Shell防DDOS攻击原理

#!/bin/sh
  #date:2015-12-13
  #filename:fang-DOS.sh 
  #version:v1.0
  while true
  do
      #awk '{print $1}' access_2015-12-15.log|grep -v "^$"|sort|uniq -c >/tmp/tmp.log
      netstat -an|grep EST|awk -F '[ :]+' '{print $6}'|sort|uniq -c >/tmp/tmp.log 
      exec </tmp/tmp.log
      while read line
      do
          ip=`echo $line|awk '{print $2}'`
          count=`echo $line|awk '{print $1}'`
          if [ $count -gt 3 ] && [ `iptables -L -n|grep "$ip"|wc -l` -lt 1 ]
            then 
                iptables -I INPUT -s $ip -j DROP
                echo "$line is dropped" >>/tmp/droplist.log
          fi
      done
         sleep 5 
   done

​

python, equal to anything！