On Mar 19, 2013, at 9:27 AM, atul kumar <[email protected]> wrote:
> I felt like taking your suggestions , regarding few of modification i intent
> to do in 802.11 radio information.
>
> Actually I want to added 802.11n params like
> ShorGi,LongGi,Aggregation[Ampdu/Amsdu] , along with already existing
> DataRate,Channel,Rssi.
>
> So in short , I am trying to enhance or populate more of phyLayer information.
>
> Is it possible to add it ,
Yes, but we're not the ones who control that. Wireshark reads what it's given;
it does not, and will not, define its own file format or its own radio metadata
format. We want interoperability, not our own unique and proprietary file and
metadata formats.
The most commonly used radio metadata format on UN*X systems (Linux, *BSD, and
OS X) is radiotap. The group responsible for radiotap is the radiotap.org
group:
http://www.radiotap.org
See the "defined-fields" page:
http://www.radiotap.org/defined-fields
for stuff that radiotap *already* supports. In particular, see:
http://www.radiotap.org/defined-fields/MCS
which *already* has a guard interval flag that indicates whether there's a long
or short GI, so there's nothing to add if you're going to be using radiotap
headers.
See also
http://www.radiotap.org/defined-fields/A-MPDU%20status
to see if that provides some of the aggregation information you want.
If there's additional information you want, check to see whether it's already
been proposed:
http://www.radiotap.org/suggested-fields
and:
if it has, join the radiotap.org mailing list (instructions are on the
http://www.radiotap.org/Radiotap page) and participate in the discussions about
that proposal;
if it hasn't, join that list and propose it (there appears to be a form
on the http://www.radiotap.org/suggested-fields page for proposing new fields;
I don't know how that works).
Note, by the way, that RSSI is *not* one of the defined fields. Instead, there
are fields that give antenna signal power either in dBm:
http://www.radiotap.org/defined-fields/Antenna%20signal
or in dB from an arbitrary reference point:
http://www.radiotap.org/defined-fields/dB%20antenna%20noise
There is a suggested RSSI field:
http://www.radiotap.org/suggested-fields/RSSI
but it's only suggested because OpenBSD implements it, and, unfortunately, the
OpenBSD people decided to pick a code ("presence bit" value) for it that is the
same as the code for an existing defined field, so it *really* shouldn't be
used. If the antenna signal power (and antenna noise power) values aren't
sufficient for your purposes, you should advocate the adoption of the RSSI
field - with a different code value! - on the radiotap.org mailing list.
The other significant format, used on some UN*Xes (OS X, at least) and used
(along with, I think, radiotap) by AirPcap, is the PPI format:
http://www.cacetech.com/documents/PPI%20Header%20format%201.0.7.pdf
I don't know to what extent that's being extended. It's less widely used than
radiotap, so if you use it, there may be fewer tools that can handle it.
(Wireshark is not, and I, at least, have no interest in having it become, the
one and only tool for all capture file processing.)
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