[[ldap]] === Using LDAP to Authenticate Users You can configure Shield to communicate with a Lightweight Directory Access Protocol (LDAP) directory to authenticate users. To integrate with LDAP, you configure an LDAP realm and assign LDAP groups to Shield roles in the <>. To protect passwords, communications between Shield and the LDAP server should be encrypted using SSL/TLS. Clients and nodes that connect via SSL/TLS to the LDAP server need to have the LDAP server's certificate or the server's root CA certificate installed in their keystore or truststore. For more information about installing certificates, see <>. ==== Configuring an LDAP Realm LDAP stores users and groups hierarchically, similar to the way folders are grouped in a file system. An LDAP directory's hierarchy is built from containers such as the _organizational unit_ (`ou`), _organization_ (`o`), and _domain controller_ (`dc`). The path to a entry is a _Distinguished Name_ (DN) that uniquely identifies a user or group. User and group names typically have attributes such as a _common name_ (`cn`) or _unique ID_ (`uid`). A DN is specified as a string, for example `"cn=admin,dc=example,dc=com"`. White space is ignored. The LDAP realm supports two modes of operation, a user search mode and a mode with specific templates for user DNs. See <> for all of the options you can set for an LDAP realm. [[ldap-user-search]] ===== Configuring an LDAP Realm with User Search added[1.1.0] LDAP user search is the most common mode of operation. In this mode, a specific user with permission to search the LDAP directory is used to search for the user DN based on the username and an LDAP attribute. To configure an LDAP Realm with User Search: . Add a realm configuration of type `ldap` to `elasticsearch.yml` in the `shield.authc.realms` namespace. At a minimum, you must set the realm `type` to `ldap`, specify the `url` of the LDAP server, and specify the container DN to search for users with the `user_search.base_dn` option. If you are configuring multiple realms, you should also explicitly set the `order` attribute to control the order in which the realms are consulted during authentication. See <> for all of the options you can set for an LDAP realm. + For example, the following snippet shows an LDAP realm configured with a user search: + [source, yaml] ------------------------------------------------------------ shield: authc: realms: ldap1: type: ldap order: 0 url: "ldaps://ldap.example.com:636" bind_dn: "cn=ldapuser, ou=users, o=services, dc=example, dc=com" bind_password: changeme user_search: base_dn: "dc=example,dc=com" attribute: cn group_search: base_dn: "dc=example,dc=com" files: role_mapping: "/mnt/elasticsearch/group_to_role_mapping.yml" unmapped_groups_as_roles: false ------------------------------------------------------------ . Restart Elasticsearch ===== Configuring an LDAP Realm with User DN Templates If your LDAP environment uses a few specific standard naming conditions for users, you can use User DN templates to configure the realm. The advantage of this method is that a search does not have to be performed to find the user DN. However, multiple bind operations might be needed to find the correct user DN. To configure an LDAP Realm with User Search: . Add a realm configuration of type `ldap` to `elasticsearch.yml` in the `shield.authc.realms` namespace. At a minimum, you must set the realm `type` to `ldap`, specify the `url` of the LDAP server, and specify at least one template with the `user_dn_templates` option. If you are configuring multiple realms, you should also explicitly set the `order` attribute to control the order in which the realms are consulted during authentication. See <> for all of the options you can set for an LDAP realm. + For example, the following snippet shows an LDAP realm configured with User DN templates: + [source, yaml] ------------------------------------------------------------ shield: authc: realms: ldap1: type: ldap order: 0 url: "ldaps://ldap.example.com:636" user_dn_templates: - "cn={0}, ou=users, o=marketing, dc=example, dc=com" - "cn={0}, ou=users, o=engineering, dc=example, dc=com" group_search: base_dn: "dc=example,dc=com" files: role_mapping: "/mnt/elasticsearch/group_to_role_mapping.yml" unmapped_groups_as_roles: false ------------------------------------------------------------ [[ldap-settings]] ===== LDAP Realm Settings .Common LDAP Realm Settings |======================= | Setting | Required | Description | `type` | yes | Indicates the realm type. Must be set to `ldap`. | `order` | no | Indicates the priority of this realm within the realm chain. Realms with a lower order are consulted first. Although not required, we recommend explicitly setting this value when you configure multiple realms. Defaults to `Integer.MAX_VALUE`. | `enabled` | no | Indicates whether this realm is enabled or disabled. Enables you to disable a realm without removing its configuration. Defaults to `true`. | `url` | yes | Specifies an LDAP URL of the form of `ldap[s]://:`. Shield attempts to authenticate against this URL. | `user_group_attribute` | no | Specifies the attribute to examine on the user for group membership. The default is `memberOf`. This setting will be ignored if any `group_search` settings are specified. | `group_search.base_dn` | no | Specifies a container DN to search for groups in which the user has membership. When this element is absent, Shield searches for the attribute specified by `user_group_attribute` set on the user to determine group membership. | `group_search.scope` | no | Specifies whether the group search should be `sub_tree`, `one_level` or `base`. `one_level` only searches objects directly contained within the `base_dn`. The default `sub_tree` searches all objects contained under `base_dn`. `base` specifies that the `base_dn` is a group object, and that it is the only group considered. | `group_search.filter` | no | Specifies a filter to use to lookup a group. If not set, the realm searches for `group`, `groupOfNames`, or `groupOfUniqueNames`, with the attributes `member` or `memberOf`. Any instance of `{0}` in the filter is replaced by the user attribute defined in `group_search.user_attribute` | `group_search.user_attribute` | no | Specifies the user attribute that is fetched and provided as a parameter to the filter. If not set, the user DN is passed to the filter. | `unmapped_groups_as_roles` | no | Specifies whether the names of any unmapped LDAP groups should be used as role names and assigned to the user. Defaults to `false`. | `connect_timeout` | no | Specifies the timeout period for establishing an LDAP connection. An `s` at the end indicates seconds, `ms` indicates milliseconds. Defaults to `5s` (5 seconds). | `read_timeout` | no | The timeout period for an LDAP operation. An `s` at the end indicates seconds, `ms` indicates milliseconds. Defaults to `5s` (5 seconds). | `files.role_mapping` | no | Specifies the path and file name for the <>. Defaults to `ES_HOME/config/shield/role_mapping.yml`. | `follow_referrals` | no | Specifies whether Shield should follow referrals returned by the LDAP server. Referrals are URLs returned by the server that are to be used to continue the LDAP operation (e.g. search). Defaults to `true`. | `hostname_verification` | no | Specifies whether hostname verification is performed when connecting to an LDAP server. When `true`, the hostname or IP address used in the `url` must match one of the names in the certificate or the connection will not be allowed. Due to its potential security impact, `hostname_verification` is not exposed via the {ref}/cluster-nodes-info.html#cluster-nodes-info[nodes info API]. Defaults to `true`. | `cache.ttl` | no | Specifies the time-to-live for cached user entries. A user's credentials are cached for this period of time. Specify the time period using the standard Elasticsearch {ref}/common-options.html#time-units[time units]. Defaults to `20m`. | `cache.max_users` | no | Specifies the maximum number of user entries that can be stored in the cache at one time. Defaults to 100,000. | `cache.hash_algo` | no | Specifies the hashing algorithm that is used for the cached user credentials. See <> for the possible values. (Expert Setting) |======================= .User Template LDAP Realm Settings |======================= | Setting | Required | Description | `user_dn_templates` | yes | Specifies the DN template that replaces the user name with the string `{0}`. This element is multivalued, allowing for multiple user contexts. |======================= .User Search LDAP Realm Settings added[1.1.0] |======================= | Setting | Required | Description | `bind_dn` | no | The DN of the user that is used to bind to the LDAP and perform searches. If not specified, an anonymous bind is attempted. Due to its potential security impact, `hostname_verification` is not exposed via the {ref}/cluster-nodes-info.html#cluster-nodes-info[ nodes info API]. | `bind_password` | no | The password for the user that is used to bind to the LDAP. Due to its potential security impact, `hostname_verification` is not exposed via the {ref}/cluster-nodes-info.html#cluster-nodes-info[ nodes info API]. | `user_search.base_dn` | yes | Specifies a container DN to search for users. | `user_search.scope` | no | The scope of the user search. Valid values are `sub_tree`, `one_level` or `base`. `one_level` only searches objects directly contained within the `base_dn`. `sub_tree` searches all objects contained under `base_dn`. `base` specifies that the `base_dn` is the user object, and that it is the only user considered. Defaults to `sub_tree`. | `user_search.attribute` | no | Specifies the attribute to match with the username presented to Shield. Defaults to `uid`. | `user_search.pool.size` | no | Specifies the maximum number of connections to the LDAP server to allow in the connection pool. Defaults to `20`. | `user_search.pool.initial_size` | no | The initial number of connections to create to the LDAP server on startup. Defaults to `5`. | `user_search.pool.health_check.enabled` | no | Enables or disables a health check on LDAP connections in the connection pool. Connections are checked in the background at the specified interval. Defaults to `true`. | `user_search.pool.health_check.dn` | no | Specifies the distinguished name to retrieve as part of the health check. Defaults to the value of `bind_dn`. If `bind_dn` is not configured, you must specify a value. | `user_search.pool.health_check.interval` | no | How often to perform background checks of connections in the pool. Defaults to `60s`. |======================= NOTE: If any settings starting with `user_search` are specified, the `user_dn_templates` the settings are ignored. [[assigning-roles-ldap]] ==== Assigning LDAP Groups to Roles To configure privileges for LDAP users, you assign LDAP groups to roles in the role mapping file stored on each node. When a user authenticates with LDAP, the privileges for that user are the union of all privileges defined by the roles assigned to the set of groups that the user belongs to. You specify groups using their distinguished names. For example, the following mapping configuration assigns the LDAP `admins` group both the `monitoring` and `user` roles, and assigns the `user` role to the `users` group. [source, yaml] ------------------------------------------------------------ monitoring: <1> - "cn=admins,dc=example,dc=com" <2> user: - "cn=users,dc=example,dc=com" <3> - "cn=admins,dc=example,dc=com" ------------------------------------------------------------ <1> The name of a role defined in <>. <2> The distinguished name of the `admins` group. <3> The distinguished name of the `users` group. For more information, see <>. ==== Encrypting Communications Between Shield and LDAP with SSL/TLS You should encrypt communications between Shield and your LDAP server to protect the user credentials that are sent to for authentication. Connecting via SSL/TLS ensures that the identity of the LDAP server is authenticated before Shield transmits the user credentials, and the user names and passwords are encrypted in transit. To encrypt communications between Shield and your LDAP server: . Configure each node to trust certificates signed by the CA that signed your LDAP server certificates. For example, the following command imports `cacert.pem` into node01's keystore. (For information about using truststores, see <>.) + [source,shell] -------------------------------------------------- cd CONFIG_DIR/shield keytool -importcert -keystore node01.jks -file cacert.pem -alias ldap_ca -------------------------------------------------- + The CA cert must be a PEM encoded certificate. + [NOTE] =============================== You can also import the individual server certificates rather than the CA certificate, but this is only recommended if you have a single LDAP server. You can fetch the LDAP server certificate with `openssl`. For example, the following command gets the certificate for `ldap.example.com` and stores it locally in `ldap.crt`. [source, shell] ---------------------------------------------------------------------------------------------- echo | openssl s_client -connect ldap.example.com:636 2>/dev/null | openssl x509 > ldap.crt ---------------------------------------------------------------------------------------------- If you are using an older version of openssl you might need to use use the `-host` and `-port` options rather than the `-connect` option. =============================== . If you haven't already configured the path to the node's keystore or truststore in `elasticsearch.yml`, set the `shield.ssl.keystore.path` or `shield.ssl.truststore.path` attributes. For example: + [source, yaml] -------------------------------------------------- shield.ssl.keystore.path: /home/es/config/shield/node01.jks <1> shield.ssl.keystore.password: myPass <2> shield.ssl.keystore.key_password: myKeyPass <3> -------------------------------------------------- <1> The full path to the node keystore file. This must be a location within the Elasticsearch configuration directory. <2> The password used to access the keystore. <3> The password used to access the certificate. This is only required if you specified a separate certificate password when generating the certificate. + For more information, see <>. . Set the `url` attribute in the realm configuration to specify the LDAPS protocol and the secure port number. For example, `url: ldaps://ldap.example.com:636`. . Restart Elasticsearch to pick up the changes to `elasticsearch.yml`. NOTE: By default, when you configure Shield to connect to an LDAP server using SSL/TLS, Shield attempts to verify the hostname or IP address specified with the `url` attribute in the realm configuration with the values in the certificate. If the values in the certificate and realm configuration do not match, Shield does not allow a connection to the LDAP server. This is done to protect against man in the middle attacks. If necessary, you can disable this behavior by setting the <> property to `false`. `hostname_verification` is considered to be a sensitive setting and is not exposed via {ref}/cluster-nodes-info.html#cluster-nodes-info[nodes info API].