Chapter 14 TCPIP Services and Applications

8/10/2019 Chapter 14 TCPIP Services and Applications

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TCP/IP Services and

Applications

Chapter 14


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Chapter 3 2

Chapter Objectives - I

Explain Simple Mail TransferProtocol

Explain Hyper Text Transfer Protocol

Explain and configure File Transfer Protocol Explain and configure Network News Transfer

Protocol

Explain and configure Simple Network Management

Protocol Explain Post Office Protocol


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Chapter 3 3

Chapter Objectives - II

Explain Internet Message Access

Protocol

Explain Electronic mail

Explain X.400 protocol

Explain BOOTP and DHCP

Explain and configure TELNET

Explain WWW


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Chapter 3 4

Simple Mail Transfer Protocol (SMTP)

Specifies how mail should be delivered from one

system to another

Standard protocol used for transferring email from

one computer to another Makes connection between senders server and

recipient and then transfer messages


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Chapter 3 5

SMTP Work Flow

A two-way transmission channel established between the senderSMTP and a receiver SMTP

Commands are generated by sender SMTP and sent to receiverSMTP


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Chapter 3 7

HTTP Work Flow

HTTP works on requestand response between

browser and server

Web server is designated

to handle HTTP requests

then sends requested

HTML page

Proxy servers is used with firewalls to monitor anddirect HTTP traffic through proxy to external

internet


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Chapter 3 8

Uniform Resource Locator (URL)

Text string that is used to locate a file or an object

on an internet

Syntax:


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Chapter 3 9

Used over Internet to exchange files

Uses Internet's TCP/IP protocols to enable data

transfer

Establishes two way connections betweencomputers

File Transfer Protocol (FTP)


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FTP Communication

Machine that are involved in an FTP transaction

Client (local host) machine and a server (remote

host)

Client machine initiates transfer Get command used to

copy files from server to

client

Put command is used to

copy files from client to server


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Chapter 3 11

Trivial File Transfer Protocol (TFTP) - I

Used to transfer files to and from a remote computer

Used by servers to boot diskless workstations, X-

terminals and routers

Start with a small amount of built-in software


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Chapter 3 12

Trivial File Transfer Protocol (TFTP)II

Connection and Communication between

Client/Server

Communication and messaging different in TFTP

when compared with FTP TFTP uses UDP

Process of transferring a file:

Initial Connection

Data Transfer Connection Termination


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Chapter 3 13

Network News Transfer Protocol (NNTP)

Used to transfer Usenet news from one machine to

another machine

Usenet news is a large collection of discussion

groups, covering a wide range of topics NNTP provides connection-oriented service

Communication takes place between a client and a

server that keeps netnews on both the places


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Chapter 3 14

Simple Network Management Protocol

(SNMP)

Framework for managing devices over Internet

using TCP/IP protocol suite

Provides set of fundamental operation for monitoring

and maintaining devices in the network

Agent is server process that maintains Management

Information Base (MIB) database for host


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SNMP Management Components

SNMP uses two protocols to manage tasks:

Structure of management Information (SMI)

Management Information Base (MIB)

Components of network management on theInternet:

SNMP

SMI

MIB


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Security

SNMP leads to vulnerability to a variety of security

threats

Threats

MasqueradingModification

of InformationDisclosure

Message

Sequence


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Chapter 3 17

Post Office Protocol (POP)

Used to retrieve email from remote server to localclient over TCP/IP connection

E-mail clients using POP3 connect, retrieve all

messages or store them on user's PC as new

messages or delete them from server and disconnect

POP3 is a TCP/IP client/server protocol

Session States:

Authorization State Transaction State

Update State


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Chapter 3 18

POP Session states


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Chapter 3 19

Internet Message Access Protocol (IMAP)

Enables the users to work with the mail on the

server

Does not download the mails

Used to access e-mails from a local server Working with mails

Accessing and deleting mails

Attachments


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Chapter 3 20

IMAP Advantages and Disadvantages

Advantages:

As the e-mail foldersare stored on theserver, the user is able

to read email from anycomputer whichbelongs to the network

To access more thanone account from

different locations,IMAP will be the mostefficiently

Disadvantages:

Complicated

Results in higher server

loads than POP3 Utilizes a lot of server

resources


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Chapter 3 21

Electronic Mail (E-mail)

Provides way to communicate and send letters over

the Internet

Mail

Delivery

System

Mail

User

Agent (MUA)

Mail

Submission

Agent (MSA)

Mail

Transfer

Agent (MTA)

Mail

Delivery

Agent (MDA)


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Chapter 3 22

E-mail Architecture

An E-mail system is divided into two sub-systems: User Agents (UA)

Message Transfer Agent (MTA)

E-mail architecture supports basic functions:

Composition

Transfer

Reporting

Displaying Disposition


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Chapter 3 23

User Agent (UA)

Allows user to send and read e-mail

Program that provide various methods such ascommand based, menu based or graphical tointeract with the e-mail

Sending Mail - User needs to provide message,destination address and other parameters whilesending an e-mail

Receiving Mail - The UA at the recipient end checks

the mailbox periodically for new e-mail


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Chapter 3 24

Message Transfer Agent (MTA)

Moves message from source to destination

Process that run in the background and transfersthe e-mail through system

Message Format

RFC 822Specifies syntax for text messages withinthe framework of electronic mail

Two componentsEnvelope and Content

MIMEMulti purpose Internet Mail Extension

Header fields defined in MIMEVersion, ContentType, Content-transfer-encoding, content ID anddescription


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Chapter 3 25

RFC 822 Message Formats

Header MeaningTo: Primary recipient e-mail address

Cc: Secondary recipient e-mail address

Bcc: Blind carbon copy e-mail address

From: User who created the message

Sender: Senders e-mail address

Received: Line added by each transfer agent along the route

Return-Path: Can be used to identify a path back to the sender

Date: The date and time of the message sent

Reply-To: Email address to which replies should be sent

Message-Id: Unique number for later reference

In-reply-To: Identification of the message to which this is a reply

References: Over relevant message-id

Keywords: Keywords chosen by user

Subject: Summary of the message


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Chapter 3 26

E-mail Privacy

Protection of e-mail from unauthorized access and

inspection

Connection to the Internet should be secured to

provide privacy between routers and otherconnections between them

Data encryption provides privacy by translating the

content into different format which is unreadable


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Chapter 3 27

BOOTP and DHCP - I

BOOTPFirst automated configuration tool for IPhosts

BootstrappingProvides the host with the

capability of getting IP addresses while machine

boots Requires two phases:

Client provided with address and other parameters

Client downloads softwares to function on network and

perform tasks


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Chapter 3 28

BOOTP and DHCPII

Dynamic Host Configuration Protocol (DHCP)Successor of BOOTP with different features

Dynamically assign addresses to clients and

centrally manage

Consists of two major components1. Addressallocation mechanism 2. Protocol that allows clients

and server to communicate

DHCP standard includes three different address

allocation mechanisms:

Manual , Automatic and Dynamic


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Chapter 3 29

Difference between BOOTP and DHCP

Bootstrap Protocol (BOOTP) Dynamic host configuration protocol (DHCP)

Fails if host moves from one physical network to another Provides with temporary IP address on request, hence works

efficiently when host moves from one physical network to

another

Cannot provide host with temporary IP address Provides host with temporary IP address

This type of IP address configuration is designed to

configure hosts, which are diskless workstation.

This type of configuration is used to configure IP addresses to

computers or host that are frequently relocating from

network to network

Supports finite or limited number of client IP address

configuration parameters

Supports large and extensible number of client IP address

configuration parameters as compared to BOOTP


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Chapter 3 30

TELNET

Network protocol used on internet or local area

network connections

Terminal emulation program for TCP/IP networks

Enables to control server and communicate withother servers on network


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Working of TELNET

Telnet clientSoftware that acts as interface touser, processing user commands and presentingoutput from remote machine

Telnet server - Program running on remote

computer that has been set up to allow remotesession

Telnet runs over connection-oriented TCP

TCP connection maintained for duration of Telnet

session Client and server send information at same time

over Telnet session because TCP is a full-duplex


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Chapter 3 32

World Wide Web (WWW) - I

WWW is a network of Internet servers, which

support documents that are developed using HTML

Hyper Text Markup Language (HTML) is a language

in which these documents are formatted Client-side

Computer applicationWeb browser that runs on

users local computer and connects to server

Interpreter that interprets code in an HTML page Operations carried out on client-side


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World Wide Web (WWW)II

Server Side

Software programWeb server that runs on a remote

server

Manages and shares web based applications Operations include processing and storage of data

from client to server


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Hyper Text Markup Language (HTML)

Markup language used to create web pages with

hypertext and other information to be displayed on

web browser

A Web page consists of HTML tags which are alsocalled as standalone and container tags

Tag starts with an open angular bracket and word

and then closing angular brackets


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Chapter 3 35

Java

Programming language with number of features

Developed by Sun Microsystems

Applet

A program written in Java programming language

Features - Display document, send message to otherapplets, play music, display images and videos

Servlets

Program that runs in response to client connection toserver

Program which run on a web server and handles userrequests and generates response


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Chapter 3 36

Working on WWW

Structure of finding information over internet divided

into three stages:

Finding documents

Formulating queries Determining relevance


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Chapter 3 37

Summary - I

SMTP protocol specifies how mail should bedelivered from one host to another host

HTTP is a set of rules that is used for exchangingfiles on the World Wide Web

FTP protocol is used to exchange files from onehost to another over the network

NNTP protocol is used for transfer Usenet newsfrom one machine to another machine

SNMP is a framework that is used to managedevices that are connected to Internet using theTCP/IP protocol suite


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Chapter 3 38

Summary - II

POP3 is a protocol used to retrieve email from a

remote server to a local machine over a TCP/IP

connection

IMAP enables the users to work with the mailon the server and does not download the mail

E-mail is an abbreviation for Electronic mail, through

which the user can communicate and send letters

over the Internet


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Summary - III

X.400 Protocol is a standard for electronic mail to

exchange messages between people and software

application

BOOTP and DHCP are configuration protocols toolsused to give IP address to computers

TELNET is a standard internet protocol used to

access remote systems

WWW is a computer network consisting of acollection of internet sites that offer text, graphics

and sound

Chapter 14 TCPIP Services and Applications

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