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<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE refentry PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
<refentry id="idmap_autorid.8">
<refmeta>
<refentrytitle>idmap_autorid</refentrytitle>
<manvolnum>8</manvolnum>
<refmiscinfo class="source">Samba</refmiscinfo>
<refmiscinfo class="manual">System Administration tools</refmiscinfo>
<refmiscinfo class="version">&doc.version;</refmiscinfo>
</refmeta>
<refnamediv>
<refname>idmap_autorid</refname>
<refpurpose>Samba's idmap_autorid Backend for Winbind</refpurpose>
</refnamediv>
<refsynopsisdiv>
<title>DESCRIPTION</title>
<para>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.</para>
<para>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.</para>
<para>The mappings of which domain is mapped to which range is stored
in autorid.tdb, thus you should backup this database regularly.</para>
<para>Due to the algorithm being used, it is the module that is
most easy to use as it only requires a minimal configuration.</para>
</refsynopsisdiv>
<refsect1>
<title>IDMAP OPTIONS</title>
<variablelist>
<varlistentry>
<term>range = low - high</term>
<listitem><para>
Defines the available matching uid and gid
range for which the backend is
authoritative. Note that the range acts as a
filter. If algorithmically determined UID or
GID fall outside the range, they are ignored
and the corresponding map is discarded. It is
intended as a way to avoid accidental UID/GID
overlaps between local and remotely defined
IDs. Note that the range should be a multiple
of the rangesize and needs to be at least twice
as large in order to have sufficient id range
space for the mandatory BUILTIN domain.
With a default rangesize of 100000 the range
needs to span at least 200000.
This would be: range = 100000 - 299999.
</para></listitem>
</varlistentry>
<varlistentry>
<term>rangesize = numberofidsperdomain</term>
<listitem><para>
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.
</para>
<para>
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.
</para>
<para>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.</para>
<para>
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.
</para>
<para>The default value is 100000.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>read only = [ yes | no ]</term>
<listitem><para>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.</para>
</listitem>
</varlistentry>
<varlistentry>
<term>ignore builtin = [ yes | no ]</term>
<listitem><para>Ignore any mapping requests for the BUILTIN domain.
Defaults to no.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>THE MAPPING FORMULAS</title>
<para>
The Unix ID for a RID is calculated this way:
<programlisting>
ID = REDUCED RID + IDMAP RANGE LOW VALUE + RANGE NUMBER * RANGE SIZE
</programlisting>
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).
</para>
<para>
Correspondingly, the formula for calculating the RID for a
given Unix ID is this:
<programlisting>
RID = (ID - LOW ID) % RANGE SIZE + DOMAIN RANGE INDEX * RANGE SIZE
</programlisting>
Where the DOMAIN RANGE INDEX is retrieved from the database along with the
domain sid by the RANGE NUMBER = (ID - LOW ID) / RANGE SIZE .
</para>
</refsect1>
<refsect1>
<title>EXAMPLES</title>
<para>
This example shows you the minimal configuration that will
work for the principal domain and 19 trusted domains / range
extensions.
</para>
<programlisting>
[global]
security = ads
workgroup = CUSTOMER
realm = CUSTOMER.COM
idmap config * : backend = autorid
idmap config * : range = 1000000-1999999
</programlisting>
<para>
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.
</para>
<programlisting>
[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
</programlisting>
</refsect1>
<refsect1>
<title>AUTHOR</title>
<para>
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.
</para>
</refsect1>
</refentry>
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