sin/samba-mirror
1
0
Fork 0
mirror of https://github.com/samba-team/samba.git synced 2025-01-20 14:03:59 +03:00
Code
samba-mirror/docs/guide/Chap09-AddingUNIXClients.xml
John Terpstra ea45ec5e08 Adding clarification of KRB support for SuSE and Red Hat Linux 
(This used to be commit db0387aa5ab0bd5db4ce3a3cdfe30437e2a215df)
2008-04-23 08:45:49 -05:00

2538 lines
94 KiB
XML
Raw Blame History

<?xml version="1.0" encoding="iso-8859-1"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
<!-- Stuff for xincludes -->
<!ENTITY % xinclude SYSTEM "../entities/xinclude.dtd">
%xinclude;
<!-- entities files to use -->
<!ENTITY % global_entities SYSTEM '../entities/global.entities'>
%global_entities;
]>
<chapter id="unixclients">
<title>Adding UNIX/LINUX Servers and Clients</title>
<para><indexterm>
<primary>Open Magazine</primary>
</indexterm><indexterm>
<primary>survey</primary>
</indexterm>
The most frequently discussed Samba subjects over the past two years have focused around Domain Control and printing.
It is well known that Samba is a file and print server. A recent survey conducted by Open Magazine found
that of all respondents: 97% use Samba for file and print services, and 68% use Samba for Domain Control. See the
<ulink url="http://www.open-mag.com/cgi-bin/opencgi/surveys/survey.cgi?survey_name=samba">Open-Mag</ulink>
Web site for current information. The survey results as found on January 14, 2004, as shown in
<link linkend="ch09openmag"/>.
</para>
<figure id="ch09openmag">
<title>Open Magazine Samba Survey</title>
<mediaobject>
<imageobject role="latex">
<imagedata fileref="guide/images/openmag.png" scale="60" scalefit="1"/>
</imageobject>
<imageobject>
<imagedata fileref="guide/images/openmag.png" scale="60" scalefit="1"/>
</imageobject>
</mediaobject>
</figure>
<para>
While Domain Control is an exciting subject, basic file and print sharing remains the staple bread-and-butter
function that Samba provides. Yet this book may give the appearance of having focused too much on more
exciting aspects of Samba deployment. This chapter directs your attention to provide important information on
the addition of Samba servers into your present Windows network &smbmdash; whatever the controlling technology
may be. So let's get back to Abmas and our good friends Bob Jordan and company.
</para>
<sect1>
<title>Introduction</title>
<para><indexterm>
<primary>Linux desktop</primary>
</indexterm><indexterm>
<primary>Domain Member</primary>
<secondary>server</secondary>
</indexterm>
Bob Jordan looks back over the achievements of the past year or two. Daily events are rather straightforward
with not too many distractions or problems. Bob, your team is doing well, but a number of employees
are asking for Linux desktop systems. Your network has grown and demands additional Domain Member servers. Let's
get on with this; Christine and Stan are ready to go.
</para>
<para><indexterm>
<primary>Domain Member</primary>
<secondary>desktop</secondary>
</indexterm>
Stan Soroka is firmly in control of the Department of the Future, while Christine is enjoying a stable and
predictable network environment. It is time to add more servers and to add Linux desktops. It is
time to meet the demands of future growth and endure trial by fire. Go on, walk the steps
with Stan and Company.
</para>
<sect2>
<title>Assignment Tasks</title>
<para><indexterm>
<primary>Active Directory</primary>
</indexterm>
You must now add UNIX/Linux Domain Member servers to your network. You have a friend who has a Windows 2003
Active Directory Domain network who wants to add a Samba/Linux server and has asked Christine to help him
out. Your real objective is to help Christine to see more of the way the Microsoft world lives and use
her help to get validation that Samba really does live up to expectations.
</para>
<para>
Over the past six months, you have hired several new staff who want Linux on their desktops. You must integrate
these systems to make sure that Abmas is not building islands of technology. You ask Christine to
do likewise at Swodniw Biz NL (your friend's company) to help them to evaluate a Linux desktop. You want to make
the right decision, don't you?
</para>
</sect2>
</sect1>
<sect1>
<title>Dissection and Discussion</title>
<para><indexterm>
<primary>winbind</primary>
</indexterm>
Recent Samba mailing list activity is witness to how many sites are using winbind. Some have no trouble
at all with it, yet to others the problems seem insurmountable. Periodically there are complaints concerning
an inability to achieve identical user and group IDs between Windows and UNIX environments.
</para>
<para>
You provide step-by-step implementations of the various tools that can be used for identity
resolution. You also provide working examples of solutions for integrated authentication for
both UNIX/Linux and Windows environments.
</para>
<sect2>
<title>Technical Issues</title>
<para>
One of the great challenges we face when people ask us, <quote>What is the best way to solve
this problem?</quote> is to get beyond the facts so we can not only clearly comprehend
the immediate technical problem, but also understand how needs may change.
</para>
<para><indexterm>
<primary>integrate</primary>
</indexterm>
There are a few facts we should note when dealing with the question of how best to
integrate UNIX/Linux clients and servers into a Windows networking environment:
</para>
<itemizedlist>
<listitem><para><indexterm>
<primary>Domain Controller</primary>
</indexterm><indexterm>
<primary>authoritative</primary>
</indexterm><indexterm>
<primary>accounts</primary>
<secondary>authoritative</secondary>
</indexterm><indexterm>
<primary>PDC</primary>
</indexterm><indexterm>
<primary>BDC</primary>
</indexterm>
A Domain Controller (PDC or BDC) is always authoritative for all accounts in its Domain.
This means that a BDC must (of necessity) be able to resolve all account UIDs and GIDs
to the same values that the PDC resolved them to.
</para></listitem>
<listitem><para><indexterm>
<primary>local accounts</primary>
</indexterm><indexterm>
<primary>Domain Member</primary>
<secondary>authoritative</secondary>
<tertiary>local accounts</tertiary>
</indexterm><indexterm>
<primary>Domain accounts</primary>
</indexterm><indexterm>
<primary>winbindd</primary>
</indexterm>
A Domain Member can be authoritative for local accounts, but is never authoritative for
Domain accounts. If a user is accessing a Domain Member server and that user's account
is not known locally, the Domain Member server must resolve the identity of that user
from the Domain in which that user's account resides. It must then map that ID to a
UID/GID pair that it can use locally. This is handled by <command>winbindd</command>.
</para></listitem>
<listitem><para>
Samba, when running on a Domain Member server, can resolve user identities from a
number of sources:
<itemizedlist>
<listitem><para><indexterm>
<primary>getpwnam</primary>
</indexterm><indexterm>
<primary>getgrnam</primary>
</indexterm><indexterm>
<primary>NSS</primary>
</indexterm><indexterm>
<primary>LDAP</primary>
</indexterm><indexterm>
<primary>NIS</primary>
</indexterm>
By executing a system <command>getpwnam()</command> or <command>getgrnam()</command> call.
On systems that support it, this utilizes the name service switch (NSS) facility to
resolve names according to the configuration of the <filename>/etc/nsswitch.conf</filename>
file. NSS can be configured to use LDAP, winbind, NIS, or local files.
</para></listitem>
<listitem><para><indexterm>
<primary>passdb backend</primary>
</indexterm><indexterm>
<primary>PADL</primary>
</indexterm><indexterm>
<primary>nss_ldap</primary>
</indexterm>
Performing, via NSS, a direct LDAP search (where an LDAP passdb backend has been configured).
This requires the use of the PADL nss_ldap tool (or equivalent).
</para></listitem>
<listitem><para><indexterm>
<primary>winbindd</primary>
</indexterm><indexterm>
<primary>SID</primary>
</indexterm><indexterm>
<primary>winbindd_idmap.tdb</primary>
</indexterm><indexterm>
<primary>winbindd_cache.tdb</primary>
</indexterm>
Directly by querying <command>winbindd</command>. The <command>winbindd</command>
contact a Domain Controller to attempt to resolve the identity of the user or group. It
receives the Windows networking security identifier (SID) for that appropriate
account and then allocates a local UID or GID from the range of available IDs and
creates an entry in its <filename>winbindd_idmap.tdb</filename> and
<filename>winbindd_cache.tdb</filename> files.
</para>
<para><indexterm>
<primary>idmap backend</primary>
</indexterm><indexterm>
<primary>mapping</primary>
</indexterm>
If the parameter
<smbconfoption><name>idmap backend</name><value>ldap:ldap://myserver.domain</value></smbconfoption>
was specified and the LDAP server has been configured with a container in which it may
store the IDMAP entries, all Domain Members may share a common mapping.
</para></listitem>
</itemizedlist>
</para>
<para>
Irrespective of how &smb.conf; is configured, winbind creates and caches a local copy of
the ID mapping database. It uses the <filename>winbindd_idmap.tdb</filename>, and
<filename>winbindd_cache.tdb</filename> files to do this.
</para>
<para>
Which of the above resolver methods is chosen is determined by the way that Samba is configured
in the &smb.conf; file. Some of the configuration options are rather less than obvious to the
casual user.
</para></listitem>
<listitem><para><indexterm>
<primary>winbind enable local accounts</primary>
</indexterm><indexterm>
<primary>Domain Member</primary>
<secondary>servers</secondary>
</indexterm><indexterm>
<primary>Domain Controllers</primary>
</indexterm>
If you wish to make use of accounts (users and/or groups) that are local to (i.e., capable
of being resolved using) the name service switch (NSS) facility, it is imperative to use the
<smbconfoption><name>winbind enable local accounts</name><value>Yes</value></smbconfoption>
in the &smb.conf; file. This parameter specifically applies only to Domain Controllers,
not to Domain Member servers.
</para></listitem>
</itemizedlist>
<para><indexterm>
<primary>Posix accounts</primary>
</indexterm><indexterm>
<primary>Samba accounts</primary>
</indexterm><indexterm>
<primary>LDAP</primary>
</indexterm>
For many administrators, it should be plain that the use of an LDAP-based repository for all network
accounts (both for Posix accounts as well as for Samba accounts) provides the most elegant and
controllable facility. You eventually appreciate the decision to use LDAP.
</para>
<para><indexterm>
<primary>nss_ldap</primary>
</indexterm><indexterm>
<primary>identifiers</primary>
</indexterm><indexterm>
<primary>resolve</primary>
</indexterm>
If your network account information resides in an LDAP repository, you should use it ahead of any
alternative method. This means that if it is humanly possible to use the <command>nss_ldap</command>
tools to resolve UNIX account UIDs/GIDs via LDAP, this is the preferred solution, as it provides
a more readily controllable method for asserting the exact same user and group identifiers
throughout the network.
</para>
<para><indexterm>
<primary>Domain Member</primary>
<secondary>server</secondary>
</indexterm><indexterm>
<primary>winbind trusted domains only</primary>
</indexterm><indexterm>
<primary>getpwnam</primary>
</indexterm><indexterm>
<primary>smbd</primary>
</indexterm><indexterm>
<primary>Trusted Domains</primary>
</indexterm><indexterm>
<primary>External Domains</primary>
</indexterm>
In the situation where UNIX accounts are held on the Domain Member server itself, the only effective
way to use them involves the &smb.conf; entry
<smbconfoption><name>winbind trusted domains only</name><value>Yes</value></smbconfoption>. This forces
Samba (<command>smbd</command>) to perform a <command>getpwnam()</command> system call that can
then be controlled via <filename>/etc/nsswitch.conf</filename> file settings. The use of this parameter
disables the use of Samba with Trusted Domains (i.e., External Domains).
</para>
<para><indexterm>
<primary>appliance mode</primary>
</indexterm><indexterm>
<primary>Domain Member</primary>
<secondary>server</secondary>
</indexterm><indexterm>
<primary>winbindd</primary>
</indexterm><indexterm>
<primary>automatically allocate</primary>
</indexterm>
Winbind can be used to create an appliance mode Domain Member server. In this capacity, <command>winbindd</command>
is configured to automatically allocate UIDs/GIDs from numeric ranges set in the &smb.conf; file. The allocation
is made for all accounts that connect to that Domain Member server, whether within its own Domain or from
Trusted Domains. If not stored in an LDAP backend, each Domain Member maintains its own unique mapping database.
This means that it is almost certain that a given user who accesses two Domain Member servers does not have the
same UID/GID on both servers &smbmdash; however, this is transparent to the Windows network user. This data
is stored in the <filename>winbindd_idmap.tdb</filename> and <filename>winbindd_cache.tdb</filename> files.
</para>
<para><indexterm>
<primary>mapping</primary>
</indexterm>
The use of an LDAP backend for the Winbind IDMAP facility permits Windows Domain security identifiers (SIDs)
mappings to UIDs/GIDs to be stored centrally. The result is a consistent mapping across all Domain Member
servers so configured. This solves one of the major headaches for network administrators who need to copy
files between/across network file servers.
</para>
</sect2>
<sect2>
<title>Political Issues</title>
<para><indexterm>
<primary>OpenLDAP</primary>
</indexterm><indexterm>
<primary>NIS</primary>
</indexterm><indexterm>
<primary>yellow pages</primary>
<see>NIS</see>
</indexterm><indexterm>
<primary>identity management</primary>
</indexterm>
One of the most fierce conflicts recently being waged is one of resistance to the adoption of LDAP, in
particular OpenLDAP, as a replacement for UNIX NIS (previously called Yellow Pages). Let's face it, LDAP
is different and requires a new approach to the need for a better identity management solution. The more
you work with LDAP, the more its power and flexibility emerges from its dark, cavernous chasm.
</para>
<para>
LDAP is a most suitable solution for heterogenous environments. If you need crypto, add Kerberos.
The reason these are preferable is because they are heterogenous. Windows solutions of this sort are NOT
heterogenous by design. This is fundamental &smbmdash; it isn't religious or political. This also doesn't say that
you can't use Windows Active Directory in a heterogenous environment &smbmdash; it can be done, it just requires
commercial integration products &smbmdash; it's just not what Active Directory was designed for.
</para>
<para><indexterm>
<primary>directory</primary>
</indexterm><indexterm>
<primary>management</primary>
</indexterm>
A number of long-term UNIX devotees have recently commented in various communications that the Samba Team
is the first application group to almost force network administrators to use LDAP. It should be pointed
out that we resisted this as long as we could. It is not out of laziness or out of malice that LDAP has
finally emerged as the preferred identity management backend for Samba. We recommend LDAP for your total
organizational directory needs.
</para>
</sect2>
</sect1>
<sect1>
<title>Implementation</title>
<para><indexterm>
<primary>Domain Member</primary>
<secondary>server</secondary>
</indexterm><indexterm>
<primary>Domain Member</primary>
<secondary>client</secondary>
</indexterm><indexterm>
<primary>Domain Controller</primary>
</indexterm>
The Domain Member server and the Domain Member client are at the center of focus in this chapter.
Configuration of Samba-3 Domain Controller has been covered in earlier chapters, so if your
interest is in Domain Controller configuration, you will not find that here. You will find good
oil that helps you to add Domain Member servers and clients.
</para>
<para><indexterm>
<primary>Domain Member</primary>
<secondary>workstations</secondary>
</indexterm>
In practice, Domain Member servers and Domain Member workstations are very different entities, but in
terms of technology they share similar core infrastructure. A technologist would argue that servers
and workstations are identical. Many users would argue otherwise, given that in a well-disciplined
environment a workstation (client) is a device from which a user creates documents and files that
are located on servers. A workstation is frequently viewed as a disposable (easy to replace) item,
but a server is viewed as a core component of the business.
</para>
<para><indexterm>
<primary>workstation</primary>
</indexterm>
One can look at this another way. If a workstation breaks down, one user is affected, but if a
server breaks down, hundreds of users may not be able to work. The services that a workstation
must provide are document and file production oriented; a server provides information storage
and is distribution oriented.
</para>
<para><indexterm>
<primary>authentication process</primary>
</indexterm><indexterm>
<primary>logon process</primary>
</indexterm><indexterm>
<primary>user identities</primary>
</indexterm>
<emphasis>Why is this important?</emphasis> &smbmdash; For starters, we must identify what
components of the operating system and its environment must be configured. Also, it is necessary
to recognize where the interdependencies between the various services to be used are.
In particular, it is important to understand the operation of each critical part of the
authentication process, the logon process, and how user identities get resolved and applied
within the operating system and applications (like Samba) that depend on this and may
actually contribute to it.
</para>
<para>
So, while here we demonstrate how to implement the technology. It is done within a context of
what type of service need must be fulfilled.
</para>
<sect2 id="sdcsdmldap">
<title>Samba Domain with Samba Domain Member Server &smbmdash; Using LDAP</title>
<para><indexterm>
<primary>ldapsam</primary>
</indexterm><indexterm>
<primary>ldapsam backend</primary>
</indexterm><indexterm>
<primary>IDMAP</primary>
</indexterm><indexterm>
<primary>mapping</primary>
<secondary>consistent</secondary>
</indexterm><indexterm>
<primary>winbindd</primary>
</indexterm><indexterm>
<primary>foreign SID</primary>
</indexterm>
In this example, it is assumed that you have Samba PDC/BDC servers. This means you are using
an LDAP ldapsam backend. In this example, we are adding to the LDAP backend database (directory)
containers for use by the IDMAP facility. This makes it possible to have globally consistent
mapping of SIDs to/from UIDs/GIDs. This means that you are running <command>winbindd</command>
as part of your configuration. The primary purpose of running <command>winbindd</command> (within
this operational context) is to permit mapping of foreign SIDs (those not originating from our
own Domain). Foreign SIDs can come from any external Domain or from Windows clients that do not
belong to a Domain.
</para>
<para><indexterm>
<primary>winbindd</primary>
</indexterm><indexterm>
<primary>getpwnam</primary>
</indexterm><indexterm>
<primary>NSS</primary>
</indexterm>
If your installation is accessed only from clients that are members of your own domain, then
it is not necessary to run <command>winbindd</command> as long as all users can be resolved
locally via the <command>getpwnam()</command> system call. On NSS-enabled systems, this condition
is met by having:
</para>
<itemizedlist>
<listitem><para><indexterm>
<primary>/etc/passwd</primary>
</indexterm><indexterm>
<primary>/etc/group</primary>
</indexterm>
All accounts in <filename>/etc/passwd</filename> or in <filename>/etc/group</filename>.
</para></listitem>
<listitem><para><indexterm>
<primary>NSS</primary>
</indexterm><indexterm>
<primary>compat</primary>
</indexterm><indexterm>
<primary>compat</primary>
</indexterm><indexterm>
<primary>ldap</primary>
</indexterm><indexterm>
<primary>nis</primary>
</indexterm><indexterm>
<primary>nisplus</primary>
</indexterm><indexterm>
<primary>hesoid</primary>
</indexterm><indexterm>
<primary>ldap</primary>
</indexterm><indexterm>
<primary>nss_ldap</primary>
</indexterm><indexterm>
<primary>PADL Software</primary>
</indexterm>
Resolution via NSS. On NSS-enabled systems, there is usually a facility to resolve IDs
via multiple methods. The methods typically include: <command>files, compat, db, ldap,
nis, nisplus, hesoid.</command> When correctly installed, Samba adds to this list
the <command>winbindd</command> facility. The ldap facility is frequently the nss_ldap
tool provided by PADL Software.
</para></listitem>
</itemizedlist>
<para><indexterm>
<primary>Identity resolution</primary>
</indexterm>
The diagram in <link linkend="ch9-sambadc"/> demonstrates the relationship of samba and system
components that are involved in the Identity resolution process where Samba is used as a Domain
Member server within a Samba Domain Control network.
</para>
<figure id="ch9-sambadc">
<title>Samba Domain: Samba Member Server</title>
<mediaobject>
<imageobject role="latex">
<imagedata fileref="guide/images/chap9-SambaDC.png" scale="75" scalefit="1"/>
</imageobject>
<imageobject>
<imagedata fileref="guide/images/chap9-SambaDC.png" scale="75" scalefit="1"/>
</imageobject>
</mediaobject>
</figure>
<para><indexterm>
<primary>IDMAP</primary>
</indexterm><indexterm>
<primary>foreign</primary>
</indexterm>
In this example configuration, Samba will directly search the LDAP-based passwd backend ldapsam
to obtain authentication and user identity information. The IDMAP information is stored in the LDAP
backend so that it can be shared by all Domain Member servers so that every user will have a
consistent UID and GID across all of them. The IDMAP facility will be used for all foreign
(i.e., not having the same SID as the Domain it is a member of) Domains. The configuration of
NSS will ensure that all unix processes will obtain a consistent UID/GID.
</para>
<para>
The instructions given here apply to the Samba environment as shown in Chapters 6 and 7.
If your network does not have an LDAP slave server (i.e., Chapter 6 configuration), you
must change the target LDAP server from <constant>lapdc</constant> to <constant>massive.</constant>
</para>
<procedure>
<title>Configuration of LDAP-Based Identity Resolution</title>
<step><para>
Create the &smb.conf; file as shown in <link linkend="ch9-sdmsdc"/>. Locate
this file in the directory <filename>/etc/samba</filename>.
</para></step>
<step><para><indexterm>
<primary>ldap.conf</primary>
</indexterm>
Configure the file that will be used by <constant>nss_ldap</constant> to
locate and communicate with the LDAP server. This file is called <filename>ldap.conf</filename>.
If your implementation of <constant>nss_ldap</constant> is consistent with
the defaults suggested by PADL (the authors), it will be located in the
<filename>/etc</filename> directory. On some systems, the default location is
the <filename>/etc/openldap</filename> directory. Change the parameters inside
the file that is located on your OS so it matches <link linkend="ch9-sdmlcnf"/>.
To find the correct location of this file, you can obtain this from the
library that will be used by executing the following:
<screen>
&rootprompt; strings /lib/libnss_ldap* | grep ldap.conf
/etc/ldap.conf
</screen>
</para></step>
<step><para>
Configure the name service switch (NSS) control file so it matches the one shown
in <link linkend="ch9-sdmnss"/>.
</para></step>
<step><para><indexterm>
<primary>Identity resolution</primary>
</indexterm><indexterm>
<primary>getent</primary>
</indexterm>
Before proceeding to configure Samba, validate the operation of the NSS Identity
resolution via LDAP by executing:
<screen>
&rootprompt; getent passwd
...
root:x:0:512:Netbios Domain Administrator:/root:/bin/false
nobody:x:999:514:nobody:/dev/null:/bin/false
bobj:x:1000:513:Robert Jordan:/home/bobj:/bin/bash
stans:x:1001:513:Stanley Soroka:/home/stans:/bin/bash
chrisr:x:1002:513:Christine Roberson:/home/chrisr:/bin/bash
maryv:x:1003:513:Mary Vortexis:/home/maryv:/bin/bash
jht:x:1004:513:John H Terpstra:/home/jht:/bin/bash
bldg1$:x:1006:553:bldg1$:/dev/null:/bin/false
temptation$:x:1009:553:temptation$:/dev/null:/bin/false
vaioboss$:x:1005:553:vaioboss$:/dev/null:/bin/false
fran$:x:1008:553:fran$:/dev/null:/bin/false
josephj:x:1007:513:Joseph James:/home/josephj:/bin/bash
</screen>
You should notice the location of the users' home directories. First, make certain that
the home directories exist on the Domain Member server; otherwise, the home directory
share is not available. The home directories could be mounted off a domain controller
using NFS, or by any other suitable means. Second, the absence of the Domain name in the
home directory path is indicative that Identity resolution is not being done via Winbind.
<screen>
&rootprompt; getent group
...
Domain Admins:x:512:root,jht
Domain Users:x:513:bobj,stans,chrisr,maryv,jht,josephj
Domain Guests:x:514:
Accounts:x:1000:
Finances:x:1001:
PIOps:x:1002:
sammy:x:4321:
</screen>
<indexterm>
<primary>secondary group</primary>
</indexterm><indexterm>
<primary>primary group</primary>
</indexterm><indexterm>
<primary>group membership</primary>
</indexterm>
This shows that all is working as it should. Notice that in the LDAP database
the users primary and secondary group memberships are identical. It is not
necessary to add secondary group memberships (in the group database) if the
user is already a member via primary group membership in the password database.
When using winbind, it is in fact undesirable to do this as it results in
doubling up of group memberships and may break winbind under certain conditions.
</para></step>
<step><para><indexterm>
<primary>slapcat</primary>
</indexterm>
The LDAP directory must have a container object for IDMAP data. There are several ways you can
check that your LDAP database is able to receive IDMAP information. One of the simplest is to
execute:
<screen>
&rootprompt; slapcat | grep -i idmap
dn: ou=Idmap,dc=abmas,dc=biz
ou: idmap
</screen>
<indexterm>
<primary>ldapadd</primary>
</indexterm>
If the execution of this command does not return IDMAP entries, you need to create an LDIF
template file (see <link linkend="ch9-ldifadd"/>). You can add the required entries using the following command:
<screen>
&rootprompt; ldapadd -x -D "cn=Manager,dc=abmas,dc=biz" \
-w not24get &lt; /etc/openldap/idmap.LDIF
</screen>
Samba automatically populates this LDAP directory container when it needs to.
</para></step>
<step><para><indexterm>
<primary>net</primary>
<secondary>rpc</secondary>
<tertiary>join</tertiary>
</indexterm><indexterm>
<primary>Domain join</primary>
</indexterm>
The system is ready to join the Domain. Execute the following:
<screen>
net rpc join -U root%not24et
Joined domain MEGANET2.
</screen>
This indicates that the Domain join succeeded.
</para></step>
<step><para>
You may now start Samba in the usual manner and your Samba Domain Member server
is ready for use. Just add shares as required.
</para></step>
</procedure>
<smbconfexample id="ch9-sdmsdc">
<title>Samba Domain Member in Samba Domain Control Context &smbmdash; &smb.conf; File</title>
<smbconfcomment>Global parameters</smbconfcomment>
<smbconfsection>[global]</smbconfsection>
<smbconfoption><name>unix charset</name><value>LOCALE</value></smbconfoption>
<smbconfoption><name>workgroup</name><value>MEGANET2</value></smbconfoption>
<smbconfoption><name>security</name><value>DOMAIN</value></smbconfoption>
<smbconfoption><name>username map</name><value>/etc/samba/smbusers</value></smbconfoption>
<smbconfoption><name>log level</name><value>10</value></smbconfoption>
<smbconfoption><name>syslog</name><value>0</value></smbconfoption>
<smbconfoption><name>log file</name><value>/var/log/samba/%m</value></smbconfoption>
<smbconfoption><name>max log size</name><value>50</value></smbconfoption>
<smbconfoption><name>smb ports</name><value>139 445</value></smbconfoption>
<smbconfoption><name>name resolve order</name><value>wins bcast hosts</value></smbconfoption>
<smbconfoption><name>printcap name</name><value>CUPS</value></smbconfoption>
<smbconfoption><name>wins server</name><value>192.168.2.1</value></smbconfoption>
<smbconfoption><name>ldap suffix</name><value>dc=abmas,dc=biz</value></smbconfoption>
<smbconfoption><name>ldap machine suffix</name><value>ou=People</value></smbconfoption>
<smbconfoption><name>ldap user suffix</name><value>ou=People</value></smbconfoption>
<smbconfoption><name>ldap group suffix</name><value>ou=Groups</value></smbconfoption>
<smbconfoption><name>ldap idmap suffix</name><value>ou=Idmap</value></smbconfoption>
<smbconfoption><name>ldap admin dn</name><value>cn=Manager,dc=abmas,dc=biz</value></smbconfoption>
<smbconfoption><name>idmap backend</name><value>ldap:ldap://lapdc.abmas.biz</value></smbconfoption>
<smbconfoption><name>idmap uid</name><value>10000-20000</value></smbconfoption>
<smbconfoption><name>idmap gid</name><value>10000-20000</value></smbconfoption>
<smbconfoption><name>winbind trusted domains only</name><value>Yes</value></smbconfoption>
<smbconfoption><name>printer admin</name><value>root</value></smbconfoption>
<smbconfoption><name>printing</name><value>cups</value></smbconfoption>
<smbconfsection>[homes]</smbconfsection>
<smbconfoption><name>comment</name><value>Home Directories</value></smbconfoption>
<smbconfoption><name>valid users</name><value>%S</value></smbconfoption>
<smbconfoption><name>read only</name><value>No</value></smbconfoption>
<smbconfoption><name>browseable</name><value>No</value></smbconfoption>
<smbconfsection>[printers]</smbconfsection>
<smbconfoption><name>comment</name><value>SMB Print Spool</value></smbconfoption>
<smbconfoption><name>path</name><value>/var/spool/samba</value></smbconfoption>
<smbconfoption><name>guest ok</name><value>Yes</value></smbconfoption>
<smbconfoption><name>printable</name><value>Yes</value></smbconfoption>
<smbconfoption><name>browseable</name><value>No</value></smbconfoption>
<smbconfsection>[print$]</smbconfsection>
<smbconfoption><name>comment</name><value>Printer Drivers</value></smbconfoption>
<smbconfoption><name>path</name><value>/var/lib/samba/drivers</value></smbconfoption>
<smbconfoption><name>admin users</name><value>root, Administrator</value></smbconfoption>
<smbconfoption><name>write list</name><value>root</value></smbconfoption>
</smbconfexample>
<example id="ch9-ldifadd">
<title>LDIF IDMAP Add-On Load File &smbmdash; File: /etc/openldap/idmap.LDIF</title>
<screen>
dn: ou=Idmap,dc=abmas,dc=biz
objectClass: organizationalUnit
ou: idmap
structuralObjectClass: organizationalUnit
</screen>
</example>
<example id="ch9-sdmlcnf">
<title>Configuration File for NSS LDAP Support &smbmdash; <filename>/etc/ldap.conf</filename></title>
<screen>
URI ldap://massive.abmas.biz ldap://massive.abmas.biz:636
host 192.168.2.1
base dc=abmas,dc=biz
binddn cn=Manager,dc=abmas,dc=biz
bindpw not24get
pam_password exop
nss_base_passwd ou=People,dc=abmas,dc=biz?one
nss_base_shadow ou=People,dc=abmas,dc=biz?one
nss_base_group ou=Groups,dc=abmas,dc=biz?one
ssl no
</screen>
</example>
<example id="ch9-sdmnss">
<title>NSS using LDAP for Identity Resolution &smbmdash; File: <filename>/etc/nsswitch.conf</filename></title>
<screen>
passwd: compat ldap
group: compat ldap
hosts: files dns wins
networks: files dns
services: files
protocols: files
rpc: files
ethers: files
netmasks: files
netgroup: files
publickey: files
bootparams: files
automount: files
aliases: files
</screen>
</example>
</sect2>
<sect2 id="wdcsdm">
<title>NT4/Samba Domain with Samba Domain Member Server &smbmdash; Using Winbind</title>
<para>
You need to use this method for creating a Samba Domain Member server if any of the following conditions
prevail:
</para>
<itemizedlist>
<listitem><para>
LDAP support (client) is not installed on the system.
</para></listitem>
<listitem><para>
There are mitigating circumstances forcing a decision not to use LDAP.
</para></listitem>
<listitem><para>
The Samba Domain Member server must be part of a Windows NT4 Domain.
</para></listitem>
</itemizedlist>
<para><indexterm>
<primary>Windows ADS Domain</primary>
</indexterm><indexterm>
<primary>Samba Domain</primary>
</indexterm><indexterm>
<primary>LDAP</primary>
</indexterm>
Later in the chapter, you can see how to configure a Samba Domain Member server for a Windows ADS Domain.
Right now your objective is to configure a Samba server that can be a member of a Windows NT4 style
Domain and/or does not use LDAP.
</para>
<note><para><indexterm>
<primary>duplicate accounts</primary>
</indexterm>
If you use <command>winbind</command> for Identity resolution, do make sure that there are no
duplicate accounts.
</para>
<para><indexterm>
<primary>/etc/passwd</primary>
</indexterm>
For example, do not have more than one account that has UID=0 in the password database. If there
is an account called <constant>root</constant> in the <filename>/etc/passwd</filename> database,
it is okay to have an account called <constant>root</constant> in the LDAP ldapsam or in the
tdbsam. But if there are two accounts in the passdb backend that have the same UID, winbind will
break. This means that the <constant>Administrator</constant> account must be called
<constant>root</constant>.
</para>
<para><indexterm>
<primary>/etc/passwd</primary>
</indexterm><indexterm>
<primary>ldapsam</primary>
</indexterm><indexterm>
<primary>tdbsam</primary>
</indexterm>
Winbind will break if there is an account in <filename>/etc/passwd</filename> that has
the same UID as an account that is in LDAP ldapsam (or in tdbsam) but that differs in name only.
</para></note>
<para><indexterm>
<primary>credentials</primary>
</indexterm><indexterm>
<primary>traverse</primary>
</indexterm><indexterm>
<primary>wide-area</primary>
</indexterm><indexterm>
<primary>network</primary>
<secondary>wide-area</secondary>
</indexterm><indexterm>
<primary>tdbdump</primary>
</indexterm>
The following configuration uses CIFS/SMB protocols alone to obtain user and group credentials.
The winbind information is locally cached in the <filename>winbindd_cache.tdb winbindd_idmap.tdb</filename>
files. This provides considerable performance benefits compared with the LDAP solution, particularly
where the LDAP lookups must traverse wide-area network links. You may examine the contents of these
files using the tool <command>tdbdump</command>, though you may have to build this from the Samba
source code if it has not been supplied as part of a binary package distribution that you may be using.
</para>
<procedure>
<title>Configuration of Winbind-Based Identity Resolution</title>
<step><para>
Using your favorite text editor, create the &smb.conf; file so it has the contents
shown in <link linkend="ch0-NT4DSDM"/>.
</para></step>
<step><para><indexterm>
<primary>/etc/nsswitch.conf</primary>
</indexterm>
Edit the <filename>/etc/nsswitch.conf</filename> so it has the entries shown in
<link linkend="ch9-nsswbnd"/>.
</para></step>
<step><para><indexterm>
<primary>net</primary>
<secondary>rpc</secondary>
<tertiary>join</tertiary>
</indexterm>
The system is ready to join the Domain. Execute the following:
<screen>
net rpc join -U root%not24et
Joined domain MEGANET2.
</screen>
This indicates that the Domain join succeed.
</para></step>
<step><para><indexterm>
<primary>winbind</primary>
</indexterm><indexterm>
<primary>wbinfo</primary>
</indexterm>
Validate operation of <command>winbind</command> using the <command>wbinfo</command>
tool as follows:
<screen>
&rootprompt; wbinfo -u
MEGANET2+root
MEGANET2+nobody
MEGANET2+jht
MEGANET2+maryv
MEGANET2+billr
MEGANET2+jelliott
MEGANET2+dbrady
MEGANET2+joeg
MEGANET2+balap
</screen>
This shows that Domain users have been listed correctly.
<screen>
&rootprompt; wbinfo -g
MEGANET2+Domain Admins
MEGANET2+Domain Users
MEGANET2+Domain Guests
MEGANET2+Accounts
MEGANET2+Finances
MEGANET2+PIOps
</screen>
This shows that Domain groups have been correctly obtained also.
</para></step>
<step><para><indexterm>
<primary>NSS</primary>
</indexterm><indexterm>
<primary>getent</primary>
</indexterm><indexterm>
<primary>winbind</primary>
</indexterm>
The next step verifies that NSS is able to obtain this information
correctly from <command>winbind</command> also.
<screen>
&rootprompt; getent passwd
...
MEGANET2+root:x:10000:10001:NetBIOS Domain Admin:
/home/MEGANET2/root:/bin/bash
MEGANET2+nobody:x:10001:10001:nobody:
/home/MEGANET2/nobody:/bin/bash
MEGANET2+jht:x:10002:10001:John H Terpstra:
/home/MEGANET2/jht:/bin/bash
MEGANET2+maryv:x:10003:10001:Mary Vortexis:
/home/MEGANET2/maryv:/bin/bash
MEGANET2+billr:x:10004:10001:William Randalph:
/home/MEGANET2/billr:/bin/bash
MEGANET2+jelliott:x:10005:10001:John G Elliott:
/home/MEGANET2/jelliott:/bin/bash
MEGANET2+dbrady:x:10006:10001:Darren Brady:
/home/MEGANET2/dbrady:/bin/bash
MEGANET2+joeg:x:10007:10001:Joe Green:
/home/MEGANET2/joeg:/bin/bash
MEGANET2+balap:x:10008:10001:Bala Pillay:
/home/MEGANET2/balap:/bin/bash
</screen>
The user account information has been correctly obtained. This information has
been merged with the winbind template information configured in the &smb.conf; file.
<screen>
&rootprompt;# getent group
...
MEGANET2+Domain Admins:x:10000:MEGANET2+root,MEGANET2+jht
MEGANET2+Domain Users:x:10001:MEGANET2+jht,MEGANET2+maryv,\
MEGANET2+billr,MEGANET2+jelliott,MEGANET2+dbrady,\
MEGANET2+joeg,MEGANET2+balap
MEGANET2+Domain Guests:x:10002:MEGANET2+nobody
MEGANET2+Accounts:x:10003:
MEGANET2+Finances:x:10004:
MEGANET2+PIOps:x:10005:
</screen>
</para></step>
<step><para>
The Samba member server of a Windows NT4 Domain is ready for use.
</para></step>
</procedure>
<smbconfexample id="ch0-NT4DSDM">
<title>Samba Domain Member Server &smb.conf; File for NT4 Domain</title>
<smbconfcomment>Global parameters</smbconfcomment>
<smbconfsection>[global]</smbconfsection>
<smbconfoption><name>unix charset</name><value>LOCALE</value></smbconfoption>
<smbconfoption><name>workgroup</name><value>MEGANET2</value></smbconfoption>
<smbconfoption><name>security</name><value>DOMAIN</value></smbconfoption>
<smbconfoption><name>username map</name><value>/etc/samba/smbusers</value></smbconfoption>
<smbconfoption><name>log level</name><value>1</value></smbconfoption>
<smbconfoption><name>syslog</name><value>0</value></smbconfoption>
<smbconfoption><name>log file</name><value>/var/log/samba/%m</value></smbconfoption>
<smbconfoption><name>max log size</name><value>0</value></smbconfoption>
<smbconfoption><name>smb ports</name><value>139 445</value></smbconfoption>
<smbconfoption><name>name resolve order</name><value>wins bcast hosts</value></smbconfoption>
<smbconfoption><name>printcap name</name><value>CUPS</value></smbconfoption>
<smbconfoption><name>wins server</name><value>192.168.2.1</value></smbconfoption>
<smbconfoption><name>idmap uid</name><value>10000-20000</value></smbconfoption>
<smbconfoption><name>idmap gid</name><value>10000-20000</value></smbconfoption>
<smbconfoption><name>template primary group</name><value>"Domain Users"</value></smbconfoption>
<smbconfoption><name>template shell</name><value>/bin/bash</value></smbconfoption>
<smbconfoption><name>winbind separator</name><value>+</value></smbconfoption>
<smbconfoption><name>printer admin</name><value>root</value></smbconfoption>
<smbconfoption><name>hosts allow</name><value>192.168.2., 192.168.3., 127.</value></smbconfoption>
<smbconfoption><name>printing</name><value>cups</value></smbconfoption>
<smbconfsection>[homes]</smbconfsection>
<smbconfoption><name>comment</name><value>Home Directories</value></smbconfoption>
<smbconfoption><name>valid users</name><value>%S</value></smbconfoption>
<smbconfoption><name>read only</name><value>No</value></smbconfoption>
<smbconfoption><name>browseable</name><value>No</value></smbconfoption>
<smbconfsection>[printers]</smbconfsection>
<smbconfoption><name>comment</name><value>SMB Print Spool</value></smbconfoption>
<smbconfoption><name>path</name><value>/var/spool/samba</value></smbconfoption>
<smbconfoption><name>guest ok</name><value>Yes</value></smbconfoption>
<smbconfoption><name>printable</name><value>Yes</value></smbconfoption>
<smbconfoption><name>browseable</name><value>No</value></smbconfoption>
<smbconfsection>[print$]</smbconfsection>
<smbconfoption><name>comment</name><value>Printer Drivers</value></smbconfoption>
<smbconfoption><name>path</name><value>/var/lib/samba/drivers</value></smbconfoption>
<smbconfoption><name>admin users</name><value>root, Administrator</value></smbconfoption>
<smbconfoption><name>write list</name><value>root</value></smbconfoption>
</smbconfexample>
<example id="ch9-nsswbnd">
<title>Name Service Switch Control File: <filename>/etc/nsswitch.conf</filename></title>
<screen>
# /etc/nsswitch.conf
passwd: compat winbind
group: compat winbind
hosts: files dns wins
networks: files dns
services: files
protocols: files
rpc: files
ethers: files
netmasks: files
netgroup: files
publickey: files
bootparams: files
automount: files
aliases: files
</screen>
</example>
</sect2>
<sect2 id="adssdm">
<title>Active Directory Domain with Samba Domain Member Server</title>
<para><indexterm>
<primary>Active Directory</primary>
<secondary>join</secondary>
</indexterm><indexterm>
<primary>Kerberos</primary>
</indexterm><indexterm>
<primary>Domain Member</primary>
<secondary>server</secondary>
</indexterm>
One of the much-sought-after features new to Samba-3 is the ability to join an Active Directory
Domain using Kerberos protocols. This makes it possible to operate an entire Windows network
without the need to run NetBIOS over TCP/IP and permits more secure networking in general. An
exhaustively complete discussion of the protocols is not possible in this book; perhaps a
later book may explore the intricacies of the NetBIOS-less operation that Samba-3 can participate
in. For now, we simply focus on how a Samba-3 server can be made a Domain Member server.
</para>
<para><indexterm>
<primary>Active Directory</primary>
</indexterm><indexterm>
<primary>LDAP</primary>
</indexterm><indexterm>
<primary>Identity resolution</primary>
</indexterm><indexterm>
<primary>Kerberos</primary>
</indexterm>
The diagram in <link linkend="ch9-adsdc"/> demonstrates how Samba-3 interfaces with
Microsoft Active Directory components. It should be noted that if Microsoft Windows Services
for UNIX has been installed and correctly configured, it is possible to use client LDAP
for Identity resolution just as can be done with Samba-3 when using an LDAP passdb backend.
The UNIX tool that you need for this, as in the case of LDAP on UNIX/Linux, is the PADL
Software nss_ldap tool-set. Compared with use of winbind and Kerberos, the use of
LDAP-based Identity resolution is a little less secure. In view of the fact that this solution
requires additional software to be installed on the Windows 200x ADS Domain Controllers,
and that means more management overhead, it is likely that most Samba-3 ADS client sites
may elect to use winbind.
</para>
<para>
Do not attempt to use this procedure if you are not 100 percent certain that the build of Samba-3
you are using has been compiled and linked with all the tools necessary for this to work.
Given the importance of this step, you must first validate that the Samba-3 message block
daemon (<command>smbd</command>) has the necessary features.
</para>
<para>
The hypothetical domain you are using in this example assumes that the Abmas London office
decided to take their own lead (some would say this is a typical behavior in a global
corporate world; besides, a little divergence and conflict makes for an interesting life).
The Windows Server 2003 ADS Domain is called <constant>london.abmas.biz</constant> and the
name of the server is <constant>W2K3S</constant>. In ADS realm terms, the Domain Controller
is known as <constant>w2k3s.london.abmas.biz</constant>. In NetBIOS nomenclature, the
Domain Name is <constant>LONDON</constant> and the server name is <constant>W2K3S</constant>.
</para>
<figure id="ch9-adsdc">
<title>Active Directory Domain: Samba Member Server</title>
<mediaobject>
<imageobject role="latex">
<imagedata fileref="guide/images/chap9-ADSDC.png" scale="75" scalefit="1"/>
</imageobject>
<imageobject>
<imagedata fileref="guide/images/chap9-SambaDC.png" scale="75" scalefit="1"/>
</imageobject>
</mediaobject>
</figure>
<procedure>
<step><para><indexterm>
<primary>smbd</primary>
</indexterm>
Before you try to use Samba-3, you want to know for certain that your executables have
support for Kerberos and for LDAP. Execute the following to identify whether or
not this build is perhaps suitable for use:
<screen>
&rootprompt; cd /usr/sbin
&rootprompt; smbd -b | grep KRB
HAVE_KRB5_H
HAVE_ADDR_TYPE_IN_KRB5_ADDRESS
HAVE_KRB5
HAVE_KRB5_AUTH_CON_SETKEY
HAVE_KRB5_GET_DEFAULT_IN_TKT_ETYPES
HAVE_KRB5_GET_PW_SALT
HAVE_KRB5_KEYBLOCK_KEYVALUE
HAVE_KRB5_KEYTAB_ENTRY_KEYBLOCK
HAVE_KRB5_MK_REQ_EXTENDED
HAVE_KRB5_PRINCIPAL_GET_COMP_STRING
HAVE_KRB5_SET_DEFAULT_IN_TKT_ETYPES
HAVE_KRB5_STRING_TO_KEY
HAVE_KRB5_STRING_TO_KEY_SALT
HAVE_LIBKRB5
</screen>
The above output was obtained on a SuSE Linux system and shows the output for
Samba that has been compiled and linked with the Heimdal Kerberos libraries.
The following is a typical output that will be found on a Red Hat Linux system that
has been linked with the MIT Kerberos libraries:
<screen>
&rootprompt; cd /usr/sbin
&rootprompt; smbd -b | grep KRB
HAVE_KRB5_H
HAVE_ADDRTYPE_IN_KRB5_ADDRESS
HAVE_KRB5
HAVE_KRB5_AUTH_CON_SETUSERUSERKEY
HAVE_KRB5_ENCRYPT_DATA
HAVE_KRB5_FREE_DATA_CONTENTS
HAVE_KRB5_FREE_KTYPES
HAVE_KRB5_GET_PERMITTED_ENCTYPES
HAVE_KRB5_KEYTAB_ENTRY_KEY
HAVE_KRB5_LOCATE_KDC
HAVE_KRB5_MK_REQ_EXTENDED
HAVE_KRB5_PRINCIPAL2SALT
HAVE_KRB5_PRINC_COMPONENT
HAVE_KRB5_SET_DEFAULT_TGS_KTYPES
HAVE_KRB5_SET_REAL_TIME
HAVE_KRB5_STRING_TO_KEY
HAVE_KRB5_TKT_ENC_PART2
HAVE_KRB5_USE_ENCTYPE
HAVE_LIBGSSAPI_KRB5
HAVE_LIBKRB5
</screen>
You can validate that Samba has been compiled and linked with LDAP support
by executing:
<screen>
&rootprompt; smbd -b | grep LDAP
massive:/usr/sbin # smbd -b | grep LDAP
HAVE_LDAP_H
HAVE_LDAP
HAVE_LDAP_DOMAIN2HOSTLIST
HAVE_LDAP_INIT
HAVE_LDAP_INITIALIZE
HAVE_LDAP_SET_REBIND_PROC
HAVE_LIBLDAP
LDAP_SET_REBIND_PROC_ARGS
</screen>
This does look promising; <command>smbd</command> has been built with Kerberos and LDAP
support. You are relieved to know that it is safe to progress.
</para></step>
<step><para><indexterm>
<primary>Kerberos</primary>
<secondary>libraries</secondary>
</indexterm><indexterm>
<primary>MIT Kerberos</primary>
</indexterm><indexterm>
<primary>Heimdal Kerberos</primary>
</indexterm><indexterm>
<primary>Kerberos</primary>
<secondary>MIT</secondary>
</indexterm><indexterm>
<primary>Kerberos</primary>
<secondary>Heimdal</secondary>
</indexterm><indexterm>
<primary>Red Hat Linux</primary>
</indexterm><indexterm>
<primary>SUSE Linux</primary>
</indexterm><indexterm>
<primary>SerNet</primary>
</indexterm><indexterm>
<primary>validated</primary>
</indexterm>
The next step is to identify which version of the Kerberos libraries have been used.
In order to permit Samba-3 to interoperate with Windows 2003 Active Directory, it is
essential that it has been linked with either MIT Kerberos version 1.3.1 or later,
or that it has been linked with Heimdal Kerberos 0.6 plus specific patches. You may
identify what version of the MIT Kerberos libraries are installed on your system by
executing (on Red Hat Linux):
<screen>
&rootprompt; rpm -q krb5
</screen>
Or on SUSE Linux, execute:
<screen>
&rootprompt; rpm -q heimdal
</screen>
Please note that the RPMs provided by the Samba-Team are known to be working and have
been validated. Red Hat Linux RPMs may be obtained from the Samba FTP sites. SUSE
Linux RPMs may be obtained from <ulink url="ftp://ftp.sernet.de">Sernet</ulink> in
Germany.
</para>
<para>
From this point on, you are certain that the Samba-3 build you are using has the
necessary capabilities. You can now configure Samba-3 and the name service
switcher (NSS).
</para></step>
<step><para>
Using you favorite editor, configure the &smb.conf; file that is located in the
<filename>/etc/samba</filename> directory so that it has the contents shown
in <link linkend="ch9-adssdm"/>.
</para></step>
<step><para>
Edit or create the NSS control file so it has the contents shown in <link linkend="ch9-nsswbnd"/>.
</para></step>
<step><para><indexterm>
<primary>/etc/samba/secrets.tdb</primary>
</indexterm>
Delete the file <filename>/etc/samba/secrets.tdb</filename>, if it exists. Of course, you
do keep a backup, don't you?
</para></step>
<step><para>
Delete the tdb files that cache Samba information. You keep a backup of the old
files, of course. You also remove all files to ensure that nothing can pollute your
nice, new configuration. Execute the following (example is for SUSE Linux):
<screen>
&rootprompt; rm /var/lib/samba/*tdb
</screen>
</para></step>
<step><para><indexterm>
<primary>testparm</primary>
</indexterm>
Validate your &smb.conf; file using <command>testparm</command> (as you have
done previously). Correct all errors reported before proceeding. The command you
execute is:
<screen>
&rootprompt; testparm -s | less
</screen>
Now that you are satisfied that your Samba server is ready to join the Windows
ADS Domain, let's move on.
</para></step>
<step><para><indexterm>
<primary>net</primary>
<secondary>ads</secondary>
<tertiary>join</tertiary>
</indexterm><indexterm>
<primary>Kerberos</primary>
</indexterm>
This is a good time to double-check everything and then execute the following
command when everything you have done has checked out okay:
<screen>
&rootprompt; net ads join -UAdministrator%not24get
Using short domain name -- LONDON
Joined 'FRAN' to realm 'LONDON.ABMAS.BIZ'
</screen>
You have successfully made your Samba-3 server a member of the ADS Domain
using Kerberos protocols.
</para>
<para><indexterm>
<primary>silent return</primary>
</indexterm><indexterm>
<primary>failed join</primary>
</indexterm>
In the event that you receive no output messages, a silent return means that the
Domain join failed. You should use <command>ethereal</command> to identify what
may be failing. Common causes of a failed join include:
<itemizedlist>
<listitem><para><indexterm>
<primary>name resolution</primary>
<secondary>Defective</secondary>
</indexterm>
Defective or misconfigured DNS name resolution.
</para></listitem>
<listitem><para><indexterm>
<primary>Restrictive security</primary>
</indexterm>
Restrictive security settings on the Windows 200x ADS Domain controller
preventing needed communications protocols. You can check this by searching
the Windows Server 200x Event Viewer.
</para></listitem>
<listitem><para>
Incorrectly configured &smb.conf; file settings.
</para></listitem>
<listitem><para>
Lack of support of necessary Kerberos protocols because the version of MIT
Kerberos (or Heimdal) in use is not up to date enough to support the necessary
functionality.
</para></listitem>
</itemizedlist>
<indexterm>
<primary>net</primary>
<secondary>rpc</secondary>
<tertiary>join</tertiary>
</indexterm><indexterm>
<primary>RPC</primary>
</indexterm><indexterm>
<primary>mixed mode</primary>
</indexterm>
In any case, never execute the <command>net rpc join</command> command in an attempt
to join the Samba server to the Domain, unless you wish not to use the Kerberos
security protocols. Use of the older RPC-based Domain join facility requires that
Windows Server 200x ADS has been configured appropriately for mixed mode operation.
</para></step>
<step><para><indexterm>
<primary>tdbdump</primary>
</indexterm><indexterm>
<primary>/etc/samba/secrets.tdb</primary>
</indexterm>
If the <command>tdbdump</command> is installed on your system (not essential),
you can look inside the <filename>/etc/samba/secrets.tdb</filename> file. If
you wish to do this, execute:
<screen>
&rootprompt; tdbdump secrets.tdb
{
key = "SECRETS/SID/LONDON"
data = "\01\04\00\00\00\00\00\05\15\00\00\00\EBw\86\F1\ED\BD\
F6{\5C6\E5W\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\
00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\
00\00\00\00\00\00\00\00"
}
{
key = "SECRETS/MACHINE_PASSWORD/LONDON"
data = "le3Q5FPnN5.ueC\00"
}
{
key = "SECRETS/MACHINE_SEC_CHANNEL_TYPE/LONDON"
data = "\02\00\00\00"
}
{
key = "SECRETS/MACHINE_LAST_CHANGE_TIME/LONDON"
data = "E\89\F6?"
}
</screen>
This is given to demonstrate to the skeptics that this process truly does work.
</para></step>
<step><para>
It is now time to start Samba in the usual way (as has been done many time before
in this book).
</para></step>
<step><para><indexterm>
<primary>wbinfo</primary>
</indexterm>
This is a good time to verify that everything is working. First, check that
winbind is able to obtain the list of users and groups from the ADS Domain Controller.
Execute the following:
<screen>
&rootprompt; wbinfo -u
LONDON+Administrator
LONDON+Guest
LONDON+SUPPORT_388945a0
LONDON+krbtgt
LONDON+jht
</screen>
Good, the list of users was obtained. Now do likewise for group accounts:
<screen>
&rootprompt; wbinfo -g
LONDON+Domain Computers
LONDON+Domain Controllers
LONDON+Schema Admins
LONDON+Enterprise Admins
LONDON+Domain Admins
LONDON+Domain Users
LONDON+Domain Guests
LONDON+Group Policy Creator Owners
LONDON+DnsUpdateProxy
</screen>
Excellent. That worked also, as expected.
</para></step>
<step><para><indexterm>
<primary>getent</primary>
</indexterm>
Now repeat this via NSS to validate that full Identity resolution is
functional as required. Execute:
<screen>
&rootprompt; getent passwd
...
LONDON+Administrator:x:10000:10000:Administrator:
/home/LONDON/administrator:/bin/bash
LONDON+Guest:x:10001:10001:Guest:
/home/LONDON/guest:/bin/bash
LONDON+SUPPORT_388945a0:x:10002:10000:SUPPORT_388945a0:
/home/LONDON/support_388945a0:/bin/bash
LONDON+krbtgt:x:10003:10000:krbtgt:
/home/LONDON/krbtgt:/bin/bash
LONDON+jht:x:10004:10000:John H. Terpstra:
/home/LONDON/jht:/bin/bash
</screen>
Okay, ADS user accounts are being resolved. Now you try group resolution as follows:
<screen>
&rootprompt; getent group
...
LONDON+Domain Computers:x:10002:
LONDON+Domain Controllers:x:10003:
LONDON+Schema Admins:x:10004:LONDON+Administrator
LONDON+Enterprise Admins:x:10005:LONDON+Administrator
LONDON+Domain Admins:x:10006:LONDON+jht,LONDON+Administrator
LONDON+Domain Users:x:10000:
LONDON+Domain Guests:x:10001:
LONDON+Group Policy Creator Owners:x:10007:LONDON+Administrator
LONDON+DnsUpdateProxy:x:10008:
</screen>
This is very pleasing. Everything works as expected.
</para></step>
<step><para><indexterm>
<primary>net</primary>
<secondary>ads</secondary>
<tertiary>info</tertiary>
</indexterm><indexterm>
<primary>Active Directory</primary>
<secondary>server</secondary>
</indexterm><indexterm>
<primary>Kerberos</primary>
</indexterm>
You may now perform final verification that communications between Samba-3 winbind and
the Active Directory server is using Kerberos protocols. Execute the following:
<screen>
&rootprompt; net ads info
LDAP server: 192.168.2.123
LDAP server name: w2k3s
Realm: LONDON.ABMAS.BIZ
Bind Path: dc=LONDON,dc=ABMAS,dc=BIZ
LDAP port: 389
Server time: Sat, 03 Jan 2004 02:44:44 GMT
KDC server: 192.168.2.123
Server time offset: 2
</screen>
It should be noted that Kerberos protocols are time-clock critical. You should
keep all server time clocks synchronized using the network time protocol (NTP).
In any case, the output we obtained confirms that all systems are operational.
</para></step>
<step><para><indexterm>
<primary>net</primary>
<secondary>ads</secondary>
<tertiary>status</tertiary>
</indexterm>
There is one more action you elect to take, just because you are paranoid and disbelieving,
so you execute the following command:
<programlisting>
&rootprompt; net ads status -UAdministrator%not24get
objectClass: top
objectClass: person
objectClass: organizationalPerson
objectClass: user
objectClass: computer
cn: fran
distinguishedName: CN=fran,CN=Computers,DC=london,DC=abmas,DC=biz
instanceType: 4
whenCreated: 20040103092006.0Z
whenChanged: 20040103092006.0Z
uSNCreated: 28713
uSNChanged: 28717
name: fran
objectGUID: 58f89519-c467-49b9-acb0-f099d73696e
userAccountControl: 69632
badPwdCount: 0
codePage: 0
countryCode: 0
badPasswordTime: 0
lastLogoff: 0
lastLogon: 127175965783327936
localPolicyFlags: 0
pwdLastSet: 127175952062598496
primaryGroupID: 515
objectSid: S-1-5-21-4052121579-2079768045-1474639452-1109
accountExpires: 9223372036854775807
logonCount: 13
sAMAccountName: fran$
sAMAccountType: 805306369
operatingSystem: Samba
operatingSystemVersion: 3.0.2-SUSE
dNSHostName: fran
userPrincipalName: HOST/fran@LONDON.ABMAS.BIZ
servicePrincipalName: CIFS/fran.london.abmas.biz
servicePrincipalName: CIFS/fran
servicePrincipalName: HOST/fran.london.abmas.biz
servicePrincipalName: HOST/fran
objectCategory: CN=Computer,CN=Schema,CN=Configuration,
DC=london,DC=abmas,DC=biz
isCriticalSystemObject: FALSE
-------------- Security Descriptor (revision: 1, type: 0x8c14)
owner SID: S-1-5-21-4052121579-2079768045-1474639452-512
group SID: S-1-5-21-4052121579-2079768045-1474639452-513
------- (system) ACL (revision: 4, size: 120, number of ACEs: 2)
------- ACE (type: 0x07, flags: 0x5a, size: 0x38,
mask: 0x20, object flags: 0x3)
access SID: S-1-1-0
access type: AUDIT OBJECT
Permissions:
[Write All Properties]
------- ACE (type: 0x07, flags: 0x5a, size: 0x38,
mask: 0x20, object flags: 0x3)
access SID: S-1-1-0
access type: AUDIT OBJECT
Permissions:
[Write All Properties]
------- (user) ACL (revision: 4, size: 1944, number of ACEs: 40)
------- ACE (type: 0x00, flags: 0x00, size: 0x24, mask: 0xf01ff)
access SID: S-1-5-21-4052121579-2079768045-1474639452-512
access type: ALLOWED
Permissions: [Full Control]
------- ACE (type: 0x00, flags: 0x00, size: 0x18, mask: 0xf01ff)
access SID: S-1-5-32-548
...
------- ACE (type: 0x05, flags: 0x12, size: 0x38,
mask: 0x10, object flags: 0x3)
access SID: S-1-5-9
access type: ALLOWED OBJECT
Permissions:
[Read All Properties]
-------------- End Of Security Descriptor
</programlisting>
And now you have conclusive proof that your Samba-3 ADS Domain Member Server
called <constant>FRAN</constant>, is able to communicate fully with the ADS
Domain Controllers.
</para></step>
</procedure>
<para>
Your Samba-3 ADS Domain Member server is ready for use. During training sessions,
you may be asked what is inside the <filename>winbindd_cache.tdb and winbindd_idmap.tdb</filename>
files. Since curiosity just took hold of you, execute the following:
<programlisting>
&rootprompt; tdbdump /var/lib/samba/winbindd_idmap.tdb
{
key = "S-1-5-21-4052121579-2079768045-1474639452-501\00"
data = "UID 10001\00"
}
{
key = "UID 10005\00"
data = "S-1-5-21-4052121579-2079768045-1474639452-1111\00"
}
{
key = "GID 10004\00"
data = "S-1-5-21-4052121579-2079768045-1474639452-518\00"
}
{
key = "S-1-5-21-4052121579-2079768045-1474639452-502\00"
data = "UID 10003\00"
}
...
&rootprompt; tdbdump /var/lib/samba/winbindd_cache.tdb
{
key = "UL/LONDON"
data = "\00\00\00\00bp\00\00\06\00\00\00\0DAdministrator\0D
Administrator-S-1-5-21-4052121579-2079768045-1474639452-500-
S-1-5-21-4052121579-2079768045-1474639452-513\05Guest\05
Guest-S-1-5-21-4052121579-2079768045-1474639452-501-
S-1-5-21-4052121579-2079768045-1474639452-514\10
SUPPORT_388945a0\10SUPPORT_388945a0.
S-1-5-21-4052121579-2079768045-1474639452-1001-
S-1-5-21-4052121579-2079768045-1474639452-513\06krbtgt\06
krbtgt-S-1-5-21-4052121579-2079768045-1474639452-502-
S-1-5-21-4052121579-2079768045-1474639452-513\03jht\10
John H. Terpstra.S-1-5-21-4052121579-2079768045-1474639452-1110-
S-1-5-21-4052121579-2079768045-1474639452-513"
}
{
key = "GM/S-1-5-21-4052121579-2079768045-1474639452-512"
data = "\00\00\00\00bp\00\00\02\00\00\00.
S-1-5-21-4052121579-2079768045-1474639452-1110\03
jht\01\00\00\00-S-1-5-21-4052121579-2079768045-1474639452-500\0D
Administrator\01\00\00\00"
}
{
key = "SN/S-1-5-21-4052121579-2079768045-1474639452-513"
data = "\00\00\00\00xp\00\00\02\00\00\00\0CDomain Users"
}
{
key = "GM/S-1-5-21-4052121579-2079768045-1474639452-518"
data = "\00\00\00\00bp\00\00\01\00\00\00-
S-1-5-21-4052121579-2079768045-1474639452-500\0D
Administrator\01\00\00\00"
}
{
key = "SEQNUM/LONDON\00"
data = "xp\00\00C\92\F6?"
}
{
key = "U/S-1-5-21-4052121579-2079768045-1474639452-1110"
data = "\00\00\00\00xp\00\00\03jht\10John H. Terpstra.
S-1-5-21-4052121579-2079768045-1474639452-1110-
S-1-5-21-4052121579-2079768045-1474639452-513"
}
{
key = "NS/S-1-5-21-4052121579-2079768045-1474639452-502"
data = "\00\00\00\00bp\00\00-
S-1-5-21-4052121579-2079768045-1474639452-502"
}
{
key = "SN/S-1-5-21-4052121579-2079768045-1474639452-1001"
data = "\00\00\00\00bp\00\00\01\00\00\00\10SUPPORT_388945a0"
}
{
key = "SN/S-1-5-21-4052121579-2079768045-1474639452-500"
data = "\00\00\00\00bp\00\00\01\00\00\00\0DAdministrator"
}
{
key = "U/S-1-5-21-4052121579-2079768045-1474639452-502"
data = "\00\00\00\00bp\00\00\06krbtgt\06krbtgt-
S-1-5-21-4052121579-2079768045-1474639452-502-
S-1-5-21-4052121579-2079768045-1474639452-513"
}
....
</programlisting>
Now all is revealed. Your curiosity, as well as that of those with you, has been put at ease.
May this server serve well all who happen upon it.
</para>
<smbconfexample id="ch9-adssdm">
<title>Samba Domain Member &smb.conf; File for Active Directory Membership</title>
<smbconfcomment>Global parameters</smbconfcomment>
<smbconfsection>[global]</smbconfsection>
<smbconfoption><name>unix charset</name><value>LOCALE</value></smbconfoption>
<smbconfoption><name>workgroup</name><value>LONDON</value></smbconfoption>
<smbconfoption><name>realm</name><value>LONDON.ABMAS.BIZ</value></smbconfoption>
<smbconfoption><name>server string</name><value>Samba 3.0.2</value></smbconfoption>
<smbconfoption><name>security</name><value>ADS</value></smbconfoption>
<smbconfoption><name>username map</name><value>/etc/samba/smbusers</value></smbconfoption>
<smbconfoption><name>log level</name><value>1</value></smbconfoption>
<smbconfoption><name>syslog</name><value>0</value></smbconfoption>
<smbconfoption><name>log file</name><value>/var/log/samba/%m</value></smbconfoption>
<smbconfoption><name>max log size</name><value>50</value></smbconfoption>
<smbconfoption><name>printcap name</name><value>CUPS</value></smbconfoption>
<smbconfoption><name>ldap ssl</name><value>no</value></smbconfoption>
<smbconfoption><name>idmap uid</name><value>10000-20000</value></smbconfoption>
<smbconfoption><name>idmap gid</name><value>10000-20000</value></smbconfoption>
<smbconfoption><name>template primary group</name><value>"Domain Users"</value></smbconfoption>
<smbconfoption><name>template shell</name><value>/bin/bash</value></smbconfoption>
<smbconfoption><name>winbind separator</name><value>+</value></smbconfoption>
<smbconfoption><name>printing</name><value>cups</value></smbconfoption>
<smbconfsection>[homes]</smbconfsection>
<smbconfoption><name>comment</name><value>Home Directories</value></smbconfoption>
<smbconfoption><name>valid users</name><value>%S</value></smbconfoption>
<smbconfoption><name>read only</name><value>No</value></smbconfoption>
<smbconfoption><name>browseable</name><value>No</value></smbconfoption>
<smbconfsection>[printers]</smbconfsection>
<smbconfoption><name>comment</name><value>SMB Print Spool</value></smbconfoption>
<smbconfoption><name>path</name><value>/var/spool/samba</value></smbconfoption>
<smbconfoption><name>guest ok</name><value>Yes</value></smbconfoption>
<smbconfoption><name>printable</name><value>Yes</value></smbconfoption>
<smbconfoption><name>browseable</name><value>No</value></smbconfoption>
<smbconfsection>[print$]</smbconfsection>
<smbconfoption><name>comment</name><value>Printer Drivers</value></smbconfoption>
<smbconfoption><name>path</name><value>/var/lib/samba/drivers</value></smbconfoption>
<smbconfoption><name>admin users</name><value>root, Administrator</value></smbconfoption>
<smbconfoption><name>write list</name><value>root</value></smbconfoption>
</smbconfexample>
</sect2>
<sect2>
<title>UNIX/Linux Client Domain Member</title>
<para><indexterm>
<primary>user credentials</primary>
</indexterm>
So far this chapter has been mainly concerned with the provision of file and print
services for Domain Member servers. However, an increasing number of UNIX/Linux
workstations are being installed that do not act as file or print servers to anyone
other than a single desktop user. The key demand for desktop systems is to be able
to log onto any UNIX/Linux or Windows desktop using the same network user credentials.
</para>
<para><indexterm>
<primary>Single Sign-On</primary>
<see>SOS</see>
</indexterm>
The ability to use a common set of user credential across a variety of network systems
is generally regarded as a Single Sign-On (SOS) solution. SOS systems are sold by a
large number of vendors and include a range of technologies such as:
</para>
<itemizedlist>
<listitem><para>
Proxy sign-on
</para></listitem>
<listitem><para>
Federated directory provisioning
</para></listitem>
<listitem><para>
Meta-directory server solutions
</para></listitem>
<listitem><para>
Replacement authentication systems
</para></listitem>
</itemizedlist>
<para><indexterm>
<primary>Identity management</primary>
</indexterm>
There are really only three solutions that provide integrated authentication and
user Identity management facilities:
</para>
<itemizedlist>
<listitem><para>
Samba Winbind (free)
</para></listitem>
<listitem><para>
<ulink url="http://www.padl.com">PADL</ulink> PAM and LDAP Tools (free)
</para></listitem>
<listitem><para>
<ulink url="http://www.vintela.com">Vintela</ulink> Authentication Services (Commercial)
</para></listitem>
</itemizedlist>
<para>
The following guidelines are pertinent in respect of the deployment of winbind-based authentication
and Identity resolution with the express purpose of allowing users to log onto UNIX/Linux desktops
using Windows network Domain user credentials (username and password).
</para>
<para>
You should note that it is possible to use LDAP-based PAM and NSS tools to permit distributed
systems logons (SSO) providing user and group accounts are stored in an LDAP directory. This
provides logon services for UNIX/Linux users, while Windows users obtain their sign-on
support via Samba-3.
</para>
<para><indexterm>
<primary>Windows Services for UNIX</primary>
<see>SUS</see>
</indexterm>
On the other hand, if the authentication and Identity resolution backend must be provided by
a Windows NT4 style Domain or from an Active Directory Domain that does not have the Microsoft
Windows Services for UNIX (SUS) installed, winbind is your best friend. Specific guidance for these
situations now follows.
</para>
<para><indexterm>
<primary>PAM</primary>
</indexterm><indexterm>
<primary>Identity resolution</primary>
</indexterm><indexterm>
<primary>NSS</primary>
</indexterm>
To permit users to log onto a Linux system using Windows network credentials, you need to
configure Identity resolution (NSS) and PAM. This means that the basic steps include those
outlined above with the addition of PAM configuration. Given that most workstations (desktop/client)
usually do not need to provide file and print services to a group of users, the configuration
of shares and printers is generally less important. Often this allows the share specifications
to be entirely removed from the &smb.conf; file. That is obviously an administrator decision.
</para>
<sect3>
<title>NT4 Domain Member</title>
<para>
The following steps provide a Linux system that users can log onto using
Windows NT4 Domain (or Samba-3) Domain network credentials:
</para>
<procedure>
<step><para>
Follow the steps outlined in <link linkend="wdcsdm"/> and ensure that
all validation tests function as shown.
</para></step>
<step><para>
Identify what services users must log onto. On Red Hat Linux, if it is
intended that the user shall be given access to all services, it may be
most expeditious to simply configure the file
<filename>/etc/pam.d/system-auth</filename>.
</para></step>
<step><para>
Carefully make a backup copy of all PAM configuration files before you
begin making changes. If you break the PAM configuration, please note
that you may need to use an emergency boot process to recover your Linux
system. It is possible to break the ability to log into the system if
PAM files are incorrectly configured. The entire directory
<filename>/etc/pam.d</filename> should be backed up to a safe location.
</para></step>
<step><para>
If you require only console login support, edit the <filename>/etc/pam.d/login</filename>
so it matches <link linkend="ch9-pamwnbdlogin"/>.
</para></step>
<step><para>
To provide the ability to log onto the graphical desktop interface, you must edit
the files <filename>gdm</filename> and <filename>xdm</filename> in the
<filename>/etc/pam.d</filename> directory.
</para></step>
<step><para>
Edit only one file at a time. Carefully validate its operation before attempting
to reboot the machine.
</para></step>
</procedure>
</sect3>
<sect3>
<title>ADS Domain Member</title>
<para>
This procedure should be followed to permit a Linux network client (workstation/desktop)
to permit users to log on using Microsoft Active Directory based user credentials.
</para>
<procedure>
<step><para>
Follow the steps outlined in <link linkend="adssdm"/> and ensure that
all validation tests function as shown.
</para></step>
<step><para>
Identify what services users must log onto. On Red Hat Linux, if it is
intended that the user shall be given access to all services, it may be
most expeditious to simply configure the file
<filename>/etc/pam.d/system-auth</filename> as shown in <link linkend="ch9-rhsysauth"/>.
</para></step>
<step><para>
Carefully make a backup copy of all PAM configuration files before you
begin making changes. If you break the PAM configuration, please note
that you may need to use an emergency boot process to recover your Linux
system. It is possible to break the ability to log into the system if
PAM files are incorrectly configured. The entire directory
<filename>/etc/pam.d</filename> should be backed up to a safe location.
</para></step>
<step><para>
If you require only console login support, edit the <filename>/etc/pam.d/login</filename>
so it matches <link linkend="ch9-pamwnbdlogin"/>.
</para></step>
<step><para>
To provide the ability to log onto the graphical desktop interface, you must edit
the files <filename>gdm</filename> and <filename>xdm</filename> in the
<filename>/etc/pam.d</filename> directory.
</para></step>
<step><para>
Edit only one file at a time. Carefully validate its operation before attempting
to reboot the machine.
</para></step>
</procedure>
</sect3>
<example id="ch9-pamwnbdlogin">
<title>SUSE: PAM <filename>login</filename> Module Using Winbind</title>
<screen>
# /etc/pam.d/login
#%PAM-1.0
auth sufficient pam_unix2.so nullok
auth sufficient pam_winbind.so use_first_pass use_authtok
auth required pam_securetty.so
auth required pam_nologin.so
auth required pam_env.so
auth required pam_mail.so
account sufficient pam_unix2.so
account sufficient pam_winbind.so user_first_pass use_authtok
password required pam_pwcheck.so nullok
password sufficient pam_unix2.so nullok use_first_pass use_authtok
password sufficient pam_winbind.so use_first_pass use_authtok
session sufficient pam_unix2.so none
session sufficient pam_winbind.so use_first_pass use_authtok
session required pam_limits.so
</screen>
</example>
<example id="ch9-pamwbndxdm">
<title>SUSE: PAM <filename>xdm</filename> Module Using Winbind</title>
<screen>
# /etc/pam.d/gdm (/etc/pam.d/xdm)
#%PAM-1.0
auth sufficient pam_unix2.so nullok
auth sufficient pam_winbind.so use_first_pass use_authtok
account sufficient pam_unix2.so
account sufficient pam_winbind.so use_first_pass use_authtok
password sufficient pam_unix2.so
password sufficient pam_winbind.so use_first_pass use_authtok
session sufficient pam_unix2.so
session sufficient pam_winbind.so use_first_pass use_authtok
session required pam_dev perm.so
session required pam_resmgr.so
</screen>
</example>
<example id="ch9-rhsysauth">
<title>Red Hat 9: PAM System Authentication File: <filename>/etc/pam.d/system-auth</filename> Module Using Winbind</title>
<screen>
#%PAM-1.0
auth required /lib/security/$ISA/pam_env.so
auth sufficient /lib/security/$ISA/pam_unix.so likeauth nullok
auth sufficient /lib/security/$ISA/pam_winbind.so use_first_pass
auth required /lib/security/$ISA/pam_deny.so
account required /lib/security/$ISA/pam_unix.so
account sufficient /lib/security/$ISA/pam_winbind.so use_first_pass
password required /lib/security/$ISA/pam_cracklib.so retry=3 type=
# Note: The above line is complete. There is nothing following the '='
password sufficient /lib/security/$ISA/pam_unix.so \
nullok use_authtok md5 shadow
password sufficient /lib/security/$ISA/pam_winbind.so use_first_pass
password required /lib/security/$ISA/pam_deny.so
session required /lib/security/$ISA/pam_limits.so
session sufficient /lib/security/$ISA/pam_unix.so
session sufficient /lib/security/$ISA/pam_winbind.so use_first_pass
</screen>
</example>
</sect2>
<sect2>
<title>Key Points Learned</title>
<para>
The addition of UNIX/Linux Samba servers and clients is a common requirement. In this chapter, you
learned how to integrate such servers so that the UID/GID mappings they use can be consistent
across all Domain Member servers. You also discovered how to implement the ability to use Samba
or Windows Domain account credentials to log onto a UNIX/Linux client.
</para>
<para>
The following are key points noted:
</para>
<itemizedlist>
<listitem><para>
Domain Controllers are always authoritative for the Domain.
</para></listitem>
<listitem><para>
Domain Members may have local accounts and must be able to resolve the identity of
Domain user accounts. Domain user account identity must map to a local UID/GID. That
local UID/GID can be stored in LDAP. This way, it is possible to share the IDMAP data
across all Domain Member machines.
</para></listitem>
<listitem><para>
Resolution of user and group identities on Domain Member machines may be implemented
using direct LDAP services or using winbind.
</para></listitem>
<listitem><para>
On NSS/PAM enabled UNIX/Linux systems, NSS is responsible for Identity management
and PAM is responsible for authentication of logon credentials (user name and password).
</para></listitem>
</itemizedlist>
</sect2>
</sect1>
<sect1>
<title>Questions and Answers</title>
<para>
The following questions were obtained from the mailing list and also from private discussions
with Windows network administrators.
</para>
<qandaset defaultlabel="chap09qa" type="number">
<qandaentry>
<question>
<para>
We use NIS for all UNIX accounts. Why do we need winbind?
</para>
</question>
<answer>
<para><indexterm>
<primary>NIS</primary>
</indexterm><indexterm>
<primary>encrypted passwords</primary>
</indexterm><indexterm>
<primary>smbpasswd</primary>
</indexterm><indexterm>
<primary>tdbsam</primary>
</indexterm><indexterm>
<primary>passdb backend</primary>
</indexterm><indexterm>
<primary>Winbind</primary>
</indexterm>
You can use NIS for your UNIX accounts. NIS does not store the Windows encrypted
passwords that need to be stored in one of the acceptable passdb backends.
Your choice of backend is limited to <parameter>smbpasswd</parameter> or
<parameter>tdbsam</parameter>. Winbind is needed to handle the resolution of
SIDs from trusted domains to local UID/GID values.
</para>
<para><indexterm>
<primary>winbind trusted domains only</primary>
</indexterm><indexterm>
<primary>getpwnam()</primary>
</indexterm>
On a Domain Member server, you effectively map Windows Domain users to local users
that are in your NIS database by specifying the <parameter>winbind trusted domains
only</parameter>. This causes user and group account lookups to be routed via
the <command>getpwnam()</command> family of systems calls. On an NIS-enabled client,
this pushes the resolution of users and groups out through NIS.
</para>
<para>
As a general rule, it is always a good idea to run winbind on all Samba servers.
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>
Our IT management people do not like LDAP, but are looking at Microsoft Active Directory.
Which is better?<indexterm>
<primary>Active Directory</primary>
</indexterm>
</para>
</question>
<answer>
<para><indexterm>
<primary>LDAP</primary>
<secondary>server</secondary>
</indexterm><indexterm>
<primary>Kerberos</primary>
</indexterm><indexterm>
<primary>schema</primary>
</indexterm>
Microsoft Active Directory is an LDAP server that is intricately tied to a Kerberos
infrastructure. Most IT managers who object to LDAP do so because of the fact that
an LDAP server is most often supplied as a raw tool that needs to be configured, and
for which the administrator must create the schema, create the administration tools and
devise the backup and recovery facilities in a site dependent manner. LDAP servers
in general are seen as a high-energy, high-risk facility.
</para>
<para><indexterm>
<primary>management</primary>
</indexterm>
Microsoft Active Directory by comparison is easy to install, configure, and
is supplied with all tools necessary to implement and manage the directory. For sites
that lack a lot of technical competence, Active Directory is a good choice. For sites
that have the technical competence to handle Active Directory well, LDAP is a good
alternative. The real issue that needs to be addressed is what type of solution does
the site want? If management wants a choice to use an alternative, they may want to
consider the options. On the other hand, if management just wants a solution that works,
Microsoft Active Directory is a good solution.
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>
We want to implement a Samba PDC, four Samba BDCs, and 10 Samba servers. Is it possible
to use NIS in place of LDAP?
</para>
</question>
<answer>
<para><indexterm>
<primary>NIS</primary>
</indexterm><indexterm>
<primary>LDAP</primary>
</indexterm><indexterm>
<primary>encrypted passwords</primary>
</indexterm><indexterm>
<primary>synchronized</primary>
</indexterm><indexterm>
<primary>secure account password</primary>
</indexterm><indexterm>
<primary>PDC</primary>
</indexterm><indexterm>
<primary>BDC</primary>
</indexterm>
Yes, it is possible to use NIS in place of LDAP, but there may be problems with keeping
the Windows (SMB) encrypted passwords database correctly synchronized across the entire
network. Workstations (Windows client machines) periodically change their Domain
Membership secure account password. How can you keep changes that are on remote BDCs
synchronized on the PDC?
</para>
<para><indexterm>
<primary>centralized storage</primary>
</indexterm><indexterm>
<primary>management</primary>
</indexterm><indexterm>
<primary>network Identities</primary>
</indexterm>
LDAP is a more elegant solution because it permits centralized storage and management
of all network Identities (user, group and machine accounts) together with all information
Samba needs to provide to network clients and their users.
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>
Are you suggesting that users should not log onto a Domain Member server? If so, why?
</para>
</question>
<answer>
<para><indexterm>
<primary>security</primary>
</indexterm><indexterm>
<primary>data</primary>
<secondary>integrity</secondary>
</indexterm><indexterm>
<primary>mapped drives</primary>
</indexterm>
Many UNIX administrators mock the model that the Personal Computer industry has adopted
as normative since the early days of Novell Netware. One may well argue that the old
perception of the necessity to keep users off file and print servers was a result of
fears concerning the security and integrity of data. It was a simple and generally
effective measure to keep users away from servers, except through mapped drives.
</para>
<para><indexterm>
<primary>user logins</primary>
</indexterm><indexterm>
<primary>risk</primary>
</indexterm><indexterm>
<primary>user errors</primary>
</indexterm><indexterm>
<primary>strategy</primary>
</indexterm><indexterm>
<primary>policy</primary>
</indexterm>
UNIX administrators are fully correct in asserting that UNIX servers and workstations
are identical in terms of the software that is installed. They correctly assert that
in a well secured environment it is safe to store files on a system that has hundreds
of users. But all network administrators must factor into the decision to allow or
reject general user logins to a UNIX system that is principally a file and print
server. One must take account of the risk to operations through simple user errors.
Only then can one begin to appraise the best strategy and adopt a site-specific
policy that best protects the needs of users and of the organization alike.
</para>
<para><indexterm>
<primary>system level logins</primary>
</indexterm>
From experience, it is my recommendation to keep general system level logins to a
practical minimum and to eliminate them if possible. This should not be taken as a
hard rule, though. The better question is, what works best for the site?
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para><indexterm>
<primary>winbind enable local accounts</primary>
</indexterm><indexterm>
<primary>/etc/passwd</primary>
</indexterm><indexterm>
<primary>options list</primary>
</indexterm><indexterm>
<primary>ACL</primary>
</indexterm><indexterm>
<primary>share</primary>
</indexterm>
In my &smb.conf; file, I enabled the parameter <parameter>winbind enable local accounts
</parameter> on all Domain Member servers, but it does not work. The accounts I put in
<filename>/etc/passwd</filename> do not show up in the options list when I try to set an
ACL on a share. What have I done wrong?
</para>
</question>
<answer>
<para><indexterm>
<primary>local users</primary>
</indexterm><indexterm>
<primary>local groups</primary>
</indexterm><indexterm>
<primary>UNIX account</primary>
</indexterm><indexterm>
<primary>getpwnam()</primary>
</indexterm><indexterm>
<primary>getgrgid()</primary>
</indexterm><indexterm>
<primary>Identity resolution</primary>
</indexterm><indexterm>
<primary>failure</primary>
</indexterm><indexterm>
<primary>Domain</primary>
</indexterm>
The manual page for this &smb.conf; file parameter clearly says, <quote>This parameter
controls whether or not winbindd will act as a stand in replacement for the various
account management hooks in smb.conf (for example, add user script). If enabled, winbindd
will support the creation of local users and groups as another source of UNIX account
information available via getpwnam() or getgrgid(), etc...</quote> By default this
parameter is already enabled; therefore, the action you are seeing is a result of a failure
of Identity resolution in the Domain.
</para>
<para><indexterm>
<primary>Domain logons</primary>
</indexterm><indexterm>
<primary>Identity resolution</primary>
</indexterm><indexterm>
<primary>Domain</primary>
<secondary>user</secondary>
</indexterm><indexterm>
<primary>Domain</primary>
<secondary>group</secondary>
</indexterm><indexterm>
<primary>UID</primary>
</indexterm><indexterm>
<primary>GID</primary>
</indexterm>
These are the accounts that are available for Windows network Domain logons. Providing
Identity resolution has been correctly configured on the Domain Controllers, as well as
on Domain Member servers. The Domain user and group identities automatically map
to a valid local UID and GID pair.
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para><indexterm>
<primary>trusted domains</primary>
</indexterm><indexterm>
<primary>domain</primary>
<secondary>trusted</secondary>
</indexterm><indexterm>
<primary>winbind trusted domains only</primary>
</indexterm><indexterm>
<primary>domain members</primary>
</indexterm>
We want to ensure that only users from our own domain plus from trusted domains can use our
Samba servers. In the &smb.conf; file on all servers, we have enabled the <parameter>winbind
trusted domains only</parameter> parameter. We now find that users from trusted domains
cannot access our servers, and users from Windows clients that are not domain members
can also access our servers. Is this a Samba bug?
</para>
</question>
<answer>
<para><indexterm>
<primary>distributed</primary>
</indexterm><indexterm>
<primary>NIS</primary>
</indexterm><indexterm>
<primary>rsync</primary>
</indexterm><indexterm>
<primary>LDAP</primary>
</indexterm><indexterm>
<primary>winbindd</primary>
</indexterm><indexterm>
<primary>/etc/passwd</primary>
</indexterm>
The manual page for this <parameter>winbind trusted domains only</parameter> parameter says,
<quote>This parameter is designed to allow Samba servers that are members of a Samba controlled
domain to use UNIX accounts distributed vi NIS, rsync, or LDAP as the UIDs for winbindd users
in the hosts primary domain. Therefore, the user <constant>SAMBA\user1</constant> would be
mapped to the account <constant>user1</constant> in <filename>/etc/passwd</filename> instead
of allocating a new UID for him or her.</quote> This would clearly suggest that you are trying
to use this parameter inappropriately.
</para>
<para><indexterm>
<primary>valid users</primary>
</indexterm>
A far better solution would be to use the <parameter>valid users</parameter> by specifying
precisely the Domain users and groups that should be permitted access to the shares. You could,
for example, set the following parameters:
<screen>
[demoshare]
path = /export/demodata
valid users = @"Domain Users", @"OTHERDOMAIN\Domain Users"
</screen>
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>
What are the benefits of using LDAP for my Domain Member servers?
</para>
</question>
<answer>
<para><indexterm>
<primary>LDAP</primary>
</indexterm><indexterm>
<primary>benefit</primary>
</indexterm><indexterm>
<primary>UID</primary>
</indexterm><indexterm>
<primary>GID</primary>
</indexterm><indexterm>
<primary>Domain Controllers</primary>
</indexterm><indexterm>
<primary>Domain Member servers</primary>
</indexterm><indexterm>
<primary>copy</primary>
</indexterm><indexterm>
<primary>replicate</primary>
</indexterm><indexterm>
<primary>identity</primary>
</indexterm>
The key benefit of using LDAP is that the UID of all users and the GID of all groups
are globally consistent on Domain Controllers as well as on Domain Member servers.
This means that it is possible to copy/replicate files across servers without
loss of identity.
</para>
<para><indexterm>
<primary>Identity resolution</primary>
</indexterm><indexterm>
<primary>winbind</primary>
</indexterm><indexterm>
<primary>IDMAP backend</primary>
</indexterm><indexterm>
<primary>LDAP</primary>
</indexterm><indexterm>
<primary>Domain Controllers</primary>
</indexterm><indexterm>
<primary>Domain Member</primary>
<secondary>servers</secondary>
</indexterm><indexterm>
<primary>Posix</primary>
</indexterm><indexterm>
<primary>account information</primary>
</indexterm>
When use is made of account Identity resolution via winbind, even when an IDMAP backend
is stored in LDAP, the UID/GID on Domain Member servers is consistent, but differs
from the ID that the user/group has on Domain Controllers. The winbind allocated UID/GID
that is stored in LDAP (or locally) will be in the numeric range specified in the <parameter>
idmap uid/gid</parameter> in the &smb.conf; file. On Domain Controllers, the UID/GID is
that of the Posix value assigned in the LDAP directory as part of the Posix account information.
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>
Is proper DNS operation necessary for Samba-3 plus LDAP? If so, what must I put into
my DNS configuration?
</para>
</question>
<answer>
<para><indexterm>
<primary>DNS</primary>
<secondary>configuration</secondary>
</indexterm><indexterm>
<primary>DNS</primary>
<secondary>lookup</secondary>
</indexterm><indexterm>
<primary>hosts</primary>
</indexterm><indexterm>
<primary>/etc/nsswitch.conf</primary>
</indexterm><indexterm>
<primary>NSS</primary>
</indexterm><indexterm>
<primary>/etc/hosts</primary>
</indexterm><indexterm>
<primary>WINS</primary>
<secondary>lookup</secondary>
</indexterm>
Samba depends on correctly functioning resolution of host names to their IP address. Samba
makes no direct DNS lookup calls, but rather redirects all name to address calls via the
<command>getXXXbyXXX()</command> function calls. The configuration of the <constant>hosts</constant>
entry in the NSS <filename>/etc/nsswitch.conf</filename> file determines how the underlying
resolution process is implemented. If the <constant>hosts</constant> entry in your NSS
control file says:
<screen>
hosts: files dns wins
</screen>
This means that a host name lookup first tries the <filename>/etc/hosts</filename>.
If this fails to resolve, it attempts a DNS lookup and if that fails, it tries a
WINS lookup.
</para>
<para><indexterm>
<primary>NetBIOS</primary>
</indexterm><indexterm>
<primary>TCP/IP</primary>
</indexterm><indexterm>
<primary>name resolution</primary>
</indexterm>
The addition of the WINS-based name lookup makes sense only if NetBIOS over TCP/IP has
been enabled on all Windows clients. Where NetBIOS over TCP/IP has been disabled, DNS
is the preferred name resolution technology. This usually makes most sense when Samba
is a client of an Active Directory Domain, where NetBIOS use has been disabled. In this
case, the Windows 200x auto-registers all locator records it needs with its own DNS
server/s.
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para>
Our Windows 2003 Server Active Directory Domain runs with NetBIOS disabled. Can we
use Samba-3 with that configuration?
</para>
</question>
<answer>
<para>
Yes.
</para>
</answer>
</qandaentry>
<qandaentry>
<question>
<para><indexterm>
<primary>net</primary>
<secondary>ads</secondary>
<tertiary>join</tertiary>
</indexterm><indexterm>
<primary>net</primary>
<secondary>rpc</secondary>
<tertiary>join</tertiary>
</indexterm>
When I tried to execute <quote>net ads join</quote>, I got no output. It did not work, so
I think that it failed. I then executed <quote>net rpc join</quote> and that worked fine.
That is okay, isn't it?
</para>
</question>
<answer>
<para><indexterm>
<primary>Kerberos</primary>
</indexterm><indexterm>
<primary>authentication</primary>
</indexterm>
No. This is not okay. It means that your Samba-3 client has joined the ADS Domain as
a Windows NT4 client, and Samba-3 will not be using Kerberos-based authentication.
</para>
</answer>
</qandaentry>
</qandaset>
</sect1>
</chapter>
View Git Blame Copy Permalink