The login screen of OS X defaults to showing the account pictures and user names of all accounts on the given Mac. This is undoubtedly convenient for most users as it makes logging into accounts much faster, but for situations where a Mac requires higher security, users may wish to hide user account names from the login window, thereby requiring a complete authentication of both a username and password.



The reason this is more secure is fairly simple: not only would an unscrupulous individual have to know or guess the password for a user account, but now they would also have to know or guess the username for the account too. By hiding the user accounts from the login screens, there are no hints offered as to what user accounts are on the Mac, and a proper username must be known in addition to the appropriate password, offering a layer of privacy and obscurity to help protect the Mac.

How to Hide User Names from Mac Login Windows

Requiring the full user authentication at any Mac login screen in OS X is easy, here’s how to enable this feature:

Open System Preferences from the  Apple menu and choose “Users & Groups” Click on “Login Options” in the lower left corner, then click the lock icon to authenticate with an admin user to be able to make adjustments If it hasn’t be done already, set “Automatic Login” to OFF* Set “Display login window as:” to ‘Name and password’ Close out of System Preferences

You can now log out, reboot, or lock the Macs screen to test the change yourself. The login window will appear as usual, but there will no longer be a list of users and accounts shown, instead a basic prompt for a complete username and password is necessary to login to the Mac.

All user accounts on the Mac will continue to work as usual, including a guest account, but the proper username for each account must be entered properly. Note that full user names or short usernames work for this purpose.

Of course, this is no replacement for using a secure password and securing a Mac in general with things like FileVault and boot passwords, but it’s an added security trick that can help to add another level of security to Macs. This can be particularly important in public computers and work machines, though it would obviously still have security benefits for more typical portable and home situations too.

* You’ll need Automatic Login turned off for this to work, otherwise a Mac that has been rebooted, locked, or logged back in will simply boot into the desktop without prompting for a user login anyway.