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diff --git a/src/man/include/ldap_id_mapping.xml b/src/man/include/ldap_id_mapping.xml new file mode 100644 index 00000000..62e5598e --- /dev/null +++ b/src/man/include/ldap_id_mapping.xml @@ -0,0 +1,192 @@ +<refsect1 id='idmap'> + <title>ID MAPPING</title> + <para> + The ID-mapping feature allows SSSD to act as a client of Active + Directory without requiring administrators to extend user attributes + to support POSIX attributes for user and group identifiers. + </para> + <para> + NOTE: When ID-mapping is enabled, the uidNumber and gidNumber + attributes are ignored. This is to avoid the possibility of conflicts + between automatically-assigned and manually-assigned values. If you + need to use manually-assigned values, ALL values must be + manually-assigned. + </para> + + <refsect2 id='idmap_algorithm'> + <title>Mapping Algorithm</title> + <para> + Active Directory provides an objectSID for every user and group + object in the directory. This objectSID can be broken up into + components that represent the Active Directory domain identity and + the relative identifier (RID) of the user or group object. + </para> + <para> + The SSSD ID-mapping algorithm takes a range of available UIDs and + divides it into equally-sized component sections - called + "slices"-. Each slice represents the space available to an Active + Directory domain. + </para> + <para> + When a user or group entry for a particular domain is encountered + for the first time, the SSSD allocates one of the available slices + for that domain. In order to make this slice-assignment repeatable + on different client machines, we select the slice based on the + following algorithm: + </para> + <para> + The SID string is passed through the murmurhash3 algorithm to + convert it to a 32-bit hashed value. We then take the modulus of + this value with the total number of available slices to pick the + slice. + </para> + <para> + NOTE: It is possible to encounter collisions in the hash and + subsequent modulus. In these situations, we will select the next + available slice, but it may not be possible to reproduce the same + exact set of slices on other machines (since the order that they + are encountered will determine their slice). In this situation, it + is recommended to either switch to using explicit POSIX attributes + in Active Directory (disabling ID-mapping) or configure a default + domain to guarantee that at least one is always consistent. See + <quote>Configuration</quote> for details. + </para> + </refsect2> + + <refsect2 id='idmap_config'> + <title>Configuration</title> + <para> + Minimum configuration (in the <quote>[domain/DOMAINNAME]</quote> + section): + </para> + <para> +<programlisting> +ldap_id_mapping = True +ldap_schema = ad +</programlisting> + </para> + <para> + The default configuration results in configuring 10,000 slices, + each capable of holding up to 200,000 IDs, starting from 10,001 + and going up to 2,000,100,000. This should be sufficient for + most deployments. + </para> + <refsect3 id='idmap_advanced_config'> + <title>Advanced Configuration</title> + <variablelist> + <varlistentry> + <term>ldap_idmap_range_min (integer)</term> + <listitem> + <para> + Specifies the lower bound of the range of POSIX IDs to + use for mapping Active Directory user and group SIDs. + </para> + <para> + NOTE: This option is different from + <quote>id_mn</quote> in that <quote>id_min</quote> + acts to filter the output of requests to this domain, + whereas this option controls the range of ID + assignment. This is a subtle distinction, but the + good general advice would be to have + <quote>id_min</quote> be less-than or equal to + <quote>ldap_idmap_range_min</quote> + </para> + <para> + Default: 10001 + </para> + </listitem> + </varlistentry> + <varlistentry> + <term>ldap_idmap_range_max (integer)</term> + <listitem> + <para> + Specifies the upper bound of the range of POSIX IDs to + use for mapping Active Directory user and group SIDs. + </para> + <para> + NOTE: This option is different from + <quote>id_max</quote> in that <quote>id_max</quote> + acts to filter the output of requests to this domain, + whereas this option controls the range of ID + assignment. This is a subtle distinction, but the + good general advice would be to have + <quote>id_max</quote> be greater-than or equal to + <quote>ldap_idmap_range_max</quote> + </para> + <para> + Default: 2000100000 + </para> + </listitem> + </varlistentry> + <varlistentry> + <term>ldap_idmap_range_size (integer)</term> + <listitem> + <para> + Specifies the number of IDs available for each slice. + If the range size does not divide evenly into the min + and max values, it will create as many complete slices + as it can. + </para> + <para> + Default: 200000 + </para> + </listitem> + </varlistentry> + <varlistentry> + <term>ldap_idmap_default_domain_sid (string)</term> + <listitem> + <para> + Specify the domain SID of the default domain. This + will guarantee that this domain will always be + assigned to slice zero in the ID map, bypassing + the murmurhash algorithm described above. + </para> + <para> + Default: not set + </para> + </listitem> + </varlistentry> + <varlistentry> + <term>ldap_idmap_default_domain (string)</term> + <listitem> + <para> + Specify the name of the default domain. + </para> + <para> + Default: not set + </para> + </listitem> + </varlistentry> + <varlistentry> + <term>ldap_idmap_autorid_compat (boolean)</term> + <listitem> + <para> + Changes the behavior of the ID-mapping algorithm + to behave more similarly to winbind's + <quote>idmap_autorid</quote> algorithm. + </para> + <para> + When this option is configured, domains will be + allocated starting with slice zero and increasing + monatomically with each additional domain. + </para> + <para> + NOTE: This algorithm is non-deterministic (it + depends on the order that users and groups are + requested). If this mode is required for + compatibility with machines running winbind, it + is recommended to also use the + <quote>ldap_idmap_default_domain_sid</quote> + option to guarantee that at least one domain is + consistently allocated to slice zero. + </para> + <para> + Default: False + </para> + </listitem> + </varlistentry> + </variablelist> + </refsect3> + </refsect2> + +</refsect1> |