Choose Apple menu > System Preferences, click Security, and then click Firewall. (If some settings are dimmed, click the lock icon and type an administrator name and password.) Choose option A to allow all programs. If you would prefer to restrict incoming connections, you can select Option C and add our program to the exceptions list. (see Steps 2-3 below)
To add an application, click Add (+), and then select the application in the dialog that appears. Example: Mac HD> Applications>PositScience>InSight.
To change whether to allow incoming connections on an application or service, click the up and down arrows next to the item on the list, and then choose a setting from the pop-up menu.