To use the iptables service instead of firewalld, first disable firewalld by running the following command as root:

~]# systemctl disable firewalld # systemctl stop firewalld

Then install the iptables-service package by entering the following command as root:

~]# yum install iptables-services 

Then, to start iptables service, run the following commands as root:

  # touch /etc/sysconfig/iptables
  # touch /etc/sysconfig/ip6tables
  # systemctl start iptables
  # systemctl start ip6tables
  # systemctl enable iptables
  # systemctl enable ip6tables