防火墙（firewall）

systemctl status firewalld 查看防火墙状态
systemctl start firewalld 开启防火墙
systemctl stop firewalld 关闭防火墙
firewall-cmd –permanent –zone=public –add-port=27017/tcp –permanent 开启指定端口
firewall-cmd –zone=public –remove-port=27017/tcp –permanent 关闭指定端口
firewall-cmd –permanent –zone=public –add-port=27017-30000/tcp –permanent 开启指定范围端口
firewall-cmd –permanent –zone=public –add-port=1-65535/tcp –permanent 开始所有端口
firewall-cmd –zone=public –remove-port=27017-30000/tcp –permanent 关闭指定范围端口
firewall-cmd –permanent –query-port=27017/tcp 查看端口是否开放
firewall-cmd –reload 重启防火墙
firewall-cmd –list-ports 查看已经开放的端口
iptables -L -n 查看规则，这个命令是和 iptables 的相同的
man firewall-cmd 查看帮助