vastai-security-basicsClaude Skill

Vast.ai Security Basics

Overview

Security best practices for Vast.ai API keys, SSH access to GPU instances, data protection on rented hardware, and credential management. Vast.ai instances run as root on shared hardware, requiring careful attention to data lifecycle.

Prerequisites

• Vast.ai account with API key
• Understanding of SSH key management
• Secrets manager available (optional but recommended)

Instructions

Step 1: API Key Management

# Never commit API keys to git
echo '.vast_api_key' >> .gitignore
echo '.env' >> .gitignore

# Use environment variables, not files in repos
export VASTAI_API_KEY="$(vault kv get -field=api_key secret/vastai)"

# Rotate keys periodically at cloud.vast.ai > Account > API Keys

# Fail fast on missing credentials
import os

def get_api_key():
    key = os.environ.get("VASTAI_API_KEY")
    if not key:
        key_file = os.path.expanduser("~/.vast_api_key")
        if os.path.exists(key_file):
            key = open(key_file).read().strip()
    if not key:
        raise ValueError("VASTAI_API_KEY not set and ~/.vast_api_key not found")
    return key

Step 2: SSH Key Security

# Generate a dedicated key pair for Vast.ai instances
ssh-keygen -t ed25519 -f ~/.ssh/vastai_key -C "vastai-instances" -N ""

# Upload public key at cloud.vast.ai > Account > SSH Keys

# Use the dedicated key for connections
ssh -i ~/.ssh/vastai_key -p PORT root@HOST

Step 3: Data Protection on Shared Hardware

def secure_cleanup(instance_id, ssh_host, ssh_port):
    """Securely wipe data before destroying an instance."""
    import subprocess
    # Overwrite sensitive files before instance destruction
    subprocess.run([
        "ssh", "-p", str(ssh_port), "-o", "StrictHostKeyChecking=no",
        f"root@{ssh_host}",
        "rm -rf /workspace/data /workspace/checkpoints /root/.ssh/authorized_keys; "
        "history -c"
    ], check=True)
    # Then destroy
    subprocess.run(["vastai", "destroy", "instance", str(instance_id)], check=True)

Step 4: Network Security

• Use SSH tunnels for any services exposed on instances
• Never expose ports with sensitive data to the public internet
• Transfer data over SCP/SFTP, not unencrypted HTTP
• Encrypt training data before upload; decrypt on-instance

Step 5: Credential Rotation Checklist

• API key rotated every 90 days
• SSH keys dedicated to Vast.ai (not shared with production)
• Old SSH keys removed from cloud.vast.ai after rotation
• .vast_api_key file permissions set to 600
• No API keys in shell history (export from a sourced file, not typed)

Output

• API key loaded from environment or secrets manager
• Dedicated SSH key pair for Vast.ai instances
• Secure cleanup before instance destruction
• Network security guidelines
• Credential rotation checklist

Error Handling

Error	Cause	Solution
API key leaked in git	Committed .env or key file	Rotate key immediately; add to .gitignore
SSH key rejected	Wrong key or not uploaded	Verify key is at cloud.vast.ai > SSH Keys
Data left on destroyed instance	Forgot to clean up	Use secure_cleanup() before destroy
Key file world-readable	Wrong permissions	chmod 600 ~/.vast_api_key ~/.ssh/vastai_key

Resources

• Vast.ai CLI Security
• SSH Key Management

Next Steps

For production deployment checklist, see vastai-prod-checklist.

Examples

Vault integration: Load API key from HashiCorp Vault at runtime, never write to disk, and use SSH agent forwarding for key management.

Ephemeral instances: Treat every Vast.ai instance as throwaway. Never store persistent state on instances; always upload data, process, download results, and destroy.