Outbound firewall applications come up many times in discussions about privacy as this is one way to monitor and prevent the apps you use from phoning home.
Privacy Guides does not have any recommendation regarding outbound firewalls. I’d like to know your/everyone’s opinion about these kind of firewall apps. Do you find them useful? Do they deserve a section/mention on PG’s recommendations? Do you use something else to achieve similar effect, like DNS filtering? Maybe you use both?
The section could also be more general or merge into the section about DNS, I cannot come up with a good name, maybe you can, but like about How to monitor and control/filter the outgoing connections of apps on all platforms, desktop and mobile. And then include outbound firewall apps as one sub topic. What do you think?
Desktop (macOS/Windows/Linux)
In no particular order, here are some outbound firewall apps for desktop.
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Little Snitch (macOS, closed source)
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OpenSnitch (Linux, open source version of Little Snitch)
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Lulu (macOS, open source)
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Portmaster (Windows, Linux, open source)
iOS and iPadOS
If I’m correct, Apple does not allow the development of these kind of apps on iOS/iPadOS, so the only way to achieve something similar (block outgoing connections) is via DNS filtering and if you use an app for that, it requires a VPN slot and then leaves you unable to use a VPN on that device unless both the DNS and VPN are included within the same app. If you do manage to use both custom DNS and VPN somehow, you will get dns leaks if the DNS is different from the VPN’s default, so there is that to take into consideration.
Android
I am not sure what’s the situation on Android. If I’m correct there is a firewall app called NetGuard that can block apps accessing the internet, but it is only the access to internet right? You cannot pick and choose which domains are allowed and disallowed. Maybe someone here who knows better about Android can tell us?
