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Wireless Networks: Signaling and Security

Wireless Networks: Signaling and Security. William Tucker CEN 4516: Computer Networks FGCU: Fort Myers, FL: 09/05. Wireless Networks: Primer. Networks are set up AD Hoc Or a Hardware/ Software Access Point is Used to Connect Devices. Wireless Networks: Primer.

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Wireless Networks: Signaling and Security

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  1. Wireless Networks: Signaling and Security William Tucker CEN 4516: Computer Networks FGCU: Fort Myers, FL: 09/05

  2. Wireless Networks: Primer • Networks are set up AD Hoc • Or a Hardware/ Software Access Point is Used to Connect Devices

  3. Wireless Networks: Primer • Several Wireless Technologies • Bluetooth • IrDA • 802.11 Standard • 802.11a • 802.11b • 802.11g • 802.11n

  4. Wireless Networks: Primer • Wireless Technologies (cont.) • PCS • WAP • WTLS • WML • Wi-Fi • HomeRF • Most of the above are not as popular

  5. Bluetooth • Low Cost • Small Range (<10 M) • Mediocre Speed (700 Kbps)

  6. IrDA • Used in Inventory • Needs Clear LOS • Needs short Distance • Used Mostly in Desktop Cable Replacement

  7. The 802.11 Standard • 802.11a • Fastest Maximum Speed (54 Mbps) • Supports More Simultaneous Users • Higher Cost • Shorter Range

  8. The 802.11 Standard • 802.11b • Slowest Maximum Speed (11 Mbps) • Longer range (Less Obstruction) • More Signal Noise (2.4 GHz)

  9. The 802.11 Standard • 802.11g • Fastest Maximum Speed (54 Mbps) • Longer range (Less Obstruction) • Backwards Compatible with 802.11b • Combines best of 802.11a and b

  10. The 802.11 Standard • 802.11n • Utilizes Multiple Wireless Antennas • Coordinates Multiple Signals • Fastest Speeds (100-200+ Mbps) • No Word on Compatibility (Drafts) • Expected in 2006

  11. 802.11 Specifics • Protocols operate on the physical layer • 802.11 MAC addressing is done at the Data Link layer • Authentication is done by ‘handshake’ structure

  12. Problem Definition: • Wireless Networking: • Physical Limitations • Security • Methods of Improvement • Signal Strengthening • Security Protocols

  13. The Electromagnetic Spectrum • Wireless Networks Operate at 2.4 GHz (2.4 x 10^6) • Low Traffic and Standardized

  14. Physical Propagation • Radio Waves are sent via a transmitter and a receiver • Data rate dependant on frequency • Signal Strength is based on Power (Watts)

  15. Signal Strength • Signal power is amplitude of wave • Attenuation occurs (Humidity) • Amplifiers boost signal strength • Weakening and Strengthening given in Decibels

  16. Example of Signal • Taken Using 802.11g at Close Range

  17. Antennas • Responsible for converting electrical impulses into radio waves • Omni directional Antennas • Directional Antennas

  18. Physical Layer Security • Has not been a major problem for wired networks • Wireless is highly susceptible to physical sniffing • No security by default

  19. Wired Equivalent Privacy • Uses encrypted keys • Key Length (64, 128 bit) • Initialization Vectors (24 bits) • 16.7 Million Possibilities (Low)

  20. Initialization Vectors • No check for duplication • Weakens the cryptographic system • Weak Keys are used

  21. Cracking WEP: How To • Wireless Card capable of being ‘passive’ (sniffing) • Packet/IV collection software • Modified Brute Force WEP Cracking Software

  22. Cracking WEP: Using Aircrack • Aircrack includes Airodump • Aircrack includes Aircrack • Aircrack can be run on Windows! (using CygWin1.dll)

  23. Aircrack Sniffing Example • 15 min of collection on Medium Traffic 128 bit WEP 802.11g

  24. Aircrack Cracking Example • 500k IV’s found from packets

  25. Conclusion • If using WEP, use 128 bit keys • Use MAC Address Filtering • Don’t Broadcast Your SSID • Download Useful Programs • and Most of all… Enable Some Security!

  26. Questions?

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