TCP/IP Services and Applications Chapter 14 Release 16/7/2009

Chapter Objectives - I Explain Simple Mail Transfer Protocol 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 Release 16/7/2009

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 Release 16/7/2009

Simple Mail Transfer Protocol (SMTP) Specifies how mail should be delivered from one system to another Standard protocol used for transferring from one computer to another Makes connection between sender’s server and recipient and then transfer messages For sending mails SMTP server must supply name of the destination host as well as name of destination mailbox Release 16/7/2009

SMTP Work Flow A two-way transmission channel established between the sender SMTP and a receiver SMTP Commands are generated by sender SMTP and sent to receiver SMTP Release 16/7/2009

Hypertext Transfer Protocol (HTTP) Set of rules used to exchange files on World Wide Web Users can exchange text, graphic images, sound, video and other multimedia files Defines how messages are formatted and transmitted over the Internet Release 16/7/2009

HTTP Work Flow HTTP works on request and response between browser and server Web server is designated to handle HTTP requests then sends requested HTML page Data is carried in the Multipurpose Internet Mail Extensions (MIME) format between the request and response Release 16/7/2009

Uniform Resource Locator (URL) Text string that is used to locate a file or an object on an internet URL Syntax : E.g. “http” is the scheme and “ is the scheme specific partwww.microsoft.com Release 16/7/2009

Used over Internet to exchange files Uses Internet's TCP/IP protocols to enable data transfer Establishes two way connections between computers one for transferring data and other for sending control information File Transfer Protocol (FTP) and show configuration from CBT Release 16/7/2009

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 upload files from client to server The control connection is established when the user starts an FTP session If there are many files to be transmitted the data connection can be opened and closed multiple times Release 16/7/2009

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 Release 16/7/2009

Trivial File Transfer Protocol (TFTP) – II Connection and Communication between Client/Server  Communication and messaging different (send data byte by byte) in TFTP when compared with FTP  TFTP uses UDP (port no. 69)  Process of transferring a file: Initial Connection Data Transfer Connection Termination Multiple TFTP exchanges are possible simultaneously by a server using unique port number Release 16/7/2009

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 Release 16/7/2009

Show NNTP configuration Release 16/7/2009

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 Based upon client-server model Release 16/7/2009

SNMP Management Components SNMP uses two protocols to manage tasks:  Structure of management Information (SMI) – defines rules for naming an object and defining the type of object  Management Information Base (MIB) – defines the number of objects Components of network management on the Internet:  SNMP  SMI  MIB Release 16/7/2009

Security SNMP leads to vulnerability to a variety of security threats because of lack of any authentication capabilities Threats Masquerading Modification of Information Message Sequence Disclosure Release 16/7/2009

Show how to install and configure SNMP Release 16/7/2009

Post Office Protocol (POP) Used to retrieve from remote server to local client over TCP/IP connection 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 Release 16/7/2009

POP Session states Release 16/7/2009

Internet Message Access Protocol (IMAP) Enables the users to work with the mail on the server Does not download the mails Used to access s from a local server Working with mails  Accessing and deleting mails  Attachments Release 16/7/2009

IMAP Advantages and Disadvantages Advantages:  As the folders are stored on the server, the user is able to read from any computer which belongs to the network  To access more than one account from different locations, IMAP will be the most efficiently Disadvantages:  Complicated  Results in higher server loads than POP3  Utilizes a lot of server resources Release 16/7/2009

Electronic 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) Release 16/7/2009

Architecture An system is divided into two sub-systems:  User Agents (UA)  Message Transfer Agent (MTA) architecture supports basic functions:  Composition  Transfer  Reporting  Displaying  Disposition Release 16/7/2009

User Agent (UA) Allows user to send and read Program that provide various methods such as command based, menu based or graphical to interact with the Sending Mail - User needs to provide message, destination address and other parameters while sending an Receiving Mail - The UA at the recipient end checks the mailbox periodically for new Release 16/7/2009

Message Transfer Agent (MTA) Moves message from source to destination Process that run in the background and transfers the through system Message Format  RFC 822 – Specifies syntax for text messages within the framework of electronic mail  Two components – Envelope and Content MIME – Multi purpose Internet Mail Extension Header fields defined in MIME – Version, Content Type, Content-transfer-encoding, content ID and description Release 16/7/2009

RFC 822 Message Formats HeaderMeaning To:Primary recipient address Cc:Secondary recipient address Bcc:Blind carbon copy address From:User who created the message Sender:Senders 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: 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 Release 16/7/2009

Privacy Protection of from unauthorized access and inspection Connection to the Internet should be secured to provide privacy between routers and other connections between them Data encryption provides privacy by translating the content into different format which is unreadable Release 16/7/2009

BOOTP and DHCP - I BOOTP – First automated configuration tool for IP hosts  Bootstrapping – Provides 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 Release 16/7/2009

BOOTP and DHCP – II Dynamic Host Configuration Protocol (DHCP) – Successor of BOOTP with different features Dynamically assign addresses to clients and centrally manage Consists of two major components – 1. Address allocation mechanism 2. Protocol that allows clients and server to communicate DHCP standard includes three different address allocation mechanisms:  Manual, Automatic and Dynamic Release 16/7/2009

Difference between BOOTP and DHCP Bootstrap Protocol (BOOTP) Dynamic host configuration protocol (DHCP) Fails if host moves from one physical network to anotherProvides with temporary IP address on request, hence works efficiently when host moves from one physical network to another Cannot provide host with temporary IP addressProvides 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 Release 16/7/2009

TELNET Network protocol used on internet or local area network connections Terminal emulation program for TCP/IP networks Enables to control server and communicate with other servers on network Release 16/7/2009

Working of TELNET Telnet client – Software that acts as interface to user, processing user commands and presenting output from remote machine Telnet server - Program running on remote computer that has been set up to allow remote session 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 Release 16/7/2009

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 application – Web browser that runs on user’s local computer and connects to server  Interpreter that interprets code in an HTML page  Operations carried out on client-side Release 16/7/2009

World Wide Web (WWW) – II Server Side  Software program – Web server that runs on a remote server  Manages and shares web based applications  Operations include processing and storage of data from client to server Release 16/7/2009

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 also called as standalone and container tags Tag starts with an open angular bracket and word and then closing angular brackets Release 16/7/2009

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 other applets, play music, display images and videos Servlets  Program that runs in response to client connection to server  Program which run on a web server and handles user requests and generates response Release 16/7/2009

Working on WWW Structure of finding information over internet divided into three stages:  Finding documents  Formulating queries  Determining relevance Release 16/7/2009

Summary - I SMTP protocol specifies how mail should be delivered from one host to another host HTTP is a set of rules that is used for exchanging files on the World Wide Web FTP protocol is used to exchange files from one host to another over the network NNTP protocol is used for transfer Usenet news from one machine to another machine SNMP is a framework that is used to manage devices that are connected to Internet using the TCP/IP protocol suite Release 16/7/2009

Summary - II POP3 is a protocol used to retrieve from a remote server to a local machine over a TCP/IP connection IMAP enables the users to work with the mail on the server and does not download the mail is an abbreviation for Electronic mail, through which the user can communicate and send letters over the Internet Release 16/7/2009

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 tools used to give IP address to computers TELNET is a standard internet protocol used to access remote systems WWW is a computer network consisting of a collection of internet sites that offer text, graphics and sound Release 16/7/2009