Testing protocol stack with OsmocomBB (cheap way)

Gianni Tedesco gianni at scaramanga.co.uk
Mon May 30 22:42:48 UTC 2011


On Tue, 2011-05-31 at 00:31 +0200, Drasko DRASKOVIC wrote:
> On Tue, May 31, 2011 at 12:18 AM, Gianni Tedesco
> <gianni at scaramanga.co.uk> wrote:
> > On Tue, 2011-05-31 at 00:05 +0200, Drasko DRASKOVIC wrote:
> >> Hi Gianni,
> >> after few hours of searching through the wiki pages, I have not been
> >> able to find the document you were mentioning that would explain
> >> attaching to cell and have some packet transfered through protocol
> >> stack up to the Wireshark.
> >>
> >> Are you sure that this document still exist and not have been removed/replaced ?
> >>
> >> All I have found that can resemble is this :
> >> http://bb.osmocom.org/trac/wiki/layer23
> >> but I guess that this is not what you are talking about, as it gives
> >> no detailed instructions for the things I want to obtain (i.e. which
> >> applications to start, in which order, what are things to observe,
> >> etc...).
> >
> > Pretty much, but also look at the page for your specific phone model and
> > http://bb.osmocom.org/trac/wiki/osmocon
> >
> > Basically you just need to use osmocon to load the layer1 firmware,
> > power the phone up and then if 'mobile' (or whatever app you want) is
> > running, it should be "all systems go". You can run
> > mobile/cell_log/whatever before or after booting the phone and it'll be
> > fine.
> >
> >> I tried some basic test by watching OsocomBB video presentations, as
> >> these are closest instructions and recepies on tools usage I have
> >> found to get one up and running, and I described troubles I have been
> >> facing in previous mail - I tried to guess what can be the right
> >> scenario as I find no docs, but I am still not able to synchronize to
> >> any cell, nor have some packets coming...
> >
> > It's not a complicated scenario and is well explained on the wiki:
> >
> > We have a firmware for the phone that we compiled on the PC
> >
> > We have a data cable between phone and PC
> >
> > The firmware does low level things
> >
> > Other apps running on the PC do high level things (eg. mobile phone)
> >
> > We use a loader program (osmocon) to load the firmware from the PC on to
> > the phone via the cable.
> >
> > After the firmware is running on the phone, we can run high level apps
> > on the PC (mobile, cell_log, etc).
> >
> > The high level apps communicate to the phone via the communication
> > channel setup by the loader.
> >
> > Most (all?) of the high level apps have a command line switch which
> > tells them to transmit GSMTAP logs to a specific IP address.
> >
> > You can use tcpdump to capture the GSMTAP info and view it in wireshark.
> 
> Yes, thanks. I gotten that. What I meant is more like some
> instructions how to get the system running, this what I am trying to
> achieve. Now, as you can see there is a lot of information spread all
> around and I have hard time to get them together in a meaningful
> picture.
> 
> What troubles me the most is these kind of information that are
> missing, for example :
> - start this application first, then this one
> - LOST message is OK
> - there is no SIM simulated, and you can not do anything without SIM,
> which is not supported on the master
> - connect this to this to get logs in Wireshark
> - etc...
> 
> Some kind of a tutorial that would prevent every starter to get stuck.

Sure. Although it is a goal of the project to bring awareness,
knowledge, access to GSM to a wider audience, osmocom is still highly
experimental software and that means that to do anything useful with it
you are going to need to be very comfortable with figuring out these
sorts of issues anyway. I mean, at this stage it's still very much for
hackers who are ready to roll their sleeves up and get stuck in.

I must say,  I didn't even know of sylvains driver (non obvious branch
name) or cell_log and had to write my own SIM access code to get going -
it was a fun night :)

Gianni





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