Two Fedora 27 machines not connecting to each other

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1

I installed syncthing through dnf in two Fedora 27 machines. The version is 0.14.43.

I tried the default setup, which implies a quite complex network topology in my company. I can ping from one machine to the other, either with the DNS name or the IP. I can connect through SSH in both directions. Also, both machines show Listener 3/3 and Discovery 2/2 in the GUI. However, they cannot connect; both of them are shown as ‘Disconnected’.

NOTE: this same setup has been working ok for a couple of years. Last successful connection was on october. Global discovery never worked, but setting DNS/ip addresses did.

Alternatively, I tried using an OvisLink EVO-W10BAR, where UPnP is enabled. Still not connecting. Listener 3/3 and Discovery 2/2 is shown, and both logs are the same:

[25BF3] 14:58:12 INFO: Detected 0 NAT devices
[25BF3] 14:58:22 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) shutting down
[25BF3] 14:58:22 INFO: c.S.listenerSupervisor: Failed service 'dynamic+https://relays.syncthing.net/endpoint' (1.000000 failures of 2.000000), restarting: true, error: "{dynamic+https://relays.syncthing.net/endpoint dynamic+https://relays.syncthing.net/endpoint} returned unexpectedly", stacktrace: [unknown stack trace]
[25BF3] 14:58:22 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) starting
[25BF3] 14:58:42 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) shutting down
[25BF3] 14:58:42 INFO: c.S.listenerSupervisor: Failed service 'dynamic+https://relays.syncthing.net/endpoint' (1.629943 failures of 2.000000), restarting: true, error: "{dynamic+https://relays.syncthing.net/endpoint dynamic+https://relays.syncthing.net/endpoint} returned unexpectedly", stacktrace: [unknown stack trace]
[25BF3] 14:58:42 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) starting
[25BF3] 14:59:02 INFO: Relay listener (dynamic+https://relays.syncthing.net/endpoint) shutting down
[25BF3] 14:59:02 INFO: Entering the backoff state.

Last, I tried connecting both computers directly (without any intermediate device), manually setting the IP for each of them. It won’t work either.

Any clue about how to troubleshoot this?

There are other remote Win10 and Win7 machines which used to be connected to these, and they are also not working now. However, I want to focus on getting the direct/local connection first, because I am afraid that this could be related to some configuration in Fedora.

2

Feels like a firewall issue or a proxy that is not setup.

3

I can reproduce the error message with c.S.listenerSupervisor with this [unknown stack trace] which I consider a bug. I’ll dig into this deeper.

I set up 2 virtualboxes on a windows host, installed fedora27, dnf install syncthing and let both talk to each other. quick tests went fine, no way to reproduce your problem.

So I followed Audrius helpful hint and dropped one of the machines dead on my gateway/rooter. iptools -A FORWARD -s 192.168.1.70 -j DROP no internet for you little fedora-vm. Seconds later: [unknown stack trace].

I even build and ran the latest&greatest by:

# sudo dnf install go
# p=go/src/github.com/syncthing
# mkdir $p
# cd $p
# git clone https://github.com/syncthing/syncthing
# go run build.go
[...]
# bin/syncthing

and after shutting down internet access I got the same problem. Also in my setup it doesn’t see the other vms anymore.

But this could also be normal… I’ll dig into this later.

logfile: https://gist.github.com/wwwutz/b7233f99b3f089d9964163177baa1dda

4

Not sure why it would panic, feels like a bug, but until @calmh fixes suture to panic on panics, we won’t know what the panic is.

5

Yet this shouldn’t affect anything apart from the log messages, if a direct connection is possible.

6

That’s not a panic, that’s just the relay thing failing to talk to the relay pool. For some reason. That it doesn’t care to log.

7

Right, given internet cable was yanked, it makes sense that it fails like that

8

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