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12, Key Concepts, l, l, , l, , History of the Internet, Connecting the computer to, the Internet, Types of connectivity, o, o, o, o, , l, , Services on Internet, o, o, o, o, , l, , Dial up, Wired broadband, Wireless broadband, Internet access sharing, methods, www, Search engines, Email, Social media, , Cyber security, o Computer virus, worm, Trojan, horse, spams, hacking,, phishing, denial of service, attack, man-in the-middle, attacks, , l, , Preventing network attacks, o Firewall, antivirus scanners,, cookies, , l, , l, l, , Guidelines for using, computers over Internet, Mobile computing, Mobile communication, o Generations in mobile, communication, o Mobile communication, services, , l, , Mobile operating system, , In the previous chapter we saw that the Internet, is the largest computer network in the world. We, use the Internet to check SSLC results, to submit, applications for higher secondary school, admissions and check its status, to get, information about various types of scholarships, and to submit applications for receiving them,, etc. Can you imagine life without the Internet, today? It would be difficult for us to manage all, the above tasks without it. Internet has definitely, made life easier for us. It has influenced our daily, life to a great extent. Because of its wide, popularity and increase in use even the television, sets with facilities for Internet connectivity have, come up in markets., People generally use the Internet to search, information, access e-mails, make bill payments,, for online shopping, online banking, to connect, with people in social networking sites, etc. The, reach of Internet is very vast and it helps in, reducing cost and time. Issues like online intrusion, to privacy, online fraud, cyber-attacks, etc. are, becoming common now. Apart from the Internet, and its access methods, let us discuss the various, services provided by the Internet like search, engines, e-mail, social media and about the threats, and preventive measures while using Internet in, this chapter.
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12.1 History of the Internet, The Internet started as a small network through a project by the United States, Department of Defence by the name ARPANET (Advanced Research Projects, Agency Network). During 1970s this military network was connected to the, computers of Universities and companies that worked for the Department of, Defence. In 1984 the military network split from ARPANET to form MILNET to, be used by the American military only. ARPANET which used TCP/IP protocol, for communication was thereafter used for scientific research and information, sharing. Later, several other networks merged with ARPANET to form a large, network. ARPANET is considered as the first wide area network (WAN).Vinton, Gray Cerf who was instrumental in the development of Internet and TCP/IP, protocol, is considered as the father of Internet., Vinton Gray Cerf (1943 - ) popularly called Vint, Cerf, an American computer scientist, is widely, known as ‘Father of the Internet’. He was, instrumental in the initial development of Internet, along with his fellow American computer scientist Bob Kahn., He worked for the United States Department of Defence, Advanced Research Projects Agency (DARPA) and had a key role in the, development of TCP/IP protocol. He was also involved in the formation of, ICANN., , In 1989, Tim Berners Lee, a researcher, proposed the idea of, World Wide Web (WWW). Tim BernersLee and his team are, credited with inventing Hyper Text Transfer Protocol (HTTP),, HTML and the technology for a web server and a web, browser. Using hyperlinks embedded in hypertext the web, developers were able to connect web pages. They could design, attractive webpages containing text, sound and graphics. This, change witnessed a massive expansion of the Internet in the, 1990s., Fig. 12.1:Tim Berners Lee, , Various types of computers loaded with diverse operating, (1955 - ), systems in different organisations at geographically distant locations joined this, network making it a global phenomenon.TCP/IP protocol is used as the, communication protocol for Internet. Any computer that joins Internet should follow, the TCP/IP protocol. In 1998, Internet Corporation for Assigned Names and, Numbers (ICANN) was established. ICANN does not control the Internet content;, rather it develops policies on the Internet’s Uniform Resource Locators (URL)., 346
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12. Internet and Mobile Computing, , Today, Internet is the largest public network that connects billions of computers, all over the world and provides several services like searching, e-mail, file transfer,, social networking, etc. The Internet is an interconnected system of computer, networks that serves the users all over the world., An intranet is considered as a private computer network similar to Internet that, uses TCP/IP protocol to share information, software or services within an, organisation. An intranet can host websites, provide e-mail service, file transfer, and other services available on Internet., When an intranet is made accessible to some computers that are not part of a, company’s private network it is called an extranet. A network that allows vendors, and business partners to access a company resource can be considered as an example, of extranet., 12.2 Connecting the computer to the Internet, As we know today, the Internet has become very popular and almost all organisations, and people around the world are joining it. Earlier, people used the Internet to, search for information and check e-mails only, but today It is used to book train, tickets, recharge mobile phones, Internet banking and a lot more. Therefore almost, all of us require an Internet connection in our computers or mobile devices., The following are the hardware and software requirements for connecting a computer, to the Internet:, A computer with Network Interface Card (wired/wireless) facility and an, operating system that supports TCP/IP protocol, l, Modem, l, Telephone connection, l, An Internet account given by an Internet Service Provider (ISP), l, Software like browser, client application for e-mail, chat, etc., Nowadays desktop computers or laptops are not the only devices that we use to, connect to the Internet. People have also started using tablets, smart phones, etc. to, browse the Internet. Some of these devices come with built-in modems, whereas, others use a wireless dongle or wireless connection from a modem to access the, Internet., l, , 12.3 Types of connectivity, Today most websites use images and multimedia content to make webpages more, attractive. Several websites provide videos that can be downloaded or viewed on, , 347
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the Internet. Instead of distributing software in CDs or other storage media, it is, now distributed online by various vendors. The latest trend shows that software, like word processors, spreadsheets, antivirus, etc. are used online on a rental basis, instead of installing it on each computer. In all these cases, a large volume of data, is transferred online. Therefore the speed or data transfer rate of the Internet is an, important aspect. Data transfer rate is the average number of bits transferred, between devices in unit time., 1 kbps = 1000 bits per second, 1 Mbps = 1000 kbps, 1 Gbps = 1000 Mbps, Difference between unit symbols b and B, b stands for bit, B stands for Byte, Difference between unit symbols k and K, k = 1000 = 103, K = 1024 = 210, Here ‘k’ is a decimal unit and ‘K’ is a binary unit of measurement. But for, Mega, Giga and Tera, both decimal and binary units use ‘M’, ‘G’ and ‘T’ as, symbols respectively. They are differentiated from the context in which, they are used., Note that data transfer rate is measured in decimal units and memory is, measured in binary., , The main factor that decides Internet access speed is the type of connectivity we, choose to link to the Internet. Internet connectivity is classified based on the speed, of the connection and the technology used. They can be broadly classified as dialup connectivity, wired broadband connectivity and wireless broadband connectivity., The data transfer rates of each type of connectivity may vary as techonology, advances., , 12.3.1 Dial-up connectivity, A dial-up connection uses the conventional telephone line and a dial-up modem to, dial and connect to the server at the Internet Service Provider (ISP). Figure 12.2, shows the dial-up connectivity system. As the connection is made by dialing, it, takes time to connect to the server at the ISP. This connection commonly uses a 56, kbps modem that can transmit data up to a maximum speed of 56 kbps. This slow, , 348
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12. Internet and Mobile Computing, , Computer, Internet Service, Provider, Modem, , Telephone, lines, , Modem, , Fig. 12.2:Dial-up connectivity, , connection is comparatively less costly when compared to other types of connections., Another disadvantage is that a dial-up connection requires exclusive use of the, telephone line, i.e., while accessing Internet, we cannot make or receive telephone, calls (voice calls). Nowadays, broadband connections that have a higher speed are, replacing dial-up connections., , 12.3.2 Wired broadband connectivity, The term broadband refers to a broad range of, Fig. 12.3: Broadband, technologies that help us to connect to the Internet at a, modem, higher data rate (speed). Wired broadband connections, are ‘always on’ connections that do not need to be dialled and connected. Broadband, connections use a broadband modem (refer Figure 12.3) and allow us to use the, telephone even while using the Internet. Table 12.1 shows the comparison between, dial-up and wired broadband connections., Dial-up connection, • Slow connection, speed upto 56 kbps, , Wired broadband connection, • High speed connection,, speed usually higher than 256 kbps, , • Requires dialing to connect to ISP, , • Always on connection, , • Uses telephone line exclusively, , • Simultaneous use of voice and Internet, , • Uses dial-up modem, , • Uses broadband modem, , Table 12.1: Comparison between dial-up and wired broadband connections, , Popular broadband technologies are Integrated Services Digital Network (ISDN),, Cable Internet, Digital Subscriber Line (DSL), Leased Lines and Fiber to the Home, (FTTH)., a. Integrated Services Digital Network (ISDN), ISDN is a broadband service capable of transporting voice and digital data. Most, ISDN lines offered by telephone companies give users two lines. The users can use, 349
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one line for voice and the other for data, or they can use both lines for data. ISDN, lines are capable of offering data transfer rates upto 2 Mbps., b. Cable Internet, Cable Internet access provides Internet access using coaxial cables laid for television, signal transmission to our homes. The service provider uses a cable modem at our, home to connect our computer to cable network. Cable TV systems are designed, to carry large bandwidth and therefore cable Internet can provide speeds between, 1 Mbps to 10 Mbps., c. Digital Subscriber Line (DSL), DSL is another broadband service that provides connection to the Internet through, standard telephone lines. DSL allows the user to use copper telephone lines for, both Internet communication and for making voice calls simultaneously. It is, composed of several subcategories, the most common being Asymmetric Digital, Subscriber Line (ADSL). ADSL is a communication technology that allows faster, flow of information over a telephone line. The down stream speed of ADSL, services typically ranges from 256 kbps to 24 Mbps. This connection requires an, ADSL modem at our homes/offices. ADSL is the most popular broadband service, available in India., d. Leased Line, Leased lines are dedicated lines used to provide Internet facility to ISPs, business,, and other large enterprises. An Internet leased line is a premium Internet connection, that provides speed in the range from 2 Mbps to 100 Mbps and is comparatively, costly. This is why leased lines are used only for connecting large campus of, organisations like educational institutions to Internet., e. Fibre to the Home (FTTH), Fibre to the Home (FTTH) uses optical fibres for data transmission. Optical fibres, are laid from the ISP to our homes. FTTH technology has been accepted worldwide, to implement high speed Internet to the home. Since optical fibres are known to, have high bandwidth and low error rates, they provide very high speed connectivity., A Network Termination Unit (NTU) is installed in our homes, which is connected, to our computer through an FTTH modem., , 12.3.3 Wireless broadband connectivity, Wireless broadband connectivity provides almost the, same speed as that of a wired broadband connection., The popular wireless broadband accesses are Mobile, Broadband, Wi-MAX, Satellite Broadband and, Wi-Fi. Some of the wireless modems available for, use to connect to Internet are shown in Figure 12.4., 350, , Fig. 12.4 : Wireless broadband, modems
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12. Internet and Mobile Computing, , a. Mobile broadband, Mobile broadband is wireless Internet access using mobile phone, USB wireless, modem, tablet or other mobile devices. The modem is built into mobile phones,, tablets, USB dongles, etc. Mobile broadband offers the freedom to allow the user, to access the Internet from anywhere on the move. This technology uses the cellular, network of mobile phones for data transmission. The mobile technology for data, transmission has been changing from 2nd Generation (2G) through 3rd Generation, (3G) to the current 4th Generation (4G). The speed of data transmission increases, with the progression of generations of mobile technology., b. Wi-MAX, In the previous chapter we learned that Worldwide Interoperability for Microwave, Access (Wi-MAX) is used as an alternative for wired broadband. Wi-MAX offers, a Metropolitan Area Network which can provide wireless Internet upto a distance, of 50 Km. Connectivity is provided using devices like Wi-MAX handsets, USB, dongles, devices embedded in laptops, etc. that have a Wi-MAX modem integrated, in it. This technology provides a maximum connection speed of upto 70 Mbps., c. Satellite broadband, Satellite broadband technology is a method by which Internet connectivity is, provided through a satellite. A Very Small Aperture Terminal (VSAT) dish antenna, and a transceiver (transmitter and receiver) are required at the user’s location. A, modem at the user’s end links the user’s computer with the transceiver. Download, speed is upto 1 Gbps for this technology. It is among the most expensive forms of, broadband Internet access. They are used by banks, stock exchanges, governments,, etc. and also for Internet access in remote areas., , 12.3.4 Internet access sharing methods, An Internet connection can be shared among several computers using a LAN,, Wi-Fi network or Li-Fi network., a. Using LAN, The Internet connected to a computer in a Local Area Network (LAN) can be, shared among other computers in the network. This can be done either using features, available in the operating system or using any proxy server software available in, the market. Sharing can also be done by connecting computers directly to the router, using a cable., , 351
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b. Using Wi-Fi network, We have heard of Wi-Fi campuses in large educational institutions, coffee shops,, shopping malls, hotels, etc. We also know that some of the broadband modems at, our homes and schools offer Wi-Fi Internet access.Wi-Fi is a popular short distance, data transmission technology that is used for network access, mostly Internet. WiFi locations receive Internet connection through any one of the above mentioned, wired or wireless broadband access methods, as discussed in the previous, section.They provide us Internet connectivity through, a Wi-Fi router or a wireless network access point., Such an access point, popularly called hotspot, has a, range of about 100 meters indoors and a greater range, outdoors. We access Internet in our Wi-Fi enabled, devices like laptops, tablets, mobile phones, etc., through these hotspots. A drawback of Wi-Fi is that Fig. 12.5 : Wi-Fi network, it is less secure than wired connections., c. Using Li-Fi network, Li-Fi (Light Fidelity) is a fast optical version of Wi-Fi, which uses visible light for, data transmission. The main component of this communication is a bright LED, (Light Emitting Diode) lamp that can transmit data and a photo diode that serves, as the receiver. LEDs can be switched on and off to generate a binary string of 1s, and 0s. The flickering of this LED is so fast that the human eye cannot detect it. A, data rate of over 100 Mbps is possible using this technique as light offers very high, bandwidth. Another advantage is that since Li-Fi uses light, it can be used in aircrafts, and hospitals where radio waves may cause interference. It can also be used, underwater where Wi-Fi does not work. It provides greater security as light cannot, penetrate walls when compared to Wi-Fi. One of the shortcomings of Li-Fi is that, it works only in direct line-of-sight. In future this technology can be further developed, to use light bulbs as a source of Internet., , Check yourself, 1., 2., 3., 4., 5., , 352, , ARPANET stands for _________., Who proposed the idea of www?, The protocol for Internet communication is ________., What do you mean by an ‘always on’ connection?, A short distance wireless Internet access method is _______.
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12. Internet and Mobile Computing, , Prepare a comparison chart on the different methods of Internet, connection., Let us do, , 12.4 Services on Internet, The Internet offers a variety of services. Services like WWW, e-mail, search engines,, social media, etc. are widely used throughout the globe. In this section we shall, discuss some of the services of Internet., , 12.4.1 World Wide Web (WWW), The World Wide Web (WWW) is a system of interlinked hypertext documents, accessed via the Internet. It is a service on the Internet that uses Internet infrastructure., WWW is a huge client-server system consisting of millions of clients and servers, connected together. Each server maintains a collection of documents and they can, be accessed using a reference called Uniform Resource Locator (URL). These, documents may contain text, images, videos and other multimedia content. It may, also contain hyperlinks to documents on different servers. Selecting a hyperlink, results in a request to fetch that document/web page from the server and display, it. The WWW works by establishing hypertext links between documents anywhere, on the network. Clients can access the documents on the servers using software, called browser. A browser is responsible for properly displaying the documents., , a. Browser, A web browser is a software that we use to retrieve or present information and to, navigate through web pages in the World Wide Web. The document to be displayed, is identified using a URL. A URL consists of its DNS name and the file name to be, retrieved. It also specifies the protocol for transferring the document across the, network. A browser is capable of displaying text, images, hypertext links, videos,, sounds, scripts (program code inside a web page), etc. in a web document/page., Most of WWW documents are created using Hyper Text Markup Language, (HTML) tags and are called web pages. The web browser interprets these tags and, displays a formatted page. It allows us to navigate through web pages using the, hyperlinks available in web pages. Some common browsers are Google Chrome,, Internet Explorer, Mozilla Firefox, Opera, and Safari. Icons of some popular, browsers are shown in Figure 12.6. Some of these browsers have a mobile version, that can be used in mobile operating systems., 353
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Google Chrome, , Internet Explorer Mozilla Firefox, , Opera, , Safari, , Fig. 12.6 : Icons of popular browsers, , b. Web browsing, All of us have visited web sites by entering the website address (URL) into web, browsers and then using the hyperlinks in it to move through the web pages., Traversing through the web pages of World Wide Web is called web browsing., Major operations performed while web browsing are shown in Figure 12.7., , ISP’s DNS server, , Web server, , Fig. 12.7 : Web browsing, , Suppose you wish to visit the website ‘www.kerala.gov.in’. What will you do? You, will enter this URL in the address box of the web browser and press Enter key., The steps a browser will follow to display a webpage may be summarised as follows., 1., 2., 3., 4., 5., 6., 354, , The browser determines the URL (http://www.kerala.gov.in) entered., The browser then sends a request to the DNS server of the user’s ISP to get, the IP address of the URL., The ISP’s DNS server replies with the IP address., The browser then makes a TCP connection to the web server at the IP address, (www.kerala.gov.in)., Then it sends a GET request for the required file (web page) to the web server., The web server returns the web page.
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12. Internet and Mobile Computing, , 7., 8., , The TCP connection is released., The browser processes the contents of the webpage and displays it., , 12.4.2 Search engines, Internet, , Finds new pages or, changed, information on a, web page., , crawls, , its, , Returns to create an, index in the server, , vis, , There are millions of pages available, on the Internet that contain, information on a variety of topics., But it is very difficult to search for a, topic in this large collection of web, pages. Internet search engine, websites are special programs that, are designed to help people to find, information available in World Wide, Web. Search engine programs search, documents available on World Wide, Web for specified keywords and, return a list of the documents/web, pages matching the keywords., , la u n c h, , es, , Spider/, Crawler, Search engine server, , Let us discuss the technology behind, these websites. Search engine web, Fig. 12.8 : Working of a search engine, sites use programs called web, crawlers or spiders or robots to search the web. Web crawlers search the web pages, stored in the different web servers and find possible keywords. The search engine, website stores these keywords along with their URLs to form an index in the search, engine’s web servers. When we use the search engine website to search a particular, , Fig. 12.9 : Search results of different search engines, , 355
Page 12 : topic (keyword), it does not search the World Wide Web. It only searches the index,, which the web crawler programs have created in the search engine’s web server for, the topic/keyword. Search engines select a list of URLs where the particular topic, is found from the index and displays it as the result. Figure 12.8 shows the working, of a search engine., Some of the most popular web search engine sites are Google, Bing, Yahoo Search,, Ask, etc. Figure 12.9 shows the search results of different search engines., , 12.4.3 E-mail, E-mail enables us to contact any person in the world in a matter of seconds. Billions, of e-mail messages are sent over the Internet every day. Electronic mail or e-mail, is a method of exchanging digital messages between computers over Internet., E-mail has become an extremely popular communication tool. The e-mail will be, delivered almost instantly in the recipient’s mail box (Inbox). Apart from text matter,, we can send files, documents, pictures, etc. as attachment along with e-mail. The, same e-mail can be sent to any number of people simultaneously. Figure 12.10, shows a sample e-mail message., , Fig. 12.10 – A sample e-mail message, , Most of you will have an e-mail address. The structure of an e-mail address is:, user name@domain name. An example of an e-mail address is,
[email protected], An e-mail address consists of two parts separated by @ symbol. The first part, scertkerala is the username that identifies the addressee and the second part gmail.com, is the domain name of the e-mail server, i.e., the name of the e-mail service provider., 356
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12. Internet and Mobile Computing, , E-mails can be accessed using websites like gmail.com, hotmail.com, etc. that provide, web applications consisting of functions to send, receive, forward, reply and organise, e-mails. Such a facility is popular and is commonly referred to as web mail., E-mails can also be accessed using e-mail client software that is installed in our, computers. Such software uses our e-mail address and password to retrieve e-mails, from the e-mail service provider’s server and store it in our computer. An e-mail, client allows to send, receive and organise e-mail. The messages sent when the, computer is offline are stored in the program and send later when computer is, online. For receiving messages, e-mail client applications usually use either the Post, Office Protocol (POP) or the Internet Message Access Protocol (IMAP). The, popular e-mail client applications are Microsoft Outlook and Mozilla Thunderbird., , a. Sections of an e-mail, A client software gives provisions to enter the following sections. Figure 12.11, shows the major sections of an e-mail., , Fig. 12.11 : Composing an e-mail, , To (Recepient Address) – A box to provide the e-mail addresses of the primary, recipients to whom the e-mail has to be sent., Cc (Carbon copy) – Write the e-mail addresses of the secondary recipients to whom, the message has to be sent., Bcc (Blind carbon copy) - Write the e-mail addresses of the tertiary recipients who, receive the message. When the message is received the primary and secondary, recipients cannot see the e-mail addresses of the tertiary recipients in the message., Depending on e-mail service used, the tertiary recipients may only see their own, e-mail address in Bcc, or they may see the e-mail addresses of all recipients., 357
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Subject – Provide a meaningful subject for your conversation here. This helps you, to identify a conversation with a particular person when you search your e-mails, later., Content – Type your message here. Today most of the e-mail service providers, offer features to create an attractive message by giving colours, changing font styles,, size, etc., Attachment facility allows us to send files like documents, pictures, etc. along with, an e-mail. The ‘Send’ button is used to send the message to the recipients. ‘Reply’, button allows you to send a reply back to the sender of the message received., ‘Forward’ button helps you to send a message received by you to other people., , b. Working of e-mail, Have you ever wondered how e-mail is sent from your computer to a friend on the, other side of the world? When an e-mail is sent from your computer using web mail, or e-mail client software, it reaches the e-mail server of our e-mail service provider., From there the message is routed from sender’s e-mail server all the way to the, recipient’s e-mail server. The recipient’s e-mail server then delivers the e-mail to the, recipient’s mail box (inbox), which stores the e-mail and waits for the user to read, it. Simple Mail Transfer Protocol (SMTP) is used for e-mail transmission across, Internet. Figure 12.12 shows the working of e-mail., 1. Sender, composes, message using, e-mail client/, web mail, , 2. Sender uploads, message to SMTP, server, , SMTP, server, , 3. Message, traverses Internet, (probably passing, through several, routers), , 4. Message arrives at, receiving server and is, placed in recipient’s, mailbox file/folder, , 5. Recipient’s e-mail client/ web mail checks, mailbox for new messages and downloads, message, 6. Recipient reads, message using email client/ web mail., , SMTP/POP3/, IMAP Server, , Fig. 12.12:Working of email, , 358
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12. Internet and Mobile Computing, , c. Advantages of using e-mail, The benefits of using e-mail facility are listed below., •, , Speed: An e-mail is delivered instantly to any location across the globe. We, can send the same e-mail to multiple users simultaneously., • Easy to use: We can send and receive e-mails, organise our daily conversations, and save them easily on our computer., • Provision of attachments: The attachment feature allows to send pictures,, files, documents, etc. along with e-mail., • Environment friendly: e-mails do not use paper and save a lot of trees from, being cut down., • Reply to an e-mail: When we need to reply to an e-mail, we can use the, provision of attaching previous e-mails as reference. It helps to refresh the, recipient about the subject., • Cost-effective: When compared to fax or conventional mail, e-mail is less, expensive., • Available anywhere anytime: Messages can be read at user’s convenience., Access to mail box is available anytime., The e-mail service, though beneficial in our daily life, can be misused in different, ways as listed below., •, , •, , E-mails may carry viruses: Viruses send along with e-mail can harm our, computer system. Viruses can also illegally access our e-mail address book, and spread virus infected messages to all e-mail addresses in it., Junk mails: Checking and deleting unwanted mails consume a lot of time., Internet of Things (IoT), Can you imagine a fridge which checks its egg tray and reminds you, to buy eggs in your mobile phone or orders the nearby grocery store, to supply eggs to your home; an air conditioner that can be switched, on or off using your mobile phone; or a car that automatically reminds you about, filling fuel as you approach a fuel pump? This is being made possible using Internet, of Things (IoT). IoT is the concept of connecting all devices like mobile phones,, fridges, cars, air conditioners, lamps, wearable devices, etc. to the Internet. Each, device is provided with a unique IP address which identifies it and allows it to, transfer data over Internet without human intervention. The huge increase in the, number of IP addresses due to the implementation of IPv6 supports the, introduction of this technology. The IoT can be used to monitor health of patients, and inform the doctor about an urgency, applied to things which help us reduce, wastage like power, water, etc. and improve the way we work and live., , 359
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12.4.4 Social media, All of us are familiar with wikipedia, the free encyclopedia in Internet. We have, also heard about people responding to social issues through facebook, twitter, etc., Also we know that people use youtube to share videos and for promotion of, products or business. All of these are part of social media which is changing the, way we communicate, entertain and live. Social media refers to the use of mobile, and web-based technologies through which individuals and communities can create,, share, discuss and modify content., In social media, interactions among people happen in virtual communities and, networks over Internet. These digital technologies influence the formation and, activities of civil communities to a great extent., , a. Classification of social media, The various types of social media that exist on the Internet are:, Internet forums, social blogs, microblogs, wikis, social networks,, content communities and a lot more. Figure 12.13 displays logos, of popular social media websites. Here we discuss the most, popular classifications of social media., 1., , Internet forums, , Fig. 12.13 Logo of, popular social, media websites, , An Internet forum is an online discussion web site where people can engage in, conversations in the form of posted messages. Each Internet forum will have sub, forums which may have several topics. Each discussion on a topic is called a thread., People can login and start a thread or respond to discussion in a thread. Some, forums allow anonymous login also. Discussions can be about programming, social/, political issues, fashion, etc. These discussions help us to learn and find solutions to, problems. Ubuntu Forum – a community that provides help on Ubuntu is a popular, forum., 2., , Social blogs, , A blog (web log) is a discussion or informational website consisting of entries or, posts displayed in the reverse chronological order i.e., the most recent post appears, first. Some blogs provide comments on a particular subject; others function as, personal online diaries and some others as online brand advertising for a particular, individual or company. Initially blogs were created by a single user only. But now, there are multi-author blogs that are professionally edited. Blogger.com and, Wordpress.com are popular sites that offer blogging facility., 3., , Microblogs, , Microblogs allow users to exchange short sentences, individual images or video, links. People use microblogs to share what they observe in their surroundings –, 360
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12. Internet and Mobile Computing, , information about events and opinions about topics from a wide range of fields., Microblogging offers a communication mode that is spontaneous and can influence, public opinion. Twitter.com is a popular microblogging site., 4., , Wikis, , Wikis allow people to add content or edit existing information in a web page, to, form a community document. Wiki is a type of content management system. Editing, done by users is very closely monitored by other editors and therefore incorrect, information, advertising, etc. are removed immediately. wikipedia.org – the free, online encyclopedia is the most popular wiki on web., Wikipedia is a free online encyclopedia to which, anyone can add content and edit. Wikipedia was formally, launched on 15th January 2001 by Jimmy Wales and Larry, Sanger using the concept and technology of a wiki. Wikipedia consists, of over 3 crore articles in around 300 languages. The english edition alone includes, around 44 lakhs articles and is one of the most visited websites on Internet. Articles, on topics range from very broad to highly specific. Each article consists of a number, of links to Wikipedia itself and other external resources. Since users are able to, create and edit articles, the quality of the content in the articles depends on the, person who contributes and edits it. The Malayalam edition of Wikipedia is available, at ml.wikipedia.org., , 5., , Social networks, , Social networking sites allow people to build personal web pages and then connect, with friends to communicate and share content. We can share text, pictures, videos,, etc. and comment to the posts. A social networking site can be for general topics or, for a specific area like professional networking. Public opinion is greatly influenced, by the discussions and posts in these websites. Popular social networking sites are, facebook.com and linkedin.com., 6., , Content communities, , Content communities are websites that organise and share contents like photos,, videos, etc. Youtube.com is a popular video sharing site and flickr.com shares, pictures., Most of today’s social media websites offer more than one type of service, i.e.,, social networking and microblogging; blogging and internet forum; etc. Studies, have revealed that social media is now recognised as a social influencer., , b. Advantages of social media, •, , Bring people together: Social networking allows people to find long-lost, childhood friends and make new ones., 361
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•, •, , •, , Plan and organise events: These sites help users to organise and participate, in events., Business promotion: Social media offers opportunities for businesses to, connect with customers, implement marketing campaigns, manage reputation,, etc., Social skills: These sites allow people to express their views over a particular, issue and become an agent for social change., , c. Limitations in use of social media, •, , •, , •, , Intrusion to privacy: The personal information of users can be used for, illegal activities. Information like the e-mail address, name, location and age, can be used to commit online crimes., Addiction: Addiction to these sites wastes our valuable time. It will negatively, affect our mental states and may lead to depression and tension. It can reduce, the productivity of workers in an organisation. Students may lose concentration, and this in turn may affect their studies., Spread rumours: Social media will spread the news very quickly. It can facilitate, or worsen a crisis by spreading negative information or misinformation at an, incredible speed., , d. Social media interaction – Best practices, •, •, •, , •, , Avoid unnecessary uploading of personal data like e-mail address, telephone, number, address, pictures and videos., Setting time schedule for using these sites can save wastage of time., In social media websites like wikis and blogs, photo and video sharing are, public. What you contribute is available for all to see. Be aware of what you, post online. Avoid posting content you may regret later., Set your privacy levels in such a way that you know exactly who can see your, posts and who can share them.The three basic privacy levels in social media, are private, friends and public., •, Let us do, , •, •, , 362, , Prepare a chart on the different social networking websites and, their uses., Create a blog of your class and update the activities like, achievements in sports, arts, class tests, assignments, etc., Conduct a survey in your school to find the most popular Internet, browser. Also prepare a chart based on the collected data.
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12. Internet and Mobile Computing, , Check yourself, 1., 2., 3., 4., 5., 6., , Give an example for an e-mail address., Which of the following is not a search engine?, (a) Google, (b) Bing, (c) Facebook (d) Ask, Name the protocol used for e-mail transmission across Internet., What is a blog?, Name two services over Internet., Each document on the web is referred using ____., , 12.5 Cyber security, Today, we know that people use Internet to transfer personal and confidential, information or make payments, organisations like banks perform all their financial, transactions using their computer network, railways do business – selling tickets,, information on running trains, etc. using the railway’s computer network. Can you, imagine the volume of financial loss and other issues that may occur if these, computer networks are not available, even for a short time?, Security to computer networks is vital because important data can be lost and privacy, can be violated. Further, work or business can be interrupted for several hours or, even days if a network comes under attack. With the arrival of the Internet, security, has become a major concern as people started using Internet as a tool for, communication and doing business. Every organisation should monitor its network, for possible intrusion and other attacks. Here we discuss the common threats that, affect a computer network., , 12.5.1 Computer virus, A computer virus is a program that attaches itself to another program or file enabling, it to spread from one computer to another without our knowledge and interferes, with the normal operation of a computer. A virus might corrupt or delete data on, our computer, replicate itself and spread to other computers or even erase everything, on the hard disk. Almost all viruses are attached to executable files. A virus may, exist on a computer, but it cannot infect the computer unless this malicious program, is run or opened. Viruses spread when the file they are attached to, is transferred, from one computer to another using a portable storage media (USB drives, portable, hard disks, etc.), file sharing, or through e-mail attachments.Viruses have become a, huge problem on the Internet and have caused damage worth billions., , 363
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12.5.2 Worm, A computer worm is a stand alone malware (malicious software) program that, replicates itself in order to spread to other computers. Worms spread from, computer to computer on its own. Unlike a virus, it does not need to attach itself, to a program to propagate. A worm takes advantage of the data transport features, of the computer system to travel without help. Worms always slow data traffic on, the network by consuming bandwidth, whereas viruses almost always corrupt or, modify files on a computer. The most destructive effect that a worm can cause is, through e-mails. A worm can send a copy of itself to every address in an e-mail, address book. Then, the worm sends itself to everyone listed in each of the receiver’s, address book and so on., I LOVE YOU worm, This worm affected computers in 2000 by overwriting most of, the files. Users received this worm as an e-mail with a subject, line “ILOVEYOU” and with a file attachment LOVE-LETTER-FORYOU.TXT.vbs. Those who clicked the attachment got their computers, affected by the worm and lost their files., , 12.5.3 Trojan horse, A Trojan horse, will appear to be a useful software but will actually do damage, once installed or run on the computer. Users are typically tricked into loading and, executing it on their systems. When a Trojan is activated on a computer, they can, cause serious damage by deleting files and destroying information on the system., Some Trojans create a backdoor on the computer. This gives malicious users access, to confidential or personal information in the computer through the network. Unlike, viruses and worms, Trojans do not reproduce by infecting files nor do they selfreplicate., Ie0199.exe Trojan, E-mail users received a message that offered a free upgrade to, Internet Explorer that contained an executable file Ie0199.exe, as attachment. This e-mail instructed the user to download and install this, program for the upgrade. The users who followed these instructions got their, files infected., , 364
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12. Internet and Mobile Computing, , Trojan War, In Greek mythology, the Trojan War was, waged against the city of Troy by the, Greeks after Prince Paris of Troy stole, away the Greek Queen Helen. The Greeks fought a, battle with the city of Troy for ten long years. The, Greek soldiers got fed up and wanted to return to their homes. Then, Athena,, the Goddess of war gave the Greeks an idea to end the war. According to, the plan, they built a big hollow wooden horse. The hollow horse was filled, with soldiers and they left it as a gift for the Trojans. All other soldiers, pretended to abandon their camp. Trojans thought that they had won the, war. They pulled the huge horse to their city. They started celebrations of, their victory. In the night when everyone was asleep, the Greek soldiers, opened the horse and came out. They killed the sleeping soldiers of Troy and, rescued Queen Helen., , 12.5.4 Spams, Spams or junk mails are unsolicited e-mails sent, indiscriminately to persons to promote a product, or service. Spammers collect e-mail addresses, from chat rooms, websites, customer lists,, newsgroups, etc. Clicking on links in spams may, send users to websites that host certain viruses., Today most e-mail service providers provide email filters that can successfully separate genuine, e-mail from spams as indicated in Figure 12.14., , Fig. 12.14 Collection of spams in the, e-mail menu, , 12.5.5 Hacking, In computer networking, hacking is a technical effort to manipulate the normal, behavior of network connections and connected systems. Hacking is performed, both by computer security experts and by computer criminals. Computer experts, perform hacking to test the security and find the vulnerabilities in computer networks, and computer systems. Such computer experts are often called ‘white hats’ and, such hacking is called ethical hacking., Computer criminals break into secure networks to destroy data or make the network, unusable for those who are authorised to use the network. They do this with the, intent of stealing confidential data or destroying files. Such criminals are called, ‘black hats’., 365
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There is another category of hackers called grey hat hackers, who fall between white, and black hackers. They sometimes act illegally, though with good intentions, to, identify the vulnerabilities. Grey hat hackers do this to achieve better security., , 12.5.6 Phishing, Phishing is a type of identity theft that occurs online. Phishing is an attempt to, acquire information such as usernames, passwords and credit card details by posing, as the original website, mostly that of banks and other financial institutions. Phishing, websites have URLs and home pages similar to their original ones. The act of creating, such a misleading website is called spoofing. People are persuaded to visit these, spoofed websites through e-mails. Users are tempted to type their usernames,, passwords, credit card numbers, etc. in these web pages and lose them to these, websites. These frauds use this information to steal money. Phishing is currently the, most widespread financial threat on the Internet. The URL in Figure 12.15 indicates, that it is a phishing website., , Fig. 12.15:A phishing website, , 12.5.7 Denial of Service (DoS) attack, A Denial of Service(DoS) attack is usually aimed at a web server. Such an attack, forces the server/computer to restart. An attack in which the attackers’ goal is to, shut down the target server rather than stealing data is called DoS attacks.This, prevents genuine users of a service/website on the web server from using that, service. This attack can be done using a single computer called Denial of Service, (DoS) attack or using more than one computer called Distributed Denial of Service, (DDoS) attack., 366
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12. Internet and Mobile Computing, , We have learned that when we type a, Attacker, website address in the browser and press, the Enter key, the browser requests for that, web page from the server. DoS attacks, Handler, Handler, sends large number of such requests to the, server until it collapses under the load and, stops functioning. A DoS attack using a, Zombies, computer on a network slows down the, network by flooding a server with a large, number of requests. A DDoS attack uses, multiple computers in the network that it, has previously infected. These infected, Victim, computers called ‘zombies’, work together, and send out large quantities of fake Fig. 12.16: Distributed Denial of Service, messages/requests to the target server., (DDoS) attacks, Figure 12.16 shows the Distributed Denial, of Service attack. This increases the amount of data traffic to the target server. This, leads to server overload and the server is unable to provide services to its users., The target computer is thus forced to reset / restart leading to unavailability of its, service for a period of time. A DoS attack interrupts network service for some, period, but it does not cause severe damage to files as in the case of a virus attack., , 12.5.8 Man-in-the-Middle attacks, A man-in-the-middle attack refers to an attack in which an attacker secretly intercepts, electronic messages between the sender and the receiver and then captures, inserts, and modifies messages during message transmission. If sender transmits messages, without appropriate security, the attacker may exploit the vulnerabilities in the, network to capture and modify the messages and send the modified messages to, the receiver. Since the network transmission still works properly, both the sender, and receiver will find it difficult to notice that the messages have been trapped or, modified by an intruder. If we use such a computer for online transactions, the man, in the middle may capture our bank account number and password to steal money,, leading to financial loss. Encrypted connections such as HTTPS (HTTP Secure),, SFTP (Secure FTP) etc. should be used for secure transactions, so that intruders, cannot modify the messages., 12.6 Preventing network attacks, Threats to computers and networks are a major issue as long as information is, accessible and transferred across the Internet. Different defense and detection, mechanisms are developed to deal with these attacks., 367
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12.6.1 Firewall, Home, network, , A firewall is a system of computer, hardware and software that provides, security to the computer network in an, organisation. A firewall controls the, incoming and outgoing network traffic by, analysing the data and determining, Fig. 12.17: Firewall, whether they should be allowed through, or not, based on a rule set. Firewalls deny malicious data from entering into the, computer networks as shown in Figure 12.17., Firewall, , Internet, , Sandboxing, Sandboxing is a technique through which programs that are, suspected to be infected with a virus can be run. Through, sandboxing such programs are run in a separate memory area and therefore, cannot damage our operating system., , 12.6.2 Anti-virus scanners, Viruses, worms and Trojan horses are all examples of malicious software (malware)., Antivirus tools are used to detect them and cure the infected system. Anti-virus, software scans files in the computer system for known viruses and removes them if, found. The anti-virus software uses virus definition files containing signatures (details), of viruses and other malware that are known. When an antivirus program scans a, file and notices that the file matches a known piece of malware, the antivirus program, stops the file from running, and puts it into ‘quarantine’. Quarantine is a special, area for storing files probably infected with viruses. These files can later be deleted, or the virus can be removed. For effective use of anti-virus software, virus, definitions must be updated regularly., , 12.6.3 Cookies, Cookies are small text files that are created when we use a browser to visit a website., Cookies keep track of our movements within the website – remembers our user, name, preferences, e-mail address, etc. Browsers store cookies for an interval of, time, usually in a cookie folder on the client’s computer. Cookies are text files and, so they are not executable programs. Websites use cookies mainly because they, save time and make browsing efficient., Cookies are treated as data and so it is not a virus, but it is always possible for a, hacker to use it for malicious purposes. Cookies can be used to act as a spyware., , 368
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12. Internet and Mobile Computing, , There are harmful cookies that are used by different websites to compromise our, privacy. Such websites store a special cookie in our computer that will keep track, of our activities like, websites visited, products purchased or the forms that are, filled. Most browsers provide facilities to manage/delete harmful cookies. Frequent, deletion of cookies helps to prevent illegal access and use of personal information., 12.7 Guidelines for using computers over Internet, , I, , I, , STOP, , think, , BEFORE, , BEFORE I, , I, DOWNLOAD, , click, , MY PASSWORD, MIXES, , LeTters, #umbers, AND, , $ymbol!#, , Following are the major guidelines for using computers over Internet., • Most of the computer viruses are spread through e-mail attachments. Do not, open any e-mail attachment that you are not sure about the sender., • Download files only from reputed sources. Do not use/copy software that, you cannot confirm the origin., • Avoid clicking on pop-up advertisements. Close them instead., • Use USB drives with caution. Plugging someone else’s USB storage into your, computer or plugging your own USB storage into a computer at an Internet, cafe/unsafe computer, can spread an infection through the USB storage., • Make sure the firewall is set and turned on., • Use strong passwords. Change passwords at regular intervals., • Update the virus definitions of your antivirus program periodically online., • Keep a regular backup of your important files (on DVD, another hard disk,, etc.), • Be careful about giving personal data online. If you see e-mail message requests, for personal data such as telephone number, address, credit card number, etc., from unknown persons, ignore it., 369
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Guidelines for setting up a strong password, •, •, , •, •, •, •, •, , •, , •, , •, , A password should have atleast 8 characters., A password should contain, • Upper case letters, • Lower case letters, • Numbers, • Symbols like @, #, $, etc., A password should not be personal information like name, date, of birth, etc. or common words., Never disclose your password to others., Do not write it on a paper or store it in a file in your computer., Do not use the same password for all logins., Change password often., , Visit banks’ websites by typing the URL into the address bar. Do not click on, links within e-mails to go to bank websites. Banks or any of its representatives, never sends you e-mail/SMS or phone calls to get your personal information,, usernames or password. Never reveal your passwords or ATM card details to, anyone., Check whether the website you are visiting is secure while performing financial, transactions. The web address in the address bar should start with ‘https://’., Also look for a lock icon on the browser’s address bar., Keep a regular check on your online accounts. Regularly login to your online, accounts, and check your statements. If you see any suspicious transaction,, report them to your bank or credit card provider., , Fig 12.18: Secure banking - lock icon and https, , 370
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12. Internet and Mobile Computing, , •, , Conduct a group discussion on the topic “security threats / cyber, attacks to your system”, and draw a bar diagram based on, information arrived in the event., , Let us do •, , List the names of various viruses and their features in the form of, a chart., , Check yourself, 1., 2., 3., 4., 5., , What is a virus?, What do you mean by phishing?, The small text files used by browsers to remember our email ids,, user names, etc. are known as ________., The act of breaking into secure networks to destroy data is called, _______ hacking., What is quarantine?, , 12.8 Mobile computing, The advances in computer technology have led to the development of more, computing power in small devices. Light weight computing devices with low power, consumption is now cheap and is common. Devices like laptops, tablets, smart, phones, etc. changed the lifestyle and work culture of people drastically. Today, people are able to connect to others, send and receive files or other information, anywhere anytime. This increased the computing demands day by day., Mobile computing is a technology that has computing capability and can transmit/, receive data while in motion. Mobile computing requires portable computing, devices like laptops, tablets, smart phones, etc., wireless communication networks, and connectivity to Internet. The demand for mobile computing started the growth, and development of mobile communication technology., 12.9 Mobile communication, The term ‘mobile’ has completely revolutionised communication by opening up, innovative ways for exchanging information. Today, mobile communication has, become the backbone of the society. Mobile system technologies have improved, the living standards. Mobile communication networks does not depend on any, physical connection to communicate between two devices., 371
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12.9.1 Generations in mobile communication, The mobile phone was introduced in the year 1946. In the initial stage, the growth, in mobile communication was very slow. With the increase in the number of users,, accommodating them within the limited available frequency spectrum became a, major problem. To solve this problem, the concept of cellular communication, was evolved.The cellular concept was developed in the 1960’s at Bell Laboratories., However, in the late 1990’s, when the Government of India offered spectrum licenses, for mobile communication, cellular technology became a common standard in, our country. The different generations in mobile communication are given below:, , a., , First Generation networks (1G), , 1G refers to the first-generation of wireless telephone technology (mobile, telecommunications) developed around 1980. 1G mobile phones were based on, the analog system and provided basic voice facility only., , b., , Second Generation networks (2G), , 2G networks follow digital system for communication. This improved the audio, quality in transmission. In 2G networks phone conversations are digitally, encrypted.These networks provided far greater mobile phone coverage. 2G, networks also introduced data services for mobile. Picture messages and MMS, (Multimedia Messaging Service) were introduced. The two popular standards, introduced by 2G systems are GSM and CDMA. A detailed discussion on the, GSM and CDMA standards are given below., i. Global System for Mobile (GSM), GSM is a globally accepted standard for digital cellular communication. GSM uses, narrowband TDMA (Time Division Multiple Access), which allows simultaneous, calls on the same radio frequency. It is a digital, circuit-switched network for voice, telephony. The frequency band for GSM is 900 MHz to 1800 MHz. GSM follows a, uniform international standard that made it possible to use a mobile device around, the world. The network is identified using the SIM (Subscriber Identity Module)., The users can select a handset of their choice. GSM is the most successful family of, cellular standards., 372
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12. Internet and Mobile Computing, GPRS and EDGE, , 2G network was expanded later to include improved data communication features, using GPRS (General Packet Radio Services) and EDGE (Enhanced Data rates, for GSM Evolution)., GPRS is a packet oriented mobile data service on GSM. When compared to, conventional GSM, users of GPRS benefitted from shorter access time and higher, data rates. GPRS allows billing based on volume of data transferred. Although, GPRS is a data only technology, it helps to improve GSM’s voice quality., EDGE is a digital mobile phone technology that allows improved data transmission, rates for GSM. EDGE is a superset to GPRS and can function on any network, with GPRS deployed on it. It provides nearly three times faster speeds than the, GPRS system. Both phone and network must support EDGE, otherwise the phone, will revert automatically to GPRS., ii. Code Division Multiple Access (CDMA), In CDMA or Code Division Multiple Access system, several transmitters can send, information simultaneously over a single communication channel. CDMA provides, wider coverage than GSM and provides better reception even in low signal strength, conditions. The voice quality in CDMA is better than GSM. It has a signal with, wider bandwidth and increased resistance to interference. CDMA technology, provides better security to the mobile network when compared to GSM., , c., , Third Generation networks (3G), , 3G wireless network technology provides high data transfer rates for handheld, devices. The high data transfer rates allows 3G networks to offer multimedia services, combining voice and data. 3G is also referred to as wireless broadband as it has the, facility to send and receive large amounts of data using a mobile phone. The access, part in 3G networks uses WCDMA (Wideband Code Division Multiple Access). It, requires upgrading the base stations (mobile towers) and mobile phones. Also the, base stations need to be close to each other., , d., , Fourth Generation networks (4G), , A 4G system, also called Long Term Evolution (L.T.E.), provides mobile ultrabroadband Internet access to mobile devices. 4G networks offer very high speeds, and provides excellent performance for bandwidth intensive applications such as, high quality streaming video. One of the key requirements for 4G is a wireless IPbased access system. The access part in 4G networks uses OFDMA (Orthogonal, Frequency Division Multiple Access). 4G provides good quality images and videos, than TV., 373
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12.9.2 Mobile communication services, Mobile communication industry uses a number of acronyms for the various, technologies that are being developed. Here we discuss a few popular mobile, communication technologies like SMS, MMS, GPS and smart cards., , a. Short Message Service (SMS), Short Message Service (SMS) is a text messaging service in mobile communication, systems that allows exchanging short text messages. SMS is the most widely used, data application by mobile phone users. The GSM standard allows to send a message, containing upto 160 characters. When a message is sent, it reaches a Short Message, Service Center (SMSC), which provides a ‘store and forward’ mechanism. SMSC, attempts to send messages to the recipients. If a recipient is not reachable, the, SMSC waits and then retries later. Some SMSC’s also provide a ‘forward and forget’, option where transmission is tried only once and if it fails, the message is not sent, again. SMS messages are exchanged using the protocol called SS7 (Signalling System, No # 7)., The First SMS, The first SMS message was sent on 3rdDecember 1992 from a, personal computer to a cellular phone on the Vodafone GSM, network in the UK.The content of the message was ‘Merry, Christmas’., , b. Multimedia Messaging Service (MMS), Multimedia Messaging Service (MMS) is a standard way to send and receive messages, that consists of multimedia content using mobile phones. It is an extension of the, capability of SMS to send text messages. Unlike SMS, MMS does not specify a, maximum size for a multimedia message. MMS supports contents such as text,, graphics, music, video clips and more. An MMS server is responsible for storing, and handling incoming and outgoing messages. Associated with the MMS server is, the MMS proxy relay, which is responsible for transferring messages between, different messaging systems., , c., , Global Positioning System (GPS), , The Global Positioning System (GPS) is a satellite based navigation system that is, used to locate a geographical position anywhere on earth, using its longitude and, latitude. GPS is designed and operated by the U.S. Department of Defence and it, consists of satellites, control and monitoring stations, and receivers., The basis of the GPS is a group of satellites that are continuously orbiting the, earth. These satellites transmit radio signals that contain their exact location, time,, 374
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12. Internet and Mobile Computing, , Global positioning satellite network, Cellular, Data, Network, , Internet, , GPS Tracking, Application, , Fig. 12.19: GPS fleet tracking, , and other information. The radio signals from the satellites, which are monitored, and corrected by control stations, are picked up by the GPS receiver. GPS receivers, take information transmitted from the satellites to calculate a user’s exact location, on earth. A GPS receiver needs only three satellites to plot a 2D position, which, will not be very accurate. Ideally, four or more satellites are needed to plot a 3D, position, which is much more accurate., GPS is used for vehicle fleet tracking by transporting companies to track the, movement of their trucks. Figure 12.19 depicts the working of a truck tracking, application using GPS. Vehicle navigation systems will direct the driver to his or, her destination through the best route. In commercial aviation GPS is used for, aircraft navigation. GPS is also used in oil exploration, farming, atmospheric studies,, etc. GPS receivers are now integrated in many mobile phones for implementing, various tracking applications., , d., , Smart cards, , Let us recollect about smart cards and smart card, readers that we discussed in Chapter 3. A smart card, is a plastic card embedded with a computer chip /, memory that stores and transacts data. The, advantages of using smart cards is that it is secure, (data is protected), intelligent (it can store and process, , Fig. 12.20: A model smart card, , 375
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data) and that it is convenient (it is easy to carry). That is why businesses and other, organisations use smart cards for authentication and storing data.A model of smart, card issued by Government of India for RSBY scheme is shown in Figure 12.20., In mobile communication the smart card technology is used in Subscriber Identity, Modules (SIM) for GSM phone systems (refer Figure 12.21). The smart card is, inserted or integrated into the mobile handset. The card stores personal subscriber, information and preferences. SIM cards help to identify, a subscriber, roam across networks and provide security, to value added services like Internet browsing, mobile, commerce, mobile banking, etc. Smart cards also work, as credit cards, ATM cards, fuel cards, authorisation, cards for television receiver, high-security identification, Fig. 12.21 GSM SIM card, cards, etc., 12.10 Mobile operating system, A mobile operating system is the operating system used in a mobile device (smart, phone, tablet, etc.), similar to an operating system used in a desktop or laptop, computer., , Fig. 12.22:Icons of popular mobile operating systems, , A mobile OS manages the hardware, multimedia functions, Internet connectivity,, etc. in a mobile device. It is the software platform on which other programs, called, application programs, are running. Popular mobile operating systems are Android, from Google, iOS from Apple, BlackBerry OS from BlackBerry and Windows, Phone from Microsoft., Android operating system, , Android is a Linux-based operating system designed mainly for touch screen mobile, devices such as smart phones and tablet computers. It was originally developed by, Android Inc. that was founded in Palo Alto, California in 2003 by Andy Rubin and, his friends. In 2005, Google acquired Android Inc. making it a wholly owned, subsidiary of Google. At Google, the team led by Rubin developed a mobile device, platform powered by the Linux kernel. In 2007, the Open Handset Alliance, a, consortium of several companies which include Google, HTC, Intel, Motorola,, 376
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12. Internet and Mobile Computing, , etc. was established with a goal to develop open standards for mobile devices., Android was released along with the formation of the Open Handset Alliance, (OHA)., The user interface of Android is based on touch inputs like swiping, tapping, pinching, and reverse pinching to manipulate on-screen objects. Android allows users to, customise their home screens with shortcuts to applications and widgets. Since its, launch in 2007, the Android operating system’s market share has been growing at a, fast pace to make it the most widely used mobile operating system today. Major, Android versions have been developed under a codename and released according, to alphabetical order. Table 12.2 shows the Android version names., The Android OS consists of a kernel, based on Linux kernel. Android uses, Linux kernel as it has a powerful, memory and process management, system, permissions-based security, structure and open source nature. An, Application Framework for, developers to build applications using, the Android Software Development, Kit is available in Android., Applications like Google Maps,, Facebook, etc.that run on Android are, built using this., , Version, , Code name, , 4.4, 4.1, 4.0.3, 3.1, 2.3, 2.2, 2.0, 1.6, 1.5, , KitKat, Jelly Bean, Ice Cream Sandwich, Honeycomb, Gingerbread, Froyo, Eclair, Donut, Cupcake, , Table 12.2: Android version names, , The Android code is released under the Apache License. Apache licensing allows, the software to be freely modified and distributed by device manufacturers and, developers. Android has a large community of developers writing applications, called ‘apps’ that enhance the functionality of devices. Apps are written using a, customised version of the Java programming language., Android’s acceptance is due to factors like it’s open source nature. This makes it, easy for developers to make programs/applications for Android OS called Android, apps. Most of these apps are available for free download from the Android Play, Store. It adds the popularity of this OS., With remarkable advances in mobile hardware and software, these trimmed-down, operating systems may be heading in a direction that could replace a desktop OS. It, is also likely that mobile OS could be further developed to be included in electronic, devices like televisions, washing machines, watches, etc., , 377
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•, , Prepare a chart displaying the different mobile operating systems, available in the market and their features., , Let us do, , Check yourself, 1., , 2., 3., 4., 5., , SIM is, (a) Subscriber Identity Module, (b) Subscriber Identity Mobile, (c) Subscription Identification Module, (d) Subscription Identification Mobile, What is a GPS?, The protocol used to send SMS messages is ______., How can multimedia content be sent using mobile phones?, What are the functions of a mobile operating system?, , Let us sum up, The Internet, which was started as a defence project of the US government, has become a part of our life. Today the Internet is accessed using mobile, devices like mobile phones, tablets, etc. than using a desktop computer., Therefore speed of Internet access has become an important factor. New, technologies connect to Internet focus on data transmission speed. Internet, services like e-mail, social media, searching etc. have changed the way we, communicate. Each of the above services has its own benefits and risks., Computer networks today play an important role in providing the above, services. It has increased the risk factors for networks, like viruses, worms,, Trojan horse, phishing, etc. Antivirus software, firewalls, etc. are used to, protect computer networks from different kinds of attacks. The risks for a, network attack can be reduced by following certain guidelines while using, computers on Internet., The convergence of a mobile phone and a computer has shifted the focus, from desktops to mobile computing devices. These devices are always, connected to the Internet and therefore mobile communication technology, , 378
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12. Internet and Mobile Computing, , has gained importance. The mobile communication technology has evolved, through generations from 1G to 4G, the prime focus being speed. This also, has led to the development of features like SMS, MMS, GPS, etc. Android is, one of the popular mobile operating systems, developed by Google based on, Linux kernel. The advances in the development of this OS is in such a way that, it will soon replace desktop operating systems and could be used in devices, like television, washing machines, etc., , Learning outcomes, After the completion of this chapter the learner will be able to, recognise the people behind the evolution of Internet., identify the hardware and software requirements for Internet connection., use the services available on Internet., classify the different types of social media., judge the risks while interacting with social media., recognise the threats to network security., identify the various mobile computing terminologies., recognise the features of mobile operating systems., discover the features of Android operating system., , l, l, l, l, l, l, l, l, l, , Sample questions, , 123456789012345678901234567890121234567890123456789012345678901212345678, 123456789012345678901234567890121234567890123456789012345678901212345678, 123456789012345678901234567890121234567890123456789012345678901212345678, 123456789012345678901234567890121234567890123456789012345678901212345678, 123456789012345678901234567890121234567890123456789012345678901212345678, 123456789012345678901234567890121234567890123456789012345678901212345678, , Very short answer type, 1., 2., 3., 4., 5., 6., 7., , Why is the invention of HTTP and HTML considered an important land mark, in the expansion of Internet?, Compare intranet and extranet., Write short notes on, a., Mobile broadband, b. Wi-MAX, Explain the terms web browser and web browsing., Compare blogs and microblogs., What are wikis?, What is firewall?, , 379
Page 36 : Short answer type, 1., , Your neighbour Ravi purchased a new PC for his personal use. Mention the, components required to connect this PC to Internet., 2. What are the advantages of using broadband connection over a dial-up, connection?, 3. XYZ engineering college has advertised that its campus is Wi-Fi enabled. What, is Wi-Fi? How is the Wi-Fi facility implemented in the campus?, 4. Madhu needs to prepare a presentation. For this, he uses www.google.com to, search for information. How does google display information when he types, ‘Phishing’ in the search box and clicks search button?, 5. Manoj’s e-mail id is
[email protected]. He sends an email to Joseph whose, e-mail id is
[email protected]. How is the mail sent from Manoj’s computer, to Joseph’s computer?, 6. How does a Trojan horse affect a computer?, 7. Explain a few threats that affect a computer network., 8. Compare GSM and CDMA standards., 9. Write short notes on SMS., 10. What is a smart card? How is it useful?, , Long answer type, 1., , 2., 3., 4., , 380, , Suppose you wish to visit the website of kerala school kalolsavam,, www.schoolkalolsavam.in and you have entered the URL in the address bar., Write the steps that follow until the home page is displayed., Write the disadvantages of social media. What are the different ways to avoid, the disadvantages of social media?, Explain the features of Android OS., Explain the various broadband technologies available for Internet access.
