Per ITS policy, all Macs on SU's network should have a firewall enabled.  You can enable it using the following instructions:

1. Go to the  menu in the top left corner of your screen > System Preferences
   
   
2. In System Preferences, select Security & Privacy
   
   
3. Select the "Firewall" tab
   
   

4. If you Firewall is off, click the button that says "Turn On Firewall"

   Make sure the screen says it is unlocked for changes.  If not, click on the lock icon in the bottom left corner of the window to unlock the settings. You will be prompted to enter the administrator password for the computer.

5. If the Firewall has been turned on, you will see a green light and the wording Firewall: On
   
   
6. Click on the lock icon to lock down the settings