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= NX Client =
= NX Client =
'''Please note:''' We are gradually moving to noVNC (VNC via a web browser) and VNC as our main graphical remote access tool, as it will be the default access method in the newer visualization station image. NX is still available on visualization workstations that are running the older operating system image, but it will no longer be available once the systems are upgraded (Fall 2013).
== What is NX Client? ==
== What is NX Client? ==

Revision as of 12:25, 12 September 2013

We are now gradually moving to noVNC (VNC via a web browser) and VNC as our main graphical remote access tool. NX is still available on most visualization workstations.


noVNC (web browser)

noVNC is a HTML5 VNC client that runs inside a web browser. You can find the links in our systems page under 'Visualization Workstations': just click on a blue icon next to the workstation name to connect. Your web browser needs to be fairly modern to support the advanced features of HTML5. Currently, we are testing noVNC on two machines (viz1-uwaterloo and viz6-uoguelph), and it'll be propagated to the rest of the visualization workstations in the near future.

ssvnc (local client)

We tested ssvnc client on Linux, MacOS, and Windows. Other clients supporting VeNCrypt should work as well; here we provide instructions for ssvnc. The address below can be changed to any other visualization workstation.

ssvnc on Linux

Download a unix_only version from, unpack it, and then run the command:

/path/to/your/ssvnc/bin/ssvnc_cmd -proxy vencrypt://

ssvnc on MacOS

Download a no_windows version from, unpack it, and then in the (found under /Applications/Utilities) run the commands:

export UNAME=Darwin.i386
/path/to/your/ssvnc/bin/ssvnc_cmd -proxy vencrypt://

ssvnc on Windows

Download a windows_only version from and unpack it. Navigate to ssvnc\Windows and run sshvnc. When a window opens up, press Options, and then press Mode. Switch the mode from the default "SSH-Only (sshvnc)" to "SSHVNC". A newer larger configuration window will open. Set VNCHost:Display to and Proxy/Gateway to vencrypt:// . Check "Use SSL" and uncheck "Verify All Certs", and finally press Connect.

NX Client

Please note: We are gradually moving to noVNC (VNC via a web browser) and VNC as our main graphical remote access tool, as it will be the default access method in the newer visualization station image. NX is still available on visualization workstations that are running the older operating system image, but it will no longer be available once the systems are upgraded (Fall 2013).

What is NX Client?

NX Client is a program which allows you to remotely connect to a virtual desktop on an X11 computer in a similar manner to VNC. NX Client has several advantages over both Xming/PuTTY and VNC however, including:

  • Connection is streamed through an SSH connection for increased security
  • Eliminates a lot of X11's latency issues, making interfaces way more responsive, even over cable modem/ADSL connections
  • Gives you your own private login session that is not accessible to others. (VNC merely lets you control the screen remotely, and anyone at the workstation can see what you are doing, and take control back. NX Client avoids this problem.)
  • Provides you with a real X session hosted on the remote system, using the remote system's hardware, meaning you do not need to install a local X server to run it, and the capabilities of the remote system are used for your session.
  • Preserves your session if you are accidentally disconnected! If your network connection is disconnected or your computer is shut down due to an accident, your session on the remote computer will not be killed - instead it will be returned to you once you log back in, with your programs still running. Xming can not do this.

Java NX Client

If your web browser supports it, you can run the Java NX launcher directly from our website (this downloads the appropriate client for you and installs in a plugin directory on your machine). Just

  1. click the desktop icon for the machine you wish to connect to,
  2. tell your browser it is okay to run the NX Web Companion application (if it asks),
  3. press the continue button when it comes up and says it is read to run,
  4. enter your SHARCNET login and password and press login.

If it says that the maximum number of concurrent sessions have been reached for this sever, the machine you have picked already has too many people connected to it. You can try again later or pick another.

Binary NX Client

You can obtain the binary NX client program by going to and entering their Download area. Go to the NX Client Products section (the client is free), and choose the one that best matches your workstation. You should not need the "fonts" packages unless you are running a very old program on the Viz terminals, and are having difficulties.

Once you have downloaded the nxclient installer, run it, and it will create a "NX Client for Windows" icon on your desktop. Run this program, and you will be taken to a set of configuration screens, where we can create our first Session - this will make an icon on the desktop for us to choose so that we don't need to configure the session every time we start the program. First, choose a session name, and enter the Host name of the Viz Terminal you wish to connect to. (In this example, we use


After filling those in, click "Next" and choose the GNOME session and 1024x768 as your screen size - while it is possible to use larger screen sizes on larger monitors, for connections from home via DSL or cable modem especially, keeping the size limited will make the program run much more smoothly:


Now click on "Next" until finished, and you will be given the NX "Login" window as below:


In the future, you only need to click on the desktop icon you created to log in this way, rather than setting it up again. Enter your username and password, then click the "Login" button, and NX Client will connect to the remote machine (as long as it is on) and give you a desktop that looks just like the one you would get if you were at the machine itself:


IMPORTANT NOTE: When logging out of your NX Client session, always do it by logging out of the local machine - in the menus along the top of the virtual screen, choose "Session", then "Log Out (your userid)" to log out.


Xming Software

What is Xming?

Xming is an X11 server that can be run on your local Windows desktop computer - it will allow you to run graphical applications from remote Unix and Linux computers such as the SHARCNET clusters, when used in combination with an SSH client.

Where to get Xming

Xming is available from, where a variety of versions can be downloaded. For a fee, you can download the latest version, or a slightly older, but still functional version is avaliable for free. Of the two free versions, one is the basic "Xming" server, and the second, "Xming-mesa", allows you to make use of 3D graphics if they are used by the remote application. This tutorial will work under the assumption that you have downloaded the free version, labeled "Xming-mesa", since it will do all of the work that the basic Xming program does, and in situations where a program requires 3D graphics support, it is better to have it already, rather than finding out when your program will not run.

How to Install and Use Xming

To install Xming, first download the Xming-mesa public domain from The Website, and run it. For the majority of the setup options, you should accept the default, and just click "Next >". When asked to Select Components, make sure "Normal PuTTY Link SSH client" is selected, and turn on all checkboxes, as below:


Once this has been completed, you can click "Next" until you reach the "Setup" window, and turn on the desktop icons for Xming and XLaunch if you wish. After this, click "Next" until done, and click the final "Install" button to complete the installation.

The first time you install Xming, you may also be asked for additional configuration options for the server. In each of these conditions, the default setting is the best choice for using Xming with the SHARCNET clusters.

Right after installation, the Xming server will already be running, but if you log out or reboot your computer, you will need to click the "Xming" icon to start it up again if you wish to use it. If you chose not to install the desktop icon, the server can also be found in the Programs menu under "Xming". To verify that Xming is installed, check the taskbar of your computer to see if the "X" logo is present, like this:


PuTTy SSH client

Next, if you do not already have a copy of the PuTTY SSH client, you can get one from here - download the putty.exe program file, and place it on your desktop for easy access, no installation is needed for this program. Once it is downloaded, run it, and you will be presented with the configuration screen. For this example, we will connect to the system, but the same instructions can be used for any of the clusters, simply by changing the Host Name you use.

In the first configuration screen, we need to do a few things. We enter our Host Name ( and a name for our session (Rainbow X11) and then click "Save" - we should then see what is shown below:


Next, click "X11" in the category menu on the left. (It should be near the bottom) and turn on the checkbox beside "Enable X11 forwarding", like this:


Last, return to the "Session" category at the very top of the menu on the left, and click the "Save" button again to save the X11 settings. Now the setup is complete, and you can click "Open" to log in. The next time you start PuTTY, all of the settings should be in place already if you double click the "Rainbow X11" entry in the Saved Sessions list. You can now log into the cluster using your regular SHARCNET username and password.

Now that everything is installed, the next time you come to your computer to use X11 programs on SHARCNET, you will only need to follow three steps:

  1. Start Xming (if the Xming logo is not in the tool tray, double click the Xming icon to start it.)
  2. Start PuTTY
  3. Double-click the session you wish to log into in PuTTY and log in with your username and password.

Once you are logged into the cluster, if you wish to test to verify that X11 is working, type the command "xlogo" and hit enter. A small window that looks like this should appear somewhere on your screen:


You can now run any program that requires X11 to function while on the clusters.