samba-mirror/docs-xml/manpages/idmap_autorid.8.xml

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<!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">4.4</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.
		</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>