wpa_supplicant: It takes ~10 seconds to connect to a Hidden profile (scan_ssid=1)

Jouni Malinen j at w1.fi
Fri Jul 10 16:04:07 EDT 2015

On Wed, Jul 08, 2015 at 11:28:17AM +0000, Hahn, Maital wrote:
> I found an issue in the following scenario:
> I have one hidden profile (scan_ssid=1) defined in my conf file.
> The supplicant performs Normal Scan before performing Sched Scan.
> In the Normal Scan, it first scans for wildcard SSID, waits for 5 seconds, and then scans the profile's SSID.
> So the connection to the profile takes ~10 seconds. This is a bad user experience.

How many SSIDs does the driver support per scan request? Many drivers
support at least four different SSIDs for an active scan and as such,
can do the broadcast SSID (len=0) and the first three scan_ssid=1
networks in a single round.

> Suggested solution:
> In the Normal Scan, switch the order of the scans. Start with the profile's SSID and after 5 seconds scan for wildcard SSID.

I don't really want to optimize hidden SSID over proper AP behavior.
Hidden SSIDs should never be used taken into account how many issues it
causes and it being non-compliant with the standard requirements.

If you want to optimize for this case, I'd recommend increasing the
number of SSIDs supported by the driver for each scan request.

Jouni Malinen                                            PGP id EFC895FA

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