urity policy should specify the requirement for user authentication and strong passwords. Changing Default Shared Keys Although the fundamental cryptographic weakness has been recognised and addressed, as was described in the Section "WEP - Wired Equivalent Privacy Encryption, p. 209", it is still good security practice to enable data encryption using wired equivalent privacy (WEP) in pre-802.11i networks, and to use the longest supported shared key length. Some access points have factory set default encryption keys and, similar to SSIDs, it is recommended practice to change these default values when encryption is enabled. Figure 8-13 shows a typical access point configuration screen, with encryption keys being generated using an algorithm based on a password or passphrase entered on set-up. Shared keys or passphrases must be changed to maintain security whenever a previous network user is no longer authorised to access the network or if a device that has been configured to use the network is lost or compromised. Wireless LAN Security D-Link Building Networks for People Air Plus G 802.11g/2.4GHz Wireless Router Advanced Tools Status DI-524 Wireless Settings These are the wireless settings for the AP(Access Point) portion. Network ID(SSID) Another_SSC Channel Wizard Security Wireless Apply Cancel Help Figure 8-12: Changing SSID Default D-Link Bunding Networks for People AirPlus G 802.11g/2.4GHz Wireless Router Advanced Tools Status DI-524 Wireless Settings These are the wireless settings for the AP(Access Point) portion Network ID(SSID) Another _SSID Channel Wizard Security WEP Encryption 64 Bit Wireless Key Mode WEP Key A20B30CC40 Input 10 HEX characters (HEX is 0~9, A~F, or a~D Apply Cancel Help Figure 8-13: Enabling WEP and Specifying Shared Keys Chapter Eight MAC Address Filtering If MAC address filtering is enabled, the access point will review every request for access against a permit list held in its memory. The permit list holds the MAC addresses of all authorised client stations, and the access point will