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thread radio over the network

OpenThread does not run on the pi. it runs as Home Assistant's OpenThread Border Router app on the Home Assistant VM, and the radio stays here. ser2net exposes the SkyConnect on TCP port 8000, and the app's network device setting points at 192.168.1.96:8000. the app connects with socat and treats the socket as its serial port.

i ran the border router here twice, in containers, and went back to this both times. a border router here and the app cannot both use the radio at once, so it is one or the other. the history, the network as a whole, the second border router, and getting the app running again after the pi has been off are on the thread page.

ser2net reads /docker-data/ser2net/data/ser2net.yaml, which the compose binds in. the file lives on the pi, not in git:

ser2net.yaml, 8 lines 
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%YAML 1.1
---
connection: &skyconnect
  accepter: tcp,8000
  connector: serialdev,/dev/ttyUSB1,460800n81,local,rtscts
  options:
    kickolduser: true
    remaddr: 192.168.1.63,0;2001:db8:1000:1::63,0
line why
serialdev,/dev/ttyUSB1 the compose maps the SkyConnect's by-id path to /dev/ttyUSB1 inside the container
460800n81 the speed the app runs the radio at
local ignore the modem control lines
rtscts hardware flow control between ser2net and the radio. the app's flow control setting (on, its default) has no effect over the network socket, so flow control is set here
kickolduser: true ser2net takes one connection per port by default. without this, a half-open session left by a VM or app restart blocks the reconnect
remaddr only Home Assistant can connect, from its IPv4 or IPv6 address and any source port (,0). otherwise anything on the LAN can talk to the thread radio

i leave the banner off. ser2net can send one when a client connects, and that is text arriving in front of a binary protocol. mine used to, and it only worked because the framing throws away junk before the first frame.

ser2net reads the file at start, so after a change restart ser2net first, then the app.

checking it

ser2net logs only errors: a config it cannot load, a device it cannot open, and read or write failures. the image already runs it with -d, which sends those to docker logs. a working connection logs nothing, so an empty log is the good case.

sudo ss -tnp | grep ser2net

you should see one ESTAB line from Home Assistant's address. an IPv4 client shows with a ::ffff: prefix in front of its address, because ser2net listens on IPv4 and IPv6 on the same socket.

the app's log should show the thread role:

Mle-----------: Role detached -> router

the ESP board holds the primary backbone router (see watching a failover), so the app runs as the standby and does not log Backbone Router becomes Primary!.

remaddr has to match the source address Home Assistant connects from, which its OS picks. give it a fixed address, and check with ss rather than assuming.

i have not tested how remaddr interacts with kickolduser, so i do not test the restriction by connecting from another machine while the app is connected.