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?