RTL-SDR stick not working in LXC + Docker with /dev/rtl_sdr mount under Proxmox

[Daniel-WW]

Hi all,

I’m having trouble getting my RTL-SDR stick to work inside a Docker container that runs inside an unprivileged LXC on Proxmox.

Setup:

• Proxmox VE 8.2
• Unprivileged LXC container with Ubuntu 22.04
• RTL-SDR stick (USB ID 0bda:2838) plugged into host
• In the LXC config, I only use this line to mount the device:
  lxc.mount.entry: /dev/bus/usb/001/003 /dev/rtl_sdr none bind,optional,create=file

The device /dev/rtl_sdr shows up inside the container (I can see it with ls -l /dev/rtl_sdr).

In Docker-compose, I pass the device like this:

services:
  rtl433:
    image: hertzg/rtl_433
    devices:
      - /dev/rtl_sdr:/dev/rtl_sdr
    privileged: true
    restart: unless-stopped

In the rtl_433.conf file I just have device 0 or i tried with device /dev/rtl_sdr, but the container keeps crashing right away. The logs don’t show any clear errors about missing device or permissions, it just restarts constantly.

Does anyone know what the correct config should be? Should the device path in the config be /dev/rtl_sdr or something else? Or is it even possible to use the stick like this in an unprivileged LXC + Docker setup?

Any help or hints would be appreciated, thanks!

If you want, I can help test or provide configs/logs. - Thanks and best Regards - Daniel

[hertzg]

The issue is that rtl_433 (via librtlsdr/libusb) specifically looks for USB devices in /dev/bus/usb/ - it won't detect devices at custom paths like /dev/rtl_sdr.

To fix this, you need to preserve the USB bus structure:

1. In your LXC config, mount the entire USB bus (or the specific device at its proper path):

lxc.mount.entry: /dev/bus/usb dev/bus/usb none bind,optional,create=dir

2. Or for a specific device, keep its bus path:

lxc.mount.entry: /dev/bus/usb/001/003 dev/bus/usb/001/003 none bind,optional,create=file

3. Then in Docker Compose:

devices:
  - /dev/bus/usb/001/003:/dev/bus/usb/001/003

For unprivileged LXC, you'll also need:

• Pass through USB device cgroup permissions in the LXC config
• Ensure proper UID/GID mapping for device access

Debugging steps:

1. Check container logs: docker logs <container_name>
2. Test with privileged mode first: docker run --privileged -v /dev/bus/usb:/dev/bus/usb hertzg/rtl_433
3. If privileged works, the issue is permissions - you may need to adjust cgroup device rules in the LXC config