Getting Hardware UUID

Windows

You may get the UUID value from PowerShell.

get-wmiobject Win32_ComputerSystemProduct | Select-Object -ExpandProperty UUID

Linux / FreeBSD

Use the dmidecode utility to get the UUID

dmidecode | grep -i uuid

You may need to install dmidecode since it usually isn't bundled with the base OS. On FreeBSD, it's available in ports at /usr/ports/sysutils/dmidecode.

VMWare ESXi

To get the UUID of the physical machine that your ESXi server is running on, login via SSH and run:

esxcfg-info |grep -i uuid

You will see a bunch of UUIDs, most of which pertain to disks/volumes. What you are looking for is:

|----System UUID..............................................5178962d-2fcf-df50-536d-000423d9985a