Centos7 closes and restarts the system firewall and opens firewall ports

The default firewall of the Linux system installed by some people is not iptables, but firewall, then the firewall must be turned off in the following way.

>>>Turn off firewall

systemctl stop firewalld.service #stop firewall
systemctl disable firewalld.service #Prohibit firewall from starting

>>>Open the port

firewall-cmd --zone=public --add-port=80/tcp --permanent

command meaning

--zone #scope
--add-port=80/tcp #Add port, the format is: port/communication protocol
--permanent #Permanent effect, invalid after restart without this parameter

>>>Restart firewall

firewall-cmd --reload

Other common commands:

 firewall-cmd --state ##Check the firewall status, whether it is running
firewall-cmd --reload ##Reload the configuration, for example, after adding rules, you need to execute this command
firewall-cmd --get-zones ##List supported zones
firewall-cmd --get-services ##List the supported services, the services in the list are allowed
firewall-cmd --query-service ftp ##Check whether the ftp service is supported, return yes or no
firewall-cmd --add-service=ftp ##Temporarily open ftp service
firewall-cmd --add-service=ftp --permanent ##Permanently open ftp service
firewall-cmd --remove-service=ftp --permanent ##Permanently remove the ftp service
firewall-cmd --add-port=80/tcp --permanent ##Add port 80 permanently
iptables -L -n ##View the rules, this command is the same as iptables
man firewall-cmd ##View help

For more commands, use firewall-cmd --help to view the help file

>>> CentOS 7.0 uses firewall as the firewall by default, and iptables must be reset

1. Turn off the firewall directly

systemctl stop firewalld.service #stop firewall
systemctl disable firewalld.service #Prohibit firewall from starting

2. Set iptables service

yum -y install iptables-services
If you want to modify the firewall configuration, such as adding firewall port 3306
vi /etc/sysconfig/iptables
add rules
-A INPUT -m state --state NEW -m tcp -p tcp --dport 3306 -j ACCEPT

After saving and exiting
systemctl restart iptables.service #Restart the firewall to make the configuration take effect
systemctl enable iptables.service #Set the firewall to start at boot