There are several ways to run X applications inside your [[VEcontainer]].

=== Single application === To run an X application inside a [[VEcontainer]], one need needs simply to connect to a VE container with '''ssh -X''':

host# ssh -2 -c blowfish -X user@address

After login to VE container check that <code>$DISPLAY</code> variable is set and X11 forwarding is enabled:

In case <code>$DISPLAY</code> is not set, make sure that X forwarding is enabled in <code>sshd</code> config inside VEcontainer. In most Linux distros sshd configuration is stored in <code>/etc/ssh/sshd_config</code>. You should set parameter <code>X11Forwarding</code> to <code>yes</code>. Also container should contain <code>xauth</code> package, thus install <code>xauth</code> if it is missing (in Debian this is part of the xbase-clients package). After that, restart your sshd daemon:

Now you can run X applications from your VEcontainer:

First, one need to run '''Xvnc''' server inside VEcontainer. The easiest way for this is to run

host# vncviewer <VE_IPcontainer_IP>:1

To start KDE desktop instead of default twm one replace '<code>twm &' </code> line with '<code>startkde &' </code> in user's<code>~/.vnc/xstartup </code> fileon the container.

A usuall usual '''ssh''' can be used for tunneling VNC connections as described below.

== Using xdm Xephyr == Xephyr gives you nested X windows. First, install Xephyr on your host. Start Xephyr <pre>Xephyr -ac -screen 1280x1024 -br -reset -terminate :1 &</pre> Change your display settings (don't forget to change them back after you establish a connection) <pre>DISPLAY=:1.0</pre> Forward your application or desktop over ssh to Xephyr <pre>ssh -XfC -c blowfish user@server xfce4-session</pre> If you use an alternate window manager, substitute "startkde", "gnome-session", "startfluxbox", etc. as needed.  [http://cafelinux.org/OptickleArt/albums/userpics/Xephyr.png Screenshot] == Using XDM with XDMCP ==This method will give you a graphical login prompt remotely similar to VNC, but with some differences. Most notably, XDMCP is faster than VNC (due to the way each deals with screen handling) and but you CANNOT connect to existing sessions like you can with VNC. Each time you logout, your programs are closed. XDMCP is better suited in situations where you don't have a local display (or dumb terminals/clients) but want to run X11 programs === container Configuration ===It should be Install your desktop environment as you'd like (kde/gnome/xfce/etc) and ensure you install at least XDM. You can opt to use GDM/KDM as they also possible do the same job as XDM. The configuration for KDM/GDM is different than XDM's and I was only able to do remote find one link on configuring GDM (more below). ===== XDM =====Configuring XDM requires editing 3 files: /etc/X11/xdm/xdm-config, /etc/X11/xdm/Xservers, /etc/X11/xdm/Xaccess In xdm-config, comment out the line where it says '''DisplayManager.requestPort: 0''' In Xservers, comment out the line ''':0 local /usr/bin/X :0 vt7'''' (this starts a local X by running server, which will fail) In Xaccess, uncomment the line with '''xdm* #any host can get a login window''' inside VE (Please keep in mind the security implications by the above line. Read the comments found in the file andset it appropriately)X To provide the possibility to run sound applications from container, /dev/dsp device file needs to be exported in container:<pre>vzctl set 221 --devnodes dsp:rw --query save<remote IP/pre>  Finally, if you intend to make xdm invoking a heavy desktop like kde, it is reasonable to increase the amount of memory available for allocation inside this container:<pre>vzctl set 221 --privvmpages 500M:600M --save</pre>For light desktop like icewm this is not needed. Once these changes have been made, start your xdm server by the appropriate startup script (typically similar to /etc/init.d/xdm start). That concludes the XDM setup in the container. ===== GDM =====Edit the '''gdm.conf''' file and in xdmcp section, comment out the '''0=standard''' line under the [servers] section - this will prevent gdm from trying to launch an X server on the local machine - it will simply listen for xdmcp requests. Insert '''0=inactive''' in [servers] section. Insert '''Enable=1''' in [xdmcp] section. Also, change from VCAllocation=true to VTAllocation=false and comment out the FirstVT=7 line if that lines exists. Change the access restrictions (if any) to suit your needs and then start GDM. === Client/Host Configuration ===

On the Client/Host (whatever machine you are connecting from to the container), you need to install ONLY a bare Xserver as per your OS instructions (use yum, emerge, apt, whatever). A desktop environment like XFCE/GNOME/KDE is entirely optional on the client, but keep in mind that it won't be used while you're connecting to the desktop on the container. To get access to the XDM server, just start an Xserver with '''X -query <remote IP> :0''' (where :0 is the local display...set to :1 if you already have an X session running, or use Xnest) There are guides online on howto securely tunnel XDMCP over the Internet (typically vpn as XDMCP can't be tunneled over ssh afaik), in an otherwise INSECURE protocol. === Errata ===On a side note, as of December 2007, I was never able to successfully get an Xserver to run inside a container and have the display output onto virtual-terminal 7 (the Xserver default), However VNC approach , you can get an Xserver running on the hostnode to display output on virtual-terminal 7 without any special configuration (as the hostnode has direct access to all necessary devices). Another user has done this with XDM and X. Just follow the directions on the wiki. It is much easierpossible. == See also ==* [[NX inside VE]]

* http://ait.web.psi.ch/services/linux/kde-desktop-sharingsoftware/local/by_task/desktop_sharing/index.htmhtml