if running a Virtual Machine on my Server in an external data center, is it possible to secure it in such a way that not even physical access could be a security leak? E.g. the administrator cannot access my VM?
Thanks, heinrich!
You can encrypt its (virtual) hard disc and lock the console down (NB: it won't boot-up without a password entered), but you can't stop the host machine admin obtaining the contents of memory (or indeed the password, as they can log the virtual keyboard if they want).
If someone gets access to the VM host, all bets are off.
No matter what you do inside the VM, it's the host that is emulating it - and if the operator in question has root on the host, they can either undo any changes you make or interact with the process/memory directly.
It's just not possible
No way.
You can keep the server in our house if the data is very sensitive. The cost of doing this is affordable nowadays.