Question on saving burst information

[Bhaskar11]

Thanks for the clarification. I'm developing in an unencrypted private
network so it did not strike me!

>>If you want to save the cleartext decoded burst, use tcpdump or wireshark.

I would like to extract only the SMS messages sent to me and save the text
only automatically from within my modified ccch_scan, without using
external monitoring tools like wireshark.

1. From what I have figured out so far, I need to catch the L2 packets at
the point where they are sent on gsmtap_send(), and then apply my own
decode to filter out SMS messages and extract data. Is this correct so far?

2. What reference material would you recommend for L2 packet formats? I
checked the 3gpp website, but there are so many versions of all specs that
I cannot figure what to use, and could not figure out where the format
definitions are given. Is there a better site generally for GSM specs? Or
should I be able to figure this out from the mobile app code alone? (I
tried that but kind of got lost in the call setup process. I will try again
anyway!)

Thanks for your prompt guidance.

B.


On Sun, Dec 30, 2012 at 6:06 PM, Sylvain Munaut <246tnt at gmail.com> wrote:

> Hi,
>
>
> > Would it not be more useful to save burst data after local_burst_decode?
>
> After  local_burst_decode they are not bursts anymore, they are L2
> packets and that call only works if either it's unciphered or if you
> know the key.
>
> If you want to save the cleartext decoded burst, use tcpdump or wireshark.
>
>
> > Is there some utility in storing it in its raw form? Looks like I am
> missing
> > something?
>
> They're stored by by ccch_scan ... but there are no utility to use
> those data, you have to write an utility to use those data in any way
> you'd like.
>
>
> Cheers,
>
>       Sylvain
>
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