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How to login

To connect to VSC you need:

  • username
  • password
  • phone number for receiving OTP (One Time Password)

Info

The OTP is valid for 12 hours. You still need to enter your password each time for every new VSC session.

Login methods:

VPN

Since November 2013, access to VSC has been restricted to IP addresses associated with participating partner universities of the VSC project. Users wishing to connect from outside these IP ranges must first log in to a machine or service within their university network. A common method for connecting is using a Virtual Private Network (VPN). Here are specific instructions from some of the partner universiteis.

Warning

You need to be in an partner university network to access VSC, you can either be physically on campus or connected through the university's VPN.

Note

In some special cases, we can also open up other IP ranges outside the partner universities

ssh

Login via:

VSC-5

 ssh [-X] <username>@vsc5.vsc.ac.at

VSC-4

 ssh [-X] <username>@vsc5.vsc.ac.at

X11 forwarding

The -X option refers to X11 forwarding, which allows to display remote computer to your local machine. This is entirely optional. For example, applications like Mathematica or Matlab that have a graphical user interface, can be displayed from on your own computer. Having said that... for better performance and because modern GUI does not run well on X-forwarding use NoMachine for application like Mathematica or Matlab. It still useful for gnuplot, xmgrace and maybe some simple VESTA visualization.

Tip

Use NoMachine (!M) for graphic heavy applications.

One can also make this change permanent by adding the following line in $HOME/.ssh/config

ForwardX11 yes

Connecting to a specific login node

VSC-4 login nodes are named: l40, …, l49.

VSC-5 login nodes are named: l50, …, l56.

Using SSH keys

Besides the traditional password method to login, one can use the key-pair or public-key authentication. Each SSH key pair includes two keys: a public key and a private key. The public key is the one to be copied to the SSH server. The private key must remain with the user and must be kept secret. The server uses the public key to encrypt a message and send it to the client. If the client, on the user side, has the correct private key, it can decrypt the message and send it back to the server for verification.

Things to consider:

  • Can be much more secure than regular password authentication.
  • Can be less secure if used incorrectly (understand before use).
  • Allows multiple logins without reentering password/pass phrase.
  • Allows safer use of ssh chains.

Generate a key-pair on your local computer. The key must be protected by a passphrase. This passphrase should be as secure as possible. (just like a strong password).

Example to generating an ssh key-pair:

$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key ($HOME/<username>/.ssh/id_rsa): 
Created directory '$HOME/<username>/.ssh'.
Enter passphrase (empty for no passphrase): 
Enter same passphrase again: 
Your identification has been saved in $HOME/<username>/.ssh/id_rsa.
Your public key has been saved in $HOME/<username>/.ssh/id_rsa.pub.
...
Now one needs to put the key on the host system. Using ssh-copy-id is a convenient way to do it. (you will be asked for your password).
$ ssh-copy-id <username>vsc5.vsc.ac.at
<username>@vsc5.vsc.ac.at's password: 
Alternatively, you can anter the ssh-key into your account via the service website - see Account management.

Using ssh-keys is an option that allows you to open multiple shells on the cluster by entering your passphrase only once.

Note

In order to login to the cluster with the ssh key use the port 27 instead of the default port 22

ssh -p 27 <username>@vsc5.vsc.ac.at

SSH agent

It is possible to load the private key into your SSH agent using ssh-add -c. The -c option will ask for confirmation every time the key is used which increases security. With this ssh, scp will work without reentering your passphrase every time. With the strongly suggested -c option you have to hit enter in the confirmation dialog once every time your key is used.

$ ssh-add -c
Enter passphrase for $HOME/<username>/.ssh/id_rsa: 

IDE integration

Some IDEs allow for connections to be made from within the program. An example would be VSCode:

  • Download an extension called "Remote Explorer".
  • Create a new SSH tunnel by clicking the "+" symbol.
  • ssh [-X] vsc5.vsc.ac.at in the command pallete.
  • Chose one of the config file to save the SSH configuration.
  • Chose the "->" to connect within the same window, or in a new VS Code window.
  • A password prompt again appears in the command pallete after which you are logged into VSC using VS Code features.

For Windows users

Users on Windows machines can also use MobaXterm to connect:

  • Download the free version of MobaXTerm from this link: MobaXTerm.
  • Session -> SSH -> In Basic SSH settings, enter remote host as "vsc5.vsc.ac.at" -> Click Specify username and enter your userid -> Keep Port as 22 -> (Optional) Change name to your desired name in "Bookmark settings" in "Session name" as, say VSC5.
  • Click ok.
  • Enter your password and OTP to connect to the VSC login node.

Putty

Putty is an alternative to the standard terminal SSH connection, it was originally designed for the Windows platform, however, can also be used on other platforms, you can download it from: https://www.putty.org

You can also use public-key authentication the PuTTY SSH client. The SSH agent in PuTTY is named Pageant. Please read the PuTTY documentation for more information.

As hostname, you have to enter one of our systems (either VSC4 or VSC5).

example hostname:

vsc5.vsc.ac.at