IWEVPMKIDCAND Event

[Paresh Sawant]

Thanks ! That helps !

Have we seen roaming working with "ap_scan=2" on Linux with any
hardware/driver ?

Thanks
- Paresh

On Thu, Aug 27, 2009 at 11:55 PM, Jouni Malinen<j at w1.fi> wrote:
> On Thu, Aug 27, 2009 at 11:26:49AM +0530, Paresh Sawant wrote:
>
>> 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
>> ?
>
> Well, that is assuming quite much.. The PMKID candidate event is mainly
> to support NDIS drivers, i.e., less frequently used on Linux. In theory,
> you could use this with ndiswrapper and an NDIS driver that is the
> actual source of the event. I don't know whether anyone has tested that.
> In addition, rndis_wlan driver does have code for emitting this event
> (again, due to its NDIS-like nature). Just like with ndiswrapper, I have
> no idea whether someone has actually tested this.
>
>> 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.
>
> I don't think there is any WEXT capability flag providing this
> information.
>
>> 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.
>
> RSN pre-authentication candidates are usually determined from scan
> results and as such, this is very much related to scanning and roaming
> in general. For the driver to be able to generate IWEVPMKIDCAND events,
> it will need to be processing scan results (similarly, when ap_scan=1 is
> used, wpa_supplicant can do the same processing internally and does not
> need the additional driver event).
>
> --
> Jouni Malinen ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?PGP id EFC895FA
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