Problem:
When trying to start/enable the iptables daemon you receive the errors:
# systemctl enable iptables Failed to issue method call: Access denied
# systemctl start iptables Failed to start iptables.service: Unit iptables.service failed to load: No such file or directory.
Solution:
Starting with RHEL 7, firewalld is introduced and by default the iptables package is not installed on the system. This is done to avoid conflict in running both iptables and firewalld.
Make sure you have the iptables-services package installed. This legacy package provides the systemd scripts for the previous iptables invocation. This package is not always installed, depending on your installation choices when you installed (or upgraded).
The package “iptables-services” needs to be installed before you are able to start the service.
# yum install iptables-services