IDMAP_AD(8)

📦
version 4.24.7 · 27 versions
, in fedora 44

✨ IDMAP_AD — Samba's idmap_ad Backend for Winbind ✨

ok bestie, so this is idmap_ad(8), the manual page for the idmap_ad backend. It's a Winbind thing, it's very "read-only queen", and we're gonna get you all the way through it 💅

💖 NAME 💖

idmap_ad — Samba's idmap_ad Backend for Winbind

🦋 DESCRIPTION 🦋

So the idmap_ad plugin is literally the way Winbind reads id mappings off an AD server that's running RFC2307/SFU schema extensions. That's its whole thing. 🌸

Now, important: this module implements only the "idmap" API, and it is READONLY. Not "read-only-ish". READONLY. Periodt. 😤

Which means the mappings have to be handed over in advance by the administrator — you go into the AD and add uidNumber attributes for users and gidNumber attributes for groups. That's on you, bestie, the plugin will not do it for you.

Winbind will only map users that have a uidNumber and whose primary group has a gidNumber attribute set. That "and" is doing a lot of heavy lifting, so pay attention. 👑

And yeah — it is however recommended that all groups in use have gidNumber attributes assigned, otherwise they are not working. No cap, an unassigned group is just... not working. 🫠

Now for the plot twist: currently, the ad backend does not work as the default idmap backend. Not the main character in that slot, sorry. Instead you have to configure it separately for each domain you want to use it for, and you use disjoint ranges while you're at it.

You'll usually also need to configure a writeable default idmap range — using, for example, the tdb or ldap backend — so you can actually map the BUILTIN sids and possibly other trusted domains. 💫

And the writeable default config is also needed in order to be able to create group mappings. Yes, both. It's giving "you need the boring one so the cool one can function."

This catch-all default idmap configuration should have a range that is disjoint from any explicitly configured domain with idmap backend ad. See the example below, we gotchu. 👇

✨ IDMAP OPTIONS ✨

  • range = low - high — Defines the available matching UID and GID range for which the backend is authoritative. Note that the range acts as a filter. If specified, any UID or GID stored in AD that falls outside the range is ignored and the corresponding map is discarded. It's intended as a way to avoid accidental UID/GID overlaps between local and remotely defined IDs. 🚧
  • schema_mode = <rfc2307 | sfu | sfu20> — Defines the schema that idmap_ad should use when querying Active Directory regarding user and group information. This can be either the RFC2307 schema support included in Windows Server 2003 R2 and newer, or the Service for Unix (SFU) schema for versions before Windows Server 2003 R2. For SFU 3.0 or 3.5 please choose "sfu", for SFU 2.0 please choose "sfu20". Please note that the behavior of primary group membership is controlled by the unix_primary_group option.

Default: rfc2307

  • unix_primary_group = yes/no — Defines whether the user's primary group is fetched from the SFU attributes or the AD primary group. If set to yes, the primary group membership is fetched from the LDAP attributes (gidNumber). If set to no, the primary group membership is calculated via the "primaryGroupID" LDAP attribute.

Default: no

  • unix_nss_info = yes/no — If set to yes, winbind will retrieve the login shell and home directory from the LDAP attributes. If set to no, or the AD LDAP entry lacks the SFU attributes, the options template shell and template homedir are used.

Default: no

  • all_groupmem = yes/no — If set to yes, winbind will retrieve all group members for getgrnam(3), getgrgid(3) and getgrent(3) calls, including those with missing uidNumber.

Default: no

  • deny ous — This parameter is a list of OUs from which objects will not be mapped via the ad idmap module. If deny ous is set but allow ous is not set, every object outside the OUs listed in deny ous is allowed.

Default: none

  • allow ous — This parameter is a list of OUs from which objects will be mapped via the ad idmap module. If allow ous is set but deny ous is not set, every object outside the OUs allow ous is denied.

If both allow ous and deny ous are set, deny ous is evaluated first, then allow ous is looked at. If an AD object matches neither, it is denied. 🚫

Default: none

🌈 EXAMPLES 🌈

The following example shows how to retrieve idmappings from our principal and trusted AD domains. If trusted domains are present, id conflicts must be resolved beforehand — there is no guarantee on the order conflicting mappings would be resolved at this point. 😭

This example also shows how to leave a small non conflicting range for local id allocation that may be used in internal backends like BUILTIN.

[global]
workgroup = CORP

idmap config * : backend = tdb
idmap config * : range = 1000000-1999999

idmap config CORP : backend  = ad
idmap config CORP : range = 1000-999999

👑 AUTHOR 👑

The original Samba software and related utilities were created by Andrew Tridgell. Samba is now developed by the Samba Team as an Open Source project similar to the way the Linux kernel is developed.

ok that's the whole page, you ate that fr fr 🫶 this was IDMAP_AD(8) from Samba 4.24.7, dated 09/09/2026 — go forth and map those ids, bestie 💖✨🎀

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