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This chapter provides an overview of the security modes of which Samba is capable and how they relate to MS
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Windows servers and clients.
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A question often asked is, “<span class="quote">Why would I want to use Samba?</span>” Most chapters contain a section that
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A question often asked is, <span class="quote">“<span class="quote">Why would I want to use Samba?</span>”</span> Most chapters contain a section that
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highlights features and benefits. We hope that the information provided will help to answer this question. Be
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warned though, we want to be fair and reasonable, so not all features are positive toward Samba. The benefit
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may be on the side of our competition.
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</p><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2558832"></a>Features and Benefits</h2></div></div></div><p>
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</p><div class="sect1" title="Features and Benefits"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2564889"></a>Features and Benefits</h2></div></div></div><p>
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Two men were walking down a dusty road, when one suddenly kicked up a small red stone. It
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hurt his toe and lodged in his sandal. He took the stone out and cursed it with a passion
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and fury befitting his anguish. The other looked at the stone and said, “<span class="quote">This is a garnet.
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I can turn that into a precious gem and some day it will make a princess very happy!</span>”
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and fury befitting his anguish. The other looked at the stone and said, <span class="quote">“<span class="quote">This is a garnet.
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I can turn that into a precious gem and some day it will make a princess very happy!</span>”</span>
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The moral of this tale: Two men, two very different perspectives regarding the same stone.
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Like it or not, Samba is like that stone. Treat it the right way and it can bring great
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pleasure, but if you are forced to use it and have no time for its secrets, then it can be
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a source of discomfort.
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Samba started out as a project that sought to provide interoperability for MS Windows 3.x
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clients with a UNIX server. It has grown up a lot since its humble beginnings and now provides
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features and functionality fit for large-scale deployment. It also has some warts. In sections
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like this one, we tell of both.
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So, what are the benefits of the features mentioned in this chapter?
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</p><div class="itemizedlist"><ul type="disc"><li><p>
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</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>
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Samba-3 can replace an MS Windows NT4 domain controller.
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</p></li><li class="listitem"><p>
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Samba-3 offers excellent interoperability with MS Windows NT4-style
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domains as well as natively with Microsoft Active Directory domains.
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</p></li><li class="listitem"><p>
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Samba-3 permits full NT4-style interdomain trusts.
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</p></li><li class="listitem"><p>
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Samba has security modes that permit more flexible authentication
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than is possible with MS Windows NT4 domain controllers.
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</p></li><li class="listitem"><p>
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Samba-3 permits use of multiple concurrent account database backends.
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(Encrypted passwords that are stored in the account database are in
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formats that are unique to Windows networking).
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</p></li><li class="listitem"><p>
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The account database backends can be distributed
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and replicated using multiple methods. This gives Samba-3
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greater flexibility than MS Windows NT4 and in many cases a
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significantly higher utility than Active Directory domains
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with MS Windows 200x.
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</p></li></ul></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2558991"></a>Server Types</h2></div></div></div><p>
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</p></li></ul></div></div><div class="sect1" title="Server Types"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2565049"></a>Server Types</h2></div></div></div><p>
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Administrators of Microsoft networks often refer to three different types of servers:
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</p><div class="itemizedlist"><ul type="disc"><li><p>Domain Controller</p><div class="itemizedlist"><ul type="circle"><li><p>Primary Domain Controller (PDC)</p></li><li><p>Backup Domain Controller (BDC)</p></li><li><p>ADS Domain Controller</p></li></ul></div></li><li><p>Domain Member Server</p><div class="itemizedlist"><ul type="circle"><li><p>Active Directory Domain Server</p></li><li><p>NT4 Style Domain Domain Server</p></li></ul></div></li><li><p>Standalone Server</p></li></ul></div><p>
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</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Domain Controller</p><div class="itemizedlist"><ul class="itemizedlist" type="circle"><li class="listitem"><p>Primary Domain Controller (PDC)</p></li><li class="listitem"><p>Backup Domain Controller (BDC)</p></li><li class="listitem"><p>ADS Domain Controller</p></li></ul></div></li><li class="listitem"><p>Domain Member Server</p><div class="itemizedlist"><ul class="itemizedlist" type="circle"><li class="listitem"><p>Active Directory Domain Server</p></li><li class="listitem"><p>NT4 Style Domain Domain Server</p></li></ul></div></li><li class="listitem"><p>Standalone Server</p></li></ul></div><p>
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The chapters covering domain control (<a class="link" href="samba-pdc.html" title="Chapter�4.�Domain Control">Domain Control</a>),
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backup domain control (<a class="link" href="samba-bdc.html" title="Chapter�5.�Backup Domain Control">Backup Domain Control</a>), and
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domain membership (<a class="link" href="domain-member.html" title="Chapter�6.�Domain Membership">Domain Membership</a>) provide
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You are strongly encouraged to become intimately familiar with these chapters because
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they lay the foundation for deployment of Samba domain security.
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A Standalone server is autonomous in respect of the source of its account backend.
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Refer to <a class="link" href="StandAloneServer.html" title="Chapter�7.�Standalone Servers">Standalone Servers</a> to gain a wider appreciation
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of what is meant by a server being configured as a <span class="emphasis"><em>standalone</em></span> server.
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</p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2559136"></a>Samba Security Modes</h2></div></div></div><p>
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</p></div><div class="sect1" title="Samba Security Modes"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2565193"></a>Samba Security Modes</h2></div></div></div><p>
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In this section, the function and purpose of Samba's security modes are described. An accurate understanding of
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how Samba implements each security mode as well as how to configure MS Windows clients for each mode will
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significantly reduce user complaints and administrator heartache.
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Microsoft Windows networking uses a protocol that was originally called the Server Message Block (SMB)
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protocol. Since some time around 1996 the protocol has been better known as the Common Internet Filesystem
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In the SMB/CIFS networking world, there are only two types of security: <span class="emphasis"><em>user-level</em></span> and
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<span class="emphasis"><em>share level</em></span>. We refer to these collectively as <span class="emphasis"><em>security levels</em></span>. In
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implementing these two security levels, Samba provides flexibilities that are not available with MS Windows
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The term <code class="literal">client</code> refers to all agents whether it is a Windows workstation, a Windows server,
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another Samba server, or any vanilla SMB or CIFS client application (e.g., <code class="literal">smbclient</code>) that
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make use of services provided by an SMB/CIFS server.
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</p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2559298"></a>User Level Security</h3></div></div></div><p>
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</p><div class="sect2" title="User Level Security"><div class="titlepage"><div><div><h3 class="title"><a name="id2565355"></a>User Level Security</h3></div></div></div><p>
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We describe user-level security first because its simpler. In user-level security, the client sends a session
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setup request directly following protocol negotiation. This request provides a username and password. The
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server can either accept or reject that username/password combination. At this stage the server has no idea
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what share the client will eventually try to connect to, so it can't base the
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<span class="emphasis"><em>accept/reject</em></span> on anything other than:
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</p><div class="orderedlist"><ol type="1"><li><p>the username/password.</p></li><li><p>the name of the client machine.</p></li></ol></div><p>
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</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>the username/password.</p></li><li class="listitem"><p>the name of the client machine.</p></li></ol></div><p>
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If the server accepts the username/password credentials, the client expects to be able to mount shares (using
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a <span class="emphasis"><em>tree connection</em></span>) without further specifying a password. It expects that all access
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rights will be as the username/password credentials set that was specified in the initial <span class="emphasis"><em>session
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setup</em></span>.
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It is also possible for a client to send multiple <span class="emphasis"><em>session setup</em></span>
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requests. When the server responds, it gives the client a <span class="emphasis"><em>uid</em></span> to use
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as an authentication tag for that username/password. The client can maintain multiple
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authentication contexts in this way (WinDD is an example of an application that does this).
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Windows networking user account names are case-insensitive, meaning that upper-case and lower-case characters
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in the account name are considered equivalent. They are said to be case-preserving, but not case significant.
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Windows and LanManager systems previous to Windows NT version 3.10 have case-insensitive passwords that were
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not necessarily case-preserving. All Windows NT family systems treat passwords as case-preserving and
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</p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2559423"></a>Example Configuration</h4></div></div></div><p>
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</p><div class="sect3" title="Example Configuration"><div class="titlepage"><div><div><h4 class="title"><a name="id2565481"></a>Example Configuration</h4></div></div></div><p>
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The <code class="filename">smb.conf</code> parameter that sets user-level security is:
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</p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2559444"></a><em class="parameter"><code>security = user</code></em></td></tr></table><p>
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</p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="indexterm" name="id2565502"></a><em class="parameter"><code>security = user</code></em></td></tr></table><p>
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This is the default setting since Samba-2.2.x.
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</p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2559461"></a>Share-Level Security</h3></div></div></div><p>
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</p></div></div><div class="sect2" title="Share-Level Security"><div class="titlepage"><div><div><h3 class="title"><a name="id2565518"></a>Share-Level Security</h3></div></div></div><p>
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<a class="indexterm" name="id2565532"></a>
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In share-level security, the client authenticates itself separately for each share. It sends a password along
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with each tree connection request (share mount), but it does not explicitly send a username with this
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operation. The client expects a password to be associated with each share, independent of the user. This means
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shadow: files nis ldap
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group: files nis ldap
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In the example shown here (not likely to be used in practice) the lookup will check
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<code class="filename">/etc/passwd</code> and <code class="filename">/etc/group</code>, if not found it will check NIS, then
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</p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2559620"></a>Example Configuration</h4></div></div></div><p>
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</p><div class="sect3" title="Example Configuration"><div class="titlepage"><div><div><h4 class="title"><a name="id2565677"></a>Example Configuration</h4></div></div></div><p>
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The <code class="filename">smb.conf</code> parameter that sets share-level security is:
195
</p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2559641"></a><em class="parameter"><code>security = share</code></em></td></tr></table></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2559653"></a>Domain Security Mode (User-Level Security)</h3></div></div></div><p>
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<a class="indexterm" name="id2559696"></a>
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</p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="indexterm" name="id2565698"></a><em class="parameter"><code>security = share</code></em></td></tr></table></div></div><div class="sect2" title="Domain Security Mode (User-Level Security)"><div class="titlepage"><div><div><h3 class="title"><a name="id2565710"></a>Domain Security Mode (User-Level Security)</h3></div></div></div><p>
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Domain security provides a mechanism for storing all user and group accounts in a central, shared, account
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repository. The centralized account repository is shared between domain (security) controllers. Servers that
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act as domain controllers provide authentication and validation services to all machines that participate in
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logon and authentication services. Usually, BDCs will answer network logon requests more responsively than
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When Samba is operating in <a class="link" href="smb.conf.5.html#SECURITY" target="_top">security = domain</a> mode, the Samba server has a
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domain security trust account (a machine account) and causes all authentication requests to be passed through
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to the domain controllers. In other words, this configuration makes the Samba server a domain member server,
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even when it is in fact acting as a domain controller. All machines that participate in domain security must
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have a machine account in the security database.
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<a class="indexterm" name="id2565868"></a>
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Within the domain security environment, the underlying security architecture uses user-level security. Even
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machines that are domain members must authenticate on startup. The machine account consists of an account
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entry in the accounts database, the name of which is the NetBIOS name of the machine and of which the password
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it cannot be trusted. The machine account is referred to as a machine trust account.
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There are three possible domain member configurations:
233
</p><div class="orderedlist"><ol type="1"><li><p>Primary domain controller (PDC) - of which there is one per domain.</p></li><li><p>Backup domain controller (BDC) - of which there can be any number per domain.</p></li><li><p>Domain member server (DMS) - of which there can be any number per domain.</p></li></ol></div><p>
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<a class="indexterm" name="id2559859"></a>
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</p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Primary domain controller (PDC) - of which there is one per domain.</p></li><li class="listitem"><p>Backup domain controller (BDC) - of which there can be any number per domain.</p></li><li class="listitem"><p>Domain member server (DMS) - of which there can be any number per domain.</p></li></ol></div><p>
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We will discuss each of these in separate chapters. For now, we are most interested in basic DMS
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</p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2559868"></a>Example Configuration</h4></div></div></div><p><span class="emphasis"><em>
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</p><div class="sect3" title="Example Configuration"><div class="titlepage"><div><div><h4 class="title"><a name="id2565925"></a>Example Configuration</h4></div></div></div><p><span class="emphasis"><em>
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Samba as a Domain Member Server
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</em></span></p><p>
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240
<a class="indexterm" name="id2565937"></a>
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This method involves addition of the following parameters in the <code class="filename">smb.conf</code> file:
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</p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2559900"></a><em class="parameter"><code>security = domain</code></em></td></tr><tr><td><a class="indexterm" name="id2559910"></a><em class="parameter"><code>workgroup = MIDEARTH</code></em></td></tr></table><p>
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</p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="indexterm" name="id2565957"></a><em class="parameter"><code>security = domain</code></em></td></tr><tr><td><a class="indexterm" name="id2565968"></a><em class="parameter"><code>workgroup = MIDEARTH</code></em></td></tr></table><p>
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In order for this method to work, the Samba server needs to join the MS Windows NT
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security domain. This is done as follows:
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<a class="indexterm" name="id2559934"></a>
248
</p><div class="procedure"><ol type="1"><li><p>On the MS Windows NT domain controller, using
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<a class="indexterm" name="id2565983"></a>
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<a class="indexterm" name="id2565992"></a>
248
</p><div class="procedure"><ol class="procedure" type="1"><li class="step" title="Step 1"><p>On the MS Windows NT domain controller, using
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the Server Manager, add a machine account for the Samba server.
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</p></li><li><p>On the UNIX/Linux system execute:</p><pre class="screen"><code class="prompt">root# </code><strong class="userinput"><code>net rpc join -U administrator%password</code></strong></pre></li></ol></div><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
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<a class="indexterm" name="id2559981"></a>
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</p></li><li class="step" title="Step 2"><p>On the UNIX/Linux system execute:</p><pre class="screen"><code class="prompt">root# </code><strong class="userinput"><code>net rpc join -U administrator%password</code></strong></pre></li></ol></div><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
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<a class="indexterm" name="id2566038"></a>
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Samba-2.2.4 and later Samba 2.2.x series releases can autojoin a Windows NT4-style domain just by executing:
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</p><pre class="screen">
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<code class="prompt">root# </code><strong class="userinput"><code>smbpasswd -j <em class="replaceable"><code>DOMAIN_NAME</code></em> -r <em class="replaceable"><code>PDC_NAME</code></em> \
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-U Administrator%<em class="replaceable"><code>password</code></em></code></strong>
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<a class="indexterm" name="id2560012"></a>
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<a class="indexterm" name="id2566070"></a>
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Samba-3 can do the same by executing:
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</p><pre class="screen">
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<code class="prompt">root# </code><strong class="userinput"><code>net rpc join -U Administrator%<em class="replaceable"><code>password</code></em></code></strong>
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It is not necessary with Samba-3 to specify the <em class="replaceable"><code>DOMAIN_NAME</code></em> or the
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<em class="replaceable"><code>PDC_NAME</code></em>, as it figures this out from the <code class="filename">smb.conf</code> file settings.
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<a class="indexterm" name="id2560058"></a>
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<a class="indexterm" name="id2560064"></a>
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<a class="indexterm" name="id2560070"></a>
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<a class="indexterm" name="id2566115"></a>
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<a class="indexterm" name="id2566121"></a>
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<a class="indexterm" name="id2566127"></a>
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Use of this mode of authentication requires there to be a standard UNIX account for each user in order to
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assign a UID once the account has been authenticated by the Windows domain controller. This account can be
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blocked to prevent logons by clients other than MS Windows through means such as setting an invalid shell in
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the <code class="filename">/etc/passwd</code> entry. The best way to allocate an invalid shell to a user account is to
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set the shell to the file <code class="filename">/bin/false</code>.
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<a class="indexterm" name="id2560097"></a>
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<a class="indexterm" name="id2560104"></a>
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<a class="indexterm" name="id2566155"></a>
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<a class="indexterm" name="id2566161"></a>
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Domain controllers can be located anywhere that is convenient. The best advice is to have a BDC on every
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physical network segment, and if the PDC is on a remote network segment the use of WINS (see <a class="link" href="NetworkBrowsing.html" title="Chapter�10.�Network Browsing">Network Browsing</a> for more information) is almost essential.
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An alternative to assigning UIDs to Windows users on a Samba member server is presented in <a class="link" href="winbind.html" title="Chapter�24.�Winbind: Use of Domain Accounts">Winbind</a>, <a class="link" href="winbind.html" title="Chapter�24.�Winbind: Use of Domain Accounts">Winbind: Use of Domain Accounts</a>.
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For more information regarding domain membership, <a class="link" href="domain-member.html" title="Chapter�6.�Domain Membership">Domain Membership</a>.
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</p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2560148"></a>ADS Security Mode (User-Level Security)</h3></div></div></div><p>
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<a class="indexterm" name="id2560156"></a>
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<a class="indexterm" name="id2560163"></a>
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</p></div></div><div class="sect2" title="ADS Security Mode (User-Level Security)"><div class="titlepage"><div><div><h3 class="title"><a name="id2566205"></a>ADS Security Mode (User-Level Security)</h3></div></div></div><p>
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<a class="indexterm" name="id2566214"></a>
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<a class="indexterm" name="id2566220"></a>
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Both Samba-2.2, and Samba-3 can join an Active Directory domain using NT4 style RPC based security. This is
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possible if the domain is run in native mode. Active Directory in native mode perfectly allows NT4-style
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domain members. This is contrary to popular belief.
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domain, would still require NT-compatible authentication data. Samba in AD-member mode can accept Kerberos
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<a class="indexterm" name="id2560187"></a>
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<a class="indexterm" name="id2560194"></a>
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<a class="indexterm" name="id2566245"></a>
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<a class="indexterm" name="id2566251"></a>
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Sites that use Microsoft Windows active directory services (ADS) should be aware of the significance of the
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terms: <code class="literal">native mode</code> and <code class="literal">mixed mode</code> ADS operation. The term
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<code class="literal">realm</code> is used to describe a Kerberos-based security architecture (such as is used by
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</p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2560220"></a>Example Configuration</h4></div></div></div><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2560232"></a><em class="parameter"><code>realm = your.kerberos.REALM</code></em></td></tr><tr><td><a class="indexterm" name="id2560242"></a><em class="parameter"><code>security = ADS</code></em></td></tr></table><p>
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</p><div class="sect3" title="Example Configuration"><div class="titlepage"><div><div><h4 class="title"><a name="id2566278"></a>Example Configuration</h4></div></div></div><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="indexterm" name="id2566289"></a><em class="parameter"><code>realm = your.kerberos.REALM</code></em></td></tr><tr><td><a class="indexterm" name="id2566300"></a><em class="parameter"><code>security = ADS</code></em></td></tr></table><p>
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The following parameter may be required:
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</p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2560263"></a><em class="parameter"><code>password server = your.kerberos.server</code></em></td></tr></table><p>
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</p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="indexterm" name="id2566320"></a><em class="parameter"><code>password server = your.kerberos.server</code></em></td></tr></table><p>
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Please refer to <a class="link" href="domain-member.html" title="Chapter�6.�Domain Membership">Domain Membership</a>, and <a class="link" href="domain-member.html#ads-member" title="Samba ADS Domain Membership">Samba
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ADS Domain Membership</a> for more information regarding this configuration option.
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</p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2560291"></a>Server Security (User Level Security)</h3></div></div></div><p>
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</p></div></div><div class="sect2" title="Server Security (User Level Security)"><div class="titlepage"><div><div><h3 class="title"><a name="id2566348"></a>Server Security (User Level Security)</h3></div></div></div><p>
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Server security mode is left over from the time when Samba was not capable of acting
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as a domain member server. It is highly recommended not to use this feature. Server
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security mode has many drawbacks that include:
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</p><div class="itemizedlist"><ul type="disc"><li><p>Potential account lockout on MS Windows NT4/200x password servers.</p></li><li><p>Lack of assurance that the password server is the one specified.</p></li><li><p>Does not work with Winbind, which is particularly needed when storing profiles remotely.</p></li><li><p>This mode may open connections to the password server and keep them open for extended periods.</p></li><li><p>Security on the Samba server breaks badly when the remote password server suddenly shuts down.</p></li><li><p>With this mode there is NO security account in the domain that the password server belongs to for the Samba server.</p></li></ul></div><p>
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<a class="indexterm" name="id2560344"></a>
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<a class="indexterm" name="id2560351"></a>
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</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Potential account lockout on MS Windows NT4/200x password servers.</p></li><li class="listitem"><p>Lack of assurance that the password server is the one specified.</p></li><li class="listitem"><p>Does not work with Winbind, which is particularly needed when storing profiles remotely.</p></li><li class="listitem"><p>This mode may open connections to the password server and keep them open for extended periods.</p></li><li class="listitem"><p>Security on the Samba server breaks badly when the remote password server suddenly shuts down.</p></li><li class="listitem"><p>With this mode there is NO security account in the domain that the password server belongs to for the Samba server.</p></li></ul></div><p>
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<a class="indexterm" name="id2566402"></a>
312
<a class="indexterm" name="id2566408"></a>
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In server security mode the Samba server reports to the client that it is in user-level security. The client
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then does a session setup as described earlier. The Samba server takes the username/password that the client
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sends and attempts to log into the <a class="link" href="smb.conf.5.html#PASSWORDSERVER" target="_top">password server</a> by sending exactly the same
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user mode server. This requires an additional parameter <a class="link" href="smb.conf.5.html#PASSWORDSERVER" target="_top">password server</a> that points to
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the real authentication server. The real authentication server can be another Samba server, or it can be a
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Windows NT server, the latter being natively capable of encrypted password support.
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</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
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<a class="indexterm" name="id2560439"></a>
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<a class="indexterm" name="id2560445"></a>
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</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
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<a class="indexterm" name="id2566496"></a>
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<a class="indexterm" name="id2566503"></a>
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When Samba is running in <span class="emphasis"><em>server security mode</em></span>, it is essential that the parameter
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<span class="emphasis"><em>password server</em></span> is set to the precise NetBIOS machine name of the target authentication
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server. Samba cannot determine this from NetBIOS name lookups because the choice of the target authentication
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server is arbitrary and cannot be determined from a domain name. In essence, a Samba server that is in
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<span class="emphasis"><em>server security mode</em></span> is operating in what used to be known as workgroup mode.
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</p></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2560468"></a>Example Configuration</h4></div></div></div><p><span class="emphasis"><em>
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</p></div><div class="sect3" title="Example Configuration"><div class="titlepage"><div><div><h4 class="title"><a name="id2566526"></a>Example Configuration</h4></div></div></div><p><span class="emphasis"><em>
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Using MS Windows NT as an Authentication Server
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</em></span></p><p>
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This method involves the additions of the following parameters in the <code class="filename">smb.conf</code> file:
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</p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2560495"></a><em class="parameter"><code>encrypt passwords = Yes</code></em></td></tr><tr><td><a class="indexterm" name="id2560505"></a><em class="parameter"><code>security = server</code></em></td></tr><tr><td><a class="indexterm" name="id2560516"></a><em class="parameter"><code>password server = "NetBIOS_name_of_a_DC"</code></em></td></tr></table><p>
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</p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="indexterm" name="id2566552"></a><em class="parameter"><code>encrypt passwords = Yes</code></em></td></tr><tr><td><a class="indexterm" name="id2566562"></a><em class="parameter"><code>security = server</code></em></td></tr><tr><td><a class="indexterm" name="id2566573"></a><em class="parameter"><code>password server = "NetBIOS_name_of_a_DC"</code></em></td></tr></table><p>
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There are two ways of identifying whether or not a username and password pair is valid.
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One uses the reply information provided as part of the authentication messaging
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process, the other uses just an error code.
349
<a class="indexterm" name="id2560536"></a>
350
<a class="indexterm" name="id2560542"></a>
349
<a class="indexterm" name="id2566593"></a>
350
<a class="indexterm" name="id2566599"></a>
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The downside of this mode of configuration is that for security reasons Samba
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will send the password server a bogus username and a bogus password, and if the remote
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server fails to reject the bogus username and password pair, then an alternative mode of
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Use of this mode of authentication requires a standard UNIX account for the user.
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This account can be blocked to prevent logons by non-SMB/CIFS clients.
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</p></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2560566"></a>Password Checking</h2></div></div></div><p>
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</p></div></div></div><div class="sect1" title="Password Checking"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2566623"></a>Password Checking</h2></div></div></div><p>
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MS Windows clients may use encrypted passwords as part of a challenge/response
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authentication model (a.k.a. NTLMv1 and NTLMv2) or alone, or clear-text strings for simple
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password-based authentication. It should be realized that with the SMB protocol,
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the password is passed over the network either in plaintext or encrypted, but
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not both in the same authentication request.
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<a class="indexterm" name="id2560583"></a>
367
<a class="indexterm" name="id2560589"></a>
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<a class="indexterm" name="id2566640"></a>
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<a class="indexterm" name="id2566646"></a>
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When encrypted passwords are used, a password that has been entered by the user
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is encrypted in two ways:
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</p><div class="itemizedlist"><ul type="disc"><li><p>An MD4 hash of the unicode of the password
370
</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>An MD4 hash of the unicode of the password
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string. This is known as the NT hash.
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</p></li><li><p>The password is converted to uppercase,
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</p></li><li class="listitem"><p>The password is converted to uppercase,
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and then padded or truncated to 14 bytes. This string is
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then appended with 5 bytes of NULL characters and split to
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form two 56-bit DES keys to encrypt a "magic" 8-byte value.
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The resulting 16 bytes form the LanMan hash.
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</p></li></ul></div><p>
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<a class="indexterm" name="id2560619"></a>
378
<a class="indexterm" name="id2566676"></a>
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MS Windows 95 pre-service pack 1 and MS Windows NT versions 3.x and version 4.0 pre-service pack 3 will use
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either mode of password authentication. All versions of MS Windows that follow these versions no longer
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support plain-text passwords by default.
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<a class="indexterm" name="id2560635"></a>
383
<a class="indexterm" name="id2566692"></a>
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MS Windows clients have a habit of dropping network mappings that have been idle
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for 10 minutes or longer. When the user attempts to use the mapped drive
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connection that has been dropped, the client re-establishes the connection using
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The following parameters can be used to work around the issue of Windows 9x/Me clients
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uppercasing usernames and passwords before transmitting them to the SMB server
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when using clear-text authentication:
399
</p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2560675"></a></td></tr><tr><td><a class="indexterm" name="id2560681"></a></td></tr></table><p>
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</p><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="indexterm" name="id2566732"></a></td></tr><tr><td><a class="indexterm" name="id2566739"></a></td></tr></table><p>
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By default Samba will convert to lowercase the username before attempting to lookup the user
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in the database of local system accounts. Because UNIX usernames conventionally
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only contain lowercase characters, the <a class="link" href="smb.conf.5.html#USERNAME-LEVEL" target="_top">username-level</a> parameter
403
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is rarely needed.
405
<a class="indexterm" name="id2560706"></a>
405
<a class="indexterm" name="id2566763"></a>
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However, passwords on UNIX systems often make use of mixed-case characters. This means that in order for a
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user on a Windows 9x/Me client to connect to a Samba server using clear-text authentication, the
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<a class="link" href="smb.conf.5.html#PASSWORDLEVEL" target="_top">password level</a> must be set to the maximum number of uppercase letters that
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Samba is a server regardless of which security mode is chosen. When Samba is used outside of a domain security
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context, it is best to leave the security mode at the default setting. By default Samba-3 uses user-mode
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</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2560815"></a>What Makes Samba a Domain Controller?</h3></div></div></div><p>
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<a class="indexterm" name="id2560823"></a>
436
</p></div><div class="sect2" title="What Makes Samba a Domain Controller?"><div class="titlepage"><div><div><h3 class="title"><a name="id2566873"></a>What Makes Samba a Domain Controller?</h3></div></div></div><p>
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<a class="indexterm" name="id2566880"></a>
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The <code class="filename">smb.conf</code> parameter <a class="link" href="smb.conf.5.html#SECURITY" target="_top">security = domain</a> does not really make Samba behave
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as a domain controller. This setting means we want Samba to be a domain member. See <a class="link" href="samba-pdc.html" title="Chapter�4.�Domain Control">Samba as a PDC</a> for more information.
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</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2560852"></a>What Makes Samba a Domain Member?</h3></div></div></div><p>
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</p></div><div class="sect2" title="What Makes Samba a Domain Member?"><div class="titlepage"><div><div><h3 class="title"><a name="id2566910"></a>What Makes Samba a Domain Member?</h3></div></div></div><p>
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Guess! So many others do. But whatever you do, do not think that <a class="link" href="smb.conf.5.html#SECURITY" target="_top">security = user</a>
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makes Samba act as a domain member. Read the manufacturer's manual before the warranty expires. See
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<a class="link" href="domain-member.html" title="Chapter�6.�Domain Membership">Domain Membership</a>, for more information.
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</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2560879"></a>Constantly Losing Connections to Password Server</h3></div></div></div><p>“<span class="quote">
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</p></div><div class="sect2" title="Constantly Losing Connections to Password Server"><div class="titlepage"><div><div><h3 class="title"><a name="id2566937"></a>Constantly Losing Connections to Password Server</h3></div></div></div><p><span class="quote">“<span class="quote">
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Why does server_validate() simply give up rather than re-establish its connection to the
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password server? Though I am not fluent in the SMB protocol, perhaps the cluster server
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process passes along to its client workstation the session key it receives from the password
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server, which means the password hashes submitted by the client would not work on a subsequent
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connection whose session key would be different. So server_validate() must give up.
450
</span>”</p><p>
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</span>”</span></p><p>
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Indeed. That's why <a class="link" href="smb.conf.5.html#SECURITY" target="_top">security = server</a>
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is at best a nasty hack. Please use <a class="link" href="smb.conf.5.html#SECURITY" target="_top">security = domain</a>;
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<a class="link" href="smb.conf.5.html#SECURITY" target="_top">security = server</a> mode is also known as pass-through authentication.
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</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2560937"></a>Stand-alone Server is converted to Domain Controller Now User accounts don't work</h3></div></div></div><p>“<span class="quote">
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</p></div><div class="sect2" title="Stand-alone Server is converted to Domain Controller Now User accounts don't work"><div class="titlepage"><div><div><h3 class="title"><a name="id2566995"></a>Stand-alone Server is converted to Domain Controller Now User accounts don't work</h3></div></div></div><p><span class="quote">“<span class="quote">
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When I try to log in to the DOMAIN, the eventlog shows <span class="emphasis"><em>tried credentials DOMAIN/username; effective
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credentials SERVER/username</em></span>
457
</span>”</p><p>
457
</span>”</span></p><p>
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Usually this is due to a user or machine account being created before the Samba server is configured to be a
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domain controller. Accounts created before the server becomes a domain controller will be
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<span class="emphasis"><em>local</em></span> accounts and authenticated as what looks like a member in the SERVER domain, much
added
removed
docs/htmldocs/Samba3-HOWTO/ServerType.html
