Dr. J. VijiPriya - Information and Communication Technology Chapter 8 The Internet

Information and CommunicationInformation and Communication
TechnologyTechnology
Chapter 8
The 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)
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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 computers
2. 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
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Getting connected to InternetGetting connected to Internet
Two basic ways:
1. dial-up internet connection
2. broad band or leased line internet connection
Dial-up internet connection
 dialing into an Internet service provider's (ISP) computer
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con…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, Safari
Advantages 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
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con…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 o
Disadvantages 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
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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
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Protocols Con…Protocols Con…
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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.
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Protocols con…Protocols con…
Website
 refers to a collection of one or more web pages on the web
Relationship 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 it
To 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
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Relationship between browsers (client) and the web servers:
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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
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Social Network Service Con…Social Network Service Con…
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History of Social Network ServiceHistory of Social Network Service
 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)
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Internet Applications or ServicesInternet Applications or Services
Types of Internet Services
1. World wide web
2. Electronic mail
3. File Transfer Protocol (FTP)
4. Telnet
5. Internet Relay Chat (IRC)
6. Internet Telephony
7. Video conferencing
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Internet Services Con…Internet Services Con…
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con…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.
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con…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.
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con…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
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con…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
Internet
Telnet
 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)
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con…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
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con…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 program
Instant messaging
 allows a user on the Web to contact another user currently logged in and type
a conversation
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con…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..
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Social Network Services :-Social Network Services :-
Typical structureTypical structure
1. Basics Features
2. Normal Features
3. Additional Features
Basics Features
Two 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),
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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…
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Normal Features
A 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
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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
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Emerging Trends in Social NetworksEmerging Trends in Social Networks
 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
prospects
iii. companies are able to drive traffic to their own online sites
iv. encouraging their consumers and clients to have discussions on how to improve
or change products or services
v. 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
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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 privacy
2. 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 list
3. 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
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Issues in Social Network ServicesIssues in Social Network Services
con…con…
Risk for child safety
 misuse by child and teenagers of social network services, particularly in relation to
online sexual predators
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Social Network Services inSocial Network Services in
InvestigationsInvestigations
Social 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
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Application domainsApplication domains
1. 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
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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 user
2. Propagation phase - duplicates itself without making damage
3. Triggering phase -triggered by some occurrence such as date or a particular
number of replications, sequence of keystroke
4. 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
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Malware Con…Malware Con…
Viruses
A computer virus attaches itself to a program or file enabling it to spread from one
computer to another
1. 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 pc
2. 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
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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-DOS
5. 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-ROMs
6. 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
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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 remotely
Trojan 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
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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
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Adware and SpywareAdware and Spyware
Adware
 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
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Adware and SpywareAdware and Spyware
Spyware
 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
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How to protect your computerHow to protect your computer
against virusesagainst 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

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