NX - A Virtual Desktop
to the PPPL portal Cluster
The "portal" computers are the set of login nodes
to the PPPL Research Computing Center. These machines, named
sunfireXX, are the user's entry point for developing software,
analyzing data, and submitting batch jobs. The portal
computers do not have graphics hardware and do not run an X-Window
server. They are limited to running command line shells.
To overcome this limitation and provide a graphical interface to
portal, PPPL has licensed the NX Server products. The NX
server provides a virtual graphical desktop that simulates a Linux
workstation with its own graphics hardware and X-Window
environment. NX is developed by NoMachine in Luxembourg,
The NX system provides a Linux desktop to the
PPPL "portal" computers. NX is a client/server system where
the client runs on a user's desktop or laptop computer. The
client computer can run Mac OS, Windows, or Linux. The NX
desktop is displayed in a window on your computer, as in Figure
1. It can run programs with graphical user interfaces, display
images, and provide a multi-window environment on portal.
Performance is typically faster than just an X-Window connection.
When you connect to NX you can choose either KDE
or GNOME as your desktop environment. Your desktop will be
preserved from one client session to another. This enables you
to connect to the same desktop session from your home computer as
well as from computers at the lab. If you are going to make a
connection from outside of PPPL, then be sure to use your SecureID
and log in to the VPN beforehand.
Figure 1 - An NX Desktop to "portal" is displayed in a window.
1. Client Program
The NX client program runs on your local computer. PPPL is
currently running version 4.5 of the NX server. You can
download the corresponding client program for your computer from http://w3.pppl.gov/fgweb/nx/clients4.5
This web page has options for Windows, Mac, and Linux. It will
be version 4.5.
If version 4.5 of the NX client does not work with the operating system on your computer
then you should install the latest version of the NX client from the NoMachine website
1.1 For Mac:
Download the file nomachine_4.5.0_1.dmg.
When the download is complete, about 27 megabytes, open a Finder
window and go to Downloads. Double click on the file named
nomachine_4.5.0_1.dmg and it will bring up the NoMachine
installation window. Double click on the NoMachine.pkg
icon. This will bring up the Install NoMachine window.
Go through its installation steps.
To run the NX client, click on the magnifying glass in the toolbar
and type in: nomachine. Select the NoMachine
application. Continue with the set up instructions in section 1.4 on this page.
You can disable the help screens by checking the box for Don't show
this message again.
1.2 For Windows:
Download the file nomachine_4.5.0_1.exe. When the download is
complete (about 28 megabytes) select the downloaded file, right
click on it, and choose "Privilege Manager Install/Run
Elevated". Run the EXE file and go through the Setup Wizard to
complete the installation.
If you are not able to run this exe to install the client, then go
to the icon in the taskbar for the PPPL Software Center.
Select the option for NoMachine and go through its installation
To run the NX client, go to All Programs in the start menu and
select No Machine NX client. Continue with the set up
instructions in section 1.4 on this page.
1.3 For Linux:
Download the file nomachine_4.5.0_1_x86_64.tar.
As root, cd /usr and put the file in /usr.
tar -xvf nomachine_4.5.0_1_x86_64.tar
/usr/NX/nxserver -- install
Then run the client: /usr/NX/bin/nxplayer
1.4 Defining Your
Initial NX Connection
Run the NoMachine client program to define a connection to the NX
server. Click on the "New" icon or on
<Click here to create a new connection> as shown in
2 - Defining a new connection to the NX server.
The program will guide you through 5 steps to define a connection.
1. Protocol - Set the protocol to NX.
2. Host - Enter host
port number should be 4000.
3. Authentication -
Use the system login.
4. Proxy - Don't use
5. Save as - Enter a
name, such as nxV4. Finally click on Done. An icon for
your description will be shown as in Figure 3.
off the checkbox for "Use UDP communication for multimedia data"
This checkbox is in the Advanced
Figure 3 - A connection to the NX
server has been defined.
The NoMachine client program will automatically save your
definition for future use. When you start the program
do not have to repeat the definition process. You can just
start using the connection that you defined as described in
A typical work session will start with the screen shown in
1.4 Connecting to the NX Server
Click on the icon to select the connection that you have
defined. Then click on Connect. This brings up the
login shown in Figure 4.
Enter your username and password and click on OK.
Figure 4 - Login screen.
When the login completes it brings up a screen showing existing
connections (if any) to the NX server. You may see connections
from other users. To show just your own connections click on
the View icon. To create your initial desktop, click on
<New virtual desktop or custom session> shown in Figure 5.
5 - Creating a new desktop.
Next you can choose your desktop environment. Click on either
GNOME or KDE. Note: GNOME produces a sharper
looking display than KDE so GNOME is the recommended choice.
Then click on Continue as shown in Figure 6.
The new custom session lets you create a "rootless" window for a
single application. Choose custom only if you want
to run one program or just one shell window.
6 - Choose GNOME or KDE for your desktop environment.
Now you should have a desktop displayed in the client
window. Initially you are logged in to nxsrv01 or nxsrv02 and
placed in a temporary /home directory. This is not your /u
directory and does not contain any of your files. Do not save
any of your work in your /home directory. This computer does
not mount your /u home directory. Therefore, in each terminal
window that you open, ssh to portal to get to your /u
directory. ssh to portal does not require a password on this
computer. X forwarding is on by default.
2.1 NX client crashes
If your client program suddenly exits (when trying to connect) it is
likely that you have to remove NX client from your computer and
re-install it. Windows users should contact the Help Desk and request removal of
all "hidden" nx files.
2.2 Client Connects but shows all black window or Connection Fails
This is usually caused by a problematic NX or gnome environment in
your directory on the NX server computers.
Connections will also fail if you have more than 5 NX sessions on the servers.
You can try to correct this yourself by terminating all your open sessions.
In the client, right click on each of your sessions and select "Terminate session"
from the pop-up menu. Then log in to each of the 4
computers: nxfront, nxsrv01, nxsrv02, nxsrv03. In your home
directory on each computer, run:
rm -rf .gconf .gconfd .gnome2 .kde .nx
2.3 Client is automatically scrolling the desktop
This happens when the size of the desktop is bigger than the client
window. To eliminate the scrolling, click on the NX icon in
the menubar and click on Show the menu panel. Go to Display
and click on Resize remote screen. Then Done, Done to get back
to your desktop. That will eliminate the scrollbars and