I have an OpenVPN connection that was initially over UDP. After a while I started to have serious problems when running ssh inside that tunnel.
As seen from inside the tunnel, the ssh packets were lost, there were unreachable host ICMP messages, all this translated into a connection that was hanging all the time (and then returned to normal, to hang up again after some time ).
From the perspective of the operator interface, I was seeing a constant stream of encrypted packets (
DATA_V2). The OpenVPN server remained stable (without disconnection / reconnection of the client).
I switched to TCP and all the problems are gone.
Now I would like to understand what part of the connection is at fault.
In topological terms, the client and the server are about 10 jumps away, with a RTT of 12 ms. The networks are presumably solid (the client, after leaving a solid corporate network, moves to a level 3, linked to Orange, which brings FTTH).
Is there a reasonable way to verify if the UDP problems are close to either end (corporate or local)?
Note: I understand that UDP is by nature a protocol that expects losses. Due to the "strength" of the network, however, they seem to be very important.