macOS comes with a built-in firewall that is designed to prevent unauthorised programs and services from accepting incoming network connections. Strangely, unlike Windows, Apple disables this firewall by default on new Macs, leaving it up to the user to enable it for extra security.
How to Turn on the macOS Firewall
Turning the firewall on takes only a few clicks in System Settings:
- Click the Apple menu icon () in the top-left corner of your screen.
- Select System Settings from the dropdown menu (or System Preferences on older versions of macOS).
- In the left sidebar, click on Network.
- Click on Firewall in the main window.
- Toggle the switch next to Firewall so that it turns green (enabled).
Configuring Firewall Options
Once enabled, you can click the Options button to customise how the firewall behaves. Here you will find a few important settings:
- Block all incoming connections: Enabling this will prevent all sharing services (like screen sharing and file sharing) from working. It is highly secure but limits functionality.
- Automatically allow built-in software to receive incoming connections: This allows Apple-signed software to connect through the firewall without asking for permission.
- Stealth Mode: This prevents your Mac from responding to ping requests or connection attempts from closed networks, making your computer practically invisible on public Wi-Fi networks. This is highly recommended for laptops.