How to Turn On the Firewall on a Mac

A firewall is a crucial security barrier that monitors and controls the incoming and outgoing network traffic on your computer. It acts as a digital bouncer, aggressively blocking malicious probes, unauthorized connection attempts, and hackers trying to access your system from the internet.

Surprisingly, Apple disables the built-in macOS Application Firewall by default on new computers. While this makes connecting to local printers and setting up file sharing slightly easier for beginners, it leaves your Mac exposed when connecting to untrusted public Wi-Fi networks in airports or coffee shops. Enabling the firewall takes only a few clicks and operates silently in the background.

How to Enable the Firewall

The process for managing your firewall is located within the main System Settings application.

1. Click the Apple Logo in the top-left corner of the menu bar.
2. Select System Settings (or System Preferences on macOS Monterey and earlier).
3. Scroll down the left-hand sidebar and click on Network.
4. In the main panel, click on Firewall.
5. Toggle the switch next to Firewall to the ON position. (If you are using an older version of macOS, you may need to click the padlock icon in the bottom-left corner and enter your administrator password before you can click the “Turn On Firewall” button).

The status indicator will instantly turn green, indicating that your Mac is now actively blocking unauthorized incoming connections.

Configuring Advanced Firewall Settings

For the vast majority of users, the default settings are perfectly adequate. However, if you are highly security-conscious or if you find that a specific application (like a multiplayer game or a local media server) has suddenly stopped working, you can adjust the firewall’s strictness.

1. On the same Firewall settings page, click the Options… button.

A new menu will appear offering several key features:

• Block all incoming connections: Enabling this is the “nuclear option.” It will block absolutely everything except essential core internet services (like basic web browsing and email). It will immediately break all local file sharing, screen sharing, and third-party messaging apps. Only enable this if you are on a highly suspicious public network and require maximum lockdown.
• Automatically allow built-in software to receive incoming connections: Leave this ticked. It ensures that Apple’s own apps (like FaceTime, Messages, and AirDrop) function without constantly asking for your permission.
• Automatically allow downloaded signed software to receive incoming connections: Leave this ticked. It allows legitimate, verified apps downloaded from the App Store or trusted developers to update and connect automatically.
• Stealth Mode: Ticking this box makes your Mac virtually invisible to automated network scanners and ping requests used by hackers to find vulnerable targets. It is highly recommended to turn this ON.

How to Allow a Blocked Application

If the firewall accidentally blocks a legitimate program, you can add an exception manually.

1. In the Firewall Options… menu, click the small plus (+) button under the application list.
2. The Applications folder will open. Select the specific app you want to unblock.
3. Click Open.
4. Ensure the setting next to the app in the list says “Allow incoming connections,” and click OK.