Review the concept of available ports

[oseasandrepro]

 s.bind((self.host, 0))

In the above piece of code, used in server stub to server a specific procedure,
you’re asking the OS to bind the socket to any available ephemeral port (port chosen automatically by the kernel).

It looks like available port is different to blocked/not blocked. So, the SO can bind an available port that is blocked by the firewall. I am not sure 🤔

[oseasandrepro]

Yes — in this scenario, the kernel(SO) will happily bind; the firewall will politely ignore the clients.

[oseasandrepro]

OK, to avoid this scenario (bind a procedure to a port that is available but blocked) and the necessity for the server host to open a range of ports.
I will use one specific port for all procedures, and config the firewall to not block this port.