$ErrorActionPreference = "SilentlyContinue"
$input1,$input2 = $null
 
# START | The script asks for an IP, put it in a while for error checking. It only checks if the IP is a valid one.
while ($input1 -eq $null)
{
    [ipaddress]$input1 = read-host "Please input the first IP address you would like to scan: "
}
# END | The script asks for an IP, put it in a while for error checking. It only checks if the IP is a valid one.    
while ($input2 -eq $null)
{
    [ipaddress]$input2 = read-host "Please input the IP address you want to finish the scan: "
}
# Grabs each respective input and puts them into their own arrays.
[array]$ip1 = $input1 -split ".",0,"simplematch"; [array]$ip2 = $input2 -split ".",0,"simplematch"
 
# Begin madness. The ping sweep is four nested for loops. Each for loop interates for each octet. We call the count for each octet a.b.c.d respectively.
# $a starts at the first input.. obviously. The first input should be less or equal to the second input. i.e. 192.x.x.x 192..193.x.x.x
for ([int]$a = $ip1[0];($a -le $ip2[0]); $a++)
{
    # Say we're interating through a ton of IPs.. eventually when we get to where we want to be.. we need to reset the limit to stop at our second input
    # input will never change.. but ip1 and ip2 can because they are our limiters.
    if ($a -eq $ip2[0])
    {
        [array]$ip2 = $input2 -split ".",0,"simplematch"
    }
   
    # This is the first break.. don't worry about how it's spelled. In order for the loop to break properly.. we had to add a mechanism to exit each nested for.
    # I.E. when b.c.d. reaches 255.. that was the easiest way to go back to the previous for loop in order to interate to the next subnet.
    [int]$brakeB = 0
 
    # $b starts at the first inputs second octet. Checks to see if it's less or equal to the second input's second octet OR if $a is less than the input2's first octet.
    # I.E. 65.77.120.1 , 66.20.50.1. Those are two valid ranges.. but input1 $b > input2 $b. but... 65 < 66.. so we're still good.
    for ([int]$b = $ip1[1];($b -le $ip2[1] -or $a -lt $ip2[0]) -and [int]$brakeB -eq 0; $b++)
    {
        # So.. We have to tell the sweep where to stop when it's iterating.. or.. it'll just keep going. a.b.c.d is our count. ip1 and ip2 are constants/limiters
        # We want $c to be 255 when we want to add to $b
        if ($b -lt $ip2[1] -or $a -lt $ip2[0])
            {
                [int]$ip2[2] = 255
            }
        # This checks if $b gets to 255 or 256 and needs to keep going.
        # First it checks if a is less than ip2's first octet, if it is.. it sets the limit of b to 256, because if it equals 255 it will auto reset to 0 if you start on the 255 subnet
        if ($a -lt $ip2[0])
        {
            $ip2[1] = 256
            # so if $b is 256... that means it wants to keep going.. so reset and break the loop.
            if ($b -eq $ip2[1])
            {
                $b = 0
                $ip1[1] = 0
                [int]$brakeB++
            }
        }
        # This is here to be able to break out of the $c loop
        $brakeC = 0
       
        # $c starts at input1's third octet. Checks against ip2's a.b.c. If $c less or equal to ip2 OR b < inpute's second octet, or a < input2's first octet.
        # The breaks make sure that it's supposed to run at that current time
        for ([int]$c = $ip1[2];($c -le $ip2[2] -or $b -lt $ip2[1] -or $a -lt $ip2[0]) -and $brakeB -eq 0 -and $brakeC -eq 0; $c++)
        {        
            # if c is less than input2's third octet, it sets the limit to 255
            if ($c -lt $ip2[2])
            {
                [int]$ip2[3] = 255
            }
            # if c is equal to input2's third octet, reset the constant so it'll stop if our input told it to
            elseif ($c -eq $ip2[2])
            {
                [array]$ip2 = $input2 -split ".",0,"simplematch"
            }
            # This checks to see if b < input2's second octet or if a < input2's first octet
            elseif ($b -lt $ip2[1] -or $a -lt $ip2[0])
            {
               # so if $c is 256... that means it wants to keep going.. so reset and break the loop.
               if ($c -eq 256)
               {
                   $c = 0
                   $ip1[2] = 0
                   $brakeC++
               }
            }
            # This is here to be able to break out of the $d loop
            $brakeD = 0
            # d starts at input1's fourth octet. checks to see if it's less or equal to it's input2 counterpart
            # checks to see if a.b.c are less than it's counterpart and if it's supposed to be running
            for ([int]$d = $ip1[3];($d -le $ip2[3] -or $c -lt $ip2[2] -or $b -lt $ip2[1] -or $a -lt $ip2[0]) -and $BrakeC -eq 0 -and $brakeD -eq 0; $d++)
            {    
                ping -n 1 "$a.$b.$c.$d"
                [array]$ip2 = $input2 -split ".",0,"simplematch"
                if ($c -lt $ip2[2] -or $b -lt $ip2[1] -or $a -lt $ip2[0])
                {
                    if ($d -eq 255)
                    {
                        $d = 1
                        $ip1[3] = 1
                        $brakeD++
                    }
                }    
            }
        }
    }
}