1. On your MAC, click the Apple Icon in the upper left corner of your screen > System Preferences > Security & Privacy > Click the Firewall tab at the top
2. If the lock icon at the bottom left is locked, click it to unlock it
3. Click the 'Turn On Firewall' button to turn firewall on
4. To specify additional security settings, click "Firewall Options".
- Allow only specified app's and services to connect: Click the Add button, then select the app or service in the dialog that appears.
- Allow only essential apps and services to connect: Select the "Block all incoming connections" checkbox.
- Automatically allow built-in software to receive incoming connections: Select the "Automatically allow built-in software to receive incoming connections" checkbox
- Automatically allow downloaded signed software to receive incoming connections: Select the "Automatically allow downloaded signed software to receive incoming connections" checkbox.
- Enable stealth mode to make it more difficult for hackers and malware to find your Mac: Select "Enable stealth mode."
