Hello everyone,
with the support of some friends of the Italian forum I realised an interface to manage the captive portal that can be installed directly on ZeroShell. Its name is Zerotruth and it makes the use of captive portal much easier;
it also allows several functions that are normally unavailable in ZeroShell:
the auto-registration, which sends username and password per sms and email, programming and limiting of daily connections, timetable, limit of daily and monthly hours, print of users tickets, auto-update, backup, web cache with squid, shaping for classes, multi-language interface
(currently Italian, English, Spanish, German), password change and recovery, backup… for more information see http://www.zerotruth.net/indexe.php
bye.