/ 
Captive-Portal-4.10
River stage zero No dependents
/ Captive::Portal

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 have been achieved by using scalable technologies like ipset/iptables, FastCGI/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/CGI enabled HTTPS-server.

ALGORITHM IN SHORT

1. Access Denied

Only selected protocols like DHCP/DNS/NTP/IMAPS/IPSec/... to selected servers are allowed for unauthenticated clients.

2. Internal NAT redirect

HTTP-traffic on the gateways inside interface - from unauthenticated clients - is redirected by an iptables(8) NAT-rule to a port the HTTP-server is listening, e.g.

iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 80 -j REDIRECT --to-port 5281
3. External HTTP 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>

CLIENT REQUEST:

   GET /foo/bar HTTP/1.1
   Host: www.test.org

SERVER RESPONSE:

   HTTP/1.1 302 Found
   Location: https://gateway.acme.org/capo/
4. SESSION LOGIN

The capo.fcgi script, fired due to this redirected request, offers a splash/login page. After successful login the firewall is dynamically changed to allow this clients IP/MAC tuple for internet access by ipset(8):

ipset add capo_sessions_ipset CLIENT_IP,CLIENT_MAC
5. SESSION LOGOUT

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

ipset del capo_sessions_ipset CLIENT_IP
6. SESSION IDLE

A cronjob fires periodically the capo-ctl.pl script checking for idle or malformed sessions. Idle means, the client didn't send any packet for a period of time (cfg param: IDLE_TIME = 10min). Clients sending packets are registered via iptables/ipset in the capo_activity_ipset.

7. COMFORTABLE 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 has cookies enabled and a HTTP request matches the stored IP/MAC/COOKIE data on disc, the session is reactivated without a login page.

INSTALLATION

Please see the INSTALL file in this distribution.

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 CSS is based on the wonderful blueprint css framework, see http://www.blueprintcss.org/. Of course you may use your own styles if needed.

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 to add some local needed additional rules without changing the perl code. Be careful, you must understand the algorithm and the different states. Best you ask the author for any modifications.

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

CREDITS

Most of the good parts have been implemented by many creative discussion with my colleague Bernd Leibing.

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 2010-2013 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.