08-email and chat

8/6/2019 08-Email and Chat

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Advanced Network Services Topic 8 Email and Chat

Email and Chat

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GROUP NAME:-YASER PATEL

PATEL HANIF

PRAFUL

JESHAN


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Many faces of Messagingy DeliveringDatay texty binaryy graphicy digitized videoy audio

y Between human users / computer systemsy Messaging types

y Emaily Directemaily Web based Email

y Chaty IRCy Instant messagingy Web based chat

y Short Message Service (SMS)


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MHS (Message Handling Service)

Components

MTS

MTA

MTAMTA

UA

UA

UA


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MHS Layout

UA UA

P2 (MIME,MAPI)

Video, data, audio, etc.

P3(IMAP,POP3,

SMTP)

P3

MTA MTA MTA MTA

MTS

P1 P1 P1

(SMTP)


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MHS Componentsy User Agent (UA)

y Program, with which human users read, create and

managee-maily Reads and writes messages using a P3 protocol

y Encodes and decodes messages using a P2 protocol

y Mail Transport Agent (MTA)y Transfers messages between computers

y Store and forward (non-real-time)

y Uses a P1 protocol


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Practical implementation of MHS protocols

y P1 movement of messagesy SMTP Simple Mail Transfer Protocol

yP2 coding and decoding messagesy MIME Multipurpose Internet Mail Extension

y MAPI - Messaging Application Programming Interface

y P3 reading and sending messages

y SMTP to sendy POP (Post Office Protocol) toread

y IMAP (Internet Message Access Protocol) toread


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Email in a picture

SMTP

POP or

IMAP


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Web maily Mail where the UA is in a browser

y Where is the sending MTA?

y All therest is the samey UA- local MTA communication

y Not using SMTP, POP, IMAP

y Internal to the Web provider

y In the filesystem?y Proprietaryprotocols?


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Format of messagesy RFC 822: STANDARD FOR THE FORMAT OF

ARPA INTERNET TEXT MESSAGESy Published in 1982

y Defines a format for text messages that are sentusing emaily Contains headers like From, To, Subject, Datey Lines no longer than 1000 chary

Message body- plain US-ASCII text (7 bits!)y Message header lines - plain US-ASCII texty Limit on message length


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Email headery The mail data consists of a header and a message body,

separated bya blank line.

y the header includes colon terminated fields such as:y To:y From:

y Subject:

y Date:

y Received:

y added to by intermediary MTAs. It is a form of postmark

y Cc:

y My own header:


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SMTP commandsy $telnet students.ballarat.edu.au 25y HELO y MAIL From:

y RCPTTo:y Datay Subject:Test emaily Hello there y .y 250 Ok: queued as F28B08603y Quity 221 Bye


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POP and IMAP

y Both are standards forreceiving email from aremote machiney Read email from mail file created byMTA

y POP (Post Office Protocol)y You can get, list, and delete mail.y Email downloaded gets stored on the local machine

y IMAP (Internet Message Access Protocol)y Quicklydownload header information and then readonlythe messagesyou want toread.y Email can be stored online in different foldersy Offline mode available


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POP-3 Commands

y USER- specifyusername

y PASS - specifypassword

y STAT- get mailbox status

LIST- get a list of messages and sizes

y RETR- retrieve a message

y DELE - mark a message for deletion from the mailbox

y NOOP- send back positivereply

y RSET- reset. All deletion marks are unmarked

y QUIT- remove marked messages and close the (TCP)

connection


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S/MIME

(Secure/Multipurpose Internet Mail Extensions)

y Verysimilar to PGP

y Likelytoemerge as industrystandard for commercial

use (PGP for personal)y Message signature

y Messageencryption

y Based on RSA


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What does S/MIME give us?y Secrecy Onlyintended recipient can read the

message. (A thick envelope and trustworthycouriers.)

y

Authentication Recipient knows the message camefrom the apparent sender. (An ink signature thatyourecognize.)

y Integrity Recipient knows the message was notchanged en route. (Un-erasable ink in a letter.)


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sendmail Unix MTAy Backboneof Internet email

y Open Source full function MTA

y On Adios disky Standard Linux service

y service sendmail start

y sendmail server listens for connections

y sendmail client passes messages on


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sendmail and DNSy MTA uses DNS to check validityof sender, receiveretc

y Lab requiresyourown DNS server

y Download and extract DNS filesy Usenamed g u namedto start server


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sendmail securityy Open relay

y Allows anyclient to send email anywhere

y Great for spammers!y Bydefault disabled

y Remote access

y Listening to a real IP/port

y Bydefault onlylocalhost


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New Account - Outlook Express


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MicrosoftO

utlookEx

press


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Send and receive e-mail

To send an e-mail message: Press the New Mail button on the Outlook Express toolbar Type in thee-mail addresses of therecipient Typeyour subject matter Typeyour message and then click the Send button

Toretrieve mail that has been sent toyou: Click the Send/Recv button on the toolbar Outlook Express will contactyoure-mail server and downloadyour

e-mail messages

Toreplyto a message: Click the Replybutton Therecipient address and the subject matter are automaticallyfilled

in Whenyou have completed typingyourreply, click the Send button


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The Outlook Express

New Message dialog box


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Reply to an e

-mail message


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Adding contacts to the

Address Book You can use the Address Book to keep track of

all the people and organizations with which

you correspond electronically. You not onlycan store thee-mail addresses foryour contacts, but also all otherrelatedinformation.

Click the Addresses button on the toolbar toopen the Address Book, and then select NewContact from the New button on the toolbar.


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Adding contacts to the

Address Book


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Advantages of Outlook Express

and other email programsy There are several advantages of Outlook Express and other

email management software such asWindows MailVista,Windows Live Mail, Outlook, Thunderbird, Zimbraetc.

y Availability of email even without an internetconnection: Ifyou've been using web based emailaccounts such as Hotmail, Gmail or Yahoo! Mail,you knowthat an active internet connection is required to login toyouronline account and access messages. With Outlook

Express, the program will automaticallyconnect toyouraccount,download email and store them onyour computer.Since now the messages areonyour local machine theyareavailable toyou even without an internet connection.


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Advantages of Outlook Express

and other email programsy Save time by downloading email from various accounts: This point applies

to thosewho have multipleemail accounts. You don't need to waste time inchecking each email account separately. Multiple accounts can be set up inOutlook Expresswhich means email from all these accounts will bedownloaded together at one place - your computer. You can also use filters

and Outlook Express messagerules to segregateemail messages as theyarriveatyour system. Forexample, all incoming Gmail messages can be diverted toone folder while those from Hotmail to another. You can similarlyisolateemailsbased on sender, file size, whether theyhave attachments etc.

y Acopy of your emails in on your computer: Probablythe most importantadvantage of using Outlook Express and otheremail management software isthe abilityto store a copyof allyouremail onyour computer. Soeven ifyou

accidentlydelete an important message fromyour serveror if (God forbid)youraccount is hacked or is inaccessible,you knowyou can retrieve the messagesfromyour system. Also, to playit reallysafe,you can takeregular backups ofOutlook Express.


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What Is Chat?

y

Real tim

eco

mmunicatio

nover

the

Inter

net.

y Synchronousy Email is asynchronous

y Types of chaty PrivateChaty Public Chats

yApproachesof chaty Internet RelayChat (IRC)y Instant Messaging Softwarey Web-Based Chat


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Internet Relay Chat

y Based on UNIXTalk

y IRC uses a client-server network model: IRC serversare connected through the internet to form an IRCnetwork.

y Individual chat participants use IRC client softwareand connect to the servers in the network.

y IRC uses a simple text-based protocol


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Instant Messaging Softwarey Instant messaging software lets two users chat in real

timeover the Internet.

y

Usuallybetween people who know each othery Tools that letyou identifyyour friends and alertyou

whenyour friends areonline.

y Various protocols


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Instant Messaging Softwarey Instant messaging software programs:

y Proprietaryprotocols

y

ICQy AOL Instant Messenger

y Windows Messenger

y Yahoo! Messenger

y Multi protocol

y Pidgin (formerlyGAIM)

y Trillian


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Web-based ChatyWeb-based chat is even more convenient than

Windows-based chat programs. Users do not need

to install anyprogram. Theyreach a chat site, login and begin to chat.

y There are two forms of web-based chat rooms:html version and Java Applet version. The html

chat rooms are programmed in html (hypertextmark-up language) and the Java Applet charroomsare programmed in Java language.


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Web-Based Chat Sitesy Most Web-based chat sites prohibit spam

messages, the useof automated programs, profane

and vulgar language, and threats to individuals.y Most sites requireyou toregister beforeusing their

chat rooms.

yAlthough Web sites that provide chat rooms have

rules of appropriate conduct,you might encounterconversations taking place that areoffensive toyou.


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Voice Chaty Voice Chat is the chat using voice.y Onceyou connect to a voice char server,your can

talk toother people in the same chat room or listento their talking.

y The sound qualitydepends on several factors suchas: speed of the Internet connection, Internettraffic and numberof participants in the same chat

room.y Voice chat rooms mayhave a limit of numbers of

participants.


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THANK YOU

08-email and chat

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