03 Services Hosted in Internet

7/26/2019 03 Services Hosted in Internet

1/27

Services hosted in Internet

Internet ApplicationsAINT001-3-1-IA


2/27

Internet Application

Internet Applications Slide 2 of 18

Topic & Structure of the lesson

Electronic Mail

Internet Relay Chat

Newsgroup


3/27



Learning utco!es

At the end of this lesson" #$ %ill e ale to'

Explain the basic concept of electronic Mail Describe how Internet email works

Discuss the use of SM!" !#!$ an% MIME

&n%erstan% the use of Newsgroup Describe the functions of Internet Relay Chat


4/27


Internet Applications Slide ( of 18

)e* Ter!s *ou !ust e ale to use

Source : webopedia.com

If you ha'e mastere% this topic" you shoul% be able to use the followingterms correctly in your assignments an% exams(

Internet Service

+-!ail

S,T

3

,I,+

I./

Ne%sgroup


5/27


Internet Applications Slide of 18

he Internet is host to a number of ser'ices which its usersuse to communicate with one another)

Most of these ser'ices %eal with information an% how it isaccesse%)

he *orl% *i%e *eb +***, is one such ser'ice)

he *** ser'ice of the Internet is the most popularamongst all" next to e-mail)

he reasons for its popularity is because of(. he *eb is relati'ely easy to use compare% to most of

the other ser'ices)

. he *eb is one of the first graphical interface to the

Internet)

Services hosted in the Internet


6/27



+lectronic +!ail

Electronic mail" or e-mail" is among the mostpre'alent ser'ice on the Internet)

Similar to how the *eb works" the e-mailprocess functions through a client ser'erprocess as well)

he primary protocols that han%les e-mail are(

S,T +Simple Mail ransfer !rotocol,3 +!ost #ffice !rotocol 'ersion $,

,I,+ +Multi-!urpose Internet Mail Extensions,


7/27



/n e-mail ser'er runs two separateprograms on its machine)

he first is calle% the SM! Ser'er" SM!han%les all outgoing mail)

he other program is calle% the !#!$Ser'er" !#!$han%les all incoming mail)

+lectronic +!ail S,T & 34


8/27



+lectronic +!ail+lectronic +!ail S,T & 34

SM!(he protocol use% for email on theInternet) It %efines a message format an% aproce%ure to route messages through the Internet

from source to %estination 'ia email ser'ers)!#!$(&se% by local e-mail clients) It is anapplication-layer Internet stan%ar% protocol" toretrie'e e-mail from a remote ser'er o'er a C!0I!connection) Nearly all subscribers to in%i'i%ualInternet ser'ice pro'i%er e-mail accounts accesstheir e-mail with client software that uses !#!$)


9/27



6o% Internet e!ail %or7s


10/27



he %iagram abo'e shows a typical se1uence ofe'ents that takes place when /lice composes amessage using her email account +calle% M&/ or mail user agent in the%iagram,) She types in the e-mail a%%ress of hercorrespon%ent) She hits the 2sen%2 button)

3, 4er M&/ formats the message in Internet e-mail format an% uses the S,Tto sen% themessage to the local mail transfer agent +M/,"in this case smtp)a)org" run by /lice5s InternetSer'ice !ro'i%er +IS!,)

6o% Internet e!ail %or7s +refer page 6,


11/27



7, he M/looks at the %estinationa%%ress pro'i%e% in the SM!protocol"

in this case [email protected].

$, smtp)a)org sen%s the message tomx)b)org using SM!" which %eli'ers it

to the mailbox of the user bob)

8, 9ob presses the 2get mail2 button in hisM&/" which picks up the messageusing the !#!$)



12/27



his se1uence of e'ents applies to the ma:ority of e-mailusers) 4owe'er" there are many alternati'e possibilitiesan% complications to the e-mail system(

/lice or 9ob may use a client connecte% to a corporate e-mail system" such as I9M5s ;otus Notes or Microsoft5sExchange) hese systems often ha'e their own internal e-mail format an% their clients typically communicate withthe e-mail ser'er using a 'en%or-specific" proprietaryprotocol)

If /lice an% 9ob work for the same company" the entiretransaction may happen completely within a singlecorporate e-mail system)



13/27



3 Attach!ent4

Due to the fact that 3 storesinformation in a text file" attachments may

not be anything other than text) his problem was sol'e% using a program

calle% uuencode)

$uencodecon'erts any file format into afile format that contains only textcharacters)


14/27


Internet Applications Slide 1( of 18

/n example of a uuenco%e generate%file(

. begin !?+9 #@ABR#6RF4@53!62F*6

3 Attach!ent4


15/27



/t the %estination" a re'erse programcalle% uudecode con'erts the enco%e%

message back into its original form) In this way" attachments of many %ifferent

types can be transferre% 'ia e-mail)

9ut we re1uire %ifferent programs to 'iewthose attachments)

3 Attach!ent4


16/27



,I,+ - ,a7ing things colorful

MIME +Multi-!urpose Internet Mail Extensions,is an extension to the tra%itional way the SM!base% ser'ers han%le information)

*here SM! an% !#!$ use% to only han%le/SCII text files" MIMEtells the client whichWplayerX it nee%s to use to 'iew the information)

In short" MIME is simply an a%%ition to SM! toallow greater flexibility in managing information)


17/27



ther services' Internet .ela* /hat I./4

I./is one of the most popular an% mostinteracti'e ser'ices on the Internet)

I./allows people all o'er the worl% participate

in real-time con'ersations) &sing an I./client +program, you can exchange

text messages interacti'ely with other people all

o'er the worl%) Some of the more popular chat clients are

mIRC" !irch" an% irc for *in%ows an% 4omeror Ircle for Mac5s)


18/27



*hat program you use %oes not really matter allof them connect to the same chat networks)*hen logge% into a chat session" you

2con'erse2 by typing messages that are instantlysent to other chat participants) I./%epen%s onhost ser'ers to cater to the millions of I./users

/n I./user is re1uire% to %ownloa% a client to

allow them to log onto these ser'ers) #nce connecte%" a user can :oin any channel

an% con'erse with others there)

ther services' Internet .ela* /hat I./4


19/27



Con'ersations in an IRC channel may bepublic or pri'ate" between one or morepeople)

9ecause the I! a%%ress of a user can bema%e known" information can be tra%e% inany form" much like e-mail attachments

he main %isa%'antage of IRC is thepresence of many %ifferent forms ofattacks)

ther services' Internet .ela* /hat


20/27



Common IRC attacks(. ro:an 4orses

Scripts0!rograms %isguise% as something useful

but compromises security. Running unknown scripts

Channels usually auto-offer scripts to ease IRCuse) May contain tro:ans

. *ebsite referrals *ebsites a%'ertise% on channels which may

utiliYe the 'ictimZs computer for other maliciouspurposes



21/27



I./!rotection(

.Check %ownloa%

.Do not accept anything from astranger

.Do not run unknown scripts.&p%ate 'irus %efinitions



22/27



I./maintains its reputation as the best place toshare information o'er a fast en'ironment)

Despite the many security risks" it is still a

premier information exchange location) he main ser'ers that pro'i%e the backbone of

IRC are(. www)efnet)net

. www)un%ernet)org

. www)funet)fi0[irc

. www)%al)net

. www)newnet)net



23/27



ther services'Ne%sgroups

Newsgroups was the 3stfew WattractionsXon the Internet)

he term newsgroup is originally %eri'e%from &seNet +&serZs Network,)

Newsgroups are a centraliYe% location for

sharing news articles an% hol%ingcon'ersations about them)


24/27


Internet Applications Slide 2( of 18


he architecture of newsgroups is similarto that of the e-mail)

News articles are store% on a centraliYe%ser'er with thousan%s of clients%ownloa%ing the article)

he ser'er woul% also store runningcon'ersations about a certain article whichusers are able to subscribe to)


25/27




*hen a news threa% is subscribe% to by auser" all information an% comments ma%eabout that article will be %ownloa%e% onto

the client)

#nce the news is %ownloa%e%" the userscan rea% it at their leisure)

Comments can then be ma%e onto thatthrea% an% poste% for all to see)


26/27



uic7 .evie% uestions

*hy the *** is more popular thanother Internet ser'ices

4ow %oes the *** work

;ist %own the $ primary protocol that

han%le email) Explain briefly what is the !#!$ ser'er


27/27


> /

uestion and Ans%er Session

03 Services Hosted in Internet

Documents

Transcript of 03 Services Hosted in Internet