x2go failed to connect but not ssh with "Error: Failure negotiating the session in stage '7'."

Question

I try to use x2go on Debian Jessy.

Firstly, I can connect to localhost with ssh using ssh fauve@localhost -p 22 -i ~/.ssh/id_dsa and it work.

But, when I use x2go with the following configuration:

Host: localhost
Identifiant: fauve
SSH Port: 22
Use as DSA/RSA key for ssh authentification: ~/.ssh/id_dsa
Session type: xfce

Wen I use this,

1. I get a window witch ask me about my dsa key. I write it and click on ok button.
2. After that, I get a dialog box with user (witch have “fauve” as default user) and in the password rectangle I right my system session password and click on ok.
3. I get again a window who ask me about my dsa key like the first one (WTF?). I write it and I click on ok button.
4. I get a dialog box with a list of session. It say “select a session”. There is only one item on the list so I click on it.
5. I only get the x2go’s wallpaper with noting else. No desktop, no error message, noting.

But in a dialog box betwen the (2) and the (3) I can read the following messages:

NXPROXY - Version 3.5.0

Copyright (C) 2001, 2010 NoMachine.
See http://www.nomachine.com/ for more information.

Info: Proxy running in client mode with pid '21545'.
Session: Starting session at 'Mon Aug  8 20:55:58 2016'.
Info: Using abstract X11 socket in kernel namespace for accessing DISPLAY=:0.
Info: Connecting to remote host 'localhost:31001'.
Info: Connection to remote proxy 'localhost:31001' established.
Error: The remote NX proxy closed the connection.
Error: Failure negotiating the session in stage '7'.
Error: Wrong version or invalid session authentication cookie.
Session: Terminating session at 'Mon Aug  8 20:55:58 2016'.
Session: Session terminated at 'Mon Aug  8 20:55:58 2016'.
Connection expirée, abandon en cours
NXPROXY - Version 3.5.0

Copyright (C) 2001, 2010 NoMachine.
See http://www.nomachine.com/ for more information.

Info: Proxy running in client mode with pid '22032'.
Session: Starting session at 'Mon Aug  8 20:56:43 2016'.
Info: Using abstract X11 socket in kernel namespace for accessing DISPLAY=:0.
Info: Connecting to remote host 'localhost:31004'.
Info: Connection to remote proxy 'localhost:31004' established.
Error: The remote NX proxy closed the connection.
Error: Failure negotiating the session in stage '7'.
Error: Wrong version or invalid session authentication cookie.
Session: Terminating session at 'Mon Aug  8 20:56:43 2016'.
Session: Session terminated at 'Mon Aug  8 20:56:43 2016'.

I see the line with Error: Failure negotiating the session in stage '7'.. So what thats it mean exactly?

And generally, how can I connect to my session without this wallpaper-bug?

Answer 1

I finally find it. The problem was in /etc/ssh/ssd_config.

I had a line containing:

AllowTcpForwarding no

I comment it and it work now.