VPN MTU limit breaks ssh connection to openssh 6.2p2 server

[Peter Stuge]

Ernst Kratschmer wrote:
> From my debug, I can see that the 1460 byte packet get split into
> two packets exactly as expected from the MTU limit.

Nobody is challenging this.


> And both packets get sent to the client.

Nor this. But what really matters is that they are both well-formed
and that they *arrive* at the client. I'm not sure you've provided
information about whether that is the case.


> The client then resets the communication.

If either packet is malformed then that's the right thing to do.


> This happens regardless of the type of client software used,
> Cygwin, putty, openssh any version, etc.

As you know, TCP is not implemented by the client software, but by
the operating system network stack. And given an invalid packet most
operating systems will do the same (right) thing.


Please analyze what the client receives, if it is two packets then
investigate whether they are well-formed. If they are, then look
further up the layers.


//Peter