SSH stands for Secure SHell, and creates a encrypted connection between you and the place you are connecting to. In this article, we discuss some SSH clients, how to create an SSH connection to NTNU's servers, as well as how to use SSH with X-window.

Norsk versjon - Sikker med SSH

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If you want to use SSH to connect to the students' UNIX computers, use one of the programs below to connect yourself to Employees should use

Later on in this article, we will use in examples. Replace this with if you are an employee.

Programs #

To read about what you can do with SSH, see the manual pages for this command by running 'man ssh' in a shell. This will give you a variety of links to different SSH clients you can install on your computer. Many of them are not well tested, and we can't guarantee that they will work. If you find a bad link, please tell Orakel Support Services.

These programs are meant to be installed on your personal computer only. Do not install them on NTNU computers without speaking with the system administrator first. The system administrator should ensure that an SSH client is installed on all NTNU computers.

ClientOperating systemLicense type
ConnectBotAndroidOpen source
OpenSSHUNIX, Linux, MacOS XFreeware
iTermMacOS XFreeware/Donationware

Setting up X-window forwarding with SSH #

What is X-Window Forwarding? #

With X-Window Forwarding you can access graphical applications on your personal computer, even if the applications are on one of NTNU's servers.

Setup (Windows) #

X-windowing is not found on standard Windows installations, but you can connect to an X-window server by using X-Win32 and then connecting to when you are asked what server to connect to.

Setup (Linux/UNIX/MacOS X) #

From a console, run the command:

ssh -X -C

On MacOS X, you have to use the X11 terminal client found in /Applications/Utilities/

Set up X-window forwarding automatically. The DISPLAY variable on the computer you are logging onto should also be set automatically upon login. The -C option compresses the connection, which is desirable when forwarding X-window.

Common problems #

Troubleshooting on the computer you connect to (X-window) #

To check if the DISPLAY variable was set correctly, you should run the following command in bash/csh/tcsh:

env | grep DISPLAY

(note that this command is case sensitive). You should then get a result that looks something like:


The number after DISPLAY=localhost: can vary from login to login, and you are not supposed to set DISPLAY yourself. This will set up a normal, unencrypted connection.

Troubleshooting on the machine you are connecting with(X-window) #

Remember that the DISPLAY variable must be correctly set on the machine you are connecting with. This is not set automatically. If you are connecting with Linux from home, you can use the console to check that the DISPLAY variable has been set correctly by running:

env | grep DISPLAY

This will normally return


You can test if this works by running:


If you don't receive any error messages, and a new terminal window appears, everything is set up correctly. If not you should set the DISPLAY variable manually. In bash, that is done by running the following command:

export DISPLAY=localhost:0.0

and in csh/tcsh the same operation is done by running:

setenv DISPLAY localhost:0.0

Also see #

Contact #

Orakel Support Services can help you install an SSH client, and show you how to connect to NTNU's servers.

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