Before we go into detail into detail about IPtables in Linux we first must explain what the technology behind it is. An IPTable is actually another name for a firewall in Linux. It is mostly in Linux derivatives in which it will come preinstalled in but sometimes you will have to use apt-get or something similar to install it. So now that you know that it is a firewall, you might be asking yourself what does a firewall do?
What does a Firewall do?
When you access the internet you do it through one of the many open ports that you have on your computer system. There can be several thousands of open ports on one computer alone. There are some ports that are used for special programs and there are other ports that are just there in case any program that is wishing to be networked or connect to the internet needs it. But you cannot just let these ports stay open by themselves. You need a way that is going to be able to guard the ports to make sure that no one from the outside is able to get in without your permission. That is where firewalls come into play. They allow you to guard the ports automatically and set up special permissions to keep people out of it.
And that is what IPTables do. You will hear the term a lot when people talk about Linux but you might not actually know what it means. IPTables simply means that the Linux based server has a firewall that surrounds it.
Now most of the time you will hear people say that having a firewall is mandatory. But not all security experts feel that way. There are some who feel that a firewall is overkill and it is really not needed. I say be on the safe side and keep a firewall installed on your server. It is better to be safe than sorry.