Accessing Euler

Euler is accessible via SSH at hostname euler.wacc.wisc.edu. Accounts for research projects may be requested by contacting Dan Negrut.

The following describes how to log in from various operating systems.

Linux / MacOSX / Unix

Most Unix-like systems include an SSH client. To access Euler, simply open the terminal and type ssh username@euler.wacc.wisc.edu, replacing username with the one provided to you.

macosx:~ demo$ ssh demo@euler.wacc.wisc.edu
demo@euler.wacc.wisc.edu's password:
Creating directory '/home/demo'.
[demo@euler ~]$

Windows

PuTTY is one of the most popular SSH clients for Windows. The installer version is preferred as it includes a few utilities that will be used later (PuTTYGen).

To use PuTTY, enter the server hostname (euler.wacc.wisc.edu) and click Open.

login: demo
demo@euler.wacc.wisc.edu's password:
[demo@euler ~]$

Key-Based Authentication (Optional)

Public key-based authentication allows you to access resources without explicitly entering a password every time. This section is optional and is not required in order to access Euler.

Linux / MacOSX / Unix

OpenSSH-based clients typically include a command named ssh-keygen which is used to generate the private and public keys. Once generated, the public key can be copied to the server using ssh-copy-id.

Note

MacOSX does not ship with ssh-copy-id; a copy is available here: ssh-copy-id.

On Linux:

[demo@linux ~]$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/demo/.ssh/id_rsa):
Created directory '/home/demo/.ssh'.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/demo/.ssh/id_rsa.
Your public key has been saved in /home/demo/.ssh/id_rsa.pub.
[demo@linux ~]$ ssh-copy-id demo@euler.wacc.wisc.edu
demo@euler.wacc.wisc.edu's password:

Number of key(s) added: 1

Now try logging into the machine, with:   "ssh 'demo@euler.wacc.wisc.edu'"
and check to make sure that only the key(s) you wanted were added.

On MacOSX:

macosx:~ demo$ ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/demo/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /Users/demo/.ssh/id_rsa.
Your public key has been saved in /Users/demo/.ssh/id_rsa.pub.
macosx:~ demo$ curl -o ssh-copy-id https://gist.github.com/andrewseidl/6488345/raw/bffde4ea5cf23eebd8b0f4ee15708a0a9d0af7f5/ssh-copy-id
macosx:~ demo$ less ssh-copy-id # inspect to make sure nothing changed
macosx:~ demo$ chmod +x ssh-copy-id
macosx:~ demo$ ./ssh-copy-id demo@euler.wacc.wisc.edu
demo@euler.wacc.wisc.edu's password:
Now try logging into the machine, with "ssh 'demo@euler.wacc.wisc.edu'", and check in:

  .ssh/authorized_keys

to make sure we haven't added extra keys that you weren't expecting.

Windows

In Windows, use the program PuTTYgen to generate the keys, saving the private key to a safe place. Copy the public key to the clipboard.

Next, log in to Euler as you normally would using PuTTY. Create a file named ~/.ssh/authorized_keys which contains the public key you copied from PuTTYgen (right-click in PuTTY is mapped to paste).

[demo@euler ~]$ mkdir ~/.ssh && chmod 700 ~/.ssh
[demo@euler ~]$ cat >> ~/.ssh/authorized_keys << EOF
ssh-rsa AAAAB3NzaC1yc2...0seOoxPfSAwlQ== rsa-key-20130908
EOF
[demo@euler ~]$ chmod 600 ~/.ssh/authorized_keys

Finally, configure PuTTY to automatically send your username and the key. In a new session, set your username in Connection > Data > Auto-login username and select your private key in Connection > SSH > Auth > Private key. Return to Session, re-enter the hostname, enter a name under Saved Sessions, and hit Save. Double clicking on the session name should then automatically log you in to Euler.

Remote X Sessions via NX

It is sometimes desirable to use X11-/GUI-based programs from Euler. While Unix-like systems can forward this programs directly using ssh -X, Windows users typically need to install and configure an X server such as Xming. Alternatively, Euler allows users to create a remote X session using NoMachine NX.

Warning

NX on Euler should be considered unsupported and legacy. It may not always work and may be replaced in the future.

To begin, download and install the NoMachine 4 Beta Client for your system. While that is installing, login to Euler via SSH and run cat /home/nx/client.id_dsa.key to get a copy of NX’s key. Save this to a file on your machine.

Next, open NoMachine and click the icon for Add a computer. Give the session a name (“Euler”), set the protocol to ‘SSH’, and enter the hostname (euler.wacc.wisc.edu). Click Advanced and select Use the NoMachine login. Click Continue and select the file you just created with NX’s key. Click Continue to finish.

You should now be on a summary page with the new connection. Click Connect and enter your Euler login details. Once connected, click Create a new virtual desktop and select Create a new GNOME virtual desktop. After clicking Continue you should be presented with a desktop running on Euler where you can use GUI-based programs.

Note

Please remember to logout once you no longer require a desktop. NX is very resource-intensive compared to the terminal, which may cause issues if too many people are using it at once.