[geeks] X11 Connection Forwarding Madness

[Jonathan C. Patschke]

Maybe I'm asking for too much here, but I want to forward a forwarded
X11 connection.  Here's the setup:

I have a Mac at home running Apple's X11 server.  It's behind a firewall
that does NAT.

I have a Sun at work running Sun's SSH server.  It's behind a firewall
that does NAT.

I have a server coloed with a friend of mine.  It's behind a firewall
that doesn't to firewalling (it approximates a filtering bridge).

The Sun is set up to keep an SSH tunnel open to my server.  That tunnel
maps to port 22 on the Sun.  So, I can ssh from my Mac to my server the
Sun at the office and get work done.

I'm home sick today, and I need to do some work involving a particularly
awful piece of IBM software that uses a Java-based GUI administration
tool.  X11 forwarding from the server to the Mac works just fine.  X11
forwarding from the Sun to the server works just fine.

However, this doesn't work:

  [jp at mac:~]$ echo $DISPLAY
  :0.0
  [jp at mac:~]$ ssh -X -C jp at server
  [jp at server:~]$ echo $DISPLAY
  server:10.0
  [jp at server:~]$ ssh -X -C -p nnnn jp at localhost
  [jp at sun:~]$ echo $DISPLAY
  sun:10.0
  [jp at sun:~]$ xterm
  X11 connection rejected because of wrong authentication.
  X connection to sun:10.0 broken (explicit kill or server shutdown).

Xauth looks okay, at least, I -think- it does:

  [jp at sun:~]$ xauth list
  sun:10  MIT-MAGIC-COOKIE-1  498763f6779dbc41a72fd4f1784d421e
  sun/unix:10  MIT-MAGIC-COOKIE-1  498763f6779dbc41a72fd4f1784d421e
  [jp at server:~]$ xauth list
  server:10  MIT-MAGIC-COOKIE-1  498763f6779dbc41a72fd4f1784d421e
  server/unix:10  MIT-MAGIC-COOKIE-1  498763f6779dbc41a72fd4f1784d421e

What could the problem be?  sshd_config on all machines allows X11
forwarding and TCP forwarding.

-- 
Jonathan Patschke  *)  "It's not about who's right and who's wrong...
Thorndale, TX      (*   it's about who works for the government and who
                   *)   doesn't."                        --Dave McGuire