How can i get the Unique IDentifier of client

[dotori1995]

I have used an example that server.py
i think it was great to use on raspberry pi 5.
I can't seem to find a function to get the unique identifier (MAC address, or something else) of a Raspberry Pi 5 client. Does such a function not exist? I am looking to use it as a substitute in an environment where WebSockets cannot be used.