[X2go-dev] remote proxy closed the connection

[John A. Sullivan III]

On Fri, 2011-02-04 at 20:31 -0500, Gerry Reno wrote:
> On 02/04/2011 06:09 PM, Gerry Reno wrote:
> > On 02/04/2011 06:01 PM, Gerry Reno wrote:
> >   
> >> On 02/04/2011 04:43 PM, Mike Gabriel wrote:
> >>   
> >>     
> >>> Hi Gerry,
> >>>
> >>> On Fr 04 Feb 2011 22:14:28 CET Gerry Reno wrote:
> >>>
> >>>     
> >>>       
> >>>> Has anyone found out how to prevent this "remote proxy closed the
> >>>> connection" error from happening when a session becomes detached and a
> >>>> user tries to resume the session?
> >>>>
> >>>> We are seeing this problem quite often and every once in a while you can
> >>>> get it to resume but mostly this session is unrecoverable and must be
> >>>> manually terminated - which is creating much sysadmin work.
> >>>>       
> >>>>         
> >>> Test the following:
> >>>
> >>> Whenever this error occurs, restart your X2go server's SSH daemon. My
> >>> guess is that you can resume the session once SSH is restarted.
> >>>
> >>> I have read about weird port forwarding habits of the SSH daemon... I
> >>> also meet these problems with PyHoca-GUI.
> >>>
> >>> Greets,
> >>> Mike
> >>>
> >>>     
> >>>       
> >> Ok, the plot thickens.
> >>
> >> I took a look at netstat both prior-to and after we get this error:
> >>
> >> # normal state
> >> # we can successfully resume a session
> >>
> >>     # netstat -a | grep 300
> >>     tcp        0      0 localhost:30008         *:*                    
> >>     LISTEN    
> >>     tcp        0      0 localhost:30009         *:*                    
> >>     LISTEN    
> >>     tcp6       0      0 ip6-localhost:30008     [::]:*                 
> >>     LISTEN    
> >>     tcp6       0      0 ip6-localhost:30009     [::]:*                 
> >>     LISTEN    
> >>
> >>
> >> # # after I forced a session to detach
> >>
> >>     # netstat -a | grep 300
> >>     tcp        0      0 localhost:30008         *:*                    
> >>     LISTEN    
> >>     tcp        0      0 localhost:30009         *:*                    
> >>     LISTEN    
> >>     tcp        0      0 localhost:33552         localhost:30037        
> >>     TIME_WAIT 
> >>     tcp6       0      0 ip6-localhost:30008     [::]:*                 
> >>     LISTEN    
> >>     tcp6       0      0 ip6-localhost:30009     [::]:*                 
> >>     LISTEN    
> >>
> >>
> >> # # if we just wait for a while then reattempt to resume the session it
> >> succeeds
> >>
> >>     # netstat -a | grep 300
> >>     tcp        0      0 localhost:30008         *:*                    
> >>     LISTEN    
> >>     tcp        0      0 localhost:30009         *:*                    
> >>     LISTEN    
> >>     tcp6       0      0 ip6-localhost:30008     [::]:*                 
> >>     LISTEN    
> >>     tcp6       0      0 ip6-localhost:30009     [::]:*                 
> >>     LISTEN    
> >>
> >>
> >> So whatever is causing this TIME_WAIT is what appears to have a role in
> >> the error.
> >>
> >>
> >> Regards,
> >> Gerry
> >>
> >>
> >>
> >>   
> >>     
> > 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.
> >
> >
> > Regards,
> > Gerry
> >
> >   
> 
> The TIME_WAIT occurs on the server because apparently there is no
> keep_alive which would make the client responsible for closing the
> connection.  I didn't see any TCPKeepAlive=yes in the ssh options which
> may be accounting for TIME_WAIT showing up on the server.
<snip>
Hmm . . . not sure but it rings a bell that 300 seconds is hard coded in
the client - John