Host-base Mode + selective scanning

Jouni Malinen jkmaline
Sat Mar 26 19:14:52 PST 2005

On Wed, Mar 23, 2005 at 06:26:02AM +0100, Marcin Dabrowski wrote:

> 	Is that true that host-based mode is only accesible in
> AP mode ??

I'm not sure that I understood what you mean, but yes, Prism2/2.5/3
firmware takes care of number of management tasks in client mode and
does not allow the driver to fully control things like authentication
and association frame sending.

> 	To implement selective scanning I need possibility to send
> probe requests and to process all received frames. But it seems that
> it can be achieved only in master mode with host roaming mode set to
> 2. Unfortunately master mode makes AP from my card :(

I don't see why this would require processing all received frames. It
should be enough to receive all Beacon and Probe Response frames. In
addition, Master mode does not use host roaming configuration and host
scan command can be used to do somewhat selective scanning (e.g., to
select which channels to scan).

> Also in master mode card receives all frames from all channel. Is it
> possible to force card to receive frames from chosen channels ?

Only in monitor mode (in which the card does not work correctly as far
as AP or client functionality is concerned).

> Another question is how to distinguish from which channel frame was
> received ?

Most IEEE 802.11b/g cards are unable to do this for frames sent in IEEE
802.11b rates. In other words, the card can receive frames sent on other
channels and still assume that they came on the currently configured
channel. However, if you are talking about IEEE 802.11b Beacon and Probe
Response frames, you could parse them and look at the DS params IE for
the advertised channel.

Jouni Malinen                                            PGP id EFC895FA

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