[CentOS] how to display/create DUID?

Sat Sep 18 23:10:49 UTC 2021
hw <hw at gc-24.de>


I would like to assign an ipv6 address through the DHCPv6 server of 
pfsense.  To configure a static address, I need to tell the DHCPv6 
server a DUID.

Apparently DUIDs belong to a particular machine and aren't supposed to 
ever change unless you re-install the operating system.  I guess every 
network card would need it's DUID because devices can have multiple 
network adapters, though ... and what happens when you change out the card?

IIUC, the DUID is required to ask for/get ipv6 addresses from a DHCPv6 
server.  So there must be a way to create one, and perhaps it has 
already been created.  Does networkmanager do that?

So how/where do find I this DUID on my server?