Disable Firewalld Service.
[root@rhel-centos7-tejas-barot-linux ~]# systemctl mask firewalld
Stop Firewalld Service.
[root@rhel-centos7-tejas-barot-linux ~]# systemctl stop firewalld
Install iptables service related packages.
[root@rhel-centos7-tejas-barot-linux ~]# yum -y install iptables-services
Make sure service starts at boot:
[root@rhel-centos7-tejas-barot-linux ~]# systemctl enable iptables
Now, Finally Let’s start the iptables services.
[root@rhel-centos7-tejas-barot-linux ~]# systemctl start iptables