MacOS – How to protect Single User Mode to require a password

You want to set an Open Firmware Password. This makes it so that a thief needs a password to boot to another disk (or do anything other than a normal boot). This means that they can't reset your password from the OS disc and get in anyway. This is an important security measure to take. The only problem is that you can't do things like safe boots and verbose mode. Here is an article about how to set up the OF password (and how to reset a user password).

And here is a general article about physical and virtual options to increase security (ways to help locate a stolen Mac, make thieves think it's broken, or even just lock it to your desk).

The following article may help your problem. :)

Mac OS X: Require Password at Single User Mode:

By default, Mac OS X will simply give you a shell when you perform a Single User Mode startup. However, you can force OS X to ask for a password in order to gain shell access. To do so, vi the /etc/ttys and change secure to insecure. Once you have done so, create a password in /etc/master.passwd for root.