Beginner5 min read

Set up SSH keys and disable password logins

The single highest-value change you can make to a new server.

Last updated 1 August 2026

Generate a key

bash

ssh-keygen -t ed25519 -C "you@example.com"

Accept the default location and set a passphrase. The passphrase protects the key on your own machine; it is never sent anywhere.

bash

ssh-copy-id -i ~/.ssh/id_ed25519.pub root@203.0.113.24

Keep your current session open

Open a second terminal and confirm the key works before you change the configuration. If the change is wrong, the open session is how you undo it.

bash

sed -i 's/^#\?PasswordAuthentication.*/PasswordAuthentication no/' /etc/ssh/sshd_config
systemctl reload sshd

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