[X2go-dev] remote proxy closed the connection

[Mike Gabriel]

Hi Gerry,

On Sa 05 Feb 2011 00:09:52 CET Gerry Reno wrote:

> What's interesting is that it presents the menu and the process is shown
> as "running" so then your "suspend" it and "resume" it and you still get
> the "remote proxy closed the connection" error and NX proxy shows
> "aborting" but it does resume the session.  Very confusing to users but
> at least they get their session back.

By what I read the issue really occurs around the port forwarding  
request. I try to sketch the mechanism...


   o client: sets up a forwarding tunnel to the server (for nxproxy traffic
     which in our discussed scenario)
   o server: thinks the tunnel is already/still set up (by the former request)
             and denies the tunnel

     -> here PyHoca-GUI tries to push a cancel_port_forward request to the SSH
        daemon which sometimes works but sometimes doesn't

   o the x2goclient does not realize the failed tunnel (PyHoca-GUI  
btw. does and
     reports an error)
   o thus, x2goclient continues as planned
   o client: call of server-side x2goresume-session script (which fails because
     of the missing port forwarding tunnel)
   o client: from x2goresum-session script the x2goresume script is called
     (which updates the database and states that the new session is running
     although the session resuming failed)

The problem is that old port forwarding requests on the SSH server do  
not get properly cancelled by the clients. If a request does not get  
canceled the port is blocked/busy and another SSH client instance  
cannot request a port forwarding on this server port.

Hope that sheds more light on the situation... If you can find an SSHd  
option that could fix this behaviour this would be really great!!!

Greetings,
Mike





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