超级NB的防DDOS(小量级)攻击的脚本

# tree /usr/local/ddos/
/usr/local/ddos/
├── ddos.conf
├── ddos.sh
├── ignore.ip.list
└── LICENSE

0 directories, 4 files

# ll /usr/local/sbin/ddos 
lrwxrwxrwx 1 root root 23 Sep 13 15:36 /usr/local/sbin/ddos -> /usr/local/ddos/ddos.sh
# cat /etc/cron.d/ddos.cron 
SHELL=/bin/sh
*/1 * * * * root /usr/local/ddos/ddos.sh >/dev/null 2>&1

查看关键的几个脚本:

# cat ddos.conf 
##### Paths of the script and other files
PROGDIR="/usr/local/ddos"
PROG="/usr/local/ddos/ddos.sh"
IGNORE_IP_LIST="/usr/local/ddos/ignore.ip.list"
CRON="/etc/cron.d/ddos.cron"
APF="/etc/apf/apf"
IPT="/sbin/iptables"

##### frequency in minutes for running the script
##### Caution: Every time this setting is changed, run the script with --cron
#####          option so that the new frequency takes effect
FREQ=1

##### How many connections define a bad IP? Indicate that below.
NO_OF_CONNECTIONS=150

##### APF_BAN=1 (Make sure your APF version is atleast 0.96)
##### APF_BAN=0 (Uses iptables for banning ips instead of APF)
#APF_BAN=1
APF_BAN=0

##### KILL=0 (Bad IPs are'nt banned, good for interactive execution of script)
##### KILL=1 (Recommended setting)
KILL=1

##### An email is sent to the following address when an IP is banned.
##### Blank would suppress sending of mails
EMAIL_TO="xxx@xxx.com"

##### Number of seconds the banned ip should remain in blacklist.
BAN_PERIOD=600

# cat ddos.sh 
#!/bin/sh
##############################################################################
# DDoS-Deflate version 0.6 Author: Zaf <zaf@vsnl.com>                        #
##############################################################################
# This program is distributed under the "Artistic License" Agreement         #
#                                                                            #
# The LICENSE file is located in the same directory as this program. Please  #
#  read the LICENSE file before you make copies or distribute this program   #
##############################################################################
load_conf()
{
    CONF="/usr/local/ddos/ddos.conf"
    if [ -f "$CONF" ] && [ ! "$CONF" ==    "" ]; then
        source $CONF
    else
        head
        echo "$CONF not found."
        exit 1
    fi
}

head()
{
    echo "DDoS-Deflate version 0.6"
    echo "Copyright (C) 2005, Zaf <zaf@vsnl.com>"
    echo
}

showhelp()
{
    head
    echo 'Usage: ddos.sh [OPTIONS] [N]'
    echo 'N : number of tcp/udp    connections (default 150)'
    echo 'OPTIONS:'
    echo '-h | --help: Show    this help screen'
    echo '-c | --cron: Create cron job to run this script regularly (default 1 mins)'
    echo '-k | --kill: Block the offending ip making more than N connections'
}

unbanip()
{
    UNBAN_SCRIPT=`mktemp /tmp/unban.XXXXXXXX`
    TMP_FILE=`mktemp /tmp/unban.XXXXXXXX`
    UNBAN_IP_LIST=`mktemp /tmp/unban.XXXXXXXX`
    echo '#!/bin/sh' > $UNBAN_SCRIPT
    echo "sleep $BAN_PERIOD" >> $UNBAN_SCRIPT
    if [ $APF_BAN -eq 1 ]; then
        while read line; do
            echo "$APF -u $line" >> $UNBAN_SCRIPT
            echo $line >> $UNBAN_IP_LIST
        done < $BANNED_IP_LIST
    else
        while read line; do
            echo "$IPT -D INPUT -s $line -j DROP" >> $UNBAN_SCRIPT
            echo $line >> $UNBAN_IP_LIST
        done < $BANNED_IP_LIST
    fi
    echo "grep -v --file=$UNBAN_IP_LIST $IGNORE_IP_LIST > $TMP_FILE" >> $UNBAN_SCRIPT
    echo "mv $TMP_FILE $IGNORE_IP_LIST" >> $UNBAN_SCRIPT
    echo "rm -f $UNBAN_SCRIPT" >> $UNBAN_SCRIPT
    echo "rm -f $UNBAN_IP_LIST" >> $UNBAN_SCRIPT
    echo "rm -f $TMP_FILE" >> $UNBAN_SCRIPT
    . $UNBAN_SCRIPT &
}

add_to_cron()
{
    rm -f $CRON
    sleep 1
    service crond restart
    sleep 1
    echo "SHELL=/bin/sh" > $CRON
    if [ $FREQ -le 2 ]; then
        echo "0-59/$FREQ * * * * root /usr/local/ddos/ddos.sh >/dev/null 2>&1" >> $CRON
    else
        let "START_MINUTE = $RANDOM % ($FREQ - 1)"
        let "START_MINUTE = $START_MINUTE + 1"
        let "END_MINUTE = 60 - $FREQ + $START_MINUTE"
        echo "$START_MINUTE-$END_MINUTE/$FREQ * * * * root /usr/local/ddos/ddos.sh >/dev/null 2>&1" >> $CRON
    fi
    service crond restart
}


load_conf
while [ $1 ]; do
    case $1 in
        '-h' | '--help' | '?' )
            showhelp
            exit
            ;;
        '--cron' | '-c' )
            add_to_cron
            exit
            ;;
        '--kill' | '-k' )
            KILL=1
            ;;
         *[0-9]* )
            NO_OF_CONNECTIONS=$1
            ;;
        * )
            showhelp
            exit
            ;;
    esac
    shift
done

TMP_PREFIX='/tmp/ddos'
TMP_FILE="mktemp $TMP_PREFIX.XXXXXXXX"
BANNED_IP_MAIL=`$TMP_FILE`
BANNED_IP_LIST=`$TMP_FILE`
echo "Banned the following ip addresses on `date`" > $BANNED_IP_MAIL
echo >>    $BANNED_IP_MAIL
BAD_IP_LIST=`$TMP_FILE`
netstat -ntu | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -nr > $BAD_IP_LIST
cat $BAD_IP_LIST
if [ $KILL -eq 1 ]; then
    IP_BAN_NOW=0
    while read line; do
        CURR_LINE_CONN=$(echo $line | cut -d" " -f1)
        CURR_LINE_IP=$(echo $line | cut -d" " -f2)
        if [ $CURR_LINE_CONN -lt $NO_OF_CONNECTIONS ]; then
            break
        fi
        IGNORE_BAN=`grep -c $CURR_LINE_IP $IGNORE_IP_LIST`
        if [ $IGNORE_BAN -ge 1 ]; then
            continue
        fi
        IP_BAN_NOW=1
        echo "$CURR_LINE_IP with $CURR_LINE_CONN connections" >> $BANNED_IP_MAIL
        echo $CURR_LINE_IP >> $BANNED_IP_LIST
        echo $CURR_LINE_IP >> $IGNORE_IP_LIST
        if [ $APF_BAN -eq 1 ]; then
            $APF -d $CURR_LINE_IP
        else
            $IPT -I INPUT -s $CURR_LINE_IP -j DROP
        fi
    done < $BAD_IP_LIST
    if [ $IP_BAN_NOW -eq 1 ]; then
        dt=`date`
        if [ $EMAIL_TO != "" ]; then
            cat $BANNED_IP_MAIL | mail -s "IP addresses banned on $dt" $EMAIL_TO
        fi
        unbanip
    fi
fi
rm -f $TMP_PREFIX.*

# cat ignore.ip.list 
127.0.0.1
10.100.0.5
#不防御的ip

 注意权限:

# ll /etc/cron.d/ddos.cron 
-rw-r--r-- 1 root root 71 Sep 14 17:13 /etc/cron.d/ddos.cron

注意软连接:

# ll /usr/local/sbin/ddos 
lrwxrwxrwx 1 root root 23 Sep 13 15:36 /usr/local/sbin/ddos -> /usr/local/ddos/ddos.sh