Using MarcoPolo to Lock Down Your Mac When Connected to a Public WiFi Network

On my PowerBook I run quite a few sharing services, things like Web Sharing, Bonjour for file sharing and Screen Sharing. But the thing is, I only need these services running when I am at home; I’d rather not “publish” theses services when I am surfing at my local Internet cafe.

I’d also like to enable some sort of password protection for when I walk away from my PowerBook momentarily.

Enter MarcoPolo

MarcoPolo lets you switch your Mac between locations; Which it can do automatically or you can manually switch it. This means that when I am at home, I can switch to my “Home” location profile have any password protection disabled and all my services flipped on. When I am at a cafe, I can switch to my “Public” profile I can enable a screensaver password protection and have all my services flipped off.

MarcoPolo Switching Locations

Rules enable automatic switching between locations.

MarcoPolo Rules


The only problem I found with MarcoPolo was the poor help documentation and poor verbage within the app itself. So, here is…

How to use MarcoPolo to enable a screensaver password

Once downloaded and installed, click the compass icon on the menu bar and select “Preferences…”.

1. Click the context tab and then the plus symbol and add a profile named “Public”.

2. Click the actions tab, then the plus symbol and select “Add ScreenSaver Password Action…” and enter info as below:
MarcoPolo ScreenSaver

3. You will now want to create another “Add ScreenSaver Password Action…”, but with the context set to “Automatic” that is set to disable the screensaver password so you don’t have the password prompt when at home.

That’s it. Now when you flip to your “Public” location there will be a password that flips on when your screensaver kicks in.


There are actually quite a few actions your Mac can take, based on your location:

  • Setting your default printer
  • Changing your desktop background
  • Enable or disable particular firewall rules
  • Setting iChat status message
  • Setting the default IMAP or SMTP server for Mail.app
  • Mounting network shares (smb://, afp://, etc.)
  • Muting or Unmuting system audio
  • Changing OS X network location
  • Opening a file (an application, a document, etc.)
  • Quit an application
  • Enabling or disabling screen saver password
  • Start/stop screen saver
  • Changing screen saver idle timeout
  • Running a shell script (or any other kind of script, via Platypus)
  • Turning on or off Bluetooth
  • Turning on or off WiFi (AirPort)
  • Establish or disconnect VPN

You can also set you Mac to automatically switch between locations automatically based on quite a few rules

  • Visible WiFi networks
  • Current Audio Output device (headphones/internal speakers)
  • Discoverable Bluetooth devices
  • Advertised Bonjour (Zeroconf) services
  • Attached FireWire devices
  • Assigned IP addresses
  • Ambient Light level
  • Attached Monitors
  • Active Network Links
  • Power source (power adapter/battery)
  • Running Applications
  • Current Time Of Day
  • Attached USB devices

You can even run AppleScript or shell script actions when switching between locations…

Very cool!