Does anyone have a utility or method to show the IPv6 DUID for a client
system without relying on looking through a DHCP server's logs or
waiting until after a request is made?

I'd like to determine a client's DUID before I set it up for IPv6, that
way I can have it configured in the dhcpd6.conf file for a static
assignment before it gets set up.

I really don't care if it's an LL, LLT or UUID style as long as I can
get it.