NetBarrier contains a powerful network firewall that allows you to protect your Mac from outside threats by preventing other devices from communicating with your Mac. All of the default profiles that come with NetBarrier block all incoming connections from the Internet.
This is a good thing for the most part, however, it can prevent some applications from functioning. This is often the case with software that allows you to remotely control your computer for instance. Obviously, for that software to operate you must be able to connect with your computer remotely and that means sending requests to it from over the network.
You do this by telling the firewall what applications you would like to allow to pass through the firewall, and you do that by identifying “ports” for applications that are safe. Knowing what ports require exceptions is application specific, and can usually be found by executing a network search with the name of the application you want to use and “port.” However, because NetBarrier also watches for applications attempting to access the network we can make this easier for you by showing you the applications that are actively listening for network connections and what “ports” they are listening on.
In NetBarrier, you add a port exception to either the incoming or outgoing Internet channel by clicking on the “gear” configuration icon.
To open the ports associated with an active application, select the option to show applications. You will see a list of applications that are actively listening for requests from the network. You can click the "+" next to an application to add all of the ports that it is actively listening on to the list of exceptions.
You can also expand the application and selectively add ports from this list.
This is a simple mechanism to help you identify what ports an application might require. It is not active, meaning that if the application opens up a port at some point in the future, the new port will not automatically be added to the list of exceptions. Doing so would potentially be a security exposure. Most applications that require these exceptions tend to begin listening on the network as soon as they are started, and this should make the process of adding exceptions for specific software quite simple.
To manually add a port number maybe because the application you want to provide an exception for is not currently running, press the +/- button at the bottom of the list to add a new entry and type the port number into the new entry.
Remove an exception(s) by selecting one or more rows and pressing the “-“ button.