Ruth Ruth - 4 years ago 236
PHP Question

Check if an IP address is private

I like to check if an IP address is in a private network. It doesn't work.

My code:

<?php
$ip = $_SERVER['REMOTE_ADDR'];

function _isPrivate($ip)
{
$i = explode('.', $ip);

if ($i[0] == 10) {
return true;
} else if ($i[0] == 172 && $i[1] > 15 && $i[1] < 32) {
return true;
} else if ($i[0] == 192 && $i[1] == 168) {
return true;
}
return false;
}
?>


The other one:

<?php
$ip = $_SERVER['REMOTE_ADDR'];

function _isPrivate($ip)
{
$ip = ip2long($ip);
$net_a = ip2long('10.255.255.255') >> 24;
$net_b = ip2long('172.31.255.255') >> 20;
$net_c = ip2long('192.168.255.255') >> 16;

return $ip >> 24 === $net_a || $ip >> 20 === $net_b || $ip >> 16 === $net_c;
}
?>


Any help would be much appreciated, thanks!

Answer Source
function ip_is_private ($ip) {
    $pri_addrs = array (
                      '10.0.0.0|10.255.255.255', // single class A network
                      '172.16.0.0|172.31.255.255', // 16 contiguous class B network
                      '192.168.0.0|192.168.255.255', // 256 contiguous class C network
                      '169.254.0.0|169.254.255.255', // Link-local address also refered to as Automatic Private IP Addressing
                      '127.0.0.0|127.255.255.255' // localhost
                     );

    $long_ip = ip2long ($ip);
    if ($long_ip != -1) {

        foreach ($pri_addrs AS $pri_addr) {
            list ($start, $end) = explode('|', $pri_addr);

             // IF IS PRIVATE
             if ($long_ip >= ip2long ($start) && $long_ip <= ip2long ($end)) {
                 return true;
             }
        }
    }

    return false;
}

See http://mebsd.com/coding-snipits/check-private-ip-function-php.html

You might also want to check out about the private address spaces here

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