OpenGGSN

Terje Kristoffer Hybbestad Skow terjeks at stud.ntnu.no
Tue Mar 1 10:12:01 UTC 2016


Thank you Neels!

The "logfile /tmp/foo" did gave an error message saying "unrecognized
option".

I'm going to look at DNS packets going through a GGSN to try and find ways
to detect DNS tunnels, do you have any recommendations how to do this?
I do not have the time or resources to use real UE's so I hope to simulate
it on a computer using VMs or something like that.

I have looked at this: http://openbsc.osmocom.org/trac/wiki/OpenBSC_GPRS as
an idea of how to set up the testbed, but I do not know which of the nodes
I really need. Do you have any idea?


Regards
Terje Kristoffer Skow

2016-02-29 18:50 GMT+01:00 Neels Hofmeyr <nhofmeyr at sysmocom.de>:

> Hey Terje,
>
> On Mon, Feb 29, 2016 at 12:46:30PM +0100, Terje Kristoffer Hybbestad Skow
> wrote:
> > Does this mailinglist also regard openGGSN?
>
> Yes, the Osmocom community has adopted maintenance of OpenGGSN, even
> though it
> wasn't written "here".
>
> > If so do I have some questions. I have problem setting it up correctly.
>
> To test the basic openggsn I used to do something like this:
>
>
>   sudo -s
>
>   LD_LIBRARY_PATH=/usr/local/lib ./git/openggsn/ggsn/ggsn -f -c
> ./localggsn.conf &
>
>   ./git/openggsn/sgsnemu/sgsnemu --createif -l 127.0.0.1 -r 127.0.0.2
>
>
> With localggsn.conf as
>
> listen 127.0.0.2
> net 127.0.0.0/24
> pcodns1 8.8.8.8
> logfile /tmp/foo
>
>
> The above works on linux because it allows implicitly creating the
> 127.*.*.*
> interfaces. On other OSes, you'd have to create those first on one of your
> network interfaces.
>
> See http://git.osmocom.org/openggsn/tree/examples/ggsn.conf for more
> config
> options.
>
> I'd recommend to use wireshark to see what packets are transmitted back and
> forth, if you're not already doing that.
>
> I've "recently" implemented GTPhub, which relays GTP, e.g. through a NAT.
> If
> that's of interest too, call again, and I can give you an example config
> for
> testing sgsnemu -> gtphub -> openggsn, too.
>
> To actually relay data through the tunnel interface that is created, AFAIK
> you
> first need to send a Create PDP Context message to the GGSN. Maybe read
> http://git.osmocom.org/openbsc/tree/openbsc/tests/gtphub/gtphub_test.c
> For testing real data, I used an actual sysmoBTS with a "special" SIM card
> instead of sgsnemu, because here in the lab that was easier... :P
>
> Hope to have helped :)
>
> ~Neels
>
>
>
> --
> - Neels Hofmeyr <nhofmeyr at sysmocom.de>          http://www.sysmocom.de/
> =======================================================================
> * sysmocom - systems for mobile communications GmbH
> * Alt-Moabit 93
> * 10559 Berlin, Germany
> * Sitz / Registered office: Berlin, HRB 134158 B
> * Geschäftsführer / Managing Directors: Holger Freyther, Harald Welte
>
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