[pkg-wpa-devel] Bug#630681: /usr/sbin/wpa_gui: When Using nl80211 wpa-driver, Signal Strength is Displayed as Zero

[Kel Modderman]

On Thu, 16 Jun 2011 07:26:40 PM Leo L. Schwab wrote:
> Package: wpagui
> Version: 0.7.3-3
> Severity: normal
> File: /usr/sbin/wpa_gui
> 
> 	When using wpa_gui to perform a scan for local WAPs, the signal
> strengths in the list of results will be diferent depending on what
> wpa-driver you've configured for that interface.
> 
> 	In my case, wpa_supplicant can talk to the iwl3945 driver using
> wpa-driver 'wext' or the newer 'nl80211'.  If you configure wext, then the
> results displayed by wpa_gui will have meaningful signal strengths

There exist a few people who believe the WEXT signal quality measurements
are crap - and that is why the quality property is always 0 with the nl80211
framework, it is not implimented there.

> displayed.  If, however, you configure nl80211, then wpa_gui will display
> all signal strengths as zero.
> 
> 	I did a little experiment using wpa_cli to look at the scan results.
> Here's a sample list of results using wpa-driver wext:
> 
> ----
> bssid / frequency / signal level / flags / ssid
> 94:44:52:5a:11:4c	2412	173	[WPA-PSK-CCMP][WPA2-PSK-CCMP][WPS][ESS]	
Belkin.3
> 14C 00:1b:2f:c4:c9:11	2462	219	[WEP][ESS]	ewhac-water
> 00:14:95:3e:f2:42	2437	190	[WEP][ESS]	2WIRE303
> 00:1b:2f:c4:c9:10	2462	219	[ESS]	ewhac-air
> 00:1f:27:74:74:00	2462	172	[ESS]	local-wifi
> 00:1d:7e:57:49:e9	2437	177	[WEP][ESS]	linksys_SES_42522
> 00:16:b6:ce:b1:9f	2437	175	[WEP][ESS]	jvelez
> ----
> 
> 	And here's a list of results using wpa-driver nl80211:
> 
> ----
> bssid / frequency / signal level / flags / ssid
> 00:1b:2f:c4:c9:10	2462	-32	[ESS]	ewhac-air
> 00:16:01:92:e1:89	2417	-83	[WPA-PSK-TKIP][ESS]	BERLOGA-101
> 94:44:52:5a:11:4c	2412	-83	[WPA-PSK-CCMP][WPA2-PSK-CCMP][WPS][ESS]	
Belkin.3
> 14C 00:1b:2f:c4:c9:11	2462	-33	[WEP][ESS]	ewhac-water
> 00:14:95:3e:f2:42	2437	-62	[WEP][ESS]	2WIRE303
> 00:16:b6:ce:b1:9f	2437	-78	[WEP][ESS]	jvelez
> ----
> 
> 	It seems evident that different signal strength units are returned
> from the two wpa-drivers, which is confusing wpa_gui.  Please investigate
> this matter.

A signal measurement in dBm is returned by the nl80211 driver. It could 
provide the basis for a more meaningful signal indicator in wpa_gui.

There difficult part is that wpa_gui doesn't know which driver is being used 
so it is a little difficult to support two different signal/quality methods 
based on the information it does know.

Thanks, Kel.