1.iptables -L

2.iptables -F   service iptables save or /etc/rc.d/init.d/iptables save 

3.iptables -A INPUT -p tcp --dport 22 -j ACCEPT (先保证ssh)

4.iptables -P INPUT DROP

5.iptables -P OUTPUT ACCEPT

6.iptables -P FORWARD DROP

7.添加需要的协议和端口：

eg1:   iptables -A INPUT -p icmp -j ACCEPT

eg2:   iptables-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT                 iptables-A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

eg3:　iptables -A INPUT -s 192.168.0.104 -p tcp --dport 22 -j ACCEPT　　　　iptables -D INPUT -p tcp --dport 22 -j ACCEPT

iptables初始化