Login Node¶

Users accessing CCR's HPC resources will be connected to a login node. A login node is a outward facing node within CCR's HPC environment that users can connect to from their local machines. Once on a login node, users can perform a limited number of tasks:

Edit files
Transfer Data
Submitting Jobs
Access storage resources

As of August 2023, new users have access to CCR's new environment. See here for more information

This page covers connecting to a login node using SSH (Secure Shell Protocol). When you connect via SSH, you authenticate using a private key file on your local machine. For more information about SSH, see Secure Shell on Wikipedia. You can also connect to CCR's login nodes using a web browser with the OnDemand Portal.

Note

Login nodes should not be used for resource-intensive tasks such as running software or compiling code. For those tasks, users should submit batch or interactive jobs to reserve a node in the cluster.

To get started connecting to CCR's HPC clusters and shared storage you need the following:

A CCR user account with two factor authentication enabled and an active allocation to HPC resources. For more information see our getting access guide.
An SSH Key added to your account
An SSH client. Linux & MacOS include a terminal app. For Windows users, we recommend using Git Bash

VPN Required

Access to CCR login nodes is restricted to UB and Roswell Park networks (either on campus or connected to their VPN services). See here

Connecting with SSH¶

Using the SSH protocol, you can connect and authenticate to CCR login nodes without supplying your password. To set up SSH, you will need to generate a new SSH key pair that contains a private key (stored only on your personal computer) and a public key (uploaded to your CCR account using the IDM portal). During the login process the CCR servers attempt to match the public key that you've uploaded to your CCR account with the private key you have stored on your computer. If they match, the login is successful.

Generate new SSH key¶

The first time you want to login to CCR's login servers, you'll need to generate a new SSH key pair on your local machine. After you generate the key pair, you must add the public key to your account using CCR's IDM portal.

Follow these easy steps:

Open your terminal or Git Bash if you're on windows
Run the following command, substituting in your email address:
```
$ ssh-keygen -t ed25519 -C "your_email_address"
```
At the prompt, type a secure passphrase
Copy the contents of the public key to your clipboard. The file is located here:
```
~/.ssh/id_ed25519.pub
```
Login to the CCR IDM portal and click on SSH Keys in the left nav menu
Click on the "New SSH Key" button, paste the contents of your public key in the text box, and click "Add".

Initial Wait Period

After uploading your SSH key to the CCR portal, it will take 20-30 minutes to propagate our systems and allow you to login.

Using the SSH Agent¶

Running an SSH agent process on your local machine allows you to load your SSH private key one time and it will be used for every SSH login attempt. This allows you to skip entering your SSH key passphrase each time you login and you will not have to specify your private key in the SSH login command. Follow these steps to add your key to the ssh-agent:

Open your terminal or Git Bash if you're on windows

Start the ssh-agent in the background:

$ eval "$(ssh-agent -s)"
> Agent pid 12345

Add your SSH private key to the ssh-agent using the command below. If you created your key with a different name or location, use the correct path and filename to your private key. You will be prompted to enter your passphrase for the key. NOTE: The SSH key passphrase is NOT your CCR password. This is the passphrase you set when creating your SSH key pair:
```
$ ssh-add ~/.ssh/id_ed25519
```
List the SSH keys currently loaded in your running SSH agent:
```
$ ssh-add -L
```

Restarting the SSH Agent

If you restart your computer, the SSH agent may not automatically restart. This varies by operating system so we recommend searching for online documentation on how to set this up. You will need to supply the private key passphrase each time the agent restarts.

Logging in¶

Once you've uploaded your SSH public key to your CCR account you will be able to use the SSH protocol to connect to CCR's login nodes. Follow these steps:

Open your terminal or Git Bash if you're on Windows and, if you're running a SSH agent as described above, enter the following:
```
ssh username@vortex.ccr.buffalo.edu
```
New users & those wanting to use CCR's new environment should use:
```
ssh username@vortex-future.ccr.buffalo.edu
```

NOTE: If you're not running a SSH agent (see above) you will need to specify the location and filename of your PRIVATE key using the -i option in the SSH command and you'll be prompted for your SSH key passphrase. This is NOT your CCR password. This is the passphrase you set when creating your SSH key pair. For example:

ssh -i /path-to-key/id_ed25519 username@vortex-future.ccr.buffalo.edu
Enter passphrase for key 'id_ed25519':

2. When logging into CCR's login nodes, you may see a warning message similar to this. Verify the fingerprint in the message you see matches CCR's public key fingerprint. If it does, then type yes.

The authenticity of host 'vortex-future.ccr.buffalo.edu (128.205.41.24)' can't be established.
ED25519 key fingerprint is SHA256:qYT1DzrHv8yTlHiNGV2td29309oXPHdN4OPj/KptFYg.
Are you sure you want to continue connecting (yes/no/[fingerprint])?

3. If your login was successful, you should now be at a shell prompt on the login node:

username@vortex-future:~$

First Login - Additional Setup

On first login your home directory will be created automatically. You will see a message indicating this has been done, a SSH key pair gets generated for use on the cluster, and you're given access to CCR's new software modules.

OnDemand for Web-Based Cluster Access¶

Open OnDemand provides access to CCR's clusters, storage, visualization servers, and interactive apps. CCR's OnDemand portal offers Linux desktops for GUI-based applications, software applications like MatLab, RStudio Desktop, Jupyter Notebook, and vscode, an interactive development environment. OnDemand can be used in any browser from almost any device. More information about OnDemand can be found here.