JP5321030B2 - COMMUNICATION DEVICE, COMMUNICATION METHOD, AND PROGRAM - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide communication equipment, a communication method, and a program for performing communication that uses a highly anonymous address regularly changed. <P>SOLUTION: Pieces of communication equipment (20, 100) include: storage means for storing an address registration table 116 for registering one or more anonymous addresses together with expiration dates; a generation means 112 for generating an anonymous address, allocating it to a network interface 140, setting an expiration date, and adding it to the address registration table 116; a transmission means 120 for switching in response to generation and transmitting to the address a message which designates a response destination including the anonymous address; a deletion means 114 for allocating the anonymous address that has expired to the network interface 140 and deleting it from the address registration table 116; and a receiving means 130 for waiting for reception of the message addressed to the anonymous address registered until the expiration date expires. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a network communication technique, and more particularly, to a communication device, a communication method, and a program that execute communication using a highly anonymous IP (Internet Protocol) address that is periodically changed.

  IPv6 (IP Version 6) solves the problem of IP address depletion, which was a concern in IPv4 (IP version 4), and also provides security protection by IPsec (Security Architecture for Internet Protocol) at the IP layer, thereby enabling end-to- It is a next-generation IP network standard that realizes end secure communication.

  The IPv6 includes a stateless address automatic generation function that automatically generates a unicast address assigned to a host. According to this stateless address automatic generation function, the host receives the router advertisement message notified from the neighboring router, and further uses the host's own information, so that the IPv6 address is not manually set in advance. An address (hereinafter, unless otherwise specified, an IP address means an IPv6 address) is automatically generated. In this stateless address, the lower 64 bits of the host address part (including the interface identifier) is usually in a format such as EUI-64, and the link layer address (MAC address or the like: Media Access Control Address) of the network interface. Generated from

  However, since the network identifier of the stateless address is generated based on the link layer address, there has been a problem that the activity on the Internet by a specific user can be easily traced. In order to solve such privacy problems of IPv6, an extension that automatically generates anonymity addresses (hereinafter referred to as anonymous addresses) is an RFC (Request for Comments) by IETF (Internet Engineering Task Force). ) 3041 (Non-Patent Document 1). In the RFC3041, it is proposed that the anonymous address automatically generated within one day as the recommended period and within seven days at the longest is switched to a new one as a standard value.

  In communication using this anonymous address, a non-anonymous IP address is registered in the DNS server so that the other party can transmit data to itself, and is transmitted with a fully qualified domain name (FQDN). On the other hand, when transmitting to the other party, the above anonymous address is used instead of the fully qualified domain name in order to ensure anonymity. Also, in the broadband environment, registration to the DNS server is not performed, and it is assumed that an anonymous address is used as it is instead of a fully qualified domain.

  In relation to the problem of address privacy due to traffic analysis, Japanese Patent Laid-Open No. 2006-173673 (Patent Document 1) generates, for example, a temporary link local address in response to power-on or reboot of a communication device. Thus, a configuration is disclosed in which a random MAC address is generated, and when the random MAC address is confirmed to be unique within the link, the random MAC address is assigned to a communication interface.

In addition, a technique for changing an IP address for each session has been proposed in connection with secure communication. For example, Japanese Patent Laid-Open No. 2006-5606 (Patent Document 2) distributes a one-time address from a terminal by providing a network with a mechanism for distributing a one-time address, which is a temporary IP address, to a terminal. Discloses a technique for starting a communication session based on a distributed one-time address. In this prior art, the distributed one-time address is discarded after the communication session ends.
JP 2006-173673 A JP 2006-5606 A IETF RFC 3041 Privacy Extensions for Stateless Address Autoconfiguration in IPv6, January 2001

  By the way, with recent broadbandization of networks, facsimile terminals having an Internet FAX communication function for realizing facsimile communication via the network are becoming widespread. As the Internet FAX, ITU-T (International Telecommunication Union Telecommunication Standardization Sector) recommendation T.T. There is a so-called storage and exchange type that conforms to 37.

  In the storage-type Internet FAX, transmission / reception is usually performed via an external mail server. On the other hand, with the spread of IPv6 described above, an IP address is assigned to each communication device, and in the future, so-called direct SMTP (direct SMTP) in which image information is directly exchanged between facsimile terminals without going through an external mail server. Simple Mail Transfer Protocol) is expected to become popular.

  In the above-described storage type Internet FAX, message delivery confirmation (MDN: Message Disposition Notifications) of the electronic mail distribution system is used for confirmation of FAX image delivery. When receiving the electronic mail, the Internet FAX terminal analyzes the electronic mail and determines whether or not the “Disposition-Notification-To:” field is included in the header portion. When the “Disposition-Notification-To:” field is included in the e-mail, the Internet FAX terminal determines that the read confirmation is requested, and performs the MDN for the mail address specified in the field value. Respond. This MDN response is not necessarily performed at the time of reception, and may be transmitted with a certain time difference.

  According to the anonymous address of RFC3041, the privacy problem of IPv6 is preferably solved. However, since the anonymous address of RFC3041 is normally updated to a new address periodically, a problem may arise when an MDN response occurs in a session different from that at the time of transmission. In other words, when an MDN response is made by the receiving side, the anonymous address used at the time of sending the mail requesting the MDN has already been changed, and there is a possibility that the MDN may not reach the sending side.

  Even in normal e-mail, when an e-mail requesting confirmation of opening is received, an MDN is returned after the e-mail is opened. In addition, in an Internet / fax terminal set for paperless reception, an MDN response may be made when an e-mail is opened with a key of printing output and receipt from a personal computer. Even in such a case, the anonymous address of RFC3041 may cause a problem.

  The prior art of Patent Document 1 tries to protect the privacy by randomly generating a MAC address. In the prior art disclosed in Patent Document 2, the one-time address is discarded after the communication session ends. Is done. For this reason, the prior arts of Patent Document 1 and Patent Document 2 do not attempt to cope with a case where an MDN response having a time difference occurs.

  In other words, in communication using a highly anonymous address that is regularly updated, even if a response occurs in a different session, it is desirable to develop a technology that can receive the response while maintaining anonymity. It was rare.

  The present invention has been made in view of the above problems, and the present invention is an anonymous address used by a response addressed to the anonymous address in communication using an anonymous address that is periodically changed and has high anonymity. To provide a communication device, a communication method, and a program capable of receiving a response until an expiration date determined for an anonymous address even if the session has been performed in a different session after switching Objective.

  In the present invention, in order to solve the above-described problem, first, an address registration table for registering one or more anonymous addresses having anonymity together with an expiration date is secured in the storage unit of the communication device. Then, an anonymous address is generated, assigned to the network interface, an expiration date is set, and the anonymous address is added to the address registration table. On the other hand, the anonymous address whose expiration date has expired is deleted from the network interface assignment and address registration table.

  The communication device switches the anonymous address to be used in response to the generation, and transmits a message specifying the response destination including the anonymous address to the destination via the network. And after switching the anonymous address to be used, the communication apparatus is registered in the address registration table and waits for reception of a message addressed to the anonymous address until the expiration date expires.

  With the above configuration, even after the anonymous address to be used is switched, at least until the expiration date of the anonymous address, the assignment of the anonymous address to the network interface is maintained, and the message directed to the destination including the anonymous address Can be received. Moreover, even if the interval for switching the anonymous address used for transmission is shortened, a period during which a response can be received can be sufficiently ensured, so that the level of privacy protection can be suitably increased.

  Further, according to the present invention, it is possible to extend the expiration date of the used anonymous address within the allowable maximum expiration date in response to the transmission of the message specifying the response destination including the anonymous address. With the above configuration, when a transmission requesting a response is executed, the expiration date can be extended within the allowable maximum expiration date. In other words, only the anonymous address that has the possibility of receiving a response has its expiration date extended. For this reason, it becomes possible to release the resource for managing an anonymous address with little possibility of receiving a response at an early stage.

  Furthermore, according to the present invention, an upper limit is set for the number of registrations in the address registration table, and when the number of registrations reaches the maximum number that can be registered, it is possible to delete from the anonymous address with the closest maximum expiration date. With the above-described configuration, it is possible to adapt to finite resource constraints such as the memory and the number of sockets of the communication device. In addition, the router in the same link as the communication device has a limitation on the capacity of the neighborhood cache, but by limiting the number of registrations by the above configuration, it can be adapted to the resource limitation on the router side. Become.

  Furthermore, according to the present invention, a transmission log can be registered in the log registration table in correspondence with the transmission of a message. Then, the message addressed to the anonymous address can be received, and the response reception can be recorded in the corresponding transmission log of the log registration table. And the deletion process of an anonymous address can postpone the deletion within the range of a maximum expiration date about the anonymous address which has not received a response.

  With the above configuration, the deletion of the anonymous address that has not yet received the requested response is postponed within the maximum allowable expiration date even when the expiration date is exceeded. Therefore, considering the capacity of the storage means for storing the address registration table, even if the expiration date set for the anonymous address is shortened, sufficient waiting time is required for the anonymous address required for waiting for a response. Can be secured. And it is possible to release resources for the management of anonymous addresses that do not require waiting for a response at an early stage. Normally, there is an upper limit for the number of registrations in the log registration table. However, the above configuration is effective for the old anonymous address when the mail transmission log is deleted even if the requested MDN response has not yet been received. Has the advantage of being deleted.

  Further, according to the present invention, when retransmission corresponding to the transmission log of the log registration table is executed, it is possible to cancel the response non-reception of the transmission log of the log registration table. The above configuration has an advantage that old anonymous addresses that are no longer needed due to retransmission are efficiently deleted because the record of unsent responses in the previous transmission log that has been retransmitted is released.

  According to the present invention, it may further include router advertisement detection means for acquiring a router advertisement message and registering a network prefix included in the router advertisement message in a prefix registration table together with a time limit. Then, the anonymous address including the network prefix that has expired can be deleted. The above configuration is anonymity that cannot be used in response to changes in the network environment, such as when the router breaks down, the communication device is connected to another link, or the power is turned on after a long disconnection This has the advantage that addresses can be deleted efficiently.

  Hereinafter, although it demonstrates using embodiment of this invention, embodiment of this invention is not limited to the following embodiment. In the following embodiment, as an example of a communication apparatus, ITU-T recommendation T.30. A facsimile (hereinafter referred to as “FAX”) image communication that conforms to 37 will be described using an Internet FAX apparatus capable of performing image communication.

  FIG. 1 is a schematic diagram showing a network environment according to the present embodiment. A network environment 10 shown in FIG. 1 includes a first LAN (Local Area Network) 12 to which a first Internet FAX device 20 as a communication device is connected, and the Internet connected to the first LAN 12 via a router 22. 14 and the like. The Internet 14 is further connected to the second LAN 16 via the router 24. Similarly, the second LAN 16 has an ITU-T recommendation T.30. A second Internet FAX device 26 capable of executing FAX image communication conforming to 37 and a laptop computer (hereinafter referred to as a laptop) 28 equipped with e-mail software and the like are connected.

  In the network environment 10, each of the hosts such as the Internet FAX apparatuses 20 and 26 and the laptop 28 has an appropriate transport layer / network layer protocol such as TCP (Transmission Control Protocol) and IPv6 (Internet Protocol version 6). Use interconnected. The specific configuration of the network environment 10 is not particularly limited. For example, a configuration in which the Internet 14 is replaced with an intranet can be adopted, and a configuration in which the first LAN 12 and the second LAN 16 are connected between bases via the Internet 14 by a VPN (Virtual Private Network) can also be adopted.

  The first Internet FAX apparatus 20 is connected to the first LAN 12, receives a router advertisement message from the router 22, and automatically configures its link local address (if the address is not otherwise specified) by stateless address automatic configuration. An IPv6 address shall be referred to)) and a global address is assigned. Similarly, the second Internet FAX device 26 and the laptop 28 also receive the router advertisement message from the router 24 and are assigned a link local address and a global address. In addition, the host connected to the LAN may be assigned an address by a stateful address automatic configuration by a DHCPv6 (Dynamic Host Configuration Protocol version 6) server.

  In the present embodiment, the first Internet FAX apparatus 20 is configured to be capable of FAX image communication by direct SMTP. Direct SMTP is a technique for connecting terminals directly via SMTP without going through a mail server in order to realize immediacy of FAX image transmission by e-mail.

  The first Internet FAX apparatus 20 of the present embodiment registers a public global IP address in a DNS (Domain Name Server) (not shown). The public global IP address is associated with the fully qualified domain. As a result, other terminals such as the second Internet FAX apparatus 26 specify the destination of the e-mail address including the fully qualified domain associated with the public global IP address, and thereby the first Internet FAX apparatus 20 is addressed. FAX image transmission is possible.

  The first Internet FAX apparatus 20 further automatically configures a temporary address (hereinafter referred to as an anonymous address) that is protected by privacy as defined in RFC3041. The first Internet FAX apparatus 20 uses this anonymous address when transmitting a FAX image to another terminal. When transmitting a FAX image from the Internet FAX apparatus 20 to another terminal, the FAX image data is attached to an e-mail addressed from an e-mail address including an automatically configured anonymous address, and transmitted by SMTP. When requesting MDN (Message Disposition Notifications), a “Disposition-Notification-To:” field (hereinafter referred to as a response destination field for simplicity) of the header of the e-mail is created, and this anonymous address is set. Specify the email address that you want to include as the response destination.

  On the other hand, the terminal that has received the electronic mail from the first Internet FAX apparatus 20 checks the presence or absence of the response destination field and determines the presence or absence of the MDN request. When an MDN is requested, the e-mail address described in the response destination field is designated and the MDN response mail is transmitted by SMTP. The first Internet FAX apparatus 20 according to the present embodiment can receive an MDN response mail whose destination is an electronic mail address including the anonymous address only during a period when the anonymous address is valid. The MDN response mail is delivered to the first Internet FAX apparatus 20 if the anonymous address included in the destination electronic mail address is within a valid period. Details of the period for which the anonymous address is valid will be described later.

  FIG. 2 shows a schematic configuration of the Internet FAX apparatus 20 of the present embodiment. An Internet FAX apparatus 20 shown in FIG. 2 includes a control unit 30 that performs overall control of the apparatus, a display device for displaying an operation screen, an operation panel 32 that includes operation keys for waiting for data input and operation instructions, A memory 34 for storing data and a nonvolatile memory 42 for storing various registration tables to be described later are included.

  Further, the Internet FAX apparatus 20 includes a scanner 38 that reads a document image and converts it into an electrical signal, a plotter 40 that prints the received FAX image, and a data compression / decompression unit (DCR: Data Compression) that compresses and decompresses image data. and a reconstruction control unit (CCU) 46 for controlling line connection.

  Furthermore, the Internet FAX apparatus 20 of this embodiment includes TCP / IP, SMTP, and ITU-T recommendation T.264. 37 includes a network transmission control unit 36 that executes communication protocol control such as a FAX image communication protocol conforming to 37. The above-described components 30 to 46 are interconnected by a bus 48.

  Hereinafter, the anonymous address management function by the Internet FAX apparatus of this embodiment will be described in detail. FIG. 3 shows a functional block 100 of the Internet FAX apparatus 20 of the present embodiment. The functional block 100 shown in FIG. 3 includes an anonymous address management unit 110 that manages anonymous addresses, a mail transmission unit 120, a mail reception unit 130, and a network interface (hereinafter referred to as network I / F) 140. The network I / F 140 is an abstraction of the physical layer and the data link layer of the network transmission control unit 36 shown in FIG. Furthermore, the functional block 100 can be configured to include a router advertisement detection unit 150, a log management unit 160, and a job management unit 170.

  The mail transmission unit 120 executes mail transmission processing. When transmitting a FAX image by e-mail, the mail transmission unit 120 first converts a document image into an electrical signal by the scanner 38 and stores the image data in the memory 34. Subsequently, the mail transmission unit 120 uses the data compression / decompression unit 44 to compress the image data of the document image, for example, a compression code such as an MR (Modified Read) method, an MH (Modified Huffman) method, or an MMR (Modified Modified Read) method. Compression processing. Then, the mail transmission unit 120 is transmitted to the ITU-T recommendation T.30 by the network transmission control unit 36. 37, the compressed FAX image data is transmitted to the destination terminal according to the communication protocol defined by SMTP.

  The mail receiving unit 130 executes mail receiving processing. When receiving a FAX image by e-mail, the mail receiving unit 130 receives FAX image data from the counterpart terminal according to a communication protocol defined by SMTP and stores it in the memory 34. Subsequently, the mail receiving unit 130 decompresses the received FAX image data and reproduces the image data. Then, the mail receiving unit 130 stores the reproduced image data in the nonvolatile memory 42 or a hard disk (not shown), or causes the plotter 40 to print out the image data.

  The anonymous address management unit 110 manages anonymous addresses by generating anonymous addresses having anonymity and deleting expired anonymous addresses in accordance with the provisions of RFC 3041 that extends IPv6 stateless automatic configuration. ing. More specifically, the anonymous address management unit 110 includes an anonymous address generation unit 112, an anonymous address deletion unit 114, and an anonymous address registration table 116 that registers anonymous addresses.

  The anonymous address generation unit 112 generates an interface identifier randomized using a random number generation algorithm at a predetermined time interval, and information such as a network prefix (hereinafter simply referred to as a prefix) included in the router advertisement message. In addition, a global scope anonymous address is generated and assigned to the network I / F 140. The anonymous address generation unit 112 registers the newly allocated anonymous address in the anonymous address registration table 116 by setting the validity period and the like.

  A plurality of addresses such as a global address, a site local address, and a link local address can be assigned to the network I / F 140. When an address is assigned, the network I / F 140 performs duplication detection, path setting, and communication parameter setting, and sets so that packet transmission / reception using the address is possible.

  On the other hand, the latest anonymous address among the anonymous addresses assigned to the network I / F 140 is used for mail transmission by the mail transmission unit 120. That is, the anonymous address used for mail transmission is switched at a time interval (hereinafter referred to as a switching interval) generated by the anonymous address generation unit 112. Further, when requesting an MDN response, the mail transmission unit 120 specifies an e-mail address including the latest anonymous address used for mail transmission in the response destination field of the e-mail header.

  On the other hand, assignment of anonymous addresses other than the latest one to the network I / F 140 is maintained while it is valid. For this reason, even after the anonymous address to be used is switched, it is possible to receive packets addressed to an e-mail address including the anonymous address while the anonymous address is valid.

  FIG. 4 shows the data structure of the anonymous address registration table. The anonymous address registration table 116 shown in FIG. 4 includes a field 116a in which an anonymous address is input, a field 116b in which the expiration date is input, and a field 116c in which an allowable maximum expiration date is input. The maximum validity period of the field 116c can be a value obtained by adding the length of a given allowable maximum validity period to the date and time when the anonymous address is generated. The anonymous address registration table 116 is stored in the non-volatile memory 42 or a hard disk (not shown), read out at the time of activation, and stored in the memory 34.

  Although the expiration date of the anonymous address is not particularly limited, the switching interval (for example, one day which is the standard value of RFC3041) is added to the date and time when the anonymous address is generated, and a certain period (for example, 1) (Day) can be added to obtain a value. Further, the expiration date of the anonymous address can be set to a maximum expiration date allowable from the beginning (for example, 7 days which is a standard value of RFC3041).

  Furthermore, the expiration date of the anonymous address adopts a value obtained by adding the switching interval (for example, 1 day) to the date and time when the anonymous address is generated as the initial value, and a message requesting an MDN response is transmitted In addition, the transmission date and time can be updated to a value obtained by adding a certain period (for example, one day). However, the expiration date of the anonymous address is within the range of the maximum expiration date.

  The anonymous address registration table 116 can also have an upper limit on the number of anonymous addresses registered. Hereinafter, the upper limit of the registration number is referred to as the maximum registration number. For example, the maximum allowable number of registrations can be set in advance according to the capacity of the nonvolatile memory 42 or the memory 34 that stores the anonymous address registration table 116.

  Referring again to FIG. 3, the anonymous address deletion unit 114 deletes the assignment of the anonymous address to the network I / F 140 in response to the expiration of the expiration date of the anonymous address registered in the anonymous address registration table 116. . At this time, the packet addressed to the anonymous address whose assignment has been deleted cannot reach the destination. Further, the anonymous address deleting unit 114 deletes the anonymous address whose expiration date has passed from the anonymous address registration table 116.

  After transmitting the message designating the MDN response, the mail transmission unit 120 can extend the expiration date of the used anonymous address within the maximum allowable expiration date. In this case, the email transmission unit 120 causes the anonymous address management unit 110 to rewrite and update the corresponding anonymous address in the anonymous address registration table 116 with a value obtained by extending the expiration date.

  The first Internet FAX apparatus 20 reads a program (not shown) stored in a storage device such as a nonvolatile memory 42, a hard disk (not shown), or an SD card (not shown), and stores the memory Each function unit described above and each process to be described later are realized by expanding to 34 memory areas.

  FIG. 5 is a flowchart showing the anonymous address management process of the first embodiment executed by the anonymous address management unit 110. In the anonymous address management process of the first embodiment, an upper limit is set for the number of registrations in the anonymous address registration table 116, and after sending a message designating an MDN response, the expiration date of the used anonymous address is maximized. A configuration that extends within the time limit is adopted.

  The process shown in FIG. 5 is started from step S100 in response to the activation of the Internet FAX apparatus 20, for example. In step S <b> 101, the anonymous address generation unit 112 executes an anonymous address generation process according to the provisions of RFC3041 and assigns a new anonymous address to the network I / F 140. This latest anonymous address is used for mail transmission as described above. Further, the anonymous address generation unit 112 calculates the expiration date and the maximum expiration date of the anonymous address, and further records the date and time when the anonymous address was generated. In step S102, the generated anonymous address is additionally registered in the anonymous address registration table 116 together with the expiration date and the maximum expiration date.

  In step S103, the anonymous address registration table 116 is referred to, and it is determined whether or not there is an anonymous address whose expiration date has passed among the registered anonymous addresses. If it is determined in step S103 that there is an anonymous address whose expiration date has passed (YES), the process proceeds to step S104.

  In step S <b> 104, the anonymous address deletion unit 114 executes an anonymous address deletion process for which the expiration date has passed, and deletes the assignment of the anonymous address to the network I / F 140. In step S105, the anonymous address deletion unit 114 further deletes the anonymous address whose assignment has been deleted from the anonymous address registration table 116, and advances the process to step S106. On the other hand, if it is determined in step S103 that there is no anonymous address with an expired expiration date (NO), the process proceeds directly to step S106.

  In step S106, it is determined whether or not a predetermined switching interval has elapsed since the generation of the anonymous address last time. If it is determined in step S106 that the switching interval time has not elapsed (NO), the process loops to step S103. On the other hand, if it is determined in step S106 that the switching interval has elapsed (YES), the process proceeds to step S107.

  In step S107, it is determined whether the number of addresses already registered in the anonymous address registration table 116 (hereinafter referred to as the number of registered addresses) is an allowable maximum number of registrations. In step S107, when the number of registered addresses is not the maximum registered number (NO), the process loops to step S101, and the anonymous address to be used is switched again by the anonymous address generation process.

  On the other hand, if the number of registered addresses is the maximum number of registered in step S107 (YES), the process proceeds to step S108. In step S <b> 108, the anonymous address deletion unit 114 executes an anonymous address deletion process with the smallest maximum expiration date. In other words, the anonymous address registered the oldest and the earliest valid expiration date is deleted. In step S <b> 109, the anonymous address deletion unit 114 further deletes the anonymous address having the youngest maximum expiration date from the anonymous address registration table 116. Then, the process is looped to step S101, and the anonymous address to be used is switched again by the anonymous address generation process. The process illustrated in FIG. 5 is repeated until, for example, the Internet FAX apparatus 20 is stopped.

  FIG. 6 is a flowchart illustrating a mail transmission process executed by the mail transmission unit 120 in the anonymous address management process of the first embodiment. The process shown in FIG. 37 FAX image transmission is instructed, and the process starts from step S200.

  In step S201, the mail transmission unit 120 attaches the FAX image data of the document image to the e-mail and transmits it to the destination terminal according to the communication protocol defined by SMTP. In step S202, the mail transmission unit 120 determines whether or not the message requests an MDN response. If it is determined in step S202 that an MDN response is not requested (NO), the process proceeds to step S209, and the mail transmission process is terminated.

  On the other hand, if it is determined in step S202 that an MDN response is required (YES), the process proceeds to step S203. In step S203, the mail transmission unit 120 determines whether the transmission is successful. If it is determined in step S203 that the process has failed (NO), the process proceeds to step S209, and the mail transmission process is terminated. On the other hand, if it is determined in step S203 that the process has succeeded (YES), the process proceeds to step S204.

  In step S204, the mail transmission unit 120 calculates an extended expiration date by adding an extra period (for example, one day) to the date and time at the time of transmission. In step S205, the maximum expiration date of the anonymous address used in the anonymous address registration table 116 is compared with the expiration date after extension, and it is determined whether or not the calculated expiration date exceeds the maximum expiration date. judge.

  If it is determined in step S205 that the extended expiration date exceeds the maximum expiration date (YES), the process proceeds to step S207. In step S207, the extended expiration date is set as the maximum expiration date, and the process proceeds to step S208. On the other hand, if it is determined in step S205 that the extended expiration date is within the maximum expiration date (NO), the process proceeds to step S206.

  In step S206, the expiration date of the anonymous address used for transmission in the anonymous address registration table 116 is compared with the expiration date after the extension, and the expiration date before the extension that is currently registered is extended. Judge whether or not. If it is determined in step S206 that the post-extension expiration date does not exceed the pre-extension expiration date (NO), the process proceeds to step S209 and the mail transmission process is terminated as it is. On the other hand, if it is determined in step S206 that the expiration date after extension exceeds the expiration date before extension (YES), the process proceeds to step S208.

  In step S208, the e-mail transmission unit 120 renews and updates the expiration date of the anonymous address used for transmission in the anonymous address registration table 116 with the above-described extension expiration date by the anonymous address management unit 110. End the email transmission process.

  According to the anonymous address management process of the first embodiment described above, an expiration date is provided for each anonymous address separately from the switching interval of the anonymous address to be used. And even after the anonymous address to be used is switched, at least during the expiration date of the anonymous address, the assignment of the anonymous address to the network I / F 140 is maintained, and the MDN response can be received. Further, even if the anonymous address switching interval is shortened, a sufficient period of time during which an MDN response can be received can be ensured, so that the level of privacy protection can be suitably increased.

  Further, according to the anonymous address management process of the first embodiment, when transmission requesting an MDN response is executed, the expiration date can be extended within the allowable maximum expiration date. That is, only the anonymous address that may receive the MDN response has its expiration date extended. For this reason, it becomes possible to release the resource for managing the anonymous address without the possibility of receiving the MDN response at an early stage.

  Furthermore, according to the anonymous address management process of the first embodiment, since the upper limit is set for the number of registered addresses in the anonymous address registration table 116, it is adapted to restrictions on finite resources such as the memory and the number of sockets of the Internet FAX apparatus 20. It becomes possible to make it. In addition, the router connected to the same link as the Internet FAX apparatus 20 has a limitation on the capacity of the neighborhood cache. However, by limiting the number of registered addresses, the router 22 can be adapted to the resource limitation on the router 22 side. It becomes possible.

  Hereinafter, the anonymous address management process of the second embodiment executed by the anonymous address management unit 110 will be described with reference to FIGS. 3 and 7 to 10. Note that the anonymous address management process of the second embodiment employs a configuration that manages anonymous addresses using a transmission log. In the anonymous address management process of the second embodiment, the configuration of the log management unit 160 and the job management unit 170 shown in FIG. 3 is used.

  Referring to FIG. 3 again, the log management unit 160 is configured to include a log registration table 162 that registers mail transmission logs. FIG. 7A shows the data structure of the log registration table. The log registration table 162 shown in FIG. 7A includes a field 162a in which an e-mail address of a transmission destination is input, a field 162b in which an anonymous address used at the time of transmission is input, and a job ID for identifying the mail transmission job. Field 162c in which is entered. Further, the log registration table 162 includes a field 162d in which a transmission result is input and a field 162e in which a reception result of an MDN response corresponding to mail transmission is input. Although FIG. 7A illustrates an e-mail address with an IP address direct designation address system, the e-mail address system that can be used with direct SMTP is not particularly limited. An address system that performs name resolution by DNS using a normal domain name may be used.

  A value indicating success or an error reason is input as a transmission result in the field 162d. In the field 162e, "response received" indicating that the MDN response has been received, "response not required" indicating that the MDN response was unnecessary transmission, and that the MDN response has not been received yet and is in a standby state. A value such as “response not received” or “response non-delivery” indicating that the MDN response has been given up due to timeout or the like is input.

  Referring to FIG. 3 again, after completing the FAX image transmission by e-mail, the mail transmission unit 120 causes the log management unit 160 to register a mail transmission log with the transmission result as history information. In addition, regarding the transmission of the message requesting the MDN response, the mail transmission unit 120 records “response not received” indicating the MDN response standby state in the mail transmission log. On the other hand, when mail transmission that does not require an MDN response is executed, the mail transmission unit 120 records “response unnecessary” indicating that the MDN response is unnecessary transmission as a response reception result of the mail transmission log.

  When receiving the MDN response message, the mail reception unit 130 causes the log management unit 160 to record “response reception” in the transmission log corresponding to the MDN response message. According to the specifications of RFC2298, the “Message-ID” field of a message requesting an MDN response is inherited by the “Original-Message-ID” field of the MDN response message. In the present embodiment, the transmission mail and the MDN response mail are associated with each other by embedding the job ID in “Message-ID” of the transmission mail. The “Message-ID” field is, for example, <[date and time] [random character string (2-byte ASCII)]. [Fixed character string (5-byte ASCII)]-J [Job ID (5-byte number)]-S [Sequence number (5-byte number)] @ [Domain name]> Each time the job ID is created, for example, it is incremented by one. The sequence number is also incremented by 1 each time it is transmitted.

  The anonymous address management unit 110 shown in FIG. 3 accepts an anonymous address that has not yet been recorded in response and is waiting for an MDN response, even if the anonymous address has expired. The deletion process can be postponed within the range of the maximum valid period allowed.

  The job management unit 170 includes a job registration table 172, and manages the progress of jobs instructed by an operator or the like. The job registration table 172 registers a FAX image transmission job requested to be executed and image data of a document used for the job in association with each other, and functions as a transmission job execution waiting queue. When receiving a FAX image transmission job by e-mail from the operator, the job management unit 170 additionally registers the job in the job registration table 172. The registered jobs are sequentially delivered to the mail transmission unit 120 and executed.

  FIG. 7B shows the data structure of the job registration table. A job registration table 172 shown in FIG. 7B includes a field 172a in which an e-mail address of a transmission destination is input, a field 172b in which a job ID is input, and a document ID for identifying original image data transmitted in the job. Field 172c into which is entered.

  Referring to FIG. 3 again, when the mail receiving unit 130 detects that a certain time has passed without receiving the MDN response message, it can instruct the job management unit 170 to perform retransmission. In response to the re-transmission instruction, the job management unit 170 registers the re-transmission job of the same job in the job registration table 172 and sequentially passes it to the mail transmission unit 120.

  When the transmission job is handed over, the mail transmission unit 120 detects transmission of retransmission by inquiring of the log management unit 160 whether a transmission log with the same job ID exists in the log registration table 162. It is assumed that the resent job ID matches the previous job ID. When the mail transmission unit 120 executes resending, the log management unit 160 cancels the MDN response standby state of the corresponding transmission log and records “response undelivered”.

  FIG. 8 is a flowchart illustrating a mail transmission process executed by the mail transmission unit 120 in the anonymous address management process of the second embodiment. The processing shown in FIG. 8 is started from step S300 when, for example, an operator instructs the FAX image transmission.

  In step S301, the mail transmission unit 120 inquires of the log management unit 160 and determines whether or not it is retransmission. If it is determined in step S301 that there is no transmission log with the same job ID as the job for which execution has been commanded and it is determined that the transmission is not retransmission (NO), the process proceeds to step S303. On the other hand, if it is determined in step S301 that there is a transmission log having the same job ID as the job for which execution has been instructed and it is determined that the transmission is retransmission (YES), the process proceeds to step S302. In step S <b> 302, the mail transmission unit 120 changes the response reception result field 162 e of the transmission log with the matching job ID in the log registration table 162 from “response not received” to “response not delivered” by the log management unit 160. Rewrite and update.

  In step S303, the mail transmission unit 120 attaches the FAX image data of the original image to the e-mail and transmits it to the destination terminal according to the communication protocol defined by SMTP. In step S304, the mail transmission unit 120 determines whether or not the message requests an MDN response. If it is determined in step S304 that an MDN response has been requested (YES), the process proceeds to step S305. On the other hand, if it is determined in step S304 that an MDN response is not requested (NO), the process proceeds to step S306.

  In step S <b> 305, the mail transmission unit 120 causes the log management unit 160 to register the transmission log of the job in the log registration table 162. At this time, “no response received” is recorded in the field 162e of the record to be registered. Then, the process proceeds to step S307, and the mail transmission process is terminated.

  On the other hand, in step S306, the mail transmission unit 120 causes the log management unit 160 to register the transmission log of the job in the log registration table 162, and records “response unnecessary” in the field 162e. Then, the process proceeds to step S307, and the mail transmission process is terminated.

  FIG. 9 is a flowchart illustrating a mail reception process executed by the mail reception unit 130 in the anonymous address management process of the second embodiment. The process shown in FIG. 9 is started from step S400 upon receipt of a message transmission from the counterpart terminal, for example.

  In step S401, the mail receiving unit 130 receives a message from the partner terminal in accordance with a communication protocol defined by SMTP. In step S402, the mail receiving unit 130 determines whether or not the message is an MDN response. In step S402, the determination can be made based on the presence / absence of the “Original-Message-ID” field, for example. If it is determined in step S402 that the response is an MDN response (YES), the process proceeds to step S403.

  In step S403, the mail receiving unit 130 first extracts a job ID from “Original-Message-ID” of the received message according to the above-described format. Then, the mail receiving unit 130 inquires of the log management unit 160 whether or not the same job ID is registered. Those with matching job IDs are searched from the log registration table 162, and the corresponding transmission log is specified. The mail receiving unit 130 causes the log management unit 160 to rewrite the response reception result field 162e of the mail transmission log from “response not received” to “response received” and update it. Then, the process proceeds to step S404, and the mail reception process is terminated. On the other hand, if it is determined in step S402 that the response is not an MDN response (NO), the process proceeds directly to step S404, and the mail reception process is terminated.

  FIG. 10 is a flowchart illustrating the anonymous address management process of the second embodiment executed by the anonymous address management unit 110. The process shown in FIG. 10 is started from step S500 in response to, for example, activation of the apparatus. In step S501, the anonymous address generation unit 112 executes an anonymous address generation process in accordance with the provisions of RFC3041. In step S502, the generated anonymous address is additionally registered in the anonymous address registration table 116 together with the expiration date and the maximum expiration date.

  In step S503, the anonymous address registration table 116 is referred to, and it is determined whether or not there is an anonymous address whose allowable maximum expiration date has passed among the registered anonymous addresses. If it is determined in step S503 that there is no anonymous address whose maximum expiration date has passed (NO), the process proceeds to step S504.

  In step S504, the anonymous address management unit 110 further determines whether there is an anonymous address whose expiration date has passed. If it is determined in step S504 that there is an anonymous address with an expired expiration date (YES), the process proceeds to step S505.

  In step S505, the anonymous address management unit 110 inquires of the log management unit 160, extracts the anonymous address recorded as “response not received” from the log registration table 162, and advances the process to step S506. On the other hand, if it is determined in step S503 that there is an anonymous address whose maximum expiration date has passed (YES), the process proceeds directly to step S506.

  In step S <b> 506, the anonymous address deletion unit 114 executes the deletion process of the anonymous address to be deleted, and deletes the assignment of the anonymous address to the network I / F 140. Here, when there is an anonymous address whose maximum expiration date has passed in step S503, the anonymous address is an anonymous address to be deleted. Further, if there is an anonymous address whose expiration date has passed in step S504, the anonymous address that has expired and is not recorded as “response not received” is to be deleted. It becomes. That is, since the anonymous address recorded as “response not received” is currently waiting for an MDN response, the execution of the deletion process is postponed within the allowable maximum expiration date.

  In step S507, the anonymous address deletion unit 114 further deletes the anonymous address whose assignment has been deleted from the anonymous address registration table 116, and advances the process to step S508. On the other hand, if it is determined in step S504 that there is no anonymous address with an expired expiration date (NO), the process proceeds directly to step S508.

  In step S508, it is determined whether or not a predetermined switching interval has elapsed since the generation of the anonymous address last time. If it is determined in step S508 that the switching interval time has not elapsed (NO), the process loops to step S503. On the other hand, if it is determined in step S508 that the switching interval has elapsed (YES), the process loops to step S501, and the anonymous address to be used is switched again by the anonymous address generation process.

  According to the anonymous address management process of the second embodiment described above, the deletion of an anonymous address that has not yet received the requested MDN response can be permitted even if the expiration date is exceeded. It will be postponed within the deadline. For this reason, even if the expiration date set for the anonymous address is shortened in consideration of the capacity of the nonvolatile memory 42, sufficient standby time is secured for the anonymous address required for waiting for the MDN response. It becomes possible. And it becomes possible to release the resource for the management of the anonymous address which does not need to wait for the MDN response at an early stage.

  Normally, there is an upper limit for the number of registrations in the log registration table 162. In the anonymous address management process of the second embodiment, however, the mail transmission log can be used even if the requested MDN response has not yet been received. Has an advantage that the old anonymous address is efficiently deleted at the stage when the is deleted.

  Furthermore, in the anonymous address management process of the second embodiment, the response reception result field 116e of the retransmitted previous transmission log is canceled as “response not received” and rewritten as “response undelivered”. Address deletion will not be postponed. The MDN response waiting for the retransmitted previous transmission is unnecessary because it is sufficient to receive the MDN response for the retransmission. That is, according to the anonymous address management process of the second embodiment, there is an advantage that old anonymous addresses that are no longer necessary due to retransmission are efficiently deleted.

  Hereinafter, the anonymous address management process of the third embodiment will be described with reference to FIGS. 3, 11, and 12. Note that the anonymous address management process of the third embodiment employs a configuration that deletes anonymous addresses in response to changes in the network environment. In the anonymous address management process of the third embodiment, the configuration of the router advertisement detection unit 150 shown in FIG. 3 is used. The operations of the anonymous address management unit 110, the mail transmission unit 120, the mail reception unit 130, the network I / F 140, the log management unit 160, and the job management unit 170 are the same as those of the first embodiment or the second embodiment. Since it is the same as the address management process, a detailed description is omitted.

  Referring to FIG. 3, the router advertisement detection unit 150 includes a prefix registration table 152. When the router advertisement detection unit 150 receives the router advertisement message, if a new prefix is included, the router advertisement detection unit 150 sets the time limit for the prefix and registers it in the prefix registration table 152. In addition, when the prefix included in the received router advertisement message has already been registered, the router advertisement detection unit 150 extends the time limit of the prefix. The router advertisement detection unit 150 further detects a prefix that has expired, and requests the anonymous address deletion unit 114 to delete the anonymous address including the prefix.

  FIG. 11 shows the data structure of the prefix registration table. The prefix registration table 152 shown in FIG. 11 includes a field 152a in which a prefix included in the router advertisement message is input, and a field 152b in which the time limit is input.

  The time limit of the prefix is not particularly limited, but can be a value obtained by adding a certain period to the date and time when the router advertisement message including the prefix is received. The expiration date of the prefix is updated as needed as long as the router advertisement continues to be received. However, if communication with the router is interrupted, such as when a router breaks down, the Internet FAX machine 20 is connected to another link, or is turned on after a long disconnection, the prefix Will expire.

  FIG. 12 is a flowchart illustrating a process executed by the router advertisement detection unit 150 in the anonymous address management process of the third embodiment. In the anonymous address management process of the third embodiment, the router advertisement detection unit 150 assists the function of the anonymous address management unit 110, and the anonymous address management unit 110 is separate from the router advertisement detection unit 150. It is assumed that processing as shown in FIG. 5 or FIG. 10 is being executed.

  The process shown in FIG. 12 is started from step S600 in response to the activation of the Internet FAX apparatus 20, for example. In step S601, the router advertisement detection unit 150 refers to the prefix registration table 152 and determines whether there is a prefix that has expired. In step S601, if there is a prefix that has expired (YES), the process proceeds to step S602.

  In step S602, the router advertisement detection unit 150 notifies the anonymous address management unit 110 of the prefix whose term has expired, and requests deletion processing of the anonymous address including this prefix. In step S603, the router advertisement detection unit 150 deletes the prefix that has expired from the prefix registration table 152, and the process proceeds to step S604. On the other hand, if there is no expired prefix in step S601 (NO), the process proceeds directly to step S604.

  In step S604, the router advertisement detection unit 150 determines whether a router advertisement message including a prefix has been received. If it is determined in step S604 that a router advertisement message including a prefix has not been received (NO), the process loops to step S601.

  If it is determined in step S604 that a router advertisement message including a prefix has been received (YES), the process proceeds to step S605. In step S605, the router advertisement detection unit 150 extracts a prefix included in the router advertisement message and registers or updates the prefix in the prefix registration table 152. At this time, if the prefix has already been registered, the router advertisement detection unit 150 extends the prefix and updates it. On the other hand, if the prefix is not registered, it is newly registered in the prefix registration table 152.

  According to the anonymous address management process of the third embodiment described above, when the router breaks down, the Internet FAX apparatus 20 is connected to another network, or the power is turned on after a long disconnection. For example, an anonymous address that cannot be used can be efficiently deleted in response to changes in the network environment.

  As described above, according to the present invention, in the communication using the anonymous address that is periodically changed and highly anonymous, the response addressed to the anonymous address is changed after the anonymous address to be used is switched. It is possible to provide a communication device, a communication method, and a program that can receive the response until the expiration date set for the anonymous address even if it is performed in the above.

  The above function can be realized by a device executable program described in a legacy programming language such as assembler, C, C ++, C #, Java (registered trademark), an object-oriented programming language, or the like. ROM, EEPROM, EPROM, It can be stored in a device-readable recording medium such as flash memory, flexible disk, CD-ROM, CD-RW, DVD, SD memory, MO, and distributed.

  Moreover, as a message which designates an anonymous address as a response destination, although the message which contains an anonymous address in a MDN response destination field has been demonstrated as an example, it is not specifically limited. Any message in which a response destination including an anonymous address is described in the transmission message can be adopted.

  In addition, as an example of a communication device, ITU-T recommendation T.30. Although the description has been made using an Internet FAX apparatus that executes FAX image communication conforming to 37, there is no particular limitation. In another embodiment, for example, an image reading apparatus (scanner) with a transmission function, an image forming apparatus (copying machine, multifunction peripheral, printer), an information processing apparatus (personal computer), and various apparatuses having a communication function are provided. It can also be configured as a communication device of the invention. In still another embodiment, it may be configured as a network interface card having the above functions.

  The specific embodiments of the present invention have been described above. However, the embodiments of the present invention are not limited to the above-described embodiments, and those skilled in the art will conceive other embodiments, additions, modifications, deletions, and the like. It can be changed within the range that can be performed, and any embodiment is included in the scope of the present invention as long as the operation and effect of the present invention are exhibited.

Schematic which shows the network environment of this embodiment. 1 is a diagram illustrating a schematic configuration of an Internet FAX apparatus according to an embodiment. 1 is a functional block diagram of an Internet FAX apparatus according to an embodiment. The figure which shows the data structure of an anonymous address registration table. The flowchart which shows the anonymous address management process of 1st Embodiment which an anonymous address management part performs. The flowchart which shows the mail transmission process which a mail transmission part performs in the anonymous address management process of 1st Embodiment. The figure which shows the data structure of (A) log registration table and (B) job registration table. The flowchart which shows the mail transmission process which a mail transmission part performs in the anonymous address management process of 2nd Embodiment. The flowchart which shows the mail reception process which a mail receiving part performs in the anonymous address management process of 2nd Embodiment. The flowchart which shows the anonymous address management process of 2nd Embodiment which an anonymous address management part performs. The figure which shows the data structure of a prefix registration table. The flowchart which shows the process which a router advertisement detection part performs in the anonymous address management process of 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Network environment, 12 ... LAN, 14 ... Internet, 16 ... LAN, 20 ... Internet FAX apparatus, 22 ... Router, 24 ... Router, 26 ... Internet FAX apparatus, 28 ... Laptop, 30 ... Control part, 32 ... Operation Panel, 34 ... Memory, 36 ... Network transmission control unit, 38 ... Scanner, 40 ... Plotter, 42 ... Non-volatile memory, 44 ... Data compression / decompression unit (DCR), 46 ... Facsimile communication control unit (CCU), 48 ... Bus , 100 ... functional block, 110 ... anonymous address management part, 112 ... anonymous address generation part, 114 ... anonymous address deletion part, 116 ... anonymous address registration table, 120 ... mail transmission part, 130 ... mail reception part, 140 ... network I / F, 150 ... router advertisement detection unit, 152 ... prefix registration Buru, 160 ... log management unit, 162 ... log registration table 170 ... job management section, 172 ... job registration table

Claims (10)

Storage means for storing an address registration table in which one or more anonymous addresses having anonymity are registered together with an expiration date;
Generating means for generating an anonymous address, assigning the anonymous address to a network interface, and setting the expiration date and adding it to the address registration table;
A transmission unit that switches in response to the generation and transmits a transmission message that specifies a response destination including the latest anonymous address to the destination via the network;
Means for extending the expiration date of the designated anonymous address in response to transmission of the transmission message;
Deleting means for deleting the anonymous address whose expiration date has expired from the assignment of the network interface;
Receiving means for waiting for reception of a response message addressed to an anonymous address registered in the address registration table in a session different from the transmission message until the anonymous address is deleted from the assignment of the network interface; Including a communication device.   The communication apparatus according to claim 1, wherein the transmission unit extends the expiration date of the designated anonymous address within a maximum allowable expiration date in response to transmission of the transmission message. The communication device according to claim 2 , wherein the deletion unit deletes the anonymous address from the closest anonymous address when the registration number in the address registration table reaches a maximum number that can be registered. The transmission means registers a transmission log in a log registration table in response to transmission of the transmission message, and the reception means receives the response message addressed to the anonymous address, and corresponds to the log registration table. 4. The communication device according to claim 2 , wherein response reception is recorded in a transmission log to be transmitted, and the deletion unit postpones deletion of the anonymous address that has not been received in response within the range of the maximum validity period. 5.   The communication device according to claim 4, wherein the transmission unit cancels the response non-reception of the transmission log of the log registration table when the retransmission corresponding to the transmission log of the log registration table is executed.   The communication apparatus further includes router advertisement detection means for acquiring a router advertisement message and registering a network prefix included in the router advertisement message in a prefix registration table together with a time limit, and the deletion means has the time limit expired. The communication apparatus according to claim 1, wherein the anonymous address including the network prefix is deleted. A communication method executed by a communication device, the communication device comprising:
Generating an anonymous address having anonymity, assigning the anonymous address to a network interface, and setting and adding an expiration date to an address registration table in which one or more anonymous addresses are registered together with the expiration date; and ,
Switching in response to generation and sending a send message specifying a response destination including the latest anonymous address to the destination over the network;
Corresponding to the transmission of the transmission message, setting an extended expiration date of the specified anonymous address in the address registration table;
Waiting for reception of a response message addressed to the anonymous address registered in the address registration table in a session different from the transmission message while the anonymous address is assigned to the network interface;
Deleting the anonymous address whose expiration date has expired from the assignment of the network interface.   The communication according to claim 7, wherein the setting step is a step of extending the expiration date of the designated anonymous address within an allowable maximum expiration date in response to transmission of the transmission message. Method. In response to transmission of the transmission message, registering a transmission log in a log registration table;
Receiving the response message addressed to the anonymous address and recording the response reception in a corresponding transmission log of the log registration table;
The communication method according to claim 8, further comprising: postponing deletion of the anonymous address that has not been received in response within the range of the maximum validity period. A program for causing a computer to function as a communication device connected to a network via a network interface, the computer comprising:
Storage means for storing an address registration table in which one or more anonymous addresses having anonymity are registered together with an expiration date;
Generating means for generating an anonymous address, assigning the anonymous address to the network interface, and setting the expiration date and adding it to the address registration table;
A transmission unit that switches in response to generation and transmits a transmission message that specifies a response destination including the latest anonymous address to a destination via the network;
Means for extending the expiration date of the designated anonymous address in response to transmission of the transmission message;
Delete means for deleting the expired anonymous address from the assignment of the network interface, and a response message in a session different from the transmission message addressed to the anonymous address registered in the address registration table A program for causing reception to function as reception means for waiting until the anonymous address is deleted from the assignment of the network interface.

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