This is a repo with the sources from https://github.com/ptrkrysik/gr-gsm in a docker to easily decode GSM with a rtlsdr dongle.
Start the image with extra privileges to access the rtlsdr dongle and expose a ssh-port:
$ docker run -ti --privileged -p 2224:22 marcelmaatkamp/gnuradio-gr-gsm-ptrkrys:latest
root@gnuradio-gr-gsm-ptrkrys# /usr/sbin/sshd
Then add your ssh pubkey into /root/.ssh/authorized_keys2
In another terminal ssh into the box with X-forwarding enabled:
$ ssh -X -p 2224 root@dockerhost
root@gnuradio-gr-gsm-ptrkrys# locale-gen en_US en_US.UTF-8
root@gnuradio-gr-gsm-ptrkrys# export LC_ALL="en_US.UTF-8"
root@gnuradio-gr-gsm-ptrkrys# airprobe_rtlsdr.py
If you tune it right the terminal will display a flood of GSM messages:
I made a nogui version which will output the gsm stream:
root@gnuradio-gr-gsm-ptrkrys# # airprobe_rtlsdr_nogui.py -p 55 -g 48 -f 9.462e+08
You can now open Wireshark and inspect the GSM messages on port 4729/udp