Re: mac80211 / iwl3945 + dynamic wep (again)

[drago01 <drago01@gmail.com>]

Johannes Berg wrote:
>> Because in the case of hidden SSIDs, wpa_supplicant pretty much says to
>> use ap_scan=2.
>>
>> There are a few problems here:
>>
>> 1) Historically, some drivers worked better with ap_scan=1 (madwifi),
>> others worked better with ap_scan=2 (many fullmac drivers)
>>
>> 2) scan_ssid=1 hasn't worked consistently on all drivers because it's
>> pretty new and many drivers don't support it yet.  This is supposed to
>> make the driver/firmware send out probe request for the SSID in
>> question.
>>
>> So basically, we're up shit creek without a paddle.  You have to use
>> ap_scan=2 on some cards because they don't support specific-ssid
>> scanning (with scan_ssid=1) to find the BSS you want to connect to, but
>> some cards can handle ap_scan=1+scan_ssid=1 OK.
>>     
>
> Fun. I'm pretty sure mac80211 handles ap_scan=1/scan_ssid=1 fine,
> sending probe requests for that specific SSID.
>
>   
yes it does an work fine that way. but ap_scan=2 = no go.
I can get some logs tomorrow for you.
If I remeber correctly wpa_supplicant just says "Got X scan results" and 
never find the ssid asked for.
>> NM has logic to cache the BSSIDs of APs you've connected to before, and
>> to match those up with an SSID when it sees them in the scan list if the
>> AP isn't broadcasting the SSID.  Unfortunately, that information isn't
>> available to wpa_supplicant because wpa_supplicant doesn't have an
>> interface to handle that sort of thing.  Therefore, when faced with an a
>> request to connect to a hidden network, wpa_supplicant must rely
>> _entirely_ on the driver Doing The Right Thing with scan_ssid=1 or
>> ap_scan=2, and that almost never works due to inconsistency in driver
>> implementation.
>>     
>
> Who invented hidden SSIDs anyway? Well, I guess I can actually test this
> now that I finally have a second mac80211-based wireless card, although
> iwl4965 is special wrt. scanning. I guess the trick will be to make
> ap_scan=2 work although ap_scan=1/scan_ssid=1 works much better :(
>
>   
well a "fix" would be for nm to try ap_scan=2 when it fails fall back to 
ap_scan=1 + scan_ssid=1 bt thats nothing more than a hack.
> We can fix that in nl80211 by making sure that scan_ssid is implemented
> right away and whoever has nl80211 support needs to support that so that
> we can rely on it...
>   
yes that should finally fix it ... but until then we need something that 
works.