Execution: ` firewall CMD — zone = public — add port = 8081/TCP — permanent`

The following error is prompted

`FirewallD is not running`

  The reason is that the firewall is not turned on

solve:

1. Check firewall status:

Execute ` systemctl status firewalld`

  Display dead status

2. Modify firewall status

Execute ` systemctl start firewalld`

Re execution   ` Systemctl status firewalld ` check whether the modification is successful

3. Reopen the port

`Firewall CMD — zone = public — add port = 8081/TCP — permanent ‘

4. Turn off the firewall, or you won’t be able to access it

`systemctl stop firewalld`