Installing ssh server

sudo apt-get install openssh-server

Setting up ssh connections without requiring a password

1. Copy public key from local machine to remote machine

   scp ~/.ssh/id_rsa.pub mythbox@c2:/tmp/jess.id_rsa.pub
   

2. Log in to remote machine and append public key to authorized_keys file

   ssh mythbox@c2
   cat /tmp/jess.id_rsa.pub >> .ssh/authorized_keys
   

Remove ssh key

If a server's IP address has changed, trying to connect via ssh will fail because the IP address stored against the server's key no longer matches. If you're sure there is no man-in-the-middle attack in play, you can remove the offending key

ssh-keygen -R <hostname>