Another thing that doesn’t work anymore after blocking network traffic from my Android phone: Some push notifications.

I run a Matrix server for our family. I use “FluffyChat” on my phone. Traffic from the phone to my Matrix server is allowed and chatting in FluffyChat works.

But I don’t get any notifications anymore on new messages.

So, what’s going on here? Does FluffyChat, which only really needs to talk to my own server, rely on some cloud service for notifications? Seriously? 🤔 How does that work, does this cloud service see all my notifications or what?

Anyone around who did app development on Android? Can you shed some light on this?

@movq@www.uninformativ.de can’t Ntfy help with that? That’s how I get my signal notifications (I think).

This guide may me of help…
Good luck!

@movq@www.uninformativ.de I’m personally using the android app as is. Didn’t set up my own notifications server, the default one works just fine I guess.

@movq@www.uninformativ.de I haven’t done any app development, but I know notifications on phones are indeed dependent on cloud services run by the OS vendor which talk to servers run by the app vendor on your behalf. This is supposedly better on battery life, but it conveniently lets your OS vendor read all your notifications.

Mobile XMPP clients usually implement notifications using XEP-0537 and it goes like this:

Your XMPP server -> Client vendor's notification server -> Client OS notification server -> User's device

It’s not end-to-end encrypted so servers will usually just send a dummy message through (You received a message from juliet@capulet.lit!) so you have to open the app to see the (hopefully) encrypted message.
It’s a similar flow on both iOS and Android and I assume Matrix clients work the same way.

It looks like ntfy.sh can work either through the OS’s notification service or by maintaining its own connection to the server in the background. For privacy, you definitely want to use “Instant Delivery” and self-host the server.

https://docs.ntfy.sh/faq/#how-much-battery-does-the-android-app-use
https://docs.ntfy.sh/faq/#what-is-instant-delivery

Actually, it looks like notifications using Google’s service can be encrypted end-to-end. I don’t know if this is used much in practice or if you can tell if the notifications on your device are encrypted. There seems to be some conflicting information out there.

Even if the content is encrypted, though, you’re still giving quite a bit of metadata to Google by using their notification service.

@movq@www.uninformativ.de People just don’t ask these questions. It’s really a serious privacy issue, and I don’t see it brought up very often. Not even in privacy-minded circles. If you’re using a proprietary operating system on any Internet-connected device, you need to assume that the vendor can see everything you do on it and maybe even what you do on other devices as well..