NAME
    Captive::Portal - Perl based solution for controlled network access

ABSTRACT
    A so called *Captive Portal* written in perl for Linux Gateways. For a
    longer explanation see:

    <http://en.wikipedia.org/wiki/Captive_Portal>

DESCRIPTION
    Captive::Portal a.k.a. CaPo is a hotspot solution for Linux Gateways.
    CaPo is developed and in service at Ulm University for thousands of
    concurrent users. The main focus is scalability, performance, simple
    administration and user-friendliness.

    The goals were achieved by using scalable technologies like ipset(8)
    instead of native iptables(8), FastCGI instead of CGI and a fine tuned
    concurrent session handling based on the filesystem locking mechanism
    without any need for an additional RDBMS.

    CaPo is compatible with any FastCGI enabled HTTP(S)-server.

ALGORITHM IN SHORT
    1. Internal NAT redirect
        HTTP-traffic on the gateways inside interface - from unknown clients
        - is redirected by an iptables(8) NAT-rule to a port the HTTP-server
        is listen, e.g.

         iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 80 -j REDIRECT --to-port 5281

    2. HTTP to HTTPS redirect
        The HTTP-server redirects the HTTP-request by a rewrite rule to an
        HTTPS-request for the CaPo script *capo.fcgi* , e.g.

         <VirtualHost *:5281>
             RewriteEngine On
             RewriteRule   .*  https://gateway.acme.org/capo/? [R,L]
         </VirtualHost>

    3. SESSION LOGIN
        The *capo.fcgi* script offers a login/splash page. After successful
        login the firewall is dynamically changed to allow this clients
        IP/MAC tuple for internet access.

    4. SESSION LOGOUT
        The capo.fcgi script offers a status/logut page. After successful
        logout the firewall is dynamically changed to disallow this IP/MAC
        tuple for internet access.

    5. SESSION IDLE
        A cronjob fires periodically the capo-ctl.pl script checking for
        idle sessions. Idle means, the client didn't send any packet for a
        period of time (cfg param: IDLE_TIME = 10min). Before a session is
        put into idle state the client is once pinged.

        It is a design goal not requiring JavaScript on clients!

    6. SESSION REACTIVATION
        For a short period of time (cfg param: KEEP_OLD_STATE_PERIOD = 1h)
        the session is still on disc, but in idle state. If a client request
        matches the sessions IP/MAC/COOKIE data, the session is reactivated
        without a login page.

INSTALLATION
    Please see the INSTALL file in this distribution. As a minimum please be
    aware of the following access restrictions:

    Captive::Portal needs access to iptables(8) and ipset(8) to change the
    firewall-rules on request. You must add the following rule (or similar)
    to the sudoers file, depending on the username of your http daemon:

     WWW_USER ALL=NOPASSWD: /PATH/TO/iptables, /PATH/TO/ipset

    If you use fping(8) (see USE_FPING config parameter) to trigger idle
    sessions before going idle you must add fping to the sudoers file like
    ipset and iptables, regardless of the suid bit on fping, since we need
    special timing flags available only for root:

     WWW_USER ALL=NOPASSWD: /PATH/TO/iptables, /PATH/TO/ipset, /PATH/TO/fping

    The default $SESSIONS_DIR is set to '/var/cache/capo'.

    WWW_USER must be the owner of this dir with write permissions!

CONFIGURATION
    The configuration file is searched in the following default places:

        $ENV{CAPTIVE_PORTAL_CONFIG} ||
        $Bin/../etc/local/config.pl ||
        $Bin/../etc/config.pl

LOGGING
    Logging is handled by the Log::Log4perl module. The logging
    configuration is searched in the following default places:

        $ENV{CAPTIVE_PORTAL_LOG4PERL}   ||
        $Bin/../etc/local/log4perl.conf ||
        $Bin/../etc/log4perl.conf

LOCAL ADAPTATION
    The HTML files are generated from templates (Template-Toolkit syntax).
    You should use the original template files as stanzas and put the
    locally changed versions into the local template tree. The template
    search order prefers the local templates.

    The firewall rules and commands are also generated from template files.
    Normally there is no need to change the firewall rules but it would be
    possible without changing the perl code.

I18N
    There exists a template tree for each supported language. Some
    system/error messages used by the program must also be translated for
    the message catalog in the config file.

SEE ALSO
    Captive::Portal::Role::Config, capo.fcgi and capo-ctl.pl

BUGS AND LIMITATIONS
    There are no known problems with this module.

    Please report any bugs or feature requests to "bug-captive-portal at
    rt.cpan.org", or through the web interface at
    <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Captive-Portal>. I will
    be notified, and then you'll automatically be notified of progress on
    your bug as I make changes.

AUTHOR
    Karl Gaissmaier, "<gaissmai at cpan.org>"

LICENSE AND COPYRIGHT
    Copyright 2010-2011 Karl Gaissmaier, all rights reserved.

    This distribution is free software; you can redistribute it and/or
    modify it under the terms of either:

    a) the GNU General Public License as published by the Free Software
    Foundation; either version 2, or (at your option) any later version, or

    b) the Artistic License version 2.0.