Anti-Syn Ddos firewall

#!/bin/sh
# R00TW0RMs (https://www.r00tw0rm.com/)
#-------------------------------------|------------------------------------------#
#        _______  _______   __          _______
#_______ \   _  \ \   _  \_/  |___  _  _\   _  \_______  _____
#\_  __ \/  /_\  \/  /_\  \   __\ \/ \/ /  /_\  \_  __ \/     \
# |  | \/\  \_/   \  \_/   \  |  \     /\  \_/   \  | \/  Y Y  \
# |__|    \_____  /\_____  /__|   \/\_/  \_____  /__|  |__|_|  /
#               \/       \/                    \/            \/
#
#
# This was written for educational purpose and pentest only.
# Use it at your own risk. Author will be not responsible for any damage!
# Coder      : th3breacher <th3breacher@r00tw0rm.com> |th3breacher.wordpress.com|
# Version    : 0.1
# Description: That's SYN flood firewall script , it uses tcp_syncookies ,backlog protection and also
#              iptables rules , the script runs in background...
# Usage      : Simple , when a SYN attack comes out , run the script as "./antiSyn watchtime & " , watch time
#              deals with the severity of the attack , 10 seconds as default.
# Tested on  : linux(all)
# Special thanks to :  r0073r, r4dc0re, Sid3^effects, L0rd CrusAd3r, KedAns-Dz, Angel Injection, gunslinger, JF,Seishin, CrosS (1337day.com)
#                      CrosS, Xenu, Versus71, alsa7r, mich4th3c0wb0y, FInnH@X, s3rver.exe (r00tw0rm.com)
#-------------------------------------|------------------------------------------#
level=""
logfile="/tmp/synlogs"
RED="\\033[1;31m"
NORMAL="\\033[0;39m"
showbanner() {
echo -ne "$RED"  "

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8     Y88P   Y88P   Y8P   YP  YP    Y88P  8    8   8   8


                                #SYN flood firewall
                                th3breacher <th3breacher@r00tw0rm.com>

Usage : $0 watchtime (watchtime (seconds))
Example : $0 10   means the firewall will watch for Syn Ddos every 10 seconds
KILL    : ps aux | grep antiSyn take the PID and kill PID
""$NORMAL"
}


preparation () {

echo "[+] SYN Flood protection started..." > $logfile

}
configuration() {

    echo "1" > /proc/sys/net/ipv4/tcp_syncookies

    echo "1024" > /proc/sys/net/ipv4/tcp_max_syn_backlog

    echo "1" > /proc/sys/net/ipv4/conf/all/rp_filter

    echo "[+] Preparation completed..." >> $logfile


}
iptables_watch () {
    echo "[+] SYN Firewall Started..." >> $logfile
    while true; do
        for i in ` netstat -tanpu | grep "SYN_RECV" | awk {'print $5'} | cut -f 1 -d ":" | sort | uniq -c | sort -n | awk {'if ($1 > 3) print $2'}` ; do echo $i; iptables -A INPUT -s $i/24 -j DROP; done
        sleep $level

    done
}
mynohup(){
# Close stdin, and make any read attempt an error
    if [ -t 0 ]
    then
        exec 0>/dev/null
    fi

# Redirect stdout to a file if it's a TTY
    if [ -t 1 ]
    then
        exec 1>nohup.out
        if [ $? -ne 0 ]
        then
            exec 1>$HOME/nohup.out
        fi
    fi

# Redirect stderr to stdout if it's a TTY
    if [ -t 2 ]
    then
        exec 2>&1
    fi

# Trap
    trap : HUP
}
showbanner
if [ -z "$1" ]; then
    echo "[+] Using default level set to 10 seconds"
    level=10
else
    echo "[+] Setting up level to $1 "
    level=$1
fi

mynohup
preparation
configuration
iptables_watch