IDMAP_AUTORID(8) System Administration tools IDMAP_AUTORID(8)NAMEidmap_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.
Samba 3.6 09/18/2013 IDMAP_AUTORID(8)