ZyXEL Communications ZyWALL5UTM 4.0 User Manual

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ZyWALL 5/35/70 Series User’s Guide
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Chapter 9 Wireless LAN
If this feature is enabled, it is not necessary to configure a default encryption key in the 
Wireless Card screen (see 
). You may still configure and store 
keys here, but they will not be used while dynamic WEP is enabled.
To use dynamic WEP, enable and configure dynamic WEP key exchange in the Wireless 
Card
 screen and configure RADIUS server settings in the AUTH SERVER RADIUS screen 
(see 
). Ensure that the wireless station's EAP type is configured to 
one of the following: 
• EAP-TLS
• EAP-TTLS
• PEAP
Note: EAP-MD5 cannot be used with dynamic WEP key exchange.
9.11  Introduction to WPA
Wi-Fi Protected Access (WPA) is a subset of the IEEE 802.11i standard. Key differences 
between WPA and WEP are user authentication and improved data encryption. 
9.11.1  User Authentication 
WPA applies IEEE 802.1x and Extensible Authentication Protocol (EAP) to authenticate 
wireless clients using an external RADIUS database. You can't use the ZyWALL's Local User 
Database for WPA authentication purposes since the Local User Database uses EAP-MD5 
which cannot be used to generate keys.  See later in this chapter and the appendices for more 
information on IEEE 802.1x, RADIUS and EAP. 
If you don't have an external RADIUS server you should use WPA-PSK (WPA -Pre-Shared 
Key)  that only requires a single (identical) password entered into each access point, wireless 
gateway and wireless client. As long as the passwords match, a client will be granted access to 
a WLAN. 
9.11.2  Encryption 
WPA improves data encryption by using Temporal Key Integrity Protocol (TKIP), Message 
Integrity Check (MIC) and IEEE 802.1x. 
Temporal Key Integrity Protocol (TKIP) uses 128-bit keys that are dynamically generated and 
distributed by the authentication server. It includes a per-packet key mixing function, a 
Message Integrity Check (MIC) named Michael, an extended initialization vector (IV) with 
sequencing rules, and a re-keying mechanism.