Understanding the 802.11 Authentication Frame

As a part of 802.11 Supplicant and Authenticator handshake, A STA must perform Authentication with the Access Point. This Authentication is often confused with some sort of security handshake or user authentication, which it is completely not! So what it is in reality? Operating at the link level, these frames are fundamental components of the Open System authentication method, involving a two-message exchange process that ensures proper network access control.


Authentication Message Exchange:

The authentication process begins when an unauthenticated and unassociated Station, generates the first authentication frame. In this initial frame, the station includes its MAC address in both the Source Address (SA) and Transmitter Address (TA) fields, while the target BSSID is specified in the Destination Address (DA) and Receiver Address (RA) fields.

Wireshark Filter : "wlan.fc.type_subtype eq 11"




Access point responds with a second authentication frame. This response reverses the addressing, placing the station's MAC address in the DA and RA fields while using the BSSID's MAC address for the TA and SA fields. The frame includes an authentication result status, either "successful" or "unsuccessful."




If authentication succeeds, the station establishes a secure connection with the access point. However, if unsuccessful, the station must either retry the authentication process or search for an alternative access point. This straightforward yet effective mechanism ensures basic security in wireless networks while maintaining efficient network access control.

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