SYN攻击TIME_WAIT防御。

 #! /bin/bash

 /bin/netstat -anput | grep TIME_WAIT >time_wait.txt
 /bin/cat time_wait.txt |awk '{print $5}' |awk -F '[:]' '{print $1}' |sort|uniq -c |awk '{print $2"="$1;}' >wait_num.txt

 DEFINE=""
 for i in `/bin/cat  /root/wait_num.txt`
 do
     IP=`echo $i |awk -F= '{print $1}'`
     NUM=`echo $i|awk -F= '{print $2}'`
     if [ $NUM -gt $DEFINE ];then
         grep $IP /etc/sysconfig/iptables > /dev/null
         if [ $? -gt  ];then
           /sbin/iptables -I INPUT -s $IP -j DROP
           echo "`date` $IP($NUM) ----将该IP加入到防火墙中。。。" >> /var/log/scanner.log
       fi
     fi
 done