Get client IP address

client_ip.php

<?php
function get_client_ip() {
  $ipaddress = '';
  if (getenv('HTTP_CLIENT_IP'))
    $ipaddress = getenv('HTTP_CLIENT_IP');
  else if(getenv('HTTP_X_FORWARDED_FOR'))
    $ipaddress = getenv('HTTP_X_FORWARDED_FOR');
  else if(getenv('HTTP_X_FORWARDED'))
    $ipaddress = getenv('HTTP_X_FORWARDED');
  else if(getenv('HTTP_FORWARDED_FOR'))
    $ipaddress = getenv('HTTP_FORWARDED_FOR');
  else if(getenv('HTTP_FORWARDED'))
    $ipaddress = getenv('HTTP_FORWARDED');
  else if(getenv('REMOTE_ADDR'))
    $ipaddress = getenv('REMOTE_ADDR');
  else
    $ipaddress = 'UNKNOWN';
  return $ipaddress;
}