linux网关之iptabels篇

rpm -qa |grep iptables   查看iptables是否安装。
若是没安装请去网上下载安装 或YUM install iptables
#!/bin/bash
iptables -F
iptables -X
iptables -t nat -F
iptables -t nat -X
iptables -P INPUT DROP

#default open port
ports="80 22 20 21 53"
for kill in $ports ; do
iptables -I INPUT -i eth0 -p tcp --sport $kill -j ACCEPT
iptables -I INPUT -i eth0 -p tcp --dport $kill -j ACCEPT
iptables -I INPUT -i eth0 -p udp --sport $kill -j ACCEPT
iptables -I INPUT -i eth0 -p udp --dport $kill -j ACCEPT

#OUT
iptables -I OUTPUT -p tcp --sport $kill -j ACCEPT
iptables -I OUTPUT -p tcp --dport $kill -j ACCEPT
iptables -I OUTPUT -p udp --dport $kill -j ACCEPT
iptables -I OUTPUT -p udp --sport $kill -j ACCEPT

#open ping
iptables -A INPUT -i eth0 -p icmp -j ACCEPT
echo 1 > /proc/sys/net/ipv4/ip_forward

#nat
iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -o ppp0 -j MASQUERADE   #adsl
iptables -t nat -A POSTROUTING -s 192.168.0.0/24 -o eth0 -j SNAT --to ip  #ip static
service iptables save
done