The best firewalls for your Mac

One of the most important tools in your online security arsenal is a firewall. Firewalls block incoming and outgoing network connections and can often be configured to be as strict or as relaxed as you like. You can also usually configure a firewall to prevent your Mac from being “pinged” – where a piece of data is sent to it over the network to check if it’s “there.” 

Firewalls can be software or hardware, though most these days are software. macOS has its built-in firewall that can be configured in System Settings > Network > Firewall, and your broadband router probably has one, too. Your router’s firewall, if it has one, can be turned on and off in the settings webpage for the router.

Tip
Want to know how to turn on the firewall on your Mac? Just go to System Settings > Network > Firewall and turn it on.

To tighten the built-in firewall, click Options in the same pane. Enable stealth mode stops your Mac from responding to probing requests that could reveal it on a network, and Block all incoming connections stops incoming connections to nonessential services and apps, which makes sense on public or untrusted Wi-Fi. 

On a work Mac, don't change firewall settings or install a third-party firewall without your IT team's approval.

Why download another Mac firewall?

If your Mac already has a firewall built-in, why would you consider a third-party version? Well, for one thing, the macOS firewall only blocks incoming connections; it doesn’t protect you from security threats that come from outbound traffic. Though there are advanced options tucked away, it’s not as configurable as some third-party firewalls.

Did you know?

In addition to a firewall, it’s a good idea to use an antimalware tool to scan your Mac regularly and keep it safe. CleanMyMac does just that. It scans your Mac for malware and neutralizes the threats it finds. Get your free CleanMyMac trial.

The best firewalls for your Mac

How we chose these apps: each one controls network connections in ways the built-in firewall doesn't, and each is still offered by its developer. We didn't run lab tests; the descriptions below are based on each developer's documentation.

Little Snitch

Little Snitch has been around for almost as long as macOS. Its goal is to block apps from making outgoing network connections unless you explicitly choose to allow it. This is useful for a couple of reasons:

1. It stops apps from contacting a server and sending data about you to it.

2. It alerts you to software that shouldn't be on your Mac, i.e., malware, and is trying to connect to a host server.

Source: Objective Development

When an app initiates a connection to a server, Little Snitch alerts you and offers you the opportunity to allow it to connect or to prevent it. It learns from your decisions and creates rules based on them. Notably, there’s a silent mode that hides alerts so that you’re not bombarded with them – there are a lot of them at first. You can then come back to alerts later to make decisions and create rules.

Lulu

We mentioned earlier that the macOS firewall is good at blocking incoming connections. Lulu complements that by blocking outgoing connections, similarly to Little Snitch. When an app tries to make a new outgoing connection, LuLu alerts you and asks whether to allow or block it. If you decide to allow an app or service to connect, every attempt made by that app or service will be allowed. Lulu’s source code is published on GitHub so anyone can inspect it.

Radio Silence

Radio Silence is the simplest and most elegant of the firewalls available for macOS. There’s nothing to configure and no pop-up windows to distract you. One small window is its only user interface element. That window is split into two tabs. 

Source: radiosilenceapp.com

One, titled Network Monitor, displays all the apps that have open network connections. Next to the app is a number showing you how many open connections it has. Click on that number, and you can see a list of connections.

You may be surprised at just how many network connections some apps make. And next to that number is a Block button, allowing you to prevent the app from making connections. Press that button, and the app shows up in the other tab, Firewall. That tab lists all the apps you’ve blocked from making connections. It’s a very simple but effective tool that has won praise and rave reviews from some of the most well-known Mac blogs and websites.

Murus Pro

Murus Pro consists of two apps, Murus and Vallum. The former will perfectly complement the macOS built-in firewall by providing an interface that allows you to create rules for incoming connections. The latter, Vallum, is similar to Little Snitch and Radio Silence – it allows you to monitor and block connections that apps make, both incoming and outgoing. 

Murus allows you to drag and drop elements to create sets of rules from pre-created presets. Or you can rewrite your own rules from scratch. If what you want is to fine-tune the built-in macOS firewall, Murus could be the ideal tool.

Source: murusfirewall.com 

Vallum monitors and intercepts incoming and outgoing connections by apps and lets you block them. It sits in the menu bar until you decide to configure it. When you do, like Murus Pro, you can do it by dragging and dropping. For example, to prevent an app from making outgoing connections, you just drag it from the Finder onto the Vallum window. You can modify the firewall rules for each app manually, or use one of the predefined presets. 

There are several very good firewall tools available for Macs. Some complement Mac’s built-in firewall and block incoming connections; others are focused on outgoing connections. Whichever you choose, it’s also a good idea to use an additional security and Mac maintenance tool like CleanMyMac.