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Chapter 9

Chapter 9. Wireless network. Wireless Network. In wireless network, data are carried by electrical wave (e.g., radio wave ) from one node to another. There is no physical cable/wire connecting one computer to another. Wired (Cabled) Network versus Wireless Network.

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Chapter 9

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  1. Chapter 9 Wireless network

  2. Wireless Network • In wireless network, data are carried by electrical wave(e.g., radio wave) from one node to another. • There is no physical cable/wireconnecting one computer to another

  3. Wired (Cabled) Network versus Wireless Network • Advantages of Wireless Network over Wired (Cabled) Network • Mobility: Users can roam around the network without being disconnected • Installation speed and cost: Building wireless medium to large network is usually faster and cheaper than building wired (cabled) medium to large network because there is no need to pull cable through walls and ceilings • Reach of network: Wireless network can be extended to places where wire/cable cannot reach • Flexibility/scalability: New computers can be added easily without having to pull cable into the computers • Disadvantages of Wireless Network compared to Wired Network • Speed: In general, wireless network technology is slower than wired network technology • Security: In general, wireless network is less secured than wired network

  4. Basic Components of Wireless Network

  5. Wireless Network Hardware • Wireless NIC (e.g., wireless Ethernet NIC or Bluetooth NIC) must be installed in each computer • Major functions of wireless NIC: • Sender NIC: • Take data from Layer 3 (Network Layer) • Encapsulate the data into frame • Load the frame to electrical wave • Transmit the electrical wave • Receiver NIC performs the reverse activities • Wireless NIC comes in various forms (e.g., expansion board, PCMCIA, USB, built-in)

  6. Wireless Network Hardware • Wireless Access Point (WAP/Access Point/AP/Universal Access Point/UAP) • Central “wiring” device to connect wireless nodes to wireless/wired network • If a network uses WAP, all computers must communicate via the WAP

  7. Wireless Network Mode • Ad-Hoc Mode (Peer-to-Peer Mode) • Each wireless node can communicate directly with each of the other nodes in the network (without Wireless Access Point) • Mesh network topology • IBSS (Independent Basic Service Set): a group of nodes communicating in ad-hoc mode • Infrastructure Mode • All wireless node communicate to one another via Wireless Access Point • Star network topology • BSS (Basic Service Set): a group of nodes communicating in infrastructure mode. • An BSS has one wireless access point • EBSS (Extended Basic Service Set): two or more BSS that can communicate to one another • An EBSS contains two or more wireless access points

  8. Ad-Hoc versus Infrastructure Mode Ad-Hoc Mode (IBSS) InfrastructureMode (BSS)

  9. Infrastructure Mode: BSS versus EBSS BSS EBSS

  10. Wireless Network Security • Three basic wireless network security methods: • SSID(Service Set IDentification) • MACAddress Filtering • Encryption

  11. Wireless Network Security • SSID (Service Set IDentifier) (Network Name): • A 32-alphanumeric character given to a network • Valid SSID: USER, 1234, ThisIsAValidSSID • Invalid SSID: ThisIsAnInvalidSSIDDoYouKnowTheReason • All nodes and the Wireless Access Point must have the same SSID to be able to communicate in infrastructure mode • SSID is defined by usingConfiguration utilitysoftware for the Wireless Access Pointand the NIC

  12. Wireless Network Security • SSID (Service Set IDentifier) (Network Name): • SSID Broadcast/Beaconing: • WAP can be configured to continuously broadcast its SSID. As a result, every wireless device that come within the range of the WAP (hotspot) can connect to the WAP • To improve security, turn off the SSID broadcast/beacon • Problem with SSID: • Even if you turn off the “SSID broadcast/beacon” of the WAP, SSID can be easily “sniffed” (i.e., by using a wireless “packet sniffer” a cracker is able to listen in on network traffic and identify the SSID)

  13. Wireless Network Security • MAC Address Filtering: • To allow (prevent) certain computers to access a wireless network • Wireless Access Point can be configured to: • Allow communication with certain MAC Addresses ONLY • Deny communication with certain MAC Addresses • MAC Address Filtering is set by using Configuration utility software for the Wireless Access Point • Problem with MAC address filtering: • MAC address can be easily “sniffed” (i.e., by using a wireless “packet sniffer” a cracker is able to listen in on network traffic and identify the MAC addresses of computers connected to the network)

  14. Wireless Network Security • Encryption: • Two major encryption technologies for wireless network: • WEP (Wired Equivalent Privacy): older, less safe (a single key for all users and sessions) • WPA (Wireless Protected Access): newer, more safe (different key for different users and sessions) • Encryption technology is defined by using Configuration utility software for the Wireless Access Point and the NIC

  15. Web-based WAP Configuration Utility

  16. Wireless network Security • Configuring a Wireless NIC: • http://www.usr.com/support/5450/54xx-ug/four.html • Wi-Fi Protected Setup (WPS) • A standard for easy and secure establishment of a wireless home network, created by the Wi-Fi Alliance and officially launched on January 8, 2007. • The goal of the WPS protocol is to simplify the process of configuring security on wireless networks, and so it was first named ‘Wi-Fi Simple Config’. • http://kb.netgear.com/app/answers/detail/a_id/96 • http://www.youtube.com/watch?v=XDxHXu5jxWQ

  17. Wireless network Speed • Wireless network speeddepends on: • The wireless network technology standard • The distancebetween sender and receiver, or between a node and a Wireless Access Point • Interferencefrom other wireless devices or electronic devices (e.g., wireless phone) • The presence of solid object(especially metal object, electronic appliance) between the sender and receiver, or between a node and a Wireless Access Point

  18. Wireless Network Range (i.e., maximum distance between sender and receiver, or a node and a Wireless Access Point ) • Wireless network rangedepends on: • The wireless network technology standard • Interferencefrom other wireless devices or electronic devices • The presence of solid object(especially metal object, electronic appliance) between the sender and receiver, or between a node and a Wireless Access Point • To increase the wireless network range: • Using “signal booster” • Using Wireless Access Point (i.e., instead of using ad-hoc mode, use infrastructure mode) • Using MULTIPLEWireless Access Points (What is Power over Ethernet (PoE)?)

  19. Extending Wireless Network BSS EBSS

  20. Wireless Network Access Method (CSMA/CA) • CSMA/CA (Carrier Sense Media Access with Collision Avoidance): • Using a stricter network access method to avoid collision (minimize the probability of collision as much as possible)

  21. Wireless Network Standards • Two major wireless network technology standards: • IEEE 802.11 • Wireless Fidelity (Wi-Fi) • IEEE 802.15 • Bluetooth

  22. Wireless Network Standards • IEEE 802.11 • Wi-Fi • Most popular • All Wi-Fi standards (802.11, a, b, g) have the following features: • Communication mode: supporting Ad-hoc and Infrastructure • SSID • Supporting WEP and/or WPA

  23. Wireless Network Standards • Wi-Fi: • Includes: • 802.11 • The oldest • Maximum throughput: 2 Mbps • More interference from other electronic devices (Why? 2.4 GHz frequency range is used by a lot of other electronic devices) • Maximum distance between sender and receiver (node and WAP): 150 feet • 802.11 b • Maximum throughput: 11 Mbps • More interference from other electronic devices (Why? 2.4 GHz frequency range is used by a lot of other electronic devices) • Maximum distance between sender and receiver (node and WAP): 300 feet

  24. Wireless Network Standards • Wi-Fi: • 802.11 a • Developed after (newer than) 802.11 b • Maximum throughput: 54 Mbps • Less interference from other electronic devices (Why? 5 GHz frequency range is NOT used by many electronic devices) • Problem: NOT compatible with the “popular” 802.11 b • Maximum distance between sender and receiver (node and WAP): 150 feet • 802.11 g • Maximum throughput: 54 Mbps • More interference from other electronic devices (Why? 2.4 GHz frequency range is used by a lot of other electronic devices) • Maximum distance between sender and receiver (node and WAP): 300 feet

  25. Wireless Network Standards: Bluetooth • Bluetooth: • Major application: short-range network (e.g., connecting a PDA device to a computer)/small network (PAN: Personal Area Network = Pico/Piconet) • Maximum throughput: 4 Mbps • Maximum distance between sender and receiver: 33 feet (10 meters) • Supporting proprietary 128-bit encryption algorithm • 2.4 GHz

  26. Assignment 3Due on Monday, October 5, 2009 • Problem 1: Search the WWW about: • 802.11 N • What frequency does this technology use? • What is its maximum data transmission speed? • What is its maximum range? • Wi-Max • Which IEEE sub-committee is responsible in the development and promotion of this technology? • What are the major differences between this technology and the Wi-Fi? • What type of network usually uses this technology? LAN, MAN, or WAN • Passphrase • WPA uses passphrase. What is passphrase in the context of wireless network security? What is the function of passphrase in the context of wireless network security?

  27. Assignment 3Due on Monday, October 5, 2009 • Problem 2: Watch these two videos and submit a report: • Video 1: http://www.youtube.com/watch?v=yBP9ZOpRLWM • Video 2: http://www.youtube.com/watch?v=9UFh0W_Z3kI&feature=PlayList&p=045B8541438D01D0&playnext=1&index=3 • Based on the information provided in those two videos: • What are the basic steps to create a wireless network? • What are the basic configurations that must be done to connect a computer to a wireless network? • Identify all of the wireless router features that should be used to make your wireless network more secure, and write a tutorial that specifies all of the steps to set up each of the feature that you mentioned above

  28. Assignment 3Due on Monday, October 5, 2009 • How to submit the assignment? • All answers must be typed • Submit the print out in the beginning of the class on Monday, October 5, 2009

  29. How to connect to multiple wireless networks? • http://technofriends.in/2009/01/07/how-to-simultaneously-connect-to-multiple-wireless-networks-with-one-wlan-card/

  30. How to connect to a private network and a public network (the Internet) at the same time? • Set the security zones for each network adapter. • The local intranet should be set to Private, and the connection to the internet should be set to public. • This link will explain the difference and how to check.http://technet.microsoft.com/en-us/library/bb878110.asp • Also make sure that only the wireless internet connection has a default gateway set and the private wired does not. • This could cause you to send packages to the internet to the wrong gateway. • If you have any networks asides the one attached to the local network you will need to use routing statements.

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