Dette scriptet er ikke testet samt DoS bør hindres på kernel nivå!

A simple rule-based DoS attack-prevention shell script. However, the proposed shell script is not a perfect tool for preventing DoS attacks, but a powerful tool for alleviating DoS attacks overheads of the Linux servers significantly.

#!/bin/bash
rm -f ttt
touch tmp
# disabled IPs can be obtained from /etc/sysconfig/iptables
grep DROP /etc/sysconfig/iptables|awk '{print $5}' >tmp
# ------------------------ DoS attacks rule -------------------------
#identity mismatch in secure
grep Did /var/log/secure|awk '{print $12}' >>tmp
#Invalid user
grep "Invalid user" /var/log/secure|awk '{print $10}' >>tmp
# Maximum login
grep "Maximum login" /var/log/secure|awk '{print $7}'|sed 's/.*[(.*)])/1/g' >>tmp
#
# ------------------ reduce redundant IPs from tmp file -------------
size=`/usr/bin/wc tmp|awk '{print $1}'`
i=0
while test $i -lt $size
do
      us=`sed -n 1p tmp`
      sed /$us/d tmp >tmps
      echo $us >>ttt
      cp -f tmps tmp
      size=`/usr/bin/wc tmp|awk '{print $1}'`
done
rm -f tmp tmps temp0 temp
#
# ------------------ activate detected IPs --------------------------
size=`wc ttt|awk '{print $1}'`
size=`expr $size + 1`
/sbin/iptables -F
i=1
while test $i -lt $size
do
        ip=`sed -n "$i"p ttt`
        i=`expr $i + 1`
/sbin/iptables -A INPUT -s $ip -j DROP
done
# -----------------end of shell script test -------------------------