[X2go-Dev] 3.99 Testing - Multiple X2goclient instances fail

John A. Sullivan III jsullivan at opensourcedevel.com
Fri Jul 29 08:56:37 CEST 2011


On Fri, 2011-07-29 at 07:24 +0200, Daniel Lindgren wrote:
> 2011/7/28 John A. Sullivan III <jsullivan at opensourcedevel.com>:
> <snip>
> >> > > > > >>> I believe I have tested this on both Linux and Windows - becoming a bit
> >> > > > > >>> of a blur after a long hot day!.  In previous versions of X2GoClient, I
> >> > > > > >>> could open multiple instances and connect to multiple different X2Go
> >> > > > > >>> Server simultaneously.  It was not official and it generated a few
> >> > > > > >>> errors but it worked.  This is actually a highly desirable feature for a
> >> > > > > >>> possible very large account of ours.
> >> > > > > >>>
> >> > > > > >>> For some reason, that has stopped working in 3.99.  It did not work in
> >> > > > > >>> 3.0.1.18 either.  It does work in Pyhoca so I do not think it is an
> >> > > > > >>> impossibility.  If at all possible, we would like to see this
> >> > > > > >>> functionality restored - preferably officially but even accidentally as
> >> > > > > >>> it was would do :)  Thanks - John
> 
> One thing I've had problems with in the past is TCP port conflicts.
> When x2go starts a session, it always uses a TCP port above 30000,
> decided by x2gostartagent on the server side. If you start multiple
> sessions from one client to several different servers, wouldn't that
> create a port conflict sooner or later? Maybe that is what you've
> seen, with conflicts causing sessions to terminate.
> 
> Example, x2go on client CA connects (a ssh tunnel) to server SA on
> port 30001 (-L 30001:localhost:30001 user at SA). You then start another
> session from client A to server B, also using port 30001 (-L
> 30001:localhost:30001 user at SB). Doesn't that create a port conflict on
> client CA? You have two separate ssh tunnels trying to use the same
> TCP port on the client.
> 
> The problems I've seen have been when client CA has connected to
> server SA, which then has been used as a "gateway client" to connect
> to other servers. Sometimes the session between CA and SA used port
> 30001 and the session(s) between SA and other server SB also used port
> 30001. I could always set up the sessions, but if I tried to reconnect
> from client CA to SA I got an error message about ”the remote proxy
> closed the connection while negotiating …”. My workaround was to
> separate the port ranges used by x2gostartagent on the servers; server
> SA now uses 30001-, server SB uses 30101-, server SC uses 30201- and
> so on. No more conflicts.
> 
> I've been trying to think of some way to make x2go automatically only
> use free ports, but since there are possibly several clients and
> servers involved in multiple incoming and outgoing sessions, the only
> safe way I've come up with would be to register used ports (or reserve
> port ranges) on a shared resource somewhere, which would make all x2go
> clients and servers dependent on that one resource.
<snip>
Yes, but I believe in the past it has always managed to magically pick
another set of ports.  That seems to have stopped happening - John




More information about the x2go-dev mailing list