Connecting to Discovery

You connect to Discovery using a secure shell program to initiate an SSH session to sign in to Discovery. Mac and Windows have slightly different procedures for connecting, as detailed below. If you usually launch software from the command line that uses a graphical user interface (GUI), see Using X11 for tips and troubleshooting information.

Mac

Mac computers come with a Secure Shell (SSH) program called Terminal that you use to connect to Discovery using SSH. If you need to use software that uses a GUI, such as Matlab or Maestro, make sure to use the -Y option in the second step below (see Using X11 for more tips and troubleshooting information).

Note

If you use Mac OS X version 10.8 or higher, and you have XQuartz running in the background to do X11 forwarding, you should execute the following command in Terminal once before connecting to Discovery:

defaults write org.macosforge.xquartz.X11 enable_iglx -bool true

You should keep XQuartz running in the background. If you close and restart XQuartz, you will need to execute the above command again after restarting. Do not use the Terminal application from within XQuartz to sign in to Discovery. Use the default Terminal program that comes with your Mac (see Step 1 in the procedure below).

To connect to Discovery on a Mac:

  1. Go to Finder > Applications > Utilities, and then double click Terminal.
  2. At the prompt, type ssh <username>@login.discovery.neu.edu, where <username> is your Northeastern username. If you need to use X11 forwarding, type ssh -Y <username>@login.discovery.neu.edu.
  3. Type your Northeastern password and press Enter.

You are now connected to Discovery at a login node.

Windows

Before you can connect to Discovery on a Windows computer, you’ll need to download a terminal program, such as MobaXterm or PuTTY. We recommend MobaXterm, as you can also use it for file transfer, whereas with other SSH programs, you would need a separate file transfer program.

To connect to Discovery with MobaXterm:

  1. Open MobaXterm.
  2. Click Session, then click SSH as the connection type.
  3. In Remote Host, type login.discovery.neu.edu, make sure Port is set to 22, and click OK. (OPTIONAL: You can type your Northeastern username and password on MobaXterm, and it will save that information every time you sign in. If you opt to do this, you will be connected to Discovery after you click OK.)
  4. At the prompt, type your Northeastern username and press Enter.
  5. Type your Northeastern password and press Enter. Note that the cursor does not move as you type your password. This is expected behavior.

You are now connected to Discovery at a login node.

Using X11

When you launch a software application that uses a graphical user interface (GUI) from the command line, this is completed through X11 forwarding. If you use MobaXterm on Windows, X11 forwarding is turned on by default. If you use the Terminal program on Mac, you’ll need to login using the -Y option (ssh -Y <yourusername>@login.discovery.neu.edu).

Tip

If you used the -Y option to enable X11 forwarding on your Mac, you can test to see if it is working by typing xeyes. This will run a small program that makes a pair of eyes appear to follow your cursor.

Passwordless ssh

You need to setup passwordless ssh to ensure that GUI-based applications will launch without any issues. You also need to make sure that your keys are added to the authorized.key file. This needs to be done anytime you regenerate your keys. If you’re having an issue with opening an application that need X11 forwarding, such as MATLAB or Schrodinger, and you recently regenerated your keys, make sure to add your keys to the authorized.key file.

Note

Errors that you can see on both Mac and Windows when launching a GUI-based program include the following:

Error: unable to open display localhost:19.0

Launch failed: non-zero return code

If you are getting these types of errors, follow the steps below to set up passwordless ssh. If you are on a Mac, complete all of the steps. If you are on Windows, sign in to Discovery using MobaXterm, then follow the procedure below starting at step 9.

To setup passwordless ssh:

  1. On a Mac, open Terminal and type, cd ~/.ssh. This moves you to the ssh folder on your local computer. Note: Make sure you’re on your local computer for steps 1 through 4. If you are connected to Discovery, type exit to return to your local computer.
  2. Type ssh-keygen -t rsa to generate two files: id_rsa and id_rsa.pub.
  3. Press Enter to all of the prompts (do not generate a passphrase).
  4. Type ssh-copy-id -i ~/.ssh/id_rsa.pub <yourusername>@login.discovery.neu.edu to copy id_rsa.pub to your /home/.ssh folder on Discovery. Enter your NU password if prompted.
  5. Connect to Discovery by typing ssh <yourusername>@login.discovery.neu.edu.
  6. Type cd ~/.ssh ; cat id_rsa.pub >> authorized_keys. This moves you to your ssh folder and adds the contents of your public key file to a new line in the ~/.ssh/authorized_keys file.
  7. Log out by typing exit.
  8. Connect to Discovery again by typing ssh <yourusername>@login.discovery.neu.edu. Note: If you are using a Windows machine using MobaXterm, sign in to Discovery as usual, then complete steps 9 through 12 to complete the passwordless ssh setup.
  9. Type cd ~/.ssh to move to your ssh folder.
  10. Type ssh-keygen -t rsa to generate your key files.
  11. Press Enter to all of the prompts (do not generate a passphrase). If prompted to overwrite a file, type Y.
  12. Type cat id_rsa.pub >> authorized_keys. This adds the contents of your public key file to a new line in the ~/.ssh/authorized_keys file.

Next steps

After you are connected, you can run jobs either in interactive mode with srun or submit a script using sbatch. See Using srun and Using sbatch for more information.

To load and run software, see Using Module and installing_software.

To find out more about the hardware and partitions on Discovery, see Hardware overview and Partitions.

To watch an introductory training video, go to Northeastern’s LinkedIn Learning page.