As noted earlier, the very first step is to secure Open Firmware. This is done by booting the machine and holding down the OPTION O F keys. The command line interface appears:
Apple PowerMac3, 5 4.2.3f1 BootROM built on 08/01/01 at 11:14:42
All Rights Reserved
Welcome to open firmware. The system time and date is 15:03:42 12/3/02
To continue booting, type “mac-boot” and press return.
To shut down, type “shutdown” and press return.
Release keys to continue!
Now, set the password:
Enter a new password: ******
Enter password again: ******
Password will be in place after next boot! ok
The commands you type are shown in bold.
Find a way to remember this password!
Finally, set the security mode level:
0 >setenv security-mode command ok
Then reboot the machine:
0 >reset-all ok
Open Firmware is now secured.