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[Samba/gebeck_regimport.git] / docs / Samba3-HOWTO / TOSHARG-Winbind.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="winbind">

<chapterinfo>
        <author>
                <firstname>Tim</firstname><surname>Potter</surname>
                <affiliation>
                        <orgname>Samba Team</orgname>
                        <address><email>tpot@linuxcare.com.au</email></address>
                </affiliation>
        </author>
        &author.tridge;
        <author>
                <firstname>Naag</firstname><surname>Mummaneni</surname>
                <affiliation>
                        <address><email>getnag@rediffmail.com</email></address>
                </affiliation>
                <contrib>Notes for Solaris</contrib>
        </author>
        <author>
                <firstname>John</firstname><surname>Trostel</surname>
                <affiliation>
                        <orgname>SNAP</orgname>
                        <address><email>jtrostel@snapserver.com</email></address>
                </affiliation>
        </author>

        &author.jelmer;
        &author.jht;
        <pubdate>June 15, 2005</pubdate>
</chapterinfo>

<title>Winbind: Use of Domain Accounts</title>

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

        <para>
<indexterm><primary>holy grail</primary></indexterm>
<indexterm><primary>heterogeneous computing</primary></indexterm>
        Integration of UNIX and Microsoft Windows NT through a unified logon has
        been considered a <quote>holy grail</quote> in heterogeneous computing environments for
        a long time.
        </para>

        <para>
<indexterm><primary>interoperability</primary></indexterm>
<indexterm><primary>domain user</primary></indexterm>
<indexterm><primary>domain group</primary></indexterm>
<indexterm><primary>group ownership</primary></indexterm>
        There is one other facility without which UNIX and Microsoft Windows network
        interoperability would suffer greatly. It is imperative that there be a
        mechanism for sharing files across UNIX systems and to be able to assign
        domain user and group ownerships with integrity.
        </para>

        <para>
<indexterm><primary>Pluggable Authentication Modules</primary><see>PAM</see></indexterm>
<indexterm><primary>winbind</primary></indexterm>
<indexterm><primary>NSS</primary></indexterm>
<indexterm><primary>RPC</primary></indexterm>
        <emphasis>winbind</emphasis> is a component of the Samba suite of programs that
        solves the unified logon problem. Winbind uses a UNIX implementation of Microsoft
        RPC calls, Pluggable Authentication Modules (PAMs), and the name service switch (NSS) to
        allow Windows NT domain users to appear and operate as UNIX users on a UNIX
        machine. This chapter describes the Winbind system, the functionality
        it provides, how it is configured, and how it works internally.
        </para>

        <para>
        Winbind provides three separate functions:
        </para>

        <itemizedlist>
                <listitem><para>
<indexterm><primary>ADS</primary></indexterm>
<indexterm><primary>NT4 domain</primary></indexterm>
                Authentication of user credentials (via PAM). This makes it possible to
                log onto a UNIX/Linux system using user and group accounts from a Windows
                NT4 (including a Samba domain) or an Active Directory domain.
                </para></listitem>

                <listitem><para>
<indexterm><primary>identity resolution</primary></indexterm>
<indexterm><primary>NSS</primary></indexterm>
                Identity resolution (via NSS). This is the default when winbind is not used.
                </para></listitem>

                <listitem><para>
<indexterm><primary>UID</primary></indexterm>
<indexterm><primary>GID</primary></indexterm>
<indexterm><primary>SID</primary></indexterm>
<indexterm><primary>idmap uid</primary></indexterm>
<indexterm><primary>idmap gid</primary></indexterm>
<indexterm><primary>idmap backend</primary></indexterm>
<indexterm><primary></primary>LDAP</indexterm>
                Winbind maintains a database called winbind_idmap.tdb in which it stores
                mappings between UNIX UIDs, GIDs, and NT SIDs. This mapping is used only
                for users and groups that do not have a local UID/GID. It stores the UID/GID
                allocated from the idmap uid/gid range that it has mapped to the NT SID.
                If <parameter>idmap backend</parameter> has been specified as <constant>ldap:ldap://hostname[:389]</constant>,
                then instead of using a local mapping, Winbind will obtain this information
                from the LDAP database.
                </para></listitem>
        </itemizedlist>

        <note><para>
        <indexterm><primary>winbindd</primary></indexterm>
        <indexterm><primary>starting samba</primary><secondary>winbindd</secondary></indexterm>
<indexterm><primary>/etc/passwd</primary></indexterm>
<indexterm><primary>/etc/group</primary></indexterm>
<indexterm><primary>smbd</primary></indexterm>
<indexterm><primary>NSS</primary></indexterm>
        If <command>winbindd</command> is not running, smbd (which calls <command>winbindd</command>) will fall back to
        using purely local information from <filename>/etc/passwd</filename> and <filename>/etc/group</filename> and no dynamic
        mapping will be used. On an operating system that has beeb enabled with the NSS,
        the resolution of user and group information will be accomplished via NSS.
        </para></note>


        <figure id="winbind_idmap">
        <title>Winbind Idmap</title>
        <imagefile scale="50">idmap_winbind_no_loop</imagefile>
        </figure>

</sect1>


<sect1>
        <title>Introduction</title>
        
        <para>It is well known that UNIX and Microsoft Windows NT have 
        different models for representing user and group information and 
        use different technologies for implementing them. This fact has 
        made it difficult to integrate the two systems in a satisfactory 
        manner.</para>
        
        <para>
<indexterm><primary>synchronization problems</primary></indexterm>
<indexterm><primary>passwords</primary></indexterm>
        One common solution in use today has been to create 
        identically named user accounts on both the UNIX and Windows systems 
        and use the Samba suite of programs to provide file and print services 
        between the two. This solution is far from perfect, however, because 
        adding and deleting users on both sets of machines becomes a chore, 
        and two sets of passwords are required &smbmdash; both of which
        can lead to synchronization problems between the UNIX and Windows 
        systems and confusion for users.</para>
        
        <para>We divide the unified logon problem for UNIX machines into 
        three smaller problems:</para>
        
        <itemizedlist>
                <listitem><para>Obtaining Windows NT user and group information.
                </para></listitem>
                
                <listitem><para>Authenticating Windows NT users.
                </para></listitem>
                
                <listitem><para>Password changing for Windows NT users.
                </para></listitem>
        </itemizedlist>


        <para>
<indexterm><primary>unified logon</primary></indexterm>
<indexterm><primary>duplication of information</primary></indexterm>
        Ideally, a prospective solution to the unified logon problem 
        would satisfy all the above components without duplication of 
        information on the UNIX machines and without creating additional 
        tasks for the system administrator when maintaining users and 
        groups on either system. The Winbind system provides a simple 
        and elegant solution to all three components of the unified logon 
        problem.</para>
</sect1>


<sect1>
        <title>What Winbind Provides</title>

        <para>
<indexterm><primary>Windows account management</primary></indexterm>
<indexterm><primary>UNIX users</primary></indexterm>
<indexterm><primary>UNIX groups</primary></indexterm>
<indexterm><primary>NT domain</primary></indexterm>
        Winbind unifies UNIX and Windows NT account management by 
        allowing a UNIX box to become a full member of an NT domain. Once 
        this is done, the UNIX box will see NT users and groups as if 
        they were <quote>native</quote> UNIX users and groups, allowing the NT domain 
        to be used in much the same manner that NIS+ is used within 
        UNIX-only environments.</para>
        
        <para>
<indexterm><primary>Winbind hooks</primary></indexterm>
<indexterm><primary>domain controller</primary></indexterm>
<indexterm><primary>NSS</primary></indexterm>
<indexterm><primary>redirection</primary></indexterm>
        The end result is that whenever a
        program on the UNIX machine asks the operating system to look up 
        a user or group name, the query will be resolved by asking the 
        NT domain controller for the specified domain to do the lookup.
        Because Winbind hooks into the operating system at a low level 
        (via the NSS name resolution modules in the C library), this 
        redirection to the NT domain controller is completely 
        transparent.</para>
        
        <para>
<indexterm><primary>user and group</primary></indexterm>
<indexterm><primary>domain user</primary></indexterm>
        Users on the UNIX machine can then use NT user and group 
        names as they would <quote>native</quote> UNIX names. They can chown files 
        so they are owned by NT domain users or even login to the 
        UNIX machine and run a UNIX X-Window session as a domain user.</para>
        
        <para>
<indexterm><primary>domain controller</primary></indexterm>
        The only obvious indication that Winbind is being used is 
        that user and group names take the form <constant>DOMAIN\user</constant> and 
        <constant>DOMAIN\group</constant>. This is necessary because it allows Winbind to determine 
        that redirection to a domain controller is wanted for a particular 
        lookup and which trusted domain is being referenced.</para>
        
        <para>
<indexterm><primary>PAM-enabled</primary></indexterm>
<indexterm><primary>domain controller</primary></indexterm>
        Additionally, Winbind provides an authentication service that hooks into the PAM system 
        to provide authentication via an NT domain to any PAM-enabled 
        applications. This capability solves the problem of synchronizing 
        passwords between systems, since all passwords are stored in a single 
        location (on the domain controller).</para>
        
        <sect2>
                <title>Target Uses</title>
                
                <para>
<indexterm><primary>infrastructure</primary></indexterm>
                Winbind is targeted at organizations that have an 
                existing NT-based domain infrastructure into which they wish 
                to put UNIX workstations or servers. Winbind will allow these 
                organizations to deploy UNIX workstations without having to 
                maintain a separate account infrastructure. This greatly 
                simplifies the administrative overhead of deploying UNIX 
                workstations into an NT-based organization.</para>
                
                <para>
<indexterm><primary>Appliances</primary></indexterm>
<indexterm><primary>Winbind</primary></indexterm>
                Another interesting way in which we expect Winbind to 
                be used is as a central part of UNIX-based appliances. Appliances 
                that provide file and print services to Microsoft-based networks 
                will be able to use Winbind to provide seamless integration of 
                the appliance into the domain.</para>
        </sect2>

        <sect2>
        <title>Handling of Foreign SIDs</title>

        <para>
<indexterm><primary>foreign SID</primary></indexterm>
        The term <emphasis>foreign SID</emphasis> is often met with the reaction that it
        is not relevant to a particular environment. The following documents an interchange
        that took place on the Samba mailing list. It is a good example of the confusion
        often expressed regarding the use of winbind.
        </para>

        <para>
<indexterm><primary>local domain</primary></indexterm>
        Fact: Winbind is needed to handle users who use workstations that are NOT part 
        of the local domain.
        </para>

        <para>
<indexterm><primary>PDC</primary></indexterm>
        Response: <quote>Why? I've used Samba with workstations that are not part of my domains
        lots of times without using winbind. I though winbind was for using Samba as a member server
        in a domain controlled by another Samba/Windows PDC.</quote>
        </para>

        <para>
<indexterm><primary>UID</primary></indexterm>
<indexterm><primary>GID</primary></indexterm>
<indexterm><primary>foreign user</primary></indexterm>
        If the Samba server will be accessed from a domain other than the local Samba domain, or
        if there will be access from machines that are not local domain members, winbind will
        permit the allocation of UIDs and GIDs from the assigned pool that will keep the identity
        of the foreign user separate from users that are members of the Samba domain.
        </para>

        <para>
<indexterm><primary>PDC</primary></indexterm>
<indexterm><primary>domain member</primary></indexterm>
<indexterm><primary>domain non-member</primary></indexterm>
<indexterm><primary>SID</primary></indexterm>
        This means that winbind is eminently useful in cases where a single
        Samba PDC on a local network is combined with both domain member and domain non-member workstations.
        If winbind is not used, the user george on a Windows workstation that is not a domain
        member will be able to access the files of a user called george in the account database
        of the Samba server that is acting as a PDC. When winbind is used, the default condition
        is that the local user george will be treated as the account DOMAIN\george and the
        foreign (non-member of the domain) account will be treated as MACHINE\george because
        each has a different SID.
        </para>

        </sect2>
</sect1>



<sect1>
        <title>How Winbind Works</title>
        
        <para>
<indexterm><primary>winbindd</primary></indexterm>
<indexterm><primary>UNIX domain socket</primary></indexterm>
<indexterm><primary>NSS</primary></indexterm>
<indexterm><primary>PAM</primary></indexterm>
        The Winbind system is designed around a client/server 
        architecture. A long-running <command>winbindd</command> daemon 
        listens on a UNIX domain socket waiting for requests
        to arrive. These requests are generated by the NSS and PAM 
        clients and are processed sequentially.</para>
        
        <para>The technologies used to implement Winbind are described 
        in detail below.</para>
        
        <sect2>
                <title>Microsoft Remote Procedure Calls</title>
                
                <para>
<indexterm><primary>Microsoft Remote Procedure Call</primary><see>MSRPC</see></indexterm>
<indexterm><primary>PDC</primary></indexterm>
<indexterm><primary>remote management</primary></indexterm>
<indexterm><primary>user authentication</primary></indexterm>
<indexterm><primary>print spooling</primary></indexterm>
                Over the last few years, efforts have been underway 
                by various Samba Team members to decode various aspects of 
                the Microsoft Remote Procedure Call (MSRPC) system. This 
                system is used for most network-related operations between 
                Windows NT machines, including remote management, user authentication,
                and print spooling. Although initially this work was done 
                to aid the implementation of Primary Domain Controller (PDC) 
                functionality in Samba, it has also yielded a body of code that 
                can be used for other purposes.</para>
                
                <para>
<indexterm><primary>MSRPC</primary></indexterm>
<indexterm><primary>enumerate domain users</primary></indexterm>
<indexterm><primary>enumerate domain groups</primary></indexterm>
                Winbind uses various MSRPC calls to enumerate domain users 
                and groups and to obtain detailed information about individual 
                users or groups. Other MSRPC calls can be used to authenticate 
                NT domain users and to change user passwords. By directly querying 
                a Windows PDC for user and group information, Winbind maps the 
                NT account information onto UNIX user and group names.</para>
        </sect2>
        
        <sect2>
                <title>Microsoft Active Directory Services</title>

                <para>
<indexterm><primary>LDAP</primary></indexterm>
<indexterm><primary>Kerberos</primary></indexterm>
<indexterm><primary>Winbind</primary></indexterm>
<indexterm><primary>native mode</primary></indexterm>
                Since late 2001, Samba has gained the ability to interact with Microsoft Windows 2000 using its <quote>native
                mode</quote> protocols rather than the NT4 RPC services.  Using LDAP and Kerberos, a domain member running
                Winbind can enumerate users and groups in exactly the same way as a Windows 200x client would, and in so doing
                provide a much more efficient and effective Winbind implementation. 
                </para>
        </sect2>
        
        <sect2>
                <title>Name Service Switch</title>
                
                <para>
<indexterm><primary>NSS</primary></indexterm>
<indexterm><primary>networked workstation</primary></indexterm>
<indexterm><primary>NIS</primary></indexterm>
<indexterm><primary>DNS</primary></indexterm>
                The NSS is a feature that is present in many UNIX operating systems. It allows system 
                information such as hostnames, mail aliases, and user information 
                to be resolved from different sources. For example, a standalone 
                UNIX workstation may resolve system information from a series of 
                flat files stored on the local file system. A networked workstation 
                may first attempt to resolve system information from local files, 
                and then consult an NIS database for user information or a DNS server 
                for hostname information.</para>
                
                <para>
<indexterm><primary>NSS</primary></indexterm>
<indexterm><primary>MSRPC</primary></indexterm>
<indexterm><primary>trusted domain</primary></indexterm>
<indexterm><primary>local users</primary></indexterm>
<indexterm><primary>local groups</primary></indexterm>
                The NSS application programming interface allows Winbind 
                to present itself as a source of system information when 
                resolving UNIX usernames and groups. Winbind uses this interface 
                and information obtained from a Windows NT server using MSRPC 
                calls to provide a new source of account enumeration. Using standard 
                UNIX library calls, you can enumerate the users and groups on
                a UNIX machine running Winbind and see all users and groups in 
                an NT domain plus any trusted domain as though they were local 
                users and groups.</para>
                
                <para>
<indexterm><primary>NSS</primary></indexterm>
<indexterm><primary>/etc/nsswitch.conf</primary></indexterm>
<indexterm><primary>passwd</primary></indexterm>
                The primary control file for NSS is <filename>/etc/nsswitch.conf</filename>. 
                When a UNIX application makes a request to do a lookup, 
                the C library looks in <filename>/etc/nsswitch.conf</filename> 
                for a line that matches the service type being requested; for 
                example, the <quote>passwd</quote> service type is used when user or group names 
                are looked up. This config line specifies which implementations 
                of that service should be tried and in what order. If the passwd 
                config line is:
<screen>
passwd: files example
</screen>
<indexterm><primary>/lib/libnss_files.so</primary></indexterm>
<indexterm><primary>/lib/libnss_example.so</primary></indexterm>
<indexterm><primary>resolver functions</primary></indexterm>
                then the C library will first load a module called 
                <filename>/lib/libnss_files.so</filename> followed by
                the module <filename>/lib/libnss_example.so</filename>. The 
                C library will dynamically load each of these modules in turn 
                and call resolver functions within the modules to try to resolve 
                the request. Once the request is resolved, the C library returns the
                result to the application.</para>
                
                <para>
<indexterm><primary>NSS</primary></indexterm>
<indexterm><primary>libnss_winbind.so</primary></indexterm>
<indexterm><primary>/etc/nsswitch.conf</primary></indexterm>
                This NSS interface provides an easy way for Winbind 
                to hook into the operating system. All that needs to be done 
                is to put <filename>libnss_winbind.so</filename> in <filename>/lib/</filename> 
                then add <quote>winbind</quote> into <filename>/etc/nsswitch.conf</filename> at 
                the appropriate place. The C library will then call Winbind to 
                resolve user and group names.</para>
        </sect2>
        
        <sect2>
                <title>Pluggable Authentication Modules</title>
                
                <para>
<indexterm><primary>PAM</primary></indexterm>
<indexterm><primary>authentication methods</primary></indexterm>
<indexterm><primary>authorization</primary></indexterm>
<indexterm><primary>NIS database</primary></indexterm>
                PAMs provide a system for abstracting authentication and authorization 
                technologies. With a PAM module, it is possible to specify different 
                authentication methods for different system applications without 
                having to recompile these applications. PAM is also useful
                for implementing a particular policy for authorization. For example, 
                a system administrator may only allow console logins from users 
                stored in the local password file but only allow users resolved from 
                an NIS database to log in over the network.</para>
                
                <para>
<indexterm><primary>PAM</primary></indexterm>
<indexterm><primary>Winbind</primary></indexterm>
<indexterm><primary>authentication management</primary></indexterm>
<indexterm><primary>password management</primary></indexterm>
<indexterm><primary>PDC</primary></indexterm>
                Winbind uses the authentication management and password 
                management PAM interface to integrate Windows NT users into a 
                UNIX system. This allows Windows NT users to log in to a UNIX 
                machine and be authenticated against a suitable PDC.
                These users can also change their passwords and have 
                this change take effect directly on the PDC.
                </para>
                
                <para>
<indexterm><primary>PAM</primary></indexterm>
<indexterm><primary>/etc/pam.d/</primary></indexterm>
<indexterm><primary>pam_winbind.so</primary></indexterm>
<indexterm><primary>/lib/security/</primary></indexterm>
                PAM is configured by providing control files in the directory 
                <filename>/etc/pam.d/</filename> for each of the services that 
                require authentication. When an authentication request is made 
                by an application, the PAM code in the C library looks up this
                control file to determine what modules to load to do the 
                authentication check and in what order. This interface makes adding 
                a new authentication service for Winbind very easy: simply copy 
                the <filename>pam_winbind.so</filename> module 
                to <filename>/lib/security/</filename>, and the PAM 
                control files for relevant services are updated to allow 
                authentication via Winbind. See the PAM documentation
                in <link linkend="pam">PAM-Based Distributed Authentication</link>, for more information.</para>
        </sect2>
        
        
        <sect2>
                <title>User and Group ID Allocation</title>
                
                <para>
<indexterm><primary>RID</primary></indexterm>
<indexterm><primary>Winbind</primary></indexterm>
<indexterm><primary>UNIX ID</primary></indexterm>
                When a user or group is created under Windows NT/200x, 
                it is allocated a numerical relative identifier (RID). This is 
                slightly different from UNIX, which has a range of numbers that are 
                used to identify users and the same range used to identify 
                groups. It is Winbind's job to convert RIDs to UNIX ID numbers and
                vice versa. When Winbind is configured, it is given part of the UNIX 
                user ID space and a part of the UNIX group ID space in which to 
                store Windows NT users and groups. If a Windows NT user is 
                resolved for the first time, it is allocated the next UNIX ID from 
                the range. The same process applies for Windows NT groups. Over 
                time, Winbind will have mapped all Windows NT users and groups
                to UNIX user IDs and group IDs.</para>

                <para>
<indexterm><primary>ID mapping database</primary></indexterm>
<indexterm><primary>tdb</primary></indexterm>
<indexterm><primary>UNIX ID</primary></indexterm>
<indexterm><primary>RID</primary></indexterm>
                The results of this mapping are stored persistently in 
                an ID mapping database held in a tdb database. This ensures that 
                RIDs are mapped to UNIX IDs in a consistent way.</para>
        </sect2>
        
        
        <sect2>
                <title>Result Caching</title>

                <para>
<indexterm><primary>SAM</primary></indexterm>
<indexterm><primary>caching scheme</primary></indexterm>
<indexterm><primary>Winbind</primary></indexterm>
<indexterm><primary>ADS</primary></indexterm>
<indexterm><primary>PDC</primary></indexterm>
                        An active directory system can generate a lot of user and group 
                name lookups. To reduce the network cost of these lookups, Winbind 
                uses a caching scheme based on the SAM sequence number supplied 
                by NT domain controllers. User or group information returned 
                by a PDC is cached by Winbind along with a sequence number also 
                returned by the PDC. This sequence number is incremented by 
                Windows NT whenever any user or group information is modified. If 
                a cached entry has expired, the sequence number is requested from 
                the PDC and compared against the sequence number of the cached entry. 
                If the sequence numbers do not match, then the cached information 
                is discarded and up-to-date information is requested directly 
                from the PDC.</para>
        </sect2>
</sect1>


<sect1>
        <title>Installation and Configuration</title>
        
<sect2>
<title>Introduction</title>

<para>
<indexterm><primary>Winbind</primary></indexterm>
<indexterm><primary>PDC</primary></indexterm>
<indexterm><primary>authentication control</primary></indexterm>
This section describes the procedures used to get Winbind up and 
running. Winbind is capable of providing access 
and authentication control for Windows Domain users through an NT 
or Windows 200x PDC for regular services, such as telnet and ftp, as
well for Samba services.
</para>

<itemizedlist>
<listitem>
        <para>
        <emphasis>Why should I do this?</emphasis>
        </para>
        
        <para>This allows the Samba administrator to rely on the 
        authentication mechanisms on the Windows NT/200x PDC for the authentication 
        of domain members. Windows NT/200x users no longer need to have separate 
        accounts on the Samba server.
        </para>
</listitem>

<listitem>
        <para>
        <emphasis>Who should be reading this document?</emphasis>
        </para>
        
        <para>
        This document is designed for system administrators. If you are 
        implementing Samba on a file server and wish to (fairly easily) 
        integrate existing Windows NT/200x users from your PDC onto the
        Samba server, this document is for you.
        </para>
</listitem>
</itemizedlist>
</sect2>


<sect2>
<title>Requirements</title>

<para>
If you have a Samba configuration file that you are currently using, <emphasis>BACK IT UP!</emphasis>
If your system already uses PAM, <emphasis>back up the <filename>/etc/pam.d</filename> directory
contents!</emphasis> If you haven't already made a boot disk, <emphasis>MAKE ONE NOW!</emphasis>
</para>

<para>
Messing with the PAM configuration files can make it nearly impossible to log in to your machine. That's
why you want to be able to boot back into your machine in single-user mode and restore your
<filename>/etc/pam.d</filename> to the original state it was in if you get frustrated with the
way things are going.
</para>

<para>
The latest version of Samba-3 includes a functioning winbindd daemon. Please refer to the <ulink
url="http://samba.org/">main Samba Web page</ulink>, or better yet, your closest Samba mirror site for
instructions on downloading the source code.
</para>

<para>
To allow domain users the ability to access Samba shares and files, as well as potentially other services
provided by your Samba machine, PAM must be set up properly on your
machine. In order to compile the Winbind modules, you should have at least the PAM development libraries installed
on your system. Please refer the PAM Web site <ulink url="http://www.kernel.org/pub/linux/libs/pam/"/>.
</para>
</sect2>

<sect2>
<title>Testing Things Out</title>

<para>
Before starting, it is probably best to kill off all the Samba-related daemons running on your server.
Kill off all &smbd;, &nmbd;, and &winbindd; processes that may be running. To use PAM,
make sure that you have the standard PAM package that supplies the <filename>/etc/pam.d</filename>
directory structure, including the PAM modules that are used by PAM-aware services, several PAM libraries,
and the <filename>/usr/doc</filename> and <filename>/usr/man</filename> entries for PAM. Winbind is built
better in Samba if the pam-devel package is also installed. This package includes the header files
needed to compile PAM-aware applications.
</para>

<sect3>
<title>Configure <filename>nsswitch.conf</filename> and the Winbind Libraries on Linux and Solaris</title>

<para>
PAM is a standard component of most current generation UNIX/Linux systems. Unfortunately, few systems install
the <filename>pam-devel</filename> libraries that are needed to build PAM-enabled Samba. Additionally, Samba-3
may auto-install the Winbind files into their correct locations on your system, so before you get too far down
the track, be sure to check if the following configuration is really
necessary. You may only need to configure
<filename>/etc/nsswitch.conf</filename>.
</para>

<para>
The libraries needed to run the &winbindd; daemon through nsswitch need to be copied to their proper locations:
</para>

<para>
<screen>
&rootprompt;<userinput>cp ../samba/source/nsswitch/libnss_winbind.so /lib</userinput>
</screen>
</para>

<para>
I also found it necessary to make the following symbolic link:
</para>

<para>
&rootprompt; <userinput>ln -s /lib/libnss_winbind.so /lib/libnss_winbind.so.2</userinput>
</para>

<para>And, in the case of Sun Solaris:</para>
<screen>
&rootprompt;<userinput>ln -s /usr/lib/libnss_winbind.so /usr/lib/libnss_winbind.so.1</userinput>
&rootprompt;<userinput>ln -s /usr/lib/libnss_winbind.so /usr/lib/nss_winbind.so.1</userinput>
&rootprompt;<userinput>ln -s /usr/lib/libnss_winbind.so /usr/lib/nss_winbind.so.2</userinput>
</screen>

<para>
Now, as root, you need to edit <filename>/etc/nsswitch.conf</filename> to 
allow user and group entries to be visible from the &winbindd;
daemon. My <filename>/etc/nsswitch.conf</filename> file looked like 
this after editing:
</para>

<para><programlisting>
        passwd:     files winbind
        shadow:     files 
        group:      files winbind
</programlisting></para>

<para>  
The libraries needed by the <command>winbindd</command> daemon will be automatically 
entered into the <command>ldconfig</command> cache the next time 
your system reboots, but it is faster (and you do not need to reboot) if you do it manually:
</para>

<para>
&rootprompt;<userinput>/sbin/ldconfig -v | grep winbind</userinput>
</para>

<para>
This makes <filename>libnss_winbind</filename> available to winbindd 
and echos back a check to you.
</para>

</sect3>

<sect3>
<title>NSS Winbind on AIX</title>

<para>(This section is only for those running AIX.)</para>

<para>
The Winbind AIX identification module gets built as <filename>libnss_winbind.so</filename> in the
nsswitch directory of the Samba source. This file can be copied to <filename>/usr/lib/security</filename>,
and the AIX naming convention would indicate that it should be named WINBIND. A stanza like the following:
<programlisting>
WINBIND:
        program = /usr/lib/security/WINBIND
        options = authonly
</programlisting>
can then be added to <filename>/usr/lib/security/methods.cfg</filename>. This module only supports
identification, but there have been reports of success using the standard Winbind PAM module for
authentication. Use caution configuring loadable authentication modules, since misconfiguration can make
it impossible to log on to the system.  Information regarding the AIX authentication module API can
be found in the <quote>Kernel Extensions and Device Support Programming Concepts for AIX</quote> document that
describes the <ulink url="http://publibn.boulder.ibm.com/doc_link/en_US/a_doc_lib/aixprggd/kernextc/sec_load_mod.htm">
Loadable Authentication Module Programming Interface</ulink> for AIX. Further information on administering the modules
can be found in the <ulink url="http://publibn.boulder.ibm.com/doc_link/en_US/a_doc_lib/aixbman/baseadmn/iandaadmin.htm">System
Management Guide: Operating System and Devices.</ulink>
</para>
</sect3>

<sect3>
<title>Configure smb.conf</title>

<para>
Several parameters are needed in the &smb.conf; file to control the behavior of &winbindd;. These
are described in more detail in the <citerefentry><refentrytitle>winbindd</refentrytitle>
<manvolnum>8</manvolnum></citerefentry> man page. My &smb.conf; file, as shown in <link
linkend="winbindcfg">Example 23.5.1</link>, was modified to include the necessary entries in the [global] section.
</para>

<example id="winbindcfg">
<title>smb.conf for Winbind Setup</title>
<smbconfblock>
<smbconfsection name="[global]"/>
<smbconfcomment> separate domain and username with '\', like DOMAIN\username</smbconfcomment>
<smbconfoption name="winbind separator">\</smbconfoption>
<smbconfcomment> use uids from 10000 to 20000 for domain users</smbconfcomment>
<smbconfoption name="idmap uid">10000-20000</smbconfoption>
<smbconfcomment> use gids from 10000 to 20000 for domain groups</smbconfcomment>
<smbconfoption name="idmap gid">10000-20000</smbconfoption>
<smbconfcomment> allow enumeration of winbind users and groups</smbconfcomment>
<smbconfoption name="winbind enum users">yes</smbconfoption>
<smbconfoption name="winbind enum groups">yes</smbconfoption>
<smbconfcomment> give winbind users a real shell (only needed if they have telnet access)</smbconfcomment>
<smbconfoption name="template homedir">/home/winnt/%D/%U</smbconfoption>
<smbconfoption name="template shell">/bin/bash</smbconfoption>
</smbconfblock>
</example>

</sect3>


<sect3>
<title>Join the Samba Server to the PDC Domain</title>

<para>
All machines that will participate in domain security should be members of
the domain. This applies also to the PDC and all BDCs.
</para>

<para>
The process of joining a domain requires the use of the <command>net rpc join</command>
command. This process communicates with the domain controller it will register with
(usually the PDC) via MS DCE RPC. This means, of course, that the <command>smbd</command>
process must be running on the target domain controller. It is therefore necessary to temporarily
start Samba on a PDC so that it can join its own domain.
</para>

<para>
Enter the following command to make the Samba server join the 
domain, where <replaceable>PDC</replaceable> is the name of 
your PDC and <replaceable>Administrator</replaceable> is 
a domain user who has administrative privileges in the domain.
</para>
        
<note><para>
Before attempting to join a machine to the domain, verify that Samba is running
on the target domain controller (usually PDC) and that it is capable of being reached via ports
137/udp, 135/tcp, 139/tcp, and 445/tcp (if Samba or Windows Server 2Kx).
</para></note>

<para>
&rootprompt;<userinput>/usr/local/samba/bin/net rpc join -S PDC -U Administrator</userinput>
</para>

<para>
The proper response to the command should be <quote>Joined the domain 
<replaceable>DOMAIN</replaceable></quote> where <replaceable>DOMAIN</replaceable> 
is your domain name.
</para>

</sect3>

<sect3>
<title>Starting and Testing the <command>winbindd</command> Daemon</title>

<para>
Eventually, you will want to modify your Samba startup script to 
automatically invoke the winbindd daemon when the other parts of 
Samba start, but it is possible to test out just the Winbind
portion first. To start up Winbind services, enter the following 
command as root:
</para>
        
<para>
&rootprompt;<userinput>/usr/local/samba/sbin/winbindd</userinput>
</para>

<note><para>
The command to start up Winbind services assumes that Samba has been installed in the <filename>/usr/local/samba</filename>
directory tree. You may need to search for the location of Samba files if this is not the
location of <command>winbindd</command> on your system.
</para></note>

<para>
Winbindd can now also run in <quote>dual daemon mode</quote>. This will make it 
run as two processes. The first will answer all requests from the cache,
thus making responses to clients faster. The other will
update the cache for the query to which the first has just responded.
The advantage of this is that responses stay accurate and are faster. 
You can enable dual daemon mode by adding <option>-B</option> to the command line:
</para>

<para>
&rootprompt;<userinput>/usr/local/samba/sbin/winbindd -B</userinput>
</para>

<para>
I'm always paranoid and like to make sure the daemon is really running.
</para>

<para>
&rootprompt;<userinput>ps -ae | grep winbindd</userinput>
</para>
<para>
This command should produce output like the following if the daemon is running.

</para>
<screen>
3025 ?        00:00:00 winbindd
</screen>

<para>
Now, for the real test, try to get some information about the users on your PDC:
</para>

<para>
&rootprompt;<userinput>/usr/local/samba/bin/wbinfo -u</userinput>
</para>

<para>  
This should echo back a list of users on your Windows users on 
your PDC. For example, I get the following response:
</para>

<para><screen>
        CEO\Administrator
        CEO\burdell
        CEO\Guest
        CEO\jt-ad
        CEO\krbtgt
        CEO\TsInternetUser
</screen></para>

<para>
Obviously, I have named my domain <quote>CEO</quote> and my <smbconfoption name="winbind separator"/> is <quote>\</quote>.
</para>

<para>
You can do the same sort of thing to get group information from the PDC:
</para>

<para><screen>
&rootprompt;<userinput>/usr/local/samba/bin/wbinfo -g</userinput>
        CEO\Domain Admins
        CEO\Domain Users
        CEO\Domain Guests
        CEO\Domain Computers
        CEO\Domain Controllers
        CEO\Cert Publishers
        CEO\Schema Admins
        CEO\Enterprise Admins
        CEO\Group Policy Creator Owners
</screen></para>

<para>
The function <command>getent</command> can now be used to get unified 
lists of both local and PDC users and groups. Try the following command:
</para>

<para>
&rootprompt;<userinput>getent passwd</userinput>
</para>
        
<para>
You should get a list that looks like your <filename>/etc/passwd</filename> 
list followed by the domain users with their new UIDs, GIDs, home 
directories, and default shells.
</para>

<para>
The same thing can be done for groups with the command:
</para>

<para>
&rootprompt;<userinput>getent group</userinput>
</para>

</sect3>


<sect3>
<title>Fix the init.d Startup Scripts</title>

<sect4>
<title>Linux</title>

<para>
The &winbindd; daemon needs to start up after the &smbd; and &nmbd; daemons are running. 
To accomplish this task, you need to modify the startup scripts of your system.
They are located at <filename>/etc/init.d/smb</filename> in Red Hat Linux and in 
<filename>/etc/init.d/samba</filename> in Debian Linux. Edit your
script to add commands to invoke this daemon in the proper sequence. My 
startup script starts up &smbd;, &nmbd;, and &winbindd; from the 
<filename>/usr/local/samba/bin</filename> directory directly. The <command>start</command> 
function in the script looks like this:
</para>

<para><programlisting>
start() {
        KIND="SMB"
        echo -n $"Starting $KIND services: "
        daemon /usr/local/samba/bin/smbd $SMBDOPTIONS
        RETVAL=$?
        echo
        KIND="NMB"
        echo -n $"Starting $KIND services: "
        daemon /usr/local/samba/bin/nmbd $NMBDOPTIONS
        RETVAL2=$?
        echo
        KIND="Winbind"
        echo -n $"Starting $KIND services: "
        daemon /usr/local/samba/sbin/winbindd
        RETVAL3=$?
        echo
        [ $RETVAL -eq 0 -a $RETVAL2 -eq 0 -a $RETVAL3 -eq 0 ] &amp;&amp; \
                touch /var/lock/subsys/smb || RETVAL=1
        return $RETVAL
}
</programlisting></para>

<para>If you would like to run winbindd in dual daemon mode, replace 
the line:
<programlisting>
        daemon /usr/local/samba/sbin/winbindd
</programlisting>

in the example above with:

<programlisting>
        daemon /usr/local/samba/sbin/winbindd -B
</programlisting>.
</para>

<para>
The <command>stop</command> function has a corresponding entry to shut down the 
services and looks like this:
</para>

<para><programlisting>
stop() {
        KIND="SMB"
        echo -n $"Shutting down $KIND services: "
        killproc smbd
        RETVAL=$?
        echo
        KIND="NMB"
        echo -n $"Shutting down $KIND services: "
        killproc nmbd
        RETVAL2=$?
        echo
        KIND="Winbind"
        echo -n $"Shutting down $KIND services: "
        killproc winbindd
        RETVAL3=$?
        [ $RETVAL -eq 0 -a $RETVAL2 -eq 0 -a $RETVAL3 -eq 0 ] &amp;&amp; \
                 rm -f /var/lock/subsys/smb
        echo ""
        return $RETVAL
}
</programlisting></para>
</sect4>

<sect4>
<title>Solaris</title>

<para>
Winbind does not work on Solaris 9; see <link linkend="winbind-solaris9">Winbind on Solaris 9 section</link>
for details.
</para>

<para>
On Solaris, you need to modify the <filename>/etc/init.d/samba.server</filename> startup script. It
usually only starts smbd and nmbd but should now start winbindd, too. If you have Samba installed in
<filename>/usr/local/samba/bin</filename>, the file could contains something like this:
</para>

<para>
        <programlisting>
        ##
        ## samba.server
        ##

        if [ ! -d /usr/bin ]
        then                    # /usr not mounted
                exit
        fi

        killproc() {            # kill the named process(es)
                pid=`/usr/bin/ps -e |
                     /usr/bin/grep -w $1 |
                     /usr/bin/sed -e 's/^  *//' -e 's/ .*//'`
                [ "$pid" != "" ] &amp;&amp; kill $pid
        }
         
        # Start/stop processes required for Samba server

        case "$1" in

        'start')
        #
        # Edit these lines to suit your installation (paths, workgroup, host)
        #
        echo Starting SMBD
           /usr/local/samba/bin/smbd -D -s \
                /usr/local/samba/smb.conf

        echo Starting NMBD
           /usr/local/samba/bin/nmbd -D -l \
                /usr/local/samba/var/log -s /usr/local/samba/smb.conf

        echo Starting Winbind Daemon
           /usr/local/samba/sbin/winbindd
           ;;

        'stop')
           killproc nmbd
           killproc smbd
           killproc winbindd
           ;;

        *)
           echo "Usage: /etc/init.d/samba.server { start | stop }"
           ;;
        esac
</programlisting></para>

<para>
Again, if you would like to run Samba in dual daemon mode, replace:
<programlisting>
        /usr/local/samba/sbin/winbindd
</programlisting>
in the script above with:
<programlisting>
        /usr/local/samba/sbin/winbindd -B
</programlisting>
</para>

</sect4>

<sect4>
<title>Restarting</title>
<para>
If you restart the &smbd;, &nmbd;, and &winbindd; daemons at this point, you
should be able to connect to the Samba server as a domain member just as
if you were a local user.
</para>
</sect4>
</sect3>

<sect3>
<title>Configure Winbind and PAM</title>

<para>
If you have made it this far, you know that <command>winbindd</command> and Samba are working
together. If you want to use Winbind to provide authentication for other 
services, keep reading. The PAM configuration files need to be altered in
this step. (Did you remember to make backups of your original 
<filename>/etc/pam.d</filename> files? If not, do it now.)
</para>

<para>
You will need a PAM module to use winbindd with these other services. This 
module will be compiled in the <filename>../source/nsswitch</filename> directory
by invoking the command:
</para>

<para>
&rootprompt;<userinput>make nsswitch/pam_winbind.so</userinput>
</para>

<para>
from the <filename>../source</filename> directory. The
<filename>pam_winbind.so</filename> file should be copied to the location of
your other PAM security modules. On my Red Hat system, this was the
<filename>/lib/security</filename> directory. On Solaris, the PAM security 
modules reside in <filename>/usr/lib/security</filename>.
</para>

<para>
&rootprompt;<userinput>cp ../samba/source/nsswitch/pam_winbind.so /lib/security</userinput>
</para>

<sect4>
<title>Linux/FreeBSD-Specific PAM Configuration</title>

<para>
The <filename>/etc/pam.d/samba</filename> file does not need to be changed. I 
just left this file as it was:
</para>


<para><programlisting>
        auth    required        /lib/security/pam_stack.so service=system-auth
        account required        /lib/security/pam_stack.so service=system-auth
</programlisting></para>

<para>
The other services that I modified to allow the use of Winbind 
as an authentication service were the normal login on the console (or a terminal 
session), telnet logins, and ftp service. In order to enable these 
services, you may first need to change the entries in 
<filename>/etc/xinetd.d</filename> (or <filename>/etc/inetd.conf</filename>). 
Red Hat Linux 7.1 and later uses the new xinetd.d structure, in this case you need 
to change the lines in <filename>/etc/xinetd.d/telnet</filename> 
and <filename>/etc/xinetd.d/wu-ftp</filename> from 
</para>

<para><programlisting>
        enable = no
</programlisting>
to
<programlisting>
        enable = yes
</programlisting></para>

<para>  
For ftp services to work properly, you will also need to either 
have individual directories for the domain users already present on 
the server or change the home directory template to a general
directory for all domain users. These can be easily set using 
the &smb.conf; global entry 
<smbconfoption name="template homedir"/>.
</para>

<note>
        <para>The directory in <smbconfoption name="template homedir"/> is not created automatically! Use pam_mkhomedir or pre-create 
                the directories of users to make sure users can log in on UNIX with 
                their own home directory.
        </para>
</note>

<para>
The <filename>/etc/pam.d/ftp</filename> file can be changed 
to allow Winbind ftp access in a manner similar to the
samba file. My <filename>/etc/pam.d/ftp</filename> file was 
changed to look like this:
<programlisting>
auth       required     /lib/security/pam_listfile.so item=user sense=deny \
         file=/etc/ftpusers onerr=succeed
auth       sufficient   /lib/security/pam_winbind.so
auth       required     /lib/security/pam_stack.so service=system-auth
auth       required     /lib/security/pam_shells.so
account    sufficient   /lib/security/pam_winbind.so
account    required     /lib/security/pam_stack.so service=system-auth
session    required     /lib/security/pam_stack.so service=system-auth
</programlisting></para>

<para>
The <filename>/etc/pam.d/login</filename> file can be changed in nearly the 
same way. It now looks like this:
<programlisting>
auth       required     /lib/security/pam_securetty.so
auth       sufficient   /lib/security/pam_winbind.so
auth       sufficient   /lib/security/pam_unix.so use_first_pass
auth       required     /lib/security/pam_stack.so service=system-auth
auth       required     /lib/security/pam_nologin.so
account    sufficient   /lib/security/pam_winbind.so
account    required     /lib/security/pam_stack.so service=system-auth
password   required     /lib/security/pam_stack.so service=system-auth
session    required     /lib/security/pam_stack.so service=system-auth
session    optional     /lib/security/pam_console.so
</programlisting></para>

<para>
In this case, I added the <programlisting>auth sufficient /lib/security/pam_winbind.so</programlisting> 
lines as before, but also added the <programlisting>required pam_securetty.so</programlisting>
above it to disallow root logins over the network. I also added a 
<programlisting>sufficient /lib/security/pam_unix.so use_first_pass</programlisting>
line after the <command>winbind.so</command> line to get rid of annoying 
double prompts for passwords.
</para>

</sect4>

<sect4>
<title>Solaris-Specific Configuration</title>

<para>
The <filename>/etc/pam.conf</filename> needs to be changed. I changed this file so my Domain
users can log on both locally as well as with telnet. The following are the changes
that I made. You can customize the <filename>pam.conf</filename> file as per your requirements, but
be sure of those changes because in the worst case it will leave your system
nearly impossible to boot.
</para>

<para><programlisting>
#
#ident "@(#)pam.conf 1.14 99/09/16 SMI"
#
# Copyright (c) 1996-1999, Sun Microsystems, Inc.
# All Rights Reserved.
#
# PAM configuration
#
# Authentication management
#
login   auth required   /usr/lib/security/pam_winbind.so
login auth required  /usr/lib/security/$ISA/pam_unix.so.1 try_first_pass 
login auth required  /usr/lib/security/$ISA/pam_dial_auth.so.1 try_first_pass 
#
rlogin  auth sufficient /usr/lib/security/pam_winbind.so
rlogin  auth sufficient /usr/lib/security/$ISA/pam_rhosts_auth.so.1
rlogin auth required  /usr/lib/security/$ISA/pam_unix.so.1 try_first_pass
#
dtlogin auth sufficient /usr/lib/security/pam_winbind.so
dtlogin auth required  /usr/lib/security/$ISA/pam_unix.so.1 try_first_pass
#
rsh auth required /usr/lib/security/$ISA/pam_rhosts_auth.so.1
other   auth sufficient /usr/lib/security/pam_winbind.so
other auth required /usr/lib/security/$ISA/pam_unix.so.1 try_first_pass
#
# Account management
#
login   account sufficient      /usr/lib/security/pam_winbind.so
login account requisite /usr/lib/security/$ISA/pam_roles.so.1 
login account required /usr/lib/security/$ISA/pam_unix.so.1 
#
dtlogin account sufficient      /usr/lib/security/pam_winbind.so
dtlogin account requisite /usr/lib/security/$ISA/pam_roles.so.1 
dtlogin account required /usr/lib/security/$ISA/pam_unix.so.1 
#
other   account sufficient      /usr/lib/security/pam_winbind.so
other account requisite /usr/lib/security/$ISA/pam_roles.so.1 
other account required /usr/lib/security/$ISA/pam_unix.so.1 
#
# Session management
#
other session required /usr/lib/security/$ISA/pam_unix.so.1 
#
# Password management
#
#other   password sufficient     /usr/lib/security/pam_winbind.so
other password required /usr/lib/security/$ISA/pam_unix.so.1 
dtsession auth required /usr/lib/security/$ISA/pam_unix.so.1
#
# Support for Kerberos V5 authentication (uncomment to use Kerberos)
#
#rlogin auth optional /usr/lib/security/$ISA/pam_krb5.so.1 try_first_pass
#login auth optional /usr/lib/security/$ISA/pam_krb5.so.1 try_first_pass
#dtlogin auth optional /usr/lib/security/$ISA/pam_krb5.so.1 try_first_pass
#other auth optional /usr/lib/security/$ISA/pam_krb5.so.1 try_first_pass
#dtlogin account optional /usr/lib/security/$ISA/pam_krb5.so.1
#other account optional /usr/lib/security/$ISA/pam_krb5.so.1
#other session optional /usr/lib/security/$ISA/pam_krb5.so.1
#other password optional /usr/lib/security/$ISA/pam_krb5.so.1 try_first_pass
</programlisting></para>

<para>
I also added a <parameter>try_first_pass</parameter> line after the <filename>winbind.so</filename>
line to get rid of annoying double prompts for passwords.
</para>

<para>
Now restart your Samba and try connecting through your application that you
configured in the pam.conf.
</para>

</sect4>

</sect3>

</sect2>

</sect1>

<sect1>
<title>Conclusion</title>

<para>The Winbind system, through the use of the NSS, 
PAMs, and appropriate 
Microsoft RPC calls, have allowed us to provide seamless 
integration of Microsoft Windows NT domain users on a
UNIX system. The result is a great reduction in the administrative 
cost of running a mixed UNIX and NT network.</para>
        
</sect1>

<sect1>
<title>Common Errors</title>
        
        <para>Winbind has a number of limitations in its current 
        released version that we hope to overcome in future 
        releases:</para>

        <itemizedlist>
                <listitem><para>Winbind is currently only available for 
                the Linux, Solaris, AIX, and IRIX operating systems, although ports to other operating 
                systems are certainly possible. For such ports to be feasible, 
                we require the C library of the target operating system to 
                support the NSS and PAM
                systems. This is becoming more common as NSS and 
                PAM gain support among UNIX vendors.</para></listitem>
                
                <listitem><para>The mappings of Windows NT RIDs to UNIX IDs 
                is not made algorithmically and depends on the order in which 
                unmapped users or groups are seen by Winbind. It may be difficult 
                to recover the mappings of RID to UNIX ID if the file 
                containing this information is corrupted or destroyed.</para>
                </listitem>
                
                <listitem><para>Currently the Winbind PAM module does not take 
                into account possible workstation and logon time restrictions 
                that may be set for Windows NT users; this is
                instead up to the PDC to enforce.</para></listitem>
        </itemizedlist>

        <sect2>
        <title>NSCD Problem Warning</title>

        <?latex \nopagebreak ?>

        <warning><para>
        Do not under any circumstances run <command>nscd</command> on any system
        on which <command>winbindd</command> is running.
        </para></warning>

        <para>
        If <command>nscd</command> is running on the UNIX/Linux system, then
        even though NSSWITCH is correctly configured, it will not be possible to resolve
        domain users and groups for file and directory controls.
        </para>

        </sect2>

        <sect2>
        <title>Winbind Is Not Resolving Users and Groups</title>

        <para><quote>
        My &smb.conf; file is correctly configured. I have specified 
        <smbconfoption name="idmap uid">12000</smbconfoption>, 
        and <smbconfoption name="idmap gid">3000-3500</smbconfoption>
        and <command>winbind</command> is running. When I do the following, it all works fine.
        </quote></para>

<para><screen>
&rootprompt;<userinput>wbinfo -u</userinput>
MIDEARTH\maryo
MIDEARTH\jackb
MIDEARTH\ameds
...
MIDEARTH\root

&rootprompt;<userinput>wbinfo -g</userinput>
MIDEARTH\Domain Users
MIDEARTH\Domain Admins
MIDEARTH\Domain Guests
...
MIDEARTH\Accounts

&rootprompt;<userinput>getent passwd</userinput>
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/bin/bash
...
maryo:x:15000:15003:Mary Orville:/home/MIDEARTH/maryo:/bin/false
</screen></para>

<para><quote>
But the following command just fails:
</quote>
<screen>
&rootprompt;<userinput>chown maryo a_file</userinput>
chown: `maryo': invalid user
</screen>
<quote>
This is driving me nuts! What can be wrong?
</quote></para>

<para>
Same problem as the one above.
Your system is likely running <command>nscd</command>, the name service
caching daemon. Shut it down, do not restart it! You will find your problem resolved.
</para>

</sect2>
</sect1>

</chapter>