Abstract:
To provide a VPN access control system, an operating method thereof, a non-transitory computer-readable recording medium having a program recorded thereon, a VPN router, and a server capable of reducing the effort of work of an administrator and quickly permitting remote access. A VPN access control system includes a VPN router and an image server. The VPN router executes a router authentication process based on router authentication information, and the image server executes a server authentication process based on server authentication information. The image server receives an access right granting request from a portable terminal of a registered user to which the access right has been granted and executes a first user registration process. The VPN router executes a second user registration process based on a command from the image server, and transmits an authentication information notification to a user who is an access right granting target.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2014-190322, filed on Sep. 18, 2014. The above application(s) is hereby expressly incorporated by reference, in its entirety, into the present application. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a VPN access control system, an operating method thereof, a non-transitory computer-readable recording medium having a program recorded thereon, a VPN router, and a server that controls remote access using a VPN. 
         [0004]    2. Description of the Related Art 
         [0005]    A virtual private network (VPN) is known as a communication technology for building a communication network for a high level of information security. The VPN is a technology for using a shared wide area network such as the Internet or a wide area Internet protocol (IP) network provided by a communication provider, as a shared network, and building a virtual dedicated line for a plurality of users (companies or hospitals) on this shared network. The dedicated line provides high information security due to the physical occupancy of the line, but there is a disadvantage in that costs are high. Since in the VPN, the dedicated line for a plurality of users can be virtually built on a shared backbone network, high information security can be ensured at a low cost. 
         [0006]    Since transmission control protocol/Internet protocol (TCP/IP) is used as a communication protocol in the Internet or a wide area IP network, data is transferred in the form of an Internet protocol (IP) packet. According to the VPN, a logical dedicated communication channel is established in a shared network using encapsulation technology such as “Multi Protocol Label Switching (MPLS)” for attaching an identifier called a “label” specific to the VPN for each user to the IP packet and transferring the resultant IP packet, or an encryption technology such as Internet protocol security (IPsec). Accordingly, information security is ensured. 
         [0007]    The VPN is realized using a VPN router. The VPN router has an encryption function of encrypting an IP packet, in addition to a normal routing function of selecting a communication path in the network for an IP packet to be transferred. The VPN router functions as a gateway that relays communication between an internal communication network such as a local area network (LAN) within a medical facility and an external communication network such as the Internet. 
         [0008]    Access to the internal communication network from the external communication network is generally referred to as remote access. In case where the VPN is built by the VPN router, the remote access using a VPN to the internal communication network is performed. The VPN router determines whether a remotely accessing terminal has an access right, permits access of the terminal having the access right, and prohibits access of a terminal having no access right. 
         [0009]    The access right is granted by registering a user in the VPN router and notifying the registered user of authentication information. Specifically, the VPN router issues a user ID and a password as the authentication information of the user in response to a request, and registers the issued authentication information as account information of the user. Accordingly, the user registration in the VPN router is performed. The registered user is notified of the authentication information. Accordingly, the access right is granted to the registered user. Further, software for VPN access (referred to as VPN client software or the like) is installed in the terminal of the registered user, and the authentication is performed through the VPN client software. 
         [0010]    Technology for temporarily permitting remote access of a terminal of an unregistered user (temporary operator) in an emergency in a relay system described in JP 2012-231293A is described (paragraphs 0085 to 0094). In the relay system described in JP 2012-231293A, a center terminal  5  having a router function is provided as a gateway of the internal communication network ( FIGS. 1 and 2 ). In case where an administrator (a second operator Op2; paragraph 0089) receives a request for temporary access permission for remote access, the administrator performs setup for the center terminal  5 , and notifies a remotely accessing user of authentication information such as a one-time password through a telephone or the like (paragraph 0089). Accordingly, registration of a terminal of the unregistered user is performed and the access right is granted. By performing the access through the center terminal  5 , remote access from an external communication network to the internal communication network is possible. In case where the terminal of the remotely accessing user logs out, subsequent remote access is prohibited (paragraphs 0103 to 0106). 
       SUMMARY OF THE INVENTION 
       [0011]    As described above, when the remote access using a VPN is performed, first, it is necessary to obtain authentication of the VPN router that is a gateway. However, in fact, authentication of a server that is a final access destination is often necessary, in addition to the authentication of the VPN router. For example, when the remote access using a VPN to an image server of a hospital network that is a communication network inside the hospital is performed, it is necessary to obtain authentication of the image server that is a final access destination, in addition to the authentication of the VPN router that is the gateway of the network inside the hospital. In this case, so as to provide permission of remote access to a terminal of an unregistered user, user registration in the image server is required, in addition to user registration in the VPN router. Performing registration of both of the VPN router and a server that is an access destination in this way requires effort and is time-consuming. Reduction of such effort and shortening of the time are particularly desired in fields requiring promptness, such as medical fields. 
         [0012]    In the technology described in JP 2012-231293A, the setup of the VPN router is performed by the administrator when remote access is necessary, but setup of the server is not described. Even when the administrator performs the setup of the server, the effort of work of the administrator is not reduced and performing the setup is not a solution to the above problem. Further, the administrator performs notification of the authentication information through telephone contact to a temporary operator, as described in JP 2012-231293A. Such telephone contact is effective in a sense of ensuring reliability of personal identification, but the effort of the work is required of the administrator, and the reduction of such work is also strongly desired. 
         [0013]    An object of the present invention is to provide a VPN access control system, an operating method thereof, a non-transitory computer-readable recording medium having a program recorded thereon, a VPN router, and a server capable of reducing the effort of work of an administrator and quickly permitting remote access using a VPN. 
         [0014]    A VPN access control system of the present invention is a VPN access control system including a VPN router and a server, and controlling remote access to an internal communication network to which the server is connected, from an external communication network of the VPN router, in which the server includes a request reception unit, a first user registration unit, and a command issuing unit, and the VPN router includes a second user registration unit, and an authentication information transmission unit. The VPN router has an authentication function of providing access permission based on router authentication information in case where receiving an access request from a terminal of a registered user to which an access right has been granted, and the server has an authentication function of providing access permission based on server authentication information separate from the router authentication information in case where receiving the access request from the terminal of the registered user via the VPN router. The request reception unit receives an access right granting request for granting the access right to a terminal of an unregistered user to which the access right has not been granted, the access right granting request being issued from the terminal of the registered user to which the access right has been granted. The first user registration unit executes issuing of the server authentication information and first user registration for the unregistered user based on the access right granting request. The command issuing unit issues a command including the server authentication information and instructing the VPN router to issue the router authentication information and perform second user registration. The second user registration unit issues the router authentication information based on the command and executes the second user registration. The authentication information transmission unit transmits authentication information including the router authentication information and the server authentication information to the unregistered user. 
         [0015]    It is preferable that a notification destination of the unregistered user is included in the access right granting request, and the authentication information transmission unit transmits the authentication information to the notification destination. 
         [0016]    It is preferable that the command issuing unit transmits the server authentication information and the command in a e-mail format to the VPN router. 
         [0017]    It is preferable that VPN client software for performing the remote access is installed in the terminal, and the VPN router receives the router authentication information through the VPN client software. 
         [0018]    It is preferable that the authentication information transmission unit encrypts the server authentication information and the router authentication information into information that can be decrypted by the VPN client software, and transmits the encrypted information. It is preferable that the authentication information transmission unit also encrypts an address of the server. 
         [0019]    It is preferable that the first user registration unit or the second user registration unit has a validity period setting function of setting a validity period of the router authentication information or the server authentication information. 
         [0020]    It is preferable that the validity period of the access right is capable of being designated in the access right granting request, and the first user registration unit or the second user registration unit sets the validity period of the server authentication information or the router authentication information based on the designation. 
         [0021]    It is preferable that the first user registration unit or the second user registration unit sets the validity period set in advance in case where there is no designation. 
         [0022]    It is preferable that the VPN router determines that the command is included in the IP packet when the source address is the server and the destination address is the VPN router by referring to address information of the received IP packet. 
         [0023]    It is preferable that the server is a medical information server that distributes medical information. It is preferable that the medical information server is installed in a medical facility. 
         [0024]    A method of operating a VPN access control system of the present invention is a method of operating a VPN access control system including a VPN router and a server, and controlling remote access to an internal communication network to which the server is connected, from an external communication network of the VPN router, in which the server executes a request reception step, a first user registration step, and a command issuing step, and the VPN router executes a second user registration step, and an authentication information transmission step. The request reception step includes receiving an access right granting request for granting the access right to a terminal of an unregistered user to which the access right has not been granted, the access right granting request being issued from the terminal of the registered user to which the access right has been granted. The first user registration step includes executing issuing of the server authentication information and first user registration for the unregistered user based on the access right granting request. The command issuing step includes issuing a command including the server authentication information and instructing the VPN router to issue the router authentication information and perform second user registration. The second user registration step includes issuing the router authentication information based on the command and executing the second user registration. The authentication information transmission step includes transmitting authentication information including the router authentication information and the server authentication information to the unregistered user. 
         [0025]    A program of a VPN access control system of the present invention is a program of a VPN access control system including a VPN router and a server and controlling remote access to an internal communication network to which the server is connected, from an external communication network of the VPN router, in which the server is caused to function as a request reception unit, a first user registration unit, and a command issuing unit, and the VPN router is caused to function as a second user registration unit, and an authentication information transmission unit. The request reception unit receives an access right granting request for granting the access right to a terminal of an unregistered user to which the access right has not been granted, the access right granting request being issued from a terminal of a registered user to which the access right has been granted. 
         [0026]    A VPN router of the present invention is a VPN router having an authentication function of providing access permission based on router authentication information in case where receiving an access request from a terminal of a registered user to which an access right is granted, and the VPN router cooperating with a server having an authentication function of providing access permission based on server authentication information separate from the router authentication information in case where receiving the access request from the terminal of the registered user via the VPN router, to perform VPN access control for controlling remote access to an internal communication network to which the server is connected, from an external communication network of the VPN router, in which the VPN router includes a second user registration unit, and an authentication information transmission unit. The second user registration unit issues the router authentication information based on a command including the server authentication information issued by the server after the server executes issuing of the server authentication information and first user registration for an unregistered user to which the access right has not been granted based on an access right granting request for granting the access right to a terminal of the unregistered user, the access right granting request being issued from the terminal of the registered user to which the access right has been granted, and executes second user registration. The authentication information transmission unit transmits authentication information including the router authentication information and the server authentication information to the unregistered user. 
         [0027]    A server of the present invention is a server having an authentication function of providing access permission based on server authentication information in case where receiving an access request from a terminal of a registered user to which an access right has been granted, the server cooperating with a VPN router having an authentication function of providing access permission based on router authentication information separate from the server authentication information, to perform VPN access control for controlling remote access to an internal communication network to which the server is connected, from an external communication network of the VPN router, in which the server includes a request reception unit, and a first user registration unit. 
         [0028]    According to the present invention, it is possible to provide a VPN access control system, an operating method thereof, a non-transitory computer-readable recording medium having a program recorded thereon, a VPN router, and a server capable of reducing an effort of work of an administrator and quickly permitting remote access using a VPN. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]      FIG. 1  is a block diagram of a hospital system. 
           [0030]      FIG. 2  is an illustrative diagram of an access right grant application screen. 
           [0031]      FIG. 3  is a functional block diagram of an image server and a VPN router constituting a VPN access control system. 
           [0032]      FIG. 4  is an illustrative diagram of a first user registration table. 
           [0033]      FIG. 5  is an illustrative diagram of an IP packet transmitted from a portable terminal to a server. 
           [0034]      FIG. 6  is an illustrative diagram of a command transmitted from an image server to a VPN router. 
           [0035]      FIG. 7  is an illustrative diagram of authentication information notification. 
           [0036]      FIG. 8  is a flowchart illustrating an encryption procedure of an authentication information notification unit. 
           [0037]      FIG. 9  is a flowchart illustrating an access right granting procedure. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0038]    In  FIG. 1 , a hospital system  10  that is a form of a VPN access control system of the present invention is an information system built in a hospital (medical facility)  11 , and includes a medical record server  12 , an image server  13 , a client terminal  14 , and a VPN router  16 . These are communicably connected to each other by a local area network (LAN)  17  which is a communication network provided in the hospital  11 . 
         [0039]    The medical record server  12  is a server that distributes an electronic medical record of a patient, and includes a medical record database (DB)  12 A that retrievably stores electronic medical records. The image server  13  is a server that distributes an inspection image of a patient, and includes an image DB  13 A that retrievably stores inspection images. 
         [0040]    The client terminal  14  is a terminal installed in a medical department, such as surgical department or an internal department, and has a function of viewing the electronic medical records or the images. The right to access the medical record server  12  or the image server  13  has been granted to the client terminal  14 . The medical record server  12  or the image server  13  has an authentication function of granting access permission to the client terminal  14 . When the medical record server  12  or the image server  13  receives an access request, such as a viewing or updating request from the client terminal  14 , the medical record server  12  or the image server  13  performs authentication of the access right based on the server authentication information issued to the pre-registered user. When the access of the client terminal  14  of which the access right has been authenticated is permitted, distribution of the electronic medical record or the inspection image or updating of the electronic medical record is performed based on the content of the access request. 
         [0041]    In the hospital system  10 , a VPN is built using the VPN router  16  as a countermeasure to prevent leakage of information from the inside of the hospital  11  to an external communication network, such as the Internet  18  outside the hospital  11 , or illegal intrusion from the external communication network to the LAN  17 , which is an internal communication network, or the hospital system  10 . In the LAN  17  or the Internet  18 , data is transferred in the form of an IP packet defined in TCP/IP. The VPN router  16  has an encryption function, in addition to a normal router function of performing selection of a communication path (routing) based on an IP address included in the IP packet transferred over the network for the IP packet. 
         [0042]    The VPN router  16  functions as a gateway that connects the internal communication network with respect to the VPN router  16 , such as the LAN  17  in the hospital, to the external communication network with respect to the VPN router  16 , such as the Internet  18 . Connections from the external communication network to the internal communications network are all performed via the VPN router  16 . The external communication network includes a public switched telephone network (PTSN) or a wide area network (WAN) such as a wide area IP network, as well as the Internet  18 . 
         [0043]    As described above, the VPN is a technology for converting an IP packet into a form that can be decrypted by only a specific partner, using an encryption technology such as IPsec and transferring the resultant IP packet. Using encryption of the IP packet, a logical dedicated communication channel is established in a shared network such as the Internet  18 . 
         [0044]    The VPN router  16  has an authentication function of granting access permission based on the router authentication information when the VPN router  16  receives an access request from the terminal of the registered user. The router authentication information is issued to the registered user, similar to the server authentication information of the image server  13 . The VPN router  16  performs an authentication process based on the router authentication information to determine whether or not there is an access right. Also, only access from a terminal to which the access right has been granted is permitted, and access from a terminal having no access right is prohibited. 
         [0045]    For example, a doctor D 1  that is a staff member of the hospital  11  (hospital A) may access the hospital system  10  in which the VPN has been built, using a portable terminal  21  of the doctor D 1  from a destination. In this case, remote access to the internal communication network such as the LAN  17  using the VPN is performed from the external communication network such as the Internet  18 . Since the doctor D 1  is a staff member of the hospital  11 , information on the doctor D 1  is registered in the VPN router  16 , and the access right is granted to the doctor D 1 . VPN client software  22  for remote access to the VPN router  16  via the external network is installed in the portable terminal  21  of the doctor D 1 . 
         [0046]    The portable terminal  21  is, for example, a portable terminal having a wireless communication function, such as a smart phone, a tablet device, or a note-type terminal. In this example, while the portable terminal has been described as an example of a remotely accessing terminal, a stationary terminal may be used. 
         [0047]    The VPN client software  22  is application software for performing encryption or decoding of the IP packet so as to communicate with the VPN router  16 . The VPN router  16  communicates with only the terminal in which VPN client software  22  has been installed, as the remotely accessing terminal. That is, the VPN client software  22  is necessary in order to access the hospital system  10  via the VPN router  16 . 
         [0048]    The VPN client software  22  has been installed in the portable terminal  21  in advance. However, for example, the VPN client software  22  can also be downloaded from a world wide web (WEB) server  23  connected to the Internet  18  and installed. The WEB server  23  is a server that includes an application DB  23 A that stores application software, such as the VPN client software  22 , and distributes the application software in response to a distribution request from the terminal. 
         [0049]    In case where the doctor D 1  remotely accesses the hospital system  10 , for example, the doctor D 1  starts up the VPN client software  22  in the portable terminal  21  and designates a uniform resource locator (URL) address of the image server  13  in the hospital system  10  to transmit an access request via the Internet  18 . The router authentication information and the server authentication information are included in the access request transmitted by the portable terminal  21  of the registered user. The access request from the portable terminal  21  is received by the VPN router  16  that is a gateway of the hospital system  10 . In case where the VPN router  16  receives an access request, the VPN router  16  performs authentication of the access right based on the router authentication information to permit the access. The access request authenticated by the VPN router  16  is transmitted to the image server  13  via the LAN  17 . In the image server  13 , authentication of the access right is performed based on the server authentication information, and access to the image server  13  is permitted. 
         [0050]    Since the VPN is built in the hospital system  10  in this way, the registered user having the access right, such as the doctor D 1 , can perform remote access. On the other hand, since an unregistered user, such as an outsider other than a staff member of the hospital  11  (hospital A), has no access right, the unregistered user cannot perform the remote access in principle. However, for example, the doctor D 1  of hospital A may request an external doctor such as a doctor D 2  of hospital B to interpret an inspection image of a patient of hospital A. The hospital system  10  has a function of temporarily granting a right to access the hospital system  10  to the doctor D 2  in such a case. 
         [0051]    Thus, the VPN router  16  and the image server  13  having the respective authentication functions function as a VPN access control system that controls remote access using a VPN from the external communication network such as the Internet  18  to the LAN  17  that is an internal communication network to which the image server  13  is connected. 
         [0052]    The hospital system  10  receives an access right granting request to grant temporary access right to the doctor D 2  having no access right from the portable terminal  21  of the doctor D 1  having right to access the hospital system  10  via the VPN router  16 . In case where the hospital system  10  receives the access right granting request, the hospital system  10  issues the authentication information and notifies the portable terminal  24  of the doctor D 2  of the authentication information. The doctor D 2  can download the VPN client software  22  from the WEB server  23  to the portable terminal  24 , and can access the hospital system  10  using the VPN client software  22  and the authentication information. 
         [0053]    As illustrated in  FIG. 2 , the issuance of the access right granting request from the portable terminal  21  of the doctor D 1  is performed through an access right grant application screen  27 . The access right grant application screen  27  is downloaded from a server that is an access target, such as the image server  13  in response to a request from the portable terminal  21 . Also, the access right grant application screen  27  is displayed on a display of the portable terminal  21 . 
         [0054]    An input field  27 A for inputting an e-mail address of a target who applies granting of the access right, an input field  27 B for inputting a validity period of the access right, an OK button  27 C, and a cancel button  27 D are provided in the access right grant application screen  27 . Further, in the access right grant application screen  27 , a guidance message for requesting to input the e-mail address of the target who applies granting of the access right and the validity period of the access right to the input field  27 A and the input field  27 B is displayed. 
         [0055]    In case where the access right is requested to be granted to the doctor D 2  of hospital B, an e-mail address of the doctor D 2  of hospital B is input to the input field  27 A. The validity period is designated by inputting beginning and end of a period, such as Jun. 6, 2014 to Jun. 13, 2014. The validity period may be designated by inputting the period, such as three days, one week, or one month. In case where the OK button  27 C is pressed, the access right granting request including the input e-mail address or the input validity period is issued and transmitted to the image server  13 . The cancel button  27 D is an operation button for canceling input content. 
         [0056]    A configuration for realizing a VPN access control function will be described using an example of a combination of the image server  13  and the VPN router  16  with reference to  FIG. 3 . The image server  13  has a configuration that is based on a computer such as a personal computer or a workstation and in which a control program such as an operating system or the server program  36  for causing the computer to function as the image server  13  is installed. Also, although not illustrated, the image server  13  includes a display and an input device (a keyboard or a mouse). 
         [0057]    The image server  13  includes a central processing unit (CPU)  31 , a memory  32 , a storage device  33 , and a communication Interface (I/F)  34 , which are connected via a data bus (not illustrated). 
         [0058]    The storage device  33  is a device that stores various data and includes, for example, a hard disk drive. In the storage device  33 , a control program or a server program  36  is stored. Further, a first user registration table  37  in which information on the registered user who can access the image server  13  has been recorded is stored in the storage device  33 . 
         [0059]    The memory  32  is a work memory used for the CPU  31  to execute the process, and includes, for example, a random access memory (RAM). The CPU  31  loads a control program stored in the storage device  33  into the memory  32 , and executes a process according to the program to overall control respective units of the computer. The communication I/F  34  performs transfer control for connection to the LAN  17 . The image server  13  communicates with the client terminal  14  connected to the LAN  17  via the communication I/F  34 , and communicates with the external portable terminal  21  via the communication I/F  34  and the VPN router  16 . 
         [0060]    A program for realizing a server authentication function serving as a part of the VPN access control function, in addition to the image server function, is included in the server program  36 . When the server program  36  starts up, the CPU  31  of the image server  13  is in cooperation with the memory  32  to function as a server authentication unit  31 A, a request reception unit  31 B, a first user registration unit  31 C, and a command issuing unit  31 D. 
         [0061]    The server authentication unit  31 A performs an authentication process to determine whether to permit access to the image server  13  based on the server authentication information provided to the registered user in advance. Specifically, when the server authentication unit  31 A receives, for example, a variety of access requests (for example, a distribution request or an update request) from the portable terminal  21  of the registered user such as the doctor D 1 , the server authentication unit  31 A transmits an input screen in which a message for requesting a user to input the server authentication information is described, to the portable terminal  21 . In case where the server authentication information is input in the input screen by the user, the server authentication information is transmitted from the portable terminal  21  to the image server  13 . The server authentication unit  31 A compares the server authentication information transmitted from the portable terminal  21  with the server authentication information registered for each user in the first user registration table  37 . In case where the server authentication information transmitted from the portable terminal  21  and the registered server authentication information match as a result of the comparison, the server authentication unit  31 A determines that the user has an access right, and permits access. In case where the server authentication information transmitted from the portable terminal  21  and the registered server authentication information do not match, the server authentication unit  31 A denies access. 
         [0062]    The request reception unit  31 B receives a variety of access requests from the portable terminal  21  of which the access is permitted, and distributes the received access requests to respective units according to content of the requests. For example, when the request reception unit  31 B receives an image distribution request, the request reception unit  31 B inputs the image distribution request to the image distribution unit (not illustrated). In the case of an update request, the request reception unit  31 B inputs the update request to a database updating unit. Further, in case where the request reception unit  31 B receives the access right granting request (see  FIG. 2 ), the request reception unit  31 B inputs the access right granting request to the first user registration unit  31 C. The access right granting request is a request for granting the access right to a terminal of an unregistered user to which the access right has not been granted, as described above. 
         [0063]    In case where the access right granting request is input, the first user registration unit  31 C performs user registration of the unregistered user based on the content of the access right granting request, issues the server authentication information, and performs a first user registration process. An email address of a target that is an unregistered user that is an granting target of the access right, and a validity period are included in the access right granting request. The first user registration unit  31 C registers content of the access right such as the validity period and the issued server authentication information in the first user registration table  37  in association with each other. 
         [0064]    As illustrated in  FIG. 4 , user registration information of each user is recorded in the first user registration table  37 . The user registration information includes items such as a user identification data (ID), a password (PASS), a user type, and the validity period of the access right. The server authentication information includes the user ID and the password in the user registration information. 
         [0065]    The user type includes, for example, two types: a standard user (standard) and a temporary user (temporary). The standard user is a staff member of hospital A that holds the image server  13 , such as the doctor D 1 . A validity period of the standard user is not limited. The temporary user is an external user outside hospital A, such as the doctor D 2  of hospital B, and is a user to which the access right is temporarily granted according to the access right granting request. In the case of the temporary user, the validity period designated in the access right granting request is set. For a user of which the validity period has expired, access is prohibited by the server authentication unit  31 A regardless of a determination result for the server authentication information. 
         [0066]    In case where the first user registration unit  31 C completes the first user registration process, the command issuing unit  31 D receives the server authentication information issued by the first user registration unit  31 C, and performs a process of issuing a command  38  including the server authentication information. The command  38  is a command for instructing the VPN router  16  to perform user registration and issue router authentication information. As will be described below, the command  38  is created in the form in which the command  38  is inserted into e-mail data  51  of an e-mail format (see  FIG. 7 ). 
         [0067]    The VPN router  16  is a computer device, and includes a CPU  41 , a memory  42 , a storage device  43 , and a communication I/F  44 , which are connected via a data bus (not illustrated). 
         [0068]    The storage device  33  is a device that stores various data, and includes, for example, a nonvolatile memory such as a flash memory or an electrically erasable programmable read-only memory (EEPROM). A router program  46  for causing the CPU  41  to function as the VPN router  16  is stored in the storage device  43 . Further, a second user registration table  47  in which information on registered users who can access the VPN router  16  has been recorded is stored in the storage device  43 . 
         [0069]    The memory  42  is a work memory used for the CPU  41  to execute a process and includes, for example, a RAM. The CPU  41  loads the router program  46  stored in the storage device  43  into the memory  32 , and executes the process according to the program to overall control respective units. The communication I/F  44  performs transfer control for connection to the Internet  18  and the LAN  17 . The VPN router  16  relays communication between the client terminal  14  or the image server  13  connected to the LAN  17  and the external portable terminal  21  that performs access over the Internet  18 , via the communication I/F  44 . 
         [0070]    A program for realizing the router authentication function serving as a part of the VPN access control function, in addition to as the router function, is included in the router program  46 . In case where the router program  46  starts up, the CPU  41  cooperates with the memory  42  to function as a router authentication unit  41 A, a routing processing unit  41 B, a second user registration unit  41 C, and an authentication information transmission unit  41 D. Here, the server program  36  and the router program  46  constitute a program of the VPN control system. 
         [0071]    The router authentication unit  41 A performs an authentication process to determine whether to permit access to the VPN router  16 , based on the router authentication information provided to the registered user in advance. Specifically, in case where the router authentication unit  41 A receives the IP packet from the external Internet  18 , the router authentication unit  41 A identifies whether the IP packet is an IP packet corresponding to the VPN prior to authentication. The IP packet corresponding to the VPN is encrypted by, for example, an encryption technology, such as IPsec. In case where the received IP packet is the IP packet corresponding to the VPN, the router authentication unit  41 A proceeds to an authentication process for the IP packet. On the other hand, in case where the received IP packet does not correspond to the VPN, the router authentication unit  41 A discards the IP packet without proceeding to the router authentication process. 
         [0072]    The router authentication unit  41 A reads the router authentication information from the decoded IP packet in the router authentication process, and compares the read router authentication information with the router authentication information registered for each user in the second user registration table  47 . For example, as illustrated in  FIG. 5 , the IP packet includes user data that is used by an upper application than TCP/IP, and an IP header defined by TCP/IP. Also, the IP header is assumed to include a TCP header used by TCP, in addition to the IP header used by IP. 
         [0073]    The user data is, for example, various access requests transmitted from the portable terminal  21  of the registered user, such as the doctor D 1 . Address information including a destination address (DA) of the IP packet and a source address, and transfer control information associated with transfer control are included in the IP header. The router authentication information, for example, is added to the IP header by the VPN client software  22  in the portable terminal  21 . 
         [0074]    In case where the router authentication information read from the IP header and the router authentication information read from the second user registration table  47  match as a result of the comparison, the router authentication unit  41 A determines that the user has an access right, and permits access. In case where the router authentication information read from the IP header and the router authentication information read from the second user registration table  47  do not match, the router authentication unit  41 A denies access. In case where the router authentication unit  41 A permits access, the router authentication unit  41 A inputs the received IP packet to the routing processing unit  41 B. 
         [0075]    The routing processing unit  41 B performs routing based on the address information included in the IP packet for which the access is permitted, and transfers the IP packet to the destination address. On the other hand, in case where the routing processing unit  41 B transfers the IP packet from the LAN  17  to the external Internet  18 , the routing processing unit  41 B encrypts the IP packet and then performs the routing. 
         [0076]    Further, in case where the IP packet input from the router authentication unit  41 A includes the command  38  from the image server  13 , the routing processing unit  41 B inputs the IP packet including the command  38  to the second user registration unit  41 C instead of transferring the IP packet including the command  38 . In the routing processing unit  41 B, the determination as to whether the command  38  is included in the received IP packet is performed as follows. 
         [0077]    As illustrated in  FIG. 6 , the command  38  from the image server  13  is transmitted as the user data of the IP packet, similar to the access request illustrated in  FIG. 5 . The routing processing unit  41 B determines, for example, that the command  38  from the image server  13  is included in the user data in case where the source address (SA) is the image server and the destination address (DA) is a VPN router address based on the address information included in the IP header. 
         [0078]    A registration request command for requesting the VPN router  16  to perform the second user registration with respect to the user for which first user registration has been performed in the image server  13 , and an authentication information transmission request command for requesting transmission of the authentication information including the server authentication information and the router authentication information to the terminal of the user after the second user registration are included in the command  38 . The command  38  is inserted into the e-mail data  51  of a typical e-mail format that can be received by a terminal such as the portable terminal  24 , as will be described below. 
         [0079]    In  FIG. 3 , in case where the command  38  is input, the second user registration unit  41 C issues router authentication information and executes the second user registration. The second user registration unit  41 C performs the user registration of the unregistered user according to the command  38  and issues the router authentication information. The second user registration unit  41 C registers content of the access right, such as a validity period, and the router authentication information in the second user registration table  47  in association with each other. The second user registration table  47  has substantially the same configuration as the first user registration table  37  illustrated in  FIG. 4 , and is used for the authentication process of the router authentication unit  41 A. 
         [0080]    In case where the second user registration unit  41 C completes the second user registration, the second user registration unit  41 C executes an authentication information transmission process of transmitting the authentication information to the user to which an access right is granted. The VPN router  16  transmits the authentication information for the user, for example, in a general e-mail format that can be received by the portable terminal  24  or the like. Therefore, the image server  13  creates the e-mail data  51  that is a template of authentication information notification according to the format in which the VPN router  16  finally transmits the authentication information, and transmits the e-mail data  51  in the form in which the command  38  is inserted into the e-mail data  51 , to the VPN router  16 . 
         [0081]    As illustrated in  FIG. 7 , in the e-mail data  51 , an e-mail header and e-mail text are created according to content of the access right granting request received by the image server  13 , so that the e-mail data  51  can be used as an authentication information notification  52 . An e-mail address of the target to which the access right is granted is input to a transmission destination of the e-mail header, and a title such as guidance of server access permission is input to a subject field. For example, information on a requester, “access to the server is permitted”, a message such as description of a procedure of accessing the server, such as downloading of software for access (for example, the VPN client software  22 ), server authentication information issued in the image server  13 , a server address (URL: Uniform Resource Locator) or an IP address of the image server  13 , and the command  38  are included in the e-mail text. 
         [0082]    The second user registration unit  41 C reads the command  38  from the e-mail data  51 , issues the router authentication information based on the command  38 , and executes a second registration process. The authentication information transmission unit  41 D receives the e-mail data  51  and the router authentication information from the second user registration unit  41 C, and changes the e-mail data  51  to insert the router authentication information instead of the command  38 . Accordingly, the authentication information notification  52  including the server authentication information and the router authentication information is created. 
         [0083]    In  FIG. 3 , the authentication information transmission unit  41 D receives the authentication information notification  52  from the second user registration unit  41 C, and transmits the authentication information notification  52  to the destination of the e-mail header via the routing processing unit  41 B. The authentication information notification  52  is data that is transmitted to an unregistered user. Accordingly, in a step in which the authentication information notification  52  is transmitted to the portable terminal  24  of the doctor D 2 , the VPN client software  22  is not installed in the portable terminal  24 . Thus, encryption communication using the VPN cannot be performed. However, prevention of leakage of the authentication information to the outside is highly required so as to ensure information security of the hospital system  10 . 
         [0084]    Therefore, as illustrated in  FIG. 8 , in case where the authentication information transmission unit  41 D creates the authentication information notification  52  (step (S)  100 ), the authentication information transmission unit  41 D encrypts, in the authentication information notification  52 , the authentication information (the server authentication information or the router authentication information) included in the e-mail text into information that can be decrypted by the VPN client software  22  (S  110 ). Accordingly, even in case where the e-mail data  51  leaks to the outside, the leakage of the authentication information to the outside is prevented since the authentication information is encrypted. 
         [0085]    Further, the server address may be may encrypted, in addition to or in place of the authentication information. In case where the server address is encrypted, the access destination is not recognized even in case where the authentication information leaks, and thus, the information security is ensured. It is understood that it is preferable to encrypt both of the authentication information and the server address. 
         [0086]    There is low need for prevention of leakage of parts other than the authentication information and the server address. In addition, description of an access procedure or the like makes no sense if the user of the portable terminal  24  cannot interpret the description. Therefore, encryption is not performed on any parts other than the authentication information and the server address. The authentication information transmission unit  41 D transmits the authentication information after the encryption ends (S  120 ). 
         [0087]    An operation of the above configuration will be described with reference to a flowchart illustrated in  FIG. 9 . For example, it is assumed that in case where the doctor D 1  of hospital A exits the hospital, the doctor D 1  receives a request for diagnosis of an inspection image of a patient from hospital A in an emergency. In such a case, the doctor D 1  may respond to the request in an emergency. In case where the doctor D 1  cannot respond to the request, the doctor D 1  contacts another doctor of hospital A to request the other doctor to interpret the inspection image. Further, in case where the doctor in hospital A cannot respond to the request, it may be necessary to request the doctor D 2  of hospital B other than hospital A to interpret the inspection image. 
         [0088]    In this case, since the doctor D 1  contacts the doctor D 2  to request the doctor D 2  to interpret the inspection image and provides the doctor D 2  with a right to access the image server  13  of the hospital system  10  of hospital A, the doctor D 1  delivers that the doctor D 1  desires the doctor D 2  to access the hospital system  10  and download the inspection image. In case where consent of the doctor D 2  is obtained, the doctor D 1  performs a process of granting, to the doctor D 2 , the right to access the hospital system  10  from the portable terminal  21 . 
         [0089]    As illustrated in  FIG. 9 , the doctor D 1  that is a requester of the interpretation accesses the image server  13  from the portable terminal  21 , and downloads the access right grant application screen  27  (see  FIG. 2 ). In the access right grant application screen  27 , an e-mail address of an access right granting target (doctor D 2 ) and a validity period of the access right are input. In case where the OK button  27 C is operated, an access right granting request is transmitted from the portable terminal  21  to the image server  13 . 
         [0090]    Since the doctor D 1  is a user that is a registered user of the image server  13  or the VPN router  16 , the doctor D 1  is provided with the router authentication information and the server authentication information. Further, since the VPN client software  22  is installed in the portable terminal  21  of the doctor D 1 , the portable terminal  21  can accept router authentication of the VPN router  16  or the server authentication of the image server  13 . 
         [0091]    In case where the image server  13  receives the access right granting request, the first user registration unit  31 C issues the server authentication information and executes the first user registration process. In case where the first user registration unit  31 C completes the first user registration process, the command issuing unit  31 D issues the command  38  to the VPN router  16 . The command  38  is inserted into an e-mail text of the e-mail data  51  that is a template of the authentication information notification. The e-mail data  51  including the command  38  is sent to the VPN router  16 . 
         [0092]    In the VPN router  16 , the routing processing unit  41 B determines whether the command  38  is included in the user data of the received IP packet based on address information of the IP header of the received IP packet. The IP packet that does not include the command  38  is subjected to normal routing and transferred to a transfer destination. In case where the command  38  is not included in the IP packet, the routing processing unit  41 B inputs the user data of the IP packet including the command  38  to the second user registration unit  41 C. The second user registration unit  41 C issues the router authentication information according to the command  38 , and executes a second user registration process. 
         [0093]    The authentication information transmission unit  41 D creates an authentication information notification  52  based on the e-mail data  51  and the router authentication information, encrypts the authentication information according to the procedure illustrated in  FIG. 8 , and transmits the authentication information to the portable terminal  24  of a destination of the e-mail data  51  (the doctor D 2  who is a target to which the access right is granted). Accordingly, the access right is granted to the doctor D 2  that is a request destination for the interpretation, and remote access to the hospital system  10  using the VPN can be performed from the portable terminal  24 . 
         [0094]    In case where the doctor D 2  receives the authentication information notification  52  in the portable terminal  24 , the doctor D 2  downloads the VPN client software  22  from the WEB server  23  according to an instruction of the authentication information notification  52  and installs the VPN client software  22  in the portable terminal  24 . In case where the installation completes, the VPN client software  22  decrypts and decodes the encrypted authentication information in the authentication information notification  52 . The doctor D 2  accesses the server address of the image server  13  described in the authentication information notification  52  using the portable terminal  24  after completing the installation. 
         [0095]    Since the portable terminal  24  has the VPN client software  22  and the router authentication information, the portable terminal  24  can skip the router authentication of the VPN router  16 . Further, in case where the portable terminal  24  receives a request for the server authentication information from the image server  13 , the portable terminal  24  inputs the server authentication information and thus, can also skip the server authentication. Also, the portable terminal  24  can receive distribution of the designated inspection image from the image server  13 . Accordingly, the doctor D 2  becomes able to interpret the distributed inspection image. 
         [0096]    In case where the validity period of the authentication information has expired, the image server  13  or the VPN router  16  automatically deletes the registration of the doctor D 2 . Due to the registration deletion, the access right of the doctor D 2  lapses, and the doctor D 2  becomes an unregistered user. Accordingly, the access to the hospital system  10  is prohibited. 
         [0097]    According to this embodiment, since the right to access both the image server  13  and the VPN router  16  can be granted based on the access right granting request from the terminal of the registered user as described above, it is possible to reduce the effort of work of the administrator performing registration work of the image server  13  or the VPN router  16 , and quickly control remote access using the VPN. 
         [0098]    Setting work of the VPN router  16 , such as user registration, requires highly specialized knowledge, as compared to setting of the image server  13 . The VPN router  16  has the configuration of the second user registration unit  41 C and the authentication information transmission unit  41 D, and thus, the setup work in the VPN router  16  is automated. Accordingly, simple and rapid access right granting becomes possible. 
         [0099]    Further, in this embodiment, the configuration in which the access right is granted to the unregistered user based on the access right granting request from the registered user is adopted. Since this is to grant the access right based on reliability of the registered user, reliability can be ensured without identification of the unregistered user. Therefore, it is possible to reduce the effort of the administrator. 
         [0100]    Further, in this embodiment, first, the access right granting request is transmitted to the image server  13 , and thus, the image server  13  executes a first user registration process including issuing of the server authentication information. Second, the command is transmitted from the image server  13  to the VPN router  16 , and thus, the VPN router  16  performs a second user registration process including issuing of the router authentication information. The image server  13  performs a primary process and the VPN router  16  performs a secondary process in this way, and thus, it is possible to reduce a processing load or modification of the VPN router  16 . 
         [0101]    Further, since the VPN router  16  is a communication device that performs routing based on the IP header of the IP packet as described above, the VPN router  16  does not inherently have a function of executing a process by referring to the user data of the IP packet. Therefore, it is preferable to minimize the addition of a function other than routing to the VPN router  16 . 
         [0102]    For example, in case where the first process is performed by the VPN router  16 , it is necessary to determine the IP packet including the access right granting request from among IP packets received by the VPN router  16 . However, since a determination cannot be performed as to which of the IP packets received from the outside includes the access right granting request based on only information on the IP header, it is necessary for the VPN router  16  to refer to the user data of all the IP packets. Then, a processing load on the VPN router  16  increases. 
         [0103]    On the other hand, since the image server  13  inherently includes the request reception unit  31 B that performs a process by referring to the user data in the IP packet unlike the VPN router  16 , a processing load of the image server  13  does not increase unlike the VPN router  16 . In this embodiment, the access right granting request is transmitted to the image server  13 , the image server  13  performs the primary process, and the VPN router  16  performs the secondary process according to the command  38  from the image server  13 . 
         [0104]    Then, the routing processing unit  41 B of the VPN router  16  can determine that the IP packet transmitted from the image server  13  to the VPN router  16  is the IP packet including the command  38  based on the address information without referring to the user data, as described above. Therefore, a processing load does not increase, and a small modification is needed, unlike the case of referring to the user data of all IP packets. Further, since there is no need to examine the content of all the user data, it is possible to minimize delay in the routing process. 
         [0105]    Further, the command  38  from the image server  13  to the VPN router  16  is transmitted in an e-mail format. Specifically, the command  38  is transmitted using the e-mail data  51  that is a template of the authentication information notification  52 . It is possible to further reduce a processing load or modification of the VPN router  16  having routing of the IP packet as an original function. 
         [0106]    While the destination of the authentication information notification  52  has been the target (the doctor D 2  of hospital B in the above example) to which the access right is granted, who is an unregistered user in the embodiment, the destination may be a source (the doctor D 1  of hospital A in the above example) of the access right granting request. In this case, it is necessary to transfer the authentication information notification  52  from the source of the access right granting request to the access right granting target. Therefore, it is preferable for the destination of the authentication information notification  52  to be the target to which the access right is granted, as shown in the above embodiment. 
         [0107]    While the first user registration unit  31 C and the second user registration unit  41 C set the validity period designated in the access right granting request in the above embodiment, for example, an initial value of the validity period that has been set in advance, such as one day or one week, may be set in case where there is no designation. 
         [0108]    While the example in which the temporary access right is granted according to the access right granting request has been described in the above embodiment, the present invention may be used in case where a permanent access right such as the access right of the standard user is granted. 
         [0109]    While the VPN access control system has been described as a combination of the image server  13  and the VPN router  16  by way of example in the above embodiment, the VPN access control system may be a combination of another server such as the medical record server  12  in place of or in addition to the image server  13  and the VPN router  16 . 
         [0110]    In the above embodiment, the example in which the server constituting the VPN access control system is the medical information server, such as the image server  13  or the medical record server  12 , that distributes medical information such as the inspection image or the medical record have been described. Since medical information includes a large amount of information on privacy, it is highly necessary to increase information security. Therefore, it is particularly preferable for the VPN access control system to be used for a medical information system that deals with medical information. Further, in case where the medical information server constitutes the hospital system  10 , a higher level of information security is required, and thus, there is greater need for the information security. 
         [0111]    Also, the medical information server may not be installed in the medical facility, unlike the above embodiment. For example, the medical information server may be installed in a data center shared among a plurality of medical facilities. Further, the medical information server may be used for an information system that deals with information other than medical information. The VPN access control system of this embodiment is effective in an information system requiring high information security, other than the medical information system.