X Windows

This article describes the steps necessary to install X server software on your home computer. This will enable you to display windows and graphics created by applications running on remote UNIX systems.

Note that in many cases you may be better of using the EML JupyterHub for browser-based access to RStudio and VS Code, or Remote Desktop to run any graphical program in a remote desktop window.

Windows: eXceed

Most of our users who require X server software tend to choose Hummingbird’s eXceed because of its availability to the Berkeley campus, its broad feature set, and its Microsoft Windows compatability.

Download

Hummingbird eXceed can be downloaded from http://software.berkeley.edu. You are required to authenticate with your CalNet ID.

Install

Installation is fairly simple; just double-click on the installation program. The installer runs some display diagnostics towards the end so expect the installation process to take longer than most software installations.

Configure

The best way to run eXceed is in conjunction with SSH software. This ensures that your connection is secure and that anyone snooping on your internet connection will not be able to read any passwords or other secure information that you type. When you run eXceed and SSH software, you will launch programs from the SSH window and eXceed will be able to display them. See these instructions for information on downloading and installing SSH software.

Enable Passive mode

To enable eXceed to work with SSH clients, it will have to be configured to wait for X connections, as opposed to initiating X sessions itself.

Run the Xconfig utility that comes with eXceed. In the Xconfig control panel, open the Communication item and configure your connection to be Passive.

SSH X Forwarding

Your Windows SSH client must be configured to forward X Window System communication from the machine you are connecting to to your PC’s display.

putty

Launch putty.exe, click on the plus sign to the left of “SSH” in the left hand pane, then click “X11” and check the box labelled “Enable X11 Forwarding”.
SSH Communications Security

Choose Settings… from the Edit menu and then choose Tunneling from the Profile Settings tree on the left. Check Tunnel X11 connections in the pane on the right.

The above works fine if you start eXceed first and then start your SSH client. It is possible, however, to create a shortcut on your desktop that will automatically start both eXceed and your SSH client automatically. To enable this:
- Open the Xsession utility that came with eXceed.
- In the Xsession Session Startup Application popup window, click on New Program. Then choose Windows App and then the OK button.
- In the Wstart popup window, fill in:
```
Description:  ssh
Command line: the path to ssh.exe (Browse for it)
Working directory: the path up to \ssh, i.e., c:\data fellows\f-secure\ssh
Run:  Normal
```
  Then choose Save from the File menu and name the file ssh.ws. Then quit the Wstart window.
- Now in the Xsession window, you will see ssh.ws ssh under Available Programs. ssh.ws is the new filename, and ssh is the description.
  
  Click on ssh.ws ssh to enable the Add button. Click on Add. This adds the ssh.ws file to Included Programs.
- Next choose Save from the File menu and name the file ssh.ses. Again, the default path is the user directory in the exceed tree.
- The last step is to find where eXceed saved ssh.ses and create a shortcup to it on your desktop. This is the icon you should double-click to start your secure X session.

Windows: Xming

Xming is the X Windows Software from X.Org ported to Microsoft Windows. It shares source code with Cygwin’s X server (see below), but you do not need the full cygwin environment to run it. You can use this X server in much the same way you use eXceed, though it does not come with many of the features of eXceed. If, for some reason, eXceed becomes unavailable to you, try this software. It can be downloaded from http://www.straightrunning.com/XmingNotes/.

Windows: Cygwin

The Cygwin UNIX environment also includes the XFree86 X Window System. It can be downloaded from http://www.cygwin.com/xfree/.

Apple: XQuartz

Install

Download XQuartz from https://www.xquartz.org.

Forwarding X11

For forwarding remote X sessions over ssh you can use either Terminal.app (also found in /Applications/Utilities) or xterm. If you are using the macOS Terminal, you will need to set your DISPLAY variable. Enter this statement into the file ~/.bashrc on your own computer (not your EML account):

if [ -z "$DISPLAY" ]; then export DISPLAY=:0.0; fi

and then start a new Terminal window. If you are using xterm from with XQuartz (via the Application menu > xterm), the variable should be set for you.

On the Mac you should also use the -X and -Y options:

ssh -X -Y username@hostname