安装的是centOS7 mini，apache httpd的80端口始终访问不了，发现是防火墙问题，网上查了很多方法，好像都没成功。
直接命令：service firewalld stop
1. Disable Firewalld Service.
systemctl mask firewalld
2. Stop Firewalld Service.
systemctl stop firewalld
3. Install iptables service related packages.
yum -y install iptables-services
4. Make sure service starts at boot:
systemctl enable iptables
# If you do not want ip6tables, You can skip following command.
systemctl enable ip6tables
5. Now, Finally Let’s start the iptables services.
systemctl start iptables
# If you do not want ip6tables, You can skip following command.
systemctl start ip6tables
Firewalld Service is now disabled and stop, You can use iptables.
