Click the blue Apple icon in the upper left corner of the screen and choose System Preferences...
In System Preferences, click on the Sharing icon in the Internet & Network section.
In the Sharing window, click the Firewall tab.
If the status says Firewall Off, click the Start button.
Once the status changes to Firewall On, the firewall is enabled. From the Apple menu bar, click System Preferences and choose Quit System Preferences.

For further assistance, please contact the IT Services Help Desk at (414) 288-7799.