SSH to a login to Ubuntu Core on Raspberry Pi3 requires password

Question

I've just installed Ubuntu Core 16 on a Raspberry Pi 3. When I login using my private ssh key, it always needs a password.

I installed it by following the official provided guide.

Answer 1

For someone who might get the same confusion as me: I also followed the tutorial from Ubuntu website, but in the final step, log in via ssh, I was required to enter a password.

Load key "/home/chin/.ssh/ubuntucore_rsa": bad permissions debug1: Next authentication method: password username@192.168.1.108's password:

This problem was caused by my private rsa file was poorly protected. So I used the following command to modify its permission

sudo chmod 400 ~/.ssh/ubuntucore_rsa

Then I could login to Ubuntu Core via ssh.