JP2001308931A - Gateway - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gateway that can limit the use of an off-ramp gateway function only to a specific user. SOLUTION: Sender identifier information notified in a prescribed form is collated with contents of a user limit information storage means at the reception of an electronic mail with communication data via a network from a transmitter and only when it is discriminated that the sender transmitter can use the off-ramp gateway function, the communication data received from the sender transmitter in a form of an electronic mail are transmitted to a destination unit specified by destination designation information included in the electronic mail in a prescribed form via a public network.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gateway device, and more particularly to a gateway device which is connected to a network such as the Internet and is connected to a public network. The present invention relates to a gateway device having at least an off-ramp gateway function for transmitting via a public network to a destination device specified by destination designation information included in an electronic mail in a predetermined format.

[0002]

2. Description of the Related Art In e-mail communication via a network such as the Internet, the use of which has been rapidly expanding in recent years, not only text data but also voice data and image data are encoded into text data. Inexpensive data communication using a network that can exchange data and is basically free of communication charges is possible.

[0003] On the other hand, communication via a public network, such as a telephone line or ISDN, on which a communication fee is basically charged to a calling side, for example, facsimile communication, is also performed in parallel with e-mail communication via the network. Widely used.

[0004] In the Internet, an off-ramp gateway function is one of the extended functions of a so-called Internet facsimile apparatus which transmits and receives data by exchanging electronic mails according to the SMTP protocol.

[0005] The off-ramp gateway function uses a free Internet for a portion that can communicate with the Internet, and provides a facsimile apparatus connected to a public network with a network provided with an off-ramp gateway function at the end of the Internet. This is a kind of relay function of transmitting G3 or G4 from a facsimile apparatus or a gateway apparatus having an off-ramp gateway function.

[0006]

In the case of a so-called on-ramp relay for transferring data received via a public network to a destination via the Internet, a device for performing a gateway process is charged a communication fee in the public network. However, in the off-ramp gateway process, a communication fee is charged because the gateway device is the calling side.

[0007] Therefore, it can be said that the off-ramp gateway function should be used only by a user whose gateway apparatus recognizes that a communication fee may be charged for the user.

However, a method of specifying a destination address for off-ramp gateway is described in RFC 2303 and R
Since it is defined by FC2304, once the existence of this off-ramp gateway becomes clear by knowing its domain name, etc., the off-ramp gateway function is used without permission by a malicious third party, and the communication cost of another person is There was a problem that would have to take over.

The present invention has been made in view of the above circumstances, and has as its object to provide a gateway device capable of restricting use of the off-ramp gateway function to only a specific user.

[0010]

A gateway device according to claim 1 is connected to a network such as the Internet and connected to a public network, and receives communication data received from a transmission source device via an electronic mail via the network. In a gateway device having at least an off-ramp gateway function for transmitting via the public network to a destination device specified by destination designation information included in the e-mail in a predetermined format, the use of the off-ramp gateway function is restricted. A user restriction information storage unit that presets and stores a transmission source to be transmitted, and a transmission that is notified from the transmission source device in a predetermined format when receiving communication data via the network from the transmission source device by e-mail. The source identification information is compared with the user restriction information storage means, and the transmission source device is turned off. The availability determining means for determining whether or not the ramp gateway function is available, and the transmitting apparatus only when the availability determining means determines that the off-ramp gateway function is available. And off-ramp gateway control means for transmitting communication data received by e-mail from the e-mail to a destination device specified by destination designation information included in the e-mail in a predetermined format via the public network. I do.

According to a second aspect of the present invention, in the gateway device according to the first aspect, the availability judging means checks the user restriction information storage means and the transmission source apparatus is an off-ramp gateway. The source identification information notified in a predetermined format from the source device for determining whether or not the function is available is a source mail address described in a predetermined format in a mail header portion of the email. There is a feature.

According to a third aspect of the present invention, in the gateway device according to the first aspect, the availability judging means checks the user restriction information storage means and the transmission source apparatus is an off-ramp gateway. The transmission source identification information notified in a predetermined format from the transmission source device for determining whether the function is available or not is a transmission source mail address notified at an electronic mail transmission protocol level. I do.

According to a fourth aspect of the present invention, in the gateway device according to the first aspect, the availability determining means checks the user restriction information storage means to determine whether the transmission source apparatus is an off-ramp gateway. The transmission source identification information notified in a predetermined format from the transmission source device for determining whether the function can be used is a transmission associated with packet data exchanged via the network when an electronic mail is received. It is the original network address.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described in detail.

First, a connection form of the network facsimile apparatus 1 as a gateway apparatus according to the embodiment of the present invention to the Internet 30 and the public network 40 will be described with reference to FIG.

In FIG. 1, a network facsimile apparatus 1 is connected to both the Internet 30 and a public network 40, and connects the Internet 30 to other network facsimile apparatuses 50a, 50b, etc. connected to the Internet 30. Data communication by electronic mail via the public network 40 such as PSTN and ISDN, and the facsimile devices 60a, 60b, and 6
Data communication is performed with 0c or the like. Note that an e-mail address and a fax number are assigned to each network facsimile machine or facsimile machine as shown in FIG.

FIG. 2 shows a network facsimile machine 1
The block configuration of FIG.

In FIG. 1, a network facsimile apparatus 1 includes a system control unit 2, a ROM 3, a RAM 4, a scanner 5, a plotter 6, an EEPROM 7, an image memory 8, an operation display unit 9, an encoding / decoding unit 10, a LAN communication control unit. 11, a modem 12, a network control unit 13, and a system bus 14.

The system control unit 2 is a microcomputer that controls each unit of the apparatus according to a control program written in the ROM 3 while using the RAM 4 as a work area.

As described above, the ROM 3 is a read-only memory in which a control program for the system control section 2 to control each section of the apparatus is stored. RAM4
Is a random access memory used as a work area of the system control unit 2 as described above.

The scanner 5 has 3.85 lines / mm, 7.7
This is for obtaining image information by reading a document image at a predetermined reading line density such as book / mm and 15.4 book / mm.

The plotter 6 records and outputs the received image information according to the line density, and records and outputs the image information read by the scanner 5 according to the line density (copy operation).
It is for doing.

The EEPROM 7 is an electrically rewritable read-only memory that can rewrite data in byte units but has a relatively small capacity. The EEPROM 7 holds various parameters necessary for the operation of the apparatus even when the apparatus is turned off. It is.

As shown in FIG. 3, in the EEPROM 7, off-ramp use restriction information is set and stored in advance in a storage area 7a. The details of the off-ramp use restriction information 7a will be described later.

The operation display unit 9 is provided with a numeric keypad, a start key, a one-touch dial key, and various other keys for designating a destination fax number and the like. It displays the operating state of the device to be notified and various messages.

The encoding / decoding unit 10 encodes the transmission image data via the public network by a predetermined encoding system such as an MH encoding system, an MR encoding system, and an MMR encoding system, which is compatible with G3 facsimile. On the other hand, image data received via the public network is subjected to MH coding, MR coding, and MM coding.
The decoding is performed by a predetermined decoding method corresponding to the R encoding method or the like. In addition, the encoding / decoding unit 10 outputs the MIM
Conversion of image data into a predetermined file format such as TIFF format exchanged by e-mail in E format, and
The inverse conversion process is also performed.

The LAN communication control unit 11 is connected to the LAN, controls the TCP / IP protocol on the LAN protocol, and controls the SMT on the TCP / IP protocol.
This is for enabling the system control unit 2 to transmit and receive e-mails using protocols such as P and POP. It should be noted that LA connected to the LAN communication control unit 11
N refers to the Internet 30 via a router or the like (not shown).
It is connected to the.

The modem 12 is a G3 facsimile modem that modulates data transmitted to the public network 40 via the network control unit 13 and demodulates a signal received from the public network 40 via the network control unit 13. is there. Also, the modem 12
Also transmits a DTMF signal corresponding to the destination number.

The network control unit 13 is connected to the public network, and detects the inversion of the line polarity, closes and releases the DC loop of the line, detects the line release, detects the dial tone, and outputs a tone signal such as a busy tone. It controls connection with a line such as detection and detection of a call signal, and transmits a selection signal corresponding to a destination number by a dial pulse signal corresponding to a 20PPS or 10PPS dial line. System bus 14
Is a signal line through which the above components exchange data.

The network facsimile apparatus 1 having the above configuration has an on-ramp / off-ramp gateway function. In the on-ramp, data received from the facsimile apparatus 60a or the like via the public network 40 to which the caller is charged is provided free of charge. Since the e-mail is sent to the network facsimile apparatus 50a or the like via the Internet 30, there is basically no need to apply restrictions except for restricting traffic.

On the other hand, in the off-ramp gateway,
Since the calling side in the public network 40 is the network facsimile apparatus 1 as a gateway apparatus,
Unconditionally responding to an off-ramp relay request from a transmission source device on the Internet 30 would cause an unreasonable communication fee to the network facsimile device 1 for a malicious third party who knew that the network facsimile device 1 was present. You will be charged.

Now, referring to FIG.
Consider a case where data is transmitted from the upper network facsimile device 50a to the facsimile device 60a on the public network 40. In this case, it is assumed that the network facsimile device 1 plays the role of the off-ramp gateway.

In this case, in the application that carries out the SMTP protocol in the network facsimile apparatus 50a, as shown in FIG. 4, the source mail address (FROM field) and the destination mail address (To field) are specified in the mail header. In order to analyze the transmission destination mail address “04622281234@xxx.yyy.co.jp”, an inquiry is made to a DNS server (not shown). The DNS server uses the domain name "xxx.yy
y.co.jp ”is the network facsimile machine 1 (IP of
Address), the application that carries out the SMTP protocol of the network facsimile device 50a tries to connect to the network facsimile device 1 on the lower TCP / IP protocol, and the destination is “04622281234@xxx.yyy. co.jp ".

In the network facsimile machine 1,
From the user name indicating the fax number of "0462281234",
Since the request is an off-ramp gateway request, it must be determined whether the request can be accepted and the off-ramp gateway process performed.

In the present embodiment, the network facsimile apparatus 1 determines whether or not the source apparatus of the e-mail can perform the off-ramp gateway processing as requested, and is determined to be good. Restricts users, responding only to off-ramp gateway requests from the source device.

Here, the first and second steps of the off-ramp gateway user restriction processing procedure in the facsimile machine 1 are described.
And each of the third example will be described. The difference between the procedures in each example is mainly due to the method of specifying the transmission source.

First, the off-ramp gateway user restriction processing procedure according to the first example will be described with reference to FIG.

As shown in FIG. 6, the network facsimile apparatus 1 has an SMTP and a mail format defined by RFC821 and RFC822 as shown in FIG.
By exchanging the phases F1 to F9 based on the protocol, a mail header described as shown in FIG. 4 is received (Process 101).

Then, the source mail address described in the FROM field in the text data of the received mail header is extracted (process 102). And
The extracted sender mail address is checked against the off-ramp use restriction information 7a (step 103), and the extracted sender mail address (in this case, “xyz@aaa.bbb.co.j
p ") is determined as to whether or not it is subject to use restriction (decision 104).

When it is determined that the mail is subject to the use restriction (Yes in the determination 104), no further mail reception based on the SMTP protocol is performed, and the phase F1 in FIG.
0, an SMTP response code "551" indicating that the specified destination user does not exist at this host.
To forcibly stop receiving mail.

If it is determined that the mail is not subject to the use restriction (No in decision 104), the mail reception based on the SMTP protocol is continued as it is, and the off-ramp gateway process is performed for the destination described in the To field. To

In the determination in the process 103, the sender's mail address “xyz@aaa.bbb.co.jp” is compared with the off-ramp use restriction information 7a. Register the source mail addresses that are permitted to be used as 7a, and use the off-ramp gateway when the source mail addresses “xyz@aaa.bbb.co.jp” are included in those addresses. Is the simplest way to determine that is allowed.

As another collation / judgment method, there is a method in which comparison is made from the end of the symbol string of the mail address. Since this is based on the Internet address system, for example, if a partial mail address “bbb.co.jp” is registered as the restriction information 7a, the sender mail address “xyz@aaa.bbb. "co.jp" can be determined as a sender whose use is permitted by collating from the rear end, and as the restriction information 7a, a partial mail address "ccc.bbb.co.j
If you register "p", the sender email address "xyz @ aa
"a.bbb.co.jp" can be easily determined to be a sender whose use is not permitted by collating from the rear end. Also, UNIX
(Registered trademark) is widely used for searching character strings.
It is also possible to apply a match judgment using a regular expression using a wildcard such as an asterisk, and to make the contents of the restriction information 7a intermittent rather than registering the sender e-mail addresses permitted to use individually. And the amount of information can be reduced.

Next, the off-ramp gateway user restriction processing procedure according to the second example will be described with reference to FIG.

The SMTP protocol has the concept of envelopes and contents used for ordinary mail. In the SMTP protocol, MAIL FROM: and RCPT TO:
Command is prepared. This MAIL FROM: contains the address of the sender. For this reason, the above Fro
The same effect as obtaining the source mail address by extracting the m: header field can be obtained by the MAIL FROM: command. Instead of extracting the FROM field from the text data of the mail header after reception, SMTP
The source mail address is obtained by the MAIL FROM: command at the protocol level, and by judging whether or not the sender uses the off-ramp gateway, the traffic required to check the sender can be reduced. In the case of the usage restriction, the SMTP protocol can be stopped at that point, so that unnecessary traffic can be suppressed.

That is, in FIG. 7, following the exchange of the phases F20, F21 and F22 based on the SMTP protocol in which the protocol and the mail format are defined by RFC821 and RFC822 as shown in FIG. ), Phase F23, and execute the MAIL FROM: command to send the e-mail address (in this case, "xyz @
aaa.bbb.co.jp ") (process 202).

Then, the obtained source mail address is collated with the off-ramp use restriction information 7a (Process 2).
03), the obtained sender email address (in this case,
It is determined whether or not “xyz@aaa.bbb.co.jp” is subject to use restriction (decision 204).

If it is determined that the command is subject to use restriction (Yes in decision 204), no further exchange of the SMTP protocol is performed, and there is a problem in the order of command execution as shown in phase F24 in FIG. SM indicating that there is
The SMTP protocol is forcibly stopped by returning the TP response code “503” or the like.

If it is determined that the electronic mail is not subject to the use restriction (No in determination 204), the SMTP protocol is continued as it is, the electronic mail is received, and the e-mail is transmitted to the destination described in the To field of the mail header of the received mail. Perform off-ramp gateway processing.

In the judgment in the process 203, the sender's mail address "xyz@aaa.bbb.co.jp" is compared with the off-ramp use restriction information 7a. The same collation / judgment method as in the example can be applied.

Next, an off-ramp gateway user restriction processing procedure according to the third example will be described with reference to FIG.

In the TCP / IP protocol, which is a lower protocol of the SMTP protocol, a port is assigned for each protocol. In the case of SMTP, the port number is 25. At this time, at the TCP / IP level, the connection request source, that is, the IP address of the source of the e-mail is added to the IP packet. Therefore, the source can be specified by the IP address. In that case, instead of the SMTP protocol level, TCP / I
At the stage of the P protocol, by judging whether or not the source has a restriction on the use of the off-ramp gateway, if the source is subject to the restriction on the use of the off-ramp gateway, the TCP / IP protocol can be stopped at that point. In addition, unnecessary traffic can be suppressed, and traffic of the SMTP protocol can be omitted.

That is, in FIG. 9, the phase F3 based on the TCP / IP protocol as shown in FIG.
IP packets 0 and F31 are exchanged with the transmission source to obtain the IP address of the transmission source added to the IP packet from the transmission source (process 301).

Then, the obtained transmission source IP address is compared with the off-ramp use restriction information 7a (Step 30).
2) It is determined whether or not the obtained transmission source IP address is subject to use restriction (determination 303).

If it is determined that the packet is subject to use restriction (Yes in determination 303), no further exchange of the TCP / IP protocol is performed, and an error response as shown in phase F32 in FIG. 8 is performed. To forcibly stop the TCP / IP file.

If it is determined that the received mail is not a usage restriction target (No in determination 303), the TCP / IP protocol is continued, the e-mail is received by the SMTP protocol, and the e-mail is received in the To field of the mail header of the received mail. An off-ramp gateway process is performed for the described destination.

In the determination in the process 302, the source IP address is checked against the off-ramp use restriction information 7a. In this case, the checking and determining method is the same as that of the mail address symbol string in the first or second example. The same collation / judgment method as in the case can be applied to the number / symbol string of the IP address.

As described above, according to the present embodiment, since the use of the off-ramp gateway can be restricted according to the transmission source, the off-ramp gateway can be used only for the legitimate transmission source. It is possible to prevent the transmission source from using the off-ramp gateway, thereby preventing an unreasonable communication fee from being charged.

In the embodiment described above, the present invention is applied to a network facsimile apparatus having an off-ramp gateway function, that is, a network facsimile apparatus including an off-ramp gateway apparatus as a component. However, the present invention is not limited thereto, and any other device having at least the off-ramp gateway function, such as a gateway device specialized for the off-ramp gateway function, can be similarly applied.

[0060]

According to the first aspect of the present invention, since the use of the off-ramp gateway can be restricted according to the transmission source, the off-ramp gateway can be used only for the legitimate transmission source. It is possible to prevent the use of off-ramp gateways for such sources and prevent improper communication charges from being charged,
The use of the off-ramp gateway function can be restricted to only a specific user, and an effect that it is possible to avoid improper communication costs can be obtained.

According to the second aspect of the present invention, in addition to the same effects as those of the first aspect, the transmission source is a transmission source mail address described in a predetermined format in a mail header portion of the electronic mail. For example, in the case of the SMTP protocol, there is an effect that it is possible to specify the source mail address described in the FROM field.

According to the third aspect of the present invention, in addition to the same effect as in the first aspect, the transmission source is not the transmission source mail address extracted from the text data of the mail header portion after reception, but the electronic mail. Source email address that is notified directly at the transmission protocol level, specifically, for example,
In the case of the SMTP protocol, there is an effect that the mail can be specified by the source mail address obtained by the MAIL FROM: command. Therefore, compared to the case of extracting from the text data of the mail header part after reception, the traffic required for sender confirmation can be reduced, and if the sender is subject to off-ramp gateway use restriction, Since the SMTP protocol can be stopped, there is an advantage that unnecessary traffic can be suppressed.

According to the fourth aspect of the invention, in addition to the same effects as those of the first aspect, the transmission source is a transmission source network address attached to the packet data exchanged at the time of receiving the e-mail. For example, in the case of exchanging e-mails according to the SMTP protocol over the TCP / IP protocol, an advantage is obtained in that the e-mail can be specified by the source IP address attached to the IP packet. For this reason, it is possible to determine whether or not the sender uses the off-ramp gateway at the level of the network protocol such as the TCP / IP protocol instead of the level of the e-mail protocol such as the SMTP protocol. In the case of the target, the network protocol such as the TCP / IP protocol can be stopped at that time, so that there is also an advantage that unnecessary traffic can be further suppressed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a connection mode of a network facsimile apparatus according to an embodiment of the present invention to the Internet and a public network.

FIG. 2 is a diagram showing a block configuration of a network facsimile apparatus according to the embodiment of the present invention.

FIG. 3 is a diagram showing stored contents of an EEPROM of the network facsimile apparatus according to the embodiment of the present invention.

FIG. 4 is a diagram illustrating an example of a mail header.

FIG. 5 is a flowchart showing a first example of an off-ramp gateway user restriction processing procedure in the network facsimile apparatus according to the embodiment of the present invention.

FIG. 6 is a diagram showing a transmission sequence of a mail header part and the like.

FIG. 7 is a flowchart illustrating a second example of an off-ramp gateway user restriction processing procedure in the network facsimile apparatus according to the embodiment of the present invention.

FIG. 8 is a diagram showing a transmission sequence of a source mail address and the like.

FIG. 9 is a flowchart showing a third example of an off-ramp gateway user restriction processing procedure in the network facsimile apparatus according to the embodiment of the present invention.

FIG. 10 is a diagram showing an IP packet transmission sequence and the like.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Network facsimile apparatus 2 System control part 3 ROM4 RAM 5 Scanner 6 Plotter 7 EEPROM 8 Image memory 9 Operation display part 10 Encoding / decoding part 11 LAN communication control part 12 Modem 13 Network control part 14 System bus 30 Internet 40 Public network 50a, 50b Network facsimile machine 60a, 60b, 60c Facsimile machine

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/32 F term (Reference) 5C062 AA02 AA13 AA29 AA30 AC58 AE14 AF00 AF01 BD00 5C075 AB90 BB07 CA90 CD07 FF90 5K030 GA11 GA16 HA06 HB04 HB08 HC01 HD03 HD09 JT05 KA04 LD14 LD20 5K101 KK01 LL01 LL03 LL05 MM04 MM05 NN06 NN25 NN34 SS06 SS07 TT06 UU03 UU08 UU16 UU19 9A001 CC02 JJ14 JJ25 KK56

Claims (4)

[Claims] 1. A communication system which is connected to a network such as the Internet and to a public network, and receives communication data received from a transmission source device via an electronic mail via the network in accordance with destination designation information included in the electronic mail in a predetermined format. In a gateway device having at least an off-ramp gateway function for transmitting to a specified destination device via the public network, user restriction information in which a transmission source to be restricted from using the off-ramp gateway function is set and stored in advance. Storage means;
When receiving the communication data from the transmission source device via the network by e-mail, the transmission source identification information notified from the transmission source device in a predetermined format is compared with the user restriction information storage unit, and the transmission is performed. Availability determination means for determining whether the source device is capable of using the off-ramp gateway function, and only when the availability determination means determines that the source device is capable of using the off-ramp gateway function, Off-ramp gateway control means for transmitting communication data received by e-mail from the transmission source device to a destination device specified by destination designation information included in the e-mail in a predetermined format via the public network. A gateway device characterized by the above-mentioned. 2. The transmission source device, wherein the availability determination unit checks the user restriction information storage unit to determine whether the transmission source device can use an off-ramp gateway function. 2. The gateway device according to claim 1, wherein the sender identification information notified in a predetermined format from the sender is a source mail address described in a predetermined format in a mail header part of the electronic mail. 3. The transmission source device for determining whether the transmission source device can use an off-ramp gateway function by comparing the availability determination unit with the user restriction information storage unit. 2. The gateway device according to claim 1, wherein the sender identification information notified in a predetermined format from the sender is a sender mail address notified at an electronic mail transmission protocol level. 4. The transmission source device for determining whether the transmission source device can use an off-ramp gateway function by comparing the use permission determination unit with the user restriction information storage unit. 2. The gateway device according to claim 1, wherein the sender identification information notified in a predetermined format from the sender is a sender network address attached to packet data exchanged via the network when an electronic mail is received. .