getscanlist command redundant?

[Frank Huang]

Marcelo.

Here is the difference between specific SCAN and broadcast SCAN:

In specific scan issued through wlanconfig, the SSID specified by user
will be included in probe request (this is done by firmware). This could
solve the problem for the AP which has hidden SSID feature enabled.

In broadcast SCAN issued through "iwlist", the SSID in probe request
will be broadcast SSID which length is 0. The AP with hidden SSID
feature enabled will not respond this probe request. So the scan by
"iwlist" can not find those APs which have hidden SSID feature enabled.

Regards,

Frank

-----Original Message-----
From: libertas-dev-bounces at lists.infradead.org
[mailto:libertas-dev-bounces at lists.infradead.org] On Behalf Of Marcelo
Tosatti
Sent: Thursday, November 16, 2006 2:47 PM
To: Dan Williams
Cc: Marcelo Tosatti; Ronak Chokshi; Alan Cunningham;
libertas-dev at lists.infradead.org
Subject: Re: getscanlist command redundant?

On Thu, Nov 16, 2006 at 08:01:50AM -0500, Dan Williams wrote:
> On Thu, 2006-11-16 at 03:26 -0200, Marcelo Tosatti wrote:
> > Ronak,
> > 
> > wlanconfig contains the "extscan/getscanlist" commands:
> > 
> > extscan
> >         This command is used to do a specific scan.
> > 
> >         Usage: wlanconfig ethX extscan <SSID>
> > 
> >         Example:
> >                 wlanconfig ethX extscan LINKSYS-AP
> > 
> >         To see the results of use getscanlist command.
> > 
> > getscanlist
> >         This command is used to get the scan results.
> > 
> >         Usage: wlanconfig ethX getscanlist
> > 
> >         Example:
> >                 wlanconfig ethX getscanlist
> > 
> > What is the purpose of the extscan command? One can achieve same
results
> > by doing a "iwlist ethX scan" and looking for a specific SSID,
right? Or
> > am I missing something? 
> 
> Likely, yes.  iwlist doesn't let you scan for a particular SSID at all
> at this time, but the SIOCSIWSCAN handler does allow this, and drivers
> like the IPW cards implement the specific-SSID scan option.  We should
> too if we don't already.

I still fail to see the purpose of a specific SSID scan? Like I said,
one can simply
scan all available SSID's and look for a particular one in that list.

include/linux/wireless.h shows:
        /*
         * Use this ESSID if IW_SCAN_THIS_ESSID flag is used instead of
using
         * the current ESSID. This allows scan requests for specific
ESSID
         * without having to change the current ESSID and potentially
breaking
         * the current association.
         */
        __u8            essid[IW_ESSID_MAX_SIZE];

The only scenario that I see it making sense is where a "global" scan
does not show a particular ESSID, where a specific one does. I wonder if
that can ever happen.

For now I'll just convert the specific SSID scan to debugfs (since as
you mentioned iwlist does not support it yet).

> Other than that, there seems to be some redundancy here.
> 
> dan
> 
> > And about "getscanlist", I don't see how it provides any additional
> > information other than "iwlist ethX scan" and "getscantable" ?
> > 
> > -bash-3.1# ./wlanconfig eth0 getscanlist
> > Driver build with Wireless Extension 21
> > 
> > BSSID:   00:13:46:36:EB:48
> > SSID:    ult
> > NetMode: infra
> > Quality: 216
> > Privacy: disabled
> > 
> > No of AP's = 1
> > 
> > Thanks
> > 
> > _______________________________________________
> > libertas-dev mailing list
> > libertas-dev at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/libertas-dev

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