5.1. UserIdResolvers

Each organisation or company usually has its users managed at a central location. This is why privacyIDEA does not provide its own user management but rather connects to existing user stores.

UserIdResolvers are connectors to those user stores, the locations, where the users are managed. Nowadays this can be LDAP directories or especially Active Directory, some times FreeIPA or the Redhat 389 service. But classically users are also located in files like /etc/passwd on standalone unix systems. Web services often use SQL databases as user store.

Today with many more online cloud services SCIM is also an uprising protocol to access userstores.

privacyIDEA already comes with UserIdResolvers to talk to all these user stores:

  • Flatfile resolver,

  • LDAP resolver,

  • SQL resolver,

  • SCIM resolver.

Note

New resolver types (python modules) can be added easily. See the module section for this (UserIdResolvers).

You can create as many UserIdResolvers as you wish and edit existing resolvers. When you have added all configuration data, most UIs of the UserIdResolvers have a button “Test resolver”, so that you can test your configuration before saving it.

Starting with privacyIDEA 2.4 resolvers can be editable, i.e. you can edit the users in the user store. Read more about this at Manage Users.

Note

Using the policy authentication:otppin=userstore users can authenticate with the password from their user store, being the LDAP password, SQL password or password from flat file.

5.1.1. Flatfile resolver

Flatfile resolvers read files like /etc/passwd.

Note

The file /etc/passwd does not contain the unix password. Thus, if you create a flatfile resolver from this file the functionality with otppin=userstore is not available. You can create a flatfile with passwords using the tool privacyidea-create-pwidresolver-user which is usually found in /opt/privacyidea/bin/.

Create a flat file like this:

privacyidea-create-pwidresolver-user -u user2 -i 1002 >> /your/flat/file

5.1.2. LDAP resolver

The LDAP resolver can be used to access any kind of LDAP service like OpenLDAP, Active Directory, FreeIPA, Penrose, Novell eDirectory.

../_images/ldap-resolver.png

LDAP resolver configuration

In case of Active Directory connections you might need to check the box No anonymous referral chasing. The underlying LDAP library is only able to do anonymous referral chasing. Active Directory will produce an error in this case 1.

The Server URI can contain a comma separated list of servers. The servers are used to create a server pool and are used with a round robin strategy 3.

Example:

ldap://server1, ldaps://server2:1636, server3, ldaps://server4

This will create LDAP requests to

  • server1 on port 389

  • server2 on port 1636 using SSL

  • server3 on port 389

  • server4 on port 636 using SSL.

The Bind Type with Active Directory can either be chosen as “Simple” or as “NTLM”.

Note

When using bind type “Simple” you need to specify the Bind DN like cn=administrator,cn=users,dc=domain,dc=name. When using bind type “NTLM” you need to specify Bind DN like DOMAINNAME\username.

The LoginName attribute is the attribute that holds the loginname. It can be changed to your needs.

Starting with version 2.20 you can provide a list of attributes in LoginName Attribute like:

sAMAccountName, userPrincipalName

This way a user can login with either his sAMAccountName or his principalName.

The searchfilter is used to list all possible users, that can be used in this resolver. The searchfilter is used for forward and backward search the object in LDAP.

The attribute mapping maps LDAP object attributes to user attributes in privacyIDEA. privacyIDEA knows the following attributes:

  • phone,

  • mobile,

  • email,

  • surname,

  • givenname,

  • password

  • accountExpires.

The above attributes are used for privacyIDEA’s normal functionality and are listed in the userview. However, with a SAML authentication request user attributes can be returned. (see SAML Attributes). To return arbitrary attributes from the LDAP you can add additional keys to the attribute mapping with a key, you make up and the LDAP attribute like:

"homedir": "homeDirectory",
"studentID": "objectGUID"

“homeDirectory” and “objectGUID” being the attributes in the LDAP directory and “homedir” and “studentID” the keys returned in a SAML authentication request.

The MULTIVALUEATTRIBUTES config value can be used to specify a list of user attributes, that should return a list of values. Imagine you have a user mapping like { "phone" : "telephoneNumber", "email" : "mail", "surname" : "sn", "group": "memberOf"}. Then you could specify ["email", "group"] as the multi value attribute and the user object would return the emails and the group memberships of the user from the LDAP server as a list.

Note

If the MULTIVALUEATTRIBUTES is left blank the default setting is “mobile”. I.e. the mobile number will be returned as a list.

The MULTIVALUEATTRIBUTES can be well used with the samlcheck endpoint (see Validate endpoints) or with the policy add_user_in_response.

The UID Type is the unique identifier for the LDAP object. If it is left blank, the distinguished name will be used. In case of OpenLDAP this can be entryUUID and in case of Active Directory objectGUID. For FreeIPA you can use ipaUniqueID.

Note

The attributes entryUUID, objectGUID, and ipaUniqueID are case sensitive!

The option No retrieval of schema information can be used to disable the retrieval of schema information 4 in order to improve performance. This checkbox is deactivated by default and should only be activated after having ensured that schema information are unnecessary.

The CACHE_TIMEOUT configures a short living per process cache for LDAP users. The cache is not shared between different Python processes, if you are running more processes in Apache or Nginx. You can set this to 0 to deactivate this cache.

The Server pool retry rounds and Server pool skip timeout settings configure the behavior of the LDAP server pool. When establishing a LDAP connection, the resolver uses a round-robin strategy to select a LDAP server from the pool. If the current server is not reachable, it is removed from the pool and will be re-inserted after the number of seconds specified in the skip timeout. If no server from the pool is reachable, the servers are queried again from the beginning. If a reachable server has not been found after the number of rounds specified in the retry rounds, the request fails.

By default, knowledge about unavailable pool servers is not persisted between requests. Consequently, a new request may retry to reach unavailable servers, even though the skip timeout has not passed yet. If the Per-process server pool is enabled, knowledge about unavailable servers is persisted within each process. This setting may improve performance in situations in which a LDAP server from the pool is down for extended periods of time.

5.1.2.1. TLS certificates

Starting with privacyIDEA 2.18, in case of encrypted LDAPS connections privacyIDEA can verify the TLS certificate. (Python >= 2.7.9 required) To have privacyIDEA verify the TLS certificate, you need to check the according checkbox.

You can specify a file with the trusted CA certificate, that signed the TLS certificate. The default CA filename is /etc/privacyidea/ldap-ca.crt and can contain a list of base64 encoded CA certificates. PrivacyIDEA will use the CA file if specifed. If you leave the field empty it will also try the system certificate store (/etc/ssl/certs/ca-certificates.crt or /etc/ssl/certs/ca-bundle.crt).

5.1.2.2. Modifying users

Starting with privacyIDEA 2.12, you can define the LDAP resolver as editable. I.e. you can create and modify users from within privacyIDEA.

There are two additional configuration parameters for this case.

DN Template defines how the DN of the new LDAP object should be created. You can use username, surname, givenname and basedn to create the distiguished name.

Examples:

CN=<givenname> <surname>,<basedn>

CN=<username>,OU=external users,<basedn>

uid=<username>,ou=users,o=example,c=com

Object Classes defines which object classes the user should be assigned to. This is a comma separated list. The usual object classes for Active Directory are

top, person, organizationalPerson, user, inetOrgPerson

5.1.2.3. Expired Users

You may set

“accountExpires”: “accountExpires”

in the attribute mapping for Microsoft Active Directories. You can then call the user listing API with the parameter accountExpires=1 and you will only see expired accounts.

This functionality is used with the script privacyidea-expired-users.

5.1.3. SQL resolver

The SQL resolver can be used to retrieve users from any kind of SQL database like MySQL, PostgreSQL, Oracle, DB2 or sqlite.

../_images/sql-resolver.png

SQL resolver configuration

In the upper frame you need to configure the SQL connection. The SQL resolver uses SQLAlchemy internally. In the field Driver you need to set a driver name as defined by the SQLAlchemy dialects like “mysql” or “postgres”.

In the SQL attributes frame you can specify how the users are identified.

The Database table contains the users.

Note

At the moment, only one table is supported, i.e. if some of the user data like email address or telephone number is located in a second table, those data can not be retrieved.

The Limit is the SQL limit for a userlist request. This can be important if you have several thousand user entries in the table.

The Attribute mapping defines which table column should be mapped to which privayIDEA attribute. The known attributes are:

  • userid (mandatory),

  • username (mandatory),

  • phone,

  • mobile,

  • email,

  • givenname,

  • surname,

  • password.

The password attribute is the database column that contains the user password. This is used, if you are doing user authentication against the SQL database.

Note

There is no standard way to store passwords in an SQL database. privacyIDEA supports the most common ways like Wordpress hashes starting with $P or $S. Secure hashes starting with {SHA} or salted secure hashes starting with {SSHA}, {SSHA256} or {SSHA512}. Password hashes of length 64 are interpreted as OTRS sha256 hashes.

You can mark the users as Editable. The Password_Hash_Type can be used to determine which hash algorithm should be used, if a password of an editable user is written to the database.

You can add an additional Where statement if you do not want to use all users from the table.

The poolSize and poolTimeout determine the pooling behaviour. The poolSize (default 5) determine how many connections are kept open in the pool. The poolTimeout (default 10) specifies how long the application waits to get a connection from the pool.

Note

The pooling parameters only have an effect if the PI_ENGINE_REGISTRY_CLASS config option is set to "shared" (see Engine Registry Class). If you then have several SQL resolvers with the same connection and pooling settings, they will use the same shared connection pool. If you change the connection settings of an existing connection, the connection pool for the old connection settings will persist until the respective connections are closed by the SQL server or the web server is restarted.

Note

The Additional connection parameters refer to the SQLAlchemy connection but are not used at the moment.

5.1.4. SCIM resolver

SCIM is a “System for Cross-domain Identity Management”. SCIM is a REST-based protocol that can be used to ease identity management in the cloud.

The SCIM resolver is tested in basic functions with OSIAM 2, the “Open Source Idenity & Access Management”.

To connect to a SCIM service you need to provide a URL to an authentication server and a URL to the resource server. The authentication server is used to authenticate the privacyIDEA server. The authentication is based on a Client name and the Secret for this client.

../_images/scim-resolver.png

User information is then retrieved from the resource server.

The available attributes for the Attribute mapping are:

  • username (mandatory),

  • givenname,

  • surname,

  • phone,

  • mobile,

  • email.

5.1.5. User Cache

privacyIDEA does not implement local user management by design and relies on UserIdResolvers to connect to external user stores instead. Consequently, privacyIDEA queries user stores quite frequently, e.g. to resolve a login name to a user ID while processing an authentication request, which may introduce a significant slowdown. In order to optimize the response time of authentication requests, privacyIDEA 2.19 introduces the user cache which is located in the local database. It can be enabled in the system configuration (see User Cache).

A user cache entry stores the association of a login name in a specific UserIdResolver with a specific user ID for a predefined time called the expiration timeout, e.g. for one week. The processing of further authentication requests by the same user during this timespan does not require any queries to the user store, but only to the user cache.

The user cache should only be enabled if the association of users and user ID is not expected to change often: In case a user is deleted from the user store, but can still be found in the user cache and still has assigned tokens, the user will still be able to authenticate during the expiration timeout! Likewise, any changes to the user ID will not be noticed by privacyIDEA until the corresponding cache entry expires.

Expired cache entries are not deleted from the user cache table automatically. Instead, the tool privacyidea-usercache-cleanup should be used to delete expired cache entries from the database, e.g. in a cronjob.

However, cache entries are removed at some defined events:

  • If a UserIdResolver is modified or deleted, all cache entries belonging to this resolver are deleted.

  • If a user is modified or deleted in an editable UserIdResolver, all cache entries belonging to this user are deleted.

Note

Realms with multiple UserIdResolvers are a special case: If a user userX tries to authenticate in a realm with two UserIdResolvers resolverA (with highest priority) and resolverB, the user cache is queried to find the user ID of userX in the UserIdResolver resolverA. If the cache contains no matching entry, resolverA itself is queried for a matching user ID! Only if resolverA does not find a corresponding user, the user cache is queried to determine the user ID of userX in resolverB. If no matching entry can be found, resolverB is queried.

Footnotes

1

http://blogs.technet.com/b/ad/archive/2009/07/06/referral-chasing.aspx

2

http://www.osiam.org

3

https://github.com/cannatag/ldap3/blob/master/docs/manual/source/servers.rst#server-pool

4

http://ldap3.readthedocs.io/schema.html