Tips and Tricks for Setting Up a WLAN

These tips can help tweak speed and stability as well as security aspects of your WLAN.

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 field) or with NetworkManager or KNetworkManager. 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 specified by the manufacturer, 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 useful 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 dBm (updated)
    Typical/Reference : Quality:26/94  Signal level:-60 dBm   Noise level:-90 dBm

Security

If you want to set up a wireless network, remember that anybody within the transmission range can easily access it if no security measures are implemented. Therefore, be sure to activate an encryption method. All WLAN cards and access points support WEP encryption. Although this is not entirely safe, it does present an obstacle for a potential attacker. WEP is usually adequate for private use. WPA-PSK would be even better, but it is not implemented in older access points or routers with WLAN functionality. On some devices, WPA can be implemented by means of a firmware update. Furthermore, although Linux supports WPA on most hardware components, some drivers do not offer WPA support. If WPA is not available, WEP is better than no encryption. In enterprises with advanced security requirements, wireless networks should only be operated with WPA.