issue with openssh-server running in a libvirt based centos virtual machine

Adrian Pascalau
2018-01-26T19:50:14Z

On Fri, Jan 26, 2018 at 5:02 AM, Darren Tucker <dtucker at dtucker.net>
wrote:
> On 26 January 2018 at 06:44, Adrian Pascalau <adrian27oradea at
gmail.com>
> wrote:
>>
>> [...]
>> debug1: SSH2_MSG_KEXINIT sent [preauth]
>>
>> Here the debug mode stops, and there is no login prompt shown on the
>> Putty window.
>
>
> This behaviour is often caused by a path MTU/fragmentation problem.
>
> If you run "netstat" on both client and server and find the SSH
TCP
> connection you should see a "Send-Q" column.  This column is the
number of
> bytes in the TCP socket buffer that the other end has not acknowledged.  If
> it is non-zero number that remains above zero or increases then IP
> fragmentation is likely your problem and you need to fix whatever in your
> environment is causing that.

Darren, thanks for your reply.

In the ssh client side, I have a windows host that runs Putty. So I
installed a new centos to be able to see the "Send-Q" column, since
the windows netstat does not have it. Surprise, the ssh connection
works like a charm. I went back to the windows box to try again with
Putty, and I have the same issue. So could this be because of windows?
I cannot suspect Putty, since I tried this with another windows based
ssh client (MobaXterm), and the same issue happens.