CentOS 7之后默認使用的是firewall作為防火牆，這里改為iptables防火牆,並開啟80端口、3306端口。
1、關閉firewall：
systemctl stop firewalld.service #停止firewall systemctl disable firewalld.service #禁止firewall開機啟動
2、安裝iptables防火牆
yum install iptables-services #安裝
vi /etc/sysconfig/iptables #編輯防火牆配置文件
內容為：
# Firewall configuration written by system-config-firewall # Manual customization of this file is not recommended. *filter :INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0] -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT -A INPUT -p icmp -j ACCEPT -A INPUT -i lo -j ACCEPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 8888 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 9999 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 21 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 3306 -j ACCEPT -A INPUT -j REJECT --reject-with icmp-host-prohibited -A FORWARD -j REJECT --reject-with icmp-host-prohibited COMMIT
3、重啟、開機啟動iptables
systemctl restart iptables.service #最后重啟防火牆使配置生效
systemctl enable iptables.service #設置防火牆開機啟動