Jorge Luis Mera wrote:

> what is Captive portal, in which it is possible to be used and how it is
> used.


Jose,

Judging by your similar question (dated 2004-05-24 05:23:13) in 
http://m0n0.ch/wall/list/?action=show_msg&actionargs[]=56&actionargs[]=97 
I'll assume you haven't found/used the m0n0wall mailing list search 
function.

Try searching for the phrase 'captive portal' at 
http://m0n0.ch/wall/list/search.php

A short answer to your question comes from 
http://www.personaltelco.net/index.cgi/CaptivePortal

"Captive portals allow you to leverage a common browser as a secure 
authentication device. They also have the potential to allow you to do 
everything securely via SSL and IPSec and setup per user quality of 
service rules, and still maintain an open network. If you are curious 
about why you might want to install a captive portal please see 
WhyCaptivePortal. You can also see the beginning of our software 
requirements process at CaptivePortalDefinition.

Captive portals are becoming a popular way for SMS/BSN vendors to 
provide user authentication and IP flow management (basically traffic 
shaping and bandwidth control) without a required client application. 
They work by forcing un-authenticated users to a web page, once you have 
"captured them" this way by allowing the web page to interact with the 
router/firewall you can completely control their access."


Some initial thoughts on m0n0wall's captive portal design criteria can 
be found at http://socalfreenet.org/book/view/58


A thread that discusses the m0n0wall community's want/need for built-in 
captive portal features can be viewed at 
http://m0n0.ch/wall/list/query.php?query=reward+&type=subj&Submit=Search


Another thread from Manuel Kasper announcing the completion of the 
m0n0wall captive portal and Dinesh Nair's contributions are on the 
m0n0wall developer's mailing list.


Hope that finally answers your question.

z