unreliable connection

[Guus Sliepen]

On Fri, Jul 02, 2021 at 07:55:04PM +0200, Erich Eckner wrote:

> I recently upgraded tinc from 1.0.36 to 1.1pre18 on one of my nodes and I
> see some connection trouble since then.
> 
> My topology is attached.
> 
> All nodes were running 1.0.36 before and the net worked fine. Recently, I
> updated "desk" to 1.1pre18 (it's the only node running crux linux, all the
> others run archlinux) and now connections from "desk" to "backup_lo" and
> "nlopc43" are really unreliable: pings and ssh mostly time out, but
> *sometimes* succeed - it seems, the *first* time, pings come through, but
> once I quit "ping" and restart, they won't.

Can you try to capture a log of what is happening? On desk that can be
done with:

tinc -n enet log 5 | tee log.txt

Then try to ping and SSH. Send me the log.txt file and I will have a look.

> Increasing debug level on "desk" didn't bring anything up, except, that tinc
> apparently now prefers ed25519 keys, so I created one on "desk", put it into
> the host configs on "home" and "fenster" and restarted tinc on "desk",
> "fenster" and "home". But nothing changed :-(

The Ed25519 key won't do anything until you have other nodes moving to
1.1, so that's expected.

> I'm out of ideas - what should I try next? I could think of tcpdump'ing the
> connections on any node, but I have no real idea, what filters to use :-/

If tinc is running on port 655, you can use something like:

tcpdump -lni eth0 udp port 655

However, if it worked with tinc 1.0.36, I don't think this will offer
any insights. The log output from tinc should be more helpful.

-- 
Met vriendelijke groet / with kind regards,
     Guus Sliepen <guus at tinc-vpn.org>
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