mavsniff

Capture and replay MAVLink packets from your drone or GCS. Works on Linux and Windows.

You can read from a serial line (/dev/ttyXXX or COMx) or even from network (TCP and UDP). Mavsniff stores packets in pcapng format so you can analyze them with Wireshark.

Installation

pip install git+https://github.com/dronetag/[email protected]

If you are running mavsniff on WSL then you need a tool for forwarding USBs to Linux. For that, WSL uses usbip on Linux side sudo apt install usbip and WSL USB Manager on Windows side.

For installation on Windows, you will need Python3 (install from Windows Store) and Git (install from https://git-scm.com/).

Usage

Finding your device

Once your device is plugged into your computer you need to find out which port it got connected to. It will be /dev/ttyACMx (or /dev/ttyUSBx) on Linux and COMxy on Windows mavsniff ports list all compatible serial connections on your computer.

$ mavsniff ports
Usual baudrate is 115200, sometimes 57600
Your available COM ports are:
 - /dev/ttyACM0: Dronetag Beacon 2 [USB VID:PID=1900:5212 SER=397E9D237C782B7B LO...]

on Windows, the output might be more cryptic but hopefully only one COM port will show up and that will be your device (COMxy)

Your available COM ports are:
 - COM67: USB Serial Device (COM67) [USB VID:PID=1900:5212 SER=397E9D237C782B7B LO...]

Capture (or replay) MAVLink traffic

Now you are ready to to capture or replay traffic. Both commands have the same arguments --device and --file. The target file will always have .pcapng suffix because it is compatible with latest WireShark

Supported devices

• -d /dev/ttyS0 - standard serial port on UNIX systems
• -d COMx - from COM1 to COM99 - standard serial ports on Windows systems
• -d udp://<host>:<port> or tcp://<host>:<port> - receive or send packets over network (TCP or UDP)
• -d file.tlog - almost any (at least a bit standard) binary or textual file can be replayed

$ mavsniff capture --device COM67 --file recording --baud=57600 # for serial line, specify baud if different from 115200
$ mavsniff replay -f recording -d udp://localhost:12250 --mavlink-dialect path-to-custom/my-dialect.xml

Mavsniff never ends! Even if it finished processing your file it will keep waiting for more input. Simply kill it with ctrl+c.

Inspect with Wireshark.

Wireshark doesn't know MAVLink packets by default. It needs MAVLink dissector in form of an addon to show you MAVLink packets correctly. We created a command to compile such addon from the default dialect or your own and install it into the default wireshark addons folder.

$ mavsniff wsplugin # install Wireshark MAVlink disector plugin for reading Mavlink packets

Now you should be able to open and inspect MAVLink commands in your Wireshark.

Using with network

mavsniff uses compatible format of UDP packets with QGroundControl. That means if you capture packets emitted (mirrored) by QGroundControl with Wireshark then you will be able to replay those to any serial device. Those packets have minimal ethernet header 02 00 00 00 and uses 20 bytes long IP header and only 8 bytes for a UDP header. Any other packets will not be replayable by mavsniff.

MAVLink dialects

MAVLink is an extensible format that is configurable with XML definitions. Those are called dialects. Default dialect is arduinomega and version is 2.0. You can specify your custom dialect in form of mavlink's XML definition via --mavlink-dialect/-m flag. Mavsniff will copy your XML into internal pymavlink folder and compile it on the first run. All subsequent runs won't update nor recompile your dialect. Once your custom dialect was imported and compiled, you can reference by its name (XML filename without extension).

Developement

Start developing by cloning the repo and installing tha application locally

$ git clone [email protected]:katomaso/mavsniff.git && cd mavsniff
$ python -m venv .venv && source $VENV
$ pip install poetry
$ poetry install -E dev
$ poetry run pytest