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Ethereal-users: RE: [Ethereal-users] Sniffing 802.11b control packets fromneighbouring channels

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From: "Henky Jatmiko Gunawan" <eng10810@xxxxxxxxxx>
Date: Sun, 5 Dec 2004 00:52:53 +0800
Channel 1 and channel 11? Interesting. :)

My observation is slightly different. When I am sniffing at channel 1, I only get beacons from channel 1 to 6. When in channel 11, I get beacons from channel 6 to 13 (My AP supports channel 1 to channel 13). Sniffing at channel 6 allows me to capture from channel 1 to 11. It seems that for my case, I can capture up to plus minus 5 channels.

Have tried to use other hardwares for the card? I have used orinoco cards and it seems that Orinoco captures less of the neighbouring channels. Instead of being able to capture beacons from plus minus 5 channels, I can only listen to plus minus one channel.

The only other card available to me is a Cisco Aironet card. I did not use it because Kismet (a wardriving program) claims that the firmware for Cisco does not provide proper channel control and the firmware hops channel whenever it feels like too. I did not hear of similar problem with Linksys or Orinoco, but I am not too sure how to check it either.

Regards,

Henky

-----Original Message-----
From:	ethereal-users-bounces@xxxxxxxxxxxx on behalf of Peter De Cleyn
Sent:	Fri 12/3/2004 6:25 PM
To:	Ethereal user support
Cc:	
Subject:	Re: [Ethereal-users] Sniffing 802.11b control packets fromneighbouring channels
Yes Henky, I observed the same using an identical setup. Linksys
WPC11, hostap and monitoring mode.

It seems that packets from other channels are visible, but  got the
impression that when data is transmitted over the monitored channel,
not all traffic from neighbouring channels is seen.

Neighbouring channels is actually an euphymism. I use 2 channel 1 and
11 and can observe packets from one when capturing on the other.

To be complete, the machine I use to capture the packets is equiped
with 2 WNIC cards and captures on both channels using 2 different
tethereal processes.

I'm also very curious about what causes this and more important, how
to avoid this!

regards,

Peter

On Thu, 2 Dec 2004 23:17:05 +0800, Henky Jatmiko Gunawan
<eng10810@xxxxxxxxxx> wrote:
> Has anybody tried to sniff 802.11b control packets from neighbouring channels?
> I was sniffing on channel 6 but I seem to be able to get beacons from the neighbouring channels as well. Has anybody observed this?
> 
> I was using Linksys WPC11 on hostap driver. I put it into monitor mode and set it to channel 6. I rotated my AP to provide service from channel 1 to channel 11, as I continue to sniff at channel 6. Strangely, ethereal seems to show that I have also captured beacons that are supposedly transmitted on other channels as well.
> 
> As far as I know, I should only be getting packets from channel 6. An article from this mailing list also seems to suggest that:
> http://www.ethereal.com/lists/ethereal-users/200401/msg00012.html
> 
> Regards,
> 
> Henky
> 
> _______________________________________________
> Ethereal-users mailing list
> Ethereal-users@xxxxxxxxxxxx
> http://www.ethereal.com/mailman/listinfo/ethereal-users
>

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