NETGEAR ProSafe WG302 Reference Manual page 94

Reference Manual for the NETGEAR ProSafe 802.11g Wireless Access Point WG302
– Michael message integrity code (MIC)
– AES support (WPA2, requires hardware support)
• Support for a mixture of WPA, WPA2, and WEP wireless clients to allow a migration strategy,
but mixing WEP and WPA/WPA2 is discouraged
These features are discussed below.
WPA/WPA2 addresses most of the known WEP vulnerabilities and is primarily intended for
wireless infrastructure networks as found in the enterprise. This infrastructure includes stations,
access points, and authentication servers (typically RADIUS servers). The RADIUS server holds
(or has access to) user credentials (for example, user names and passwords) and authenticates
wireless users before they gain access to the network.
The strength of WPA/WPA2 comes from an integrated sequence of operations that encompass
802.1X/EAP authentication and sophisticated key management and encryption techniques. Its
major operations include:
• Network security capability determination. This occurs at the 802.11 level and is
communicated through WPA information elements in Beacon, Probe Response, and (Re)
Association Requests. Information in these elements includes the authentication method
(802.1X or Pre-shared key) and the preferred cipher suite (WEP, TKIP, or AES).
The primary information conveyed in the Beacon frames is the authentication method and the
cipher suite. Possible authentication methods include 802.1X and Pre-shared key. Pre-shared
key is an authentication method that uses a statically configured pass phrase on both the
stations and the access point. This obviates the need for an authentication server, which in
many home and small office environments will not be available nor desirable. Possible cipher
suites include: WEP, TKIP, and AES (Advanced Encryption Standard). We talk more about
TKIP and AES when addressing data privacy below.
• Authentication. EAP over 802.1X is used for authentication. Mutual authentication is gained
by choosing an EAP type supporting this feature and is required by WPA. 802.1X port access
control prevents full access to the network until authentication completes. 802.1X
EAPOL-Key packets are used by WPA to distribute per-session keys to those stations
successfully authenticated.
The supplicant in the station uses the authentication and cipher suite information contained in
the information elements to decide which authentication method and cipher suite to use. For
example, if the access point is using the pre-shared key method then the supplicant need not
authenticate using full-blown 802.1X. Rather, the supplicant must simply prove to the access
point that it is in possession of the pre-shared key. If the supplicant detects that the service set
does not contain a WPA information element then it knows it must use pre-WPA 802.1X
authentication and key management in order to access the network.
B-10
v0.1, December 2005
Wireless Networking Basics