While any good sysadmin knows to use "WPA" for their Wi-Fi network security, and not the older and more vulnerable "WEP", there are some cases where it is necessary to use WEP, particularly to ensure compatibility with older Wi-Fi client hardware. If your network is one of those using WEP, and you use an Apple Airport or Airport Extreme base station (including Airport Express), you may have experienced problems connecting Windows XP/2000 and other non-apple Wi-Fi clients to your network.

When using WEP for network security, Wi-Fi clients using Apple Airport cards can authenticate to the network using the same text ASCII password that was entered in the Airport admin program when the network was created. However, due to inconsistent standards adoption in the earlier days of wireless networking, Wi-Fi clients using non-Apple hardware need to authenticate using a "Hexidecimal equivalent password," or "WEP key." Such a key is simply the ASCII password translated such that each text Roman character is represented by a 2-character hexadecimal equivalent. To find out what the WEP key is for your Airport network, use the Airport admin utility to log on to your base station, then click the "Password" button at the top. Use the key shown to join your non-apple client to your AirPort WiFi network.

To avoid this hassle altogether, there is a trick to make WEP keys work regardless of the client platform, without having to deal with hexidecimal equivalent WEP keys. If your base station uses 40 bit wireless security, choose a 5-character network password (i.e. "login"), or if you use 128 bit wireless security, choose a 13-character password (i.e. "airportlogin1"). When you've done this, you can enter the regular text password (not the hex equivalent), regardless of client hardware.