CentOS 7.0默认使用的是firewall作为防火墙

1、关闭firewall：

systemctl stop firewalld.service#停止firewall

systemctl disable firewalld.service#禁止firewall开机启动

2、安装iptables防火墙

yum install iptables-services#安装

编辑防火墙配置文件打开指定的端口号使用udp协议打开52100端口：

vi/etc/sysconfig/iptables

# 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 3306 -j ACCEPT

-A INPUT -j REJECT --reject-with icmp-host-prohibited

-A FORWARD -j REJECT --reject-with icmp-host-prohibited

COMMIT

:wq!#保存退出

systemctl restart iptables.service#最后重启防火墙使配置生效

systemctl enable iptables.service#设置防火墙开机启动