Loop issues

[jgreeno]

I'm trying to setup a page for our techs to use to determine which IPs are free in our DNS in a subnet that they supply.

 

For instance they would type in 192.168.1 to see all free IPs in the 192.168.1.1-255 range.

Here's my issue:

I've tried the while, do_while and for and still the script only runs to the 42nd address before quitting.

What am I missing?

 

 

$l="0";
$finalp=".";	
for($l<=255; ;$l++){
$ipaddress=$record.$finalp.$l;
$lookup=@gethostbyaddr($ipaddress);
echo "<br>".$ipaddress." scanned.<br>";
if ($lookup==$ipaddress){
$data.="<b>".$ipaddress."</b> is free<br>";
echo "<b>".$ipaddress."</b> is free<br>";
					}
				}	

[trq]

<?php

  $finalp=".";	
  foreach(range(0,255) as $l) {
    $ipaddress = $record.$finalp.$l;
    $lookup=@gethostbyaddr($ipaddress);
    echo "<br>".$ipaddress." scanned.<br>";
    if ($lookup==$ipaddress){
      $data.="<b>".$ipaddress."</b> is free<br>";
      echo "<b>".$ipaddress."</b> is free<br>";
    }
  }

?>

[jgreeno]

Also: $record is the subnet's forst 3 octets.. so:

$record="192.168.1";

[jgreeno]

After some more troubleshooting I'm seeing that the loop works fine, it appears to be an issue with the amount of data that I'm pumping into the variable $data.

After looking up only 42 addresses, the loop exits and does not execute subsequent commands.

It's like the script just quits after 42 entries.

 

 

Is there a logical limit to the amount of data that can be stored in a variable?

[jgreeno]

I wonder is there's a limit to the number of DNS lookups that can be performed against and Active Directory DNS server in x amount of time..

[PC Nerd]

also,

at the end of every look, maybe go unset($date); or maybe create an array value, that will store all your results?

[jgreeno]

Am I even on the right track here?

 

I feel like I'm so close and missing something stupid and simple..

 

 

<?php
// Initialize some variables
$finalp=".";
$loop="0";
$record="192.168.1";

// 0 - 255 step loop
while($loop <=255){
// Build the ip from the $record and the loop counter
$ipaddress=$record.$finalp.$loop;
// Do a lookup on the address
$data=@gethostbyaddr($ipaddress);
// If the lookup pukes, push the ip to an array value with loop counter as the key
if ($data==$ipaddress){
$arr=array($loop => $ipaddress);
                      }
// Increment the counter
$loop++;
}
// Feed the array to foreach and build the output
foreach($arr as $output){
$output.=$output;
}
?>

[jgreeno]

also,

at the end of every look, maybe go unset($date); or maybe create an array value, that will store all your results?

 

So, how can I write values out of the loop and into an array for later use?

My use of an array above seems to be overwritten every go round..