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<HTML
><HEAD
><TITLE
>Unified Logons between Windows NT and UNIX using Winbind</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.57"></HEAD
><BODY
CLASS="ARTICLE"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="ARTICLE"
><DIV
CLASS="TITLEPAGE"
><H1
CLASS="TITLE"
><A
NAME="WINBIND"
>Unified Logons between Windows NT and UNIX using Winbind</A
></H1
><HR></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN3"
>Abstract</A
></H1
><P
>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
<I
CLASS="EMPHASIS"
>winbind</I
>, 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.</P
></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="AEN7"
>Introduction</A
></H1
><P
>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.</P
><P
>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.</P
><P
>We divide the unified logon problem for UNIX machines into
three smaller problems:</P
><P
></P
><UL
><LI
><P
>Obtaining Windows NT user and group information
</P
></LI
><LI
><P
>Authenticating Windows NT users
</P
></LI
><LI
><P
>Password changing for Windows NT users
</P
></LI
></UL
><P
>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.</P
></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="AEN20"
>What Winbind Provides</A
></H1
><P
>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.</P
><P
>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.</P
><P
>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.</P
><P
>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.</P
><P
>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).</P
><DIV
CLASS="SECT2"
><HR><H2
CLASS="SECT2"
><A
NAME="AEN27"
>Target Uses</A
></H2
><P
>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.</P
><P
>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.</P
></DIV
></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="AEN31"
>How Winbind Works</A
></H1
><P
>The winbind system is designed around a client/server
architecture. A long running <B
CLASS="COMMAND"
>winbindd</B
> 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.</P
><P
>The technologies used to implement winbind are described
in detail below.</P
><DIV
CLASS="SECT2"
><HR><H2
CLASS="SECT2"
><A
NAME="AEN36"
>Microsoft Remote Procedure Calls</A
></H2
><P
>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.</P
><P
>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.</P
></DIV
><DIV
CLASS="SECT2"
><HR><H2
CLASS="SECT2"
><A
NAME="AEN40"
>Name Service Switch</A
></H2
><P
>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.</P
><P
>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.</P
><P
>The primary control file for NSS is
<TT
CLASS="FILENAME"
>/etc/nsswitch.conf</TT
>.
When a UNIX application makes a request to do a lookup
the C library looks in <TT
CLASS="FILENAME"
>/etc/nsswitch.conf</TT
>
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:</P
><P
><B
CLASS="COMMAND"
>passwd: files example</B
></P
><P
>then the C library will first load a module called
<TT
CLASS="FILENAME"
>/lib/libnss_files.so</TT
> followed by
the module <TT
CLASS="FILENAME"
>/lib/libnss_example.so</TT
>. 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.</P
><P
>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 <TT
CLASS="FILENAME"
>libnss_winbind.so</TT
> in <TT
CLASS="FILENAME"
>/lib/</TT
>
then add "winbind" into <TT
CLASS="FILENAME"
>/etc/nsswitch.conf</TT
> at
the appropriate place. The C library will then call Winbind to
resolve user and group names.</P
></DIV
><DIV
CLASS="SECT2"
><HR><H2
CLASS="SECT2"
><A
NAME="AEN56"
>Pluggable Authentication Modules</A
></H2
><P
>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.</P
><P
>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.
</P
><P
>PAM is configured by providing control files in the directory
<TT
CLASS="FILENAME"
>/etc/pam.d/</TT
> 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 <TT
CLASS="FILENAME"
>pam_winbind.so</TT
> module
is copied to <TT
CLASS="FILENAME"
>/lib/security/</TT
> and the PAM
control files for relevant services are updated to allow
authentication via winbind. See the PAM documentation
for more details.</P
></DIV
><DIV
CLASS="SECT2"
><HR><H2
CLASS="SECT2"
><A
NAME="AEN64"
>User and Group ID Allocation</A
></H2
><P
>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.</P
><P
>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.</P
></DIV
><DIV
CLASS="SECT2"
><HR><H2
CLASS="SECT2"
><A
NAME="AEN68"
>Result Caching</A
></H2
><P
>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.</P
></DIV
></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="AEN71"
>Installation and Configuration</A
></H1
><P
>Many thanks to John Trostel <A
HREF="mailto:jtrostel@snapserver.com"
TARGET="_top"
>jtrostel@snapserver.com</A
>
for providing the HOWTO for this section.</P
><P
>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.</P
><DIV
CLASS="SECT2"
><HR><H2
CLASS="SECT2"
><A
NAME="AEN76"
>Introduction</A
></H2
><P
>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.</P
><P
>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.</P
><P
></P
><UL
><LI
><P
> <I
CLASS="EMPHASIS"
>Why should I to this?</I
>
</P
><P
>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.
</P
></LI
><LI
><P
> <I
CLASS="EMPHASIS"
>Who should be reading this document?</I
>
</P
><P
> 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.
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT2"
><HR><H2
CLASS="SECT2"
><A
NAME="AEN89"
>Requirements</A
></H2
><P
>If you have a samba configuration file that you are currently
using... <I
CLASS="EMPHASIS"
>BACK IT UP!</I
> If your system already uses PAM,
<I
CLASS="EMPHASIS"
>back up the <TT
CLASS="FILENAME"
>/etc/pam.d</TT
> directory
contents!</I
> If you haven't already made a boot disk,
<I
CLASS="EMPHASIS"
>MAKE ONE NOW!</I
></P
><P
>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
<TT
CLASS="FILENAME"
>/etc/pam.d</TT
> back to the original state they were in if
you get frustrated with the way things are going. ;-)</P
><P
>The latest version of SAMBA (version 2.2.2 as of this writing), now
includes a functioning winbindd daemon. Please refer to the
<A
HREF="http://samba.org/"
TARGET="_top"
>main SAMBA web page</A
> or,
better yet, your closest SAMBA mirror site for instructions on
downloading the source code.</P
><P
>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 <TT
CLASS="FILENAME"
>pam-0.74-22</TT
>. For best results, it is helpful to also
install the development packages in <TT
CLASS="FILENAME"
>pam-devel-0.74-22</TT
>.</P
></DIV
><DIV
CLASS="SECT2"
><HR><H2
CLASS="SECT2"
><A
NAME="AEN103"
>Testing Things Out</A
></H2
><P
>Before starting, it is probably best to kill off all the SAMBA
related daemons running on your server. Kill off all <B
CLASS="COMMAND"
>smbd</B
>,
<B
CLASS="COMMAND"
>nmbd</B
>, and <B
CLASS="COMMAND"
>winbindd</B
> 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 <TT
CLASS="FILENAME"
>/etc/pam.d</TT
>
directory structure, including the pam modules are used by pam-aware
services, several pam libraries, and the <TT
CLASS="FILENAME"
>/usr/doc</TT
>
and <TT
CLASS="FILENAME"
>/usr/man</TT
> 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 <TT
CLASS="FILENAME"
>pam-0.74-22</TT
> and
<TT
CLASS="FILENAME"
>pam-devel-0.74-22</TT
> RPMs installed.</P
><DIV
CLASS="SECT3"
><HR><H3
CLASS="SECT3"
><A
NAME="AEN114"
>Configure and compile SAMBA</A
></H3
><P
>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.</P
><P
><PRE
CLASS="PROGRAMLISTING"
><TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>autoconf</B
>
<TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>make clean</B
>
<TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>rm config.cache</B
>
<TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>./configure --with-winbind</B
>
<TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>make</B
>
<TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>make install</B
></PRE
></P
><P
>This will, by default, install SAMBA in <TT
CLASS="FILENAME"
>/usr/local/samba</TT
>.
See the main SAMBA documentation if you want to install SAMBA somewhere else.
It will also build the winbindd executable and libraries. </P
></DIV
><DIV
CLASS="SECT3"
><HR><H3
CLASS="SECT3"
><A
NAME="AEN133"
>Configure <TT
CLASS="FILENAME"
>nsswitch.conf</TT
> and the
winbind libraries</A
></H3
><P
>The libraries needed to run the <B
CLASS="COMMAND"
>winbindd</B
> daemon
through nsswitch need to be copied to their proper locations, so</P
><P
><TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>cp ../samba/source/nsswitch/libnss_winbind.so /lib</B
></P
><P
>I also found it necessary to make the following symbolic link:</P
><P
><TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>ln -s /lib/libnss_winbind.so /lib/libnss_winbind.so.2</B
></P
><P
>Now, as root you need to edit <TT
CLASS="FILENAME"
>/etc/nsswitch.conf</TT
> to
allow user and group entries to be visible from the <B
CLASS="COMMAND"
>winbindd</B
>
daemon. My <TT
CLASS="FILENAME"
>/etc/nsswitch.conf</TT
> file look like
this after editing:</P
><P
><PRE
CLASS="PROGRAMLISTING"
> passwd: files winbind
shadow: files
group: files winbind</PRE
></P
><P
>
The libraries needed by the winbind daemon will be automatically
entered into the <B
CLASS="COMMAND"
>ldconfig</B
> cache the next time
your system reboots, but it
is faster (and you don't need to reboot) if you do it manually:</P
><P
><TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>/sbin/ldconfig -v | grep winbind</B
></P
><P
>This makes <TT
CLASS="FILENAME"
>libnss_winbind</TT
> available to winbindd
and echos back a check to you.</P
></DIV
><DIV
CLASS="SECT3"
><HR><H3
CLASS="SECT3"
><A
NAME="AEN158"
>Configure smb.conf</A
></H3
><P
>Several parameters are needed in the smb.conf file to control
the behavior of <B
CLASS="COMMAND"
>winbindd</B
>. Configure
<TT
CLASS="FILENAME"
>smb.conf</TT
> These are described in more detail in
the <A
HREF="winbindd.8.html"
TARGET="_top"
>winbindd(8)</A
> man page. My
<TT
CLASS="FILENAME"
>smb.conf</TT
> file was modified to
include the following entries in the [global] section:</P
><P
><PRE
CLASS="PROGRAMLISTING"
>[global]
<...>
# separate domain and username with '+', like DOMAIN+username
<A
HREF="winbindd.8.html#WINBINDSEPARATOR"
TARGET="_top"
>winbind separator</A
> = +
# use uids from 10000 to 20000 for domain users
<A
HREF="winbindd.8.html#WINBINDUID"
TARGET="_top"
>winbind uid</A
> = 10000-20000
# use gids from 10000 to 20000 for domain groups
<A
HREF="winbindd.8.html#WINBINDGID"
TARGET="_top"
>winbind gid</A
> = 10000-20000
# allow enumeration of winbind users and groups
<A
HREF="winbindd.8.html#WINBINDENUMUSERS"
TARGET="_top"
>winbind enum users</A
> = yes
<A
HREF="winbindd.8.html#WINBINDENUMGROUP"
TARGET="_top"
>winbind enum groups</A
> = yes
# give winbind users a real shell (only needed if they have telnet access)
<A
HREF="winbindd.8.html#TEMPLATEHOMEDIR"
TARGET="_top"
>template homedir</A
> = /home/winnt/%D/%U
<A
HREF="winbindd.8.html#TEMPLATESHELL"
TARGET="_top"
>template shell</A
> = /bin/bash</PRE
></P
></DIV
><DIV
CLASS="SECT3"
><HR><H3
CLASS="SECT3"
><A
NAME="AEN174"
>Join the SAMBA server to the PDC domain</A
></H3
><P
>Enter the following command to make the SAMBA server join the
PDC domain, where <TT
CLASS="REPLACEABLE"
><I
>DOMAIN</I
></TT
> is the name of
your Windows domain and <TT
CLASS="REPLACEABLE"
><I
>Administrator</I
></TT
> is
a domain user who has administrative privileges in the domain.</P
><P
><TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>/usr/local/samba/bin/net rpc join -s PDC -U Administrator</B
></P
><P
>The proper response to the command should be: "Joined the domain
<TT
CLASS="REPLACEABLE"
><I
>DOMAIN</I
></TT
>" where <TT
CLASS="REPLACEABLE"
><I
>DOMAIN</I
></TT
>
is your DOMAIN name.</P
></DIV
><DIV
CLASS="SECT3"
><HR><H3
CLASS="SECT3"
><A
NAME="AEN185"
>Start up the winbindd daemon and test it!</A
></H3
><P
>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:</P
><P
><TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>/usr/local/samba/bin/winbindd</B
></P
><P
>I'm always paranoid and like to make sure the daemon
is really running...</P
><P
><TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>ps -ae | grep winbindd</B
></P
><P
>This command should produce output like this, if the daemon is running</P
><P
>3025 ? 00:00:00 winbindd</P
><P
>Now... for the real test, try to get some information about the
users on your PDC</P
><P
><TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>/usr/local/samba/bin/wbinfo -u</B
></P
><P
>
This should echo back a list of users on your Windows users on
your PDC. For example, I get the following response:</P
><P
><PRE
CLASS="PROGRAMLISTING"
>CEO+Administrator
CEO+burdell
CEO+Guest
CEO+jt-ad
CEO+krbtgt
CEO+TsInternetUser</PRE
></P
><P
>Obviously, I have named my domain 'CEO' and my <TT
CLASS="PARAMETER"
><I
>winbind
separator</I
></TT
> is '+'.</P
><P
>You can do the same sort of thing to get group information from
the PDC:</P
><P
><PRE
CLASS="PROGRAMLISTING"
><TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>/usr/local/samba/bin/wbinfo -g</B
>
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</PRE
></P
><P
>The function 'getent' can now be used to get unified
lists of both local and PDC users and groups.
Try the following command:</P
><P
><TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>getent passwd</B
></P
><P
>You should get a list that looks like your <TT
CLASS="FILENAME"
>/etc/passwd</TT
>
list followed by the domain users with their new uids, gids, home
directories and default shells.</P
><P
>The same thing can be done for groups with the command</P
><P
><TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>getent group</B
></P
></DIV
><DIV
CLASS="SECT3"
><HR><H3
CLASS="SECT3"
><A
NAME="AEN221"
>Fix the <TT
CLASS="FILENAME"
>/etc/rc.d/init.d/smb</TT
> startup files</A
></H3
><P
>The <B
CLASS="COMMAND"
>winbindd</B
> daemon needs to start up after the
<B
CLASS="COMMAND"
>smbd</B
> and <B
CLASS="COMMAND"
>nmbd</B
> daemons are running.
To accomplish this task, you need to modify the <TT
CLASS="FILENAME"
>/etc/init.d/smb</TT
>
script to add commands to invoke this daemon in the proper sequence. My
<TT
CLASS="FILENAME"
>/etc/init.d/smb</TT
> file starts up <B
CLASS="COMMAND"
>smbd</B
>,
<B
CLASS="COMMAND"
>nmbd</B
>, and <B
CLASS="COMMAND"
>winbindd</B
> from the
<TT
CLASS="FILENAME"
>/usr/local/samba/bin</TT
> directory directly. The 'start'
function in the script looks like this:</P
><P
><PRE
CLASS="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
}</PRE
></P
><P
>The 'stop' function has a corresponding entry to shut down the
services and look s like this:</P
><P
><PRE
CLASS="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
}</PRE
></P
><P
>If you restart the <B
CLASS="COMMAND"
>smbd</B
>, <B
CLASS="COMMAND"
>nmbd</B
>,
and <B
CLASS="COMMAND"
>winbindd</B
> 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.</P
></DIV
><DIV
CLASS="SECT3"
><HR><H3
CLASS="SECT3"
><A
NAME="AEN243"
>Configure Winbind and PAM</A
></H3
><P
>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
<TT
CLASS="FILENAME"
>/etc/pam.d</TT
> files? If not, do it now.)</P
><P
>You will need a pam module to use winbindd with these other services. This
module will be compiled in the <TT
CLASS="FILENAME"
>../source/nsswitch</TT
> directory
by invoking the command</P
><P
><TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>make nsswitch/pam_winbind.so</B
></P
><P
>from the <TT
CLASS="FILENAME"
>../source</TT
> directory. The
<TT
CLASS="FILENAME"
>pam_winbind.so</TT
> file should be copied to the location of
your other pam security modules. On my RedHat system, this was the
<TT
CLASS="FILENAME"
>/lib/security</TT
> directory.</P
><P
><TT
CLASS="PROMPT"
>root#</TT
> <B
CLASS="COMMAND"
>cp ../samba/source/nsswitch/pam_winbind.so /lib/security</B
></P
><P
>The <TT
CLASS="FILENAME"
>/etc/pam.d/samba</TT
> file does not need to be changed. I
just left this fileas it was:</P
><P
><PRE
CLASS="PROGRAMLISTING"
>auth required /lib/security/pam_stack.so service=system-auth
account required /lib/security/pam_stack.so service=system-auth</PRE
></P
><P
>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
<TT
CLASS="FILENAME"
>/etc/xinetd.d</TT
> (or <TT
CLASS="FILENAME"
>/etc/inetd.conf</TT
>).
RedHat 7.1 uses the new xinetd.d structure, in this case you need
to change the lines in <TT
CLASS="FILENAME"
>/etc/xinetd.d/telnet</TT
>
and <TT
CLASS="FILENAME"
>/etc/xinetd.d/wu-ftp</TT
> from </P
><P
><PRE
CLASS="PROGRAMLISTING"
>enable = no</PRE
></P
><P
>to</P
><P
><PRE
CLASS="PROGRAMLISTING"
>enable = yes</PRE
></P
><P
>
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 <TT
CLASS="FILENAME"
>smb.conf</TT
> global entry
<B
CLASS="COMMAND"
>template homedir</B
>.</P
><P
>The <TT
CLASS="FILENAME"
>/etc/pam.d/ftp</TT
> file can be changed
to allow winbind ftp access in a manner similar to the
samba file. My <TT
CLASS="FILENAME"
>/etc/pam.d/ftp</TT
> file was
changed to look like this:</P
><P
><PRE
CLASS="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</PRE
></P
><P
>The <TT
CLASS="FILENAME"
>/etc/pam.d/login</TT
> file can be changed nearly the
same way. It now looks like this:</P
><P
><PRE
CLASS="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</PRE
></P
><P
>In this case, I added the <B
CLASS="COMMAND"
>auth sufficient /lib/security/pam_winbind.so</B
>
lines as before, but also added the <B
CLASS="COMMAND"
>required pam_securetty.so</B
>
above it, to disallow root logins over the network. I also added a
<B
CLASS="COMMAND"
>sufficient /lib/security/pam_unix.so use_first_pass</B
>
line after the <B
CLASS="COMMAND"
>winbind.so</B
> line to get rid of annoying
double prompts for passwords.</P
></DIV
></DIV
></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="AEN290"
>Limitations</A
></H1
><P
>Winbind has a number of limitations in its current
released version that we hope to overcome in future
releases:</P
><P
></P
><UL
><LI
><P
>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.</P
></LI
><LI
><P
>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.</P
></LI
><LI
><P
>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.</P
></LI
></UL
></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="AEN300"
>Conclusion</A
></H1
><P
>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.</P
></DIV
></DIV
></BODY
></HTML
>
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