9. Directory Services

FreeNAS® supports integration with these directory services:

It also supports Kerberos Realms, Kerberos Keytabs, and the ability to add more parameters to Kerberos Settings.

This section summarizes each of these services and their available configurations within the FreeNAS® GUI.

9.1. Active Directory

Active Directory (AD) is a service for sharing resources in a Windows network. AD can be configured on a Windows server that is running Windows Server 2000 or higher or on a Unix-like operating system that is running Samba version 4. Since AD provides authentication and authorization services for the users in a network, it is not necessary to recreate these user accounts on the FreeNAS® system. Instead, configure the Active Directory service so that it can import the account information and imported users can be authorized to access the SMB shares on the FreeNAS® system.

Many changes and improvements have been made to Active Directory support within FreeNAS®. It is strongly recommended to update the system to the latest FreeNAS® 11.1 before attempting Active Directory integration.

Ensure name resolution is properly configured before configuring the Active Directory service. ping the domain name of the Active Directory domain controller from Shell on the FreeNAS® system. If the ping fails, check the DNS server and default gateway settings in Network ‣ Global Configuration on the FreeNAS® system.

Add a DNS record for the FreeNAS® system on the Windows server and verify the hostname of the FreeNAS® system can be pinged from the domain controller.

Active Directory relies on Kerberos, which is a time-sensitive protocol. The time on both the FreeNAS® system and the Active Directory Domain Controller cannot be out of sync by more than a few minutes. The best way to ensure the same time is running on both systems is to configure both systems to:

  • use the same NTP server (set in System ‣ NTP Servers on the FreeNAS® system)
  • have the same timezone
  • be set to either localtime or universal time at the BIOS level

Figure 9.1.1 shows the screen that appears when Directory Service ‣ Active Directory is chosen. Table 9.1.1 describes the configurable options. Some settings are only available in Advanced Mode. To see these settings, either click Advanced Mode or configure the system to always display these settings by checking Show advanced fields by default in System ‣ Advanced.

_images/directoryservice-ad1a.png

Fig. 9.1.1 Configuring Active Directory

Table 9.1.1 Active Directory Configuration Options
Setting Value Advanced Mode Description
Domain Name (DNS/Realm-Name) string   Name of Active Directory domain (example.com) or child domain (sales.example.com). This setting is mandatory and the GUI will refuse to save the settings if the domain controller for the specified domain cannot be found.
Domain Account Name string   Name of the Active Directory administrator account. This setting is mandatory and the GUI will refuse to save the settings if it cannot connect to the domain controller using this account name.
Domain Account Password string   Password for the Active Directory administrator account. This setting is mandatory and the GUI will refuse to save the settings if it cannot connect to the domain controller using this password
AD check connectivity frequency (seconds) integer   How often to verify that Active Directory services are active.
How many recovery attempts integer   Number of times to attempt reconnecting to the Active Directory server. Tries forever when set to 0.
Enable Monitoring checkbox   Restart Active Directory automatically if the service is disconnected.
Encryption Mode drop-down menu Choices are Off, SSL, or TLS.
Certificate drop-down menu Select the certificate of the Active Directory server if SSL connections are used. If a certificate does not exist yet, create a CA, then create a certificate on the Active Directory server and import it to the FreeNAS® system with Certificates.
Verbose logging checkbox When checked, logs attempts to join the domain to /var/log/messages.
UNIX extensions checkbox Only set if the AD server is explicitly configured to map permissions for UNIX users. Enabling provides persistent UIDs and GUIDs, otherwise, users/groups are mapped to the UID/GUID range configured in Samba.
Allow Trusted Domains checkbox Only enable if the network has active domain/forest trusts and files need to be managed on multiple domains. Use with caution as it will generate more winbindd traffic, slowing down the ability to filter through user and group information.
Use Default Domain checkbox Unset to prepend the domain name to the username. If Allow Trusted Domains is set and multiple domains use the same usernames, unset to prevent name collisions.
Allow DNS updates checkbox Unset to disable Samba from doing DNS updates when joining a domain.
Disable Active Directory user/group cache checkbox Set to disable caching of AD users and groups. This is useful if the system cannot bind to a domain with a large number of users or groups.
Site Name string The relative distinguished name of the site object in Active Directory.
Domain Controller string Automatically be added to the SRV record for the domain and, when multiple controllers are specified, FreeNAS® selects the closest DC which responds. Uses the short form of the FQDN. An example is sampleserver.
Global Catalog Server string If the hostname of the global catalog server to use is specified, make sure it is resolvable.
Kerberos Realm drop-down menu Select the realm created using the instructions in Kerberos Realms.
Kerberos Principal drop-down menu Browse to the location of the keytab created using the instructions in Kerberos Keytabs.
AD timeout integer In seconds, increase if the AD service does not start after connecting to the domain.
DNS timeout integer In seconds, increase if AD DNS queries timeout.
Idmap backend drop-down menu and Edit Select the backend to use to map Windows security identifiers (SIDs) to UNIX UIDs and GIDs. See Table 9.1.2 for a summary of the available backends. Click the Edit link to configure the backend.
Windbind NSS Info drop-down menu Defines the schema to use when querying AD for user/group info. rfc2307 uses the RFC2307 schema support included in Windows 2003 R2, sfu20 is for Services For Unix 3.0 or 3.5, and sfu is for Services For Unix 2.0.
SASL wrapping drop-down menu Defines how LDAP traffic is transmitted. Choices are plain (plain text), sign (signed only), or seal (signed and encrypted). Windows 2000 SP3 and newer can be configured to enforce signed LDAP connections.
Enable checkbox   Enable the Active Directory service.
NetBIOS name string Limited to 15 characters. Automatically populated with the original hostname of the system. This must be different from the Workgroup name.
NetBIOS alias string Limited to 15 characters.

Table 9.1.2 summarizes the backends which are available in the Idmap backend drop-down menu. Each backend has its own man page which gives implementation details. Since selecting the wrong backend will break Active Directory integration, a pop-up menu will appear whenever changes are made to this setting.

Table 9.1.2 ID Mapping Backends
Value Description
ad AD server uses RFC2307 or Services For Unix schema extensions. Mappings must be provided in advance by adding the uidNumber attributes for users and gidNumber attributes for groups in the AD.
autorid Similar to rid, but automatically configures the range to be used for each domain, so there is no need to specify a specific range for each domain in the forest. The only needed configuration is the range of UID/GIDs to use for user/group mappings and an optional size for the ranges.
fruit Generate IDs the way Apple Mac OS X does, so UID and GID can be identical on all FreeNAS® servers on the network. For use in LDAP environments where Apple’s Open Directory is the authoritative LDAP server.
ldap Stores and retrieves mapping tables in an LDAP directory service. Default for LDAP directory service.
nss Provides a simple means of ensuring that the SID for a Unix user is reported as the one assigned to the corresponding domain user.
rfc2307 An AD server is required to provide the mapping between the name and SID and an LDAP server is required to provide the mapping between the name and the UID/GID.
rid Default for AD. Requires an explicit idmap configuration for each domain, using disjoint ranges where a writeable default idmap range is to be defined, using a backend like tdb or ldap.
script Stores mapping tables for clustered environments in the winbind_cache tdb.
tdb Default backend used by winbindd for storing mapping tables.
tdb2 Substitute for tdb used by winbindd in clustered environments.

Click Rebuild Directory Service Cache if a new Active Directory user needs immediate access to FreeNAS®. This occurs automatically once a day as a cron job.

Note

Active Directory places restrictions on which characters are allowed in Domain and NetBIOS names, a limits the length of those names to 15 characters. If there are problems connecting to the realm, verify the settings do not include any disallowed characters. The Administrator account password cannot contain the $ character. If a $ exists in the domain administrator’s password, kinit will report a “Password Incorrect” error and ldap_bind will report an “Invalid credentials (49)” error.

It can take a few minutes after configuring the Active Directory service for the AD information to be populated to the FreeNAS® system. Once populated, the AD users and groups will be available in the drop-down menus of the Permissions screen of a volume/dataset. For performance reasons, every available user may not show in the listing. However, it will autocomplete all applicable users when typing in a username.

The Active Directory users and groups that are imported to the FreeNAS® system are shown by typing commands in the FreeNAS® Shell:

  • View users: wbinfo -u
  • View groups: wbinfo -g

In addition, wbinfo -t tests the connection and, if successful, shows a message similar to:

checking the trust secret for domain YOURDOMAIN via RPC calls succeeded

To manually check that a specified user can authenticate, use net ads join -S dcname -U username.

getent passwd and getent group can provide more troubleshooting information if no users or groups are listed in the output.

Tip

Sometimes network users do not appear in the drop-down menu of a Permissions screen but the wbinfo commands display these users. This is typically due to the FreeNAS® system taking longer than the default ten seconds to join Active Directory. Increase the value of AD timeout to 60 seconds.

To change a certificate, set the Encryption Mode to Off, then disable AD by unchecking Enable. Click Save. Select the new Certificate, set the Encryption Mode as desired, check Enable to re-enable AD, and click Save to restart AD.

9.1.1. Troubleshooting Tips

When running AD in a 2003/2008 mixed domain, see this posting for instructions to prevent the secure channel key from becoming corrupt.

Active Directory uses DNS to determine the location of the domain controllers and global catalog servers in the network. Use host -t srv _ldap._tcp.domainname.com to determine the SRV records of the network and change the weight and/or priority of the SRV record to reflect the fastest server. More information about SRV records can be found in the Technet article How DNS Support for Active Directory Works.

The realm used depends upon the priority in the SRV DNS record. DNS can override the system Active Directory settings. When unable to connect to the correct realm, check the SRV records on the DNS server.

If the cache becomes out of sync due to an AD server being taken off and back online, resync the cache using Directory Service ‣ Active Directory ‣ Rebuild Directory Service Cache.

An expired password for the administrator account will cause kinit to fail. Ensure the password is still valid. Also, double-check the password on the AD account being used does not include any spaces, special symbols, and is not unusually long.

If the Windows server version is lower than 2008 R2, try creating a Computer entry on the Windows server’s OU. When creating this entry, enter the FreeNAS® hostname in the name field. Make sure it is under 15 characters, the same name as the one set in the Hostname field in Network ‣ Global Configuration, and the same NetBIOS Name in Directory Service ‣ Active Directory settings. Make sure the hostname of the domain controller is set in the Domain Controller field of Directory Service ‣ Active Directory.

9.1.2. If the System Will not Join the Domain

If the system will not join the Active Directory domain, run these commands in the order listed. echo commands will return a value of 0 and klist will show a Kerberos ticket:

sqlite3 /data/freenas-v1.db "update directoryservice_activedirectory set ad_enable=1;"
echo $?
service ix-kerberos start
service ix-nsswitch start
service ix-kinit start
service ix-kinit status
echo $?
klist

If the cache becomes out of sync due to an AD server being taken off and back online, resync the cache using Directory Service ‣ Active Directory ‣ Rebuild Directory Service Cache.

Note

If any of the commands fail or result in a traceback, create a bug report at https://redmine.ixsystems.com/projects/freenas/issues that includes the commands in the order in which they were run and the exact wording of the error message or traceback.

Next, only run these two commands if Unix extensions is set in Advanced Mode and a keytab has been uploaded using Kerberos Keytabs:

service ix-sssd start
service sssd start

Finally, run these commands. echo returns a 0 unless something has gone wrong:

python /usr/local/www/freenasUI/middleware/notifier.py start cifs
service ix-activedirectory start
service ix-activedirectory status
echo $?
python /usr/local/www/freenasUI/middleware/notifier.py restart cifs
service ix-pam start
service ix-cache start &

9.2. LDAP

FreeNAS® includes an OpenLDAP client for accessing information from an LDAP server. An LDAP server provides directory services for finding network resources such as users and their associated permissions. Examples of LDAP servers include Microsoft Server (2000 and newer), Mac OS X Server, Novell eDirectory, and OpenLDAP running on a BSD or Linux system. If an LDAP server is running on the network, configure the FreeNAS® LDAP service so network users can authenticate to the LDAP server and have authorized access to the data stored on the FreeNAS® system.

Note

LDAP authentication for SMB shares is disabled unless the LDAP directory has been configured for and populated with Samba attributes. The most popular script for performing this task is smbldap-tools. In addition, the LDAP server must support SSL/TLS and the certificate for the LDAP server CA must be imported with System ‣ Certificates ‣ Import Certificate. Note that non-CA certificates are not supported at this time.

Tip

Apple’s Open Directory is an LDAP-compatible directory service into which FreeNAS® can be integrated. See FreeNAS with Open Directory in Mac OS X environments.

Figure 9.2.1 shows the LDAP Configuration screen that is seen after clicking Directory Service ‣ LDAP.

_images/directoryservice-ldap1.png

Fig. 9.2.1 Configuring LDAP

Table 9.2.1 summarizes the available configuration options. Some settings are only available in Advanced Mode. To see these settings, either click the Advanced Mode button or configure the system to always display these settings by checking the box Show advanced fields by default in System ‣ Advanced.

Those new to LDAP terminology should read the OpenLDAP Software 2.4 Administrator’s Guide.

Table 9.2.1 LDAP Configuration Options
Setting Value Advanced Mode Description
Hostname string   Hostname or IP address of the LDAP server.
Base DN string   Top level of the LDAP directory tree to be used when searching for resources. Example: dc=test,dc=org.
Bind DN string   Name of administrative account on the LDAP server. Example: cn=Manager,dc=test,dc=org.
Bind password string   Password for Root bind DN.
Allow Anonymous Binding checkbox Instructs the LDAP server to not provide authentication and to allow read and write access to any client.
User Suffix string Optional. Can be added to the name when the user account is added to the LDAP directory. Example: dept. or company name.
Group Suffix string Optional. Can be added to the name when the group is added to the LDAP directory. Example: dept. or company name.
Password Suffix string Optional. Can be added to the password when the password is added to LDAP directory.
Machine Suffix string Optional. Can be added to the name when the system added to the LDAP directory. Example: server, accounting.
SUDO Suffix string Use if LDAP-based users need superuser access.
Kerberos Realm drop-down menu Select the realm created using the instructions in Kerberos Realms.
Kerberos Principal drop-down menu Browse to the location of the principal in the keytab created as described in Kerberos Keytabs.
Encryption Mode drop-down menu Choices are Off, SSL, or TLS. Note that either SSL or TLS and a Certificate must be selected in order for authentication to work.
Certificate drop-down menu Select the certificate of the LDAP CA (required if authentication is used). The certificate for the LDAP server CA must first be imported with System ‣ Certificates ‣ Import Certificate.
LDAP timeout integer Increase this value (in seconds) if obtaining a Kerberos ticket times out.
DNS timeout integer Increase this value (in seconds) if DNS queries timeout.
Idmap backend drop-down menu and Edit Select the backend to use to map Windows security identifiers (SIDs) to UNIX UIDs and GIDs. See Table 9.1.2 for a summary of the available backends. Click the Edit link to configure the selected backend.
Samba Schema checkbox Set if LDAP authentication for SMB shares is needed and the LDAP server is already configured with Samba attributes.
Auxiliary Parameters string Additional options for sssd.conf(5).
Schema drop-down menu If Samba Schema is set, select the schema to use. Choices are rfc2307 and rfc2307bis.
Enable checkbox   Unset to disable the configuration without deleting it.
NetBIOS Name string Limited to 15 characters. Automatically populated with the original hostname of the system. This must be different from the Workgroup name
NetBIOS Alias string Limited to 15 characters.

Click the Rebuild Directory Service Cache button after adding a user to LDAP who needs immediate access to FreeNAS®. Otherwise this occurs automatically once a day as a cron job.

Note

FreeNAS® automatically appends the root DN. This means the scope and root DN are not to be included when configuring the user, group, password, and machine suffixes.

LDAP users and groups appear in the drop-down menus of the guilabel:Permissions screen of a dataset after configuring the LDAP service. Type getent passwd from Shell to verify the users have been imported. Type getent group to verify the groups have been imported.

If the users and groups are not listed, refer to Common errors encountered when using OpenLDAP Software for common errors and how to fix them. When troubleshooting LDAP, open Shell and look for error messages in /var/log/auth.log.

9.3. NIS

The Network Information Service (NIS) maintains and distributes a central directory of Unix user and group information, hostnames, email aliases, and other text-based tables of information. If an NIS server is running on the network, the FreeNAS® system can be configured to import the users and groups from the NIS directory.

Note

In Windows Server 2016, Microsoft removed the Identity Management for Unix (IDMU) and NIS Server Role. See Clarification regarding the status of Identity Management for Unix (IDMU) & NIS Server Role in Windows Server 2016 Technical Preview and beyond.

Figure 9.3.1 shows the configuration screen which opens after navigating Directory Service ‣ NIS. Table 9.3.1 summarizes the configuration options.

_images/directoryservice-nis.png

Fig. 9.3.1 NIS Configuration

Table 9.3.1 NIS Configuration Options
Setting Value Description
NIS domain string Name of NIS domain.
NIS servers string Comma-delimited list of hostnames or IP addresses.
Secure mode checkbox If set, ypbind(8) will refuse to bind to any NIS server that is not running as root on a TCP port number over 1024.
Manycast checkbox If set, ypbind will bind to the server that responds the fastest. This is useful when no local NIS server is available on the same subnet
Enable checkbox Unset to disable the configuration without deleting it.

Click the Rebuild Directory Service Cache button after adding a user to NIS who needs immediate access to FreeNAS®. Otherwise this occurs automatically once a day as a cron job.

9.4. Kerberos Realms

A default Kerberos realm is created for the local system in FreeNAS®. Directory Service ‣ Kerberos Realms can be used to view and add Kerberos realms. If the network contains a KDC, click Add kerberos realm to add the realm. This configuration screen is shown in Figure 9.4.1.

_images/directoryservice-realm.png

Fig. 9.4.1 Adding a Kerberos Realm

Table 9.4.1 summarizes the configurable options. Some settings are only available in Advanced Mode. To see these settings, either click Advanced Mode or configure the system to always display these settings by checking the box Show advanced fields by default in System ‣ Advanced.

Table 9.4.1 Kerberos Realm Options
Setting Value Advanced Mode Description
Realm string   Mandatory. Name of the realm.
KDC string Name of the Key Distribution Center.
Admin Server string Server where all changes to the database are performed.
Password Server string Server where all password changes are performed.

9.5. Kerberos Keytabs

Kerberos keytabs are used to do Active Directory or LDAP joins without a password. This means the password for the Active Directory or LDAP administrator account does not need to be saved into the FreeNAS® configuration database, which is a security risk in some environments.

When using a keytab, it is recommended to create and use a less privileged account for performing the required queries as the password for that account will be stored in the FreeNAS® configuration database. To create the keytab on a Windows system, use these commands:

ktpass.exe -out hostname.keytab host/ hostname@DOMAINNAME -ptype KRB5_NT_PRINCIPAL -mapuser DOMAIN\username -pass userpass

setspn -A host/ hostname@DOMAINNAME DOMAIN\username

where:

  • hostname is the fully qualified hostname of the domain controller.
  • DOMAINNAME is the domain name in all caps.
  • DOMAIN is the pre-Windows 2000 short name for the domain.
  • username is the privileged account name.
  • userpass is the password associated with username.

This will create a keytab with sufficient privileges to grant tickets.

After the keytab is generated, use Directory Service ‣ Kerberos Keytabs ‣ Add kerberos keytab to add it to the FreeNAS® system.

To instruct the Active Directory service to use the keytab, select the installed keytab using the drop-down Kerberos keytab menu in Directory Service ‣ Active Directory. When using a keytab with Active Directory, make sure that the “username” and “userpass” in the keytab matches the “Domain Account Name” and “Domain Account Password” fields in Directory Service ‣ Active Directory.

To instruct LDAP to use a principal from the keytab, select the principal from the drop-down Kerberos Principal menu in Directory Service ‣ LDAP.

9.6. Kerberos Settings

To configure additional Kerberos parameters, use Directory Service ‣ Kerberos Settings. Figure 9.6.1 shows the fields available:

  • Appdefaults auxiliary parameters: contains settings used by some Kerberos applications. The available settings and their syntax are listed in the [appdefaults] section of krb.conf(5).
  • Libdefaults auxiliary parameters: contains settings used by the Kerberos library. The available settings and their syntax are listed in the [libdefaults] section of krb.conf(5).
_images/directoryservice-kerberos-settings.png

Fig. 9.6.1 Additional Kerberos Settings