getscanlist command redundant?

Marcelo Tosatti marcelo at kvack.org
Thu Nov 16 17:46:44 EST 2006


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
> > 
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