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Introduction to Internet

This book is a part of the course by Jaipur National University, Jaipur.This book contains the course content for Introduction to Internet.

JNU, PuneFirst Edition 2013

The content in the book is copyright of JNU. All rights reserved.No part of the content may in any form or by any electronic, mechanical, photocopying, recording, or any other means be reproduced, stored in a retrieval system or be broadcast or transmitted without the prior permission of the publisher.

JNU makes reasonable endeavours to ensure content is current and accurate. JNU reserves the right to alter the content whenever the need arises, and to vary it at any time without prior notice.

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Index

ContentI. ...................................................................... II

List of FiguresII. .......................................................... V

List of TablesIII. ..........................................................VI

AbbreviationsIV. ...................................................... VII

Case StudyV. .............................................................. 102

BibliographyVI. ........................................................ 110

Self Assessment AnswersVII. ................................... 113

Book at a Glance

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Contents

Chapter I ....................................................................................................................................................... 1Overview of Internet .................................................................................................................................... 1Aim ................................................................................................................................................................ 1Objectives ...................................................................................................................................................... 1Learning outcome .......................................................................................................................................... 11.1 Introduction to Internet ............................................................................................................................ 21.2 History of Internet .................................................................................................................................... 31.3 Internet Culture ........................................................................................................................................ 51.4 Internet Service Provider ......................................................................................................................... 61.5 Addresses ................................................................................................................................................. 6 1.5.1 Internet Addresses .................................................................................................................... 7 1.5.2 IP Address ................................................................................................................................ 7 1.5.3 Domain Name Server ............................................................................................................... 91.6 Internet Tools ..........................................................................................................................................111.7 Internet Applications .............................................................................................................................. 12Summary ..................................................................................................................................................... 15References ................................................................................................................................................... 15Recommended Reading ............................................................................................................................. 15Self Assessment ........................................................................................................................................... 16

Chapter II ................................................................................................................................................... 18Components of Internet Structure ........................................................................................................... 18Aim .............................................................................................................................................................. 18Objectives .................................................................................................................................................... 18Learning outcome ........................................................................................................................................ 182.1 Personal Computer ................................................................................................................................. 192.2 Communication Equipment of User ...................................................................................................... 20 2.2.1 Local Loop Carrier ................................................................................................................. 21 2.2.2 Location of ISP ...................................................................................................................... 22 2.2.3 Web Servers ........................................................................................................................... 22Summary ..................................................................................................................................................... 24References ................................................................................................................................................... 24Recommended Reading ............................................................................................................................ 24Self Assessment ........................................................................................................................................... 25

Chapter III .................................................................................................................................................. 27Electronic Mail and Features of Internet ................................................................................................ 27Aim .............................................................................................................................................................. 27Objectives .................................................................................................................................................... 27Learning outcome ........................................................................................................................................ 273.1 Introduction ............................................................................................................................................ 283.2 Message Components ............................................................................................................................ 283.3 Mailer Features ...................................................................................................................................... 293.4 E-mail Management ............................................................................................................................... 303.5 MIME Types .......................................................................................................................................... 333.6 Newsgroups ........................................................................................................................................... 333.7 Mailing Lists .......................................................................................................................................... 353.8 Chatting Rooms ..................................................................................................................................... 35Summary ..................................................................................................................................................... 37References ................................................................................................................................................... 37Recommended Reading ............................................................................................................................. 37Self Assessment ........................................................................................................................................... 38

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Chapter IV .................................................................................................................................................. 40World Wide Web ........................................................................................................................................ 40Aim .............................................................................................................................................................. 40Objectives .................................................................................................................................................... 40Learning outcome ........................................................................................................................................ 404.1 Introduction to WWW ........................................................................................................................... 414.2 Web Browser .......................................................................................................................................... 424.3 Searching WWW ................................................................................................................................... 45 4.3.1 Directories .............................................................................................................................. 45 4.3.2 Search Engines ....................................................................................................................... 46 4.3.3 Meta Search Engines ............................................................................................................. 46 4.3.4 Searching Strategies ............................................................................................................... 474.4 Browsing and Surfing ............................................................................................................................ 514.5 Web Page Installation ............................................................................................................................. 524.6 Plug-ins .................................................................................................................................................. 52Summary ..................................................................................................................................................... 54References ................................................................................................................................................... 54Recommended Reading ............................................................................................................................. 54Self Assessment ........................................................................................................................................... 55

Chapter V .................................................................................................................................................... 57Languages ................................................................................................................................................... 57Aim .............................................................................................................................................................. 57Objectives .................................................................................................................................................... 57Learning outcome ........................................................................................................................................ 575.1 HTML (Hyper Text Markup Language) ................................................................................................ 585.2 Dynamic HTML ..................................................................................................................................... 605.3 Java Script Language ............................................................................................................................. 615.4 XML (Extended Markup Language) ...................................................................................................... 655.5 VRML (Virtual Reality Modelling Language) ...................................................................................... 70Summary .................................................................................................................................................... 72References ................................................................................................................................................... 72Recommended Reference .......................................................................................................................... 72Self Assessment ........................................................................................................................................... 73

Chapter VI ................................................................................................................................................. 75Cookies ........................................................................................................................................................ 75Aim .............................................................................................................................................................. 75Objectives .................................................................................................................................................... 75Learning outcome ........................................................................................................................................ 756.1 Introduction to Cookies .......................................................................................................................... 766.2 Functions of Cookies ............................................................................................................................. 766.3 Types of Cookies .................................................................................................................................... 776.4 Benefits of Cookies ................................................................................................................................ 776.5 Managing Cookies ................................................................................................................................. 78Summary .................................................................................................................................................... 79References .................................................................................................................................................. 79Recommended Reading ............................................................................................................................. 79Self Assessment .......................................................................................................................................... 80

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Chapter VII ................................................................................................................................................ 82Internet Connectivity ................................................................................................................................. 82Aim .............................................................................................................................................................. 82Objectives .................................................................................................................................................... 82Learning outcome ........................................................................................................................................ 827.1 Dial-up Connection from PC ................................................................................................................. 837.2 Accessing Internet through Leased Line ................................................................................................ 857.3 Connecting to Internet through a Mobile Phone .................................................................................... 867.4 Connecting to Internet through Cable Network ..................................................................................... 86Summary .................................................................................................................................................... 88References ................................................................................................................................................... 88Recommended Reading ............................................................................................................................. 88Self Assessment ........................................................................................................................................... 89

Chapter VIII .............................................................................................................................................. 91Internet Security ........................................................................................................................................ 91Aim .............................................................................................................................................................. 91Objectives .................................................................................................................................................... 91Learning outcome ........................................................................................................................................ 918.1 Security and Internet .............................................................................................................................. 928.2 Password Protection ............................................................................................................................... 928.3 Computer Viruses ................................................................................................................................... 93 8.3.1 Avoiding Viruses .................................................................................................................... 948.4 Spyware .................................................................................................................................................. 948.5 Firewalls ................................................................................................................................................. 958.6 Proxy Servers ......................................................................................................................................... 96Summary .................................................................................................................................................... 99References ................................................................................................................................................... 99Recommended Reading ............................................................................................................................. 99Self Assessment ......................................................................................................................................... 100

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List of Figures

Fig. 1.1 Working of Internet ........................................................................................................................... 2Fig. 1.2 Addresses .......................................................................................................................................... 6Fig. 2.1 A computer system.......................................................................................................................... 19Fig. 2.2 Accessing internet from a stand alone computer at home .............................................................. 20Fig. 2.3 Accessing internet from a computer through a LAN ...................................................................... 21Fig. 2.4 User connecting to internet through wireless/cable network .......................................................... 21Fig. 2.5 Relationship between internet user and the Internet Service Provider ........................................... 22Fig. 2.6 Web servers ..................................................................................................................................... 23Fig. 3.1 Instance search in Microsoft Outlook ............................................................................................. 30Fig. 3.2 View tab using date, subject or sender and receiver ....................................................................... 30Fig. 3.3 The Arrange By: box in inbox ........................................................................................................ 31Fig. 3.4 The expanded Ribbon in Outlook 2010 replaces Outlook 2007 menu ........................................... 31Fig. 3.5 The Quick Steps feature in new Outlook ........................................................................................ 31Fig. 4.1 Address bar ..................................................................................................................................... 42Fig. 4.2 Cursor ............................................................................................................................................. 43Fig. 4.3 Selected text .................................................................................................................................... 43Fig. 4.4 Selecting any URL .......................................................................................................................... 44Fig. 4.5 Back button ..................................................................................................................................... 44Fig. 7.1 Dial-up icon .................................................................................................................................... 83Fig. 7.2 Connect to dialog box ..................................................................................................................... 84Fig. 7.3 Dialling process .............................................................................................................................. 84Fig. 7.4 Verification of username and password .......................................................................................... 84Fig. 7.5 Connected dialog box ..................................................................................................................... 85Fig. 7.6 Connecting to the Internet through leased line ............................................................................... 86Fig. 7.7 WAP device connecting to the web server ...................................................................................... 86Fig. 7.8 Connecting to the Internet through cable network ......................................................................... 87Fig. 8.1 Internet security .............................................................................................................................. 92Fig. 8.2 Account password ........................................................................................................................... 92Fig. 8.3 Types of viruses .............................................................................................................................. 93Fig. 8.4 Computer spyware .......................................................................................................................... 95Fig. 8.5 Firewall ........................................................................................................................................... 96Fig. 8.6 Proxy servers .................................................................................................................................. 97

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List of Tables

Table 1.1 Class A, B, C and CIDR networks ................................................................................................. 8Table 3.1 Message components ................................................................................................................... 29Table 3.2 Mailer features ............................................................................................................................. 29Table 5.1 JavaScript statements ................................................................................................................... 65

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Abbreviations

APIPA - Automatic Private IP AddressingARPANET - Advanced Research Projects Agency NetworkBCC - Blind Carbon CopyCAD - Computer-Aided DesignCC - Carbon CopyCERN - Centre for Particle ResearchCIDR - Classless Inter-Domain RoutingCSRG - Computer Science Research GroupDARPA - Advanced Research Projects AgencyDHCP - Dynamic Host Configuration ProtocolDNS - Domain Name SystemDOS - Disk Operating SystemDSL - Digital Subscriber LineDTD - Document Type Definition FAQ’s - Frequently Asked QuestionsFTP - File Transfer ProtocolHTML - Hyper Text Mark-up LanguageHTTP - Hypertext Transfer ProtocolIBM - International Business MachinesICANN - Internet Corporation for Assigned Names and NumbersIDF - Inverse Document FrequencyIETF - Internet Engineering Task Force IMAP - Internet Message Access Protocol IP - Internet Protocol IRC - Internet Relay ChatISDN - Integrated Services Digital NetworkLAN - Local Area NetworkMIDI - Musical Instrument Digital InterfaceNCSA - National Centre for Supercomputing ApplicationsNIC - Network Information CenterNIC - Network Interface CardNSF - National Science Foundation PDA - Personal Digital AssistantPOP - Post Office ProtocolPSTN - Public Switched Telephone NetworkRAM - Random Access MemorySCLML - Selena’s Client List Mark-up LanguageSGML - Standard Generalised Mark-up Language SMTP - Simple Mail Transfer Protocol TCP - Transmission Control ProtocolTF - Term FrequencyUCB - University of California at BerkeleyURL - Uniform Resource LocatorVRML - Virtual Reality Modelling LanguageWAIS - Wide Area Information SearchWAN - Wide Area NetworkWAP - Wireless Application ProtocolWML - Wireless Mark-up LanguageWWW - World Wide Web

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Chapter I

Overview of Internet

Aim

The aim of this chapter is to:

introduce the internet•

describe the history of internet•

highlight the internet culture•

Objectives

The objectives of this chapter are to:

elucidate the internet service provider•

explain addresses •

describe different internet tools•

Learning outcome

At the end of this chapter, you will be able to:

understand various internet applications•

comprehend domain server name•

discuss the internet address an• d IP address


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1.1 Introduction to InternetThe Internet is a global collection of personal computers which are linked together by cables and telephone lines makingcommunicationpossibleamongtheminacommonlanguage.However,therigidtechnologicaldefinitionofInternetisthatitisaglobalcollectionofinterconnectednetworks.Bydefinition,“anetworkcomputerusersharecomputer equipment and programs, messages, and the information available at one site”.

Internet basically tries to connect many LANs and WANs. There are many major networks connected within Internet. Some of them are ARPANET, NSFNET, NASA, BITNET, DECnets, etc. However, the basic networks on Internet are compounding.

Computernetworkbydefinitionallowssharingofresources.Sinceallsoftwareresourcesexistincomputersintheformofdatafiles;oneofthekeyaspectinnetworkofmanycomputersistomovedatabetweentwospecificcomputers. For such a communication, following things are required:

address of the destination•a safe mean of moving data in the form of electronic signals•

As far as safe movement of data is concerned, there exists a set of rules which governs the sending and receiving of data on the Internet. These rules are implemented in two parts in the network software and are called Transmission Control Protocol (TCP) and Internet Protocol (IP). These two are collectively called TCP/IP. For sending large block of text/data to another machine, TCP divides the data into little data packets. It also adds special information e.g. packet position, error correction code etc.

To make sure that packet at the destination can be reassembled correctly and without any damage to data. The role of IP is to put destination addressing information on such packets. On Internet it is not necessary that all the packets will follow the same path from source to destination. A special machine called routers tries to, load balance various paths that exist on networks.

Another special machine called gateways allows different electronic networks to talk to Internet which uses TCP/IP.

Submarine line Internet service provider

RouterAccess server

Satellite earth stationMicrowave relay station

Telephone line

E-mail softwareBrowser +

Modem +Desktop computer +

Internet user Server Cable modem

Cable line

Dedicated line

+ Telecommunication satellite

Fig. 1.1 Working of Internet(Source:http://visual.merriam-webster.com/images/communications/office-automation/internet_1.jpg)

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Addresses are essential for virtually everything you do on the Internet. The IP in TCP/IP is a mechanism for providing addresses for computers on the Internet. Internet addresses have two forms.

Person understandable which are expressed as words•Machine understandable which are expressed as numbers.•

The following can be a typical person understandable address on Internet:

username @ host.subdomain domain

The username in general is the name of the Internet account. This name is same as the one which you may use when logging in to the computer on which you have your Internet account. Logging in is the process of gaining access to your account on a computer which is shared by several users. Your Internet account is created on it.

Hosts are in general, individual machines at a particular location. Resources of a host machine is normal shared and can be utilised by any user on the Internet. Hosts and local networks are grouped together into domains, which then are grouped into one or more larger domains.

Domain may be an apartment complex, a town, or even a country. Sub-domains may correspond to organisations such as NASA or CompuServe such as India comes under a larger domain ‘-IN”.

Computers termed as name servers contain databases of Internet host addresses. They translate word addresses or person understandable into numeric equivalents.

1.2 History of InternetInternet has become a vital part of our life. It has brought the whole world together on a single platform. It has not only made information accessible but made our life very easy. Today, from personal mails to e-commerce, everything is possible on the Internet. And our web activity is growing day-by-day as the Internet provides us with immense opportunity to conduct business online in easier and faster way. The Internet as we know it today, traces its origin way back in late 1960s.

1969 - Birth of a networkIn 1969, the US Defence Department was working on a project for wartime digital communications. At that time the telephone system was about the only theatre-scale communications system in use. A major problem had been identifiedinitsdesign-itsdependenceonswitchingstationsthatcouldbetargetedduringanattack.Woulditbepossibletodesignanetworkthatcouldquicklyreroutedigitaltrafficaroundfailednodes?Apossiblesolutionhadbeenidentifiedintheory.Thatwastobuilda“web”ofdatagramnetwork,calleda“catenet”,andusedynamicroutingprotocols toconstantlyadjust theflowof trafficthroughthecatenet.TheDefenceAdvancedResearchProjectsAgency (DARPA) launched the DARPA Internet Program.

1970s - InfancyDARPA Internet, largely the plaything of academic and military researchers, spent more than a decade in relative obscurity. As Vietnam, Watergate, the Oil Crisis, and the Iranian Hostage Crisis rolled over the nation, several Internet research teams preceded through a gradual evolution of protocols. In 1975, DARPA declared the project a success and handed its management over to the Defence Communications Agency. Several of today’s key protocols (including IP and TCP) were stable by 1980, and adopted throughout ARPANET by 1983.

Mid 1980s - The research netAsmallcomputerwasaPDP-11/45,andaPDP-11/45doesnotfitonyourdesk.Somesiteshadahundredcomputersattached to the Internet. Most had a dozen or so, probably with something like a VAX doing most of the work - mail, news, EGP routing. Users did their work using DEC VT-100 terminals. FORTRAN was the word of the day. Few companies had Internet access, relying instead on SNA and IBM mainframes. Rather, the Internet community was dominated by universities and military research sites. It’s most popular service was the rapid email it made possible


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with distant colleagues. In August 1983, there were 562 registered ARPANET hosts (RFC 1296). UNIX deserves at leastanhonourablemention,sincealmostalltheinitialInternetprotocolsweredevelopedfirstforUNIX,largelydue to the availability of kernel source (for a price) and the relative ease of implementation (relative to things like VMS or MVS).

The University of California at Berkeley (UCB) deserves special mention, because their Computer Science •Research Group (CSRG) developed the BSD variants of AT&T’s UNIX operating system. BSD UNIX and its derivatives would become the most common Internet programming platform.Many key features of the Internet were already in place, including the IP and TCP protocols. ARPANET was •fundamentally unreliable in nature, as the Internet is still today. This principle of unreliable delivery means that the Internet only makes a best-effort attempt to deliver packets. Thenetworkcandropapacketwithoutanynotification tosenderor receiver.Remember, theInternetwas•designed for military survivability. The software running on either end must be prepared to recognise data loss, retransmitting data as often as necessary to achieve its ultimate delivery.

Late 1980s - The PC revolutionDriven largely by the development of the PC and LAN technology, subnetting was standardised in 1985 when RFC 950 wasreleased.LANtechnologymadetheideaofa“catenet”feasible-aninternetworkofnetworks.InterconnectingLANs with WANS was possible by subnetting.

The National Science Foundation (NSF), in 1986, started the Supercomputer Centres program. Until then, •supercomputers such as Crays were largely the playthings of large, well-funded universities and military research centres. NSF’s idea was to make supercomputer resources available to those of more modest means by constructingfivesupercomputercentresaroundthecountryandbuildinganetworklinkingthemwithpotentialusers. NSF decided to base their network on the Internet protocols, and NSFNET was born. For the next decade, NSFNET would be the core of the U.S. Internet, until its privatisation and ultimate retirement in 1995.Domain naming was stable by 1987 when RFC 1034 was released. Until then, hostnames were mapped to IP •address using static tables, but the Internet’s exponential growth had made this practice infeasible.In the late 1980s, important advances related to poor network performance with poor TCP performance, and a •string of papers by the likes of Nagle and Van Jacobson (RFC 896, RFC 1072, RFC 1144, RFC 1323) presented key insights into TCP performance.The 1987 Internet Worm was the largest security failure in the history of the Internet. More information can be •found in RFC 1135. All things considered, it could happen again.

Early 1990s - Address exhaustion and the WebIntheearly90s,thefirstaddressexhaustioncrisishittheInternettechnicalcommunity.Thepresentsolution,CIDR,willsustaintheInternetforafewmoreyearsbymakingmoreefficientuseofIP’sexisting32-bitaddressspace.Fora more lasting solution, IETF is looking at IPv6 and its 128-bit address space, but CIDR is here to stay.

Crisis aside, the World Wide Web (WWW) has been one of Internet’s most exciting recent developments. The idea of hypertext has been around for more than a decade, but in 1989 a team at the European Centre for Particle Research (CERN) in Switzerland developed a set of protocols for transferring hypertext via the Internet. In the early 1990s it was enhanced by a team at the National Centre for Supercomputing Applications (NCSA) at the University of Illinois - one of NSF’s supercomputer centres. The result was NCSA Mosaic, a graphical, point-and-click hypertext browserthatmadeInterneteasy.Theresultingexplosionin“Websites”drovetheInternetintothepubliceye.

Mid 1990s - The new InternetThe Internet’s technical progress in the 1990s has been its sociological progress. It has already become part of the national vocabulary, and seems headed for even greater prominence. It has been accepted by the business community, with a resulting explosion of service providers, consultants, books, and TV coverage. It has given birth to the Free Software Movement.

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The Free Software Movement owes much to bulletin board systems, but really came into its own on the Internet, due to a combination of forces. The public nature of the Internet’s early funding ensured that much of its networking software was non-proprietary. The emergence of anonymous FTP sites provided a distribution mechanism that almost anyone could use. Network newsgroups and mailing lists offered an open communication medium. Last but not the least were individualists like Richard Stallman, who wrote EMACS, launched the GNU Project and founded the Free Software Foundation. In the 1990s, Linus Torvalds wrote Linux, the popular (and free) UNIX clone operating system.

\begin{soapbox}The explosion of capitalist conservatism, combined with a growing awareness of Internet’s business value, has led to major changes in the Internet community. Many of them have not been for the good.

First, there seems to be a growing departure from Internet’s history of open protocols, published as RFCs. Many •new protocols are being developed in an increasingly proprietary manner. IGRP, a trademark of Cisco Systems, has the dubious distinction as the most successful proprietary Internet routing protocol, capable only of operation between Cisco routers. Other protocols, such as BGP, are published as RFCs, but with important operational detailsomitted.Thenotoriouslymis-namedOpenSoftwareFoundationhasintroducedawholesuiteof“open”protocolswhosespecificationsareavailable-foraprice-andnotonthenet.People forget that businesses have tried to run digital communications networks in the past. IBM and DEC both •developed proprietary networking schemes that only ran on their hardware. Several information providers did very well for themselves in the 80s, including LEXIS/NEXIS, Dialog, and Dow Jones. Public data networks were constructed by companies like Tymnet and run into every major US city. CompuServe and others built large bulletin board-like systems. Many of these services still offer a quality and depth of coverage unparalleled on the Internet (examine Dialog •if you are sceptical of this claim). But none of them offered nudie GIFs that anyone could download. None of them let you read through the RFCs and then write a Perl script to tweak the one little thing you needed to adjust. None of them gave birth to a Free Software Movement. None of them caught people’s imagination.The very existence of the Free Software Movement is part of the Internet saga, because free software would not •existwithoutthenet.“Movements”tendtoarisewhenprogressoffersusnewfreedomsandwefindnewwaystoexplore and, sometimes, to exploit them. The Free Software Movement has offered what would be unimaginable when the Internet was formed - games, editors, windowing systems, compilers, networking software, and even entire operating systems available for anyone who wants them, without licensing fees, with complete source code, and all you need is Internet access. It also offers challenges, forcing us to ask what changes are needed in our society to support these new freedoms •that have touched so many people. And it offers chances at exploitation, from the businesses using free software development platforms for commercial code, to the Internet Worm and the security risks of open systems.People wonder whether progress is better served through government funding or private industry. The Internet •defies thepopularwisdomof “business is better”.Bothbusiness andgovernment tried tobuild largedatacommunicationnetworksinthe1980s.Businessdependedongoodmarketdecisions;thegovernmentresearchersbasedtheirsystemonopenness,imaginationandfreedom.Businessfailed;Internetsucceeded.Ourrewardhasbeen its commercialisation.

1.3 Internet CultureThewholeworldhasasinglecultureforthefirsttimeever,whichisInternet.SomepeoplewouldcharacterisetheInternet as a subculture. This is true on the local, regional, and national levels where only a percentage or sometimes only a tiny minority of the population use the Internet. However, all of these subcultures are intertwined to form their own superculture that expands the entire world. The current phenomenon over Internet shows, there will be more people using the Internet.

Many people in the world are directly or indirectly affected by the internet. On the Internet, there are people who •take part in the internet culture by contributing information, data, pictures, and videos that have direct interests and/or indirect consequences for each and every person.


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AnotherexampleofthefirstworldcultureisthatmorepeoplewanttolearntheEnglishlanguage,because•English is the most common language on the Internet and people want to better comprehend the information of the Internet. As a result, more people now understand English than ever before. Anyone can read information on internet by translating from English to whichever language he knows. This helps to gain knowledge of different cultures and traditions and can learn anything by sitting in any part of the world. Not only is the Internet the culture of the world, but this culture is growing faster than any previous culture. •ThisInternetcultureissolargeanddiversethatyoucanfindanythingontheInternet.As a result, the Internet is crossing the records of different cultures throughout the world, where information and •ideas can be shared with almost anyone in the world and morphed into something new almost instantaneously. ThatiswhytheInternetisthefirstworldwideculture.

1.4 Internet Service ProviderAn Internet Service Provider (ISP) is an organisation that provides Internet accounts, whether dial-in, DSL, ISDN, cable, satellite, or wireless. In addition to connecting you to the Internet, here are some other features that your Internet account provides:

E-mail mailboxes:• Your account almost certainly comes with at least one e-mail mailbox on a POP or IMAP server. Many ISPs provide more than one mailbox, so that each member of your family can read his or her mail separately, either as part of the cost of the account or for an extra fee.Web server space• : Most Internet accounts include a modest amount of disk space on a web server, so that you can make your own web pages accessible to the Internet. If you need more space, you can usually buy more for a small monthly fee.Domain hosting: • If you want your own domain name, most ISPs can host your domain, so that e-mail to the domain lands in your mailbox, and web addresses in your domain refer to pages that you store on your ISP’s web server.

1.5 AddressesInternet is a global network of computers. Each computer connected to the Internet must have a unique address. Internet addresses are in the form 000.000.000.000 where 000 must be a number from 0 - 255. This address is called an IP (Internet Protocol) address.

ThefollowingfigureshowstwocomputersconnectedtotheInternetwhereonecomputerhasIPaddressas1.2.3.4and another computer with IP address 5.6.7.8.

Your computer 1.2.3.4

Another computer 5.6.7.8

Internet

Fig. 1.2 Addresses(Source: http://www.theshulers.com/whitepapers/internet_whitepaper/index.html)

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After connecting to the Internet via Internet Service Provider (ISP), a temporary IP address for the duration of your dial-in session is usually assigned. However, you might have a permanent IP address or it might obtain a temporary onefromaDHCP(DynamicHostConfigurationProtocol)serverwhenyouconnecttotheInternetusingalocalarea network (LAN). In any case, if you are connected to the Internet, your computer has a unique IP address.

1.5.1 Internet AddressesIt is necessary to understand internet addresses for sending emails or to do anything using the Internet. For delivering data or mails from computer to computer, the Internet Protocol (IP) uses internet address information. IP address on internet is a series of four numbers, which is separated by periods or dots. The IP address sometimes changes. Itisdifficulttorememberthisnumericaddresswhenyouneedtocontactsomeone.Thiswouldnotbepossibletoremind so many numeric addresses at one time along with the changed one.

In the early 1980s, Sun Microsoft developed the Domain Name System (DNS) for keeping a track of the IP •addresses. Since then this has been the addressing system on the internet. The DNS establishes a hierarchy of domains, which are groups of computers on the internet. The DNS gives each computer on the net an internet address or domain name by using easily recognisable letters and words instead of numbers. The domains at the top level of the hierarchy maintain lists and addresses of the domains just beneath them. Those subordinate domains have similar responsibilities for the domains just beneath them, and so on. In this way, every computer on the net gets an internet address. The DNS also helps internet address into its IP numeric equivalent. Aninternetaddressismadeupoftwomajorpartsseparatedbyan@(at)sign.Thefirstpartoftheaddress,to•the left of the @ sign, is the user name, which usually refers to the person who holds the internet account and is often that person’s login name. The second part of the address, to the right of the @ sign, is the host or the domainname,whichidentifiesthespecificcomputerwherethepersonhasaninternetemailaccount.Iftheemailaccountislocatedattheperson’swork,thishostordomainnamemayreflectthenameofthecompany.Otherwise, itwillprobablyreflectwherethepersonhasaninternetaccount,eitherwithaninternetserviceprovider (ISP) or online service. Therightmostpositionofthedomainsectionoftheaddressidentifiesthelargestdomainandkindoforganisation•where the person has his or her address. Common domains in the United States are .com for commercial, .edu for education, .gov for government, .mil for military, .net for network and .org for organisation. A variety of plans have been proposed for seven or more domains to be added, such as .web for Web. Outside the US, only two letters are used to identify the domains, such as .au for Australia, .ca for Canada, .uk for United Kingdom and .in for India.

1.5.2 IP AddressInternet Protocol Address (or IP Address) is a unique address that computing devices use to identify itself and communicate with other devices in the Internet Protocol network. Any device connected to the IP network must have a unique IP address within its network. An IP address is analogous to a street address or telephone number in thatitisusedtouniquelyidentifyanetworkdevicetodelivermailmessage,orcall(“view”)awebsite.

Dotted decimalsThetraditionalIPAddresses(IPv4)usesa32-bitnumbertorepresentanIPaddress,anditdefinesbothnetworkand host address. Due to IPv4 addresses running out, a new version of the IP protocol (IPv6) has been invented to offervirtuallylimitlessnumberofuniqueaddresses.AnIPaddressiswrittenin“dotteddecimal”notation,whichis 4 sets of numbers separated by period each set representing 8-bit number ranging from (0-255). An example of IPv4 address is 216.3.128.12, which is the IP address assigned to topwebhosts.org.

An IPv4 address is divided into two parts: network and host address. The network address determines how many of the 32 bits are used for the network address, and remaining bits for the host address. The host address can be further divided into subnet work and host number.


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Class A, B, C and CIDR networksTraditionallyIPnetworkisclassifiedasA,BorCnetwork.Thecomputersidentifiedtheclassbythefirst3bits(A=000,B=100,C=110),whilehumansidentifytheclassbyfirstoctet(8-bit)number.WithscarcityofIPaddresses,theclass-basedsystemhasbeenreplacedbyClasslessInter-DomainRouting(CIDR)tomoreefficientlyallocateIP addresses.

Class Network Address Number of Hosts Netmask

CIDR /4 240435456 240.0.0.0

CIDR /5 13217728 248.0.0.0

CIDR /6 67108860 252.0.0.0

CIDR /7 33554432 254.0.0.0

A /8 (1-126) 16777216 255.0.0.0

CIDR /9 8388608 255.128.0.0

CIDR /10 4194304 255.192.0.0

CIDR /11 2097152 255.224.0.0

CIDR /12 1048576 255.240.0.0

CIDR /13 524288 255.248.0.0

CIDR /14 262144 255.252.0.0

CIDR /15 131072 255.254.0.0

B /16 (128-191) 65534 255.255.0.0

CIDR /17 32768 255.255.128.0

CIDR /18 16384 255.255.192.0

CIDR /19 8192 255.255.224.0

CIDR /20 4096 255.255.240.0

CIDR /21 2048 255.255.248.0

CIDR /22 1024 255.255.252.0

CIDR /23 512 255.255.254.0

C /24 (192-223) 256 255.255.255.0

CIDR /25 128 255.255.255.128

CIDR /26 64 255.255.255.192

CIDR /27 32 255.255.255.224

CIDR /28 16 255.255.255.240

CIDR /29 8 255.255.255.248

CIDR /30 4 255.255.255.252

Table 1.1 Class A, B, C and CIDR networks(Source: http://www.topwebhosts.org/tools/ip-address.php)

Note: (1) 127 Network Address reserved for loopback test. (2) Class D (224-247, Multicast) and Class E (248-255, Experimental) are not intended to be used in public operation.

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Public and private IP addresses In order to maintain uniqueness within global namespace, the IP addresses are publicly registered with the Network InformationCenter(NIC)toavoidaddressconflicts.Devicesthatneedtobepubliclyidentifiedsuchaswebormail servers must have a globally unique IP address, and they are assigned a public IP address. Devices that do not requirepublicaccessmaybeassignedaprivateIPaddress,andmakeituniquelyidentifiablewithinoneorganisation.For example, a network printer may be assigned a private IP address to prevent the world from printing from it. To allow organisations to freely assign private IP addresses, the NIC has reserved certain address blocks for private use. A private network is a network that uses RFC 1918 IP address space. The following IP blocks are reserved for private IP addresses.

Class Starting IP Address Ending IP Address

A 10.0.0.0 10.255.255.255

B 172.16.0.0 172.31.255.255

C 192.168.0.0 192.168.255.255

In addition to above classful private addresses, 169.254.0.0 through 169.254.255.255 addresses are reserved for Zeroconf (or APIPA, Automatic Private IP Addressing) to automatically create the usable IP network without configuration.

What is loopback IP address? The loopback IP address is the address used to access itself. The IPv4 designated 127.0.0.1 as the loopback address with the 255.0.0.0 subnet mask. A loopback interface is also known as a virtual IP, which does not associate with hardware interface. On Linux systems, the loopback interface is commonly called lo or lo0. The corresponding hostname for this interface is called localhost.

The loopback address is used to test network software without physically installing a Network Interface Card (NIC), and without having to physically connect the machine to a TCP/IP network. A good example of this is to access the web server running on itself by using http://127.0.0.1 or http://localhost.

1.5.3 Domain Name ServerDNS is a hierarchical system. DNS organises all registered names in a tree structure. At the base or root of the tree are a group of top-level domains including familiar names like com, org, and edu and numerous country-level domains likefi(Finland),ca(Canada),andmy(Malaysia).Onegenerallycannotpurchasenamesatthislevel.However,ina well-publicised and controversial event in 2000, the island nation of Tuvalu agreed to receive a large payment in return for rights to the root domain tv.

Below this level are the second-level registered domains such as about.com. These are domains that organisations can purchase from any of numerous accredited registrars. For nodes in the com, org, and edu domains, the Internet Corporation for Assigned Names and Numbers (ICANN) oversees registrations.

Belowthat,localdomainslikecompnetworking.about.comaredefinedandadministeredbytheoveralldomainowner.DNS supports additional tree levels as well. The period (‘.’) always separates each level of the hierarchy in DNS.

DNS root level and other serversDNS is also a distributed system. The DNS database contains a list of registered domain names. It further contains a mapping or conversion between each name and one or more IP addresses. However, DNS requires a coordinated effortamongmanycomputers(servers);noonecomputerholdstheentireDNSdatabase.EachDNSservermaintainsjust one piece of the overall hierarchy - one level of the tree and then only a subset or zone within that level.


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The top level of the DNS hierarchy, also called the root level, is maintained by a set of 13 servers called root name servers. These servers have gained some notoriety for their unique role on the Internet. Maintained by various independent agencies, the servers are uniquely named A, B, C and so on up to M. Ten of these servers reside in the United States, one in Japan, one in London, and one in Stockholm, Sweden.

DNS resolversDNS works in a client/server fashion. DNS servers respond to requests from DNS clients called resolvers. ISPs and other organisations set up local DNS resolvers as well as servers. Most DNS servers also act as resolvers, routing requests up the tree to higher-level DNS servers, and also delegating requests to other servers. DNS servers eventually return the requested mapping (either address-to-name or name-to-address) to the resolver.

DNS and DHCPDNS was not designed to work with dynamic addressing such as that supported by DHCP. DNS requires that fixed(static)addressesbemaintainedinthedatabase.WebserversinparticularrequirefixedIPaddressesforthisreason.

DNS server hierarchyThe DNS is a distributed system, meaning that only the 13 root servers contain the complete database of domain names and IP addresses. All other DNS servers are installed at lower levels of the hierarchy and maintain only certain pieces of the overall database.

Lower level DNS servers are owned by businesses or Internet Service Providers (ISPs). For example, Google •maintains various DNS servers around the world that manage the google.com, google.co.uk, and other domains. Your ISP also maintains DNS servers as part of your Internet connection setup.DNS networking is based on the client / server architecture. Your Web browser functions as a DNS client (also •called DNS resolver) and issues requests to your Internet provider’s DNS servers when navigating between Web sites.When a DNS server receives a request not in its database (such as a geographically far away or rarely visited •Web site), it temporarily transforms from a server to a DNS client. The server automatically passes that request to another DNS server or up to the next higher level in the DNS hierarchy as needed. Eventually the request arrives at a server that has the matching name and IP address in its database (all the way to the root level if necessary),andtheresponseflowsbackthroughthechainofDNSserverstoyourclient.

DNS servers and home networkingComputers on your home network locate a DNS server through the Internet connection setup properties. Providers givetheircustomersthepublicIPaddress(es)ofprimaryandbackupDNSservers.YoucanfindthecurrentIPaddressesofyourDNSserverconfigurationviaseveralmethods:

ontheconfigurationscreensofahomenetworkrouter•ontheTCP/IPconnectionpropertiesscreensinWindowsControlPanel(ifconfiguredviathatmethod)•fromipconfigorsimilarcommandlineutility•

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1.6 Internet ToolsInternet can and does provide a host of other services apart from the normal data transfer. These services include Chat, E-mail, News groups and Gopher.

ChatChatting refers to the interaction between two or more people through the Internet, as if they were talking to each other.

E-mailE-mailing refers to the process of one person sending a message to another user through the Internet and the other user reading it when he wants to rather than as it is sent. E-mail (electronic mail) is the exchange of computer-stored messagesbytelecommunication.(Somepeoplespellitemail;wepreferthecurrentlymoreestablishedspellingofe-mail).However,youcanalsosendnon-texttiles,suchasgraphicimagesandsoundfiles,asattachmentssentinbinarystreams.E-mailwasoneofthefirstusesoftheInternetandisstillthemostpopularuse.AlargepercentageofthetotaltrafficovertheInternetise-mail.E-mailcanbedistributedtolistsofpeopleaswellastoindividuals.It has three main parts:

Header: An e-mail heading has following parts.•To : Which contains recipient’s Address �CC : The Carbon Copy �Subject : Subject of Email �

Message body: This is the place where the actual text of the email is written.•Signature:Ituniquelyidentifiesthesender.Thedetails,whichcanbepartofit,areSendersName,Phone-Fax•No., Address etc.

News groupsNews groups refer to the specialised group of people who regularly remain in contact with each other through the above-mentioned methods for the purpose of discussions on a specialised topic. For instance, there could be a newsgroup of people who enjoy gardening, like to know about extra-terrestrial beings etc.

GopherIt is a search tool that helps to look for information on the Internet on any subject what so ever.

World Wide Web (WWW)World Wide Web (WWW) is the collection of web pages available on the Internet.

Uniform Resource Locator (URL)It stands for Uniform Resource Locator. Every web page on the Internet has a unique address known as the Uniform Resource Locator. For locating any document on World Wide Web, you must know its Uniform Resource Locator (URL).

Web browserWeb browser is application software that allows us to view web pages. Windows provides us with a browser known as the Internet Explorer. You could have other browsers as well from elsewhere like Netscape Navigator.


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1.7 Internet ApplicationsThe Internet is the largest, most vast, most complex but unorganised learning source in the world. Through the Internetonecanfindknowledgeresourcesthatallowonetostudyvirtuallyanydisciplineimaginable.

The use of Internet services over the Internet has greatly speeded communication among companies, co-workers, and individuals. A variety of Internet tools have been developed over the years to make effective use of these services.

Electronic mail Electronic Mail, or e-mail, is a fast, easy and inexpensive way to communicate with other Internet users around the world. E-mail can be used not only to exchange correspondence with friends, but to transfer documents, obtain electronic copies of books, subscribe to electronic news services or journals, and to obtain information about anything that is stored on a computer.

ListservsE-mail also provides a platform for sharing information quickly and on a grand scale by using listservs. Listservs are electronic groups that typically centre around a broad topic such as Digital Libraries or Reference Service, etc.

Every e-mail message sent to the listserv is distributed to all members of that listserv, which is potentially hundreds •or thousands of people. It does not cost anything to subscribe to a listserv, but simply requires that the user send an e-mail message to the appropriate address with the message: subscribe (listserv) Firstname Lastname. Each Listserver has one address where a user sends requests to subscribe, un-subscribe, search the archives, •etc., and another address to send actually questions or responses to the readers of the list. Apart from organising discussions, job announcements and conference announcements are popular usage of Listservs.

NewsgroupsAnother Internet service similar to listservs are newsgroups. News groups are like an international bulletin board. Each group is a forum for a different subject, where you can post questions and answers. There are hundreds of newsgroupcommunities.Theycentrearoundtopicssuchascomputing,news,recreation,social,and“alternative”topics.Eachnewsgroupnamebeginswithacodethatidentifiesthetypeofnewsgroupthatis.

UsenetUsenet is a collection of more than 8,000 newsgroups, or discussion groups, on every conceivable subject. Anyone can contribute a message, called an article, to a Usenet newsgroup or post a reply, known as a follow-up post, to an existing article. The system is intended for exchange of information in an informal way.

Remote loginRemote login is the ability of a computer user in one location to establish an online connection with another computer elsewhere. Once a connection is established with a remote computer, users can use that remote system as if their computer were a hard-wired terminal of that system. Many of these systems are available for any Internet user to access and use without an account.

TelnetTelnet is the service of the Internet that allows you to access remote computers outside your area. Many computers on the Internet are set up to allow Telnet access. Some require login names and passwords, but many do not have any restrictions. Telnet allows remote login to host computers, and commonly is used to connect to electronic catalogues and databases at near and distant libraries.

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File transfer (FTP)FiletransferisoneofthemostfrequentlyusedInternetapplications,enablingyoutocopyfilesfromoverathousanddifferentarchivesaroundtheworld.Thesefilesholdsuchthingsastext,images,sound,andexecutableprogrammes.FTPorFileTransferProtocolisusedtotransferfilesbetweencomputersonthenetwork.TherearetwotypesofFTP connections, anonymous and non-anonymous.

GopherGopher is an Internet system developed at the University of Minnesota, which allows a site to create an invisible tunnel from itself to other sites. Gopher was originally developed in April of 1991 by a team of experts including Bob Alberti, Farhad Anklesaria, Paul Lindner, Mark McCahill, and Daniel Torry at the University’s Microcomputer and Workstation Networks Centre.

The Internet Gopher is a simple protocol for building distributed information systems and organising access to Internet resources. It uses a series of menus to organise and automate access to information and other online system, wherever, they reside on the Internet. The Internet Gopher client software presents users with a virtual information matrix that they can navigate by either browsing a hierarchical arrangement of items, or search by submitting queries.

ArchieArchieisafilesearchingsystemthatwasdevelopedatMcGillUniversityofCanada.Itwasoriginallyformedtobea quick and easy way to scan the offerings of the many anonymous FTP sites that are maintained around the world. The Archie service is accessible through an interactive telnet session, e-mail queries and command line and X-window clients. Each Archie server, independent of the others, collects data and stores it future use. A query can be put to Archietofindfilenameswhichcontainacertainsearchstringorwhosedescriptioncontainsacertainword.

VeronicaVeronica attempts to index the world of Gopher servers, much like Archie attempts to build a comprehensive index of all anonymous FTP servers. Veronica usually is a menu item on a Gopher or World Web server. There might be several Veronica sites available on a given Gopher or WWW server. The search engine supports sophisticated searchstringsspecificallytotargetthedesiredinformation.TheVeronicasearchenginepermitslimitedBooleanand substring searches. Boolean searches enable the user to include and, or, and not, along with a hierarchy of parentheses, to control the search.

Wide Area Information Search WAIS stands for Wide Area Information Servers. Real-time connections are used to connect to other WAIS servers and to search their indexes. In combination with the World Wide Web, WAIS can be used as a back-end search engine.

WAIS works in two parts.The server side, which indexes WWW sites periodically and maintains this index for access by WAIS and •WWW clients.The client side, which includes WAIS clients and WWW clients.•

WAIS is a distributed information service that takes its input in a simple natural language format, offers indexed searchforfastretrieval,andhasa“relevancefeedback”mechanismtopermittheresultsofinitialsearchestobiasfuturesearches.WAISsearchenginesalsosupportBooleanqueries,supportingsyntaxsuchas“freedandgreennotblue,” which would get all items containing both red and green, excluding all records with only blue.

FingerFingerisanoldUnixutilitytoexaminetheuserloginfileandlearnsomethingabouttheuser.Ithelpstoknowiftheuserisloggedintothesystematthatverymoment.Thecommandstructureforfingerisasfollows:

Finger username@hostname


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Theusername is optional and requests specific information about a userwhosefirst or last namematches theusername on the hostname system.

WHOisWhois is the name of a particular white pages directory, it is a general directory, and it is an application that accesses thesedirectories.Usingit,youcanfindemailaddresses,hostcomputernamesanddomainnames.

MessagingThe messaging is the creation, storage, exchange, and management of text, images, voice, telex, fax, e-mail, paging, and Electronic Data Interchange (EDI) over a communications network. In programming, messaging is the exchange of message to a messaging server, which acts as a message exchange programme for client programmes. There are two major messaging server models: the point-to-point model and the publish/subscribe model.

Instant messagingInstant messaging (sometimes called IM or IMing) is the ability to easily see whether a chosen friend or co-worker is connected to the Internet and, if they are, to exchange messages with them.

Web chatThe Internet provides facility for a real time (on-line) communicating with one to one or one to many computers. This is popularly known as chat. On the Internet, chatting is talking to other people who are using the Internet at the sametimeyouare.Usually,this“talking”istheexchangeoftyped-inmessagesrequiringonesiteastherepositoryforthemessages(or“chatsite”)andagroupofuserswhotakepartfromanywhereontheInternet.

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SummaryThe Internet is a global collection of people computers which are linked together by cables and telephone lines •making communication possible among them in a common language.Computernetworkbydefinitionallowssharingofresources.•As far as safe movement of data is concerned, there exists a set of rules which governs the sending and receiving •of data on the Internet. These rules are implemented in two parts in the network software and are called Transmission Control Protocol (TCP) and Internet Protocol (IP).Username is same as the one which you may use when logging in to the computer on which you have your •Internet account. Logging in is the process of gaining access to your account on a computer which shared by several users.•Domain may be an apartment complex, a town, or even a country. Sub-domains may correspond to •organisations.The Internet as we know it today, in the mid-1990s, traces it origins back to a Defence Department project in •1969.An Internet service provider (ISP) is an organisation that provides Internet accounts, whether dial-in, DSL, •ISDN, cable, satellite or wireless.Internet Protocol Address (or IP Address) is a unique address that computing devices use to identify itself and •communicate with other devices in the Internet Protocol network.The DNS is a distributed system, meaning that only the 13 root servers contain the complete database of domain •names and IP addresses. All other DNS servers are installed at lower levels of the hierarchy and maintain only certain pieces of the overall database.Internet can and does provide a host of other services apart from the normal data transfer. These services include •Chat, E-mail, News Groups and Gopher.Through the Internet one canfind knowledge resources that allow one to study virtually any discipline•imaginable.

ReferencesSherman,J., 2003. • History of the Internet, Demco Media.Miller, P. F, Vandome, F. A. and McBrewster, J., 2009. • Domain Name System, VDM Publishing House Ltd.About.com, 2011. • Domain Name System – DNS [Online] Available at: <http://compnetworking.about.com/od/internetaccessbestuses/l/aa020503a.htm> [Accessed 11 November 2011].Baccala, B., 1997. • Internet History [Online] Available at: <http://www.freesoft.org/CIE/Topics/57.htm> [Accessed 11 November 2011].Portablefilmfestival, 2009.• History of the Internet [Video Online] Available at: <http://www.youtube.com/watch?v=d3VccCRiP98>[Accessed11November2011].Amazeen, T., 2008. • Internet Uses & Tools[VideoOnline]Availableat:<http://www.youtube.com/watch?v=D2ImPAlv0CQ&feature=results_main&playnext=1&list=PL7AF0E7C68B0C3DAF>[Accessed11November2011].

Recommended ReadingMoschovitis, J. P. C., 1999. • History of the Internet: a chronology, 1843 to the present, ABC-CLIO.Brown, H., 2001. • Internet Tools, Cengage Learning College.Trans-European Research and Education Networking Association Netskills, 2002. Internet• users’ reference, Addison-Wesley.


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Self AssessmentAspecialmachinecalled___________triesto,loadbalancevariouspathsthatexistonnetworks.1.

CPUa. routerb. monitorc. gatewayd.

Aspecialmachinecalled_________allowsdifferentelectronicnetworkstotalktoInternetwhichusesTCP/2. IP.

CPUa. routerb. monitorc. gatewayd.

Whichofthefollowingstatementsistrue?3. Domain may be an apartment complex, a town, or even a country.a. Sub-domain may be an apartment complex, a town, or even a country.b. Internet protocol may be an apartment complex, a town, or even a country.c. Transmission control protocol may be an apartment complex, a town, or even a country.d.

Whichofthefollowingcommunicatewitheachotherusingprivatenetworkprotocols?4. Web serversa. DNS serversb. DHCPc. DNS resolversd.

Which of the following refers to the interaction between two or more people through the Internet, as if they 5. weretalkingtoeachother?

Gophera. Chattingb. Emailc. New groupsd.

Whichofthefollowingistheexchangeofcomputer-storedmessagesbytelecommunication?6. Gophera. Chattingb. Emailc. New groupsd.

____________isasearchtoolthathelpstolookforinformationontheInternetonanysubject.7. Gophera. Chattingb. Emailc. New groupsd.

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Which of the following refer to the specialised group of people who regularly remain in contact with each other 8. throughtheabove-mentionedmethodsforthepurposeofdiscussionsonaspecialisedtopic?

Gophera. Chattingb. Emailc. New groupsd.

Match the column.9.

Gopher1. Application softwareA.

WWW2. Used for locating document on WWWB.

URL3. collection of web pages available on the InternetC.

Web browser4. search toolD. 1-A, 2-B, 3-C, 4-Da. 1-D, 2-C, 3-B, 4-Ab. 1-B, 2-D, 3-A, 4-Cc. 1-C, 2-A, 3-D, 4-Bd.

__________areelectronicgroupsthattypicallycentrearoundabroadtopic.10. Listservsa. Newsgroupsb. Emailc. Usenetd.


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Chapter II

Components of Internet Structure

Aim


introduce the personal computer•

describe communication equipment for users•

highlight the local loop carrier•

Objectives


elucidate the location of ISP•

explain web servers •

describe the different ways of accessing internet through personal computer•

Learning outcome


understand different modes of connection through local loop carrier•

comprehend various features of a personal computer•

discuss the relationship between the interne• t user and ISP

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2.1 Personal ComputerApersonalcomputerthatisusedtoconnecttoInternetandbrowsethewebpagesshouldhavespecificfeatures.Though, not all the features are compulsory, having all of them makes you eligible to browse almost all types of content on the Internet which had different technologies. It is preferable to have a computer with the components that support multimedia inputs, such as webcam, speakers, headphones, colour monitor, good amount of hard disk and RAM, microphone, etc. A webcam is a device which is installed and connected to the computer that enables you to be seen on the display of another computer that is connected to the internet.

Appropriate driver software has to be loaded in your machine and the webcam has to be connected to the machine. •If speakers are connected to the computer, then you can hear the audio content of the web page. For example, there are a number of websites such as cnn.com (http://www.cnn.com), bbcnews.com (http://www.bbcnews.com)etc.,whichconsistsofsignificantamountofaudiocontent.Intheabsenceofspeakers,youcannothearaudio contents.Amicrophoneenablesyoutoaddressalargenumberofpeoplespreadoverinalargeareawhoareatsignificant•distance. In the context of Internet, if you have a microphone installed on your computer, then you can speak to other users of Internet. Now a days, it has become common to use Internet as a medium to make telephone calls. When you connect to another person through Internet, the only way you can converse with him/her is with the help of microphone. Of course, the other person should have speakers/headphones to hear you. A colour monitor enables you to view the content of web pages in true colours. Otherwise, the content is displayed in black and white. Thecomputershouldalwayshavesignificantamountsofprimaryandsecondarymemories.Thiswillenablethe•user to load web pages which occupy large amounts of memory due to the presence of images, animations, etc., as part of their content. Also, users can install different types of software which will enable them to access as well as create different types of content on the Internet. There is a very important standard abbreviated as MIDI which stands for Musical Instrument Digital Interface. Most of the music emitting devices such as sound cards conform to this standard. The advantage of conformance of this standard is that the composition of the music willalsobeavailable.Thecompositionincludesdifferentvaluesofthatspecifiednote’spitch,length,etc.Any music that is available on one synthesiser which conforms to this standard can also be played as well as •modifiedonanyothersynthesiserwhichalsoconformstotheMIDIstandard.So,itispreferablethatthecomputeris also equipped with MIDI interface which enables you to record music and modify it from the synthesisers which conform to MIDI.

An illustration of the computer that is equipped with all the above mentioned components is given in following figure.

CPU

Webcam

Head phone

Fig. 2.1 A computer system


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2.2 Communication Equipment of UserItrequiresspecificinfrastructuretoconnectthecomputeroftheuserfromwheres/heaccessesInternettothelocalloopoftheInternet.Primarily,auserofInternetmayaccessitfromoffice/home.Itispossiblethats/heaccessesInternetwhileonthemovesuchasfromflight,train,etc.WhentheuserisaccessingInternetfromhome,s/hemayrequire a modem that may be residing inside/outside the computer which in turn, is connected to the telephone line. The signal from/to Internet through computer is modulated/ demodulated using modem. This is the dial-up connection which is commonly used to access Internet from home. There are also other ways of accessing Internet from home such as through Cable TV, etc.

Broadband modem

Broadband modem(to internet

connection)

Ethernet or USB cable

Computer 2

Computer 3Computer 4

Computer 1Wi-Fi

Wi-Fi

Fig. 2.2 Accessing internet from a stand alone computer at home(Source: http://home-remodeling-pic.com/wp-content/uploads/2011/06/Home-Network.jpg)

ThewayofaccessingInternetfromtheofficediffersfromthewayitisaccessedfromthehome.Itisnotruledout•thatthewayInternetisaccessedfromofficemaybethesameasthatoffromhomeincaseofsmallorganisationswhicharehavingacoupleofdial-upconnections.ThemostpopularwayofaccessingInternetfromtheofficeis through leased lines via a network. The computer of the user from where s/he is accessing Internet is connected to a Local Area Network (LAN) •whoseserverisinturnconnectedtoInternetthroughadedicatedtelephoneline.Usually,afirewallisinstalledwhich is connected to the dedicated telephone line and the server of the LAN for security purposes. This enables theofficetoobstructillegalintrudersintothenetworkofofficethroughInternet.Withsuchasetup,itispossibleto extend the services provided by the LAN to the web also.With connection to the Internet through LAN, the users are enabled to mail messages not only to their peers •on the LAN but also to anyone who is connected to the Internet. Such a LAN based Internet access can also enable an organisation to set up an Intranet for itself. The server of the LAN offers various services to the users. FollowingfiguredepictsthecommunicationequipmentassociatedwiththecomputeroftheuserwhoaccessesInternetthroughoffice.

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Front Desk Computer

Doctor’s Computer

Hub or Switch

Wireless Access PointBilling

ComputerHandheld Computer

Fig. 2.3 Accessing internet from a computer through a LAN(Source: http://www.ezbis.com/images/wireless.gif)

2.2.1 Local Loop CarrierIt connects the locationof theuser suchasoffice/organisation to the InternetServiceProvider’s location.Theconnection may be based on different modes. The location of the user may be connected to the ISP through the following:

Cable•Satellite•Leased lines•Wi Fi•Power lines•

The Wi Fi technology is the latest way of accessing the Internet. It is possible to connect to Internet wirelessly. The only important requirement is that the machine should be within the area mentioned by the particular hot spot provider. Such hot spots are available in university campus, airports etc. from where a person can access Internet. This is a revolutionary technology which enables anyone to be in touch with the rest of the world without any interruption. Followingfiguredepictstheconnectionsbetweenuser’slocationandtheInternetserviceprovider(ISP).

Internet

Desktop with Gigabite NIC

External Storage

Laptop with WiFi

Cable WAN port

XBOXDGND3700

Phone line

Cable Alternate Cable

Fig. 2.4 User connecting to internet through wireless/cable network(Source: http://www.wireless-router-net.com/wp-content/uploads/2011/01/92-dgnd-3700-network-diagra.jpg)


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2.2.2 Location of ISPWhenever anyone intends to obtain internet connection, they need to select the appropriate Internet service provider (ISP). ISP charges the subscriber accordingly. An ISP provides the telephone numbers that are to be dialled by the userstoconnecttoInternet.IncaseoflargeofficeswhichsubscribetoInternetaccessthroughleasedlines,theyareallottedtelephoneline(s)whichdedicatedlyconnecttheofficetoInternet.ThetermsandconditionsvaryfromISP to ISP.

The Internet connection can be visualised as a thread with user’s machine located at one end and the ISP at the other. Every ISP provides subscription to a large number of users. The database of all the users is available with ISP including the user names and passwords. Any subscriber, when tries to connect to the Internet, his/ her user name and password are authenticated by the ISP. An ISP’s, function is to provide access of Internet to its subscribers. The user may be subscribed to ISP for access to Internet through a leased line, dial-up connection, etc.

FollowingfiguredepictstherelationshipbetweentheInternetuserandtheInternetserviceprovider(ISP).

Internet service provider

Internet

Enterprise

Telecom Operator

Fig. 2.5 Relationship between internet user and the Internet Service Provider(Source: http://www.erudium.polymtl.ca/images/industrie/industrie1-eng.gif)

2.2.3 Web ServersA web server is a computer which serves the requests of the hosts that are connected to the Internet. Web servers are connected to the Internet which enables them to host and serve web pages. They have a unique and static domain name and an IP address associated with them.

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Web service

Web service

File share

File share

Web server farm

Web server farm

Provisioning Server

Network share sharedconfiguration

Fig. 2.6 Web servers(Source:http://learn.iis.net/file.axd?i=626)


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SummaryApersonal computer that is used to connect to Internet and browse theweb pages should have specific•features.Amicrophoneenablesyoutoaddressalargenumberofpeoplespreadoverinalargeareawhoareatsignificant•distance.When the user is accessing Internet from home, s/he may require a modem that may be residing inside/outside •the computer which in turn, is connected to the telephone line.ThewayofaccessingInternetfromtheofficediffersfromthewayitisaccessedfromthehome.•With connection to the Internet through LAN, the users are enabled to mail messages not only to their peers on •the LAN but also to anyone who is connected to Internet.The Wi Fi technology is the latest way of accessing the Internet. It is possible to connect to Internet •wirelessly.Whenever anyone intends to obtain internet connection, they need to select the appropriate Internet service •provider (ISP). ISP charges the subscriber accordingly.The Internet connection can be visualised as a thread with user’s machine located at one end and the ISP at the •other.Web servers are connected to the Internet which enables them to host and serve web pages.•

ReferencesSarikaya, B., 2002. • Geographic location in the Internet, Springer.Gray, N., 2003. • Web server programming, Wiley-India.Blair, S. & Kimmet, M., • The Web Server [pdf] Available at:< http://www.nd.edu/~cseprog/proj02/webserver/webserver.pdf> [Accessed 11 November 2011].Ferguson, G., 1999. • How to Find Your Internet ISP Address [Online] Available at:< http://www.ehow.com/how_5873240_internet-isp-address.html>[Accessed11November2011].ChristianNetcom, 2009. • Internet Service Providers [Video Online] Available at:< http://www.youtube.com/watch?v=aa36wqwq9b4>[Accessed11November2011].cscie1, 2006. • Videos of the Week (Vol. 4): Web Servers [Video Online] Available at:< http://www.youtube.com/watch?v=CCUKuBZJJWE>[Accessed11November2011].

Recommended Reading Schiller, H. J. & Voisard, A., 2004. • Location-based services, Elsevier.Yeager, J. N. & McGrath, E. R., 1996. • Web server technology: the advanced guide for World Wide Web information providers, Morgan Kaufmann.Collin, H. M. S., 1997. • Setting up a Web server, Elsevier.

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Self Assessment_________isadevicewhichisinstalledandconnectedtothecomputerthatenablesyoutobeseenonthe1. display of another computer that is connected to the internet.

Microphonea. Webcamb. Speakerc. Moused.

Which of the following enables you to address a large number of people spread over a large area who are at 2. significantdistance?

Microphonea. Webcamb. Speakerc. Moused.

If___________areconnectedtothecomputer,thenyoucanheartheaudiocontentofthewebpage.3. hard diska. speakersb. webcamc. moused.

Whichofthefollowingstatementsistrue?4. When the user is accessing Internet from home, s/he may require a web server that may be residing inside/a. outside the computer.When the user is accessing Internet from home, s/he may require a DNS server that may be residing inside/b. outside the computer.When the user is accessing Internet from home, s/he may require a listservs that may be residing inside/c. outside the computer.When the user is accessing Internet from home, s/he may require a modem that may be residing inside/d. outside the computer.

Thesignalfrom/toInternetthroughcomputerismodulated/demodulatedusing__________.5. modema. mouseb. microphonec. webcamd.

ThemostpopularwayofaccessingInternetfromofficeisthroughleasedlineswherethecomputeroftheuser6. fromwheres/heisaccessingInternetisconnectedtoa_________.

DNSa. WANb. LANc. WiFid.


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ThelocationoftheusermaybeconnectedtotheISPthrough_____________.7. modema. satelliteb. LANc. Web serverd.

WhichofthefollowingallowswirelessconnectivitytotheInternet?8. Cablea. Leased linesb. Power linesc. WiFid.

Wheneveranyoneintendstoobtaininternetconnection,theyneedtoselecttheappropriate_________.9. ISPa. LANb. WANc. DNSd.

___________isacomputerwhichservestherequestsofthehoststhatareconnectedtotheInternet.10. Modema. Satelliteb. LANc. Web serverd.

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Chapter III

Electronic Mail and Features of Internet

Aim


introduce the concept of e-mail•

describe various mailer features•

highlight e-mail management•

Objectives


elucidate different message components•

explain MIME types •

explicate chat rooms•

Learning outcome


understand news groups•

comprehend mailing lists•

differentiate betwe• en e-mail and post mail


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3.1 IntroductionElectronic mail is the service that is available to people on a local area network or on the global Internet. It is one of the most commonly used services on the Internet, as this service is more convenient than normal postal system. E-mail does not require the person receiving the mail to be available (logged into the destination computer) at the time of receiving the mail.

It is called e-mail, as the basic concept in e-mail is similar to the postal mail services viz.You put on e-mail message into electronic envelope and place an electronic address on it.•You then hand over the envelope to someone else (the network) for delivery.•You do not worry, when the e-mail is read.•You can forward e-mail to a forwarding address. The e-mail system routes it to the forwarding address.•Your message may come back to you if your mail cannot be delivered. •

Other common points between e-mail and postal mail are:The sender should know your e-mail address.•You can keep in touch with your friends using e-mail.•An electronic magazine or a mailing list subscription may provide you with the latest trends in the topics of •your interest.Commercialcompaniesmaysendyoutheiradvertisementthroughelectronicmail.Thisisalsocalled“junk”•mail.Your mail may be delivered to, and read by, someone else.•Every piece of e-mail you get may not be pleasant and friendly.•

Some of the difference between e-mail and postal mail are:As e-mail is so easy to handle, therefore, it has become an extremely useful tool for reaching people you does •not even intend to see.Your e-mail because of problems may go to a computer postmaster or the person responsible to handle bounced •e-mail.E-mail, since it is very easy to create, may result in sending responses on which one may regret later.•

3.2 Message ComponentsFollowing are the components of an e-mail message.

HeaderThe header of an e-mail address is where all the important addressing information is kept, along with data about the message itself. The following table describes the elements that make up the header of an e-mail.

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To TheTofieldiswherethee-mailaddressofthemessagesrecipientisentered.

Subject The subject is essentially a title, or a very short summary, of an e-mail. Ideally it should contain some sort of reference to the e-mail's content.

CC

To Carbon Copy (CC) a message to someone is to send them a copy of the e-mail, even though they are not the e-mail’s intended recipient. This is a common practice in business communications, where many people in an organisation often need to be made aware of certain communications, even if they are not actively involved in the conversation.

BCCBCC stands for Blind Carbon Copy. Any people included in the BCC recipient list of an e-mail receive a copy of the message, but their name is not included in the message headers, and no one else who received the message knows that they were sent a copy.

Table 3.1 Message components(Source: http://helpdesk.lakeheadu.ca/e-mail-message-components/)

BodyThe body of the message is, of course, the most important part. Everything you need to say is entered here, and this is what the recipient will be reading.

3.3 Mailer FeaturesDifferent mailer features are detailed in the following table.

Personalised MailsPersonalise each mails based on any header. Each list is mapped to a CSVfile,andthemailsendtothatlistcanbepersonalisedonanyoftheheaderpresentinthatCSVfile.

Direct Mailing

No need to add all your customers e-mail addresses together. Just create a subscription list, include all the subscribers, and send a single mail to that list. eMailer will in turn send that mail directly to each of the subscribers.

No SMTP required

Don’thaveanSMTPserver?Don’tworry.eMailercantalkdirectlywith the recipient mail server and deliver the mails. If you have an SMTPserverandwanttoroutethemailsthroughit,justconfigureeMailer. It even supports SSL mail servers.

Unlimited Subscription ListsCreate as must subscription lists as you want. Its just a matter of importingaCSVfile!Youcanalsocreateanynumberofsenderaccounts.

HTML / Plain Text MailsSend HTML or Plain Text mails easily. eMailer contains a WYSIWYG HTML editor, which allows you to create HTML mails easily.

Drag and Drop Attachments Attachingafileisjustamatterofdraganddrop.Attachanynumberoffileseasily.

Emoticons Support eMailer supports a wide range of emoticons. It can be easily extended to add your own set of emoticons/smileys.

Platform Independence eMailer can run on any OS that supports Java like Windows, Mac, Linux, etc.

Fast Delivery Youdecidehowfastitshouldbe.eMaileriscompletelyconfigurable.

Table 3.2 Mailer features(Source: http://emailer.utilstore.com/features.htm)


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3.4 E-mail ManagementE-mailmanagementcoversfourkeyfactorsthatcanhelpyouprocessyoure-mailmoreefficientlyathomeaswellasattheoffice.Mostofthetechniquescanhelpyoutomoreefficientlyprocesse-mailandemptyyourInbox,evenif you use an e-mail application other than Outlook.

Step 1: Set up a simple and effective e-mail reference systemThefirststeptowardanorganisedInboxistounderstandthedifferencebetweenreferenceinformationandactioninformation.

Referenceinformationisinformationthatisnotrequiredtocompleteanaction;itisinformationthatyoukeepincase you need it later. Reference information is stored in your reference system—an e-mail reference folder, your My Documents folder, or a company intranet site, for example.Action information is information you must have to complete an action. Action information is stored with the action, either on your to-do list or on your Calendar.

Most people receive a considerable amount of reference information through e-mail. Sometimes as much as one-third of your e-mail is reference information. So it is essential to have a system that makes it easy to transfer messages from yourInboxintoyoure-mailreferencesystem—aseriesofe-mailfilefolderswhereyoustorereferenceinformationto ensure you have easy access to it later.

Step 2: Schedule uninterrupted time to process and organise e-mailMany e-mail messages require you to make a decision. The best decisions require focus, and focus requires uninterrupted attention. Establish a regular time each day to process your e-mail so that you can empty your Inbox. You can scan your e-mail during the day for urgent messages or requests from your boss.

Bookyourselfarecurringappointmentforanhouradaytoprocesse-mail,andmarkthattimeas“busy.”Duringthathour, don’t answer the phone or take interruptions, and work only on processing your Inbox. You can also turn off theaudioalertthatsoundseachtimeyoureceiveanewe-mail—whichcanbeadistractioninitself.Atfirst,keepingthese appointments will take discipline. But over time, the discipline becomes habit. And after you completely empty your Inbox, you’ll see the value of this one hour a day and you’ll stick to it like glue.

Fig. 3.1 Instance search in Microsoft Outlook(Source: http://www.microsoft.com/atwork/productivity/email.aspx)

Step 3: Process one item at a time, starting at the topSortyourinboxbytheorderinwhichyouwillprocessit.Forexample,youcanfilterbydate,bysubject,orevenby the sender or receiver of the e-mail message.

Fig. 3.2 View tab using date, subject or sender and receiver(Source: http://www.microsoft.com/atwork/productivity/e-mail.aspx)

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You can also change the arrangement directly from your Inbox. To display the list of options, under the Search box, right-click the Arrange By: box.

Fig. 3.3 The Arrange By: box in inbox(Source: http://www.microsoft.com/atwork/productivity/email.aspx)

Step 4: Use the “Four Ds for Decision-Making” modelThe“FourDsforDecision-Making”model(4Ds)isavaluabletoolforprocessinge-mail,helpingyoutoquicklydecide what action to take with each item and how to remove it from your Inbox.

Fig. 3.4 The expanded Ribbon in Outlook 2010 replaces Outlook 2007 menu(Source: http://www.microsoft.com/atwork/productivity/email.aspx)

The Quick Steps feature speeds up managing your e-mail even more. This feature enables you to perform the multi-steppedtasksyouusemostoften,suchasmovinge-mailtoaspecificfolderormovingamessageandreplyingtoitwithameetingrequest,withasingleclick.TheQuickStepsgalleryincludesbuttonsforone-clickfileandflag,sending messages to your team, and other popular commands.

Fig. 3.5 The Quick Steps feature in new Outlook(Source: http://www.microsoft.com/atwork/productivity/email.aspx)


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Decide what to do with each and every messageHowmanytimeshaveyouopened,reviewed,andclosedthesamee-mailmessageorconversation?Thosemessagesare getting lots of attention but very little action. It is better to handle each e-mail message only once before taking action—which means you have to decide what to do with it and where to put it. With the 4 Ds model, you have four choices:

Delete itGenerally, you can delete about half of all the e-mail you get. But some of you shudder when you hear the phrase “deletee-mail.”Ifyoudousealargepercentageofwhatyoukeep,yourmethodisworking.Butmanyofuskeepa lot more than we use. Here are some questions to ask yourself to help you decide what to delete:

Doesthemessagerelatetoameaningfulobjectiveyou’recurrentlyworkingon?Ifnot,youcanprobablydelete•it.Whykeepinformationthatdoesn’trelatetoyourmainfocus?Doesthemessagecontaininformationyoucanfindelsewhere?Ifso,deleteit.•Doesthemessagecontaininformationthatyouwillrefertowithinthenextsixmonths?Ifnot,deleteit.•Doesthemessagecontaininformationthatyou’rerequiredtokeep?Ifnot,deleteit.•

Do itThereisnopointinfilingane-mailorclosingane-mailifyoucancompletetheassociatedtaskinlessthantwominutes. Try it out—see how much mail you can process in less than two minutes. I think you will be extremely surprisedandhappywiththeresults.Youcouldfilethemessage,youcouldrespondtothemessage,oryoucouldmake a phone call. You can probably handle about one-third of your e-mail messages in less than two minutes.

Delegate itIf you can delegate it (forward it to another team member to handle), do so right away. You should be able to compose and send the delegating message in about two minutes. After you have forwarded the message, delete the original message or move it into your e-mail reference system.

Defer itIf you cannot delete it, do it in less than two minutes, or delegate it, the action required is something that only you can accomplish and that will take more than two minutes. Because this is your dedicated e-mail processing time, youneedtodeferitanddealwithitafteryouaredoneprocessingyoure-mail.Youwillprobablyfindthatabout20 percent of your e-mail messages have to be deferred. There are two things you can do to defer a message: Turn it into an actionable task, or turn it into an appointment.

Using the 4 Ds model on a daily basis makes it easier to handle a large quantity of e-mail. Our experience shows that, on average, people can process about 100 e-mail messages an hour. If you receive 40 to 100 messages per day, all you need is one hour of uninterrupted e-mail processing time to get through your Inbox. Our statistics show that of the e-mail you receive:

Fiftypercentcanbedeletedorfiled.•Thirty percent can be delegated or completed in less than two minutes.•Twenty percent can be deferred to your Task List or Calendar to complete later.•

If you have a backlog of hundreds of messages, it will take time to get to the point where your daily routine keeps you up to date. It’s important to get that backlog down, so I would suggest setting blocks of time aside to work through it. Then, you can really enjoy processing your messages every day using the 4 Ds.

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3.5 MIME TypesMIME is a standard for describing different types of information. This was originally meant to be used to specify encoding for different types of information into text. This made it possible to send them as e-mail. The standard MIME is also used in other types of communication where there is a need for specifying which type of information is used. This could be your local operating system or a web server.

Mimeis justaspecification.Normally the information isencodedwithsomeotherstandardformat.When•decodeditregainsitoriginalshape.Tobeabletoreadthefileyouneedanapplicationthatcanhandletheattachedfile.Iftwofiles,aworddocumentandaimageissentbye-mailtheywouldbothgetencodedasMIME.Uponreceivingthesefilesthereneedtobeanapplicationassociatedwitheachfiletype.Microsoftwordormaybeanotherwordprocessorwouldbeassociatedwiththeworddocumentmakingitpossibletoreadthefile.Photoshop or another image viewer would be associated with the image. Normally the conversion from MIME tofilesishandledbythee-mailapplication.Whenthefileisstoredondiskitisuptotheoperatingsystemtomapanapplicationtofiletype.EachkindofmediafilecommonlyusedontheInternethasaMIME(MultipurposeInternetMailExtension)•type. Browsers differ in their intrinsic capabilities for handling various MIME types. If a browser cannot display a certain MIME type, it tries to turn the job over to an additional chunk of software like a viewer, plug-in, or ActiveX control. If it has no such software to display the embedded media, it then either displays any alternative text that you have included in the <OBJECT> tag using the ALT attribute or proceeds to display an alternative object using the <NOEMBED> tag.Inthe<OBJECT>tag,youcanidentifytheMIMEtypeofyourmultimediafilebyusingtheTYPEattribute.•The TYPE attribute is optional, but by including it, you allow the browser to avoid wasting time downloading thefileifithasnowayofdisplayingthefile.Ifyoudon’tincludetheTYPEattribute,thebrowserusesthefileextensiontofigureoutwhatkindoffileitis.MIME type names have two parts, the type and subtype, separated by a slash in the MIME name as in •application/x-msvideo.Commonmultimediatypesareapplication,audio,andvideo;applicationisacatch-alltypethatsimplyimpliesthatthefile’sformatisgenerallynativetoaparticularapplication.MIME subtypes are of two varieties: registered and unregistered. Registered subtypes are registered by the •Internet Assigned Numbers Authority (IANA), after a formal process. Unregistered subtypes can be anything atall—infact,youcancreateyourown—butthesubtypemustbeginwithx-.AudiofilesinWAVformat,forinstance, are of the MIME type audio/x-wav.

3.6 Newsgroups Usenetisbasicallyanelectronicbulletinboard.Itconsistsofasetof“newsgroups”withnamesthatareclassifiedhierarchicallybysubject.“Articles”or“messages”are“posted”tothesenewsgroupsbypeopleoncomputerswiththe appropriate software — these articles are then broadcast to other interconnected computer systems via a wide varietyofnetworks.Somenewsgroupsare“moderated”;inthesenewsgroups,thearticlesarefirstsenttoamoderatorfor approval before appearing in the newsgroup. Usenet is available on a wide variety of computer systems and networks,butthebulkofmodernUsenettrafficistransportedovereithertheInternetorUUCP.

Usenethasmadeauniquecontributiontotheworldofcomputing.Itwasthefirstattempttocreateanetworkbeyondlocal BBS communities (which themselves were fairly new). At a time when the ‘internet’ was a network of privately operated ARPANET sites, Usenet offered a network for the general public.

Although most of the communication on Usenet was technically oriented, casual conversation was also popular, and more and more machines joined the network. To keep up with demand and handle growing amounts of data, the underlying software powering Usenet was updated and rewritten numerous times by the same people that participated in the newsgroups.


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Usenetwasnotonlyanimportanttechnicaldevelopment;manysocialaspectsofonlinecommunicationwere•introduced,refined,andbecamedefactostandardsthankstoUsenet.Emoticons,flamewars,trolls,signatures,andevenslangacronyms(BRB,LOL)foundtheirfirstcommonusageonUsenet.Compared to other technologies, computers have evolved (and are still evolving) at a whirlwind pace. •Consequently, the history of computing has been muddied by innovations that quickly become obsolete, concurrent developments that solve the same issues, and developers discarding documentation of simple projects that became extremely successful.Duetotheseissues,thearchiveprovidedbyUsenetisafinesourceofprimaryinformationfromthemostrecent•decades of computing. Usenet’s history is not just relevant to social networks, but to many high-tech concepts and innovations.Newsgroups are arranged in subgroups which make them easier to list. A newsgroup name starts with a subgroup •headerfollowedbyoneormoredescriptivewords,separatedby“.”Frequently Asked Questions (FAQ’s) are an important part of USENET culture. These list and answer the kinds •of questions that beginner’s ask, and provide a good introduction to each group. They are often an excellent source of information on the subject matter of the group.

Features of UsenetUsenet is not an organisation. No person or group has authority over Usenet as a whole. No one controls who gets anewsfeed,whicharticlesarepropagatedwhere,whocanpostarticles,oranythingelse.Thereisno“UsenetIncorporated,”noristherea“UsenetUser’sGroup.”You’reonyourown.

It is not a democracy. Since there is no person or group in charge of Usenet as a whole — i.e., there is no Usenet •“government”—itfollowsthatUsenetcannotbeademocracy,autocracy,oranyotherkindof“-acy.”Itisnotfair.Afterall,whoshalldecidewhat’sfair?Forthatmatter,ifsomeoneisbehavingunfairly,who’s•goingtostophim?Usenetisnotaright.Somepeoplemisunderstandtheirlocalrightof“freedomofspeech”tomeanthatthey•have a legal right to use others’ computers to say what they wish in whatever way they wish, and the owners of said computers have no right to stop them.It is not a public utility. Some Usenet sites are publicly funded or subsidised. Most of them, by plain count, are •not. There is no government monopoly on Usenet, and little or no government control.It is not an academic network. It is no surprise that many Usenet sites are universities, research labs or other •academic institutions. Usenet originated with a link between two universities, and the exchange of ideas and information is what such institutions are all about. But the passage of years has changed Usenet’s character. Today, by plain count, most Usenet sites are commercial entities.Usenet is not an advertising medium. Because of Usenet’s roots in academia, and because Usenet depends so •heavily on cooperation (sometimes among competitors), custom dictates that advertising be kept to a minimum. It is tolerated if it is infrequent, informative, and low-hype.It is not the Internet. The Internet is a wide-ranging network, parts of which are subsidised by various governments. •Itcarriesmanykindsoftraffic,ofwhichUsenetisonlyone.AndtheInternetisonlyoneofthevariousnetworkscarryingUsenettraffic.ItisnotaUUCPnetwork.UUCPisaprotocol(actuallya“protocolsuite,”butthat’satechnicalquibble)for•sending data over point-to-point connections, typically using dialup modems. Sites use UUCP to carry many kindsoftraffic,ofwhichUsenetisonlyone.AndUUCPisonlyoneofthevarioustransportscarryingUsenettraffic.Usenet is not a United States network. It is true that Usenet originated in the United States, and the fastest growth •in Usenet sites has been there. Nowadays, however, Usenet extends worldwide. The heaviest concentrations of Usenet sites outside the U.S. seem to be in Canada, Europe, Australia and Japan.

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3.7 Mailing ListsBy using e-mail, you can search for different groups of people sharing same interest. Whether you are interested in sports, research or botany. E-mail provides a mechanism for groups of people who have shared interests to establish and maintain contact. These groups are called mailing lists (lists or short) where there are mailing lists of the members’ e-mail addresses. You can subscribe to any of such lists. You will receive copies of all the mail sent to the list. You can also send mail to all the subscribers of the list.

For becoming list subscriber, you need to contact the list administrator and ask to be added to the list. There are •two types of list administrators: humans and the computer programs called listservs. Your request to subscribe may sometimes be refused. Do not get disappointed, there will be plentiful more lists who will accept your subscription.If you have joined many lists, you may wind up with lot of junk mails in your mailbox. For example, if you •subscribe to several active lists. You may receive over 100 messages every day. Thus, limit your subscriptions to limited lists. Moderated lists have one or more human moderators who screen all incoming mail and only redistribute a selected portion to the list. Immoderate lists just pass along all the mail. If you do not like a particular list, you can always unsubscribe from it, by sending a request to the administrator.

3.8 Chatting RoomsThe Internet provides facility for a real time (on-line) communicating with one to one or one to many computers. This is popularly known as chat. On the Internet, chatting is talking to other people who are using the Internet at the sametimeyouare.Usually,this“talking”istheexchangeoftyped-inmessagesrequiringonesiteastherepositoryfor the messages and a group of users who take part from anywhere on the Internet.

In some cases, a private chat can be arranged between two parties who meet initially in a group chat. Chats •can be ongoing or scheduled for a particular time and duration. Most chats are focused on a particular topic of interestandsomeinvolveguestexpertsorfamouspeoplewho“talk”toanyonejoiningthechat.Chatsarealsoconducted on online services, by bulletin board services, and by Web sites.One to one chat is commonly used to communicate with friends, relatives or co-workers. A chat can also be •conducted using sound or sound and video, assuming you have the bandwidth access and the appropriate programming. Users can incorporate images, video, audio, and hot links into their chat. Working with standard browsers and no additional special software, WebChat can be used for businesses that want to attract lots of visitors to their websites for marketing, realtime customer support, direct sales, corporate teleconferencing, and consumer education.

Internet Relay Chat (IRC)Internet Relay Chat (IRC) allows you to meet online with people of similar interests. IRC consists of a large number of channels that contain group conversations. Channels can be created by anyone, and users can join channels and exchange messages. It is a text based mode of communication.

Users often use cryptic codes and abbreviations to signify phrases of speech, so they do not have to type whole •words. Channels are located on IRC servers, which often talk to each other and share channels, so that messages on one server are relayed to the same channels on other IRC servers. IRC provides real-time communication with others on the Internet. Popularly known throughout the Internet as •IRC, Internet Relay Chat offers the ability to communicate interactively with many thousands of people around the world about nearly any subject imaginable. Unlike any other Internet service, IRC enables you to hold a spontaneous conversation, in real time, with a group of individuals who may never physically meet.Internet Relay Chat works as a client/server application, and the IRC servers are interconnected to form, from •the user’s perspective, one large service. Each IRC user must use a client programme on their Internet host.


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Audio and video streamingStreaming audio and video is the ability to download video and audio from the Internet and have this play without havingtowaitfortheentirefiletobedownloaded.Thismeansstreamingaudioandvideocansupport“live”events,and viewers can watch or listen to events as they occur. Streaming audio and video requires special servers and software to be installed on your computer.

ConferencingConferencing can take many forms, such as web chat, audio conferencing, video conferencing, multimedia conferencing, screen-sharing, etc. You can use the desktop video and audio simultaneously, use the audio alone, or just use the screen-sharing capability without either audio or video.

Virtual corporationAvirtualcorporationcanbedefinedasa temporarycollaborativenetworkofagroupofprofessionals suchascreativedesigners,manufacturers, suppliers, customersorotherexperts inmarketingandfinance linkedbyaninteractive multimedia network to share skills, costs, production facilities, resources, and access to each other’s markets. The virtual corporation implies a competitive advantage or even survival in an increasingly interdependent global economy.

Collaborative multimedia computingCollaborative computing allows users to work together on a document or project, usually in real time, by taking advantage of underlying network communication systems.

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SummaryElectronic mail is the service that is available to people on a local area network or on the global Internet.•E-mail does not require the person receiving the mail to be available (logged into the destination computer) at •the time of receiving the mail.The header of an e-mail address is where all the important addressing information is kept, along with data about •the message itself.The body of the message is, of course, the most important part. Everything you need to say is entered here, and •this is what the recipient will be reading.E-mailmanagementcoversfourkeyfactorsthatcanhelpyouprocessyoure-mailmoreefficientlyathomeas•wellasattheoffice.Mostofthetechniquescanhelpyoutomoreefficientlyprocesse-mailandemptyyourInbox, even if you use an e-mail application other than Outlook.MIME is a standard for describing different types of information. This was originally meant to be used to specify •encoding for different types of information into text.Usenetisbasicallyanelectronicbulletinboard.Itconsistsofasetof“newsgroups”withnamesthatareclassified•hierarchically by subject.E-mail provides a mechanism for groups of people who have shared interests to establish and maintain contact. •These groups are called mailing lists (lists or short) where there are mailing lists of the members’ e-mail addresses.On the Internet, chatting is talking to other people who are using the Internet at the same time you are.•Internet Relay Chat (IRC) allows you to meet online with people of similar interests.•

ReferencesBrimner, D. L., 2000. • E-Mail, Children’s Press.Burdick, B. Coakley, C. and Richardson, P. J., 2006. • The Internet literacy handbook, Council of Europe.LANTech, 1996, • Mime Types [Online] Available at: <http://www.ltsw.se/knbase/internet/mime.htp> [Accessed 11 November 2011].Internet-101, 2011. About Newgroups [Online] Available at: <http://www.internet101.org/welcome-to-internet-•101/about-newsgroups> [Accessed 11 November 2011].BoldSoftware, 2011. • See What Email Management is All About [Video Online] Available at: < http://www.youtube.com/watch?v=HR3NcGW5PzU>[Accessed11November2011].eHowTech, 2009. • Computer Information: What Is a Newsgroup? [Video Online] Available at: < http://www.youtube.com/watch?v=_qGFlaZum4A>[Accessed11November2011].

Recommended ReadingHaig, M., 2001. • E-mail essentials: how to make the most of e-communication, Kogan Page Publishers.Greenlaw, 2005. • In-Line/On-Line, 2nd ed., Tata McGraw-Hill Education.TechRepublic, 2003. • IT Professional’s Guide to E-mail Administration, CNET Networks Inc.


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Self AssessmentWhichofthefollowingisnotacomponentofe-mailmessage?1.

Headera. Bodyb. Junk mailc. Signatured.

_________amessagetosomeoneistosendthemacopyofthee-mail,eventhoughtheyarenotthee-mail’s2. intended recipient.

CCa. BCCb. Signaturec. Salutationd.

__________coversfourkeyfactorsthatcanhelpyouprocessyoure-mailmoreefficientlyathomeaswellas3. attheoffice.

E-mail messagea. E-mail managementb. Internetc. Usernamed.

Which of the following is a valuable tool for processing e-mail, helping you to quickly decide what action to 4. takewitheachitemandhowtoremoveitfromInbox?

Interneta. E-mail b. E-mail managementc. Four Ds for Decision-Makingd.

____________isastandardfordescribingdifferenttypesofinformation.5. MIMEa. Serverb. E-mailc. Newgroupsd.

_________isbasicallyanelectronicbulletinboard.6. MIMEa. Usenetb. Serverc. E-maild.

Whichof the following consists of a set of “newsgroups”withnames that are classifiedhierarchicallyby7. subject?

MIMEa. E-mailb. Serverc. Usenetd.

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Groupsofpeoplehavingsimilarinterestarecalled_____________.8. useneta. MIMEb. mailing listc. serverd.

Which of the following is the facility for a real time (on-line) communication with one to one or one to many 9. computers?

Mailing lista. Newgroupsb. Chatc. Usenetd.

Whichofthefollowingcanbedefinedasatemporarycollaborativenetworkofagroupofprofessionalssuch10. ascreativedesigners,manufacturers,suppliers?

Collaboration multimedia computinga. Virtual corporationb. Conferencingc. Audi and video streamingd.


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Chapter IV

World Wide Web

Aim


introduce the WWW•

describe the web browser•

highlight the methods of searching WWW•

Objectives


elucidatebrowsingandsurfing•

explain web page installation •

explicate plug-ins•

Learning outcome


understand search engines•

comprehend directories•

enlist the various sear• ching strategies

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4.1 Introduction to WWWWorld Wide Web (WWW) is an advanced information recovery system. Currently, it is mostly in an experimental stage, but it is being developed rapidly. It supports more types of gopher such as graphs, pictures and colours, provided the user’s devices support them. In a sense, WWW competes with the Gopher information system. Notice that, using WWW you can also access information in Gopher (and in FTP servers, Usenet news, etc.). Voice can also be delivered, if the user’s device has a sound generator. WWW can also be used on a simple terminal, but then pictures are replaced by just a notation like [IMAGE].

WWW is based on hypertext, which means, among other things, that when the user is navigating on the ocean •of information he can pick up an interesting word or expression within a text and request for more information about it. This does not apply to all words in a text but only to those who have been properly designated as such by the producer of the information and which are displayed on screen. In practise the use of WWW is still largely similar to the use of simpler, menu-driven information systems.InmostUnixmachinesoftheComputingCentre,WWWcanbestartedbythecommand“www”whichselects•the proper mode of operation according to the characteristics of user’s device.Youwill first see theHUThomepage inFinnish.To access information inEnglish, select the itemHUT•information in English. Alternatively, you can start WWW so that it gets you directly to the home page in English:wwwhttp://www.hut.fi/English/www.english.html

How to get started?On a simple terminal (actually, when using the lynx program), WWW initially displays a starting page (home page), on which some words or expressions appear as different from normal text, for example, with black and white reversed ortextinboldface.Usingthearrowkeys“up”and“down”,youcanmovefromonesuchtexttoanother.

Afterfindinganinterestingitem,selectitbypressingthereturnkey.WWWthendisplaysanewpage,from•whichyoucanproceedinthesamemanner.Bonvoyage!Whenyouwishtoquit,typeQ.Therearesomemoreinstructions at the bottom of the WWW screen, and more detailed information can be obtained by the Unix command“manlynx”.On a workstation or X terminal (actually, when using the Mosaic program), you operate in principal in the •same manner, but the special words or expressions are displayed underlined, and you can select one of them by moving the cursor to point to such a word and clicking the leftmost button of the mouse. WWW changes the underlining to broken line when you have looked at the information. On top of the window you can access some pull-down menus, for instance the item Exit Program in the File menu.

Some words of warningYou may have to wait, while WWW starts or retrieves a large amount of information from somewhere far away. It may happen that some information is accessible just when you need it, because some computer on the globe is not working or some cable has been cut off. The available information is not a representative sample from the pool of information known to mankind but the result of efforts of a set of people who wish to make information available in this way.

Some hints If you select the item Information Resources outside HUT on the starting page, you will have access to information intheworldwideWWWsystem,inwhichyoucanperhapsbestnavigatebyselectingbySubject.Thenyoucanfindfor instance a course on Esperanto, a large collection of international agreements on protection of environment, more than you will probably ever want to know about Unix, or fresh research reports on high energy physics.


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4.2 Web BrowserThe Internet’s World Wide Web, is a collection of over six billion Web Pages containing virtually all human knowledge (not to mention countless beliefs, opinions, attitudes, misconceptions, delusions, and who-knows-what-else). The program you use to look at these pages is called a Web browser. The best known and most widely used web browser is called Internet Explorer.

Even though there are over six billion pages of information on the Web, they all share certain features designed to make Web browsing easy. Learning to use those features requires only a small set of basic skills, which you can learn in minutes.

Every web page has a URLWhen you dial a mobile phone number, every mobile phone in the world doesn’t ring. Only the phone you called rings because the number you dialled is unique to that phone. Just as every telephone has a unique number, every Web page has a unique address (also called a URL or Uniform Resource Locator). A URL isn’t a number though.

It’s a group of letters separated by dots (full stops), as in these examples:www.google.com•www.silversurfersatbedford.org.uk•bbc.co.uk•

In fact the full addresses of the three examples just quoted are:http://www.google.com•http://www.silversurfersatbedford.org.uk•http://www.bbc.co.uk•

The http:// part is called the protocol. HTTP stands for hypertext transfer protocol. This refers to the method of data transfer that all Web pages use. However it’s not required to type this part when entering a web address since your Internet Explorer will insert it for you.

The next part, which is usually www (for World Wide Web) is called the host name. For many web pages the www isalsooptional.Forexample,youcouldfindtheBBCwebsitebyusingwww.bbc.co.ukorjustbbc.co.uk.Whenin doubt include the www.

Those URLs take you to the home page for a given web site. The home page is a little like the cover of a book. It’s thefirstthingyousee,butthereareplentymorepagesinsidethebook.Eachpage“inside”asitehasalongername.For example, the URL for the BBC Gardening page is: bbc.co.uk/gardening.

Using your browser’s address barTheAddressbaristheplacewhereyousee(andcantype)aWebsite’sURL.FollowingfigureshowswhattheAddress bar looks like in Internet Explorer. The address bar always shows the URL of the page currently being displayed starting with http://.

Fig. 4.1 Address bar(Source:http://www.silversurfersatbedford.org.uk/downloads/intro_web_browsing.pdf)

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The Cursor is the blinking vertical bar that shows where the next thing you type will appear. The cursor is not the same as the mouse pointer (which is the little arrow that moves around on the screen when you move the mouse).

Fig. 4.2 Cursor(Source:http://www.silversurfersatbedford.org.uk/downloads/intro_web_browsing.pdf)

TextthatiscurrentlyhighlightedisreferredtoasSelected.Followingfigureshowsasampleofregulartext,andhow that same text looks when selected.

Fig. 4.3 Selected text(Source:http://www.silversurfersatbedford.org.uk/downloads/intro_web_browsing.pdf)

To select the text simply click on it with the mouse. You can then type in the address of the web site you want to visit.

Typing a new URLSuppose you know the website and the URL of the site which you want to visit. For example, you might have learned it from a TV show or magazine article. To go to this site you have to type the URL into your Web browser’s Address bar.

Before you can type in the Address bar, you have to click on the address bar to get the cursor into the Address bar. Normally,whenyoufirstclickontheAddressbar,theentireaddressthat’salreadyinthebarwillbeselected.Whenyou see selected text you know that any new text you type will instantly replace the selected text. (If you prefer you can press the Delete key on the keyboard at this point to remove the selected text, but you don’t need to. Note: If thefirstlettersoftheWebsiteyouwanttovisitarehttp://thenitisnotnecessarytotypethehttp://part.

If you click anywhere in the address bar only once, all the text will be selected. Now type yahoo.co.uk, that new URL will replace the old URL. So you can just press the Enter key, or click the Go button to the right of the Address bar (if you browser has such a button) and that’s it. You’re at the Web site of that address.

Note:IfthefirstlettersoftheWebsiteyouwanttovisitarehttp://thenit’snotnecessarytotypethehttp://part.

Text

Cursor

Selected Text


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Using Auto CompleteAnother thing you might notice while typing in the Address bar is that when you start typing the URL of a page you’ve visited in the past, similar URLs appear in a drop-down menu. The more you type, the shorter the list becomes,becauseonlyURLswhosefirstlettersmatchwhatyou’vetypedsofarappearinthelist.IfyouhappentonoticethattheURLyouwereabouttotypeisalreadyinthedrop-downmenu,youdon’tneedtofinishtypingtheURL. Instead, just click on the URL in the drop-menu that you want to visit.

Fig. 4.4 Selecting any URL(Source:http://www.silversurfersatbedford.org.uk/downloads/intro_web_browsing.pdf)

Getting back to the previous pageAny time you want to go back to the page you just left, you can click the Back button in your Web browser’s toolbar. TheexactlocationofthatbuttonvariesfromoneWebbrowsertothenext.Followingfigureshowsthelocationofthe Back button (circled in red).

Fig. 4.5 Back button(Source:http://www.silversurfersatbedford.org.uk/downloads/intro_web_browsing.pdf)

Click any URL in the menu to revisit that page

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You can click the Back button repeatedly to retrace your steps. So if you’ve visited four web pages since you started browsing clicking the Back button four times will take you back to each of those pages in turn. This means you need nevergetlostwhileyou’resurfingtheWeb,youcanalwaysfindyourwaybacktowhereyoustarted.

Onceyougetthehangofusinghyperlinks,theBackbutton,andyourWebbrowser’sAddressbar,youshouldfindit pretty easy to get around on the World Wide Web.

4.3 Searching WWWSearching the Internet is now as common place as driving a car and most of the people consider the use of just one search engine to obtain results that they are looking for. There are many excellent resources on the internet to search for information and to discover new knowledge.

There are basically four areas to search for information n the internet:Search engines•Indexes and directories•Intuitive search•Custom search and deep web search•

4.3.1 DirectoriesTheWorldWideWebissuchahugesystemwhereitmightbetrickytoshowonfirstpageofyourlookupcatalogue.It is a prevalent trend of intricate to a web directory to rank good for search engines like Google. Web directories areacceptedasacompetentwaytoobtainqualitybacklinks.KeysearchengineslikeGooglegivemassivebenefitsto the people internet websites which have one-way links from similar web sites.

What are internet directories?Itiseasilythemostprevalentandleastdifficultmethodofaninternetsearchengine.Theyareutilisedforalongperiod as things are the way to getting quality back links. The aim of these QuickBurn sites is to trade Philippines products and solutions or other support provided by the directory. These back links are created for hoping at higher PR (page rank) on search engines like Google.

The two main varieties of internet directories are:Standard sites: They have got listing of sites in greater areas. They can’t concentrate on certain subjects.•Specialised niche sites: They pay attention to precise matters. How many areas might be a lesser amount of but •it’ll be remarkably relevant to this subject matter.

Need of directoriesDirectories are just human being researched so it’s vital to get quality internet websites inside of distinct areas. The main issue for the achievements of these sites is the link popularity. The web link can help programme improve the visitors to your internet site only for those who have a fantastic link popularity. It enables a very high rank in your web site on the search engines. Thus, it will be important to upload your website towards web directory. It is usually the chance that the visitors from many sites may very well be minor but a few of the appropriate inbound backlinks aimed at your web can boost your entire search engine optimisation link popularity.

PopularityThe sites are more popular among totally free backlinks. Absolutely everyone seeks just about any back links as well asthesitesclearuptheirrequirementquickly.Yourdirectorymanagerseventuallyfindnewoptionsforbuildingearnings off their sites.

Itisvitaltobeawareofextrapriortointricateyourinternetsitetoadirectory.Themostbeneficialsitesare•search engine optimisation favourable sites which may have not for-mutual or one-way backlinks. Those sites which don’t scribe the extrovert backlinks guide your internet site to rank higher on the search engines.


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Don’tsetafulldropbypostingtosites.Itmustfulfiltheneedsyouhaveofacceleratingprimaryvisitorsor•otherwise not an outstanding link back. Thus, this stuff has to be viewed prior to posting to barefoot jogging. Ifyoufindthatithelpsinthenyoudefinitelydonothesitatetouploadyourinternetsite.Preserveacheckforyourefficiencyorhigherdateyourinternetsitewhendemanded.

4.3.2 Search EnginesInternetsearchenginesarespecialsitesontheWebthataredesignedtohelppeoplefindinformationstoredonothersites. There are differences in the ways various search engines work, but they all perform three basic tasks:

They search the Internet - or select pieces of the Internet - based on important words.•Theykeepanindexofthewordstheyfind,andwheretheyfindthem.•They allow users to look for words or combinations of words found in that index.•

Early search engines held an index of a few hundred thousand pages and documents, and received maybe one or two thousand inquiries each day. Today, a top search engine will index hundreds of millions of pages, and respond to tens of millions of queries per day. In this article, we’ll tell you how these major tasks are performed, and how InternetsearchenginesputthepiecestogetherinordertoletyoufindtheinformationyouneedontheWeb.

History of search enginesThe concept of hypertext and a memory extension really came to life in July of 1945, when after enjoying the scientificcamaraderiethatwasasideeffectofWWII,VannevarBush’sAs We May Think was published in The Atlantic Monthly. He urged scientists to work together to help build a body of knowledge for all mankind. He then proposed the idea of a virtually limitless, fast, reliable, extensible, associative memory storage and retrieval system. He named this device as memex.

Gerard Salton (1960s - 1990s)Gerard Salton, who died on August 28th of 1995, was the father of modern search technology. His teams at Harvard and Cornell developed the SMART informational retrieval system. Salton’s Magic Automatic Retriever of Text included important concepts like the vector space model, Inverse Document Frequency (IDF), Term Frequency (TF), term discrimination values, and relevancy feedback mechanisms. He authored a 56 page book called A Theory of Indexing which does a great job explaining many of his tests upon which search is still largely based. Tom Evslin posted a blog entry about what it was like to work with Mr. Salton.

Ted NelsonTed Nelson created Project Xanadu in 1960 and coined the term hypertext in 1963. His goal with Project Xanadu was to create a computer network with a simple user interface that solved many social problems like attribution. While Ted was against complex markup code, broken links, and many other problems associated with traditional HTMLontheWWW,muchoftheinspirationtocreatetheWWWwasdrawnfromTed’swork.Thereisstillconflictsurrounding the exact reasons why Project Xanadu failed to take off.

4.3.3 Meta Search EnginesMetadata in its broadest sense is data about data. The familiar library catalogue record could be described as metadata in that the catalogue record is ‘data about data’. Similarly database records from abstracting and indexing services are metadata. However the term metadata is increasingly being used in the information world to specify records, which refer to digital resources available across a network.

This means a metadata record refers to another piece of information capable of existing in a separate physical •form from the metadata record itself. Metadata also differs from traditional catalogue data in that the location information is held within the record in such a way as to allow direct document delivery from appropriate application software, in other words the record may well contain detailed access information and the network address.

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A metasearch engine queries two or more search engines at the same time. It sends the results from the search •engines back to you. Metasearch engines do not have their own database or index web pages. They send their queries to search engines. The results from each search engine are combined. Duplicates are removed or merged. Pages are sometimes ranked in order of importance. Metasearchenginesaregoodforfindinginformationquickly.Theyarebestwhenkeywordsareused.Youcanuse•metasearchenginestofindoutwhichsearchengineshavetheinformationyouwant.Metasearchenginesdonotreturn all the pages found. They only return the top ten or so pages. Metasearch engines use simple queries.Most of these engines work on the principle of taking the highest ranking hits from the various engines they pass •their requests on to, limiting that selection either by number of bits or sometimes by time elapsed in response. Results can then usually be grouped either by site, keyword, or other parameters, allowing the user to easily analyse what has appeared where and how it has been ranked. This is a very easy way of broadening coverage but minimising the effect of massive recall killing off precision: key: sites will hopefully appear in more than onesystemand,thus,beflaggedup.Butlesser-knownsitesshouldstillappearonatleastonesystemnearthetop if truly relevant.

4.3.4 Searching StrategiesBecausetheWebisnotindexedinanystandardmanner,findinginformationcanseemdifficult.Searchenginesarepopular tools for locating web pages, but they often return thousands of results. Search engines explore the Web andlogthewordsfromthewebpagestheyfindintheirdatabases.Becausesomesearchengineshaveloggedthewords from over 1 billion documents, results can be overwhelming. Without a clear search strategy, using a search engineislikewanderingaimlesslyinthestacksofalibrarytryingtofindaparticularbook.

Successful searching involves two key steps. First, you must have a clear understanding of how to prepare your search. You must identify the main concepts in your topic and determine any synonyms, alternate spellings, or variant word forms for the concepts. Second, you need to know how to use the various search tools available on the Internet. For example, search engines (for example, AltaVista) are very different than subject directories (for example, Yahoo). Evensearchenginesthemselvescanvarygreatlyinsize,accuracy,features,andflexibility.

Subject directoriesA subject directory is a catalogue of sites collected and organised by humans. Subject directories are often called subject“trees”becausetheystartwithafewmaincategoriesandthenbranchoutintosubcategories,topics,andsubtopics.TofindthehomepagefortheAtlantaBravesatYahoo!,forexample,select“Recreation&Sports”atthetoplevel,“Sports”atthenextlevel,“Baseball”atthethirdlevel,“MajorLeagueBaseball”atthefourthlevel,“Teams”atthefifthlevel,thenfinally“AtlantaBraves.”

Becausehumansorganisethewebsitesinsubjectdirectories,youcanoftenfindagoodstartingpointifyourtopicisincluded.Directoriesarealsousefulforfindinginformationonatopicwhenyoudon’thaveapreciseideaofwhat you need. Many large directories include a keyword search option which usually eliminates the need to work through numerous levels of topics and subtopics.

Because directories cover only a small fraction of the pages available on the Web, they are most effective for findinggeneralinformationonpopularorscholarlysubjects.Ifyouarelookingforsomethingspecific,useasearchengine.

Search enginesSearch engines are very different from subject directories. While humans organise and catalogue subject directories, search engines rely on computer programs called spiders or robots to crawl the Web and log the words on each page.Withasearchengine,keywordsrelatedtoatopicaretypedintoasearch“box.”Thesearchenginescansitsdatabaseandreturnsafilewithlinkstowebsitescontainingthewordorwordsspecified.Becausethesedatabasesareverylarge,searchenginesoftenreturnthousandsofresults.Withoutsearchstrategiesortechniques,findingwhatyouneedcanbelikefindinganeedleinahaystack.


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To use search engines effectively, it is essential to apply techniques that narrow results and push the most relevant pages to the top of the results list. Below are a number of strategies for boosting search engine performance. When a“practice”linkappears,clickonthelinktopracticethetechniquewithAltaVista’ssearchengine.

Identify keywordsWhenconductingasearch,breakdownthetopicintokeyconcepts.Forexample,tofindinformationonwhattheFCChassaidaboutthewirelesscommunicationsindustry,thekeywordsmightbe:“FCCwirelesscommunication”

Boolean ANDConnecting search terms with AND tells the search engine to retrieve web pages containing ALL the keywords. “FCCandwirelessandcommunication”

The search engine will not return pages with just the word FCC. Neither will it return pages with the word FCC and the word wireless. The search engine will only return pages where the words FCC, wireless, and communication all appear somewhere on the page. Thus, AND helps to narrow your search results as it limits results to pages where all the keywords appear.

Boolean ORLinking search terms with OR tells the search engine to retrieve web pages containing ANY and ALL keywords. “(FCCorwirelessorcommunication)”

When OR is used, the search engine returns pages with a single keyword, several keywords, and all keywords. Thus, OR expands your search results. Use OR when you have common synonyms for a keyword. Surround OR statements with parentheses for best results. To narrow results as much as possible, combine OR statements with AND statements. For example, the following search statement locates information on purchasing a used car: “(carorautomobileorvehicle)and(buyorpurchase)andused”

Boolean AND NOTANDNOTtellsthesearchenginetoretrievewebpagescontainingonekeywordbutnottheother“dolphinsandnot Miami”

The above example instructs the search engine to return web pages about dolphins but not web pages about the “MiamiDolphins”footballteam.UseANDNOTwhenyouhaveakeywordthathasmultiplemeanings.Theneedfor AND NOT often becomes apparent after you perform an initial search. If your search results contain irrelevant results(forexample,SaturnthecarratherthanSaturntheplanet),considerusingANDNOTtofilterouttheundesiredwebsites.

Implied boolean:plus and minusIn many search engines, the plus and minus symbols can be used as alternatives to full Boolean AND and AND NOT. The plus sign (+) is the equivalent of AND, and the minus sign (-) is the equivalent of AND NOT. There is no space between the plus or minus sign and the keyword.

NOTE: AltaVista’s Simple Search requires the use of plus and minus rather than AND, OR, and AND NOT.

+welding +process+Saturn -carcouch sofa

IMPORTANT: Use AltaVista’s Simple Search for implied Boolean (+/-) searches, and use AltaVista’s Advanced Search for full Boolean (AND, OR, AND NOT) searches.

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Phrase searchingSurrounding a group of words with double quotes tells the search engine to only retrieve documents in which those wordsappearside-by-side.Phrasesearchingisapowerfulsearchtechniqueforsignificantlynarrowingyoursearchresults, and it should be used as often as possible.

“JohnF.Kennedy”“WaltDisneyWorld”“globalwarming”

For best results, combine phrase searching with implied Boolean (+/-) or full Boolean (AND, OR, and AND NOT) logic.

+”heart disease” +cause“heartdisease”andcause

The above example tells the search engine to retrieve pages where the words heart disease appears side-by-side and the word cause appears somewhere else on the page.

NOTE ON IMPLIED BOOLEAN LOGIC (+/-): When a phrase search is combined with additional keywords using implied Boolean logic (+/-), you must put a plus or minus sign before the phrase as well as the other keywords. Ifthesearchinvolvesaphrasewithnoadditionalkeywords(e.g.,“WaltDisneyWorld”),theplussignbeforethequotes is optional.

Plural forms, capital letters, and alternate spellingsMost search engines interpret lower case letters as either upper or lower case. Thus, if you want both upper and lower case occurrences returned, type your keywords in all lower case letters. However, if you want to limit your results to initialcapitalletters(forexample,“GeorgeWashington”)oralluppercaseletters,typeyourkeywordsthatway.

Like capitalisation, most search engines interpret singular keywords as singular or plural. If you want plural forms only, make your keywords plural.

A few search engines support truncation or wildcard features that allow variations in spelling or word forms. The asterisk (*) symbol tells the search engine to return alternate spellings for a word at the point that the asterisk appears. For example, capital* returns web pages with capital, capitals, capitalise, and capitalisation.

Title searchField searching is one of the most effective techniques for narrowing results and getting the most relevant websites listedatthetopoftheresultspage.Awebpageiscomposedofanumberoffields,suchastitle,domain,host,URL,andlink.SearchingeffectivenessincreasesasyoucombinefieldsearcheswithphrasesearchesandBooleanlogic.Forexample,ifyouwantedtofindinformationaboutGeorgeWashingtonandhiswifeMartha,youcouldtrythefollowing search:

+title:”George Washington” +President +Marthatitle:”George Washington” and President and Martha

The above TITLE SEARCH example instructs the search engine to return web pages where the phrase George Washington appears in the title and the words President and Martha appear somewhere on the page. Like plus and minus, there is no space between the colon (:) and the keyword.

Domain searchInadditiontothetitlesearch,otherhelpfulfieldsearchingstrategiesincludethedomainsearch,thehostsearch,thelink search, and the URL search. The DOMAIN SEARCH allows you to limit results to certain domains such as websites from the United Kingdom (.uk), educational institutions (.edu), or government sites (.gov).


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+domain:uk +title:”Queen Elizabeth”domain:uk and title:”Queen Elizabeth”

+domain:edu +”lung cancer” +smok*domain:eduand“lungcancer”andsmok*

Host searchTheHOSTSEARCHcomesinhandywhenyouneedtofindsomethinglocatedatalargesitethatdoesnothavean internal search engine. With this search technique, you can search all the pages at a website (contained in the engine’s database) for keywords or phrases of interest.

NOTE: Because the major search engines do not always log an entire website, use an internal search engine, if the website has one, for best results.

+host:www.disney.com +”special offer”host:www.disney.comand“specialoffer”

URL searchThe URL SEARCH limits search results to web pages where the keyword appears in the URL or website address. A URL search can narrow very broad results to web pages devoted to the keyword topic.

+url:halloween +title:storiesurl:halloween and title:stories

Link searchUse the LINK SEARCH when you want to know what websites are linked to a particular site of interest. For example, if you have a home page and you are wondering if anyone has put a link to your page on their website, use the Link search. Researchers use link searches for conducting backward citations.

link:www.pepsi.comlink:www.ipl.org/ref/

Preparing for searchByspendingafewminutesclarifyingyoursearch,youcanincreaseyourchancesoffindingwhatyouneedfastand effectively.

Step1:StatewhatyouwanttofindFirst,inoneortwosentences,statewhatyouwanttofindontheInternet.Forexample:

Iwanttofindinformationonpopularmethodsoflosingweight.•Whatarethecharacteristicstolookforwhenpurchasingadiamond?•WhendotheMonarchbutterfliesmigrate?•

Step 2: Identify keywordsNext, underline the main concepts in the statement.

Iwanttofindinformationonpopularmethodsoflosingweight.•Whatarethecharacteristicstolookforwhenpurchasingadiamond?•WhendotheMonarchbutterfliesmigrate?•

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Step 3: Select synonyms and variant word formsList synonyms, alternate spellings, and variant word forms of each keyword

popular common favourite•methods method ways way techniques technique•losing lose reducing reduce reduction•weight fat dieting diet•

Step 4: Combine synonyms, keywords, and variant word formsCombine synonyms with Boolean OR.

NOTE: Place parentheses around OR statements.(popular or common or favourite)•(methods or method or ways or way or techniques or technique)•(losing or lose or reducing or reduce or reduction)•(weight or fat or dieting or diet)•

Use truncation with an asterisk symbol (*) to combine variant word forms.(popular or common or favourite)•(method* or way* or technique*)•(los* or reduc*)•(weight or fat or diet*)•

Combine keywords with Boolean AND.(popular or common or favourite) and•(method* or way* or technique*) and•(los* or reduc*) and•(weight or fat or diet*)•

Step 5: Check your spellingSearch engines return websites with words that match your keywords. If you misspell a keyword, your results will contain websites where that word is also misspelled.

4.4BrowsingandSurfingThewords“Browsing”or“Surfing”areusedtodescribetheprocessoflookingatdocuments,websitesandwebpages on the Internet. As mentioned earlier you will need to use a Web Browser for this.

Many people will use Internet Explorer, which is the Microsoft Browser that is supplied with most PCs, but there are alternative (some say better) solutions such as Firefox and Opera.

Browsing behaviour differs from person to person. To access a website you can either type the domain name (the website address – more later) of the website directly into the address bar or you can use a search engine to search for the site using the business name or some other keywords that you know can be found on the website.

For example let’s say you are looking for information about buying a house. You may decide to enter buying a house into the Google search window. At the time of writing this brings up almost 45 million results. Let’s say you wanted tonarrowthatdown.Onewayofdoingthiswouldbeputquotationmarksroundthesearchtermthus,“buyingahouse”. This reduces the results to about 2 million.


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What this does is display only results where these three words are found together and in the order submitted. In the firstsearchtheresultswillbeforwebsiteswherethethreewordsappearanywhereonthepage.

Thisisjustanexampleofthemanytechniquesthatcanbeusedtoensurethatyoufindwhatyouarelookingforusing a search engine. Google and the other search engines provide detailed information on how they should be used to the best advantage. It is important that small businesses maximise their productive time and much of today’s research is carried out online so it is well worth taking the time to learn the tricks of searching.

4.5 Web Page InstallationYou can install the entire web site on your own computer by doing one of the following:

Ifyouareinstallingfromthe‘official’CD:Makesureyouhave100MBfreediskspace.Thenjustcopythe•entire folder livatl2 (and its subfolders) onto your hard disk. It can be copied to any disk letter (for example, C:, D:, or E:), but you must copy it to the top level of your chosen disk (for example, C:\) so that the opening fileis,forexample,‘c:\livatl2\index.htm’.YoudoNOTneedtocopythebigzipfilescalledlivatl2down.ziporlivatlreports.zip.If you are installing over the web, it’s a bit more complicated, and you will need to follow these steps:•

Step 1: Read all these instructions before you do anything else, so you know what you are letting yourself �in for. Then make sure you have at least 100MB free on your hard disk. Step2:Downloadthefileswithallthewebpagesinthembyclickingonthefilename:livatl2down.zip.Note �thatthisisalargefile(about7MB)andcouldtakeahourortwotodownloadifyouareusingamodem.Step3:OpenthezipfileyouhavejustdownloadedinWinziporequivalentdecompressionsoftware.You �shouldbeabletodothisbyclickingonthefileinExplorer.Step4:ExtractalltheAtlasfilesfromthezipfiletoyourdiskandspecifythetopleveldirectory(e.g.‘c:\’). �Makesurethatyoutellwinzipto‘usefoldernames’.TheAtlasfilesshouldthenbeplacedintoafoldercalled ‘c:\livatl2’, as well as a series of subfolders. You can change the main folder name from ‘livatl2’ to another if you like, but don’t change any of the subfolder names.Step5:ThesummarydocumentandreferencedocumentfilesareNOTincludedinthewebsitezipfileto �keepthefilesizedown,IfyouwanttheAtlassummarydocument,downloaditnow(7MB)andputitinthesamefolderastheotherwebsitefiles(firexample,c:\livatl2\).IfyouwanttheReferencereports,downloadlivatlreports.zip(25MB),andunpackthefilesinto\livatl2\reports.Ifyoudecidenottodownloadthesefiles,the website will still work, but the ‘download’ links to the documents will not. Step6:Openthefileindex.htm(whichshouldbein‘c:/livatl2/index.htm’)usingabrowsersuchasNetscape �or Internet Explorer and enjoy.

Updates: Updates will also be available periodically, which you can download and install to keep up with our •progress.

4.6 Plug-insAs the name implies, a plug-in is an addition to an application that can be added to it after installation. Browsers use these to increase functionality. The reason for not being a standard part of the application varies. Often, the ability tohandleaplug-ingivestheapplicationmoreflexibilitythanitwouldhaveifeverythingwerejustmadeastandardpart of the basic program. Firefox supports so many plug-ins, that if they were all in the basic script, it would be too huge. Most users choose a few, not all.

Plug-ins are usually not needed as much as wanted. I want to view certain web-based goodies like video •presentations. A word of caution,plug-ins must be downloaded and installed. Like anything else, they can be a source of malware. Get them only from trusted places, scan with your security products before installing.Plug-ins are software modules that add to the functionality of an application. Many applications use plug-ins, •including Photoshop, and web browsers such as Firefox and Internet Explorer.

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Plug-ins can have many different functions. Web browsers typically use plug-ins to expand the range of formats •they can display (e.g., Acrobat documents, QuickTime or Adobe Flash content). When the web browser encounters a format it doesn’t support, it looks for a plug-in that does. A plug-in can launch its own viewer, appear within a browser window, appear in an embedded frame (within a window that may also contain HTML), or run in the background. Plug-ins work in similar ways with other kinds of programs.

How you install a plug-in depends on both the parent application and the plug-in itself. In many cases, the directory or folder where you place your plug-in(s) may have an installer. For more information, consult the documentation for both the plug-in and the application.

Formoreinformationaboutspecificplug-ins,visitoneofthesesites:Firefox•Mozilla•Thunderbird•Adobe Photoshop and other Adobe products•BBEdit (text editor)•

Note: Not all plug-ins are compatible with all browsers. Always check a plug-in’s documentation before trying to use it with your web browser.


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SummaryWorld Wide Web (WWW) is an advanced information recovery system. Currently it is mostly in an experimental •stage, but it is being developed rapidly.WWW is based on hypertext, which means, among other things, that when the user is navigating on the ocean •of information he can pick up an interesting word or expression within a text and request for more information about it.The Internet’s World Wide Web, is a collection of over six billion Web Pages containing virtually all human •knowledge.Searching the internet is now as common place as driving a car and most of the people consider the use of just •one search engine to obtain results that they are looking for.Web directories are accepted as a competent way to obtain quality back links.•Thewords“Browsing”or“Surfing”areusedtodescribetheprocessoflookingatdocuments,websitesand•web pages on the Internet. To access a website you can either type the domain name of the website directly into the address bar or you can •use a search engine to search for the site using the business name or some other keywords that you know can be found on the website.Plug-ins is usually not needed as much as wanted. I want to view certain web-based goodies like video •presentations.Plug-ins are software modules that add to the functionality of an application.•Search engines are very different from subject directories.•Subjectdirectoriesareoftencalledsubject“trees”becausetheystartwithafewmaincategoriesandthenbranch•out into subcategories, topics, and subtopics.

ReferencesGillies, J. and Cailliau, R., 2000. • How the Web was born: the story of the World Wide Web, Oxford University Press.Bullock, L., 2003. • The World Wide Web, Raintree Steck-Vaughn.1101doc, 2003. • What are Plugins? [Online] Available at: <http://www.computerbasicsandbeyond.com/tutorials/plug-ins.html> [Accessed 11 November 2011].Wall, A., • History of Search Engines: From 1945 to Google Today [Online] Available at: <http://www.searchenginehistory.com/> [Accessed 11 November 2011].Korpela, J. K., 1994. • What is WWW?[Online]Availableat:<http://www.cs.tut.fi/~jkorpela/www-eng.html>[Accessed 11 November 2011].bbaker48, 2008. • Info Literacy 9. Browsing & searching the web [Video Online] Available at: <http://www.youtube.com/watch?v=ZBJyhu1GrTI>[Accessed11November2011].Google, 2009. • What is a browser?[VideoOnline]Availableat:<http://www.youtube.com/watch?v=BrXPcaRlBqo>[Accessed 11 November 2011].

Recommended ReadingKaye, K. B. and Medoff, J. N., 2001. • The World Wide Web: A Mass Communication Perspective, McGraw-Hill.Levene, M., 2010. • An Introduction to Search Engines and Web Navigation, 2nd ed., John Wiley and Sons.Jamsa, 2002. • Html & Web Design: Tips & Techniques, Tata McGraw-Hill Education.

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Self Assessment___________competeswiththeGopherinformationsystem.1.

Interneta. HTMLb. WWWc. Usenetd.

Whichofthefollowingisknownasprotocol?2. wwwa. .comb. www.bbc.co.ukc. http://d.

WhichofthefollowingreferstothemethodofdatatransferthatallWebpagesuse?3. HTTPa. HTMLb. WWWc. URLd.

Whichofthefollowingiscalledthehostname?4. HTTPa. HTMLb. wwwc. URLd.

_____________istheblinkingverticalbarthatshowswherethenextthingyoutypewillappear.5. Address bara. Selectedb. AutoCompletec. Cursord.

__________istheplacewhereyousee(andcantype)aWebsite’sURL.6. Address bara. Selectedb. AutoCompletec. Cursord.

Whichofthefollowingstatementsisfalse?7. Before you can type in the Address bar, you have to click on the address bar to get the cursor into the a. Address bar.If you click anywhere in the address bar only once, all the text will be selected.b. There are many excellent resources on the internet to search for information and to discover new c. knowledge.Usenet is accepted as a competent way to obtain quality back links.d.


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Whichofthefollowinghavegotlistingofsitesingreaterareas?8. Specialised niche sitesa. Standard sitesb. Directoriesc. Usenetd.

___________payattentiontoprecisematters.9. Standard sitesa. Directoriesb. Specialised niche sitesc. Usenetd.

Which of the following record refers to another piece of information capable of existing in a separate physical 10. formfromthemetadatarecorditself?

Directoriesa. Metadatab. Search enginesc. Internet d.

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Chapter V

Languages

Aim


introduce the concept of XML•

describe the HTML (Hyper Text Markup Language)•

highlight the concept of dynamic HTML•

Objectives


elucidate JavaScript language•

explain various advantages of XML •

explicate the VRML and its uses•

Learning outcome


understand the elements in HTML documents•

comprehend the technology components of dynamic HTML •

enlist the features of J• avaScript


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5.1 HTML (Hyper Text Markup Language)HTML or Hyper Text Markup Language is designed to specify the logical organisation of a document, with important hypertext extensions. It is not designed to be the language of a WYSIWYG word processor such as Word or WordPerfect. This choice was made because the same HTML document may be viewed by many different “browsers”,ofverydifferentabilities.Thus,forexample,HTMLallowsyoutomarkselectionsoftextastitlesorparagraphs, and then leaves the interpretation of these marked elements up to the browser. For example one browser may indent the beginning of a paragraph, while another may only leave a blank line.

HTML instructions divide the text of a document into blocks called as elements. These can be divided into two broadcategories-thosethatdefinehowtheBODYofthedocumentistobedisplayedbythebrowserandthosethatdefineinformation'about'thedocument,suchasthetitleorrelationshipstootherdocuments.ThelastpartofthesectionalsodescribesstandardnamingschemesforHTMLdocumentsandrelatedfiles.

ThedetailedrulesforHTML(thenamesofthetags/elements,howtheycanbeused)aredefinedusinganotherlanguageknownasthestandardgeneralisedmarkuplanguage,orSGML.SGMLiswickedlydifficult,andwasdesignedformassivedocumentcollections,suchas repairmanuals forF-16fighters,ormaintenanceplansfornuclearsubmarines.Fortunately,HTMLismuchsimpler!

However, SGML has useful features that HTML lacks. For this reason, markup language and software experts have developed a new language, called XML (the extensible markup language) which has most of the most useful features of HTML and SGML.

Elements in HTML documentsThe HTML instructions, along with the text to which the instructions apply, are called HTML elements. The HTML instructionsarethemselvescalledtags,andlooklike<element_name>--thatis,theyaresimplytheelementnamesurrounded by left and right angle brackets.

Mostelementsmarkblocksofthedocumentforparticularpurposeorformatting:theabove<element_name>tagmarksthebeginningofsuchassection.Theendofthissectionisthenmarkedbytheendingtag</element_name>--notetheleadingslashcharacter“/”thatappearsinfrontoftheelementnameinanendtag.End,orstoptagsarealways indicated by this leading slash character.

For example, the heading at the top of this page is an H2 element, (a level 2 heading) which is written as: <H2> 2.1 Elements in HTML </H2>.

Empty elementsSome elements are empty - that is, they do not affect a block of the document in some way. These elements do not require an ending tag. An example is the <HR> element, which draws a horizontal line across the page. This element would simply be entered as <HR>

Upper and lower caseElement names are case insensitive. Thus, the horizontal rule element can be written as any of <hr>, <Hr> or <HR>.

Elements can have attributesMany elements can have arguments that pass parameters to the interpreter handling this element. These arguments are called attributes of the element. For example, consider the element A, which marks a region of text as the beginning (orend)ofahypertextlink.Thiselementcanhaveseveralattributes.Oneofthem,HREF,specifiesthehypertextdocument to which the marked piece of text is linked. To specify this in the tag for A you write:

<AHREF=”http://www.somewhere.ca/file.html”>markedtext</a>

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where the attribute HREF is assigned the indicated value. Note that A element is not empty, and that it is closed by the tag </a>. Note also that end tags never take attributes - the attributes to an element are always placed in the start tag.

HTML document structureHTML documents are structured into two parts, the HEAD, and the BODY. Both of these are contained within the HTML element - this element simply denotes this as an HTML document.

The head contains information about the document that is not generally displayed with the document, such as its TITLE. The BODY contains the body of the text, and is where you place the document material to be displayed. Elements allowed inside the HEAD, such as TITLE, are not allowed inside the BODY, and vice versa.

Following is the example of document structure.<HTML><HEAD><TITLE> Environmental Change Project </TITLE></HEAD><BODY><h1> Environmental Change Project </h1>

Welcome to the home page of the Environmental Change Project. This project is different from other projects with similar names. In our case we actually wish to change the climate. For example, we would like hot beaches in Northern Quebec, and deserts near Chicago.

<p>So how will we do this. Well we do the following<ul><li><A HREF=”burn.html”>Burn</A> more forests.<li>Destroy the <A HREF=”http://who.zoo.do/ozone.html”>Ozone</A> layer.<li>Birth more <A HREF=”ftp:foo.do.do/cows.gif”>cows</a></ul>

</BODY> </HTML>

Versions of HTMLHTMLisanevolvinglanguage,andeachnewversionisgivenanumber.ThefirstdefinitiveversionwasHTML2.0 - this had most of the elements we know and love, but was missing some of the Netscape/Microsoft extensions, and did not support tables, or ALIGN attributes.

HTML 3 (late 1995) was an ambitious effort on the part of Dave Raggett to upgrade the features and utility of HTML. However,itwasnevercompletedorimplemented,althoughmanyfeatureswereintegratedinthenext“official”version of HTML, known as HTML 3.2.

HTML3.2wasthenextofficialversion,integratingsupportforTABLES,image,headingandotherelementALIGNattributes,andafewotherfinickydetails.HTML3.2isthecurrent“universal”dialect-essentiallyallbrowsersunderstand HTML 3.2. IT was, however, missing some of the Netscape/Microsoft extensions, such as FRAMEs, EMBED and APPLET. Support for these (after a fashion) came in HTML 4.0


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HTML4.01isthecurrentofficialstandard.Itincludessupportformostoftheproprietaryextensions,plussupportfor extra features (Internationalised documents, support for Cascading Style Sheets, extra TABLE, FORM, and JavaScript enhancements), that are not universally supported. Some of these enhancements are not discussed in these online notes. They are discussed in detail in The HTML 4.0 Sourcebook, available in most bookstores.

For more details about the various versions of HTML, you are also referred to the bibliography, which contains referencestothevariousspecifications,andtomyonlineresourcethatdefinesthestructuralrulesofthedifferentHTMLvariants,foundattheURLhttp://www.utoronto.ca/webdocs/HTMLdocs/HTML_Spec/html.htmldocuments.

5.2 Dynamic HTMLDynamic HTML (DHTML) is a set of innovative features originally introduced in Microsoft Internet Explorer 4.0. By enabling authors to dynamically change the rendering and content of a Web page as the user interacts with it, DHTML enables authors to create visually compelling Web sites without the overhead of server-side programs or complicated sets of controls to achieve special effects.

WithDHTML,youcaneasilyaddeffectstoyourpagesthatpreviouslyweredifficulttoachieve.

For example, you can:Hide content until a given time elapses or the user interacts with the page.•Animate text and images in your document, independently moving each element from any starting point to any •ending point, following a predetermined path or one chosen by the user.Embed a ticker that automatically refreshes its content with the latest news, stock quotes, or other data.•Use a form to capture user input, and then instantly process and respond to that data.•

DHTML achieves these effects by modifying the in-memory representation of the current document and automatically reformatting it to show changes. It does not reload the document, load a new document, or require a distant server to generate new content. Instead, it uses the user’s computer to calculate and carry out changes. This means a user does not wait for text and data to complete time-consuming round-trips to and from a server before seeing the results. Furthermore, DHTML does not require additional support from applications or embedded controls to make changes. Typically, DHTML documents are self-contained, using styles and a script to process user input and directly manipulate the HTML elements, attributes, styles, and text of the document.

In short, DHTML eliminates the shortcomings of static pages. You can create innovative Web sites, on the Internet or onanintranet,withouthavingtosacrificeperformanceforinteractivity.NotonlydoesDHTMLenhancetheuser’sperception of your documents, it also improves server performance by reducing requests to the server.

Technology componentsThe major components of dynamic HTML technology are:Style sheets (NS) (MS) let you specify the stylistic attributes of the typographic elements of your web page. They let you change the colour, size, or style of the text on a page without waiting for the screen to refresh.

Content positioning (NS) (MS) lets a web developer animate any element on a web page, moving pictures, text, and objects at will. It lets you ensure that pieces of content are displayed on the page exactly where you want them to appear, and you can modify their appearance and location after the page has been displayed.

Dynamic content (MS) actually changes the words, pictures, or multimedia on a page without another trip to the web Server. Data binding (MS) lets you get all the information you need to ask questions, change elements, and get results without going back to the web server. Downloadable fonts (NS) let you use the fonts of your choice to enhance the appearance of your text. Then you can package the fonts with the page so that the text is always displayed with your chosen fonts.

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Scripting languagesScripts that are executed when a document is loaded may be able to modify the document’s contents dynamically. Theabilitytodosodependsonthescriptinglanguageitself(e.g.,the“document.write”statementintheHTMLobject model supported by some vendors).

JavaScript is often used to create dynamic HTML documents. One of the more practical things that JavaScript does atthistimeisincreasetheaestheticsandfriendlinessofwebsitesbyaddingauthor-specifiedusereventstostaticpages. For example, JavaScript allows the page author to embed into page statements which allow user response to certain common events such as when you move the mouse cursor over a link.

The following example illustrates how scripts may modify a document dynamically. The following script:<SCRIPT type=”text/javascript”> document.write(“<b>Date:<\/b>“) document.write(Date())</SCRIPT>

5.3 Java Script LanguageJavaScript is a scripting language, and scripting languages are easier to learn and use than traditional programming languages. JavaScript works on the client side, which means that it runs on the user’s computer and not on the Web server. The browsers interpret JavaScript statements embedded directly in an HTML page.

JavaScript is designed for use on Web pages and is closely integrated with HTML. JavaScript statements embedded in an HTML page can recognise and respond to User Events such as Mouse Clicks, Form Input, and Page Navigation.

For example, you can write a JavaScript function to verify that users enter valid information into a form requesting a telephone number or zip code. Without any network transmission, an HTML page with embedded JavaScript can interpret the entered text and alert the user with a message dialog if the input is invalid. Or you can use JavaScript toperformanaction(suchasplayanaudiofile,executeanapplet,orcommunicatewithaplug-in)inresponsetothe user opening or exiting a page.

Following are the features of JavaScript

A scripting languageScripting languages have been in use long before the Web came around. In Unix environment, scripts have been •used to perform repetitive system administration tasks and to automate many tasks for less computer-literate users. In addition, scripting languages are the basis of much of the cgi-bin programming that is currently used to add limited form of interactivity to Web pages.Of course, this still doesn’t tell what the main advantages of scripting languages are. Like all scripting languages, •JavaScriptisinterpreted,whichprovidesaneasydevelopmentprocess;itcontainsalimitedandeasy-to-learncommandsetandsyntax;anditisdesignedforperformingawell-definedsetoftasks.

Designed for simple, small programs

Because JavaScript is a scripting language, it is well suited to implementing simple, small programs. For instance, •JavaScript would ideally be suited to developing a unit conversion calculator between miles and kilometers or pounds and kilograms. These tasks can be easily written and performed at acceptable speeds with JavaScript and would be easily •integrated into a Web page. A more robust language such as Java would be less suitable for the quick development and easy maintenance of these types of applications.


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By contrast, JavaScript would not be well suited to implementing a distributed CAD document display and •manipulation environment. While eventually JavaScript will be a tool for integrating this type of Java applet orplug-inintoaWebpage,toattempttodeveloptheactualappletinJavaScriptwouldatbest,difficultandinefficientand,morelikely,wouldbeimpossible.

Performs repetitive tasks

Just as JavaScript is suited to producing small programs, it is especially well designed for repetitive, event-•invokedtasks.Forexample,JavaScriptisidealforcalculatingthecontentofonfieldinaformbasedonchangestothedatainanotherfield.Eachtimethedatachanges,theJavaScriptprogramtohandletheeventisinvoked,andthenewdatafortheotherfieldiscalculatedanddisplayed.

Designed for programming user events

Because of the way in which JavaScript is integrated into the browser and can interact directly with the HTML •pages, JavaScript makes it possible to program responses to user events such as mouse clicks and data entry in forms.For instance, a JavaScript script could be used to implement a simple help system. Whenever the user points •a button or a link on the page, a helpful and informative message can be displayed in the bar at the bottom of the browser window.This adds interactivity to Web pages, makes forms dynamic, and can decrease the bandwidth requirements and •server load incurred by using forms and CGI programming.

Easy debugging and testing

Like other scripting languages, JavaScript eases development and trouble-shooting because it is not compiled. •It is easy to test program code, look at the results, make changes, and test it again without the overhead and delay of compiling.

Live connect

Live connect enables communication between JavaScript and Java applets in a page and between JavaScript and •Plug-ins loaded on a page. JavaScript can trigger events in Java applets, and Java applets can call JavaScript methods and functions.

Strengths of JavaScript JavaScript offers several strengths to the programmer including a short development cycle, ease of learning, and small size scripts. These strengths mean that JavaScript can be easily and quickly used to extend HTML pages already on the web.

Quick development: because JavaScript does not require time-consuming compilation, scripts can be developed in •a relatively short period of time. This is enhanced by the fact that most of the interface features, such as dialogue boxes, forms, and other GUI elements, are handled by the browser and HTML code. JavaScript programmers don’t have to worry about creating or handling these elements of their applications.Easy to learn: while JavaScript may share many similarities with Java, it doesn’t include the complex syntax •and rules of Java. By learning just a few commands and simple rules of syntax, along with understanding the way objects are used in JavaScript, it is possible to begin creating fairly sophisticated programs.Platform independence: Because the WWW, by its very nature, is platform-independent, JavaScript programs •createdforthebrowsersarenottiedtoanyspecifichardwareplatformoroperatingsystem.Thesameprogramcode can be used on any platform for which a browser is available.Small overhead: JavaScript programs tend to be fairly compact and are quite small, compared to the binary •applets produced by Java. This minimises storage requirements on the server and download time for the user. Inaddition,becauseJavaScriptprogramsusuallyareincludedinthesamefileastheHTMLcodeforapage,they require fewer network accesses.

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Weakness of JavaScriptAs would be expected, JavaScript has it own unique weaknesses. These include limited set of built-in methods, the inability to protect source code from prying eyes.

Limited Range of Built-in Methods, however, more and more Methods are being introduced in the newer •JavaScript versions.Generally, only Client-Side script•No Code Hiding•

JavaScript statements JavaScript statements enable you to implement logic, looping, and more within your script.


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Statements Description

var The var statement is used to explicitly declare a variable in JavaScript. While technically you do not have to use the var statement in front of a variable to create it. It is good programming practice. Once a variable is declared, you can continue referencing that variable without the var statement in front of it. For example:var x=5x=x+10 //x now contains 15

You can declare multiple variables at once by separating each declaration with a comma:var x, y=10, z=25, dog=”Spotty”

Variable names in JavaScript are case sensitive, so “mydog” and “MYDOG” areconsidered two different variables in JavaScript.

Local versus global scopeWhen you use the var statement outside of any functions, the variable declared is added to the global scope, making it a global variable accessible anywhere inside the page. You can reference this variable inside a function and change it as well from within the function.

When you use the var statement inside of a function, however, you are creating a local variable that’s only visible from within the function. Any changes to this variable is contained within the function only.

Copying variables- by value or by referenceIn JavaScript, when you copy one variable to another, you are either:Copying the value of the original variable to the new variable, creating a 2nd copy of it in the process, orCreating a reference to the original variable, so the new variable merely acts as a pointer to the original.Modifying the newvariable inexplicitly alsomodifies the originalvariable.

The general rule in JavaScript is that primitive variable types (Numbers, Booleans and Strings) are manipulated by value, where as reference type variables (Arrays, objects, and functions) are manipulated by reference. This means if you copy an array to a new variable, you are in fact merely creating a new pointer to the original array. Changes to the new variable will affect the original array as well. For example:var x=[1,2,3]var y=x //”copy” variable x to variable y, which merely creates new pointery[0]=4 //change 1st element of array y to 4

alert(x[0])//alerts4.Arrayx’sfirstelementischangedto4aswell!

IntheaboveIcopyarrayxtoanewvariabley,thenchangearrayy’sfirstelementto4.Sincearraysarereferencetypes,doingsoalsoinexplicitlychangesarrayx’sfirstelementto 4 as well.

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with “with”isatimesavingstatementthatallowsyouto“cache”anobject,soforstatementsthat follow, you no longer need to reference the object again when referring to it.

Syntax:with (object)statement

Example:with (document.form1){field1.value=”test”field2.value=”test2”}

Intheaboveexample,theobject“document.form1”iscached,so“field1”actuallyrefersto“document.form1.field1”.

Table 5.1 JavaScript statements(Source: http://www.javascriptkit.com/jsref/statements.shtml)

5.4 XML (Extended Markup Language)Like HTML, XML (also known as Extensible Markup Language) is a markup language which relies on the concept of rule-specifying tags and the use of a tag-processing application that knows how to deal with the tags. However, XML is far more powerful than HTML.

Thisisbecauseofthe“X”.XMLis“eXtensible”.Specifically,ratherthanprovidingasetofpre-definedtags,asinthecaseofHTML,XMLspecifiesthestandardswithwhichyoucandefineyourownmarkuplanguageswiththeirownsetsoftags.XMLisameta-markuplanguagewhichallowsyoutodefineaninfinitenumberofmarkuplanguagesbaseduponthestandardsdefinedbyXML.

For example, create a new markup language called SCLML (Selena’s Client List Markup Language). This language willdefinetagstorepresentcontactpeopleandinformationaboutcontactpeople.

The set of tags will be simple. However, they will be expressive. Unlike <UL> and <LI> XML tags can be immediately understood just by reading the document.


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<CONTACT><NAME>Gunther Birznieks</NAME><ID>001</ID><COMPANY>Bob’s Fish Store</COMPANY><EMAIL>[email protected]</EMAIL><PHONE>662-9999</PHONE><STREET>1234 4th St.</STREET><CITY>New York</CITY><STATE>New York</STATE><ZIP>Zip: 10024</ZIP></CONTACT>

<CONTACT><NAME>Susan Czigonu</NAME><ID>002</ID><COMPANY>Netscape</COMPANY><EMAIL>[email protected]</EMAIL><PHONE>555-1234</PHONE><STREET>9876 Hazen Blvd.</STREET><CITY>San Jose</CITY><STATE>California</STATE><ZIP>90034</ZIP></CONTACT>

Whatyou see above is a very simple “XMLdocument”.Asyou can see, it looks pretty similar to anHTMLdocument.

It is not enough to simply encode (markup) the data. For the data to be decoded by someone or something else, the encoding markup languages must follow standard rules including:

The syntax for marking up•The meaning behind the markup•

In other words, a processing application must know what a valid markup is (perhaps a tag) and what to do with itifitisvalid?Afterall,howwouldNetscapeknowwhattodowiththeabovedocument?Whatintheworldisa<PHONE>tag?Isitalegaltag?Howshoulditbedisplayed?Ourmarkuplanguagemustsomehowcommunicatethe syntax of the markup so that the processing application will know what to do with it.

InXML,thedefinitionofavalidmarkupishandledbyaDocumentTypeDefinition(DTD)whichcommunicatesthestructureofthemarkuplanguage.TheDTDspecifieswhatitmeanstobeavalidtag(thesyntaxformarkingup).

To specifywhatvalid tagsmean,XMLdocuments are also associatedwith “style sheets”whichprovideGUIinstructions for a processing application like a web browser. A style sheet, the details of which we will discuss later, might specify display instructions such as:

Anytime you see a <CONTACT>, display it using a <UL> tag. Similarly, </CONTACT> tags should be •converted to </UL>All <NAME> tags can be substituted for <LI> tags and </NAME> tags should be ignored.•All <EMAIL> tags can be substituted for <LI> tags and </EMAIL> tags should be ignored.•

Inthisexample,thestylesheetutilisesthefunctionalityofHTMLtodefinetheformattingofSCLML.ButiftheXML document was being processed by a program other than a web browser, the HTML translation step might be bypassed.

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Processing applications combine the logic of the style sheet, the DTD, and the data of the SCLML document and displayitaccordingtotherulesandthedata.NowinsteadofasingleHTMLdocument,whichdefinesthedataand the rules to display the data, we have an SCLML document, a DTD, AND a style sheet. That’s three pieces as opposed to just one.

Further, we need a processing agent that can do the work of putting the DTD, style sheet, and SCLML document together.Webbrowsersaremadetoreadaspecificmarkuplanguage(likeHTML),notanymarkuplanguage.Thatmeans we have three documents to pull together plus one processing program to write or buy. What a mess.

History of XMLXML emerged as a way to overcome the shortcomings of its two predecessors, SGML and HTML which were both verysuccessfulmarkuplanguages,butwhichwerebothflawedincertainways.SGML,theinternationalstandardfor marking up data, has been used since the 80s. SGML is an extremely powerful and extensible tool for semantic markup which is particularly useful for cataloging and indexing data. Like XML, SGML can be used to create an infinitenumberofmarkuplanguagesandhasahostofotherresourcesaswell.

However, SGML is pretty darn complex, especially for the everyday uses of the web. Not only that, but SGML •is pretty expensive. Adding SGML capability to a word processor could double or triple the price. Finally, the commercial browsers made it pretty clear that they did not intend to ever support SGML.HTML on the other hand was free, simple and widely supported. HTML was originally designed at CERN •around1990toprovideaverysimpleversionofSGMLwhichcouldbeusedby“regular”people.Aseveryoneknows,HTMLspreadlikewildfire.Unfortunately, HTML had serious defects that we discussed earlier. So in 1996, discussions began which •focusedonhowtodefineamarkuplanguagewiththepowerandextensibilityofSGMLbutwiththesimplicityof HTML. The World Wide Web Consortium (W3C) decided to sponsor a group of SGML gurus including Jon Bosak from Sun.Essentially, Bosak and his team did to SGML what the Java team had done to C++. All of the non-essential, •unused, cryptic parts of SGML were sliced away. What remained was a lean, mean marking up machine: XML. ThespecificationofXML(writtenmostlybyTimBrayandC.M.Sperberg-McQueen)wasonly26pagesasopposedtothe500+pagesoftheSGMLspecification!Nevertheless,alltheusefulthingswhichcouldbedoneby SGML, could also be done with XML.Over the next few years, XML evolved, drawing from the work of its sponsors and the work of developers solving •similar problems such as Peter Murray-Rust who had been working on CML (Chemical Markup Language) and the consortium of folks working on MathML. By mid 1997 the eXtensible Linking Language XLL project wasunderwayandbythesummerof1997,MicrosofthadlaunchedtheChannelDefinitionFormat(CDF)asoneofthefirstreal-worldapplicationsofXML.Finally,in1998,theW3CapprovedVersion1.0oftheXMLspecificationandanewlanguagewasborn.

Advantages of XMLThefirstbenefitofXMListhatbecauseyouarewritingyourownmarkuplanguage,youarenotrestrictedtoa•limitedsetoftagsdefinedbyproprietaryvendors.Rather than waiting for standard bodies to adopt tag set enhancements (a process which can take quite some •time),orforbrowsercompaniestoadopteachother’sstandards(yeahright!),withXML,youcancreateyourown set of tags at your own pace. Not only are you free to develop at your own pace, but you are free to develop tools that meet your needs exactly.Bydefiningyourowntags,youcreatethemarkuplanguageintermsofyourspecificproblemset!Ratherthan•relying on a generic set of tags which suits everyone’s needs adequately, XML allows every person/organisation to build their own tag library which suits their needs perfectly.Though the majority of web designers do not need tags to format musical notation, medical formula, or •architecturalspecifications,musicians,doctorsandarchitectsmight.


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XMLallowseachspecificindustrytodevelopitsowntagsetstomeetitsuniqueneedswithoutforcingeveryone’s•browser to incorporate the functionality of zillions of tag sets, and without forcing the developers to settle for a generic tag set that is too generic to be useful.TherealpowerofXMLcomesfromthefactthatwithXML,notonlycanyoudefineyourownsetoftags,but•therulesspecifiedbythosetagsneednotbelimitedtoformattingrules.XMLallowsyoutodefineallsortsoftags with all sorts of rules, such as tags representing business rules or tags representing data description or data relationships.Consider again the case of the contact list in SCLML. Using standard HTML, a developer might use something •like the following:

<UL><LI>Gunther Birznieks<UL><LI>Client ID: 001<LI>Company: Bob’s Fish Store<LI>Email:[email protected]<LI>Phone: 662-9999<LI>Street Address: 1234 4th St.<LI>City: New York<LI>State: New York<LI>Zip: 10024</UL><LI>Susan Czigonu<UL><LI>Client ID: 002<LI>Company: Netscape<LI>Email: [email protected]<LI>Phone: 555-1234<LI>Street Address: 9876 Hazen Blvd.<LI>City: San Jose<LI>State: California<LI>Zip: 90034</UL></UL>

Whilethismaybeanacceptablewaytostoreanddisplayyourdata,itishardlythemostefficientorpowerful.Asyou are probably aware, there are many potential problems associated with marking up your data using HTML.

Three particularly serious problems, which come to mind are:The GUI is embedded in the data. What happens if you decide that you like a table-based presentation better •thanalist-basedpresentation?Inordertochangetoatable-basedpresentation,youmustrecodeyourentireHTML!Thiscouldmeaneditingmanyofpages.Searchingforinformationinthedataistough.HowwouldyougetaquicklistofonlytheclientsinCalifornia?•Certainly,sometypeofscriptwouldbenecessary.Buthowwouldthatscriptwork?Itwouldprobablyhavetosearchthroughthefilewordforwordlookingforthestring“California”.Andevenifitfoundmatches,itwouldhavenowayofknowingthatCaliforniamighthavearelationshipto“NewYork”-thattheyarebothstates.Forget about the relationships between pieces of data which are crucial to power searching.The data is tied to the logic and language of HTML. What happens if you want to present your data in a Java •applet?Well,unfortunately,yourJavaappletwouldhavetoparsethroughtheHTMLdocumentstrippingouttagsand reformat the data. Non-HTML processing applications should not be burdened with extraneous work.

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With XML, these problems and similar problems are solved. In XML, the same page would look like the following:

<CLIENT><NAME>Gunther Birznieks</NAME><ID>001</ID><COMPANY>Bob’s Fish Store</COMPANY><EMAIL>[email protected]</EMAIL><PHONE>662-9999</PHONE><STREET>1234 4th St.</STREET><CITY>New York</CITY><STATE>New York</STATE><ZIP>Zip: 10024</ZIP></CLIENT>

<CLIENT><NAME>Susan Czigonu</NAME><ID>002</ID><COMPANY>Netscape</COMPANY><EMAIL>[email protected]</EMAIL><PHONE>555-1234</PHONE><STREET>9876 Hazen Blvd.</STREET><CITY>San Jose</CITY><STATE>California</STATE><ZIP>90034</ZIP></CLIENT>

Custom tags are used to bring meaning to the data being displayed. When stored this way, data becomes extremely portablebecauseitcarrieswithititsdescriptionratherthanitsdisplay.Displayis“extracted”fromthedataandaswewillseelater,incorporatedintoa“stylesheet”.

With XML, the GUI is extracted. Thus, changes to display do not require futzing with the data. Instead, a separate •style sheet will specify a table display or a list display.Searchingthedataiseasyandefficient.Searchenginescansimplyparsethedescription-bearingtagsrather•than muddling in the data. Tags provide the search engines with the intelligence they lack.Complex relationships like trees and inheritance can be communicated.•The code is much more legible to a person coming into the environment with no prior knowledge. In the •above example, it is obvious that <ID>002</ID> represents an ID whereas <LI>002 might not. XML is self-describing.

The XML declarationTobeginanXMLdocument,itisagoodideatoincludetheXMLdeclarationastheveryfirstlineofthedocument.Isay“goodidea”because,thoughtheXMLdeclarationisoptional,itissuggestedbytheW3Cspecification.

Essentially,theXMLdeclarationisaprocessinginstructionthatnotifiestheprocessingagentthatthefollowingdocument has been marked up as an XML document. It will look something like the following:

<?xmlversion=“1.0”?>

Allprocessinginstructions,includingtheXMLdeclaration,beginwith<?andendwith?>.Followingtheinitial<?,youwillfindthenameoftheprocessinginstruction,whichinthiscaseis“xml”.


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TheXMLprocessinginstructionrequiresthatyouspecifya“version”attributeandallowsyoutospecifyoptional“standalone”and“encoding”attributes.

In its full regalia, the XML declaration might look like the following:<?xmlversion=“1.0”standalone=“yes”encoding=“UTF-8”?> The version attributeAswesaidbefore,ifyoudodecidetousetheoptionalXMLdeclaration,youmustdefinethe“version”attribute.Asofthiswriting,thecurrentversionofXMLis1.0.Notethatifyouincludetheoptionalattributes,“version”mustbespecifiedfirst.

The standalone attributeThe“standalone”attributespecifieswhetherthedocumenthasanymarkupdeclarationsthataredefinedinaseparatedocument.Thus,if“standalone”issetto“yes”,therewillbenomarkupdeclarationsinexternalDTD’s.Settingitto“no”leavestheissueopen.ThedocumentmayormaynotaccessexternalDTD’s.

The encoding attributeAll XML parsers must support 8-bit and 16-bit Unicode encoding corresponding to ASCII. However, XML parsers may support a larger set.

5.5 VRML (Virtual Reality Modelling Language)VRML, often pronounced ‘ver-mull,’ is Virtual Reality Modelling Language, the open standard for virtual reality on the Internet. You can use VRML to create three dimensional worlds, representations of information, and games. Asanopenstandard,nooneparticularcompanycontrolstheVRMLspecification,thatis,thelanguagedefinition.

Theoretically, anybody can use VRML to write software or worlds without having to license technology from •others. Using VRML, you can build a sequence of visual images into web settings with which a user can interact by viewing, moving, rotating, and otherwise interacting with an apparently 3-D scene. For example, you can view a room and use controls to move the room, as you would experience it if you were walking through it in real space. ToviewaVRMLfile,youneedaVRMLviewerorbrowser,whichcanbeaplug-inforawebbrowseryou•already have. Among viewers that you can download for the Windows platforms are blaxxun’s CC Pro, Platinum’s Cosmo Player, webFX, WorldView, and Fountain. Whurlwind and Voyager are two viewers for the Mac. Virtual reality refers to an immersive environment, an environment that you feel you are inside of. You can attain this immersive feeling with computers using 3D graphics and audio. Sounds in a virtual world can be specialised so that they sound louder when you are closer to them. When virtual •reality happens on the Internet, new possibilities arise for distributed, networked virtual environments. In HTML, inline images let you include graphics from anywhere on the web on to your web page. In VRML, •you can have inline parts of a virtual world, so that a chair in a VRML world can come from a URL on a server in France, while the garden comes from a server in Japan, and the soundtrack is from a URL on a server in England. In addition, hyperlinks from an object in a VRML world can lead to another URL on the web, which could be •another VRML world, an HTML page, or any other URL.VRML, often pronounced ‘ver-mull,’ is Virtual Reality Modelling Language, the open standard for virtual reality on the Internet.

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Uses of VRMLTherearemanyapplicationsforVRML,varyinginfocusfromVRML’sopen3Dfileformat,toitsnetworkingcapabilities, to its multimedia nature. Here are some applications for which people are currently using VRML.

Computer-aided design (CAD)•Scientificsimulations•Games•Data visualisation•Distributed, multi-user environments•Social computing•User interfaces to information•Financial applications•Product marketing and advertising•Education•Entertainment•


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Summary HTML or Hyper Text Markup Language is designed to specify the logical organisation of a document, with •important hypertext extensions.HTML instructions divide the text of a document into blocks called elements.•The HTML instructions, along with the text to which the instructions apply, are called HTML elements.•Many elements can have arguments that pass parameters to the interpreter handling this element. These arguments •are called attributes of the element.Dynamic HTML (DHTML) is a set of innovative features originally introduced in Microsoft.•JavaScript is a scripting language, and scripting languages are easier to learn and use than traditional programming •languages.XML emerged as a way to overcome the shortcomings of its two predecessors, SGML and HTML which were •bothverysuccessfulmarkuplanguages,butwhichwerebothflawedincertainways.VRML, often pronounced ‘ver-mull,’ is Virtual Reality Modelling Language, the open standard for virtual •reality on the Internet.

ReferencesMusciano, C. and Kennedy, B., 2006. • HTML & XHTML: the definitive guide, O’Reilly Media, Inc.Harold, R. E. and Means, S. W., 2004. • XML in a nutshell, O’Reilly Media, Inc.extropia, 1994. • Introduction to XML For Web Developers [Online] Available at: <http://www.extropia.com/tutorials/xml/history.html> [Accessed 11 November 2011].QuinStreet Inc., 2011. • Dynamic HTML [Online] Available at: <http://www.wdvl.com/Style/DHTML/> [Accessed 11 November 2011].Teachucompinc, 2011. • HTML Tutorial XML, XHTML, & DHTML Training Lesson 1.6 [Video Online] Available at:<http://www.youtube.com/watch?v=FdPk45Ktgbc>[Accessed11November2011].Ogsolution, 2008. • What is JavaScript? [Video Online] Available at: <http://www.youtube.com/watch?v=qtzjzMsJiO8>[Accessed11November2011].

Recommended ReferencePowell, A. T., 2003. • HTML & XHTML: the complete reference, McGraw-Hill Professional.Williamson, 2001. • Xml: The Complete Reference, Tata McGraw-Hill Education.Vacca, R. J., 1996. • VRML: bringing virtual reality to the Internet, AP Professional.

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Self AssessmentHTMLinstructionsdividethetextofadocumentintoblockscalled_________.1.

elementsa. bytesb. classesc. objectsd.

HTMLdocumentsarestructuredintotwoparts,namely,___________and________.2. heading, sub-headinga. head, body b. title, bodyc. object, headd.

Which of the following is a set of innovative features originally introduced in Microsoft Internet Explorer 3. 4.0?

Static HTMLa. JavaScriptb. Dynamic HTMLc. Javad.

__________ is a scripting language, and scripting languages are easier to learn and use than traditional4. programming language.

HTMLa. DHTMLb. VRMLc. JavaScriptd.

Whichofthefollowingstatementsistrue?5. JavaScript is designed for use on Web pages and is closely integrated with HTMLa. .HTML is designed for use on Web pages and is closely integrated with DHTML.b. DHTML is designed for use on Web pages and is closely integrated with HTML.c. JavaScript is designed for use on Web pages and is closely integrated with VRML.d.

DHTMLeliminatestheshortcomingsof____________pages.6. dynamica. staticb. webc. customd.

Whichofthefollowingtagsareusedtobringmeaningtothedatabeingdisplayed?7. Title a. Heading b. Customc. Boldd.


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__________isanextremelypowerfulandextensibletoolforsemanticmarkupwhichisparticularlyusefulfor8. cataloging and indexing data.

VRMLa. DHTMLb. HTMLc. SGMLd.

Youcanuse____________tocreatethreedimensionalworlds,representationsofinformationandgames.9. VRMLa. DHTMLb. HTMLc. SGMLd.

WhichofthefollowingisnotanapplicationofVRML?10. Computer-aided design (CAD)a. Social networkingb. Scientificsimulationsc. Gamesd.

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Chapter VI

Cookies

Aim


introduce the concept of cookies•

describe the functions of cookies•

highlight the concept of connecting to internet through mobile phone•

Objectives


elucidatethebenefitsofcookies•

explain various ways of managing cookies•

explicate the working of the cookie technology•

Learning outcome


understand the purpose of using cookie technology•

explain the disadvantages of cookie technology •

enlist t• he types of cookies


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6.1 Introduction to CookiesThe cookie technology relates to the use of HTTP cookies or web cookies, as they are called, by the websites. A cookie is a piece of text that is sent by a server to a web client, and returned by the client, each time it uses that server. Usually a cookie is a text message that is less than 255 characters long. The cookie technology is used for authentication of the website users, session tracking as also for maintaining certain information about the users.

Cookies serve as the means to identify a particular user. Once a user logs in to a website, a cookie can be made to associate with the user’s login information. For the subsequent visits by that user to the same website, the cookie canletknowthewebsitethattheuserisauthenticated.Thus,theuserissavedfromthemonotonoustasksoffillingin the login information each time he visits the website.

The second purpose of using the cookie technology is to differentiate between website users. The information pertaining to the user and his preferences can be held in the cookies. This makes it possible for the websites to provide personalisation to the users. Based on the preferences of a particular user, websites can bring about a personalisation in the presentation of the website and also its functionality. Many websites offer the authenticated users with a facility to customise the web pages and obtain a personalised look and feel in the website.

How does the cookie technology work?The transfer of web pages between a server and a browser happens by means of the Hypertext Transfer Protocol (HTTP). When a user types in a URL in the address bar of a browser, the browser takes it and sends a request to the server,askingforthewebpagethatwasspecifiedbytheuser.

Next, the server sends the page requested by the browser, in the form of an HTTP response. The response is •sent as a packet of text that may contain a statement asking the browser to store cookies. This is done by means ofastatement,“set-cookie:name=value”.Thebrowserisaskedtostorethevalue-stringin‘name’andreturnit to the server during any of the further requests made to it.During any subsequent request made to the same server, even while requesting a different web page from that •server,thebrowsersendsbackthecookievaluetoserver.Theserveridentifiesthisinformationandfulfilstherequest, without having the user to perform the authentication process again.

6.2 Functions of CookiesFunctions of cookies are detailed below.

Computer based cookies come with one or more name-value pairs consisting of information such as user •preferences,serverbasedsessionidentifiers,shoppingcartcontentsanddataemployedbyothersites.They are also known as the HTTP cookies, browser cookies and tracking cookies. Essentially a cookie is directed •as an HTTP header to a web browser by a web server, it is then redirected back by the browser. Cookies also serve authentication purposes, session tracking and storing particular information about the user.The information may include browsing patterns or the contents of shopping carts, and there exists some •alternatives to the cookies, and each exhibit strengths and weaknesses.Cookies, however, can enable your navigation patterns to be tracked, although they are by nature neither •spyware or viruses just simple un-executable pieces of text, various anti spyware software can detect cookies fromcertainsites.Andwhenabrowserrejectscookies;thisoftenrenderssomesitesasinaccessible,owingtologin complications.In the early days, cookies were implemented as a means to deal with problem of establishing credible shopping •cart platforms, and following which they were utilised for tracking visitor trends on the Netscape website.This cookie technology was patented in 1998 as belonging to Lou Montulli, and support for cookies was •incorporated starting with Internet Explorer version 2. Privacy concerns around cookies helped raise awareness in the members of the public of their growing use. It is in February of 1996 that a working group within the IETFofficiallyidentifiedthirdpartycookiesasaprivacythreat.

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However,NetscapeandInternetExplorerignoredtherecommendationscontainedinRFC2109specification•by the working group. Today’s shopping basket applications normally store the list of basket items in a database on the server side instead of storing them in the cookie itself.The application of tracking user’s internet cookies can be carried out by employing the IP address of the computer •inquestionorthereferrerfieldoftheHTTPheader.A site receiving a unique (no cookie) page request, in turn creates a random string and returns to the browser •involved a cookie with the requested page, intended for future requests. You can get rid of a tracking cookie by deleting persistent cookies on your web browser when the application is closed.Third party cookies can hook up with your browser in cases where the browser downloads images or other objects •(such as web banners) contained in a web server than a web page, thus, may then receive third party cookies.

6.3 Types of CookiesThere arefive different types of cookies; Persistent, temporary or session cookies, first-party, third-party andunsatisfactory cookies, which are explained below.

Persistent cookies:• Apersistentcookieisonestoredasafileonyourcomputer,anditremainstherewhenyouclose Internet Explorer. The cookie can be read by the website that created it when you visit that site again.Temporary (Session) cookies:• A temporary or session cookie is stored only for your current browsing session, and is deleted from your computer when you close your browser.First-party cookies:• Afirst-partycookieeitheroriginatesonorissenttotheWebsiteyouarecurrentlyviewing.These cookies are commonly used to store information, such as your preferences when visiting that site.Third-party cookies:• A third-party cookie either originates on or is sent to a Website different from the one you are currently viewing. Third-party Websites usually provide some content on the Website you are viewing. For example, many sites use advertising from third-party Websites and those third-party Websites may use cookies. A common use for this type of cookie is to track your Web page use for advertising or other marketing purposes. Third-party cookies can either be persistent or temporary.Unsatisfactory cookies:• Unsatisfactorycookiesarecookiesthatmightallowaccesstopersonallyidentifiableinformation that could be used for a secondary purpose without your consent.

6.4BenefitsofCookiesCookies are not harmful. Unlike worms and viruses, cookies cannot damage your computer or the data saved on yourharddrive.Theyaresimplytinytextfiles,placedonacomputerbyaWebserverandareonlyreadablebythesame server that placed them.

Cookies only contain basic information such as a user’s browser type and IP address, or information that the •user has voluntarily supplied, such as a stored passwords or preferences to customise a favourite site. Unlike spywareorcomputerviruses,cookiescannotbeconfiguredtodoanythingmorethantrackanonymousWebuser behaviour.Cookies are what make the Web a more enjoyable, personalised experience. Without cookies, Internet users •would have to remember all the passwords to all the different sites they visit. They would not be able to receive customised content, such as news, stock prices, sports scores or weather, and online shopping would be very cumbersome–ifnotimpossible!Instead, consumers would receive irrelevant information and content, such as advertising that fails to correspond •with their personal interests and needs. In addition, disabling or deleting cookies does not make Web users safer from viruses or other similar online threats.Cookies are beneficial to all Internet users – advertisers, online content providers and consumers–but in•different ways. Like TV and radio, much of the Internet is supported by advertising. To keep content on the Web free for consumers, online publishers need to generate advertising revenue, and advertisers need to reach the right audience.


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Cookies help to do this more effectively while making sure that consumers are not getting bombarded with •irrelevantorduplicativeads,content,orpromotionsthatcandiminishthequalityandvalueoftheWebsurfingexperience.

Disadvantages of the cookie technologyAlongwiththebenefitsofcookietechnology,therearecertaindisadvantagesthatareexplainedbelow.

Cookiepoisoningisdefinedastheactofmanipulatingthecontentsinthecookiebeforetheyaresenttothe•server. Changing the information contained in the cookies can misguide the websites and advertisers. In case a cookie contains a transaction information, an attacker can change the value in the cookie causing losses on part of the user or the e-commerce website, involved in the transaction. A site has an independent set of cookies. Anothersiteshouldnotbeabletomanipulateitscookies.Thecookietechnologyisvulnerabletothisdifficultyin case of some browsers.Cookies may generate an inconsistent state between the state of the client and that stored in the cookie. In cases, •where an operation is undone by clicking on a Back button, or when a page is reloaded, the state stored in the cookieshouldreflectthecorrespondingchange.Thecookietechnologylackstheabilitytodistinguishbetweentwo users who use the same user account. Cookies do not distinguish one user from another. They can distinctly identify only the combination of a user account, a browser and a computer.The cookie technology is vulnerable to cookie hijacking. Cookie hijacking refers to the interception of the •information on the cookies by a malicious user. When cookies are sent over the network in unencrypted HTTP sessions, there exists a potential risk that the information on the cookies can be stolen.

6.5 Managing CookiesFormanagingcookies,followingstepsarebeneficial.

Click on the Internet Explorer icon on your computer’s ‘Start’ menu.•Click on ‘Tools’ in the toolbar at the top of the browser window.•Select the ‘Internet Options’ heading.•Go to the ‘Privacy’ tab.•Use the slider bar on the left to set your cookie preferences. You can choose to accept all cookies, no cookies •or to restrict the use of cookies to the degree of your choice. You will be presented with an explanation of what sorts of cookies are blocked at each level of restriction.Allow cookies from certain Websites. Click on the ‘Sites’ button and then enter the URLs of Websites from •which you always want to allow cookies. Click ‘Allow,’ then ‘OK’ when you are done. You can follow the same steps to always block cookies from certain sites. Just hit the ‘Block’ button instead of the ‘Allow’ button.Click‘OK’onthemaincookiemanagementwindowwhenyouarefinishedmakingallofyourselections.•

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Summary The cookie technology relates to the use of HTTP cookies or web cookies, as they are called, by the websites.•A cookie is a piece of text that is sent by a server to a web client, and returned by the client, each time it uses •that server.The transfer of web pages between a server and a browser happens by means of the Hypertext Transfer Protocol •(HTTP).Therearefivedifferenttypesofcookies,namely,Persistent,TemporaryorSessionCookies,First-Party,Third-•Party and Unsatisfactory cookies. Apersistentcookie isonestoredasafileonyourcomputer,and it remains therewhenyouclose Internet•Explorer.A temporary or session cookie is stored only for your current browsing session, and is deleted from your computer •when you close your browser.Afirst-partycookieeitheroriginatesonorissenttotheWebsiteyouarecurrentlyviewing.•A third-party cookie either originates on or is sent to a Website different from the one you are currently •viewing.Unsatisfactorycookiesarecookiesthatmightallowaccesstopersonallyidentifiableinformationthatcouldbe•used for a secondary purpose without your consent.Cookiepoisoningisdefinedastheactofmanipulatingthecontentsinthecookiesbeforetheyaresenttothe•serverCookies may generate an inconsistent state between the state of the client and that stored in the cookie.•

References Levine, R. J. and Young, L. M., 2011. • The Internet For Dummies, John Wiley & Sons.Holzman, C., 2003. • The healthy PC: preventive care and home remedies for your computer , McGraw-Hill Professional.Buzzle.com, 2000. • What is Cookie Technology? [Online] Available at: <http://www.buzzle.com/articles/what-is-cookie-technology.html> [Accessed 11 November 2011].COMPUTER BASICS AND BEYOND, 2003. • What are the types of Cookies? [Online] Available at: <http://www.computerbasicsandbeyond.com/tutorials/cookietypes.html> [Accessed 11 November 2011]. Butterscotchcom, 2009. • What are Internet cookies? [Video Online] Available at: <http://www.youtube.com/watch?v=mZ7xD-czx-Q>[Accessed11November2011].Janet ma, 2008. • Internet cookies[VideoOnline]Availableat:<http://www.youtube.com/watch?v=QYFKbp_OedA> [Accessed 11 November 2011].

Recommended ReadingColmer, S. R. and Thomas, M. T., 2005. • The senior’s guide to the Internet: surfing, shopping, e-mail and security, EKLEKTIKA, Inc.Elmer, G., 2002. • Critical perspectives on the Internet,Rowman&Littlefield.Schneider, P. G, Evans, J. and Pinard, T. K., 2008. • The Internet: Illustrated, 5th ed., Cengage Learning.


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Self Assessment Thecookietechnologyrelatestotheuseof___________cookiesorwebcookies,astheyarecalled,bythe1. websites.

HTTPa. HTMLb. DHTMLc. VRMLd.

The____________ technology isused forauthenticationof thewebsiteusers, session trackingasalso for2. maintaining certain information about the users.

XMLa. Cookieb. XTMLc. HTMLd.

Whichoffollowingstatementsisfalse?3. A cookie is a piece of text that is sent by a server to a web client, and returned by the client, each time it a. uses that server.Unsatisfactorycookiesarecookiesthatmightallowaccesstopersonallyidentifiableinformationthatcouldb. be used for a secondary purpose without your consent.Satisfactorycookiesarecookiesthatmightallowaccesstopersonallyidentifiableinformationthatcouldc. be used for a secondary purpose without your consent.Cookies serve as the means to identify a particular user.d.

Thesecondpurposeofusingthecookietechnologyistodifferentiatebetweentwo/many______________.4. LAN usersa. static usersb. cookie userc. website usersd.

Thetransferofwebpagesbetweenaserverandabrowserhappensbythemeansof_____________.5. Hypertext Transfer Protocol a. Network protocolb. Internet protocolc. Internetwork protocold.

_______________isdefinedastheactofmanipulatingthecontentsinthecookiesbeforetheyaresenttothe6. server.

Cookie positioninga. Cookie poisoningb. Cookie markingc. Cookie interfacingd.

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Whichofthefollowingcookieisstoredasafileonyourcomputer,anditremainstherewhenyoucloseInternet7. Explorer?

Sessiona. Temporaryb. Persistent c. First-partyd.

Which of the following cookie is stored only for your current browsing session, and is deleted from your 8. computerwhenyoucloseyourbrowser?

Persistenta. First-partyb. Third-partyc. Temporary d.

A__________cookieeitheroriginatesonorissenttotheWebsiteyouarecurrentlyviewing.9. first-partya. persistentb. temporaryc. sessiond.

A__________cookie either originates onor is sent to aWebsite different from theoneyou are currently10. viewing.

third-partya. first-partyb. temporaryc. sessiond.


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Chapter VII

Internet Connectivity

Aim


introduce the dial-up connection from a computer•

describe accessing internet through leased line•

highlight the concept of connecting to internet through mobile phone•

Objectives


elucidate connecting to internet through cable network•

explain the requirements for accessing internet through leased line•

describe the process for connecting to internet through mobile phone•

Learning outcome


understand the different requirements for using internet through dial-up connection•

comprehend the requirement for connecting to internet through cable network•

enlist the steps to access Internet through dial-• up connection

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7.1 Dial-up Connection from PCThe most popular way of accessing Internet is through a Dial-up connection from your PC. The digital data from the computer is converted by the modem to analog form and is passed on to the telephone line. At the other end, another modem is used which converts the analog data received to digital form and then passes onto the receiving machine. Open the dialer software and click on the connect button. Once the connection is established, you may be requested to enter user name and password, or you may supply the same in the window of the dialer before starting theprocessofdiallingtheISP.Afterverificationofusernameandpassword,yourPCisloggedontotheInternetand you can start browsing the Internet.

The following are the requirements to access the Internet through a dial-up connection:A modem•TCP software•Internet account from an ISP•Dialler software to connect to ISP•Browser•

Accessing Internet through dial-up connection is most popular among the users who access Internet from home.The following are various steps that are to be followed to access Internet through dial-up connection:

Step 1: Open the dialer software

Fig. 7.1 Dial-up icon(Source: http://www.itservices.hku.hk/news/ccnews89/dun.gif)


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Step 2: Enter user name and password. Then click on Connect button in the Connect to Dialog Box

Fig. 7.2 Connect to dialog box(Source:http://support.gateway.com/s/manlib/notebooks/images/dun_main.jpg)

FollowingfiguredepictsthePCdiallingthenumberoftheserveroftheInternetServiceProvider(ISP).

Fig. 7.3 Dialling process(Source: http://blogs.zdnet.com/images/connect2.jpg)

Followingfiguredepictstheverificationofusernameandpasswordattheserverend.

Fig.7.4Verificationofusernameandpassword(Source: http://www.cwu.edu/~its/images/win98/image038.jpg)

Once successfully logged into the Internet the connection complete Dialog Box appears. If you are successfully connected, a little computer screen icon appears on the right hand side of the of Windows task bar.

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Fig. 7.5 Connected dialog box(Source:http://t1.gstatic.com/

images?q=tbn:ANd9GcT3RzuTWEQO4WXcPVYHPRbLhHg4WPi3W5VrTVz8xwNGTjajDoId2w)

Thisflasheswithsentandreceiveddataindicatingthatthelinkisactive.Whenyoudouble-clickonthisicon,youwillseeadialogboxasshowninthefigure.

Step 3: After logging onto the Internet, click on the browser button to start browsing. It is important to set the Internet options for your PC before trying to access Internet by applying the above steps. Internet is accessed through a Dial-up connection from a single PC. The access speeds vary from 2400 bps to 56000 bps.

7.2 Accessing Internet through Leased LineUsually,corporateofficesaccessInternetthroughleasedlines.AleasedlineisadedicatedcommunicationchannelwhichconnectsthecompanytotheISP.ThesignificanceofthismodeofaccessingInternetisthatthecompanyisalways connected to Internet. It does not have to dial to the ISP as and when access is required.

The expenses involved for the user in accessing Internet through leased line are higher when compared to dial-•up access, but the speeds are also higher. They vary from 56 kbps to 10 mbps. Some ISPs charge the user based onthevolumeoftraffic.ItmeansthatyourbillisdirectlyproportionaltotheuseofInternet.SomeISPshaveafixedchargeperannum.Employees of corporate sector access Internet through their nodes. A group of nodes are connected to a hub or a •switch.Forexample,ifanorganisationishavingthreeseparatebuildingsaspartofitsoffice,thenoneprobabilityis that each building will have a hub/switch and all nodes of that building are connected to that hub/switch. The hub or switch is in turn connected to the router and the router is in turn connected to the leased line for •accessing Internet. A radio link is also a form of leased line wherein a radio antenna is used to establish virtual connectionbetweenacorporateofficeandanISP.SeveralISPssupportradiolink.Thefigureshownbelowdepicts the connection to Internet through a leased line.


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Internet

Leased lineMail server

Web server

Work stations

Ethernet network

Router with IP address

POP

Fig. 7.6 Connecting to the Internet through leased line(Source: http://www.itsavvy.in/wp-content/uploads/2011/01/leased-line-connection.gif)

7.3 Connecting to Internet through a Mobile PhoneInternet can be accessed through a Mobile phone which is WAP enabled. Here, a mobile phone could be any WAP enabled device such as PDA, Laptop etc. When you click on the appropriate menu item in your mobile phone, then the WAP enabled device contacts the concerned base station. In turn, the request is transmitted to a WAP gateway.

A WAP enabled device can only access web pages which are developed using WML. But, web servers have •webpageswhicharewrittenusingHTML.So,afilterisusedforconversionfromHTMLtoWMLandvice-versa. TheWAPgatewaycontacts thefilterwhichconverts the inputWMLrequest intoHTMLandcontacts the•appropriatewebserver.ThewebservertransmitstheresponsetothefilterwhichconvertstheinputHTMLpageto WML page, thus making it compatible to WAP enabled device. The other way for WAP enabled device to access web pages which are developed using WML directly is to •contactthewebserverthroughtheWAPgateway.FollowingfiguredepictsthecommunicationbetweenaWAPenabled device and a web server.

Communication tower

WTP

WTLS

WAP gateway

Internet

HTTPWeb server

SSL

Fig. 7.7 WAP device connecting to the web server(Source:http://flylib.com/books/3/262/1/html/2/024_files/image001.gif)

7.4 Connecting to Internet through Cable NetworkCable television has become as popular as radio now-a-days. Internet can also be accessed through the cable that brings TV channels to our homes using a cable modem. To access Internet through a cable, there is a need for a cable modem. Cable modem acts as an interface between the computer and the cable. Cable modem separates digital and analog signals travelling on the cable and enables a PC to send and receive data using coaxial cable on the same frequencies used by the cable TV channels.

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ISDN and DSL cannot match the bandwidth and speed offered by the cable. PSTN offers maximum of 56 kbps, •ISDN offers a maximum of 128 kbps whereas cable starts with 64 kbps and can go upto 38 Mbps. Internet through cable is, therefore, suitable for downloading multimedia such as movies, animation, etc. Neither television nor data signals are affected by simultaneous use. Internet through cable is right solution for •bandwidth intensive applications and corporate customers. Though cable has immense potentials as an access technology, it has a long way to go in terms of infrastructure, quality of service, cost factor, security, etc.

Internet

How cable internet works (PC)

Internet gateway

Leased line

Leased line TV cable

Cable modem

Television

Computer

Fig. 7.8 Connecting to the Internet through cable network(Source: http://bombaybite.hathway.com/images/billing/howcable.jpg)


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Summary The most popular way of accessing Internet is through a Dial-up connection from your PC. •The digital data from the computer is converted by the modem to analog form and is passed on to the telephone •line.A leased line is a dedicated communication channel which connects the company to the ISP.•Internet can be accessed through a mobile phone which is WAP enabled.•A WAP enabled device can only access web pages which are developed using WML.•TheWAPgatewaycontacts thefilterwhichconverts the inputWMLrequest intoHTMLandcontacts the•appropriate web server.Internet can also be accessed through the cable that brings TV channels to our homes using a cable modem.•Cable modem acts as an interface between the computer and the cable.•Cable modem separates digital and analog signals travelling on the cable and enables a PC to send and receive •data using coaxial cable on the same frequencies used by the cable TV channels.ISDN and DSL cannot match the bandwidth and speed offered by the cable.•

ReferencesMiller, 2007. • Absolute Beginner’s Guide to Computer Basics, Pearson Education India.Minoli, 1999. • Internet & Intranet Engineering, Tata McGraw-Hill Education.PCWorld Communications, Inc., 1998. • How It Works: Dial-Up Networking [Online] Available at: <http://www.pcworld.com/article/48467/how_it_works_dialup_networking.html>[Accessed14November2011].Indian Express Group, 2001. • Leased line [Online] Available at: <http://www.networkmagazineindia.com/200110/basics1.htm> [Accessed 14 November 2011].sachinnaik04, 2010. • Connecting mobile internet to PC for all networks [Video Online] Available at: <http://www.youtube.com/watch?v=ZsI3OE-TiLw>[Accessed14November2011].TheMoCABlog, 2011. • Connecting Your TV to the Internet [Video Online] Available at: <http://www.youtube.com/watch?v=BKutF91eGkM>[Accessed14November2011].

Recommended ReadingChambers, L. M., 2010. • PCs All-in-One For Dummies, John Wiley & Sons.Eckel, G. and Steen, W., 1996. • Intranet working, New Riders.Stair, R. and Reynolds, G., 2011. • Principles of Information Systems, Cengage Learning.

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Self AssessmentThemostpopularwayofaccessingtheInternetisthrougha_________fromyourPC.1.

dial-up connectiona. leased lineb. LANc. WANd.

Thedigitaldatafromthecomputerisconvertedbythe___________toanalogformandispassedontothe2. telephone line.

DACa. Modemb. ADCc. Convertor d.

WhichofthefollowingisadedicatedcommunicationchannelconnectingthecompanytotheISP?3. Local linea. Dedicated lineb. Leased linec. Data lined.

Internetcanbeaccessedthroughamobilephonewhichis___________enabled4. WMLa. DSLb. ISDNc. WAPd.

AWAPenableddevicecanonlyaccesswebpageswhicharedevelopedusing___________.5. WMLa. DSLb. IDSLc. ISDNd.

The___________gatewaycontactsthefilterwhichconvertstheinputWMLrequestintoHTMLandcontacts6. the appropriate web server.

DSLa. WAPb. ISDNc. XMLd.

__________actsasaninterfacebetweenthecomputerandthecable.7. Data modema. Internal modemb. Cable modemc. External modemd.


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Cablemodemseparates_____________and_________signalstravellingonthecableandenablesaPCtosend8. and receive data using coaxial cable on the same frequencies used by the cable TV channels.

simplex, duplexa. Static, dynamicb. internal, externalc. digital, analogd.

_______________andDSLcannotmatchthebandwidthandspeedofferedbythecable.9. ISDNa. XMLb. PSTNc. ISDLd.

A___________isalsoaformofleasedlinewhereinaradioantennaisusedtoestablishvirtualconnection10. betweenacorporateofficeandanISP.

up-linka. radio linkb. down-linkc. netlinkd.

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Chapter VIII

Internet Security

Aim


introduce security and internet•

describe the concept of password protection•

highlight the concept of computer virus•

Objectives


elucidate spyware•

explaintheconceptoffirewalls•

explicate the concept of proxy servers•

Learning outcome


understand different ways of avoiding virus•

comprehend the functioning of a typical proxy server•

enlist the types of computer viru• ses


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8.1 Security and InternetThere has been an enormous information explosion, and the mushrooming popularity of the Internet puts huge amountsofinformationrightatourfingertips.HowsafeistransmissionofdataontheInternetisabigquestion.Threats to privacy are being widely publicised from time to time.

Fig. 8.1 Internet security(Source:http://t3.gstatic.com/images?q=tbn:ANd9GcSyJWsuv7dBYP2YnAVRrenAcB36Qp9JsTteAweiyKd4fR2

ksT65)

If one is running a business, one would probably want information to be easily accessible about products or services butcertainlynotother informationlikefillingof tenders,pricesquotedtovariouscustomers,etc.Ontheotherside we have to ensure that data kept on our servers is not attempted by intruders or hackers and wrong messages are sent to the people visiting our site. We can save our personal information and secure our system from hackers, intruders or virus attacks.

8.2 Password ProtectionThestoragespaceonahostcomputerisusedasatemporaryholdingplaceforfilesbeforedownloadingthemtothepersonalcomputer.ThereisaneedtoprotectsuchfilesasthesecanbeaccessedeasilythroughtheInternet.Thiscallsforprotectingthesystemasawhole.Inthisrespect,thefirstlevelofsecuritymechanismisyourpassword.Passwordsareanimportantfirstlineofdefenceagainstintrudersanditisineveryone’sbestinteresttousethisprincipal mode of protection.

Fig. 8.2 Account password(Source:http://t2.gstatic.com/images?q=tbn:ANd9GcSt8z9fzzE3Daqv1-EUnZX5bLysv93sIpeyaw7Z73eqnC5m

dnlm)

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Ifanintrudercanbreakintoyourhost’ssystemusingyourpassword,heorshemaythenbeabletofindothersecurity holes in that system or use it as a means of entry into other systems on the Internet. When you establish an Internet account, you should follow some basic rules when choosing a password. You make it easy for a cracker to decipheryourpasswordifyouchooseonethatiseasytoremember,likeyourfirstname,yourspouse’sfirstnameor a pet’s name. To help make your account more secure, consider the following principles when creating and using your password:

Don’tuseyournameoramodificationofyournameforyourpassword.•Don’tuseawordormodificationofawordthatoccursinanydictionary.•Don’t use an acronym.•Once you’ve created an account password, don’t share it with anyone.•Change your password often, at least every three months.•Don’t leave your terminal unattended when you’re logged in.•Don’t write your ID and password on a piece of paper or send it to friends via e-mail.•

8.3 Computer VirusesAcomputervirusisacomputerprogrammethatinfectsyourcomputerapplicationsorsystemfiles.Whenthevirusbecomes active, it can destroy data on any computer. The virus does this by getting into your computer’s memory andfromthereitcancopyitselftoitsharddiskorfloppydisks.Thecomputervirusisapieceofprogrammingcodeusually disguised as something else that causes some unexpected and usually undesirable event.

Email and attachments

Media: Disks, CDs,

Tapes

Worms

Scripts: ActiveX,

Visual Basic

Boot and Program

virus

Boot and Program

virus

Web pagesEmail and attachments

Scripts: ActiveX,

Visual Basic Worms

Media: Disks, CDs,

Tapes

Internet protocols

Can contain

Attached programsTravels by

human

MSOfficeMacros

Embedded or in attachment

Can contain

Search and replicate

Web page components

Fig. 8.3 Types of viruses(Source:http://www.livinginternet.com/g/virus_families.gif)

A virus is often designed so that it is automatically spread to other computer users. Viruses can be transmitted as attachments to an e-mail note, as downloads, or be present on a diskette or CD. The source of the e-mail note, downloadedfile,ordisketteyou’vereceivedisoftenunawareofthevirus.Someviruseswreaktheireffectassoonas theircode isexecuted;otherviruses liedormantuntilcircumstancescause theircode tobeexecutedby thecomputer. Some viruses are playful in intent and effect and some can be quite harmful, erasing data or causing your hard disk to require reformatting.


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Viruses are inactive until you execute an application that’s infected. You can also activate a virus by starting up yourcomputerwithafloppydiskthat’sinfectedbyabootsectorvirus.Goingonlineanddownloadinganinfectedprogramme isn’t harmful. Only when you execute the infected programme can the virus infect your PC. Generally, there are three main classes of viruses:

File infectors: • Somefile infectorviruses attach themselves toprogrammefiles,usually selected .COMor.EXEfiles.Somecaninfectanyprogrammeforwhichexecutionisrequested,including.SYS,.OVL,.PRG,and.MNUfiles.Whentheprogrammeisloaded,thevirusisloadedaswell.Otherfileinfectorvirusesarriveas wholly-contained programmes or scripts sent as an attachment to an e-mail note.System or boot-record infectors:• These viruses infect executable code found in certain system areas on a disk. They attach to the DOS boot sector on diskettes or the Master Boot Record on hard disks. A typical scenario is to receive a diskette from an innocent source that contains a boot disk virus. When your operating system is running,filesonthediskettecanbereadwithouttriggeringthebootdiskvirus.Macro viruses: • These are among the most common viruses, and they tend to do the least damage. Macro viruses infect your Microsoft Word application and typically insert unwanted words or phrases. The best protection againstavirusistoknowtheoriginofeachprogrammeorfileyouloadintoyourcomputeroropenfromyoure-mail programme.

Sincethisisdifficult,youcanbuyanti-virussoftwarethatcanscreene-mailattachmentsandalsocheckallofyourfilesperiodicallyandremoveanyvirusesthatarefound.Today,therearethousandsofknownvirusesandnewviruses are being developed daily.

8.3.1 Avoiding VirusesIfyousharefloppieswithothersordownloadfilesfromonlineservices,thereisno100%guaranteethatyou’llalways be protected against viruses. To help reduce the risk of your computer being infected, follow these tips:

Run an anti-virus programme and keep it updated often.•Scanfloppiesthatyoususpectmightbeinfected.•Don’t copy programmes from one computer to another. Use the original distribution diskettes to install •programmes.Scan your system regularly with the full scanning engine.•Avoidusingfloppiesfromunknownsources.•Write-projectyourfloppiesbycoveringthenotchon5.25-inchdisksorbyslidingthelittletabtoexposethe•hole on 3.5-inch disks.Never boot your computers from unknown diskettes. If you do and you suspect there may be a virus on the •diskette, shut the computer down. Boot up from a clean system diskette and check the system with an anti-virus programme.Utiliseyouranti-virusprogramme’smemoryresidentscannerstocheckallfilesastheyareaccessed,evenfrom•the Internet.

8.4 SpywareSpyware is a software planted on your computer to retrieve and forward information about you to outside systems. Theinformationcollectedcanrangefromasurveyofyoursurfinghabitspassedalongtoadvertisersandmarketersto the passwords and credit card numbers you type passed along to crackers who may exploit it.

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Fig. 8.4 Computer spyware(Source:http://howtobuycomputer.net/images/spyware%20doctor%20scan%20results%20screen-thumb.gif)

The Internet Technology software can be planted through e-mail or even included in software you obtain and install for other purposes. It can also record information about what you do while you are there, and perhaps collect further information from you. Many sites want you to register in order to use their services.

You may be asked your real name and e-mail address, your home or business address, your telephone number, •your income level, your interests, and so on. This can be valuable information for running a business. The information is voluntary, of course, and they have no way to tell if you are faking the information. Think twice before giving out such information freely. Think about whom you are giving it to and what uses they could put the information to. To defend yourself •against spyware, always maintain current anti-virus software on your system, and be very careful about installing software from unknown sources.

8.5 FirewallsIf you use a dial-up connection, you probably are reasonably safe. If you use a full time network connected to the Internet or use a full time connection like cable modem or Digital Subscriber Line (DSL), you may be quite vulnerable.

At any time, thousands of automated programmes are running on the Internet just looking for vulnerable computer •systems. As a result, your computer is probably being probed repeatedly during the day. In order to secure your computerfromreceivingsuchunwantedprogrammesandpreventintrusions,firewallsmaybeinstalled.Afirewallisasetofrelatedprogrammes,locatedatanetworkgatewayserverthatprotectstheresourcesofa•private network from users from other networks. An enterprise with an intranet that allows its workers access tothewiderInternetinstallsafirewalltopreventoutsidersfromaccessingitsownprivatedataresourcesandfor controlling what outside resources its own users have access to. Thereareanumberoffirewallscreeningmethods.Asimpleoneistoscreenrequeststomakesuretheycome•fromacceptabledomainnameandInternetProtocoladdresses.Formobileusers,firewallsallowremoteaccessintotheprivatenetworkbytheuseofsecurelogonproceduresandauthenticationcertificates.


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Server

Workstation

Wireless AP

Hub or Switch Router

Firewall

Internet

Fig. 8.5 Firewall(Source:http://www.windowsitpro.com/content/content/27095/Figure_02.gif)

Afirewallreferstotheconceptofasecurityinterfaceorgatewaybetweenaclosedsystemornetworkandthe•outsideInternetthatblocksormanagescommunicationsinandoutofthesystem.Basically,afirewall,workingclosely with a router programme, examines each network packet to determine whether to forward it towards its destination. Afirewallalsoincludesorworkswithaproxyserverthatmakesnetworkrequestsonbehalfofworkstation•users.Afirewallisofteninstalledinaspeciallydesignatedcomputerseparatefromtherestofthenetworksothatnoincomingrequestcangetdirectlyatprivatenetworkresources.Afirewallssecuritymaybeprovidedbypasswords,authenticationtechniques,software,andhardware,i.e.,afirewallisadevicethatprotectsanetwork(group of computers) from outside interference. Itcanbeahardwareorsoftwaredevice.AfirewallisarouterthatrestrictsInternetaccessbyonlyallowing•accesstocertaincomputerswithintheorganisation.Afirewallprotectsthecompanycomputers.ItcanalsostopcompanyworkersfromaccessingtheInternet.Anumberofcompaniesmakefirewallproducts.Featuresinclude logging and reporting, automatic alarms at given thresholds of attack, and a graphical user interface for controllingthefirewall.

8.6 Proxy ServersIn an enterprise that uses the Internet, a proxy server is a server that acts as an intermediary between a workstation user and the Internet so that the enterprise can ensure security, administrative control, and caching service. A proxy server is associated with or is part of a gateway server that separates the enterprise network from the outside network andafirewallserverthatprotectstheenterprisenetworkfromoutsideintrusion.

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Remote Client

1. HTTP or HTTPS request2. External DNS view re-directs to proxy server

Proxy Server

3. Re-direct to HTTPS (if needed)4. Authenticated5. Proxy request/response to/from internet server

EncryptedTraffic

Encrypted or Unencrypted

Internet Server

Internet

Fig. 8.6 Proxy servers(Source:http://thelowedown.files.wordpress.com/2008/07/proxyarchitecture.png)

AproxyserverreceivesarequestforanInternetservicefromauser.Ifitpassesfilteringrequirements,theproxyserver,assumingitisalsoacacheserver,looksinitslocalcacheofpreviouslydownloadedwebpages.Ifitfindsthepage, it returns it to the user without needing to forward the request to the Internet. If the page is not in the cache, the proxy server, acting as a client on behalf of the user, uses one of its own IP addresses to request the page from the server out on the Internet.

When the page is returned, the proxy server relates it to the original request and forwards it on to the user. When a firewallisusedtostopcompanyworkersfromaccessingtheInternet,aproxyserverisusedtoprovideaccess.Italsoacts as a security device by providing a buffer between inside and outside (on Internet) computers. The functioning of a typical proxy server is given below:

Whenaclientwantsafile,thisrequestissenttotheproxyserver.•Theproxyservercontactsthewebservertogetthefile.•Theproxyserverkeepsacopyofthefile.•Theproxyserversendsthefilebacktotheclient.•

Ifanotherclientwantsthesamefile,theproxyserverknowsitalreadyhasacopy.Itdoesnotcontactthewebserver.Theproxyserversendsthecopyofthefiletotheclient.ProxyserverssaveInternettraffic.Ifonehundredclientswantthesamefile,theproxyservergetsthefileonce.Itkeepsacopyofthefileincache.Thecopyisgiventoalltheclients.Ifyoudidnotuseaproxyserver,eachclientwoulddownloadtheirownfilefromtheInternet.


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The functions of proxy,firewall, and caching can be in separate server programmesor combined in a singlepackage. Different server programmes can be in different computers. For example, a proxy server may be in the samemachinewithafirewallserveroritmaybeonaseparateserverandforwardrequeststhroughthefirewall.Totheuser,theproxyserverisinvisible;allInternetrequestsandreturnedresponsesappeartobedirectlywiththeaddressed Internet server.

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Summary Thestoragespaceonahostcomputerisusedasatemporaryholdingplaceforfilesbeforedownloadingthem•to the personal computer.Ifanintrudercanbreakintoyourhost’ssystemusingyourpassword,heorshemaythenbeabletofindother•security holes in that system or use it as a means of entry into other systems on the Internet.Acomputervirusisacomputerprogrammethatinfectsyourcomputerapplicationsorsystemfiles.•The computer virus is a piece of programming code usually disguised as something else that causes some •unexpected and usually undesirable event.Viruses can be transmitted as attachments to an e-mail note, as downloads, or be present on a diskette or CD.•Somefileinfectorvirusesattachthemselvestoprogrammefiles,usuallyselected.COMor.EXEfiles.•Spyware is software planted on your computer to retrieve and forward information about you to outside •systems.The Internet Technology software can be planted through e-mail or even included in software you obtain and •install for other purposes.Afirewallisasetofrelatedprogrammes,locatedatanetworkgatewayserverthatprotectstheresourcesofa•private network from users from other networks.A proxy server is associated with or is part of a gateway server that separates the enterprise network from the •outsidenetworkandafirewallserverthatprotectstheenterprisenetworkfromoutsideintrusion.

ReferencesPreethanm, V. V., 2002. • Internet security and firewalls, Premier Press.Stitt, C. and Keilar, L., 2004. • Computer Virus, Blake Education.What Is My IP Address, 2000. • What is a Proxy Server? [Online] Available at: <http://whatismyipaddress.com/proxy-server> [Accessed 14 November 2011].Microsoft, 2011. • Firewalls [Online] Available at: <http://technet.microsoft.com/en-us/library/cc700820.aspx> [Accessed 14 November 2011].Ciscovid, 2009. • What is a Firewall? [Video Online] Available at: <http://www.youtube.com/watch?v=Onk5q2TLUmM>[Accessed14November2011].Butterscotchcom, 2009. • What is a proxy server? [Video Online] Available at: <http://www.youtube.com/watch?v=BbRGenGwCd8>[Accessed14November2011].

Recommended ReadingSpeed, T. and Ellis, J., 2003. • Internet security: a jumpstart for systems administrators and IT managers, Digital Press.Loson, J., 1999. • The computer virus, Newark Central Schools.Luotonen, A., 1998. • Web proxy servers, Prentice Hall PTR.


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Self Assessment___________areanimportantfirstlineofdefenceagainstintrudersanditisineveryone’sbestinteresttouse1. this principal mode of protection.

Passwordsa. Anti-virusb. Smart cardsc. Id-cardsd.

Acomputer_________isacomputerprogrammethatinfectscomputerapplicationsorsystemfiles.2. buga. virusb. trojan horsec. wormd.

Which of the following viruses infect Microsoft Word application and typically insert unwanted words or 3. phrases?

Microa. Dynamicb. Macroc. Static d.

Whichofthefollowingstatementsistrue?4. Trojan horse is software planted on your computer to retrieve and forward information about you to outside a. systems.Firmware is software planted on your computer to retrieve and forward information about you to outside b. systems Bug is software planted on your computer to retrieve and forward information about you to outside c. systems Spyware is software planted on your computer to retrieve and forward information about you to outside d. systems.

InanenterprisethatusestheInternet,a________________isaserverthatactsasanintermediarybetweena5. workstation user and the Internet.

proxy servera. DNS serverb. domain serverc. name serverd.

A___________isarouterthatrestrictsInternetaccessbyonlyallowingaccesstocertaincomputerswithin6. the organisation.

Proxy servera. Firewallb. Spywarec. Firmwared.

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Whichofthefollowingvirusesinfectingexecutablecodearefoundincertainsystemareasonadisk?7. Macro infectorsa. File infectorsb. System or boot-record infectorsc. Disk infectors d.

Virusesare______________untilyouexecuteanapplicationthat’sinfected.8. activea. dynamicb. deadc. inactived.

Some_______________infectorvirusesattachthemselvestoprogrammefiles,usuallyselected.COMor.EXE9. files.

filea. systemb. bootc. serverd.

Whenthe_________________isrunning,filesonthediskettecanbereadwithouttriggeringthebootdisk10. virus.

servera. operating systemb. bootfilec. boot serverd.


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Application I

Sendmail e-mail Server Commandeered

In this case a spammer had successfully exploited vulnerability in the server code which allowed the sender to use the client’s machine for sending hundreds of thousands of spam. The tremendous load on the server caused by the outgoing mail, replies of undeliverable mail, and the ensuing hate mail crippled the other services provided by the machine.

Solution — Thiswasarathersimpledisastertorecoverfromoncewewerefinallyabletoaccessthemachine.Atthetime,thisclientwasrunningSunOSandtheprocesstableoverflowed,creatingadenialofservicewherewecouldn’tcreateanewloginprocessasRoot.Onceweregainedaccesstothemachine,thefixwastoupdatethevulnerableversionofSendmail,ensurethattheconfigurationdidn’tallowrelayingfromanythingbutthelocalnetwork.A very important lesson learned here was the extreme importance in separating your services amongst multiple servers. The web site shouldn’t have been down because of a problem with the e-mail server. This client decided that it was much cheaper to invest in a couple new servers than to have his source of income shut down unnecessarily. The third phase of this solution was to check the system for other vulnerabilities to e-mail attacks. We found a CGI programonthesitethatwasnamedFormMail.Thisisafilethatisexploitedbyspammersregularly.

Source: access technologies, 2011. Sendmail e-mail Server Commandeered [Online] Available at: <http://www.networksecuritytechnology.com/2011/01/sendmail-e-mail-server-commandeered/> [Accessed 14 November 2011].

QuestionsWhathappenedtoSendmailserver?1. Answer In this case a spammer had successfully exploited vulnerability in the server code, which allowed the sender to use the client’s machine for sending hundreds of thousands of spam. The tremendous load on the server caused by the outgoing mail, replies of undeliverable mail, and the ensuing hate mail crippled the other services provided by the machine.

Howthedisasterrecovered?2. AnswerAtthetime,theclientwasrunningSunOSandtheprocesstableoverflowed,creatingadenialofservicewhereitcouldn’tcreateanewloginprocessasRoot.Onceweregainedaccesstothemachine,thefixwastoupdatethevulnerableversionofSendmail,ensurethattheconfigurationdidn’tallowrelayingfromanythingbutthelocal network.

Whichfilewasbeingexploitedbyspammers?3. AnswerFoundaCGIprogramon the site thatwasnamedFormMail.This is afile that is exploitedby spammersregularly.

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Application II

E-mail Case Study: Analysing J.C. Penney’s Frequency, Subject Lines

Online retailers often face decisions regarding their e-mail programs. These include issues like determining ideal frequencies and crafting compelling subject lines. To help address these questions, a series of case-study-type articles, pairinglarge,popularonlineretailerswithdifferente-mailtopics.Forthisfirstinstallment,theauthorexaminesJ.C.Penney’s approach to e-mail segmentation, frequency and subject lines.

Subscriber segmentationThe subscriber purchased products online from J.C. Penney a few times — more than three years ago. Penney’s wouldpresumablyclassifythesubscriberas“lapsed”customer.ButhestillopenPenney’se-mailsoften—partiallyoutofcuriositybutalsotocheckouttheoffer.Therefore,becauseofhishistoryasan“opener”anda“purchaser,”hemostlikelyfitintothebucketofsomeonewhoisapttoconvert.ThusPenneye-mailshimfrequently.

Frequency of e-mailsHe receives a good amount of J.C. Penney e-mails. But he never thought it was overwhelming — especially to the point of unsubscribing. He has shopped there before, and the next time he need something and a good deal appears in his inbox, it is likely that he will purchase again. It wasn’t until he started saving e-mails for this article that he noticed J.C. Penney e-mails him almost every day, even on weekends. This is apparent proof that — for a major online retailer with e-mail analysis resources — e-mailing every day garners enough revenue to outweigh e-mail unsubscribe.

To help decide a proper frequency, attach a dollar value to every subscriber, as follows. Over time the subscriber’s •e-mailfilewillproduceacertainamountofsales.Dividethatamountbythenumberofsubscribersandhaveagood estimate of what each subscriber is worth. This will help decide whether increasing frequency at the cost of subscribers is worth the increase in revenue.For example, assume an e-mail list contains 1,000 subscribers and revenue over time from marketing to that •list is $100,000. $100,000 divided by 1,000 equals $100, the rough value of each subscriber. If each e-mail causesfiverecipientstounsubscribe,butproducesonly$400inactualrevenue,the$500oflost“value”ismorethan the $400 of incoming revenue. This would indicate that the e-mails are too frequent, as they produce less revenue than the value of the subscribers that opted out.For acquisition purposes, this subscriber-value amount — $100 in the example above — will also help evaluate •options to grow your list. Using the example above, an acquisition program that costs $20 per new subscriber makes economic sense. One that costs $120 per new subscriber does not.

Also, analyse which types of subscribers are opting out. Opt-outs are not necessarily a bad thing if the subscribers wereneveragoodfit.Ifit’sunlikelytheywouldpurchaseanything,thinkofitasendingarelationshipthatneitherparty values. It will make the database cleaner and more effective.

Subject linesThe e-mail that offer-heavy subject lines had given way to some very creative and fun ones that were different and compelling and led him to open — simply because he noticed a change. This is something any online retailer should consider. Just changing what is now normally done may spark newfound interest among the subscribers and re-engage them.

In J.C. Penney’s case, the most interesting subject line for him was the blank one: there was no text on the subject-line section of the e-mail. He was curious if the company simply made an error, or if it was testing open rates from blank subject lines. He used to open the e-mail and was engaged, simply because he was curious.


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jcpenny Class Picks. $5.99

jcpenny 2DaysOnly!HowBigIsBig?

jcpenny Va-Va-View!Upto60%Off

jcpenny Finally,PantsThatFit!

jcpenny FirstDayFabulous!40-50%OffArizona

jcpenny Gracias!Merci!Danke!THANKYOU!

jcpenny So Many Choices, So Little Time

jcpenny AGreatBigThankYou!

jcpenny Imagine What A Penny Can Do

jcpenny LiveItUp!30-60%offHome

jcpenny JustforyourCAROLYNTWODAYS15-20%EXTRAOFF

jcpenny FindYourComfortZone!UpTo60!OffHome

jcpenny This Sale Is On Fire

J.C. Penney changes its e-mail subject lines often, utilising personalisation and discounts, as viewed in the author’s e-mail inbox

Try changing the patterns and organisation of e-mail subject lines. If else otherwise include a discount or sale amount, then try something funny or appealing in other ways.

ConclusionAnalysing what major online retailers do with their e-mail programs can help smaller merchants. Larger retailers have the staff and resources to heavily segment, test, tweak and review. Take advantage of the work they have done. Subscribe to their e-mails, and learn from them.

Source: Nye, C., 2011. E-mail Case Study: Analyzing J.C. Penney’s Frequency, Subject Lines [Online] Available at:< http://www.practicalecommerce.com/articles/2962-E-mail-Case-Study-Analysing-J-C-Penney-s-Frequency-Subject-Lines> [Accessed 14 November 2011].

QuestionsWhichideacanbeimplementedtodecidethefrequencyofincominge-mails?1. Whatissuesareoftenfacedbytheretailersregardingtheire-mailprograms?2. Whatwastheconclusionderivedfromtheanalysis?3.

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Application III

Vulnerability Case Study: Cookie Tampering

BackgroundCookies are technically small pieces of text that are sent to the Web client browser by a server and intended to be sent back to the server, unchanged, each time it accesses the same server or another server in the same domain. Cookiesareusedforauthentication,tracking,maintainingstateoverstatelessHTTP,aswellasmaintainingspecificinformation about the user such as their site preferences, etc. The minimum size of a cookie is a name-value pair.Cookies were originally developed for use in Web applications that used online or virtual shopping baskets. Cookies allowed for the contents of the basket to be changed, based on the user’s actions and tracked items in the basket between browser sessions.

Cookies are also used when users log in to a Web site. Users enter their username and password into a login page and, if they are authenticated, a cookie is saved that allows the Web site to know the users are already logged in as they navigate around the site. This permits them access to any functionality that may be available only to logged-in users, probably the primary use of cookies at this time.

Another use of cookies is to save user preferences for a site so that the site presentation and functionality can be personalised, based on the preferences of the user.

Cookies are used to track user actions across the site or domain. There are also some third-party cookies that allow for tracking across multiple sites. Most tracking done within a site or domain is done to gather usage data for that site.Trackingovermultiplesitesisdonebyadvertisingcompaniestobuildusageprofilestoallowformoretargetedmarketing.

Cookies are destroyed at the point the user closes the browser unless a deletion date has been set. If a deletion date has been set, the cookie will be destroyed on that date instead. The cookies that have deletion dates are called persistent cookies.

Cookies are supposed to be sent only to the server that set them or another server in the same Internet domain. However, a Web page in one domain may contain images or components that are referenced on a page in the original domain but which are stored on a server in another domain. When these components are retrieved, cookies can be set for the second domain. These are called third-party cookies.

There are some privacy and security concerns around the use (and misuse) of cookies and that has caused some legislation to be enacted in the United States and the European Union. It is also important to know that the only real restriction on cookies is a maximum of 300 at a time, which is respected by most browser manufacturers. The site can create one cookie or a lot of cookies - the number is truly up to the site in question and its needs.

Cookie Risks

Cookie theftCookies are supposed to be sent only between the Web browser and the server or servers in the same domain that set the cookie. But, if the cookie is being sent over an ordinary HTTP connection, it is visible to anyone across the network using a packet sniffer. This means cookies really cannot contain sensitive information. This is sometimes overcome by using HTTPS to encrypt the connection, but that’s not the solution because it only solves one of the problems associated with having sensitive data stored in cookies..


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For example, cross-site scripting can be used to send cookies to servers that should not be receiving that data. Encryption does not help stop this cookie theft, which is often done with a simple snippet of HTML posted to a site that users can be tricked into clicking on, and which sends their cookie for that site to a location that the attacker specifies.Becausetherequestiscomingfromthesamedomainintendedforthecookie,therearenoproblems.Thesecookiescanthenbeexploitedbyconnectingtothesamesiteusingthestolencookies,thusspoofingtheoriginalowner of the cookie.

Cookie poisoningCookies are supposed to be sent back to the server unchanged, but attackers can modify the value of a cookie before sending them back to the server. This is typically done to carry out some sort of attack against the server that relates to some sort of data contained in the cookie. For example, if a cookie contains the price per item for something in the shopping basket, a change to this value in the cookie may cause the server to charge the user a lower price for that item. This process of modifying a cookie before it is sent back to the server is called cookie poisoning. Sometimes, cookie poisoning is used after cookie theft.

MostWebsitesonlystorearandomlygenerateduniquesessionidentifierinthecookie,andeverythingelse is stored on the server. This pretty much eliminates the threat of cookie poisoning.

Cookie inaccuraciesEven outside of deliberate cookie tampering, there are aspects to how cookies are used in some situations that cause cookies to carry inaccurate data on which to base sensitive transactions.

One issue is that separate people using the same computer, browser, and user account will unavoidably share cookies. Another is that if a single user uses multiple browsers, multiple computers, or multiple user accounts, it means that the user will have multiple sets of cookies.

Cross-site cookingDespite the fact that each site is supposed to have its own set of cookies and to not be able to alter or set cookies foranyothersite,therearesomebrowserflawsthatcausecross-sitecookingvulnerabilitiesandallowmalicioussites to break this rule.

This is similar to cookie poisoning, but instead of the attacker attacking the site itself, the attacker is now attacking non-malicious users with vulnerable browsers.

Manybrowsershaveaflawinhowtheydealwithoverlyrelaxedcookiedomains.Theyaresupposedtorequireatwo-dotspecificationforalldomainsunderthefollowingtop-leveldomains:

.com•

.edu•

.net•

.org•

.gov•

.mil•

.int•

This is supposed to prevent the setting of a cookie for a subdomain like .com. So, the actual intent is that if you wishtosetacookieona.comsite,youneedtospecify“.mysite.com”asthetwo-dotname.Thisbreakswhenyouget to the international naming system for some domains like .com.au or .com.de. In some browsers, it’s possible for a cookie to be set for the entire .com.au (for example) domain.

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Another problem is how some browsers deal with periods. There is typically no check to see whether there is anything between the periods or if there is trailing period being used to override the local domain search path. This means thatacookiecanbesetfor“.com.,”whichthensendstheusertohttp://www.mywebsite.com./

Thisaddressisnotthe“real”one,buthowmanyuserswillcareaboutthetrailingperiod?Probablynotverymany.Even some seasoned users may not be adequately suspicious.

The third issue is that attackers can force cookies on random visitors, which are then relayed to a third-party site by setting IN A record and then redirecting users to the third-party site.

Anatomy of an ExploitCookie theft•

The attacker posts an auction that includes a link to what is advertised to be additional pictures or information �about the object in the auction. Instead, when users click on the link, their cookie for the auction Web site is sent to the attacker’s server, where a CGI script logs the information. Now the attacker can look through the list of cookies and pick some of the most recent cookies to use to try to log in to the auction site and spoof the user.

Cookie poisoningThe attacker visits an E-commerce site and adds an expensive item to his shopping cart. Then, the user examines •the cookie stored on his system from that site to see whether the cookie includes the total cost of the items in the attacker’s cart.Theattackerthenmodifiesthecookieonhissystemtochangethetotaltobe$5.00andresavesthecookie.Then,•the user returns to the E-commerce site and checks his cart to see that the total is now $5.00 and proceeds to order the items for the false price.

Cross-site cookingTheattackercraftsacookieforthedomain“.com.uk”andsetsupaWebsitetodistributethecookie.Then,the•attacker posts a link to his Web site on various bulletin boards or via e-mail, and when the users click on the link, they are given the attacker’s crafted cookie that can then overwrite or disrupt the real business they do with Web sites in that international domain.

Real-World ExamplesCookie theft•

A cookie theft vulnerability was reported in January 2005 in the Froogle (Google, Inc., Mountain View, �California) comparison shopping service. Although the details reported are sketchy, it appears that malicious Java-Script in a URL points to Froogle. Once a user clicks that link, the JavaScript executes a redirect to a malicious Web site, which then steals the user’s Google (Google, Inc., Mountain View, California) cookie. Thisstolencookieapparentlycontainedtheusernameandpasswordforthe“GoogleAccounts”centralisedlog in service, information that is used by multiple Google services.

Cross-site cookingAt the moment, cross-site cooking is a proof of concept that demonstrates the vulnerability and hasn’t emerged •in the wild.

Test TechniquesBlack-box testing•

Thefirstthingyouneedtodoisknowjustwhatcookiesarebeingcreatedbytheapplicationandwhen.But �allcookiesarenotkeptascreated.Somearemodifiedbytheapplicationasitruns,andyouneedtoknowwhenandhowthecookiesaremodified.


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As a black-box tester, you really need to explore the application, track what cookies are being set where, and exactly what they contain. Then, delete or modify the cookie, and see where the system is looking for the data from the cookies.Youneedtoseewheretheapplicationmodifiesthecookies.

I generally start with a spreadsheet and have the page name on the left, a column for the date and time obtained, and then the contents of the cookies on the right, so I can compare them and the track changes. You should make multiple passes through the product with different user identities to give you a good amount of data to examine, and always include as many user states as you can (logged in, not logged in, a variety of user permission levels, etc.).

Analyse the gathered cookiesOnce you have some data gathered, you need to examine the cookies you have gathered to try to get an idea of what they are supposed to tell the server or store. I typically start making notes on my spreadsheet if I think I see patterns or can make educated guesses at the cookie’s contents or intent. In essence, you are trying to reverse-engineer the cookies. The major items to look for are:

Predictability• : By looking at several samples of the cookies, can you detect a pattern in the format or makeup of thecookies?Therecanbeobviouslypredictableformatsthataremadeclearbytheuseofdelimitersorlabels.There can also be hints in the name of the cookie itself. What changes in the cookies were issued from different sessions?Fordifferentusers?Whatcausesthecookietobemodified?Sensitive data storage• : See if you can determine or guess what data is being stored in this cookie. Sometimes the labels help, but sometimes you can make educated guesses from hints of format, content, etc.Secureflag• :Isthesecureflagset?Thiswouldindicatethecookieisonlysupposedtobesentoverasecureconnection and may indicate the cookie contains sensitive data.Expiration data• : If a cookie holds session information, it should either have a very short expiration date or no expiration, so that it will be deleted when the browser session is closed. If the cookie is meant to contain non-sensitive information, it may have a longer expiration date.

Compare to documentationJust because you are doing black-box testing does not mean that you cannot seek out any documentation on what the individual cookies are supposed to do and contain.

If there is any documentation available, compare that to your spreadsheet of notes and guesses and see if any issues are immediately obvious. Disparities can emerge between documentation and reality, and there may be cases where securitymeasures(secureflagandexpirationdate)arenotinplacewheretheyshouldbe.Thesetestedcookiesbecomethefirsttomanipulateandexploreforvulnerabilities,asdescribedinthenextstep.

Modify cookiesNowyouneedtostartexperimentingwiththecookiestoseeifyoucanfindvulnerabilities.Ifyouhavedocumentationto use, you can start with the ones you marked as most interesting. Otherwise, you can start wherever you think the most risk is.

Startbymodifyingonefieldofonecookieatatime.Ifyouhavefoundapatterntothecookie,testbothinsideandoutside the pattern.

Naturally, cookies with one or more pieces of data in clear text are the easiest to modify, but to experiment with othercookiesandcookiefields,too.

Don’tstaywithinthefieldsizetherealcookieisusing.Itmaybepossibletocreateanoverflow,andthatshouldbe explored as well.

Don’tstaywithintheapparentdatatypeofthecookie’sfield.Theservershouldbecheckingallincomingdataandvalidating type before use.

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Write down the results of each attempt and listen to your intuition when it comes to potential vulnerabilities.

Cookie misuseDon’t forget to try other cookie uses that go beyond cookie tampering. Try testing as if you had stolen someone else’s valid cookie.

White-box testingWhite-box testing of cookie vulnerabilities uses the same basic theories, but because you have direct insight into the code that saves and reuses the cookies, you don’t have carry out the somewhat tedious task of reverse engineering the cookie itself.

Source: van der Linden, A. M., 2009. Vulnerability Case Study: Cookie Tampering [Online] Available at: <http://www.infosectoday.com/Articles/Cookie_Tampering.htm>[Accessed14November2011].

QuestionsWhatareCookies?1. HowtomanageCookies?2. WhatarethebenefitsofCookies?3.


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Holzman, C., 2003. • The healthy PC: preventive care and home remedies for your computer, McGraw-Hill Professional.Indian Express Group, 2001. • Leased line [Online] Available at: <http://www.networkmagazineindia.com/200110/basics1.htm> [Accessed 14 November 2011].Internet-101, 2011. About Newgroups [Online] Available at: <http://www.internet101.org/welcome-to-internet-•101/about-newsgroups> [Accessed 11 November 2011].Janet ma, 2008. • Internet cookies[VideoOnline]Availableat:<http://www.youtube.com/watch?v=QYFKbp_OedA> [Accessed 11 November 2011].Korpela, J. K., 1994. • What is WWW?[Online]Availableat:<http://www.cs.tut.fi/~jkorpela/www-eng.html>[Accessed 11 November 2011].LANTech, 1996, • Mime Types [Online] Available at: <http://www.ltsw.se/knbase/internet/mime.htp> [Accessed 11 November 2011].Levine, R. J. and Young, L. M., 2011. The Internet For Dummies, John Wiley & Sons.•Microsoft, 2011. • Firewalls [Online] Available at: <http://technet.microsoft.com/en-us/library/cc700820.aspx> [Accessed 14 November 2011].Miller, 2007. • Absolute Beginner’s Guide to Computer Basics, Pearson Education India.Miller, P. F, Vandome, F. A. and McBrewster, J., 2009. • Domain Name System, VDM Publishing House Ltd.Minoli, 1999. • Internet & Intranet Engineering, Tata McGraw-Hill Education.Musciano, C. and Kennedy, B., 2006. • HTML & XHTML: the definitive guide, O’Reilly Media, Inc.Ogsolution, 2008. • What is JavaScript? [Video Online] Available at: <http://www.youtube.com/watch?v=qtzjzMsJiO8>[Accessed11November2011].PCWorld Communications, Inc., 1998. • How It Works: Dial-Up Networking [Online] Available at: <http://www.pcworld.com/article/48467/how_it_works_dialup_networking.html>[Accessed14November2011].Portablefilmfestival, 2009.• History of the Internet [Video Online] Available at: <http://www.youtube.com/watch?v=d3VccCRiP98>[Accessed11November2011].Preethanm, V. V., 2002• . Internet security and firewalls, Premier Press.QuinStreet Inc., 2011. • Dynamic HTML [Online] Available at: <http://www.wdvl.com/Style/DHTML/> [Accessed 11 November 2011].sachinnaik04, 2010. • Connecting mobile internet to PC for all networks [Video Online] Available at: <http://www.youtube.com/watch?v=ZsI3OE-TiLw>[Accessed14November2011].Sarikaya, B., 2002. • Geographic location in the Internet, Springer.Sherman,J., 2003. • History of the Internet, Demco Media.Stitt, C. and Keilar, L., 2004. • Computer Virus, Blake Education.Teachucompinc, 2011. • HTML Tutorial XML, XHTML, & DHTML Training Lesson 1.6 [Video Online] Available at:<http://www.youtube.com/watch?v=FdPk45Ktgbc>[Accessed11November2011].TheMoCABlog, 2011. • Connecting Your TV to the Internet [Video Online] Available at: <http://www.youtube.com/watch?v=BKutF91eGkM>[Accessed14November2011].Wall, A., • History of Search Engines: From 1945 to Google Today [Online] Available at: <http://www.searchenginehistory.com/> [Accessed 11 November 2011].What Is My IP Address, 2000. • What is a Proxy Server?[Online]Availableat:<http://whatismyipaddress.com/proxy-server> [Accessed 14 November 2011].


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Recommended ReadingBrown, H., 2001. • Internet Tools, Cengage Learning College.Chambers, L. M., 2010. • PCs All-in-One For Dummies, John Wiley & Sons.Collin, H. M. S., 1997. • Setting up a Web server, Elsevier.Colmer,S.R.andThomas,M.T.,2005.Thesenior’sguidetotheInternet:surfing,shopping,e-mailandsecurity,•EKLEKTIKA, Inc.Eckel, G. and Steen, W., 1996. • Intranet working, New Riders.Elmer, G., 2002. • Critical perspectives on the Internet,Rowman&Littlefield.Greenlaw, 2005. • In-Line/On-Line, 2nd ed., Tata McGraw-Hill Education.Haig, M., 2001. • E-mail essentials: how to make the most of e-communication, Kogan Page Publishers.Jamsa, 2002. • Html & Web Design: Tips & Techniques, Tata McGraw-Hill Education.Kaye, K. B. and Medoff, J. N., 2001. • The World Wide Web: A Mass Communication Perspective, McGraw-Hill.Levene, M., 2010. • An Introduction to Search Engines and Web Navigation, 2nd ed., John Wiley and Sons.Loson, J., 1999. • The computer virus, Newark Central Schools.Luotonen, A., 1998. • Web proxy servers, Prentice Hall PTR.Moschovitis, J. P. C., 1999. • History of the Internet: a chronology, 1843 to the present, ABC-CLIO.Powell, A. T., 2003. • HTML & XHTML: the complete reference, McGraw-Hill Professional.Schiller, H. J. and Voisard, A., 2004. • Location-based services, Elsevier.Schneider, P. G, Evans, J. and Pinard, T. K., 2008. • The Internet: Illustrated, 5th ed., Cengage Learning.Speed, T. and Ellis, J., 2003. Internet • security: a jumpstart for systems administrators and IT managers, Digital Press.Stair, R. and Reynolds, G., 2011. • Principles of Information Systems, Cengage Learning.TechRepublic, 2003. • IT Professional’s Guide to E-mail Administration, CNET Networks Inc.Trans-European Research and Education Networking Association• Netskills, 2002. Internet users’ reference, Addison-Wesley.Vacca, R. J., 1996. • VRML: bringing virtual reality to the Internet, AP Professional.Williamson, 2001. • Xml: The Complete Reference, Tata McGraw-Hill Education.Yeager, J. N. and McGrath, E. R., 1996. • Web server technology: the advanced guide for World Wide Web information providers, Morgan Kaufmann.

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Self Assessment Answers

Chapter Ib1. d2. a3. b4. b5. c6. a7. d8. b9. a10.

Chapter IIb1. a2. b3. d4. a5. c6. b7. d8. a9. d10.

Chapter IIIc1. a2. b3. d4. a5. b6. d7. c8. c9. b10.

Chapter IVc1. d2. a3. c4. d5. a6. d7. b8. c9. b10.


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Chapter Va1. b2. c3. d4. a5. b6. c7. d8. a9. b10.

Chapter VIa1. b2. c3. d4. a5. b6. c7. d8. a9. b10.

Chapter VIIa1. b2. c3. d4. a5. b6. c7. d8. a9. b10.

Chapter VIIIa1. b2. c3. d4. a5. b6. c7. d8. a9. b10.