Change Firewall preferences on Mac
Use the Firewall pane of Security & Privacy preferences to turn on the firewall in macOS to prevent unwanted connections from the internet or other networks.
To open this pane on your Mac, choose Apple menu 
> System Preferences, click Security & Privacy, then click Firewall.
Option | Description |
|---|---|
Turn On Firewall | If the firewall is turned off, click Turn On Firewall to turn on firewall protection. |
Firewall Options | Click the Firewall Options button to change firewall settings. |
Block all incoming connections | In Firewall Options, select to prevent incoming connections to non-essential services and apps. Basic internet services are a set of apps that allow your Mac to find services provided by other computers on the network. This setting prevents connections to all other sharing services. |
Add | In Firewall Options, to add an app or service, click the Add button |
Remove | In Firewall Options, to remove an app, select it in the list, then click the Remove button |
Automatically allow built-in software to receive incoming connections | In Firewall Options, select to allow built-in apps and services that are signed by a valid certificate authority to be automatically added to the list of allowed apps, without your authorisation. |
Automatically allow downloaded signed software to receive incoming connections | In Firewall Options, select to allow downloaded apps and services that are signed by a valid certificate authority to be automatically added to the list of allowed apps, without your authorisation. |
Enable stealth mode | In Firewall Options, select to prevent your Mac from responding to probing requests that can be used to reveal its existence. The Mac still answers requests from authorised apps, but unauthorised requests such as ICMP (ping) get no response. |
Lock | Locks or unlocks Security & Privacy preferences. Click the lock icon |
Advanced | Click to increase the security on your Mac by adjusting specific settings in the Change Advanced preferences. |
to unlock it, then enter an administrator name and password.Certain shared services can connect through the firewall when they are turned on in Sharing preferences. For additional security, you can prevent connections to these incoming services by turning off the service in Sharing preferences. See Share your Mac screen, files and services with other users on your network.