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Technology in Action

Technology in Action. Chapter 8 Behind the Scenes: Networking and Security. Chapter Topics. Advantages of business networks Client/server vs. peer-to-peer networks Classifications of client/server networks Client/server network components Types of transmission media Network adapters

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Technology in Action

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  1. Technology in Action Chapter 8 Behind the Scenes: Networking and Security

  2. Chapter Topics • Advantages of business networks • Client/server vs. peer-to-peer networks • Classifications of client/server networks • Client/server network components • Types of transmission media • Network adapters • Moving data in a client/server network • Securing networks

  3. Networking Advantages • Networks • Increase productivity • Enable the sharing of hardware resources • Enable the sharing of software • Facilitate communication inside and outside the company

  4. Network Advantages • Sharing networked hardware can reduce costs • Sharing networked hardware can provide access to a wide range of services and specialized peripheral devices • Sharing networked software can reduce costs • Sharing data on a network is easy • Networks enable people to work together regardless of time and place (telecommuting)

  5. Network Challenges • Networks may be vulnerable to unauthorized access from many sources and locations • More vulnerable than standalone computers • Wireless networks can be tapped from a “snooping” computer • Networked computers are susceptible to an increasing number of worms, Trojan horses, and blended threats

  6. Organizational Structure: Client/Server and Peer-to-Peer • Where are the resources? • Centralized – Client/Server • resources in the Server(s) • Distributed – Peer-to-Peer (file sharing) • resources in all the machines

  7. Organizational Structure: Client/Server and Peer-to-Peer 7

  8. Client/Server Networks • Server-based network • Clients and servers • Data flows efficiently • Servers respond to requests from clients • Servers perform specific tasks • Scalable network • Centralized

  9. Classifications of Client/Server Networks • LAN • Local area network • Computers linked together over a small geographic region

  10. Classifications of Client/Server Networks • WAN • Wide area network • Computers linked over large geographic locations • MAN • Metropolitan area network • Computers linked together within a city or county

  11. Classifications of Client/Server Networks • PAN • Personal area network • Wireless devices connected in close proximity to each other • Intranet • Private corporate network using TCP/IP • Protected by a firewall from the Internet outside

  12. Constructing Client/Server Networks • Servers • Transmission media • Network adapters • Network navigation devices

  13. Servers • Number and type of servers depend on network size and workload • Dedicated server • Performs one specific function • Authentication server • Keeps track of network logins and services available • File server • Stores and manages files

  14. Dedicated Servers • Communications server • Handles communications between networks including the Internet • Often the only device on the network directly connected to the Internet • Web server • Hosts a Web site available through the Internet

  15. Dedicated Servers, cont'd • Print server • Manages client-requested printing jobs • Creates print queue (prioritizes print jobs) • Applications server • Acts as a storage area for application software • Database server • Provides clients with access to database information • E-mail server • Processes and delivers incoming and outgoing e-mail

  16. Transmission Media • The routes data takes to flow between devices on a network • Wired • Wireless

  17. Network Links • Wired network • Twisted-pair cable • Coaxial cable • Fiber-optic cable • Wireless network • RF signals • Microwaves • Infrared light

  18. Maximum run length Bandwidth Bend radius Cable cost Installation costs Susceptibility to interference Choosing a Cable

  19. Twisted Pair Cable • Pairs of copper wire twisted around each other • Twists make the wires less susceptible to interference • Shielded twisted pair (STP) • Layer of foil shielding • Unshielded twisted pair (UTP) • Cat 5E: Bandwidth 200 Mbps • Cat 6: Bandwidth 1 Gbps • No foil layer UTP STP

  20. Coaxial Cable • Four components • Copper core • Nonconductive insulating material • Braided metal • Plastic cover

  21. Fiber-Optic Cable • Components include • Glass or plastic fibers • Cladding • Outer jacket • Uses light impulses to transmit data • Immune to interference • Physically smaller • More difficult to install

  22. Network Adapters • Devices that enable computers to communicate on a network • Network interface cards (NICs) • Three functions • Generate network transmission signals • Create data packets • Act as information gatekeepers • Ethernet compliant • Wireless NICs

  23. Wired Ethernet Networks • Protocol created by Xerox PARC in 70’s • Bandwidth from 10/100 Mbps to 1 Gbps • Connection with Unshielded Twisted Pair • Cat 5, Cat 5E, Cat 6 • Network interface card added if not builtin • Switch device works to send data where it goes, avoiding collisions • Routers work between two networks, like your network and the Internet

  24. Wireless Ethernet Networks • Use radio instead of wires • Wi-Fi = 802.11 standard • Need a wireless network adapter for each machine – transmits and receives signals • Radio signals can be blocked by walls, reduced by distance • WAP – wireless access point – will extend the range

  25. Wireless Media802.11 Standard • Wi-Fi, short for Wireless Fidelity • 802.11b – first cost-effective wireless devices. • 802.11a, 802.11g – bandwidth increased to 54 Mbps • Super G – bandwidth to 108 Mbps • 802.11n – will support higher throughput and greatly increased range

  26. Grid computing • Loosely connected networks of machines volunteered to work on research • Donate your unused cycles to research • CPUs are idle a lot, software has been written to make use of those idle machine cycles • Download software that connects you • SETI, medicine, mathematics, astrophysics • Make sure it’s a project that is legitimate

  27. “Cloud computing” • The Internet is “the cloud” • Your data is stored on servers remotely, not on your local hard drive • Applications you run (even Office) are via a web browser • Portable • Cheaper? “software as service” • Like plugging into the wall vs. owning a generator

  28. Network Security Threats • Human Errors and Mistakes • Accidents and mistakes • Malicious Human Activity • Current and former employees hacking or planting viruses • Natural Events and Disasters • Hurricanes, floods, fire

  29. Computer Threats • Hackers and Crackers • Viruses • Trojan Horses • Worms • Bots • Combating Malicious Code "Malware"

  30. Hackers and Crackers • Why do they do it? • To show off their technical expertise • blackmail • espionage • industrial • military • Theft • Global terrorism

  31. Viruses • Viruses are malicious code that enters a computer and disrupts normal operation • Viruses might deliver a payload, which could either be annoying or devastating • Trigger events can unleash some viruses • When you check email • On a certain date/time • When your computer starts up

  32. Viruses • Computer viruses attach themselves to a file, reproduce, and spread to other files and computers • File virus • Boot sector virus • Macro / script virus • Email virus • Main goal is to reproduce itself • Attempts to be unnoticed - stealth mode • Depends on the user to execute a program or open a file to get started

  33. Trojan Horses • Seems to perform one function while doing another • Keyloggers record your keystrokes • Backdoors allow unauthorized access to computers • Wants to be noticed - looks desirable to get itself installed • A funny video or a cool game

  34. Worms • Designed to spread from computer to computer - more active than a virus or Trojan • Will send ITSELF without user knowledge if there is a network connection available • Mass-mailing worms spread to addresses in the address book on the infected computer • Examples include Klez, Netsky, Sasser • Messages sometimes contain a spoofed address

  35. Bots • A bot is software that can automate a task or autonomously execute a task • Bots can be useful – system administrators use them to do repetitive work more quickly than a human could, “spiders” are bots • Bots can be the payload of a virus or Trojan • Botnets are linked bot-infested computers • Bots can be networked to make a botnet • Used for “DOS” attacks

  36. What can they do? • Malicious code can perform the following activities: • Network traffic jam • Denial of Service attacks • Bot nets • Browser reconfiguration • Delete and modify files • Access confidential information • Performance degradation • Disable antivirus and firewall software

  37. Network Security • Authentication • User ID and password used to access the network • Use of a possessed object for access • Access privileges • Enable access to certain network systems • Physical protection measures • Restrict physical access to sensitive network equipment • Magnetic card readers • Biometric access devices

  38. Network Security • Firewalls • Prevent access to the network by unauthorized users • Composed of software and/or hardware • Screen and validate data packets • Software firewalls • Norton, McAfee, ZoneAlarm, BlackICE • Hardware firewalls • Usually built into routers

  39. Network Firewall Layout

  40. Combating Malicious Code • Use antivirus software and firewall software on every computing device you own • keep them up to date • Virus signatures keep changing • McAfee software freely available on download.uky.edu to all UK students • AVG software www.avg.com free for home use • Do not open suspicious e-mail attachments • Regularly download and install the latest security patches available for your OS, e-mail program, andbrowser.

  41. Combating Malicious Code • Limit sharing disks and other removable storage media. • Only download programs from reputable Web sites. • Limit the amount of file-sharing you do • Use anti-virus software to scan all emails and all files received from someone else • Backup your files regularly • Look for unexpected file extensions – like exe on a jpg file • Test your computer with Gibson Research’s free scan

  42. Protecting a Wireless Network • Change your network’s name • Disable the broadcast of its name (SSID) • Change the default password on your router • Turn on WEP (wired equivalent privacy) (weak) or WPA (wi-fi protected access) • Turn on MAC addresses – so only computers whose addresses you enter are allowed on • Keep software up to date

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