Hostap station mode active scan question

Jouni Malinen jkmaline
Fri Dec 29 18:07:21 PST 2006

On Fri, Dec 29, 2006 at 06:45:25PM -0600, Sriram Chadalavada wrote:

>   We are trying to measure the Effective Isotropic Radiated Power(EIRP) of
> few prism3 based compact flash wireless cards running on an embedded target
> with hostap 0.3.8. For this purpose we need to have the cards transmitting
> without being associated to an access point. Probe requests sent as part of
> an active scan should be sufficient.

Setting the card in Host AP mode would make it send out periodic beacon
frames on one channel which could be even easier for this..

> If I use the 'iwlist wlan0 scan' command, does the card firmware perform an
> active scan with probe requests or does it simply perform a passive scan of
> the values already obtained from AP beacons?

This may depend on the firmware and regulatory configuration.. Should be
easy to figure out with a wireless sniffer, though.

> >From the hostap README, I came to know of the 'iwpriv wlan0 host_scan <x>'
> command which performs an active scan. Does this work even in the default
> firmware roaming mode?

Maybe, if you have new enough firmware.

> Also, is there a way I can restrict the active scan to be performed only in
> one channel at a time? Please let me know.

iwpriv wlan0 scan_channels <bitmask>

Jouni Malinen                                            PGP id EFC895FA

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