Dana Vrajitoru
C151 Multi-User Operating Systems

How To Connect as an X Client

Linux

If you work from a Linux computer in the CS labs, then there is nothing special to do.

If you work on a Linux computer from outside of the campus, you can either do the work locally, or connect remotely with the command explained in Lab 0 and in the file How To Connect. In the ssh command, the "-X" option specifies the use of the local X11 library. It is important for X to be uppercase.

If you get an error message when you try to open an application requiring a GUI, like gedit, then you may have to enable your local machine to accept the display of X applications from a remote location. For that, before you connect (you may have to close the connection, and open it again after this), run the command

xhost +

and then open the ssh connection with the -X option.

Mac OS

From a MacOS machine, by connecting remotely with the -XY option, you already connect your terminal to the X11 utility on your MacOS. This utility is normally installed with the system, but if it's not, you can look up the X11 on the Apple site and install it.

You still need to set up a preference option that is useful when working remotely or even locally under X11. Go to the X11 menu at the top of the screen and open the Preferences... Click on the Input tab. Make sure that the third option about enabling key equivalents under X11 is not checked. Many X11 applications use the Ctrl and Cmd keys for their own purposes, and enabling the MacOS equivalents would disable the normal functionality of these keys under these applications. In the same window select "Emulate three button mouse". Go back to the terminal.

If you are working in the CS labs on one of the non-Linux machines, reboot the computer under MacOS (you have to hold the Alt key during the reboot to be able to choose the system).

Windows

On a Windows machine, if you are working from one of the IT open labs computers, the software should already be installed - Putty and Xming.

At home, you will have to install an X client for Windows. The one that we have on campus and that I've tested myself with positive results is called Xming and you can download it from:
http://www.straightrunning.com/XmingNotes/ - click on the Xming link from Public Domain Releases.

Once you install it, you first have to start Xming. When asked to allow Xming to connect to nextworks, check both the private and public networks. Then open Putty normally and click (simple click) on one of your bookmarked llinks. Click on the button Load. Or simply type the name of the host instead. Before you click on Open, go to the Connection section on the left at the bottom, click on ssh, then on X11. Check the button Enable X11 forwarding. Now you can open the connection.