[CentOS] how to display/create DUID?

Wed Sep 29 20:22:27 UTC 2021
hw <hw at gc-24.de>

On Sunday, September 19, 2021 6:53:45 PM CEST Kenneth Porter wrote:
> --On Sunday, September 19, 2021 3:02 PM +0200 hw <hw at gc-24.de> wrote:
> > None of this is working because the server isn't running a DHCPv6 server,
> > and there seems to be no file in /var/lib/NetworkManager that would seem
> > to be helpful.
> > 
> > Isn't there a tool that creates the DUID and prints it?  This can't be
> > too difficult ...
> I found this thread that suggests that NetworkManager computes it every
> time unless it's manually overridden:
> <https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/issues/135>

That might mean that I would need to extract the functions from the soruces of 
dhclient to make a program that prints DUID(s) for the machine you run it on. 
... But that isn't so easy.  Maybe I can find out how to create a DUID and 
write something in perl; it doesn't seem to be too complicated in the source.

The comment is interesting:

 * The "best" default DUID, since we cannot predict any information
 * about the system (such as whether or not the hardware addresses are
 * integrated into the motherboard or similar), is the "LLT", link local
 * plus time, DUID. For real stateless "LL" is better.
 * Once generated, this duid is stored into the state database, and
 * retained across restarts.
 * For the time being, there is probably a different state database for
 * every daemon, so this winds up being a per-interface identifier...which
 * is not how it is intended.  Upcoming rearchitecting the client should
 * address this "one daemon model."

I don't understand what the point of a DUID is which is /not/ a per-interface 
identifier.  When I assign addresses via DHCP, I don't want them to end up 
being assigned anywhere else than to the interface they need to be assigned 
to.  What is intended with these DUIDs?

> Based on that, nmtui-connect might do what you want.

That seems to only allow to bring up or down a connection but doesn't display