Authentifizierung über LDAP
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Diese Authentifizierungsmethode verwendet einen LDAP-Server, um zu prüfen, ob die Anmeldedaten eines Nutzers (Anmeldename / Kennwort) gültig sind.
Dieser Artikel beschreibt, wie die Authentifizierung über LDAP konfiguriert wird. Wir gehen zunächst von einem Basisszenario aus, betrachten dann ein erweitertes Szenario und zeigen abschließend, wie man mit möglichen Fehlerfällen umgehen kann.
Aktivierung
Die Aktivierung der Authentifizierung über einen LDAP-Server erfolgt auf der Seite
- Website-Administration > Nutzer/innen > Authentifizierung > Übersicht (ab Moodle 1.9)
- Website-Administration > Nutzer/innen > Authentifizierung (bis Moodle 1.9)
Klicken Sie in der Liste auf das geschlossene Auge-Symbol 
in der Zeile LDAP-Server.
Spezifische Einstellungen
Spezifische Einstellungen für die Authentifizierung über LDAP nehmen Sie auf folgender Seite vor:
- Website-Administration > Nutzer/innen > Authentifizierung > Übersicht > LDAP-Server > Einstellungen (ab Moodle 1.9)
- Website-Administration > Nutzer/innen > Authentifizierung > LDAP-Server > Einstellungen (bis Moodle 1.9)
Basisszenario
Dieses Szenario entspricht einer einfachen Grundkonfiguration, die für die meisten Installation geeignet ist. Nehmen wir beispielhaft folgende Voraussetzungen an:
- Ihre Moodle-Installation ist über http://your.moodle.site/ erreichbar.
- Sie haben auf dem Moodle-Server PHP inklusive der LDAP-Erweiterung installiert und aktiviert, und dies wird unter http://your.moodle.site/admin/phpinfo.php angezeigt, wenn Sie sich als Administrator in Moodle anmelden.
- Ihr LDAP-Server hat die IP-Adresse 192.168.1.100.
- Sie verwenden kein LDAP mit SSL (auch bekannt als ldaps).
- Sie möchten nicht, dass Nutzer beim ersten Login in Moodle ihr Kennwort ändern.
- Sie verwenden eine einzige Domain als Quelle für ihre Authentifizierungsdaten im Fall, dass Sie das MS Active Directory verwenden.
- Sie verwenden den DN-Namen dc=my,dc=organization,dc=domain als Wurzel Ihres LDAP-Baums.
- Sie haben einen Bind-Nutzer, der die Verbindung zum LDAP-Server aufnimmt. Stellen Sie sicher, das Nutzername und Kennwort dieses Bind-Nutzers dauerhaft gültig sind, und verwendet Sie ein möglichst starkes Kennwort. Sie müssen dieses Kennwort nur einmal bei der Konfiguration der LDAP-Authentifizierung angeben. Der Anmeldename dieses Bind-Nutzers sei in unserem Basisszenario cn=ldap-user,dc=my,dc=organization,dc=domain, und das Kennwort sei ein_ganz_starkes_Kennwort.
- Alle Moodle-Nutzer gehören zu einer Organisationseinheit (OU), die moodleusers heißt und direkt unterhalb der Wurzel des LDAP-Baums liegt. Diese Organsiationseinheit hat den DN-Namen ou=moodleusers,dc=my,dc=organization,dc=domain.
- Sie möchten nicht, dass die LDAP-Kennwörter Ihrer Nutzer in der Moodle-Datenbank gespeichert werden.
Für dieses Basisszenario müssen Sie nun folgende spezifischen Einstellungen vornehmen:
LDAP Server-Einstellungen
| Name | Wert |
|---|---|
| Host URL | As the IP of your LDAP server is 192.168.1.100, type "ldap://192.168.1.100" (without the quotes), or just "192.168.1.100" (some people have trouble connecting with the first syntax, specially on MS Windows servers). |
| Version | Unless you are using a really old LDAP server, version 3 is the one you should choose. |
| LDAP Codierung | Specify encoding used by LDAP server. Most probably utf-8. |
Bind-Einstellungen
| Name | Wert |
|---|---|
| Kennwörter verbergen | As you don't want to store the users's password in Moodle's database, choose Yes here. |
| Gekennzeichneter Name | This is the distinguished name of the bind user defined above. Just type "cn=ldap-user,dc=my,dc=organization,dc=domain" (without the quotes). |
| Kennwort | This is the bind user password defined above. Type "hardtoguesspassword" (without the quotes). |
Einstellungen zur Nutzerüberprüfung
| Name | Wert |
|---|---|
| Nutzertyp | Choose:
|
| Kontexte | The DN of the context (container) where all of your Moodle users are found. Type ou=moodleusers,dc=my,dc=organization,dc=domain here. |
| Subkontexte suchen | If you have any sub organizational units (subcontexts) hanging from ou=moodleusers,dc=my,dc=organization,dc=domain and you want Moodle to search there too, set this to yes. Otherwise, set this to no. |
| Alias berücksichtigen | Sometimes your LDAP server will tell you that the real value you are searching for is in fact in another part of the LDAP tree (this is called an alias). If you want Moodle to 'dereference' the alias and fetch the real value from the original location, set this to yes. If you don't want Moodle to dereference it, set this to no. If you are using MS-AD, set this to no. |
| Nutzerattribute | The attribute used to name/search users in your LDAP tree. This option takes a default value based on the User type value you choosed above. So unless you need something special, you don't need to fill this in.
By the way, it's usually cn (Novell eDirectory and MS-AD) or uid (RFC-2037, RFC-2037bis and SAMBA 3.x LDAP extension), but if you are using MS-AD you could use sAMAccountName (the pre-Windows 2000 logon account name) if you need too. |
| Mitgliedsattribut | The attribute used to list the members of a given group. This option takes a default value based on the User type value you choosed above. So unless you need something special, you don't need to fill this in.
By the way, the usual values are member and memberUid. |
| Mitgliedsattribut nutzt dn | Whether the member attribute contains distinguished names (1) or not (0).This option takes a default value based on the User type value you choosed above. So unless you need something special, you don't need to fill this in. |
| Objekt Class | The type of LDAP object used to search for users. This option takes a default value based on the User type value you choosed above. So unless you need something special, you don't need to fill this in.
Here are the default values for each of the ldap_user_type values:
If you get an error about a problem with updating the ldap server (even if you have specified not to write changes back to the ldap server) try setting the ldap object class to * - see http://moodle.org/mod/forum/discuss.php?d=70566 for a discussion on this problem |
Verbindliche Änderung des Passwortes
| Name | Wert |
|---|---|
| Verbindliche Änderung des Passwortes | Set this to Yes if you want to force your users to change their password on the first login into Moodle. Otherwise, set this to no. Bear in mind the password they are forced to change is the one stored in your LDAP server.
As you don't want your users to change their passwords in their first login, leave this set to No |
| Standardseite zur Passwortänderung nutzen |
Bear in mind that changing your LDAP passwords from Moodle might require a LDAPS connection (this is actually a requirement for MS-AD). In addition to that, the bind user specified above must have the rights needed to change other users' passwords. Also, code for changing passwords from Moodle for anything but Novell eDirectory and Active Directory is almost not tested, so this may or may not work for other LDAP servers. |
| Passwortformat | Specify how the new password is encrypted before sending it to the LDAP server: Plain text, MD5 hash or SHA-1 hash. MS-AD uses plain text, for example. |
| URL zur Kennwortänderung | Here you can specify a location at which your users can recover or change their username/password if they've forgotten it. This will be provided to users as a button on the login page and their user page. if you leave this blank the button will not be printed. |
LDAP Passwortablaufeinstellung
| Name | Wert |
|---|---|
| Ablauf |
Current code only deals with Novell eDirectory LDAP server and MS-AD. So unless you have Novell eDirectory server or MS-AD, choose No here. |
| Ablaufhinweis | This value sets how many days in advance of password expiration the user is warned that her password is about to expire. |
| Ablauf-Attribut | The LDAP user attribute used to check password expiration. This option takes a default value based on the User type value you choosed above. So unless you need something special, you don't need to fill this in. |
| Grace Login | This setting is specific to Novell eDirectory. If set to Yes, enable LDAP gracelogin support. After password has expired the user can login until gracelogin count is 0.
So unless you have Novell eDirectory server and want to allow gracelogin support, choose No here. |
| grace Login Attribute | This setting is currently not used in the code (and is specific to Novell eDirectory).
So you don't need to fill this in. |
Nutzer-Erstellung aktivieren
| Name | Wert |
|---|---|
| Nutzer extern anlegen | New (anonymous) users can self-create user accounts on the external LDAP server and confirm them via email. If you enable this, remember to also configure module-specific options for user creation and to fill in some instructions in auth_instructions field in Administration >> Users >> Authentication >> Manage authentication. Otherwise the new users won't be able to self-create new accounts.
As of now, only Novell eDirectory and MS-AD can create users externally. |
| Kontext für neue Nutzer | Specify the context where users are created. This context should be different from other users' contexts to prevent security issues. |
Kursverwalter/in
| Name | Wert |
|---|---|
| Kursverwalter/innen | The DN of the group that contains all of your Moodle creators. This is typically a posixGroup with a "memberUid" attribute for each user you want to be a creator. If your group is called creators, type cn=creators,ou=moodleusers,dc=my,dc=organization,dc=domain here. Each memberUid attribute contains the CN of a user who is authorized to be a creator. Do not use the user's full DN (e.g., not memberUid: cn=JoeTeacher,ou=moodleusers,dc-my,dc=organizations,dc=domain, but rather memberUid: JoeTeacher).
In eDirectory, the objectClass for a group is (by default) not posixGroup but groupOfNames, whose member attribute is member, not memberUid, and whose value is the full DN of the user in question. Although you can probably modify Moodle's code to use this field, a better solution is just to add a new objectClass attribute of posixGroup to your creators group and put the CNs for each creator in a memberUid attribute. In MS Active Directory, you will need to create a security group for your creators to be part of and then add them all. If your ldap context above is 'ou=staff,dc=my,dc=org' then your group should then be 'cn=creators,ou=staff,dc=my,dc=org'. If some of the users are from other contexts and have been added to the same security group, you'll have to add these as separate contexts after the first one using the same format. |
Cron-Synchronisierungsskript
| Name | Wert |
|---|---|
| Entfernte externe Nutzer | Specify what to do with internal user account during mass synchronization when user was removed from external source. Only suspended users are automatically revived if they reappear in ext source. |
NTLM SSO
| Name | Wert |
|---|---|
| Aktivieren | If you want to use NTLM SSO (see details at NTLM_authentication), choose Yes here. Otherwise, choose No. |
| Subnet | Specify the subnets of the clients that will use NTLM SSO (see details at NTLM_authentication). |
Data Mapping
| Name | Wert |
|---|---|
| Vorname | The name of the attribute that holds the first name of your users in your LDAP server. This is usually givenName.
This setting is optional |
| Nachname | The name of the attribute that holds the surname of your users in your LDAP server. This is usually sn.
This setting is optional |
| E-Mail-Adresse | The name of the attribute that holds the email address of your users in your LDAP server. This is usually mail.
This setting is optional |
| Stadt/Ort | The name of the attribute that holds the city/town of your users in your LDAP server. This is usully l (lowercase L) or localityName (not valid in MS-AD).
This setting is optional |
| Land | The name of the attribute that holds the couuntry of your users in your LDAP server. This is usully c or countryName (not valid in MS-AD).
This setting is optional |
| Sprache | preferredLanguage
This setting is optional |
| Beschreibung | description
This setting is optional |
| Webseite | This setting is optional |
| ID-Nummer |
This setting is optional |
| Institution |
This setting is optional |
| Abteilung | The name of the attribute that holds the department name of your users in your LDAP server. This is usully departmentNumber (for posixAccount and maybe eDirectory) or department (for MS-AD).
This setting is optional |
| Telefon 1 | The name of the attribute that holds the telephone number of your users in your LDAP server. This is usually telephoneNumber.
This setting is optional |
| Telefon 2 | The name of the attribute that holds an additional telephone number of your users in your LDAP server. This can be homePhone, mobile, pager, facsimileTelephoneNumber or even others.
This setting is optional |
| Adresse | The name of the attribute that holds the street address of your users in your LDAP server. This is usully streetAddress or street'.
This setting is optional |
Setting up regular automatic synchronisation using cron
There is a script located at /auth/ldap/auth_ldap_sync_users.php which will create or suspend/delete (see the setting above) all LDAP accounts automatically. Ideally, this is called from the command line once a day during a quiet time using exactly the same procedure as the standard cron job (so you will end up with two cron entries). It is important, however, to make sure that all of the above LDAP settings are working properly before you try this, as well as backing up your database and moodledata folders. Poor LDAP configuration could lead to users being wrongly deleted.
If you find that the script is not running through all of your users properly and you have MS Active Directory + over 1000 users, this is because by default, MS AD only sends back 1000 users at a time. Follow the instructions here to set the MaxPageSize setting to a number higher than your total number of users (both now and in future) to fix it.
Active Directory help
Active Directory is Microsoft's directory service. It is included in Windows 2000 Server and later versions of their operating system. For more information about subjects below, please go here.
- Warning: The PHP LDAP module does not seem to be present
- LDAP-module cannot connect any LDAP servers
- Getting correct CNs for Contexts and Creators
- Getting the right user_attribute
- Installing ldp.exe Server Tool
- Example Active Directory Configuration
- Child Domains and the Global Catalog in MS Active Directory
- Enabling the Global Catalog
- Active Directory with Moodle 1.8
- MS Active Directory + SSL
Advanced Scenarios - Multiple servers or locations
For larger installations with multiple LDAP servers, or multiple locations (contexts) in a LDAP tree.
Using multiple LDAP Servers
Entering more than one name in the ldap_host_url field can provide some sort of resilience to your system. Simply use the syntax : ldap://my.first.server ; ldap://my.second.server ; ...
Of course, this will only work if all the servers share the same directory information, using a replication or synchronization mecanism once introduced in eDirectory and now generalized to the main LDAP-compatible directories.
There is one drawback in Moodle 1.5 - 1.6 implementation of LDAP authentication : the auth_ldap_connect() function processes the servers sequentially, not in a round robin mode. Thus, if the primary server fails, you will have to wait for the connection to time out before switching to the following one.
Using multiple user locations (contexts) in your LDAP tree
There is no need to use multiple user locations if your directory tree is flat, i.e. if all user accounts reside in a ou=people,dc=my,dc=organization,dc=domain or ou=people,o=myorg container.
At the opposite, if you use the ACL mecanism to delegate user management, there are chances that your users will be stored in containers like ou=students,ou=dept1,o=myorg and ou=students,ou=dept2,o=myorg ...
Then there is an alternative :
- Look at the o=myorg level with the ldap_search_sub attribute set to yes.
- Set the ldap_context to ou=students,ou=dept1,o=myorg ; ou=students,ou=dept2,o=myorg.
Choosing between these two solutions supposes some sort of benchmarking, as the result depends heavily on the structure of your directory tree and on your LDAP software indexing capabilities. Simply note that there is a probability in such deep trees that two users share the same common name (cn), while having different distinguished names. Then only the second solution will have a deterministic result (returning allways the same user).
Using LDAPS (LDAP + SSL)
Enabling LDAPS on the LDAP server side
Enabling LDAPS on the client side (Moodle server)
- If you are running Moodle on MS Windows, you need to tell PHP's OpenLDAP extension to disable SSL server certificate checking. You must create a directory called C:\OpenLDAP\sysconf. In this directory, create a file called ldap.conf with the following content:
TLS_REQCERT never
- If you are running Moodle on Linux or any other Unix-like operating system, and you want to disable SSL server certificate checking, you need to edit the OpenLDAP client configuration file (usually /etc/ldap.conf or /etc/ldap/ldap.conf or even /etc/openldap/ldap.conf) and make sure you have a line like the following one:
TLS_REQCERT never
Now you should be able to use ldaps:// when connecting to your LDAP server.
If you have the certificate of the LDAPS server as a file and want to check the certificate for the connection, copy the certificate file to an arbitary directory (e.g. /etc/ldap/certificate.pem) on your client and change the content of the ldap.conf as follows:
TLS_REQCERT demand TLS_CACERT /etc/ldap/certificate.pem
When the requested server certificate is bad or not provided, the connection to the LDAPS server is immediately terminated.
Appendices
ldap auth_user_create() only suports Novell
After configuring user authentication with ldap I realized ldap only support edir (Novell) when combining ldap an email user confirmation. For example in my case (I use openldap) I have the following error after filling the user form:
auth: ldap auth_user_create() does not support selected usertype:"rfc2307" (..yet)
Setting Resource Limits RedHat Directory Server
Operational attributes can be set for the bind user DN using the command-line. One can simply use ldapmodify to add the following attributes:
| Attribute Name | Description |
|---|---|
| nsLookThroughLimit | Specifies how many entries are examined for a search operation. Giving this attribute a value of -1 indicates that there is no limit. |
| nsSizeLimit | Specifies the maximum number of entries the server returns to a client application in response to a search operation. Giving this attribute a value of -1 indicates that there is no limit. |
| nsTimeLimit | Specifies the maximum time the server spends processing a search operation. Giving this attribute a value of -1 indicates that there is no time limit. |
| nsIdleTimeout | Specifies the time a connection to the server can be idle before the connection is dropped. The value is given in seconds. Giving this attribute a value of -1 indicates that there is no limit. |
LDAP Console Command-Line ldapmodify -h redhat_dir_server -p 389 -D "cn=directory manager" -w secretpwd dn: uid=MoodleAdmin,ou=system,dc=myschool,dc=edu changetype: modify add:nsSizeLimit nsSizeLimit: 1000
Siehe auch
- Authentifizierung
- Module für die Authentifizierung verwalten
- Kurseinschreibung über LDAP
- LDAP auth and enrolment set-up guide (PDF 227KB)
- User authentication forum - Diskussionsforum im Kurs Using Moodle auf moodle.org
- PHP LDAP module does not seem to be present - Diskussionsbeitrag im Kurs Using Moodle auf moodle.org
