Killing wpa_supplicant and wi-fi interface down problem

Raghavendra s.raghu at
Mon Nov 17 22:46:26 EST 2008

Hi Dan,

   I totally agree with your point that it is better to put interface down, 
when we kill wpa_supplicant. I my case I am using wpa_supplicant for 
associating with the AP. I can not use this for scanning becoz of limitation 
on the number of scan result it provides using control interface which is 
max of 15 or 16 AP info. Also I we want to set advnced configuration of 
interface like setting power management, RTS, txpower, getting MAC of 
interface...etc we need wi-fi interface up and wpa_supplicant does not 
provide support for these feature.

So I would like to know is there a way by which I can disable putting 
interface down, without changing wpa_supplicant code. I mean just by using 
some config while enabling wpa_supplicant or I should change wpa_supplicant 
code it self?


----- Original Message ----- 
From: "Dan Williams" <dcbw at>
To: "Raghavendra" <s.raghu at>
Cc: <hostap at>
Sent: Monday, November 17, 2008 9:12 PM
Subject: Re: Killing wpa_supplicant and wi-fi interface down problem

> On Mon, 2008-11-17 at 16:31 +0530, Raghavendra wrote:
>> Hi All,
>>   Whenever I use 'killall wpa_supplicant' command, it puts wi-fi
>> interface down?
>> Can any one tell me what is the reason behind this behaviour?
>> can we avoid this?
> What's the specific problem with this behavior?  When the supplicant is
> told to terminate, the association with the AP is almost certainly
> terminated or otherwise not able to be maintained.  Thus, there's
> nothing you can do with the previous setup of the card anyway.
> Furthermore, setting the card 'down' ensures that the driver refuses
> traffic (which it couldn't transmit anyway) and you won't get lost
> frames or other odd behavior (though the driver should be protecting
> against that, but sometimes drivers suck).
> dan

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