IP by groups

/**
 * Checking IP's or parts of an IP for session validation (for example)
 *
 * get_ip_groups(3) = 123.456.798
 * get_ip_groups(2) = 123.456       (default)
 */

/*
function get_real_ip()
{
    $ip = null;
    if(isset($_SERVER['HTTP_CF_CONNECTING_IP']))
    {
        $ip = $_SERVER['HTTP_CF_CONNECTING_IP']; // Get IP from Cloudflare
    }
    elseif (isset($_SERVER['HTTP_CLIENT_IP']))
    {
        $ip = $_SERVER['HTTP_CLIENT_IP']; // Get IP from share internet
    }
    elseif(isset($_SERVER['HTTP_X_FORWARDED_FOR']))
    {
        $ip = $_SERVER['HTTP_X_FORWARDED_FOR']; // Get IP from proxy
    }
    elseif(isset($_SERVER['HTTP_X_FORWARDED']))
    {
        $ip = $_SERVER['HTTP_X_FORWARDED']; // Get IP from proxy
    }
    elseif(isset($_SERVER['HTTP_FORWARDED_FOR']))
    {
        $ip = $_SERVER['HTTP_FORWARDED_FOR']; // Get IP from proxy
    }
    elseif(isset($_SERVER['HTTP_FORWARDED']))
    {
        $ip = $_SERVER['HTTP_FORWARDED']; // Get IP from proxy
    }
    elseif (isset($_SERVER['REMOTE_ADDR']))
    {
        $ip = $_SERVER['REMOTE_ADDR'];
    }
    return $ip;
}
*/

function get_ip_groups($group = null)
{
    // Looking for (real ip or) ip,
    $ip_addr = (function_exists('get_real_ip')) ? get_real_ip() : $_SERVER['REMOTE_ADDR'];

    $group = (is_int($group) == null || $group >= 5 || $group == 0) ? 2 : (int) $group;
    $ip2check = array_slice(explode('.', $ip_addr), 0, $group);
    return implode('.', $ip2check);
}

?>
<p>Checking IP by {1..4} groups...<br />
<em>(Default is "2", and max is "4")</em></p>
<pre><code>
[Examples]

    get_ip_groups(7) = <?= get_ip_groups(7) . "\n"; ?>
    get_ip_groups(6) = <?= get_ip_groups(6) . "\n"; ?>
    get_ip_groups(5) = <?= get_ip_groups(5); ?><strong>
    get_ip_groups(4) = <?= get_ip_groups(4) . "\n"; ?>
    get_ip_groups(3) = <?= get_ip_groups(3) . "\n"; ?>
    get_ip_groups(2) = <?= get_ip_groups(2) . "\n"; ?>
    get_ip_groups(1) = <?= get_ip_groups(1); ?></strong>
    get_ip_groups(0) = <?= get_ip_groups(0) . "\n"; ?>
</code></pre>

<?php
$show_code = highlight_string('
<?php

function get_ip_groups($group = null)
{
    // Looking for (real ip or) ip,
    $ip_addr = (function_exists(\'get_real_ip\')) ? get_real_ip() : $_SERVER[\'REMOTE_ADDR\'];

    $group = (is_int($group) == null || $group >= 5 || $group == 0) ? 2 : (int) $group;
    $ip2check = array_slice(explode('.', $ip_addr), 0, $group);
    return implode('.', $ip2check);
};
', true);

//echo $show_code;