SSH Connection Guide¶

This guide will help you set up SSH connections to OSC for secure and convenient access to the clusters.

Windows users: run SSH from WSL

All SSH commands in this guide should be run inside your WSL terminal, not PowerShell or Command Prompt. If you haven't set up WSL yet, see the WSL Setup Guide first.

Basic SSH Connection¶

Quick Start¶

Connect to OSC with this command:

ssh username@pitzer.osc.edu

Replace username with your OSU name.# (e.g., buckeye.1).

Available Clusters¶

# Pitzer (recommended for GPU work)
ssh username@pitzer.osc.edu

# Owens (older cluster)
ssh username@owens.osc.edu

Configuring SSH for Convenience¶

SSH Config File¶

Create or edit ~/.ssh/config to simplify connections:

On Linux/macOS:

nano ~/.ssh/config

On Windows:

notepad $HOME\.ssh\config

Basic Configuration¶

Add this to your SSH config file:

# OSC Pitzer
Host pitzer
    HostName pitzer.osc.edu
    User your.osuusername
    ServerAliveInterval 60
    ServerAliveCountMax 3

# OSC Owens
Host owens
    HostName owens.osc.edu
    User your.osuusername
    ServerAliveInterval 60
    ServerAliveCountMax 3

Replace your.osuusername with your actual OSU username (e.g., buckeye.1).

Now you can connect simply with:

ssh pitzer
# or
ssh owens

Advanced Configuration with SSH Keys¶

For password-less login (after setting up SSH keys):

Host pitzer
    HostName pitzer.osc.edu
    User your.osuusername
    IdentityFile ~/.ssh/id_ed25519
    ServerAliveInterval 60
    ServerAliveCountMax 3
    Compression yes
    ForwardAgent no

Host owens
    HostName owens.osc.edu
    User your.osuusername
    IdentityFile ~/.ssh/id_ed25519
    ServerAliveInterval 60
    ServerAliveCountMax 3
    Compression yes
    ForwardAgent no

Configuration Options Explained¶

ServerAliveInterval 60: Sends keep-alive messages every 60 seconds
ServerAliveCountMax 3: Disconnects after 3 failed keep-alives
Compression yes: Enables data compression (useful for slow connections)
ForwardAgent no: Disables SSH agent forwarding (security best practice)
IdentityFile: Specifies which SSH key to use

SSH Keys Setup¶

Why Use SSH Keys?¶

No password typing: Automatic authentication
More secure: Harder to compromise than passwords
Required for VS Code Remote: Makes remote development seamless

Generate SSH Key Pair¶

If you haven't already:

# Generate ED25519 key (recommended)
ssh-keygen -t ed25519 -C "your.email@osu.edu"

# Or generate RSA key (alternative)
ssh-keygen -t rsa -b 4096 -C "your.email@osu.edu"

Press Enter to accept the default location, then optionally enter a passphrase.

Add Key to OSC¶

Display your public key:

cat ~/.ssh/id_ed25519.pub
# Or for RSA: cat ~/.ssh/id_rsa.pub

Copy the entire output
Log into my.osc.edu
Go to "My Account" → "Manage SSH Public Keys"
Add your public key
Wait 5-10 minutes for propagation

Test SSH Key Authentication¶

ssh pitzer

You should connect without entering your OSU password (though you may need your SSH key passphrase if you set one).

Using SSH Agent (Optional)¶

If you set a passphrase on your SSH key, use SSH agent to avoid typing it repeatedly:

Linux/macOS¶

# Start SSH agent
eval "$(ssh-agent -s)"

# Add your key
ssh-add ~/.ssh/id_ed25519

# Verify it was added
ssh-add -l

Windows (PowerShell)¶

# Start SSH agent service
Start-Service ssh-agent

# Add your key
ssh-add $HOME\.ssh\id_ed25519

Connection from Off-Campus¶

Option 1: OSU VPN (Recommended)¶

Install Cisco AnyConnect
Connect to OSU VPN
SSH to OSC normally

Option 2: Direct Connection via Duo 2FA¶

OSC systems are accessible from off-campus without VPN, but you must authenticate with Duo two-factor authentication at each login.

Port Forwarding¶

Forward ports for accessing services running on OSC (e.g., Jupyter, TensorBoard):

Local Port Forwarding¶

# Forward remote port 8888 to local port 8888
ssh -L 8888:localhost:8888 pitzer

# Forward with custom local port
ssh -L 9999:localhost:8888 pitzer

In SSH Config¶

Host pitzer-jupyter
    HostName pitzer.osc.edu
    User your.osuusername
    LocalForward 8888 localhost:8888

Then connect with:

ssh pitzer-jupyter

Dynamic Port Forwarding (SOCKS Proxy)¶

ssh -D 8080 pitzer

File Transfer¶

For SCP, SFTP, rsync, and other transfer methods, see the File Transfer Guide.

Troubleshooting¶

Connection Timeout¶

Problem: Connection times out or hangs

ssh: connect to host pitzer.osc.edu port 22: Operation timed out

Solutions: - Check if you're on OSU network or VPN - Verify OSC system status: https://www.osc.edu/resources/system-status - Try alternative cluster (Owens if Pitzer fails)

Permission Denied (publickey)¶

Problem: SSH key authentication fails

Permission denied (publickey,gssapi-keyex,gssapi-with-mic).

Solutions: - Verify SSH key is added to OSC: my.osc.edu → SSH Keys - Check key permissions:

chmod 600 ~/.ssh/id_ed25519
chmod 644 ~/.ssh/id_ed25519.pub
chmod 700 ~/.ssh

- Wait 10 minutes after adding key for propagation - Verify correct key with ssh-add -l

Connection Closes Unexpectedly¶

Problem: Connection drops after period of inactivity

Solution: Add to SSH config:

ServerAliveInterval 60
ServerAliveCountMax 3

SSH Key Not Working¶

Problem: Still prompted for password despite SSH key

Solutions: 1. Verify public key is on OSC:

ssh pitzer 'cat ~/.ssh/authorized_keys'

Check SSH config uses correct key:
```
IdentityFile ~/.ssh/id_ed25519
```
Test with verbose output:
```
ssh -v pitzer
```

Cannot Create SSH Config File¶

Windows Issue: ~/.ssh directory doesn't exist

Solution:

mkdir $HOME\.ssh