node ID closest to the hash value (the hash value becomes the content ID) (for example, the higher digit matches more). Will be stored. That is, even if the same content data (content ID is the same) is stored in a plurality of content holders, location information (such as IP addresses of the plurality of content holders) indicating the location of the content data. Can be managed by one root node.

  Then, a node used by a user who wants to acquire (download) certain content data (hereinafter referred to as “user node”) acquires location information indicating the location of the content data from the root node, and based on this, acquires a content holder. And the content data is acquired.

  FIG. 2 is a diagram illustrating an example of DHT routing when a user node acquires location information in a DHT node ID space.

  In the example of FIG. 2, the user node 1a sends a query (inquiry information) to which the content ID of the desired content data is added to the other nodes 1, so that the query is transmitted through some DHT routing. A node (hereinafter referred to as “relay node”) is reached to a root node 1b that stores location information indicating the location of the content data. Each of the relay nodes 1n compares the content ID added to the received query with the node ID registered in the DHT, and specifies the node 1 to be transferred next (for example, upper digits of the content ID) The IP address of the node 1 corresponding to the node ID with which the IDs match is specified), and the query is transferred there. In this way, the user node 1a acquires (receives) location information from the root node 1b, and acquires (receives) the content data from the content holder 1c.

  Note that a query transfer method using DHT from the user node 1a to the root node 1b is well-known, for example, “Pastry”, and thus further detailed description is omitted. Further, the location information may be acquired (received) from the node 1 that caches the same location information as the root node until the query reaches the root node.

  In such a content distribution system S, each of the nodes 1 is a hash function (hereinafter referred to as “port number hash function”) that is a common function among the nodes 1 in the content distribution system S. For example, the port number (first port number) corresponding to the IP address assigned to itself may be generated using the same hash function or a different hash function. (For example, the IP address is applied to the port number hash function, and the lower 16 bits of the obtained value (4 digits in hexadecimal (maximum value “FFFFh”) is used as the port number)), and the port number is set as the standby port number. It is supposed to be set. When a certain node 1 connects to another node 1 using an IP address, the port number corresponding to the IP address of the other node 1 (second Port number) (for example, the IP address is applied to the hash function for the port number, and the lower 16 bits (4 digits in hexadecimal) of the obtained value is used as the port number), and the port number is the destination port number. The connection with the node 1 is established.

  The target to be applied to the port number hash function is not limited to the IP address, and any identification information that is unique to each node 1 and can be acquired from other nodes 1 can be applied. For example, a node ID or a MAC address may be used.

  Also, when the node 1 to which a private IP address is assigned is connected to an intranet of an organization such as a company, and connected to the Internet (global network), a NAT (Network Address Translation) function as its own relay device When the installed router converts the private IP address in the IP packet into a global IP address and communicates (that is, the node 1 exists inside the router with the NAT function), the private IP address overlaps with the other node 1 In some cases, it cannot be used as a target for the port number hash function. In such a case, the global IP address assigned to the NAT function-equipped router (not shown) as a relay device necessary for the node 1 to connect to the Internet is used as the unique identification information of the node 1, and the common A port number corresponding to the global IP address is generated using the hash function for the port number and set as a standby port number of the node 1 in the NAT function-equipped router. Then, the data transmitted to the standby port of the router with the NAT function is set to be transferred (port forwarding) to the node 1.

  By the way, as is well known, numbers in decimal numbers from 0 to 65535 (hexadecimal values from 0 to FFFF) are used as well-known port numbers. Of these numbers, well-known port numbers (Well-known numbers) are used. port: in other words, a reserved port number) (for example, in the case of the 25th port number, SMTP (Simple Mail Transfer Protocol) is specified), and each node 1 cannot use it freely. . Therefore, for example, when the generated port number is less than 1024 (overlapping with the well-known port number), a predetermined value is set for the generated port number so as not to overlap with the well-known port number. The number obtained as a result of the above operation is set as a standby port number (details will be described later).

[2. Node configuration]
Next, the configuration and function of the node 1 in the content distribution system S will be described with reference to FIG.

  FIG. 3 is a diagram illustrating a schematic configuration example of the node 1.

  As shown in FIG. 3, each node 1 includes a control unit 11 as a computer including a CPU having a calculation function, a working RAM, a ROM for storing various data and programs, a hash function for node ID, a port A storage unit 12 (storage for the content data and the location information is stored) composed of an HDD or the like for storing and storing (storing) the hash function for number, the content data, the location information, the DHT, and the program (There is also a node 1 that is not performed), a buffer memory 13 that temporarily stores received content data, encoded video data (video information), audio data (audio information), and the like included in the content data are decoded (data Decoder unit 14 for decompression and decoding) and the decoded video A video processing unit 15 that performs predetermined drawing processing on the data and outputs the video signal; a display unit 16 such as a CRT or a liquid crystal display that displays video based on the video signal output from the video processing unit 15; The decoded audio data is converted into an analog audio signal by D (Digital) / A (Analog) conversion, then amplified by an amplifier and output, and the audio signal output from the audio processing unit 17 is output. A communication unit 20 for controlling communication of information between the speaker 18 that outputs sound waves, the other node 1 through the network 8, and an instruction signal corresponding to the instruction received from the user to the control unit 11 And an input unit (for example, a keyboard, a mouse, or an operation panel) 21 provided to the control unit 11 and storage 12, buffer memory 13, decoder unit 14, a communication unit 20, and the input unit 21 are connected to each other via a bus 22. As the node 1, an STB (Set Top Box) or a personal computer can be applied.

  The control unit 11 performs overall control of the entire node 1 by the CPU executing various programs stored in the storage unit 12 or the like, and the above-described user node 1a, root node 1b, content holder Any operation of 1c and relay node 1n can be performed. The control unit 11 functions as a first port number generation unit, a standby port setting unit, an identification information acquisition unit, a second port number generation unit, and a connection establishment unit according to the present invention, and performs various processes described later. It has become.

  The program may be downloaded from a predetermined server on the network 8, for example, or may be recorded on a recording medium such as a CD-ROM and read via a drive of the recording medium. It may be.

[3. Operation of content distribution system]
Next, the operation of the content distribution system S will be described separately for the first and second embodiments.

(Embodiment 1)
First, the operation of the content distribution system S according to the first embodiment will be described with reference to FIGS. In the first embodiment, the IP address is an object to be applied to the port number hash function.

  FIG. 4 is a flowchart showing a standby port number setting process in the node control unit 11, FIG. 5 is a flowchart showing a content data search process in the user node control unit 11, and FIG. FIG. 7 is a flowchart illustrating content data search processing in the node control unit 11. FIG. 7 is a flowchart illustrating content data acquisition processing in the user node control unit 11.

  The process of FIG. 4 is started when, for example, the user operates the input unit 21 to input a request for participation in the overlay network 9, and the control unit 11 first determines that its node 1 is a NAT function-equipped router. It is determined whether or not it exists inside (step S1). When the self does not exist inside the NAT function-equipped router (step S1: N), the process proceeds to step S2, and when the self exists inside the NAT function-equipped router (step S1: Y), the process proceeds to step S6.

  In step S2, the control unit 11 hashes the IP address assigned to its own node 1 with the port number hash function, and the lower 16 bits (4 digits in hexadecimal) of the hash value obtained thereby are port numbers. (Step S2). For example, assuming that the hash value obtained by the port number hash function is “A3178692h” (the h at the end indicates a hexadecimal number), the lower 2 bytes “8692h” are extracted.

  Next, the control unit 11 determines whether or not the value extracted as the port number is less than “400h” (hexadecimal: 1024 in decimal) (step S3). Step S3: N), the value extracted as the port number is set (released) as a standby port number (step S5), and the process proceeds to step S13. On the other hand, when the extracted value is less than “400h” (step S3: Y), that is, when the extracted value overlaps with the well-known port number, the control unit 11 extracts, for example, the port number. “4E20h” (hexadecimal: 20000 in decimal) is added to the obtained value (step S4). In other words, a predetermined value is set for the generated port number so as not to overlap with the well-known port number. Is set (opened) as a standby port number (step S5), and the process proceeds to step S13.

  On the other hand, in step S6, the control unit 11 acquires the IP address of the NAT function-equipped router to which the node 1 is connected. Then, the control unit 11 hashes the acquired IP address with a port number hash function, and extracts the lower 16 bits (4 digits in hexadecimal) of the hash value obtained thereby as a port number (step S7).

  Next, as in step S3, the control unit 11 determines whether or not the value extracted as the port number is less than “400h” (step S8). If not less than “400h” (step S8: N) ), And if it is less than “400h” (step S8: Y), “4E20h” (hexadecimal: 20000 in decimal) is added to the value extracted as the port number ( Step S9) and the process proceeds to step S10.

  In step S10, the control unit 11 determines whether or not the port number obtained in step S7 or step S9 is already in use as a standby port number of another node 1 by inquiring the NAT function-equipped router. That is, it is determined whether or not there are a plurality of nodes 1 inside the NAT function-equipped router, and the port number obtained from the IP address of the NAT function-equipped router has already been set as a standby port number by another node 1. .

  If the port number obtained in step S7 or step S9 is not in use by another node 1 (step S10: N), the control unit 11 sets (releases) the port number as a standby port number. (Step S11), the process proceeds to Step S13. In this setting, a command for setting the port number of the node 1 as a standby port number is issued to the NAT function-equipped router (port forwarding setting), whereby the standby port number of the node 1 is set in the NAT function-equipped router. Is set.

  On the other hand, when the port number obtained in step S7 or step S9 is being used by another node 1 (step S10: Y), the control unit 11 displays another node on the display screen of the display unit 16, for example. 1 displays a message indicating that the port number is in use (for example, “the port number is being used by another node”) (step S12), and the process is terminated.

  In step S13, the control unit 11 acquires the IP address of an arbitrary node 1 that has already participated in the overlay network 9 (for example, it may be stored in the storage unit 12 when the node 1 is shipped, It may be acquired from a predetermined server connected to the network 3).

  Next, the control unit 11 hashes the acquired IP address with the hash function for port number, and extracts the lower 16 bits (4 digits in hexadecimal) of the hash value obtained thereby as a port number (step S14). .

  Next, the control unit 11 determines whether or not the value extracted as the port number is less than “400h” (step S15). If the value is not less than “400h” (step S15: N), the above-described extraction is performed. Establishing a connection with the arbitrary node 1 using the IP address and the port number as the destination IP address and the destination port number, respectively (step S16), and connecting the arbitrary node 1 to the overlay network 9 Participation request information indicating participation request (IP address of own node 1 as a source IP address (in the case of node 1 inside the NAT function router, private IP address (converted to a global IP address by the NTA function router) And node ID is included in the payload) (step S17) To terminate the management.

  On the other hand, if the value extracted as the port number is less than “400h” (step S15: Y), “4E20h” (hexadecimal: 20000 in decimal) is added to the value extracted as the port number. (Step S18), using this as the port number, and establishing the connection with the arbitrary node 1 using the extracted IP address and the port number as the destination IP address and the destination port number, respectively (Step S16). Then, the participation request information is transmitted to the arbitrary node 1 (step S17), and the process ends.

  As a result, the own node 1 participates in the overlay network 9 and acquires the DHT, and the IP address and node ID of the node 1 are in any one or more other nodes 1. It will be registered in DHT. In this way, all nodes 1 participating in the overlay network 9 release the value generated by the port number hash function and the IP address as the standby port number.

  In the above processing, when there are multiple nodes 1 inside the NAT function-equipped router and the generated port number is in use by another node 1, it is “used by another node” etc. However, it is also possible to set the standby port number of each node 1 so that it is not in use by other nodes 1. For example, in the above step S7, the MAC address or serial number uniquely assigned to the node 1 is hashed by the port number hash function, and the lower 16 bits (4 digits in hexadecimal) of the hash value obtained thereby are ported. A number is extracted, and after steps S8 and S9, a standby port number is set in step S11. In such a configuration, the participation request information transmitted in step S13 includes the MAC address or serial number, the node ID of the node 1, and the IP address of the NAT function-equipped router. Alternatively, the set of the serial number and the IP address of the router equipped with the NAT function is registered in the DHT in any one or more other nodes 1 together with the node ID (in this case, the other node 1 stores the MAC address or the serial number). The standby port number is obtained by hashing with the port number hash function). Further, the node ID uniquely given to the node 1 is hashed by the port number hash function, and the lower 16 bits (4 digits in hexadecimal) of the hash value obtained thereby are extracted as the port number, and step S8, Through step 9, the standby port number may be set in step S11.

  Next, the process of FIG. 5 is started when the user in the user node 1a operates the input unit 21 to input a content data search instruction, for example, and the control unit 11 is stored in the storage unit 12, for example. The content list data is read out and displayed on the display screen of the display unit 16 (step S21). In this content list, information such as content names of a plurality of content data is described.

  In such a display state, when the user operates the input unit 21 and selects a desired content name, the control unit 11 responds to this (step S22: Y), and uses the selected content name for the node ID. The content ID is obtained by hashing with a hash function (step S23).

  Next, the control unit 11 refers to the DHT and extracts, for example, the IP address of the other node 1 (the other node 1 to which the query is to be transmitted) corresponding to the node ID with which the most significant digit of the content ID matches ( Step S24).

  Next, the control unit 11 hashes the extracted IP address with the port number hash function, and extracts the lower 16 bits (4 digits in hexadecimal) of the hash value obtained thereby as a port number (step S25).

  Next, the control unit 11 determines whether or not the value extracted as the port number is less than “400h” (step S26). If the value is not less than “400h” (step S26: N), the above-described extraction is performed. Establishing a connection with the other node 1 using the IP address and the port number as the destination IP address and the destination port number, respectively (step S27), and the query to which the content ID obtained in step S23 is added Is transmitted to the other node 1 (step S28), and the process ends.

  On the other hand, if the value extracted as the port number is less than “400h” (step S26: Y), “4E20h” (hexadecimal: 20000 in decimal) is added to the value extracted as the port number. (Step S29), using this as the port number, and establishing the connection with the other node 1 using the extracted IP address and the port number as the destination IP address and the destination port number, respectively (Step S27). Then, the query (including its own IP address) to which the content ID obtained in step S23 is added is transmitted to the other node 1 (step S28), and the process is terminated.

  Next, the processing of FIG. 6 is started when a query transmitted from the user node 1a is received. First, the control unit 11 determines that the node 1 has a content ID added to the received query. For example, whether or not the node ID of its own node 1 is closest to the content ID (for example, the higher-order digits match more). Step S31).

  When the node 1 is not the root node 1b (step S31: N), the control unit 11 refers to the DHT, for example, a node in which the upper few digits (for example, the upper second digit) of the content ID match. The IP address of the other node 1 (other node 1 to which the query is transferred) corresponding to the ID is extracted (step S32).

  Next, the control unit 11 hashes the extracted IP address with the port number hash function, and extracts the lower 16 bits (4 digits in hexadecimal) of the hash value obtained thereby as a port number (step S33).

  Next, the control unit 11 determines whether or not the value extracted as the port number is less than “400h” (step S34). If the value is not less than “400h” (step S34: N), the above-described extraction is performed. Establishing a connection with the other node 1 using the IP address and the port number as the destination IP address and the destination port number, respectively (step S35), and transmitting the received query to the other node 1 (Transfer) (step S36), and the process ends.

  On the other hand, if the value extracted as the port number is less than “400h” (step S34: Y), “4E20h” (hexadecimal: 20000 in decimal) is added to the value extracted as the port number. (Step S37), using this as the port number, and establishing the connection with the other node 1 using the extracted IP address and the port number as the destination IP address and the destination port number, respectively (Step S35). The received query is transmitted (transferred) to the other node 1 (step S36), and the process is terminated.

  On the other hand, if the node 1 is the root node 1b in step S31 (step S31: Y), the control unit 11 acquires the location information of the content data requested by the query from the storage unit 12 (step S31). S38).

  Next, the control unit 11 extracts the IP address of the user node 1a from the query (step S39), hashes the IP address with the hash function for the port number, and the lower 16 bits (hexadecimal number) of the hash value obtained thereby. 4 digits) is extracted as a port number (step S40).

  Next, the control unit 11 determines whether or not the value extracted as the port number is less than “400h” (step S41). If it is not less than “400h” (step S41: N), the control unit 11 takes out the above-mentioned value. Establishing a connection with the user node 1a using the IP address and the port number as the destination IP address and the destination port number, respectively (step S42), and the location information of the content data acquired in step S38 is used as the user node 1a (step S43), and the process ends.

  On the other hand, if the value extracted as the port number is less than “400h” (step S41: Y), “4E20h” (hexadecimal: 20000 in decimal) is added to the value extracted as the port number. (Step S44), using this as the port number, establishing the connection with the user node 1a using the extracted IP address and the port number as the destination IP address and the destination port number, respectively (Step S42). The location information of the content data acquired in step S38 is transmitted to the user node 1a (step S43), and the process ends.

  Next, the processing of FIG. 7 is started when, for example, location information of content data transmitted from the root node 1c is received. First, the control unit 11 determines the IP of the content holder 1c from the location information. An address is acquired (step S51). When the location information includes IP addresses of a plurality of content holders, one IP address randomly selected from the IP addresses selected from the IP addresses selected by the user or one IP selected by the user via the input unit 21 is used. An address will be obtained.

  Next, the control unit 11 hashes the acquired IP address with the port number hash function, and extracts the lower 16 bits (4 digits in hexadecimal) of the hash value obtained thereby as a port number (step S52).

  Next, the control unit 11 determines whether or not the value extracted as the port number is less than “400h” (step S53). When the value is not less than “400h” (step S53: N), the acquired value is obtained. Establishing a connection with the content holder 1c using the IP address and the port number as the destination IP address and the destination port number, respectively (step S54), and transmitting the request information of the content data to the content holder 1c ( In step S55, the content data transmitted by the content holder 1c in response to this is received (step S56), and the process is terminated.

  On the other hand, if the value extracted as the port number is less than “400h” (step S53: Y), “4E20h” (hexadecimal: 20000 in decimal) is added to the value extracted as the port number. (Step S57), using this as the port number and establishing the connection with the content holder 1c using the acquired IP address and the port number as the destination IP address and the destination port number, respectively (Step S54). The content data request information is transmitted to the content holder 1c (step S55), and the content data transmitted from the content holder 1c is received accordingly (step S56), and the process ends.

(Embodiment 2)
Next, the operation of the content distribution system S according to the second embodiment will be described with reference to FIGS. In the second embodiment, the node ID is an object to be applied to the port number hash function.

  FIG. 8 is a flowchart showing a standby port number setting process in the node control unit 11, FIG. 9 is a flowchart showing a content data search process in the user node control unit 11, and FIG. FIG. 11 is a flowchart illustrating content data search processing in the node control unit 11. FIG. 11 is a flowchart illustrating content data acquisition processing in the user node control unit 11.

  The process of FIG. 8 is started when, for example, the user operates the input unit 21 and inputs a request for participation in the overlay network 9, and the control unit 11 is uniquely assigned to its own node 1, for example. The production number is hashed with a node ID hash function to obtain a node ID (for example, 1CF2 A0B6 F32B 4581h (hexadecimal number)) (step S101).

  Next, the control unit 11 hashes the node ID with the port number hash function, and obtains the lower 16 bits (4 digits in hexadecimal) of the hash value (for example, B356 8976h (hexadecimal)) obtained thereby. (For example, 8976h) is extracted (step S102).

  Next, the control unit 11 determines whether or not the value extracted as the port number is less than “400h” (hexadecimal number) (step S103). If not less than “400h” (step S103: N) The process proceeds to step S105, and if it is less than “400h” (step S103: Y), “4E20h” (hexadecimal number) is added to the value extracted as the port number (step S104), and step S105. Migrate to

  In step S105, the control unit 11 determines whether or not its own node 1 exists inside the NAT function-equipped router. If the self does not exist inside the NAT function-equipped router (step S105: N), the process proceeds to step S106. If the self exists within the NAT function-equipped router (step S105: Y), the process proceeds to step S107. To do.

  In step S106, the control unit 11 sets (releases) the value obtained as the port number in step S102 or step S104 as the standby port number (step S106), and proceeds to step S110.

  On the other hand, in step S107, the control unit 11 determines whether or not the value obtained as the port number in step S102 or step S104 is already in use as the standby port number of another node 1 to the NAT function-equipped router. Determine by making an inquiry. That is, there are a plurality of nodes 1 inside the NAT function-equipped router, and the value obtained as the port number in step S102 or step S104 has already been obtained by another node 1 existing inside the same NAT function-equipped router. It is determined whether the value is the same (by the port number hash function). This is because the node IDs of the plurality of nodes 1 existing inside the router equipped with the NAT function are different from each other, but the lower 16 bits (4 digits in hexadecimal) of these hash values (or “4E20h” (hexadecimal) This is because the value obtained by adding () may match. However, since there is a sufficient possibility that they do not match, rather than obtaining the port number by hashing the IP address with the port number hash function as in the first embodiment, the node ID is hashed with the port number hash function to obtain the port number. Obtaining a number has the advantage that the setting range of the standby port number is widened.

  If the port number obtained in step S102 or step S104 is not in use by another node 1 (step S107: N), the control unit 11 sets (releases) the port number as a standby port number. (Step S108), the process proceeds to Step S110. In this setting, a command for setting the port number of the node 1 as a standby port number is issued to the NAT function-equipped router (port forwarding setting), whereby the standby port number of the node 1 is set in the NAT function-equipped router. Is set.

  On the other hand, when the port number obtained in step S102 or step S104 is being used by another node 1 (step S107: Y), the control unit 11 displays another node on the display screen of the display unit 16, for example. 1 displays a message indicating that the port number is in use (for example, “the port number is being used by another node”) (step S109), and the process is terminated.

  In step S110, the control unit 11 acquires the IP address and node ID of any node 1 that has already joined the overlay network 9.

  Next, the control unit 11 hashes the acquired node ID with the port number hash function, and extracts the lower 16 bits (4 digits in hexadecimal) of the hash value obtained thereby as a port number (step S111). .

  Next, the control unit 11 determines whether or not the value extracted as the port number is less than “400h” (step S112). If the value is not less than “400h” (step S112: N), the above-described extraction is performed. Establishing a connection with the arbitrary node 1 using the IP address and the port number as the destination IP address and the destination port number, respectively (step S113), and connecting the arbitrary node 1 to the overlay network 9 Participation request information indicating a participation request (IP address of own node 1 (a private IP address in the case of the node 1 inside the NAT function-equipped router) and a node ID is included in the payload) is transmitted as a transmission source address ( Step S114), the process ends.

  On the other hand, if the value extracted as the port number is less than “400h” (step S112: Y), “4E20h” (hexadecimal: 20000 in decimal) is added to the value extracted as the port number. (Step S115), this is used as a port number, and the connection with the arbitrary node 1 is established using the extracted IP address and the port number as the destination IP address and the destination port number, respectively (Step S113). ), The participation request information is transmitted to the arbitrary node 1 (step S114), and the process ends.

  As a result, the own node 1 participates in the overlay network 9 and acquires the DHT, and the IP address and node ID of the node 1 are in any one or more other nodes 1. It will be registered in DHT. As described above, all the nodes 1 participating in the overlay network 9 release the value generated by the port number hash function and the node ID as the standby port number.

  Next, the process of FIG. 9 is started when the user in the user node 1a operates the input unit 21 to input a content data search instruction. In addition, since the process from step S121 to S123 is the same as the process from step S21 to S23 shown in FIG. 5, the overlapping description is abbreviate | omitted.

  Next, the control unit 11 refers to the DHT and extracts, for example, a node ID having the same most significant digit of the content ID and an IP address of another node 1 corresponding to the node ID (step S124).

  Next, the control unit 11 hashes the extracted node ID with the port number hash function, and extracts the lower 16 bits (4 digits in hexadecimal) of the hash value obtained thereby as a port number (step S125).

  Note that the processing from step S126 to S129 is the same as the processing from step S26 to S29 shown in FIG.

  Next, the processing of FIG. 10 is started when a query (including the IP address and node ID of the user node 1a) transmitted from the user node 1a is received. 1 is the root node 1b of the content data corresponding to the content ID added to the received query. For example, the node ID of its own node 1 is closest to the content ID (for example, the upper digit) Is determined according to whether or not more match (step S131).

  When the own node 1 is not the root node 1b (step S131: N), the control unit 11 refers to the DHT, for example, a node in which the upper few digits (for example, the upper second digit) of the content ID match. The ID and the corresponding IP address are extracted (step S132).

  Next, the control unit 11 hashes the extracted node ID with the port number hash function, and extracts the lower 16 bits (4 digits in hexadecimal) of the hash value obtained thereby as a port number (step S133).

  Note that the processing from step S134 to S137 is the same as the processing from step S34 to S37 shown in FIG.

  On the other hand, when the node 1 is the root node 1b in step S131 (step S131: Y), the control unit 11 acquires the location information of the content data requested by the query from the storage unit 12 (step S131). S138).

  Next, the control unit 11 extracts the node ID and IP address of the user node 1a from the query (step S139), hashes the node ID with the port number hash function, and the lower 16 bits of the hash value obtained thereby. (4 digits in hexadecimal) is extracted as a port number (step S140).

  Note that the processing from step S141 to S144 is the same as the processing from step S41 to S44 shown in FIG. The root node 1c transmits the node ID together with the location information of the content data to the user node 1a.

  Next, the process of FIG. 11 is started when, for example, the location information and node ID of the content data transmitted from the root node 1c are received. First, the control unit 11 selects the content holder from the location information. The IP address 1c is acquired (step S151).

  Next, the control unit 11 hashes the received node ID with the port number hash function, and extracts the lower 16 bits (4 digits in hexadecimal) of the hash value obtained thereby as a port number (step S152).

  Note that the processing from step S153 to S157 is the same as the processing from step S53 to S57 shown in FIG.

  As described above, according to the above-described embodiment, the standby port number of each node 1 is hashed by the common port number hash function using the IP address or node ID uniquely assigned to each node 1. Therefore, each node 1 makes an inquiry to the port number introduction (inquiry) server while improving the security. Without using the common port number hash function (that is, the same port number hash function as that of the node 1 for setting the standby port number, and the same calculation) ) Can be acquired efficiently. This can also reduce the cost of providing a port number introduction (inquiry) server.

  In the above-described embodiment, the port number hash function shared by the nodes 1 is updated (changed) periodically (for example, at the DHT update timing), and the updated port number hash function is updated. A port number may be generated on the basis of this, and the standby port number may be periodically changed (reset). With this configuration, it is possible to further improve security.

  For example, a plurality (different types, for example, 12 types) of port number hash functions (for example, port number hash functions 1 to 12) are stored in advance in the storage unit 12 of each node 1. The control unit 11 in each node 1 acquires one port number hash function from a plurality of port number hash functions stored in the storage unit 12 at regular intervals (for example, at 0:00 on the first day of every month, A hash function for a port number having a number corresponding to the month is acquired), and a first port number is generated using this function, and the generated first port number is reset as a standby port number. The control unit 11 in each node device changes the port number hash function to be used in synchronization with the resetting of the standby port number, that is, the port number used when connecting to another node 1. A hash function is appropriately acquired from the storage unit 12 (for example, a port number hash function having a number corresponding to the month is acquired), and a standby port number as a destination is generated using the hash function.

  Further, the port number hash function is distributed (distributed) from a predetermined node or server connected to the network 3 to each node 1 via the network 3 periodically (for example, monthly). And stored in the storage unit 12 (for example, the old hash function for the old port number has been distributed and updated with the new hash function for the port number), and the control unit 11 in each node 1 is distributed. Obtain a port number hash function (for example, information indicating the update date and time is also added to the hash function) (for example, when the update date and time is reached), and use this to generate the first port number Then, the generated first port number is reset as a standby port number. The control unit 11 in each node device changes the port number hash function to be used in synchronization with the resetting of the standby port number, that is, the port number used when connecting to another node 1. A hash function is acquired from the storage unit 12, and a standby port number as a destination is generated using the hash function.

  It should be noted that such periodic update (change) of the port number hash function needs to be performed synchronously (at the same timing) in all the nodes 1 participating in the overlay network 9. Since the node 1 needs to accurately recognize the date and time, the node 1 is configured to acquire an accurate date using, for example, NTP (Network Time Protocol). As a result, the update timing of the port number hash function can be made accurate.

  In the above embodiment, the IP address or the like is applied to the port number hash function, the last 4 digits are extracted in hexadecimal of the obtained value, and the standby port number is set based on this, but it is limited to this. For example, the IP address or the like is applied to the port number hash function, the last 4 digits of the decimal number is extracted with the decimal value of the obtained value, and 10000 to 60000 is added to the extracted value, for example, and the standby port It is good also as a number (however, when it becomes 1023 or less or 65536 or more, it adjusts so that it may become 1024 or more and 65535 or less).

  Further, in all the steps S9, S18, S29, S37, S44, S57, S104, S115, S129, S137, S144, and S157, the constant value “4E20h” was added. As long as they are common values, other values may be used, or they may not be added.

  For example, when the value obtained from the port number hash function is less than 1024 (decimal number), it can also be obtained by the following calculation.

(1) Subtract the calculated value (value less than 1024) from 65535. (2) Exclusive in bit units between the value greater than 1024 (common value) and the calculated value (value less than 1024) OR (3) Complement of obtained value (value less than 1024) (inverted value of all bits)
In the above embodiment, the description has been made on the assumption that the overlay network 9 is constructed by an algorithm using DHT. However, the present invention is not limited to this and can be applied to other computer network systems. It is.

It is a figure which shows an example of the connection aspect of each node apparatus in the content delivery system which concerns on this embodiment. It is a figure which shows an example of DHT routing in case a user node acquires location information in the node ID space of DHT. FIG. 3 is a diagram illustrating a schematic configuration example of a node 1. 5 is a flowchart illustrating a standby port number setting process in a node control unit 11 according to the first exemplary embodiment. 5 is a flowchart illustrating content data search processing in a control unit 11 of a user node in the first embodiment. 5 is a flowchart illustrating content data search processing in a control unit 11 of a relay node or a root node in the first embodiment. 5 is a flowchart illustrating content data acquisition processing in a control unit 11 of a user node in the first embodiment. 9 is a flowchart illustrating a standby port number setting process in a control unit 11 of a node in the second embodiment. 9 is a flowchart illustrating content data search processing in a control unit 11 of a user node in the second embodiment. 9 is a flowchart illustrating content data search processing in a control unit 11 of a relay node or a root node in the second embodiment. 9 is a flowchart illustrating content data acquisition processing in a control unit 11 of a user node in the second embodiment.

Explanation of symbols

1 node 8 network 9 overlay network 11 control unit 12 storage unit 13 buffer memory 14 decoder unit 15 video processing unit 16 display unit 17 audio processing unit 18 speaker 20 communication unit 21 input unit 22 bus

Claims (10)

In a network system including a plurality of node devices that can be connected to each other via a network,
Each of the node devices is
Storage means for storing identification information uniquely assigned to the relay device necessary for connecting itself or the network to the network, and a common function in the network system;
First port number generation means for generating a first port number using the common function and the identification information assigned to itself or the relay device;
Standby port setting means for setting the generated first port number as a standby port number;
Identification information acquisition means for acquiring identification information uniquely assigned to another node device or a relay device necessary for the other node device to connect to the network when connected to the other node device; ,
Second port number generation means for generating a second port number using the common function and the acquired identification information;
Connection establishment means for establishing a connection with the other node device based on the generated second port number;
A network system comprising: The network system according to claim 1,
The first port number generation unit and the second port number generation unit may prevent the well-known port number from overlapping when the port number generated using the common function overlaps with a well-known port number. In addition, the network system is characterized in that the port number is a number obtained by performing a predetermined operation on the generated port number. The network system according to claim 1,
A network system, wherein a common function in each of the node devices is periodically updated, and a standby port number in each of the node devices is periodically reset. The network system according to claim 1,
The storage means of each of the node devices stores a plurality of the common functions in advance,
The first port number generation means in each of the node devices acquires one common function from a plurality of common functions stored in the storage means at regular time intervals, and uses this to use the first port function. A port number is generated, and the standby port setting means resets the generated first port number as the standby port number,
The second port number generation means in each of the node devices changes the common function to be used in synchronization with the resetting of the standby port number by the standby port setting means. . The network system according to claim 1,
The common function is periodically distributed to the respective node devices via the network and stored in the storage means.
The first port number generation means in each of the node devices generates the first port number using the distributed common function, and the standby port setting means uses the generated first port number. Re-set as the standby port number,
The second port number generation means in each of the node devices changes the common function to be used in synchronization with the resetting of the standby port number by the standby port setting means. . In the network system according to any one of claims 1 to 5,
The network system, wherein the common function is a hash function. The network system according to any one of claims 1 to 6,
The network system, wherein the identification information is an IP address or a node ID. A node device in a network system including a plurality of node devices that can be connected to each other via a network,
Storage means for storing identification information uniquely assigned to the relay device necessary for connecting itself or the network to the network, and a common function in the network system;
First port number generation means for generating a first port number using the common function and the identification information assigned to itself or the relay device;
Standby port setting means for setting the generated first port number as a standby port number;
Identification information acquisition means for acquiring identification information uniquely assigned to another node device or a relay device necessary for the other node device to connect to the network when connected to the other node device; ,
Second port number generation means for generating a second port number using the common function and the acquired identification information;
Connection establishment means for establishing a connection with the other node device based on the generated second port number;
A node device comprising: A program for causing a computer to function as the node device according to claim 8 . A connection establishment method in a network system including a plurality of node devices that can be connected to each other via a network,
Each of the node devices stores identification information uniquely assigned to itself or a relay device necessary for itself to connect to the network, and a function common to the network system;
Each of the node devices generates a first port number using the common function and the identification information assigned to itself or the relay device;
Each of the node devices sets the generated first port number as a standby port number;
Obtaining the identification information uniquely assigned to the other node device or the relay device necessary for the other node device to connect to the network when connected to the other node device;
The first node device generates a second port number using the common function and the acquired identification information;
The one node device establishing a connection with the other node device based on the generated second port number;
A connection establishment method comprising:

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