Enabling iptables Firewall

Prerequisites

• A burning, unquenchable desire to disable the default firewalld application, and enable iptables.

Introduction

firewalld is now the default firewall on Rocky Linux. firewalld was nothing more than a dynamic application of iptables using xml files that loaded changes without flushing the rules in CentOS 7/RHEL 7. With CentOS 8/RHEL 8/Rocky 8, firewalld is now a wrapper around nftables. It is still possible, however, to install and use straight iptables if that is your preference. To install and run straight iptables without firewalld you can do so by following this guide. What this guide will not tell you is how to write rules for iptables. It is assumed that if you want to get rid of firewalld, you must already know how to write rules for iptables.

Disabling firewalld

You can't really run the old iptables utilities alongside firewalld. They're just not compatible. The best way to get around this is to disable firewalld entirely (no need to unistall it unless you want to), and reinstall the iptables utilities. Disabling firewalld can be done using these commands:

Stop firewalld:

systemctl stop firewalld

Disable firewalld so it won't start on boot:

systemctl disable firewalld

Mask the service so that it can't be found:

systemctl mask firewalld

Installing And Enabling iptables Services

Next we need to install the old iptables services and utilities. This is done with the following:

dnf install iptables-services iptables-utils

This will install everything that is needed to run a straight iptables rule set.

Now we need to enable the iptables service to make sure that it starts on boot:

systemctl enable iptables

Conclusion

You can return to using straight iptables if you prefer it over firewalld. You can return to using the default firewalld by simply reversing these changes.