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SSH Key Management: A Complete Guide
Generating SSH Keys
# Ed25519 (recommended — fast, secure, short keys)ssh-keygen -t ed25519 -C "your@email.com"
# RSA 4096 (broader compatibility)ssh-keygen -t rsa -b 4096 -C "your@email.com"You’ll be prompted for a file location and passphrase. Always use a passphrase for production keys.
Managing Multiple Keys
Edit ~/.ssh/config to assign different keys to different hosts:
# Personal GitHubHost github.com HostName github.com User git IdentityFile ~/.ssh/id_ed25519_personal
# Work GitLabHost gitlab.work.com HostName gitlab.work.com User git IdentityFile ~/.ssh/id_ed25519_work
# Production serverHost prod HostName 203.0.113.50 User deploy IdentityFile ~/.ssh/id_ed25519_prod Port 2222Now you can simply ssh prod instead of typing the full command.
Adding Keys to the SSH Agent
# Start the agenteval "$(ssh-agent -s)"
# Add your keyssh-add ~/.ssh/id_ed25519
# On macOS, add to Keychainssh-add --apple-use-keychain ~/.ssh/id_ed25519Copying Public Keys to Servers
# The easy wayssh-copy-id -i ~/.ssh/id_ed25519.pub user@server
# Manual way (if ssh-copy-id is unavailable)cat ~/.ssh/id_ed25519.pub | ssh user@server \ "mkdir -p ~/.ssh && cat >> ~/.ssh/authorized_keys"Security Best Practices
- Use Ed25519 keys — they’re more secure and performant than RSA
- Always set a passphrase — protects you if your key file is stolen
- Set proper permissions:
chmod 700 ~/.sshchmod 600 ~/.ssh/id_ed25519chmod 644 ~/.ssh/id_ed25519.pubchmod 600 ~/.ssh/config
- Disable password authentication on servers:
/etc/ssh/sshd_config PasswordAuthentication noPubkeyAuthentication yes - Rotate keys periodically — treat them like passwords
- Use
ssh-agentforwarding sparingly — it can be a security risk
Troubleshooting
# Test connection with verbose outputssh -vT git@github.com
# Check which key is being usedssh -v user@server 2>&1 | grep "Offering"
# Fix permission issueschmod 600 ~/.ssh/id_ed25519SSH keys are the foundation of secure remote access. Take the time to set them up properly, and you’ll save yourself countless headaches.
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SSH Key Management: A Complete Guide
https://blog.levifree.com/posts/ssh-key-management/ Some information may be outdated
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