On 09/05/2015 08:31 AM, Hazel Russman wrote:
On Fri, 4 Sep 2015 14:46:16 -0500
"Douglas R. Reno" <[email protected]> wrote:
On Sep 4, 2015 2:44 PM, "Bruce Dubbs" <[email protected]> wrote:
Simon Kitching wrote:
On 09/04/2015 12:40 PM, Hazel Russman wrote:
I've finally figured out the cause: the nl80211 backend doesn't work
with a hidden SSID. The wext one does. Reconfiguring my router to
publish the SSID suddenly makes nl80211 work again.
I've contacted the wpa_supplicant list to see if this is expected
behaviour or a bug. Probably a bug, as it doesn't exit with an error
message but just fails to detect a network.
(and yes, I know that a non-published SSID can still be detected
reasonably easily with the right tools, ie doesn't add much to security).
Note that in the sysv version of BLFS the wpa service script has:
/sbin/wpa_supplicant -q -B -Dnl80211,wext ...
-- Bruce
I wonder what the reason is for not including that in the systemd unit. I
will take a look into it soon.
When I started with wa_supplicant, I also had a hidden SSID. Like Simon, I couldn't get
the card to work, although it worked under NetworkManager in Mint. The interface itself
was up, but ip link showed "NO CARRIER". So I simplified things by cutting out
everything I could. I changed DHCP to a static address and the hidden SSID to a broadcast
one. Then suddenly it worked and I had no idea why. Now I know.
I asked on the wpa_supplicant list, and they informed me that my
wpa_supplicant.conf file was wrong. I was using ap_scan=2 but apparently
ap_scan=2 should never be used except "with broken drivers"; ap_scan=1
is recommended even with hidden SSIDs (ie scan_ssid=1).
Removing the "ap_scan=2" from my wpa_supplicant.conf did indeed fix the
problem.
Sadly, the wpa_supplicant.conf documentation is not very clear on this,
there is a lot of bad advice on internet forums, "wext" _does_ still
function with "ap_scan=2", and nl80211 doesn't warn about not supporting
ap_scan=2 (just fails to bring up the link). Ah well, the delights of
fiddling with Linux :-)
So in short: no need for a "-Dwext" or a "-Dnl80211,wext" in most cases
- just use ap_scan=1 (ie the default) and let wpa_supplicant default to
the nl80211 backend which is supported by all currently-maintained drivers.
Regards,
Simon
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