ssh

*server*
useradd username
passwd username
su username
*host*
cat ~/.ssh/id_rsa.pub | ssh username@remote_host "mkdir -p ~/.ssh && touch ~/.ssh/authorized_keys && chmod -R go= ~/.ssh && cat >> ~/.ssh/authorized_keys"

*Disable Password Authentication on your Server*
sudo vi /etc/ssh/sshd_config
  ...
  PasswordAuthentication no
  PubkeyAuthentication yes
  ...
sudo systemctl restart sshd.service