ZyXEL NWD271N User Guide - Page 70

User Authentication, Wireless Client WPA Supplicants, WPA2 with RADIUS Application Example - software download

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Appendix C Wireless LANs The encryption mechanisms used for WPA(2) and WPA(2)-PSK are the same. The only difference between the two is that WPA(2)-PSK uses a simple common password, instead of user-specific credentials. The common-password approach makes WPA(2)-PSK susceptible to brute-force password-guessing attacks but it's still an improvement over WEP as it employs a consistent, single, alphanumeric password to derive a PMK which is used to generate unique temporal encryption keys. This prevent all wireless devices sharing the same encryption keys. (a weakness of WEP) User Authentication WPA and WPA2 apply IEEE 802.1x and Extensible Authentication Protocol (EAP) to authenticate wireless clients using an external RADIUS database. WPA2 reduces the number of key exchange messages from six to four (CCMP 4-way handshake) and shortens the time required to connect to a network. Other WPA2 authentication features that are different from WPA include key caching and preauthentication. These two features are optional and may not be supported in all wireless devices. Key caching allows a wireless client to store the PMK it derived through a successful authentication with an AP. The wireless client uses the PMK when it tries to connect to the same AP and does not need to go with the authentication process again. Pre-authentication enables fast roaming by allowing the wireless client (already connecting to an AP) to perform IEEE 802.1x authentication with another AP before connecting to it. 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. 70 NWD-271N User's Guide

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Appendix C Wireless LANs
NWD-271N User’s Guide
70
The encryption mechanisms used for WPA(2) and WPA(2)-PSK are the same. The
only difference between the two is that WPA(2)-PSK uses a simple common
password, instead of user-specific credentials. The common-password approach
makes WPA(2)-PSK susceptible to brute-force password-guessing attacks but it’s
still an improvement over WEP as it employs a consistent, single, alphanumeric
password to derive a PMK which is used to generate unique temporal encryption
keys. This prevent all wireless devices sharing the same encryption keys. (a
weakness of WEP)
User Authentication
WPA and WPA2 apply IEEE 802.1x and Extensible Authentication Protocol (EAP) to
authenticate wireless clients using an external RADIUS database. WPA2 reduces
the number of key exchange messages from six to four (CCMP 4-way handshake)
and shortens the time required to connect to a network. Other WPA2
authentication features that are different from WPA include key caching and pre-
authentication. These two features are optional and may not be supported in all
wireless devices.
Key caching allows a wireless client to store the PMK it derived through a
successful authentication with an AP. The wireless client uses the PMK when it
tries to connect to the same AP and does not need to go with the authentication
process again.
Pre-authentication enables fast roaming by allowing the wireless client (already
connecting to an AP) to perform IEEE 802.1x authentication with another AP
before connecting to it.
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.