samba-mirror/docs-xml/Samba3-HOWTO/TOSHARG-Group-Mapping.xml

<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE chapter PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
<chapter id="groupmapping">
<chapterinfo>
	&author.jht;
	<author>
		<firstname>Jean François</firstname><surname>Micouleau</surname>
	</author>
	&author.jerry;
</chapterinfo>
<title>Group Mapping: MS Windows and UNIX</title>


	<para>
<indexterm significance="preferred"><primary>groups</primary><secondary>mapping</secondary></indexterm>
<indexterm><primary>SID</primary></indexterm>
<indexterm><primary>associations</primary></indexterm>
<indexterm><primary>UNIX groups</primary></indexterm>
<indexterm><primary>groupmap</primary></indexterm>
<indexterm><primary>net</primary></indexterm>
	Starting with Samba-3, new group mapping functionality is available to create associations
	between Windows group SIDs and UNIX group GIDs. The <command>groupmap</command> subcommand
	included with the &net; tool can be used to manage these associations.
	</para>

	<para>
<indexterm><primary>group mapping</primary></indexterm>
<indexterm><primary>domain groups</primary></indexterm>
	The new facility for mapping NT groups to UNIX system groups allows the administrator to decide
	which NT domain groups are to be exposed to MS Windows clients. Only those NT groups that map
	to a UNIX group that has a value other than the default (<constant>-1</constant>) will be exposed
	in group selection lists in tools that access domain users and groups.
	</para>

	<warning>
	<para>
	<indexterm><primary>domain admin group</primary></indexterm>
<indexterm><primary>Windows group</primary></indexterm>
	The <parameter>domain admin group</parameter> parameter has been removed in Samba-3 and should no longer
	be specified in &smb.conf;. In Samba-2.2.x, this parameter was used to give the listed users membership in the
	<constant>Domain Admins</constant> Windows group, which gave local admin rights on their workstations
	(in default configurations).
	</para>
	</warning>

<sect1>
<title>Features and Benefits</title>

	<para>
	Samba allows the administrator to create MS Windows NT4/200x group accounts and to
	arbitrarily associate them with UNIX/Linux group accounts.
	</para>

	<para>
	<indexterm><primary>UID</primary></indexterm>
	<indexterm><primary>GID</primary></indexterm>
	<indexterm><primary>idmap uid</primary></indexterm>
<indexterm><primary>MMC</primary></indexterm>
<indexterm><primary>winbindd</primary></indexterm>
<indexterm><primary>ID range</primary></indexterm>
<indexterm><primary>group accounts</primary></indexterm>
	Group accounts can be managed using the MS Windows NT4 or MS Windows 200x/XP Professional MMC tools.
	Appropriate interface scripts should be provided in &smb.conf; if it is desired that UNIX/Linux system
	accounts should be automatically created when these tools are used. In the absence of these scripts, and
	so long as <command>winbindd</command> is running, Samba group accounts that are created using these
	tools will be allocated UNIX UIDs and GIDs from the ID range specified by the
	<smbconfoption name="idmap uid"/>/<smbconfoption name="idmap gid"/>
	parameters in the &smb.conf; file.
	</para>

	<figure id="idmap-sid2gid">
		<title>IDMAP: Group SID-to-GID Resolution.</title>
		<imagefile scale="50">idmap-sid2gid</imagefile>
	</figure>

	<figure id="idmap-gid2sid">
		<title>IDMAP: GID Resolution to Matching SID.</title>
	<imagefile scale="50">idmap-gid2sid</imagefile>
	</figure>

	<para>
	<indexterm><primary>IDMAP</primary></indexterm>
<indexterm><primary>SID-to-GID</primary></indexterm>
<indexterm><primary>net</primary><secondary>groupmap</secondary></indexterm>
<indexterm><primary>group mappings</primary></indexterm>
	In both cases, when winbindd is not running, only locally resolvable groups can be recognized. Please refer to
	<link linkend="idmap-sid2gid">IDMAP: Group SID-to-GID Resolution</link> and <link
	linkend="idmap-gid2sid">IDMAP: GID Resolution to Matching SID</link>.  The <command>net groupmap</command> is
	used to establish UNIX group to NT SID mappings as shown in <link linkend="idmap-store-gid2sid">IDMAP: storing
	group mappings</link>.
	</para>

	<figure id="idmap-store-gid2sid">
		<title>IDMAP Storing Group Mappings.</title>
		<imagefile scale="50">idmap-store-gid2sid</imagefile>
	</figure>

	<para>
	<indexterm><primary>groupadd</primary></indexterm>
	<indexterm><primary>groupdel</primary></indexterm>
<indexterm><primary>shadow utilities</primary></indexterm>
<indexterm><primary>groupmod</primary></indexterm>
	Administrators should be aware that where &smb.conf; group interface scripts make
	direct calls to the UNIX/Linux system tools (the shadow utilities, <command>groupadd</command>,
	<command>groupdel</command>, and <command>groupmod</command>), the resulting UNIX/Linux group names will be subject
	to any limits imposed by these tools. If the tool does not allow uppercase characters
	or space characters, then the creation of an MS Windows NT4/200x-style group of
	<literal>Engineering Managers</literal> will attempt to create an identically named
	UNIX/Linux group, an attempt that will of course fail.
	</para>

	<para>
	<indexterm><primary>GID</primary></indexterm>
	<indexterm><primary>SID</primary></indexterm>
	There are several possible workarounds for the operating system tools limitation. One
	method is to use a script that generates a name for the UNIX/Linux system group that
	fits the operating system limits and that then just passes the UNIX/Linux group ID (GID)
	back to the calling Samba interface. This will provide a dynamic workaround solution.
	</para>

	<para>
<indexterm><primary>net</primary><secondary>groupmap</secondary></indexterm>
	Another workaround is to manually create a UNIX/Linux group, then manually create the
	MS Windows NT4/200x group on the Samba server, and then use the <command>net groupmap</command>
	tool to connect the two to each other.
	</para>

</sect1>

<sect1>
<title>Discussion</title>

	<para>
<indexterm><primary>Windows NT4/200x</primary></indexterm>
<indexterm><primary>group privileges</primary></indexterm>
	When you install <application>MS Windows NT4/200x</application> on a computer, the installation
	program creates default users and groups, notably the <constant>Administrators</constant> group,
	and gives that group privileges necessary to perform essential system tasks,
	such as the ability to change the date and time or to kill (or close) any process running on the
	local machine.
	</para>
	
	<para>
	<indexterm><primary>Administrator</primary></indexterm>
	The <constant>Administrator</constant> user is a member of the <constant>Administrators</constant> group, and thus inherits
	<constant>Administrators</constant> group privileges. If a <constant>joe</constant> user is created to be a member of the
	<constant>Administrators</constant> group, <constant>joe</constant> has exactly the same rights as the user
	<constant>Administrator</constant>.
	</para>

	<para>
<indexterm><primary>domain member</primary></indexterm>
<indexterm><primary>Domain Admins</primary></indexterm>
<indexterm><primary>inherits rights</primary></indexterm>
<indexterm><primary>PDC</primary></indexterm>
	When an MS Windows NT4/200x/XP machine is made a domain member, the <quote>Domain Admins</quote> group of the
	PDC is added to the local <constant>Administrators</constant> group of the workstation. Every member of the
	<constant>Domain Admins</constant> group inherits the rights of the local <constant>Administrators</constant> group when
	logging on the workstation.
	</para>

	<para>
<indexterm><primary>Domain Admins</primary></indexterm>
<indexterm><primary>PDC</primary></indexterm>
	The following steps describe how to make Samba PDC users members of the <constant>Domain Admins</constant> group.
	</para>

	<orderedlist>
		<listitem><para>
		Create a UNIX group (usually in <filename>/etc/group</filename>); let's call it <constant>domadm</constant>.
		</para></listitem>

		<listitem><para>
<indexterm><primary>/etc/group</primary></indexterm>
		Add to this group the users that must be <quote>Administrators</quote>. For example,
		if you want <constant>joe, john</constant>, and <constant>mary</constant> to be administrators,
		your entry in <filename>/etc/group</filename> will look like this:
		</para>

		<para><programlisting>
		domadm:x:502:joe,john,mary
		</programlisting>
		</para></listitem>

		<listitem><para>
		Map this domadm group to the <quote>Domain Admins</quote> group by executing the command:
		</para>

		<para>
<screen>
&rootprompt;<userinput>net groupmap add ntgroup="Domain Admins" unixgroup=domadm rid=512 type=d</userinput>
</screen>
		</para>
		
		<para>
		<indexterm><primary>Domain Admins group</primary></indexterm>
		The quotes around <quote>Domain Admins</quote> are necessary due to the space in the group name.
		Also make sure to leave no white space surrounding the equal character (=).
		</para></listitem>
	</orderedlist>

	<para>
	Now <constant>joe, john</constant>, and <constant>mary</constant> are domain administrators.
	</para>

	<para>
	<indexterm><primary>groups</primary><secondary>domain</secondary></indexterm>
	It is possible to map any arbitrary UNIX group to any Windows NT4/200x group as well as
	to make any UNIX group a Windows domain group. For example, if you wanted to include a
	UNIX group (e.g., acct) in an ACL on a local file or printer on a Domain Member machine,
	you would flag that group as a domain group by running the following on the Samba PDC:
	</para>

	<para>
<screen>
&rootprompt;<userinput>net groupmap add rid=1000 ntgroup="Accounting" unixgroup=acct type=d</userinput>
</screen>
	The <literal>ntgroup</literal> value must be in quotes if it contains space characters to prevent
	the space from being interpreted as a command delimiter.
	</para>

	<para>
<indexterm><primary>RID</primary></indexterm>
<indexterm><primary>assigned RID</primary></indexterm>
	Be aware that the RID parameter is an unsigned 32-bit integer that should
	normally start at 1000. However, this RID must not overlap with any RID assigned
	to a user. Verification for this is done differently depending on the passdb backend
	you are using. Future versions of the tools may perform the verification automatically,
	but for now the burden is on you.
	</para>

	<sect2>
	<title>Warning: User Private Group Problems</title>

	<para>
<indexterm><primary>group accounts</primary></indexterm>
<indexterm><primary>Red Hat Linux</primary></indexterm>
<indexterm><primary>private groups</primary></indexterm>
	Windows does not permit user and group accounts to have the same name.
	This has serious implications for all sites that use private group accounts.
	A private group account is an administrative practice whereby users are each
	given their own group account. Red Hat Linux, as well as several free distributions
	of Linux, by default create private groups.
	</para>

	<para>
<indexterm><primary>UNIX/Linux group</primary></indexterm>
<indexterm><primary>Windows group</primary></indexterm>
	When mapping a UNIX/Linux group to a Windows group account, all conflict can
	be avoided by assuring that the Windows domain group name does not overlap
	with any user account name.
	</para>

	</sect2>

	<sect2>
	<title>Nested Groups: Adding Windows Domain Groups to Windows Local Groups</title>

	<indexterm><primary>groups</primary><secondary>nested</secondary></indexterm>

	<para>
<indexterm><primary>nested groups</primary></indexterm>
	This functionality is known as <constant>nested groups</constant> and was first added to
	Samba-3.0.3.
	</para>

	<para>
<indexterm><primary>nested groups</primary></indexterm>
	All MS Windows products since the release of Windows NT 3.10 support the use of nested groups.
	Many Windows network administrators depend on this capability because it greatly simplifies security
	administration.
	</para>

	<para>
<indexterm><primary>nested group</primary></indexterm>
<indexterm><primary>group membership</primary></indexterm>
<indexterm><primary>domain security</primary></indexterm>
<indexterm><primary>domain member server</primary></indexterm>
<indexterm><primary>local groups</primary></indexterm>
<indexterm><primary>domain global groups</primary></indexterm>
<indexterm><primary>domain global users</primary></indexterm>
	The nested group architecture was designed with the premise that day-to-day user and group membership
	management should be performed on the domain security database. The application of group security
	should be implemented on domain member servers using only local groups. On the domain member server,
	all file system security controls are then limited to use of the local groups, which will contain
	domain global groups and domain global users.
	</para>

	<para>
<indexterm><primary>individual domain user</primary></indexterm>
<indexterm><primary>domain group settings</primary></indexterm>
<indexterm><primary>Account Unknown</primary></indexterm>
	You may ask, What are the benefits of this arrangement? The answer is obvious to those who have plumbed
	the dark depths of Windows networking architecture. Consider for a moment a server on which are stored
	200,000 files, each with individual domain user and domain group settings. The company that owns the
	file server is bought by another company, resulting in the server being moved to another location, and then
	it is made a member of a different domain. Who would you think now owns all the files and directories?
	Answer: Account Unknown.
	</para>

	<para>
<indexterm><primary>directory access control</primary></indexterm>
<indexterm><primary>local groups</primary></indexterm>
<indexterm><primary>ACL</primary></indexterm>
<indexterm><primary>Account Unknown</primary></indexterm>
	Unraveling the file ownership mess is an unenviable administrative task that can be avoided simply
	by using local groups to control all file and directory access control. In this case, only the members
	of the local groups will have been lost. The files and directories in the storage subsystem will still
	be owned by the local groups. The same goes for all ACLs on them. It is administratively much simpler
	to delete the <constant>Account Unknown</constant> membership entries inside local groups with appropriate
	entries for domain global groups in the new domain that the server has been made a member of.
	</para>

	<para>
<indexterm><primary>nested groups</primary></indexterm>
<indexterm><primary>administrative privileges</primary></indexterm>
<indexterm><primary>domain member workstations</primary></indexterm>
<indexterm><primary>domain member servers</primary></indexterm>
<indexterm><primary>member machine</primary></indexterm>
<indexterm><primary>full rights</primary></indexterm>
<indexterm><primary>Domain Admins</primary></indexterm>
<indexterm><primary>local administrative privileges</primary></indexterm>
	Another prominent example of the use of nested groups involves implementation of administrative privileges
	on domain member workstations and servers. Administrative privileges are given to all members of the
	built-in local group <constant>Administrators</constant> on each domain member machine. To ensure that all domain
	administrators have full rights on the member server or workstation, on joining the domain, the
	<constant>Domain Admins</constant> group is added to the local Administrators group. Thus everyone who is
	logged into the domain as a member of the Domain Admins group is also granted local administrative
	privileges on each domain member.
	</para>

	<para>
<indexterm><primary>nested groups</primary></indexterm>
<indexterm><primary>auxiliary members</primary></indexterm>
<indexterm><primary>/etc/group</primary></indexterm>
<indexterm><primary>winbind</primary></indexterm>
	UNIX/Linux has no concept of support for nested groups, and thus Samba has for a long time not supported
	them either. The problem is that you would have to enter UNIX groups as auxiliary members of a group in
	<filename>/etc/group</filename>. This does not work because it was not a design requirement at the time
	the UNIX file system security model was implemented. Since Samba-2.2, the winbind daemon can provide
	<filename>/etc/group</filename> entries on demand by obtaining user and group information from the domain
	controller that the Samba server is a member of.
	</para>

	<para>
<indexterm><primary>/etc/group</primary></indexterm>
<indexterm><primary>libnss_winbind</primary></indexterm>
<indexterm><primary>local groups</primary></indexterm>
<indexterm><primary>Domain Users</primary></indexterm>
<indexterm><primary>alias group</primary></indexterm>
	In effect, Samba supplements the <filename>/etc/group</filename> data via the dynamic
	<command>libnss_winbind</command> mechanism. Beginning with Samba-3.0.3, this facility is used to provide
	local groups in the same manner as Windows. It works by expanding the local groups on the
	fly as they are accessed. For example, the <constant>Domain Users</constant> group of the domain is made
	a member of the local group <constant>demo</constant>. Whenever Samba needs to resolve membership of the
	<constant>demo</constant> local (alias) group, winbind asks the domain controller for demo members of the Domain Users
	group. By definition, it can only contain user objects, which can then be faked to be member of the
	UNIX/Linux group <constant>demo</constant>.
	</para>

	<para>
<indexterm><primary>nested groups</primary></indexterm>
<indexterm><primary>winbindd</primary></indexterm>
<indexterm><primary>NSS</primary></indexterm>
<indexterm><primary>winbind</primary></indexterm>
<indexterm><primary>local groups</primary></indexterm>
<indexterm><primary>Domain User Manager</primary></indexterm>
<indexterm><primary>net</primary><secondary>rpc</secondary><tertiary>group</tertiary></indexterm>
	To enable the use of nested groups, <command>winbindd</command> must be used with NSS winbind.
	Creation and administration of the local groups is done best via the Windows Domain User Manager or its
	Samba equivalent, the utility <command>net rpc group</command>. Creating the local group
	<constant>demo</constant> is achieved by executing:
	<screen>
	&rootprompt; net rpc group add demo -L -Uroot%not24get
	</screen>
<indexterm><primary>addmem</primary></indexterm>
<indexterm><primary>delmem</primary></indexterm>
	Here the -L switch means that you want to create a local group. It may be necessary to add -S and -U
	switches for accessing the correct host with appropriate user or root privileges. Adding and removing
	group members can be done via the <constant>addmem</constant> and <constant>delmem</constant> subcommands of
	<command>net rpc group</command> command. For example, addition of <quote>DOM\Domain Users</quote> to the
	local group <constant>demo</constant> is done by executing:
	<screen>
	net rpc group addmem demo "DOM\Domain Users"
	</screen>
<indexterm><primary>getent group demo</primary></indexterm>
<indexterm><primary>trusted domain</primary></indexterm>
<indexterm><primary>foreign domain</primary></indexterm>
<indexterm><primary>local access permissions</primary></indexterm>
	Having completed these two steps, the execution of <command>getent group demo</command> will show demo
	members of the global <constant>Domain Users</constant> group as members of  the group
	<constant>demo</constant>.  This also works with any local or domain user. In case the domain DOM trusts
	another domain, it is also possible to add global users and groups of the trusted domain as members of
	<constant>demo</constant>. The users from the foreign domain who are members of the group that has been
	added to the <constant>demo</constant> group now have the same local access permissions as local domain
	users have. 
	</para>

	</sect2>

	<sect2>
	<title>Important Administrative Information</title>

	<para>
	Administrative rights are necessary in two specific forms:
	</para>

	<orderedlist>
		<listitem><para>For Samba-3 domain controllers and domain member servers/clients.</para></listitem>
		<listitem><para>To manage domain member Windows workstations.</para></listitem>
	</orderedlist>

	<para>
<indexterm><primary>rights and privileges</primary></indexterm>
<indexterm><primary>domain member client</primary></indexterm>
<indexterm><primary>group account</primary></indexterm>
	Versions of Samba up to and including 3.0.10 do not provide a means for assigning rights and privileges
	that are necessary for system administration tasks from a Windows domain member client machine, so
	domain administration tasks such as adding, deleting, and changing user and group account information, and
	managing workstation domain membership accounts, can be handled by any account other than root.
	</para>

	<para>
<indexterm><primary>privilege management</primary></indexterm>
<indexterm><primary>delegated</primary></indexterm>
<indexterm><primary>Administrator</primary></indexterm>
	Samba-3.0.11 introduced a new privilege management interface (see <link linkend="rights">User Rights and Privileges</link>)
	that permits these tasks to be delegated to non-root (i.e., accounts other than the equivalent of the
	MS Windows Administrator) accounts.
	</para>

	<para>
<indexterm><primary>mapped</primary></indexterm>
<indexterm><primary>Domain Admins</primary></indexterm>
	Administrative tasks on a Windows domain member workstation can be done by anyone who is a member of the
	<constant>Domain Admins</constant> group. This group can be mapped to any convenient UNIX group.
	</para>

	<sect3>
	<title>Applicable Only to Versions Earlier than 3.0.11</title>

	<para>
<indexterm><primary>privilege</primary></indexterm>
	Administrative tasks on UNIX/Linux systems, such as adding users or groups, requires
	<constant>root</constant>-level privilege. The addition of a Windows client to a Samba domain involves the
	addition of a user account for the Windows client.
	</para>

	<para>
<indexterm><primary>system security</primary></indexterm>
<indexterm><primary>privileges</primary></indexterm>
	Many UNIX administrators continue to request that the Samba Team make it possible to add Windows workstations, or 
	the ability to add, delete, or modify user accounts, without requiring <constant>root</constant> privileges. 
	Such a request violates every understanding of basic UNIX system security.
	</para>

	<para>
<indexterm><primary>privileges</primary></indexterm>
<indexterm><primary>/etc/passwd</primary></indexterm>
<indexterm><primary>Domain Server Manager</primary></indexterm>
<indexterm><primary>Domain User Manager</primary></indexterm>
<indexterm><primary>manage share-level ACL</primary></indexterm>
<indexterm><primary>share-level ACLs</primary></indexterm>
	There is no safe way to provide access on a UNIX/Linux system without providing
	<constant>root</constant>-level privileges. Provision of <constant>root</constant> privileges can be done
	either by logging on to the Domain as the user <constant>root</constant> or by permitting particular users to
	use a UNIX account that has a UID=0 in the <filename>/etc/passwd</filename> database. Users of such accounts
	can use tools like the NT4 Domain User Manager and the NT4 Domain Server Manager to manage user and group
	accounts as well as domain member server and client accounts. This level of privilege is also needed to manage
	share-level ACLs.
	</para>

	</sect3>

	</sect2>

	<sect2>
	<title>Default Users, Groups, and Relative Identifiers</title>

	<para>
	<indexterm><primary>Relative Identifier</primary><see>RID</see></indexterm>
	<indexterm><primary>RID</primary></indexterm>
<indexterm><primary>Windows NT4/200x/XP</primary></indexterm>
<indexterm><primary>well-known RID</primary></indexterm>
<indexterm><primary>domain groups</primary></indexterm>
<indexterm><primary>tdbsam</primary></indexterm>
<indexterm><primary>LDAP</primary></indexterm>
<indexterm><primary>NT groups</primary></indexterm>
	When first installed, Windows NT4/200x/XP are preconfigured with certain user, group, and
	alias entities. Each has a well-known RID. These must be preserved for continued
	integrity of operation. Samba must be provisioned with certain essential domain groups that require
	the appropriate RID value. When Samba-3 is configured to use <constant>tdbsam</constant>, the essential
	domain groups are automatically created. It is the LDAP administrator's responsibility to create
	(provision) the default NT groups.
	</para>

	<para>
<indexterm><primary>default users</primary></indexterm>
<indexterm><primary>default groups</primary></indexterm>
<indexterm><primary>default aliases</primary></indexterm>
<indexterm><primary>RID</primary></indexterm>
	Each essential domain group must be assigned its respective well-known RID. The default users, groups,
	aliases, and RIDs are shown in <link linkend="WKURIDS">Well-Known User Default RIDs</link>.
	</para>

	<note><para>
<indexterm><primary>passdb backend</primary></indexterm>
<indexterm><primary>LDAP</primary></indexterm>
<indexterm><primary>ldapsam</primary></indexterm>
<indexterm><primary>domain groups</primary></indexterm>
<indexterm><primary>RID</primary></indexterm>
	It is the administrator's responsibility to create the essential domain groups and to assign each
	its default RID.
	</para></note>

	<para>
<indexterm><primary>domain groups</primary></indexterm>
<indexterm><primary>RID</primary></indexterm>
	It is permissible to create any domain group that may be necessary; just make certain that the essential
	domain groups (well known) have been created and assigned their default RIDs. Other groups you create may
	be assigned any arbitrary RID you care to use.
	</para>

	<para>
	Be sure to map each domain group to a UNIX system group. That is the only way to ensure that the group
	will be available for use as an NT domain group.
	</para>

	<para>
	<table frame="all" id="WKURIDS">
	<title>Well-Known User Default RIDs</title>
		<tgroup cols="4" align="left">
			<colspec align="left"/>
			<colspec align="left"/>
			<colspec align="left"/>
			<colspec align="center"/>
			<thead>
				<row>
					<entry>Well-Known Entity</entry>
					<entry>RID</entry>
					<entry>Type</entry>
					<entry>Essential</entry>
				</row>
			</thead>
			<tbody>
				<row>
					<entry>Domain Administrator</entry>
					<entry>500</entry>
					<entry>User</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Domain Guest</entry>
					<entry>501</entry>
					<entry>User</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Domain KRBTGT</entry>
					<entry>502</entry>
					<entry>User</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Domain Admins</entry>
					<entry>512</entry>
					<entry>Group</entry>
					<entry>Yes</entry>
				</row>
				<row>
					<entry>Domain Users</entry>
					<entry>513</entry>
					<entry>Group</entry>
					<entry>Yes</entry>
				</row>
				<row>
					<entry>Domain Guests</entry>
					<entry>514</entry>
					<entry>Group</entry>
					<entry>Yes</entry>
				</row>
				<row>
					<entry>Domain Computers</entry>
					<entry>515</entry>
					<entry>Group</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Domain Controllers</entry>
					<entry>516</entry>
					<entry>Group</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Domain Certificate Admins</entry>
					<entry>517</entry>
					<entry>Group</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Domain Schema Admins</entry>
					<entry>518</entry>
					<entry>Group</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Domain Enterprise Admins</entry>
					<entry>519</entry>
					<entry>Group</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Domain Policy Admins</entry>
					<entry>520</entry>
					<entry>Group</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Builtin Admins</entry>
					<entry>544</entry>
					<entry>Alias</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Builtin users</entry>
					<entry>545</entry>
					<entry>Alias</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Builtin Guests</entry>
					<entry>546</entry>
					<entry>Alias</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Builtin Power Users</entry>
					<entry>547</entry>
					<entry>Alias</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Builtin Account Operators</entry>
					<entry>548</entry>
					<entry>Alias</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Builtin System Operators</entry>
					<entry>549</entry>
					<entry>Alias</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Builtin Print Operators</entry>
					<entry>550</entry>
					<entry>Alias</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Builtin Backup Operators</entry>
					<entry>551</entry>
					<entry>Alias</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Builtin Replicator</entry>
					<entry>552</entry>
					<entry>Alias</entry>
					<entry>No</entry>
				</row>
				<row>
					<entry>Builtin RAS Servers</entry>
					<entry>553</entry>
					<entry>Alias</entry>
					<entry>No</entry>
				</row>
			</tbody>
		</tgroup>
	</table>
	</para>

	</sect2>

	<sect2>
	<title>Example Configuration</title>

		<para>
<indexterm><primary>net</primary><secondary>groupmap</secondary><tertiary>list</tertiary></indexterm>
		You can list the various groups in the mapping database by executing
		<command>net groupmap list</command>. Here is an example:
		</para>

		<para>
<indexterm><primary>net</primary><secondary>groupmap</secondary></indexterm>
<screen>
&rootprompt; <userinput>net groupmap list</userinput>
Domain Admins (S-1-5-21-2547222302-1596225915-2414751004-512) -> domadmin
Domain Users (S-1-5-21-2547222302-1596225915-2414751004-513) -> domuser
Domain Guests (S-1-5-21-2547222302-1596225915-2414751004-514) -> domguest
</screen>
		</para>

		<para>
		For complete details on <command>net groupmap</command>, refer to the net(8) man page.
		</para>

	</sect2>

</sect1>

<sect1>
<title>Configuration Scripts</title>

	<para>
	Everyone needs tools. Some of us like to create our own, others prefer to use canned tools
	(i.e., prepared by someone else for general use). 
	</para>

	<sect2>
	<title>Sample &smb.conf; Add Group Script</title>

		<para>
		<indexterm><primary>smbgrpadd.sh</primary></indexterm>
		<indexterm><primary>groupadd limitations</primary></indexterm>
		<indexterm><primary>smbgrpadd.sh</primary></indexterm>
<indexterm><primary>/etc/group</primary></indexterm>
<indexterm><primary>groupadd</primary></indexterm>
		A script to create complying group names for use by the Samba group interfaces
		is provided in <link linkend="smbgrpadd.sh">smbgrpadd.sh</link>. This script
		adds a temporary entry in the <filename>/etc/group</filename> file and then renames
		it to the desired name. This is an example of a method to get around operating
		system maintenance tool limitations such as those present in some version of the
		<command>groupadd</command> tool.
<example id="smbgrpadd.sh">
<title>smbgrpadd.sh</title>
<programlisting>
#!/bin/bash

# Add the group using normal system groupadd tool.
groupadd smbtmpgrp00

thegid=`cat /etc/group | grep ^smbtmpgrp00 | cut -d ":" -f3`

# Now change the name to what we want for the MS Windows networking end
cp /etc/group /etc/group.bak
cat /etc/group.bak | sed "s/^smbtmpgrp00/$1/g" > /etc/group
rm /etc/group.bak

# Now return the GID as would normally happen.
echo $thegid
exit 0
</programlisting>
</example>
</para>

		<para>
		The &smb.conf; entry for the above script shown in <link linkend="smbgrpadd">the configuration of
		&smb.conf; for the add group Script</link> demonstrates how it may be used.

<example id="smbgrpadd">
<title>Configuration of &smb.conf; for the add group Script</title>
<smbconfblock>
<smbconfsection name="[global]"/>
<smbconfoption name="add group script">/path_to_tool/smbgrpadd.sh &quot;%g&quot;</smbconfoption>
</smbconfblock>
</example>
		</para>

	</sect2>
	
	<sect2>
	<title>Script to Configure Group Mapping</title>

	<para>
<indexterm><primary>initGroups.sh</primary></indexterm>
	In our example we have created a UNIX/Linux group called <literal>ntadmin</literal>.
	Our script will create the additional groups <literal>Orks</literal>, <literal>Elves</literal>, and <literal>Gnomes</literal>.
	It is a good idea to save this shell script for later use just in case you ever need to rebuild your mapping database.
	For the sake of convenience we elect to save this script as a file called <filename>initGroups.sh</filename>.
	This script is given in <link linkend="set-group-map">intGroups.sh</link>.
<indexterm><primary>initGroups.sh</primary></indexterm>
<example id="set-group-map">
<title>Script to Set Group Mapping</title>
<programlisting>
#!/bin/bash

net groupmap add ntgroup="Domain Admins" unixgroup=ntadmin rid=512 type=d
net groupmap add ntgroup="Domain Users" unixgroup=users rid=513 type=d
net groupmap add ntgroup="Domain Guests" unixgroup=nobody rid=514 type=d

groupadd Orks
groupadd Elves
groupadd Gnomes

net groupmap add ntgroup="Orks"   unixgroup=Orks   type=d
net groupmap add ntgroup="Elves"  unixgroup=Elves  type=d
net groupmap add ntgroup="Gnomes" unixgroup=Gnomes type=d
</programlisting>
</example>
	</para>

	<para>
	Of course it is expected that the administrator will modify this to suit local needs.
	For information regarding the use of the <command>net groupmap</command> tool please
	refer to the man page.
	</para>

	<note><para>
	Versions of Samba-3 prior to 3.0.23 automatically create default group mapping for the
	<literal>Domain Admins, Domain Users</literal> and <literal>Domain Guests</literal> Windows
	groups, but do not map them to UNIX GIDs. This was a cause of administrative confusion and 
	trouble. Commencing with Samba-3.0.23 this anomaly has been fixed - thus all Windows groups
	must now be manually and explicitly created and mapped to a valid UNIX GID by the Samba 
	administrator.
	</para></note>

	</sect2>

</sect1>

<sect1>
<title>Common Errors</title>

<para>
At this time there are many little surprises for the unwary administrator. In a real sense
it is imperative that every step of automated control scripts be carefully tested
manually before putting it into active service.
</para>

	<sect2>
	<title>Adding Groups Fails</title>

		<para>
<indexterm><primary>groupadd</primary></indexterm>
		This is a common problem when the <command>groupadd</command> is called directly
		by the Samba interface script for the <smbconfoption name="add group script"/> in
		the &smb.conf; file.
		</para>

		<para>
<indexterm><primary>uppercase character</primary></indexterm>
<indexterm><primary>space character</primary></indexterm>
		The most common cause of failure is an attempt to add an MS Windows group account
		that has an uppercase character and/or a space character in it.
		</para>

		<para>
<indexterm><primary>groupadd</primary></indexterm>
		There are three possible workarounds. First, use only group names that comply
		with the limitations of the UNIX/Linux <command>groupadd</command> system tool.
		Second, it involves the use of the script mentioned earlier in this chapter, and
		third is the option is to manually create a UNIX/Linux group account that can substitute
		for the MS Windows group name, then use the procedure listed above to map that group
		to the MS Windows group.
		</para>

	</sect2>

	<sect2>
	<title>Adding Domain Users to the Workstation Power Users Group</title>

		<para><quote>
		What must I do to add domain users to the Power Users group?
		</quote></para>

		<para>
<indexterm><primary>Domain Users group</primary></indexterm>
		The Power Users group is a group that is local to each Windows 200x/XP Professional workstation.
		You cannot add the Domain Users group to the Power Users group automatically, it must be done on
		each workstation by logging in as the local workstation <emphasis>administrator</emphasis> and
		then using the following procedure:
		</para>

		<procedure>
			<step><para>
			Click <guimenu>Start -> Control Panel -> Users and Passwords</guimenu>.
			</para></step>

			<step><para>
			Click the <guimenuitem>Advanced</guimenuitem> tab.
			</para></step>

			<step><para>
			Click the <guibutton>Advanced</guibutton> button.
			</para></step>

			<step><para>
			Click <constant>Groups</constant>.
			</para></step>

			<step><para>
			Double-click <constant>Power Users</constant>. This will launch the panel to add users or groups
			to the local machine <constant>Power Users</constant> group.
			</para></step>

			<step><para>
			Click the <guibutton>Add</guibutton> button.
			</para></step>

			<step><para>
			Select the domain from which the <constant>Domain Users</constant> group is to be added.
			</para></step>

			<step><para>
			Double-click the <constant>Domain Users</constant> group.
			</para></step>

			<step><para>
			Click the <guibutton>OK</guibutton> button. If a logon box is presented during this process, 
			please remember to enter the connect as <constant>DOMAIN\UserName</constant>, that is, for the
			domain <constant>MIDEARTH</constant> and the user <constant>root</constant> enter
			<constant>MIDEARTH\root</constant>.
			</para></step>
		</procedure>
	</sect2>

</sect1>

</chapter>