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Connecting to Active Directory (AD)

Sara Levy
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Active Directory Overview

VAST Cluster leverages Active Directory (AD) two ways:

  • Via direct AD queries using native AD APIs.

  • Via LDAP queries using LDAP APIs since AD is also an LDAP server.

Configuring a connection to Active Directory can therefore include either of the following:

  • Configuring LDAP connectivity to Active Directory, as for configuring LDAP connectivity to any other LDAP-based directory server. This is relevant in the case where you are using Active Directory to authorize file and directory access via NFSv3. (It is also theoretically relevant for NFSv4.1 access if, atypically, NFSv4.1 were used without Kerberos authentication or ID mapping.)

  • Both LDAP connectivity to Active Directory and the AD domain join process, in which the VAST Cluster is added to an AD domain as a new directory object. The AD domain join is required for enabling SMB access to the cluster. Similarly, in order to enable NFSv4.1 access with Kerberos authentication or with ID mapping, AD domain join is required.

Prerequisites for SMB Access

  • Active Directory running on Windows Server 2008R2 or newer.

  • A domain name served by Active Directory, and a DNS setup to resolve the domain name.

  • User credentials for an admin user with permission to create and modify machine accounts within the Organizational Unit (OU) in the Active Directory domain to which you want to add the new machine object for the cluster.

 

Configuration Requirements for SMB Access

  • Views exposed as SMB shares work only if the cluster is joined to Active Directory. This includes views that are exposed only to SMB and multiprotocol views that are exposed to both SMB and NFS.

  • As part of the LDAP configuration, you must map LDAP attributes to the AD schema. This step is required for SMB access to work.

 

Configuration Requirements for NFS Access

  • Typically, NFSv4.1 access is used with Kerberos authentication and ID mapping. Kerberos and NFS4 ID mapping require that the cluster is joined to Active Directory. When configuring LDAP connectivity in this case, be sure to set advanced attribute mappings as required for NFS4 ID mapping.

  • If you're using Active Directory as an LDAP server for NFSv3 access, follow Connecting to an LDAP Server.

 

AD Domain Auto-Discovery

VAST Cluster supports client user access from multiple automatically discovered Active Directory (AD) domains, with automatic discovery of domain controllers (DCs).

Auto-discovery is an optional setting that you can enable or disable in the LDAP configuration for Active Directory.

When auto-discovery is enabled, VAST Cluster automatically discovers all domains and domain controllers in the AD forest. When the cluster queries AD for users and groups, all discovered domains are queried. After initial discovery is complete, you can view the discovered AD objects, including AD global catalog servers. The information is updated periodically, with indication of the time to the next refresh of the global catalog that is currently used by the cluster.

You can choose whether to use LDAP over TLS (LDAPS) for AD domain auto-discovery. If set to use LDAPS, VAST Cluster connects to port 636 for the domain controller or port 3269 for the global catalog and initiates a TLS handshake immediately afterwards.

When auto-discovery is disabled, VAST Cluster contacts only manually configured domain controllers and does not process requests from users in other domains in the AD forest. You have to specify LDAP URIs and the search base DN in the LDAP configuration for Active Directory.

 
 

Joining Active Directory

Joining AD and Configuring LDAP via VAST Web UI

  1. From the left navigation menu, select User Management and then Active Directory.

  2. Click Create Active Directory to create a new Active Directory record.

  3. Under Active Directory, fill in the fields for creating the machine object on the Active Directory domain:

    Field

    Description

    Machine account name (required)

    Specify a name for the machine object that will be created for the cluster within Active Directory, inside the Organizational Unit (see next). It is recommended to name the machine name the same as the cluster name for simplicity.

    Organizational unit (required)

    The organizational unit (OU) in the Active Directory domain in which to create the machine object.

    Specify as a Distinguished Name (DN).

    For example: OU=Computers,DC=company-ad,DC=com

  4. If you want to use this Active Directory configuration for SMB client access, enable SMB Allowed. Only one AD can be SMB allowed per cluster.

  5. Under LDAP, if LDAP connectivity to Active Directory has already been configured on the cluster, select the existing LDAP configuration from the dropdown list. Otherwise, select Create new ldap.

  6. Complete the LDAP fields to configure LDAP connectivity to Active Directory:

    Field

    Description

    URLs (required if Auto-discovery is off)

    This field is available only if Auto-discovery is disabled.

    Enter a comma-separated list of URIs of the AD domain's domain controllers (DCs). The order of listing defines the priority order. The DC with highest priority that has a good health status is used.

    Specify the URI of each DC in the format <scheme>://<address>. <address> can be either a DNS name or an IP address.

    Examples:

    • ldap://company-ad.com

    • ldap://company-ad.com,ldap://company-ad2.com

    • ldap://192.0.2.0,ldap://192.0.2.1,ldap://192.0.2.2

    Auto-discovery

    When enabled, VAST Cluster automatically discovers and queries all domains and domain controllers in the Active Directory forest. For more information, see AD Domain Auto-Discovery.

    When disabled, the LDAP URI ( URLs ) and search base DN ( Base DN ) fields must be specified manually. VAST Cluster contacts only the domain controller configured in the URLs field and does not process requests from users in other domains in the Active Directory forest.

    Port (required)

    The port to append to the URI.

    Recommended values: 389 for LDAP (with or without TLS), 636 for LDAPS.

    Note

    The recommended values are required if Auto-discovery and Use TLS are enabled. Failing to set the recommended port value can cause LDAP to disconnect.

    Use LDAPS

    Enables or disables use of LDAP over TLS (LDAPS) if Auto-discovery is enabled.

    When enabled, VAST Cluster connects to an alternative port (port 636 for the domain controller, port 3269 for the Global Catalog) and initiates a TLS handshake immediately afterwards.

    Domain name

    The fully qualified domain name (FQDN) of the Active Directory domain to join.

    Example: company-ad.com

    Authentication method (required)

    The LDAP authentication method that the AD domain controller uses to authenticate clients:

    • Anonymous. The AD domain controller accepts queries without any authentication.

    • Simple. The AD domain controller attempts to bind a specified user name to a matching AD user. If the LDAP bind succeeds, VAST Cluster is allowed access to perform the query. Set also Bind DN and Bind password.

    Base DN

    This field is available only if Auto-discovery is disabled.

    The entry in the Active Directory tree to use as a starting point for user queries. By default, this is also used as the starting point for group queries. Optionally, you can specify a different entry as the Group Base DN.

    To maximize the speed of authentication queries, start the search in the lowest branch of the tree under which all users can be found. For example, if the entire directory must be queried, the search base must specify the root of the tree. However, if the search can be restricted to a specific organizational unit (OU), queries may be faster.

    The format for base DN is a comma separated list of components. Each component is an attribute=value pair defining an object in the directory tree. The first component defines the object at the lowest part of the tree that you want to use as the starting point of the search, the next component is its container and so on up the tree, with the last component representing the top level domain.

    The following attributes can be specified:

    • cn: common name

    • ou: organizational unit

    • o: organization

    • c: country

    • dc: domain

    For example, supposing your user accounts are all located in a container called 'users' under a domain 'mydomain.local'. If you want to set the users container as the starting point for search queries, you would enter: ou=users,dc=mydomain,dc=local

    To specify the full domain as your search base, you would enter: dc=mydomain,dc=local

    Bind DN (required if Authentication method is set to Simple)

    Enter the bind DN for authenticating to the LDAP domain. You can specify any user account that has read access to the domain.

    Format is as described for Search base beginning with a cn attribute component specifying the user object.

    For example, cn=admin,ou=users,dc=mydomain,dc=local specifies user 'admin' located in the 'users' container under the domain 'mydomain.local'.

    Bind password (required if Authentication method is set to Simple)

    This field appears if Simple is selected in the Method field. This is the password used with the Bind DN to authenticate to the AD domain controller.

    Query Group Mode

    Sets the mode for querying a users' auxiliary group memberships, where applicable:

    Note

    Group memberships may or may not be queried during access checks depending on the Group Membership Source setting in the View Policy.

    • Compatible (default). Groups are queried using an aggregate of the RFC2307BIS and RFC2307 compliant group membership queries (see the other options). You can use this default option unless you are using an authentication provider which is incompatible with this aggregated query mode.

    • RFC2307BIS only. Auxiliary group memberships are queried according to the RFC2307BIS standard, in which the group has a member attribute that contains the Distinguished Name (DN) of the member user and the user has a memberOf attribute which contains the DNs of the groups to which the user belongs. This standard is used by Active Directory and may be used with other LDAP-based authorization providers with LDAP schema extensions.

    • RFC2307 only. Auxiliary group memberships are queried according to the RFC2307 standard, in which the group object has a memberUid attribute for each user object that is a member of the group, specifying the name of the user object. This standard may be used by openLDAP, freeIPA and other LDAP-based authorization providers.

    • None. If this option is selected, auxiliary group memberships are not queried at all. In the event that the relevant view's view policy cites the authorization provider as the group membership source and the user tries to access a file or directory within that view to which the user only has permission as a member of a the owning user's group, permission will not be granted.

    Use TLS

    Enable to use TLS to secure communication between VAST Cluster and the LDAP server.

    When enabled, VAST Cluster connects to the standard port (port 389 for the domain controller, port 3268 for the Global Catalog) and performs a StartTLS operation as defined in RFC 4513.

    TLS certificate

    If Use TLS is enabled, use this field to provide a certificate if you want the cluster to verify the LDAP server's TLS certificate. The remote LDAP server's TLS certificate will be verified against the certificate you provide. If the certificate you provide does not list the certificate authority (CA) of the server's certificate, the cluster will fail to establish a connection with the LDAP server.

    If you choose to leave this field blank, the VAST Cluster's TLS client will not request the LDAP server's TLS certificate and will ignore any certificate received.

    Important

    Regardless of this field's value, ensure that the LDAP server is not configured to request client certificates (TLSVerifyClient should be set to never). Otherwise, connections will fail.

    VMS Auth Provider

    When enabled, this LDAP configuration is the one that can be used for authentication of VMS users. Only one LDAP server can be used for VMS authentication.

    Reverse lookup

    Enables reverse lookup for LDAP netgroups. By default, this option is disabled.

  7. Click Advanced-attribute mappings to make sure that the correct object class names will be used to query provider's entries and ensure that the user authorization process will find users and groups on the provider.

    Do the following:

    1. Select a template from the Templates for advanced setting dropdown. This fills the attribute mapping fields with a base set of values before you make any custom modifications:

      • AD. Fills all the attribute mapping fields with RFC2307BIS-compliant values, typically used in Active Directory.

        Note

        This value is required to enable SMB access to the cluster.

      • Open LDAP. Fills all the attribute mapping fields with RFC2307-compliant values, used by OpenLDAP and other LDAP-based providers.

      • Custom. Presents you with mostly empty fields to fill with customer values.

    2. In the Group base DN field, specify the entry in the AD directory tree to use as a starting point for group queries. By default, the Base DN is used.

    3. Check that the values are set correctly for your provider, and make changes as needed. Consult the following table for a description of each value you need to specify:

      Field

      Description

      Default (RFC2307 Compliant)

      AD Equivalent

      gidNumber

      The attribute of a group entry that contains the GID number of a group.

      gidNumber

      gidNumber

      uid

      The attribute of a user entry that contains the user name.

      uid

      sAMAccountName (common, use unless you know otherwise). Also can be uid (rare) or cn (rare).

      uidNumber

      The attribute of a user entry that contains the UID number.

      uidNumber

      uidNumber

      memberUid

      The attribute of the group entry that contains names of group members.

      memberUID

      member

      PosixAccount

      The object class that defines a user entry.

      posixAccount

      user

      PosixGroup

      The object class that defines a group entry.

      posixGroup

      group

      Match User

      The attribute to use when querying a provider for a user that matches a user that was already retrieved from another provider. A user entry that contains a matching value in this attribute will be considered the same user as the user previously retrieved.

      Equal to the setting for uid.

      sAMAccountName

      Username Property Name

      The attribute to use when querying a provider for a user when the query is initiated by a VMS user.

      cn

      name

      user login name

      Applicable only for Active Directory and only for NFSv4 with client-enabled ID matching. This field specifies the attribute used to query AD for the user login name for NFS4 ID mapping.

      On NDU, this value is set to sAMAccountname for Active Directory configurations.

      uid

      sAMAccountName

      group login name

      Applicable only for Active Directory and only for NFSv4.1 with client-enabled ID matching. This field specifies the attribute used to query AD for the group login name for NFS4 ID mapping.

      On NDU, this value is set to sAMAccountname for Active Directory configurations.

      cn

      sAMAccountName

      uid member value property name

      Specifies the attribute which represents the value of the LDAP group's member property.

      uid

      sAMAccountName

      mail property name

      The attribute to use for the user's email address.

      		    

  8. Click Create.

    The record is now created and you can see it displayed. The JOINED status is displayed as NO because the cluster has not yet joined the AD domain.

  9. Click Actions_Button.png to open the Actions menu for the configuration record and select Join to join the AD domain.

  10. Supply a user name and password for an admin user with permission to join the AD domain. (These credentials are used only for a one time connection and not stored on the cluster.)

    This may take a few moments. When the cluster has joined the AD domain, the status displayed in the JOINED column changes to YES.

 

Joining AD and Configuring LDAP via VAST CLI

  1. Run ldap create to configure LDAP connectivity to Active Directory.

    Note

    If you are going to enable AD domain auto-discovery, specify a single URI in the --url parameter. Also note that the auto-discovery feature cannot be enabled right on the initial ldap create command. It must be enabled with an ldap modify command after the Active Directory configuration is created (as a last step in this procedure).

    vcli: admin> ldap create --urls ldap://company-ad.com,ldap://company-ad2.com --port 389 --binddn cn=admin,ou=users,dc=mycompanyad,dc=com --bindpw **** --basedn ou=users,dc=mycompanyad,dc=com --group-searchbase ou=groups,dc=mycompanyad,dc=com --method simple --use-tls --domain-name co-ad.com --posix-templates AD

    An LDAP configuration record is created.

  2. Run ldap list to find out the ID of the newly created LDAP configuration record. in this example, the ID is 2.

  3. Run activedirectory create with the LDAP configuration record ID specified on the --ldap-id parameter:

    vcli: admin> activedirectory create --ldap-id 2 --machine-account-name co-vcluster  --organizational-unit OU=Computers,DC=co-ad,DC=com

    An AD configuration record is created.

  4. Run activedirectory list to find out the ID of the AD configuration record. In this example, the ID is 3.

  5. Run activedirectory modify with the AD configuration record ID specified on the --id parameter. Add the --enabled option to join the AD domain. Specify --admin-username and provide a user name of an AD admin user with permission to join the AD domain:

    vcli admin> activedirectory modify --id 3 --enabled --admin-username USER

  6. Confirm that you wish to proceed:

    Are you sure you want to modify the Active directory? [y/N] y

  7. Enter the password for the AD admin user when prompted:

    Enter admin password:
Password:

Waiting ...

[2022-03-31 10:18:39] waiting for active directory My_AD enabled state to change to True ... /

Completed
vcli: admin>

  8. Run activedirectory list again and verify that the Active Directory configuration state is now Enabled.

  9. If you want to enable AD domain auto-discovery, run ldap modify with the LDAP configuration record ID specified on the --ldap-id parameter. Add the --enable-auto-discovery option and specify the AD template:

    vcli: admin> ldap modify --ldap-id 2 --enable-auto-discovery --advanced-settings-templates AD
 
 

Viewing Discovered AD Topology

When AD domain auto-discovery is enabled, you can view the discovered AD topology as follows:

Viewing Discovered Domains

To view automatically discovered AD domains:

  • Via VAST Web UI: On the Active Directory tab, click Actions_Button.png to open the Actions menu for the Active Directory configuration and select Show AD Domains.

  • Via VAST CLI: Run the activedirectory show_ad_domains command.

The display lists each of the discovered AD domains in the AD forest with indication of its fully qualified domain name (FQDN), search base DN, and security identifier (SID).

Note

When AD domain auto-discovery is disabled or AD information is not available, a No data to show or similar error message is displayed.

 

Viewing Discovered DCs of the Joined Domain

To view automatically discovered domain controllers (DC) of the AD domain that the cluster has joined:

  • Via VAST Web UI: On the Active Directory tab, click Actions_Button.png to open the Actions menu for the Active Directory configuration and select Show Joined Domain DCs.

  • Via VAST CLI: Run the activedirectory show_joined_domain_dcs command.

The display lists each of the discovered DCs in the cluster's joined domain with indication of its URI, status (such as HEALTHY or FAILED), and whether it is on the same AD site as the cluster.

Note

When AD domain auto-discovery is disabled or AD information is not available, a No data to show or similar error message is displayed.

 

Viewing Discovered Global Catalog Servers

To view automatically discovered AD global catalog (GC) servers:

  • Via VAST Web UI: On the Active Directory tab, click Actions_Button.png to open the Actions menu for the Active Directory configuration and select Show AD Global Catalog.

  • Via VAST CLI: Run the activedirectory show_ad_gcs command.

The display shows the URI of the AD global catalog (GC) server that is currently used by the cluster and the time to the next global catalog refresh (in seconds). Following is a list of other discovered GC servers, each with indication of its URI, status (such as HEALTHY or FAILED), and whether it is on the same AD site as the cluster.

Note

When AD domain auto-discovery is disabled or AD information is not available, a No data to show or similar error message is displayed.

 
 

Leaving Active Directory

When you leave an AD domain, the cluster's machine account is deleted from the AD domain controller.

If the AD domain controller is not accessible to the cluster when you try to leave the AD domain, the leave will fail. In this case, you can effectively force the cluster to leave the AD domain by removing the AD configuration from the cluster. The machine account will remain on the AD domain controller, where it can be manually deleted.

  • Via VAST Web UI: On the Active Directory tab, click Actions_Button.png to open the Actions menu for the Active Directory configuration and select Leave.

  • Via VAST CLI: Run the activedirectory modify command with the --disabled option.

 
 

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