NM less reliable than wpa_supplicant (and more confusing) when forcing a BSSID?

["Andrew Lutomirski" <luto myrealbox com>]

Hi all-

I work in a building with a lot of APs and a lot of users (MIT, in
case anyone's interested).  We have some APs that are overloaded (fail
association with "too many clients" or some such -- code 0x1100
according to Wireshark), and we have some APs that just plain don't
work (I can see traffic but I don't get a lease).  We also have plenty
of APs with strong enough signals that work fine.  Conveniently, they
all have ESSID "MIT."

Using wpa_supplicant directly, I can connect almost instantly using
something like:

network={
 ssid="MIT"
 scan_ssid=1
 key_mgmt=NONE
 bssid=<bssid of a good AP>
}

and then dhclient gets a lease quickly enough.

With NM, maybe one in ten tries works.  I tried to force a BSSID by
going to Edit Connections and creating a new connection with a
specific BSSID, which had no apparent effect whatsoever -- nothing
showed up on the menu, nothing connected, etc.  So, guessing at random
"connect to a hidden network," and selected my new connection (ahem,
"hidden?"), and clicked connect.  Didn't work either.

The NM logs say:

Nov 18 12:29:54 iridium NetworkManager: <info>  Config: added 'ssid' value 'MIT'

Nov 18 12:29:54 iridium NetworkManager: <info>  Config: added 'scan_ssid' value
'1'
Nov 18 12:29:54 iridium NetworkManager: <info>  Config: added 'bssid' value '00:
11:88:28:a6:50'
Nov 18 12:29:54 iridium NetworkManager: <info>  Config: added 'key_mgmt' value '
NONE'
Nov 18 12:29:54 iridium NetworkManager: <info>  Activation (wlan0) Stage 2 of 5
(Device Configure) complete.
Nov 18 12:29:54 iridium NetworkManager: <info>  Config: set interface ap_scan to
 1
Nov 18 12:29:54 iridium NetworkManager: <info>  (wlan0): supplicant connection s
tate change: 0 -> 2
Nov 18 12:30:19 iridium NetworkManager: <info>  Activation (wlan0/wireless): ass
ociation took too long, failing activation.

wpa_supplicant still works fine if I run it manually, even with ap_scan=1.

So, two sane questions...

1. Any ideas why NM can't connect when wpa_supplicant has no trouble?

2. Can you explain how the NM UI is supposed to work?  I know what a
BSSID is and I still can't figure it out how to use it properly.

...and two UI questions...

3. I'd love some kind of subtle control on the list of SSIDs that pops
up that lets me manually choose which AP to use.  ISTM it could be
done with less confusion that creating a manual network (what are
those "Auto" things, anyway?) and it would be handy in places with
lots of APs of which many don't work.  Of course, it would be even
better if NM could handle management frames saying that an AP is
overloaded and fall back to a different one.  Any chance of
reconsidering the UI a little to make this easier?

4. When NM fails to connect, all I get is a message that the network
is disconnected.  Could these be made more descriptive (e.g. "Unable
to communicate with the access point at all," "Unable to find the
access point," "Connected successfully but could not obtain an
address," "The access point is overloaded," etc.)?

I'd be happy to try things, test different versions/patches, and even
write code, with the caveat that I know *nothing* about GTK/Gnome.

This is on Ubuntu 8.10, with Ubuntu's NM build, using iwlagn on an
iwl4965 with 802.11n enabled (but the APs are all .11a or .11g).

Thanks,
Andy

P.S.  For all that I'm griping about NM's handling of lots of
unreliable APs, in other circumstances around here, it's better than
either Windows or Mac -- NM understands that different BSSIDs might
not share the same IP range and generally gets a new valid IP when I
roam across subnets, whereas other people often walk into a new
building and their laptops don't figure it out until they disable and
re-enable networking.