OS X Mountain Lion: The Missing Manual

Signing In, Logging Out

Once somebody has set up your account, here’s what it’s like getting into, and out of, an OS X machine. (For the purposes of this discussion, “you” are no longer the administrator—you’re one of the students, employees, or family members for whom an account has been set up.)

POWER USERS’ CLINIC: The Firmware Password Utility

After all this discussion of security and passwords, it may come as a bit of a shock to learn that enterprising villains can bypass all of OS X’s security features in 10 seconds. If you haven’t turned on FileVault, their nefarious options include using the Unix console described in Appendix B, single-user mode, FireWire disk mode, and so on.

But there is one way to secure your Mac completely: by turning on the very secret, little-known firmware password.

To find it, restart your Mac while pressing ⌘-R. That starts up Mountain Lion’s Recovery console (The Recovery HD).

Once you’ve chosen your language, choose Utilities→Firmware Password Utility.

When you run this utility, enter an administrator’s password. Now turn on “Require password to change firmware settings,” as shown here. Then make up a password—your firmware password—that will be required to start up from anything but the internal drive.

Next, you’re asked for an administrator’s password. Finally, a message tells you, “The settings were successfully saved.” Restart the Mac.

From now on, ...