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<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 7. Domain Membership</title><link rel="stylesheet" href="samba.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.60.1"><link rel="home" href="index.html" title="SAMBA Project Documentation"><link rel="up" href="type.html" title="Part II. Server Configuration Basics"><link rel="previous" href="samba-bdc.html" title="Chapter 6. Backup Domain Control"><link rel="next" href="StandAloneServer.html" title="Chapter 8. Stand-Alone Servers"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 7. Domain Membership</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="samba-bdc.html">Prev</a> </td><th width="60%" align="center">Part II. Server Configuration Basics</th><td width="20%" align="right"> <a accesskey="n" href="StandAloneServer.html">Next</a></td></tr></table><hr></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="domain-member"></a>Chapter 7. Domain Membership</h2></div><div><div class="author"><h3 class="author"><span class="firstname">John</span> <span class="othername">H.</span> <span class="surname">Terpstra</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><tt class="email"><<a href="mailto:jht@samba.org">jht@samba.org</a>></tt></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Jeremy</span> <span class="surname">Allison</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><tt class="email"><<a href="mailto:jra@samba.org">jra@samba.org</a>></tt></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Gerald</span> <span class="othername">(Jerry)</span> <span class="surname">Carter</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><tt class="email"><<a href="mailto:jerry@samba.org">jerry@samba.org</a>></tt></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Andrew</span> <span class="surname">Tridgell</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><tt class="email"><<a href="mailto:tridge@samba.org">tridge@samba.org</a>></tt></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Jelmer</span> <span class="othername">R.</span> <span class="surname">Vernooij</span></h3><div class="affiliation"><span class="orgname">The Samba Team<br></span><div class="address"><p><tt class="email"><<a href="mailto:jelmer@samba.org">jelmer@samba.org</a>></tt></p></div></div></div></div></div><div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><a href="domain-member.html#id2895146">Features and Benefits</a></dt><dt><a href="domain-member.html#id2894718">MS Windows Workstation/Server Machine Trust Accounts</a></dt><dd><dl><dt><a href="domain-member.html#id2894878">Manual Creation of Machine Trust Accounts</a></dt><dt><a href="domain-member.html#id2896660">Using NT4 Server Manager to Add Machine Accounts to the Domain</a></dt><dt><a href="domain-member.html#id2896857">"On-the-Fly" Creation of Machine Trust Accounts</a></dt><dt><a href="domain-member.html#id2896912">Making an MS Windows Workstation or Server a Domain Member</a></dt></dl></dd><dt><a href="domain-member.html#id2897057">Domain Member Server</a></dt><dd><dl><dt><a href="domain-member.html#id2897105">Joining an NT4 type Domain with Samba-3</a></dt><dt><a href="domain-member.html#id2899703">Why is this better than security = server?</a></dt></dl></dd><dt><a href="domain-member.html#ads-member">Samba ADS Domain Membership</a></dt><dd><dl><dt><a href="domain-member.html#id2899841">Setup your smb.conf</a></dt><dt><a href="domain-member.html#id2899924">Setup your /etc/krb5.conf</a></dt><dt><a href="domain-member.html#ads-create-machine-account">Create the computer account</a></dt><dt><a href="domain-member.html#ads-test-server">Test your server setup</a></dt><dt><a href="domain-member.html#ads-test-smbclient">Testing with smbclient</a></dt><dt><a href="domain-member.html#id2900266">Notes</a></dt></dl></dd><dt><a href="domain-member.html#id2900288">Common Errors</a></dt><dd><dl><dt><a href="domain-member.html#id2900310">Can Not Add Machine Back to Domain</a></dt><dt><a href="domain-member.html#id2900342">Adding Machine to Domain Fails</a></dt></dl></dd></dl></div><p>
Domain Membership is a subject of vital concern, Samba must be able to
participate as a member server in a Microsoft Domain security context, and
Samba must be capable of providing Domain machine member trust accounts,
otherwise it would not be capable of offering a viable option for many users.
</p><p>
This chapter covers background information pertaining to domain membership,
Samba configuration for it, and MS Windows client procedures for joining a
domain. Why is this necessary? Because both are areas in which there exists
within the current MS Windows networking world and particularly in the
Unix/Linux networking and administration world, a considerable level of
mis-information, incorrect understanding, and a lack of knowledge. Hopefully
this chapter will fill the voids.
</p><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2895146"></a>Features and Benefits</h2></div></div><div></div></div><p>
MS Windows workstations and servers that want to participate in domain
security need to
be made Domain members. Participating in Domain security is often called
<span class="emphasis"><em>Single Sign On</em></span> or <span class="acronym">SSO</span> for short. This
chapter describes the process that must be followed to make a workstation
(or another server - be it an <span class="application">MS Windows NT4 / 200x</span>
server) or a Samba server a member of an MS Windows Domain security context.
</p><p>
Samba-3 can join an MS Windows NT4 style domain as a native member server, an
MS Windows Active Directory Domain as a native member server, or a Samba Domain
Control network.
</p><p>
Domain membership has many advantages:
</p><div class="itemizedlist"><ul type="disc"><li><p>
MS Windows workstation users get the benefit of SSO
</p></li><li><p>
Domain user access rights and file ownership / access controls can be set
from the single Domain SAM (Security Accounts Management) database
(works with Domain member servers as well as with MS Windows workstations
that are domain members)
</p></li><li><p>
Only <span class="application">MS Windows NT4 / 200x / XP Professional</span>
workstations that are Domain members
can use network logon facilities
</p></li><li><p>
Domain Member workstations can be better controlled through the use of
Policy files (<tt class="filename">NTConfig.POL</tt>) and Desktop Profiles.
</p></li><li><p>
Through the use of logon scripts users can be given transparent access to network
applications that run off application servers
</p></li><li><p>
Network administrators gain better application and user access management
abilities because there is no need to maintain user accounts on any network
client or server, other than the central Domain database
(either NT4/Samba SAM style Domain, NT4 Domain that is back ended with an
LDAP directory, or via an Active Directory infrastructure)
</p></li></ul></div></div><div xmlns:ns7="" class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2894718"></a>MS Windows Workstation/Server Machine Trust Accounts</h2></div></div><div></div></div><p>
A machine trust account is an account that is used to authenticate a client
machine
(rather than a user) to the Domain Controller server. In Windows terminology,
this is known as a "Computer Account."
</p><p>
The password of a machine trust account acts as the shared secret for
secure communication with the Domain Controller. This is a security
feature to prevent an unauthorized machine with the same NetBIOS name
from joining the domain and gaining access to domain user/group
accounts. Windows NT, 200x, XP Professional clients use machine trust
accounts, but Windows 9x / Me / XP Home clients do not. Hence, a
Windows 9x / Me / XP Home client is never a true member of a domain
because it does not possess a machine trust account, and thus has no
shared secret with the domain controller.
</p><p>
A Windows NT4 PDC stores each machine trust account in the Windows Registry.
The introduction of MS Windows 2000 saw the introduction of Active Directory,
the new repository for machine trust accounts.
</p><ns7:p>
A Samba PDC, however, stores each machine trust account in two parts,
as follows:
</ns7:p><div class="itemizedlist"><ul type="disc"><li><p>
A Domain Security Account (stored in the
<i class="parameter"><tt>passdb backend</tt></i> that has been configured in the
<tt class="filename">smb.conf</tt> file. The precise nature of the account information that is
stored depends on the type of backend database that has been chosen.
</p><p>
The older format of this data is the <tt class="filename">smbpasswd</tt> database
which contains the unix login ID, the Unix user identifier (UID), and the
LanMan and NT encrypted passwords. There is also some other information in
this file that we do not need to concern ourselves with here.
</p><p>
The two newer database types are called <span class="emphasis"><em>ldapsam</em></span>,
<span class="emphasis"><em>tdbsam</em></span>. Both store considerably more data than the
older <tt class="filename">smbpasswd</tt> file did. The extra information
enables new user account controls to be used.
</p></li><li><p>
A corresponding Unix account, typically stored in
<tt class="filename">/etc/passwd</tt>. Work is in progress to allow a
simplified mode of operation that does not require Unix user accounts, but
this may not be a feature of the early releases of Samba-3.
</p></li></ul></div><ns7:p>
</ns7:p><p>
There are three ways to create machine trust accounts:
</p><div class="itemizedlist"><ul type="disc"><li><p>
Manual creation from the Unix/Linux command line. Here, both the Samba and
corresponding Unix account are created by hand.
</p></li><li><p>
Using the MS Windows NT4 Server Manager (either from an NT4 Domain member
server, or using the Nexus toolkit available from the Microsoft web site.
This tool can be run from any MS Windows machine so long as the user is
logged on as the administrator account.
</p></li><li><p>
"On-the-fly" creation. The Samba machine trust account is automatically
created by Samba at the time the client is joined to the domain.
(For security, this is the recommended method.) The corresponding Unix
account may be created automatically or manually.
</p></li></ul></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2894878"></a>Manual Creation of Machine Trust Accounts</h3></div></div><div></div></div><p>
The first step in manually creating a machine trust account is to manually
create the corresponding Unix account in <tt class="filename">/etc/passwd</tt>.
This can be done using <b class="command">vipw</b> or another 'add user' command
that is normally used to create new Unix accounts. The following is an example for a Linux based Samba server:
</p><p>
<tt class="prompt">root# </tt><b class="userinput"><tt>/usr/sbin/useradd -g 100 -d /dev/null -c <i class="replaceable"><tt>"machine nickname"</tt></i> -s /bin/false <i class="replaceable"><tt>machine_name</tt></i>$ </tt></b>
</p><p>
<tt class="prompt">root# </tt><b class="userinput"><tt>passwd -l <i class="replaceable"><tt>machine_name</tt></i>$</tt></b>
</p><p>
On *BSD systems, this can be done using the <b class="command">chpass</b> utility:
</p><p>
<tt class="prompt">root# </tt><b class="userinput"><tt>chpass -a "<i class="replaceable"><tt>machine_name</tt></i>$:*:101:100::0:0:Workstation <i class="replaceable"><tt>machine_name</tt></i>:/dev/null:/sbin/nologin"</tt></b>
</p><p>
The <tt class="filename">/etc/passwd</tt> entry will list the machine name
with a "$" appended, won't have a password, will have a null shell and no
home directory. For example a machine named 'doppy' would have an
<tt class="filename">/etc/passwd</tt> entry like this:
</p><pre class="programlisting">
doppy$:x:505:501:<i class="replaceable"><tt>machine_nickname</tt></i>:/dev/null:/bin/false
</pre><p>
Above, <i class="replaceable"><tt>machine_nickname</tt></i> can be any
descriptive name for the client, i.e., BasementComputer.
<i class="replaceable"><tt>machine_name</tt></i> absolutely must be the NetBIOS
name of the client to be joined to the domain. The "$" must be
appended to the NetBIOS name of the client or Samba will not recognize
this as a machine trust account.
</p><p>
Now that the corresponding Unix account has been created, the next step is to create
the Samba account for the client containing the well-known initial
machine trust account password. This can be done using the <a href="smbpasswd.8.html" target="_top"><b class="command">smbpasswd(8)</b></a> command
as shown here:
</p><ns7:p>
</ns7:p><pre class="screen">
<tt class="prompt">root# </tt><b class="userinput"><tt>smbpasswd -a -m <i class="replaceable"><tt>machine_name</tt></i></tt></b>
</pre><ns7:p>>
</ns7:p><p>
where <i class="replaceable"><tt>machine_name</tt></i> is the machine's NetBIOS
name. The RID of the new machine account is generated from the UID of
the corresponding Unix account.
</p><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Join the client to the domain immediately</h3><p>
Manually creating a machine trust account using this method is the
equivalent of creating a machine trust account on a Windows NT PDC using
the <span class="application">Server Manager</span>. From the time at which the
account is created to the time which the client joins the domain and
changes the password, your domain is vulnerable to an intruder joining
your domain using a machine with the same NetBIOS name. A PDC inherently
trusts members of the domain and will serve out a large degree of user
information to such clients. You have been warned!
</p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2896660"></a>Using NT4 Server Manager to Add Machine Accounts to the Domain</h3></div></div><div></div></div><p>
If the machine from which you are trying to manage the domain is an
<span class="application">MS Windows NT4 workstation</span>
then the tool of choice is the package called <b class="command">SRVTOOLS.EXE</b>.
When executed in the target directory this will unpack
<b class="command">SrvMge.exe</b> and <b class="command">UsrMgr.exe</b> (both are
Domain Management tools for MS Windows NT4 workstation.
</p><p>
If your workstation is any other MS Windows product you should download the
<b class="command">Nexus.exe</b> package from the Microsoft web site. When executed
from the target directory this will unpack the same tools but for use on
<span class="application">MS Windows 9x/Me/200x/XP</span>.
</p><p>
Launch the <b class="command">srvmgr.exe</b> (Server Manager for Domains) and follow these steps:
</p><div class="procedure"><p class="title"><b>Procedure 7.1. Server Manager Account Machine Account Management</b></p><ol type="1"><li><p>
From the menu select <span class="guimenu">Computer</span>
</p></li><li><p>
Click on <span class="guimenuitem">Select Domain</span>
</p></li><li><p>
Click on the name of the domain you wish to administer in the
<span class="guilabel">Select Domain</span> panel and then click
<span class="guibutton">OK</span>.
</p></li><li><p>
Again from the menu select <span class="guimenu">Computer</span>
</p></li><li><p>
Select <span class="guimenuitem">Add to Domain</span>
</p></li><li><p>
In the dialog box, click on the radio button to
<span class="guilabel">Add NT Workstation of Server</span>, then
enter the machine name in the field provided, then click the
<span class="guibutton">Add</span> button.
</p></li></ol></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2896857"></a>"On-the-Fly" Creation of Machine Trust Accounts</h3></div></div><div></div></div><p>
The second (and recommended) way of creating machine trust accounts is
simply to allow the Samba server to create them as needed when the client
is joined to the domain.
</p><p>Since each Samba machine trust account requires a corresponding Unix account, a method
for automatically creating the Unix account is usually supplied; this requires configuration of the
<a href="smb.conf.5.html#ADDMACHINESCRIPT" target="_top">add machine script</a> option in
<tt class="filename">smb.conf</tt>. This method is not required, however; corresponding Unix
accounts may also be created manually.
</p><p>
Below is an example for a RedHat Linux system.
</p><pre class="programlisting">
[global]
# <...remainder of parameters...>
add machine script = /usr/sbin/useradd -d /dev/null -g 100 -s /bin/false -M %u
</pre></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2896912"></a>Making an MS Windows Workstation or Server a Domain Member</h3></div></div><div></div></div><p>
The procedure for making an MS Windows workstation of server a member of the domain varies
with the version of Windows:
</p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2896925"></a>Windows 200x XP Professional</h4></div></div><div></div></div><p>
When the user elects to make the client a domain member, Windows 200x prompts for
an account and password that has privileges to create machine accounts in the domain.
A Samba administrative account (i.e., a Samba account that has root privileges on the
Samba server) must be entered here; the operation will fail if an ordinary user
account is given.
</p><p>
Note: For security reasons the password for this administrative account should be set
to a password that is other than that used for the root user in the
<tt class="filename">/etc/passwd</tt>.
</p><p>
The name of the account that is used to create domain member machine accounts can be
anything the network administrator may choose. If it is other than <span class="emphasis"><em>root</em></span>
then this is easily mapped to root using the file pointed to be the <tt class="filename">smb.conf</tt> parameter
<i class="parameter"><tt>username map = /etc/samba/smbusers</tt></i>.
</p><p>
The session key of the Samba administrative account acts as an
encryption key for setting the password of the machine trust
account. The machine trust account will be created on-the-fly, or
updated if it already exists.
</p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2896993"></a>Windows NT4</h4></div></div><div></div></div><p>
If the machine trust account was created manually, on the
Identification Changes menu enter the domain name, but do not
check the box <span class="guilabel">Create a Computer Account in the Domain</span>.
In this case, the existing machine trust account is used to join the machine
to the domain.
</p><p>
If the machine trust account is to be created
on-the-fly, on the Identification Changes menu enter the domain
name, and check the box <span class="guilabel">Create a Computer Account in the
Domain</span>. In this case, joining the domain proceeds as above
for Windows 2000 (i.e., you must supply a Samba administrative account when
prompted).
</p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2897034"></a>Samba</h4></div></div><div></div></div><p>Joining a samba client to a domain is documented in
the <a href="domain-member.html" title="Chapter 7. Domain Membership">Domain Member</a> chapter.
</p></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2897057"></a>Domain Member Server</h2></div></div><div></div></div><p>
This mode of server operation involves the samba machine being made a member
of a domain security context. This means by definition that all user
authentication will be done from a centrally defined authentication regime.
The authentication regime may come from an NT3/4 style (old domain technology)
server, or it may be provided from an Active Directory server (ADS) running on
MS Windows 2000 or later.
</p><p>
<span class="emphasis"><em>
Of course it should be clear that the authentication back end itself could be
from any distributed directory architecture server that is supported by Samba.
This can be LDAP (from OpenLDAP), or Sun's iPlanet, of NetWare Directory
Server, etc.
</em></span>
</p><p>
Please refer to the <a href="samba-pdc.html" title="Chapter 5. Domain Control">Domain Control chapter</a>
for more information regarding how to create a domain
machine account for a domain member server as well as for information
regarding how to enable the samba domain member machine to join the domain and
to be fully trusted by it.
</p><div xmlns:ns8="" class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2897105"></a>Joining an NT4 type Domain with Samba-3</h3></div></div><div></div></div><ns8:p>
</ns8:p><div class="table"><a name="id2897115"></a><p class="title"><b>Table 7.1. Assumptions</b></p><table summary="Assumptions" border="1"><colgroup><col><col></colgroup><tbody><tr><td align="left">NetBIOS name:</td><td align="left">SERV1</td></tr><tr><td align="left">Win2K/NT domain name:</td><td align="left">DOM</td></tr><tr><td align="left">Domain's PDC NetBIOS name:</td><td align="left">DOMPDC</td></tr><tr><td align="left">Domain's BDC NetBIOS names:</td><td align="left">DOMBDC1 and DOMBDC2</td></tr></tbody></table></div><ns8:p>
</ns8:p><p>
First, you must edit your <tt class="filename">smb.conf</tt> file to tell Samba it should
now use domain security.
</p><p>
Change (or add) your <a href="smb.conf.5.html#SECURITY" target="_top">
<i class="parameter"><tt>security</tt></i></a> line in the [global] section
of your <tt class="filename">smb.conf</tt> to read:
</p><ns8:p>
</ns8:p><pre class="programlisting">
security = domain
</pre><ns8:p>
</ns8:p><p>
Next change the <a href="smb.conf.5.html#WORKGROUP" target="_top"><i class="parameter"><tt>
workgroup</tt></i></a> line in the <i class="parameter"><tt>[global]</tt></i>
section to read:
</p><ns8:p>
</ns8:p><pre class="programlisting">
workgroup = DOM
</pre><ns8:p>
</ns8:p><p>
as this is the name of the domain we are joining.
</p><p>
You must also have the parameter <a href="smb.conf.5.html#ENCRYPTPASSWORDS" target="_top">
<i class="parameter"><tt>encrypt passwords</tt></i></a> set to <tt class="constant">yes
</tt> in order for your users to authenticate to the NT PDC.
</p><p>
Finally, add (or modify) a <a href="smb.conf.5.html#PASSWORDSERVER" target="_top">
<i class="parameter"><tt>password server</tt></i></a> line in the [global]
section to read:
</p><ns8:p>
</ns8:p><pre class="programlisting">
password server = DOMPDC DOMBDC1 DOMBDC2
</pre><ns8:p>
</ns8:p><p>
These are the primary and backup domain controllers Samba
will attempt to contact in order to authenticate users. Samba will
try to contact each of these servers in order, so you may want to
rearrange this list in order to spread out the authentication load
among domain controllers.
</p><p>
Alternatively, if you want smbd to automatically determine
the list of Domain controllers to use for authentication, you may
set this line to be:
</p><ns8:p>
</ns8:p><pre class="programlisting">
password server = *
</pre><ns8:p>
</ns8:p><p>
This method, allows Samba to use exactly the same mechanism that NT does. This
method either broadcasts or uses a WINS database in order to
find domain controllers to authenticate against.
</p><p>
In order to actually join the domain, you must run this command:
</p><ns8:p>
</ns8:p><pre class="screen">
<tt class="prompt">root# </tt><b class="userinput"><tt>net join -S DOMPDC -U<i class="replaceable"><tt>Administrator%password</tt></i></tt></b>
</pre><ns8:p>
</ns8:p><p>
If the <tt class="option">-S DOMPDC</tt> argument is not given then
the domain name will be obtained from <tt class="filename">smb.conf</tt>.
</p><p>
As we are joining the domain DOM and the PDC for that domain
(the only machine that has write access to the domain SAM database)
is DOMPDC. The <i class="replaceable"><tt>Administrator%password</tt></i> is
the login name and password for an account which has the necessary
privilege to add machines to the domain. If this is successful
you will see the message:
</p><p>
<tt class="computeroutput">Joined domain DOM.</tt>
or <tt class="computeroutput">Joined 'SERV1' to realm 'MYREALM'</tt>
</p><p>
in your terminal window. See the <a href="net.8.html" target="_top">
net(8)</a> man page for more details.
</p><p>
This process joins the server to the domain without having to create the machine
trust account on the PDC beforehand.
</p><p>
This command goes through the machine account password
change protocol, then writes the new (random) machine account
password for this Samba server into a file in the same directory
in which an smbpasswd file would be stored - normally :
</p><p>
<tt class="filename">/usr/local/samba/private/secrets.tdb</tt>
</p><p>
This file is created and owned by root and is not
readable by any other user. It is the key to the domain-level
security for your system, and should be treated as carefully
as a shadow password file.
</p><p>
Finally, restart your Samba daemons and get ready for
clients to begin using domain security!
</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2899703"></a>Why is this better than security = server?</h3></div></div><div></div></div><p>
Currently, domain security in Samba doesn't free you from
having to create local Unix users to represent the users attaching
to your server. This means that if domain user <tt class="constant">DOM\fred
</tt> attaches to your domain security Samba server, there needs
to be a local Unix user fred to represent that user in the Unix
filesystem. This is very similar to the older Samba security mode
<a href="smb.conf.5.html#SECURITYEQUALSSERVER" target="_top">security = server</a>,
where Samba would pass through the authentication request to a Windows
NT server in the same way as a Windows 95 or Windows 98 server would.
</p><p>
Please refer to the <a href="winbind.html" target="_top">Winbind
paper</a> for information on a system to automatically
assign UNIX uids and gids to Windows NT Domain users and groups.
</p><p>
The advantage to domain-level security is that the
authentication in domain-level security is passed down the authenticated
RPC channel in exactly the same way that an NT server would do it. This
means Samba servers now participate in domain trust relationships in
exactly the same way NT servers do (i.e., you can add Samba servers into
a resource domain and have the authentication passed on from a resource
domain PDC to an account domain PDC).
</p><p>
In addition, with <i class="parameter"><tt>security = server</tt></i> every Samba
daemon on a server has to keep a connection open to the
authenticating server for as long as that daemon lasts. This can drain
the connection resources on a Microsoft NT server and cause it to run
out of available connections. With <i class="parameter"><tt>security = domain</tt></i>,
however, the Samba daemons connect to the PDC/BDC only for as long
as is necessary to authenticate the user, and then drop the connection,
thus conserving PDC connection resources.
</p><p>
And finally, acting in the same manner as an NT server
authenticating to a PDC means that as part of the authentication
reply, the Samba server gets the user identification information such
as the user SID, the list of NT groups the user belongs to, etc.
</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
Much of the text of this document
was first published in the Web magazine
<a href="http://www.linuxworld.com" target="_top">LinuxWorld</a> as the article <a href="http://www.linuxworld.com/linuxworld/lw-1998-10/lw-10-samba.html" target="_top">Doing
the NIS/NT Samba</a>.
</p></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="ads-member"></a>Samba ADS Domain Membership</h2></div></div><div></div></div><p>
This is a rough guide to setting up Samba 3.0 with kerberos authentication against a
Windows2000 KDC.
</p><div xmlns:ns9="" class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2899841"></a>Setup your <tt class="filename">smb.conf</tt></h3></div></div><div></div></div><p>
You must use at least the following 3 options in <tt class="filename">smb.conf</tt>:
</p><pre class="programlisting">
realm = your.kerberos.REALM
security = ADS
encrypt passwords = yes
</pre><ns9:p>
In case samba can't figure out your ads server using your realm name, use the
<i class="parameter"><tt>ads server</tt></i> option in <tt class="filename">smb.conf</tt>:
</ns9:p><pre class="programlisting">
ads server = your.kerberos.server
</pre><ns9:p>
</ns9:p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
You do <span class="emphasis"><em>not</em></span> need a smbpasswd file, and older clients will be authenticated as
if <i class="parameter"><tt>security = domain</tt></i>, although it won't do any harm and
allows you to have local users not in the domain. It is expected that the above
required options will change soon when active directory integration will get
better.
</p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2899924"></a>Setup your <tt class="filename">/etc/krb5.conf</tt></h3></div></div><div></div></div><p>
The minimal configuration for <tt class="filename">krb5.conf</tt> is:
</p><pre class="programlisting">
[realms]
YOUR.KERBEROS.REALM = {
kdc = your.kerberos.server
}
</pre><p>
Test your config by doing a <b class="userinput"><tt>kinit
<i class="replaceable"><tt>USERNAME</tt></i>@<i class="replaceable"><tt>REALM</tt></i></tt></b> and
making sure that your password is accepted by the Win2000 KDC.
</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
The realm must be uppercase or you will get <span class="errorname">Cannot find KDC for
requested realm while getting initial credentials</span> error
</p></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
Time between the two servers must be synchronized. You will get a
<span class="errorname">kinit(v5): Clock skew too great while getting initial credentials</span>
if the time difference is more than five minutes.
</p></div><p>
You also must ensure that you can do a reverse DNS lookup on the IP
address of your KDC. Also, the name that this reverse lookup maps to
must either be the netbios name of the KDC (ie. the hostname with no
domain attached) or it can alternatively be the netbios name
followed by the realm.
</p><p>
The easiest way to ensure you get this right is to add a
<tt class="filename">/etc/hosts</tt> entry mapping the IP address of your KDC to
its netbios name. If you don't get this right then you will get a
<span class="errorname">local error</span> when you try to join the realm.
</p><p>
If all you want is kerberos support in <span class="application">smbclient</span> then you can skip
straight to <a href="domain-member.html#ads-test-smbclient" title="Testing with smbclient">Test with <span class="application">smbclient</span></a> now.
<a href="domain-member.html#ads-create-machine-account" title="Create the computer account">Creating a computer account</a>
and <a href="domain-member.html#ads-test-server" title="Test your server setup">testing your servers</a>
is only needed if you want kerberos support for <span class="application">smbd</span> and <span class="application">winbindd</span>.
</p></div><div xmlns:ns10="" class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="ads-create-machine-account"></a>Create the computer account</h3></div></div><div></div></div><ns10:p>
As a user that has write permission on the Samba private directory
(usually root) run:
</ns10:p><pre class="programlisting">
<b class="userinput"><tt>net join -U Administrator%password</tt></b>
</pre><ns10:p>
</ns10:p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2900115"></a>Possible errors</h4></div></div><div></div></div><ns10:p>
</ns10:p><div class="variablelist"><dl><dt><span class="term"><span class="errorname">ADS support not compiled in</span></span></dt><dd><p>Samba must be reconfigured (remove config.cache) and recompiled
(make clean all install) after the kerberos libs and headers are installed.
</p></dd><dt><span class="term"><span class="errorname">net join prompts for user name</span></span></dt><dd><p>You need to login to the domain using <b class="userinput"><tt>kinit
<i class="replaceable"><tt>USERNAME</tt></i>@<i class="replaceable"><tt>REALM</tt></i></tt></b>.
<i class="replaceable"><tt>USERNAME</tt></i> must be a user who has rights to add a machine
to the domain. </p></dd></dl></div><ns10:p>
</ns10:p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="ads-test-server"></a>Test your server setup</h3></div></div><div></div></div><p>
If the join was successful, you will see a new computer account with the
NetBIOS name of your Samba server in Active Directory (in the "Computers"
folder under Users and Computers.
</p><p>
On a Windows 2000 client try <b class="userinput"><tt>net use * \\server\share</tt></b>. You should
be logged in with kerberos without needing to know a password. If
this fails then run <b class="userinput"><tt>klist tickets</tt></b>. Did you get a ticket for the
server? Does it have an encoding type of DES-CBC-MD5 ?
</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="ads-test-smbclient"></a>Testing with <span class="application">smbclient</span></h3></div></div><div></div></div><p>
On your Samba server try to login to a Win2000 server or your Samba
server using <span class="application">smbclient</span> and kerberos. Use <span class="application">smbclient</span> as usual, but
specify the <i class="parameter"><tt>-k</tt></i> option to choose kerberos authentication.
</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2900266"></a>Notes</h3></div></div><div></div></div><p>
You must change administrator password at least once after DC
install, to create the right encoding types
</p><p>
W2k doesn't seem to create the _kerberos._udp and _ldap._tcp in
their defaults DNS setup. Maybe fixed in service packs?
</p></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2900288"></a>Common Errors</h2></div></div><div></div></div><p>
In the process of adding / deleting / re-adding domain member machine accounts there are
many traps for the unwary player and there are many "little" things that can go wrong.
It is particularly interesting how often subscribers on the samba mailing list have concluded
after repeated failed attempts to add a machine account that it is necessary to "re-install"
MS Windows on t he machine. In truth, it is seldom necessary to reinstall because of this type
of problem. The real solution is often very simple, and with understanding of how MS Windows
networking functions. easily overcome.
</p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2900310"></a>Can Not Add Machine Back to Domain</h3></div></div><div></div></div><p>
<span class="emphasis"><em>Problem:</em></span> A Windows workstation was reinstalled. The original domain machine
account was deleted and added immediately. The workstation will not join the domain if I use
the same machine name. Attempts to add the machine fail with a message that the machine already
exists on the network - I know it doen't. Why is this failing?
</p><p>
The original name is still in the NetBIOS name cache and must expire after machine account
deletion BEFORE adding that same name as a domain member again. The best advice is to delete
the old account and then to add the machine with a new name.
</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2900342"></a>Adding Machine to Domain Fails</h3></div></div><div></div></div><p>
Adding a Windows 200x or XP Professional machine to the Samba PDC Domain fails with a
message that, <span class="errorname">The machine could not be added at this time, there is a network problem.
Please try again later.</span> Why?
</p><p>
You should check that there is an <i class="parameter"><tt>add machine script</tt></i> in your <tt class="filename">smb.conf</tt>
file. If there is not, please add one that is appropriate for your OS platform. If a script
has been defined you will need to debug it's operation. Increase the <i class="parameter"><tt>log level</tt></i>
in the <tt class="filename">smb.conf</tt> file to level 10, then try to rejoin the domain. Check the logs to see which
operation is failing.
</p><p>
Possible causes include:
</p><div class="itemizedlist"><ul type="disc"><li><p>
The script does not actually exist, or could not be located in the path specified.
</p><p>
<span class="emphasis"><em>Corrective Action:</em></span> Fix it. Make sure that when run manually
that the script will add both the Unix system account _and_ the Samba SAM account.
</p></li><li><p>
The machine could not be added to the Unix system accounts file <tt class="filename">/etc/passwd</tt>
</p><p>
<span class="emphasis"><em>Corrective Action:</em></span> Check that the machine name is a legal Unix
system account name. ie: If the Unix utility <b class="command">useradd</b> is called
then make sure that the machine name you are trying to add can be added using this
tool. <b class="command">Useradd</b> on some systems will not allow any upper case characters
nor will it allow spaces in the name.
</p></li></ul></div></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="samba-bdc.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="type.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="StandAloneServer.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 6. Backup Domain Control </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 8. Stand-Alone Servers</td></tr></table></div></body></html>
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