Connect with SSH

Instances are accessed through key-based SSH authentication. This page documents connection requirements, command format, and troubleshooting expectations.

Connection prerequisites

• A running instance
• A private key matching the public SSH key configured for that instance
• Network access to the instance endpoint

Connection parameters

Required SSH parameters:

• Endpoint: host or IP exposed for the instance
• Username: image-dependent default user
• Private key path: local key file corresponding to assigned public key

Instance details page provides endpoint and identity metadata required for connection validation.

SSH configuration

Prerequisites

Ensure you have socat installed for SSH tunneling:

# macOS
brew install socat

# Ubuntu/Debian
sudo apt-get install socat

# CentOS/RHEL
sudo yum install socat

SSH config setup

Add the following to your ~/.ssh/config file for easier connection management:

Host dev-*
  User root
  ProxyCommand socat - PROXY:dev.dc2.dcptunnel.net:%h:%p,proxyport=5002

Direct connection command

ssh -i ~/.ssh/your-key.pem <username>@<instance-endpoint>

Common image usernames

• Ubuntu: ubuntu
• Debian: debian
• CentOS: centos

Session validation

After connection, validate host access with basic system queries:

hostname
uname -a

Successful command output confirms remote shell access and host reachability.

Troubleshooting

Permission denied (publickey)

• Verify the private key file matches the SSH key registered in your account
• Ensure correct key permissions: chmod 600 ~/.ssh/your-key.pem
• Confirm the key used for instance launch is still available locally
• Try adding verbose output for debugging: ssh -vvv -i ~/.ssh/your-key.pem <username>@<instance-endpoint>

Connection timed out

• Verify instance is in Running state
• Check endpoint is correct from instance details page
• Verify network/firewall allows outbound SSH (port 22)
• Try again after waiting a minute—new instances may need time to fully initialize

Instance unreachable

• Confirm instance status is Running, not Stopped or Provisioning
• Check if instance has an endpoint assigned
• Verify you're using the correct username for the OS image (see Common image usernames)
• For persistent issues, try rebooting the instance from the console

Permission denied (no other methods available)

• Ensure the account SSH key hasn't been deleted
• Regenerate and register a new SSH key if needed
• Contact support if unable to resolve

Next steps

• Manage SSH Keys
• Manage Snapshots