Thank you for your reply! I ran the ./bbn_80211b_tap.py and then I used Ctrl-C to stop the bbn_80211b_tap.py. After that I ran ./bbn_80211b_tap.py again. However, I got the error as follows:
I guess that I did not stop the ./bbn_80211b_tap.py correctly at the first time. What should I do to avoid this kind of error?
From: Doug Geiger <address@hidden>
To: Jane Chen <address@hidden>
Cc: address@hidden
Sent: Saturday, February 21, 2009 8:52:34 AM
Subject: Re: [Discuss-gnuradio] Beacon frames of BBN 802.11
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Jane Chen wrote:
> Hi all,
>
>
>
> I ran
bbn_80211b_rx.py and got the information as follows:
>
> PKT: len=163, rssi=-18, src="" time=13720, rate=1 Mbps
>
> PKT: len=163, rssi=-23, src="" time=21272, rate=1 Mbps
>
> .......
>
>
>
>
//
>
> According to the information of packets, I don't think I can know if
> these packets are beacon frames or not because I don't know the subtype
> of the frame. However, on the [Discuss-gnuradio] 802.11 on USRP+GNURadio
> : "/Looking at the archives, I understand that I can receive 1 Mbps
> probe/beacon packets with code developed by BBN",/ it seems I can know
> if the packets are beacon frames. Can anyone tell me how to know if
> these packets are beacon frames if it is possible? Thank you!
>
>
>
> Jane
>
The BBN 802.11 code can currently only deal with 1 and 2Mbps packets
(i.e. using either DBPSK or DQPSK modulation and DSSS with length-11
Barker Code). Since most WiFi traffic these days tends to be at higher
data rates (unless the client is far away from the access point, or
something similar), beacon frames are typically the only
traffic that
you will see with those rates: so it may be safe to assume that those
frames you are seeing are in fact beacons (or it may not, depending on
what sorts of wifi devices you have around).
If you get
bbn_80211b_tap.py running you should be able to run either
tcpdump or wireshark on the tap/tun interface it creates and you can get
some more information about the packets.
Doug
- --
Doug Geiger
Research Assistant
Communications and Signal Processing Lab
Oklahoma State University
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