JP2004213534A - Network communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a network communication device capable of appropriately preventing the dangerousness of password tapping caused by authentication of a plain text in the case of transmitting a mail by an SMTP (simple mail transprt protcol). <P>SOLUTION: In the case of performing an SMTP authentication based on RFC2554 which is an extended SMTP function at the time of transmitting a mail to an SMTP server, an SMTP client distinguishes an authentication system based on encryption and an authentication system based on the plain text out of a plurality of authentication systems allowed to be utilized for the present machine, and in the case of performing authentication by the authentication system based on the plain text when an SMTP server which is a connection party can use the authentication system based on encryption, outputs a message for performing authentication by the authentication system based on the plain text and a message for asking agreement of authentication using the authentication system of the plain text. Since the user can recognize authentication based on the plain text liable to be tapped and careless leakage of a password of the plain text to a network can be prevented to improve security. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a network communication device, and more particularly, to a network communication device that allows a user to appropriately recognize the danger of eavesdropping on a password due to unambiguous authentication when performing mail transmission based on SMTP.
[0002]
[Prior art]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 9-22396 [Patent Document 2]
SUMMARY OF THE INVENTION In recent years, with the development of computer communication networks such as the Internet, information communication devices such as computers have been used to call the nearest provider (connection company to the computer communication network). It can communicate with communication terminals not only in Japan but also all over the world.
[0003]
An e-mail system capable of transmitting and receiving e-mails using the Internet has been constructed. Conventionally, e-mail authentication is generally performed using an authentication method based on Simple Mail Transport Protocol (SMTP) authentication. Have been.
[0004]
This authentication method using SMTP is a recognition method using plain text, and is a mechanism for performing authentication by transmitting a password after receiving an e-mail in order to prevent unauthorized use of a mail server.
[0005]
However, in the authentication method using the SMTP, since the password is transmitted in plain words over the network, there is a risk that the password can be easily eavesdropped, but the user can use the password without recognizing that the password may be eavesdropped. There was a problem that there is.
[0006]
Conventionally, regarding the confidentiality of a password on a network, Patent Literature 1 proposes a “network cooperation method and a transmission source network and a cooperation device therefor”. According to this conventional technology, a source network transmits a certificate in which at least the latter of an identification number and a password of a caller in a destination network is encrypted, and a message to the destination network to a cooperative device. Then, the cooperating device that has received the password logs in the destination network by using the identification number extracted by decrypting the encrypted part of the certificate with the private key and the password, and then sends a message to this login destination. What to send.
[0007]
In this conventional technique, the identification number and the password are transmitted in plain text.
[0008]
In addition, the present applicant has previously proposed "a method and system for remote diagnosis, control, and information collection based on various communication modes for transmitting a message to a user" (see Patent Document 2). ).
[0009]
This prior art transmits a first electronic message by a first device, receives a first electronic message by a first computer, and the received first electronic message transmits information about a first end user. If it is determined whether the first electronic message includes the information about the first end user, the first communication information is transmitted from the first computer to the first end user.
[0010]
Also in this conventional technique, information about the end user is transmitted in plain text.
[0011]
[Problems to be solved by the invention]
However, in the prior art, in any case, since the identification number, the password and the information on the end user are transmitted in plain text, there is a risk that such information is still easily eavesdropped. The problem that the user uses these pieces of information without realizing that there is a risk of eavesdropping has not been solved.
[0012]
Therefore, according to the first aspect of the present invention, when mail is transmitted to an SMTP server by a protocol based on RFC2821 via a network, when SMTP authentication based on RFC2554, which is an extended SMTP function, is performed, a plurality of available machines can be used. When distinguishing between the authentication method using encryption and the authentication method using plain text from the authentication method, when the SMTP server to connect to is an SMTP server that cannot use the authentication method using encryption and performs authentication using the authentication method using plain text, On the other hand, by outputting a message requesting consent to perform the authentication using the plain text authentication method and to perform the authentication using the plain text authentication method, the SMTP client user is made aware that the authentication is to be performed using the plain text that is easily intercepted. In addition, it is easy to eavesdrop only with the permission of the user Performing authentication, it is an object of the passwords in inadvertently plaintext is prevented from flowing on the network, providing a network communication device which can improve safety.
[0013]
According to a second aspect of the present invention, when the SMTP server is an SMTP server that cannot use an authentication method based on encryption, mail is transmitted without performing SMTP authentication, and authentication is performed depending on the destination depending on the setting of the SMTP server. You may be able to send e-mails without authentication.In this case, by sending e-mails without performing authentication processing, e-mails can be sent, and the possibility of e-mails being sent without having to send passwords over the network using flat passwords is expanded. Accordingly, it is an object of the present invention to provide a network communication device capable of improving usability while improving security.
[0014]
According to a third aspect of the present invention, when the SMTP server is an SMTP server that cannot use an authentication method based on encryption, a mail is transmitted after performing authentication using POP before SMTP, so that a password obtained by dividing the password is transmitted to the network. It increases the probability of sending an email without sending it, and only requires the user to determine whether or not to send the password over the network, simplifying the user's trouble in setting up authentication when sending an email, and improving security. It is an object of the present invention to provide a network communication device capable of improving the usability while improving the network communication device.
[0015]
[Means for Solving the Problems]
The network communication apparatus according to the first aspect of the present invention is a network communication apparatus having an SMTP client function of sending an e-mail to an SMTP server by a protocol based on RFC2821 via a network, and performs SMTP authentication based on RFC2554 which is an extended SMTP function. When performing the authentication, the authentication method using encryption and the authentication method using plain text are distinguished from a plurality of authentication methods that can be used by the own device, and the connection destination SMTP server is an SMTP server that cannot use the authentication method using encryption. When performing authentication using the plaintext authentication method, the above object is achieved by outputting a message requesting that the user perform authentication using the plaintext authentication method and consent to perform authentication using the plaintext authentication method. ing.
[0016]
According to the above configuration, when performing SMTP authentication based on RFC2554, which is an extended SMTP function, when sending mail to an SMTP server using a protocol based on RFC2821 via a network, encryption is performed from a plurality of authentication schemes that can be used by itself. The authentication method based on encryption is distinguished from the authentication method based on plain text, and when the connection destination SMTP server is an SMTP server that cannot use the authentication method based on encryption and performs authentication using the authentication method based on plain text, the user is authenticated using plain text. Since a message requesting consent to perform authentication using the authentication method and performing authentication using the authentication method is output, it is possible to make the SMTP client user recognize that authentication is to be performed using the easy-to-intercept normal authentication, An equitable recognition that is prone to eavesdropping only with the permission of the user The go, inadvertently can passwords in plaintext is prevented from flowing on the network, it is possible to improve safety.
[0017]
In this case, for example, when the SMTP server is an SMTP server that cannot use an authentication method using encryption, the network communication device performs mail transmission without performing SMTP authentication. It may be something.
[0018]
According to the above configuration, when the SMTP server is an SMTP server that cannot use the authentication method by encryption, the mail is transmitted without performing the SMTP authentication. Therefore, depending on the settings of the SMTP server, the mail may be transmitted without the authentication depending on the destination. In some cases, you can send the email.In this case, you can send the email by trying to send the email without performing the authentication process. Thus, safety can be improved and usability can be improved.
[0019]
Further, for example, as described in claim 3, when the SMTP server is an SMTP server that cannot use an authentication method based on encryption, the network communication device performs mail transmission after performing authentication using POP before SMTP. It may be performed.
[0020]
According to the above configuration, when the SMTP server is an SMTP server that cannot use the authentication method using encryption, the mail is transmitted after performing authentication using the POP before SMTP, so that the password is not transmitted on the network by using a common password. In addition to increasing the probability of sending e-mails, it also simplifies the time and effort required for users to make authentication settings when sending e-mails, by only requiring the user to decide whether or not to pass the password over the network. Thus, safety can be improved, and usability can be further improved.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments described below are preferred embodiments of the present invention, and therefore, various technically preferred limitations are added. However, the scope of the present invention is not limited to the following description. The embodiments are not limited to these embodiments unless otherwise specified.
[0022]
FIGS. 1 and 2 are diagrams showing a first embodiment of a network communication device according to the present invention. FIG. 1 is a diagram to which the network communication device according to the first embodiment of the network communication device according to the present invention is applied. FIG. 2 is a diagram showing a message sequence in the network system 1.
[0023]
In FIG. 1, a network system 1 includes an SMTP server 2 and an SMTP client 3, and the SMTP server 2 and the SMTP client 3 are connected by a network such as the Internet.
[0024]
The SMTP client 3 is a network communication device including an interface for connecting to a network such as a personal computer, a display, and an operation unit for performing various input operations. The SMTP client 3 uses a protocol based on RFC2821 (SMTP: Simple Mail Transport Protocol). A mail is transmitted to the SMTP server 2 via the network.
[0025]
The SMTP client 3 is equipped with an extended SMTP function (SMTP Service Extension for Authentication), and can use itself when performing SMTP authentication (SMTP-AUTH) based on RFC2554, which is the extended SMTP function. The authentication method using encryption and the authentication method using plain text are distinguished from the plurality of authentication methods, and when the SMTP server 2 at the connection destination does not support the authentication method using encryption, authentication is performed using the authentication method using plain text. In this case, a message is displayed on the display requesting that the user perform authentication using a plain text authentication method and that he / she agree.
[0026]
The SMTP server 2 is an ordinary SMTP server, and sends and receives mails to and from a plurality of SMTP clients 3 via a network using a protocol based on RFC2821.
[0027]
Next, the operation of the present embodiment will be described. When sending an e-mail from the SMTP client 3, the network system 1 of the present embodiment first connects to the SMTP server 2 via the port 25 as shown in the message sequence in FIG. When connection permission / 220 is received from server 2, a HELO command is sent to start a session.
[0028]
The SMTP client 3 sends an AUTH command when there is a 250 response from the SMTP server 2, authenticates the SMTP client 3, and sends a MAIL command when there is a response from the SMTP server 2 that permits login of 235. Notify the sender of the email.
[0029]
The SMTP client 3 sends an RCPT command to notify the list of e-mail recipients when a response of 250 is received from the SMTP server 2, and transmits a text of the e-mail by a DATA command when a response of 250/251 is received. If you send a line with only a "." (Period) to it, it indicates the end of the text.
[0030]
Finally, the SMTP client 3 sends the QUIT command, and if there is a response of 221, the mail is actually transmitted. If there is a response of 221, the connection of the port 25 is disconnected.
[0031]
The SMTP server 2 that has received the mail stores the received mail in the user's spool as it is if the received mail is addressed to a user in its own spool. Transfer to system.
[0032]
Then, the SMTP client 3 performs an authentication control process in the message sequence as shown in FIG. That is, when transmitting the HELO command (step S101), the SMTP client 3 analyzes from the response of the SMTP server 2 whether the SMTP authentication is supported and what kind of authentication method can be used (step S102). 2 checks whether it supports SMTP authentication (step S103).
[0033]
When the SMTP server 2 does not support the SMTP authentication, the SMTP client 3 continues the SMTP protocol processing without performing the authentication (step S104), and when the SMTP server 2 supports the SMTP authentication, It is checked whether there is an authentication method that can be used by the client 3) (step S105).
[0034]
If there is no available authentication method, the SMTP client 3 continues the SMTP protocol processing without performing authentication (step S106). If there is an available authentication method, whether the authentication method using encryption can be used. Check (step S107).
[0035]
When the authentication method using encryption can be used, the SMTP client 3 performs authentication using the encrypted method, and continues the SMTP protocol processing as described above (step S108).
[0036]
When the authentication method using encryption cannot be used, the SMTP client 3 displays on the display a message asking the user to authenticate using the authentication method using plain text and consent to the user and notifies the user (step S109). Checks whether they have agreed to perform plain text authentication (step S110). At this time, the SMTP client 3 outputs a message such as "While there is a risk that the password may be eavesdropped on the network and still send it by e-mail" on the display as a message. Encourage and seek consent.
[0037]
The user of the SMTP client 3 recognizes from the message displayed on the display that the authentication method by encryption cannot be used and that the authentication may be eavesdropped, and then performs the authentication in plain text. The user instructs whether or not he / she agrees with the mouse or keyboard.
[0038]
If the user does not agree with the plaintext authentication, the SMTP client 3 notifies the user that mail cannot be sent, and ends the process without sending mail (step S111).
[0039]
If the user does not agree with the plaintext authentication, the SMTP client 3 may attempt to transmit the mail without stopping the mail transmission and without performing the authentication process. That is, depending on the settings of the SMTP server 2, mail transmission may be possible without authentication depending on the destination. In this case, mail transmission can be performed by attempting mail transmission without performing authentication processing.
[0040]
When the user agrees with the plaintext authentication, the SMTP client 3 performs the plaintext authentication, continues the SMTP protocol processing, and transmits the mail as described above (step S112).
[0041]
As described above, the SMTP client 3 of the network system 1 according to the present embodiment performs SMTP authentication based on RFC2554, which is an extended SMTP function, when performing mail transmission to the SMTP server 2 by a protocol based on RFC2821 via a network. An authentication method using encryption and an authentication method using plain text are distinguished from a plurality of authentication methods that can be used by the own device, and the SMTP server 2 at the connection destination is an SMTP server 2 that cannot use the authentication method using encryption and When the authentication is performed by the authentication method according to (1), a message requesting the user to perform the authentication using the plain text authentication method and consent to perform the authentication by the authentication method using the plain text is output.
[0042]
Therefore, the user of the SMTP client 3 can recognize that the authentication is to be performed in an equitable manner that is easy to be eavesdropped, and performs the authentication in the equitable environment that is easy to be eavesdropped only when the user has permission. It is possible to prevent the password from flowing on the network beforehand, and it is possible to improve security.
[0043]
Further, when the SMTP server 2 is an SMTP server 2 that cannot use the authentication method by encryption, the SMTP client 3 of the present embodiment transmits mail without performing SMTP authentication.
[0044]
Therefore, depending on the settings of the SMTP server 2, mail transmission may be possible without authentication depending on the destination. In this case, mail transmission can be performed by attempting mail transmission without performing authentication processing. It is possible to increase the possibility of sending an e-mail without sending a password over a network, to improve security, and to improve usability.
[0045]
FIG. 3 is a flowchart showing an authentication control process by an SMTP client which is a network communication device in a message sequence of a network system to which the second embodiment of the network communication device according to the present invention is applied.
[0046]
Note that the present embodiment is applied to a network system similar to the network system 1 of the first embodiment, and in the description of the present embodiment, the first embodiment The description will be made using the reference numerals used in the description of the embodiment as they are.
[0047]
In the network system 1 of the present embodiment, when the SMTP server 2 does not support an authentication method by encryption, mail transmission is performed after authentication using POP before SMTP.
[0048]
In the extended SMTP function, as a method for performing authentication, there is a method using POP before SMTP in addition to a method using an AUTH command (SMTP-AUTH method) as in the first embodiment.
[0049]
The POP before SMTP method is a method in which an e-mail cannot be transmitted without checking whether an e-mail addressed to the user has arrived, that is, an SMTP server 2 that is a POP (Post Office Protocol) server or an IMAP server before transmitting the e-mail. This is a method in which a login process is performed on the SMTP server 2 so that the SMTP server 2 can be used for a fixed time.
[0050]
Then, in the network system 1 of the present embodiment, the SMTP client 3 performs an authentication control process in a message sequence as shown in FIG.
[0051]
That is, when transmitting the HELO command (step S201), the SMTP client 3 analyzes from the response of the SMTP server 2 whether the SMTP authentication is supported and what kind of authentication method can be used (step S202). It is checked whether or not 2 supports the SMTP authentication (step S203).
[0052]
When the SMTP server 2 does not support the SMTP authentication, the SMTP client 3 continues the SMTP protocol processing without performing the authentication (step S204), and when the SMTP server 2 supports the SMTP authentication, the client (SMTP). It is checked whether there is an authentication method that can be used by the client 3) (step S205).
[0053]
If there is no available authentication method, the SMTP client 3 performs mail transmission after performing authentication using POP before SMTP (step S206).
[0054]
If there is an authentication method that can be used by itself, the SMTP client 3 checks whether an authentication method using encryption can be used (step S207). If an authentication method using encryption can be used, the SMTP client 3 performs authentication using the encryption method. Then, the SMTP protocol processing is continued as described above (step S208).
[0055]
When the authentication method using encryption cannot be used, the SMTP client 3 displays a message requesting the user to authenticate using the authentication method using plain text and consent to the user on the display and notifies the user (step S209). Checks whether they have agreed to perform plain text authentication (step S210). At this time, the user of the SMTP client 3 recognizes from the message displayed on the display that the authentication method by encryption cannot be used, and that the authentication may be eavesdropped, and then the plain text is used. The user instructs whether or not he / she agrees to perform authentication by using a mouse, a keyboard, or the like.
[0056]
If the user does not agree with the plain text authentication, the SMTP client 3 performs mail transmission after performing authentication using POP before SMTP (step S211).
[0057]
When the user agrees with the plaintext authentication, the SMTP client 3 performs the plaintext authentication, continues the SMTP protocol processing, and transmits the mail as described above (step S212).
[0058]
As described above, when the SMTP server 2 is the SMTP server 2 that cannot use the authentication method using encryption, the SMTP client 3 of the network system 1 according to the present embodiment transmits the mail after performing the authentication using the POP before SMTP. It is carried out.
[0059]
Therefore, it is possible to increase the probability of sending an e-mail without sending a password in the form of a password over the network. Can be simplified, the safety can be improved, and the usability can be further improved.
[0060]
As described above, the invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to the above, and can be variously modified without departing from the gist thereof. Needless to say.
[0061]
【The invention's effect】
According to the network communication apparatus of the first aspect, when mail is transmitted to an SMTP server by a protocol based on RFC2821 via a network, when an SMTP authentication based on RFC2554 which is an extended SMTP function is performed, the own apparatus is used. An authentication method using encryption and an authentication method using plain text are distinguished from a plurality of possible authentication methods, and the connection destination SMTP server is an SMTP server that cannot use the authentication method using encryption and performs authentication using an authentication method using plain text. In some cases, a message is output to the user requesting that the user authenticate using the plain text authentication method and consent to perform the authentication using the plain text authentication method. And with the permission of the user Only performing authentication on the eavesdropping is susceptible flat component, can be passwords in inadvertently plaintext is prevented from flowing on the network, it is possible to improve the safety.
[0062]
According to the network communication apparatus of the second aspect, when the SMTP server is an SMTP server that cannot use the authentication method by encryption, the mail is transmitted without performing the SMTP authentication. May be able to send e-mail without authentication depending on the destination.In this case, by sending e-mail without performing authentication processing, e-mail can be sent, It is possible to increase the possibility of mail transmission, improve security, and improve usability.
[0063]
According to the network communication apparatus of the third aspect, when the SMTP server is an SMTP server that cannot use the authentication method by encryption, mail transmission is performed after performing authentication using POP before SMTP. It is possible to increase the probability of sending an e-mail without sending the password over the network, and to ask the user only to determine whether or not to send the password over the network, The labor can be simplified, the safety can be improved, and the usability can be further improved.
[Brief description of the drawings]
FIG. 1 is a view showing a message sequence of a network system to which a first embodiment of a network communication device according to the present invention is applied;
FIG. 2 is a flowchart showing an authentication control process by the SMTP client of FIG. 1;
FIG. 3 is a flowchart illustrating an authentication control process performed by an SMTP client in a network system to which a second embodiment of the network communication device according to the present invention is applied;
[Explanation of symbols]
1 network system 2 SMTP server 3 SMTP client

Claims (3)

In a network communication device having an SMTP client function for sending an e-mail to an SMTP server by a protocol based on RFC2821 via a network, when performing SMTP authentication based on RFC2554 which is an extended SMTP function, a plurality of devices which can be used by the own device are used. When distinguishing between the authentication method using encryption and the authentication method using plain text from the authentication method, when the SMTP server to connect to is an SMTP server that cannot use the authentication method using encryption and performs authentication using the authentication method using plain text, A network communication device for outputting a message requesting that authentication be performed by an authentication method using plain text and consent to perform authentication using an authentication method using plain text. 2. The network communication device according to claim 1, wherein the network communication device performs mail transmission without performing SMTP authentication when the SMTP server is an SMTP server that cannot use an authentication method based on encryption. 2. The network communication apparatus according to claim 1, wherein when the SMTP server is an SMTP server that cannot use an authentication method based on encryption, the network communication apparatus performs mail transmission after performing authentication using POP before SMTP. .

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