behavior of among wpa_supplicant + madwifi + AP in mixed security mode.

YenJung Chang yenjung
Thu Oct 13 01:51:43 PDT 2005


I have had wpa_supplicant 0.3.8 + madwifi connect to an AP which
opened WPA-PSK + WEP 128 bits (mixed security mode). wpa_supplicant
could connect to the AP by WEP successfully, but failed in WPA-PSK.

It seems the root cause is that the key id of group key sent from AP
(handshake 1 of 2) is 0, and it is same with the key id of unicast
key. Therefore, the unicast key would be overwrote by the group key
after the key was set into madwifi driver, then data encryption would
be failed and the AP would disconnect the station.

AFAIK, the way of using 0 as the key id of group key is not
"recommended" in WPA spec, however, it is not forbad to use.
I believe some APs would have the same behavior as the AP I used has,
in particular, in mixed security mode.
I don't know whether it is a bug or not, I just let you all know this
situation. :)

Please let me know if you need any information about this.


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