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Appendix B Wireless LANs
NWD271N User’s Guide
109
Wireless Client WPA Supplicants
A wireless client supplicant is the software that runs on an operating system instructing the
wireless client how to use WPA. At the time of writing, the most widely available supplicant is
the
WPA patch for Windows XP, Funk Software's Odyssey client.
The Windows XP patch is a free download that adds WPA capability to Windows XP's built-
in "Zero Configuration" wireless client. However, you must run Windows XP to use it.
WPA(2) with RADIUS Application Example
To set up WPA(2), you need the IP address of the RADIUS server, its port number (default is
1812), and the RADIUS shared secret. A WPA(2) application example with an external
RADIUS server looks as follows. "A" is the RADIUS server. "DS" is the distribution system.
1 The AP passes the wireless client's authentication request to the RADIUS server.
2 The RADIUS server then checks the user's identification against its database and grants
or denies network access accordingly.
3 A 256-bit Pairwise Master Key (PMK) is derived from the authentication process by the
RADIUS server and the client.
4 The RADIUS server distributes the PMK to the AP. The AP then sets up a key hierarchy
and management system, using the PMK to dynamically generate unique data encryption
keys. The keys are used to encrypt every data packet that is wirelessly communicated
between the AP and the wireless clients.
Figure 72 WPA(2) with RADIUS Application Example
WPA(2)-PSK Application Example
A WPA(2)-PSK application looks as follows.
1
First enter identical passwords into the AP and all wireless clients. The Pre-Shared Key
(PSK) must consist of between 8 and 63 ASCII characters or 64 hexadecimal characters
(including spaces and symbols).
2 The AP checks each wireless client's password and allows it to join the network only if
the password matches.