<?xml version="1.0" encoding="iso8859-1"?>
<chapter id="groupmapping">
<chapterinfo>
	<author>
		<firstname>Jean Fran�ois</firstname><surname>Micouleau</surname>
	</author>
	&author.jerry;
</chapterinfo>

<title>Configuring Group Mapping</title>

<para>
Starting with Samba 3.0 alpha 2, new group mapping functionality
is available to create associations between Windows SIDs and UNIX
groups. The <parameter>groupmap</parameter> subcommand included with
the <command>net</command> tool can be used to manage these associations.
</para>

<para>
The first immediate reason to use the group mapping on a Samba PDC, is that
the <parameter>domain admin group</parameter> &smb.conf; has been removed.
This parameter was used to give the listed users membership in the "Domain Admins"
Windows group which gave local admin rights on their workstations (in
default configurations).
</para>

<para>
When installing NT/W2K on a computer, the installer program creates some users
and groups. Notably the 'Administrators' group, and gives to that group some
privileges like the ability to change the date and time or to kill any process
(or close too) running on the local machine. The 'Administrator' user is a
member of the 'Administrators' group, and thus 'inherit' the 'Administrators'
group privileges. If a 'joe' user is created and become a member of the
'Administrator' group, 'joe' has exactly the same rights as 'Administrator'.
</para>

<para>
When a NT/W2K machine is joined to a domain, the "Domain Adminis" group of the
PDC is added to the local 'Administrators' group of the workstation. Every
member of the 'Domain Administrators' group 'inherit' the
rights of the local 'Administrators' group when logging on the workstation.
</para>

<para>
The following steps describe how to make samba PDC users members of the
'Domain Admins' group?
</para>

<orderedlist>
<listitem><para>create a unix group (usually in <filename>/etc/group</filename>),
  let's call it domadm</para></listitem>
<listitem><para>add to this group the users that must be Administrators. For example
  if you want joe,john and mary, your entry in <filename>/etc/group</filename> will
  look like:</para>

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

  </listitem>

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

  <para><prompt>root# </prompt><userinput>net groupmap add ntgroup="Domain Admins" unixgroup=domadm</userinput></para>
  
  <para>The quotes around "Domain Admins" are necessary due to the space in the group name.  Also make
  sure to leave no whitespace surrounding the equal character (=).</para>
  </listitem>

</orderedlist>

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

<para>
It is possible to map any arbitrary UNIX group to any Windows NT
group as well as making any UNIX group a Windows domain group.
For example, if you wanted to include a UNIX group (e.g. acct) in a 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><prompt>root# </prompt><userinput>net groupmap add rid=1000 ntgroup="Accounting" unixgroup=acct</userinput></para>

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

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

<para><programlisting><prompt>root# </prompt>net groupmap list
System Administrators (S-1-5-21-2547222302-1596225915-2414751004-1002) -> sysadmin
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
</programlisting></para>

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

</chapter>