Error in an effort to run an X client in a remote X Display.

chomwitt · 2025-06-09 09:27:54

Home Lan: hostname: enous (192.168.2.75) / user : chomwitt
hostname : familypc (192.168.2.11) / user : alex
Both run devuan/daedalus.

We'll need deb package : x11-apps for xeyes (@)

(chomwitt/enous) $ xhost +
access control disabled, clients can connect from any host
(alex/familypc) $ xeyes -display 192.168.2.75:0.0
Error: Can't open display: 192.168.2.75:0.0

The same happens trying to start xeyes in enous and use as X Display familypc.

Last edited by chomwitt (2025-06-09 09:40:49)

ralph.ronnquist · 2025-06-09 09:43:43

If you check with pgrep -a Xorg (on the host where it is running) you will se that it is started with the parameter -nolisten tcp which means precisely that, that the server doesn't listen for connections on its standard tcp port (well not on any port).

To run remotely the way you attempt to do it requires you to start Xorg without that parameter.

When you've figured out how to do that, you have passed "Xorg usage 101" I'll have a browse myself meanwhile, and we can have it as a race....

ralph.ronnquist · 2025-06-09 10:21:32

The -nolisten tcp gets added to the Xorg command line by the /etc/X11/xinit/xserverrc start up script when invoked by startx. Aaccording to man startx the start up script may be overridden by the user (root?) who starts Xorg.

For experimentation you could edit that file, changing it to -listen tcp before restarting Xorg to see that it works. (It should)

chomwitt · 2025-06-09 11:51:09

@ralph.ronnquist I was off for a while so unfortunately i couldnt sync to your proposed X conf race :-)
but thanks for the solution.

It worked but only to one of my host where i start X from a tty shell with startx.
In the other xfce host with xdm as display manager it didnt work.

I will try to read to xdm conf.
I think it's :

/etc/X11/xdm/Xservers
:0 local /usr/bin/X :0 vt7 -nolisten tcp

Changing -nolisten to -listen it'll be effective after restarting the whole system.Logging out from XDM and
llogginh again in didnt work.

Also it seem's appropriate since i started that thread to quote the security note from /etc/X11/xdm/Xservers
and remind to fellow devuan readers that what drives me is the curiosity to learn some basic of how network
trasnaperncy works with X.

# - SECURITY NOTE: Always pass the "-nolisten tcp" option to the X
# server, as shown in the examples below, unless you know you
# need the X server listening on a TCP port. Omitting this
# option can expose your X server to attacks from remote hosts.
# Note also that SSH's X11 port-forwarding option works even with
# X servers that do not listen on a TCP port, so you do not need
# to remove the "-nolisten tcp" option for SSH's benefit.

Speaking of 'security' in the context of X can have more finegrained control than xost + that i tried for experimentation's sake.
So i think that ssh forwarding could 'overdone it' for a home lan. I guess having access restricted inside the lan hosts could be a far more better and less computational intesive approach. Last, i prefer the term 'workflow isolation' than security. Security make me think of badass criminals and police. But when i work on my table for me 'security' is not allowing other family members messing with my workspace. On the other hand i may have set a space to allow someone to laydown a snack or water.. (i wonder if that is a part of the desktop metaphor that was missed in the 80s..)

Last edited by chomwitt (2025-06-09 13:10:13)

PedroReina · 2025-06-09 15:00:41

Logging out from XDM and llogginh again in didnt work.

It makes sense: the X server is not restarted.

Changing -nolisten to -listen it'll be effective after restarting the whole system.

No need to: just restart the X server.

Did you try to ssh -X into your remote box?

chomwitt · 2025-06-09 18:10:34

@PedroReina How will i restart the X server in xdm or another display manager?
For the moment i try using network transparency without using ssh.

ralph.ronnquist · 2025-06-09 23:27:03

Bring up a terminal and use the command

pkill Xorg

(as the user that owns the Xorg process)

PedroReina · 2025-06-10 09:51:18

chomwitt wrote:

How will i restart the X server in xdm or another display manager?

Restarting the display manager restarts the X server. With SysV, service YOUR_DM restart. As I said, just logging out and in does not read the new configuration values. So, the procedure shoud be: log out, restart DM, log in again.

chomwitt wrote:

For the moment i try using network transparency without using ssh.

Understood. It will be very educational. I hope the best to you . By the way, I felt in love with the old X system when I succeded doing what you are trying now. Back then (circa 1998) I didn't know the very existence of ssh.

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#1 2025-06-09 09:27:54

Error in an effort to run an X client in a remote X Display.

#2 2025-06-09 09:43:43

Re: Error in an effort to run an X client in a remote X Display.

#3 2025-06-09 10:21:32

Re: Error in an effort to run an X client in a remote X Display.

#4 2025-06-09 11:51:09

Re: Error in an effort to run an X client in a remote X Display.

#5 2025-06-09 15:00:41

Re: Error in an effort to run an X client in a remote X Display.

#6 2025-06-09 18:10:34

Re: Error in an effort to run an X client in a remote X Display.

#7 2025-06-09 23:27:03

Re: Error in an effort to run an X client in a remote X Display.

#8 2025-06-10 09:51:18

Re: Error in an effort to run an X client in a remote X Display.

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