Stations can send a probe request packet to
elicit a probe response containing similar information. A probe request can be sent to a
particular station, or to the broadcast address (in which case, any response will come from
access points, or the equivalents in an IBSS).
2.2.4.2 Authentication and Deauthentication
The first step in creating an association between two stations is authentication. If a station
receives an association request from a station that is not authenticated with it, it sends a
deauthentication notice to the requester.
Authentication is achieved by an exchange of management packets. The standards
support several types of authentication.
The original standard provided only two forms: open and shared key. In open
authentication, any standards-compliant node is automatically authenticated. In shared key
authentication, the node must prove it knows one of the Wired Equivalent Privacy (WEP)
keys in use by the network.
These original methods are still supported, but the 802.11i revision added additional
steps for networks using the newer encryption methods. To avoid making complex changes
to the original protocol, these newer methods first use the older open authentication
method, then create a new security association between the two nodes during the
association phase immediately following.
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