Wireles Networks The Definitive Guide.pdf - Csbdu.in

A.2.2 Authentication Algorithms Table
The authentication algorithms table reports on which authentication algorithms are supported by the
station on each interface. It is best thought of as the three-dimensional array shown in Figure A-4.
Figure A-4. The authentication algorithms table
In addition to the ifIndex index variable, an auxiliary index variable is used. The reason for the
auxiliary variable is that multiple authentication algorithms exist, and the table should report on all of
them. For each index, the auxiliary index allows several cells to report on one authentication algorithm
each. Each cell has two component objects:
dot11AuthenticationAlgorithm (enumerated type)
This object is set either to openSystem (1) or sharedKey (2) to report on the authentication
algorithm.
dot11AuthenticationAlgorithmsEnable (TruthValue)
This object reflects whether the corresponding authentication algorithm noted by the previous
object is supported by the interface that indexes the table. By default, it is set to true (1) for
open-system authentication and false (2) for shared-key authentication.
A.2.3 WEP Key Tables
Two tables report on the status of WEP key information. Both use the WEPKeytype defined data type,
which is simply a 40-bit string. The WEP key tables are shown in Figure A-5. WEP key tables are
supposed to be write-only, but a security advisory was issued in June 2001 against one vendor who
exposed the keys to queries using SNMP.
Figure A-5. WEP key tables
A.2.3.1 WEP default key table
The default key table is quite simple. Each interface has a maximum of four default keys associated
with it because the WEP specification allows for four default keys per network. When transmitted in
frames over the air, the WEP key ID for the default key runs from 0-3. In this table, however, the
index runs from 1-4. Each cell in the table has just one object:
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