Tunnelling X11 via ssh

From: Jana Dunn (jana@scsr.nevada.edu)
Date: Fri Oct 17 2003 - 19:17:56 EDT


Greetings,

I'm having trouble tunnelling X11 vi ssh.
I have a feeling that my problem may be a configuration
problem on my sun system(s), rather than just an ssh
issue, hence my query here.

I want to display the X client on a Solaris 2.8 system. I will call that
system "mydesktop." I have SSH Secure Shell 3.2.5 installed on that
system.

The X client (HP Openview NNM, if it matters) will run on/from a
separate Sun server, myserver, also Solaris 2.8, also with SSH
Secure Shell 3.2.5 installed.

I compiled and installed SSH on both systems taking the defaults:

checking whether to install ssh-signer as suid root... yes
checking whether to disable tcp-port forwardings... no
checking whether to disable X11 forwarding... no

On mydesktop,

in /etc/ssh2/ssh2_config:
     ForwardX11 yes

xauth is in my path on mydesktop
(although I'm not sure it matters:)

/usr/openwin/bin/xauth

Xaccess does not have any entries, just comment lines.

On myserver,

in /etc/ssh2/sshd2_config:
        AllowX11Forwarding yes

There is not a firewall or any other traffic filtering device between
the two systems.

Here's the issue as I have it diagnosed so far--the proxy DISPLAY variable
on myserver doesn't get created when I log in via ssh:

mydesktop%> echo $DISPLAY
mydesktop:0.0
mydesktop%> ssh +x jana@myserver
jana's password:
Authentication successful.

myserver%> echo $DISPLAY
DISPLAY: Undefined variable
myserver%> printenv | grep -i display

The +X (treat X applications as trusted)
flag does not make a difference, but I think
the problem occurs before I get to that point anyway.

I believe I have problems (configuration errors?) with both mydesktop and
myserver.

I have eXceed on a PC; with that PC I can ssh to another sun server
that I don't manage (I'll call it otherserver) and successfully tunnel X
through ssh. The DISPLAY variable is set correctly when I ssh to
otherserver using the PC version of ssh. I am able to display X clients
from otherserver on my PC/eXceed.

However, when I connect with eXceed to the server system I manage,
myserver,
the DISPLAY variable is not set.

Also, with I use ssh to connect from mydesktop to otherserver, the DISPLAY
variable is not set when I've logged in to otherserver.

Any suggestions as to what I might have wrong, or suggestions as to how
I might troubleshooting this issue? The "verbose" mode for ssh and sshd
wasn't particularly helpful. I didn't see any messages relating to X11,
at least at the default debugging level.

Thanks much,

Jana Dunn
jana@scsr.nevada.edu
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