802.11 "monitor mode" issues

[Sam Leffler]

On Friday 20 February 2004 12:38 pm, Adams, Kevin wrote:
> In the man pages of "ifconfig" it states that "monitor"...
> "Put the interface in monitor mode. No packets are transmitted,
> and received packets are discarded after bpf(4) processing."
>
> Now, using
>     ifconfig ath0 monitor up
>
> does not seem to be doing that.
>

The monitor thing is totally bogus; it should be removed.  You want to do the 
following:

ifconfig ath0 mediaopt monitor <other stuff> up

(where other stuff might be commands to set the channel).  At that point you 
can run programs like Ethereal and tcpdump w/o the driver trying to associate 
with an AP.

If you get the latest ethereal from CVS it has radiotap support which lets you 
look at frames "below the 802.11 layer".  The tcpdump port likewise has 
radiotap support; you do

tcpdump -i ath0 -y IEEE802_11_RADIO

(I think, this is from memory).

	Sam