From Documentation
For annotation case in this page, we have tested ZK version 3.6.2 works fine with Hibernate Version 3.3 and hsqldb 1.8. Tested at 2009/06/10.
if (!empty($_SERVER['HTTP_CLIENT_IP'])) $ip=$_SERVER['HTTP_CLIENT_IP']; else if (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) $ip=$_SERVER['HTTP_X_FORWARDED_FOR']; else $ip=$_SERVER['REMOTE_ADDR']; ?>