I don't trust that my machines are not compromised. All I can do is to start with a machine I believe to be "clean", and take measures to keep it that way (oth

I don't trust that my machines are not compromised. All I can do is to start with a machine I believe to be "clean", and take measures to keep it that way (others have suggested suitable measures). But even a brand-new machine might have a compromised BIOS, or compromised firmware in some peripheral processor like the Wifi adaptor. I don't know how to guarantee that a machine is "clean" to begin with, and I doubt anyone else does.