On Mon, Aug 25, 2014 at 11:48:59PM +0100, peter green wrote:
> I'm not sure if standard wifi adaptors can be set in a mode where they=20
> will detect all packets even those they can't decrypt. Something like an=
=20
> ettus/NI USRP could certainly be programmed to do that kind of stuff but=
=20
> it doesn't come cheap.

The encrypted packets have an unencrypted encapsulation.

The radio in a conventional WiFi adapter will receive all packets.

Many have firmware that allow the host to read packets not intended
for it; a monitor mode.  Packets that can't be decrypted can be
released still encrypted to the host.

Some firmware also have a way to measure and report on the available
free air time on a channel, and one might code for detecting a drop in
free air time.

Some adapters also receive quite well off channel, so you can
configure them for channel 6 and still capture most stuff on several
channels adjacent.  (The packet header contains a frequency
declaration).

Otherwise you need more than one adapter.

--=20
James Cameron
http://quozl.linux.org.au/
--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.