Wireless Networks By Roddy Knight, Chris Zeiders, and Sanjay Ginde
Survey of Wireless Networks <ul><li>Public Access Networks </li></ul><ul><ul><li>User groups </li></ul></ul><ul><ul><li>Co...
Importance of Wi-Fi <ul><li>Ubiquitous internet </li></ul><ul><ul><li>Mobile users benefit </li></ul></ul><ul><ul><li>No s...
Rapid Growth <ul><li>Quarterly shipments of Wi-Fi equipment doubled from last year </li></ul><ul><li>Dell ships all new la...
Networks (public/private) <ul><li>User groups provide non-commercial wireless access </li></ul><ul><li>Telecom companies p...
User Groups <ul><li>Loose assortment of broadband customers with publicly accessible hotspots </li></ul><ul><li>Publish st...
Municipal Initiatives <ul><li>Wireless networks are funded by municipalities to attract high-tech entrepreneurs  </li></ul...
University Networks <ul><li>Duke has 45 hotspots across campus and plans to eliminate current authentication hassle </li><...
ISP Resistance <ul><li>Time Warner Cable has mailed threatening notices to customers ordering them to terminate public wir...
Cellular Carrier Dilemma <ul><li>Carriers have spent $6 billion upgrading networks for high-speed internet access </li></u...
National Wi-Fi Network <ul><li>Cometa plans coverage for top 50 metropolitan cities with 20,000 hotspots </li></ul><ul><li...
Wireless Protocols <ul><li>Competing Standards </li></ul><ul><ul><li>802.11, 802.15, 802.16, HomeRF, Bluetooth </li></ul><...
802.11 Protocol <ul><li>Physical and Data-Link Layer of OSI Network </li></ul>
Transmitting Data <ul><li>Infrared </li></ul><ul><li>Radio Waves – A double-edged sword </li></ul><ul><li>Spread Spectrum ...
Unique Wireless Problems <ul><li>Hidden Nodes Problem </li></ul><ul><li>Exposed Nodes Problem </li></ul>Undetected Collisi...
802.11 Solution <ul><li>Virtual Collision Detection (VCD) </li></ul>CTS not sent to D, so waits to transmit D Hears RTS, b...
Access Points <ul><li>Necessary for widespread public wireless networks </li></ul><ul><li>APs connected to a Distributed S...
Packet Routing <ul><li>Wireless user has no “stable” network it is associated with </li></ul><ul><li>Packet routing using ...
Mobile IP <ul><li>Two addresses: Home address and “care-of” address </li></ul><ul><li>Each user has a static home address ...
Security Goals <ul><li>Privacy </li></ul><ul><ul><li>Open connection </li></ul></ul><ul><li>Authentication </li></ul><ul><...
Why Is Privacy Important? <ul><li>Use by business men and woman </li></ul><ul><li>Need at least the same level that an a d...
Wired Equivalent Privacy C = P    RC4( v , k )   Graphic from:  Gast, Matthew S.  802.11 Wireless Networks .
More WEP Graphic from:  Gast, Matthew S.  802.11 Wireless Networks .
Problems with WEP <ul><li>Manual key management </li></ul><ul><ul><li>Automation needed with unknown users </li></ul></ul>...
WEP Keystream Reuse <ul><li>Difficult key management = rare rekeying </li></ul><ul><li>Cipher Analysis </li></ul><ul><li>I...
Is Authentication Important? <ul><li>ALS Scan Inc. v. RemarQ Communities Inc. </li></ul><ul><ul><li>ISP potentially liable...
Authentication <ul><li>802.11b uses MAC addresses </li></ul><ul><ul><li>Inflexible </li></ul></ul><ul><li>Extensible Authe...
Virtual Private Networking <ul><li>Standard for remote access security </li></ul><ul><li>More secure privacy </li></ul><ul...
Summary <ul><li>We covered Wi-Fi networks from social standpoint </li></ul><ul><ul><li>Commercial and free deployments </l...
Future Research <ul><li>Analyze the 9 task groups in IEEE 802.11 working group </li></ul><ul><li>Compare WLANs to competin...
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  1. 1. Wireless Networks By Roddy Knight, Chris Zeiders, and Sanjay Ginde
  2. 2. Survey of Wireless Networks <ul><li>Public Access Networks </li></ul><ul><ul><li>User groups </li></ul></ul><ul><ul><li>Commercial services </li></ul></ul><ul><ul><li>Universities </li></ul></ul><ul><li>Technical aspects of Wi-Fi networks </li></ul><ul><li>802.11 standard </li></ul><ul><li>Privacy and authentication in Wi-Fi </li></ul>
  3. 3. Importance of Wi-Fi <ul><li>Ubiquitous internet </li></ul><ul><ul><li>Mobile users benefit </li></ul></ul><ul><ul><li>No strings attached </li></ul></ul><ul><li>Architectural Advantages </li></ul><ul><ul><li>Transfer speeds up to 11 Mbps </li></ul></ul><ul><ul><ul><li>Rich media possible </li></ul></ul></ul><ul><ul><li>Hardware encryption </li></ul></ul>
  4. 4. Rapid Growth <ul><li>Quarterly shipments of Wi-Fi equipment doubled from last year </li></ul><ul><li>Dell ships all new laptops with Wi-Fi cards </li></ul><ul><li>Intel plans to embed Wi-Fi functionality in new processor dubbed Banias </li></ul>
  5. 5. Networks (public/private) <ul><li>User groups provide non-commercial wireless access </li></ul><ul><li>Telecom companies provide commercial networks in hotels and cafes </li></ul><ul><li>Commercial networks offer more reliability and coverage for a price </li></ul>
  6. 6. User Groups <ul><li>Loose assortment of broadband customers with publicly accessible hotspots </li></ul><ul><li>Publish status of available hotspots on web </li></ul><ul><li>Provide online forum for debate of public access issues </li></ul><ul><li>Survivors of 9/11 utilized NYC wireless nodes to spread word about relief efforts at ground zero </li></ul>
  7. 7. Municipal Initiatives <ul><li>Wireless networks are funded by municipalities to attract high-tech entrepreneurs </li></ul><ul><li>Pittsburgh Public Wireless Internet Project plans network to cover 4-square-mile area of downtown Pittsburgh </li></ul><ul><li>Jackonsonville, FL hopes free wireless networks in shopping malls will increase pedestrian traffic and revitalize economically depressed areas </li></ul>
  8. 8. University Networks <ul><li>Duke has 45 hotspots across campus and plans to eliminate current authentication hassle </li></ul><ul><li>Dartmouth has 500 hotspots that cover 200 acres of campus </li></ul><ul><li>UNC incorporates Wi-Fi into course work </li></ul><ul><ul><li>Students share drafts in English class </li></ul></ul>
  9. 9. ISP Resistance <ul><li>Time Warner Cable has mailed threatening notices to customers ordering them to terminate public wireless access for personal liability reasons </li></ul><ul><li>Most cable modem customers share common upstream pipe unlike DSL users </li></ul><ul><li>DSL providers sell equipment directly to customers because they perceive Wi-Fi as opportunity </li></ul>
  10. 10. Cellular Carrier Dilemma <ul><li>Carriers have spent $6 billion upgrading networks for high-speed internet access </li></ul><ul><li>Wi-Fi networks require a fraction of the infrastructure cost and offer greater bandwidth </li></ul><ul><li>Carriers scrambling to join commercial Wi-Fi market by placing nodes at airports, hotels, Starbucks </li></ul><ul><li>T-Mobile charges $30/month or $2.99/minute </li></ul>
  11. 11. National Wi-Fi Network <ul><li>Cometa plans coverage for top 50 metropolitan cities with 20,000 hotspots </li></ul><ul><li>Company resells service through ISPs </li></ul><ul><li>Service priced around $50/month </li></ul><ul><li>Backed by IBM, AT&T, and Intel </li></ul><ul><li>Nodes installed in hotels, coffee shops, and public venues </li></ul>
  12. 12. Wireless Protocols <ul><li>Competing Standards </li></ul><ul><ul><li>802.11, 802.15, 802.16, HomeRF, Bluetooth </li></ul></ul><ul><li>802.11 Standard </li></ul><ul><ul><li>Wireless equivalent to Ethernet </li></ul></ul><ul><ul><li>Known as “Wi-Fi” </li></ul></ul><ul><ul><li>First WLAN specification adopted by commercial vendors </li></ul></ul>
  13. 13. 802.11 Protocol <ul><li>Physical and Data-Link Layer of OSI Network </li></ul>
  14. 14. Transmitting Data <ul><li>Infrared </li></ul><ul><li>Radio Waves – A double-edged sword </li></ul><ul><li>Spread Spectrum Technology </li></ul><ul><ul><li>FHSS </li></ul></ul><ul><ul><li>DSSS </li></ul></ul>
  15. 15. Unique Wireless Problems <ul><li>Hidden Nodes Problem </li></ul><ul><li>Exposed Nodes Problem </li></ul>Undetected Collision Unnecessarily blocked to transmit
  16. 16. 802.11 Solution <ul><li>Virtual Collision Detection (VCD) </li></ul>CTS not sent to D, so waits to transmit D Hears RTS, but not CTS, so free to transmit RTS CTS ?
  17. 17. Access Points <ul><li>Necessary for widespread public wireless networks </li></ul><ul><li>APs connected to a Distributed System </li></ul><ul><li>802.11 does not define how the Distributed System works </li></ul><ul><li>802.11 does specify “scanning” and “roaming” </li></ul>
  18. 18. Packet Routing <ul><li>Wireless user has no “stable” network it is associated with </li></ul><ul><li>Packet routing using IP is impossible </li></ul>
  19. 19. Mobile IP <ul><li>Two addresses: Home address and “care-of” address </li></ul><ul><li>Each user has a static home address with a “home agent” </li></ul><ul><li>User sends a “care-of” address to home agent when it connects to a foreign network </li></ul><ul><li>Packets sent to home address via TCP, home agent re-routes data to care-of address </li></ul>
  20. 20. Security Goals <ul><li>Privacy </li></ul><ul><ul><li>Open connection </li></ul></ul><ul><li>Authentication </li></ul><ul><ul><li>Authorization </li></ul></ul>
  21. 21. Why Is Privacy Important? <ul><li>Use by business men and woman </li></ul><ul><li>Need at least the same level that an a direct cabled connection would provide </li></ul><ul><li>Wired Equivalent Privacy (WEP) standard for 802.11b </li></ul>
  22. 22. Wired Equivalent Privacy C = P  RC4( v , k ) Graphic from: Gast, Matthew S. 802.11 Wireless Networks .
  23. 23. More WEP Graphic from: Gast, Matthew S. 802.11 Wireless Networks .
  24. 24. Problems with WEP <ul><li>Manual key management </li></ul><ul><ul><li>Automation needed with unknown users </li></ul></ul><ul><li>Wireless roaming </li></ul><ul><ul><li>Need to manually enter keys at new AP </li></ul></ul><ul><li>Only protects outside attacks </li></ul><ul><ul><li>Unknown users at AP </li></ul></ul>
  25. 25. WEP Keystream Reuse <ul><li>Difficult key management = rare rekeying </li></ul><ul><li>Cipher Analysis </li></ul><ul><li>If C 1 = P 1  RC4( v , k ) and C 2 = P 2  RC4( v , k ) </li></ul><ul><li>then C 1  C 2 = (P 1  RC4( v , k ))  (P 2  RC4( v , k )) </li></ul><ul><li> = P 1  P 2 </li></ul><ul><li>Collisions </li></ul><ul><ul><li>Relatively small IV space </li></ul></ul>Graphic from: Gast, Matthew S. 802.11 Wireless Networks .
  26. 26. Is Authentication Important? <ul><li>ALS Scan Inc. v. RemarQ Communities Inc. </li></ul><ul><ul><li>ISP potentially liable for illegal activity </li></ul></ul><ul><li>Wi-Fi and Terrorism </li></ul>
  27. 27. Authentication <ul><li>802.11b uses MAC addresses </li></ul><ul><ul><li>Inflexible </li></ul></ul><ul><li>Extensible Authentication Protocol (EAP) </li></ul><ul><ul><li>Supports different authentication methods </li></ul></ul><ul><ul><li>Free public wireless providers </li></ul></ul><ul><ul><li>Wireless roaming </li></ul></ul>
  28. 28. Virtual Private Networking <ul><li>Standard for remote access security </li></ul><ul><li>More secure privacy </li></ul><ul><li>Supports different authentication methods </li></ul><ul><li>Average user set off by technicality </li></ul><ul><ul><li>BOINGO software </li></ul></ul><ul><ul><li>Need for authentication servers </li></ul></ul>
  29. 29. Summary <ul><li>We covered Wi-Fi networks from social standpoint </li></ul><ul><ul><li>Commercial and free deployments </li></ul></ul><ul><li>Surveyed key issues involved in implementation of wireless network </li></ul><ul><li>802.11 addresses issues </li></ul><ul><li>Unique security issues related to wireless networks </li></ul>
  30. 30. Future Research <ul><li>Analyze the 9 task groups in IEEE 802.11 working group </li></ul><ul><li>Compare WLANs to competing wireless protocols for broadband access such as 3G </li></ul>

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