X via ssh to HP-UX problem

[Malcolm Kay]

Hi,
At work I have been using ssh for X connections between FreeBSD an linux 
machines without problems.

Meanwhile X connections to a HP machine 'HP-UX hphendon B.10.20 A 9000/735' 
on the network have been established using classical 'rsh' with 'xhost'
authentication because the HP-UX system did not have ssh installed.

I recently installed openssh-3.7.1p2 on the HP and as a simple terminal 
connection this seems to work OK. But if I try to tunnel X through ssh
I have problems -- the connection is rejected.

From one of the FreeBSD machines (FBSD 4.9) issuing the command:
$ ssh -v -X -f hphendon xterm
yields debug information including the following lines:-

  debug1: client_input_channel_open: ctype x11 rchan 2 win 65536 max 16384
  debug1: client_request_x11: request from 127.0.0.1 1419
  debug1: fd 4 setting TCP_NODELAY
  debug1: fd 4 setting O_NONBLOCK
  debug1: channel 1: new [x11]
  debug1: confirm x11
  debug1: X11 connection uses different authentication protocol.
  X11 connection rejected because of wrong authentication.
  debug1: X11 rejected 1 i0/o0

I assume "X11 connection uses different authentication protocol" is at the
core of the problem -- but what does it really mean? Is there a way around
the problem? Must I go back to the classical insecure xhost approach?

Yes, I did enable X11 in sshd_config on the HP.

X on the HP is based on "X consortium" rather than "XFree" -- can this
be significant?

An X connection can be established in the other direction without problem.

I would appreciate any thoughts on this matter.

Malcolm Kay