Install ssh on the server:

apt-get install openssh-server

Generate a key pair (files id_rsa and id_rsa.pub) with a passphrase:

ssh-keygen

Edit the ssh configuration file:

vi /etc/ssh/sshd_config

In the file, make the following settings:

   PasswordAuthentication no
   PermitRootLogin without-password
   RSAAuthentication yes
   PubkeyAuthentication yes

Add the public key as an authorized key for root that can be used for login:

cat id_rsa.pub >> /root/.ssh/authorized_keys

That’s all for the server!

Now for the client. Copy the key pair into the folder ~/.ssh. Now you should be able to connect with:

ssh -i ~/.ssh/id_rsa root@server