Cacher is the code snippet organizer for pro developers

cat ~/.ssh/id_rsa.pub | ssh user@machine "mkdir ~/.ssh; cat >> ~/.ssh/authorized_keys"

sudo vim /etc/ssh/sshd_config 
  PermitRootLogin yes -> no
  Port 22 -> other port
  Protocol 2
  
sudo /etc/init.d/ssh restarts

http://help.ubuntu.ru/wiki/ssh