Just installed CentOS 7 on my Virtual machine and realized that, Firewalld is bit complicated as I am using iptables firewall from many years. So decided not to use firewalld at least as of now and wanted to continue with iptables commands as I was using in RHEL / CentOS 5 and 6. I thought iptables will not be there and I will have to deal with firewalld but a little small trick in RHEL7 takes me to the solution which I wanted and I found that I can still use the iptables by disabling firewalld service. So, If you are in same condition as mine and you want to use iptables on CentOS / RHEL 7 instead of firewalld, Please follow this howto.