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Overview
Overview
This appendix provides instructions for minimally configuring the client adapter through Windows XP
(instead of through ACU) as well as for enabling one of the security options that are available for use
with this operating system. The
options so that you can make an informed decision before you begin the configuration process.
In addition, the appendix also provides basic information on using Windows XP to specify the networks
to which the client adapter associates and to view the current status of your client adapter.
Note
If you require more information about configuring or using your client adapter with Windows XP, refer
to Microsoft's documentation for Windows XP.
Overview of Security Features
When you use your client adapter with Windows XP, you can protect your data as it is transmitted
through your wireless network by encrypting it through the use of wired equivalent privacy (WEP)
encryption keys. With WEP encryption, the transmitting device encrypts each packet with a WEP key,
and the receiving device uses that same key to decrypt each packet.
The WEP keys used to encrypt and decrypt transmitted data can be statically associated with your
adapter or dynamically created as part of the EAP authentication process. The information in the
WEP Keys"
of WEP keys you want to use. Dynamic WEP keys with EAP offer a higher degree of security than static
WEP keys.
WEP keys, whether static or dynamic, are either 40 or 128 bits in length. 128-bit WEP keys offer a greater
level of security than 40-bit WEP keys.
Static WEP Keys
Each device within your wireless network can be assigned up to four static WEP keys. If a device
receives a packet that is not encrypted with the appropriate key (as the WEP keys of all devices that are
to communicate with each other must match), the device discards the packet and never delivers it to the
intended receiver.
Static WEP keys are write-only and temporary; therefore, they cannot be read back from the client
adapter, and they are lost when power to the adapter is removed or the Windows device is rebooted.
Although the keys are temporary, you do not need to re-enter them each time the client adapter is inserted
or the Windows device is rebooted. This is because the keys are stored (in an encrypted format for
security reasons) in the registry of the Windows device. When the driver loads and reads the client
adapter's registry parameters, it also finds the static WEP keys, unencrypts them, and stores them in
volatile memory on the adapter.
EAP (with Dynamic WEP Keys)
The new standard for wireless LAN security, as defined by the Institute of Electrical and Electronics
Engineers (IEEE), is called 802.1X for 802.11, or simply 802.1X. An access point that supports 802.1X
and its protocol, Extensible Authentication Protocol (EAP), acts as the interface between a wireless
client and an authentication server, such as a Remote Authentication Dial-In User Service (RADIUS)
server, to which the access point communicates over the wired network.
Cisco Aironet 340, 350, and CB20A Wireless LAN Client Adapters Installation and Configuration Guide for Windows
E-2
Appendix E
"Overview of Security Features"
and
"EAP (with Dynamic WEP Keys)"
Configuring the Client Adapter through the Windows XP Operating System
section below describes each of these
sections below can help you to decide which type
"Static
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Table of Contents
Troubleshooting
