Access
An SSH key lets you log into your server from your own computer's terminal,
and lets tools like scp, rsync, VS Code and
Git talk to it. You do not need one to use your server — the terminal on
your account page always works — but everything is easier with one.
A key comes in two halves that are generated together. The private half stays on your computer and never leaves it. The public half is the one you give us; it goes into a file on your server that says "whoever holds the matching private half may log in".
That is why it replaces a password rather than being one. Nothing secret crosses the network, so there is nothing for us to lose, nothing for you to type into a fake login page, and nothing to guess.
.pub. The other file — same name, no extension — is your
private key, and anyone who has it can log in as you. If you paste a
private key here we reject it, but change it anyway if that happens.
If you have used SSH before you may already have a key. Check first — making a second one for no reason is the usual way people end up confused about which is which.
One line, starting with ssh-ed25519 or ssh-rsa.
It replaces any key already on the machine rather than adding to it, so
an old laptop stops working the moment you put a new key here — which is
what you want when the old one is gone.
Your server sits on a private network today and has no public address, so
an ssh command from your laptop cannot reach it yet — the key
is installed and correct, but there is no route to the door. Use the
terminal on your account page in the meantime.
The key is kept on your account as well as on the machine, so wiping the server puts it straight back. It is deleted with your account.