Wireless Networks: Signaling and Security William Tucker CEN 4516: Computer Networks FGCU: Fort...
-
Upload
june-richard -
Category
Documents
-
view
215 -
download
0
Transcript of Wireless Networks: Signaling and Security William Tucker CEN 4516: Computer Networks FGCU: Fort...
Wireless Networks: Signaling and Security
William TuckerCEN 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
Several Wireless Technologies Bluetooth IrDA 802.11 Standard
802.11a 802.11b 802.11g 802.11n
Wireless Networks: Primer
Wireless Technologies (cont.) PCS WAP WTLS WML Wi-Fi HomeRF Most of the above are not as popular
Bluetooth
Low Cost
Small Range (<10 M)
Mediocre Speed (700 Kbps)
IrDA
Used in Inventory
Needs Clear LOS
Needs short Distance
Used Mostly in Desktop Cable Replacement
The 802.11 Standard
802.11a Fastest Maximum Speed (54 Mbps) Supports More Simultaneous Users Higher Cost Shorter Range
The 802.11 Standard
802.11b Slowest Maximum Speed (11 Mbps) Longer range (Less Obstruction) More Signal Noise (2.4 GHz)
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
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
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
Problem Definition:
Wireless Networking: Physical Limitations Security
Methods of Improvement Signal Strengthening Security Protocols
The Electromagnetic Spectrum
Wireless Networks Operate at 2.4 GHz
(2.4 x 10^6)
Low Traffic and Standardized
Physical Propagation
Radio Waves are sent via a transmitter and a receiver
Data rate dependant on frequency
Signal Strength is based on Power (Watts)
Signal Strength
Signal power is amplitude of wave
Attenuation occurs (Humidity)Amplifiers boost signal strength
Weakening and Strengthening given in Decibels
Example of Signal
Taken Using 802.11g at Close Range
Antennas
Responsible for converting electrical impulses into radio waves
Omni directional AntennasDirectional Antennas
Physical Layer Security
Has not been a major problem for wired networks
Wireless is highly susceptible to physical sniffing
No security by default
Wired Equivalent Privacy
Uses encrypted keys
Key Length (64, 128 bit)
Initialization Vectors (24 bits) 16.7 Million Possibilities (Low)
Initialization Vectors
No check for duplication
Weakens the cryptographic system
Weak Keys are used
Cracking WEP: How To
Wireless Card capable of being ‘passive’ (sniffing)
Packet/IV collection software
Modified Brute Force WEP Cracking Software
Cracking WEP: Using Aircrack
Aircrack includes Airodump
Aircrack includes Aircrack
Aircrack can be run on Windows!(using CygWin1.dll)
Aircrack Sniffing Example
15 min of collection on Medium Traffic 128 bit WEP 802.11g
Aircrack Cracking Example
500k IV’s found from packets
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!
Questions?