24.6 Tips and Tricks for Setting Up a
WLAN
The following tools and tips can help to monitor and improve speed and stability as
well as security aspects of your WLAN.
24.6.1 Utilities
The package wireless-tools contains utilities that allow to set wireless LAN
specic parameters and get statistics. See http://www.hpl.hp.com/personal/
Jean_Tourrilhes/Linux/Tools.html for more information.
kismet (package kismet) is a network diagnosis tool with which to listen to the WLAN
packet trafc. In this way, you can also detect any intrusion attempts in your network.
More information is available at http://www.kismetwireless.net/ and in
the manual page.
24.6.2 Stability and Speed
The performance and reliability of a wireless network mainly depend on whether the
participating stations receive a clear signal from the other stations. Obstructions like
walls greatly weaken the signal. The more the signal strength sinks, the more the
transmission slows down. During operation, check the signal strength with the
iwconfig utility on the command line (Link Quality eld) or with the Network-
Manager applets provided by KDE or GNOME. If you have problems with the signal
quality, try to set up the devices somewhere else or adjust the position of the antennas
of your access points. Auxiliary antennas that substantially improve the reception are
available for a number of PCMCIA WLAN cards. The rate specied by the manufac-
turer, such as 54 Mbit/s, is a nominal value that represents the theoretical maximum.
In practice, the maximum data throughout is no more than half this value.
The iwspy command can displays WLAN statistics:
iwspy wlan0
wlan0 Statistics collected:
00:AA:BB:CC:DD:EE : Quality:0 Signal level:0 Noise level:0
Link/Cell/AP : Quality:60/94 Signal level:-50 dBm Noise level:-140
444 Reference
