How is Openthread commissioned and joined before sending packet

[wassfila]

Question from @Ksathra first posted in #8 (comment)

Now I can see it uses UDP to send a data packet. What I couldn't figure
out is how openthread commissioning and joining part is done before
this. Could you please point me to the right direction?

[wassfila]

There are two ways how firmware can join a network

1. You already know the network and accept to hardcode the credentials in the firmware

2. You have to ship devices that are target Network agnostic, there you start talking about commissioning which is the process how to give credentials to a device on runtime (without modifying its firmware)

3. In my samples I focused on the first case for simplicity and even used dummy keys, which is as you might imagine a security breach if used outside experimentation context, here you can find the master key, and the openthread stack will find these config and use it to join automatically on its startup
   

   sdk-hsm-sensortag/samples/openthread_tag_alive/prj.conf

   Line 50 in 9b5d73e

   CONFIG_OPENTHREAD_MASTERKEY="00:11:22:33:44:55:66:77:88:99:aa:bb:cc:dd:ee:ff"

4. here, I experimented with a real commissioning process and provided links to the official documentation which I highly recommend to start with https://www.homesmartmesh.com/docs/networks/thread/#commissioning
   Here are the direct links again

• openthread commissioning
• commissioning commands
• dataset commands

The commissioning as you might doubt depends on the final product shipment conditions and final user app and environment, I would not even recommend defining an own commissioning process and would suggest to have a look at higher applicative protocols such as "Matter" that encapsulate that for you, but again, the software get even more complex, needs bigger devices and so on :)
https://www.homesmartmesh.com/docs/frameworks/matter/#comissioning