GoTenna + Sauron

This GNU Radio Module passively monitors goTenna traffic with a Software Defined Radio, logs raw packets to disk, and displays broadcast communication traffic to the screen.

Encrypted traffic is also logged. If enough of the conversation is captured, the "to", "from", and "length" fields are displayed.

You can download the slide deck for our presentation at the Wireless Village here.

@bjt2n3904 @tb69rr

The Code

This is a bit hacked together right now! My apologies.

In the python folder, you will find two files. The easiest to talk about is scapy_gotenna.py. There, you will find Scapy classes which detail the structure of goTenna packets.

Each goTenna packet starts with a byte indicating the packet type, and a sixteen byte long header. The header is interpreted differently for each part of communication.

Some goTenna packets are extended by a frame, which follows a standard type, length, data, checksum format.

gotenna_sink.py is the GNU Radio block responsible for intercepting, structuring, and printing the captured packets to the screen. (It is currently a horrendous mess.) It contains a finite state machine which tracks the current state of the communication channel, in efforts to inform the user what is happening.

The flow graph simply breaks the 4 MHz wide spectrum into the five channels, and demodulates each one separately. Received packets are sent to the goTenna sink, mentioned above.

Finally, multiportrx.py allows you to connect to and monitor multiple serial ports simultaneously. This is useful for monitoring the debug port on the goTenna.

TODO: The things we haven't accomplished!

• Checksums!
• Crypto / Signing
• Transmitting
• Indication of signal quality
• Group Chat / Emergency Broadcast
• How the goTenna handles bad / corrupted packets
• More documentation!
• Sample packets and *.cfiles for analysis!

Hardware Requirements

Your SDR needs to be able to listen to 150 MHz at 4 MSPS. For now, we have tested this project with the HackRF and the Ettus B200. You will obviously also need a goTenna to listen to communications!

This project does not (yet) work with RTL-SDRs, though it should soon!

Installing

There are a few requirements to run this script. PyBombs is coming soon! Until then, here is the manual process.

1. Install GNU Radio to your system via your favorite means. Don't forget to grab the development headers!
2. Install scapy
3. Install gr-reveng
4. Install gr-nwr at revision 2cce7cfb
5. Install gr-gotenna (this project)
6. Compile and run the flowgraph under apps/gotenna_4msps.grc

Remember, the standard method to install a GNU Radio module is:

1. cd gr-project
2. mkdir build && cd build
3. cmake ..
4. make -j8
5. sudo make install
6. sudo ldconfig

Greetz

• awalls for helping us use his awesome clock recovery tools