IWEVPMKIDCAND Event

Paresh Sawant paresh.sawant at gmail.com
Thu Aug 27 01:56:49 EDT 2009


Thanks Jouni !

Since we have provision in wpa_supplicant code to handle IWEVPMKIDCAND
event, we must have tested that with some hardware/driver combination,
right ? is it possible to share information on those hardware/drivers
?

Is there a way to know beforehand at run time to know whether the
driver supports IWEVPMKIDCAND event notification? If we could know
that it does not support, then we could turn on 'ap_scan=1' during run
time, and facilitate preauthentications with right candidates. The
idea is to eliminate the race condition between event handlers for
driver driven IWEVPMKIDCAND event and ap_scan=1 driven event.

Why roaming is associated with IWEVPMKIDCAND ? IWEVPMKIDCAND is just
to facilitate the preauthentication with the candidate access points,
and that leads to pmksa caching and hence fast hand-off in case of
roaming, right? correct me if I'm wrong in understanding.

Thanks
- Paresh

On Thu, Aug 27, 2009 at 2:19 AM, Jouni Malinen<j at w1.fi> wrote:
> On Tue, Aug 04, 2009 at 12:36:12PM +0530, Paresh Sawant wrote:
>
>> I am using wpa_supplicant on Linux ( kernel 2.6.30 and WEXT V22). I am
>> looking for IWEVPMKIDCAND event notification when I have more than one APs
>> with same SSID configured as WPA2 enterprise.
>
>> Is it possible to know what all drivers support this event notification?
>
> Searching through the driver source code would probably be the best way
> of figuring that out..
>
>> I don't see the event coming on ath5K. I would like to know if it is
>> functionality of specific hardware and its driver OR it is within mac80211
>> subsystem ?
>
> It would be from mac80211 in the case of ath5k (or well, any driver
> using mac80211) _if_ they were to need this functionality. However, they
> do not. IWPMKIDCAND event is only used when the driver takes care of
> roaming (scanning, BSS selection, determination of when to roam), i.e.,
> when wpa_supplicant is not processing scan results (ap_scan=2 mode). In
> ap_scan=1 case (e.g., with mac80211), information about RSN
> pre-authentication candidates is derived from the scan results and a
> separate driver event is not needed.
>
> --
> Jouni Malinen                                            PGP id EFC895FA
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