The Internet, as the biggest computer network is not always fill with good people. There is a lot of functionality built into these utilities, iptables being the most popular nowadays, but they require a decent effort on behalf of the user to learn and understand them. Its well-supported and popular in the Linux communityeven installed by default in a lot of distros. From Wikipedia, a definition is.
If youre running Ubuntu Linux, you will find ufw as a default firewall tool. It is more volatile in the process of converting from gas to liquid. UFW also known as Uncomplicated Firewall is an interface to iptables and is particularly well-suited for host-based firewalls. And is the perfect Paper Halloween Craft for kids. It is most popular firewall tool originating from Ubuntu. Once you have installed ufw you can configure this firewall from the terminal. As such, its a great way to get started securing your sever.