INTERNET AND ITS APPLICATIONS

Transcription

1 UNIT 3 INTERNET AND ITS APPLICATIONS Structure 3.0 Introduction to Internet 3.1 Objectives 3.2 Telnet 3.3 FTP FTP commands Steps to get/put data from an anonymous FTP site 3.4 Gopher Usenet Classification of news groups 3.5 Web Browser 3.6 Search Engines 3.7 Google Search Engine Components of Google Search Engine Search tips using Google Steps to create account Spam mail Voice mail 3.9 Internet Chat Session Instant Messaging Voice chat 3.10 Blog 3.11 Internet Development Tools 3.12 Internet Security and Security Measures 3.13 Summary 3.14 Further Readings 3.0 INTRODUCTION TO INTERNET Internet is a collection of million of computers and computing devices that are all connected using wire and wireless technologies with star, bus, ring or mesh topologies. Internet basically operates on TCP/IP protocol. With help of internet user can view results of examination, access bank account, view stock market details, news, sports, etc, Ftp allows user to download/upload files across multiple sites. Various web browsers provides facilities to search on a specific topic, have account, logs, etc., Internet security can be provided by firewall and antivirus software. 3.1 OBJECTIVES After studying this unit, the student is expected to be capable of the following: Knows about TELNET Knows about FTP Knows about GOPHER 1

2 Will be able to browse Internet Use search engines Able to give Able to chat Create a blog Exposure to Internet development tools Exposure to Internet security 3.2 TELNET TELNET (TErminal NETwork) is a protocol that enables the user to log on a different system and use the resources. The different system (remote) can be located in same building, city, and country or geographically located in another place of the world. The system where the user works physically (local system) is called client and the remote system is called host. Therefore, telnet follows client/server model. To access the host system, user should know the IP address of that system. If user has login account and password on remote system, then it is called full-privilege telnet session, otherwise user can login as guest and share resources (files, memory and CPU) Restricted telnet connection is called anonymous/guest telnet session 3.3 FTP FTP (File Transfer Protocol) is a protocol to transfer file(s) from local machine to remote machine or get file(s). FTP works on a client/server model. On the local machine FTP client is installed and on the remote machine FTP server is installed. Many FTP sites allow anyone to log on the server and download related files. Such ftp sites are known as Anonymous FTP. In restricted ftp sites, user should get login and password from the ftp server system FTP Commands account, append, ASCII, bell, binary, bye, case, cd, cdup, close, cr, delete, debug, dir, discount, form, get, glob, hash, help, lcd, ls, macdef, mdelete, mdir, mget, mkdir, mls, mode, mput, nmap, ntrans, open, prompt, proxy, sendport, put, pwd, quit, quote, recv, remotehelp, rename, reset, rmdir, runique, send, status, struct, sunique, tenex, trace, type, user, verbose Steps to get/put data from an anonymous FTP site 1. FTP to access file in Berkeley education web site. Type ftp anarres.cs.berkeley.edu at command prompt. Login is anonymous and password is guest. Any one can access these files. Figure 3.1 depicts successful login. 2

3 Figure Help at ftp prompt displays a list of ftp commands(figure 3.2). Figure ls displays list of files on Berkeley site; Here folders are pub and ucb(figure 3.3) Figure cd pub. Change directory to pub (public) directory and ls displays list of file on pub directory (figure 3.4) 3

4 Figure cd algebra, change directory to algebra. ls al, displays list of file in long format (figure 3.5) 4

5 Figure pwd print/present working directory. Binary to get/put files in binary mode and ASCII to get/put files in ASCII mode. lcd to display local directory path and get MixedVolume gets the file to local directory c:\. Disconnet to close the connection to Berkeley. put file.txt is valid, provided the anonymous user can put files on the destination site. Otherwise put is not valid(figure 3.6) Figure Once the ftp task is done, close/disconnect will close the web site connection and bye will terminate ftp session(figure 3.7) 5

6 Figure GOPHER Gopher is a tool to search, download and display related data from various sites across the world. It is a client/server application similar to any web browsers. Presently, WWW is used with much more search facilities and options compared to gopher. A gopher space maintains all the related data of various fields. For a gopher session any one of the following are used: Browser for Gopher Client based gopher tool based on the operating system being used Archie to search a file related to topic of interest. And later downloaded using FTP Veronia Used to access all gopher space for a search also use other search engine features CWIS Campus Wide Information Servers. Using gopher servers, data related to campus of school, university, office, banks, corporates can be maintained. Now-a-days much sophisticate www tools are used. WAIS Wide Area Information Server. Using Veronia detail searching is not done and contents of documents are not referred. Using WAIS, details search can be done over more than 10,000 data bases Usenet Usenet is an application tool which enables the user(s) to join the user group(s) and chat or discuss on any topic of interest. These groups are called Usenet News Groups. There are more than 7000 Usenet groups. Each usenet site is maintained by news server and managed by administrator. Newsgroups are distributed around the globe through news servers Classification of news groups Comp - computer related features i.e. data bases, architecture, operating systems, games, etc., News - news related network like announce, questions and answers etc. Rec - recreational topics like sports, books, cinema, dance, music etc. Biz - business and management related features Soc - society related issues 6

7 sci - Scientific and technical features like physics, mathematics, chemistry, biology, etc. talk - group discussion and debate alt - wide range of subjects misc - miscellaneous topics 3.5 WEB BROWSER An application that runs at user end and facilitates to access many internet resources like , search engine, train/air reservation, examination results, net banking, online shopping, etc., Using URL, the corresponding web site is found. Web browsers operate using HTTP protocol. Browsers support text, audio, video, animation, etc., features for displaying web pages. Various types of web browsers are Microsoft Internet Explorer, Netscape Navigator, Mozilla, Konqueror, Firefox, Safari, Opera, Lynx, etc., With the help of web browsers user can access search engines, and access s and use all the facilities of internet. 3.6 SEARCH ENGINES Search engines provide the facility to search on any topic across many sites in various formats. Programs called spiders scan web periodically and maintain latest update in search engines. Search engine operates on the architecture of search query techniques. Various types of search engines are AltaVista, Aesop Search, ASK Jeeves, Direct Hit, Excite, Google, HotBot, Lycos, NorthenLight, SearchKing, WebCrawler,Yep,etc., Each search engine is application specific and google search is wide generally used. 3.7 GOOGLE SEARCH ENGINE Images, Video, Maps, News, Shopping, Gmail etc. are components of Google search engine Components of Google Search Engine 1. Browse to Search can be done using in any regional or national languages like Hindi. Default language is English (figure 3.8). Figure 3.8 7

8 2. To search for any image on any topic, click on Images on (figure 3.9). Figure To locate any part of the city in any country across the continents, click on Maps on (figure 3.10). Figure To track latest news in various countries, click on News on (figure 3.11). 8

9 Figure With Orkut, user can create a community of friends and share text, audio, video and instant message. Orkut mobile helps user to communicate through VoIP (figure 3.12). Figure Google Scholar is an advanced search engine useful for researchers to search for articles etc. (figure 3.13). 9

10 Figure Google Translator will translate text from/to any language(figure 3.14). Figure Google YouTube to share, upload and view video clips. Video clips can be any movie clip, user generated sequence of slides, TV clips or any clips. YouTube has video clips with audio facilities in built. Browse to (figure 3.15) 10

11 Figure Search tips using Google For searching for any topic user has to type the relevant text and click on search option. Various options used in google search are: 1. Quotes ( Mega Structures ) - Searches for exact string Mega Structures is shown in figure Figure Exclude words ( Bio -Chemistry) Searches for Bio and not related to chemistry (figure 3.17). 11

12 Figure Similar words (~Wireless) Searches for words like mobile, cell, laptop, cellular, etc. (figure 3.18). Figure Multiple Words (Quantum OR Nano Computing) Searches for quantum or nano computing (figure 3.19). 12

13 Figure Range (Global climate change ) Searches for global climate change from 2001 to Define (Define YouTube) Searches for the definition of YouTube (Figure 3.20) Figure

14 7. Site Specific (VLSI Design site:.edu)- Searches for VLSI Design in all educational institutions (figure 3.21) Figure Link Page (MCA Course: Searches for MCA in ignou web page (figure 3.22) Figure

15 3.8 is Electronic Mail. works on Simple Network Management Protocol (SNMP). Using we can send text, audio and video files to one person or a group of persons. Free can be created in Google, Yahoo, Hotmail, Netscape, Lycos, etc., the following shows sequence of steps to create account in Gmail which is a part of Google.com. To create account in yahoo site, hotmail site or any other site same sequence of steps can be followed Steps to create account Steps to create account in Gmail from Google site: 1. In Internet Explorer or any other web browser, type and at top right corner click on sign in option and the page as shown in figure 3.23 appears. Figure Click on Create an account option and fill your personal details, as shown below. Here first name is Student, last name is IGN. Desired login name is student, and password is given by user and kept confidential (figure 3.24). 15

16 Figure Security question can be entered as given by gmail or user can have his/her own question and answer should be given in the below answer option In case user forgets his/her password, gmail will prompt user this question, and user should give the correct answer given by him, otherwise gmail will not access use to login to the system. Word verification meant for confidentiality, so that no automated tool can create user account (figure 3.25). 4. After reading terms and conditions, finally user has to click on I accept create my account option and his account is created (figure 3.26). 5. Figure

17 Figure 3.26 Therefore, account of studentign has been created. The various components of are explained below: 1. Inbox - Consists of new mail that is not seen and old seen mails in a page. Inbox is located on left column of gmail. Once the user clicks on the new mail received, content of the mail is seen on new window (figure 3.27). Figure Compose Mail Meant of composing a mail to a person or group of persons. In To: recerver s identity (studentignmca@gmail.com) is written Subject: Welcome you or any other subject regarding user and content of message is written Message Box: Here the content of the message is written and fonts, size and color can be changed. Once the message is typed, send button at top of In Box is clicked and message is send to the receiver (figure 3.28). 17

18 Figure Sent Mail Gives a list of messages sent by user studentign (figure 3.29). Figure Trash Consists of list of mails deleted(figure 3.30) Figure

19 5. Contacts Helps the user to add user name and their address, postal address, phone numbers,etc., of their friends, family members, etc. (figure 3.31). Figure Settings Change - Click settings option on top right corner of the window to modify/update user account settings (figure 3.32) Spam mail Figure 3.32 Spam is unsolicited junk send my commercial companies for advertising or by any unknown person sending through know address. Spam decreases traffic due to the capacity of unnecessary flooding. Few spam mails can be detected and for bulky of spam mails it is more difficult to detect who actually is sending the spam. Web sites provide spam filter to restrict unnecessary s to your system Voice mail 19

20 Normal has text, animation and images files. In voice , the user must record his/her voice and send. When the receiver opens the , voice is heard. At both the ends voice mails need the audio hardware. 3.9 INTERNET CHAT SESSION Chat is meant for live discussion using text and multimedia features. On the left bottom of the window, click on chat option; add user identity with whom we want to chat. Confirmation comes from the recipient and the chat becomes a two way process. Internet chat provides a facility to have live chat between many persons or group of persons. It is a multi way chat technique. Internet Relay Chat (IRC) provides the facility of internet chat. Each chat group has as separate channel maintained my IRC architecture. It is normally not meant for one-to-one chat Instant Messaging Mainly meant for one-to-one private communication through messengers or SMS services in mobile phones. Using instant message text, picture can be send. Tools that provide instant message features are Microsoft Messenger, Netscape AOL Instant Messenger, Yahoo Messenger, etc, Voice Chat In instant message we can send message, but in voice chat we can have live audio communication between two persons or group persons using the features of IP telephone and VoIP (Voice over IP). Many messenger tools support the feature of voice chat also. Let us assume there are two users given below want to login: 1. Student-MCA 2. Student-IGN For these two users, account has to be created in any provider (yahoo mail, gmail, hotmail, etc.,) and their respective identity should be added in each chat options. 1. Figure 3.33 shows a live chat between two students 20

21 Figure Using left bottom option users can start voice chat and/or video chat. In this slide, both the systems do not have audio and video peripherals, as the text appears on the chat area (figure 3.34). Figure Users can use smiley faces for better dialogue (figure 3.35). 21

22 Figure Above three slides indicate a separate chat window for each user. Here the chat window is docked out to gmail user, to have full length chat. Docked option is shown with middle arrow option on right top of chat window. Once the user minimizes the chat window, it gets docked in to the gmail window as given below (figure 3.36) BLOG Figure 3.36 A blog is a type of internet website, usually maintained by an individual or a small company with frequent entries to descriptions of their interest, events, news, game, movies or to any person sharing his/her views. Material such as text, graphics, audio and video can also be shared using blog. Blog is normally a one way communication, where user gives his ideas or comments on that blog site. There are various types of blogs like science blog, social blog, movie blog, political blog, news channel blogs, etc INTERNET DEVELOPMENT TOOLS 22

23 Java A programming language enables to run applications from internet. Java applets provide the facility of GUI and audio/video features. Supports various types of operating systems and it is operating system independent. Active X Active X components and controls are downloaded and run on the computer. Active X supports all features of internet. IE supports Active x technology. JavaScript - Script for internet application to create forms, tables and GUI components. Java script lacks the complexity of programming skills. Java script can call components create by Java programming. ASP and.net also enhances the development of internet INTERNET SECURITY Computer viruses provide major threat to the system and hamper users work. Memory and data gets lost and corrupted. Virus slows down CPU and I/O performance. Virus attack systems data from internet or portable devices like pen drive, CD/DVD drive, etc. The solution is to have full updated antivirus software. Cookies are bits of data put on disk when someone visits web site. Cookies keep track of user login and password and list of files opened by the user. Hackers can access the cookies and trace personal details about the person. The following are some of the security measures possible: Access control software Software should be license certified and permission should be given to users having login accounts Antivirus software Various types of antivirus and spyware software are to installed to keep system secure Firewall Acts as a protection between computer and external network. Firewall can be a combination of hardware and software. It is normally installed on the servers and routers. List of web sites can be listed in the firewall table, restricting unwanted programs to access the system. User login and password Only users having login and password should use the systems. Users should not be given any administrator permission to modify any files. Session-1 (3 hours) Question 1: Search for information on CIT programme using atleast two search engines. Question 2: Download a video related to the topic titled How to browse Internet or any other technical topic of your interest from Internet. Question 3: Create an account using any website which enables creation of free accounts. Question 4: Create your own blog, include information about the seven wonders of the world on it. Question 5: Chat with any of your friends. 23

24 3.13 SUMMARY This unit gives practical idea of Internet and their applications. Using FTP user can download/upload any file from.edu or any other site. Main functionality of Web Browsers are explained. Various features of Google search engine and its option are explained with screen outputs. User can try these and get familiar with google search options. Various steps to create account in google are given and the same may be followed for any provider. Chat, instant message and voice chat are explained briefly. Definition of blog and its applications are given. Further, various types of programming development tools are mentioned briefly to enhance the feature Internet and its applications. Lastly, Internet security and various security measures are explained FURTHER READINGS Internet 101: A Beginner s Guide to Internet and World Wide Web by Elizabeth Castro and Wendy G Lehnert; 1998; Addison Wesley Publications How the Internet Works:Millenium Edition by Preston Gralla, Sarah Ishida, Mina Reimer and Stephen Adams; Techmedia Publications