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IDMAP_AUTORID(8)          System Administration tools         IDMAP_AUTORID(8)

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 number of uids/gids available per domain range. The
           minimum needed value is 2000. SIDs with RIDs larger than this value
           will be mapped into extension ranges depending upon number of
           available ranges. If the autorid backend runs out of available
           ranges, mapping requests for new domains (or new extension ranges
           for domains already known) are ignored and the corresponding map is
           discarded.

           Example: with rangesize set to 10000, users/groups with a RID up to
           10000 will be put into the first range for the domain. When
           attempting to map the an object with a RID of 25000, an extension
           range will be allocated that will then be used to map all RIDs from
           20000-29999.

           One range will be used for local users and groups and for
           non-domain well-known SIDs like Everyone (S-1-1-0) or Creator Owner
           (S-1-3-0). A chosen list of well-known SIDs will be preallocated on
           first start to create deterministic mappings for those.

           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.

       read only = [ yes | no ]
           Turn the module into read-only mode. No new ranges will be
           allocated nor will new mappings be created in the idmap pool.
           Defaults to no.

       ignore builtin = [ yes | no ]
           Ignore any mapping requests for the BUILTIN domain. Defaults to no.

THE MAPPING FORMULAS
       The Unix ID for a RID is calculated this way:

                          ID =  REDUCED RID + IDMAP RANGE LOW VALUE + RANGE NUMBER * RANGE SIZE

       where REDUCED RID = RID % RANGE_SIZE and a DOMAIN RANGE INDEX = RID /
       RANGE_SIZE is used together with the domain sid to determine the RANGE
       NUMBER (stored in the database).

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

                          RID = (ID - LOW ID) % RANGE SIZE + DOMAIN RANGE INDEX * RANGE SIZE

       Where the DOMAIN RANGE INDEX is retrieved from the database along with
       the domain sid by the RANGE NUMBER = (ID - LOW ID) / RANGE SIZE .

EXAMPLES
       This example shows you the minimal configuration that will work for the
       principal domain and 19 trusted domains / range extensions.

                [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.

Samba 4.2                         12/10/2015                  IDMAP_AUTORID(8)