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<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="fr" xml:lang="fr">
<head>
<meta name="generator" content=
"HTML Tidy for Linux/x86 (vers 6 November 2007), see www.w3.org" />
<title>Lemonldap::NG documentation: overview.html</title>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii" />
</head>
<body>
<div class="main-content">
<h2 class="heading-1"><span id=
"HLemonLDAP3A3ANG">LemonLDAP::NG</span></h2>
<p class="paragraph"></p><img src="logo_lemonldap-ng.png" alt=
"logo_lemonldap-ng.png" />
<p class="paragraph"></p>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.
<p class="paragraph"></p>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.
<p class="paragraph"></p>
<ul>
<li><a href="#HArchitecture">Architecture</a></li>
<li><a href="#HKinematics">Kinematics</a></li>
<li>
<a href=
"#HAuthentication2CAuthorizationandAccountingmechanisms">Authentication,
Authorization and Accounting mechanisms</a>
<ul>
<li><a href="#HAuthentication">Authentication</a></li>
<li>
<a href="#HAuthorization">Authorization</a>
<ul>
<li><a href="#HPerformance">Performance</a></li>
</ul>
</li>
<li>
<a href="#HAccounting">Accounting</a>
<ul>
<li><a href="#HLoggingportalaccess">Logging portal
access</a></li>
<li><a href="#HLoggingapplicationaccess">Logging application
access</a></li>
</ul>
</li>
</ul>
</li>
<li><a href="#HInstallation">Installation</a></li>
<li><a href="#HSessionstoragesystem">Session storage system</a></li>
<li><a href="#HAuthor">Author</a></li>
<li><a href="#HCopyrightandlicence">Copyright and licence</a></li>
</ul>
<h3 class="heading-1-1"><span id="HArchitecture">Architecture</span></h3>
<p class="paragraph"></p>Lemonldap::NG est composed by 3 elements and 3
databases :
<p class="paragraph"></p><img src="lemonldap-ng-architecture.png" alt=
"lemonldap-ng-architecture.png" />
<p class="paragraph"></p>Lemonldap::NG components :
<ul class="star">
<li>the Manager used to manage Lemonldap::NG configuration,</li>
<li>the Portal used to authenticate users,</li>
<li>Apache modules used to protect applications. They can protect an
Apache area which can be a reverse-proxy. In this case, it is
recommended to securise the link between the reverse-proxy and the
hidden server because access can be done without authentication to this
server. A simple .htaccess or an SSL handshake can be used depending on
the security level of the host network.</li>
</ul>Three databases are required :
<ul class="star">
<li>the configuration database : by default, it's a simple directory,
but you can use a network database to share configuration if all the
Lemonldap::NG components aren't on the same physical server,</li>
<li>the LDAP server : in addition to the authentications (that can be
done by another mechanism as X509 certificates), it is used to load user
attributes and calculate the rights,</li>
<li>the sessions database : Lemonldap::NG uses Apache::Session modules
to manage sessions. By default, it uses Apache::Session::File module and
so, this database is a simple directory. Using Apache::Session::MySQL
for example, the database can be used on a network so Lemonldap::NG can
works on several physical servers.</li>
</ul>
<h3 class="heading-1-1"><span id="HKinematics">Kinematics</span></h3>
<p class="paragraph"></p><img src="lemonldap-ng-cinematique.png" alt=
"lemonldap-ng-cinematique.png" />
<p class="paragraph"></p>Detail of operations :
<ul class="star">
<li>1 and 2 : non-authenticated users (ie without valid cookie) are
redirected to the portal,</li>
<li>3 : authentication request (login password validated on LDAP server
or other mechanism),</li>
<li>4 : recovery ok user attributes,</li>
<li>5 : calculation of the additional attributes asked in the
configuration (macros and groups) and storage of the user datas in the
sessions database,</li>
<li>6 : cookie generation and redirection to the asked URL,</li>
<li>7 : interception of the cookie by the agent of protection (Apache
module) and recovery of the user datas,</li>
<li>8 : checking of the access authorization to the asked URL and
transmission to the application (real application or reverse-proxy) if
granted,</li>
<li>9 and 10 : other request are treated directly with the use datas
stored in the local cache. Access grant is calculated at each
request.</li>
</ul>When the authenticated user tries to access to another protected
server, only phases 7 to 10 are replayed in all transparency for the user.
<h3 class="heading-1-1"><span id=
"HAuthentication2CAuthorizationandAccountingmechanisms">Authentication,
Authorization and Accounting mechanisms</span></h3>
<p class="paragraph"></p>All parameters described here can be edited by
the administration interface (See <span class="wikiexternallink"><a href=
"http://lemonldap.objectweb.org/NG/ManagerDemo/en/">Manager
demonstration</a></span>).
<h4 class="heading-1-1-1"><span id=
"HAuthentication">Authentication</span></h4>
<p class="paragraph"></p>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).
<p class="paragraph"></p>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.
<p class="paragraph"></p>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.
<p class="paragraph"></p>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.
<h4 class="heading-1-1-1"><span id=
"HAuthorization">Authorization</span></h4>
<p class="paragraph"></p>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:
<ul class="star">
<li>choose the ldap attributes you want to use to manage accounting and
authorization.</li>
<li>create Perl expressions to define user groups (using ldap
attributes)</li>
<li>create an array foreach virtual host associating URI regular
expressions and Perl expressions to use to grant access.</li>
</ul>Example (See Lemonldap::NG::Manager::Conf(3) to see how configuration
is stored) :
<ul class="star">
<li>Exported variables :</li>
</ul>
<div class="code">
<pre>
# Custom-Name => LDAP attribute
cn => cn
departmentUID => departmentUID
login => uid
</pre>
</div>
<ul class="star">
<li>User groups :</li>
</ul>
<div class="code">
<pre>
# Custom-Name => group definition
group1 => { $departmentUID eq <span class=
"java-quote">"unit1"</span> or $login = <span class=
"java-quote">"user1"</span> }
</pre>
</div>
<ul class="star">
<li>Area protection: each VirtualHost has its own configuration
associating URL regexp to Perl expression
<ul class="star">
<li>www1.domain.com :</li>
</ul>
</li>
</ul>
<div class="code">
<pre>
^/<span class=
"java-keyword">protected</span>/.*$ => $groups =~ /\bgroup1\b/
<span class="java-keyword">default</span> => accept
</pre>
</div>
<ul class="star">
<li>www2.domain.com :</li>
</ul>
<div class="code">
<pre>
^/site/.*$ => $uid eq <span class=
"java-quote">"admin"</span> or $groups =~ /\bgroup2\b/
^/(js|css) => accept
<span class="java-keyword">default</span> => deny
</pre>
</div>
<p class="paragraph"></p>Note: \b means start or end of a word in PCRE
(Perl Compatible Regular Expressions)
<h5 class="heading-1-1-1-1"><span id=
"HPerformance">Performance</span></h5>
<p class="paragraph"></p>You can use Perl expressions as complicated as
you want and you can use all the exported LDAP attributes (and create your
own attributes: with 'macros' mechanism) in groups evaluations, area
protections or custom HTTP headers (you just have to call them with a
"$").
<p class="paragraph"></p>ou have to be careful when choosing your
expressions:
<ul class="star">
<li>groups and macros are evaluated each time a user is redirected to
the portal,</li>
<li>virtual host rules and exported headers are evaluated for each
request on a protected area.</li>
</ul>It is also recommanded to use the groups mechanism to avoid having to
evaluate a long expression at each HTTP request :
<div class="code">
<pre>
^/<span class=
"java-keyword">protected</span>/.*$ => $groups =~ /\bgroup1\b/
</pre>
</div><br />
<br />
You can also use LDAP filters, or Perl expression or mixed expressions in
groups definitions. Perl expressions has to be enclosed with {} :
<div class="code">
<pre>
group1 => (|(uid=xavier.guimard)(ou=unit1))
group1 => {$uid eq <span class=
"java-quote">"xavier.guimard"</span> or $ou eq <span class=
"java-quote">"unit1"</span>}
group1 => (|(uid=xavier.guimard){$ou eq <span class=
"java-quote">"unit1"</span>})
</pre>
</div>
<p class="paragraph"></p>It is also recommanded to use Perl expressions to
avoid requiering the LDAP server more than 2 times per authentication.
<h4 class="heading-1-1-1"><span id="HAccounting">Accounting</span></h4>
<h5 class="heading-1-1-1-1"><span id="HLoggingportalaccess">Logging portal
access</span></h5>
<p class="paragraph"></p>Lemonldap::NG::Portal doesn't log anything by
default, but it's easy to overload log method for normal portal access.
<h5 class="heading-1-1-1-1"><span id="HLoggingapplicationaccess">Logging
application access</span></h5>
<p class="paragraph"></p>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).
<p class="paragraph"></p>The real accounting has to be done by the
application itself which knows the result of SQL transaction for example.
<p class="paragraph"></p>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 :
<ul class="star">
<li>keys are the names of the choosen headers,</li>
<li>values are Perl expressions where you can use user datas stored in
the global storage.</li>
</ul>Example:
<ul class="star">
<li>www1.domain.com :</li>
</ul>
<div class="code">
<pre>
Auth-User => $uid
Unit => $ou
</pre>
</div>
<ul class="star">
<li>www2.domain.com :</li>
</ul>
<div class="code">
<pre>
Authorization => <span class=
"java-quote">"Basic "</span>.encode_base64($employeeNumber.<span class=
"java-quote">":dummy"</span>)
Remote-IP => $ip
</pre>
</div>
<h3 class="heading-1-1"><span id="HInstallation">Installation</span></h3>
<p class="paragraph"></p>Warnings :
<ul class="star">
<li>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.</li>
<li>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.</li>
<li>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.</li>
</ul>See <span class="wikilink"><a href=
"advanced-install.html">installation manuel</a></span> for a complete
installation documentation.
<h3 class="heading-1-1"><span id="HSessionstoragesystem">Session storage
system</span></h3>
<p class="paragraph"></p>Lemonldap::NG use 3 levels of cache for
authenticated users :
<ul class="star">
<li>an Apache::Session::* module used by lemonldap::NG::Portal to store
authenticated user parameters,</li>
<li>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,</li>
<li>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.</li>
</ul>So the number of request to the central storage is limited to 1 per
active user each 10 minutes.
<p class="paragraph"></p>Lemonldap::NG is very fast, but you can increase
performance using a Cache::Cache module that does not use disk access.
<h3 class="heading-1-1"><span id="HAuthor">Author</span></h3>
<p class="paragraph"></p>Xavier Guimard, <x.guimard@free.fr>
<h3 class="heading-1-1"><span id="HCopyrightandlicence">Copyright and
licence</span></h3>
<p class="paragraph"></p>Copyright © 2005-2007 by Xavier Guimard
<x.guimard@free.fr>
<p class="paragraph"></p>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.
</div>
</body>
</html>
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