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Matching IP number with preset networks

Posted on 2002-06-10
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Last Modified: 2006-11-17
What I need is to check if the given IP number is
from one of the networks supplied in an array like
$a[]=array('195.250.64.0', '0.0.31.255');
$a[]=array('212.73.64.0', '0.0.31.255');
$a[]=array('212.42.192.0', '0.0.31.255');
etc, where the second field is netmask. the function
should return true or false.

Anyone ever coded such thing?
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Comment
Question by:vahan
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6 Comments
 
LVL 32

Expert Comment

by:Batalf
ID: 7066438
What kind of netmask is that? is it opposite of what's normal. Normally "1" determines host/server, when "0" determines client addresses.
 
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LVL 1

Author Comment

by:vahan
ID: 7066453
It's a reverse netmask. The problem is that I'm not so good with the netmask calculation, that's why I posted the question :0 The netmasks in above mean that each 31.255 should cover 32 C class networks.
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LVL 40

Expert Comment

by:RQuadling
ID: 7066522
This is off the top of my head, but why not turn the IP address into a 32 bit integer and the mask into the range.

So.

195.250.64.0 = (((((195 * 256) + 250) * 256) + 64) * 256) + 0 = 3287957504

And the mask of 0.0.31.255, is 31 * 256 + 255 = 8191.

So, you can now check to see if the address is between 3287957504 and 3287965695.

You can split the IP address into bits by using

$a = preg_split("(\d{1,3}).(\d{1,3}).(\d{1,3}).(\d{1,3})",$IP_address);

And then you can use $a[0] .. $a[3].

Hope this helps a bit.

Richard Quadling.
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LVL 1

Author Comment

by:vahan
ID: 7066575
Can u post a working code here? 150 points is not enough?
0
 
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Accepted Solution

by:
RQuadling earned 150 total points
ID: 7066610
Hopefully this will show you what I mean.

<?php

$aValidIPs['212.73.64.0'] = '0.0.31.255';
$aValidIPs['212.42.192.0'] = '0.0.31.255';
$aValidIPs['195.250.64.0'] = '0.0.31.255';

$YourIPtoTest = '195.250.92.24';

function GetInt($sGI)
{
echo "DEBUG : Checking $sGI<br>";
$a = explode('.',$sGI,4);
echo "DEBUG : Array is $a[0] - $a[1] - $a[2] - $a[3]<br>";
echo "DEBUG : Value is " . (((((($a[0] * 256) + $a[1]) * 256) + $a[2]) * 256) + $a[3]) . "<br>";
return (((((($a[0] * 256) + $a[1]) * 256) + $a[2]) * 256) + $a[3]);
}

function CheckIP($aCIP,$IP)
{
foreach($aCIP as $BaseIP => $Range)
 {
 $FirstIPVal = GetInt($BaseIP);
 $LastIPVal = $FirstIPVal + GetInt($Range);
 $IPVal = GetInt($IP);
 echo "DEBUG : FirstIP $FirstIPVal - LastIP $LastIPVal - IP $IPVal<br>";
 if (($IPVal >= $FirstIPVal) and ($IPVal <= $LastIPVal))
  {
  return true;
  }
 }
return false;
}

if (CheckIP($aValidIPs,$YourIPtoTest) == true)
 {
 echo 'Valid';
 }
else
 {
 echo 'Invalid';
 }

?>

Regards,

Richard.
0
 
LVL 1

Author Comment

by:vahan
ID: 7066709
"Works as advertised" :0

Thanks Richard!
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