Configuring SSH Key Pairs for Cluster Access

This page provides general instructions for producing and configuring SSH key pairs for authenticating to OrangeGrid and Zest.

In most cases, users are able to utilize NetID/password combinations to authenticate to their desired cluster node. However, SSH key pairs, when configured, offer several key benefits including the elimination of passwords resulting in reduced risk of credential theft as well as the cryptographic strength of the keys themselves.

Secure Connection Required

Note that SSH connections, including those utilizing SSH key pairs, require a campus or secure connection (when off campus). Additional details about each cluster, including details for connecting off-campus, are available on the OrangeGrid (OG) | HT Condor and Zest | Slurm support pages.

Head Node Code Execution

OrangeGrid and Zest are not intended to be used as a development environment. Activities on the cluster should be limited to submitting jobs, doing light editing with a text editor such as nano or vim, and running small tests that use a single core for no more than a few minutes. Avoid running code and processes directly on the node you are connected to as this can interfere with other users and, in some cases, impact the whole cluster.

On This Page

Generating and Configuring SSH Key Pairs
Follow the steps below to configure a new SSH key pair in anticipation of accessing a cluster with SSH. Once you have generated and configured your SSH key pair for the cluster, you do not have to do this step each time.
Note: These instructions are written generally for OpenSSH and some programs, such as VS Code, are not compatible with this configuration using alternative SSH solutions like PuTTY.
OpenSSH Compatible Client Required

Before proceeding, note that SSH key pair configuration requires an OpenSSH compatible SSH client (PuTTY is not supported). If you do not have administrative access to the device you are connecting with, such as campus lab and office locations, please simply log in using the connection steps above and use your NetID/password combination.
Step 1 - Generate SSH Key Pair
First, you'll need to create and configure an SSH pair for each node you'll be connecting to, a great secure solution to connection.
Open a Terminal
Open a terminal based on your operating system.
Windows - Command Prompt or Git Bash
MacOS or Linux - Terminal
Generate the SSH Key Pair
In the terminal, generate your SSH key pair with the following command. Be sure to give the key pair a comment that allows you to identify it. This could be your email address, netid, cluster name, etc.
Generate SSH Key Pair

# Example Key Generation ssh-keygen -o -a 100 -t ed25519 -f ~/.ssh/id_ed25519 -C "<comment; ex.netid or email cluster-name>"

You'll be prompted to choose a location to save the key pair. This will default to '~/.ssh/id_ed25519'. Be sure to notate if you choose another location.
You also have the option to set a passphrase. If you prefer to not, simple hit 'Enter' to skip.
Passphrase Recommended

While you are not 'required' to utilize a passphrase, doing so is highly encourage in the effort to keep your private key secure.
Step 2 - Add the SSH Public Key to the Cluster
Next, you'll need to add the public key to each node you intend to connect to using this key noting that you can certainly generate a new key for each node. Being by displaying and copying your
Copy the Public Key
Use a corresponding terminal to display the public key so that you can copy it.
Display SSH Key Pair

# CMD type %USERPROFILE%\.ssh\id_ed25519.pub # Shell cat ~/.ssh/id_ed25519.pub

Add the Public Key to the Login Node
Next, connect to the cluster and add the public key. Repeat this step for other nodes as needed.
Add SSH Key Pair to Cluster

# Make the .ssh directory in your home directory mkdir -p ~/.ssh # Put the copied public key into your authorized_keys file echo "your_copied_public_key" >> ~/.ssh/authorized_keys # Ensure the .ssh locations have the correct permissions chmod 700 ~/.ssh chmod 600 ~/.ssh/authorized_keys

Step 3 - Configure SSH Connection
Lastly, you'll need to ensure your application is configured to make the SSH connection utilizing your new or existing SSH key pair.
Either during connection prompt or when configuring, you'll need to know where your SSH configuration is saved. This is likely '~/.ssh/config' or 'C:\Users\<netid>\.ssh\config'.
Next, be sure the information for your host has been given the appropriate notations including specifying the SSH key location to be used.
Example SSH Config File

# Example Host Connection Configuration Host its-og-login1.syr.edu HostName its-og-login1.syr.edu User <your-netid> IdentifyFile <SSH key location, ex. "~/.ssh/id_ed25519">

Be sure to save any configuration files if you've made any changes.
Connect to the SSH Host
Finally, connect to your host. To do so, press 'F1' to open the Command Palette.
In the Command Palette, this time type 'Remote-SSH: Connect to Host...' and select it.
You should now see the intended host. Select it and you should be connect.

SSH Key Pair Compatibility
Below is a list of known compatible SSH solutions with this configuration type.

Getting Help
Question about Research Computing? Any questions about using or acquiring research computing resources or access can be directed at researchcomputing@syr.edu.