dr. j. vijipriya - information and communication technology chapter 8 the internet
TRANSCRIPT
Information and Information and Communication Communication TechnologyTechnology
Chapter 8The Internet
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 1
What is Internet?What is Internet? a network of networks huge collection of computer networks , freely
exchange information To ensure the delivery of the data to the right
computer, each computer on the Internet is given an address(Domain Name System or IP address)
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 2
How does the Internet work?How does the Internet work?In order to make the Internet work, it requires:1. a physical connection between the computers2. a Transmission Control Protocol/Internet Protocol (TCP/IP)
◦ all kinds of computers with different operating systems run on the Internet
◦ All computers to communicate over the Internet
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 3
Getting connected to Getting connected to Internet Internet Two basic ways:1. dial-up internet connection2. broad band or leased line internet connectionDial-up internet connection dialing into an Internet service provider's (ISP)
computer
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 4
Getting connected to Getting connected to Internet con…Internet con…To establish a dial-up connection to the Internet,
requires following: ◦ An account with an ISP (a company that provides the Internet
access)◦ A telephone connection◦ Modem (external/internal): used to connect the telephone line to the
computer◦ Communication software: e internet browsers such as internet
explorer, Mozila, Firebox, Chrome, Netscape Navigator, Opera, SafariAdvantages of dial-up connection:
◦ flexible: use it anywhere if you have an account, telephone line and computer
◦ Less monthly payment: it charges based on the amount of time usage
Disadvantages of dial-up connection:◦ Not faster: it is very slow because its the public service
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 5
Getting connected to Getting connected to Internet con…Internet con…Broad band internet connection
◦ direct connection to an ISP if you have a fixed cable or a dedicated phone line to the ISP
Advantages of broad band connection:◦ Faster: because use a free telephone line is dedicated for this
internet service oDisadvantages of broad band connection:
◦ the fixed amount of money must be paid monthly regardless of usage
◦ Not flexible: have a fixed telephone line and use it on that area only
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 6
ProtocolsProtocols the formal rules governing the exchange of information between
computers provide reliable and efficient transfer of information define the format in which data and messages are to be sent Why Protocols?
◦ Most computers are not similar, and they have to share the same language to understand each other
Example : TCP/IP
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 7
Protocols Con…Protocols Con…
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 8
Protocols con…Protocols con…To send a message across the Internet to another
user:
In Sender side◦ TCP divides the data into manageable units called packets ◦ attaches the information necessary to each packet for
reassemble the data and check for errors◦ IP labels all the packets with a header containing the address of
the destination and sends them on their way
In Receiver side ◦ Once the packets reach their destination, the receiver removes the
IP header ◦ The receiver uses the data that TCP attached to each packet to make
sure none of the packets have been lost or damaged◦ The packets are reassembled into the original message◦ If the receiver discovers a damaged packet, it sends a message to the
sender asking it to resend the packet.
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 9
Protocols con…Protocols con…Website refers to a collection of one or more web pages on the webRelationship between browsers (client) and the
web servers: Is a client/server relationship The web client (browser) requests information from the web server
(containing the requested information) The server delivers itTo access pages on web servers by using a
browser: tell your browser what web page you want to view, It goes to the web server that holds the page and retrieves it The links contained in web pages can point to areas within the
same page, to other pages residing on the same web server
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 10
Relationship between browsers (client) and the web servers:
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 11
Social Network ServiceSocial Network Service focuses on building online communities of people who share
interests and/or activities provide a variety of ways for users to interact, such as e-mail and
instant messaging services encouraged new ways to communicate and share information used regularly by millions of people types of social networking services
◦ Facebook widely used worldwide◦ MySpace, Twitter and LinkedIn in North America◦ Nexopia in Canada◦ Bebo, Hi5, MySpace, dol2day in Germany◦ Tagged, XING; and Skyrock in Europe◦ Orkut and Hi5 in South America and Central America◦ Friendster, Multiply, Orkut, Xiaonei and Cyworld in Asia and
Pacific Islands
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 12
Social Network Service Social Network Service Con…Con…
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 13
History of Social Network History of Social Network ServiceService
Early social networks via computer-mediated communication supported by Usenet, ARPANET, LISTSERV, bulletin board services (BBS) and EIES: Electronic Information Exchange Service
Early social networking websites started in the form of online communities◦ The WELL (1985)◦ Theglobe.com (1994),◦ Geocities (1994) ◦ Tripod (1995)◦ Classmates.com (1995)◦ SixDegrees.com (1997)◦ Friendster, MySpace, Bebo(2003)◦ Facebook (2004), ◦ MySpace, Yahoo, ITV (2005)◦ Twitter(2009)
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 14
Internet Applications or Internet Applications or ServicesServicesTypes of Internet Services1. World wide web2. Electronic mail3. File Transfer Protocol (FTP)4. Telnet5. Internet Relay Chat (IRC)6. Internet Telephony7. Video conferencing
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 15
Internet Services Con…Internet Services Con…
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 16
Internet Applications or Internet Applications or Services con…Services con…World Wide Web (WWW) a vast collection of documents stored on Internet computers The web documents contain links that lead to other web pages uses Hypertext Mark-up language (HTML) to design a web document user can click on any of the links and jump to the related document (non
linear) The web includes text, voice, video, pictures, graphics, sound etc (rich
media system) A web user can fill in forms on-line, run programs, select options
( interactive )Basic Internet Terms: Web Server
◦ a program and a computer clubbed into one entity which responds to the requests from web browsers for Internet resources
Home Page ◦ the first hypertext document to be shown when a user follows a link to
the web server.
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 17
Internet Applications or Internet Applications or Services con…Services con… Hyper Text Transfer Protocol (HTTP)
◦ the protocol used by the Web to transfer hypertext documents & other Internet resources
Uniform Resource Locator (URL)◦ a special scheme tells the user exactly where a resource is located on
the Internet◦ example: http://www.hu.edu.et
Web Browser ◦ a program allows a user to display & interact with a hypertext
document How to surf the web with a Browser
◦ Netscape Navigator, Microsoft Internet Explorer. ◦ Both browsers have a simple toolbar for navigating the web including
buttons to move backward and forward through pages and reload the current page.
◦ Several other options, including printing and searching, are also available from the toolbar
◦ when the mouse cursor passes over a hyperlink, it changes to a hand with pointing finger.
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 18
Internet Applications or Internet Applications or Services con…Services con…E-mail a user can send and receive mail through computers to and from
any Internet user transmit text, messages, audio and video clips to just one
user or a group of users while Large documents can be attached Users can read, print, forward, answer or delete a message cheaper and faster in comparison to other communication services assigned a unique address, used by the e-mail network to
deliver the message
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 19
Internet Applications or Internet Applications or Services con…Services con…FTP (File Transfer Protocol) allows a user to transfer data between computers on the Internet allow users to manage and download files from computers
connected to the InternetTelnet allows one computer to connect to another computer,
anywhere in the world allows user to log into computers on the Internet where user
commands as text will be executed To Telnet to a computer, user must know its address, consist of
domain name (locis.loc.gov) or IP address (140.147.254.3)
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 20
Internet Applications or Internet Applications or Services con…Services con…Usenet News global electronic bulletin board system in which millions of
computer users exchange information from academic to recreational topics
Usenet messages are stored on central computers, users must connect to these computers to read or download the messages posted to these groups
But email messages arrive in the electronic mailboxes of each list member
not as popular nowadays , instead Blogs and RSS (Rich Site Summary) feeds are newer modes of communication
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 21
Internet Applications or Internet Applications or Services con…Services con…Chat allow users on the Internet to communicate with each other by
typing in real time. Internet Relay Chat (IRC) allows participants to communicate to each other on hundreds of
channels ( based on specific topics) To access IRC, user must use an IRC software programInstant messaging allows a user on the Web to contact another user currently
logged in and type a conversation
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 22
Internet Applications or Internet Applications or Services con…Services con…Search Engine computer software that compiles lists of documents respond to a user entry, or query, by searching the lists and
displaying a list of documents (text or URL of website) that match the search query
Examples: Google, Mama, Yahoo etc..
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 23
Social Network Services :-Social Network Services :-Typical structureTypical structure1. Basics Features2. Normal Features3. Additional FeaturesBasics FeaturesTwo categories
1. Internal Social Networking (ISN)◦ closed/private community that consists of a group of
people within a company, association, society, education provider and organization
II. External Social Networking (ESN) Sites◦ open/public and available to all web users to
communicate and are designed to attract advertisers◦ smaller specialized communities (i.e. linked by a single
common interest e.g. TheSocialGolfer, ACountryLife.Com, Great Cooks Community)
◦ large generic social networking sites (Eg:-MySpace, Facebook , Twitter and Bebo etc),
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 24
Social Network Social Network Services :-Services :-Typical structure Con…Typical structure Con…Basics Features Con…In Social Network, Users can: create a profile for themselves Upload a picture of themselves, Often be "friends" with other users. Both users must confirm that they are friends before they are
linked. For example, if Alice lists Bob as a friend, then Bob would have to approve Alice's friend request before they are listed as friends.
Some social networking sites have a "favorites" feature that does not need approval from the other user
Social networks usually have privacy controls that allows the user to choose who can view their profile or contact them, etc…
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 25
Social Network Services :-Social Network Services :-Typical structure Con…Typical structure Con…Normal FeaturesA set of features are considered essential to qualify as a social
networking service, namely: The ability to set up and customize a personal 'profile' An ability for members to comment Fine granular control of who sees what (privacy settings) Ability to block an unwanted member Have own page of personal (blog like) entries or notes and
individual picture albums Ability to own, form or be member of a Group or Community
within the network Ability to include "Social Apps" or "Gadgets“ can create online
contact and spread of information
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 26
Social Network Services :-Social Network Services :-Typical structure Con…Typical structure Con…Additional features Ability to create groups share common interests or affiliations,
upload or stream live videos, and hold discussions in forums Lately, mobile social networking has become popular Mobile phone users can create their own profiles, make
friends, participate in chat rooms, create chat rooms, hold private conversations, share photos and videos, and share blogs by using their mobile phone
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 27
Emerging Trends in Social Emerging Trends in Social NetworksNetworks use of Social Networks in the Science communities. Researchers
sharing information and knowledge with one another Social Network use by college students to network with professionals
for internship and job opportunities One popular use for this new technology is social networking between
businesses. Companies found that social networking sites such as Facebook,
MySpace and twitter are great ways to build their brand image five major uses for businesses and social media. They are:i. to create Brand Awareness, online reputation management tool,
recruiting, ii. learn about new technologies and competitors and to intercept
potential prospectsiii. companies are able to drive traffic to their own online sitesiv. encouraging their consumers and clients to have discussions on how to
improve or change products or servicesv. Social networks operate under an autonomous business model via
online advertisement, in which a social network's members serve dual roles as both the suppliers and the consumers of content
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 28
Issues in Social Network Services
1. Privacy Users giving out too much personal information and increasingly
the threat of sexual predators Users of these services need to be aware of data theft or viruses Medical and scientific research data are public, republishing it
in a research paper might be considered invasion of privacy2. Notifications on websites social networking sites to send out only 'positive' notifications to
users if a user is moved to the top of another user's friends list. but no notification is sent if they are moved down the list or
they are removed totally from a person's friends list3. Potential for misuse The relative freedom afforded by social networking services has
caused concern regarding the potential of its misuse by users Eg: Craete Fake profile
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 29
Issues in Social Network Issues in Social Network Services con…Services con…Risk for child safety misuse by child and teenagers of social network services,
particularly in relation to online sexual predators
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 30
Social Network Services in Social Network Services in InvestigationsInvestigationsSocial network services are increasingly being
used in legal and criminal investigations MySpace and Facebook used by police, probation, and
university officials to prosecute users of said sites, evidence in court
Facebook is increasingly being used by school administrations and law enforcement agencies as a source of evidence against student users
Facebook to help their crack down on knife and gun crime
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 31
Application domainsApplication domains1. Business applications Social networks connect people at low cost; this can be beneficial for
entrepreneurs and small businesses looking to expand their contact/customer base
Interactive technology makes it possible for people to network with their peers from anywhere, at anytime in an online environment by creating informative and interactive meeting places
2. Medical applications Social networks adopted by healthcare professionals as a means to
manage institutional knowledge, disseminate peer to peer knowledge and to highlight individual physicians and institutions
For people suffering from life altering diseases, PatientsLikeMe offers its members the chance to connect with others dealing with similar issues
SoberCircle for alcoholics and addicts to communicate with one another and strengthen their recovery through the encouragement of others who can relate to their situation.
Daily strength support groups for a wide array of topics SparkPeople for peer support during weight loss
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 32
What is Malware?What is Malware? Malicious software designed to infiltrate or damage a computer
system without the owner's informed consent Malware includes computer viruses, worms, trojan horses,
spyware, dishonest adware, and other malicious and unwanted software, defective software contains harmful bugs
Most Malware have the following phases while affecting your computer system:
1. Dormancy phase - create a sense of trust in the user2. Propagation phase - duplicates itself without making damage3. Triggering phase -triggered by some occurrence such as date or a
particular number of replications, sequence of keystroke4. Damage phase- formatting the hard disk thereby destroying all the
data in it, reserving space on disk so that files cannot be stored on it etc…
Types of malware: viruses, worms, trojan horses, spyware
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 33
Malware Con…Malware Con…VirusesA computer virus attaches itself to a program or file enabling it to
spread from one computer to another1. Macro Viruses A macro virus, often scripted into common application programs
such as Word or Excel, is spread by infecting documents. When the application is running, this allows the macro virus to
spread amongst the operating systems Examples : Melissa A and Bablas pc2. Network Viruses Network viruses rapidly spread through a Local Network Area (LAN),
and sometimes throughout the internet. Example: Nimda and SQLSlammer.3. Logic bomb virus piece of code that is inputted into a software system clicking on an internet browser or opening a particular file, the logic
bomb virus is set off
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 34
Malware Con…Malware Con…Viruses Con…4. Companion Viruses Companion viruses take advantage of MS-DOS. This virus creates a
new file with he .COM extensions, .EXD extension, .EXE extension is rare among Windows XP computers does not use the MS-DOS5. Boot Sector Viruses Boot sector viruses generally hide in the boot sector, either in the
bootable disk or the hard drive. Unlike most viruses, this virus does not harm the files in the hard
disk, but harm the hard disk itself. spread rapidly by floppy disks and not on CD-ROMs6. Multipartite Viruses spread through infected media and usually hide in the
memory Gradually moves to the boot sector of the hard drive and infects executable files on the hard drive and later across the computer system
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 35
Malware Con…Malware Con…Worm similar to a virus by design and is considered to be a sub-class of a
virus capability to travel without any human action Due to the copying nature of a worm and its capability to travel across
networks the end result is the worm consumes too much system memory (or network bandwidth), causing Web servers, network servers and individual computers to stop responding
allow malicious users to control your computer remotelyTrojan horse at first glance will appear to be useful software but will actually do
damage once installed or run on your computer designed to be more annoying than malicious (like changing your
desktop, adding silly active desktop icons) cause serious damage by deleting files and destroying information on
your system create a backdoor for that gives malicious users access to your system,
possibly allowing confidential or personal information No self-replication unlike other viruses
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 36
Malware Con…Malware Con…Combating Viruses, Worms and Trojan Horses few primary indicators that your system might be infected: Runs consistently slower than normal Stops responding or locks up often Crashes and restarts every few minutes Restarts on its own and then fails to run normally Applications don't work properly Disks or disk drives are inaccessible Printing doesn't work correctly You see unusual error messages You see distorted menus and dialog boxes
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 37
Adware and SpywareAdware and SpywareAdware Advertising Supported Software is bundled within software a
computer owner purchases collect data on which sites the user visits, send this data back to
the company and deliver advertising based on the information using a free software product that includes adware, so a user may
opt to purchase a registered or licensed version without adware to remove the ads
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 38
Adware and SpywareAdware and SpywareSpyware type of malware that is considered by many to be privacy-invasive.
Spyware can steal a user’s information or corrupt the user’s system files
Antivirus software today detects and removes both adware and spyware
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 39
How to protect your How to protect your computer against virusescomputer against viruses
Protect your computer current with the latest updates. Use an Internet firewall (Note: Windows XP with SP2 has a firewall
already built-in and active). A firewall is a system that prevents unauthorized use and access to
your computer A firewall can be either hardware or software. Subscribe to industry standard antivirus software and keep it
current. Never open an e-mail attachment from someone you don't know Avoid opening an e-mail attachment from someone you know,
unless you know exactly what the attachment is because the sender may be unaware that it contains a virus.
If you use Microsoft Office applications, it's a good idea to keep them updated too
9/12/2015
Dr. J. VijiPriya, Assistant Professor, Hawassa University, Ethiopia 40