CentOS7 [Manage firewall port command]

1. Check the firewall status:

firewall-cmd --state

2. Turn on the firewall:

systemctl start firewalld

3. Stop the firewall:

systemctl stop firewalld

4. Restart the firewall:

systemctl restart firewalld

5. Set up the firewall at startup:

systemctl enable firewalld

6. Disable starting the firewall at boot:

systemctl disable firewalld

7. Reload firewall rules:

firewall-cmd --reload

8. Open ports:

firewall-cmd --zone=public --add-port=<端口号>/tcp --permanent

9. Remove an open port:

firewall-cmd --zone=public --remove-port=<端口号>/tcp --permanent

10. View open ports:

firewall-cmd --zone=public --list-ports

If the netstat command is not found on CentOS 7, it may be because the net-tools package is not installed on the system. In newer CentOS 7 distributions, the net-tools package may have been deprecated, so you can try using the ss command instead.

1. View occupied ports:使用 ss 命令可以列出当前正在使用的端口和与之关联的进程。

ss -tuln

2. If you just want to see if a specific port is occupied, you can use the following command:

ss -tuln | grep <端口号>

Please make sure that you have sufficient permissions when executing the above command, either using sudo or running the command as root.