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Ch-08 (Comp) - The Internet _ Computer Security.pdf
- 1. Chapter 8 The Internet& Computer Security INTRODUCTION TO COMPUTER Revised by: Ansar Javed Govt. Graduate College Garhmaharaja, Jhang. Slides Copyrights © PM Series (Original Authors) 1
- 2. The Internet Chapter 8– The Internet & Computer Security 2
- 3. The Internet • Theword "Internet" stands for International Network • Internet is the largest computer network in the world • Information can be sent and received through the Internet all over the world • Internet is the network of many computer networks around the world • It consists of millions of private, public, academic, business, and government networks • Communication protocol used for the Internet is TCP/IP • Internet connects millions of computers • These computers are linked through different communication media • Commonly used communication media are telephone lines, fiber optic cables, microwave, and satellite • A large number of books, newspapers, magazines, encyclopedia, and other types of materials are available in electronic form on the Internet • We can find information about almost anything in the world 3
- 4. The Internet • Wecan also access the latest information or news on any topic • It means that Internet is an ocean of knowledge • In addition to finding information, we can communicate with other people around world. • Due to Internet, our world has become a global village 4
- 5. The Intranet • Aninternal private network of an organization that can be accessed only by the authorized users of the organization is called Intranet • It uses Internet and Web technologies for sharing information between the users of the same organization or company • It looks like a private version of the Internet • Information cannot be exchanged outside the organization 5
- 6. The Extranet • Anetwork of an organization that can be accessed by authorized outside users is called Extranet • It is an extension of the Intranet • It may consist of two or more intranets • It is used for business and educational purposes • It uses Internet technology and the public telecommunication system for sharing business information with authorized outside users • These users may be customers, suppliers, business partners, etc. • An outside user accesses the Extranet by using the username and password 6
- 7. Internet Protocols FTP • FTPstands for File Transfer Protocol • This protocol exchanges files between users • It is specially designed for uploading and downloading audio, video, graphics, and all other different types of files • FTP software uses this protocol for transferring files on the Internet • Examples of FTP software are WS_FTP and Cute FTP HTTP • HTTP stands for HyperText Transfer Protocol • It is a protocol used for communication between browsers and web servers (e.g. for transferring information from web pages, stored on the web server, to the browser) • It was developed in 1990 when the World Wide Web (WWW) was introduced SMTP • SMTP stands for Simple Mail Transfer Protocol • This protocol is used to send and receive e-mails on the Internet 7
- 8. Services Provided bythe Internet Chapter 8 – The Internet & Computer Security 8
- 9. Services Provided bythe Internet • Internet plays a very important role in our society • It provides a lot of latest information about the business, education, etc. • It has become the main medium for advertisement and communication between users etc. World Wide Web • World Wide Web is commonly known as the web • This service is used to get different information on the Internet • World Wide Web is a vast network of HTTP servers or Web servers • These servers store webpages (websites) that are accessible on the Internet • World Wide Web is abbreviated as www or 3w 9
- 10. Services Provided bythe Internet Newsgroups • Newsgroups are discussion groups or forums • They provide services to exchange messages on Internet about a particular subject • This facility is provided on the Internet on special servers known as News servers Chatting • Internet provides facility to chat (talk) with people online all over the world • Different programs like MSN Messenger, Yahoo Messenger, AOL online, etc. are available for chatting on the Internet • Chat rooms allow users to participate in a chat on the Internet E-mail • E-mail stands for electronic mail • It is the most popular service provided by the Internet • It provides a fast and efficient way to send and receive messages through the Internet. You can send different types of files can also be sent through e-mail 10
- 11. Services Provided bythe Internet E-Commerce • E-Commerce stands for Electronic Commerce • It is a very important service provided by the Internet through which financial transactions are carried out over the Internet • It is the modern way to run a business on an international basis • When business is conducted with the help of computer networks, this activity is usually termed as e-commerce or e-trade • Examples of E-commerce are: online shopping, online advertising, online banking, etc. • Through e-commerce, goods can be purchased and sold from anywhere in the world • Credit cards are used for payments 11
- 12. Terminologies & Toolsused for Internet Chapter 8 – The Internet & Computer Security 12
- 13. Terminologies & Toolsused for Internet Web Server • A computer on the network (i.e. Internet) in which websites or web pages are stored is known as a web server • We access a web page or website from a web server through a web browser • We send a request to the web server through a web browser • Web server receives the request and sends back information of the web page or website through the web browser • Nowadays millions of web servers are providing these services on the Internet Client • Hardware and software through which user gets information from server as well as sends information to other users through server is called client • Usually, personal computers and browser programs are used to get information from server 13
- 14. Terminologies & Toolsused for Internet Web Browser • A software that is used to access websites or web pages is known as a web browser • A user enters the URL of the website in the address bar of the browser window • Browser accesses the website or web page and its information are displayed in the main window of the browser • Many web browsers are available • Examples → Internet Explorer, Google Chrome, Opera, Mozilla Firefox, and Safari Web Page • A document on the Web (World Wide Web) is called a web page • This document can contain text, graphics, audios, videos, and links to other web pages Website • A collection of related web pages is called a website • A website may contain many web pages and some other files • A user can access any website through a web browser 14
- 15. Terminologies & Toolsused for Internet Home Page • Main page or title page of the website is known as the home page • It provides an introduction to the website • This page is downloaded first when the website is accessed • Usually, all links of other pages of the website are given on the home page • Therefore, other pages of the website are visited or accessed through the home page Web Hosting • Web hosting is the service which provides the online storage space for storing website or web pages on the web servers • Companies which provide storage space on their web servers are known as web hosts 15
- 16. Terminologies & Toolsused for Internet HTML • HTML stands for Hyper Text Markup Language • HTML is a computer language • It is used to create web pages/websites • This language provides commands (or keywords) for creating HTML documents • These commands or keywords are called tags • These tags are used for defining the layout (or structure) of a web page, formatting text of a web page, and linking other web pages URL Address • URL stands for Uniform Resource Locator • It is an address of a web page or website on the Internet • Every web page has a unique address • A web page can only be accessed if we know the URL of that page • For example, Google is the most popular website and its URL is http://www.google.com 16
- 17. Advantages & Disadvantagesof the Internet Chapter 8 – The Internet & Computer Security 17
- 18. Advantages of theInternet + Sharing Information + Collection of Information + News + Searching Jobs + Advertisement + Communication + Entertainment + Online Education + Online Results + Online Airlines and Railway Schedules + Online Medical Advice • Details are given in book “Introduction to Computer” – PM Series 18
- 19. Disadvantages of theInternet - Viruses - Security Problems - Immorality - Filtration of Information - Accuracy of Information - Wastage of Time • Details are given in book “Introduction to Computer” – PM Series 19
- 20. Search Engines Chapter 8– The Internet & Computer Security 20
- 21. Search Engines • Asearch engine is a special website on the Internet • It is used to search different information on the Internet (or web) • A lot of information is available on the Internet on different websites or webpages • There are billions of websites on the Internet • We cannot remember the URLs of all the websites • We can search different websites or webpages and information stored in them through search engines • Search engines maintain a list of billions of webpages containing information on various topics • Many search engines are available on the Internet • YAHOO http://www.yahoo.com • ALTA VISTA http://www.altavista.com • ASK http://www.ask.com • GOOGLE http://www.google.com • EXCITE http://www.excite.com 21
- 22. Search Engines Searching Informationusing Search Engine • Some keywords (i.e. words) related to the topic or information being searched are given to search engine • Search engine searches the required information and sends the addresses of webpages containing the required information to the user’s computer • For example, to search information about the "History of the Internet", give these words to any search engine • Search engine will search the given information and will provide a list of links of webpages or websites along with a brief description of each webpage 22
- 23. Computer Security Chapter 8– The Internet & Computer Security 23
- 24. Computer Security • Today,critical or important information of many organizations is stored and managed on computers and mobile devices • Information may be credit card numbers, customer’s bank account information, and purchase information • Computers and mobile devices, along with the information they store, are accessible and available when needed • Many organizations provide online services to their customers/users • Data is stored online for providing fast services • For example • A credit card company may put data of its customers online • A bank providing online services • A university may provide the facility of viewing results online. Similarly, people take online exams like GRE, GUAT, etc. 24
- 25. Computer Security • Data/informationcan be lost or destroyed or misuse due to different reasons • It can be deleted or destroyed accidentally or intentionally • Data is more valuable than computer hardware and software • In case of failure of hardware, it can be replaced • Similarly, in case of loss of software, it can be re-installed • But in case of data loss, it is difficult to recover in time • Organizations must take measures (or necessary arrangements) to protect or safeguard their computers, mobile devices, and information/data they store, from loss, damage, and misuse. • Protecting a computer system and its resources (such as hardware, software, and information or data) from being damaged or accessed by unauthorized persons is called computer security • Different methods are used to ensure the security of a computer system 25
- 26. Authorized Access &Unauthorized Access • Accessing a computer or its resources legally is called authorized access • Sometimes a legal user is restricted to a specific level of access • This level of access of a user is known as his/her authorized access • A process to check the rights of a user to access a particular computer system is called authorization • Accessing a computer or its resources illegally is called unauthorized access • When someone tries to exceed his/her level of access, it is considered unauthorized access • Unauthorized access to a computer or its resources is a crime 26
- 27. Computer Virus Chapter 8– The Internet & Computer Security 27
- 28. Computer Virus • Aprogram or piece of code that infects or affects the computer system or mobile device and files/programs stored in it is called a virus • It can load into the user’s computer primary or secondary memory without his/her knowledge • The code for a computer virus is written in a programming language • This code is attached to a file such as a program file • A file containing a virus is called an infected file • When the infected file is copied to a disk, the virus is also copied and it hides itself or attaches to other files on the disk • A disk that contains virus/viruses is called an infected disk • Different computer viruses create different problems in different ways • A virus may destroy all data stored in the hard disk by formatting it • A virus may change the boot sector of the hard disk. If the boot sector of a disk is affected, it cannot boot the computer • A computer virus is automatically loaded from disk into the memory of the computer. It slows down the data accessing speed of the computer • A virus may detect some special information like passwords or any sensitive data and send it to some other user on a network. For example, a virus may read the ‘Pin Code’ of a credit card, entered by a user, and then sends this information to another user. 28
- 29. Activation of aVirus • When a virus performs its actions, it is called the activation of a virus • Different computer viruses are activated in different ways • For example, some viruses are activated on a fixed date • Usually, these viruses are part of the application programs (or operating systems) • When the application program is run on the computer, it checks the system date • If the system date matches with the activation date of the virus, the virus is activated 29
- 30. Causing of SpreadingViruses Removable Storage Media • In a flash drive / CDs, some files may be infected by viruses • When a user copies infected files from a flash drive into his/her computer, viruses are also transferred/copied Networks • In a computer network, if a computer is infected by a virus then this computer may infect other computers in the network also • For example, when users access the infected computer in the network, viruses are transferred or copied into their computers with downloaded files. Insecure Websites • There are many websites on the Internet that are not completely secure • When we access these insecure websites then viruses are also automatically downloaded and infect our computers Email Attachment • An email may contain an infected file attachment • When a user opens an infected email attachment, virus may infect computer • This virus is also transferred to other computers when email messages are sent from the infected computer to them Pirated Software • Word ‘pirated’ means ‘copied illegally’ • Software which is installed and used illegally (or without a license) is called pirated software • Pirated software is also a major source of spreading viruses 30
- 31. Antivirus Programs Chapter 8– The Internet & Computer Security 31
- 32. Antivirus Programs • Asoftware that detects and removes viruses from the computer or mobile device is known as an antivirus program • Most antivirus programs can also detect and remove viruses from the computer or mobile device • Many antivirus programs automatically scan all types of removable storage devices inserted in the computer or mobile device, files downloaded from the web, and email attachments • These programs also prevent viruses from entering into the computer • Most of the email servers and web servers also have antivirus programs installed to check incoming and outgoing email messages and files for viruses • A large number of antivirus programs are available • These programs contain a list of known viruses • They also contain methods for removing these viruses from infected files or disks • However, there is no single antivirus software, which can remove all types of viruses • If an antivirus identifies/detects an infected file, it attempts to remove the viruses 32
- 33. Antivirus Programs • Latestantivirus software must be installed on the computer to save the computer from new viruses • We should update antivirus and scan the computer system regularly • Examples of Antivirus • Symantec • McAfee • AVG • Avast • Kaspersky • NOD 32 • Windows defender 33
- 34. Some Important longQuestions 1. What is the Internet? How we access it. 2. Distinguish between the Internet, Intranet and Extranet. 3. What services are provided by the Internet? 4. What is Search Engine? How it helps us? 5. What is Computer Security? Distinguish between Authorized and Unauthorized access. 6. What is Computer virus? How it gets activated and spread? 7. What is Antivirus program? List few examples. 8. What is eCommerce? How can we utilize it for our benefit. *note: Please don’t limit yourselves to these long questions only, examiner can ask you about same material in different context. You can extract several short questions as subset of these long questions. 34
- 35. For more details,refers to PM Series Introduction to Computer by CM Aslam, Aqsa Aslam, Mussadiq Fida, & Mudassir Ahmad Publisher:Majeed Sons 22- Urdu Bazar, Lahore 35