Radio Silence: Tom's Mac Software Pick

Monitor or Block Outgoing Connections Made by Mac Apps

Radio Silence Firewall displaying Network Monitor tab.
Screen shot courtesy of Coyote Moon, Inc.

Radio Silence by Juuso Salonen is an easy-to-use firewall for the Mac designed specifically to monitor and, if needed, block outgoing network connections made by your Mac and its many apps.

Unlike other outgoing firewall apps, Radio Silence uses a minimal, non-intrusive user interface that doesn’t try to get your attention with pop-ups or alerts every time an app opens or performs some new task.


  • Easy to use, no networking knowledge required.
  • Able to monitor outgoing network connections.
  • Can block any app from phoning home.
  • Easy to manage block list you create.


  • No menu bar entry for easy monitoring of the outgoing firewall.
  • The default is to allow outgoing connections unless they're on the block list.

Radio Silence is the easiest outgoing firewall app I have ever used with my Macs. You may be wondering why you need an outgoing firewall; surely the Mac has a firewall built in?

The answer to that question is yes, the Mac has a built-in firewall; actually, a very robust firewall that can prevent and control connections made to your Mac. It is, however, difficult to use, and its strength is in blocking incoming, not outgoing, connections.

Radio Silence specializes in monitoring and blocking connections various apps and services running on your Mac may try to make to a server somewhere on the Internet. This is commonly referred to as phoning home and has many legitimate uses, including checking if an app is properly licensed, checking for updates, or if a problem occurs, sending details about why the app crashed.

The problem is that some apps either send information you would rather not have the developer know about or are engaging in activities they never told you about. Radio Silence lets you prevent those connections by apps behaving badly.

Radio Silence and Security

Radio Silence works fundamentally differently from its major competitor, Little Snitch. Little Snitch uses a rule-based firewall that can turn connections on or off by connection type, port, and other criteria. Little Snitch also starts with the idea that all outgoing connections are blocked; you have to create rules to allow an app to punch its way through the firewall to make an outgoing connection. In many cases, a single app may need multiple rules before it's able to work correctly.

Radio Silence, on the other hand, uses a simple app and service block list. If an app or service is added to the block list, then no outgoing connection can be made. The key difference here is one of security. Little Snitch's default state is to block connections, while Radio Silence's default state is to allow connections.

Those interested in security as a primary reason to use an outgoing firewall will likely prefer Little Snitch. However, that security comes at a cost: the generally increased complexity required to set up and use Little Snitch, as well as the inconvenience of having alerts and pop-up warnings harassing you every time a connection not on your rule list is requested. 

Using Radio Silence

Radio Silence is a single-window app that can display either a list of blocked apps and services or a list of outgoing network connections that are being monitored. You can select which list you wish to display using a simple two-tab interface.

Adding Apps and Services to Be Blocked

As I mentioned, Radio Silence's default condition is to allow outgoing connections to be made. To prevent an app or service from making a connection, you need to add the item to Radio Silence’s block list. The process of adding an app or service to the block list is very easy.

You can add an app to the block list by selecting the Firewall tab, and then click the Block Application button. From there, a standard Finder-style window will open in the /Applications folder. Browse through the folder, select the app you wish to block, and click the Open button. The app will be added to the block list, and no outgoing connections can be made by that app.

You can also block services from making outgoing connections. The easiest way to shut down a service from connecting is to select the Network Monitor tab. Radio Silence monitors any outgoing network connection and maintains a list of those connections in the Network Monitor tab. In the list, you'll see any apps making a connection, as well as any service. Next to each item is a Block button; clicking the Block button adds the app or service to the block list.

Removing Blocked Items

Apps and services that you have added to the Radio Silence block list will appear in the Firewall tab. Each item listed can be removed by clicking the X next to its name. Managing the block list is about as easy as it gets.

Network Monitor

The Network Monitor tab displays all the apps and services that are making outgoing connections. I mentioned how you can use the list as an easy way to add an item to the block list, but you can also use the Network Monitor tab to find out more about the connections being made.

Besides the Block button associated with each item in the list, there's also a numbered badge. The number within the badge tells you how many times an app or service has made a connection. If you click on the number, you'll find a log of each connection made. The log gives you the time of day, the host to which the connection was made, and the port used for the connection. The log can be helpful if you're looking to find out what an app is up to, or which ports or hosts are being used.

One improvement I would like to see in the log is the ability to search the log and save the log. You can save the log by selecting all of the entries and copy/pasting it as text to an app, but a simple save function would be appreciated.

Final Thoughts

I’ve mentioned how other outgoing firewalls may be a better choice for the security-minded individual. But they also require a great deal more in setup, and the ability to put up with annoying alerts and pop-ups.

Radio Silence takes care of creating rules by simply blocking all activity an app or service generates. It also doesn't throw up alerts or produce pop-ups that require you to take action. In this respect, Radio Silence can prevent apps from phoning home, while not bothering you with the minutia about the connection attempts.

For those of you who are more interested in being productive on your Mac, and not tweaking firewall settings, Radio Silence provides a much easier way to block connections on selected apps and services.

Radio Silence is $9.00. A demo is available. There's also a 30-day, no-questions-asked money back guarantees.

See other software choices from Tom's Mac Software Picks.