Hi- I believe that I have found a bug / hole in the packaging related to ssh2 / xauth. In order for X11 forwarding to work, sshd needs to run xauth, which is included in the xbase-clients package, but is not a pre-req for ssh2, or generally for x clients (sich as xemacs21). You can duplicate the problem with the following steps: install woody bare-bones, no x11 server / clients at all. apt-get install xemacs21 fix your /etc/ssh/sshd_config file to support forwarding: #Enable x11 forwarding over ssh X11Forwarding yes X11DisplayOffset 10 SSH to this machine from another with ssh forwarding enabled and attempt to tunnel the connection through (ssh -X headless.machine), it won't work, as there is no xauth to set the display. Perhaps xauth should be seperated into it's own package, apart from xbase-clients, which is recommended by or a dependency of ssh2. Or it's necessity could be indicated in the documentation.
thanks, erik