By default, on RHEL7/Centos7, Filewall uses filewalld services. If you want to use iptables on CentOS / RHEL 7 instead of firewalld, here is a quick solution.

As we all know that, CentOS / RHEL 7 both are completely systemd based, So here are few systemd related commands to disable firewalld and enable iptables service.

Testbed info:

# cat /etc/redhat-release
CentOS Linux release 7.2.1511 (Core)
# uname -a
Linux slvm01 3.10.0-327.el7.x86_64 #1 SMP Thu Nov 19 22:10:57 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

Disable Firewalld Service.

# systemctl mask firewalld

Stop Firewalld Service.

# systemctl stop firewalld

Install iptables service related packages.

# yum -y install iptables-services

Make sure service starts at boot:

# systemctl enable iptables

If you do not want ip6tables, You can skip following command.
# systemctl enable ip6tables

5. Now, Finally Let’s start the iptables services.

# systemctl start iptables

If you do not want ip6tables, You can skip following command.

# systemctl start ip6tables

Firewalld Service is now disabled and stop, You can use iptables.

You can add / remove rules as you were doing in previous releases of Red Hat / CentOS 5 and 6, check here for some examples