non-beaconing access points

[Bill Moss <bmoss clemson edu>]

Until a few days ago, I had never heard of a non-beaconing access point 
(AP). A friend of mine has a NetGear MR814v2 and when you hide the 
ESSID, you don't just blank the ESSID in the beacon packet, you stop 
transmitting beacon packets. This is an area not covered by the 802.11 
standard. In the article on NM at 
http://www.ces.clemson.edu/linux/nm.shtml (which I try to keep 
reasonably up to date), I point out that there in now a consensus among 
wireless vendors that the best approach is to broadcast ESSIDs and use 
Open System authentication which insures that an AP will broadcast 
beacon packets containing the ESSID. My friend should use these settings 
on his NetGear MR814v2. Nevertheless, he tells me that early versions of 
NM would work with non-beaconing, but the current version will not. I 
have verified this with both ipw2200 and airo drivers so this is not a 
driver issue.

When you started early versions of NM in a area with no wireless 
beacons, the detecting icon would spin forever. If you clicked on 
'Connect to Other Wireless Network ...', entered ESSID and WEP key, you 
could make a connection to a non-beaconing AP. Then several people 
including myself complained and thus was born the no-connection icon and 
the 'STOP All Wireless Devices' context menu item. With CVS HEAD 1.441, 
it you boot in an area without wireless beacons, you see the 
no-connection icon immediately. No attempt at connection is made. This 
is good. Now if you  click on 'Connect to Other Wireless Network ...', 
enter ESSID and WEP key, nm-applet hangs in the detecting mode and the 
only way to stop it is to reboot. The 'STOP All Wireless Devices' 
doesn't work. You can kill NM but you can't kill nm-applet.

Looking at the debug log, you see that NM hangs in

NetworkManagerDevices.c: nm_device_activate_schedule_stage1_device_prepare

at the line

       g_source_set_callback (source, (GSourceFunc) 
nm_device_activate_stage1_device_prepare, req, NULL);

The function  nm_device_activate_stage1_device_prepare never gets called.

The simplest approach may be to say that NM doesn't support 
non-beaconing APs. If you want to duplicate this experiment, turn off 
your AP, boot, and try to make a connection with the 'Connect to Other 
Wireless Network ...' dialog.

--
Bill Moss
Professor, Mathematical Sciences
Clemson University