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1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 6. Domain Membership</title><link rel="stylesheet" href="../samba.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.74.0"><link rel="home" href="index.html" title="The Official Samba 3.2.x HOWTO and Reference Guide"><link rel="up" href="type.html" title="Part II. Server Configuration Basics"><link rel="prev" href="samba-bdc.html" title="Chapter 5. Backup Domain Control"><link rel="next" href="StandAloneServer.html" title="Chapter 7. Standalone 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 6. 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 6. Domain Membership</h2></div><div><div class="author"><h3 class="author"><span class="firstname">John</span> <span class="othername">H.</span> <span class="orgname">Samba Team</span> <span class="surname">Terpstra</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><code class="email">&lt;<a class="email" href="mailto:jht@samba.org">jht@samba.org</a>&gt;</code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Jeremy</span> <span class="orgname">Samba Team</span> <span class="surname">Allison</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><code class="email">&lt;<a class="email" href="mailto:jra@samba.org">jra@samba.org</a>&gt;</code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Gerald</span> <span class="othername">(Jerry)</span> <span class="orgname">Samba Team</span> <span class="surname">Carter</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><code class="email">&lt;<a class="email" href="mailto:jerry@samba.org">jerry@samba.org</a>&gt;</code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Andrew</span> <span class="orgname">Samba Team</span> <span class="surname">Tridgell</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><code class="email">&lt;<a class="email" href="mailto:tridge@samba.org">tridge@samba.org</a>&gt;</code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Jelmer</span> <span class="othername">R.</span> <span class="orgname">The Samba Team</span> <span class="surname">Vernooij</span></h3><div class="affiliation"><span class="orgname">The Samba Team<br></span><div class="address"><p><code class="email">&lt;<a class="email" href="mailto:jelmer@samba.org">jelmer@samba.org</a>&gt;</code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Guenther</span> <span class="orgname">SuSE</span> <span class="surname">Deschner</span></h3><span class="contrib">LDAP updates</span> <div class="affiliation"><span class="orgname">SuSE<br></span><div class="address"><p><code class="email">&lt;<a class="email" href="mailto:gd@suse.de">gd@suse.de</a>&gt;</code></p></div></div></div></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="domain-member.html#id2569122">Features and Benefits</a></span></dt><dt><span class="sect1"><a href="domain-member.html#machine-trust-accounts">MS Windows Workstation/Server Machine Trust Accounts</a></span></dt><dd><dl><dt><span class="sect2"><a href="domain-member.html#id2569809">Manual Creation of Machine Trust Accounts</a></span></dt><dt><span class="sect2"><a href="domain-member.html#id2570246">Managing Domain Machine Accounts using NT4 Server Manager</a></span></dt><dt><span class="sect2"><a href="domain-member.html#id2570526">On-the-Fly Creation of Machine Trust Accounts</a></span></dt><dt><span class="sect2"><a href="domain-member.html#id2570632">Making an MS Windows Workstation or Server a Domain Member</a></span></dt></dl></dd><dt><span class="sect1"><a href="domain-member.html#domain-member-server">Domain Member Server</a></span></dt><dd><dl><dt><span class="sect2"><a href="domain-member.html#id2571097">Joining an NT4-type Domain with Samba-3</a></span></dt><dt><span class="sect2"><a href="domain-member.html#id2571833">Why Is This Better Than security = server?</a></span></dt></dl></dd><dt><span class="sect1"><a href="domain-member.html#ads-member">Samba ADS Domain Membership</a></span></dt><dd><dl><dt><span class="sect2"><a href="domain-member.html#id2572115">Configure smb.conf</a></span></dt><dt><span class="sect2"><a href="domain-member.html#id2572306">Configure /etc/krb5.conf</a></span></dt><dt><span class="sect2"><a href="domain-member.html#ads-create-machine-account">Create the Computer Account</a></span></dt><dt><span class="sect2"><a href="domain-member.html#ads-test-server">Testing Server Setup</a></span></dt><dt><span class="sect2"><a href="domain-member.html#ads-test-smbclient">Testing with smbclient</a></span></dt><dt><span class="sect2"><a href="domain-member.html#id2573400">Notes</a></span></dt></dl></dd><dt><span class="sect1"><a href="domain-member.html#id2573472">Sharing User ID Mappings between Samba Domain Members</a></span></dt><dt><span class="sect1"><a href="domain-member.html#id2573679">Common Errors</a></span></dt><dd><dl><dt><span class="sect2"><a href="domain-member.html#id2573719">Cannot Add Machine Back to Domain</a></span></dt><dt><span class="sect2"><a href="domain-member.html#id2573794">Adding Machine to Domain Fails</a></span></dt><dt><span class="sect2"><a href="domain-member.html#id2574030">I Can't Join a Windows 2003 PDC</a></span></dt></dl></dd></dl></div><p>
2<a class="indexterm" name="id2569070"></a>
3<a class="indexterm" name="id2569077"></a>
4<a class="indexterm" name="id2569084"></a>
5Domain membership is a subject of vital concern. Samba must be able to
6participate as a member server in a Microsoft domain security context, and
7Samba must be capable of providing domain machine member trust accounts;
8otherwise it would not be able to offer a viable option for many users.
9</p><p>
10<a class="indexterm" name="id2569099"></a>
11<a class="indexterm" name="id2569106"></a>
12This chapter covers background information pertaining to domain membership,
13the Samba configuration for it, and MS Windows client procedures for joining a
14domain. Why is this necessary? Because both are areas in which there exists
15within the current MS Windows networking world, and particularly in the
16UNIX/Linux networking and administration world, a considerable level of
17misinformation, incorrect understanding, and lack of knowledge. Hopefully
18this chapter will fill the voids.
19</p><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2569122"></a>Features and Benefits</h2></div></div></div><p>
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23MS Windows workstations and servers that want to participate in domain security need to
24be made domain members. Participating in domain security is often called
25<span class="emphasis"><em>single sign-on</em></span>, or <acronym class="acronym">SSO</acronym> for short. This
26chapter describes the process that must be followed to make a workstation
27(or another server be it an <span class="application">MS Windows NT4/200x</span>
28server) or a Samba server a member of an MS Windows domain security context.
29</p><p>
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34Samba-3 can join an MS Windows NT4-style domain as a native member server, an
35MS Windows Active Directory domain as a native member server, or a Samba domain
36control network. Domain membership has many advantages:
37</p><div class="itemizedlist"><ul type="disc"><li><p>
38 <a class="indexterm" name="id2569216"></a>
39 MS Windows workstation users get the benefit of SSO.
40 </p></li><li><p>
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42 <a class="indexterm" name="id2569235"></a>
43 <a class="indexterm" name="id2569242"></a>
44 <a class="indexterm" name="id2569249"></a>
45 Domain user access rights and file ownership/access controls can be set
46 from the single Domain Security Account Manager (SAM) database
47 (works with domain member servers as well as with MS Windows workstations
48 that are domain members).
49 </p></li><li><p>
50 <a class="indexterm" name="id2569264"></a>
51 <a class="indexterm" name="id2569270"></a>
52 Only <span class="application">MS Windows NT4/200x/XP Professional</span>
53 workstations that are domain members can use network logon facilities.
54 </p></li><li><p>
55 <a class="indexterm" name="id2569289"></a>
56 <a class="indexterm" name="id2569296"></a>
57 <a class="indexterm" name="id2569303"></a>
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59 Domain member workstations can be better controlled through the use of
60 policy files (<code class="filename">NTConfig.POL</code>) and desktop profiles.
61 </p></li><li><p>
62 <a class="indexterm" name="id2569329"></a>
63 <a class="indexterm" name="id2569336"></a>
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65 Through the use of logon scripts, users can be given transparent access to network
66 applications that run off application servers.
67 </p></li><li><p>
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72 Network administrators gain better application and user access management
73 abilities because there is no need to maintain user accounts on any network
74 client or server other than the central domain database
75 (either NT4/Samba SAM-style domain, NT4 domain that is backend-ed with an
76 LDAP directory, or via an Active Directory infrastructure).
77 </p></li></ul></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="machine-trust-accounts"></a>MS Windows Workstation/Server Machine Trust Accounts</h2></div></div></div><p>
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82A Machine Trust Account is an account that is used to authenticate a client machine (rather than a user) to
83the domain controller server. In Windows terminology, this is known as a &#8220;<span class="quote">computer account.</span>&#8221; The
84purpose of the machine trust account is to prevent a rogue user and domain controller from colluding to gain
85access to a domain member workstation.
86</p><p>
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88<a class="indexterm" name="id2569455"></a>
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92The password of a Machine Trust Account acts as the shared secret for secure communication with the domain
93controller. This is a security feature to prevent an unauthorized machine with the same NetBIOS name from
94joining the domain, participating in domain security operations, and gaining access to domain user/group
95accounts. Windows NT/200x/XP Professional clients use machine trust accounts, but Windows 9x/Me/XP Home
96clients do not. Hence, a Windows 9x/Me/XP Home client is never a true member of a domain because it does not
97possess a Machine Trust Account, and, thus, has no shared secret with the domain controller.
98</p><p>
99<a class="indexterm" name="id2569497"></a>
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103A Windows NT4 PDC stores each Machine Trust Account in the Windows Registry.
104The introduction of MS Windows 2000 saw the introduction of Active Directory,
105the new repository for Machine Trust Accounts. A Samba PDC, however, stores
106each Machine Trust Account in two parts,
107as follows:
108
109</p><div class="itemizedlist"><ul type="disc"><li><p>
110 <a class="indexterm" name="id2569534"></a>
111 <a class="indexterm" name="id2569541"></a>
112 <a class="indexterm" name="id2569548"></a>
113 A domain security account (stored in the <a class="link" href="smb.conf.5.html#PASSDBBACKEND" target="_top">passdb backend</a>) that has been configured in
114 the <code class="filename">smb.conf</code> file. The precise nature of the account information that is stored depends on the type of
115 backend database that has been chosen.
116 </p><p>
117 <a class="indexterm" name="id2569580"></a>
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123 The older format of this data is the <code class="filename">smbpasswd</code> database
124 that contains the UNIX login ID, the UNIX user identifier (UID), and the
125 LanMan and NT-encrypted passwords. There is also some other information in
126 this file that we do not need to concern ourselves with here.
127 </p><p>
128 <a class="indexterm" name="id2569636"></a>
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130 <a class="indexterm" name="id2569650"></a>
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132 The two newer database types are called ldapsam and tdbsam. Both store considerably more data than the older
133 <code class="filename">smbpasswd</code> file did. The extra information enables new user account controls to be
134 implemented.
135 </p></li><li><p>
136 <a class="indexterm" name="id2569677"></a>
137 <a class="indexterm" name="id2569684"></a>
138 A corresponding UNIX account, typically stored in <code class="filename">/etc/passwd</code>. Work is in progress to
139 allow a simplified mode of operation that does not require UNIX user accounts, but this has not been a feature
140 of the early releases of Samba-3, and is not currently planned for release either.
141 </p></li></ul></div><p>
142</p><p>
143<a class="indexterm" name="id2569710"></a>
144There are three ways to create Machine Trust Accounts:
145</p><div class="itemizedlist"><ul type="disc"><li><p>
146 <a class="indexterm" name="id2569726"></a>
147 Manual creation from the UNIX/Linux command line. Here, both the Samba and
148 corresponding UNIX account are created by hand.
149 </p></li><li><p>
150 <a class="indexterm" name="id2569740"></a>
151 <a class="indexterm" name="id2569747"></a>
152 Using the MS Windows NT4 Server Manager, either from an NT4 domain member
153 server or using the Nexus toolkit available from the Microsoft Web site.
154 This tool can be run from any MS Windows machine as long as the user is
155 logged on as the administrator account.
156 </p></li><li><p>
157 <a class="indexterm" name="id2569763"></a>
158 <a class="indexterm" name="id2569770"></a>
159 &#8220;<span class="quote">On-the-fly</span>&#8221; creation. The Samba Machine Trust Account is automatically
160 created by Samba at the time the client is joined to the domain.
161 (For security, this is the recommended method.) The corresponding UNIX
162 account may be created automatically or manually.
163 </p></li></ul></div><p>
164<a class="indexterm" name="id2569789"></a>
165<a class="indexterm" name="id2569795"></a>
166Neither MS Windows NT4/200x/XP Professional, nor Samba, provide any method for enforcing the method of machine
167trust account creation. This is a matter of the administrator's choice.
168</p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2569809"></a>Manual Creation of Machine Trust Accounts</h3></div></div></div><p>
169<a class="indexterm" name="id2569817"></a>
170<a class="indexterm" name="id2569824"></a>
171<a class="indexterm" name="id2569830"></a>
172<a class="indexterm" name="id2569836"></a>
173The first step in manually creating a Machine Trust Account is to manually
174create the corresponding UNIX account in <code class="filename">/etc/passwd</code>.
175This can be done using <code class="literal">vipw</code> or another &#8220;<span class="quote">adduser</span>&#8221; command
176that is normally used to create new UNIX accounts. The following is an example for
177a Linux-based Samba server:
178</p><pre class="screen">
179<code class="prompt">root# </code><strong class="userinput"><code>/usr/sbin/useradd -g machines -d /var/lib/nobody \
180 -c <em class="replaceable"><code>"machine nickname"</code></em> \
181 -s /bin/false <em class="replaceable"><code>machine_name</code></em>$ </code></strong>
182
183<code class="prompt">root# </code><strong class="userinput"><code>passwd -l <em class="replaceable"><code>machine_name</code></em>$</code></strong>
184</pre><p>
185</p><p>
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187<a class="indexterm" name="id2569912"></a>
188<a class="indexterm" name="id2569919"></a>
189In the example above there is an existing system group &#8220;<span class="quote">machines</span>&#8221; which is used
190as the primary group for all machine accounts. In the following examples the &#8220;<span class="quote">machines</span>&#8221; group
191numeric GID is 100.
192</p><p>
193<a class="indexterm" name="id2569939"></a>
194<a class="indexterm" name="id2569946"></a>
195On *BSD systems, this can be done using the <code class="literal">chpass</code> utility:
196</p><pre class="screen">
197<code class="prompt">root# </code><strong class="userinput"><code>chpass -a \
198'<em class="replaceable"><code>machine_name</code></em>$:*:101:100::0:0:Windows <em class="replaceable"><code>machine_name</code></em>:/dev/null:/sbin/nologin'</code></strong>
199</pre><p>
200</p><p>
201<a class="indexterm" name="id2569987"></a>
202<a class="indexterm" name="id2569994"></a>
203<a class="indexterm" name="id2570000"></a>
204<a class="indexterm" name="id2570007"></a>
205The <code class="filename">/etc/passwd</code> entry will list the machine name
206with a &#8220;<span class="quote">$</span>&#8221; appended, and will not have a password, will have a null shell and no
207home directory. For example, a machine named &#8220;<span class="quote">doppy</span>&#8221; would have an
208<code class="filename">/etc/passwd</code> entry like this:
209</p><pre class="programlisting">
210doppy$:x:505:100:<em class="replaceable"><code>machine_nickname</code></em>:/dev/null:/bin/false
211</pre><p>
212</p><p>
213<a class="indexterm" name="id2570049"></a>
214<a class="indexterm" name="id2570056"></a>
215<a class="indexterm" name="id2570063"></a>
216in which <em class="replaceable"><code>machine_nickname</code></em> can be any
217descriptive name for the client, such as BasementComputer.
218<em class="replaceable"><code>machine_name</code></em> absolutely must be the NetBIOS
219name of the client to be joined to the domain. The &#8220;<span class="quote">$</span>&#8221; must be
220appended to the NetBIOS name of the client or Samba will not recognize
221this as a Machine Trust Account.
222</p><p>
223<a class="indexterm" name="id2570089"></a>
224<a class="indexterm" name="id2570096"></a>
225<a class="indexterm" name="id2570103"></a>
226Now that the corresponding UNIX account has been created, the next step is to create
227the Samba account for the client containing the well-known initial
228Machine Trust Account password. This can be done using the
229<code class="literal">smbpasswd</code> command
230as shown here:
231</p><pre class="screen">
232<code class="prompt">root# </code><strong class="userinput"><code>smbpasswd -a -m <em class="replaceable"><code>machine_name</code></em></code></strong>
233</pre><p>
234</p><p>
235<a class="indexterm" name="id2570144"></a>
236<a class="indexterm" name="id2570151"></a>
237<a class="indexterm" name="id2570158"></a>
238<a class="indexterm" name="id2570165"></a>
239where <em class="replaceable"><code>machine_name</code></em> is the machine's NetBIOS
240name. The RID of the new machine account is generated from the UID of
241the corresponding UNIX account.
242</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>
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247<a class="indexterm" name="id2570214"></a>
248Manually creating a Machine Trust Account using this method is the
249equivalent of creating a Machine Trust Account on a Windows NT PDC using
250<a class="indexterm" name="id2570224"></a>
251the <span class="application">Server Manager</span>. From the time at which the
252account is created to the time the client joins the domain and
253changes the password, your domain is vulnerable to an intruder joining
254your domain using a machine with the same NetBIOS name. A PDC inherently
255trusts members of the domain and will serve out a large degree of user
256information to such clients. You have been warned!
257</p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2570246"></a>Managing Domain Machine Accounts using NT4 Server Manager</h3></div></div></div><p>
258<a class="indexterm" name="id2570254"></a>
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261A working <a class="link" href="smb.conf.5.html#ADDMACHINESCRIPT" target="_top">add machine script</a> is essential
262for machine trust accounts to be automatically created. This applies no matter whether
263you use automatic account creation or the NT4 Domain Server Manager.
264</p><p>
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266<a class="indexterm" name="id2570301"></a>
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269If the machine from which you are trying to manage the domain is an
270<span class="application">MS Windows NT4 workstation or MS Windows 200x/XP Professional</span>,
271the tool of choice is the package called <code class="literal">SRVTOOLS.EXE</code>.
272When executed in the target directory it will unpack <code class="literal">SrvMgr.exe</code>
273and <code class="literal">UsrMgr.exe</code> (both are domain management tools for MS Windows NT4 workstation).
274</p><p>
275<a class="indexterm" name="id2570353"></a>
276<a class="indexterm" name="id2570360"></a>
277If your workstation is a <span class="application">Microsoft Windows 9x/Me</span> family product,
278 you should download the <code class="literal">Nexus.exe</code> package from the Microsoft Web site.
279When executed from the target directory, it will unpack the same tools but for use on
280this platform.
281</p><p>
282Further information about these tools may be obtained from Knowledge Base articles
283<a class="ulink" href="http://support.microsoft.com/default.aspx?scid=kb;en-us;173673" target="_top">173673</a>, and
284<a class="ulink" href="http://support.microsoft.com/default.aspx?scid=kb;en-us;172540" target="_top">172540</a>
285</p><p>
286<a class="indexterm" name="id2570404"></a>
287<a class="indexterm" name="id2570411"></a>
288Launch the <code class="literal">srvmgr.exe</code> (Server Manager for Domains) and follow these steps:
289</p><div class="procedure"><a name="id2570426"></a><p class="title"><b>Procedure 6.1. Server Manager Account Machine Account Management</b></p><ol type="1"><li><p>
290 From the menu select <span class="guimenu">Computer</span>.
291 </p></li><li><p>
292 Click <span class="guimenuitem">Select Domain</span>.
293 </p></li><li><p>
294 Click the name of the domain you wish to administer in the
295 <span class="guilabel">Select Domain</span> panel and then click
296 <span class="guibutton">OK</span>.
297 </p></li><li><p>
298 Again from the menu select <span class="guimenu">Computer</span>.
299 </p></li><li><p>
300 Select <span class="guimenuitem">Add to Domain</span>.
301 </p></li><li><p>
302 In the dialog box, click the radio button to
303 <span class="guilabel">Add NT Workstation of Server</span>, then
304 enter the machine name in the field provided, and click the
305 <span class="guibutton">Add</span> button.
306 </p></li></ol></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2570526"></a>On-the-Fly Creation of Machine Trust Accounts</h3></div></div></div><p>
307<a class="indexterm" name="id2570535"></a>
308The third (and recommended) way of creating Machine Trust Accounts is simply to allow the Samba server to
309create them as needed when the client is joined to the domain.
310</p><p>
311<a class="indexterm" name="id2570550"></a>
312<a class="indexterm" name="id2570560"></a>
313<a class="indexterm" name="id2570567"></a>
314Since each Samba Machine Trust Account requires a corresponding UNIX account, a method
315for automatically creating the UNIX account is usually supplied; this requires configuration of the
316add machine script option in <code class="filename">smb.conf</code>. This method is not required; however, corresponding UNIX
317accounts may also be created manually.
318</p><p>
319<a class="indexterm" name="id2570588"></a>
320<a class="indexterm" name="id2570595"></a>
321Here is an example for a Red Hat Linux system:
322</p><table class="simplelist" border="0" summary="Simple list"><tr><td> </td></tr><tr><td><em class="parameter"><code>[global]</code></em></td></tr><tr><td><a class="indexterm" name="id2570617"></a><em class="parameter"><code>add machine script = /usr/sbin/useradd -d /var/lib/nobody -g 100 -s /bin/false -M %u</code></em></td></tr></table><p>
323</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2570632"></a>Making an MS Windows Workstation or Server a Domain Member</h3></div></div></div><p>
324The procedure for making an MS Windows workstation or server a member of the domain varies
325with the version of Windows.
326</p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2570643"></a>Windows 200x/XP Professional Client</h4></div></div></div><p>
327<a class="indexterm" name="id2570651"></a>
328<a class="indexterm" name="id2570658"></a>
329<a class="indexterm" name="id2570668"></a>
330<a class="indexterm" name="id2570675"></a>
331 When the user elects to make the client a domain member, Windows 200x prompts for
332 an account and password that has privileges to create machine accounts in the domain.
333 A Samba administrator account (i.e., a Samba account that has <code class="constant">root</code> privileges on the
334 Samba server) must be entered here; the operation will fail if an ordinary user
335 account is given.
336 </p><p>
337<a class="indexterm" name="id2570694"></a>
338<a class="indexterm" name="id2570701"></a>
339 For security reasons, the password for this administrator account should be set
340 to a password that is other than that used for the root user in <code class="filename">/etc/passwd</code>.
341 </p><p>
342<a class="indexterm" name="id2570720"></a>
343<a class="indexterm" name="id2570726"></a>
344<a class="indexterm" name="id2570733"></a>
345<a class="indexterm" name="id2570740"></a>
346 The name of the account that is used to create domain member machine trust accounts can be
347 anything the network administrator may choose. If it is other than <code class="constant">root</code>,
348 then this is easily mapped to <code class="constant">root</code> in the file named in the <code class="filename">smb.conf</code> parameter
349 <a class="link" href="smb.conf.5.html#USERNAMEMAP" target="_top">username map = /etc/samba/smbusers</a>.
350 </p><p>
351<a class="indexterm" name="id2570780"></a>
352<a class="indexterm" name="id2570787"></a>
353<a class="indexterm" name="id2570793"></a>
354 The session key of the Samba administrator account acts as an encryption key for setting the password of the machine trust
355 account. The Machine Trust Account will be created on-the-fly, or updated if it already exists.
356 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2570806"></a>Windows NT4 Client</h4></div></div></div><p>
357<a class="indexterm" name="id2570814"></a>
358<a class="indexterm" name="id2570821"></a>
359<a class="indexterm" name="id2570828"></a>
360 If the Machine Trust Account was created manually, on the
361 Identification Changes menu enter the domain name, but do not
362 check the box <span class="guilabel">Create a Computer Account in the Domain</span>.
363 In this case, the existing Machine Trust Account is used to join the machine
364 to the domain.
365 </p><p>
366<a class="indexterm" name="id2570849"></a>
367<a class="indexterm" name="id2570856"></a>
368<a class="indexterm" name="id2570862"></a>
369<a class="indexterm" name="id2570869"></a>
370 If the Machine Trust Account is to be created on the fly, on the Identification Changes menu enter the domain
371 name and check the box <span class="guilabel">Create a Computer Account in the Domain</span>. In this case, joining
372 the domain proceeds as above for Windows 2000 (i.e., you must supply a Samba administrator account when
373 prompted).
374 </p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2570890"></a>Samba Client</h4></div></div></div><p>
375<a class="indexterm" name="id2570898"></a>
376 Joining a Samba client to a domain is documented in <a class="link" href="domain-member.html#domain-member-server" title="Domain Member Server">the next section</a>.
377 </p></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="domain-member-server"></a>Domain Member Server</h2></div></div></div><p>
378<a class="indexterm" name="id2570928"></a>
379<a class="indexterm" name="id2570935"></a>
380<a class="indexterm" name="id2570942"></a>
381<a class="indexterm" name="id2570949"></a>
382This mode of server operation involves the Samba machine being made a member
383of a domain security context. This means by definition that all user
384authentication will be done from a centrally defined authentication regime.
385The authentication regime may come from an NT3/4-style (old domain technology)
386server, or it may be provided from an Active Directory server (ADS) running on
387MS Windows 2000 or later.
388</p><p>
389<span class="emphasis"><em>
390<a class="indexterm" name="id2570968"></a>
391<a class="indexterm" name="id2570978"></a>
392<a class="indexterm" name="id2570985"></a>
393<a class="indexterm" name="id2570991"></a>
394<a class="indexterm" name="id2570998"></a>
395<a class="indexterm" name="id2571005"></a>
396<a class="indexterm" name="id2571012"></a>
397<a class="indexterm" name="id2571018"></a>
398Of course it should be clear that the authentication backend itself could be
399from any distributed directory architecture server that is supported by Samba.
400This can be LDAP (from OpenLDAP), or Sun's iPlanet, or Novell e-Directory
401Server, and so on.
402</em></span>
403</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
404<a class="indexterm" name="id2571035"></a>
405<a class="indexterm" name="id2571042"></a>
406<a class="indexterm" name="id2571048"></a>
407When Samba is configured to use an LDAP or other identity management and/or
408directory service, it is Samba that continues to perform user and machine
409authentication. It should be noted that the LDAP server does not perform
410authentication handling in place of what Samba is designed to do.
411</p></div><p>
412<a class="indexterm" name="id2571064"></a>
413<a class="indexterm" name="id2571071"></a>
414<a class="indexterm" name="id2571078"></a>
415Please refer to <a class="link" href="samba-pdc.html" title="Chapter 4. Domain Control">Domain Control</a>, for more information regarding
416how to create a domain machine account for a domain member server as well as for
417information on how to enable the Samba domain member machine to join the domain
418and be fully trusted by it.
419</p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2571097"></a>Joining an NT4-type Domain with Samba-3</h3></div></div></div><p><a class="link" href="domain-member.html#assumptions" title="Table 6.1. Assumptions">Assumptions</a> lists names that are used in the remainder of this chapter.</p><div class="table"><a name="assumptions"></a><p class="title"><b>Table 6.1. Assumptions</b></p><div class="table-contents"><table summary="Assumptions" border="1"><colgroup><col align="right"><col align="left"></colgroup><tbody><tr><td align="right">Samba DMS NetBIOS name:</td><td align="left">SERV1</td></tr><tr><td align="right">Windows 200x/NT domain name:</td><td align="left">MIDEARTH</td></tr><tr><td align="right">Domain's PDC NetBIOS name:</td><td align="left">DOMPDC</td></tr><tr><td align="right">Domain's BDC NetBIOS names:</td><td align="left">DOMBDC1 and DOMBDC2</td></tr></tbody></table></div></div><br class="table-break"><p>
420<a class="indexterm" name="id2571182"></a>
421First, you must edit your <code class="filename">smb.conf</code> file to tell Samba it should now use domain security.
422</p><p>
423<a class="indexterm" name="id2571198"></a>
424<a class="indexterm" name="id2571205"></a>
425<a class="indexterm" name="id2571212"></a>
426<a class="indexterm" name="id2571219"></a>
427Change (or add) your <a class="link" href="smb.conf.5.html#SECURITY" target="_top">security</a> line in the [global] section
428of your <code class="filename">smb.conf</code> to read:
429</p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2571249"></a><em class="parameter"><code>security = domain</code></em></td></tr></table><p>
430Note that if the parameter <em class="parameter"><code>security = user</code></em> is used, this machine would function as a
431standalone server and not as a domain member server. Domain security mode causes Samba to work within the
432domain security context.
433</p><p>
434Next change the <a class="link" href="smb.conf.5.html#WORKGROUP" target="_top">workgroup</a> line in the <em class="parameter"><code>[global]</code></em>
435section to read:
436</p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2571297"></a><em class="parameter"><code>workgroup = MIDEARTH</code></em></td></tr></table><p>
437This is the name of the domain we are joining.
438</p><p>
439<a class="indexterm" name="id2571313"></a>
440<a class="indexterm" name="id2571320"></a>
441You must also have the parameter <a class="link" href="smb.conf.5.html#ENCRYPTPASSWORDS" target="_top">encrypt passwords</a>
442set to <code class="constant">yes</code> in order for your users to authenticate to the NT PDC.
443This is the default setting if this parameter is not specified. There is no need to specify this
444parameter, but if it is specified in the <code class="filename">smb.conf</code> file, it must be set to <code class="constant">Yes</code>.
445</p><p>
446<a class="indexterm" name="id2571359"></a>
447<a class="indexterm" name="id2571366"></a>
448<a class="indexterm" name="id2571372"></a>
449<a class="indexterm" name="id2571379"></a>
450Finally, add (or modify) a <a class="link" href="smb.conf.5.html#PASSWORDSERVER" target="_top">password server</a> line in the [global]
451section to read:
452</p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2571404"></a><em class="parameter"><code>password server = DOMPDC DOMBDC1 DOMBDC2</code></em></td></tr></table><p>
453These are the PDC and BDCs Samba
454will attempt to contact in order to authenticate users. Samba will
455try to contact each of these servers in order, so you may want to
456rearrange this list in order to spread out the authentication load
457among Domain Controllers.
458</p><p>
459<a class="indexterm" name="id2571423"></a>
460<a class="indexterm" name="id2571430"></a>
461<a class="indexterm" name="id2571437"></a>
462<a class="indexterm" name="id2571444"></a>
463Alternatively, if you want smbd to determine automatically the list of domain controllers to use for
464authentication, you may set this line to be:
465</p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2571459"></a><em class="parameter"><code>password server = *</code></em></td></tr></table><p>
466<a class="indexterm" name="id2571471"></a>
467This method allows Samba to use exactly the same mechanism that NT does. The
468method either uses broadcast-based name resolution, performs a WINS database
469lookup in order to find a domain controller against which to authenticate,
470or locates the domain controller using DNS name resolution.
471</p><p>
472To join the domain, run this command:
473<a class="indexterm" name="id2571487"></a>
474</p><pre class="screen">
475<code class="prompt">root# </code><strong class="userinput"><code>net rpc join -S DOMPDC -U<em class="replaceable"><code>Administrator%password</code></em></code></strong>
476</pre><p>
477</p><p>
478<a class="indexterm" name="id2571520"></a>
479<a class="indexterm" name="id2571527"></a>
480<a class="indexterm" name="id2571534"></a>
481<a class="indexterm" name="id2571540"></a>
482If the <code class="option">-S DOMPDC</code> argument is not given, the domain name will be obtained from <code class="filename">smb.conf</code> and
483the NetBIOS name of the PDC will be obtained either using a WINS lookup or via NetBIOS broadcast based name
484look up.
485</p><p>
486<a class="indexterm" name="id2571563"></a>
487<a class="indexterm" name="id2571570"></a>
488<a class="indexterm" name="id2571577"></a>
489<a class="indexterm" name="id2571584"></a>
490The machine is joining the domain DOM, and the PDC for that domain (the only machine
491that has write access to the domain SAM database) is DOMPDC; therefore, use the <code class="option">-S</code>
492option. The <em class="replaceable"><code>Administrator%password</code></em> is the login name and
493password for an account that has the necessary privilege to add machines to the
494domain. If this is successful, you will see the following message in your terminal window.
495Where the older NT4-style domain architecture is used:
496</p><pre class="screen">
497<code class="computeroutput">Joined domain DOM.</code>
498</pre><p>
499</p><p>
500<a class="indexterm" name="id2571620"></a>
501<a class="indexterm" name="id2571632"></a>
502<a class="indexterm" name="id2571638"></a>
503Where Active Directory is used, the command used to join the ADS domain is:
504</p><pre class="screen">
505<code class="prompt">root# </code> net ads join -U<em class="replaceable"><code>Administrator%password</code></em>
506</pre><p>
507And the following output is indicative of a successful outcome:
508</p><pre class="screen">
509<code class="computeroutput">Joined SERV1 to realm MYREALM.</code>
510</pre><p>
511</p><p>
512Refer to the <code class="literal">net</code> man page and to <a class="link" href="NetCommand.html" title="Chapter 13. Remote and Local Management: The Net Command">the chapter on remote
513administration</a> for further information.
514</p><p>
515<a class="indexterm" name="id2571696"></a>
516<a class="indexterm" name="id2571702"></a>
517<a class="indexterm" name="id2571710"></a>
518This process joins the server to the domain without separately having to create the machine
519trust account on the PDC beforehand.
520</p><p>
521<a class="indexterm" name="id2571722"></a>
522<a class="indexterm" name="id2571731"></a>
523<a class="indexterm" name="id2571738"></a>
524<a class="indexterm" name="id2571746"></a>
525This command goes through the machine account password change protocol, then writes the new (random) machine
526account password for this Samba server into a file in the same directory in which a smbpasswd file would be
527normally stored. The trust account information that is needed by the DMS is written into the file
528<code class="filename">/usr/local/samba/private/secrets.tdb</code> or <code class="filename">/etc/samba/secrets.tdb</code>.
529</p><p>
530<a class="indexterm" name="id2571774"></a>
531<a class="indexterm" name="id2571781"></a>
532This file is created and owned by root and is not readable by any other user. It is
533the key to the domain-level security for your system and should be treated as carefully
534as a shadow password file.
535</p><p>
536<a class="indexterm" name="id2571795"></a>
537<a class="indexterm" name="id2571802"></a>
538<a class="indexterm" name="id2571809"></a>
539Finally, restart your Samba daemons and get ready for clients to begin using domain
540security. The way you can restart your Samba daemons depends on your distribution,
541but in most cases the following will suffice:
542</p><pre class="screen">
543<code class="prompt">root# </code>/etc/init.d/samba restart
544</pre><p>
545</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2571833"></a>Why Is This Better Than <em class="parameter"><code>security = server</code></em>?</h3></div></div></div><p>
546<a class="indexterm" name="id2571847"></a>
547<a class="indexterm" name="id2571854"></a>
548<a class="indexterm" name="id2571861"></a>
549Currently, domain security in Samba does not free you from having to create local UNIX users to represent the
550users attaching to your server. This means that if domain user <code class="constant">DOM\fred</code> attaches to your
551domain security Samba server, there needs to be a local UNIX user fred to represent that user in the UNIX file
552system. This is similar to the older Samba security mode <a class="link" href="smb.conf.5.html#SECURITY" target="_top">security = server</a>, where Samba would pass through the authentication request to a Windows
553NT server in the same way as a Windows 95 or Windows 98 server would.
554</p><p>
555<a class="indexterm" name="id2571896"></a>
556<a class="indexterm" name="id2571902"></a>
557<a class="indexterm" name="id2571908"></a>
558Please refer to <a class="link" href="winbind.html" title="Chapter 24. Winbind: Use of Domain Accounts">Winbind: Use of Domain Accounts</a>, for information on a system
559to automatically assign UNIX UIDs and GIDs to Windows NT domain users and groups.
560</p><p>
561<a class="indexterm" name="id2571928"></a>
562<a class="indexterm" name="id2571934"></a>
563<a class="indexterm" name="id2571941"></a>
564The advantage of domain-level security is that the authentication in domain-level security is passed down the
565authenticated RPC channel in exactly the same way that an NT server would do it. This means Samba servers now
566participate in domain trust relationships in exactly the same way NT servers do (i.e., you can add Samba
567servers into a resource domain and have the authentication passed on from a resource domain PDC to an account
568domain PDC).
569</p><p>
570<a class="indexterm" name="id2571959"></a>
571<a class="indexterm" name="id2571966"></a>
572<a class="indexterm" name="id2571972"></a>
573In addition, with <a class="link" href="smb.conf.5.html#SECURITY" target="_top">security = server</a>, every Samba daemon on a server has to
574keep a connection open to the authenticating server for as long as that daemon lasts. This can drain the
575connection resources on a Microsoft NT server and cause it to run out of available connections. With
576<a class="link" href="smb.conf.5.html#SECURITY" target="_top">security = domain</a>, however, the Samba daemons connect to the PDC or BDC
577only for as long as is necessary to authenticate the user and then drop the connection, thus conserving PDC
578connection resources.
579</p><p>
580<a class="indexterm" name="id2572012"></a>
581<a class="indexterm" name="id2572019"></a>
582<a class="indexterm" name="id2572026"></a>
583<a class="indexterm" name="id2572032"></a>
584Finally, acting in the same manner as an NT server authenticating to a PDC means that as part of the
585authentication reply, the Samba server gets the user identification information such as the user SID, the list
586of NT groups the user belongs to, and so on.
587</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
588Much of the text of this document was first published in the Web magazine
589<a class="ulink" href="http://www.linuxworld.com" target="_top"><span class="emphasis"><em>LinuxWorld</em></span></a> as the article <a class="ulink" href="http://www.linuxworld.com/linuxworld/lw-1998-10/lw-10-samba.html" target="_top">http://www.linuxworld.com/linuxworld/lw-1998-10/lw-10-samba.html</a>
590<span class="emphasis"><em>Doing the NIS/NT Samba</em></span>.
591</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><p>
592<a class="indexterm" name="id2572082"></a>
593<a class="indexterm" name="id2572089"></a>
594<a class="indexterm" name="id2572098"></a>
595<a class="indexterm" name="id2572105"></a>
596This is a rough guide to setting up Samba-3 with Kerberos authentication against a
597Windows 200x KDC. A familiarity with Kerberos is assumed.
598</p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2572115"></a>Configure <code class="filename">smb.conf</code></h3></div></div></div><p>
599You must use at least the following three options in <code class="filename">smb.conf</code>:
600</p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2572141"></a><em class="parameter"><code>realm = your.kerberos.REALM</code></em></td></tr><tr><td><a class="indexterm" name="id2572153"></a><em class="parameter"><code>security = ADS</code></em></td></tr><tr><td># The following parameter need only be specified if present.</td></tr><tr><td># The default setting if not present is Yes.</td></tr><tr><td><a class="indexterm" name="id2572173"></a><em class="parameter"><code>encrypt passwords = yes</code></em></td></tr></table><p>
601<a class="indexterm" name="id2572187"></a>
602<a class="indexterm" name="id2572193"></a>
603<a class="indexterm" name="id2572200"></a>
604<a class="indexterm" name="id2572207"></a>
605<a class="indexterm" name="id2572214"></a>
606In case samba cannot correctly identify the appropriate ADS server using the realm name, use the
607<a class="link" href="smb.conf.5.html#PASSWORDSERVER" target="_top">password server</a> option in <code class="filename">smb.conf</code>:
608</p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2572245"></a><em class="parameter"><code>password server = your.kerberos.server</code></em></td></tr></table><p>
609The most common reason for which Samba may not be able to locate the ADS domain controller is a consequence of
610sites maintaining some DNS servers on UNIX systems without regard for the DNS requirements of the ADS
611infrastructure. There is no harm in specifying a preferred ADS domain controller using the <em class="parameter"><code>password
612server</code></em>.
613</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
614<a class="indexterm" name="id2572272"></a>
615<a class="indexterm" name="id2572278"></a>
616You do <span class="emphasis"><em>not</em></span> need an smbpasswd file, and older clients will be authenticated as
617if <a class="link" href="smb.conf.5.html#SECURITY" target="_top">security = domain</a>, although it will not do any harm and
618allows you to have local users not in the domain.
619</p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2572306"></a>Configure <code class="filename">/etc/krb5.conf</code></h3></div></div></div><p>
620<a class="indexterm" name="id2572318"></a>
621<a class="indexterm" name="id2572325"></a>
622<a class="indexterm" name="id2572334"></a>
623<a class="indexterm" name="id2572341"></a>
624With both MIT and Heimdal Kerberos, it is unnecessary to configure the <code class="filename">/etc/krb5.conf</code>,
625and it may be detrimental.
626</p><p>
627<a class="indexterm" name="id2572359"></a>
628<a class="indexterm" name="id2572366"></a>
629<a class="indexterm" name="id2572372"></a>
630<a class="indexterm" name="id2572379"></a>
631<a class="indexterm" name="id2572386"></a>
632Microsoft ADS automatically create SRV records in the DNS zone
633<em class="parameter"><code>_kerberos._tcp.REALM.NAME</code></em> for each KDC in the realm. This is part
634of the installation and configuration process used to create an Active Directory domain.
635A KDC is a Kerberos Key Distribution Center and forms an integral part of the Microsoft
636active directory infrastructure.
637</p><p>
638<a class="indexterm" name="id2572407"></a>
639<a class="indexterm" name="id2572414"></a>
640<a class="indexterm" name="id2572421"></a>
641<a class="indexterm" name="id2572428"></a>
642<a class="indexterm" name="id2572435"></a>
643<a class="indexterm" name="id2572442"></a>
644UNIX systems can use kinit and the DES-CBC-MD5 or DES-CBC-CRC encryption types to authenticate to the Windows
6452000 KDC. For further information regarding Windows 2000 ADS kerberos interoperability please refer to the
646Microsoft Windows 2000 Kerberos <a class="ulink" href="http://www.microsoft.com/windows2000/techinfo/planning/security/kerbsteps.asp" target="_top">Interoperability</a>
647guide. Another very useful document that may be referred to for general information regarding Kerberos
648interoperability is <a class="ulink" href="http://www.ietf.org/rfc/rfc1510.txt?number=1510" target="_top">RFC1510</a>. This RFC
649explains much of the magic behind the operation of Kerberos.
650</p><p>
651<a class="indexterm" name="id2572473"></a>
652<a class="indexterm" name="id2572480"></a>
653<a class="indexterm" name="id2572486"></a>
654<a class="indexterm" name="id2572493"></a>
655<a class="indexterm" name="id2572500"></a>
656<a class="indexterm" name="id2572507"></a>
657MIT's, as well as Heimdal's, recent KRB5 libraries default to checking for SRV records, so they will
658automatically find the KDCs. In addition, <code class="filename">krb5.conf</code> only allows specifying
659a single KDC, even there if there may be more than one. Using the DNS lookup allows the KRB5
660libraries to use whichever KDCs are available.
661</p><p>
662<a class="indexterm" name="id2572528"></a>
663When manually configuring <code class="filename">krb5.conf</code>, the minimal configuration is:
664</p><pre class="screen">
665[libdefaults]
666 default_realm = YOUR.KERBEROS.REALM
667
668[realms]
669 YOUR.KERBEROS.REALM = {
670 kdc = your.kerberos.server
671 }
672
673[domain_realms]
674 .kerberos.server = YOUR.KERBEROS.REALM
675</pre><p>
676</p><p>
677<a class="indexterm" name="id2572554"></a>
678When using Heimdal versions before 0.6, use the following configuration settings:
679</p><pre class="screen">
680[libdefaults]
681 default_realm = YOUR.KERBEROS.REALM
682 default_etypes = des-cbc-crc des-cbc-md5
683 default_etypes_des = des-cbc-crc des-cbc-md5
684
685[realms]
686 YOUR.KERBEROS.REALM = {
687 kdc = your.kerberos.server
688 }
689
690[domain_realms]
691 .kerberos.server = YOUR.KERBEROS.REALM
692</pre><p>
693</p><p>
694<a class="indexterm" name="id2572576"></a>
695<a class="indexterm" name="id2572582"></a>
696Test your config by doing a <strong class="userinput"><code>kinit
697<em class="replaceable"><code>USERNAME</code></em>@<em class="replaceable"><code>REALM</code></em></code></strong> and
698making sure that your password is accepted by the Win2000 KDC.
699</p><p>
700<a class="indexterm" name="id2572606"></a>
701<a class="indexterm" name="id2572613"></a>
702<a class="indexterm" name="id2572619"></a>
703<a class="indexterm" name="id2572626"></a>
704With Heimdal versions earlier than 0.6.x you can use only newly created accounts
705in ADS or accounts that have had the password changed once after migration, or
706in case of <code class="constant">Administrator</code> after installation. At the
707moment, a Windows 2003 KDC can only be used with Heimdal releases later than 0.6
708(and no default etypes in krb5.conf). Unfortunately, this whole area is still
709in a state of flux.
710</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
711<a class="indexterm" name="id2572647"></a>
712<a class="indexterm" name="id2572654"></a>
713<a class="indexterm" name="id2572661"></a>
714The realm must be in uppercase or you will get a &#8220;<span class="quote"><span class="errorname">Cannot find KDC for
715requested realm while getting initial credentials</span></span>&#8221; error (Kerberos
716is case-sensitive!).
717</p></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
718<a class="indexterm" name="id2572678"></a>
719<a class="indexterm" name="id2572685"></a>
720<a class="indexterm" name="id2572692"></a>
721<a class="indexterm" name="id2572699"></a>
722Time between the two servers must be synchronized. You will get a &#8220;<span class="quote"><span class="errorname">kinit(v5): Clock skew too
723great while getting initial credentials</span></span>&#8221; if the time difference (clock skew) is more than five minutes.
724</p></div><p>
725<a class="indexterm" name="id2572716"></a>
726<a class="indexterm" name="id2572723"></a>
727Clock skew limits are configurable in the Kerberos protocols. The default setting is five minutes.
728</p><p>
729<a class="indexterm" name="id2572735"></a>
730<a class="indexterm" name="id2572742"></a>
731<a class="indexterm" name="id2572748"></a>
732<a class="indexterm" name="id2572755"></a>
733You also must ensure that you can do a reverse DNS lookup on the IP address of your KDC. Also, the name that
734this reverse lookup maps to must either be the NetBIOS name of the KDC (i.e., the hostname with no domain
735attached) or it can be the NetBIOS name followed by the realm.
736</p><p>
737<a class="indexterm" name="id2572770"></a>
738<a class="indexterm" name="id2572777"></a>
739<a class="indexterm" name="id2572783"></a>
740The easiest way to ensure you get this right is to add a <code class="filename">/etc/hosts</code> entry mapping the IP
741address of your KDC to its NetBIOS name. If you do not get this correct, then you will get a <span class="errorname">local
742error</span> when you try to join the realm.
743</p><p>
744<a class="indexterm" name="id2572806"></a>
745<a class="indexterm" name="id2572813"></a>
746<a class="indexterm" name="id2572820"></a>
747<a class="indexterm" name="id2572827"></a>
748If all you want is Kerberos support in <span class="application">smbclient</span>, then you can skip directly to <a class="link" href="domain-member.html#ads-test-smbclient" title="Testing with smbclient">Testing with <span class="application">smbclient</span></a> now. <a class="link" href="domain-member.html#ads-create-machine-account" title="Create the Computer Account">Create the Computer Account</a> and <a class="link" href="domain-member.html#ads-test-server" title="Testing Server Setup">Testing Server Setup</a> are needed only if you want Kerberos support for <span class="application">smbd</span>
749and <span class="application">winbindd</span>.
750</p></div><div 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><p>
751<a class="indexterm" name="id2572898"></a>
752<a class="indexterm" name="id2572904"></a>
753<a class="indexterm" name="id2572911"></a>
754<a class="indexterm" name="id2572918"></a>
755As a user who has write permission on the Samba private directory (usually root), run:
756</p><pre class="screen">
757<code class="prompt">root# </code> <strong class="userinput"><code>net ads join -U Administrator%password</code></strong>
758</pre><p>
759The Administrator account can be any account that has been designated in the ADS domain security settings with
760permission to add machines to the ADS domain. It is, of course, a good idea to use an account other than Administrator.
761On the UNIX/Linux system, this command must be executed by an account that has UID=0 (root).
762</p><p>
763<a class="indexterm" name="id2572953"></a>
764<a class="indexterm" name="id2572959"></a>
765<a class="indexterm" name="id2572966"></a>
766<a class="indexterm" name="id2572973"></a>
767<a class="indexterm" name="id2572980"></a>
768<a class="indexterm" name="id2572987"></a>
769When making a Windows client a member of an ADS domain within a complex organization, you
770may want to create the machine trust account within a particular organizational unit. Samba-3 permits
771this to be done using the following syntax:
772</p><pre class="screen">
773<code class="prompt">root# </code> <strong class="userinput"><code>kinit Administrator@your.kerberos.REALM</code></strong>
774<code class="prompt">root# </code> <strong class="userinput"><code>net ads join createcomputer="organizational_unit"</code></strong>
775</pre><p>
776Your ADS manager will be able to advise what should be specified for the "organizational_unit" parameter.
777</p><p>
778<a class="indexterm" name="id2573037"></a>
779<a class="indexterm" name="id2573044"></a>
780<a class="indexterm" name="id2573051"></a>
781<a class="indexterm" name="id2573058"></a>
782For example, you may want to create the machine trust account in a container called &#8220;<span class="quote">Servers</span>&#8221;
783under the organizational directory &#8220;<span class="quote">Computers/BusinessUnit/Department,</span>&#8221; like this:
784</p><pre class="screen">
785<code class="prompt">root# </code> <strong class="userinput"><code>net ads join "Computers/BusinessUnit/Department/Servers"</code></strong>
786</pre><p>
787This command will place the Samba server machine trust account in the container
788<code class="literal">Computers/BusinessUnit/Department/Servers</code>. The container should exist in the ADS directory
789before executing this command. Please note that forward slashes must be used, because backslashes are both
790valid characters in an OU name and used as escapes for other characters. If you need a backslash in an OU
791name, it may need to be quadrupled to pass through the shell escape and ldap escape.
792</p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2573107"></a>Possible Errors</h4></div></div></div><p>
793</p><div class="variablelist"><dl><dt><span class="term"><span class="errorname">ADS support not compiled in</span></span></dt><dd><p>
794 <a class="indexterm" name="id2573126"></a>
795 <a class="indexterm" name="id2573133"></a>
796 <a class="indexterm" name="id2573140"></a>
797 Samba must be reconfigured (remove config.cache) and recompiled (make clean all install) after the
798 Kerberos libraries and headers files are installed.
799 </p></dd><dt><span class="term"><span class="errorname">net ads join prompts for user name</span></span></dt><dd><p>
800 <a class="indexterm" name="id2573160"></a>
801 <a class="indexterm" name="id2573167"></a>
802 You need to log in to the domain using <strong class="userinput"><code>kinit
803 <em class="replaceable"><code>USERNAME</code></em>@<em class="replaceable"><code>REALM</code></em></code></strong>.
804 <em class="replaceable"><code>USERNAME</code></em> must be a user who has rights to add a machine to the domain.
805 </p></dd><dt><span class="term">Unsupported encryption/or checksum types</span></dt><dd><p>
806 <a class="indexterm" name="id2573200"></a>
807 <a class="indexterm" name="id2573207"></a>
808 <a class="indexterm" name="id2573214"></a>
809 Make sure that the <code class="filename">/etc/krb5.conf</code> is correctly configured
810 for the type and version of Kerberos installed on the system.
811 </p></dd></dl></div><p>
812</p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="ads-test-server"></a>Testing Server Setup</h3></div></div></div><p>
813<a class="indexterm" name="id2573246"></a>
814<a class="indexterm" name="id2573252"></a>
815<a class="indexterm" name="id2573259"></a>
816If the join was successful, you will see a new computer account with the
817NetBIOS name of your Samba server in Active Directory (in the &#8220;<span class="quote">Computers</span>&#8221;
818folder under Users and Computers.
819</p><p>
820<a class="indexterm" name="id2573275"></a>
821<a class="indexterm" name="id2573282"></a>
822<a class="indexterm" name="id2573291"></a>
823On a Windows 2000 client, try <strong class="userinput"><code>net use * \\server\share</code></strong>. You should
824be logged in with Kerberos without needing to know a password. If this fails, then run
825<strong class="userinput"><code>klist tickets</code></strong>. Did you get a ticket for the server? Does it have
826an encryption type of DES-CBC-MD5?
827</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
828<a class="indexterm" name="id2573318"></a>
829<a class="indexterm" name="id2573325"></a>
830<a class="indexterm" name="id2573332"></a>
831Samba can use both DES-CBC-MD5 encryption as well as ARCFOUR-HMAC-MD5 encoding.
832</p></div></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><p>
833<a class="indexterm" name="id2573359"></a>
834<a class="indexterm" name="id2573366"></a>
835<a class="indexterm" name="id2573373"></a>
836On your Samba server try to log in to a Windows 2000 server or your Samba
837server using <span class="application">smbclient</span> and Kerberos. Use <span class="application">smbclient</span> as usual, but
838specify the <code class="option">-k</code> option to choose Kerberos authentication.
839</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2573400"></a>Notes</h3></div></div></div><p>
840<a class="indexterm" name="id2573408"></a>
841<a class="indexterm" name="id2573415"></a>
842<a class="indexterm" name="id2573422"></a>
843You must change the administrator password at least once after installing a domain controller,
844to create the right encryption types.
845</p><p>
846<a class="indexterm" name="id2573434"></a>
847<a class="indexterm" name="id2573441"></a>
848<a class="indexterm" name="id2573448"></a>
849Windows 200x does not seem to create the <em class="parameter"><code>_kerberos._udp</code></em> and
850<em class="parameter"><code>_ldap._tcp</code></em> in the default DNS setup. Perhaps this will be fixed later in service packs.
851</p></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2573472"></a>Sharing User ID Mappings between Samba Domain Members</h2></div></div></div><p>
852<a class="indexterm" name="id2573481"></a>
853<a class="indexterm" name="id2573488"></a>
854<a class="indexterm" name="id2573495"></a>
855<a class="indexterm" name="id2573501"></a>
856Samba maps UNIX users and groups (identified by UIDs and GIDs) to Windows users and groups (identified by SIDs).
857These mappings are done by the <em class="parameter"><code>idmap</code></em> subsystem of Samba.
858</p><p>
859<a class="indexterm" name="id2573520"></a>
860<a class="indexterm" name="id2573526"></a>
861<a class="indexterm" name="id2573533"></a>
862In some cases it is useful to share these mappings between Samba domain members,
863so <span class="emphasis"><em>name-&gt;id</em></span> mapping is identical on all machines.
864This may be needed in particular when sharing files over both CIFS and NFS.
865</p><p>
866<a class="indexterm" name="id2573551"></a>
867<a class="indexterm" name="id2573557"></a>
868To use the <span class="emphasis"><em>LDAP</em></span> <em class="parameter"><code>ldap idmap suffix</code></em>, set:
869</p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2573581"></a><em class="parameter"><code>ldap idmap suffix = ou=Idmap</code></em></td></tr></table><p>
870See the <code class="filename">smb.conf</code> man page entry for the <a class="link" href="smb.conf.5.html#LDAPIDMAPSUFFIX" target="_top">ldap idmap suffix</a>
871parameter for further information.
872</p><p>
873<a class="indexterm" name="id2573617"></a>
874<a class="indexterm" name="id2573624"></a>
875<a class="indexterm" name="id2573631"></a>
876Do not forget to specify also the <a class="link" href="smb.conf.5.html#LDAPADMINDN" target="_top">ldap admin dn</a>
877and to make certain to set the LDAP administrative password into the <code class="filename">secrets.tdb</code> using:
878</p><pre class="screen">
879<code class="prompt">root# </code> smbpasswd -w ldap-admin-password
880</pre><p>
881In place of <code class="literal">ldap-admin-password</code>, substitute the LDAP administration password for your
882system.
883</p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2573679"></a>Common Errors</h2></div></div></div><p>
884<a class="indexterm" name="id2573687"></a>
885<a class="indexterm" name="id2573694"></a>
886In the process of adding/deleting/re-adding domain member machine trust accounts, there are
887many traps for the unwary player and many &#8220;<span class="quote">little</span>&#8221; things that can go wrong.
888It is particularly interesting how often subscribers on the Samba mailing list have concluded
889after repeated failed attempts to add a machine account that it is necessary to &#8220;<span class="quote">reinstall</span>&#8221;
890MS Windows on the machine. In truth, it is seldom necessary to reinstall because of this type
891of problem. The real solution is often quite simple, and with an understanding of how MS Windows
892networking functions, it is easy to overcome.
893</p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2573719"></a>Cannot Add Machine Back to Domain</h3></div></div></div><p>
894<a class="indexterm" name="id2573727"></a>
895<a class="indexterm" name="id2573734"></a>
896&#8220;<span class="quote">A Windows workstation was reinstalled. The original domain machine trust
897account was deleted and added immediately. The workstation will not join the domain if I use
898the same machine name. Attempts to add the machine fail with a message that the machine already
899exists on the network I know it does not. Why is this failing?</span>&#8221;
900</p><p>
901<a class="indexterm" name="id2573755"></a>
902<a class="indexterm" name="id2573761"></a>
903The original name is still in the NetBIOS name cache and must expire after machine account
904deletion before adding that same name as a domain member again. The best advice is to delete
905the old account and then add the machine with a new name. Alternately, the name cache can be flushed and
906reloaded with current data using the <code class="literal">nbtstat</code> command on the Windows client:
907</p><pre class="screen">
908<code class="prompt">C:\&gt; </code> nbtstat -R
909</pre><p>
910</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2573794"></a>Adding Machine to Domain Fails</h3></div></div></div><p>
911<a class="indexterm" name="id2573802"></a>
912<a class="indexterm" name="id2573809"></a>
913&#8220;<span class="quote">Adding a Windows 200x or XP Professional machine to the Samba PDC Domain fails with a
914message that says, <span class="errorname">"The machine could not be added at this time, there is a network problem.
915Please try again later."</span> Why?</span>&#8221;
916</p><p>
917<a class="indexterm" name="id2573829"></a>
918You should check that there is an <a class="link" href="smb.conf.5.html#ADDMACHINESCRIPT" target="_top">add machine script</a> in your <code class="filename">smb.conf</code>
919file. If there is not, please add one that is appropriate for your OS platform. If a script
920has been defined, you will need to debug its operation. Increase the <a class="link" href="smb.conf.5.html#LOGLEVEL" target="_top">log level</a>
921in the <code class="filename">smb.conf</code> file to level 10, then try to rejoin the domain. Check the logs to see which
922operation is failing.
923</p><p>
924Possible causes include:
925</p><div class="itemizedlist"><ul type="disc"><li><p>
926<a class="indexterm" name="id2573887"></a>
927<a class="indexterm" name="id2573894"></a>
928 The script does not actually exist, or could not be located in the path specified.
929 </p><p>
930<a class="indexterm" name="id2573906"></a>
931<a class="indexterm" name="id2573912"></a>
932 <span class="emphasis"><em>Corrective action:</em></span> Fix it. Make sure when run manually
933 that the script will add both the UNIX system account and the Samba SAM account.
934 </p></li><li><p>
935<a class="indexterm" name="id2573929"></a>
936<a class="indexterm" name="id2573936"></a>
937 The machine could not be added to the UNIX system accounts file <code class="filename">/etc/passwd</code>.
938 </p><p>
939<a class="indexterm" name="id2573953"></a>
940<a class="indexterm" name="id2573960"></a>
941 <span class="emphasis"><em>Corrective action:</em></span> Check that the machine name is a legal UNIX
942 system account name. If the UNIX utility <code class="literal">useradd</code> is called,
943 then make sure that the machine name you are trying to add can be added using this
944 tool. <code class="literal">Useradd</code> on some systems will not allow any uppercase characters
945 nor will it allow spaces in the name.
946 </p></li></ul></div><p>
947<a class="indexterm" name="id2573992"></a>
948<a class="indexterm" name="id2573999"></a>
949<a class="indexterm" name="id2574006"></a>
950The <a class="link" href="smb.conf.5.html#ADDMACHINESCRIPT" target="_top">add machine script</a> does not create the
951machine account in the Samba backend database; it is there only to create a UNIX system
952account to which the Samba backend database account can be mapped.
953</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2574030"></a>I Can't Join a Windows 2003 PDC</h3></div></div></div><p>
954<a class="indexterm" name="id2574038"></a>
955<a class="indexterm" name="id2574044"></a>
956<a class="indexterm" name="id2574051"></a>
957<a class="indexterm" name="id2574058"></a>
958 Windows 2003 requires SMB signing. Client-side SMB signing has been implemented in Samba-3.0.
959 Set <a class="link" href="smb.conf.5.html#CLIENTUSESPNEGO" target="_top">client use spnego = yes</a> when communicating
960 with a Windows 2003 server. This will not interfere with other Windows clients that do not
961 support the more advanced security features of Windows 2003 because the client will simply
962 negotiate a protocol that both it and the server suppport. This is a well-known fall-back facility
963 that is built into the SMB/CIFS protocols.
964 </p></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 5. 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 7. Standalone Servers</td></tr></table></div></body></html>
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