Lecture 11Wireless security

Wireless Networks Standard

• Wireless networks are standardized by IEEE.• Under 802 LAN MAN standards committee.

Application

Presentation

Session

Transport

Network

Data Link

Physical

ISO - OSI

Logical Link Control

Medium Access (MAC)

Physical (PHY)

IEEE 802 standards

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

IEEE 802.11g

• Introduced in 2003

• Combine the feature of both standards (a,b)

• 100-150 feet range

• 54 Mbps Speed

• 2.4 GHz radio frequencies

• Compatible with ‘b’

3G WiFi

Standard WCDMA,CDMA2000 IEEE 802.11

Max Speed 2 Mbps 54 MbpsOperations Cell phone companies Individuals, WISP

License Yes NoCoverage Area Several km About 100m

Advantages Range, mobility Speed, cheapDisadvantages Relatively slow Expensive Short range

Comparison 3G versus WiFi

3G Wi-Max (Wider-Fi)

Standard WCDMA,CDMA2000 IEEE 802.16

Max Speed 2 Mbps 10 to 100 MbpsOperations Cell phone companies Individuals, WISP

License Yes Yes/NoCoverage Area Several km Several km

Advantages Range, mobility Speed, long range

Disadvantages Relatively slow Expensive Interference issues?

Comparison 3G versus WiMax

MITM Attack

1. Attacker spoofes a disassociate message from the victim

2. 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

3. The attacker connects to the real AP using victim’s MAC address

WEP vs WPA vs WPA2

WEP WPA WPA2

Cript RC4 RC4 AES

Key rotation None Dynamic session keys

Dynamic session keys

Key distribution Manual inert over each device

Automatic distribution is possible

Automatic distribution is possible

Authentification Use WEP key 802.1x & EAP supported

802.1x & EAP supported

Authentification (802.1x / EAP)

• EAP - Extensible Authentication Protocol• 802.1X parte din 802.11i• 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.

DHCP Exchange

Filepeers

Controlle

d Port

Domain Controller

Certificate AuthoritySupplies client certs and

Certificate Revocation Lists (CRL)

EAP Connection

802.11/.1XAccess PointLaptop

Domain User/Machine

Certificate

ServerCertificate

RADIUS(IAS)

Uncontro

lled P

ort

802.1x

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

WLAN security methods comparision

Security typeSecurity

levelInstall &

maintenance

Integration & easiest to

use

WEP Static Low High High

IEEE 802.1X PEAP High Midle High

IEEE 802.1x TLS High Low High

References

• Mustafa Ergen, IEEE 802.11 Overview, http://wow.eecs.berkeley.edu/ergen/docs/IEEE-802.11overview.ppt

• Greg Goldman, Is for “Wireless Fidelity” or IEEE 802.11 Standard, http://www.khirman.com/files/image/ppt/WiFi.ppt

• tcil-india.com/new/new.../TCIL%2010%20WiFi%20Technology.ppt

No wireless is 100% secure!