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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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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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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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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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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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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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POP Session states
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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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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
Delivery
System
User
Agent (MUA)
Submission
Agent (MSA)
Transfer
Agent (MTA)
Delivery
Agent (MDA)
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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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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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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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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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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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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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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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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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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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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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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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Working on WWW
Structure of finding information over internet divided
into three stages:
Finding documents
Formulating queries Determining relevance
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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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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