Linux WiFi: Deauthenticated Reason Codes

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So I’ve been having a fiddle with Linux and WiFi this evening in an attempt to make a wifi bridge (Windows can do it so why can’t Linux?)…

Anyway the long and short of it is that I was getting disconnected and de-authenticated from the access point. Having a quick look at dmesg said I was disconnected for “Reason 2″ and “Reason 6″; these on their own are not very helpful and so in a quest to find out what these codes meant, I found that there isn’t a list that’s published anywhere easy to find (a single forum post and in an IEEE pdf). The codes in italics are the most common.

Code Reason Explanation
0 Reserved Normal working operation
1 Unspecific Reason We don’t know what’s wrong
2 Previous authentication no longer valid Client has associated but is not authorised.
3 Deauthenticated because sending STA is leaving (or has left) IBSS or ESS The access point went offline, deauthenticating the client.
4 Disassociated due to inactivity Client session timeout exceeded.
5 Disassociated because AP is unable to handle all currently associated STAs The access point is busy, performing load balancing, for example.
6 Class 2 frame received from nonauthenticated STA Client attempted to transfer data before it was authenticated.
7 Class 3 frame received from nonassociated STA Client attempted to transfer data before it was associated.
8 Disassociated because sending STA is leaving (or has left) BSS Operating System moved the client to another access point using non-aggressive load balancing.
9 STA requesting (re)association is not authenticated with responding STA Client not authorized yet, still attempting to associate with an access point.
10 Disassociated because the information in the Power Capability element is unacceptable
11 Disassociated because the information in the Supported Channels element is unacceptable
12 Reserved Not Used or Special Purpose
13 Invalid information element.
14 Message integrity code (MIC) failure
15 4-Way Handshake timeout
16 Group Key Handshake timeout
17 Information element in 4-Way Handshake different from (Re)Association Request/Probe
Response/Beacon frame
18 Invalid group cipher
Association denied due to requesting STA not supporting all of the data rates in the BSSBasicRateSet parameter
The link speed requested by the client or AP is incompatible. (i,e. trying to operate N only speeds on a G AP)
19 Invalid pairwise cipher
20 Invalid AKMP
21 Unsupported RSN information element version
22 Invalid RSN information element capabilities
23 IEEE 802.1X authentication failed
24 Cipher suite rejected because of the security policy
25-31 Reserved Not Used or Special Purpose
32 Disassociated for unspecified, QoS-related reason Quality of Service has denied the action.
33 Disassociated because QoS AP lacks sufficient bandwidth for this QoS STA
34 Disassociated because excessive number of frames need to be acknowledged, but are not
acknowledged due to AP transmissions and/or poor channel conditions
35 Disassociated because STA is transmitting outside the limits of its TXOPs
36 Requested from peer STA as the STA is leaving the BSS (or resetting)
37 Requested from peer STA as it does not want to use the mechanism
38 Requested from peer STA as the STA received frames using the mechanism for which a
setup is required
39 Requested from peer STA due to timeout
45 Peer STA does not support the requested cipher suite
45-65 Reserved Not Used or Special Purpose
99 Typically “No Reason Code” / Unknown State
535 Reserved Not Used or Special Purpose

The first few reason codes where helpful while debugging my wifi related issues.


I’ve added a few more codes and descriptions; they conflict with a previous list from IEEE but this one is from Cisco and was discovered after an N wifi card refused to connect to an N router at N speeds.