Idmap config ad
Introduction
The ad
ID mapping back end implements a read-only API to read account and group information from Active Directory (AD). The back end is based on RFC 2307. For further details, see https://www.rfc-editor.org/rfc/rfc2307.txt.
For alternatives, see Identity Mapping Back Ends.
![]() | ID mapping back ends are not supported in the smb.conf file on a Samba Active Directory (AD) domain controller (DC).For details, see Failure To Access Shares on Domain Controllers If idmap config Parameters Set in the smb.conf File. |
Advantages and Disadvantages of the ad
Back End
Advantages:
- Central administration of IDs inside Active Directory (AD).
- Consistent IDs on all Samba clients and servers using the
ad
back end. - The required attributes only need creating once, this can be done when the user or group is created
- IDs are not stored in a local database that can corrupt and thus file ownerships are not lost.
Disadvantages:
- If the Windows
Active Directory Users and Computers
(ADUC) program is not used, you have to manual track ID values to avoid duplicates. - The values for the RFC2307 attributes must be set manually.
Winbind NSS info mode-specific features:
rfc2307
: Individual login shells and home directory paths for users.template
: The login shells and home directory base paths are the same for all users.
Planning the ID Ranges
Before configuring the ad
back end in the smb.conf
file, you must select unique ID ranges for each domain. The ranges must be continuous and big enough to enable Samba to assign an ID for every future user and group created in the domain.
![]() | The ID ranges of the * default domain and all other domains configured in the smb.conf file must not overlap. |
Prerequisites
To enable Samba to retrieve user and group information from Active Directory (AD):
- Users must have at least the
uidNumber
and groups thegidNumber
attribute set. When using therfc2307
winbind NSS info
mode, user accounts must also have theloginShell
,unixHomeDirectory
andprimaryGroupID
set. - Computers, or: 'machine network accounts', must have the
uidNumber
attribute set to access shares on samba domain members. - The user, computer, and group IDs must be within the range configured in the
smb.conf
for this domain. - If the
Active Directory Users and Groups
(ADUC) utility is used to assign the UNIX attributes, the NIS extensions have to be installed. For details, see Setting up RFC2307 in AD. - User and computer IDs must be unique for all users and computers, and group IDs must be unique for all groups. Duplicate IDs or reusing IDs of previously deleted accounts enable the new user, computer, or group to access files created by the other or previous ID owner. When using the ADUC utility, the user and group IDs are automatically tracked inside AD and incremented when creating a new user or group.
- Computer IDs (
uidNumber
attribute) are not automatically tracked inside AD and must be set manually in the ADUC Attribute Editor tab when a computer is joined to the domain.
The RFC2307
and template
Mode Options
Before Samba version 4.6.0:
The ad
ID mapping back end supports two modes, set in the winbind nss info
parameter in the [global]
section of the smb.conf
file:
winbind nss info = rfc2307
: All information is read from Active Directory (AD):
- Users: Account name, UID, login shell, home directory path, and primary group.
- Groups: Group name and GID.
winbind nss info = template
: Only the following values are read from AD:
- Users: Account name, UID, and primary group.
- The login shell and home directory are automatically set by user-independent settings in the
smb.conf
file.
- Groups: Group name and GID
From Samba version 4.6.0:
You no longer use the winbind nss info
parameter, it has been replaced by idmap config DOMAIN : unix_nss_info
The ad
ID mapping back end supports two modes, set in the idmap config DOMAIN : unix_nss_info
parameter in the [global]
section of the smb.conf
file:
idmap config DOMAIN : unix_nss_info = yes
: All information is read from Active Directory (AD):
- Users: Account name, UID, login shell, home directory path, and primary group.
- Groups: Group name and GID.
- These settings are set on a DOMAIN basis, this means you can have different settings for each DOMAIN.
- If a user lacks the RFC2307 attributes, the login shell and home directory are automatically set by user-independent settings in the
smb.conf
file.
idmap config DOMAIN : unix_nss_info = no
: Only the following values are read from AD:
- Users: Account name, UID, and primary group.
- The login shell and home directory are automatically set by user-independent settings in the
smb.conf
file.
- Groups: Group name and GID
- This is the default setting.
There is now a new setting unix_primary_group
, this allows you to use another group for the users primary group instead of Domain Users.
- If this is set with
unix_primary_group = yes
, the users primary group is obtained from the gidNumber attribute found in the users AD object. - If this is set with
unix_primary_group = no
, the users primary group is calculated via the "primaryGroupID" attribute. - The default is 'no'
- If this is set with
Configuring the ad
Back End
- Set the following in the
[global]
section of yoursmb.conf
file:
- If no back end for local
BUILTIN
accounts and groups on the domain member is configured, add thetdb
back end for the*
default domain and set an ID range. For example:
- If no back end for local
# Default idmap config for local BUILTIN accounts and groups idmap config * : backend = tdb idmap config * : range = 3000-7999
- Setting the default back end is mandatory.
- To configure the
ad
back end using the10000-999999
ID range for theSAMDOM
domain:
- To configure the
# idmap config for the SAMDOM domain idmap config SAMDOM:backend = ad idmap config SAMDOM:schema_mode = rfc2307 idmap config SAMDOM:range = 10000-999999
You must set the back end, schema mode, and range for every domain, except for the *
default domain. The ID ranges of the*
default domain and all other domains configured in thesmb.conf
file must not overlap.
- Configure the Winbind NSS info mode:
- To enable the
template
mode and set, for example,/bin/bash
as shell and/home/%U
as home directory path:
- To enable the
# Template settings for login shell and home directory template shell = /bin/bash template homedir = /home/%U
- The settings are applied to all users in each domain that has the
schema_mode = rfc2307
parameter set. From Samba 4.6.0, the global template settings can be overwritten on a domain-basis by enabling theidmap config domain_name:unix_nss_info
parameter.
- The settings are applied to all users in each domain that has the
- Samba resolves the
%U
variable to the session user name. For details, see theVARIABLE SUBSTITUTIONS
section in thesmb.conf(5)
man page.
- Samba resolves the
- To enable retrieving shell and home directory from Active Directory (AD), set the following value in the
[global]
section in yoursmb.conf
file:
- From Samba 4.6.0, enable this feature on a per-domain basis:
- To enable retrieving shell and home directory from Active Directory (AD), set the following value in the
idmap config SAMDOM:unix_nss_info = yes
- on Samba 4.5 and previous, set this feature globally for all domains:
winbind nss info = rfc2307
- By default, Samba sets the Windows primary group as primary group for mapped domain user entries on Unix. The Windows primary group is retrieved from the
primaryGroupID
attribute of each user entry, this is usually set to theDomain Users
group RID. This RID is then used to obtain thegidNumber
attribute from the Windows primary group.
- If you are running Samba 4.6.0 or later, you can optionally configure Samba to use the primary group set in the
gidNumber
attribute in the users entry instead. For example, when using theActive Directory Users and Computers
application, this attribute is displayed in theUNIX Attributes
tab. To use the group ID set in the usersgidNumber
attribute as primary group for each user instead of the Windows primary group, enable the following parameter in the[global]
section in yoursmb.conf
file:
idmap config SAMDOM:unix_primary_group = yes
Whichever setting you use, the group (or groups) set as the users primary group must have the gidNumber
attribute set. For example, if you only use theDomain Users
group as the primary group for all accounts, then theDomain Users
group must have agidNumber
attribute set. Winbind is unable to map accounts that use primary groups that do not have thegidNumber
attribute set.
- Reload Samba:
# smbcontrol all reload-config
For further details, see the smb.conf(5)
and idmap_ad(5)
man page.