邮件传输协议外文翻译文献.docx

1、邮件传输协议外文翻译文献邮件传输协议外文翻译文献(文档含中英文对照即英文原文和中文翻译)外文:SMTP Service Extension for AuthenticationThis 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 Prot

2、ocol Standards (STD 1) for the 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

3、sent to the users mailbox direct 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.

4、 Once the transmission channel 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 retu

5、rns OK response; if you cannot 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 pro

6、cessed, it returns OK response.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

7、 sites must be consistent with 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 da

8、te is the DATA command. These 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 o

9、r more of the contents of the 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 transmiss

10、ion system (or IPCE) is not 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,

11、 mail can be a host of different 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

12、different relay hosts on the 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 remot

13、e Mail server SMTP connection.Copyright NoticeCopyright (C) the Internet Society (1999). All Rights Reserved.1. IntroductionThis document defines an SMTP service extension ESMTP whereby an SMTP client may indicate an authentication mechanism to the server; perform an authentication protocol exchange

14、, and optionally negotiate security layer for subsequent protocol interactions. This extension is a profile of the Simple Authentication and Security Layer SASL.2. Conventions Used in this DocumentIn examples, C: and S: indicate lines sent by the client and server respectively. The key words MUST, M

15、UST NOT, SHOULD, SHOULD 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 th

16、is extension is AUTH(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 MAI

17、L FROM command by 500 characters.(6) This extension is appropriate for the submission protocol SUBMIT.4. The AUTH command AUTH mechanism initial-responseArguments:A string identifies a SASL authentication mechanism. An optional base64-encoded responseRestrictions:After an AUTH command has successful

18、ly completed, 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 mecha

19、nism to the server. If the server supports the requested authentication mechanism, it performs an authentication protocol exchange to authenticate and identify the user. Optionally, it also negotiates a security layer for subsequent protocol interactions. If the requested authentication mechanism is

20、 not supported, the server rejects the AUTH command with a 504 reply.The authentication protocol exchange consists of a series of server challenges and client answers that are specific to the authentication mechanism. A server challenge, otherwise known as a ready response, is a 334 reply with the t

21、ext part containing a BASE64 encoded string. The client answer consists of a line containing a BASE64 encoded string. If the client wishes to cancel an authentication exchange, it issues a line with a single *. If the server receives such an answer, it MUST reject the AUTH command by sending a 501 r

22、eply.The optional initial-response argument to the AUTH command is used to save a round trip when using authentication mechanisms that are defined to send no data in the initial challenge.When the initial-response argument is used with such a mechanism, the initial empty challenge is not sent to the

23、 client and the server uses the data in the initial-response argument as if it were sent in response to the empty challenge. Unlike a zero-length client answer to a 334 reply, a zero- length initial response is sent as a single equals sign (=). If the client uses an initial-response argument to the

24、AUTH command with a mechanism that sends data in the initial challenge, the server rejects the AUTH command with a 535 reply.If the server cannot BASE64 decode the argument, it rejects the AUTH command with a 501 reply. If the server rejects the authentication data, it SHOULD reject the AUTH command

25、 with a 535 reply unless a more specific error code, such as one listed in section 6, is appropriate. Should the client successfully complete the authentication exchange, the SMTP server issues a 235 reply.The service name specified by this protocols profile of SASL is SMTP.If a security layer is ne

26、gotiated through the SASL authentication exchange, it takes effect immediately following the CRLF that concludes the authentication exchange for the client, and the CRLF of the success reply for the server. Upon a security layers taking effect, the SMTP protocol is reset to the initial state (the st

27、ate in SMTP after a server issues a 220 service ready greeting). The server MUST discard any knowledge obtained from the client, such as the argument to the EHLO command, which was not obtained from the SASL negotiation itself. The client MUST discard any knowledge obtained from the server, such as

28、the list of SMTP service extensions, which was not obtained from the SASL negotiation itself (with the exception that a client MAY compare the list of advertised SASL mechanisms before and after authentication in order to detect an active down-negotiation attack). The client SHOULD send an EHLO comm

29、and as the first command after a successful SASL negotiation which results in the enabling of a security layer.The server is not required to support any particular authentication mechanism, nor are authentication mechanisms required to support any security layers. If an AUTH command fails, the clien

30、t may try another authentication mechanism by issuing another AUTH command.If an AUTH command fails, the server MUST behave the same as if the client had not issued the AUTH command.The BASE64 string may in general be arbitrarily long. Clients and servers MUST be able to support challenges and respo

31、nses that are as long as are generated by the authentication mechanisms they support, independent of any line length limitations the client or server may have in other parts of its protocol implementation.Examples:S: 220 ESMTP server readyC: EHLO S: 250-S: 250 -AUTH CRAM-MD5 DIGEST-MD5C: AUTH FOOBAR

32、S: 504 unrecognized authentication types.C: AUTH CRAM-MD5S: 235 Authentication successful.5. The AUTH parameter to the MAIL FROM commandAUTH=addr-specArguments:An addr-spec containing the identity which submitted the message to the delivery system, or the two character sequence , indicating such an identity is unknown or insufficiently authenticated.Discussion:The optional AUTH parameter to the MAIL FROM command allows cooperating agents in a trusted environment to c