iwlist and scanning

From: ??? (imp_at_airlinktek.com)
Date: 2002-09-06 12:23:03 UTC

Dear Jouni Malinen..

Thanks for your reply...
but, I read your documentation http://hostap.epitest.fi/hostap/2002-06/0965.html I'd like try to scan other AP in one AP which running in Managed mode as your documentation means...

but, the problem is my wireless_ext version is 12 which located in /linux/include/wireless.h Eventhough I download most recently version of wireless tools I can't use the scanning in iwlist..

as my understand iwlist scanning only support WIRELESS_EXT > 13..

Could you tell me how can I solve this issue ? to running the scanning with iwlist ? I mean, I should keep this version of kernel... but, I'd like just upgrade only for the wireless extension parts.

How can I to do it ? please, give your advanced experience.. Thanks for your attention.

-----Original Message-----
From: Jouni Malinen [mailto:jkmaline_at_cc.hut.fi] Sent: Friday, September 06, 2002 12:01 AM To: Hostap
Subject: Re: basic question ...

On Thu, Sep 05, 2002 at 02:18:29PM +0900, ■ wrote:

> As I know, hostap which run as AP Mode can scan near around other APs... right ?
> if so, one AP can detect near around other APs and channel which used by other APs..

That's not exactly true. Current driver is able to notice beacons on the same channel (and possible the neighboring channels), but it does not scan others channels for APs.

> Could you tell me how can I scan other AP in AP mode ?

Station firmware does not seem to allow firmware based scanning functionality in Host AP mode, so this would need some sort of driver controlled mechanism. One could perform scanning every now and then by shutting down the AP for a few seconds and requesting firmware-based scan of the channels. Other option would be to go through the channels while staying in AP mode and passively scan channels by receiving beacon frames from other APs.

Both of the methods have some drawbacks since the normal AP functionality is disturbed. This might not be that bad a problem if the scanning is not performed frequently. When an AP changes channels, the associated stations might move automatically to the new channel (I've seen this happening), but then again, they might locate another AP and associate with it.

Jouni Malinen                                            PGP id EFC895FA

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