====== Remote X: Linux to Linux ======

As X11 in its newer versions doesn't allow incoming tcp connections by default anymore (see the relative [[https://cgit.freedesktop.org/xorg/xserver/commit/?id=cc59be38b7eff52a1d003b390f2994c73ee0b3e9|commit)]], since Slackware 14.2 you have to launch your X server (the one which has to display the remote application) explicitly enabling them, like

     startx -- -listen tcp

if you are using a display manager to launch your X session refer to its documentation for enabling this in its configuration file.
====== Plain Ol' Vanilla X11 Forwarding ======

**NOTE:** in the X11 world, the **SERVER machine** is the one listening for a connection (your desktop).  The **CLIENT machine** is the one initiating the connection (the machine you are executing the commands on).  I know, it sounds backwards but, it is actually correct if you understand the X11 connection.

1) Tell your X11 Server Linux box to accept X11 connections from the Client machines with the xhost command. You can add the the command to .bashrc or .profile:
   EXAMPLE: xhost +192.168.1.36

2) Start the connection from the **client** (the remote) machine to the **server** (your desktop) machine:
Connect to the remote machine via ssh/telnet/rlogin/whatever and run:

     DISPLAY=X11_SERVER_IP:0;export DISPLAY;APPLICATION_YOU_WANT_TO_RUN &
     
     EXAMPLE: DISPLAY=192.168.1.10:0;export DISPLAY;xterm &

====== X11 Forwarding Over SSH======

 1) Edit /etc/ssh/sshd_conf on the **remote machine**.

   CHANGE:
   #X11Forwarding no
   
   TO:
   X11Forwarding yes
   
   CHANGE:
   #X11UseLocalhost yes
   
   TO:
   X11UseLocalhost yes

2) ensure that X11Forwarding is enabled in /etc/ssh/ssh_conf on the **local machine**.

3) open an X11 forwarded ssh session to the remote machine:

     ssh -X USER@REMOTE_MACHINE 
     XAPPLICATION_YOU_WANT_TO_RUN



**__PROBLEMS__** \\
**PROBLEM:** ssh connection is complaining about an "Invalid MIT-MAGIC-COOKIE". \\
**FIX:** start a less secure ssh session:

     ssh -Y USER@REMOTE_MACHINE


====== Sources ======
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 * Originally written by [[wiki:user:arfon | arfon]]
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{{tag>howtos software X_Windows X11 author_arfon}}