I once set up a Slackware-based recovery partition on a USB HDD, and configured it so I could SSH to the machine, as root, with no password. (Took a bit of doin

I once set up a Slackware-based recovery partition on a USB HDD, and configured it so I could SSH to the machine, as root, with no password. (Took a bit of doing, too. OpenSSH is well built.) This HDD was only ever used for recovery. Incidentally I only ever used it at home, on a LAN that only has devices I know about on it. In a work environment I'd only ever do the same running off an isolated lab switch. But in certain situations, "login to the box as root w/ no pw" is awesome for rapid bringup/diagnosis/repair/whatever.