Introduction to the
`Internet for Engineers
`
`RAYMOND GREENLAW
`Armstrong Atlantic State University
`
`ELLEN HEPP
`University of New Hampshire
`
`ORRADRE LIBRARY
`SANTA CLARA UNIVERSITY
`SANTA CLARA, CALIFORNIA
`
`awe
`filed VicGraw-Hill
`Boston Burr Ridge, IL Dubuque, [A Madison, WI New York San Francisco
`St. Louis Bangkok Bogota Caracas Lisbon London Madrid MexicoCity
`Milan New Delhi
`Seoul Singapore
`Sydney ‘Taipei
`“Toronto
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`Page 1 of 20
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`LG/HUAWEI EXHIBIT 1110
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`Page 1 of 20
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`LG/HUAWEI EXHIBIT 1110
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`

`

`
`
`Tt
`6109. 819
`EtS|
`a7
`1979
`
`sine
`
`WCB/McGraw-Hill
`A Division ofThe McGraw-Hill Companies
`
`INTRODUCTION TO THE INTERNET FOR ENGINEERS
`
`Copyright ©1999 by The McGraw-Hill Companies, Inc. All rights reserved. Printed in the
`United States of America, Except as permitted under the United States Copyright Act of 1976,
`no partof this publication may be reproducedordistributed in any form or by any means, or
`stored in a data base or retrieval system, withoutthe prior written permission ofthe publisher.
`
`This book is printed on acid-free paper.
`
`1234567890 DOC/DOC 9432109
`
`ISBN 0-07-229143-5
`
`Vice president/Editor-in-chief: Kevin T. Kane
`Publisher: Thomas Casson
`Executive editor: Eric M. Munson
`Marketing manager:
`John T: Wannemacher
`Project manager: Ayry Hill
`Senior production supervisor: Heather D. Burbridge
`Freelance design coordinator: Mary Christianson
`Coverimage: The lmage Bank
`Supplement coordinator: Matt Perry
`Compositor:
`Techsetters, Inc.
`‘Typeface:
`10/12 Janson
`Printer: R. R. Donnelley & Sons Company
`
`Library of Congress Cataloging-in-Publication Data
`Greenlaw, Raymond
`Introduction to the Internet for engineers/Raymond Greenlaw,
`Ellen Hepp.
`p.
`cm.
`Includesindex.
`ISBN 0-07-229143-5
`1. Internet (Computer network).
`retrieval system).
`I. Hepp, Ellen.
`TKS105,.875.157G744 1999
`004.67’8—de2 1
`
`2, World Wide Web(Information
`II. Title.
`
`hetp://www.mhhe.com
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`98-32297
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`
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`Page 2 of 20
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`Page 2 of 20
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`||
`TK
`5|09. 819
`oT
`| G44
`1474
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`||| |
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`{|
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`To Laurel and Celeste.
`
`To Mark, Andrew, Elisa, and Crissy.
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`Page 3 of 20
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`Page 3 of 20
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`JaoafFonsS—
`“9moOOm>
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`Preface
`
`Electronic Mail
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`Jump Start: Browsing and Publishing
`The Internet
`
`The World Wide Web
`
`Search Topics
`Telnet and FTP
`
`HTML
`
`Internet Service Providers
`
`Text Editing
`Pine Mail Program
`Basic UNIX
`
`HTML Tags
`My URLs
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`Glossary
`Bibliography
`Index
`
`XV
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`31
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`87
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`127
`161
`187
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`201
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`251
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`257
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`263
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`273
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`283
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`289
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`299
`ag
`319
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`vii
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`types
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`Messagecomposition.
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`(MIME)
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`Page 5 of 20
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`Basice-mailfacts.
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`Mailerfeatures,
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`E-mailaddresses,passwords,anduserids.
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`E-mailmanagement.
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`E-mailadvantagesanddisadvantages.
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`E-mailinnerworkings.
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`Messagecomponents,
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`MultipurposeIntemetMailExtensions
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`OBJECTIVES
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`thischapter:
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`1.1_Introduction
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`Electronicmail,ore-mailasitismostcommonlyreferredto,isthesubject
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`ofthischapter.Ourgoalsaretoacquaintnewuserswiththefundamental
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`beenworkingwithe-mailforafewyears,andtopointoutafewsubtletiesto
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`principlesofe-mail,toreinforcethesebasicsforintermediateuserswhohave
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`moreexperiencedusers.Thefollowingtopics,amongothers,arediscussedin
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` !Priorto1990.
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`ago,peoplecannowreceiveandsende-mailto:
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`onepredicted.Incontrasttothesimplicityofe-mailfunctionsashortwhile
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`messageviatheInternetgrowninwaysthatnotoanotheruser.E-mailhas
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`it.E-mailbeganasasysteminwhichanindividualusercouldsendaplain-text
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`eithertheycouldnotfunctionwithout
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`informationtotheintendedrecipient.
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`1.2_E-Mail:AdvantagesandDisadvantages.
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`mentationofthecorrespondence.Furthermore,fromtheuserpointofview,
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`hereinrelationtoatelephonecall;e-mailis.alotlessexpensivethanaphone
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`howtoselectanISP.)
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`using.
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`detailinAppendixC.)Thebasicconceptscarryoverdirectlytomostmailers.
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`sticktoagenericdescriptionofe-mail.(ThePinemailprogramiscoveredin
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`programs(synonymsincludemailers,mailclients,andmailapplications),wewill
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`Mailclientsareprogramsthatareusedtomanage,read,andcomposee-
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`motivationsforincludingthistopicatthebeginningofthistext.Youwillfind
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`CHAPTER1ElectronicMail
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`either,itstillfaroutdistancesavailability.e-mailintermsofitsworldwide
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`wherehasaccesstoe-mail.Althoughthetelephoneisnottrulyuniversal
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`1.2.2Disadvantages
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`Despitealloftheadvantages,weshouldbearinmindthatnoteveryoneevery-
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`heardofit,useditoccasionally,orfeltTodaymanypeopleallovertheworldhavebeenexposedtoe-mail—theyhave
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`Generality—E-mailisnotlimitedtotext;itallowsthetransferofgraphics,
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`programs,andevensounds.
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`Global—Everincreasingly,peopleandbusinessesallovertheworldare
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`usinge-mail.
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`systemswillnotifythesenderifane-mailmessagewasundeliverable.
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`Reliable—Althoughmessagesareoccasionallythisisrare.Manymaillost,
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`aone-pagetypicallydeliverydocument:bothdocumentswillhavethesame
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`inwhichcasetheusermighthavetofindanalternativewayofgettingthe
`time.Therearesomemailsystemsthatcannothandleverylargemessages,
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`resources.Youcankeepanelectroniccopyofamessageforyourown
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`correspondencedoesnotneedtobeprinted,usinge-mailsavesonnatural
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`records.
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`sendinga100-pagerequiresnomoreeffortorcostsendingdocumentthan
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`Printable—Ahardcopyiseasytoobtain.However,sinceagreatdealof
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`timescallednow),amessagecaneasilybeprintedtoprovideconcretedocu-
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`callandnearlyasfast.And,likepostalmail(snailmailors-mailasitissome-
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`Inexpensive—Onceyouareon-line,thecostofsendingamessageis
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`small.
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`network.
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`jobs,andthoseinacademia.Thewords“inexpensive”and“efficient”areused
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`Speed—E-mailisfast,basedonthespeedoftheunderlyingcommunication
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`theearlydaysoftheInternet,e-mailemergedasaninexpensiveandefficient
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`meansofcommunicationbetweenresearchers,scientists,peopleinhigh-tech
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`E-mailisoneofthemostpopularservicesavailablethroughtheInternet.In
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`canbeinformalorformal.E-mailmakespublishinganddiscussingvery
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`forstationeryandstamps.Sendingamemoorshortnoteiseasy.Amessage
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`easy,forexample,intheformsofmailinglistsandnewsgroups.
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`ServiceProviders(ISPs)providetheirownmailclients.(AppendixAdiscusses
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`Convenience—Therearenotripstothepostoffice,andnoneedtosearch
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`Thishasmadeusinge-mailmucheasierandmoreefficient.Afewpopular
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`
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`arenotassophisticatedassomestand-alonemailclients.ManyInternetMostWbbrowserscomewithabuilt-inmailapplication,althoughatpresentthese
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`mail,Theseprogramshavebecomeverysophisticatedinthelastfewyears.
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`mailclientsareElm,Eudora,mail-tool,mailx,MicrosoftExchange,andPine.
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`alimitednumberofpeoplewithwhomtheycouldcommunicate.Nowthat
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`
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`Asintheearlydaysofthetelephone,theoriginalusersofe-mailonlyhad
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`
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`e-mailismoreprevalent,someoftheadvantagesofusingitareclear.
`
`1.2.1Advantages‘
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`mailprogramsarecontinuouslybeingintroduced.Additionally,ifyouswitch
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`employerwilluseadifferente-mailsystemthantheoneyouarecurrently
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`companiesatsomepointinyourcareer,thereisagoodchanceyournew
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`Itisimportanttograspthefundamentalsofe-mail,sincenewandimprovede-
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`directlytoacomputerprogramprovesusefulsubscribingtoamailinginclude
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`list,submittingapaperorformelectronically,accessingandremoteInternet
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`Thislastpointisworthelaborating.Examplesinwhichsendingamessage
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`servicessuchasfiletransferandgopher.
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`*Computerprograms.
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`*Manyusersatonce.
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`usesofe-mailthroughoutthebook.Sincetherearesomanydifferente-mail
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`E-mailinfiltratesmanyareasoftheInternet,whichisoneoftheprimary
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`*Nearlyanycountryintheworld.
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`*Oneofmillionsofcomputerusers.
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`4.2E-Mail:AdvantagesandDisadvantages
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`Page 6 of 20
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`acceptablewhencomparedwithalternatives.
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`
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`maynothavereadtheirmail.
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`CHAPTER1ElectronicMail
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`
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`14.1Userids
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`
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`yourpassword.
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`hashadwithe-mail.
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`
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` 2Asanhistoricalnote,wepointoutthatSpamwasameatproductoriginallyfedtosoldiersin
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`theadvantagesofe-mailaregreat,andthedisadvantages,althoughreal,are
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`thanaletterandnotasintrusiveasaphonecall.Ane-mailresponsecanbe
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`mailtoeitherusingthetelephoneorwritingaletter.E-mailislessformal
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`associatedwithanycommunicationmechanism,manypeoplepreferusinge-
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`ponderedandformulated,ifnecessary,orsentbackrightaway.Onthewhole,
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`
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`ofpronounsthroughoutthebook,or(3)using“she”tocompensateforyearsofoveruseof
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`singular.Thisseemstobeabettersolutionthan:(1)usinghe/she,(2)alternatingthegender
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`Inthisbook,weusethepronouns“their,”“them,”and“they,”evenwherethecorrectusageis
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`skitinwhichJohnCleese(customer)asksEricIdle(waitress}whattheyhaveonthemenufor
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`Spam,”andsoontothepointeveryoneisfinallyreadytoscreamiftheyhearthattheword
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`breakfast.“She”thenratdesoffendlesscombinationsof“eggsandSpam,”“Spam,eggs,and
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`hasacult-likefollowing,Theuseofspamfore-mailwastakenfromthefamousMontyPython
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`WorldWarIL.Spamiscommerciallyavailableandcelebratedits50thbirthdayin1997.Spam
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`
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`Funk—Anothermorerecentnegativedevelopmentinvolves“junke-mail,”
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`messagethatyouwouldnotwantthewholeworldtosee.Itissimplefor
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`Misdirection—Withe-mail,youareyourownworstenemy.Itisfarmore
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`Thereareprogramsthatcanbeusedonsomesystemstocheckwhenaper-
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`Noresponse—Amildfrustrationsometimesassociatedwithusinge-mailis
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`Theprocessofsendingjunke-mailtolotsofsitessimultaneouslyisknown
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`problem.Someon-lineservicesprovidehelpindealingwiththisunwanted
`Forgery—E-maildoesnotprecludeforgeries,thatis,someoneimpersonat-
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`someonetopassonyourmessage,callede-mailforwarding,toanotherparty.
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`Interception—Itispossible,althoughunlikely,thateavesdroppersare“listen-
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`anegativereaction.They?maynothavereceivedyourmessage,orthey
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`Despitedisadvantages,areforthemostpartthesameasthosethewhich
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`notimmediatelyassumethatalackofaresponsefromsomeoneindicates
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`sonlastreceivedane-mailmessage.Althoughe-mailishighlyreliable,do
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`basis.However,thisoccursusingregularpostalmailaswell.dealingwithrecipientswhodonotreadandrespondtotheire-mailonaregular
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`e-mail,andthereareWebsitesthatsuggeststrategiesforcopingwithspam.
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`priatee-mailissometimesreferredtoasspamr’andisbecomingaserious
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`orunsolicitedcommerciale-mail.Thisfloodingofundesirableorinappro-
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`ingin”one-mailcorrespondence.Asaruleofthumb,neversendane-mail
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`likelythatyouwillaccidentallysende-mailtoanunintendedrecipientthan
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`Overload—E-mailcanalsobetooconvenientandresultinafloodofmail.
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`ingthesender,sincethesenderisusuallynotauthenticatedinanyway.
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`asspamming.Pleaseavoidthistypeofabuseofthee-mailsystem.
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`itisforsomeoneactuallytointerceptyoure-mail.
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`3.Describeonegoodandonebadexperiencethatyouorsomeoneyouknow
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`1.Writeaparagraphortwoaimedatsomeonewhowasaroundbeforethe
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`5.Haveyoueverreceivedspam?Ifso,whatwasthenatureofthemessage?
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`youmustknowtoaccessacomputersystemareyouruseridorloginnameand
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`tiontouserids,passwordselection,ande-mailaddresses.Thissectionshouldbe
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`mayalreadyhaveanInternetServiceProviderandusee-mail,orperhapsyou
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`Beforecontinuingwithoure-maildiscussion,itisworthdevotingonesec-
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`areastudentwhohasanaccountonacampuscomputer.Theimportantitems
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`concatenationoftheword
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`Synonymsforuseridareusernameandaccountname.Useridismerely“user”andtheabbreviation“id,”standingforiden-the
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`walters.Suchuseridsaremucheasiername,pblucas,whileNickMichaelWalters’name,torememberthansomethinglikePonetteBethLucas’useridmightbeherfirsttwoinitialsjoinedbyherlastuseridmightbehislast
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`youhaveachoice,pickasdescriptiveanameaspossible,butonethatisalso
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`easytotypeandassociatewithyou.Insomecases,thesegoalsaremutually
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`same.However,significantine-mailoneiseasiertoreadandmaybeshowsabitmorerespectforMaryLamb,mlamb,orlamb.Notethatuppercaseorlowercaseisnormallynotnames.Thatis,MaryLambandmary1ambaretreatedthe
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`
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`P13245.VeryfewpeoplewillbeabletoputanametogetherwithP13245.If
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`theaccountowner.IfyournameisSteveVillage,donotpickausernameof
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`Steve,sincethereareseveralmillionStevesintheworld,andsuchauserid
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`2.Writeaparagraphexplainingyourvisionofthefutureofe-mail.
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`1.3Userids,Passwords,andE-MailAddresses
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`EXERCISES12E-Mail:AdvantagesandDisadvantages
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`
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`Theparamountissueforyouistogetaccesstoacomputersystem.You
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`tification.Youruserididentifiesyoutothecomputer.
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`Inmostsettings,useridshavesomemnemonicmeaning.Forexample,
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`IfyournamewereMaryH.Lamb,loginnameswouldbemhamb,.*sensible
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`particularlyusefulfornewcomputerusers.
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`adventofcomputers.Describeyourideaaboute-mailforthefuture,including
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`1.3.Userids,Passwords,andE-MailAddresses
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`byitselfwouldnotuniquelyidentifyyou.
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`4.Whatisane-mailbomb?
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`exclusive,butkeeptheminmind.
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`howandwhyyouseeitbecomingpopularanduniversal.
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`is.
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`again.
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`masculinepronouns.
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`«Beatleastfivecharacterslong.
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` sound.Agoodpasswordshould:
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`exceptyoushouldbeabletologintoyouraccount.
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`»Containanumber.
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`«Possessuppercaseandlowercaseletters.
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`thenewpasswordasecondtimeforverification.Whenyoutypeapassword,
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`theonlyonewhoknowsthepasswordtoyourcomputeraccount,andnoone
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`donesimplytocheckthatyouarewhoyousayyouare.Intheory,youare
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`CHAPTER1ElectronicMail
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`1.3.2Passwords
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`selectingagoodonethefirsttimearound.
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`userid.Also,manyuserskeepthesameuseridforyears,soitisworthwhile
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`Whatwerecommendisthat,ifpossible,yougeta“vanityplate”foryour
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`platedependsonlyuponwhenyouarriveatthecounterandsignyourcheck.
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`obtainalicenseplateforyourcar,thesequenceofsymbolsyougetforyour
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`wouldalsowork.
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`1.3.3E-MailAddresses
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`Ped
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`tobemetasasecuritymeasure.Afterall,ifyourpasswordisawordinthe
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`inordertobeallowed.Thatis,thecomputersystemrequirestheseconditions
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`Sincedictionariesareeasilyaccessibleon-line,thisisnotashardasitmight
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`dictionary,aprogrammermightbeabletowriteaprogramthattriestobreak
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`intoyouraccountbysimplytestingeverywordinthedictionaryasapassword.
`Onmostcomputersystems,yourpasswordwillhavetomeetbasiccriteria
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`Thefirstimportantpointtobeawareofisthatthesuffixfollowingthe@sign
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`name.Inthiscase,MariaisacomputersciencemajorattheUniversityof
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`getsmoregeneralfromlefttoright.Thatis,csisasubdomainofcolorado,
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`coloradoisasubdomainofedu,andeduspecifiesa(generic)top-leveldomain
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`Colorado.Ifmariahadherowncomputercalledtennis,thee-mailaddress
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`cases,itmaybenecessarytoappendanumbertoyourname.Forexample,
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`SusanSmith14identifiesthefifteenthSusanSmithonasystem(assuming
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`SusanSmithorSusanSmith0identifiesthefirst).
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`Thetextbeforethe@(pronounced“at”)Therearesomeexceptions,butthisformatcoversmostcommonaddresses,theusernameofthesign*specifies
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`nameandlastnamecombinedwillprobablynotuniquelyidentifyyou.Insuch
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`Ifyouhaveacommonnameorarepartofalargeorganization,yourfirst
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`username@hostname.subdomain.domain
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`Thebasicformofane-mailaddressis
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`TheirbehaviorisakintothatofaDivisionofMotorVehicles.Whenyou
`handinguserstheirnextavailableletterornumbercombinationasauserid.
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`InternetServiceProviderssometimesperformtheunfortunatepracticeof
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`passwordifthesystemforcesfileonpasswords,sothatyoucannotquicklyreuseorswitchbacktoapreviousyoutochangepasswords.Avoidwritingdown
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`passwords,especiallyinon-linefiles.
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`1.3Userids,Passwords,andE-MailAddresses
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`itisnotechoedonscreen.Modernsystemsusuallykeepanindividualhistory
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`Yourpasswordisasecretcodethatauthenticatesyoutothecomputer.Thisis
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`«Containanonalphabeticalsymbolsuchas&,%,or!.
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`addresstoe-mailaddress.Mostaddresseshaveeitheroneortwodots.For
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`Thenumberofperiods(aperiodispronounced“dot”)variesfrome-mail
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`ments.Takeforexample:
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`maria@tennis.cs.colorado.edu
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`maria@cs.colorado.edu
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`typingintheoldpassword,typinginthenewpassword,andfinallytypingin
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`promised.Onmostsystems,changingpasswordinvolvesrunningaprogram,
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`themregularly.Anotheralternativeistosetagoodpasswordandstickwithit.
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`intoamultiusersystem,pickfairlyeasy-to-rememberpasswordsandchange
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`Youshouldchangeyourpasswordimmediatelyifyouthinkithasbeencom-
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` 4“The@wasselectedinJuly1972byRayTomlinsonatBolt,Beranek,andNewman,Inc.Ac-;
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`cordingtoWhereWizardsStayUpLate,HafnerandLyon,page192:“gottherefirst,soIgot
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`hadtheadvantageofmeaning“at”thedesignatedinstitution.Hehadnoideahewascreating
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`tochooseanypunctuationIwanted,”the@sign.”TheTomlinsonsaid.“Ichosecharacteralso
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`aniconforthewiredworld.
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`hardtoremember.Oneschoolofthoughtisifyouaregoingtobelogging
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`MuL()aif,andv*p*!CA.Thedrawbacktotheseexamplesisthattheyarealso
`Caseissignificantinpasswords.Hard-to-guesspasswordsare0G&$jaNp,
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`‘Thisaddresshasatop-leveldomainofcom.Thecomstandsfor“commercial.”
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`Thesubdomainentity,andmarkisacom-wheelabratorisacommercial
`puteruserwhoworksatWheelabrator.
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`mark@wheelabrator.com
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`example,considerthefollowinge-mailaddress:
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`focusonthesuffixfollowing@.
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`Considerafewsamplee-mailaddressesbeforewemakeanygeneralstate-
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`canlocatethatindividual'smailbox.Wehaveindividual,whilethetextafterthe@signindicateshowthecomputersystemSlreadycovereduserids,soletus
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`U.S.military
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`internationalentity
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`nonprofitorganization
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`networkingorganization
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`U.S.governmentagency
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`BI
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`DomainNameMeaning
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`education
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`commercialbusiness
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`Internetuse.
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`paulallen
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`1.3.4DomainNames
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`characters.
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`CHAPTER1ElectronicMail
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`1.3Userids,Passwords,andE-MailAddresses
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`za
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`us
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`uk
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`nl
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`ip
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`hk
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`fr
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`es
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`de
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`cl
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`ca
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`au
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`DomainName
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`SouthAfrica
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`UnitedStates
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`UnitedKingdom
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`TheNetherlands
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`Japan
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`HongKong
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`France
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`Spain(Espaiia)
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`Germany
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`Chile
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`Canada
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`Australia
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`youcancommunicateyoure-mailaddressandcanrecordsomeoneelse's.The
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`nomorethan63characterslong.Allfieldscombinedmusttotallessthan256
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`firstaddressexampleisreadas“mariaatcsdotcoloradodotedu,”andthe
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`schemethatfollowstheboundariesofcountriesandorganizations,ratherthan
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`total,includingallcountrycodes,thereareabout150top-leveldomainoftop-leveldomainnamesisanartifactoftheearlyyearsoftheInternet.Innames.
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`decisioninvolveseconomicsandpoliticsasmuchastechnology.Thenumber
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`namesintheUnitedStatesarecom,edu,gov,States,andtheyarelistedinTable1.1.ThebigsevenCurrentlyonlyasmallnumberoftop-leveldomainnamesexistintheUnitedgenerictop-leveldomainint,mil,net,andorg.In
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`States,thesearecalledcountrycodes,asamplingofwhichaddition,everycountryhasitsowntop-leveldomainname.IntheUnitedareshowninTable1.2.
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`meansthatadministratorsdonotfacetheimpossiblealocalauthority(anditsbackup)isresponsibleforlocalInternet:distributedassignmentandthoseofnetworks.TheDNSrepresentsakeyfeatureofthesuccessoftherecordkeepingofadatabase,sothatinformation.Thistaskoftryingtomaintain
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`namespace(DNS).Itisimportanttorealizethatthisisadistributednaming
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`domainnames.Inthefigure,weshowaverysmallfragmentofthedomain
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`oneenormouscentraldatabasethatwouldbeachokepointandwouldstrangle
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`Itiseasytotrackdownalistingofallcountrycodeson-line.
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`TABLE1.1TheGenericTop-LevelDomainNamesUsedintheUnitedStates.
`secondoneisreadas“markatwheelabratordotcom.”
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`Agivenfieldinane-mailaddress,thatis,apartseparatedbydots,canbe
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`Howaree-mailaddressesreadoutloud?Thisisimportanttoknowsothat
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`Thereareproposalstoexpandthenumberoftop-leveldomainnames.The
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`Figure1.1providesaconvenientwayofviewingorganizationofthethe
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`toleftinane-mailaddress.ForTraversingapathfromtheroottoaleafcorrespondstogoingfromrightexample,theuserkimwouldhaveane-mail *
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`TABLE12ASmallSamplingofCountryTop-LevelDomainNames.
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`FIGURE1.1ASmallFragmentofDomainNameSpace.
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`ImagineFigure1.1asaninvertedtree,withthetopcirclebeingtheroot.
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`Page 9 of 20
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`+Useaprogramspeciallydesignedforlocatingpeople.Thisusuallyworks
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`Sinceyouknowhiscompanyisnotanonprofit,youguesscominsteadof
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`locatesomeone,anumberofdifferentmethodsareavailablefordetermining
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`guessesaboutanyone’se-mailaddress.Forthosetimeswhenyoucannot
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`org.Similarprinciplesandaspeckleoflogiccanbeusedtomakeinformed
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`youneedtosendthesamemessage.Forexample,youmaywanttosenda
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`yourclubmembers’e-mailaddresses.Thentotoeveryoneinyourbowlingclub,simplyaddressingyoure-mailmessagetomembersofaclassoraspecialinterestgroup.Tosendamessageyoumightselectanaliasof1ubandlistall
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`clubwillresultineveryonereceivingacopyofthemessage.Obviously,this
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`Ane-mailaliasgroupofpeoplecanalsobeestablishedforaavholetowhom
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`someone'se-mailaddress.
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`wouldbe
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`denellio@hoopsters.com
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`owncompanycalledHoopsters.Aneducatedguessastohise-mailaddress
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`e-mailaddress.Forexample,pictureofFigure1.1inmind,itshouldbefairlyeasyforyoutoguesssupposeyouknowthatFrankDenelliohashisOnceyouknowthebasicprinciplesbehinde-mailaddressesandyouhavethesomeone's
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`selecttheaddressMOMandthemailerwouldyourmother’sinserte-mailaddress
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`(ormakeitavailableforyoutoinsert).Ifyouhavetotypeintheaddress,typing
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`MOM.Then,everytimeyouwanttosende-mailtoyourmother,youwould
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`MOMclearlyismuchfaster.Conceptually,
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`1.3.5E-MailAddressDeterminations
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`addressof
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`CHAPTER1ElectronicMail
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`kim@cs.colorado.edu
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`ane-mailaddress
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`LoisLane@aol.com
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`book”or“nicknamefeature”bythemailer.Forexample,ifyourmotherhas
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`1.3.Userids,Passwords,andE-MailAddresses
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`MOMgetsreplacedbyLoisLane@aol.com
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`andyoufrequentlye-mail,youmaywanttosetupanalias,sendhersuchas
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`+Askthepersondirectly.
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`bestforfindingnetworkorsitesupportstaff.
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`*Gothroughyourbrowser.Forexample,NetscapeNavigatorincludesa
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`“People”buttonthatprovidesaccesstoagroupofwhitepagedirectories.
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`Whitepagesarelikeon-linephonebooks.
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`aliases.Someoneelse’saliasofc1ubmightonlyaffectthee-mailthatyousend;suchaliasesincludethemembersoftheirsoftballadistributionlistorprivatedistributiontoaslist.Thealiaseswehavebeendiscussingisveryconvenient,becauseyoudonothavetolookupthee-mailaddressesofeveryonewhoisintheclub.Thistypeofaliasissometimesreferredareknownas/ocalorprivate
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`Inadditiontosettingupalocalalias,asystemwideorpublicaliascanalso
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`team.
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`beestablished.Thesearealiasesthatareusablebyeveryoneonanysystem
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`+Useaprogramsuchasfingertoverifyaguessedaddress.Butbeawarethat
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`*UseasearchenginetodeterminetheprimaryWbserverforthesiteororga-
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`+Useasearchengine,suchasYahoo!,andsubmitaqueryonthatperson’sname.
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`nizationwherethepersonislocated.Thenlookfordirectoryinformation
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`asasecuritymeasure,manysitesdisallowexternalfingering.
`onthesite’sWebpagesbyusingasearchoptionatthatsite.
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`andtheircorrespondentsagainstchange.Thethatcansende-mail.Theprimaryuseofapublicaliasistobuffertheownerpublicaliasshouldbeselected
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`administratormightdecidethatitwouldbehelpfultomakeiteasyorconvenientexample,systemtouseanalias,suchastolocatesomeone.Forthe
`andcomments.Eventhoughyoupersonallydonothavebi11designatedas
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`canbeexpectedtochangeover
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`tobeasstableaspossibleandtopointtime.Asecondaryuseofapublicaliasistotherealdeliveryaddress,which
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`analias,themailerwilldeterminethatamessagesenttobi11isapublicalias
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`bil),forhimself,sothatanyoneonthesystemcaneasilymailhimquestions
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`remembernamethatyoucreate.Themailclientassociatesthealiaswitha
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`addresscanbesetupwithinyourowne-mailsystem.Analiasisaneasy-to-
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`mailaddressistoocumbersome
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`Havingaddress,youmayfindthattoremember.Inthatcase,analiasforthedeterminedanindividual’se-mailthee-
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`aliases,buttheyaresimilarandaretypicallycalledsomethinglike“address
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`particulare-mailaddress.Eachmailerhasitsownprocedureforsettingup
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`1.3.6LocalandSystemwideAliases2
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`localaliasforyourcollegeroommateBillPatterson.Theclientwillcheckyour
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`aliasasoneofyourlocalaliases?Assumethatyouhaveestablishedbi]asa
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`listofnicknamesandmakeanappropriatesubstitutionifoneexists.Otherwise,7
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`andwheretodeliverleavingittootherpartsofthemailsystemtodiscoveriftheaddressisvalidthemessage.Since,inthiscase,bi11isdefinedlocally,
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`theclientwilltakethenameatfacevalueandsendthemessageonitsway,
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`andwilldirectyourmessagetothecorrectaddress.
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`Onequestionis,Whathappensifyouhavealreadydesignatedaparticular
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`useridgenerationfollowsthesesequentialrules:
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`(c)First,middle(ifthereisone),andlastinitial,or
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`(a)Lastname,or
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`(b)Firstinitial,lastname,or
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`s
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`startsat2.
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`(d)First,middle(ifthereisone),andlastinitial,followedbyacounterthat
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`9.Acomputeralgorithm(whichisreallyjustasetofspecificrules)forautomatic
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`Explain.
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`biggiesmall,StevenTyler,andEddieVedder?
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`7%.(Thisproblemrequiresdiscretemathematics.)Ifyouareallowedtohave
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`softwareautomaticallydistributesthemessagetoeachnameonthelist.
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`CHAPTER1ElectronicMail
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`nottothesystemadministrator.
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`andpatterson.
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`foryou.Thisway,ifsomeoneistakinganeducatedguessatyoure-mail
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`tionwithlowercaseletters?Now,supposeweallowdigits(0-9),aswellas
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`youre-mailtobi11willwindupbeingsenttobi11@bjology.ucla.eduand
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`Allen,JohnnyAllen,JosephAllen,JosephMikeAllen,MarkAllen,Marcus
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`1.4MessageComponents
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`operatorsusesuchalgorithms?
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`BillPattersonmightbeassignede-mailaliasesofbi11p,bil]patterson,bp,
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`address,chancesarethatitwillmatchoneofyoursystemaliases.Forexample,
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`10.Onyourcomputersystem,whatisthedefaultpasswordanewuserisas-
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`signed?Howlongdoyouhavebeforeitmustbechanged?Howfrequently
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`Sometimes,itisusefulforthesystemadministratortosetuppublicaliases
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`theautomaticuseridgeneratingalgorithm?Whydoyousupposecomputer
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`Allen,RobertJohnAllen,JillKendraAllen?Doyouseeanyproblemswith
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`receivedbyanindividual,whowouldthenforwardthemessage,themailing
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`notjustthoselistedinthetext.Aretheyalltwoletterslong?Howmany
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`addressestheire-mailtothenameofthelist.Insteadofthemessagebeing
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`usinge-mail.Puttogetheralistofal/top-levelcountrycodedomainnames,
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`allowsausertosendamessagetoawholegroupofpeople.‘Tosendmessagestoeachpersononthelist,thesender
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`theresultisaprivatedistributionlistthat
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`11.Thisexerciseshouldmakeyouawareofthenumberofcountriescurrently
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`Whenasystemadministratorestablishesaglobalaliasforalistofaddresses,
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`mustthepasswordbechanged?Arethereanyrulesyoumustfollowin
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`choosingapassword?
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`differentcountriescouldyoulocate?
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`6.Whatusernameswouldyousuggestforthefollowingrockstars:
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`UniversityofArizona.Whataretwoinformedguessesastowhathise-mail
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`addressmightbe?
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`ChristinaAmphlett,MickJagger,Jewel,NatalieMerchant,AlanisMorissette,
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`14.Testoutanyprogramsavailabletoyoufortrackingdownane-mailaddress.
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`EXERCISES13Userids,Passwords,andE-MailAddresses
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`13.AmechanicalengineeringprofessornamedBarryMarkMesserworksatthe
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`e-mailaddress.
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`Usethemtolocateanoldacquaintance.Reportyourfindings.
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`passwordsarethere?Whatifwealsoallowuppercaselettersincombina-
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`passwordsconsistingofonlyfivelowercaseletters,howmanypossible
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`1.4MessageComponents
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`8.Would“concertpromoter”beagoodpasswordforaconcertpromoter?
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`Letusbeginbylookingatasamplee-mailmessage.Ofcourse,inmost
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`e-mailclients,beforeyouseethemessage,youseealistofthemessages
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`systemsallowpasswordsofupto31characterslong.)
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`ane-mailmessage.Hopefully,afewitemswetouchonwillbenewtoyou.
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`uppercaseandlowercasedifferentpasswordsarepos-letters.Howmany
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`sibleoflengthsfive,six,andsevencharacters?(Factoid:Someoperating
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`handleonthebasics.Nevertheless,itisworthconsideringwhatcomprises
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`Youmayhavealreadybeenusinge-mailforawhileandhaveaprettygood
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`*Date.
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`showing
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`*Size(bytes).
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`*Sendername.
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`*Subjectline(usuallytruncated).
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`JohnAllen,EleanorAllen,KendraAllen,ShirleyAllen,JohnAllen,JohnK.
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`differentcomponents.Figure1.2depictsasamplee-mailmessage.
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`firstpeopleaddedtothesysteminsequence,whatuseridswouldtheyhave:
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`viewedthemessageSometimes,additionalsymbolsareusedtoflagwhetherornotyouhavealready(seeFigure1.4).Ourgoalhereistoexplainamessage’s
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`Notethatallaccountnamesarelowercase.Ifthefollowinguserswerethe
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`12.Listthreeadditionalmethods(notgiveninthetext)oftrackingdownauser's
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`usinga24-hourclock.
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`brieflytofamiliarizeyouwiththeterminology.
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`Whilemostpartsofthemessageareself-explanatory,wewillmentionthem
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`themessageinamailclientfolderandthenlookatthefilewithanordinary
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`displayyoucanseetheselinesifyousavethatinformation.Sometimesextra
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`informationispartofthee-mailmessage,butclientmaynotbesettothemail
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`mailclientwilldisplayslightlydifferentheaderinformation.Often,header
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`Greeting{
`HiGuys,
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`Header
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`To:shiller@aol.com
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`Subject:beandip
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`Ce:wong@sport.middlebury.edu
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`Text
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`haveto,Tak.
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`--Alex
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`Signature
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`AlexT.Diaz|office:(401)437-2134
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`332ToastLane|messages:(401)437-0012
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`EastProvidence,|fax:(401)437-2137
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`Thefirstfivelinesofthemessagearereferredtoasthee-mailheader.Each
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`Date:Wed,18Jun199711:00:46-0400(EDT)
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`FIGURE12ASampleMessage.E-Mail
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`14
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`14MessageComponents
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`haveto,Tak.
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`HiGuys,
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`Theopening
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`15In.
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`todowith“beandip.”
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`June18,1997,at11amEasternDaylightTime(EDT).Timeisrepresented
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`Diaz,whoseaddressisalex@eng.ephs.edu,sentthemessageonWednesday,
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`TheFromfieldindicateswhosentthemessageandwhen.InthiscaseAlex
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`night.Canoneofyoupickupanothercaseofitonyour,
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`wayhome?IthinkLukeisonhisbiketodaysoyoumight
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`Someoneaccidentallyfinishedofftheblackbeandiplast.
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`texteditororjustprintthemessageout.Theheaderwehaveshownisactually
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`mation,suchaspartsoftheroutethemessagetooktoreachyourcomputer
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`anabbreviatede-mailheader.Thefillbeaderincludessomeadditionalinfor-
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`andtheuniquemessageidassociatedwiththisparticularmessage.i
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`iscalledthegreetingofthemessage.Moreformalmessagesareaddressedlike
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`off-linelettersandusuallybeginwithDear.
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`Themaincontentiscalledthetextofthemessage.
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`elsewascopiedonthemessage.
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`whenyoudonotwantoneormoreoftherecipientstoknowthatsomeone
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`KEEEREEEREEEEEEEEEEEEEEEEEEEEEEEEEEKREEEKEEKEREREEEEEEEEEE
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`themessagewasalsodeliveredtothee-mailaddress
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`wong@sport.middlebury.edu
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`REEKEEEEREKEEAREKEEREEKEEEREREEEREEEEEEEEEEREREEEEREEETEEEEEEEEE
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`RhodeIsland02915|alex@eng.ephs.edu
`IftheBecfeaturewasused,wewouldnotseeitintheheading.Becisused
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`forblindcarboncopy.Additionalcopiesofthemessagemayhavebeensentout.
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`OnefieldthatdoesnotappearthatisworthmentioningisBec,whichstands
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`wayhome?IthinkLukeisonhisbiketodaysoyoumight
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`night.Canoneofyoupickupanothercaseofitonyour
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`Someoneaccidentallyfinishedofftheblackbeandiplast
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`onlyseeingtheSubjectfield,wecanassumethemessagewillhavesomething
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`TheSubjectfieldprovidesahintastowhatthemessageisabout.Here,after
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`recipientisshi]ler@aol.com.
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`TheCcfieldtellsusthatthemessagewascopied”“carbontoanotheruser.
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`TheTofieldspecifiestowhomthemessagewassent.Inthiscase,the
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`wewouldseeareferencetoPacificDaylightTime(PDT)ratherthanEDT.
`Ingeneral,theDatefieldwillincludeareferencetothetimezonethesender
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`From:AlexDiaz<alex@eng.ephs.edu>WedJun1811:00EDT1997
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`Sincee-mailissentthroughouttheworld,areferencebythemailertoGMT
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`(GMT).Greenwich,England,isthelocationwheretimeiskept.standard
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` CHAPTER1ElectronicMail
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`—0400.ThistellsusthatEDTisfourhoursbehindGreenwichMeanTime
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`TheDatefieldrepeatsthedateandincludesaninterestingfeature:the
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`letsusdeducewhentheusersentthemessageinrelationtoourlocaltime.themessagewassentat3pmGMT.Ifthemessagehadbeen
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`sentfromClaremont,California,Inthisexample,insteadofEastProvidence,RhodeIsland,
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`bottom,followedbythenamesofothermessage.Thoserecipientsoftheletter.Inourexample,usedtogeneratetheextracopy,hencefamiliarwithbusinessletterswilloftenseea“cc:”attheLongagowhenaduplicatemessageneededtobesent,paperwastheterm“carboncopy”foraduplicatecarbon
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`15
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`Page 12 of 20
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`Page 12 of 20
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`youarecomposingyoure-mailoutsidethemailer,usingasimpletexteditor.
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`signatureis.
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`1.5MessageComposition
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`Themannerinwhichyoucomposeane-mailmessagemayvaryfromonemail
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`21.Willyoure-mailprogramallow“random"signatures?Explainwhatarandom
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`encounteredinane-mailmessage.Compareandcontrastthem.
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`20.Printoutthemostinterestingandthe“ugliest"signaturesyouhaveever
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`18.DoesyourmailclientsupperttheBccfeature?
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`dardtoomitthegreetingandsignaturealtogether.
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`toyourself.
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`Section1.9.
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`EXERCISES14MessageComponents
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`theTofield?Isthealiasautomaticallyexpandedbythemailer?
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`CHAPTER1ElectronicMail
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`Thefinalpartofthemessageisknownasthesignature.
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`--Alex
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`17.Printoutane-mailmessageyoureceivedandlabelthedifferentparts.
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`19.IfyouCeyourselfonamessagetwice,doyougett