Tcpip services and applications


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Tcpip services and applications

  1. 1. TCP/IP Services and Applications
  2. 2. 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 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
  3. 3. 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
  4. 4. 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
  5. 5. 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
  6. 6. Uniform Resource Locator (URL)• Text string that is used to locate a file or an object on an internet• URL Syntax <scheme>:<scheme-specific-part>• E.g. http:// “http” is the scheme and “” is the scheme specific part
  7. 7. File Transfer Protocol (FTP) andshow configuration from CBT• Used over Internet to exchange files• Uses Internets TCP/IP protocols to enable data transfer• Establishes two way connections between computers one for transferring data and other for sending control information
  8. 8. 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 serverThe control connection is established when the user starts an FTP sessionIf there are many files to be transmitted the data connection can be opened and closed multiple times
  9. 9. 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
  10. 10. 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
  11. 11. 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
  12. 12. 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
  13. 13. 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
  14. 14. Security• SNMP leads to vulnerability to a variety of security threats because of lack of any authentication capabilities Threats Modification MessageMasquerading Disclosure of Information Sequence
  15. 15. Post Office Protocol (POP)• Used to retrieve email from remote server to local client over TCP/IP connection• E-mail clients using POP3 connect, retrieve all messages or store them on users 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
  16. 16. POP Session states
  17. 17. 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
  18. 18. IMAP Advantages and Disadvantages• Advantages:  Disadvantages: – As the e-mail folders are  Complicated stored on the server, the user is able to read email  Results in higher server from any computer loads than POP3 which belongs to the  Utilizes a lot of server network resources – To access more than one account from different locations, IMAP will be the most efficiently
  19. 19. Electronic Mail (E-mail)• Provides way to communicate and send letters over the Internet Mail Delivery System Mail Mail Mail Mail User Submission Transfer Delivery Agent (MUA) Agent (MSA) Agent (MTA) Agent (MDA)
  20. 20. 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
  21. 21. User Agent (UA)• Allows user to send and read e-mail• Program that provide various methods such as command based, menu based or graphical to interact with the e- mail• Sending Mail - User needs to provide message, destination address and other parameters while sending an e-mail• Receiving Mail - The UA at the recipient end checks the mailbox periodically for new e-mail
  22. 22. Message Transfer Agent (MTA)• Moves message from source to destination• Process that run in the background and transfers the e- mail 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
  23. 23. RFC 822 Message Formats Header MeaningTo: Primary recipient e-mail addressCc: Secondary recipient e-mail addressBcc: Blind carbon copy e-mail addressFrom: User who created the messageSender: Senders e-mail addressReceived: Line added by each transfer agent along the routeReturn-Path: Can be used to identify a path back to the senderDate: The date and time of the message sentReply-To: Email address to which replies should be sentMessage-Id: Unique number for later referenceIn-reply-To: Identification of the message to which this is a replyReferences: Over relevant message-idKeywords: Keywords chosen by userSubject: Summary of the message
  24. 24. 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 other connections between them• Data encryption provides privacy by translating the content into different format which is unreadable
  25. 25. 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
  26. 26. 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
  27. 27. 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 anotherCannot provide host with temporary IP address Provides host with temporary IP addressThis type of IP address configuration is designed to This type of configuration is used to configure IP addresses to configure hosts, which are diskless workstation. computers or host that are frequently relocating from network to networkSupports finite or limited number of client IP address Supports large and extensible number of client IP address configuration parameters configuration parameters as compared to BOOTP
  28. 28. 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
  29. 29. 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
  30. 30. 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
  31. 31. 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
  32. 32. 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
  33. 33. 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
  34. 34. Working on WWW• Structure of finding information over internet divided into three stages: – Finding documents – Formulating queries – Determining relevance