Add A Firewall to Debian Linux with UFW

What is UFW?

The Uncomplicated Firewall (ufw, and gufw - a Graphical User Interface version of the same) is a frontend for iptables and is particularly well-suited for host-based firewalls. Ufw provides a framework for managing netfilter, as well as a command-line interface for manipulating the firewall. -https://wiki.debian.org/Uncomplicated%20Firewall%20%28ufw%29
  1. Log into the Debian device
  2. Run the following commands in a terminal window:
    # update software repositories
    sudo apt update
    # install ufw
    sudo apt install ufw -y
    # enable ufw
    sudo ufw enable
    # output the ufw status
    sudo ufw status
    # add some default firewall rules
    sudo ufw default deny incoming
    sudo ufw default allow outgoing
    # if a webserver is running, allow the incoming traffic
    sudo ufw allow 80/tcp
    sudo ufw allow 443/tcp
    # to allow incoming ssh connections, open port 22
    sudo ufw allow 22/tcp
    # output the ufw status
    sudo ufw status
    # to install a graphical user interface for ufw, install gufw
    sudo apt install gufw -y