SMTP(简单邮件传输协议).ppt

SMTP 简单邮件传输协议 SIMPLEMAILTRANSFERPROTOCOLRFC2812 Introdution standarde mailprotocolpartoftheTCP IPprotocoldefinesthemessageformatandthemessagetransferagent MTA TCPport25text basedprotocol Internetemailsystem UseragentMailserverSMTP Somemailagents MicrosoftOutlookFoxmailNetscapeMessengerEndoraMail pine elm MailServer CoreofemailsystemMailboxMessagequeue SMTP SMTPwasoriginallydesignedforonlyplaintext ASCIItext ProvidesreliabledeliveryofmessagesUsesTCPandmessageexchangebetweenclientandserverOtherfunctions E mailaddresslookupE mailaddressverification Scenario SMTPSession 220mail cs tcd ieESMTPPostfix 1 1 13 heloFooBarmailfrom 250Okrcptto 250Okdata354Enddatawith To Someone SFrom SomeOneElse SSubject FooBarHelloWorld 250Ok queuedasA04537DB3quit221Bye SMTPcommands HELOdomainnamestartupandgiveyourhostnameMAILMAILFROM mailfromthisaddressRECVTO sendittothisaddressVRFYaddressdoesthisaddressactuallyexist verify EXPNaddressexpandthisaddressDATAstartgivingyouthebodyofthemailmessageRSETresetstateanddropcurrentmailmessageNOOPdonothingDEBUG level setdebugginglevelHELPgivemesomehelppleaseQUITclosethisconnection TelnetSMTPserver telnetservername25Helo mailfrom rcptto data crlf crlf quit SMTP HTTP Request ReplyprotocolsbuiltonTCPorUDPDesignedtohandleafixedsetofmessagesPullportocolandpushprotocol ProtocolDataFormatProgramsSMTPRFC822andMIMEPine NSMail Eudora HTTPHTMLExplorer Netscape Opera MIME MultipurposeInternetMailExtensions ConsistsofthreepartsAdditionalRFC822HeadersMIME Version Content Type Content Transfer Encoding Contenttypes andsubtypes text plaintext richimage gifapplication postscriptMultipart mixed boundary MIMEEncoding MailsystemsassumeASCIIOnly64validcharactersA Z a z 0 9 Somedatatypesincludearbitrarybinarydata e g JPEG Base64encoding3bytesofdatamapto4ASCIICharactersA 0 B 1 Also7bitASCIIencodingHumanreadable EncodingofbinaryData base64encoding Treatevery3bytes 24bits as46 bitwords TheBase64Alphabet ValueEncodingValueEncodingValueEncodingValueEncoding0A17R34i51z1B18S35j5202C19T36k5313D20U37l5424E21V38m5535F22W39n5646G23X40o5757H24Y41p5868I25Z42q5979J26a43r60810K27b44s61911L28c45t62 12M29d46u63 13N30e47v14O31f48w15P32g49x16Q33h50y From SteveZdancewicMIME Version 1 0To stevez cis upenn eduSubject ExampleMailContent Type multipart mixed boundary 020307000708030506070607 Thisisamulti partmessageinMIMEformat 020307000708030506070607Content Type text plain charset us ascii format flowedContent Transfer Encoding 7bitThisisthebody 020307000708030506070607Content Type text plain name example txt Content Transfer Encoding 7bitContent Disposition inline filename example txt Hello 020307000708030506070607Content Type image jpeg name doc jpg Content Transfer Encoding base64Content Disposition inline filename doc jpg 9j 4AAQSkZJRgABAQEASABIAAD gAXQ3JlYXRlZCB3aXRoIFRoZSBHSU1Q 9sAQwAIBgYHBgUIBwcHCQkICgwUDQwLCwwZEhMPFB0aHx4dGhwcICQuJyAiLCMcHCg3KSwwMTQ0NB8nOT04 MailAccessProtocols Pop3 AsimplemailaccessprotocolRFC1939Port110ComputerwithmailboxesrunsPOPserverUserrunsPOPclientonlocalcomputerPOPclientcanaccessandretrievemessagesfrommailboxRequiresauthentication password POPCommands USER enteryouruserIDPASS enteryourpasswordQUIT quitthePOP3serverLIST listthemessagesandtheirsizeRETR