Load Balancing Script

    #!/bin/bash
    # lbd (load balancing detector) detects if a given domain uses
    # DNS and/or HTTP Load-Balancing (via Server: and Date: header and diffs between server answers)
    # Copyright (C) 2010 Stefan Behte
    #
    # This program is free software; you can redistribute it and/or
    # modify it under the terms of the GNU General Public License
    # as published by the Free Software Foundation; either version 2
    # of the License, or (at your option) any later version.
    #
    # This program is distributed in the hope that it will be useful,
    # but WITHOUT ANY WARRANTY; without even the implied warranty of
    # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    # GNU General Public License for more details.
    #
    # You should have received a copy of the GNU General Public License
    # along with this program; if not, write to the Free Software
    # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
    #
    # License: GNU General Public License, version 2
    # http://www.gnu.org/licenses/gpl-2.0.html
    #
    # Contact me, if you have any new ideas, bugs/bugfixes, recommondations or questions!
    # Please also contact me, if you just like the tool. :)
    #
    # Stefan dot Behte at gmx dot net
    #
    # 0.1:  - initial release
    # 0.2:  - fix license for fedora
    #       - fix indenting
    #

    QUERIES=50
    DOMAIN=$1
    METHODS=""

    echo
    echo "lbd - load balancing detector 0.2 - Checks if a given domain uses load-balancing."
    echo "                                    Written by Stefan Behte (http://ge.mine.nu)"
    echo "                                    Proof-of-concept! Might give false positives."

    if [ "$1" = "" ]
    then
            echo "usage: $0 [domain]"
            echo
            exit -1
    fi

    echo -e -n "\nChecking for DNS-Loadbalancing:"
    NR=`host $DOMAIN | grep -c "has add"`

    if [ $NR -gt 1 ]
    then
            METHODS="DNS"
            echo " FOUND"
            host $DOMAIN | grep "has add"
            echo
    else
            echo " NOT FOUND"
    fi

    echo -e "Checking for HTTP-Loadbalancing ["Server"]: "
    for ((i=0 ; i< $QUERIES ; i++))
    do
            printf "HEAD / HTTP/1.0\r\n\r\n" | nc $DOMAIN 80 > .nlog
            S=`grep -i "Server:" .nlog | awk -F: '{print $2}'`

            if ! grep "`echo ${S}| cut -b2-`" .log &>/dev/null
            then
                    echo "${S}"
            fi
            cat .nlog >> .log
    done

    NR=`sort .log | uniq | grep -c "Server:"`

    if [ $NR -gt 1 ]
    then
            echo " FOUND"
            METHODS="$METHODS HTTP[Server]"
    else
            echo " NOT FOUND"
    fi
    echo
    rm .nlog .log


    echo -e -n "Checking for HTTP-Loadbalancing ["Date"]: "
    D4=

    for ((i=0 ; i<$QUERIES ; i++))
    do
            D=`printf "HEAD / HTTP/1.0\r\n\r\n" | nc $DOMAIN 80 | grep "Date:" | awk '{print $6}'`
            printf "$D, "

            Df=$(echo " $D" | sed -e 's/:0/:/g' -e 's/ 0/ /g')
            D1=$(echo ${Df} | awk -F: '{print $1}')
            D2=$(echo ${Df} | awk -F: '{print $2}')
            D3=$(echo ${Df} | awk -F: '{print $3}')

            if [ "$D4" = "" ];  then   D4=0;  fi

            if [ $[ $D1 * 3600 + $D2 * 60 + $D3 ] -lt $D4 ]
            then
                    echo "FOUND"
                    METHODS="$METHODS HTTP[Date]"
                    break;
            fi

            D4="$[ $D1 * 3600 + $D2 * 60 + $D3 ]"

            if [ $i -eq $[$QUERIES - 1] ]
            then
                    echo "NOT FOUND"
            fi
    done


    echo -e -n "\nChecking for HTTP-Loadbalancing ["Diff"]: "
    for ((i=0 ; i<$QUERIES ; i++))
    do
            printf "HEAD / HTTP/1.0\r\n\r\n" | nc $DOMAIN 80 | grep -v -e "Date:" -e "Set-Cookie" > .nlog

            if ! cmp .log .nlog &>/dev/null && [ -e .log ]
            then
                    echo "FOUND"
                    diff .log .nlog | grep -e ">" -e "<"
                    METHODS="$METHODS HTTP[Diff]"
                    break;
            fi

            cp .nlog .log

            if [ $i -eq $[$QUERIES - 1] ]
            then
                    echo "NOT FOUND"
            fi
    done

    rm .nlog .log


    if [ "$METHODS" != "" ]
    then
            echo
            echo $DOMAIN does Load-balancing. Found via Methods: $METHODS
            echo
    else
            echo
            echo $DOMAIN does NOT use Load-balancing.
            echo
    fi