UNIX for Dummies Questions & Answers

We have different unix servers, let say I have server 1 and server 2.
Well whenever I ssh from server 1 to server 2, I'm ok, but when I ssh from server 2 to server 1, I can connect just fine, but I get this message:
X11 auth data does not match fake data
X11 auth data does not match fake data
X11 auth data does not match fake data
X11 auth data does not match fake data
X11 auth data does not match fake data

and I would have to hit ctrl+c to stop it, this come up at the command prompt. I checked in my ssh2_config file under /etc and made sure that X11 display forwarding is enabled. This has been bugging me for a while and I don't know what to do.

Help.

- SSH might not be setup for X11 (not a problem with BIC systems)
o To check ssh the following command should output "ForwardX11 yes"

Code:

grep X11 /etc/ssh/ssh_config

- If you change user, 'su' will cause problem with keys.
o

Code:

su username

vs.

Code:

su - username

- The '-', this will load username's environment clearing anything you had previously set.

o To fix this you must know what display you are using and get the proper xauthkeys

Code:

hostname
ubuntu

echo $DISPLAY
localhost:17.0

% xauth list | grep yorick/unix:17
ubuntu/unix:17  MIT-MAGIC-COOKIE-1  628d00dc1de8b7f60cec68d44fca01f5

- Once you have this information you can then su to the other user.

Code:

su - username
Password:

% echo $DISPLAY
DISPLAY: Undefined variable.

% setenv DISPLAY localhost:17.0

% xauth add ubuntu/unix:17  MIT-MAGIC-COOKIE-1  628d00dc1de8b7f60cec68d44fca01f5

- nilesh