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<?xml version="1.0" encoding="iso-8859-1"?>
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<!DOCTYPE chapter PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
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<chapter id="groupmapping">
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<firstname>Jean Fran�ois</firstname><surname>Micouleau</surname>
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<title>Group Mapping: MS Windows and UNIX</title>
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<indexterm significance="preferred"><primary>groups</primary><secondary>mapping</secondary></indexterm>
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<indexterm><primary>SID</primary></indexterm>
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<indexterm><primary>associations</primary></indexterm>
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<indexterm><primary>UNIX groups</primary></indexterm>
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<indexterm><primary>groupmap</primary></indexterm>
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<indexterm><primary>net</primary></indexterm>
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Starting with Samba-3, new group mapping functionality is available to create associations
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between Windows group SIDs and UNIX group GIDs. The <command>groupmap</command> subcommand
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included with the &net; tool can be used to manage these associations.
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<indexterm><primary>group mapping</primary></indexterm>
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<indexterm><primary>domain groups</primary></indexterm>
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The new facility for mapping NT groups to UNIX system groups allows the administrator to decide
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which NT domain groups are to be exposed to MS Windows clients. Only those NT groups that map
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to a UNIX group that has a value other than the default (<constant>-1</constant>) will be exposed
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in group selection lists in tools that access domain users and groups.
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<indexterm><primary>domain admin group</primary></indexterm>
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<indexterm><primary>Windows group</primary></indexterm>
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The <parameter>domain admin group</parameter> parameter has been removed in Samba-3 and should no longer
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be specified in &smb.conf;. In Samba-2.2.x, this parameter was used to give the listed users membership in the
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<constant>Domain Admins</constant> Windows group, which gave local admin rights on their workstations
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(in default configurations).
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<title>Features and Benefits</title>
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Samba allows the administrator to create MS Windows NT4/200x group accounts and to
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arbitrarily associate them with UNIX/Linux group accounts.
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<indexterm><primary>UID</primary></indexterm>
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<indexterm><primary>GID</primary></indexterm>
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<indexterm><primary>idmap uid</primary></indexterm>
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<indexterm><primary>MMC</primary></indexterm>
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<indexterm><primary>winbindd</primary></indexterm>
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<indexterm><primary>ID range</primary></indexterm>
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<indexterm><primary>group accounts</primary></indexterm>
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Group accounts can be managed using the MS Windows NT4 or MS Windows 200x/XP Professional MMC tools.
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Appropriate interface scripts should be provided in &smb.conf; if it is desired that UNIX/Linux system
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accounts should be automatically created when these tools are used. In the absence of these scripts, and
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so long as <command>winbindd</command> is running, Samba group accounts that are created using these
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tools will be allocated UNIX UIDs and GIDs from the ID range specified by the
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<smbconfoption name="idmap uid"/>/<smbconfoption name="idmap gid"/>
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parameters in the &smb.conf; file.
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<figure id="idmap-sid2gid">
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<title>IDMAP: Group SID-to-GID Resolution.</title>
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<imagefile scale="50">idmap-sid2gid</imagefile>
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<figure id="idmap-gid2sid">
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<title>IDMAP: GID Resolution to Matching SID.</title>
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<imagefile scale="50">idmap-gid2sid</imagefile>
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<indexterm><primary>IDMAP</primary></indexterm>
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<indexterm><primary>SID-to-GID</primary></indexterm>
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<indexterm><primary>net</primary><secondary>groupmap</secondary></indexterm>
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<indexterm><primary>group mappings</primary></indexterm>
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In both cases, when winbindd is not running, only locally resolvable groups can be recognized. Please refer to
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<link linkend="idmap-sid2gid">IDMAP: Group SID-to-GID Resolution</link> and <link
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linkend="idmap-gid2sid">IDMAP: GID Resolution to Matching SID</link>. The <command>net groupmap</command> is
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used to establish UNIX group to NT SID mappings as shown in <link linkend="idmap-store-gid2sid">IDMAP: storing
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group mappings</link>.
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<figure id="idmap-store-gid2sid">
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<title>IDMAP Storing Group Mappings.</title>
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<imagefile scale="50">idmap-store-gid2sid</imagefile>
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<indexterm><primary>groupadd</primary></indexterm>
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<indexterm><primary>groupdel</primary></indexterm>
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<indexterm><primary>shadow utilities</primary></indexterm>
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<indexterm><primary>groupmod</primary></indexterm>
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Administrators should be aware that where &smb.conf; group interface scripts make
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direct calls to the UNIX/Linux system tools (the shadow utilities, <command>groupadd</command>,
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<command>groupdel</command>, and <command>groupmod</command>), the resulting UNIX/Linux group names will be subject
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to any limits imposed by these tools. If the tool does not allow uppercase characters
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or space characters, then the creation of an MS Windows NT4/200x-style group of
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<literal>Engineering Managers</literal> will attempt to create an identically named
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UNIX/Linux group, an attempt that will of course fail.
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<indexterm><primary>GID</primary></indexterm>
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<indexterm><primary>SID</primary></indexterm>
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There are several possible workarounds for the operating system tools limitation. One
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method is to use a script that generates a name for the UNIX/Linux system group that
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fits the operating system limits and that then just passes the UNIX/Linux group ID (GID)
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back to the calling Samba interface. This will provide a dynamic workaround solution.
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<indexterm><primary>net</primary><secondary>groupmap</secondary></indexterm>
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Another workaround is to manually create a UNIX/Linux group, then manually create the
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MS Windows NT4/200x group on the Samba server, and then use the <command>net groupmap</command>
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tool to connect the two to each other.
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<title>Discussion</title>
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<indexterm><primary>Windows NT4/200x</primary></indexterm>
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<indexterm><primary>group privileges</primary></indexterm>
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When you install <application>MS Windows NT4/200x</application> on a computer, the installation
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program creates default users and groups, notably the <constant>Administrators</constant> group,
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and gives that group privileges necessary to perform essential system tasks,
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such as the ability to change the date and time or to kill (or close) any process running on the
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<indexterm><primary>Administrator</primary></indexterm>
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The <constant>Administrator</constant> user is a member of the <constant>Administrators</constant> group, and thus inherits
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<constant>Administrators</constant> group privileges. If a <constant>joe</constant> user is created to be a member of the
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<constant>Administrators</constant> group, <constant>joe</constant> has exactly the same rights as the user
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<constant>Administrator</constant>.
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<indexterm><primary>domain member</primary></indexterm>
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<indexterm><primary>Domain Admins</primary></indexterm>
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<indexterm><primary>inherits rights</primary></indexterm>
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<indexterm><primary>PDC</primary></indexterm>
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When an MS Windows NT4/200x/XP machine is made a domain member, the <quote>Domain Admins</quote> group of the
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PDC is added to the local <constant>Administrators</constant> group of the workstation. Every member of the
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<constant>Domain Admins</constant> group inherits the rights of the local <constant>Administrators</constant> group when
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logging on the workstation.
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<indexterm><primary>Domain Admins</primary></indexterm>
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<indexterm><primary>PDC</primary></indexterm>
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The following steps describe how to make Samba PDC users members of the <constant>Domain Admins</constant> group.
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Create a UNIX group (usually in <filename>/etc/group</filename>); let's call it <constant>domadm</constant>.
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<indexterm><primary>/etc/group</primary></indexterm>
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Add to this group the users that must be <quote>Administrators</quote>. For example,
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if you want <constant>joe, john</constant>, and <constant>mary</constant> to be administrators,
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your entry in <filename>/etc/group</filename> will look like this:
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<para><programlisting>
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domadm:x:502:joe,john,mary
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Map this domadm group to the <quote>Domain Admins</quote> group by executing the command:
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&rootprompt;<userinput>net groupmap add ntgroup="Domain Admins" unixgroup=domadm rid=512 type=d</userinput>
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<indexterm><primary>Domain Admins group</primary></indexterm>
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The quotes around <quote>Domain Admins</quote> are necessary due to the space in the group name.
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Also make sure to leave no white space surrounding the equal character (=).
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Now <constant>joe, john</constant>, and <constant>mary</constant> are domain administrators.
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<indexterm><primary>groups</primary><secondary>domain</secondary></indexterm>
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It is possible to map any arbitrary UNIX group to any Windows NT4/200x group as well as
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to make any UNIX group a Windows domain group. For example, if you wanted to include a
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UNIX group (e.g., acct) in an ACL on a local file or printer on a Domain Member machine,
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you would flag that group as a domain group by running the following on the Samba PDC:
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&rootprompt;<userinput>net groupmap add rid=1000 ntgroup="Accounting" unixgroup=acct type=d</userinput>
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The <literal>ntgroup</literal> value must be in quotes if it contains space characters to prevent
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the space from being interpreted as a command delimiter.
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<indexterm><primary>RID</primary></indexterm>
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<indexterm><primary>assigned RID</primary></indexterm>
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Be aware that the RID parameter is an unsigned 32-bit integer that should
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normally start at 1000. However, this RID must not overlap with any RID assigned
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to a user. Verification for this is done differently depending on the passdb backend
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you are using. Future versions of the tools may perform the verification automatically,
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but for now the burden is on you.
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<title>Warning: User Private Group Problems</title>
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<indexterm><primary>group accounts</primary></indexterm>
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<indexterm><primary>Red Hat Linux</primary></indexterm>
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<indexterm><primary>private groups</primary></indexterm>
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Windows does not permit user and group accounts to have the same name.
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This has serious implications for all sites that use private group accounts.
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A private group account is an administrative practice whereby users are each
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given their own group account. Red Hat Linux, as well as several free distributions
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of Linux, by default create private groups.
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<indexterm><primary>UNIX/Linux group</primary></indexterm>
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<indexterm><primary>Windows group</primary></indexterm>
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When mapping a UNIX/Linux group to a Windows group account, all conflict can
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be avoided by assuring that the Windows domain group name does not overlap
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with any user account name.
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<title>Nested Groups: Adding Windows Domain Groups to Windows Local Groups</title>
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<indexterm><primary>groups</primary><secondary>nested</secondary></indexterm>
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<indexterm><primary>nested groups</primary></indexterm>
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This functionality is known as <constant>nested groups</constant> and was first added to
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<indexterm><primary>nested groups</primary></indexterm>
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All MS Windows products since the release of Windows NT 3.10 support the use of nested groups.
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Many Windows network administrators depend on this capability because it greatly simplifies security
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<indexterm><primary>nested group</primary></indexterm>
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<indexterm><primary>group membership</primary></indexterm>
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<indexterm><primary>domain security</primary></indexterm>
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<indexterm><primary>domain member server</primary></indexterm>
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<indexterm><primary>local groups</primary></indexterm>
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<indexterm><primary>domain global groups</primary></indexterm>
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<indexterm><primary>domain global users</primary></indexterm>
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The nested group architecture was designed with the premise that day-to-day user and group membership
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management should be performed on the domain security database. The application of group security
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should be implemented on domain member servers using only local groups. On the domain member server,
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all file system security controls are then limited to use of the local groups, which will contain
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domain global groups and domain global users.
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<indexterm><primary>individual domain user</primary></indexterm>
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<indexterm><primary>domain group settings</primary></indexterm>
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<indexterm><primary>Account Unknown</primary></indexterm>
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You may ask, What are the benefits of this arrangement? The answer is obvious to those who have plumbed
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the dark depths of Windows networking architecture. Consider for a moment a server on which are stored
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200,000 files, each with individual domain user and domain group settings. The company that owns the
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file server is bought by another company, resulting in the server being moved to another location, and then
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it is made a member of a different domain. Who would you think now owns all the files and directories?
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Answer: Account Unknown.
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<indexterm><primary>directory access control</primary></indexterm>
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<indexterm><primary>local groups</primary></indexterm>
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<indexterm><primary>ACL</primary></indexterm>
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<indexterm><primary>Account Unknown</primary></indexterm>
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Unraveling the file ownership mess is an unenviable administrative task that can be avoided simply
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by using local groups to control all file and directory access control. In this case, only the members
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of the local groups will have been lost. The files and directories in the storage subsystem will still
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be owned by the local groups. The same goes for all ACLs on them. It is administratively much simpler
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to delete the <constant>Account Unknown</constant> membership entries inside local groups with appropriate
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entries for domain global groups in the new domain that the server has been made a member of.
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<indexterm><primary>nested groups</primary></indexterm>
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<indexterm><primary>administrative privileges</primary></indexterm>
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<indexterm><primary>domain member workstations</primary></indexterm>
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<indexterm><primary>domain member servers</primary></indexterm>
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<indexterm><primary>member machine</primary></indexterm>
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<indexterm><primary>full rights</primary></indexterm>
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<indexterm><primary>Domain Admins</primary></indexterm>
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<indexterm><primary>local administrative privileges</primary></indexterm>
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Another prominent example of the use of nested groups involves implementation of administrative privileges
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on domain member workstations and servers. Administrative privileges are given to all members of the
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built-in local group <constant>Administrators</constant> on each domain member machine. To ensure that all domain
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administrators have full rights on the member server or workstation, on joining the domain, the
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<constant>Domain Admins</constant> group is added to the local Administrators group. Thus everyone who is
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logged into the domain as a member of the Domain Admins group is also granted local administrative
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privileges on each domain member.
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<indexterm><primary>nested groups</primary></indexterm>
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<indexterm><primary>auxiliary members</primary></indexterm>
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<indexterm><primary>/etc/group</primary></indexterm>
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<indexterm><primary>winbind</primary></indexterm>
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UNIX/Linux has no concept of support for nested groups, and thus Samba has for a long time not supported
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them either. The problem is that you would have to enter UNIX groups as auxiliary members of a group in
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<filename>/etc/group</filename>. This does not work because it was not a design requirement at the time
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the UNIX file system security model was implemented. Since Samba-2.2, the winbind daemon can provide
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<filename>/etc/group</filename> entries on demand by obtaining user and group information from the domain
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controller that the Samba server is a member of.
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<indexterm><primary>/etc/group</primary></indexterm>
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<indexterm><primary>libnss_winbind</primary></indexterm>
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<indexterm><primary>local groups</primary></indexterm>
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<indexterm><primary>Domain Users</primary></indexterm>
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<indexterm><primary>alias group</primary></indexterm>
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In effect, Samba supplements the <filename>/etc/group</filename> data via the dynamic
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<command>libnss_winbind</command> mechanism. Beginning with Samba-3.0.3, this facility is used to provide
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local groups in the same manner as Windows. It works by expanding the local groups on the
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fly as they are accessed. For example, the <constant>Domain Users</constant> group of the domain is made
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a member of the local group <constant>demo</constant>. Whenever Samba needs to resolve membership of the
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<constant>demo</constant> local (alias) group, winbind asks the domain controller for demo members of the Domain Users
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group. By definition, it can only contain user objects, which can then be faked to be member of the
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UNIX/Linux group <constant>demo</constant>.
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<indexterm><primary>nested groups</primary></indexterm>
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<indexterm><primary>winbindd</primary></indexterm>
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<indexterm><primary>NSS</primary></indexterm>
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<indexterm><primary>winbind</primary></indexterm>
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<indexterm><primary>local groups</primary></indexterm>
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<indexterm><primary>Domain User Manager</primary></indexterm>
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<indexterm><primary>net</primary><secondary>rpc</secondary><tertiary>group</tertiary></indexterm>
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To enable the use of nested groups, <command>winbindd</command> must be used with NSS winbind.
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Creation and administration of the local groups is done best via the Windows Domain User Manager or its
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Samba equivalent, the utility <command>net rpc group</command>. Creating the local group
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<constant>demo</constant> is achieved by executing:
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&rootprompt; net rpc group add demo -L -Uroot%not24get
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<indexterm><primary>addmem</primary></indexterm>
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<indexterm><primary>delmem</primary></indexterm>
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Here the -L switch means that you want to create a local group. It may be necessary to add -S and -U
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switches for accessing the correct host with appropriate user or root privileges. Adding and removing
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group members can be done via the <constant>addmem</constant> and <constant>delmem</constant> subcommands of
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<command>net rpc group</command> command. For example, addition of <quote>DOM\Domain Users</quote> to the
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local group <constant>demo</constant> is done by executing:
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net rpc group addmem demo "DOM\Domain Users"
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<indexterm><primary>getent group demo</primary></indexterm>
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<indexterm><primary>trusted domain</primary></indexterm>
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<indexterm><primary>foreign domain</primary></indexterm>
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<indexterm><primary>local access permissions</primary></indexterm>
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Having completed these two steps, the execution of <command>getent group demo</command> will show demo
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members of the global <constant>Domain Users</constant> group as members of the group
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<constant>demo</constant>. This also works with any local or domain user. In case the domain DOM trusts
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another domain, it is also possible to add global users and groups of the trusted domain as members of
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<constant>demo</constant>. The users from the foreign domain who are members of the group that has been
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added to the <constant>demo</constant> group now have the same local access permissions as local domain
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<title>Important Administrative Information</title>
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Administrative rights are necessary in two specific forms:
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<listitem><para>For Samba-3 domain controllers and domain member servers/clients.</para></listitem>
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<listitem><para>To manage domain member Windows workstations.</para></listitem>
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<indexterm><primary>rights and privileges</primary></indexterm>
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<indexterm><primary>domain member client</primary></indexterm>
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<indexterm><primary>group account</primary></indexterm>
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Versions of Samba up to and including 3.0.10 do not provide a means for assigning rights and privileges
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that are necessary for system administration tasks from a Windows domain member client machine, so
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domain administration tasks such as adding, deleting, and changing user and group account information, and
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managing workstation domain membership accounts, can be handled by any account other than root.
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<indexterm><primary>privilege management</primary></indexterm>
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<indexterm><primary>delegated</primary></indexterm>
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<indexterm><primary>Administrator</primary></indexterm>
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Samba-3.0.11 introduced a new privilege management interface (see <link linkend="rights">User Rights and Privileges</link>)
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that permits these tasks to be delegated to non-root (i.e., accounts other than the equivalent of the
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MS Windows Administrator) accounts.
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<indexterm><primary>mapped</primary></indexterm>
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<indexterm><primary>Domain Admins</primary></indexterm>
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Administrative tasks on a Windows domain member workstation can be done by anyone who is a member of the
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<constant>Domain Admins</constant> group. This group can be mapped to any convenient UNIX group.
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<title>Applicable Only to Versions Earlier than 3.0.11</title>
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<indexterm><primary>privilege</primary></indexterm>
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Administrative tasks on UNIX/Linux systems, such as adding users or groups, requires
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<constant>root</constant>-level privilege. The addition of a Windows client to a Samba domain involves the
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addition of a user account for the Windows client.
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<indexterm><primary>system security</primary></indexterm>
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<indexterm><primary>privileges</primary></indexterm>
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Many UNIX administrators continue to request that the Samba Team make it possible to add Windows workstations, or
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the ability to add, delete, or modify user accounts, without requiring <constant>root</constant> privileges.
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Such a request violates every understanding of basic UNIX system security.
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<indexterm><primary>privileges</primary></indexterm>
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<indexterm><primary>/etc/passwd</primary></indexterm>
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<indexterm><primary>Domain Server Manager</primary></indexterm>
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<indexterm><primary>Domain User Manager</primary></indexterm>
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<indexterm><primary>manage share-level ACL</primary></indexterm>
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<indexterm><primary>share-level ACLs</primary></indexterm>
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There is no safe way to provide access on a UNIX/Linux system without providing
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<constant>root</constant>-level privileges. Provision of <constant>root</constant> privileges can be done
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either by logging on to the Domain as the user <constant>root</constant> or by permitting particular users to
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use a UNIX account that has a UID=0 in the <filename>/etc/passwd</filename> database. Users of such accounts
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can use tools like the NT4 Domain User Manager and the NT4 Domain Server Manager to manage user and group
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accounts as well as domain member server and client accounts. This level of privilege is also needed to manage
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<title>Default Users, Groups, and Relative Identifiers</title>
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<indexterm><primary>Relative Identifier</primary><see>RID</see></indexterm>
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<indexterm><primary>RID</primary></indexterm>
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<indexterm><primary>Windows NT4/200x/XP</primary></indexterm>
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<indexterm><primary>well-known RID</primary></indexterm>
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<indexterm><primary>domain groups</primary></indexterm>
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<indexterm><primary>tdbsam</primary></indexterm>
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<indexterm><primary>LDAP</primary></indexterm>
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<indexterm><primary>NT groups</primary></indexterm>
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When first installed, Windows NT4/200x/XP are preconfigured with certain user, group, and
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alias entities. Each has a well-known RID. These must be preserved for continued
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integrity of operation. Samba must be provisioned with certain essential domain groups that require
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the appropriate RID value. When Samba-3 is configured to use <constant>tdbsam</constant>, the essential
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domain groups are automatically created. It is the LDAP administrator's responsibility to create
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(provision) the default NT groups.
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<indexterm><primary>default users</primary></indexterm>
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<indexterm><primary>default groups</primary></indexterm>
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<indexterm><primary>default aliases</primary></indexterm>
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<indexterm><primary>RID</primary></indexterm>
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Each essential domain group must be assigned its respective well-known RID. The default users, groups,
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aliases, and RIDs are shown in <link linkend="WKURIDS">Well-Known User Default RIDs</link>.
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<indexterm><primary>passdb backend</primary></indexterm>
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<indexterm><primary>LDAP</primary></indexterm>
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<indexterm><primary>ldapsam</primary></indexterm>
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<indexterm><primary>domain groups</primary></indexterm>
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<indexterm><primary>RID</primary></indexterm>
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It is the administrator's responsibility to create the essential domain groups and to assign each
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<indexterm><primary>domain groups</primary></indexterm>
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<indexterm><primary>RID</primary></indexterm>
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It is permissible to create any domain group that may be necessary; just make certain that the essential
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domain groups (well known) have been created and assigned their default RIDs. Other groups you create may
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be assigned any arbitrary RID you care to use.
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Be sure to map each domain group to a UNIX system group. That is the only way to ensure that the group
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will be available for use as an NT domain group.
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<table frame="all" id="WKURIDS">
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<title>Well-Known User Default RIDs</title>
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<tgroup cols="4" align="left">
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<colspec align="left"/>
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<colspec align="left"/>
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<colspec align="left"/>
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<colspec align="center"/>
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<entry>Well-Known Entity</entry>
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<entry>Essential</entry>
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<entry>Domain Administrator</entry>
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<entry>Domain Guest</entry>
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<entry>Domain KRBTGT</entry>
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<entry>Domain Admins</entry>
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<entry>Domain Users</entry>
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<entry>Domain Guests</entry>
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<entry>Domain Computers</entry>
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<entry>Domain Controllers</entry>
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<entry>Domain Certificate Admins</entry>
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<entry>Domain Schema Admins</entry>
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<entry>Domain Enterprise Admins</entry>
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<entry>Domain Policy Admins</entry>
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<entry>Builtin Admins</entry>
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<entry>Builtin users</entry>
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<entry>Builtin Guests</entry>
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<entry>Builtin Power Users</entry>
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<entry>Builtin Account Operators</entry>
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<entry>Builtin System Operators</entry>
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<entry>Builtin Print Operators</entry>
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<entry>Builtin Backup Operators</entry>
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<entry>Builtin Replicator</entry>
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<entry>Builtin RAS Servers</entry>
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<title>Example Configuration</title>
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<indexterm><primary>net</primary><secondary>groupmap</secondary><tertiary>list</tertiary></indexterm>
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You can list the various groups in the mapping database by executing
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<command>net groupmap list</command>. Here is an example:
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<indexterm><primary>net</primary><secondary>groupmap</secondary></indexterm>
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&rootprompt; <userinput>net groupmap list</userinput>
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Domain Admins (S-1-5-21-2547222302-1596225915-2414751004-512) -> domadmin
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Domain Users (S-1-5-21-2547222302-1596225915-2414751004-513) -> domuser
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Domain Guests (S-1-5-21-2547222302-1596225915-2414751004-514) -> domguest
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For complete details on <command>net groupmap</command>, refer to the net(8) man page.
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<title>Configuration Scripts</title>
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Everyone needs tools. Some of us like to create our own, others prefer to use canned tools
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(i.e., prepared by someone else for general use).
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<title>Sample &smb.conf; Add Group Script</title>
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<indexterm><primary>smbgrpadd.sh</primary></indexterm>
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<indexterm><primary>groupadd limitations</primary></indexterm>
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<indexterm><primary>smbgrpadd.sh</primary></indexterm>
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<indexterm><primary>/etc/group</primary></indexterm>
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<indexterm><primary>groupadd</primary></indexterm>
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A script to create complying group names for use by the Samba group interfaces
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is provided in <link linkend="smbgrpadd.sh">smbgrpadd.sh</link>. This script
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adds a temporary entry in the <filename>/etc/group</filename> file and then renames
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it to the desired name. This is an example of a method to get around operating
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system maintenance tool limitations such as those present in some version of the
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<command>groupadd</command> tool.
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<example id="smbgrpadd.sh">
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<title>smbgrpadd.sh</title>
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# Add the group using normal system groupadd tool.
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thegid=`cat /etc/group | grep ^smbtmpgrp00 | cut -d ":" -f3`
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# Now change the name to what we want for the MS Windows networking end
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cp /etc/group /etc/group.bak
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cat /etc/group.bak | sed "s/^smbtmpgrp00/$1/g" > /etc/group
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# Now return the GID as would normally happen.
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The &smb.conf; entry for the above script shown in <link linkend="smbgrpadd">the configuration of
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&smb.conf; for the add group Script</link> demonstrates how it may be used.
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<example id="smbgrpadd">
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<title>Configuration of &smb.conf; for the add group Script</title>
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<smbconfsection name="[global]"/>
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<smbconfoption name="add group script">/path_to_tool/smbgrpadd.sh "%g"</smbconfoption>
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<title>Script to Configure Group Mapping</title>
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<indexterm><primary>initGroups.sh</primary></indexterm>
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In our example we have created a UNIX/Linux group called <literal>ntadmin</literal>.
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Our script will create the additional groups <literal>Orks</literal>, <literal>Elves</literal>, and <literal>Gnomes</literal>.
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It is a good idea to save this shell script for later use just in case you ever need to rebuild your mapping database.
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For the sake of convenience we elect to save this script as a file called <filename>initGroups.sh</filename>.
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This script is given in <link linkend="set-group-map">intGroups.sh</link>.
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<indexterm><primary>initGroups.sh</primary></indexterm>
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<example id="set-group-map">
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<title>Script to Set Group Mapping</title>
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net groupmap add ntgroup="Domain Admins" unixgroup=ntadmin rid=512 type=d
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net groupmap add ntgroup="Domain Users" unixgroup=users rid=513 type=d
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net groupmap add ntgroup="Domain Guests" unixgroup=nobody rid=514 type=d
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net groupmap add ntgroup="Orks" unixgroup=Orks type=d
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net groupmap add ntgroup="Elves" unixgroup=Elves type=d
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net groupmap add ntgroup="Gnomes" unixgroup=Gnomes type=d
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Of course it is expected that the administrator will modify this to suit local needs.
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For information regarding the use of the <command>net groupmap</command> tool please
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refer to the man page.
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Versions of Samba-3 prior to 3.0.23 automatically create default group mapping for the
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<literal>Domain Admins, Domain Users</literal> and <literal>Domain Guests</literal> Windows
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groups, but do not map them to UNIX GIDs. This was a cause of administrative confusion and
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trouble. Commencing with Samba-3.0.23 this annomaly has been fixed - thus all Windows groups
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must now be manually and explicitly created and mapped to a valid UNIX GID by the Samba
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<title>Common Errors</title>
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At this time there are many little surprises for the unwary administrator. In a real sense
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it is imperative that every step of automated control scripts be carefully tested
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manually before putting it into active service.
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<title>Adding Groups Fails</title>
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<indexterm><primary>groupadd</primary></indexterm>
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This is a common problem when the <command>groupadd</command> is called directly
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by the Samba interface script for the <smbconfoption name="add group script"/> in
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<indexterm><primary>uppercase character</primary></indexterm>
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<indexterm><primary>space character</primary></indexterm>
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The most common cause of failure is an attempt to add an MS Windows group account
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that has an uppercase character and/or a space character in it.
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<indexterm><primary>groupadd</primary></indexterm>
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There are three possible workarounds. First, use only group names that comply
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with the limitations of the UNIX/Linux <command>groupadd</command> system tool.
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Second, it involves the use of the script mentioned earlier in this chapter, and
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third is the option is to manually create a UNIX/Linux group account that can substitute
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for the MS Windows group name, then use the procedure listed above to map that group
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to the MS Windows group.
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<title>Adding Domain Users to the Workstation Power Users Group</title>
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What must I do to add domain users to the Power Users group?
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<indexterm><primary>Domain Users group</primary></indexterm>
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The Power Users group is a group that is local to each Windows 200x/XP Professional workstation.
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You cannot add the Domain Users group to the Power Users group automatically, it must be done on
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each workstation by logging in as the local workstation <emphasis>administrator</emphasis> and
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then using the following procedure:
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Click <guimenu>Start -> Control Panel -> Users and Passwords</guimenu>.
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Click the <guimenuitem>Advanced</guimenuitem> tab.
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Click the <guibutton>Advanced</guibutton> button.
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Click <constant>Groups</constant>.
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Double-click <constant>Power Users</constant>. This will launch the panel to add users or groups
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to the local machine <constant>Power Users</constant> group.
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Click the <guibutton>Add</guibutton> button.
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Select the domain from which the <constant>Domain Users</constant> group is to be added.
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Double-click the <constant>Domain Users</constant> group.
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Click the <guibutton>OK</guibutton> button. If a logon box is presented during this process,
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please remember to enter the connect as <constant>DOMAIN\UserName</constant>, that is, for the
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domain <constant>MIDEARTH</constant> and the user <constant>root</constant> enter
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<constant>MIDEARTH\root</constant>.
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docs-xml/Samba3-HOWTO/TOSHARG-Group-Mapping.xml
