bgscan simple not always working

Matthew Dalton msdalton
Mon Dec 2 22:08:52 PST 2013

Hi Holger,

Thanks for the reply.

I'll try the git HEAD as a last resort, but for now I'm trying to figure
out what's wrong while keeping the configuration constant.

Since my original post I have managed to get roaming working... but I did
it by putting system("wpa_cli roam bssid") calls in my code. Clearly
bgscan-controlled roaming could work (ie. there's nothing in my network
setup to prevent it), but it doesn't seem to work for me.

Anyway, I'm having much bigger issues now, with clients randomly dropping
of the wifi for no apparent reason. Putting "-ddddddt" in the command-line
for wpa_supplicant doesn't produce anything useful. Mostly a spamming of
STATUS and SCAN_RESULTS and the odd ROAM due to my forced roaming system
calls. Nothing to indicate that the network was absent for a few minutes. I
suspect the wifi access points are to blame for this, that their
mesh/bridge implementation is flaky, but I'm still trying to find real
proof that that's the case. If anyone knows where in the wpa_supplicant
source code such errors may be detectable, please let me know, even if it's
a reference to the current git HEAD of wpa_supplicant.


On Mon, Dec 2, 2013 at 9:37 PM, Holger Schurig <holgerschurig at>wrote:

> Hi Matt,
> most programmers here in this list use wpa_supplicant from the current
> git HEAD. So if you can compile that, replicate your problem and
> provide a log file, this would be helpful.
> You can git clone the hostapd project, then compile only
> wpa_supplicant. Then you can do "ifdown wlan0", and start the locally
> compiled wpa_supplicant: "./wpa_supplicant -s -i wlan0 -D nl80211 -C
> /etc/wpa_supplicant.conf -d". That way your Debian packaged
> wpa_supplicant won't be clobbered for the first test(s).
> wpa_supplicant automatically brings up the interface (equivalent of
> "ifconfig up", not setting IP adresses etc). But that is good enought
> for roaming tests.
> Also note that wpa_cli has a command "roam <bssid>" as a debugging
> aid. So you can try to roam manually to the AP in question, and then
> observe the debug output.
> Maybe the AP is simply sending beacons that he needs encryption, you
> wpa_supplicant.conf file doesn't contain any encryption, so APs with
> demand that are ignored for roaming decisions.
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