1IDMAP_AUTORID(8)          System Administration tools         IDMAP_AUTORID(8)
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NAME

6       idmap_autorid - Samba's idmap_autorid Backend for Winbind
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DESCRIPTION

9       The idmap_autorid backend provides a way to use an algorithmic mapping
10       scheme to map UIDs/GIDs and SIDs that is more deterministic than
11       idmap_tdb and easier to configure than idmap_rid.
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13       The module works similar to idmap_rid, but it automatically configures
14       the range to be used for each domain, so there is no need to specify a
15       specific range for each domain in the forest, the only configuration
16       that is needed is the range of uid/gids that shall be used for
17       user/group mappings and an optional size of the ranges to be used.
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19       The mappings of which domain is mapped to which range is stored in
20       autorid.tdb, thus you should backup this database regularly.
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22       Due to the algorithm being used, it is the module that is most easy to
23       use as it only requires a minimal configuration.
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IDMAP OPTIONS

26       range = low - high
27           Defines the available matching uid and gid range for which the
28           backend is authoritative. Note that the range acts as a filter. If
29           algorithmically determined UID or GID fall outside the range, they
30           are ignored and the corresponding map is discarded. It is intended
31           as a way to avoid accidental UID/GID overlaps between local and
32           remotely defined IDs.
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34       rangesize = numberofidsperdomain
35           Defines the number of uids/gids available per domain range. The
36           minimum needed value is 2000. SIDs with RIDs larger than this value
37           will be mapped into extension ranges depending upon number of
38           available ranges. If the autorid backend runs out of available
39           ranges, mapping requests for new domains (or new extension ranges
40           for domains already known) are ignored and the corresponding map is
41           discarded.
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43           Example: with rangesize set to 10000, users/groups with a RID up to
44           10000 will be put into the first range for the domain. When
45           attempting to map the an object with a RID of 25000, an extension
46           range will be allocated that will then be used to map all RIDs from
47           20000-29999.
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49           One range will be used for local users and groups and for
50           non-domain well-known SIDs like Everyone (S-1-1-0) or Creator Owner
51           (S-1-3-0). A chosen list of well-known SIDs will be preallocated on
52           first start to create deterministic mappings for those.
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54           Thus the number of local users and groups that can be created is
55           limited by this option as well. If you plan to create a large
56           amount of local users or groups, you will need set this parameter
57           accordingly.
58
59           The default value is 100000.
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61       read only = [ yes | no ]
62           Turn the module into read-only mode. No new ranges will be
63           allocated nor will new mappings be created in the idmap pool.
64           Defaults to no.
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66       ignore builtin = [ yes | no ]
67           Ignore any mapping requests for the BUILTIN domain. Defaults to no.
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THE MAPPING FORMULAS

70       The Unix ID for a RID is calculated this way:
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72                          ID =  REDUCED RID + IDMAP RANGE LOW VALUE + RANGE NUMBER * RANGE SIZE
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75       where REDUCED RID = RID % RANGE_SIZE and a DOMAIN RANGE INDEX = RID /
76       RANGE_SIZE is used together with the domain sid to determine the RANGE
77       NUMBER (stored in the database).
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79       Correspondingly, the formula for calculating the RID for a given Unix
80       ID is this:
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82                          RID = (ID - LOW ID) % RANGE SIZE + DOMAIN RANGE INDEX * RANGE SIZE
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85       Where the DOMAIN RANGE INDEX is retrieved from the database along with
86       the domain sid by the RANGE NUMBER = (ID - LOW ID) / RANGE SIZE .
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EXAMPLES

89       This example shows you the minimal configuration that will work for the
90       principal domain and 19 trusted domains / range extensions.
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92                [global]
93                security = ads
94                workgroup = CUSTOMER
95                realm = CUSTOMER.COM
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97                idmap config * : backend = autorid
98                idmap config * : range = 1000000-1999999
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102       This example shows how to configure idmap_autorid as default for all
103       domains with a potentially large amount of users plus a specific
104       configuration for a trusted domain that uses the SFU mapping scheme.
105       Please note that idmap ranges and sfu ranges are not allowed to
106       overlap.
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108                [global]
109                security = ads
110                workgroup = CUSTOMER
111                realm = CUSTOMER.COM
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113                idmap config * : backend = autorid
114                idmap config * : range = 1000000-19999999
115                idmap config * : rangesize = 1000000
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117                idmap config TRUSTED : backend  = ad
118                idmap config TRUSTED : range    = 50000 - 99999
119                idmap config TRUSTED : schema_mode = sfu
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AUTHOR

123       The original Samba software and related utilities were created by
124       Andrew Tridgell. Samba is now developed by the Samba Team as an Open
125       Source project similar to the way the Linux kernel is developed.
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129Samba 4.14.5                      06/01/2021                  IDMAP_AUTORID(8)
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