Since IPv6 is happening, we should be prepared. During the deployment of a new accesspoint I was in need of a Unique Local Address. IPv6 Unique Local Addresses basically are comparable to the IPv4 private address ranges.
Some sites refer to Unique-Local-IPv6.com, but that is offline nowadays. Others refer to kame.net generator, which is open source and still available yay.
But wait, there must be an offline method for this right? There is! subnetcalc (nowadays available here apparently) to the rescue:
subnetcalc fd00:: 64 -uniquelocal | grep ^Network