Hostap station mode active scan question

Sriram Chadalavada swenggsri
Mon Jan 1 16:25:15 PST 2007

On 12/29/06, Jouni Malinen <jkmaline at> wrote:
> 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..

Yes. That very well might work but I am more inclined to use the cards in
station/client mode since that is how they will be deployed in the
production environment.

> 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.

We are using STA firmware rev 1.7.4 on one card and 1.8.3 on the other and
the cards are FCC approved for use in the US.

> 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>
I do not remember seeing this option in the README for 0.3.8 release
(actually I don't see it in the latest README as well). Nevertheless, will
give it a shot.

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