MacSentry is an easy to use password protection utility that prevents unwanted users from gaining access to your computer. It works by hiding the desktop and all other applications and presenting a dialog box on the screen that requires a valid password to be entered before access is returned.
The Interface
MacSentry’s interface is very simple. It consists mainly of a single window that has a password field and various buttons:
 
When MacSentry is active, a user must enter the currently set password into the password field and click the OK button. This will dismiss the window and return control of the computer to the user. If an incorrect password is entered, MacSentry will beep and refuse access. The following is an item-by-item list of the interface elements in MacSentry:
The password field:
 
This editable text field is where the user enters his or her current password to regain access to the computer. It is also where the desired password is entered when setting or changing the current password (more on this later).
The OK and Shut Down buttons:
 
The OK button is the button used to dismiss the MacSentry dialog when the correct password has been entered into the password field.
The Shut Down button (available only when MacSentry is launched at startup) is used to simply shut the computer down. This is useful if someone tries to access your computer by starting it up without your knowledge. If MacSentry is set as a Startup Item (see below), it will launch and the user will not be able to access your computer. Rather than simply turning the power off and potentially damaging your computer, the Shut Down button offers a safer alternative.
The lock button:
 
The lock button is used to set or change MacSentry’s password. To use, first enter the current password in the password field and then click the lock button. If the correct password was entered, MacSentry’s window will change to the Set Password dialog.
Setting The Password
To set MacSentry’s password, enter your current password into the password field and click the lock button. This presents the Set Password dialog:
 
Note that the lock button now depicts an open lock. This is to notify you that MacSentry is now in an unlocked or unsafe state. (The large icon also changes to a caution icon as a warning.) Do not leave your computer unattended in this state as a user can easily change the password to whatever he or she wants and gain access to the computer.
Once MacSentry is unlocked, you can enter your desired password (up to 31 characters, case sensitive) into the password field and click the Save button to save your new password. After clicking Save, MacSentry will return to its normal locked state requiring the newly set password to be entered as usual.
To cancel the Set Password dialog and return to a locked state without changing the current password, simply click the lock button again.
 
Launching MacSentry At Startup
To have MacSentry launch at startup, simply place an alias of MacSentry in the Startup Items folder inside your system folder. The Startup Items folder looks like this:
 
To make an alias of MacSentry, hold the command and option keys down while dragging the MacSentry icon. The cursor will change to an alias cursor like so:
 
Drop the icon over the Startup Items folder and the System will place an alias of MacSentry in the folder so that MacSentry will launch each time your computer starts up. To stop MacSentry from launching at startup, simply remove the alias from the Startup Items folder.
Note: This method only works with Mac OS 8 and higher. To create an alias under any System version, select the MacSentry icon and choose “Make Alias” under the File menu. Then simply drag this icon onto the Startup Items folder.
Appearance Manager
MacSentry is also fully compatible with Mac OS 8’s Appearance Manager, which means you get a consistent user interface as well as the ability to switch themes. MacSentry currently requires Mac OS 8 or higher, but a future version may include support for previous systems.
