With RHEL 7 / CentOS 7, firewalld was introduced to manage iptables. IMHO, firewalld is more suited for workstations than for server environments.

It is possible to go back to a more classic iptables setup. First, stop and mask the firewalld service:

systemctl stop firewalld
systemctl mask firewalld 

Then, install the iptables-services package:

yum install iptables-services 

Enable the service at boot-time:

systemctl enable iptables 

Managing the service

systemctl [stop|start|restart] iptables 

Saving your firewall rules can be done as follows:

service iptables save 

or

/usr/libexec/iptables/iptables.init save