X11 forwarding in OpenSSH question

From: Mike (mikeumo_at_onebox.com)
Date: 11/17/03 

Date: Mon, 17 Nov 2003 07:16:17 GMT

Hello,

I wonder if someone could help me with this problem.

I have two Linux boxes on LAN (both Mandrake 9.1 on i586, static IP), say
BoxA and BoxB. BoxA runs X server and BoxB runs sshd
(openssh-3.6.1p2-mdk1.2.91). I use ssh client (openssh-3.6.1p2-mdk1.2.91)
from BoxA to login as a user to BoxB where I run X Windows programs (say,
konqueror) which I want to display on BoxA. As is, situation results in
(case 1):

libGL error: failed to open DRM: Operation not permitted
libGL error: reverting to (slow) indirect rendering
kbuildsycoca running...
libGL error: failed to open DRM: Operation not permitted
libGL error: reverting to (slow) indirect rendering
mcop warning: user defined signal handler found for SIG_PIPE, overriding
... # and many more as I navigate in the opened browser

and konqueror does start, but, as it says, in a slow mode.

if I set the DISPLAY variable (in /etc/profile like DISPLAY=BoxA:0.0;
export DISPLAY) on BoxB to point to BoxA's display then I get (case 2):

Xlib: connection to "192.168.1.3:0.0" refused by server
Xlib: No protocol specified
konqueror: cannot connect to X server 192.168.1.3:0.0 # i.e. BoxA display

now if I use xhost on BoxA to add BoxB to BoxA's access control list (xhost
+BoxB) then I get only (case 3):

kbuildsycoca running...
mcop warning: user defined signal handler found for SIG_PIPE, overriding

so, there seem to be fewer problems now. Now the question:

why ssh/sshd do not resolve connections in the first case automatically?

I have X11 forwarding enabled in both ssh-client and sshd. It looks to me
that md5sum cookies do not work in the first ssh case. I also tried to
extract/merge .XAuthority from BoxA to BoxB with no changes in output.

Can someone help me to understand the process of ssh forwarding and X server
authentication. The man and HOW-TO pages on this matter are confusing.

Thank you in advance,
Mikhail.

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