WO2009154249A1

WO2009154249A1 - Remote access system, device, method and program

Info

Publication number: WO2009154249A1
Application number: PCT/JP2009/061092
Authority: WO
Inventors: 邦宏石黒
Original assignee: 株式会社Access
Priority date: 2008-06-20
Filing date: 2009-06-18
Publication date: 2009-12-23
Also published as: JP2010004344A

Abstract

Provided are a terminal device and a remote access system to a home network having a home gateway. The terminal device is provided with a first Universal Plug and Play (UPnP) unit for communicating based on the UPnP protocol, and a first message conversion unit for converting a UPnP discovery message to unicast. The gateway is comprised of a second UPnP unit for communicating based on the UPnP protocol; a network address translator (NAT) unit which translates between the private address assigned to a device and a global address; a second message conversion unit which converts a unicast discovery message received from the terminal device to a multicast discovery message, and transmits the message to a private network; and a third message conversion unit which rewrites the private address of the device included in the reply message received from the device to the global address corresponding to the private address.

Description

Remote access system, apparatus, method and program

The present invention relates to a communication system for remotely accessing a private network such as a home network via the Internet, and an apparatus, method, and program used in the system.

In recent years, DLNA (Digital Living Network Alliance), a standardization organization for home networks, connects digital home appliances such as digital AV devices in the home, personal computers (PCs), and other digital contents such as videos and music. Guidelines have been formulated for mutual use. In the following description, the guidelines established by DLNA are referred to as “DLNA”. In DLNA, a server that provides content is defined as DMS (Digital Media Server), a playback client is defined as DMP (Digital Media Player), and a controller that controls DMS or DMP is defined as DMC (Digital Media Controller). Exchanged data formats, communication procedures, etc. are defined. By configuring a home network using a DLNA-compliant device, for example, it is possible to display content stored on a PC (DMS) on a television (DMP) using a cellular phone terminal (DMC). It has become.

In DLNA, UPnP (Universal Plug and Play) is adopted as a technical specification for automatically recognizing a device in a home network and sharing content included in the device. UPnP is a specification for detecting and connecting to devices connected to a local network such as a home network. For this reason, UPnP does not assume that a device located outside the local network accesses a device in the home network via the Internet, and has a mechanism that enables such remote access. Absent. By the way, in recent years, mobile terminals such as mobile phones capable of high-speed access to the Internet, large-capacity data communication, and browsing of moving image content have become widespread. As a result, the user can use not only from home but also from home, for example, to view content stored on a device at home using a mobile terminal. There is a demand for remote access to devices in the network.

In response to such demands, UPnP remote access technology has been developed in recent years. Patent Document 1 describes an example of a UPnP remote access system. In the UPnP remote access system in Patent Document 1, in order to establish secure communication between a remote device (mobile phone) in an external network and a device in the home network, the remote device and the home gateway in the home network are used. A tunnel based on IPSec (IP Security) is established. Furthermore, many functions are provided in the home gateway in order to provide various services owned by devices in the home network to the remote devices. Examples of functions given to the home gateway include a maintenance function that maintains a list of information on each device in the home network and information on services owned by each device and updates the information as needed, search from a remote device, There are a function of transferring a notification message to a device in a home network, a function of filtering a multicast address of a message transmitted from a remote device, and the like.

International Publication No. WO2007 / 110,754

Here, in order to employ the UPnP remote access described in Patent Document 1 in the DLNA home network, a tunnel by IPSec is constructed between the remote device and the home gateway as described above, and the above-mentioned home gateway is further configured as described above. Need to add many features like

However, in order to connect a remote device and a home network with an IPSec tunnel, the remote device must be an apparatus conforming to IPSec, and for this purpose, it is necessary to install IPSec client software in the remote device in advance. There is. Also, before constructing the tunnel, it is necessary to perform authentication, exchange of encryption keys, etc. between the remote device and the home gateway, and the processing becomes complicated. Furthermore, when it is desired to simultaneously connect to a home network from a plurality of remote devices, it is necessary to construct a tunnel for each remote device, which increases processing at the home gateway.

Further, as described above, in the remote access system of Patent Document 1, only the remote device and the home gateway are connected by the tunnel. For this reason, it is not possible to directly access a device in the home network from a remote device, and it is necessary to collect and hold information on services provided by the device in the network at the home gateway. In addition, every time the information of each device in the home network is updated, the information held by the home gateway must be updated. For this reason, the processing that must be performed in the home gateway increases, and the load on the home gateway increases. Particularly in a home network to which a large number of devices are connected, there is a problem that not only the processing amount of the home gateway increases, but also the necessary storage capacity increases.

The present invention has been made in view of the above circumstances, and provides a remote access system that enables remote access to a home network from a remote location by a simple communication method without imposing a heavy load on the home gateway, and the remote access. It is an object to provide an apparatus, a method, and a program for realizing the above.

In order to solve the above-described problems, the present invention provides a remote access system for accessing a private network having a gateway and at least one device from the terminal device via the Internet. The terminal device in the remote access system of the present invention includes a first network interface unit for connecting to a private network via the Internet, a first UPnP unit for performing communication based on the UPnP standard, and a UPnP discovery message as a destination for a gateway. And a first message conversion unit for converting into a unicast discovery message. The gateway in the remote access system of the present invention includes a second network interface unit for connecting to the Internet, a third network interface unit for connecting to a private network, and a second UPnP unit for performing communication based on the UPnP standard. A NAT unit that mutually converts a private address assigned to the device and a global address for Internet connection based on an address conversion table, and a unicast discovery message received from a terminal device is converted into a multicast discovery message. And a response message to the discovery message from the device via the second message conversion unit for transferring to the private network and the third network interface unit. Receive, the private address of the device included in the response message based on the address conversion table included in the NAT section, and a third message conversion unit for rewriting the global address corresponding to the private address. The terminal device according to the present invention is characterized in that communication is performed with a device that is a transmission source of a response message based on a global address included in the response message.

According to the remote access system configured as described above, the device address managed as a private address in the private network is converted into a global address based on the NAT address conversion table and transmitted to the terminal device. As a result, communication from a terminal device managed by a global address to a device in the private network becomes possible. In addition, since the response message is rewritten by using the information of the address conversion table in the NAT function installed in a general gateway, it is slightly less than the standard UPnP function unit installed in the terminal device and the gateway. The communication between the terminal device and the device is possible only by performing expansion. Further, the remote access system of the present invention does not require complicated communication procedures such as tunneling in the terminal device or gateway, and only relatively light processing such as unicast / multicast change and address rewriting using NAT. Is done. Therefore, a system can be constructed using a terminal device having a relatively low processing capability such as a mobile phone. In addition, since the terminal device can communicate directly with the device as described above, the processing load of the gateway is relatively light, and even when remote access is simultaneously received from several terminal devices, the processing capacity of the gateway There is no shortage.

In the remote access system configured as described above, the third message conversion unit may be configured to rewrite a URL indicating the location of the UPnP description of the device included in the response message to a global address.

With this configuration, in the gateway, the description URL described in the private address included in the UPnP discovery response message or the like is converted into a global address and then transferred to the terminal device. Therefore, the terminal device using the global address is used. Thus, description information held by a device in a private network such as a home network can be acquired.

Also, the private network may be a network constructed according to the DLNA guidelines.

Also, according to the present invention, a gateway for connecting a terminal device on the Internet and a private network is provided. The gateway of the present invention includes a first network interface unit for connecting to the Internet, a third network interface unit for connecting to the private network, a private address assigned to the device, and a global address for connecting to the Internet. A NAT unit for mutual conversion based on the address conversion table, a second message conversion unit for converting a unicast discovery message received from the terminal device into a multicast discovery message and transferring it to the private network, and a device to the discovery message When the response message is received, the private address of the device included in the response message is set based on the address conversion table used in NAT. And a third message conversion unit for rewriting the global address corresponding to the over preparative address.

Also, according to the present invention, a terminal device that accesses a private network having a gateway and at least one device via the Internet is provided. A terminal device according to the present invention includes a network interface unit for connecting to a private network via the Internet, a first UPnP unit that performs communication based on the UPnP standard, and a unicast discovery message whose destination is a UPnP discovery message. A first message conversion unit for converting to a first message conversion unit. Further, the terminal device is characterized in that it communicates with the device that is the transmission source of the response message by using the global address included in the response message from the device.

Further, according to the present invention, there is provided a method for performing remote access from a terminal device to a private network having a gateway and at least one device via the Internet. The remote access method of the present invention includes a step of generating a UPnP discovery message executed in a terminal device, and a first message for converting the UPnP discovery message into a unicast discovery message destined for the gateway and transferring it to the gateway. A conversion step, a second message conversion step executed in the gateway, converting a unicast discovery message received from the terminal device into a multicast discovery message and transferring it to the private network, and receiving a response message to the discovery message from the device Then, the private address of the device included in the response message is converted into the private address based on the address conversion table used in NAT. Made from the corresponding third message conversion step of rewriting the global address, the NAT conversion step of converting the private address and a global address assigned to the device to each other based on the address conversion table. The present invention also provides a program for causing a computer to execute each step of the above method.

Therefore, according to the present invention, it is possible to provide a remote access system that enables access to a home network from a remote location by a simple communication method without imposing a heavy load on the gateway.

1 is a diagram showing a schematic configuration of a remote access system according to the present invention. It is a block diagram which shows schematic structure of a home gateway. It is a functional block diagram which shows the main functions regarding the remote access system of this invention implement | achieved in a home gateway. It is a figure which shows the protocol stack of DLNA. It is a figure for demonstrating the flow of the UPnP process in a home network. It is a block diagram which shows schematic structure of a terminal device. It is a functional block diagram which shows the main functions regarding the remote access system of this invention implement | achieved in a terminal device. It is a figure for demonstrating the flow of the remote access process of this invention.

First, terms used in the description of embodiments of the present invention will be described below.
DHCP (Dynamic Host Configuration Protocol): A protocol that dynamically assigns IP addresses.
DDNS (Dynamic Domain Name System): A system that associates dynamically assigned IP addresses with domain names.
GENA (General Event Notification Architecture): A protocol used for UPnP event notification.
HTTP (Hyper Text Transfer Protocol): A communication protocol used for data transfer between a Web browser and a Web server.
-HTTPPU (HTTP over UDP): A variant of HTTP that transfers data over UDP.
-HTTPMU (HTTP Multicast over UDP): A variant of HTTP that performs multicast data transfer over UDP.
NAT (Network Address Translation): IP address translation technology that translates global addresses and local addresses.
RPC (Remote Procedure Call): Technology that entrusts execution of a part of a process to another device connected via a network.
SOAP (Simple Object Access Protocol): A protocol for executing RPC using HTTP and XML. Used for UPnP control.
SSDP (Simple Service Discovery Protocol): A protocol for discovering network services. Used for UPnP discovery.
TCP (Transmission Control Protocol): One of the Internet standard protocols. In the transport layer of the OSI reference model, it realizes connection-type reliable communication over IP.
UDP (User Datagram Protocol): One of the Internet standard protocols. In connection with the transport layer of the OSI reference model, connectionless communication such as multicast is realized over IP.
URL (Uniform Resource Locator): A description method that indicates the location of information existing on the Internet.
XML (Extensible Markup Language): One of markup languages. Extensibility that allows users to define their own tags.

Hereinafter, a remote access system 1 according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a remote access system 1 according to an embodiment of the present invention. The remote access system 1 according to the present embodiment includes a home network 100, the Internet 200, and a terminal device 300. The home network 100 is connected to the Internet 200 via a home gateway 10 described later. In the present embodiment, the terminal device 300 is a mobile phone terminal, and is connected to the Internet 200 via a mobile phone network (not shown).

The home network 100 is a local (private) network constructed in the home, and is configured by the home gateway 10 and

devices

21, 22 and 23 installed in the home. The

devices

21, 22, and 23 are home electronic devices such as a PC, a digital camera, an HDD recorder, or a home game machine. The home gateway 10 and the

devices

21, 22, and 23 are all products compliant with the DLNA guidelines, and constitute a home network 100 by being connected to each other by wire or wirelessly as will be described later.

FIG. 2 is a block diagram showing a schematic configuration of the home gateway 10. As shown in FIG. 2, the home gateway 10 includes a CPU 11, a memory 12, a local network interface unit 14, and a global network interface unit 15. These components are connected to each other via a bus 20 and are controlled by the CPU 11.

The memory 12 stores various data such as an address conversion table used in the NAT unit 160 described later, programs, and the like. The program stored in the memory 12 includes a control program for realizing the functional blocks shown in FIG. The CPU 11 implements each function shown in FIG. 3 by executing a program stored in the memory 12. The local network interface unit 14 is a network interface that connects the home gateway 10 to the home network 100. The global network interface unit 15 is a network interface that connects the home gateway 10 to the Internet 200.

FIG. 3 is a functional block diagram showing main functional blocks related to the remote access of the present invention realized in the home gateway 10. The DLNA unit 130 is a functional block for realizing various functions defined by the DLNA guidelines, and performs various processes using the UPnP unit 131. The UPnP unit 131 is a functional block for performing processing based on the UPnP standard. The UPnP unit 131 includes a remote access processing unit 140 (hereinafter referred to as “RA processing unit 140”) as a function expansion unit for realizing remote access of the present invention. Further, the UPnP unit 131 performs various processes using the DHCP server unit 132 and the Web server unit 134. In the present embodiment, FIG. 3 shows only the UPnP unit 131 as a functional block used by the DLNA unit 130. However, the DLNA unit 130 performs various processes using many other functional blocks for realizing functions necessary for DLNA (not shown). Other functions include, for example, an RTP (Real-time Transport Protocol) function that is a transmission protocol for streaming reproduction of audio data and video data in each device. In the present embodiment, the description will be focused on the processing related to UPnP used by DLNA, and thus description of other functions will be omitted.

The UPnP unit 131 performs processing such as addressing, discovery, description, control, eventing, and presentation, which will be described later, to automatically recognize a device in the home network 100 and establish mutual communication for sharing the content of the device. I do.

The DHCP server unit 132 is a functional block used for UPnP addressing, and has a function of automatically assigning a local address to a device connected to the home network 100. The DHCP server unit 132 is set with a range of local addresses that can be assigned to each device, and provides the information to devices connected to the home network 100. Then, when the device finishes communication, the address is automatically collected and assigned to another device. The Web server unit 134 has a function of performing communication with the outside using a protocol such as HTTP.

The NAT unit 160 has a function of mutually converting a local address assigned to each

device

21, 22, and 23 in the home network 100 and a global address used for communication with a device on the Internet 200. It is a conversion unit. Specifically, for example, when the device 23 accesses the Internet 200, the local IP address assigned to the device 23 by the NAT unit 160 and the TCP / UDP port number for the local network are the global IP address and the Internet. Is converted to a TCP / UDP port number. Contents to be converted by the NAT unit 160 (that is, combinations of IP addresses and TCP / UDP port numbers used in the home network 100 and the Internet 200) are registered in the address conversion table and stored in the memory 12. . Then, the NAT unit 160 refers to the address conversion table and converts the local address used in the home network 100 and the converted global address to each other. As a result, a device identified by a local address in the home network 100 is identified by a global address on the Internet 200.

Next, the UPnP function used for detecting devices in the home network 100 and exchanging contents will be described with reference to FIG. 4 and FIG. FIG. 4 shows a DLNA protocol stack. As shown in FIG. 4, the highest layer in the DLNA protocol stack is a DLNA layer that provides services in accordance with DLNA guidelines to various applications. The DLNA layer includes various interfaces such as GUI (Graphical User Interface) and API (Application Programming Interface). Below the DLNA layer, there is a UPnP layer that provides a service according to the UPnP standard to the DLNA layer. The UPnP layer uses various protocols such as SSDP, SOAP, and GENA. This protocol is used when performing discovery, control, and eventing processes in SSDP, SOAP, GENA, and UPnP. The SSDP used for discovery transmits and receives messages using HTTPMU and HTTPPU operating on UDP / IP. Control and eventing executed using SOAP and GENA are performed by connection-type communication on TCP / IP. The actual processing of UPnP composed of such a protocol stack will be described with reference to FIG.

FIG. 5 is a diagram for explaining the flow of UPnP processing in the home network 100. In FIG. 5, the flow of processing of automatic recognition and content sharing of devices and contents in the home network 100 by UPnP will be described by taking as an example a case where a device 23 is newly connected to the home network 100. This UPnP processing is realized by executing a UPnP function by a CPU (not shown) provided in the

devices

21, 22, and 23 that comply with the DLNA guidelines. Automatic recognition and content sharing by UPnP is realized by a six-stage process of addressing, discovery, description, control, eventing, and presentation.

First, when the device 23 is connected to the home network 100 by wireless or wired LAN (S1), a local IP address in the home network 100 is automatically assigned to the device 23 by the DHCP server unit 132 of the home gateway 10. (S2). This process is called addressing. When the DHCP server unit 132 does not exist in the home network 100, the device 23 uses an Auto IP function provided in the own device, and uses an arbitrary IP that does not overlap with other devices from a reserved address. It is also possible to select an address and automatically set its own IP address.

When an IP address is set in the device 23, discovery is performed next. In discovery, in order to detect servers and other devices connected to the home network 100, a discovery message is transmitted from the device 23 to each device in the home network 100 by multicast (S3). This discovery message includes information about the device 23 such as a device type, a query for making an inquiry to devices existing on the home network 100, and the like.

The discovery message multicast-transmitted in the process of S3 is received by the home gateway 10 and the

devices

21 and 22. In the following description, communication performed between the device 23 and the device 21 will be described as an example. The device 21 that has received the discovery message transmits a response message notifying that the device is connected to the network to the device 23 (S4). The response message includes basic information such as the device type and service type of the device 21 and the local IP address of the device 21 as well as a URL for referring to a description to be described later.

In addition, in the discovery of UPnP, SSDP is used for transmitting a discovery message and a response message. SSDP defines a method for detecting a device in a network and a method for notifying availability of a device. Further, in the discovery, only devices having a specific function among devices connected in the home network 100 can be detected. In this case, a discovery message including a query for only a device having a specific function is transmitted from the device 23 by multicast. Each device that has received the discovery message transmits a response message only when the device itself has the function.

Subsequently, the device 23 that has received the response message from the device 21 acquires a description from the device 21 in order to acquire more detailed information of the device 21. The description is a document described in XML, and includes a device description in which a device type name and a list of services to be provided are described, and information on each service provided by the device (a list of commands, actions, parameters of each action, etc.) There are two types of service descriptions in which are described). The device 23 transmits a description request to the device 21 based on the description URL included in the response message from the device 21 (S5). Then, in response to the description request, the device 21 transmits the description to the device 23 (S6). Transmission and reception of these descriptions is performed by HTTP communication. In order to simplify the description, in FIG. 5 and the description of the specification, the acquisition of the device description and the service description is described as one process, but in detail, the request and response for each description. Are performed in order. Specifically, the device 23 first acquires the device description of the device 21. Then, from the contents of the acquired device description, the type of service provided by the device 21 and the URL of the service description in which detailed information about each service is described are known. If the device 21 provides a necessary service to the device 23, the device 23 then requests the device 21 for a service description regarding the service. Then, a service description is acquired from the device 21.

In addition, when the device 23 uses the service provided by the device 21, processing for controlling the device 21 is performed. This process is called control. Specifically, first, a control message including an action request regarding a service provided by the device 21 is transmitted from the device 23 to the device 21 (S7). Then, a result or error for the control message is returned from the device 21 to the device 23 (S8). This control is performed using SOAP. In this way, the service provided by the device 21 can be used by the device 23 by communicating the control message and the result / error.

Further, when a change occurs in the service provided by the device 21, eventing is performed to notify the device 23 of this change (S9). For example, eventing is performed when a service item provided by the device 21 is added or deleted. Eventing is a process of notifying the device 23 that the service provided by the device 21 has been changed using GENA. In GENA, when the state of the device changes (an event occurs), notification of the event can be transmitted to a device in the network using HTTP.

If the device 21 has a presentation page, that is, if the URL of the presentation page is included in the device description transmitted from the device 21, the device 23 acquires this page and reads it into the browser. Then, the page is displayed on a display screen (not shown) provided in the device 23. Depending on the function of the page, information on the state of the device 21 can be acquired from the device 21 and displayed on the device 23. Such processing is called presentation (S10).

By each UPnP process as described above, a peer-to-peer interconnection between the device 23 newly added to the home network 100 and the device 21 becomes possible. Similarly to the device 21, the device 22 and the home gateway 10 that have received the discovery message multicast-transmitted from the device 23 also perform processing such as description, control, eventing, and presentation, as in the case of the device 21. Done. As a result, the device 23 and each device in the home network 100 can communicate with each other, and control between devices and content sharing can be performed.

When automatic device recognition using UPnP is performed as described above, in accordance with DLNA guidelines, for example, the device 21 is a DMS holding content such as a digital camera, the device 22 is a DMP having a content playback function such as a television, and the device 23 is defined as a DMC having a control function such as a PC. Then, content reproduction processing and the like are performed by the cooperation operation of each device based on the procedure stipulated in the DLNA guidelines. Specifically, by controlling the DMS (device 21) and the DMP (device 22) by the DMC (device 23), the image owned by the DMS (device 21) is transferred to the DMP (device 22), and the DMP It can be displayed on the screen.

Next, remote access from the terminal device 300 to the home network 100 in the remote access system 1 which is a feature of the present invention will be described in detail. This remote access is used, for example, when the content stored in the device 21 of the home network 100 is downloaded to the terminal device 300 held on the go and played. FIG. 6 is a block diagram illustrating a schematic configuration of the terminal device 300. In the present embodiment, the terminal device 300 is a mobile phone terminal. However, in another embodiment, for example, a mobile terminal such as a PHS (Personal Handy Phone system), a PDA (Personal Digital Assistants), or a mobile game machine may be used. A terminal that can be connected to the home gateway 10 via the Internet 200 such as an installed PC may be used.

The terminal device 300 includes a CPU 310 that performs overall control of the entire device, a memory 320 that stores programs such as various data and applications, an input unit 330 including numeric keys and direction keys for receiving user input, a liquid crystal display, an organic EL display, and the like And a network interface unit 350 for accessing the Internet 200 via a mobile phone network. These components are interconnected with other components via a bus 390.

FIG. 7 is a functional block diagram showing main functional blocks related to the remote access of the present invention realized by the CPU 310. The memory 320 stores a control program for the CPU 310 to realize each functional block shown in FIG. 7, and the CPU 310 reads out and executes each program from the memory 320, thereby causing each of the functional blocks shown in FIG. 7 to be executed. Function is realized.

The DLNA unit 360 in FIG. 7 is a functional block that performs communication based on DLNA guidelines. The DLNA unit 360 executes various processes using the UPnP unit 362. The UPnP unit 362 is a functional block that performs communication processing based on the UPnP standard, and includes discovery, description, control, eventing, and presentation processes. The UPnP unit 362 includes a remote access processing unit 366 (hereinafter referred to as “RA processing unit 366”) as a function expansion unit for realizing remote access of the present invention. Similarly to the DLNA unit 130 of the home gateway 10, the DLNA unit 360 performs processing using many functional blocks (not shown) used in the DLNA system such as the RTP function in addition to the UPnP unit 362. It has become.

FIG. 8 is a diagram for explaining remote access processing for performing remote access from the terminal device 300 to the home network 100 in the remote access system 1 of the present embodiment. First, the user of the terminal device 300 operates the input unit 330 to start an application (for example, an HDD recorder remote playback application) based on DLNA installed in the memory 320 in advance. When the application is activated, the terminal device 300 establishes a connection with the Internet 200 via the mobile phone network (S101).

Incidentally, as described above, the local IP addresses of the

devices

21, 22 and 23 in the home network 100 are assigned by the DHCP server unit 132 provided in the home gateway 10 at the time of addressing in the UPnP process. When the DHCP server does not exist in the network, the local IP address is set by the Auto IP function provided in the device. However, the terminal device 300 of this embodiment is connected to the Internet 200 instead of the home network 100 as described above. Therefore, it is not possible to perform addressing of the local IP address that is performed in a normal UPnP device such as the

devices

21, 22, and 23. Further, the terminal device 300 does not normally have an Auto IP function. Therefore, the addressing of the terminal device 300 is performed by assigning a global address from a DHCP server provided in an access point on a mobile phone network (not shown) when establishing a connection with the Internet 200. In the subsequent processing, this global address is used for identification and management of the terminal device 300.

When the connection to the Internet 200 is completed and a global address is assigned to the terminal device 300, next, the home network 100 that is the connection destination is designated (S102). The home network 100 is specified by the user of the terminal device 300 using the input unit 330 to input the domain name of the home network 100 or the like. Here, in the home network 100 of this embodiment, the home gateway 10 is published on the Internet 200 as a public server of the home network 100. At this time, services called DNS and DNS are used. Specifically, first, a global address used on the Internet 200 is assigned to the home gateway 10. This assignment is performed by a network provider that provides an Internet connection service to the home network 100. The assigned global address is associated with the domain name indicating the home network 100 and registered in a DNS server owned by the Internet service provider. In this case, the domain name can be arbitrarily set. At this time, if DDNS is used, the contents registered in the DNS server can be updated as the global address assigned to the home gateway 10 changes. As a result, a unique domain name is always assigned to the home gateway 10 even when a new global address is given each time the home gateway 10 connects to the Internet 200.

Therefore, the terminal device 300 can be connected to the home network 100 by inputting or specifying the domain name of the home network 100. When the connection to the home network 100 is established, discovery by the UPnP unit 362 of the terminal device 300 is executed. The UPnP unit 362 creates a discovery message using SSDP (S103). At this time, the discovery message created by the UPnP unit 362 conforms to the UPnP standard, and designates a multicast address by UDP as a destination. Subsequently, the RA processing unit 366 rewrites the discovery message created by the UPnP unit 362 into a message in a format suitable for remote access (hereinafter referred to as “RA message”) (S104). Specifically, the destination address of the discovery message in which the multicast address is specified as the destination is converted into a unicast message that uses the global address of the home gateway 10.

The RA message rewritten by the RA processing unit 366 is unicast transmitted from the network interface unit 350 to the home gateway 10 via the mobile phone network and the Internet 200 (S105).

The RA message unicast transmitted from the terminal device 300 is received by the global network interface unit 15 of the home gateway 10. The CPU 11 recognizes that the message is an RA message from the header information of the RA message received by the global network interface unit 15 from the terminal device 300, and executes the RA processing unit 140.

When the RA processing unit 140 reads the received RA message and recognizes that it is a discovery message transmitted from the terminal device 300, the RA processing unit 140 converts it into a multicast discovery message with the destination address as the network address of the home network 100 (S106). ). That is, this discovery message is generated so as to be transmitted by multicast using the global address of the terminal device 300 as a source address and the home network 100 as a destination address. Next, the discovery message converted by the RA processing unit 140 is multicast from the local network interface unit 14 into the home network 100 (S107).

The discovery message transmitted from the home gateway 10 by multicast is received by each of the

devices

21, 22 and 23. The subsequent processing will be described taking communication between the device 23 and the home gateway 10 as an example. When the device 23 that has received the discovery message from the home gateway 10 confirms that it is the target of the discovery message, the device 23 generates a response message notifying that the own device is connected to the network. This response message includes basic information such as the device type and service type of the device 23 and the local address of the device 23, as well as a URL for referring to a description to be described later. The destination of the response message is the global address of the terminal device 300 described in the discovery message. Then, the response message generated by the device 23 is transmitted to the home gateway 10 (S108). The home gateway 10 that has received the response message from the device 23 next rewrites the received response message (S109).

In S109, specifically, the following processing is performed. First, when the local network interface unit 14 receives a response message from the device 23, the CPU 11 executes RA processing. First, the RA processing unit 140 refers to the address conversion table used in the NAT unit 160 and extracts the global address of the device 23 corresponding to the local address of the device 23 included in the response message. If the local address of the device 23 is not registered in the address conversion table, a new global address is assigned to the device 23, and the assigned global address and the corresponding local address are registered in the address conversion table. After that, the assigned global address is extracted.

Next, the RA processing unit 140 rewrites the IP address part indicating the transmission source device included in the response message from the device 23 to the global address extracted from the local address of the device 23. Here, in the UPnP process in the home network 100 shown in FIG. 5, the detected devices are identified and managed by the local addresses assigned to them. However, in the case of remote access, since the address space to be used differs between the terminal device 300 that uses the global address and the home network 100 that uses the local address, the terminal device 300 and each device in the home network 100 remain as they are. Cannot communicate directly. Therefore, by rewriting the local address of the device 23 included in the response message in the home gateway 10 to a global address stored in the address translation table (or newly registered in the address translation table by the NAT unit 160), the terminal device 300 Can directly communicate with the device 23 in the home network 100 using the global address.

Furthermore, the response message includes a URL for referring to the description of the device 23, and the like. This URL is also a local address in the home network 100. Therefore, in the process of S109, the description URL is also rewritten to a global address based on the address conversion table of the NAT unit 160. Accordingly, the terminal device 300 can make a description request based on the global address. Then, the response message rewritten as described above is transmitted from the home gateway 10 to the terminal device 300 (S110).

The subsequent processing is the same as the UPnP processing in FIG. 5 except that the NAT unit 160 of the home gateway 10 performs address conversion. Specifically, the terminal device 300 transmits a request message for requesting the description of the device 23 based on the URL (global address) included in the response message of the device 23 transmitted from the home gateway 10 (S111). . The request message transmitted from the terminal device 300 is first received by the home gateway 10. Next, the home gateway 10 converts the destination address of the received request message from the global address to the local address in the NAT unit 160 and transfers it to the device 23. Then, in response to the description request from the terminal device 300, the device 23 returns a description (S112).

Subsequently, as in the description process, control message transmission (S113), result / error reception (S114), event notification by GENA (S115), and presentation (S116) are performed. Also in these processes, the home gateway 10 converts the destination address of the received message from the global address to the local address or from the local address to the global address in the NAT unit 160, and transmits it to the device 23 or the terminal device 300, respectively. To do. When these processes are completed, the terminal device 300 and the device 23 can directly communicate with each other. The UPnP process between the terminal device 300 and the

other devices

21 and 22 is performed in the same manner as described above. As a result, the terminal device 300 and the

devices

21, 22 and 23 in the home network 100 can communicate with each other, and the communication terminal 300 can share services and contents provided by the

devices

21, 22 and 23. It becomes possible.

Thereafter, the DLNA unit 360 of the terminal device 300 defines, for example, that the device 21 is a DMS that owns content such as a digital camera, and the terminal device 300 is a DMP that has a content playback function. Then, content such as an image can be downloaded from the device 21 (DMS) by the terminal device 300 (DMP) and displayed on the display unit 340. Thereby, for example, the content stored in the device in the home network 100 can be shared by the terminal device 300 even when away from home. In the above embodiment, the DLNA and remote access processing are executed by the CPU (11, 310) by calling a program stored in the memory (12, 320) of the terminal device 300 and the home gateway 10. However, all or a part of each functional unit may be mounted as ASIC (Application Specific Specific Integrated Circuit) on each device, and the hardware may be realized by the ASIC.

As described above, in the terminal device 300 in the remote access system 1 of the present embodiment, processing is executed according to normal UPnP except that the RA processing unit 366 transmits a discovery message to the home gateway 10 by unicast. Therefore, it is not necessary to provide an additional application in the terminal device 300. Further, the address conversion of the terminal device 300 having a different address space to be used and the

devices

21, 22 and 23 in the home network 100 is performed by using address conversion of the NAT function provided in a general gateway. Thus, the interconnection can be realized by the Internet access normally used. Therefore, it is not necessary to provide a tunnel between the home network 100 and the terminal device 300.

Furthermore, in the remote access system 1 according to the present embodiment, the terminal device 300 can know the address (global address) of the device in the home network 100 by rewriting the response message in the home gateway 10. As a result, the terminal device 300 and each device in the home network 100 can directly communicate with each other, so that the home gateway 10 lists information on each device in the network and information on services owned by each device. There is no need to perform maintenance. Therefore, in the remote access system 1 of the present embodiment, it is possible to access the home network 100 from a remote location by a simple communication method without imposing a heavy load on the home gateway 10.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments and can be modified in various ranges. For example, this embodiment relates to remote access to a home network compliant with DLNA, but is not limited to this, and can be applied to a home network compliant with other standards using UPnP.

10 Home gateway 11 CPU
12 Memory 14 Local network interface unit 15 Global

network interface unit

21, 22, 23 Device 130 DLNA unit 131 UPnP unit 132 DHCP server unit 134 Web server unit 140 RA processing unit 160 NAT unit 100 Home network 200 Internet 300 Terminal device 310 CPU
320 Memory 330 Input unit 340 Display unit 350 Network interface unit 360 DLNA unit 362 UPnP unit 366 RA processing unit

Claims

A remote access system for accessing a private network having a gateway and at least one device from a terminal device via the Internet,
The terminal device
A first network interface unit for connecting to the private network via the Internet;
A first UPnP unit that performs communication based on the UPnP standard; and a first message conversion unit that converts a UPnP discovery message into a unicast discovery message destined for the gateway.
A second network interface unit for connecting to the Internet;
A third network interface unit for connecting to the private network;
A second UPnP unit that performs communication based on the UPnP standard;
A NAT unit that mutually translates a private address assigned to the device and a global address for connecting to the Internet based on an address translation table;
A second message conversion unit that converts a unicast discovery message received from the terminal device into a multicast discovery message and forwards the message to the private network;
A response message to the discovery message is received from the device via the third network interface unit, and the private address of the device included in the response message is determined based on the address conversion table of the NAT unit. And a third message conversion unit that rewrites the global address corresponding to
The terminal apparatus performs communication with the device that is a transmission source of the response message based on a global address included in the response message rewritten by the third message conversion unit.
The remote access system according to claim 1, wherein the third message conversion unit further rewrites a URL indicating the location of the UPnP description of the device included in the response message to a corresponding global address.
The remote access system according to claim 1 or 2, wherein the private network is a network constructed in accordance with DLNA guidelines.
A gateway that connects a private network having at least one device and a terminal device on the Internet,
A second network interface unit for connecting to the Internet;
A third network interface unit for connecting to the private network;
A second UPnP unit that performs communication based on the UPnP standard;
A NAT unit for mutually converting a private address assigned to the device and a global address for Internet connection based on an address conversion table;
A second message conversion unit that converts a unicast UPnP discovery message received from the terminal device into a multicast discovery message and transfers the message to the private network;
A response message to the discovery message is received from the device via the third network interface unit, and the private address of the device included in the response message is determined based on the address conversion table of the NAT unit. A third message conversion unit for rewriting the global address corresponding to the address;
A gateway comprising:
A terminal device for accessing a private network having a gateway and at least one device via the Internet,
A first network interface unit for connecting to the private network via the Internet;
A first UPnP unit that performs communication based on the UPnP standard;
A first message conversion unit that converts a UPnP discovery message into a unicast discovery message destined for the gateway;
The terminal apparatus performs communication with the device that is a transmission source of the response message based on a global address included in the response message from the device.
A method for accessing a private network having a gateway and at least one device from a terminal device via the Internet,
Executed in the terminal device;
Generating a UPnP discovery message;
A first message conversion step of converting the UPnP discovery message into a unicast discovery message destined for the gateway and transferring it to the gateway;
Executed in the gateway,
A second message conversion step of converting a unicast discovery message received from the terminal device into a multicast discovery message and transferring it to the private network;
A third message for receiving a response message to the discovery message from the device and rewriting the private address of the device included in the response message to a global address corresponding to the private address based on an address translation table used in NAT; A conversion step;
A NAT translation step for translating the private address assigned to the device and the global address to each other based on the address translation table;
A remote access method comprising:
A method for accessing a private network having a gateway and at least one device from a terminal device via the Internet,
Executed in the terminal device;
Generating a UPnP discovery message;
A remote access method comprising: a first message conversion step of converting the UPnP discovery message into a unicast discovery message destined for the gateway and transferring it to the gateway.
A method for accessing a private network having a gateway and at least one device from a terminal device via the Internet,
Executed in the gateway,
A second message conversion step of converting a unicast discovery message received from the terminal device into a multicast discovery message and transferring it to the private network;
When receiving a response message for the discovery message from the device, a third message for rewriting the private address of the device included in the response message to a global address corresponding to the private address based on an address translation table used in NAT A conversion step;
NAT conversion step of converting the private address assigned to the device and the global address to each other based on the address conversion table;
A remote access method comprising:
A program for causing a computer to execute the remote access method according to any one of claims 6 to 8.