SSH Keys

An SSH key pair lets your device prove its identity without sending your account password for each login.

Private key: stays secret on your computer. Never send it anywhere.
Public key: can be copied to a server.

Before generating a key, read your prompt. A prompt ending in @lf2607 means you are on the server. Run exit, then use a terminal on your own computer.

ssh-keygen

Only create a key when ~/.ssh/id_ed25519.pub does not already exist or its private key is no longer safe. Accept the defaults to create:

~/.ssh/id_ed25519: private key.
~/.ssh/id_ed25519.pub: public key.

Choose a passphrase for a newly created private key. Reuse a safe existing key rather than creating another one for this course.

On macOS or Linux, type ssh-copy-id followed by the address from your personal registration command, then enter your password when prompted. In Windows Terminal or PowerShell, Get-Content ~/.ssh/id_ed25519.pub is a preview-only command: it displays the public key and changes nothing. Copy that one line, use the same personal command to start a password SSH session, then run:

mkdir -p ~/.ssh
chmod 700 ~/.ssh
cat >> ~/.ssh/authorized_keys

chmod 700 ~/.ssh means only you can enter or change that directory. Paste the one line printed locally by Get-Content ~/.ssh/id_ed25519.pub, press Enter, then press Ctrl-D. Run chmod 600 ~/.ssh/authorized_keys so only you can read or change the key list, then exit, reconnect with the same personal command, and run whoami. This appends the key without replacing existing recovery keys. Your device uses the private key to prove it has the matching public key installed on the server.

SSH Keys

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