GET real IP address (under proxy)

get_real_ip.php

<?php

function get_real_ip() {
  $proxy_headers = array(
                          'CLIENT_IP',
                          'FORWARDED',
                          'FORWARDED_FOR',
                          'FORWARDED_FOR_IP',
                          'HTTP_CLIENT_IP',
                          'HTTP_FORWARDED',
                          'HTTP_FORWARDED_FOR',
                          'HTTP_FORWARDED_FOR_IP',
                          'HTTP_PC_REMOTE_ADDR',
                          'HTTP_PROXY_CONNECTION',
                          'HTTP_VIA',
                          'HTTP_X_FORWARDED',
                          'HTTP_X_FORWARDED_FOR',
                          'HTTP_X_FORWARDED_FOR_IP',
                          'HTTP_X_IMFORWARDS',
                          'HTTP_XROXY_CONNECTION',
                          'VIA',
                          'X_FORWARDED',
                          'X_FORWARDED_FOR'
                         );

  foreach($proxy_headers as $proxy_header) {
    if(isset($_SERVER[$proxy_header]) && preg_match("/^([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])(\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])){3}$/", $_SERVER[$proxy_header])) {
        return $_SERVER[$proxy_header];
    } else if(stristr(',', $_SERVER[$proxy_header]) !== FALSE) {
      $proxy_header_temp = trim(array_shift(explode(',', $_SERVER[$proxy_header])));
      if(($pos_temp = stripos($proxy_header_temp, ':')) !== FALSE) $proxy_header_temp = substr($proxy_header_temp, 0, $pos_temp);
      if(preg_match("/^([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])(\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])){3}$/", $proxy_header_temp) return $proxy_header_temp;
    }
  }

  return $_SERVER['REMOTE_ADDR'];
}