Re: no wireless networks detected

[Dan Williams <dcbw redhat com>]

On Sat, 2011-04-16 at 23:30 +0100, Timothy Murphy wrote:
> Junaid Naseer wrote:
> 
> > My networkmanager is not automatically detecting the dozen or so
> > wireless networks surrounding me, even though it used to do so earlier,
> > until i had to reninstall the system from scratch. All drivers etc are
> > installed and all versions of the OS and network manager are the same.
> > Earlier it used to work. Now it doesn't.
> 
> I've found NM often says "No wireless networks detected"
> even when it is actually connected to one.

It depends on the driver to tell NM the right networks.  If the driver
refuses to scan periodically, then NM can't display any networks.  You
can test this out sometimes by running:

iwlist wlan0 scan

and see what it says.  If it shows networks, then we'd expect NM to
display networks.  If it returns an error *and* NM says it's connected,
then it's probably the case that the kernel driver has a bug.

More information on debugging this sort of thing is at:

http://live.gnome.org/NetworkManager/Debugging

in the wpa_supplicant section.  wpa_supplicant is the program that does
the low-level WiFi stuff like scanning and connecting, and thus it's the
place that talks directly to the driver.

Dan