To ensure you have consistent access to your server, block SSH traffic on port 22 by default.

If you want to place the rule at the beginning of the chain, simply do not supply a rule number. This option enables you to specify the exact location of the rule.

If you want to append the rule in another position, you have to use the -I option.

To append a new rule to the end of a chain, your iptables command will have to use the -A..

The order of the rules in iptables is important.

Things to Keep in Mindīefore you read ahead, here are some things you should keep in mind: On the other hand, you can also mix and match them to suit your specific needs. Remember, any of the commands given below can be used in isolation. It will help you get a better grasp of the rules you are implementing with the following commands. To follow the guide you will need to have a basic understanding of what iptables is and how it works. This guide will introduce some of the most essential iptables commands. Whenever a connection tries to establish itself with your system, the firewall will refer to these rules to determine what the next step in action should be. In this guide, we will discuss some of the common rules and commands that go with the iptables firewall. It is typically available by default on Linux systems. This means that it is software that allows you to configure a firewall on your system. Iptables is a command-line firewall utility.

Sudo iptables