Log in to a server without a password
Make the Cardputer's own SSH key, put its public half on a server, and connect with no password to type.
Typing a password on a small keyboard, every time, gets old. With a key, the server recognises the device.
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On the Cardputer, open SSH → This device's key and press Enter. It makes the key and shows its public half: one line starting with
ssh-ed25519. -
Get that line to the server. It was also written to the card as
/ssh/id_ed25519.pub, so the easy way is the phone: in Storage press w, open the page (Move files with your phone) and download the file. Or log in to the server with your password, from the Cardputer or anything else, and paste it. -
On the server, add the line to the end of
~/.ssh/authorized_keysof the user you log in as:cat id_ed25519.pub >> ~/.ssh/authorized_keys chmod 600 ~/.ssh/authorized_keys -
On the Cardputer, connect: SSH → New connection,
user@host. It logs in without asking for anything.
If it still asks for a password
| Check | How |
|---|---|
| The line is whole, on one line | ssh-ed25519, a long word, then roro9stack |
| The file's permissions | chmod 700 ~/.ssh and chmod 600 ~/.ssh/authorized_keys: OpenSSH ignores a file others can write |
| It is the right user's file | the user of user@host |
| The server takes keys | PubkeyAuthentication yes in its sshd_config (the default) |
| You made a new key since | a new key replaces the old one: put the new line on the server |
Worth knowing
The private half never leaves the device and has no passphrase: whoever holds the Cardputer can log in wherever its key is accepted. If the device is lost, remove its line from authorized_keys on your servers. More in the SSH page.