1. View firewall status
Enter the following command in the terminal:
```
systemctl status firewalld
```
If the status is displayed as "active", it means that the firewall has been activated; if the status is displayed as "inactive", it means that the firewall is not activated.
2. Start the firewall
Enter the following command in the terminal:
```
systemctl start firewalld
```
3. Stop the firewall
Enter the following command in the terminal:
```
systemctl stop firewalld
```
4. Boot up and start the firewall
Enter the following command in the terminal:
```
systemctl enable firewalld
```
5. Turn off the boot firewall
Enter the following command in the terminal:
```
systemctl disable firewalld
```
6. Add port
Enter the following command in the terminal:
```
firewall-cmd --zone=public --add-port=80/tcp --permanent
```
Among them, --zone can set the firewall area, --add-port can add ports, and --permanent can save the rules permanently.
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7. Delete port
Enter the following command in the terminal:
```
firewall-cmd --zone=public --remove-port=80/tcp --permanent
```
Among them, --zone can set the firewall zone, --remove-port can delete the port, and --permanent can save the rules permanently.
8. View the added ports
Enter the following command in the terminal:
```
firewall-cmd --zone=public --list-ports
```
Among them, --zone can set the firewall zone, and --list-ports can list the added ports.
9. View firewall rules
Enter the following command in the terminal:
```
firewall-cmd --list-all
```
This command can list all firewall rules.
The above is the tutorial for setting up the system firewall in CentOS7 system. If you want to protect your server, these operations are essential.