I need to create an isolated setup, without knowing too much about how that might be achieved by other more technical means.
This setup never goes online (the wireless adapter is unplugged) and file transfer to and from here is very rare (except during the initial installation of the programs I plan to use and I will probably use a drive or USB stick for that. Also I'd want to keep the OS and apps up to date, but how?
So I purchased a machine pre-installed with Ubuntu Desktop 15.04 and I want to enable it to separately run (dual boot?) (Ubuntu Desktop 15.04) from an external encrypted hard drive, as a way to achieve my goal of an isolated system.
More or less, I think it would look like this:
I'd unplug my wireless adapter, restart the machine, be asked if I want to boot from the external (eSATA?) drive (attached for this purpose only, otherwise not attached) and be prompted for the encryption password (separate from the Ubuntu password) which would mount the encrypted file to access the (Ubuntu Desktop 15.04) operating system files, run those files and I'd be greeted with the request for my Ubuntu password for this isolated system.