1. CSE 5/7349 – April 5 th 2006 Wireless Networking

2. Compression

3. FEC

4. CRC

5. Modulation

6. Bits / Symbols / Baud

7. DSSS / FHSS

8. Wireless Security History Cordless Phones Baby Monitors Networking

9. 802.11 Components

10. 802.11 modes Infrastructure mode Ad-hoc mode (peer-to-peer)

11. Infrastructure mode Basic Service Set (BSS) – Single cell Extended Service Set (ESS) – Multiple cells Access Point Station

12. Ad-hoc mode Independent Basic Service Set (IBSS)

13. Open System Authentication

14. MAC Address Locking

15. Interception Range Basic Service Set (BSS) – Single cell Station outside building perimeter. 100 metres

16. Interception

17. Directional Antenna Directional antenna provides focused reception. D-I-Y plans available. –Aluminium cake tin. –11 Mbps at 750 meters. –http://www.saunalahti.fi/~elepal/antennie.html

18. 802.11b Security Services

19. Wired Equivalence Privacy

20. WEP – Sending

21. Initialization Vector

22. WEP – Receiving

23. Shared Key Authentication When station requests association with Access Point –AP sends random number to station –Station encrypts random number Uses RC4, 40 bit shared secret key & 24 bit IV –Encrypted random number sent to AP –AP decrypts received message Uses RC4, 40 bit shared secret key & 24 bit IV –AP compares decrypted random number to transmitted random number

24. Security - Summary Shared secret key required for: Messages are encrypted. Messages have checksum. But SSID still broadcast in clear.

25. Security Attacks

26. 802.11 Insecurities

27. IV Collision attack

28. Limited WEP keys

29. Brute Force Key Attack

30. 128 bit WEP

31. IV weakness

32. Wepcrack

33. Airsnort

34. Safeguards

35. Wireless as Untrusted LAN Treat wireless as untrusted. –Similar to Internet. Firewall between WLAN and Backbone. Extra authentication required. Intrusion Detection –WLAN / Backbone junction. Vulnerability assessments

36. Discover Unauthorised Use Search for unauthorised access points or ad-hoc networks

37. Location of AP

38. IPSec VPN

39. IEEE 802.11i

40. 802.11i – Encryption Enhancements