Main / Linux / Iptables 防火墙

一个Iptables例子

#!/bin/sh
IPTABLES="/sbin/iptables"
echo "1" > /proc/sys/net/ipv4/ip_forward
$IPTABLES -P INPUT DROP
$IPTABLES -P FORWARD DROP
$IPTABLES -P OUTPUT DROP
$IPTABLES -F
$IPTABLES -X

$IPTABLES -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A INPUT -p tcp --dport 22 -j ACCEPT
$IPTABLES -A INPUT -p tcp --dport 80 --tcp-flags SYN,ACK,FIN,RST SYN -m limit --limit 30/m --limit-burst 2 -j ACCEPT

$IPTABLES -A OUTPUT -p tcp -s 127.0.0.1 -j ACCEPT
$IPTABLES -A OUTPUT -p tcp -s 192.168.1.102 -j ACCEPT
$IPTABLES -A OUTPUT -p udp -s 127.0.0.1 -j ACCEPT
$IPTABLES -A OUTPUT -p udp -s 192.168.1.102 -j ACCEPT

$IPTABLES -A INPUT -p tcp --syn -j DROP

如果某IP在80端口连接数过大，就DROP掉

netstat -an | grep :80 | awk -F: '{ print $8 }' | sort | uniq -c | awk -F\  '$1>10 && $2!="" { print $2 }' >> /etc/fw.list
less /etc/fw.list | sort | uniq -c | awk -F\  '$2!="" { print $2 }' > /etc/fw.list2
less /etc/fw.list2 > /etc/fw.list
while read line
      do
      t=`echo "$line"`
      $IPTABLES -A INPUT -p tcp -s $t -j DROP
done < /etc/fw.list2

IP转发

$IPTABLES -A INPUT -p tcp --dport 20002 -j ACCEPT
$IPTABLES -A INPUT -d 172.16.204.7 -p tcp -m tcp --dport 20002 -i eth0 -j ACCEPT
$IPTABLES -t nat -A PREROUTING -d 211.100.39.44 -p tcp -m tcp --dport 20002 -j DNAT --to-destination 172.16.204.7:20002
$IPTABLES -t nat -A POSTROUTING -d 172.16.204.7 -p tcp -m tcp --dport 20002 -j SNAT --to-source 10.6.39.44

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