[K12OSN] how to set up passwordless ssh access

[Krsnendu dasa]

I have run ssh-keygen on my home Ubuntu computer.
Then I pasted the contents of id_rsa.pub into ~/.ssh/authorized_keys
on the K12LTSP server.

When I ssh in it still prompts me for my password.

What else do have have to do so I don't have to enter my password
every time I ssh in?