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Subject: Re: [PATCH] mac80211: Send deauth to STA's upon AP stop
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Shay Bar <Shay.Bar@celeno.com>,
        Ben Greear <greearb@candelatech.com>
Cc:     "linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>
Date:   Thu, 30 Jul 2020 16:28:12 +0200
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On Thu, 2020-07-30 at 14:23 +0000, Shay Bar wrote:
> On 30/07/2020 17:00, Johannes Berg wrote:
> > External Email
> > 
> > 
> > On Thu, 2020-06-25 at 13:29 +0300, Shay Bar wrote:
> > > On 25/06/2020 12:51, Johannes Berg wrote:
> > > > External Email
> > > > 
> > > > 
> > > > On Sun, 2020-06-21 at 10:12 +0000, Shay Bar wrote:
> > > > > Hi Johannes and Ben,
> > > > > 
> > > > > To conclude this thread, hostapd doesn’t send any deauth/disassoc
> > > > > upon AP stop (when hostapd is killed _or_ when "ifconfig down" the
> > > > > AP interface).
> > > > Right. I'm sort of suggesting you just shouldn't be doing this, and it
> > > > doesn't seem like most people actually do, otherwise we'd have seen this
> > > > issue before?
> > > > 
> > > I shouldn't kill hostapd? Isn't this a very basic action?
> > > What is the alternative for stopping the AP?
> > I guess I would say to use hostapd_cli first to "disable" the
> > interfaces?
> 
> Indeed, using hostapd_cli "DISABLE" will call
> hostapd_flush_old_stations() that will send broadcast deauth.

Ah.

> The problem is (mentioned before) that some stations (e.g. Samsung S8)
> ignore this broadcast (while it will not ignore unicast
> deauth/disassoc).

Right, you mentioned that. I guess you could work around by disabling
all stations separately, but ... not really a great solution either.

Perhaps we should fix that at the hostapd level?

Not really sure how much trouble we should go to for bad stations
though. I mean, it's not like they should be ignoring that.

Maybe they just miss it due to super aggressive powersave, and we should
send it a few times?

johannes