Trouble with X11 forwarding

schmmd · 2008-05-14 22:57:23

Hi. I am trying to do something which should be rather easy, but by now I have spent hours on it and am very confused. I would like to set up sshd so that I can type:

michael@gilgamesh ~$ ssh -X michael@ellez
michael@192.168.1.100's password: 
[michael@ellez ~]$ xeyes

and have the program xeyes load on my computer. Both machines (gilgamesh and ellez, client and server) are running ArchLinux and have the same version of OpenSSH.

[michael@ellez ~]$ ssh -V
OpenSSH_4.7p1, OpenSSL 0.9.8g 19 Oct 2007
michael@gilgamesh ~$ ssh -V
OpenSSH_4.7p1, OpenSSL 0.9.8g 19 Oct 2007

However, when I try to run xeyes I get:

[michael@ellez ~]$ xeyes
Error: Can't open display: localhost:10.0

I am quite convinced that this is not a client problem, because I can ssh -X into a university machine and X11 programs open just fine. Moreover, I set up sshd on the client (ellez) and I can run the following successfully:

michael@gilgamesh ~$ ssh -X localhost
michael@localhost's password: 
michael@gilgamesh ~$ xeyes

To make the problem more confusing, /etc/ssh/sshd_config is the same on both machines. I will show the uncommented lines below:

ListenAddress 0.0.0.0
ChallengeResponseAuthentication no
UsePAM yes
X11Forwarding yes
X11DisplayOffset 10
Subsystem    sftp    /usr/lib/ssh/sftp-server

Can anyone think of something else that may be causing the problem? Unfortunately, I cannot look at the /etc/ssh/sshd_config on the university machine.

schmmd · 2008-05-15 02:31:45

Aaah! I've reinstalled OpenSSH but it didn't solve anything. I feel that this problem must be due to some security setting elsewhere or another program, but I don't know where to look.

DAEMONS=(syslog-ng netfs @crond dbus hal gdm @cpufreq @wicd portmap nfslock @nfsd @sshd @samba alsa @autofs mpd)

It also does not work if I run 'xhost +' on the client and then change the DISPLAY variable.

[michael@ellez ~]$ export DISPLAY=192.168.1.106:0.0
[michael@ellez ~]$ xeyes
Error: Can't open display: 192.168.1.106:0.0

drag0nl0rd · 2008-05-15 05:34:04

michael@gilgamesh ~$ ssh -Y michael@ellez

doesn't work either?

fatlarry · 2008-05-15 14:41:45

You have to enable one computer to export GUI programs on the other's display. Look for the man page of xhosts. If I am correct, you would do smth. like this on ellez to be able to run X programs from gilgamesh (as root, of course):

# xhosts +gilgamesh

You could of course do

# xhosts +

therefore allowing everybody to access your display, but that IS a bad ideea, as far as security is concerned.

schmmd · 2008-05-15 16:38:40

I tried this yesterday with no success. I will try it again when I get home, but I don't think this is the solution. If I use my roommates computer, I can ssh -X into ellez without running xhost + on either machine--and X forwarding works.

Demind · 2008-05-15 17:24:23

Her i can forward X only with -Y flag...lol
So ssh -Y and so on...ssh -X never worked for me.
Have you ever tried it?

jot · 2008-05-15 20:13:30

In my sshd_config file I have also:
AllowTcpForwarding yes

Try to add/uncomment it and then try to log in with:
$ ssh -Y -l user server

rdt · 2008-05-15 21:01:32

Arch has /etc/X11/xinit/xserverrc contain "exec /usr/bin/X -nolisten tcp" and this prevents remote X11 connections. I've changed mine to "exec /usr/bin/X ###-nolisten tcp" which comments out the -nolisten argument. You will have to restart X for this to take effect. Then you still need some xhost magic to get what you want to work.

schmmd · 2008-05-16 04:07:13

jot wrote:

In my sshd_config file I have also:
AllowTcpForwarding yes
Try to add/uncomment it and then try to log in with:
$ ssh -Y -l user server

This did not work ;-(

schmmd · 2008-05-16 04:20:04

rdt wrote:

Arch has /etc/X11/xinit/xserverrc contain "exec /usr/bin/X -nolisten tcp" and this prevents remote X11 connections. I've changed mine to "exec /usr/bin/X ###-nolisten tcp" which comments out the -nolisten argument. You will have to restart X for this to take effect. Then you still need some xhost magic to get what you want to work.

This also did not work. I did try running 'xhost +' on the client machine.

Arch Linux

#1 2008-05-14 22:57:23

Trouble with X11 forwarding

#2 2008-05-15 02:31:45

Re: Trouble with X11 forwarding

#3 2008-05-15 05:34:04

Re: Trouble with X11 forwarding

#4 2008-05-15 14:41:45

Re: Trouble with X11 forwarding

#5 2008-05-15 16:38:40

Re: Trouble with X11 forwarding

#6 2008-05-15 17:24:23

Re: Trouble with X11 forwarding

#7 2008-05-15 20:13:30

Re: Trouble with X11 forwarding

#8 2008-05-15 21:01:32

Re: Trouble with X11 forwarding

#9 2008-05-16 04:07:13

Re: Trouble with X11 forwarding

#10 2008-05-16 04:20:04

Re: Trouble with X11 forwarding

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