CentOS 6.x中安装iptables的简明步骤：
1、安装iptables
yum install iptables
2、编辑iptables配置文件
vi /etc/sysconfig/iptables
输入或者粘贴如下内容形成基础配置：
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT
3、启动iptables
service iptables start
4、设置开机后自动启动iptables
chkconfig iptables on