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

   1 <?xml version="1.0" encoding="iso-8859-1"?>
   2 <!DOCTYPE chapter PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
   3 <chapter id="groupmapping">
   4 <chapterinfo>
   5         &author.jht;
   6         <author>
   7                 <firstname>Jean François</firstname><surname>Micouleau</surname>
   8         </author>
   9         &author.jerry;
  10 </chapterinfo>
  11 <title>Group Mapping: MS Windows and UNIX</title>
  12
  13
  14         <para>
  15 <indexterm significance="preferred"><primary>groups</primary><secondary>mapping</secondary></indexterm>
  16 <indexterm><primary>SID</primary></indexterm>
  17 <indexterm><primary>associations</primary></indexterm>
  18 <indexterm><primary>UNIX groups</primary></indexterm>
  19 <indexterm><primary>groupmap</primary></indexterm>
  20 <indexterm><primary>net</primary></indexterm>
  21         Starting with Samba-3, new group mapping functionality is available to create associations
  22         between Windows group SIDs and UNIX groups. The <command>groupmap</command> subcommand
  23         included with the &net; tool can be used to manage these associations.
  24         </para>
  25
  26         <para>
  27 <indexterm><primary>group mapping</primary></indexterm>
  28 <indexterm><primary>domain groups</primary></indexterm>
  29         The new facility for mapping NT groups to UNIX system groups allows the administrator to decide
  30         which NT domain groups are to be exposed to MS Windows clients. Only those NT groups that map
  31         to a UNIX group that has a value other than the default (<constant>-1</constant>) will be exposed
  32         in group selection lists in tools that access domain users and groups.
  33         </para>
  34
  35         <warning>
  36         <para>
  37         <indexterm><primary>domain admin group</primary></indexterm>
  38 <indexterm><primary>Windows group</primary></indexterm>
  39         The <parameter>domain admin group</parameter> parameter has been removed in Samba-3 and should no longer
  40         be specified in &smb.conf;. In Samba-2.2.x, this parameter was used to give the listed users membership in the
  41         <constant>Domain Admins</constant> Windows group, which gave local admin rights on their workstations
  42         (in default configurations).
  43         </para>
  44         </warning>
  45
  46 <sect1>
  47 <title>Features and Benefits</title>
  48
  49         <para>
  50         Samba allows the administrator to create MS Windows NT4/200x group accounts and to
  51         arbitrarily associate them with UNIX/Linux group accounts.
  52         </para>
  53
  54         <para>
  55         <indexterm><primary>UID</primary></indexterm>
  56         <indexterm><primary>GID</primary></indexterm>
  57         <indexterm><primary>idmap uid</primary></indexterm>
  58 <indexterm><primary>MMC</primary></indexterm>
  59 <indexterm><primary>winbindd</primary></indexterm>
  60 <indexterm><primary>ID range</primary></indexterm>
  61 <indexterm><primary>group accounts</primary></indexterm>
  62         Group accounts can be managed using the MS Windows NT4 or MS Windows 200x/XP Professional MMC tools.
  63         Appropriate interface scripts should be provided in &smb.conf; if it is desired that UNIX/Linux system
  64         accounts should be automatically created when these tools are used. In the absence of these scripts, and
  65         so long as <command>winbindd</command> is running, Samba group accounts that are created using these
  66         tools will be allocated UNIX UIDs and GIDs from the ID range specified by the
  67         <smbconfoption name="idmap uid"/>/<smbconfoption name="idmap gid"/>
  68         parameters in the &smb.conf; file.
  69         </para>
  70
  71         <figure id="idmap-sid2gid">
  72                 <title>IDMAP: Group SID-to-GID Resolution.</title>
  73                 <imagefile scale="50">idmap-sid2gid</imagefile>
  74         </figure>
  75
  76         <figure id="idmap-gid2sid">
  77                 <title>IDMAP: GID Resolution to Matching SID.</title>
  78         <imagefile scale="50">idmap-gid2sid</imagefile>
  79         </figure>
  80
  81         <para>
  82         <indexterm><primary>IDMAP</primary></indexterm>
  83 <indexterm><primary>SID-to-GID</primary></indexterm>
  84 <indexterm><primary>net</primary><secondary>groupmap</secondary></indexterm>
  85 <indexterm><primary>group mappings</primary></indexterm>
  86         In both cases, when winbindd is not running, only locally resolvable groups can be recognized. Please refer to
  87         <link linkend="idmap-sid2gid">IDMAP: Group SID-to-GID Resolution</link> and <link
  88         linkend="idmap-gid2sid">IDMAP: GID Resolution to Matching SID</link>.  The <command>net groupmap</command> is
  89         used to establish UNIX group to NT SID mappings as shown in <link linkend="idmap-store-gid2sid">IDMAP: storing
  90         group mappings</link>.
  91         </para>
  92
  93         <figure id="idmap-store-gid2sid">
  94                 <title>IDMAP Storing Group Mappings.</title>
  95                 <imagefile scale="50">idmap-store-gid2sid</imagefile>
  96         </figure>
  97
  98         <para>
  99         <indexterm><primary>groupadd</primary></indexterm>
 100         <indexterm><primary>groupdel</primary></indexterm>
 101 <indexterm><primary>shadow utilities</primary></indexterm>
 102 <indexterm><primary>groupmod</primary></indexterm>
 103         Administrators should be aware that where &smb.conf; group interface scripts make
 104         direct calls to the UNIX/Linux system tools (the shadow utilities, <command>groupadd</command>,
 105         <command>groupdel</command>, and <command>groupmod</command>), the resulting UNIX/Linux group names will be subject
 106         to any limits imposed by these tools. If the tool does not allow uppercase characters
 107         or space characters, then the creation of an MS Windows NT4/200x-style group of
 108         <literal>Engineering Managers</literal> will attempt to create an identically named
 109         UNIX/Linux group, an attempt that will of course fail.
 110         </para>
 111
 112         <para>
 113         <indexterm><primary>GID</primary></indexterm>
 114         <indexterm><primary>SID</primary></indexterm>
 115         There are several possible workarounds for the operating system tools limitation. One
 116         method is to use a script that generates a name for the UNIX/Linux system group that
 117         fits the operating system limits and that then just passes the UNIX/Linux group ID (GID)
 118         back to the calling Samba interface. This will provide a dynamic workaround solution.
 119         </para>
 120
 121         <para>
 122 <indexterm><primary>net</primary><secondary>groupmap</secondary></indexterm>
 123         Another workaround is to manually create a UNIX/Linux group, then manually create the
 124         MS Windows NT4/200x group on the Samba server, and then use the <command>net groupmap</command>
 125         tool to connect the two to each other.
 126         </para>
 127
 128 </sect1>
 129
 130 <sect1>
 131 <title>Discussion</title>
 132
 133         <para>
 134 <indexterm><primary>Windows NT4/200x</primary></indexterm>
 135 <indexterm><primary>group privileges</primary></indexterm>
 136         When you install <application>MS Windows NT4/200x</application> on a computer, the installation
 137         program creates default users and groups, notably the <constant>Administrators</constant> group,
 138         and gives that group privileges necessary to perform essential system tasks,
 139         such as the ability to change the date and time or to kill (or close) any process running on the
 140         local machine.
 141         </para>
 142
 143         <para>
 144         <indexterm><primary>Administrator</primary></indexterm>
 145         The <constant>Administrator</constant> user is a member of the <constant>Administrators</constant> group, and thus inherits
 146         <constant>Administrators</constant> group privileges. If a <constant>joe</constant> user is created to be a member of the
 147         <constant>Administrators</constant> group, <constant>joe</constant> has exactly the same rights as the user
 148         <constant>Administrator</constant>.
 149         </para>
 150
 151         <para>
 152 <indexterm><primary>domain member</primary></indexterm>
 153 <indexterm><primary>Domain Admins</primary></indexterm>
 154 <indexterm><primary>inherits rights</primary></indexterm>
 155 <indexterm><primary>PDC</primary></indexterm>
 156         When an MS Windows NT4/200x/XP machine is made a domain member, the <quote>Domain Admins</quote> group of the
 157         PDC is added to the local <constant>Administrators</constant> group of the workstation. Every member of the
 158         <constant>Domain Admins</constant> group inherits the rights of the local <constant>Administrators</constant> group when
 159         logging on the workstation.
 160         </para>
 161
 162         <para>
 163 <indexterm><primary>Domain Admins</primary></indexterm>
 164 <indexterm><primary>PDC</primary></indexterm>
 165         The following steps describe how to make Samba PDC users members of the <constant>Domain Admins</constant> group.
 166         </para>
 167
 168         <orderedlist>
 169                 <listitem><para>
 170                 Create a UNIX group (usually in <filename>/etc/group</filename>); let's call it <constant>domadm</constant>.
 171                 </para></listitem>
 172
 173                 <listitem><para>
 174 <indexterm><primary>/etc/group</primary></indexterm>
 175                 Add to this group the users that must be <quote>Administrators</quote>. For example,
 176                 if you want <constant>joe, john</constant>, and <constant>mary</constant> to be administrators,
 177                 your entry in <filename>/etc/group</filename> will look like this:
 178                 </para>
 179
 180                 <para><programlisting>
 181                 domadm:x:502:joe,john,mary
 182                 </programlisting>
 183                 </para></listitem>
 184
 185                 <listitem><para>
 186                 Map this domadm group to the <quote>Domain Admins</quote> group by running the command:
 187                 </para>
 188
 189                 <para>
 190 <screen>
 191 &rootprompt;<userinput>net groupmap add ntgroup="Domain Admins" unixgroup=domadm</userinput>
 192 </screen>
 193                 </para>
 194
 195                 <para>
 196                 <indexterm><primary>Domain Admins group</primary></indexterm>
 197                 The quotes around <quote>Domain Admins</quote> are necessary due to the space in the group name.
 198                 Also make sure to leave no white space surrounding the equal character (=).
 199                 </para></listitem>
 200         </orderedlist>
 201
 202         <para>
 203         Now <constant>joe, john</constant>, and <constant>mary</constant> are domain administrators.
 204         </para>
 205
 206         <para>
 207         <indexterm><primary>groups</primary><secondary>domain</secondary></indexterm>
 208         It is possible to map any arbitrary UNIX group to any Windows NT4/200x group as well as
 209         to make any UNIX group a Windows domain group. For example, if you wanted to include a
 210         UNIX group (e.g., acct) in an ACL on a local file or printer on a Domain Member machine,
 211         you would flag that group as a domain group by running the following on the Samba PDC:
 212         </para>
 213
 214         <para>
 215 <screen>
 216 &rootprompt;<userinput>net groupmap add rid=1000 ntgroup="Accounting" unixgroup=acct</userinput>
 217 </screen>
 218         The <literal>ntgroup</literal> value must be in quotes if it contains space characters to prevent
 219         the space from being interpreted as a command delimiter.
 220         </para>
 221
 222         <para>
 223 <indexterm><primary>RID</primary></indexterm>
 224 <indexterm><primary>assigned RID</primary></indexterm>
 225         Be aware that the RID parameter is an unsigned 32-bit integer that should
 226         normally start at 1000. However, this RID must not overlap with any RID assigned
 227         to a user. Verification for this is done differently depending on the passdb backend
 228         you are using. Future versions of the tools may perform the verification automatically,
 229         but for now the burden is on you.
 230         </para>
 231
 232         <sect2>
 233         <title>Warning: User Private Group Problems</title>
 234
 235         <para>
 236 <indexterm><primary>group accounts</primary></indexterm>
 237 <indexterm><primary>Red Hat Linux</primary></indexterm>
 238 <indexterm><primary>private groups</primary></indexterm>
 239         Windows does not permit user and group accounts to have the same name.
 240         This has serious implications for all sites that use private group accounts.
 241         A private group account is an administrative practice whereby users are each
 242         given their own group account. Red Hat Linux, as well as several free distributions
 243         of Linux, by default create private groups.
 244         </para>
 245
 246         <para>
 247 <indexterm><primary>UNIX/Linux group</primary></indexterm>
 248 <indexterm><primary>Windows group</primary></indexterm>
 249         When mapping a UNIX/Linux group to a Windows group account, all conflict can
 250         be avoided by assuring that the Windows domain group name does not overlap
 251         with any user account name.
 252         </para>
 253
 254         </sect2>
 255
 256         <sect2>
 257         <title>Nested Groups: Adding Windows Domain Groups to Windows Local Groups</title>
 258
 259         <indexterm><primary>groups</primary><secondary>nested</secondary></indexterm>
 260
 261         <para>
 262 <indexterm><primary>nested groups</primary></indexterm>
 263         This functionality is known as <constant>nested groups</constant> and was first added to
 264         Samba-3.0.3.
 265         </para>
 266
 267         <para>
 268 <indexterm><primary>nested groups</primary></indexterm>
 269         All MS Windows products since the release of Windows NT 3.10 support the use of nested groups.
 270         Many Windows network administrators depend on this capability because it greatly simplifies security
 271         administration.
 272         </para>
 273
 274         <para>
 275 <indexterm><primary>nested group</primary></indexterm>
 276 <indexterm><primary>group membership</primary></indexterm>
 277 <indexterm><primary>domain security</primary></indexterm>
 278 <indexterm><primary>domain member server</primary></indexterm>
 279 <indexterm><primary>local groups</primary></indexterm>
 280 <indexterm><primary>domain global groups</primary></indexterm>
 281 <indexterm><primary>domain global users</primary></indexterm>
 282         The nested group architecture was designed with the premise that day-to-day user and group membership
 283         management should be performed on the domain security database. The application of group security
 284         should be implemented on domain member servers using only local groups. On the domain member server,
 285         all file system security controls are then limited to use of the local groups, which will contain
 286         domain global groups and domain global users.
 287         </para>
 288
 289         <para>
 290 <indexterm><primary>individual domain user</primary></indexterm>
 291 <indexterm><primary>domain group settings</primary></indexterm>
 292 <indexterm><primary>Account Unknown</primary></indexterm>
 293         You may ask, What are the benefits of this arrangement? The answer is obvious to those who have plumbed
 294         the dark depths of Windows networking architecture. Consider for a moment a server on which are stored
 295         200,000 files, each with individual domain user and domain group settings. The company that owns the
 296         file server is bought by another company, resulting in the server being moved to another location, and then
 297         it is made a member of a different domain. Who would you think now owns all the files and directories?
 298         Answer: Account Unknown.
 299         </para>
 300
 301         <para>
 302 <indexterm><primary>directory access control</primary></indexterm>
 303 <indexterm><primary>local groups</primary></indexterm>
 304 <indexterm><primary>ACL</primary></indexterm>
 305 <indexterm><primary>Account Unknown</primary></indexterm>
 306         Unraveling the file ownership mess is an unenviable administrative task that can be avoided simply
 307         by using local groups to control all file and directory access control. In this case, only the members
 308         of the local groups will have been lost. The files and directories in the storage subsystem will still
 309         be owned by the local groups. The same goes for all ACLs on them. It is administratively much simpler
 310         to delete the <constant>Account Unknown</constant> membership entries inside local groups with appropriate
 311         entries for domain global groups in the new domain that the server has been made a member of.
 312         </para>
 313
 314         <para>
 315 <indexterm><primary>nested groups</primary></indexterm>
 316 <indexterm><primary>administrative privileges</primary></indexterm>
 317 <indexterm><primary>domain member workstations</primary></indexterm>
 318 <indexterm><primary>domain member servers</primary></indexterm>
 319 <indexterm><primary>member machine</primary></indexterm>
 320 <indexterm><primary>full rights</primary></indexterm>
 321 <indexterm><primary>Domain Admins</primary></indexterm>
 322 <indexterm><primary>local administrative privileges</primary></indexterm>
 323         Another prominent example of the use of nested groups involves implementation of administrative privileges
 324         on domain member workstations and servers. Administrative privileges are given to all members of the
 325         built-in local group <constant>Administrators</constant> on each domain member machine. To ensure that all domain
 326         administrators have full rights on the member server or workstation, on joining the domain, the
 327         <constant>Domain Admins</constant> group is added to the local Administrators group. Thus everyone who is
 328         logged into the domain as a member of the Domain Admins group is also granted local administrative
 329         privileges on each domain member.
 330         </para>
 331
 332         <para>
 333 <indexterm><primary>nested groups</primary></indexterm>
 334 <indexterm><primary>auxiliary members</primary></indexterm>
 335 <indexterm><primary>/etc/group</primary></indexterm>
 336 <indexterm><primary>winbind</primary></indexterm>
 337         UNIX/Linux has no concept of support for nested groups, and thus Samba has for a long time not supported
 338         them either. The problem is that you would have to enter UNIX groups as auxiliary members of a group in
 339         <filename>/etc/group</filename>. This does not work because it was not a design requirement at the time
 340         the UNIX file system security model was implemented. Since Samba-2.2, the winbind daemon can provide
 341         <filename>/etc/group</filename> entries on demand by obtaining user and group information from the domain
 342         controller that the Samba server is a member of.
 343         </para>
 344
 345         <para>
 346 <indexterm><primary>/etc/group</primary></indexterm>
 347 <indexterm><primary>libnss_winbind</primary></indexterm>
 348 <indexterm><primary>local groups</primary></indexterm>
 349 <indexterm><primary>Domain Users</primary></indexterm>
 350 <indexterm><primary>alias group</primary></indexterm>
 351         In effect, Samba supplements the <filename>/etc/group</filename> data via the dynamic
 352         <command>libnss_winbind</command> mechanism. Beginning with Samba-3.0.3, this facility is used to provide
 353         local groups in the same manner as Windows does it. It works by expanding the local groups on the
 354         fly as they are accessed. For example, the <constant>Domain Users</constant> group of the domain is made
 355         a member of the local group <constant>demo</constant>. Whenever Samba needs to resolve membership of the
 356         <constant>demo</constant> local (alias) group, winbind asks the domain controller for demo members of the Domain Users
 357         group. By definition, it can only contain user objects, which can then be faked to be member of the
 358         UNIX/Linux group <constant>demo</constant>.
 359         </para>
 360
 361         <para>
 362 <indexterm><primary>nested groups</primary></indexterm>
 363 <indexterm><primary>winbindd</primary></indexterm>
 364 <indexterm><primary>NSS</primary></indexterm>
 365 <indexterm><primary>winbind</primary></indexterm>
 366 <indexterm><primary>local groups</primary></indexterm>
 367 <indexterm><primary>Domain User Manager</primary></indexterm>
 368 <indexterm><primary>net</primary><secondary>rpc</secondary><tertiary>group</tertiary></indexterm>
 369         To enable the use of nested groups, <command>winbindd</command> must be used with NSS winbind.
 370         Creation and administration of the local groups is done best via the Windows Domain User Manager or its
 371         Samba equivalent, the utility <command>net rpc group</command>. Creating the local group
 372         <constant>demo</constant> is achieved by executing:
 373         <screen>
 374         &rootprompt; net rpc group add demo -L -Uroot%not24get
 375         </screen>
 376 <indexterm><primary>addmem</primary></indexterm>
 377 <indexterm><primary>delmem</primary></indexterm>
 378         Here the -L switch means that you want to create a local group. It may be necessary to add -S and -U
 379         switches for accessing the correct host with appropriate user or root privileges. Adding and removing
 380         group members can be done via the <constant>addmem</constant> and <constant>delmem</constant> subcommands of
 381         <command>net rpc group</command> command. For example, addition of <quote>DOM\Domain Users</quote> to the
 382         local group <constant>demo</constant> is done by executing:
 383         <screen>
 384         net rpc group addmem demo "DOM\Domain Users"
 385         </screen>
 386 <indexterm><primary>getent group demo</primary></indexterm>
 387 <indexterm><primary>trusted domain</primary></indexterm>
 388 <indexterm><primary>foreign domain</primary></indexterm>
 389 <indexterm><primary>local access permissions</primary></indexterm>
 390         Having completed these two steps, the execution of <command>getent group demo</command> will show demo
 391         members of the global <constant>Domain Users</constant> group as members of  the group
 392         <constant>demo</constant>.  This also works with any local or domain user. In case the domain DOM trusts
 393         another domain, it is also possible to add global users and groups of the trusted domain as members of
 394         <constant>demo</constant>. The users from the foreign domain who are members of the group that has been
 395         added to the <constant>demo</constant> group now have the same local access permissions as local domain
 396         users have.
 397         </para>
 398
 399         </sect2>
 400
 401         <sect2>
 402         <title>Important Administrative Information</title>
 403
 404         <para>
 405         Administrative rights are necessary in two specific forms:
 406         </para>
 407
 408         <orderedlist>
 409                 <listitem><para>For Samba-3 domain controllers and domain member servers/clients.</para></listitem>
 410                 <listitem><para>To manage domain member Windows workstations.</para></listitem>
 411         </orderedlist>
 412
 413         <para>
 414 <indexterm><primary>rights and privileges</primary></indexterm>
 415 <indexterm><primary>domain member client</primary></indexterm>
 416 <indexterm><primary>group account</primary></indexterm>
 417         Versions of Samba up to and including 3.0.10 do not provide a means for assigning rights and privileges
 418         that are necessary for system administration tasks from a Windows domain member client machine, so
 419         domain administration tasks such as adding, deleting, and changing user and group account information, and
 420         managing workstation domain membership accounts, can be handled by any account other than root.
 421         </para>
 422
 423         <para>
 424 <indexterm><primary>privilege management</primary></indexterm>
 425 <indexterm><primary>delegated</primary></indexterm>
 426 <indexterm><primary>Administrator</primary></indexterm>
 427         Samba-3.0.11 introduced a new privilege management interface (see <link linkend="rights">User Rights and Privileges</link>)
 428         that permits these tasks to be delegated to non-root (i.e., accounts other than the equivalent of the
 429         MS Windows Administrator) accounts.
 430         </para>
 431
 432         <para>
 433 <indexterm><primary>mapped</primary></indexterm>
 434 <indexterm><primary>Domain Admins</primary></indexterm>
 435         Administrative tasks on a Windows domain member workstation can be done by anyone who is a member of the
 436         <constant>Domain Admins</constant> group. This group can be mapped to any convenient UNIX group.
 437         </para>
 438
 439         <sect3>
 440         <title>Applicable Only to Versions Earlier than 3.0.11</title>
 441
 442         <para>
 443 <indexterm><primary>privilege</primary></indexterm>
 444         Administrative tasks on UNIX/Linux systems, such as adding users or groups, requires
 445         <constant>root</constant>-level privilege. The addition of a Windows client to a Samba domain involves the
 446         addition of a user account for the Windows client.
 447         </para>
 448
 449         <para>
 450 <indexterm><primary>system security</primary></indexterm>
 451 <indexterm><primary>privileges</primary></indexterm>
 452         Many UNIX administrators continue to request that the Samba Team make it possible to add Windows workstations, or
 453         the ability to add, delete, or modify user accounts, without requiring <constant>root</constant> privileges.
 454         Such a request violates every understanding of basic UNIX system security.
 455         </para>
 456
 457         <para>
 458 <indexterm><primary>privileges</primary></indexterm>
 459 <indexterm><primary>/etc/passwd</primary></indexterm>
 460 <indexterm><primary>Domain Server Manager</primary></indexterm>
 461 <indexterm><primary>Domain User Manager</primary></indexterm>
 462 <indexterm><primary>manage share-level ACL</primary></indexterm>
 463 <indexterm><primary>share-level ACLs</primary></indexterm>
 464         There is no safe way to provide access on a UNIX/Linux system without providing
 465         <constant>root</constant>-level privileges. Provision of <constant>root</constant> privileges can be done
 466         either by logging on to the Domain as the user <constant>root</constant> or by permitting particular users to
 467         use a UNIX account that has a UID=0 in the <filename>/etc/passwd</filename> database. Users of such accounts
 468         can use tools like the NT4 Domain User Manager and the NT4 Domain Server Manager to manage user and group
 469         accounts as well as domain member server and client accounts. This level of privilege is also needed to manage
 470         share-level ACLs.
 471         </para>
 472
 473         </sect3>
 474
 475         </sect2>
 476
 477         <sect2>
 478         <title>Default Users, Groups, and Relative Identifiers</title>
 479
 480         <para>
 481         <indexterm><primary>Relative Identifier</primary><see>RID</see></indexterm>
 482         <indexterm><primary>RID</primary></indexterm>
 483 <indexterm><primary>Windows NT4/200x/XP</primary></indexterm>
 484 <indexterm><primary>well-known RID</primary></indexterm>
 485 <indexterm><primary>domain groups</primary></indexterm>
 486 <indexterm><primary>tdbsam</primary></indexterm>
 487 <indexterm><primary>LDAP</primary></indexterm>
 488 <indexterm><primary>NT groups</primary></indexterm>
 489         When first installed, Windows NT4/200x/XP are preconfigured with certain user, group, and
 490         alias entities. Each has a well-known RID. These must be preserved for continued
 491         integrity of operation. Samba must be provisioned with certain essential domain groups that require
 492         the appropriate RID value. When Samba-3 is configured to use <constant>tdbsam</constant>, the essential
 493         domain groups are automatically created. It is the LDAP administrator's responsibility to create
 494         (provision) the default NT groups.
 495         </para>
 496
 497         <para>
 498 <indexterm><primary>default users</primary></indexterm>
 499 <indexterm><primary>default groups</primary></indexterm>
 500 <indexterm><primary>default aliases</primary></indexterm>
 501 <indexterm><primary>RID</primary></indexterm>
 502         Each essential domain group must be assigned its respective well-known RID. The default users, groups,
 503         aliases, and RIDs are shown in <link linkend="WKURIDS">Well-Known User Default RIDs</link>.
 504         </para>
 505
 506         <note><para>
 507 <indexterm><primary>passdb backend</primary></indexterm>
 508 <indexterm><primary>LDAP</primary></indexterm>
 509 <indexterm><primary>ldapsam</primary></indexterm>
 510 <indexterm><primary>domain groups</primary></indexterm>
 511 <indexterm><primary>RID</primary></indexterm>
 512         When the <parameter>passdb backend</parameter> uses LDAP (<constant>ldapsam</constant>), it is the
 513         administrator's responsibility to create the essential domain groups and to assign each its default RID.
 514         </para></note>
 515
 516         <para>
 517 <indexterm><primary>domain groups</primary></indexterm>
 518 <indexterm><primary>RID</primary></indexterm>
 519         It is permissible to create any domain group that may be necessary; just make certain that the essential
 520         domain groups (well known) have been created and assigned their default RIDs. Other groups you create may
 521         be assigned any arbitrary RID you care to use.
 522         </para>
 523
 524         <para>
 525         Be sure to map each domain group to a UNIX system group. That is the only way to ensure that the group
 526         will be available for use as an NT domain group.
 527         </para>
 528
 529         <para>
 530         <table frame="all" id="WKURIDS">
 531         <title>Well-Known User Default RIDs</title>
 532                 <tgroup cols="4" align="left">
 533                         <colspec align="left"/>
 534                         <colspec align="left"/>
 535                         <colspec align="left"/>
 536                         <colspec align="center"/>
 537                         <thead>
 538                                 <row>
 539                                         <entry>Well-Known Entity</entry>
 540                                         <entry>RID</entry>
 541                                         <entry>Type</entry>
 542                                         <entry>Essential</entry>
 543                                 </row>
 544                         </thead>
 545                         <tbody>
 546                                 <row>
 547                                         <entry>Domain Administrator</entry>
 548                                         <entry>500</entry>
 549                                         <entry>User</entry>
 550                                         <entry>No</entry>
 551                                 </row>
 552                                 <row>
 553                                         <entry>Domain Guest</entry>
 554                                         <entry>501</entry>
 555                                         <entry>User</entry>
 556                                         <entry>No</entry>
 557                                 </row>
 558                                 <row>
 559                                         <entry>Domain KRBTGT</entry>
 560                                         <entry>502</entry>
 561                                         <entry>User</entry>
 562                                         <entry>No</entry>
 563                                 </row>
 564                                 <row>
 565                                         <entry>Domain Admins</entry>
 566                                         <entry>512</entry>
 567                                         <entry>Group</entry>
 568                                         <entry>Yes</entry>
 569                                 </row>
 570                                 <row>
 571                                         <entry>Domain Users</entry>
 572                                         <entry>513</entry>
 573                                         <entry>Group</entry>
 574                                         <entry>Yes</entry>
 575                                 </row>
 576                                 <row>
 577                                         <entry>Domain Guests</entry>
 578                                         <entry>514</entry>
 579                                         <entry>Group</entry>
 580                                         <entry>Yes</entry>
 581                                 </row>
 582                                 <row>
 583                                         <entry>Domain Computers</entry>
 584                                         <entry>515</entry>
 585                                         <entry>Group</entry>
 586                                         <entry>No</entry>
 587                                 </row>
 588                                 <row>
 589                                         <entry>Domain Controllers</entry>
 590                                         <entry>516</entry>
 591                                         <entry>Group</entry>
 592                                         <entry>No</entry>
 593                                 </row>
 594                                 <row>
 595                                         <entry>Domain Certificate Admins</entry>
 596                                         <entry>517</entry>
 597                                         <entry>Group</entry>
 598                                         <entry>No</entry>
 599                                 </row>
 600                                 <row>
 601                                         <entry>Domain Schema Admins</entry>
 602                                         <entry>518</entry>
 603                                         <entry>Group</entry>
 604                                         <entry>No</entry>
 605                                 </row>
 606                                 <row>
 607                                         <entry>Domain Enterprise Admins</entry>
 608                                         <entry>519</entry>
 609                                         <entry>Group</entry>
 610                                         <entry>No</entry>
 611                                 </row>
 612                                 <row>
 613                                         <entry>Domain Policy Admins</entry>
 614                                         <entry>520</entry>
 615                                         <entry>Group</entry>
 616                                         <entry>No</entry>
 617                                 </row>
 618                                 <row>
 619                                         <entry>Builtin Admins</entry>
 620                                         <entry>544</entry>
 621                                         <entry>Alias</entry>
 622                                         <entry>No</entry>
 623                                 </row>
 624                                 <row>
 625                                         <entry>Builtin users</entry>
 626                                         <entry>545</entry>
 627                                         <entry>Alias</entry>
 628                                         <entry>No</entry>
 629                                 </row>
 630                                 <row>
 631                                         <entry>Builtin Guests</entry>
 632                                         <entry>546</entry>
 633                                         <entry>Alias</entry>
 634                                         <entry>No</entry>
 635                                 </row>
 636                                 <row>
 637                                         <entry>Builtin Power Users</entry>
 638                                         <entry>547</entry>
 639                                         <entry>Alias</entry>
 640                                         <entry>No</entry>
 641                                 </row>
 642                                 <row>
 643                                         <entry>Builtin Account Operators</entry>
 644                                         <entry>548</entry>
 645                                         <entry>Alias</entry>
 646                                         <entry>No</entry>
 647                                 </row>
 648                                 <row>
 649                                         <entry>Builtin System Operators</entry>
 650                                         <entry>549</entry>
 651                                         <entry>Alias</entry>
 652                                         <entry>No</entry>
 653                                 </row>
 654                                 <row>
 655                                         <entry>Builtin Print Operators</entry>
 656                                         <entry>550</entry>
 657                                         <entry>Alias</entry>
 658                                         <entry>No</entry>
 659                                 </row>
 660                                 <row>
 661                                         <entry>Builtin Backup Operators</entry>
 662                                         <entry>551</entry>
 663                                         <entry>Alias</entry>
 664                                         <entry>No</entry>
 665                                 </row>
 666                                 <row>
 667                                         <entry>Builtin Replicator</entry>
 668                                         <entry>552</entry>
 669                                         <entry>Alias</entry>
 670                                         <entry>No</entry>
 671                                 </row>
 672                                 <row>
 673                                         <entry>Builtin RAS Servers</entry>
 674                                         <entry>553</entry>
 675                                         <entry>Alias</entry>
 676                                         <entry>No</entry>
 677                                 </row>
 678                         </tbody>
 679                 </tgroup>
 680         </table>
 681         </para>
 682
 683         </sect2>
 684
 685         <sect2>
 686         <title>Example Configuration</title>
 687
 688                 <para>
 689 <indexterm><primary>net</primary><secondary>groupmap</secondary><tertiary>list</tertiary></indexterm>
 690                 You can list the various groups in the mapping database by executing
 691                 <command>net groupmap list</command>. Here is an example:
 692                 </para>
 693
 694                 <para>
 695 <indexterm><primary>net</primary><secondary>groupmap</secondary></indexterm>
 696 <screen>
 697 &rootprompt; <userinput>net groupmap list</userinput>
 698 Domain Admins (S-1-5-21-2547222302-1596225915-2414751004-512) -> domadmin
 699 Domain Users (S-1-5-21-2547222302-1596225915-2414751004-513) -> domuser
 700 Domain Guests (S-1-5-21-2547222302-1596225915-2414751004-514) -> domguest
 701 </screen>
 702                 </para>
 703
 704                 <para>
 705                 For complete details on <command>net groupmap</command>, refer to the net(8) man page.
 706                 </para>
 707
 708         </sect2>
 709
 710 </sect1>
 711
 712 <sect1>
 713 <title>Configuration Scripts</title>
 714
 715         <para>
 716         Everyone needs tools. Some of us like to create our own, others prefer to use canned tools
 717         (i.e., prepared by someone else for general use).
 718         </para>
 719
 720         <sect2>
 721         <title>Sample &smb.conf; Add Group Script</title>
 722
 723                 <para>
 724                 <indexterm><primary>smbgrpadd.sh</primary></indexterm>
 725                 <indexterm><primary>groupadd limitations</primary></indexterm>
 726                 <indexterm><primary>smbgrpadd.sh</primary></indexterm>
 727 <indexterm><primary>/etc/group</primary></indexterm>
 728 <indexterm><primary>groupadd</primary></indexterm>
 729                 A script to create complying group names for use by the Samba group interfaces
 730                 is provided in <link linkend="smbgrpadd.sh">smbgrpadd.sh</link>. This script
 731                 adds a temporary entry in the <filename>/etc/group</filename> file and then renames
 732                 it to the desired name. This is an example of a method to get around operating
 733                 system maintenance tool limitations such as those present in some version of the
 734                 <command>groupadd</command> tool.
 735 <example id="smbgrpadd.sh">
 736 <title>smbgrpadd.sh</title>
 737 <programlisting>
 738 #!/bin/bash
 739
 740 # Add the group using normal system groupadd tool.
 741 groupadd smbtmpgrp00
 742
 743 thegid=`cat /etc/group | grep ^smbtmpgrp00 | cut -d ":" -f3`
 744
 745 # Now change the name to what we want for the MS Windows networking end
 746 cp /etc/group /etc/group.bak
 747 cat /etc/group.bak | sed "s/^smbtmpgrp00/$1/g" > /etc/group
 748 rm /etc/group.bak
 749
 750 # Now return the GID as would normally happen.
 751 echo $thegid
 752 exit 0
 753 </programlisting>
 754 </example>
 755 </para>
 756
 757                 <para>
 758                 The &smb.conf; entry for the above script shown in <link linkend="smbgrpadd">the configuration of
 759                 &smb.conf; for the add group Script</link> demonstrates how it may be used.
 760
 761 <example id="smbgrpadd">
 762 <title>Configuration of &smb.conf; for the add group Script</title>
 763 <smbconfblock>
 764 <smbconfsection name="[global]"/>
 765 <smbconfoption name="add group script">/path_to_tool/smbgrpadd.sh &quot;%g&quot;</smbconfoption>
 766 </smbconfblock>
 767 </example>
 768                 </para>
 769
 770         </sect2>
 771
 772         <sect2>
 773         <title>Script to Configure Group Mapping</title>
 774
 775         <para>
 776 <indexterm><primary>initGroups.sh</primary></indexterm>
 777         In our example we have created a UNIX/Linux group called <literal>ntadmin</literal>.
 778         Our script will create the additional groups <literal>Orks</literal>, <literal>Elves</literal>, and <literal>Gnomes</literal>.
 779         It is a good idea to save this shell script for later use just in case you ever need to rebuild your mapping database.
 780         For the sake of convenience we elect to save this script as a file called <filename>initGroups.sh</filename>.
 781         This script is given in <link linkend="set-group-map">intGroups.sh</link>.
 782 <indexterm><primary>initGroups.sh</primary></indexterm>
 783 <example id="set-group-map">
 784 <title>Script to Set Group Mapping</title>
 785 <programlisting>
 786 #!/bin/bash
 787
 788 net groupmap modify ntgroup="Domain Admins" unixgroup=ntadmin
 789 net groupmap modify ntgroup="Domain Users" unixgroup=users
 790 net groupmap modify ntgroup="Domain Guests" unixgroup=nobody
 791
 792 groupadd Orks
 793 groupadd Elves
 794 groupadd Gnomes
 795
 796 net groupmap add ntgroup="Orks"   unixgroup=Orks   type=d
 797 net groupmap add ntgroup="Elves"  unixgroup=Elves  type=d
 798 net groupmap add ntgroup="Gnomes" unixgroup=Gnomes type=d
 799 </programlisting>
 800 </example>
 801         </para>
 802
 803         <para>
 804         Of course it is expected that the administrator will modify this to suit local needs.
 805         For information regarding the use of the <command>net groupmap</command> tool please
 806         refer to the man page.
 807         </para>
 808
 809         </sect2>
 810
 811 </sect1>
 812
 813 <sect1>
 814 <title>Common Errors</title>
 815
 816 <para>
 817 At this time there are many little surprises for the unwary administrator. In a real sense
 818 it is imperative that every step of automated control scripts be carefully tested
 819 manually before putting it into active service.
 820 </para>
 821
 822         <sect2>
 823         <title>Adding Groups Fails</title>
 824
 825                 <para>
 826 <indexterm><primary>groupadd</primary></indexterm>
 827                 This is a common problem when the <command>groupadd</command> is called directly
 828                 by the Samba interface script for the <smbconfoption name="add group script"/> in
 829                 the &smb.conf; file.
 830                 </para>
 831
 832                 <para>
 833 <indexterm><primary>uppercase character</primary></indexterm>
 834 <indexterm><primary>space character</primary></indexterm>
 835                 The most common cause of failure is an attempt to add an MS Windows group account
 836                 that has an uppercase character and/or a space character in it.
 837                 </para>
 838
 839                 <para>
 840 <indexterm><primary>groupadd</primary></indexterm>
 841                 There are three possible workarounds. First, use only group names that comply
 842                 with the limitations of the UNIX/Linux <command>groupadd</command> system tool.
 843                 Second, it involves the use of the script mentioned earlier in this chapter, and
 844                 third is the option is to manually create a UNIX/Linux group account that can substitute
 845                 for the MS Windows group name, then use the procedure listed above to map that group
 846                 to the MS Windows group.
 847                 </para>
 848
 849         </sect2>
 850
 851         <sect2>
 852         <title>Adding Domain Users to the Workstation Power Users Group</title>
 853
 854                 <para><quote>
 855                 What must I do to add domain users to the Power Users group?
 856                 </quote></para>
 857
 858                 <para>
 859 <indexterm><primary>Domain Users group</primary></indexterm>
 860                 The Power Users group is a group that is local to each Windows 200x/XP Professional workstation.
 861                 You cannot add the Domain Users group to the Power Users group automatically, it must be done on
 862                 each workstation by logging in as the local workstation <emphasis>administrator</emphasis> and
 863                 then using the following procedure:
 864                 </para>
 865
 866                 <procedure>
 867                         <step><para>
 868                         Click <guimenu>Start -> Control Panel -> Users and Passwords</guimenu>.
 869                         </para></step>
 870
 871                         <step><para>
 872                         Click the <guimenuitem>Advanced</guimenuitem> tab.
 873                         </para></step>
 874
 875                         <step><para>
 876                         Click the <guibutton>Advanced</guibutton> button.
 877                         </para></step>
 878
 879                         <step><para>
 880                         Click <constant>Groups</constant>.
 881                         </para></step>
 882
 883                         <step><para>
 884                         Double-click <constant>Power Users</constant>. This will launch the panel to add users or groups
 885                         to the local machine <constant>Power Users</constant> group.
 886                         </para></step>
 887
 888                         <step><para>
 889                         Click the <guibutton>Add</guibutton> button.
 890                         </para></step>
 891
 892                         <step><para>
 893                         Select the domain from which the <constant>Domain Users</constant> group is to be added.
 894                         </para></step>
 895
 896                         <step><para>
 897                         Double-click the <constant>Domain Users</constant> group.
 898                         </para></step>
 899
 900                         <step><para>
 901                         Click the <guibutton>OK</guibutton> button. If a logon box is presented during this process,
 902                         please remember to enter the connect as <constant>DOMAIN\UserName</constant>, that is, for the
 903                         domain <constant>MIDEARTH</constant> and the user <constant>root</constant> enter
 904                         <constant>MIDEARTH\root</constant>.
 905                         </para></step>
 906                 </procedure>
 907         </sect2>
 908
 909 </sect1>
 910
 911 </chapter>