防火墙

# 查看状态 active(running) 打开了；inactive(dead) 关闭了。
systemctl status firewalld.service
# 临时关闭
sudo systemctl stop firewalld
# 临时打开
sudo systemctl start firewalld
# 禁止开机自启
systemctl disable firewalld.service
# 启用开机自启
systemctl enable firewalld.service