Networking And Security5

© 2008 Prentice-Hall, Inc. 1

Technology in ActionTechnology in ActionTechnology in ActionTechnology in Action

1


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

• 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

• Each is a Node Each is a Node

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


Network ArchitectureNetwork Architecture

• Network designs:Network designs:– Individual PC controlled:Individual PC controlled:

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

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

Peer-to-peer

Client/server


Peer-to-Peer NetworksPeer-to-Peer Networks

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

• Share peripheral Share peripheral devices:devices:– PrintersPrinters– Scanners Scanners

• Home and small office Home and small office networks networks


Client/Server NetworksClient/Server Networks

• Client computers:Client computers:– Users Users

• Server computers:Server computers:– Provide resources to clientsProvide resources to clients– 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 Transmission mediamedia

• Network adaptersNetwork adapters• Navigation Navigation

devicesdevices• Network softwareNetwork software


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

nodesnodes• Forms of media:Forms of media:

– Telephone wire:Telephone wire:• 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 (NIC)Network interface cards (NIC)– External network adapterExternal network adapter

• Enable communication between nodesEnable communication between nodes


Network Navigation DevicesNetwork Navigation Devices

• Devices that help make data Devices that help make data flow possibleflow possible

• Routers:Routers:– Route data between networksRoute data between networks

• Switches:Switches:– Receive data and retransmit it Receive data and retransmit it

to nodes on the networkto nodes on the network


Networking SoftwareNetworking Software

• Peer-to-Peer Software:Peer-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

• Power-linePower-line

• PhonelinePhoneline

• EthernetEthernet

• Wireless Wireless


Ethernet NetworksEthernet 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

RJ-45

Phoneline


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 NetworksWireless Networks

• Use radio waves to connect nodesUse radio waves to connect nodes• Basically an Ethernet network that uses radio waves Basically an Ethernet network that uses radio waves

instead of wiresinstead of wires• Each node requires a wireless network adapter:Each node requires a wireless network adapter:

– Transceiver Transceiver


Wireless Computing LandscapeWireless Computing Landscape


UTD Wireless Access PointsUTD Wireless Access Points


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


Phoneline NetworksPhoneline Networks

• Computers are connected Computers are connected to a house’s telephone to a house’s telephone wiring to create a networkwiring to create a network

• Home phoneline network Home phoneline network adapter is used to adapter is used to connect nodes to phone connect nodes to phone jacksjacks


Choosing a Peer-to-Peer NetworkChoosing a Peer-to-Peer Network

• Things to consider:Things to consider:– Existing wiringExisting wiring– Wireless or wiredWireless or wired– Speed of the networkSpeed of the network– Cost of the networkCost of the 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 installationand equipment costsfor networkingtwo computers

$ $ $$ $$$


Configuring Software Configuring Software for a Home Networkfor a Home Network

• Windows operating system:Windows operating system:– Windows Vista home versionsWindows Vista home versions

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

– Windows XP:Windows XP:• Network setup wizardNetwork setup wizard

– Windows ME:Windows ME:• Network setup wizardNetwork setup wizard

– Windows 98:Windows 98:• Configure manuallyConfigure manually

– Help has a clear instructionsHelp has a clear instructions


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


Denial of Service AttacksDenial of Service Attacks

• Backdoor Backdoor programs programs – Trojan horseTrojan horse– Zombies Zombies

• 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 SafeguardsComputer SafeguardsFirewalls Firewalls

• Software programs or Software programs or hardware designed to hardware designed to close logical ports to close logical ports to invadersinvaders– A firewall is built into A firewall is built into

Windows XPWindows XP– More robust firewalls are More robust firewalls are

available from other available from other vendors.vendors.

– Firewalls are critical if you Firewalls are critical if you have an always-on have an always-on broadband connection.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 line.property line.

• Default device and network ID settings Default device and network ID settings allow intruders to enter the network.allow 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 takeover.intrusion and takeover.


Computer Threat - VirusesComputer Threat - 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 VirusCatch a Virus

• Viruses copy Viruses copy themselves themselves

• Infect a file on Infect a file on your computeryour computer

• Viruses spread by Viruses spread by sharing diskssharing disks

• E-mail E-mail attachments are attachments are the most likely 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:– Annoying messagesAnnoying messages– Delete files on the hard driveDelete files on the hard drive– Change computer settingsChange computer settings


Types of VirusesTypes of Viruses

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

drivedrive

• Logic bombs:Logic bombs:– Activate when certain conditions are metActivate when certain conditions are met

• Worms:Worms:– Travel between systems through networksTravel between systems through networks


Types of VirusesTypes of Viruses• Script viruses:Script viruses:

– Hidden on Web pagesHidden on Web pages– Mini programs Mini programs

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

• Encryption virusesEncryption viruses– Search for common data filesSearch for common data files– Compress files using a complex Compress files using a complex

encryption key encryption key – User must pay to get the files User must pay to get the files

unlockedunlocked• Trojan horses:Trojan horses:

– Backdoor programsBackdoor programs– Control remote computersControl remote computers


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)– Provides options for deleting or fixing infected filesProvides options for deleting or fixing infected files– Inoculates files against further infectionInoculates 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 one up?advantages of setting one up?



• 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 power-line networks?What are power-line networks?



• What are phoneline networks?What are phoneline networks?



• What are Ethernet networks?What are Ethernet networks?



• What are wireless networks?What are wireless 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?



• How are home wireless networks How are home wireless networks vulnerable?vulnerable?



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



• 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?

Networking And Security5

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