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by ignoramous 678 days ago
ex-AOSP and rethink dns+firewall dev here

> Sadly all real firewalls need root

What do you mean by a "real" firewall? It is very much possible to build a userspace firewall in Android using the VPN APIs.

On Android, ROMs like GrapheneOS, Lineage, and CalyxOS have firewalls built-in.

> Glasswire has an Android version

Note though, Glasswire was recently acquired by another company: https://archive.is/KW2R3
2 comments
yndoendo 678 days ago
I thought parts of the Android OS can by-pass the VPN so the firewall becomes ineffective against blocking Google, OEMs, and others that have root. Wouldn't the VPN API being used as a firewall also prevent one to use a VPN client at the same time?
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khimaros 677 days ago
for the latter, Rethink can be configured to work with eg. a wireguard VPN because it has a built-in wireguard client.
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Joe_Cool 678 days ago
> Note though, Glasswire was recently acquired by another company

Ah that's why the premium stuff is now free. I was wondering. Let's hope it's not the first sign of enshittification.

> What do you mean by a "real" firewall?

In my experience the "block all non VPN traffic" options in Android don't work reliably. iptables does however.

It's a sad state that you cannot even set a static IPv6 on Android without root.

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ignoramous 677 days ago
> In my experience the "block all non VPN traffic" options in Android don't work reliably. iptables does however.

Both (iptables/nftables and VPN APIs) have to be enforced by the Linux Kernel, which is subject to the same "Androidisms", if that makes sense.

root, in fact, opens up a gaping hole in that, it totally compromises Android's security model. IMO, it isn't worth to root Android just to run iptables (just because it seems like iptables is what makes a firewall).

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Joe_Cool 676 days ago
IMHO Android's security model is incredibly flawed anyways. I don't even need root to access stuff I shouldn't have access to on my Mediatek based phone because the firmware has tons of gaping security holes anyways.

I think device you don't have root on isn't really yours and should be treated as a lease.

But you are right, when Wifi/Data is on at boot even the -tables might not get updated fast enough so stuff might get through.

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