Let's get this captive support sub-project going.  I propose that we:

1) move this to the m0n0wall developer mailing list

There the traffic is <10 msgs/wk and its more appropriate). You can
subscribe at m0n0wall dash dev dash subscribe at lists dot m0n0 dot ch and email to
m0n0wall dash dev dash subscribe at lists dot m0n0 dot ch.

2) identify key tasks/people

3) Get going!

Here's my start on (2).  I've created a set of pages,
http://socalfreenet.org/captivewall,
which everyone should be able to edit (with registration) and/or add
comments to (anonymously). Here's a copy of one of the pages,  m0n0wall
Captive Portal Design (looks much better in html,
http://socalfreenet.org/book/view/58).

User Usage Flow:
a new user gets physical connectivity to the network
they issue a DHCP request and are assigned an IP address (all
un-authenticated IP's are firewalled so they can only talk on the local
segment)
As soon as they open their browser they will be forced a local web page (see
below)
this web page will have a "Continue" button which must be pressed by the
user to continue
after they continue their IP is granted access through the firewall

Open questions:
once the user does 'continue' do they have access until their lease expires?
(Or when?)
do we need to create a separate tracking mechanism or can we piggyback on
the IP lease mechanism? (which implies, possibly, that static IPs, or
preassigned-by-MAC DHCP IPs are exempt?)

Admin Tools
per development criteria, the captive portal page will be stored in
config.xml and edited directly in the GUI. I propose a simple page where
admins can specify all text on the admin page (to allow for localization).
Note that there is no provision for a graphic due to the config.xml
restriction
page heading
preface text
legal wording
continue button text

there should be a way to disconnect a given IP which means that
there should be a way to view all IPs in use
if we decide on a timeout separate from dhcp lease timeout, then we'll need
to prompt and gather that info

Future Features
We won't try and do everything in this release. Here are some things we can
do next:
automatically add throttle rules for each new IP based on a global default

cheers, michael