1、外文资料原文 SMTP Service Extension for Authentication RFC 2554 This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the Internet Official Protocol Standards (STD 1) for the
2、 standardization state and status of this protocol. Distribution of this memo is unlimited. There are usually two operating modes: SMTP to send and receive SMTP. Specific way: to send SMTP mail in the received user request to determine whether this e-mail local mail, if sent to the users mailbox dir
3、ect investment, or to check the remote mail server dns MX record, and the establishment of the remote received a two-way between the SMTP transmission channel, then by the sending SMTP command issued by the receiving SMTP to receive, and answer the counter-side delivery. Once the transmission channe
4、l is established, SMTP MAIL command specifying the sender sends the message sender. If the recipient can receive mail SMTP OK response is returned. SMTP RCPT command issued for the sender to confirm whether the message is received. If the SMTP recipient receives, it returns OK response； if you canno
5、t receive, then refused to accept response to issue (but does not suspend operation of the entire message), the two sides will repeat so many times. When the recipients receive all messages will receive a special sequence, if the recipient of the message successfully processed, it returns OK respons
6、e. SMTP commands define the mail transfer or by user-defined system functions. Its command is End of the string. In the case with parameters, the command itself is and the parameters separately, if not directly, and with parameters Connection. Mailbox syntax and receiving sites must be consistent wi
7、th the form. SMTP commands and responses are discussed below. Send e-mail operations involving different data objects, their mutual connection by different parameters. Reply Path parameter is the MAIL command, the forward path is the RCPT command parameter, the message date is the DATA command. Thes
8、e arguments or data objects must follow the command. This model also requires a different buffer to store the objects, that is, there is a path back buffer, a forward path buffer, the contents of a message buffer. The command generates its own specific buffer, or to one or more of the contents of th
9、e buffer is cleared. An important feature of SMTP is its ability to transmit messages in the Relay, Transfer Service provides inter-process communication (IPCE), and this environment may include a network, several networks or a network subnet. Understand that the transmission system (or IPCE) is not
10、 a one to one very important. Process and other processes may be directly through the communications of known IPCE. Mail is an application or inter-process communication. Mail can be connected in different IPCE the process of inter-network mail delivery. More specifically, mail can be a host of diff
11、erent network relay transmission. Known as the Simple Mail Transfer Protocol SMTP (Simple Mail Transfer Protocol), aim to provide efficient and reliable message transfer. An important feature of SMTP is its ability to transmit messages in the Relay, that the message can be different relay hosts on t
12、he network transmission. Work in two situations: First, e-mail transmission from the client to the server； second is from one server to another server. SMTP is a request / response protocol, it listen port 25, for receiving the users Mail request to establish with the remote Mail server SMTP connect
13、ion. Copyright Notice Copyright (C) the Internet Society (1999). All Rights Reserved. 1. Introduction This document defines an SMTP service extension ESMTP whereby an SMTP client may indicate an authentication mechanism to the server； perform an authentication protocol exchange, and optionally negot
14、iate security layer for subsequent protocol interactions. This extension is a profile of the Simple Authentication and Security Layer SASL. 2. Conventions Used in this Document In examples, C: and S: indicate lines sent by the client and server respectively. The key words MUST, MUST NOT, SHOULD, SHO
15、ULD NOT, and MAY in this document are to be interpreted as defined in Key words for use in RFCs to Indicate Requirement Levels KEYWORDS. 3. The Authentication service extension (1) The name of the SMTP service extension is Authentication (2) The EHLO keyword value associated with this extension is A
16、UTH (3) The AUTH EHLO keyword contains as a parameter a space separated list of the names of supported SASL mechanisms. (4) A new SMTP verb AUTH is defined (5) An optional parameter using the keyword AUTH is added to the MAIL FROM command, and extends the maximum line length of the MAIL FROM command
17、 by 500 characters. (6) This extension is appropriate for the submission protocol SUBMIT. 4. The AUTH command AUTH mechanism initial-response Arguments: A string identifies a SASL authentication mechanism. An optional base64-encoded response Restrictions: After an AUTH command has successfully compl
18、eted, no more AUTH commands may be issued in the same session. After a successful AUTH command completes, a server MUST reject any further AUTH commands with a 503 reply. The AUTH command is not permitted during a mail transaction. Discussion: The AUTH command indicates an authentication mechanism to the server. If the server supports the requested authentication mechanism, it performs an authentication
