Mac OS X is based on BSD Unix, so one way to crack Mac passwords is with Unix password-cracking tools. In particular, John the Ripper has a good reputation for being successful in cracking Mac OS X passwords. While this can be useful to systems administrators, it points out that password security can be broken fairly easily.
Even easier than downloading and installing password-cracking software is using a Mac OS installation disk to reset the administrator password. If this is an Xserve server, be sure to unlock the drive lock so you can mount the installation disk. Insert the install disk and click on the "Install Mac OS" icon.
Click the Reset button on the installation screen, and it will begin the installation process. Click through screens until you see the normal menu bar menus on your screen.
Click on the Utilities menu and choose "Reset Password." Follow the prompts to change the admin password. After resetting the password, choose Quit from the Installer menu. Remove the installation disk from the drive and restart. You should be able to log on as administrator using the new password you just set.
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