[solved] Can't use X forwarding in SSH

[ishanarora]

Hi,

I am not able to use X forwarding with SSH. This is what I get

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ishanarora@calculus ~ $ ssh -X quack
Password: 
Warning: No xauth data; using fake authentication data for X11 forwarding.
Last login: Sun Sep 30 19:28:01 2007 from xx.xx.xx.xx
ishanarora@quack:~> 

When I run any gui apps, i get these messages

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ishanarora@quack:~> konqueror 
Xlib: connection to "localhost:10.0" refused by server
Xlib: Invalid MIT-MAGIC-COOKIE-1 key
konqueror: cannot connect to X server localhost:10.0

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ishanarora@quack:~> firefox
Xlib: connection to "localhost:10.0" refused by server
Xlib: Invalid MIT-MAGIC-COOKIE-1 key

(firefox-bin:8299): Gtk-WARNING **: cannot open display: 

Another friend of mine is able to do the same on his system, so i guess there is something wrong with my X server. I am guessing the problem is trivial where my xauth data is not being passed via ssh, but why and how do I fix it?

[mattsteven]

Make sure the /etc/ssh/ssh_config has all the X options enabled on the client machine, and /etc/ssh/sshd_config has all the X options for the server enabled on the server. Lots of times people do one but not the other.

[sternklang]

Hi,

Google is your friend

The most useful result seems to be this one:

Symptoms: ssh prints "Warning: No xauth data; using fake
authentication data for X11 forwarding."

When ssh is unable to get Xauthority information for the display, it
makes up some fake authentication data and prints:

Warning: No xauth data; using fake authentication data for X11
forwarding.

This happens in particular if there is no entry for the local display
(of the form :D.S or of the form $HOTSNAME/unix:D.S) in ~/.Xauthority on
local host (the host where you issued ssh). To see the list of display
names, run:

$ xauth list

To fix this problem, run the following command on the local host:

$ xauth add `echo "${DISPLAY}" | sed 's/.*\(:.*\)/\1/'` . `mcookie`

Make sure that the command xauth and mcookie on your PATH, otherwise
use the absolute pathname for these commands.

xauth is the program to manage the authorization information used in
connecting to the X server.

echo "${DISPLAY}" | sed 's/.*\(:.*\)/\1/' extracts the display and
screen numbers in the form :D.S (e.g., :10) from DISPLAY environment
variable of the form HOSTNAME:D.S (e.g., localhost:10).

. is an abbreviation for MIT-MAGIC-COOKIE-1 protocol name.

mcookie generates magic cookies for xauth.

[ishanarora]

Hi,

Thanks for your help. I found the solution after reading the last option in the man page for ssh_config.

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     XAuthLocation
             Specifies the full pathname of the xauth(1) program.  The default is /usr/openwin/bin/xauth.

So I just added this to my /etc/ssh/ssh_config

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Host *
  ForwardX11Trusted yes
  XAuthLocation /usr/bin/xauth

Seems I was right about xauth data not being passed coz ssh could not find xauth.

PS: I had looked up on google and I had read through that page sternklang qouted, but that doesn't work coz that seems to be a very old page doing things manually that ssh is supposed to handle fully automatically. Thanks again

[ishanarora]

I was wondering if anyone would know how to forward a kde session to a display other than the one being used for localhost