RethinkDNS: issues and questions

Hi !

I use NextDNS configuration, but I want to use the firewall of RethinkDNS…
How it works ?
Someone can be explain me how it works ?

Because sometimes I don’t have any Internet access with firewall…


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Hi there, rdns dev here

You can setup DoH (DNS-over-HTTPS) url (looks like:<cfgid>) by clicking on the + (add) button at the bottom of the DNSConfigure tab → Other DNS.

When you don’t have Internet, you can check Network logs and DNS logs to see if things are blocked. Blocked connections are marked with a red-coloured left-hand side border. When you tap on the entry, a bottom-sheet should crop up which should then show the reason (in a red-coloured chip on the top-right) explaining why Rethink blocked it.

If Rethink’s having connectivity issues, it should show up in red-colour on the homescreen just below the START / STOP button. If there are no network issues, then it should show Protected in a blue-ish colour instead.

Also, run Rethink in IPv4 mode (SettingsChoose IP versionIPv4) as IPv6 support is experimental and may not properly work on all 4G networks (we are working on a fix for this which should land in the upcoming version v054, 2 or so weeks away).

If everything looks good, see if connecting over System DNS (DNSConfigure (tab) → System DNS) works for you? Some network providers are fussy and block alternative DNSes.

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thanks for all !!

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ANDROID is blocked. Tap on it, then unblock it (by allowing it for both Mobile and WiFi). You’re possibly using NextDNS with Android’s Private DNS, and hence you need to allow ANDROID to connect (which here appears to be blocked) as ANDROID is the one making those DNS queries.

Also make sure to turn off Block when DNS is bypassed setting in FirewallUniversal (tab) (this setting isn’t shown when Private DNS is enabled; so you may have to turn off Private DNS first, make sure this setting in Rethink is also turned off; and then re-enable Private DNS again).

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Hi !

there is my screen capture of firewall rules.
It’s OK ?

(i’m french)

my first post for this app :sunny:


@ignoramous ?

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Thanks for the ping Licaon_Kter.

Answered it on reddit as it was asked there too:

Reproducing it here for others,

Hi: To add to what U8dcN7vx said,

  1. Bloquer lorsque le DNS is likely to break some apps… so check network logs when that happens.
  2. With Bloquer ... l'appareil est verrouille… but some communication apps (like Zoom, WhatsApp) may need a “bypass”, or incoming calls may be blocked, otherwise.
  3. Bloquer le traffic du port 80 may break some websites… but nothing major. Most legit websites today do support HTTP/S on port 443.
  4. Bloquer... nouvellement installees comes really handy. You’ll be shown a notification to allow / block when a newly installed app tries to connect to the Internet.
  5. Bloquer ... dont la source est inconnue is probably safe to enable. It shouldn’t break any app.

Hi everybody here !

Why RethinkDNS stop itself and lost all my firewall rules established in the past ? I have a redmi note 8 pro. And no other. Mr number filtered my phone call and SMS. I dont understand. When I save the app stop. I use DNS from nextdns pro plan.


Please report directly to the developer: Issues · celzero/rethink-app · GitHub


If you want Rethink to keep running persistently, enable Always-on VPN: Connect to a virtual private network (VPN) on Android - Android Help

Unless you reinstall Rethink, it shouldn’t be losing data… Does it happen all the time? If so, how many rules did you add that were wiped out? This sounds like serious bug… If you can reproduce it consistently…

As in, SMS and calls don’t work with Rethink?

  • For SMS/MMS, check Rethink’s DNS Logs to see if “RCS” related domains are being blocked.
  • For voice, yes, some providers (I have seen two or three such reports on T-Mobile) have problems with VoWiFi and VoLTE when Rethink is running.

But as Liacon-Kter mentioned, feel free to reach out on GitHub or Telegram, where the community is pretty responsive and multi-lingual.

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Thanks a lot.

And for “block all connexions without VPN” ?

You can enable it, if you don’t have any app “excluded” from Rethink (I can see from the screenshot you shared that there are 9 apps “exclue(s)”).

Basically, what “bloquer les all connexions…” does is, it firewalls (blocks connections of) any app or system component excluded from Rethink.

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Hi !

I am in fly mode… Or flight mode…
Why this ?


Flight mode only disables the radio for phone calls, not wifi or bluetooth.


Okey but why my RethinkDNS version stopped working… ?

Try enabling the Always-on VPN setting.

Either the app is crashing on your phone (in which case, can you please bugreport to mz at celzero dot com if you are comfortable doing so), or the Phone is killing the VPN (in which case Always-on VPN should help)?

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The same problem.

As in the app is crashing? Are you on Android 13? If so, wait for v054a to hit F-Droid within next week.

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