How to make a simple $7 IMSI Catcher

UPDATE: 2022 Jan. 20 - new text guide for ubuntu 20.x LTS:

This guide can be found here: https://www.lostserver.com/static/ims...

Install Ubuntu 20.04 LTS
# Check all the boxes on the "Ubuntu Software" tab within Software & Updates.
# .. then login so you have a shell / prompt..

Install sudo - or shift user to root
su - root
apt-get update -qq -y && apt-get install -y sudo

Install dependencies first
sudo apt-get update
This one takes some minutes
sudo apt install -y git cmake autoconf libtool pkg-config build-essential python-docutils libcppunit-dev swig doxygen liblog4cpp5-dev gnuradio-dev gr-osmosdr libosmogsm10 libosmosdr0 libosmocodec0 libosmogsm-doc libosmosdr0 libosmocodec-doc libosmosdr-dev libosmocoding0 libosmocoding-doc libosmocore libosmocore11 libosmocore-dev libosmocore-doc libosmocore-utils libosmoctrl0 libosmoctrl-doc libgmp3-dev liborc-dev python3-pip

Prepare for downloading src code
cd ~
mkdir source
cd source

Create the gnuradio dirs
mkdir ~/.grc_gnuradio/ ~/.gnuradio/

Run gnuradio-config-info to find
the version you have installed
gnuradio-config-info -v

If 3.7 # that is an older version
git clone https://git.osmocom.org/gr-gsm

If greater than 3.8
git clone -b maint-3.8 https://github.com/velichkov/gr-gsm.git

Compile gr-gsm
cd gr-gsm
mkdir build
cd build
cmake ..

Now check the output from the last cmake command
If it reports missing stuff then you should install that also
before the next step.
make
sudo make install
Run this:
export PYTHONPATH=/usr/local/lib/python3/dist-packages/:$PYTHONPATH

Add this to the file: ~/.bashrc
export PYTHONPATH=/usr/local/lib/python3/dist-packages/:$PYTHONPATH

To fix error like -- No module gr-gsm found do this
sudo cp -r /usr/local/lib/python3/dist-packages/grgsm/ /usr/lib/python3/dist-packages/

Then update the ldconfig:
sudo ldconfig

#### CLONE THE IMSI LOGGER CODE ####

Change directory back to your source directory ~/source
cd ../..
Git clone the code
git clone https://github.com/Oros42/IMSI-catche...

Find the celltowers
#--------------------------------------------------------
Run this and wait for it to finish to find the frewquencies of the
celltowers around you

sudo grgsm_scanner

Output will look like this:
ARFCN: 1014, Freq: 933.0M, CID: 12117, LAC: 22012, MCC: 238, MNC: 66, Pwr: -30
ARFCN: 1017, Freq: 933.6M, CID: 12118, LAC: 22012, MCC: 238, MNC: 66, Pwr: -28
ARFCN: 1019, Freq: 934.0M, CID: 12119, LAC: 22012, MCC: 238, MNC: 66, Pwr: -47
ARFCN: 0, Freq: 935.0M, CID: 12117, LAC: 22012, MCC: 238, MNC: 66, Pwr: -27
ARFCN: 37, Freq: 942.4M, CID: 5226, LAC: 541, MCC: 238, MNC: 1, Pwr: -34
ARFCN: 39, Freq: 942.8M, CID: 5225, LAC: 541, MCC: 238, MNC: 1, Pwr: -32
ARFCN: 40, Freq: 943.0M, CID: 5227, LAC: 541, MCC: 238, MNC: 1, Pwr: -47
ARFCN: 49, Freq: 944.8M, CID: 5225, LAC: 541, MCC: 238, MNC: 1, Pwr: -27

Now that you know where the celltowers freq is then start the grgsm_livemon GUI
in one terminal with the found freq as parameter to -f as seen below:

sudo grgsm_livemon -f 933.0M --serverport 10000

Then in another shell / terminal window:
cd ~/source/IMSI-catcher/
sudo python3 ./simple_IMSI-catcher.py -h

That was it

If it does not pick up any imsi/tmsi then tune the Freq.

NB: If you can the console behind the GUI you might see numbers like this - that is the right freq
4c 69 6b 65 56 69 64 65 6f 3d 53 65 6e 64 63 68 6f 63 6f 6c 61 74 65
00 6b 65 6c 64 2e 6e 6f 72 6d 61 6e 40 67 6d 61 69 6c 2e 63 6f 6d 00

Watch terminal 1 and wait. The TMSI/IMSI numbers should appear shortly
If nothing appears after 1 min, change the frequency.

You can also watch the GSM packets in wireshark like this:
sudo apt-get install -y wireshark tshark # NB: tshark is a commandline version of wireshark
sudo wireshark -k -Y '!icmp && gsmtap' -i lo # ignore errors about not running wireshark as root.