When usb-tethering blocks connections from tethered computer to the phone

[xandro0777]

Hi, I like to connect my phone by USB to use the tethered internet connection. On the phone I have sshd running and want to connect to that from the computer, however the connection is never established.. the connection attempt just hangs. Turning off RethinkDNS the connection works as expected.

Interestingly ping works fine.

TIA

[ignoramous]

My guess why it isn't working...

Listening sockets won't work if VPN is active unless the app/process (I'm guessing sshd is running from within Termux) that's creating those sockets are "excluded" from Rethink.

This is a function of both Rethink (which doesn't expose "port forwarding" or equivalent functionality) & Android how VPN APIs (which don't support raw IP sockets or network namespaces to do transparent port forwarding) are setup in Android.

[xandro0777]

Yes, it is sshd inside Termux. Will test this tonight, universal bypass or firewall+DNS bypass? Local connections using the 192.168.xx.xx address do work through so listening on the socket works. The sshd daemon listens on 0.0.0.0 p8022

[xandro0777]

Excluding termux wroks good enough to make a connection, unfortunately ssh hangs after authentification for some strange reason so I cant fully confirm it is working

[xandro0777]

I think this issue could be closed when the need to exclude listening apps is documented.

However, it is worth noting that it works out of the box with Netguard so maybe it could be made work like that in RethinkDNS as well?

[ignoramous]

However, it is worth noting that it works out of the box with Netguard

NetGuard excludes a bunch of IP ranges when subnet is enabled. May be you have it enabled?

https://github.com/M66B/NetGuard/blob/2691d67c2dc45fc85f931fd1d0686f2e39421adb/app/src/main/java/eu/faircode/netguard/ServiceSinkhole.java#L1310

[xandro0777]

Don't have subnet enabled.

[Lurux]

Just chiming in to say that for me, this doesn't affect a specific program, but everything on the computer. Every connection fails or times out. OS is Fedora 41, pretty much default config I think. Rethink is configured in DNS-only mode.

Update: rethink doesn't show dns resolutions in the log. Tethering over wifi sometimes, but rarely, works.

[xandro0777]

Somewhat off topic, the remaining problem where ssh connection into the phone hangs after authentification remains unresolved - however the same works perfectly if I use the phone as wifi hotspot.

Any idea what is the difference? ifconfig doesn't reveal anything obvious and route doesn't work on Android

[xandro0777]

Just chiming in to say that for me, this doesn't affect a specific program, but everything on the computer. Every connection fails or times out. OS is Fedora 41, pretty much default config I think. Rethink is configured in DNS-only mode.

Update: rethink doesn't show dns resolutions in the log. Tethering over wifi sometimes, but rarely, works.

Is your problem connections to the phone or connections to the internet from Fedora?