## Name

idmap_autorid — Samba's idmap_autorid Backend for Winbind

## DESCRIPTION

The idmap_autorid backend provides a way to use an algorithmic mapping scheme to map UIDs/GIDs and SIDs that is more deterministic than idmap_tdb and easier to configure than idmap_rid.

The module works similar to idmap_rid, but it 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 configuration that is needed is the range of uid/gids that shall be used for user/group mappings and an optional size of the ranges to be used.

The mappings of which domain is mapped to which range is stored in autorid.tdb, thus you should backup this database regularly.

Due to the algorithm being used, it is the module that is most easy to use as it only requires a minimal configuration.

## IDMAP OPTIONS

rangesize = numberofidsperdomain

  Defines the available number of uids/gids per domain. The minimum needed value is 2000. SIDs with RIDs larger than this value cannot be mapped, are ignored and the corresponding map is discarded. Choose this value carefully, as this should not be changed after the first ranges for domains have been defined, otherwise mappings between domains will get intermixed leading to unpredictable results. Please note that RIDs in Windows Domains usually start with 500 for builtin users and 1000 for regular users. As the parameter cannot be changed later, please plan accordingly for your expected number of users in a domain with safety margins.

  One range will be used for local users and groups. Thus the number of local users and groups that can be created is limited by this option as well. If you plan to create a large amount of local users or groups, you will need set this parameter accordingly.

  The default value is 100000.

## THE MAPPING FORMULAS

The Unix ID for a RID is calculated this way:

    			ID = IDMAP UID LOW VALUE + DOMAINRANGENUMBER * RANGESIZE + RID

Correspondingly, the formula for calculating the RID for a given Unix ID is this:

    			RID = ID - IDMAP UID LOW VALUE - DOMAINRANGENUMBER * RANGESIZE

## EXAMPLES

This example shows you the minimal configuration that will work for the principial domain and 19 trusted domains.

    	[global]
    	security = ads
    	workgroup = CUSTOMER
    	realm = CUSTOMER.COM

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

This example shows how to configure idmap_autorid as default for all domains with a potentially large amount of users plus a specific configuration for a trusted domain that uses the SFU mapping scheme. Please note that idmap ranges and sfu ranges are not allowed to overlap.

    	[global]
    	security = ads
    	workgroup = CUSTOMER
    	realm = CUSTOMER.COM

    	idmap config * : backend = autorid
    	idmap config * : range = 1000000-19999999
    	idmap config * : rangesize = 1000000

    	idmap config TRUSTED : backend  = ad
    	idmap config TRUSTED : range    = 50000 - 99999
    	idmap config TRUSTED : schema_mode = sfu

## 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.