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

[Daniel Lindgren]

Hi Mike,

2011/7/29 Mike Gabriel <mike.gabriel at das-netzwerkteam.de>:
> The connecting stuff is a bit tricky...
>
>  - x2gostartagent will try to detect a free server-side port >30000.
>    This port is put into the session database table. (Make sure you do
>    not have other server-side stuff running that claims ports between
>    30000 and 30000++.
> [...]
>  - x2goclient now tries to set up a forwarding tunnel from
>    client to server (-L 30000:localhost:30015)
>  - if the local port 30000 (the first one in the above expression) is
> already
>    in use, it simply selects another port. Each selected port is probed
> before
>    usage. That is done by x2goclient.

OK, will this also work if the server starts x2goclient while an
incoming tunnel is active? Example:

Client CA connects to server SA. No other sessions are running on
either, so ssh on CA forwards local port 30001 to remote port 30001 on
SA. Server SA registers server side port 30001 in the session
database.

Server SA starts an x2goclient session to server SB, where no sessions
are running. Will x2goclient on server SA then detect that port 30001
is already in use on SA?

Let's say that SA does start a session to SB on 30001 (both sides).
Client CA disconnects (suspends) SA and then resumes the suspended
session on SA. That's the point where I ran into trouble with "the
remote proxy closed the connection while negotiating …". Moving SB:s
port range to a different one than SA worked around my problems.

I discovered the conflicts about a year ago and I've been using the
workaround (separate port ranges for each server) ever since, perhaps
unnecessarily with the latest x2go* versions.

x2goclient-cli does sometime leave ssh running on the client, I've
added code to deal with it (see http://wiki.x2go.org/x2goclient-cli).

Cheers,
Daniel