shellypro3em_old fails to bind on UDP 1010 (PermissionError) on Raspberry Pi, while Shelly broadcasts from Venus battery are visible

[Gizzbert]

Hi, first of all: thanks for AstraMeter – really nice piece of work.

I’m running into a very specific issue with the Shelly Pro 3EM emulation (for a Marstek Venus E v3.0 battery) on a Raspberry Pi. The short version:

• shellypro3em_new starts and listens on UDP 2220
• shellypro3em_old fails to start with PermissionError: [Errno 13] Permission denied when binding the UDP socket (presumably on 1010)
• At the same time, I can see the Venus continuously broadcasting UDP packets to 192.168.0.255:1010, so the device is sending discovery traffic
• Because the “old” listener never comes up on 1010, the Venus will never find the emulated Shelly

Environment

• Device: Raspberry Pi 4 (4 GB)
• OS: Raspberry Pi OS DietPi v10.3.3 (64‑bit) (up to date)
• Docker: version 29.4.3, build 055a478
• Docker Compose: version v5.1.3
• AstraMeter image: ghcr.io/tomquist/astrameter:latest
• AstraMeter Git commit reported in log: cc8d94d

Network:

• Raspberry Pi 4b on Wi‑Fi (wlan0)
• Marstek Venus E v3.0 on same Wi‑Fi / same L2 LAN
• Router: R7800 running OpenWrt 24.10.5, default LAN firewall (input/output/forward ACCEPT, intra‑zone ACCEPT)

docker-compose service

services:
  astrameter:
    image: ghcr.io/tomquist/astrameter:latest
    container_name: astrameter
    restart: unless-stopped
    network_mode: host
    environment:
      - TZ=Europe/Amsterdam
      - LOG_LEVEL=debug
    security_opt:
      - apparmor=unconfined
    # (no extra ports, host network)
    volumes:
      - ./config/config.ini:/app/config.ini

config.ini (relevant parts)

[GENERAL]
DEVICE_TYPE = shellypro3em
THROTTLE_INTERVAL = 2

[HOMEASSISTANT]
IP = 192.168.0.130
PORT = 8123
ACCESSTOKEN = <redacted>

POWER_CALCULATE = True
POWER_INPUT_ALIAS = sensor.electricity_meter_power_consumption
POWER_OUTPUT_ALIAS = sensor.electricity_meter_power_production
THROTTLE_INTERVAL = 2

No [SHELLY] input powermeter section is configured – the only powermeter is Home Assistant.

AstraMeter log
On startup I consistently get:

2026-05-16 19:11:07 INFO:astrameter:started astrameter application
2026-05-16 19:11:07 INFO:astrameter:Git commit: cc8d94d3320b1b4e90d2320f291bc93228228407
2026-05-16 19:11:07 INFO:astrameter:Device Types: ['shellypro3em_old', 'shellypro3em_new']
2026-05-16 19:11:07 INFO:astrameter:Device IDs: ['shellypro3em-ec4609c439c1', 'shellypro3em-ec4609c439c1']
2026-05-16 19:11:07 INFO:astrameter:Skip Test: False
2026-05-16 19:11:07 DEBUG:asyncio:Using selector: EpollSelector
2026-05-16 19:11:07 INFO:astrameter:Starting web server...
2026-05-16 19:11:07 INFO:astrameter:Web server started on 0.0.0.0:52500
2026-05-16 19:11:07 INFO:astrameter:Web server started successfully
2026-05-16 19:11:07 INFO:astrameter:Applying section-specific throttling (2.0s) to HOMEASSISTANT
2026-05-16 19:11:07 DEBUG:astrameter:Testing powermeter configuration... (attempt 1/4)
2026-05-16 19:11:07 INFO:astrameter:Home Assistant WebSocket connected to 192.168.0.130
2026-05-16 19:11:07 DEBUG:astrameter:Home Assistant: auth required, sending token
2026-05-16 19:11:07 INFO:astrameter:Home Assistant: authenticated
2026-05-16 19:11:07 DEBUG:astrameter:Home Assistant: update_entity_value: sensor.electricity_meter_power_consumption, 0.28
2026-05-16 19:11:07 DEBUG:astrameter:Home Assistant: update_entity_value: sensor.electricity_meter_power_production, 0.0
2026-05-16 19:11:07 DEBUG:astrameter:Throttling: Fetched fresh values: [0.28]
2026-05-16 19:11:07 INFO:astrameter:Successfully fetched ThrottledPowermeter powermeter value (filter 0.0.0.0/0): 0.28W

2026-05-16 19:11:07 DEBUG:astrameter:Starting device: shellypro3em_old
2026-05-16 19:11:07 DEBUG:astrameter:Shelly Pro 3EM Settings:
2026-05-16 19:11:07 DEBUG:astrameter:Device ID: shellypro3em-ec4609c439c1
2026-05-16 19:11:07 ERROR:astrameter:Device shellypro3em_old (shellypro3em-ec4609c439c1) failed to start
Traceback (most recent call last):
  File "/app/.venv/lib/python3.12/site-packages/astrameter/main.py", line 326, in run_device
    await device.start()
  File "/app/.venv/lib/python3.12/site-packages/astrameter/shelly/shelly.py", line 294, in start
    transport, protocol = await loop.create_datagram_endpoint(
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/asyncio/base_events.py", line 1433, in create_datagram_endpoint
    raise exceptions[0]
  File "/usr/local/lib/python3.12/asyncio/base_events.py", line 1417, in create_datagram_endpoint
    sock.bind(local_address)
PermissionError: [Errno 13] Permission denied

2026-05-16 19:11:07 DEBUG:astrameter:Starting device: shellypro3em_new
2026-05-16 19:11:07 DEBUG:astrameter:Shelly Pro 3EM Settings:
2026-05-16 19:11:07 DEBUG:astrameter:Device ID: shellypro3em-ec4609c439c1
2026-05-16 19:11:07 INFO:astrameter:Shelly emulator listening on UDP port 2220...
So: shellypro3em_new is fine, shellypro3em_old cannot bind its UDP socket.

On the host:

bash
sudo ss -lunp | grep ':1010\|:2220'
UNCONN 0      0            0.0.0.0:2220      0.0.0.0:*    users:(("astrameter",pid=3114578,fd=8))

No other process is listening on 1010.

tcpdump from the Raspberry Pi
While the Venus is configured to use a Shelly Pro 3EM as meter, and during the pairing/connection attempts, I see this on the Pi:

bash
sudo tcpdump -ni any udp port 1010 or udp port 2220

Output (shortened):

19:53:42.120772 wlan0 B   IP 192.168.0.227.22222 > 192.168.0.255.1010: UDP, length 50
19:53:42.742624 wlan0 B   IP 192.168.0.227.22222 > 192.168.0.255.1010: UDP, length 50
19:53:43.358145 wlan0 B   IP 192.168.0.227.22222 > 192.168.0.255.1010: UDP, length 50
...
19:54:05.705293 wlan0 B   IP 192.168.0.227.22222 > 192.168.0.255.1010: UDP, length 50

So the Venus (192.168.0.227) is clearly broadcasting to 192.168.0.255:1010 on the same Wi‑Fi/L2 network.

What I expected
Given the README and the Shelly Pro 3EM emulation:

• shellypro3em_old should be able to bind on the appropriate UDP port (presumably 1010) on the Raspberry Pi
• It should then be able to receive these broadcasts from the Venus on 1010 and respond accordingly
• shellypro3em_new listening on 2220 is fine, but for my Venus firmware it seems the 1010 listener is the one that matters

Question
Is there a known reason why the shellypro3em_old UDP bind would hit PermissionError on some hosts (here: Raspberry Pi + Docker + host network), even when:

• no other process is bound to 1010
• the container runs with network_mode: host
• apparmor=unconfined and cap_add: [NET_ADMIN, NET_RAW] are set?

And more practically: could there be a bug or missing option in the way the “old” Shelly socket is created/bound that causes this on some Linux platforms?

Happy to run additional tests or builds and provide more logs if needed.

[tomquist]

The cause is the privileged-port rule on Linux: anything below 1024 (so 1010) can only be bound by root or by a process holding CAP_NET_BIND_SERVICE. The AstraMeter container runs as the non-root user astra (see Dockerfile), so the bind fails with EACCES, regardless of network_mode: host, AppArmor, or NET_ADMIN/NET_RAW (those capabilities don't cover binding low ports, only NET_BIND_SERVICE does, and ambient caps still have to reach the unprivileged user).

Two ways to get past it, pick whichever you prefer:

1. Lower the privileged-port range on the host (simplest with network_mode: host):

   sudo sysctl -w net.ipv4.ip_unprivileged_port_start=1010
   

   Add to /etc/sysctl.d/ to persist.

2. Run the container as root, by adding to the service:

   user: "0:0"

I'd lean toward option 1 on a dedicated Pi.

Separately, your config only declares shellypro3em so both _old and _new get started, which is intended. Once 1010 binds successfully the Venus should discover the emulator.

[Gizzbert]

Hah! Came here to post the same (ty Claude). Thanks for elaborating, might be useful to add as comment in the docker-compose.yml

They are now happily talking to each other. Next step is to find out if I can add another battery to this mix.

thanks!

[tomquist]

Already updated the readme here: #368

For multiple batteries I recommend to use the ct002 emulator instead of the Shelly emulator.

[Gizzbert]

I am on fw 148, didn't get CT002 to work (yet), thanks for your quick response!