JP2022097129A - Device, program and method for communication control - Google Patents

Abstract

To obtain a communication control device which eliminates the necessity of a setting change having been conventionally required depending on whether or not a client terminal is subordinate to a router.SOLUTION: In the communication control device, a communication control unit performs the processing of: receiving from a home client terminal an access request related to a specific domain name to designate a home server; requesting the domain name server to perform the name resolution of the specific domain name; and performing local address acquisition processing which causes the home client terminal to acquire, using a specific subdomain name, a specific internal IP address, which is a private network address of a home server linked to the specific subdomain name, according to an external IP address, which is indicated by a first response related to the specific domain name replied from the domain name server, coincident with an IP address allocated to a WAN port.SELECTED DRAWING: Figure 6

Description

The present invention relates to a communication control device, a communication control program, and a communication control method, and more particularly to a communication control device, a communication control program, and a communication control method in which a server accessible from a client terminal is arranged under the control.

A router is widely used as a communication control device for establishing communication between different networks. In such communication via a router, a terminal in a network beyond the router is accessed by communication beyond the router. In such a case, it is necessary to perform domain name resolution, and the technique related to this domain name resolution is disclosed in Patent Document 1.

In Patent Document 1, the terminal solves the domain name of the target server, and when the search result cannot be obtained, solves the domain name of the gateway relayed to the target server. At this time, the DSN server manages the domain name of the server with a dedicated TLD (Top Level Domain) added to the end of the domain name in association with the gateway address. In order to perform domain name resolution of the gateway, the terminal adds a dedicated TLD to the end of the domain name of the target server to perform domain name resolution. The DSN server returns the address of the gateway corresponding to the domain name to which the TLD is added as a response. When the terminal acquires the gateway address, it connects to the gateway in the procedure for connecting to the gateway, and requests the gateway to connect to the target server.

Japanese Unexamined Patent Publication No. 2010-13604

However, in the technique described in Patent Document 1, it is necessary to use the address of the private server on the local network (for example, the local IP address) when the home client terminal in the private network accesses the private server. That is, the setting must be changed depending on whether or not the client terminal is on the private network, which causes a problem that the setting becomes complicated.

One aspect of the communication control device according to the embodiment is a WAN port connected to a public network in which a domain name server is arranged, and a LAN connected to a private network in which access to a home client terminal and a home server is arranged. The communication control unit includes a port, a storage unit that stores a specific subdomain name that designates the home server, and a communication control unit that controls communication between the LAN port and the WAN port. A first regarding the specific domain name that receives an access request for a specific domain name that specifies a home server from the home client terminal, requests the domain name server to resolve the name of the specific domain name, and is returned from the domain name server. According to the fact that the external IP address indicated by the response of 1 matches the IP address assigned to the WAN port, the specific subdomain name is used and the home client terminal is associated with the specific subdomain name. A local address acquisition process for acquiring a specific internal IP address, which is the address of the private network of the home server, is performed.

One aspect of the communication control program according to the embodiment controls communication between a WAN port to which a public network is connected and a plurality of LAN ports to which a private network is connected, and between the plurality of LAN ports. A communication control program executed by an arithmetic unit in a communication control device that receives an access request for a specific domain name that specifies a home server located in the private network from a home client terminal located in the private network. Then, the domain name server located in the public network is requested to resolve the name of the specific domain name, and the external IP address indicated by the first response regarding the specific domain name returned from the domain name server is the WAN. The specific subdomain is used for the home client terminal by using the specific subdomain name that specifies the home server stored in the storage unit used by the calculation unit according to the match with the IP address assigned to the port. A local address acquisition process for acquiring a specific internal IP address, which is the address of the private network of the home server associated with the name, is performed.

One aspect of the communication control method according to the embodiment controls communication between a WAN port to which a public network is connected and a plurality of LAN ports to which a private network is connected, and between the plurality of LAN ports. This is a communication control method executed by the arithmetic unit in the communication control device, and receives an access request for a specific domain name that specifies a home server located in the private network from a home client terminal located in the private network. , Requests name resolution of the specific domain name from the domain name server located in the public network, and the external IP address indicated by the first response regarding the specific domain name returned from the domain name server is the WAN port. By using the specific subdomain name that specifies the home server stored in the storage unit used by the calculation unit according to the match with the IP address assigned to the home client terminal, the specific subdomain name is given to the home client terminal. Performs a local address acquisition process for acquiring a specific internal IP address which is an address of the private network of the home server associated with.

According to the communication control device, the communication control program, and the communication control method according to the embodiment, the client terminal can access the home server regardless of the location of the client terminal without making complicated settings on the client terminal. Can be made.

It is the schematic of the communication system which concerns on Embodiment 1. FIG. It is a sequence diagram explaining the operation when the private server is accessed from the client terminal which is not under the router in the communication system which concerns on Embodiment 1. FIG. It is a sequence diagram explaining the problem which occurs when the private server is accessed from the client terminal under the router when the router which concerns on Embodiment 1 is not used. It is a block diagram of the router which concerns on Embodiment 1. FIG. It is a figure explaining the program structure which operates on the router which concerns on Embodiment 1. FIG. It is a flowchart explaining the operation of the communication system which concerns on Embodiment 1. FIG. It is a sequence diagram explaining the operation when the private server is accessed from the client terminal under the router in the communication system which concerns on Embodiment 1. FIG. It is a flowchart explaining the operation of the communication system which concerns on Embodiment 2. It is a sequence diagram explaining the operation when the private server is accessed from the client terminal under the router in the communication system which concerns on Embodiment 2. FIG.

In order to clarify the explanation, the following description and drawings are omitted or simplified as appropriate. In addition, each element described in the drawing as a functional block that performs various processing can be configured by a CPU (Central Processing Unit), a memory, and other circuits in terms of hardware, and in terms of software, memory. It is realized by the program loaded in. Therefore, it is understood by those skilled in the art that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof, and the present invention is not limited to any of them. In each drawing, the same elements are designated by the same reference numerals, and duplicate explanations are omitted as necessary.

Also, the programs described above can be stored and supplied to a computer using various types of non-temporary computer-readable media. Non-temporary computer-readable media include various types of tangible recording media. Examples of non-temporary computer-readable media include magnetic recording media (eg, flexible disks, magnetic tapes, hard disk drives), optomagnetic recording media (eg, optomagnetic disks), CD-ROMs (Read Only Memory), CD-Rs. Includes CD-R / W, semiconductor memory (eg, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (Random Access Memory)). The program may also be supplied to the computer by various types of temporary computer-readable media. Examples of temporary computer readable media include electrical, optical, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

Embodiment 1
First, the communication control device according to the first embodiment is a product called a router. Therefore, in the following, the communication control device will be referred to as a router. FIG. 1 shows a block diagram of the communication system 1 according to the first embodiment. As shown in FIG. 1, in the communication system 1 according to the first embodiment, the router 10 controls the communication between the private area and the public area.

In the private area, terminals and servers capable of communicating are arranged on a private network constructed by the LAN (Local Area Network) function of the router. In the example shown in FIG. 1, an example in which a home server (for example, a private server 11) and a home client terminal (for example, a client terminal 21) are arranged on a private network is shown. In a private network, devices on the network communicate with each other by an internal IP address managed by the router 10. There may be a plurality of servers and client terminals arranged on the private network.

In the public area, there is a public network provided by a communication carrier or the like via a WAN (Wide Area Network) port of a router, and a communication network for communicating with a client terminal or a server via the public network is constructed. FIG. 1 shows an example in which a public network 12 is connected to a router 10 and a domain name server (hereinafter referred to as a DSN server 13) and an out-of-home client terminal (for example, a client terminal 22) are arranged in the public network 12. rice field. In a public network, devices on the network communicate with each other by an external IP address issued by a predetermined institution. It should be noted that many servers and client terminals arranged on the public network are not shown.

Here, the IP address is defined by numbers in four fields (IPv4) or six fields (IPv6), and a combination of the numbers is used to specify a device on the network. On the other hand, in the explanation described later, a domain name is used. The domain name is a character string that identifies a certain server, and is, for example, abc. defghi. It is a character string that is easy for a person to distinguish, such as com. Then, the domain name server has an entry associated with the domain name and the external IP address, and returns the external IP address corresponding to the inquired domain name to the inquiry destination as a response.

Further, in the communication system 1 according to the first embodiment, the first entry and the second entry are registered in the DSN server 13 in accordance with the start of use of the private server 11. The first entry is an entry in which a specific domain name that specifies a private server and a specific external IP address corresponding to the specific domain name are associated with each other. The second entry is an entry that associates a specific subdomain name that specifies a private server with a specific internal IP address that is the address of the private network of the specific subdomain name and the private server. In the following description, as an example of a domain name that specifies a private server, the specific domain name is referred to as abc. defghi. Using com, as a specific subdomain name, z. abc. defghi. com is used.

The external IP address is an IP address managed by a server on the public network 12, and is sometimes called a global IP address. Further, the internal IP address is an IP address applicable only within the private network managed by the router 10, and is also called a local IP address. In the following description, in particular, the global IP address that specifies the private server 11 is referred to as a specific global IP address, and the local IP address that specifies the private server 11 is referred to as a specific local IP address.

The router 10 controls communication between communication devices arranged in the private network and between the communication device arranged in the private network and the communication device arranged on the public network 12. Further, the router 10 controls communication between communication devices according to a predetermined protocol, and in this communication control, the communication destination device is specified based on the IP address. Further, when the client terminal 21 on the private network accesses the specific domain name by designating the specific domain name, the router 10 gives the client terminal 21 the specific local IP address set in the private server 11. Performs the local address acquisition process to be acquired. Details of this local address acquisition process will be described later.

Subsequently, the operation of the communication system 1 according to the first embodiment will be described. First, in the communication system 1 according to the first embodiment, an external access operation for accessing a private server 11 on a private network managed by a router 10 from a client terminal 22 on a public network 12 will be described. In the following description, the global IP address assigned to the WAN port of the router 10 is referred to as xxx. xxx. xxx. Let it be xxx, and the local IP address assigned to the private server 11 is yyy. yyy. yyy. The explanation will be given as yyy.

Therefore, FIG. 2 shows a sequence diagram illustrating an operation when accessing a private server from a client terminal that is not under the router in the communication system according to the first embodiment. As shown in FIG. 2, when accessing the private server 11 from the client terminal 22, the DSN server 13 is first requested to resolve the specific domain name corresponding to the private server 11. Subsequently, the DSN server 13 returns the specific global IP address associated with the specific domain name to the client terminal 22 as a response. As a result, the client terminal 22 grasps the specific global IP address that specifies the private server 11. After that, the client terminal 22 accesses the router 10 using the acquired specific global IP address, and the router 10 mediates communication between the client terminal 22 and the private server 11.

In the external access operation shown in FIG. 2, the router 10 can control the communication between the client terminal 22 and the private server 11 only by performing an operation according to the protocol without performing a special operation.

Subsequently, in the communication system 1 according to the first embodiment, an internal access operation for accessing the private server 11 from a client terminal 21 in the same private network as the private network in which the private server 11 is arranged will be described. In this internal access operation, if the local address acquisition process according to the first embodiment is not performed, a problem occurs in the access to the private server 11 by the specific domain name. In order to explain the characteristics of the local address acquisition process according to the first embodiment in more detail, first, a problem that occurs when the local address acquisition process is not performed will be described.

FIG. 3 shows a sequence diagram illustrating a problem that occurs when accessing a private server from a client terminal under the router when the router according to the first embodiment is not used.

FIG. 3 is a sequence diagram illustrating an operation when the client terminal 21 under the router 10 accesses the private server 11 using a specific domain name. In this case, the client terminal 21 sends an access request specifying a specific domain name to the router 10. Then, the router 10 requests the DSN server 13 to resolve the name of the specific domain name received from the client terminal 21, and the DSN server 13 returns the specific global IP address corresponding to the specific domain name to the router 10 as a response. After that, the router 10 gives the client terminal 21 a specific global IP address corresponding to the specific domain name as a response.

However, the specific global IP address acquired by the client terminal 21 is assigned to the WAN port of the router 10, and the client terminal 21 identifies the private server 11 in the same private network with the specific global IP address. I can't. For this reason, if the local address acquisition process according to the first embodiment is not performed, a communication error occurs in which communication devices on the same private network cannot communicate with each other using only a specific domain name.

Therefore, in the communication system 1 according to the first embodiment, the first entry and the second entry are registered in advance in the DSN server 13. The first entry is an entry in which a specific domain name that specifies the private server 11 and a specific global IP address corresponding to the specific domain name are associated with each other. The second entry is an entry in which the specific subdomain name that specifies the private server 11 and the specific subdomain name are associated with the specific local IP address that is the address of the private network of the private server 11.

Then, in the communication system 1 according to the first embodiment, the router 10 is made to perform the local address acquisition process using the first entry and the second entry. As a result, the client terminal 21 can access the private server 11 from the client terminal 21 only by grasping one specific domain name. Therefore, the details of the router 10 according to the first embodiment will be described later.

FIG. 4 shows a block diagram of the router 10 according to the first embodiment. As shown in FIG. 4, the router 10 has a communication control unit 30, a storage unit 31, a wireless LAN interface 32, a wired LAN interface 33, and a WAN interface 34. The wireless LAN interface 32 and the wired LAN interface 33 are physical circuits constituting the LAN port. The router 10 treats a communication device connected to the wireless LAN interface 32 or the wired LAN interface 33 as a device on a private network. The WAN interface 34 is a physical circuit that constitutes a WAN port. A line connected to the public network 12 is connected to the WAN interface 34. Then, the router 10 controls the communication between the wireless LAN interface 32, the wired LAN interface 33, and the WAN interface 34 by using the communication control unit 30.

Further, the storage unit 31 stores information used in the communication control performed by the communication control unit 30. In the example shown in FIG. 4, the WAN side IP information, the DNS resolved IP information, the target server FQDN information, and the target server CNAME information are stored in the storage unit 31.

The WAN side IP information is the information of the global IP address set in the WAN port of the router 10. In the router 10 according to the first embodiment, xxx. xxx. xxx. xxx is described.

The DNS resolved IP information is the information of the global IP address grasped by the response (hereinafter referred to as a response) to the name resolution inquiry (hereinafter referred to as a query) of the domain name requested by the router 10 from the DNS server 13. be. In the router 10 according to the first embodiment, xxx. xxx. xxx. xxx is described.

The target server FQDN information is a specific domain name. In the router 10 according to the first embodiment, a specific domain name that specifies the private server 11 is described. In the target server CNAME information, a specific subdomain name of the private server 11 described in the CNAME field, which is a specific field of the response operated in the local address acquisition process described later, is described.

In addition to many functions as a router, the communication control unit 30 performs a characteristic operation when there is a request for access to the private server 11 by a specific domain name that specifies the private server 11. Specifically, when the communication control unit 30 receives an access request for a specific domain name designating the private server 11 from the client terminal 21, the communication control unit 30 requests the DSN server 13 to resolve the name of the specific domain name. Then, the communication control unit 30 responds that the specific global IP address indicated by the first response regarding the specific domain name returned from the DNS server 13 matches the IP address assigned to the WAN port, and the specific subdomain 30 is used. Using the name, the local address acquisition process for causing the client terminal 21 to acquire the specific local IP address associated with the specific subdomain name is performed.

In the first embodiment, in this local address acquisition process, the communication control unit 30 performs the following operations. Specifically, in the local address acquisition process according to the first embodiment, the communication control unit 30 has the specific field in the first response that is the name resolution result of the specific domain name returned from the DNS server 13 to the router 10. Generate a second response with the specific subdomain name stored in (eg, CNAME field). Then, the communication control unit 30 returns this second response to the client terminal 21.

The CNAME field, which is a specific field, is a field that specifies the transfer destination domain name of the access destination domain name. Therefore, the client terminal 21 that has received the second response is included in the third response obtained by requesting the DSN server 13 to resolve the specific subdomain name by referring to the specific field of the second response. Access the private server 11 using the specific local IP address.

The communication control unit 30 can be realized by, for example, an arithmetic unit capable of executing a program. One of the methods for realizing the communication control unit 30 is to realize the above-mentioned operation of the communication control unit 30 by executing the communication control program in the calculation unit. Therefore, a program configuration operated by the communication control unit 30 will be described. FIG. 5 shows a diagram illustrating a program configuration operating on the router according to the first embodiment.

As shown in FIG. 5, the program running on the communication control unit 30 includes a kernel process and a user process. Kernel processes are a group of programs that have a high level of safety verification and are difficult to add or modify. On the other hand, the user process is a group of programs that can be easily added or modified by the user, although the verification level for safety is low. Then, in the program running on the communication control unit 30, the socket process 45 performs a process of connecting between the kernel process and the user process. The process shown in FIG. 5 is a part of the process executed by the communication control unit 30, and actually includes many other processes.

The kernel process includes an operating system 41, a file system 42, a WLAN driver 43, and an Ethernet driver 44. The operation system 41 is basic software for operating the software. The file system 42 is software that defines the format of information handled by the communication control unit 30. The WLAN driver 43 is software for operating a wireless LAN. The Ethernet driver 44 is software for operating a wired LAN.

User processes include a DHCP server process 46, a port control process 47, a routing table management process 48, and a DNS masquerade control process 49. The DHCP server process 46 is software that provides a DHCP function that allocates a local IP address to a communication device on a private network controlled by a router 10. The port control process 47 is software that controls protocols and information passed between the WAN port and the LAN port. The routing table management process 48 is software that manages the communication path between the WAN port and the LAN port and between the LAN port and the LAN port. The DNS masquerade control process 49 is software that provides a domain name service to terminals in a private network that are not held by the DNS server 13.

The router 10 realizes the local address acquisition process by coordinating the software shown in FIG. 5 in the communication control unit 30. Specifically, the communication control unit 30 generates a second response in which the specific subdomain name is stored in the specific field in the first response returned from the DNS server 13 in response to the name resolution request of the specific domain name. Then, the second response is returned to the client terminal 21.

Subsequently, the operation when the private server 11 is accessed from the client terminal 21 under the control of the router 10 in the communication system 1 according to the first embodiment will be described. Therefore, FIG. 6 shows a flowchart illustrating the operation of the communication system 1 according to the first embodiment.

As shown in FIG. 6, in the communication system 1 according to the first embodiment, when the client terminal 21 accesses the private server 11, the client terminal 21 generates a first DNS query regarding a specific domain name and a router. Request 10 to resolve the name of the specific domain name (step S1). However, since the router 10 cannot resolve the name of the specific domain name, this first DNS query is sent to the DNS server 13 via the router 10 (step S1).

Subsequently, the DNS server 13 refers to the first entry regarding the specific domain name for the first DNS query received, extracts the specific global IP address as a result of name resolution, and includes the specific global IP address. Generate a DNS query response of 1. Then, the DSN server 13 returns the first query response to the router 10 (step S2). Then, the router 10 that has received the first DNS query response determines whether or not the global IP address indicated by the first DNS query response matches the IP address set in the WAN port of the router 10. (Step S3). In this step S3, the WAN side IP information (the IP address of the WAN port stored in the setting process of the router 10) stored in the storage unit 31 by the communication control unit 30 and the DNS resolved IP information (in the first DNS query response). Compare the indicated global IP address).

In step S3, when the IP addresses match, the router 10 generates a second DNS query response in which the specific subdomain name is recorded in the CNAME field in the first DNS query response, and generates the second DNS query response. It is transmitted to the client terminal 21 (step S4). After that, the client terminal 21 that has received the second DNS query response refers to the CNAME field, generates a second DNS query for a specific subdomain name, and sends the second DNS query to the router 10 (. Step S5). Further, the router 10 that has received the second DNS query transmits the second DNS query to the DNS server 13 (step S5).

Subsequently, the DNS server 13 that received the second DNS query extracts the specific local IP address corresponding to the specific subdomain name as a resolution result by referring to the second entry regarding the specific subdomain name, and the specific local IP. Generate a third DNS query response containing the address. Then, the DNS server 13 sends a third DNS query response to the router 10 (step S6). This third DNS query response is sent to the client terminal 21 via the router 10. Then, the client terminal 21 communicates with the private server 11 using the specific local IP address included in the third query response (step S7).

On the other hand, if the specific global IP address indicated by the first DNS query response in step S3 and the global IP address set in the WAN port of the router 10 do not match, the router 10 sends the first DNS query response. It is transmitted to the client terminal 21 (step S8). Then, the client terminal 21 accesses the private server not under the control of the router 10 by using the specific global IP address indicated by the first DNS query response (step S9).

Subsequently, among the operations described with reference to FIG. 6, the flow up to step S7 will be described using a sequence diagram. Therefore, FIG. 7 shows a sequence diagram illustrating an operation when accessing a private server from a client terminal under a router in the communication system according to the first embodiment. Note that FIG. 7 describes the operation of the communication system 1 in the flow of the domain name or the IP address.

As shown in FIG. 7, when the client terminal 21 under the router 10 starts accessing the private server 11 using the specific domain name, the client terminal 21 makes a first DNS query regarding the specific domain name to the router 10. It is transmitted to the DNS server 13 via. Subsequently, the DNS server 13 responds to the first DNS query, refers to the first entry, and returns the first DNS query response including the specific global IP address to the router 10.

Then, if the specific global IP address indicated by the first DNS query response matches the global IP address of the WAN port of the router 10, the router 10 sets the specific subdomain name in the CNAME field of the first DNS query response. A second DNS query response is generated and transmitted to the client terminal 21.

Then, the client terminal 21 refers to the CNAME field, generates a second DNS query related to the specific subdomain name, and sends the second DNS query to the DNS server 13 via the router 10. After that, the DNS server 13 refers to the second entry, generates a third DNS query response including the specific local IP address, and returns the third DNS query response to the client terminal 21 via the router 10. .. As a result, the client terminal 21 can know the local IP address of the private server 11, and can communicate with the private server 11 using this local IP address.

From the above description, in the communication system 1 according to the first embodiment, the following operations can be performed by performing the local address acquisition process in the router 10. That is, in the communication system 1, even if the client terminal 21 holds only the specific domain name associated with the global IP address of the private server 11 in the same private network as the client terminal 21, the client terminal 21 Can establish communication with the private server 11.

At this time, the operation of the router 10 is that the specific subdomain name associated with the local IP address of the private server 11 is described in the specific field (for example, the CNAME field) in the first DNS query response of the communication protocol. Different from the domain name name resolution sequence. However, this modification is extremely small, the change in the operation of the router 10 is small, and the time and effort for verifying the operation of the router 10 due to the addition of the local address acquisition process is small. In addition, since the modification is small, the risk of inducing other defects is small.

Embodiment 2
In the second embodiment, another embodiment of the operation of the router 10 will be described. In the description of the second embodiment, the same components as those of the first embodiment are designated by the same reference numerals as those of the first embodiment, and the description thereof will be omitted. Further, it should be noted that in the second embodiment, the information included in the second DNS query response is different from that of the first embodiment.

FIG. 8 shows a flowchart illustrating the operation of the communication system according to the second embodiment. As shown in FIG. 8, in the communication system according to the second embodiment, the operation after the specific global IP address shown in the first DNS query response in step S3 and the global IP address of the WAN port of the router 10 match. Is different from the first embodiment. Therefore, only different operations will be described here.

As shown in FIG. 8, in the second embodiment, when the IP addresses match in step S3, the router 10 does not send a query response to the client terminal 21, and the router 10 has a second subdomain name. Generate a DNS query and send it to the DNS server 13 (step S10). After that, the DNS server 13 refers to the second entry to extract the specific local IP address corresponding to the specific subdomain name for the second DNS query, and the second DNS query including the specific local IP address. A response is generated, and a second DNS query response is returned to the router 10 (step S11).

Then, the router 10 that has received the second DNS query response transmits the second DNS query response to the client terminal 21 as a response to the first DNS query (step S12). As a result, the client terminal 21 can know the specific local IP address corresponding to the private server 11, and thereafter, the client terminal 21 communicates with the private server 11 using the specific local IP address (step S13).

From the above description, in the local address acquisition process according to the second embodiment, it is possible to acquire a specific local IP address from a specific domain name corresponding to the specific global IP address only by the operation of the router 10 without depending on the client terminal 21. can.

The present invention is not limited to the above embodiment, and can be appropriately modified without departing from the spirit.

1 Communication system 10 Router 11 Private server 12 Public network 13 DNS server 21 Client terminal 22 Client terminal 30 Communication control unit 31 Storage unit 32 Wireless LAN interface 33 Wired LAN interface 34 WAN interface 41 Operation system 42 File system 43 WLAN driver 44 Ethernet driver 45 Socket 46 DHCP Server Process 47 Port Control Process 48 Routing Table Management Process 49 DNS Masquerade Control Process

Claims (7)

A WAN port connected to the public network where the domain name server is located,
A LAN port connected to a private network where access to home client terminals and home servers is located,
A storage unit that stores a specific subdomain name that specifies the home server,
It has a communication control unit that controls communication between the LAN port and the WAN port.
The communication control unit
Upon receiving an access request for a specific domain name that specifies the home server from the home client terminal,
Request the name resolution of the specific domain name from the domain name server,
Using the specific subdomain name, depending on whether the external IP address indicated by the first response regarding the specific domain name returned from the domain name server matches the IP address assigned to the WAN port, A communication control device that performs a local address acquisition process for causing the home client terminal to acquire a specific internal IP address associated with the specific subdomain name. The communication control unit is in the local address acquisition process.
Generate a second response that stores the specific subdomain name in the specific field in the first response.
The second response is replied to the home client terminal,
The home client terminal is
With reference to the specific field of the second response, the home using the specific internal IP address included in the third response obtained by requesting the domain name server to resolve the name of the specific subdomain name. The communication control device according to claim 1, wherein the server is accessed. The communication control device according to claim 2, wherein the specific field is a field for designating a transfer destination domain name of the access destination domain name. The communication control unit is in the local address acquisition process.
In response to receiving the first response, the domain name server is requested to resolve the name of the specific subdomain name.
The name resolution result of the specific subdomain name is received from the domain name server as a second response, and the name is received.
The communication control device according to claim 1, wherein the specific internal IP address included in the second response is given to the home client terminal as a name resolution result of the specific domain name. The domain name server includes a first entry that associates a specific domain name that specifies the home server with a specific external IP address that corresponds to the specific domain name, a specific subdomain name that specifies the home server, and the above. The communication control according to any one of claims 1 to 4, wherein a second entry relating the specific subdomain name and the specific internal IP address which is the address of the private network of the home server is registered in advance. Device. A communication control program executed by an arithmetic unit in a communication control device that controls communication between a WAN port to which a public network is connected and a LAN port to which a private network is connected, and between the LAN ports.
An access request for a specific domain name that specifies a home server located in the private network is received from a home client terminal located in the private network.
Request the name resolution of the specific domain name from the domain name server located in the public network,
Depending on whether the external IP address indicated by the first response regarding the specific domain name returned from the domain name server matches the IP address assigned to the WAN port, the storage unit used by the arithmetic unit A communication control program that performs a local address acquisition process that causes the in-home client terminal to acquire a specific internal IP address associated with the specific sub-domain name using the stored specific sub-domain name that specifies the in-home server. A communication control method executed by an arithmetic unit in a communication control device that controls communication between a WAN port to which a public network is connected and a LAN port to which a private network is connected, and between the LAN ports.
An access request for a specific domain name that specifies a home server located in the private network is received from a home client terminal located in the private network.
Request the name resolution of the specific domain name from the domain name server located in the public network,
Depending on whether the external IP address indicated by the first response regarding the specific domain name returned from the domain name server matches the IP address assigned to the WAN port, the storage unit used by the arithmetic unit A communication control method for performing a local address acquisition process for causing the in-home client terminal to acquire a specific internal IP address associated with the specific sub-domain name by using the stored specific sub-domain name for the in-home server.

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