multilayered solution that requires common-sense
evaluation and implementation. Obvious security fixes should be
implemented first, such as limiting administrative access and
disabling open access. WLAN security is closely tied to the
volume of traffic that traverses the network. Therefore, the
use of statistics to evaluate the relative vulnerability of the
network is a valuable step toward assessing WLAN security.
Attackers are more likely to target unsecured WLANs. Proper
planning and implementation is required: - Estimate
potential security threats and the level of security
needed.
- Evaluate the amount of WLAN traffic being
sent when selecting security methods.
- Evaluate tools
and options that are applicable to WLAN design.
Content 6.4 Configuring Cisco WLAN
Clients 6.4.1 Cisco 802.11a/b/g WLAN Client
Adapters The Cisco 802.11a/b/g wireless client adapters are
supported only by Windows 2000 and Windows XP. The Cisco
Aironet 802.11a/b/g Wireless LAN Client Adapters (CB21AG and
PI21AG) support IEEE 802.11a, IEEE 802.11b, and IEEE 802.11g
(2.4 GHz and 5 GHz). The following describes the appearance of
LED 0 and LED 1 for the CardBus and Peripheral Component
Interconnect (PCI) cards: - Power save mode:
Slow blink, off
- Awake from power save mode:
On, off (can be used to indicate power is applied; the hardware
automatically enters this state after exiting from power save
mode before any other activity)
- Looking for
network association: Alternate blink between LED 1 and LED
0
- Associated or joined with network, no
activity: Slow simultaneous blink
- Associated
or joined with network, activity: Fast simultaneous blink
(blink rate increases with activity)
The
installation wizard tool is in the file
WinClient-802.11a-b-g-Ins-Wizard-v26.exe. Check cisco.com
for later versions of this software. Installation requires a
reboot at completion. This forced reboot can be suppressed by
administrators who are installing other applications
simultaneously; however, a reboot is strongly recommended at
the end of the installations, and additional testing is also
recommended. If a card is not inserted during initial
installation, drivers are loaded in addition to utilities.
After a card has been inserted, the rest of the installation
takes place automatically.
Content 6.4
Configuring Cisco WLAN Clients 6.4.2 Cisco
Aironet Desktop Utility Installation The setup utility
allows you to install the driver, desktop utility, or both.
Figure shows the step in the Cisco Aironet installation process
where the option appears for installing the Site Survey
Utility. The Site Survey Utility for the 802.11a/b/g card is an
additional program that can be installed with the ADU. This new
Cisco Aironet Site Survey Utility is available with ADU release
2.0.X and later. To install, make sure you select the
Install Cisco Aironet Site Survey Utility checkbox. On
Windows XP, you can configure your Cisco Aironet Wireless LAN
Client Adapter through the Cisco ADU or a third-party tool,
such as the Microsoft Wireless Configuration Manager. Because
third-party tools may not provide all the functionality
available in ADU, Cisco recommends that you use ADU. (Please
note that a patch from Microsoft might be required to use the
Microsoft tool with WPA security.) On the next screen, select
whether you want to use ADU or a third-party tool to configure
your client adapter. By enabling the third-party tool, you
allow the client card to be controlled by another service, such
as Windows XP Wireless Zero Config. Note: If you select
a third-party tool, some of the ADU features are not available.
To activate those features, you must re-install ADU. ADU works
with AIR-CB21AG and AIR-PI21AG. Figure shows the main status
screen of the ADU under the Current Status tab. This
screen shows signal strength, association, IP address, and
channel. For more details, click the Advanced button.
The ADU main page does not list information about associated
access points; however, selecting the Advanced button displays
the Advanced Status tab, which provides that
information. Current signal strength and noise level can be
shown in either dBm or percent. You can change this setting
from the Options menu. The Profile Management tab
offers the following features: - Create up to 16
profiles; each profile can be imported or exported.
-
Set auto profile selection and weight the profiles according to
your preferences.
- Scan the card to get a list of all
open SSIDs and directly connect to one of them.
Figure shows how to create and modify profiles. The General tab
includes the following settings: - Profile name
- Wireless computer name (default: Windows computer
name)
- Up to three SSIDs
Figure shows
how to configure and modify security in the profiles. WPA and
WPA2 are supported as of version 2.0.x. Static WEP keys are
selected as Pre-Shared Key (Static WEP). WPA/WPA2
Passphrase selects WPA/WPA2 Pre-shared Keys (PSK).
Additional parameters for the selected security method have to
be configured by clicking the Configure button. To
increase connection speed, disable different wireless modes
that are known to not be available. The maximum transmit power
of the Cisco client adapter for IEEE 802.11a is 40 mW; for IEEE
802.11b/g, it is 100 mW.
Content 6.4
Configuring Cisco WLAN Clients 6.4.3 ADU
Diagnostics: Advanced Statistics Under the
Diagnostics Tab on the main screen of ADU, you can
select Advanced Statistics to see detailed receive and
transmit statistics of the adapter. This information is often
used for troubleshooting. The Advanced Statistics dialog box
shows the transmit and receive statistics and encryption
errors. Under the Diagnostics tab on the main screen of
ADU, you can select Adapter Information. The Adapter
Information dialog box includes the following information:
- WLAN adapter type
- Client adapter MAC
address
- Driver file and version
- Adapter
serial number
You can start the ADU troubleshooting
utility from under the Diagnostics tab of the main
screen or from the System Tray icon. This utility tests
the card, driver, radio, association, and network connectivity.
Click the Start Test button to execute the test. Click
View Results to display the detailed results. The
Aironet Monitor provides a System Tray icon, which
allows you to open the ADU, disable and enable the radio,
select profiles, and display the connection status and IP
address. If security with authentication is configured in the
active profile login, re-authentication can be initiated from
the system tray icon.
Content 6.4
Configuring Cisco WLAN Clients 6.4.4 Cisco
Aironet Site Survey Utility: Associated AP Status The Site
Survey Utility monitors transmitted network traffic, and the
link speed reflects the current transmit rate of data packets.
The Associated AP Status tab includes the following
information: - Adapter Information: Identifies
the selected network adapter and the current association
status. The association status options are Associated, Not
Associated, and Device Not Present.
- Access
Point: Identifies the name, IP address, and MAC address of
the access point.
- Channel: Identifies the
channel number and frequency.
- Signal Strength:
Shows how strong the signal is for all received packets. The
higher the value and the more green the bar graph, the stronger
the signal. The trend graph provides a visual interpretation of
the current signal strength. Differences in signal strength are
indicated by the following colors: green (strongest), yellow
(middle of the range), and red (weakest).
- Signal
Quality: Shows how clear the signal is for all received