merging some changes from SAMBA_2_2

[kai/samba.git] / docs / docbook / projdoc / winbind.sgml

<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>
                <firstname>Andrew</firstname><surname>Trigdell</surname>
                <affiliation>
                        <orgname>Samba Team</orgname>
                        <address><email>tridge@linuxcare.com.au</email></address>
                </affiliation>
        </author>
        <author>
                <firstname>John</firstname><surname>Trostel</surname>
                <affiliation>
                        <orgname>Snapserver</orgname>
                        <address><email>jtrostel@snapserver.com</email></address>
                </affiliation>
        </author>
        
                
        <pubdate>16 Oct 2000</pubdate>
</chapterinfo>

<title>Unified Logons between Windows NT and UNIX using Winbind</title>

<sect1>
        <title>Abstract</title>

        <para>Integration of UNIX and Microsoft Windows NT through 
        a unified logon has been considered a "holy grail" in heterogeneous 
        computing environments for a long time. We present 
        <emphasis>winbind</emphasis>, a component of the Samba suite 
        of programs as a solution to the unified logon problem. Winbind 
        uses a UNIX implementation 
        of Microsoft RPC calls, Pluggable Authentication Modules, and the Name 
        Service Switch to allow Windows NT domain users to appear and operate 
        as UNIX users on a UNIX machine. This paper describes the winbind 
        system, explaining the functionality it provides, how it is configured, 
        and how it works internally.</para>
</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>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, as 
        adding and deleting users on both sets of machines becomes a chore 
        and two sets of passwords are required 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>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>Winbind unifies UNIX and Windows NT account management by 
        allowing a UNIX box to become a full member of a NT domain. Once 
        this is done the UNIX box will see NT users and groups as if 
        they were native 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>The end result is that whenever any 
        program on the UNIX machine asks the operating system to lookup 
        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>Users on the UNIX machine can then use NT user and group 
        names as they would use "native" UNIX names. They can chown files 
        so that 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>The only obvious indication that Winbind is being used is 
        that user and group names take the form DOMAIN\user and 
        DOMAIN\group. This is necessary as 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>Additionally, Winbind provides an authentication service 
        that hooks into the Pluggable Authentication Modules (PAM) system 
        to provide authentication via a 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>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 a NT based organization.</para>
                
                <para>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>
</sect1>



<sect1>
        <title>How Winbind Works</title>
        
        <para>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 processed sequentially.</para>
        
        <para>The technologies used to implement winbind are described 
        in detail below.</para>
        
        <sect2>
                <title>Microsoft Remote Procedure Calls</title>
                
                <para>Over the last two 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 which 
                can be used for other purposes.</para>
                
                <para>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>Name Service Switch</title>
                
                <para>The Name Service Switch, or 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 filesystem. A networked workstation 
                may first attempt to resolve system information from local files, 
                and then consult a NIS database for user information or a DNS server 
                for hostname information.</para>
                
                <para>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, one can enumerate the users and groups on
                a UNIX machine running winbind and see all users and groups in 
                a NT domain plus any trusted domain as though they were local 
                users and groups.</para>
                
                <para>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 which matches the service type being requested, for 
                example the "passwd" service type is used when user or group names 
                are looked up. This     config line species which implementations 
                of that service should be tried and in what order. If the passwd 
                config line is:</para>

                <para><command>passwd: files example</command></para>

                <para>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>This NSS interface provides a very 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 "winbind" 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>Pluggable Authentication Modules, also known as PAM, 
                is 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 
                a NIS database to log in over the network.</para>
                
                <para>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 Primary Domain 
                Controller. These users can also change their passwords and have 
                this change take effect directly on the Primary Domain Controller.
                </para>
                
                <para>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, all that needs 
                to be done is that the <filename>pam_winbind.so</filename> module 
                is copied to <filename>/lib/security/</filename> and the PAM 
                control files for relevant services are updated to allow 
                authentication via winbind. See the PAM documentation
                for more details.</para>
        </sect2>
        
        
        <sect2>
                <title>User and Group ID Allocation</title>
                
                <para>When a user or group is created under Windows NT 
                is it allocated a numerical relative identifier (RID). This is 
                slightly different to UNIX which has a range of numbers that are 
                used to identify users, and the same range in which 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>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>An active 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>
        
<para>
Many thanks to John Trostel <ulink 
url="mailto:jtrostel@snapserver.com">jtrostel@snapserver.com</ulink>
for providing the HOWTO for this section.
</para>

<para>
This HOWTO describes how to get winbind services up and running 
to control access and authenticate users on your Linux box using 
the winbind services which come with SAMBA 2.2.2.
</para>

<para>
There is also some Solaris specific information in 
<filename>docs/textdocs/Solaris-Winbind-HOWTO.txt</filename>.
Future revisions of this document will incorporate that
information.
</para>



<sect2>
<title>Introduction</title>

<para>
This HOWTO describes the procedures used to get winbind up and 
running on my RedHat 7.1 system.  Winbind is capable of providing access 
and authentication control for Windows Domain users through an NT 
or Win2K PDC for 'regular' services, such as telnet a nd ftp, as
well for SAMBA services.
</para>

<para>
This HOWTO has been written from a 'RedHat-centric' perspective, so if 
you are using another distribution, you may have to modify the instructions 
somewhat to fit the way your distribution works.
</para>


<itemizedlist>
<listitem>
        <para>
        <emphasis>Why should I to this?</emphasis>
        </para>
        
        <para>This allows the SAMBA administrator to rely on the 
        authentication mechanisms on the NT/Win2K PDC for the authentication 
        of domain members.  NT/Win2K 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 HOWTO is designed for system administrators.  If you are 
        implementing SAMBA on a file server and wish to (fairly easily) 
        integrate existing NT/Win2K users from your PDC onto the
        SAMBA server, this HOWTO is for you.  That said, I am no NT or PAM 
        expert, so you may find a better or easier way to accomplish 
        these tasks.
        </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 yourmachine. 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> back to the original state they were in if 
you get frustrated with the way things are going.  ;-)
</para>

<para>
The latest version of SAMBA (version 2.2.2 as of this writing), now 
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 (pluggable authentication modules) must
be setup properly on your machine.  In order to compile the 
winbind modules, you should have at least the pam libraries resident 
on your system.  For recent RedHat systems (7.1, for instance), that 
means <filename>pam-0.74-22</filename>.  For best results, it is helpful to also
install the development packages in <filename>pam-devel-0.74-22</filename>.
</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 <command>smbd</command>, 
<command>nmbd</command>, and <command>winbindd</command> processes that may 
be running.  To use PAM, you will want to make sure that you have the 
standard PAM package (for RedHat) which supplies the <filename>/etc/pam.d</filename> 
directory structure, including the pam modules are used by pam-aware 
services, several pam libraries, and the <filename>/usr/doc</filename> 
and <filename>/usr/man</filename> entries for pam.  Winbind built better 
in SAMBA if the pam-devel package was also installed.  This package includes 
the header files needed to compile pam-aware applications. For instance, 
my RedHat system has both <filename>pam-0.74-22</filename> and
<filename>pam-devel-0.74-22</filename> RPMs installed.
</para>

<sect3>
<title>Configure and compile SAMBA</title>

<para>
The configuration and compilation of SAMBA is pretty straightforward.
The first three steps may not be necessary depending upon
whether or not you have previously built the Samba binaries.
</para>

<para><programlisting>
<prompt>root#</prompt> <command>autoconf</command>
<prompt>root#</prompt> <command>make clean</command>
<prompt>root#</prompt> <command>rm config.cache</command>
<prompt>root#</prompt> <command>./configure --with-winbind</command>
<prompt>root#</prompt> <command>make</command>
<prompt>root#</prompt> <command>make install</command>
</programlisting></para>


<para>
This will, by default, install SAMBA in <filename>/usr/local/samba</filename>.
See the main SAMBA documentation if you want to install SAMBA somewhere else.
It will also build the winbindd executable and libraries. 
</para>

</sect3>

<sect3>
<title>Configure <filename>nsswitch.conf</filename> and the 
winbind libraries</title>

<para>
The libraries needed to run the <command>winbindd</command> daemon 
through nsswitch need to be copied to their proper locations, so
</para>

<para>
<prompt>root#</prompt> <command>cp ../samba/source/nsswitch/libnss_winbind.so /lib</command>
</para>

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

<para>
<prompt>root#</prompt> <command>ln -s /lib/libnss_winbind.so /lib/libnss_winbind.so.2</command>
</para>

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

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

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

<para>
<prompt>root#</prompt> <command>/sbin/ldconfig -v | grep winbind</command>
</para>

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

</sect3>


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

<para>
Several parameters are needed in the smb.conf file to control 
the behavior of <command>winbindd</command>. Configure 
<filename>smb.conf</filename> These are described in more detail in 
the <ulink url="winbindd.8.html">winbindd(8)</ulink> man page.  My 
<filename>smb.conf</filename> file was modified to
include the following entries in the [global] section:
</para>

<para><programlisting>
[global]
     <...>
     # separate domain and username with '+', like DOMAIN+username
     <ulink url="winbindd.8.html#WINBINDSEPARATOR">winbind separator</ulink> = +
     # use uids from 10000 to 20000 for domain users
     <ulink url="winbindd.8.html#WINBINDUID">winbind uid</ulink> = 10000-20000
     # use gids from 10000 to 20000 for domain groups
     <ulink url="winbindd.8.html#WINBINDGID">winbind gid</ulink> = 10000-20000
     # allow enumeration of winbind users and groups
     <ulink url="winbindd.8.html#WINBINDENUMUSERS">winbind enum users</ulink> = yes
     <ulink url="winbindd.8.html#WINBINDENUMGROUP">winbind enum groups</ulink> = yes
     # give winbind users a real shell (only needed if they have telnet access)
     <ulink url="winbindd.8.html#TEMPLATEHOMEDIR">template homedir</ulink> = /home/winnt/%D/%U
     <ulink url="winbindd.8.html#TEMPLATESHELL">template shell</ulink> = /bin/bash
</programlisting></para>

</sect3>


<sect3>
<title>Join the SAMBA server to the PDC domain</title>

<para>
Enter the following command to make the SAMBA server join the 
PDC domain, where <replaceable>DOMAIN</replaceable> is the name of 
your Windows domain and <replaceable>Administrator</replaceable> is 
a domain user who has administrative privileges in the domain.
</para>
        

<para>
<prompt>root#</prompt> <command>/usr/local/samba/bin/net rpc join -s PDC -U Administrator</command>
</para>


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

</sect3>


<sect3>
<title>Start up the winbindd daemon and test it!</title>

<para>
Eventually, you will want to modify your smb 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>
<prompt>root#</prompt> <command>/usr/local/samba/bin/winbindd</command>
</para>

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

<para>
<prompt>root#</prompt> <command>ps -ae | grep winbindd</command>
</para>
<para>
This command should produce output like this, if the daemon is running
</para>
<para>
3025 ?        00:00:00 winbindd
</para>

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

<para>
<prompt>root#</prompt> <command>/usr/local/samba/bin/wbinfo -u</command>
</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><programlisting>
CEO+Administrator
CEO+burdell
CEO+Guest
CEO+jt-ad
CEO+krbtgt
CEO+TsInternetUser
</programlisting></para>

<para>
Obviously, I have named my domain 'CEO' and my <parameter>winbind
separator</parameter> is '+'.
</para>

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

<para><programlisting>
<prompt>root#</prompt> <command>/usr/local/samba/bin/wbinfo -g</command>
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
</programlisting></para>

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

<para>
<prompt>root#</prompt> <command>getent passwd</command>
</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>
<prompt>root#</prompt> <command>getent group</command>
</para>

</sect3>


<sect3>
<title>Fix the <filename>/etc/rc.d/init.d/smb</filename> startup files</title>

<para>
The <command>winbindd</command> daemon needs to start up after the 
<command>smbd</command> and <command>nmbd</command> daemons are running.  
To accomplish this task, you need to modify the <filename>/etc/init.d/smb</filename>
script to add commands to invoke this daemon in the proper sequence.  My 
<filename>/etc/init.d/smb</filename> file starts up <command>smbd</command>, 
<command>nmbd</command>, and <command>winbindd</command> from the 
<filename>/usr/local/samba/bin</filename> directory directly.  The 'start' 
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 $KIND services: "
        daemon /usr/local/samba/bin/winbindd
        RETVAL3=$?
        echo
        [ $RETVAL -eq 0 -a $RETVAL2 -eq 0 -a $RETVAL3 -eq 0 ] && touch /var/lock/subsys/smb || \
           RETVAL=1
        return $RETVAL
}
</programlisting></para>

<para>
The 'stop' function has a corresponding entry to shut down the 
services and look s 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 ] && rm -f /var/lock/subsys/smb
        echo ""
        return $RETVAL
}
</programlisting></para>

<para>
If you restart the <command>smbd</command>, <command>nmbd</command>, 
and <command>winbindd</command> 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>

</sect3>



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

<para>
If you have made it this far, you know that winbindd 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>
<prompt>root#</prompt> <command>make nsswitch/pam_winbind.so</command>
</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 RedHat system, this was the
<filename>/lib/security</filename> directory.
</para>

<para>
<prompt>root#</prompt> <command>cp ../samba/source/nsswitch/pam_winbind.so /lib/security</command>
</para>

<para>
The <filename>/etc/pam.d/samba</filename> file does not need to be changed. I 
just left this fileas 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>).  
RedHat 7.1 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></para>

<para>
to
</para>

<para><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 <filename>smb.conf</filename> global entry 
<command>template homedir</command>.
</para>

<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:
</para>

<para><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 nearly the 
same way.  It now looks like this:
</para>

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


</sect3>

</sect2>

</sect1>

<sect1>
        <title>Limitations</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 operating system, 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 Name Service Switch and Pluggable Authentication
                Modules 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 mapping 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 been set for Windows NT users.</para></listitem>
        </itemizedlist>
</sect1>


<sect1>
        <title>Conclusion</title>

        <para>The winbind system, through the use of the Name Service 
        Switch, Pluggable Authentication Modules, 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>

</chapter>