WLAN Authentication Frame
This page describes WLAN authentication frame and deauthentication frame as per IEEE 802.11 WLAN standard. It mentions WLAN status codes and reason codes.
Authentication in WLAN network refers to establishing the station's identity prior to complete the association. Deauthentication refers to terminating the same.
Different algorithms are developed for this purpose. Authentication Algorithm Number decides which algorithm will be selected. As there are many steps involved in the process, sequence number is used for all the frames during exchange authentication frames.
The 'Status Code' and 'Challenge Text' fields are used in various ways by different authentication algorithms
The challenge text is transmitted using the 'Challenge Text information element'.
This shared key authentication system requires that mobile station need to successfully decrypt
the encrypted challenge text.
Challenge Text Information Element:-
Element ID - 1 byte
Length- 1 byte
Challenge text- 1 to 253 bytes
WLAN Status Codes
Status code field is of 16 bits in size. It indicates success or failure of an operation. O indicates success and non-zero value indicates failure.
| WLAN Status Code | Description |
|---|---|
| Code-0 | Operation completed successfully |
| Code-1 | Unspecified failure |
| Code-2-9 | Unused |
| Code-10 | requested capability is too broad and hence can not be supported |
| Code-11 | reassociation denied, prior association can not be identified and transferred |
| Code-12 | association denied for a reason not specified in WLAN 802.11 standard |
| Code-13 | requested authentication algorithm not supported |
| Code-14 | unexpected authentication sequence number |
| Code-15 | authentication rejected,, the response to the challenge failed |
| Code-16 | authentication rejected,, the next frame in the sequence did not arrive in the expected window |
| Code-17 | Association denied; the access point is resource constrained |
| Code-18 | Association denied;; the mobile station does not support all the data rates required by the BSS |
| Code-19 | Association denied; the mobile station does not support the short preamble option |
| Code-20 | Association denied; the mobile station does not support PBCC modulation |
| Code-21 | Association denied,, mobile station does notsupport channel agility option |
| Code-22-65535 | reserved |
WLAN Deauthentication Frame
As the name suggests, it is used to end an authentication relation between AP and STA. Reason code field of size 16 bits is used here. It mentions the reason of why sender has not joined the network.
WLAN reason codes
| WLAN Status Code | Description |
|---|---|
| Code-0 | reserved |
| Code-1 | Unspecified |
| Code-2 | prior authentication is not valid |
| Code-3 | station has left the basic service area or extended service area and is de-authenticated |
| Code-4 | Inactivity timer expired and station was disassociated |
| Code-5 | Disassociated due to insufficient resources at the access point |
| Code-6 | Incorrect frame type or subtype received from unauthenticated station |
| Code-7 | Incorrect frame type or subtype received from unassociated station |
| Code-8 | Station has left the basic service area or extended service area and is disassociated |
| Code-9 | Association or reassociation requested before authentication is complete |
| Code-10 to 65535 | reserved |
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WLAN MAC frames Links
WLAN Association Request and response frame
WLAN authentication Request and deauthentication frame
WLAN beacon frame
WLAN passive vs active scanning frame
WLAN Probe Request and response frame
WLAN reassociation Request and response frame
WLAN RTS and CTS frame
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WLAN MAC LAYER PROTOCOL PART2
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