[X2go-dev] Port conflict when using x2go client och x2go server

[Daniel Lindgren]

Hello.

I've run into a problem when using x2go to remote control a server
which in turn remote controls another server using x2go, i.e. client_a
-> server_a -> server_b.

I can create the sessions without problem, but I can't reconnect to
server_a if I suspend the session. I get an error message about "the
remote proxy closed the connection while negotiating ...".

As far as I can see there is a port conflict. Ssh on client_a forwards
local port 30001 to/from sshd on port 30001 on server_a, which in turn
has an ssh that forwards local port 30001 to/from sshd on port 30001
on server_b.

I've worked around it by manually changing SSH_PORT range in
/usr/bin/x2gostartagent on server_b to start at 30100 (i.e. a
different range than server_a uses).

I don''t know the inner workings of all x2go components, but by
studying x2goclient-cli I'm guessing that separating port ranges to
use when forwarding would solve it permanently; instead of using
"30001:localhost:30001" one would use "31001:localhost:30001", thereby
separating ssh and sshd ports if they are running on the same machine.

Cheers,
Daniel