Re: kde (again)?

[Dan Williams <dcbw redhat com>]

On Thu, 2005-12-15 at 12:07 -0800, Michael Blakeley wrote:
> My AP never shows up from a 'sudo iwlist wlan0 scan' at all - that's
> kind of the point, as I understand it. If you don't know that it's
> there, you can't access it. But I'm sure you know more about wifi than I do.
> 
> My card is a broadcom, via ndiswrapper. Perhaps that's the problem? I 
> believe ndis (and thus ndiswrapper) doesn't support some scanning modes.

Right, there are 3 possible cases here:

1) completely invisible access point; I've heard at least one other case
where the access point doesn't broadcast its ESSID or its BSSID, but I
consider these to be broken.  AFAIK, by the spec, access points are
required to broadcast beacon packets.  And if you're not broadcasting at
least your BSSID (the 'Address' in iwconfig) in the beacon packet, then
the beacon packet is pretty much useless because you can't tell what the
heck its for.

2) The broadcom/ndiswrapper combination isn't reporting access points
correctly.  Ideally, you could pop in another type of card and see what
it says, to determine whether the driver is at issue.

3) The card has "privacy" mode set.  Privacy mode (or sometimes "drop
unencrypted") is part of the 802.11 spec that causes the card to drop
all unencrypted packets when the card is in encrypted mode (ie, when you
have a key set on it).  However, I don't believe that the card can drop
management frames like the beacon broadcasts.  Sometimes this is
filtered in the driver.  I'd call drivers that drop management frames
from non-encrypted access points broken as well.  If the driver is in
the Linux kernel, then it can be fixed.  ndiswrapper drivers likely
cannot be fixed in this way.

In any case, if the access point is set only to not broadcast its ESSID
(but still broadcasts beacon frames) then NM should be able to handle
it; otherwise it's a bug.  I've got my home AP doing this, so I know it
should work (except for certain Cisco cards as mentioned earlier).

Dan