authentication types

[Bill Moss <bmoss clemson edu>]

The Cisco recommendation on security types is fairly representative.
http://www.cisco.com/warp/public/102/wlan/confwep.html
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*Accept Authentication Types*

Select the / *Open* / option, the / *Shared Key* / option, or both, to 
set the authentications the Access Point will recognize.

*Open (RECOMMENDED)*

This default setting allows any device, regardless of its WEP keys, to 
authenticate and attempt to associate.

*Shared Key*

This setting tells the Access Point to send a plain-text, Shared Key 
query to any device attempting to associate with the Access Point. This 
query can leave the Access Point open to a known-text attack from 
intruders. Therefore, it is not as secure as the Open setting.
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Note that a WEP key can be used with both Open and Shared Key 
authentication. It is a separate issue.

It is my impression that AP admins are moving away from Shared Key 
authentication but I don't have statistics to support this statement. NM 
first attempts to associate with Shared Key authentication and then it 
trys Open System authentication. On my campus, the Shared Key 
authentication test takes about 11 seconds before failing over to the 
Open System test. If the industry is moving away from Shared Key 
authentication, shouldn't NM test for Open System first and Shared Key 
second?


--
Bill Moss
Professor, Mathematical Sciences
Clemson University