On Mon, Dec 12, 2011 at 12:53:38PM -0800, Guy Harris wrote: > > Will I ever see HT40+,40- in case of beacons. > > Probably not. > > > Does this field in radiotap header (if it occurs) mean the interface beacon > > came from was having the above (equivilantly n ) support ? > > No. This field indicates how the particular frame was transmitted; it does > not mean that the transmitting device cannot transmit in any other format. > > > Ok. So, there is nothing as a N beacon.. > > Only advertisements at 1,6 rate and then actual data at N speed. > > Right. The beacons will generally be transmitted at low speed, so even older > stations can see them.
About the only time you'll see beacons on non-basic rates is a greenfield deployment, of which I've *never* found one in the wild despite all the manufacturers caring about it. Also under linux you will need to tune explicitly to CH+ or CH- to get 40mhz data packets, they will be silently ignored on just CH. This means you must use netlink to set the channel as siochannel can't understand HT+ and HT-. I don't recall offhand if you'll still see basicrate packets on CH+ or CH- settings. Sniffing 11n in linux is a big mess. -m --
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