= LDAP extensions =
[[PageOutline]]
== Abstract ==
LDAP support with group management has been added as a Trac extension. This
extension enables to use existing LDAP groups to grant permissions rather than
defining permissions for every single user on the system. The latest release also
permits to store permissions (both users and groups permissions) in the LDAP
directory itself rather than in the SQL backend.
The original proposition about LDAP ACL is documented under ticket
[http://projects.edgewall.com/trac/ticket/535 Trac#535] on the official web site.
This software is [http://trac.edgewall.com/license.html licenced] with the same
license as Trac.
== Requirements ==
You need the Python LDAP module. It can be retrieved from
[http://python-ldap.sourceforge.net/ python-ldap].[[BR]] LdapPlugin has been
tested on a Debian Linux Sarge/Sid (2.4.x and 2.6.x) server, a Windows XP SP2 workstation,
as well as on MacBook Pro OS 10.4.6, all of them running Python 2.3 with Trac 'development' releases.
To use the egg file you need to have
[http://peak.telecommunity.com/DevCenter/setuptools setuptools], version 0.6+
installed.[[BR]]Please refer to the
[http://projects.edgewall.com/trac/wiki/TracPlugins TracPlugins] page for
information about plugin installation.
=== Important note ===
You need to grab a recent version of Trac from the trunk to make the Ldap permission store extension work as expected.[[BR]]
As the trunk API may vary without notice, the plugin may be broken if you run it with a different release.
== Download ==
* Source code is available from http://trac-hacks.org/svn/ldapplugin.
* You can also find [wiki:LdapPlugin#Testing unit tests] at the same location - under the `tests` directory -, which may help you deploy the plugin.
== Installation ==
* Build the ''egg'' file following the plugin packaging [http://projects.edgewall.com/trac/wiki/TracDev/PluginDevelopment#Packaginganddeployingplugins instructions]
* Copy the `dist/LdapPlugin-0.y.z-py2.n.egg` file in your ''plugins'' project directory.
== Authentication ==
LdapPlugin does '''not''' perform authentication: Apache2 does, through the HTTP
protocol, as with any other Trac installation.[[BR]]
LdapPlugin retrieves the groups to which the authenticated user belongs and
checks the [http://projects.edgewall.com/trac/wiki/TracPermissions TracPermissions]
against these groups, along with the regular permissions for the user.
You probably want to use Apache2 LDAP authentication as well.[[BR]]
This topic is out of scope of this document but you may find useful information
on the official Apache2 [http://httpd.apache.org/docs-2.0/mod/mod_ldap.html mod_ldap]
web site.
Here is an example of a typical LDAP section of an Apache2 configuration file:
{{{
PythonOption TracEnv "/local/var/trac/project"
PythonOption TracUriRoot "/trac/project"
AuthType Basic
AuthName "Project"
Order Allow,Deny
Allow from All
AuthLDAPURL "ldap://localhost:389/dc=example,dc=org?uid"
Require group cn=tracusers,dc=example,dc=org
}}}
=== Apache 2.2 ===
Since the mod_auth_ldap module has been superseded by the mod_authnz_ldap module for Apache 2.2, the configuration also needs a little tweaking. The above example would now look like:
{{{
PythonOption TracEnv "/local/var/trac/project"
PythonOption TracUriRoot "/trac/project"
AuthType Basic
AuthName "Project"
AuthBasicProvider ldap
Order Allow,Deny
Allow from All
AuthLDAPURL "ldap://localhost:389/dc=example,dc=org?uid"
AuthzLDAPAuthoritative on
Require group cn=tracusers,dc=example,dc=org
}}}
Note that if you just use "Require valid-user" (to allow everybody with a valid LDAP login to access trac) you must set "AuthzLDAPAuthoritative off" according to the Apache documentation.
== Configuration ==
You need to customize the `trac.ini` file of your project, then[[BR]]
1. Create a new section `[ldap]` and,
1. Add the magic keyword `module` so that the Trac engine loads and uses
this extension.
1. Optionnally add the path to your plugin directory
1. Configure the LDAP directives to fit your LDAP server configuration
The section may also contain the following options (which are presented down
here with their default values)
{{{
[ldap]
# enable LDAP support for Trac
enable = false
# LDAP directory host
host = localhost
# LDAP directory port
port = 389
# BaseDN
basedn = dc=example,dc=com
# BaseDN for users (defaults to basedn)
user_basedn = dc=example,dc=com
# BaseDN for group of names (defaults to basedn)
group_basedn = dc=example,dc=com
# objectclass for groups
groupname = groupofnames
# dn entry in a groupname
groupmember = member
# attribute name for a group
groupattr = cn
# attribute name for a user
uidattr = uid
# attribute name to store trac permission
permattr = tracperm
# filter to search for dn with 'permattr' attributes
permfilter = objectclass=*
# time, in seconds, before a cached entry is purged out of the local cache.
cache_ttl = 900
# maximum number of entries in the cache
cache_size = 100
# whether to perform an authenticated bind for group resolution
group_bind = false
# whether to perform an authenticated bind for permision store operations
store_bind = false
# user for authenticated connection to the LDAP directory
bind_user =
# password for authenticated connection
bind_passwd =
# global permissions (vs. per-environment permissions)
global_perms = false
}}}
You probably want to define at least `enable=true` and the `basedn`[[BR]]
The meaning of the options are pretty straightforward for LDAP administrators.
A typical setup for group resolution would look like this:
{{{
[ldap]
enable = true
basedn = dc=example,dc=org
}}}
A typical setup for all LDAP support (group resolution and permission store)
would look like this:
{{{
[ldap]
enable = true
basedn = dc=example,dc=org
store_bind = true
bind_user = cn=tracadmin,dc=example,dc=org
bind_passwd = mypasswd
}}}
== Authenticated LDAP connections ==
If the server requires an authenticated connection to retrieve group permissions,
you want to set `group_bind = true` in the `[ldap]` section and define
the credentials as follows:
{{{
[ldap]
group_bind = true
bind_user = joeuser
bind_passwd = joepassword
}}}
If the server requires an authenticated connection to modify group permissions,
you want to set `store_bind = true` in the `[ldap]` section and define
the credentials as follows:
{{{
[ldap]
store_bind = true
bind_user = joeuser
bind_passwd = joepassword
}}}
''Note'': Most LDAP servers require authenticated bind to perform any kind of
modifications. Anyway, it would be a bad idea to allow modifications from
anybody.
== Ldap permission store ==
If you wish to use the LDAP permission store feature, you need to tell Trac to
use the LDAP extension rather than the internal default permission store which
relies on the SQL backend. To achieve this setting, add the following line to
the main `[trac]` section of your `trac.ini` configuration file:
{{{
[trac]
# ...
permission_store = LdapPermissionStore
}}}
You also need to enable `LdapPermissionStore` for LdapPlugin by adding:
{{{
[components]
ldapplugin.* = enabled
}}}
The extension differenciates '''group permissions''' from '''user permission'''.
This permits to use distinct objectclasses in the LDAP directory, to store
permission. For example thanks to the `groupattr` and `uidattr`
attributes, you can define group permission to LDAP entries such as
{{{
dn: cn=managers,dc=example,dc=org
objectclass: groupofnames
objectclass: trac
member: uid=chandler,dc=example,dc=org
member: uid=joey,dc=example,dc=org
tracperm: WIKI_ADMIN
tracperm: TICKET_ADMIN
}}}
and define user permission to LDAP entries such as
{{{
dn: uid=courtney,dc=example,dc=org
objectclass: user
objectclass: trac
tracperm: TICKET_VIEW
tracperm: REPORT_CREATE
tracperm: REPORT_VIEW
}}}
It is worth noting that the '''dn''' used for groups and for users may be
different, which should make things easier to add
[http://projects.edgewall.com/trac/wiki/TracPermissions TracPermissions] into
your existing LDAP directory.
To differenciate a group name from a user name in `trac-admin`, prefix the group
name with the `@` characters. This syntax has been borrowed from [http://www.samba.org Samba]
and many other software dealing with group management.[[BR]]
One would grant the above permissions using the following `trac-admin` commands
{{{
permission add @managers WIKI_ADMIN
permission add @managers TICKET_ADMIN
permission add courtney TICKET_VIEW
permission add courtney REPORT_CREATE
permission add courtney REPORT_VIEW
}}}
Please note that the LDAP permission store '''never''' attemps to create a new
entry in the LDAP directory. To grant (or revoke) permissions to/from the LDAP
directory, the targetted LDAP entry should exist in the directory and the
attribute defined by the `permattr` option should be writtable for the
`store_user` user.
Please have a look at the LdapPluginTests page to get an overview of LDAP ACLs
(access control lists) that manages LDAP operations on a directory.
== Permissions ==
Once LDAP support has been activated, you can use `trac-admin` as usual to
define [http://projects.edgewall.com/trac/wiki/TracPermissions TracPermissions].[[BR]]
However, you can now use the existing groups defined in your LDAP directory to
assign permissions.
A LDAP group should start with the '`@`' character
Example:
{{{
Trac [/var/local/db/trac/public]> permission list
User Action
-------------------------------
@administrators TRAC_ADMIN
@betatesters WIKI_CREATE
@betatesters WIKI_MODIFY
eblot TRAC_ADMIN
anonymous BROWSER_VIEW
anonymous CHANGESET_VIEW
anonymous FILE_VIEW
anonymous LOG_VIEW
anonymous SEARCH_VIEW
anonymous TIMELINE_VIEW
anonymous WIKI_VIEW
}}}
Here, people who are declared in the 'administrator' LDAP group have the
`TRAC_ADMIN` permission, and people who are declared in the 'betatesters'
LDAP group have the `WIKI_CREATE` and `WIKI_MODIFY` permission.
You can obviously still use permissions for regular user such as ''eblot'' in
the example above.
'''Note''': Please remember that ''anonymous'' and ''authenticated'' are special users
but are considered by the permission backend just like any other regular user.[[BR]]
This means that you need to add both these special users in your LDAP directory
if you wish to assign permission to these joker entries.
The [wiki:LdapPluginTests#Initializingthedirectory directory configuration] proposed in
the [wiki:LdapPluginTests test] page may give you some hints about how to setup
your LDAP directory.
=== Global vs. Environment permissions ===
Starting from release '''v0.3.0''', permissions are not defined globally (unless `global_perms` is set in the environment configuration file), but on per-environment basis.
With environment-wide permissions, it is now possible to define distinct permissions for each Trac environment (as long as their name differ) even if they access the same LDAP directory.[[BR]]
The Trac LDAP permission attribute value are prefixed with the environment name.[[BR]]
Using the previous example, assuming the environment name is named "test", permission attributes would become:
{{{
dn: uid=courtney,dc=example,dc=org
objectclass: user
objectclass: trac
tracperm: test:TICKET_VIEW
tracperm: test:REPORT_CREATE
tracperm: test:REPORT_VIEW
}}}
It is still possible to use global permissions by setting in the `[ldap]` section of the environment configuration file:
{{{
global_perms = true
}}}
When a directory contains global permission directives, those permissions apply on every Trac environment accessing the LDAP directory, whichever the `global_perms` value. However, permissions are always created using the current environment permission setting.
From the administrative point of view (`trac-admin`, [http://projects.edgewall.com/trac/wiki/WebAdmin WebAdmin], ...), there are no changes: permission are defined and retrieved as usual.
''Note:'' The environment ''name'' is based on the root directory of the Trac environment. This means that if you use different environment with the same name, such as:
`/var/local/trac/test` and `/var/db/test`, they are both named "test" and share the same permissions. This is a known limitation of the current implementation.
== Known limitations ==
* Only LDAP v3 protocol is supported. This extension may work with v2 protocol
as well, if the v3 specifier is removed from the code.
== !ToDo list ==
* Add user detail support so that the full name and email address are
retrieved from the LDAP server. It would require a new extension point in
Trac engine, which might be called `IUserDirectory` (not before Trac 0.11 at best)
* There's probably a lot of room for improvement (and debugging) ;-)
== Testing ==
The LdapPluginTests page gives some hints about how to test the Ldap extension for
Trac
== History ==
* '''v0.0''': First attempt to write a LDAP bridge for Trac based on Trac 0.8, which required some hacks into the Trac engine.
* '''v0.1''': A new implementation has started on September, 1st '05, to profit from the new [http://projects.edgewall.com/trac/wiki/TracPlugins TracPlugins] module architecture introduced in Trac 0.9-pre.[[BR]] This implementation should bring the following improvements:
* includes a cache to dramatically reduce LDAP requests
* better handling of LDAP errors[[BR]]This extension works with Trac 0.9-pre1 and requires the [http://peak.telecommunity.com/DevCenter/setuptools setuptools], version 0.5a13
* '''v0.2''': This new release fixes up a couple of bugs and works with Trac 0.9-pre2. It requires the [http://peak.telecommunity.com/DevCenter/setuptools setuptools], version 0.6+.[[BR]]It introduces support for LDAP permission store: TracPermissions can now be stored into the LDAP directory, rather than in the SQL backend.[[BR]]Each feature (LDAP as a provider of group permissions, LDAP as a permission store) are independent and can be enabled or disabled on demand.
* '''v0.2.1''': Bug fixing
* '''v0.2.2''': Introduce support for disting DN for users and groups (implemented suggestion described in #75)
* '''v0.2.3''': Update to support the new boolean parsing introduced in the official Trac trunk
* '''v0.3.0''': Introduce per-environment permissions: permissions are defined to the current environment and do not overlap with other Trac environments using the same LDAP directory, unless the `global_perms` configuration parameters is set.
* '''v0.4.0''': Major rewrite of the LdapPlugin to support Trac trunk [trac:changeset:3419 3419], including better support for groups (user dns may be part of a different subtree than group dns, such as `ou=people` vs. `ou=groups`), improved cache management, as well as many bug fixes and code clean up.
== Author/Contributors ==
'''Author:''' [wiki:eblot eblot] [[BR]]
'''Contributors:'''
[[TagIt(eblot,0.10,plugin)]]