penetration programming Modify the .sh script so that it also works interactively. Specifically, if no hostname is given on the command line, the program should interactively ask for a hostname, starting port, and ending port with three separate prompts, and carry out its scan using those values. After scanning finishes, the program should loop to receive another set of values, stopping only when the user enters a blank host name. If this feature is implemented properly, it will also allow you to run the script in ’batch’ mode, by “piping in” a plain text file with the hostname on the first line, start port on the second, stop port on the third, and repeating for as many hosts as you wish to scan. For example, if a file named hosts_to_scan.txt contains a list of hosts and ports in the proper format, the program should now work as follows: cat hosts_to_scan.txt | ./portscanner.sh The timeout argument should still work in this case as well: cat hosts_to_scan.txt | ./portscanner.sh -t 3 .sh #!/bin/bash #Basic bash port scanner # CHECKING CONDITION FOR -t OPTION if [ "$1" == '-t' ]; then # IF -t IS USED time=$2 host=$3 startport=$4 stopport=$5 else # IF -t IS NOT USED time=2 host=$1 startport=$2 stopport=$3 fi function pingcheck { pingresult=$(ping -c 1 $host | grep bytes | wc -l) if [ "$pingresult" -gt 1 ]; then echo else echo "$host is down, quitting" exit fi } function portcheck { # IF TIMEOUT VALUE OF LESS THAN 1 if [ "$time" -lt 1 ] then echo "Timeout value must be greater than 0, quitting" exit # IF TIMEOUT VALUE IF NOT EQUAL TO 2 elif [ "$time" -ne 2 ] then echo "Note: Timeout changed to $time." fi for ((counter=$startport; counter<=$stopport; counter++)) do if timeout $time bash -c "echo >/dev/tcp/$host/$counter" then echo "$counter open" else echo "$counter closed" fi done } #first, check that the host is alive pingcheck # next, loop through the ports portcheck

Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
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penetration programming

Modify the .sh script so that it also works interactively. Specifically, if no hostname is given on the command line, the program should interactively ask for a hostname, starting port, and ending port with three separate prompts, and carry out its scan using those values. After scanning finishes, the program should loop to receive another set of values, stopping only when the user enters a blank host name.

If this feature is implemented properly, it will also allow you to run the script in ’batch’ mode, by “piping in” a plain text file with the hostname on the first line, start port on the second, stop port on the third, and repeating for as many hosts as you wish to scan.

For example, if a file named hosts_to_scan.txt contains a list of hosts and ports in the proper format, the program should now work as follows:

cat hosts_to_scan.txt | ./portscanner.sh

The timeout argument should still work in this case as well:

cat hosts_to_scan.txt | ./portscanner.sh -t 3

 

.sh 

#!/bin/bash
#Basic bash port scanner

# CHECKING CONDITION FOR -t OPTION
if [ "$1" == '-t' ]; then
# IF -t IS USED
    time=$2
    host=$3
    startport=$4
    stopport=$5
else
# IF -t IS NOT USED
    time=2
    host=$1
    startport=$2
    stopport=$3
fi

function pingcheck
{
pingresult=$(ping -c 1 $host | grep bytes | wc -l)
if [ "$pingresult" -gt 1 ]; then
    echo
else
    echo "$host is down, quitting"
    exit
fi
}

function portcheck
{
# IF TIMEOUT VALUE OF LESS THAN 1
if [ "$time" -lt 1 ]
then
    echo "Timeout value must be greater than 0, quitting"
    exit
# IF TIMEOUT VALUE IF NOT EQUAL TO 2
elif [ "$time" -ne 2 ]
then
    echo "Note: Timeout changed to $time."

fi

for ((counter=$startport; counter<=$stopport; counter++))
do
    if timeout $time bash -c "echo >/dev/tcp/$host/$counter"
    then
        echo "$counter open"
    else
        echo "$counter closed"
    fi
done
}

#first, check that the host is alive
pingcheck
# next, loop through the ports
portcheck

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