Firewalld and iptables
PSA: if working with iptables on a RHEL 7 and you want to move to firewalld, don't uninstall iptables. Iptables actually acts as the go between netfilter and firewalld. Also, if you uninstall iptables you will be uninstalling applications that have rules associated with them. Stick with masking iptables and unmasking firewalld. You can uninstall iptables-services package safely, but never the iptables package.