The python script in this repository is designed to be ran as a Linux service on a robot that needs to be controlled remotely. By default the service listens for incoming TCP connections on port 17653 of any network interface.
A typical usecase involves running this python script at boot once the network comes online. For example with systemd, one could define a unit file as follows:
[Unit]
Description=Fernbedienung
After=network.target
[Service]
ExecStart=/usr/bin/python3 /usr/lib/fernbedienung/service.py
[Install]
WantedBy=multi-user.target
This script and systemd configuration is installed automatically on the Pi-Puck and IRIDIA Drone images generated using the meta-drone and meta-pipuck layers in this organisation.
The Fernbedienung protocol involves exchanging JSON messages over a TCP socket. The first four bytes of each message indicates the length of the JSON payload allowing the stream to be broken down into individual messages. An
Requests are sent from a client to a robot. The following table summarizes the possible requests:
| Request | Description | JSON |
|---|---|---|
| Halt | Runs the halt command on a robot | { "Halt" } |
| Reboot | Runs the reset command on a robot | { "Reboot" } |
| Process | Runs an program or script on the robot, streaming back its stdout, stderr, and termination status | |
| Upload | Uploads a single file to a robot |
Responses are sent from a robot to a client in response to a request. If a process has been started on a robot, the robot will continue to send responses whenever the process writes to the standard input or standard output until that process as terminated.
The protocol implements absolutely no security. Running this service means that any device on the same network can upload files and execute arbitary commands on a device running this client. If more security is required, consider running this service on localhost (127.0.0.1) and use SSH tunneling to access it.