ssh X forwarding not working

[Dan Christensen <jdc@jhu.edu>]

When I connect to my laptop using ssh, X forwarding doesn't work.
For example:

  jdc@scratchy:~% ssh localhost xterm
  X11 connection rejected because of wrong authentication.
  
  X connection to scratchy:11.0 broken (explicit kill or server shutdown).
  jdc@scratchy:~% ssh localhost echo \$DISPLAY
  scratchy:12.0

When I connect from the laptop to other machines, forwarding works
properly.  I have forwarding turned on.

  jdc@scratchy:~% grep Forward /etc/ssh/*config
  /etc/ssh/ssh_config:### ForwardX11 & ForwardAgent
  /etc/ssh/ssh_config:    ForwardAgent yes
  /etc/ssh/ssh_config:    ForwardX11 yes
  /etc/ssh/sshd_config:X11Forwarding yes

Supplying the appropriate command line options doesn't help.  The
machine is running

ii  ssh            1.2.2-1.4      Secure rlogin/rsh/rcp replacement (OpenSSH)

Any suggestions?

Dan

-- 
Dan Christensen
jdc@math.jhu.edu