User's Manual

PRELIMINARY
Atheros Communications, Inc. Page 26
COMPANY CONFIDENTIAL March 2004
Uninstall an Old Driver
Uninstall an old driver before upgrading to a new NDIS driver release.
To remove the newly installed driver from the system if the system does not have previously
installed versions of the NDIS driver, proceed to Step 4
.
1.
To remove the NDIS driver from the OS, go to Device Manager, right-click Atheros
Wireless Network Adapter, and choose Uninstall.
2.
Click OK to uninstall the device.
3.
When the device is uninstalled from Device Manager, search for and delete the driver
files that reside in the system.
a.
Go to the Start menu and choose Search > For Files or Folders.
b.
Enter oem*.inf in the Search for files or folders named: field, and enter
Atheros in the Containing text: field.
c.
Click Search Now.
d.
A few files matching these criteria are possible, if previous drivers have
not been removed properly.
e.
Choose the files that have been found and delete them from the system.
4.
To complete the uninstallation, remove the file ar5211.sys from the folder
\WINNT\system32\drivers.
Additional Security Features
These security features prevent attacks on a wireless network's WEP keys. The wireless adapter
automatically supports each of these features, but these features must be enabled on the access
point.
Message Integrity Check (MIC)
MIC prevents bit-flip attacks on encrypted packets. In a bit-flip attack, someone intercepts an
encrypted message retransmits it after some alterations. Thus the receiver accepts the message
as legitimate. The MIC adds some bytes to each packet to protect it against tampering.
Temporal Key Integrity Protocol (TKIP)
This feature prevents attacks on WEP in which someone catches encrypted packets and uses
their initialization vector (IV) to decipher the WEP key. TKIP removes the predictability to protect
both unicast and broadcast WEP keys.
Broadcast Key Rotation
EAP authentication provides dynamic unicast WEP keys for wireless adapters, but uses static
broadcast keys. In broadcast WEP key rotation, the access point supplies a dynamic broadcast
WEP key and changes it at intervals.