Install Firewall Ubuntu Univeral Firewall (GUFW)

Install Universal Firewall GUI For Ubuntu

With Ubuntu, the Universal Firewall(ufw) is install by default. You can run the command sudo ufw status to check it out. It is most like disabled.

If you want a simple gui for basic firewall rules, you can install the gui version ufgw. However, you need to have the the Universe repository enabled in order to install ufgw, which could be enabled by default. To install ufgw,

1) Open the terminal: 
2) Run the command: sudo apt-get install gufw 
3) When necessary, select 'Y' to complete the installation.

To use the Firewall and make rules,

1) Open System Settings >Firewall Configuation  or  Dash Home >Look for gufw >Select Firewall Configuration 
2) Make rules. The image below shows a simple rule to allow incoming traffic to receive http requests from port 80; the web server.