LemonLDAP::NG
Lemonldap::NG is a modular Web-SSO based on
Apache::Session modules. It simplifies the build of a protected area with
a few changes in the application. It manages both authentication and
authorization and provides headers for accounting. So you can have a full
AAA protection for your web space as described below.
Lemonldap::NG is a complete rewrite of Lemonldap.
All components needed to use it and to aminister it are included in the
tarball. Contrary, all modules developed for Lemonldap may not work with
Lemonldap::NG.
Authentication,
Authorization and Accounting mechanisms
All parameters described here can be edited by
the administration interface (See
Manager
demonstration).
Authentication
If a user isn't authenticated and attemps to
connect to an area protected by a Lemonldap::NG compatible handler, he is
redirected to a portal. The portal authenticates user with a ldap bind by
default, but you can also use another authentication sheme like using x509
user certificates (see Lemonldap::NG::Portal::AuthSSL(3) for more).
Lemonldap use session cookies generated by
Apache::Session so as secure as a 128-bit random cookie. You may use the
securedCookie options to avoid session hijacking.
You have to manage life of sessions by yourself
since Lemonldap::NG knows nothing about the L module you've choosed, but
it's very easy using a simple cron script because Lemonldap::NG::Portal
stores the start time in the _utime field.
By default, a session stay 10 minutes in the
local storage, so in the worth case, a user is authorized 10 minutes after
he lost his rights.
Authorization
Authorization is controled only by handlers
because the portal knows nothing about the way the user will choose. When
configuring your Web-SSO, you have to:
- choose the ldap attributes you want to use to manage accounting and
authorization.
- create Perl expressions to define user groups (using ldap
attributes)
- create an array foreach virtual host associating URI regular
expressions and Perl expressions to use to grant access.
Example (See Lemonldap::NG::Manager::Conf(3) to see how configuration
is stored) :
# Custom-Name => LDAP attribute
cn => cn
departmentUID => departmentUID
login => uid
# Custom-Name => group definition
group1 => { $departmentUID eq "unit1" or $login = "user1" }
- Area protection: each VirtualHost has its own configuration
associating URL regexp to Perl expression
^/protected/.*$ => $groups =~ /bgroup1b/
default => accept
^/site/.*$ => $uid eq "admin" or $groups =~ /bgroup2b/
^/(js|css) => accept
default => deny
Performance
You can use Perl expressions as complicated as
you want and you can use all the exported LDAP attributes (and create your
own attributes: with 'macros' mechanism) in groups evaluations, area
protections or custom HTTP headers (you just have to call them with a
"$").
ou have to be careful when choosing your
expressions:
- groups and macros are evaluated each time a user is redirected to
the portal,
- virtual host rules and exported headers are evaluated for each
request on a protected area.
It is also recommanded to use the groups mechanism to avoid having to
evaluate a long expression at each HTTP request :
^/protected/.*$ => $groups =~ /bgroup1b/
You can also use LDAP filters, or Perl expression
or mixed expressions in groups definitions. Perl expressions has to be
enclosed with {} :
group1 => (|(uid=xavier.guimard)(ou=unit1))
group1 => <uid eq "xavier.guimard" or $ou eq "unit1">
group1 => (|(uid=xavier.guimard)<ou eq "unit1">)
It is also recommanded to use Perl expressions to
avoid requiering the LDAP server more than 2 times per authentication.
Accounting
Logging portal
access
Lemonldap::NG::Portal doesn't log anything by
default, but it's easy to overload log method for normal portal access.
Logging
application access
Because a Web-SSO knows nothing about the
protected application, it can't do more than logging URL. As Apache does
this fine, Lemonldap::NG::Handler(3) gives it the name to used in logs.
The whatToTrace parameter indicates which variable Apache has to use ($uid
by default).
The real accounting has to be done by the
application itself which knows the result of SQL transaction for example.
Lemonldap::NG can export HTTP headers either
using a proxy or protecting directly the application. By default, the
Auth-User field is used but you can change it using the exportedHeaders
parameters (in the Manager, each virtual host as custom headers branch).
This parameters contains an associative array per virtual host :
- keys are the names of the choosen headers,
- values are Perl expressions where you can use user datas stored in
the global storage.
Example:
Auth-User => $uid
Unit => $ou
Authorization => "Basic ".encode_base64($employeeNumber.":dummy")
Remote-IP => $ip
Installation
Warnings :
- Lemonldap::NG is a different project than Lemonldap and contains all
you need to use and administer it. So softwares, like Lemonldap webmin
module, may not work with Lemonldap::NG.
- The Apache module part (Lemonldap::NG::Handler) works both with
Apache 1.3.x and 2.x ie mod_perl 1 and 2 (but not with mod_perl 1.99).
Portal and Manager act as CGI, so they can work everywhere.
- Lemonldap::NG configuration has to be edited using the manager
unless you know exactly what you are doing. The parameters discussed
below are all in the configuration tree.
See
installation manuel for a
complete installation documentation.
Session storage
system
Lemonldap::NG use 3 levels of cache for
authenticated users :
- an Apache::Session:: module used by
lemonldap::NG::Portal to store authenticated user
parameters,
- a Cache::Cache module used by Lemonldap::NG::Handler to share
authenticated users between Apache's threads or processus and of course
between virtual hosts on the same machine,
- Lemonldap::NG::Handler variables : if the same user use the same
thread or processus a second time, no request are needed to grant or
refuse access. This is very efficient with HTTP/1.1 Keep-Alive
system.
So the number of request to the central storage is limited to 1 per
active user each 10 minutes.
Lemonldap::NG is very fast, but you can increase
performance using a Cache::Cache module that does not use disk access.
Author
Xavier Guimard, <x.guimard@free.fr>
Copyright and
licence
Copyright © 2005-2007 by Xavier Guimard
<x.guimard@free.fr>
This library is free software; you can
redistribute it and/or modify it under the same terms as Perl itself,
either Perl version 5.8.4 or, at your option, any later version of Perl 5
you may have available.