<?php

function getUserIpAddr() {
  if (!empty($_SERVER['HTTP_CLIENT_IP'])) {
    // The user has a shared IP address
    return $_SERVER['HTTP_CLIENT_IP'];
  } else if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
    // The user comes from a proxy
    return $_SERVER['HTTP_X_FORWARDED_FOR'];
  } else {
    return $_SERVER['REMOTE_ADDR'];
  }
}

print getUserIpAddr();

?>