path: root/docs/docbook/projdoc/DOMAIN_MEMBER.xml

<chapter id="domain-member">

<chapterinfo>
	&author.jht;
	&author.jeremy;
	&author.jerry;

<!-- Authors of the ADS-HOWTO -->
	&author.tridge;
	&author.jelmer;
</chapterinfo>

<title>Domain Membership</title>

<para>
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.
</para>

<para>
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.
</para>

<sect1>
<title>Features and Benefits</title>

<para>
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 
<emphasis>Single Sign On</emphasis> or <acronym>SSO</acronym> for short. This
chapter describes the process that must be followed to make a workstation
(or another server - be it an <application>MS Windows NT4 / 200x</application>
server) or a Samba server a member of an MS Windows Domain security context.
</para>

<para>
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.
</para>

<para>
Domain membership has many advantages:
</para>

<itemizedlist>
	<listitem><para>
	MS Windows workstation users get the benefit of SSO
	</para></listitem>

	<listitem><para>
	Domain user access rights and file ownership / access controls can be set
	from the single Domain SAM (Security Account Manager) database 
	(works with Domain member servers as well as with MS Windows workstations
	that are domain members)
	</para></listitem>

	<listitem><para>
	Only <application>MS Windows NT4 / 200x / XP Professional</application>
	workstations that are Domain members
	can use network logon facilities
	</para></listitem>

	<listitem><para>
	Domain Member workstations can be better controlled through the use of
	Policy files (<filename>NTConfig.POL</filename>) and Desktop Profiles.
	</para></listitem>

	<listitem><para>
	Through the use of logon scripts, users can be given transparent access to network
	applications that run off application servers
	</para></listitem>

	<listitem><para>
	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)
	</para></listitem>
</itemizedlist>

</sect1>

<sect1>
<title>MS Windows Workstation/Server Machine Trust Accounts</title>

<para>
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."
</para>

<para>
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.
</para>

<para>
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.
</para>

<para>
A Samba PDC, however, stores each machine trust account in two parts,
as follows:

<itemizedlist>
	<listitem><para>
	A Domain Security Account (stored in the 
	<parameter>passdb backend</parameter> that has been configured in the
	&smb.conf; file. The precise nature of the account information that is
	stored depends on the type of backend database that has been chosen.
	</para>

	<para>
	The older format of this data is the <filename>smbpasswd</filename> 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.
	</para>

	<para>
	The two newer database types are called <emphasis>ldapsam</emphasis>,
	<emphasis>tdbsam</emphasis>.  Both store considerably more data than the
	older <filename>smbpasswd</filename> file did. The extra information
	enables new user account controls to be used.
	</para></listitem>

	<listitem><para>
	A corresponding Unix account, typically stored in
	<filename>/etc/passwd</filename>.  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.
	</para></listitem>
</itemizedlist>
</para>

<para>
There are three ways to create machine trust accounts:
</para>

<itemizedlist>
	<listitem><para>
	Manual creation from the Unix/Linux command line. Here, both the Samba and
	corresponding Unix account are created by hand.
	</para></listitem>

	<listitem><para>
	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.
	</para></listitem>
	
	<listitem><para>
	"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. 
	</para></listitem>
</itemizedlist>

<sect2>
<title>Manual Creation of Machine Trust Accounts</title>

<para>
The first step in manually creating a machine trust account is to manually
create the corresponding Unix account in <filename>/etc/passwd</filename>. 
This can be done using <command>vipw</command> 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:
</para>

<para>
&rootprompt;<userinput>/usr/sbin/useradd -g 100 -d /dev/null -c <replaceable>"machine nickname"</replaceable> -s /bin/false <replaceable>machine_name</replaceable>$ </userinput>
</para>

<para>
&rootprompt;<userinput>passwd -l <replaceable>machine_name</replaceable>$</userinput>
</para>

<para>
On *BSD systems, this can be done using the <command>chpass</command> utility:
</para>

<para>
&rootprompt;<userinput>chpass -a "<replaceable>machine_name</replaceable>$:*:101:100::0:0:Workstation <replaceable>machine_name</replaceable>:/dev/null:/sbin/nologin"</userinput>
</para>

<para>
The <filename>/etc/passwd</filename> 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 
<filename>/etc/passwd</filename> entry like this:
</para>

<programlisting>
doppy$:x:505:501:<replaceable>machine_nickname</replaceable>:/dev/null:/bin/false
</programlisting>

<para>
Above, <replaceable>machine_nickname</replaceable> can be any
descriptive name for the client, i.e., BasementComputer.
<replaceable>machine_name</replaceable> 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.
</para>

<para>
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 <ulink 
url="smbpasswd.8.html"><command>smbpasswd(8)</command></ulink> command 
as shown here:
</para>

<para>
<screen>
&rootprompt;<userinput>smbpasswd -a -m <replaceable>machine_name</replaceable></userinput>
</screen>
</para>

<para>
where <replaceable>machine_name</replaceable> is the machine's NetBIOS
name.  The RID of the new machine account is generated from the UID of 
the corresponding Unix account.
</para>

<warning>
	<title>Join the client to the domain immediately</title>

	<para>
	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 <application>Server Manager</application>.  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!
	</para>
</warning>
</sect2>

<sect2>
<title>Using NT4 Server Manager to Add Machine Accounts to the Domain</title>

<para>
If the machine from which you are trying to manage the domain is an 
<application>MS Windows NT4 workstation</application>
then the tool of choice is the package called <command>SRVTOOLS.EXE</command>. 
When executed in the target directory this will unpack 
<command>SrvMge.exe</command> and <command>UsrMgr.exe</command> (both are 
Domain Management tools for MS Windows NT4 workstation.
</para>

<para>
If your workstation is any other MS Windows product you should download the
<command>Nexus.exe</command> package from the Microsoft web site. When executed 
from the target directory this will unpack the same tools but for use on 
<application>MS Windows 9x/Me/200x/XP</application>.
</para>

<para>
Launch the <command>srvmgr.exe</command> (Server Manager for Domains) and follow these steps:
</para>

<procedure>
<title>Server Manager Account Machine Account Management</title>
	<step><para>
	From the menu select <guimenu>Computer</guimenu>
	</para></step>

	<step><para>
	Click on <guimenuitem>Select Domain</guimenuitem>
	</para></step>

	<step><para>
	Click on the name of the domain you wish to administer in the
	<guilabel>Select Domain</guilabel> panel and then click 
	<guibutton>OK</guibutton>.
	</para></step>

	<step><para>
	Again from the menu select <guimenu>Computer</guimenu>
	</para></step>

	<step><para>
	Select <guimenuitem>Add to Domain</guimenuitem>
	</para></step>

	<step><para>
	In the dialog box, click on the radio button to 
	<guilabel>Add NT Workstation of Server</guilabel>, then
	enter the machine name in the field provided, then click the 
	<guibutton>Add</guibutton> button.
	</para></step>
</procedure>

</sect2>

<sect2>
<title>"On-the-Fly" Creation of Machine Trust Accounts</title>

<para>
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.
</para>

<para>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
<ulink url="smb.conf.5.html#ADDMACHINESCRIPT">add machine script</ulink> option in
<filename>smb.conf</filename>. This method is not required, however; corresponding Unix
accounts may also be created manually.
</para>


<para>
Below is an example for a RedHat Linux system.
</para>

<para><programlisting>
[global]
   # &lt;...remainder of parameters...&gt;
   add machine script = /usr/sbin/useradd -d /dev/null -g 100 -s /bin/false -M %u 
</programlisting></para>


</sect2>


<sect2><title>Making an MS Windows Workstation or Server a Domain Member</title>

<para>
The procedure for making an MS Windows workstation of server a member of the domain varies
with the version of Windows:
</para>

<sect3>
	<title>Windows 200x XP Professional</title>

	<para>
	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. 
	</para>

	<para>
	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
	<filename>/etc/passwd</filename>.
	</para>

	<para>
	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 <emphasis>root</emphasis>
	then this is easily mapped to root using the file pointed to be the &smb.conf; parameter
	<parameter>username map = /etc/samba/smbusers</parameter>.
	</para>

	<para>
	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.
	</para>
</sect3>

<sect3>
	<title>Windows NT4</title>

	<para>
	If the machine trust account was created manually, on the
	Identification Changes menu enter the domain name, but do not
	check the box <guilabel>Create a Computer Account in the Domain</guilabel>.
	In this case, the existing machine trust account is used to join the machine 
	to the domain.
	</para>

	<para>
	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 <guilabel>Create a Computer Account in the 
	Domain</guilabel>.  In this case, joining the domain proceeds as above
	for Windows 2000 (i.e., you must supply a Samba administrative account when
	prompted).
	</para>
</sect3>

<sect3>
	<title>Samba</title>

	<para>Joining a Samba client to a domain is documented in 
	the <link linkend="domain-member-server">Domain Member Server</link> section of this chapter chapter.
	</para>
</sect3>

</sect2>
</sect1>

<sect1 id="domain-member-server">
<title>Domain Member Server</title>

<para>
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.
</para>

<para>
<emphasis>
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.
</emphasis>
</para>

<para>
Please refer to the <link linkend="samba-pdc">Domain Control chapter</link>
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.
</para>

<sect2>
<title>Joining an NT4 type Domain with Samba-3</title>

<para>
	<table frame="all"><title>Assumptions</title>
<tgroup align="left" cols="2">
	<tbody>
	<row><entry>NetBIOS name:</entry><entry>SERV1</entry></row>
	<row><entry>Win2K/NT domain name:</entry><entry>DOM</entry></row>
	<row><entry>Domain's PDC NetBIOS name:</entry><entry>DOMPDC</entry></row>
	<row><entry>Domain's BDC NetBIOS names:</entry><entry>DOMBDC1 and DOMBDC2</entry></row>
</tbody>
</tgroup>
</table>
</para>

<para>
First, you must edit your &smb.conf; file to tell Samba it should
now use domain security.
</para>

<para>
Change (or add) your <ulink url="smb.conf.5.html#SECURITY">
<parameter>security</parameter></ulink> line in the [global] section 
of your &smb.conf; to read:
</para>

<para>
<programlisting>
security = domain
</programlisting>
</para>

<para>
Next change the <ulink url="smb.conf.5.html#WORKGROUP"><parameter>
workgroup</parameter></ulink> line in the <parameter>[global]</parameter>
section to read: 
</para>

<para>
<programlisting>
workgroup = DOM
</programlisting>
</para>

<para>
as this is the name of the domain we are joining.
</para>

<para>
You must also have the parameter <ulink url="smb.conf.5.html#ENCRYPTPASSWORDS">
<parameter>encrypt passwords</parameter></ulink> set to <constant>yes
</constant> in order for your users to authenticate to the NT PDC.
</para>

<para>
Finally, add (or modify) a <ulink url="smb.conf.5.html#PASSWORDSERVER">
<parameter>password server</parameter></ulink> line in the [global]
section to read: 
</para>

<para>
<programlisting>
password server = DOMPDC DOMBDC1 DOMBDC2
</programlisting>
</para>

<para>
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.
</para>

<para>
Alternatively, if you want smbd to automatically determine 
the list of Domain controllers to use for authentication, you may 
set this line to be:
</para>

<para>
<programlisting>
password server = *
</programlisting>
</para>

<para>
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.
</para>

<para>
In order to actually join the domain, you must run this command:
</para>

<para>
<screen>
<prompt>root# </prompt><userinput>net join -S DOMPDC -U<replaceable>Administrator%password</replaceable></userinput>
</screen>
</para>

<para>
If the <option>-S DOMPDC</option> argument is not given then
the domain name will be obtained from &smb.conf;.
</para>

<para>
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, we use it for the <option>-S</option> option. 
The <replaceable>Administrator%password</replaceable> 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:
</para>

<para>
<computeroutput>Joined domain DOM.</computeroutput>
or <computeroutput>Joined 'SERV1' to realm 'MYREALM'</computeroutput>
</para>

<para>
in your terminal window. See the <ulink url="net.8.html">
net(8)</ulink> man page for more details.
</para>

<para>
This process joins the server to the domain without having to create the machine
trust account on the PDC beforehand.
</para>

<para>
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:
</para>

<para>
<filename>/usr/local/samba/private/secrets.tdb</filename>
</para>

<para>
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.
</para>

<para>
Finally, restart your Samba daemons and get ready for 
clients to begin using domain security!
</para>

</sect2>

<sect2>
<title>Why is this better than security = server?</title>

<para>
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 <constant>DOM\fred
</constant> 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 
<ulink url="smb.conf.5.html#SECURITYEQUALSSERVER">security = server</ulink>, 
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.
</para>

<para>
Please refer to the <link linkend="winbind">Winbind</link> chapter 
for information on a system to automatically
assign UNIX uids and gids to Windows NT Domain users and groups.
</para>

<para>
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).
</para>

<para>
In addition, with <parameter>security = server</parameter> 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 <parameter>security = domain</parameter>, 
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.
</para>

<para>
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. 
</para>

<note>
<para>
Much of the text of this document 
was first published in the Web magazine 
<ulink url="http://www.linuxworld.com">LinuxWorld</ulink> as the article <ulink
url="http://www.linuxworld.com/linuxworld/lw-1998-10/lw-10-samba.html">Doing 
the NIS/NT Samba</ulink>.
</para>
</note>

</sect2>
</sect1>

<sect1 id="ads-member">
<title>Samba ADS Domain Membership</title>

<para>
This is a rough guide to setting up Samba 3.0 with Kerberos authentication against a
Windows2000 KDC. A familiarity with Kerberos is assumed.
</para> 

<sect2>
<title>Setup your <filename>smb.conf</filename></title>

<para>
You must use at least the following 3 options in &smb.conf;:
</para>

<para><programlisting>
	realm = your.kerberos.REALM
	security = ADS
	encrypt passwords = yes
</programlisting></para>

<para>
In case samba can't figure out your ads server using your realm name, use the 
<parameter>ads server</parameter> option in <filename>smb.conf</filename>:
<programlisting>
	ads server = your.kerberos.server
</programlisting>
</para>

<note><para>
You do <emphasis>not</emphasis> need a smbpasswd file, and older clients will be authenticated as 
if <parameter>security = domain</parameter>, 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.
</para></note>

</sect2>
  
<sect2>
<title>Setup your <filename>/etc/krb5.conf</filename></title>

<para>
The minimal configuration for <filename>krb5.conf</filename> is:
</para>

<para><programlisting>
	[realms]
	    YOUR.KERBEROS.REALM = {
		kdc = your.kerberos.server
	    }
</programlisting></para>

<para>
Test your config by doing a <userinput>kinit
<replaceable>USERNAME</replaceable>@<replaceable>REALM</replaceable></userinput> and
making sure that your password is accepted by the Win2000 KDC.
</para>

<note><para>
The realm must be uppercase or you will get <errorname>Cannot find KDC for
requested realm while getting initial credentials</errorname> error.
</para></note>

<note><para>
Time between the two servers must be synchronized.  You will get a
<errorname>kinit(v5): Clock skew too great while getting initial credentials</errorname>
if the time difference is more than five minutes. 
</para></note>

<para>
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. 
</para>

<para>
The easiest way to ensure you get this right is to add a 
<filename>/etc/hosts</filename> entry mapping the IP address of your KDC to 
its NetBIOS name. If you don't get this right then you will get a 
<errorname>local error</errorname> when you try to join the realm.
</para>

<para>
If all you want is Kerberos support in &smbclient; then you can skip
straight to <link linkend="ads-test-smbclient">Test with &smbclient;</link> now. 
<link linkend="ads-create-machine-account">Creating a computer account</link> 
and <link linkend="ads-test-server">testing your servers</link>
is only needed if you want Kerberos support for &smbd; and &winbindd;.
</para>

</sect2>

<sect2 id="ads-create-machine-account">
<title>Create the computer account</title>

<para>
As a user that has write permission on the Samba private directory
(usually root) run:
<programlisting>
	&rootprompt;<userinput>net join -U Administrator%password</userinput>
</programlisting>
</para>

<sect3>
<title>Possible errors</title>

<para>
<variablelist>
	<varlistentry><term><errorname>ADS support not compiled in</errorname></term>
	<listitem><para>Samba must be reconfigured (remove config.cache) and recompiled
	(make clean all install) after the Kerberos libs and headers are installed.
	</para></listitem></varlistentry>

	<varlistentry><term><errorname>net join prompts for user name</errorname></term>
	<listitem><para>You need to login to the domain using <userinput>kinit
	<replaceable>USERNAME</replaceable>@<replaceable>REALM</replaceable></userinput>.
	<replaceable>USERNAME</replaceable> must be a user who has rights to add a machine
	to the domain.  </para></listitem></varlistentry>
</variablelist>
</para>

</sect3>

</sect2>

<sect2 id="ads-test-server">
<title>Test your server setup</title>

<para>
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.
</para>

<para>
On a Windows 2000 client try <userinput>net use * \\server\share</userinput>. You should
be logged in with Kerberos without needing to know a password. If
this fails then run <userinput>klist tickets</userinput>. Did you get a ticket for the
server? Does it have an encoding type of DES-CBC-MD5 ? 
</para>

</sect2>

<sect2 id="ads-test-smbclient">
<title>Testing with &smbclient;</title>

<para>
On your Samba server try to login to a Win2000 server or your Samba
server using &smbclient; and Kerberos. Use &smbclient; as usual, but
specify the <parameter>-k</parameter> option to choose Kerberos authentication.
</para>

</sect2>

<sect2>
<title>Notes</title>

<para>
You must change administrator password at least once after DC 
install, to create the right encoding types
</para>

<para>
W2k doesn't seem to create the _kerberos._udp and _ldap._tcp in
their defaults DNS setup. Maybe fixed in service packs?
</para>

</sect2>
</sect1>

<sect1>
<title>Common Errors</title>

<para>
In the process of adding / deleting / re-adding domain member machine accounts there are
many traps for the unwary player and there are many <quote>little</quote> 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.
</para>

<sect2>
<title>Can Not Add Machine Back to Domain</title>

<para>
<emphasis>Problem:</emphasis> 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 doesn't. Why is this failing?
</para>

<para>
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.
</para>

</sect2>

<sect2>
<title>Adding Machine to Domain Fails</title>

<para>
Adding a Windows 200x or XP Professional machine to the Samba PDC Domain fails with a
message that, <errorname>The machine could not be added at this time, there is a network problem.
Please try again later.</errorname> Why?
</para>

<para>
You should check that there is an <parameter>add machine script</parameter> in your &smb.conf;
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 <parameter>log level</parameter>
in the &smb.conf; file to level 10, then try to rejoin the domain. Check the logs to see which
operation is failing.
</para>

<para>
Possible causes include:
</para>

<itemizedlist>
	<listitem><para>
	The script does not actually exist, or could not be located in the path specified.
	</para>

	<para>
	<emphasis>Corrective Action:</emphasis> Fix it. Make sure that when run manually
	that the script will add both the Unix system account _and_ the Samba SAM account.
	</para></listitem>

	<listitem><para>
	The machine could not be added to the Unix system accounts file <filename>/etc/passwd</filename>
	</para>

	<para>
	<emphasis>Corrective Action:</emphasis> Check that the machine name is a legal Unix
	system account name. ie: If the Unix utility <command>useradd</command> is called
	then make sure that the machine name you are trying to add can be added using this
	tool. <command>Useradd</command> on some systems will not allow any upper case characters
	nor will it allow spaces in the name.
	</para></listitem>
</itemizedlist>

</sect2>

</sect1>
</chapter>