Create the new public and private keys, then rename and copy and delete the public key:

ssh-keygen
cd ~/.ssh/
cp id_rsa.pub authorized_keys
rm -rf id_rsa.pub

Copy the key cat id_rsa to your computer and then deleterm -rf id_rsa. Only with this key will you have access to the server.

The setting below is to extend bash's auto-complete functions.

sudo nano /etc/bash.bashrc

# enable bash completion in interactive shells
if ! shopt -oq posix; then
if [ -f /usr/share/bash-completion/bash_completion ]; then
. /usr/share/bash-completion/bash_completion
elif [ -f /etc/bash_completion ]; then
. /etc/bash_completion
fi
fi

sudo reboot

sudo nano /etc/ssh/sshd_config

Look for the “PasswordAuthentication” section in this configuration file, and change its value to “No”.

PasswordAuthentication no

Ready! Once the server restarts you will only have access with the private key.

Before you start working, update the packages to the latest versions.

sudo apt update; sudo apt upgrade -y

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Bonus: install htop for an extended version of the top, sl to liven up your life and ncdu for disk space analysis

sudo apt install htop sl ncdu -y