systemctl start firewalld # 启动
systemctl stop firewalld # 停止
systemctl enable firewalld # 启用自动启动
systemctl disable firewalld # 禁用自动启动
systemctl status firewalld # 查看状态  或者
firewall-cmd --state #查看状态
firewall-cmd --list-ports #查看端口开放列表

hostnamectl status

hostnamectl set-hostname centos