calculate IP range using PHP and CIDR

Question

I\'ve seen various questions and answers around this site and I\'m still having difficulty wrapping my head around this problem (could be because I\'ve got a cold). Regardle

Answer 1

Here is the actual way to calculate a true IP range based on CIDR:

The top answer is actually not correct. It gives the wrong IP range list.

function ipRange($cidr) {
   $range = array();
   $cidr = explode('/', $cidr);
   $range[0] = long2ip((ip2long($cidr[0])) & ((-1 << (32 - (int)$cidr[1]))));
   $range[1] = long2ip((ip2long($range[0])) + pow(2, (32 - (int)$cidr[1])) - 1);
   return $range;
}

 var_dump(ipRange("207.64.1.68/28"));

 //////////////////OUTPUT////////////////////////
 // array(2) {
 //   [0]=>
 //   string(12) "207.64.1.64"
 //   [1]=>
 //   string(12) "207.64.1.79"
 // }
 /////////////////////////////////////////////////

IP: 207.64.1.68

Should give me all IPs within 207.64.1.64 and 207.64.1.79

The other answers do not subtract, they only go from 207.64.1.68 - 207.64.1.83 (not correct in the IP range block)

You can check it here: https://www.ipaddressguide.com/cidr