Start by saving your current iptables rules if there are any.
If you are using CentOS 6.2 or 6.5, save your current iptables rules with the following command:
/sbin/service iptables save
If you are using CentOS 7 the base installation does not include iptables-services. You will need to install it before your firewall is persistent through boots
yum install -y iptables-services systemctl enable iptables systemctl start iptables
To save your current rule set use the following command
That’s it! Your firewall rules are in place and protecting your server. Remember, you’ll need to edit the firewall rules later if you install other software or services.