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© 2009 Prentice-Hall, Inc. 1 Technology in Action Chapter 7 Networking and Security: Connecting Computers and Keeping Them Safe from Hackers and Viruses © 2009 Prentice-Hall, Inc. 2 Chapter Topics • • • • • • • • Networking fundamentals Network architecture Network components Peer-to-peer networks Ethernet networks Computer threats Computer safeguards Computer viruses © 2009 Prentice-Hall, Inc. 3 Networking Fundamentals • Computer network: – Two or more computers connected together – Devices connected to networks: nodes • Benefits of a network: – Sharing resources – Transferring files © 2009 Prentice-Hall, Inc. 4 Network Architecture • Network designs: – Locally administered: • Peer-to-peer (P2P) – Centrally administered: • Client/server © 2009 Prentice-Hall, Inc. 5 Peer-to-Peer Networks • Nodes communicate with each other: – Peers • Share peripheral devices • Used in home and small office networks © 2009 Prentice-Hall, Inc. 6 Client/Server Networks • Client computers: – Users who make requests • Server computers: – Provide resources to clients – Central network control • Internet – A large, multiserver, multiclient network. © 2009 Prentice-Hall, Inc. 7 LANs and WANs • Local area network (LAN): – Nodes are within a small geographic region: • Homes • Schools • Small businesses • Wide area network (WAN): – LANs connected over long distances: • A few miles to thousands of miles • Use telecommunications lines © 2009 Prentice-Hall, Inc. 8 Network Components • Transmission media • Network communication devices • Software © 2009 Prentice-Hall, Inc. 9 Transmission Media • Provides communications channel between nodes • Forms of media: – – – – Twisted pair Coaxial cable Fiber-optic cable Radio waves: • Wireless • Bandwidth: – Data transfer rate – Throughput © 2009 Prentice-Hall, Inc. 10 Network Adapters • Devices connected to or installed in nodes: – Network interface cards (NICs) – External network adapters • Enable communication between nodes © 2009 Prentice-Hall, Inc. 11 Network Navigation Devices • Devices that help make data flow possible • Routers: – Route data between networks • Switches: – Receive data and retransmit it to nodes on the same network © 2009 Prentice-Hall, Inc. 12 Networking Software • Peer-to-Peer Software • Built into operating systems that support networking – Windows – Mac OS • Client/Server Software • Network operating system (NOS) software – – – – Windows XP Professional Windows Server 2003 Novell Netware Windows Vista Enterprise © 2009 Prentice-Hall, Inc. 13 Types of Peer-to-Peer Networks • Wired Ethernet networks • Wireless Ethernet networks • Power-line networks © 2009 Prentice-Hall, Inc. 14 Wired Ethernet Networks • Ethernet network adapters are used to connect nodes – NIC card – PC Card – USB adapter • Computers are connected to each other using unshielded twisted pair cable © 2009 Prentice-Hall, Inc. Ethernet Phone 15 Ethernet Switches • Keep track of data packets • Amplify and retransmit signals • Keep the network running efficiently © 2009 Prentice-Hall, Inc. 16 Ethernet Routers • Transfer packets from one network to another • Home Internet routers transfer data from the Internet to the home network. Router © 2009 Prentice-Hall, Inc. 17 Wireless Ethernet Networks • Uses radio waves to connect nodes • Basically an Ethernet network that uses radio waves instead of wires • Each node requires a wireless network adapter: – Transceivers © 2009 Prentice-Hall, Inc. 18 Power-Line Networks • Computers are connected to a house’s electrical wiring to create a network • Power-line network adapter is used to connect nodes to electrical outlets © 2009 Prentice-Hall, Inc. 19 Choosing a Peer-to-Peer Network • Things to consider: - Whether you want wireless communications How fast you want your network connection to be Whether 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 Wireless 802.11n Maximum data Transfer rate (bandwidth) 100 Mbps to 1,000 bps (1 gigabit) 54 Mbps 108 Mbps 100 to 630 bps Relative installation and equipment costs for networking two computers $ $ $$ $$$ © 2009 Prentice-Hall, Inc. 20 Configuring Software for a Home Network • Windows – Windows Vista home versions • Network setup wizard – Wired or wireless – Windows XP • Network setup wizard – Windows 98 • Configure manually – Help has a clear instruction © 2009 Prentice-Hall, Inc. 21 Computer Threats • Cybercrimes are criminal acts conducted through the use of computers by cybercriminals. © 2009 Prentice-Hall, Inc. 22 Hackers • Anyone who unlawfully accesses a computer system • Types of hackers: – White-hat – Black-hat – Script kiddies © 2009 Prentice-Hall, Inc. 23 What Hackers Do • Steal information from computers: – Credit card numbers – Bank account numbers • Internet packet sniffing • Commit identity theft © 2009 Prentice-Hall, Inc. 24 How Computers Are Attacked • Trojan horse • Backdoor program – Zombies • Denial of service attacks © 2009 Prentice-Hall, Inc. 25 How Hackers Gain Access • Direct access: – Hacking software • Indirect access: – Internet connection – Logical ports © 2009 Prentice-Hall, Inc. 26 Computer Safeguards: Firewalls • Software programs or hardware designed to close logical ports to invaders – A firewall is built into Windows Vista – More robust firewalls are available from other vendors – Firewalls are critical if you have an alwayson broadband connection © 2009 Prentice-Hall, Inc. 27 Protecting a Wireless Network • Wireless network range doesn’t stop at the property line • Default device and network ID settings allow intruders to enter the network • Internet bandwidth can be stolen • Computers can be vulnerable to hacker intrusion and takeover © 2009 Prentice-Hall, Inc. 28 Computer Threats: Viruses • A program that attaches itself to another program and spreads itself to other computers • Viruses are hidden within the code of a host program © 2009 Prentice-Hall, Inc. 29 How Does a Computer Catch a Virus? • Viruses copy themselves • Infect a file on your computer • Spread by sharing disks or flash drives • E-mail attachments are the most likely source of a virus © 2009 Prentice-Hall, Inc. 30 What Viruses Do • Replicate themselves: – Slow down networks • Secondary objectives: – Display annoying messages – Delete files on the hard drive – Change computer settings © 2009 Prentice-Hall, Inc. 31 Types of Viruses • Boot-sector viruses – Replicate themselves in the boot sector of the hard drive • Logic bombs – Activate when certain conditions are met • Time bombs – Viruses that are triggered by the passage of time or on a certain date • Worms – Travel between systems through networks © 2009 Prentice-Hall, Inc. 32 Types of Viruses • Script viruses: – Hidden on Web pages as mini programs • Macro viruses: – Attached to documents – Series of commands • E-mail virus – Use e-mail address book to distribute the virus • Encryption viruses – Compresses files using a complex encryption key – User must pay to get the files unlocked © 2009 Prentice-Hall, Inc. 33 Virus 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 © 2009 Prentice-Hall, Inc. 34 Antivirus Software • Programs designed to detect viruses: – Scan files looking for virus signatures (unique code) – Provide options for deleting or fixing infected files – Inoculate files against further infection • Detect known viruses • Antivirus programs need to be updated frequently © 2009 Prentice-Hall, Inc. 35 Chapter 7 Summary Questions • What is a network, and what are the advantages of setting up one? © 2009 Prentice-Hall, Inc. 36 Chapter 7 Summary Questions • What is the difference between a client/server network and a peer-to-peer network? © 2009 Prentice-Hall, Inc. 37 Chapter 7 Summary Questions • What are the main components of every network? © 2009 Prentice-Hall, Inc. 38 Chapter 7 Summary Questions • What are the most common home networks? © 2009 Prentice-Hall, Inc. 39 Chapter 7 Summary Questions • What are wired Ethernet networks, and how are they created? © 2009 Prentice-Hall, Inc. 40 Chapter 7 Summary Questions • What are wireless Ethernet networks, and how are they created? © 2009 Prentice-Hall, Inc. 41 Chapter 7 Summary Questions • How are power-line networks created, and are they viable alternatives to Ethernet networks? © 2009 Prentice-Hall, Inc. 42 Chapter 7 Summary Questions • How can hackers attack a network, and what harm can they cause? © 2009 Prentice-Hall, Inc. 43 Chapter 7 Summary Questions • What is a firewall, and how does it keep my computer safe from hackers? © 2009 Prentice-Hall, Inc. 44 Chapter 7 Summary Questions • Why are wireless networks more vulnerable than wired networks, and what special precautions are required to ensure my wireless network is secure? © 2009 Prentice-Hall, Inc. 45 Chapter 7 Summary Questions • From which types of viruses do I need to protect my computer? © 2009 Prentice-Hall, Inc. 46 Chapter 7 Summary Questions • What can I do to protect my computer from viruses? © 2009 Prentice-Hall, Inc. 47