Connecting to Sagehen HPC

Last updated on 2026-08-27 | Edit this page

Estimated time: 30 minutes

Overview

Questions

  • How do I connect to Sagehen using SSH?
  • How do I set up SSH on my operating system?
  • What is the OnDemand web portal?

Objectives

  • Understand SSH (Secure Shell) and its role in remote access
  • Set up SSH access on macOS, Linux, and Windows
  • Know how to use the OnDemand web portal as an alternative
  • Perform your first successful login to Sagehen

What is SSH?

SSH (Secure Shell) is a cryptographic network protocol that lets you securely connect to a remote computer and run commands as if you were sitting at that machine.

Why SSH?

  1. Encryption: All data between your computer and Sagehen is encrypted
  2. Authentication: Confirms you are who you claim to be (via password + DUO)
  3. Remote execution: You can run commands on Sagehen from your local machine
  4. Tunneling: Advanced users can forward network ports for additional security

SSH is the standard protocol for accessing HPC clusters worldwide.

SSH Connection Address

sagehen.hpc.pomona.edu

Your username is the part before @pomona.edu in your email. If your email is alice@pomona.edu, your username is alice.

Setting Up SSH Access

On macOS and Linux

macOS and Linux include SSH built-in. Open a terminal and connect:

Step 1: Open Terminal - macOS: Applications > Utilities > Terminal (or Cmd+Space, type “Terminal”) - Linux: Ctrl+Alt+T (most distributions)

Step 2: Connect to Sagehen

BASH 

ssh <myusername>@sagehen.hpc.pomona.edu

Step 3: Accept the Host Key

On your first connection, you’ll see a prompt asking you to verify the host. Type yes and press Enter.

On Windows 10/11 with PowerShell

POWERSHELL 

ssh <myusername>@sagehen.hpc.pomona.edu

On Windows with PuTTY

  1. Download PuTTY from https://www.putty.org/
  2. In “Host Name”, enter: sagehen.hpc.pomona.edu
  3. Leave “Port” as 22
  4. Click “Open”
  5. Accept the host key and enter your username

On Windows with WSL

WSL provides a native Linux environment. After installing (wsl --install in PowerShell as Administrator), use the standard SSH command.

Callout

Choosing an SSH Client

  • macOS/Linux users: Use the built-in Terminal application
  • Windows 10+ users: Use PowerShell (simplest) or WSL (most Linux-like)
  • Prefer graphical interface: Use PuTTY
  • Advanced users: Use SSH config files or terminal multiplexers (tmux, screen)

DUO Two-Factor Authentication

When you connect, Sagehen requires DUO authentication at https://duo.pomona.edu.

Flow diagram of connecting to Sagehen. Open Terminal or OnDemand, enter Pomona username, enter password, then the DUO MFA prompt offers three paths: Push approves on the Duo Mobile app, SMS enters a code from a text message, and Passcode enters a backup code. All three paths lead to Connected to Sagehen.
The login flow from opening a terminal to a successful connection, with the three DUO options.

After entering your Pomona password, you’ll see a DUO prompt:

  • Option 1: Push (recommended) – approve the notification on your phone
  • Option 2: SMS – enter the 6-digit code texted to you
  • Option 3: Backup Code – enter a pre-generated backup code
A PowerShell window running ssh to sagehen.hpc.pomona.edu. After the password prompt, a Duo two-factor menu offers Duo Push, a phone call, or SMS passcodes; option 1 is chosen and login succeeds. The commands whoami and hostname then return the username and sagehen.hpc.pomona.edu.
A real login from Windows PowerShell: password prompt, the DUO menu, then verification with whoami and hostname.

If DUO fails, contact Pomona IT Help Desk: (909) 621-8061 or .

The OnDemand Web Portal

If you prefer not to use SSH, access Sagehen through a web browser:

URL: https://ondemand.hpc.pomona.edu/

You’ll sign in with your Pomona credentials (the same Microsoft sign-in page used for other campus services):

Pomona College single sign-on page with a Sign in box prompting for username at pomona.edu, a Next button, and a campus pathway with trees in the background.
The OnDemand sign-in page. Use your full @pomona.edu address here.

After signing in and completing DUO, you’ll land on the OnDemand dashboard:

Pomona College OnDemand dashboard showing pinned apps organized into Clusters with Pomona Cluster Shell Access and System Status, Files with Home Directory, and a row of Interactive Apps, beneath menus for Apps, Files, Jobs, Clusters, and Interactive Apps.
The OnDemand dashboard with pinned apps for shell access, system status, file browsing, and interactive apps.

Advantages of OnDemand

  • No SSH knowledge required
  • Graphical file browser and text editor
  • Interactive desktop sessions (VNC)
  • Jupyter Notebook access
  • Drag-and-drop file transfer

Most advanced users use SSH, but OnDemand is perfect for getting started.

Logging Out

When you’re done, disconnect from Sagehen:

BASH 

exit

Or press Ctrl+D.

Callout

Important Security Notes

  1. Never share your password with anyone, including IT staff
  2. Close your connection when done; don’t leave it running all day
  3. SSH keys: Ed25519 is recommended; RSA-4096 is acceptable
  4. DUO is required: You cannot bypass two-factor authentication
Diagram of the secure authentication stack. Three stacked layers: Strong Password with 14 or more characters per NIST SP 800-63B and length over complexity; DUO MFA two-factor authentication at duo.pomona.edu; and SSH Keys with Ed25519 preferred, RSA-4096 acceptable, and an encrypted passphrase required. The layers converge to Secure Access to the Sagehen HPC cluster.
The three layers that protect your Sagehen HPC account: a strong password, DUO MFA, and SSH keys.
Challenge

Challenge 1: Your First SSH Connection

Connect to Sagehen and verify your environment.

Steps:

  1. Open your terminal (or PuTTY)

  2. Run: ssh <myusername>@sagehen.hpc.pomona.edu

  3. Enter your Pomona password and complete DUO authentication

  4. Verify with:

    BASH 

    whoami
hostname
pwd

You should see your username, sagehen, and /rhome/<myusername>.

If you see [<myusername>@sagehen ~]$ and the verification commands produce correct output, you’re connected.

Common errors:

  • “Permission denied”: verify your username (not email) and password
  • “DUO authentication failed”: ensure Duo Mobile is updated; try SMS
  • “Connection timeout”: check internet; try a different network
Key Points
  • SSH (Secure Shell) is the standard for securely connecting to remote computers
  • macOS and Linux include SSH built-in; Windows users can use PowerShell or PuTTY
  • DUO two-factor authentication is required; push notification is fastest
  • OnDemand (https://ondemand.hpc.pomona.edu/) provides a graphical alternative to SSH
  • Always log out when done with exit or Ctrl+D