By default,
firewall rules are saved in the following two files in
/ etc / sysconfig / iptables and / etc / sysconfig / ip6tables
yum install iptables-services ## installation
systemctl enable iptables ## boot
systemctl restart iptables ## to restart the service
iptables -F ## to clear firewall rules
service iptables save ## to save the current fire safety rules before
systemctl disable iptables ## canceled boot
systemctl disable libvirtd .service ## disassociate service start-up
libvirtd service if you do not cancel the firewall rules, then empty the boot will be reduced before the next restart
Reference
redhat official website description details about iptables
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/security_guide/sect-security_guide-iptables
Iptables principle Detailed
https://www.cnblogs.com/ggjucheng/archive/2012/08/19/2646466.html