How to generate a reliable UUID inside a guest image?

[Karl M. <kme...@me...>]

I was hoping to ask for some design help on VMWare.

I am developing a new licensing feature for a desktop app.


A typical solution to this problem is a stand-alone license server which 
just counts concurrent licensed instances on the LAN.    Unfortunately, 
the customer has taken that offtheytable and require us to do software 
only, disconnected, per seat activation.   I know their environment and 
their reasons are mission critical for them...

So to implement the license policy requires us to uniquely identify each 
physical machine the app is installed with a UUID.   For the case of 
Windows running hardware, we can make a hash value from the serial 
numbers in the bios through WMI and treat the hash value as a UUID.    
Although there is a risk a determined cheat could spoof their bios we 
decided that was an acceptable risk since bios spoofing is clumsy.   
Above a certain level of effort they could just edit our assembly and 
crack the security check anyway...


The case of Windows in a guest OS on VMWare is harder to design 
something robust to very simple cheating.   Just about everything in the 
guest OS is configurable and easily replicated with thevmxand 
checkpointing. So guest OS features like the bios or MAC addresses just 
seem too easy for a user to spoof by making many instances of particular 
(licensed) guest image.

I am looking for something an application can query which identifies the 
underlying host in a robust way.

One solution I been exploring is using theVMXhIO port to query the 
underlying host.    Using the IO Port was very attractive since it 
seemed to require minimal dependencies, installation and configuring  
and was typically on by default

According to
https://sites.google.com/site/chitchatvmback/backdoor#cmd0fh

command 13h will provide the bios UUID but then I realized that VMWare 
allows multiple instances of a particular guest image as long as they 
run on physically distinct hosts.  It seems I really need to be asking 
for the/HOST's/UUID

The PowerCLI does seem to provide that data with the Get-VMHost command

https://www.vmware.com/support/developer/PowerCLI/PowerCLI41U1/html/Get-VMHost.html

something like

(Get-VMHost -Name MY_VCENTER_IP).ExtensionData.hardware.systeminfo.uuid

Is therea IOPort way to get the same or equivalent value - the physical 
host UUID?

  I just need a stable and robust way to identify what (physical) 
machine the app is running on.   Ideally, one which is simple to 
implement and does not have a lot of dependencies or configuration for 
the customer to deal with.


thanks
Karl Meissner