OS X Mountain Lion: Protect your Mac
Here are some things you can do to make your computer use more secure while you are connected to the Internet or a network.
Use secure passwords
Require users to log in
If others can get physical access to your computer, you should set it up with a separate user for each person using the Mac, and require each user to log in. This prevents an unauthorized person from using the computer. It also separates user files, so a user only has access to their own personal files and settings. Users cannot see or modify the files or settings belonging to other users.
Secure your computer when it’s idle
You should log out of your secured computer when you are done using it. You can also set it up to lock when it goes to sleep when it’s been inactive for a certain period of time. You should require a password to wake it from sleep. You can also set up your computer to lock the screen immediately whenever you want by setting up a hot corner.
Limit the number of administrative users
Administrators have powerful privileges on your Mac. They can create, manage, and delete other users, install and remove software, and change the Mac’s settings. For these reasons, an adminstrator should create a standard user to work in when administrator privileges are not needed. If the security of a standard user is compromised the potential harm is far more limited than if the user has administartor privileges. If multiple people use your computer, limit the number of users with administrator privileges.
Encrypt the data on your Mac with FileVault
If you have private or confidential information on your computer, you can use FileVault disk encryption to protect the files on your disk from being seen or copied. FileVault encodes the information stored on your disk so it is locked and cannot be read unless a password is entered.