WPS PIN timeout in wpa_supplicant

Jouni Malinen j at w1.fi
Tue Jun 22 12:13:07 EDT 2010


On Tue, Jun 22, 2010 at 11:03:57AM +0200, marten.wikstrom at keystream.se wrote:

> I have a question regarding the timeout of 120 seconds for wps_pin command
> in wpa_cli. Does this timeout come from the WPS specification or is it
> just chosen the same as the timeout for WPS PBC?

There is no specification requirement for this and the same timeout
seemed reasonable for most PIN use cases.

> The reason for the question is that I'm trying to fit in wps support in an
> embedded system without user interface and a PIN printed on a label. As I
> understand WPS PIN, the user should only have to enter the PIN of the
> device in the AP and then everything should be configured automatically
> from there. But if I start wpa_supplicant and wps_pin when the device
> boots, it will stop working after two minutes. Am I missing something
> here? Is there another way to do it? Obviously I can make a two-minute
> loop and restart wps_pin every other minute, but to me it doesnt feel to
> be the right way.

If the device is battery powered, I would not expect that you would like
to keep it actively scanning and association with WPS APs all the time.
If that is not an issue for the device, sure, you could do this. At this
point, running wps_pin command every couple of minutes is indeed the
only way to implement that. It should be relatively simple to extend the
wps_pin command to take in a timeout value as an optional parameter.

-- 
Jouni Malinen                                            PGP id EFC895FA


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