Lab 5.1: Log in from server1 to server2 with an SSH key

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Doel

Set up key-based login so that student on server1 can log in to server2 without a password, and run commands there.

Both machines run and can reach each other by name (see lab 8.1, or use the IP addresses).
The user student exists on both machines with a password.

On server1, as student, make an Ed25519 key pair. Use an empty passphrase for this lab.
Copy the public key to student on server2.
Log in to server2 without a password and show the hostname.
From server1, run the command uptime on server2 without opening an interactive shell.
Check that the permissions of ~/.ssh and ~/.ssh/authorized_keys on server2 are correct.

$ssh -o BatchMode=yes student@server2 hostname
$ssh student@server2 'stat -c "%a %n" ~/.ssh ~/.ssh/authorized_keys'

The first command prints server2.example.com and does not ask for a password (BatchMode makes it fail instead of asking).
The permissions are 700 for ~/.ssh and 600 for authorized_keys.

Toon de hints

Toon de oplossing

Make the key.

$ssh-keygen -t ed25519 -N "" -f ~/.ssh/id_ed25519

Check and, if needed, fix the permissions on server2.

$ssh student@server2 'chmod 700 ~/.ssh; chmod 600 ~/.ssh/authorized_keys'