Start up the terminal on your system Install gufw - Graphical firewall configuration utility in Ubuntu Linux $ sudo apt-get install gufw <enter> Now you can use the GUI to configure your firewall in Ubuntu Linux.
To test if your computer firewall is protecting you on the internet, see this post. Ubuntu installs a firewall when you install it to your computer. However, the firewall is not active. To activate the firewall, open a terminal window on your system, then enter the commands in italics as shown below: $ sudo ufw … Continue reading Firewall in Ubuntu Linux
You can test your firewall using Shields Up! at https://www.grc.com/x/ne.dll?bh0bkyd2. It lets you know if you have any ports open that are listening to connections.