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guardianproject / orbot

The Github home of Orbot: Tor on Android (Also available on gitlab!)
https://gitlab.com/guardianproject/orbot
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[BUG] No network available for apps relying on VPN to use tor #1144

Open pmaziere opened 1 month ago

pmaziere commented 1 month ago

Describe the Bug Apps relying on VPN to use Tor do not resolve domain names, hence they think they do not have network connectivity. Apps allowing to define a proxy url and port to use Tor, such as F-droid, works flawlessly.

To Reproduce Steps to reproduce the behavior:

  1. install and run orbot
  2. install app that does not offer UI to define a proxy, ie Breezy Wheather 5.2.3_freenet from F-droid repository
  3. add the app to the applications handled by orbot
  4. launch the app and add a location
  5. get a "no network available" type of message

If it is of any relevance, this behavior still occurs after a reboot.

Expected Behavior App handled by orbot resolves domain name and has access to the network.

What Custom Configuration Do You Use? none

Smartphone (please complete the following information):

Thanks for taking the time to look into this issue.

graphener commented 3 weeks ago

@pmaziere Same thing on GrapheneOS. They suspect that this is an Orbot issue. It seems like fast Tor circuits, when one stumbles upon one of them at random (maybe 5% of the time) can work fine as a VPN. Other 95% of the time Orbot effectively disables DNS. I conclude from this that there is a constant timeout somewhere which just gives up on DNS resolution (which by default would occur at the exit node) if it takes too long.

The previous Orbot worked maybe 20% of the time (1 in 5 random circuits), which was at least better than 5%.

If you're using a proxy URL for Tor then maybe it's working because DNS is resolved outside of Tor and therefore won't usually time out. Not great from a security perspective but it adds weight to the timeout theory.

graphener commented 3 weeks ago

https://github.com/GrapheneOS/os-issue-tracker/issues/3615