Turn on the application firewall in OS X:
- Choose System Preferences from the Apple menu.
![Apple Menu and System Preferences Apple Menu and System Preferences](https://its.uiowa.edu/sites/its.uiowa.edu/files/wysiwyg_uploads/Screen%20Shot%202017-08-15%20at%2010.56.15%20AM.png)
- Click Security or Security & Privacy.
![Security and Privacy Icon Security and Privacy Icon](https://its.uiowa.edu/sites/its.uiowa.edu/files/wysiwyg_uploads/Screen%20Shot%202017-08-15%20at%2010.56.38%20AM.png)
- Click the Firewall tab.
![Security and Privacy Window Security and Privacy Window](https://its.uiowa.edu/sites/its.uiowa.edu/files/wysiwyg_uploads/Screen%20Shot%202017-08-15%20at%2010.56.53%20AM2.png)
- Unlock the pane by clicking the lock in the lower-left corner and enter the administrator username and password.
![Lock Icon Lock Icon](https://its.uiowa.edu/sites/its.uiowa.edu/files/wysiwyg_uploads/Screen%20Shot%202017-08-15%20at%2010.56.53%20AM.png)
- Click "Turn On Firewall" or "Start" to enable the firewall.
- Click Advanced to customize the firewall configuration.