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How SSH Keys Work in Linux šŸ”

How SSH Keys Work in Linux šŸ”

Learn how SSH public and private keys work in Linux, generate key pairs using ssh-keygen, and securely connect to remote servers and AWS EC2 instances using SSH key-based authentication.

How SSH Keys Work in Linux

1. What Are SSH Keys?

  • SSH (Secure Shell) allows secure access to remote Linux servers.
  • SSH key authentication uses a public and private key pair.
  • It is commonly used to access AWS EC2 instances and manage servers.

2. Private Key

  • Stored securely on your local machine.
  • Never share it with anyone.
  • Example: ~/.ssh/id_ed25519

3. Public Key

  • Shared with the remote server.
  • Stored in ~/.ssh/authorized_keys on the server.
  • Example: ~/.ssh/id_ed25519.pub

4. Generate SSH Keys

Run the following command:
1
ssh-keygen -t ed25519
  • Generates a public and private key pair.
  • You can set a passphrase for additional protection.

5. Copy the Public Key to the Server

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ssh-copy-id username@server-ip
  • Installs your public key on the remote server.
  • Requires an existing authentication method and suitable permissions.

6. Connect to the Server

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ssh username@server-ip
For AWS EC2:
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ssh -i my-key.pem ubuntu@<EC2-PUBLIC-IP>

7. How SSH Authentication Works

  • The client connects to the SSH server.
  • The server checks whether the public key is authorized.
  • The client proves possession of the matching private key.
  • If verification succeeds, the server authenticates the user.
  • SSH establishes an encrypted session.

8. Security Best Practices

  • Never share your private key.
  • Use a passphrase to protect your private key.
  • Set appropriate file permissions.
  • Allow SSH access only from trusted IP addresses.
  • Verify server host keys before trusting a connection.

Conclusion

SSH keys provide secure authentication for Linux servers without sending your private key over the network. They are essential for Linux administration, AWS EC2 access, and DevOps workflows.
# ssh# authorization# authentication# amazon-ec2# agentic-ai
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