How to set up SSH key authentication

SSH keys are a pair of files: one public (on the server) and one private (with you). They are far more secure than passwords and eliminate the risk of brute-force attacks.

1. Generate a key pair (on your computer)

ssh-keygen -t ed25519 -C "[email protected]"

Press Enter for the default location and, optionally, set a passphrase for the key.

2. Copy the public key to the server

ssh-copy-id root@SERVER_IP

Or manually, add it to ~/.ssh/authorized_keys on the server.

3. Test the connection

ssh root@SERVER_IP

You should log in without a password.

4. Disable passwords (once the key works)

In /etc/ssh/sshd_config:

PasswordAuthentication no

systemctl restart ssh

Important

Keep the private key safe and never share it. Continue with disabling root login for extra security.