© 2009 Prentice-Hall, Inc. 11. 2 Technology in Action Chapter 7 Networking and Security: Connecting Computers and Keeping Them Safe from Hackers and Viruses

© 2009 Prentice-Hall, Inc. 1 1

© 2009 Prentice-Hall, Inc. 2

Technology in ActionTechnology in Action

Chapter 7Chapter 7

Networking and Security: Networking and Security:

Connecting Computers and Keeping Connecting Computers and Keeping

Them Safe from Hackers and VirusesThem Safe from Hackers and Viruses


Chapter TopicsChapter Topics

• Networking fundamentalsNetworking fundamentals• Network architectureNetwork architecture• Network componentsNetwork components• Peer-to-peer networksPeer-to-peer networks• Ethernet networksEthernet networks• Computer threatsComputer threats• Computer safeguardsComputer safeguards• Computer virusesComputer viruses


Networking FundamentalsNetworking Fundamentals

• Computer network:Computer network:– Two or more computers connected togetherTwo or more computers connected together– Devices connected to networks: nodes Devices connected to networks: nodes

• Benefits of a network:Benefits of a network:– Sharing resourcesSharing resources– Transferring filesTransferring files


Network ArchitectureNetwork Architecture

• Network designs:Network designs:– Locally administered:Locally administered:

• Peer-to-peer (P2P)Peer-to-peer (P2P)

– Centrally administered:Centrally administered:• Client/serverClient/server


Peer-to-Peer NetworksPeer-to-Peer Networks

• Nodes communicate Nodes communicate with each other:with each other:– PeersPeers

• Share peripheral Share peripheral devicesdevices

• Used in home and Used in home and small office networks small office networks


Client/Server NetworksClient/Server Networks

• Client computers:Client computers:– Users who make Users who make

requests requests

• Server computers:Server computers:– Provide resources to Provide resources to

clientsclients– Central network controlCentral network control

• InternetInternet– A large, multiserver,A large, multiserver,

multiclient network.multiclient network.


LANs and WANsLANs and WANs

• Local area network (LAN):Local area network (LAN):– Nodes are within a small geographic region:Nodes are within a small geographic region:

• HomesHomes• SchoolsSchools• Small businessesSmall businesses

• Wide area network (WAN):Wide area network (WAN):– LANs connected over long distances:LANs connected over long distances:

• A few miles to thousands of milesA few miles to thousands of miles• Use telecommunications linesUse telecommunications lines


Network ComponentsNetwork Components• Transmission mediaTransmission media• Network communication Network communication

devicesdevices• SoftwareSoftware


Transmission MediaTransmission Media• Provides communications channel between Provides communications channel between

nodesnodes• Forms of media:Forms of media:

– Twisted pairTwisted pair– Coaxial cableCoaxial cable– Fiber-optic cableFiber-optic cable– Radio waves:Radio waves:

• WirelessWireless

• Bandwidth:Bandwidth:– Data transfer rateData transfer rate– ThroughputThroughput


Network AdaptersNetwork Adapters

• Devices connected to or installed in nodes:Devices connected to or installed in nodes:– Network interface cards (NICs)Network interface cards (NICs)– External network adaptersExternal network adapters

• Enable communication between nodesEnable communication between nodes


Network Navigation DevicesNetwork Navigation Devices• Devices that help make data flow possibleDevices that help make data flow possible• Routers:Routers:

– Route data between networksRoute data between networks

• Switches:Switches:– Receive data and retransmit it to nodes on the Receive data and retransmit it to nodes on the

same networksame network


Networking SoftwareNetworking Software

• Peer-to-Peer SoftwarePeer-to-Peer Software• Built into operating systems that support Built into operating systems that support

networkingnetworking– WindowsWindows– Mac OSMac OS

• Client/Server Software Client/Server Software • Network operating system (NOS) softwareNetwork operating system (NOS) software

– Windows XP ProfessionalWindows XP Professional– Windows Server 2003Windows Server 2003– Novell NetwareNovell Netware– Windows Vista EnterpriseWindows Vista Enterprise


Types of Peer-to-Peer NetworksTypes of Peer-to-Peer Networks

• Wired Ethernet networksWired Ethernet networks

• Wireless Ethernet networksWireless Ethernet networks

• Power-line networksPower-line networks


Wired Ethernet NetworksWired Ethernet Networks

• Ethernet network Ethernet network adapters are used to adapters are used to connect nodesconnect nodes– NIC cardNIC card– PC CardPC Card– USB adapter USB adapter

• Computers are Computers are connected to each connected to each other using unshielded other using unshielded twisted pair cabletwisted pair cable

Ethernet

Phone


Ethernet SwitchesEthernet Switches

• Keep track of data packetsKeep track of data packets

• Amplify and retransmit signalsAmplify and retransmit signals

• Keep the network running efficientlyKeep the network running efficiently


Ethernet RoutersEthernet Routers

• Transfer packets from one network to anotherTransfer packets from one network to another• Home Internet routers transfer data from the Home Internet routers transfer data from the

Internet to the home network.Internet to the home network.

Router


Wireless Ethernet NetworksWireless Ethernet Networks

• Uses radio waves to connect nodesUses radio waves to connect nodes• Basically an Ethernet network that uses radio Basically an Ethernet network that uses radio

waves instead of wireswaves instead of wires• Each node requires a wirelessEach node requires a wireless network adapter:network adapter:

– TransceiversTransceivers


Power-Line NetworksPower-Line Networks

• Computers are Computers are connected to a connected to a house’s electrical house’s electrical wiring to create a wiring to create a networknetwork

• Power-line network Power-line network adapter is used to adapter is used to connect nodes to connect nodes to electrical outletselectrical outlets


Choosing a Peer-to-Peer Choosing a Peer-to-Peer NetworkNetwork

• Things to consider:Things to consider:- - Whether you want wireless communicationsWhether you want wireless communications

- - How fast you want your network connection to beHow fast you want your network connection to be

- - Whether existing wiring is availableWhether existing wiring is available

- How much money you can spend on your network

Comparing the Major Types of Home Networks

Wired Ethernet

Wireless 802.11g

Wireless Enhanced

G

Wireless802.11n

Maximum dataTransfer rate (bandwidth)

100 Mbps to

1,000 bps (1 gigabit)

54 Mbps 108 Mbps 100 to 630 bps

Relative installation

and equipment costs

for networkingtwo computers

$ $ $$ $$$


Configuring Software Configuring Software for a Home Networkfor a Home Network

• Windows Windows – Windows Vista home versionsWindows Vista home versions

• Network setup wizardNetwork setup wizard– Wired or wirelessWired or wireless

– Windows XPWindows XP• Network setup wizardNetwork setup wizard

– Windows 98Windows 98• Configure manuallyConfigure manually

– Help has a clear instructionHelp has a clear instruction


Computer ThreatsComputer Threats• Cybercrimes are criminal acts conducted through Cybercrimes are criminal acts conducted through

the use of computers by cybercriminals.the use of computers by cybercriminals.


Hackers Hackers

• Anyone who unlawfully accesses a Anyone who unlawfully accesses a computer systemcomputer system

• Types of hackers: Types of hackers: – White-hatWhite-hat– Black-hatBlack-hat– Script kiddiesScript kiddies


What Hackers DoWhat Hackers Do

• Steal information from computers:Steal information from computers:– Credit card numbersCredit card numbers– Bank account numbersBank account numbers

• Internet packet sniffingInternet packet sniffing

• Commit identity theftCommit identity theft


How Computers Are AttackedHow Computers Are Attacked

• Trojan horseTrojan horse• Backdoor Backdoor

program program – ZombiesZombies

• Denial of Denial of service attacksservice attacks


How Hackers Gain AccessHow Hackers Gain Access

• Direct access:Direct access:– Hacking softwareHacking software

• Indirect access:Indirect access:– Internet connectionInternet connection– Logical portsLogical ports


Computer Safeguards:Computer Safeguards:FirewallsFirewalls

• Software programs or hardware designed Software programs or hardware designed to close logical ports to invadersto close logical ports to invaders– A firewall is built into Windows VistaA firewall is built into Windows Vista– More robust firewalls are available from More robust firewalls are available from

other vendorsother vendors– Firewalls are critical if you have an always-Firewalls are critical if you have an always-

on broadband connectionon broadband connection


Protecting a Wireless NetworkProtecting a Wireless Network

• Wireless network range doesn’t stop at the Wireless network range doesn’t stop at the property lineproperty line

• Default device and network ID settings Default device and network ID settings allow intruders to enter the networkallow intruders to enter the network

• Internet bandwidth can be stolenInternet bandwidth can be stolen

• Computers can be vulnerable to hacker Computers can be vulnerable to hacker intrusion and takeoverintrusion and takeover


Computer Threats: VirusesComputer Threats: Viruses

• A program that attaches itself to another A program that attaches itself to another program and spreads itself to other program and spreads itself to other computerscomputers

• Viruses are hidden within the code of a Viruses are hidden within the code of a host programhost program


How Does a Computer How Does a Computer Catch a Virus?Catch a Virus?

• Viruses copy Viruses copy themselves themselves

• Infect a file on your Infect a file on your computercomputer

• Spread by sharing Spread by sharing disks disks or flash drives

• E-mail attachments E-mail attachments are the most likely are the most likely source of a virussource of a virus


What Viruses DoWhat Viruses Do

• Replicate themselves:Replicate themselves:– Slow down networksSlow down networks

• Secondary objectives:Secondary objectives:– Display annoying messagesDisplay annoying messages– Delete files on the hard driveDelete files on the hard drive– Change computer settingsChange computer settings


Types of VirusesTypes of Viruses

• Boot-sector virusesBoot-sector viruses– Replicate themselves in the boot sector of the hard Replicate themselves in the boot sector of the hard

drivedrive• Logic bombsLogic bombs

– Activate when certain conditions are metActivate when certain conditions are met• Time bombsTime bombs

– Viruses that are triggered by the passage of time or Viruses that are triggered by the passage of time or on a certain dateon a certain date

• WormsWorms– Travel between systems through networksTravel between systems through networks


Types of VirusesTypes of Viruses

• Script viruses:Script viruses:– Hidden on Web pages as mini programs Hidden on Web pages as mini programs

• Macro viruses:Macro viruses:– Attached to documentsAttached to documents– Series of commandsSeries of commands

• E-mail virusE-mail virus– Use e-mail address book to distribute the virusUse e-mail address book to distribute the virus

• Encryption virusesEncryption viruses– Compresses files using a complex encryption key Compresses files using a complex encryption key – User must pay to get the files unlockedUser must pay to get the files unlocked


Virus ClassificationsVirus Classifications

• Polymorphic viruses:– Periodically rewrite themselves to avoid

detection

• Multipartite viruses:– Infect multiple file types

• Stealth viruses:– Erase their code from the hard drive and

reside in the active memory


Antivirus SoftwareAntivirus Software

• Programs designed to detect viruses:Programs designed to detect viruses:– Scan files looking for virus signatures (unique code)Scan files looking for virus signatures (unique code)– Provide options for deleting or fixing infected filesProvide options for deleting or fixing infected files– Inoculate files against further infectionInoculate files against further infection

• Detect known virusesDetect known viruses• Antivirus programs need to be updated frequentlyAntivirus programs need to be updated frequently


Chapter 7 Summary QuestionsChapter 7 Summary Questions

• What is a network, and what are the What is a network, and what are the advantages of setting up one?advantages of setting up one?



• What is the difference between a What is the difference between a client/server network and a peer-to-peer client/server network and a peer-to-peer network?network?



• What are the main components of every What are the main components of every network?network?



• What are the most common home What are the most common home networks?networks?



• What are wired Ethernet networks, and What are wired Ethernet networks, and how are they created? how are they created?



• What are wireless Ethernet networks, and What are wireless Ethernet networks, and how are they created? how are they created?



• How are power-line networks created, and How are power-line networks created, and are they viable alternatives to Ethernet are they viable alternatives to Ethernet networks?networks?



• How can hackers attack a network, and How can hackers attack a network, and what harm can they cause? what harm can they cause?



• What is a firewall, and how does it keep What is a firewall, and how does it keep my computer safe from hackers? my computer safe from hackers?



• Why are wireless networks more Why are wireless networks more vulnerable than wired networks, and what vulnerable than wired networks, and what special precautions are required to ensure special precautions are required to ensure my wireless network is secure?my wireless network is secure?



• From which types of viruses do I need to From which types of viruses do I need to protect my computer? protect my computer?



• What can I do to protect my computer from What can I do to protect my computer from viruses? viruses?

Documents

© 2009 Prentice-Hall, Inc. 11. 2 Technology in Action Chapter 7 Networking and Security: Connecting Computers and Keeping Them Safe from Hackers and Viruses