1. Lecture 11 Wireless security

2. Wireless Networks Standard
Wireless networks are standardized by IEEE.
Under 802 LAN MAN standards committee.
Application
Presentation
Session
IEEE 802 standards
Transport
Same organization that came up with IEEE Ethernet,
which is responsible for success of Internet
Network
Logical Link Control
Data Link
Medium Access (MAC)
Physical
Physical (PHY)
ISO - OSI

3. DSSS Direct Sequence Signaling (DSSS)
Using one of 11 overlapping 22MHz channels, multiply the data by an 11-bit number to spread the 1M-symbol/sec data over 11MHz. It use the 2.4 GHz band
Requires RF linearity over 11MHz
Spreading yields processing gain at receiver
Less immune to interference

4. IEEE g
Introduced in 2003
Combine the feature of both standards (a,b)
feet range
54 Mbps Speed
2.4 GHz radio frequencies
Compatible with ‘b’

5. Comparison 3G versus WiFi
Standard
WCDMA,CDMA2000
IEEE
Max Speed
2 Mbps
54 Mbps
Operations
Cell phone companies
Individuals, WISP
License
Yes No
Coverage Area
Several km
About 100m
Advantages
Range, mobility
Speed, cheap
Disadvantages
Relatively slow Expensive
Short range

6. Comparison 3G versus WiMax
Wi-Max (Wider-Fi)
Standard
WCDMA,CDMA2000
IEEE
Max Speed
2 Mbps
10 to 100 Mbps
Operations
Cell phone companies
Individuals, WISP
License
Yes
Yes/No
Coverage Area
Several km
Advantages
Range, mobility
Speed, long range
Disadvantages
Relatively slow Expensive
Interference issues?

7. MITM Attack Attacker spoofes a disassociate message from the victim
The victim starts to look for a new access point, and the attacker advertises his own AP on a different channel, using the real AP’s MAC address
The attacker connects to the real AP using victim’s MAC address

8. WEP vs WPA vs WPA2 WEP WPA WPA2 Cript RC4 AES Key rotation None
Dynamic session keys
Key distribution
Manual inert over each device
Automatic distribution is possible
Authentification
Use WEP key
802.1x & EAP supported

9. Authentification (802.1x / EAP)
EAP - Extensible Authentication Protocol
802.1X parte din i
Must certify the user not only the devices
Mutual authentification
802.1x
authentification
Key management
EAP
Model
Addition to the Wi-Fi Protected Access.
Used in internal network.
Extra security for enterprise and government Wi-Fi LANs.
Several versions available.

10. 802.1x

11. 802.1x Access Control
Designed as a general purpose network access control mechanism
Not Wi-Fi specific
Authenticate each client connected to AP (for WLAN) or switch port (for Ethernet)
Authentication is done with the RADIUS server, which ”tells” the access point whether access to controlled ports should be allowed or not
AP forces the user into an unauthorized state
user send an EAP start message
AP return an EAP message requesting the user’s identity
Identity send by user is then forwared to the authentication server by AP
Authentication server authenticate user and return an accept or reject message back to the AP
If accept message is return, the AP changes the client’s state to authorized and normal traffic flows

12. WLAN security methods comparision
Security type
Security level
Install & maintenance
Integration & easiest to use
WEP Static
Low
High
IEEE 802.1X PEAP
Midle
IEEE 802.1x TLS

13. References
Mustafa Ergen, IEEE Overview,
Greg Goldman, Is for “Wireless Fidelity” or IEEE Standard,
tcil-india.com/new/new.../TCIL%2010%20WiFi %20Technology.ppt

14. No wireless is 100% secure!