Appendix E Wireless LANs

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 builtin "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.

1The AP passes the wireless client's authentication request to the RADIUS server.

2The RADIUS server then checks the user's identification against its database and grants or denies network access accordingly.

3A 256-bit Pairwise Master Key (PMK) is derived from the authentication process by the RADIUS server and the client.

4The 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 579 WPA(2) with RADIUS Application Example

WPA(2)-PSK Application Example

A WPA(2)-PSK application looks as follows.

1First 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).

2The AP checks each wireless client's password and allows it to join the network only if the password matches.

 

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ZyWALL USG 100/200 Series User’s Guide