diff options
Diffstat (limited to 'docs/htmldocs/Samba3-HOWTO/samba-bdc.html')
| -rw-r--r-- | docs/htmldocs/Samba3-HOWTO/samba-bdc.html | 557 |
1 files changed, 0 insertions, 557 deletions
diff --git a/docs/htmldocs/Samba3-HOWTO/samba-bdc.html b/docs/htmldocs/Samba3-HOWTO/samba-bdc.html deleted file mode 100644 index 07bc9b5482..0000000000 --- a/docs/htmldocs/Samba3-HOWTO/samba-bdc.html +++ /dev/null @@ -1,557 +0,0 @@ -<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 5. Backup Domain Control</title><link rel="stylesheet" href="../samba.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.75.2"><link rel="home" href="index.html" title="The Official Samba 3.5.x HOWTO and Reference Guide"><link rel="up" href="type.html" title="Part II. Server Configuration Basics"><link rel="prev" href="samba-pdc.html" title="Chapter 4. Domain Control"><link rel="next" href="domain-member.html" title="Chapter 6. Domain Membership"></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 5. Backup Domain Control</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="samba-pdc.html">Prev</a> </td><th width="60%" align="center">Part II. Server Configuration Basics</th><td width="20%" align="right"> <a accesskey="n" href="domain-member.html">Next</a></td></tr></table><hr></div><div class="chapter" title="Chapter 5. Backup Domain Control"><div class="titlepage"><div><div><h2 class="title"><a name="samba-bdc"></a>Chapter 5. Backup Domain Control</h2></div><div><div class="author"><h3 class="author"><span class="firstname">John</span> <span class="othername">H.</span> <span class="surname">Terpstra</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><code class="email"><<a class="email" href="mailto:jht@samba.org">jht@samba.org</a>></code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Volker</span> <span class="surname">Lendecke</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><code class="email"><<a class="email" href="mailto:Volker.Lendecke@SerNet.DE">Volker.Lendecke@SerNet.DE</a>></code></p></div></div></div></div><div><div class="author"><h3 class="author"><span class="firstname">Guenther</span> <span class="surname">Deschner</span></h3><span class="contrib">LDAP updates</span> <div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><code class="email"><<a class="email" href="mailto:gd@samba.org">gd@samba.org</a>></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="samba-bdc.html#id336899">Features and Benefits</a></span></dt><dt><span class="sect1"><a href="samba-bdc.html#id337275">Essential Background Information</a></span></dt><dd><dl><dt><span class="sect2"><a href="samba-bdc.html#id337339">MS Windows NT4-style Domain Control</a></span></dt><dt><span class="sect2"><a href="samba-bdc.html#id337967">LDAP Configuration Notes</a></span></dt><dt><span class="sect2"><a href="samba-bdc.html#id338300">Active Directory Domain Control</a></span></dt><dt><span class="sect2"><a href="samba-bdc.html#id338354">What Qualifies a Domain Controller on the Network?</a></span></dt><dt><span class="sect2"><a href="samba-bdc.html#id338437">How Does a Workstation find its Domain Controller?</a></span></dt></dl></dd><dt><span class="sect1"><a href="samba-bdc.html#id338595">Backup Domain Controller Configuration</a></span></dt><dd><dl><dt><span class="sect2"><a href="samba-bdc.html#id339066">Example Configuration</a></span></dt></dl></dd><dt><span class="sect1"><a href="samba-bdc.html#id339500">Common Errors</a></span></dt><dd><dl><dt><span class="sect2"><a href="samba-bdc.html#id339540">Machine Accounts Keep Expiring</a></span></dt><dt><span class="sect2"><a href="samba-bdc.html#id339588">Can Samba Be a Backup Domain Controller to an NT4 PDC?</a></span></dt><dt><span class="sect2"><a href="samba-bdc.html#id339639">How Do I Replicate the smbpasswd File?</a></span></dt><dt><span class="sect2"><a href="samba-bdc.html#id339736">Can I Do This All with LDAP?</a></span></dt></dl></dd></dl></div><p> -Before you continue reading this section, please make sure that you are comfortable -with configuring a Samba domain controller as described in <a class="link" href="samba-pdc.html" title="Chapter 4. Domain Control">Domain Control</a>. -</p><div class="sect1" title="Features and Benefits"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id336899"></a>Features and Benefits</h2></div></div></div><p> -This is one of the most difficult chapters to summarize. It does not matter what we say here, for someone will -still draw conclusions and/or approach the Samba Team with expectations that are either not yet capable of -being delivered or that can be achieved far more effectively using a totally different approach. In the event -that you should have a persistent concern that is not addressed in this book, please email <a class="ulink" href="mailto:jht@samba.org" target="_top">John H. Terpstra</a> clearly setting out your requirements and/or question, and -we will do our best to provide a solution. -</p><p> -<a class="indexterm" name="id336921"></a> -<a class="indexterm" name="id336930"></a> -<a class="indexterm" name="id336936"></a> -<a class="indexterm" name="id336943"></a> -<a class="indexterm" name="id336952"></a> -Samba-3 can act as a Backup Domain Controller (BDC) to another Samba Primary Domain Controller (PDC). A -Samba-3 PDC can operate with an LDAP account backend. The LDAP backend can be either a common master LDAP -server or a slave server. The use of a slave LDAP server has the benefit that when the master is down, clients -may still be able to log onto the network. This effectively gives Samba a high degree of scalability and is -an effective solution for large organizations. If you use an LDAP slave server for a PDC, you will need to -ensure the master's continued availability if the slave finds its master down at the wrong time, -you will have stability and operational problems. -</p><p> -<a class="indexterm" name="id336971"></a> -<a class="indexterm" name="id336980"></a> -<a class="indexterm" name="id336989"></a> -<a class="indexterm" name="id336998"></a> -While it is possible to run a Samba-3 BDC with a non-LDAP backend, that backend must allow some form of -"two-way" propagation of changes from the BDC to the master. At this time only LDAP delivers the capability -to propagate identity database changes from the BDC to the PDC. The BDC can use a slave LDAP server, while it -is preferable for the PDC to use as its primary an LDAP master server. -</p><p> -<a class="indexterm" name="id337011"></a> -<a class="indexterm" name="id337020"></a> -<a class="indexterm" name="id337030"></a> -<a class="indexterm" name="id337041"></a> -<a class="indexterm" name="id337048"></a> -<a class="indexterm" name="id337054"></a> -<a class="indexterm" name="id337061"></a> -The use of a non-LDAP backend SAM database is particularly problematic because domain member -servers and workstations periodically change the Machine Trust Account password. The new -password is then stored only locally. This means that in the absence of a centrally stored -accounts database (such as that provided with an LDAP-based solution) if Samba-3 is running -as a BDC, the BDC instance of the domain member trust account password will not reach the -PDC (master) copy of the SAM. If the PDC SAM is then replicated to BDCs, this results in -overwriting the SAM that contains the updated (changed) trust account password with resulting -breakage of the domain trust. -</p><p> -<a class="indexterm" name="id337077"></a> -<a class="indexterm" name="id337086"></a> -<a class="indexterm" name="id337095"></a> -<a class="indexterm" name="id337104"></a> -Considering the number of comments and questions raised concerning how to configure a BDC, -let's consider each possible option and look at the pros and cons for each possible solution. -<a class="link" href="samba-bdc.html#pdc-bdc-table" title="Table 5.1. Domain Backend Account Distribution Options">The Domain Backend Account Distribution Options table below</a> lists -possible design configurations for a PDC/BDC infrastructure. -</p><div class="table"><a name="pdc-bdc-table"></a><p class="title"><b>Table 5.1. Domain Backend Account Distribution Options</b></p><div class="table-contents"><table summary="Domain Backend Account Distribution Options" border="1"><colgroup><col align="center"><col align="center"><col align="left"></colgroup><thead><tr><th align="center">PDC Backend</th><th align="center">BDC Backend</th><th align="left">Notes/Discussion</th></tr></thead><tbody><tr><td align="center"><p>Master LDAP Server</p></td><td align="center"><p>Slave LDAP Server</p></td><td align="left"><p>The optimal solution that provides high integrity. The SAM will be - replicated to a common master LDAP server.</p></td></tr><tr><td align="center"><p>Single Central LDAP Server</p></td><td align="center"><p>Single Central LDAP Server</p></td><td align="left"><p> - A workable solution without failover ability. This is a usable solution, but not optimal. - </p></td></tr><tr><td align="center"><p>tdbsam</p></td><td align="center"><p>tdbsam + <code class="literal">net rpc vampire</code></p></td><td align="left"><p> - Does not work with Samba-3.0; Samba does not implement the - server-side protocols required. - </p></td></tr><tr><td align="center"><p>tdbsam</p></td><td align="center"><p>tdbsam + <code class="literal">rsync</code></p></td><td align="left"><p> - Do not use this configuration. - Does not work because the TDB files are live and data may not - have been flushed to disk. Furthermore, this will cause - domain trust breakdown. - </p></td></tr><tr><td align="center"><p>smbpasswd file</p></td><td align="center"><p>smbpasswd file</p></td><td align="left"><p> - Do not use this configuration. - Not an elegant solution due to the delays in synchronization - and also suffers - from the issue of domain trust breakdown. - </p></td></tr></tbody></table></div></div><br class="table-break"></div><div class="sect1" title="Essential Background Information"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id337275"></a>Essential Background Information</h2></div></div></div><p> -<a class="indexterm" name="id337283"></a> -<a class="indexterm" name="id337290"></a> -<a class="indexterm" name="id337297"></a> -<a class="indexterm" name="id337303"></a> -A domain controller is a machine that is able to answer logon requests from network -workstations. Microsoft LanManager and IBM LanServer were two early products that -provided this capability. The technology has become known as the LanMan Netlogon service. -</p><p> -<a class="indexterm" name="id337316"></a> -<a class="indexterm" name="id337327"></a> -When MS Windows NT3.10 was first released, it supported a new style of Domain Control -and with it a new form of the network logon service that has extended functionality. -This service became known as the NT NetLogon Service. The nature of this service has -changed with the evolution of MS Windows NT and today provides a complex array of -services that are implemented over an intricate spectrum of technologies. -</p><div class="sect2" title="MS Windows NT4-style Domain Control"><div class="titlepage"><div><div><h3 class="title"><a name="id337339"></a>MS Windows NT4-style Domain Control</h3></div></div></div><p> -<a class="indexterm" name="id337347"></a> -<a class="indexterm" name="id337353"></a> -<a class="indexterm" name="id337360"></a> -<a class="indexterm" name="id337367"></a> -<a class="indexterm" name="id337374"></a> -<a class="indexterm" name="id337380"></a> -<a class="indexterm" name="id337389"></a> -Whenever a user logs into a Windows NT4/200x/XP Professional workstation, -the workstation connects to a domain controller (authentication server) to validate that -the username and password the user entered are valid. If the information entered -does not match account information that has been stored in the domain -control database (the SAM, or Security Account Manager database), a set of error -codes is returned to the workstation that has made the authentication request. -</p><p> -<a class="indexterm" name="id337406"></a> -<a class="indexterm" name="id337412"></a> -<a class="indexterm" name="id337419"></a> -<a class="indexterm" name="id337426"></a> -<a class="indexterm" name="id337433"></a> -When the username/password pair has been validated, the domain controller -(authentication server) will respond with full enumeration of the account information -that has been stored regarding that user in the user and machine accounts database -for that domain. This information contains a complete network access profile for -the user but excludes any information that is particular to the user's desktop profile, -or for that matter it excludes all desktop profiles for groups that the user may -belong to. It does include password time limits, password uniqueness controls, -network access time limits, account validity information, machine names from which the -user may access the network, and much more. All this information was stored in the SAM -in all versions of MS Windows NT (3.10, 3.50, 3.51, 4.0). -</p><p> -<a class="indexterm" name="id337457"></a> -<a class="indexterm" name="id337466"></a> -<a class="indexterm" name="id337472"></a> -<a class="indexterm" name="id337479"></a> -<a class="indexterm" name="id337486"></a> -The account information (user and machine) on domain controllers is stored in two files, -one containing the security information and the other the SAM. These are stored in files -by the same name in the <code class="filename">%SystemRoot%\System32\config</code> directory. -This normally translates to the path <code class="filename">C:\WinNT\System32\config</code>. These -are the files that are involved in replication of the SAM database where BDCs are present -on the network. -</p><p> -There are two situations in which it is desirable to install BDCs: -</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p> - <a class="indexterm" name="id337518"></a> - <a class="indexterm" name="id337524"></a> - On the local network that the PDC is on, if there are many - workstations and/or where the PDC is generally very busy. In this case the BDCs - will pick up network logon requests and help to add robustness to network services. - </p></li><li class="listitem"><p> - <a class="indexterm" name="id337537"></a> - At each remote site, to reduce wide-area network traffic and to add stability to - remote network operations. The design of the network, and the strategic placement of - BDCs, together with an implementation that localizes as much of network to client - interchange as possible, will help to minimize wide-area network bandwidth needs - (and thus costs). - </p></li></ul></div><p> -<a class="indexterm" name="id337554"></a> -<a class="indexterm" name="id337560"></a> -<a class="indexterm" name="id337567"></a> -<a class="indexterm" name="id337574"></a> -<a class="indexterm" name="id337580"></a> -The interoperation of a PDC and its BDCs in a true Windows NT4 environment is worth -mentioning here. The PDC contains the master copy of the SAM. In the event that an -administrator makes a change to the user account database while physically present -on the local network that has the PDC, the change will likely be made directly to -the PDC instance of the master copy of the SAM. In the event that this update may -be performed in a branch office, the change will likely be stored in a delta file -on the local BDC. The BDC will then send a trigger to the PDC to commence the process -of SAM synchronization. The PDC will then request the delta from the BDC and apply -it to the master SAM. The PDC will then contact all the BDCs in the domain and -trigger them to obtain the update and then apply that to their own copy of the SAM. -</p><p> -<a class="indexterm" name="id337597"></a> -<a class="indexterm" name="id337606"></a> -<a class="indexterm" name="id337615"></a> -<a class="indexterm" name="id337622"></a> -Samba-3 cannot participate in true SAM replication and is therefore not able to -employ precisely the same protocols used by MS Windows NT4. A Samba-3 BDC will -not create SAM update delta files. It will not interoperate with a PDC (NT4 or Samba) -to synchronize the SAM from delta files that are held by BDCs. -</p><p> -<a class="indexterm" name="id337634"></a> -<a class="indexterm" name="id337641"></a> -Samba-3 cannot function as a BDC to an MS Windows NT4 PDC, and Samba-3 cannot -function correctly as a PDC to an MS Windows NT4 BDC. Both Samba-3 and MS Windows -NT4 can function as a BDC to its own type of PDC. -</p><p> -<a class="indexterm" name="id337652"></a> -<a class="indexterm" name="id337659"></a> -<a class="indexterm" name="id337665"></a> -The BDC is said to hold a <span class="emphasis"><em>read-only</em></span> of the SAM from which -it is able to process network logon requests and authenticate users. The BDC can -continue to provide this service, particularly while, for example, the wide-area -network link to the PDC is down. A BDC plays a very important role in both the -maintenance of domain security as well as in network integrity. -</p><p> -<a class="indexterm" name="id337682"></a> -<a class="indexterm" name="id337689"></a> -<a class="indexterm" name="id337695"></a> -<a class="indexterm" name="id337702"></a> -In the event that the NT4 PDC should need to be taken out of service, or if it dies, one of the NT4 BDCs can -be promoted to a PDC. If this happens while the original NT4 PDC is online, it is automatically demoted to an -NT4 BDC. This is an important aspect of domain controller management. The tool that is used to effect a -promotion or a demotion is the Server Manager for Domains. It should be noted that Samba-3 BDCs cannot be -promoted in this manner because reconfiguration of Samba requires changes to the <code class="filename">smb.conf</code> file. It is easy -enough to manuall change the <code class="filename">smb.conf</code> file and then restart relevant Samba network services. -</p><div class="sect3" title="Example PDC Configuration"><div class="titlepage"><div><div><h4 class="title"><a name="id337727"></a>Example PDC Configuration</h4></div></div></div><p> -<a class="indexterm" name="id337735"></a> -<a class="indexterm" name="id337742"></a> -Beginning with Version 2.2, Samba officially supports domain logons for all current Windows clients, including -Windows NT4, 2003, and XP Professional. For Samba to be enabled as a PDC, some parameters in the -<em class="parameter"><code>[global]</code></em> section of the <code class="filename">smb.conf</code> have to be set. Refer to <a class="link" href="samba-bdc.html#minimalPDC" title="Example 5.1. Minimal smb.conf for a PDC in Use with a BDC LDAP Server on PDC">the Minimal smb.conf for a PDC in Use with a BDC LDAP Server on PDC -section</a> for an example of the minimum required settings. -</p><div class="example"><a name="minimalPDC"></a><p class="title"><b>Example 5.1. Minimal smb.conf for a PDC in Use with a BDC LDAP Server on PDC</b></p><div class="example-contents"><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="indexterm" name="id337792"></a><em class="parameter"><code>workgroup = MIDEARTH</code></em></td></tr><tr><td><a class="indexterm" name="id337803"></a><em class="parameter"><code>passdb backend = ldapsam://localhost:389</code></em></td></tr><tr><td><a class="indexterm" name="id337815"></a><em class="parameter"><code>domain master = yes</code></em></td></tr><tr><td><a class="indexterm" name="id337826"></a><em class="parameter"><code>domain logons = yes</code></em></td></tr><tr><td><a class="indexterm" name="id337838"></a><em class="parameter"><code>ldap suffix = dc=quenya,dc=org</code></em></td></tr><tr><td><a class="indexterm" name="id337849"></a><em class="parameter"><code>ldap user suffix = ou=Users</code></em></td></tr><tr><td><a class="indexterm" name="id337861"></a><em class="parameter"><code>ldap group suffix = ou=Groups</code></em></td></tr><tr><td><a class="indexterm" name="id337873"></a><em class="parameter"><code>ldap machine suffix = ou=Computers</code></em></td></tr><tr><td><a class="indexterm" name="id337884"></a><em class="parameter"><code>ldap idmap suffix = ou=Idmap</code></em></td></tr><tr><td><a class="indexterm" name="id337896"></a><em class="parameter"><code>ldap admin dn = cn=sambadmin,dc=quenya,dc=org</code></em></td></tr></table></div></div><br class="example-break"><p> -<a class="indexterm" name="id337911"></a> -<a class="indexterm" name="id337918"></a> -Several other things like a <em class="parameter"><code>[homes]</code></em> and a <em class="parameter"><code>[netlogon]</code></em> share -also need to be set along with settings for the profile path, the user's home drive, and so on. This is not -covered in this chapter; for more information please refer to <a class="link" href="samba-pdc.html" title="Chapter 4. Domain Control">Domain Control</a>. -Refer to <a class="link" href="samba-pdc.html" title="Chapter 4. Domain Control">the Domain Control chapter</a> for specific recommendations for PDC -configuration. Alternately, fully documented working example network configurations using OpenLDAP and Samba -as available in the <a class="ulink" href="http://www.samba.org/samba/docs/Samba3-ByExample" target="_top">book</a> <span class="quote">“<span class="quote">Samba-3 -by Example</span>”</span> that may be obtained from local and on-line book stores. -</p></div></div><div class="sect2" title="LDAP Configuration Notes"><div class="titlepage"><div><div><h3 class="title"><a name="id337967"></a>LDAP Configuration Notes</h3></div></div></div><p> -<a class="indexterm" name="id337974"></a> -<a class="indexterm" name="id337984"></a> -<a class="indexterm" name="id337993"></a> -When configuring a master and a slave LDAP server, it is advisable to use the master LDAP server -for the PDC and slave LDAP servers for the BDCs. It is not essential to use slave LDAP servers; however, -many administrators will want to do so in order to provide redundant services. Of course, one or more BDCs -may use any slave LDAP server. Then again, it is entirely possible to use a single LDAP server for the -entire network. -</p><p> -<a class="indexterm" name="id338006"></a> -<a class="indexterm" name="id338016"></a> -<a class="indexterm" name="id338025"></a> -<a class="indexterm" name="id338031"></a> -<a class="indexterm" name="id338038"></a> -When configuring a master LDAP server that will have slave LDAP servers, do not forget to configure this in -the <code class="filename">/etc/openldap/slapd.conf</code> file. It must be noted that the DN of a server certificate -must use the CN attribute to name the server, and the CN must carry the servers' fully qualified domain name. -Additional alias names and wildcards may be present in the subjectAltName certificate extension. More details -on server certificate names are in RFC2830. -</p><p> -<a class="indexterm" name="id338058"></a> -<a class="indexterm" name="id338065"></a> -<a class="indexterm" name="id338071"></a> -<a class="indexterm" name="id338078"></a> -<a class="indexterm" name="id338088"></a> -<a class="indexterm" name="id338094"></a> -<a class="indexterm" name="id338101"></a> -It does not really fit within the scope of this document, but a working LDAP installation is basic to -LDAP-enabled Samba operation. When using an OpenLDAP server with Transport Layer Security (TLS), the machine -name in <code class="filename">/etc/ssl/certs/slapd.pem</code> must be the same as in -<code class="filename">/etc/openldap/sldap.conf</code>. The Red Hat Linux startup script creates the -<code class="filename">slapd.pem</code> file with hostname <span class="quote">“<span class="quote">localhost.localdomain.</span>”</span> It is impossible to -access this LDAP server from a slave LDAP server (i.e., a Samba BDC) unless the certificate is re-created with -a correct hostname. -</p><p> -<a class="indexterm" name="id338137"></a> -<a class="indexterm" name="id338143"></a> -<a class="indexterm" name="id338150"></a> -<a class="indexterm" name="id338157"></a> -<a class="indexterm" name="id338164"></a> -<a class="indexterm" name="id338171"></a> -Do not install a Samba PDC so that is uses an LDAP slave server. Joining client machines to the domain -will fail in this configuration because the change to the machine account in the LDAP tree must take place on -the master LDAP server. This is not replicated rapidly enough to the slave server that the PDC queries. It -therefore gives an error message on the client machine about not being able to set up account credentials. The -machine account is created on the LDAP server, but the password fields will be empty. Unfortunately, some -sites are unable to avoid such configurations, and these sites should review the <a class="link" href="smb.conf.5.html#LDAPREPLICATIONSLEEP" target="_top">ldap replication sleep</a> parameter, intended to slow down Samba sufficiently for the replication to catch up. -This is a kludge, and one that the administrator must manually duplicate in any scripts (such as the -<a class="link" href="smb.conf.5.html#ADDMACHINESCRIPT" target="_top">add machine script</a>) that they use. -</p><p> -Possible PDC/BDC plus LDAP configurations include: -</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p> - PDC+BDC -> One Central LDAP Server. - </p></li><li class="listitem"><p> - PDC -> LDAP master server, BDC -> LDAP slave server. - </p></li><li class="listitem"><p> - PDC -> LDAP master, with secondary slave LDAP server. - </p><p> - BDC -> LDAP master, with secondary slave LDAP server. - </p></li><li class="listitem"><p> - PDC -> LDAP master, with secondary slave LDAP server. - </p><p> - BDC -> LDAP slave server, with secondary master LDAP server. - </p></li></ul></div><p> -In order to have a fallback configuration (secondary) LDAP server, you would specify -the secondary LDAP server in the <code class="filename">smb.conf</code> file as shown in <a class="link" href="samba-bdc.html#mulitldapcfg" title="Example 5.2. Multiple LDAP Servers in smb.conf">the Multiple LDAP -Servers in <code class="filename">smb.conf</code> example</a>. -</p><div class="example"><a name="mulitldapcfg"></a><p class="title"><b>Example 5.2. Multiple LDAP Servers in <code class="filename">smb.conf</code></b></p><div class="example-contents"><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="indexterm" name="id338287"></a><em class="parameter"><code>passdb backend = ldapsam:"ldap://master.quenya.org ldap://slave.quenya.org"</code></em></td></tr></table></div></div><br class="example-break"></div><div class="sect2" title="Active Directory Domain Control"><div class="titlepage"><div><div><h3 class="title"><a name="id338300"></a>Active Directory Domain Control</h3></div></div></div><p> -<a class="indexterm" name="id338308"></a> -<a class="indexterm" name="id338315"></a> -<a class="indexterm" name="id338321"></a> -<a class="indexterm" name="id338328"></a> -<a class="indexterm" name="id338335"></a> -<a class="indexterm" name="id338342"></a> -As of the release of MS Windows 2000 and Active Directory, this information is now stored -in a directory that can be replicated and for which partial or full administrative control -can be delegated. Samba-3 is not able to be a domain controller within an Active Directory -tree, and it cannot be an Active Directory server. This means that Samba-3 also cannot -act as a BDC to an Active Directory domain controller. -</p></div><div class="sect2" title="What Qualifies a Domain Controller on the Network?"><div class="titlepage"><div><div><h3 class="title"><a name="id338354"></a>What Qualifies a Domain Controller on the Network?</h3></div></div></div><p> -<a class="indexterm" name="id338362"></a> -<a class="indexterm" name="id338369"></a> -<a class="indexterm" name="id338375"></a> -<a class="indexterm" name="id338382"></a> -Every machine that is a domain controller for the domain MIDEARTH has to register the NetBIOS -group name MIDEARTH<1C> with the WINS server and/or by broadcast on the local network. -The PDC also registers the unique NetBIOS name MIDEARTH<1B> with the WINS server. -The name type <1B> name is normally reserved for the Domain Master Browser (DMB), a role -that has nothing to do with anything related to authentication, but the Microsoft domain -implementation requires the DMB to be on the same machine as the PDC. -</p><p> -<a class="indexterm" name="id338398"></a> -<a class="indexterm" name="id338405"></a> -<a class="indexterm" name="id338412"></a> -Where a WINS server is not used, broadcast name registrations alone must suffice. Refer to -<a class="link" href="NetworkBrowsing.html" title="Chapter 10. Network Browsing">Network Browsing</a>,<a class="link" href="NetworkBrowsing.html#netdiscuss" title="Discussion">Discussion</a> -for more information regarding TCP/IP network protocols and how SMB/CIFS names are handled. -</p></div><div class="sect2" title="How Does a Workstation find its Domain Controller?"><div class="titlepage"><div><div><h3 class="title"><a name="id338437"></a>How Does a Workstation find its Domain Controller?</h3></div></div></div><p> -<a class="indexterm" name="id338445"></a> -<a class="indexterm" name="id338452"></a> -There are two different mechanisms to locate a domain controller: one method is used when -NetBIOS over TCP/IP is enabled and the other when it has been disabled in the TCP/IP -network configuration. -</p><p> -<a class="indexterm" name="id338463"></a> -<a class="indexterm" name="id338470"></a> -Where NetBIOS over TCP/IP is disabled, all name resolution involves the use of DNS, broadcast -messaging over UDP, as well as Active Directory communication technologies. In this type of -environment all machines require appropriate DNS entries. More information may be found in -<a class="link" href="NetworkBrowsing.html#adsdnstech" title="DNS and Active Directory">DNS and Active Directory</a>. -</p><div class="sect3" title="NetBIOS Over TCP/IP Enabled"><div class="titlepage"><div><div><h4 class="title"><a name="id338488"></a>NetBIOS Over TCP/IP Enabled</h4></div></div></div><p> -<a class="indexterm" name="id338496"></a> -<a class="indexterm" name="id338503"></a> -<a class="indexterm" name="id338509"></a> -<a class="indexterm" name="id338516"></a> -An MS Windows NT4/200x/XP Professional workstation in the domain MIDEARTH that wants a -local user to be authenticated has to find the domain controller for MIDEARTH. It does this -by doing a NetBIOS name query for the group name MIDEARTH<1C>. It assumes that each -of the machines it gets back from the queries is a domain controller and can answer logon -requests. To not open security holes, both the workstation and the selected domain controller -authenticate each other. After that the workstation sends the user's credentials (name and -password) to the local domain controller for validation. -</p></div><div class="sect3" title="NetBIOS Over TCP/IP Disabled"><div class="titlepage"><div><div><h4 class="title"><a name="id338539"></a>NetBIOS Over TCP/IP Disabled</h4></div></div></div><p> -<a class="indexterm" name="id338547"></a> -<a class="indexterm" name="id338554"></a> -<a class="indexterm" name="id338561"></a> -<a class="indexterm" name="id338567"></a> -An MS Windows NT4/200x/XP Professional workstation in the realm <code class="constant">quenya.org</code> -that has a need to affect user logon authentication will locate the domain controller by -re-querying DNS servers for the <code class="constant">_ldap._tcp.pdc._msdcs.quenya.org</code> record. -More information regarding this subject may be found in <a class="link" href="NetworkBrowsing.html#adsdnstech" title="DNS and Active Directory">DNS and Active Directory</a>. -</p></div></div></div><div class="sect1" title="Backup Domain Controller Configuration"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id338595"></a>Backup Domain Controller Configuration</h2></div></div></div><p> -<a class="indexterm" name="id338603"></a> -The creation of a BDC requires some steps to prepare the Samba server before -<span class="application">smbd</span> is executed for the first time. These steps are as follows: -</p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p> - <a class="indexterm" name="id338623"></a> - <a class="indexterm" name="id338629"></a> - <a class="indexterm" name="id338636"></a> - <a class="indexterm" name="id338642"></a> - <a class="indexterm" name="id338649"></a> - <a class="indexterm" name="id338656"></a> - The domain SID has to be the same on the PDC and the BDC. In Samba versions pre-2.2.5, the domain SID was - stored in the file <code class="filename">private/MACHINE.SID</code>. For all versions of Samba released since 2.2.5 - the domain SID is stored in the file <code class="filename">private/secrets.tdb</code>. This file is unique to each - server and cannot be copied from a PDC to a BDC; the BDC will generate a new SID at startup. It will overwrite - the PDC domain SID with the newly created BDC SID. There is a procedure that will allow the BDC to acquire the - domain SID. This is described here. - </p><p> - <a class="indexterm" name="id338682"></a> - <a class="indexterm" name="id338689"></a> - <a class="indexterm" name="id338695"></a> - <a class="indexterm" name="id338702"></a> - <a class="indexterm" name="id338709"></a> - To retrieve the domain SID from the PDC or an existing BDC and store it in the - <code class="filename">secrets.tdb</code>, execute: - </p><pre class="screen"> -<code class="prompt">root# </code><strong class="userinput"><code>net rpc getsid</code></strong> -</pre></li><li class="listitem"><p> - <a class="indexterm" name="id338748"></a> - <a class="indexterm" name="id338755"></a> - <a class="indexterm" name="id338761"></a> - Specification of the <a class="link" href="smb.conf.5.html#LDAPADMINDN" target="_top">ldap admin dn</a> is obligatory. - This also requires the LDAP administration password to be set in the <code class="filename">secrets.tdb</code> - using the <code class="literal">smbpasswd -w <em class="replaceable"><code>mysecret</code></em></code>. - </p></li><li class="listitem"><p> - The <a class="link" href="smb.conf.5.html#LDAPSUFFIX" target="_top">ldap suffix</a> parameter and the <a class="link" href="smb.conf.5.html#LDAPIDMAPSUFFIX" target="_top">ldap idmap suffix</a> - parameter must be specified in the <code class="filename">smb.conf</code> file. - </p></li><li class="listitem"><p> - <a class="indexterm" name="id338833"></a> - <a class="indexterm" name="id338842"></a> - <a class="indexterm" name="id338849"></a> - <a class="indexterm" name="id338856"></a> - The UNIX user database has to be synchronized from the PDC to the - BDC. This means that both the <code class="filename">/etc/passwd</code> and - <code class="filename">/etc/group</code> have to be replicated from the PDC - to the BDC. This can be done manually whenever changes are made. - Alternately, the PDC is set up as an NIS master server and the BDC as an NIS slave - server. To set up the BDC as a mere NIS client would not be enough, - as the BDC would not be able to access its user database in case of - a PDC failure. NIS is by no means the only method to synchronize - passwords. An LDAP solution would also work. - </p></li><li class="listitem"><p> - <a class="indexterm" name="id338884"></a> - <a class="indexterm" name="id338891"></a> - <a class="indexterm" name="id338897"></a> - <a class="indexterm" name="id338904"></a> - <a class="indexterm" name="id338910"></a> - <a class="indexterm" name="id338917"></a> - <a class="indexterm" name="id338924"></a> - <a class="indexterm" name="id338931"></a> - The Samba password database must be replicated from the PDC to the BDC. - Although it is possible to synchronize the <code class="filename">smbpasswd</code> - file with <code class="literal">rsync</code> and <code class="literal">ssh</code>, this method - is broken and flawed, and is therefore not recommended. A better solution - is to set up slave LDAP servers for each BDC and a master LDAP server for the PDC. - The use of rsync is inherently flawed by the fact that the data will be replicated - at timed intervals. There is no guarantee that the BDC will be operating at all - times with correct and current machine and user account information. This means that - this method runs the risk of users being inconvenienced by discontinuity of access - to network services due to inconsistent security data. It must be born in mind that - Windows workstations update (change) the machine trust account password at regular - intervals administrators are not normally aware that this is happening - or when it takes place. - </p><p> - <a class="indexterm" name="id338968"></a> - <a class="indexterm" name="id338975"></a> - <a class="indexterm" name="id338982"></a> - <a class="indexterm" name="id338989"></a> - The use of LDAP for both the POSIX (UNIX user and group) accounts and for the - SambaSAMAccount data automatically ensures that all account change information - will be written to the shared directory. This eliminates the need for any special - action to synchronize account information because LDAP will meet that requirement. - </p></li><li class="listitem"><p> - <a class="indexterm" name="id339003"></a> - <a class="indexterm" name="id339010"></a> - <a class="indexterm" name="id339016"></a> - <a class="indexterm" name="id339023"></a> - <a class="indexterm" name="id339029"></a> - <a class="indexterm" name="id339036"></a> - The netlogon share has to be replicated from the PDC to the BDC. This can be done manually whenever login - scripts are changed, or it can be done automatically using a <code class="literal">cron</code> job that will replicate - the directory structure in this share using a tool like <code class="literal">rsync</code>. The use of - <code class="literal">rsync</code> for replication of the netlogon data is not critical to network security and is one - that can be manually managed given that the administrator will make all changes to the netlogon share as part - of a conscious move. - </p></li></ul></div><div class="sect2" title="Example Configuration"><div class="titlepage"><div><div><h3 class="title"><a name="id339066"></a>Example Configuration</h3></div></div></div><p> -Finally, the BDC has to be capable of being found by the workstations. This can be done by configuring the -Samba <code class="filename">smb.conf</code> file <em class="parameter"><code>[global]</code></em> section as shown in <a class="link" href="samba-bdc.html#minim-bdc" title="Example 5.3. Minimal Setup for Being a BDC">Minimal -Setup for Being a BDC</a>. -</p><div class="example"><a name="minim-bdc"></a><p class="title"><b>Example 5.3. Minimal Setup for Being a BDC</b></p><div class="example-contents"><table border="0" summary="Simple list" class="simplelist"><tr><td><a class="indexterm" name="id339110"></a><em class="parameter"><code>workgroup = MIDEARTH</code></em></td></tr><tr><td><a class="indexterm" name="id339121"></a><em class="parameter"><code>passdb backend = ldapsam:ldap://slave-ldap.quenya.org</code></em></td></tr><tr><td><a class="indexterm" name="id339133"></a><em class="parameter"><code>domain master = no</code></em></td></tr><tr><td><a class="indexterm" name="id339144"></a><em class="parameter"><code>domain logons = yes</code></em></td></tr><tr><td><a class="indexterm" name="id339156"></a><em class="parameter"><code>ldap suffix = dc=abmas,dc=biz</code></em></td></tr><tr><td><a class="indexterm" name="id339167"></a><em class="parameter"><code>ldap user suffix = ou=Users</code></em></td></tr><tr><td><a class="indexterm" name="id339179"></a><em class="parameter"><code>ldap group suffix = ou=Groups</code></em></td></tr><tr><td><a class="indexterm" name="id339191"></a><em class="parameter"><code>ldap machine suffix = ou=Computers</code></em></td></tr><tr><td><a class="indexterm" name="id339202"></a><em class="parameter"><code>ldap idmap suffix = ou=Idmap</code></em></td></tr><tr><td><a class="indexterm" name="id339214"></a><em class="parameter"><code>ldap admin dn = cn=sambadmin,dc=quenya,dc=org</code></em></td></tr><tr><td><a class="indexterm" name="id339226"></a><em class="parameter"><code>idmap backend = ldap:ldap://master-ldap.quenya.org</code></em></td></tr><tr><td><a class="indexterm" name="id339237"></a><em class="parameter"><code>idmap uid = 10000-20000</code></em></td></tr><tr><td><a class="indexterm" name="id339249"></a><em class="parameter"><code>idmap gid = 10000-20000</code></em></td></tr></table></div></div><br class="example-break"><p> -Fully documented working example network configurations using OpenLDAP and Samba -as available in the <a class="ulink" href="http://www.samba.org/samba/docs/Samba3-ByExample" target="_top">book</a> <span class="quote">“<span class="quote">Samba-3 -by Example</span>”</span> that may be obtained from local and on-line book stores. -</p><p> -<a class="indexterm" name="id339278"></a> -<a class="indexterm" name="id339284"></a> -<a class="indexterm" name="id339291"></a> -<a class="indexterm" name="id339298"></a> -This configuration causes the BDC to register only the name MIDEARTH<1C> with the WINS server. This is -not a problem, as the name MIDEARTH<1C> is a NetBIOS group name that is meant to be registered by more -than one machine. The parameter <a class="link" href="smb.conf.5.html#DOMAINMASTER" target="_top">domain master = no</a> forces the BDC not to -register MIDEARTH<1B>, which is a unique NetBIOS name that is reserved for the PDC. -</p><p> -<a class="indexterm" name="id339324"></a> -<a class="indexterm" name="id339330"></a> -<a class="indexterm" name="id339337"></a> -<a class="indexterm" name="id339344"></a> -<a class="indexterm" name="id339351"></a> -<a class="indexterm" name="id339358"></a> -<a class="indexterm" name="id339365"></a> -<a class="indexterm" name="id339372"></a> -<a class="indexterm" name="id339378"></a> -The <em class="parameter"><code>idmap backend</code></em> will redirect the <code class="literal">winbindd</code> utility to use the LDAP -database to store all mappings for Windows SIDs to UIDs and GIDs for UNIX accounts in a repository that is -shared. The BDC will however depend on local resolution of UIDs and GIDs via NSS and the -<code class="literal">nss_ldap</code> utility. -</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p> -<a class="indexterm" name="id339409"></a> -<a class="indexterm" name="id339418"></a> -<a class="indexterm" name="id339425"></a> -<a class="indexterm" name="id339432"></a> -Samba-3 has introduced a new ID mapping facility. One of the features of this facility is that it -allows greater flexibility in how user and group IDs are handled in respect to NT domain user and group -SIDs. One of the new facilities provides for explicitly ensuring that UNIX/Linux UID and GID values -will be consistent on the PDC, all BDCs, and all domain member servers. The parameter that controls this -is called <em class="parameter"><code>idmap backend</code></em>. Please refer to the man page for <code class="filename">smb.conf</code> for more information -regarding its behavior. -</p></div><p> -<a class="indexterm" name="id339461"></a> -<a class="indexterm" name="id339468"></a> -<a class="indexterm" name="id339475"></a> -The use of the <a class="link" href="smb.conf.5.html#IDMAPBACKEND" target="_top">idmap backend = ldap:ldap://master.quenya.org</a> -option on a BDC only makes sense where ldapsam is used on a PDC. The purpose of an LDAP-based idmap backend is -also to allow a domain member (without its own passdb backend) to use winbindd to resolve Windows network users -and groups to common UID/GIDs. In other words, this option is generally intended for use on BDCs and on domain -member servers. -</p></div></div><div class="sect1" title="Common Errors"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id339500"></a>Common Errors</h2></div></div></div><p> -<a class="indexterm" name="id339508"></a> -Domain control was a new area for Samba, but there are now many examples that we may refer to. -Updated information will be published as they become available and may be found in later Samba releases or -from the Samba Web <a class="ulink" href="http://samba.org" target="_top">site</a>; refer in particular to the -<code class="filename">WHATSNEW.txt</code> in the Samba release tarball. The book, <span class="quote">“<span class="quote">Samba-3 by Example</span>”</span> -documents well tested and proven configuration examples. You can obtain a copy of this -<a class="ulink" href="http://www.samba.org/samba/docs/Samba3-ByExample.pdf" target="_top">book</a> for the Samba web site. -</p><div class="sect2" title="Machine Accounts Keep Expiring"><div class="titlepage"><div><div><h3 class="title"><a name="id339540"></a>Machine Accounts Keep Expiring</h3></div></div></div><p> -<a class="indexterm" name="id339548"></a> -<a class="indexterm" name="id339555"></a> -<a class="indexterm" name="id339562"></a> -<a class="indexterm" name="id339568"></a> -This problem will occur when the passdb (SAM) files are copied from a central -server but the local BDC is acting as a PDC. This results in the application of -Local Machine Trust Account password updates to the local SAM. Such updates -are not copied back to the central server. The newer machine account password is then -overwritten when the SAM is recopied from the PDC. The result is that the domain member machine -on startup will find that its passwords do not match the one now in the database, and -since the startup security check will now fail, this machine will not allow logon attempts -to proceed and the account expiry error will be reported. -</p><p> -The solution is to use a more robust passdb backend, such as the ldapsam backend, setting up -a slave LDAP server for each BDC and a master LDAP server for the PDC. -</p></div><div class="sect2" title="Can Samba Be a Backup Domain Controller to an NT4 PDC?"><div class="titlepage"><div><div><h3 class="title"><a name="id339588"></a>Can Samba Be a Backup Domain Controller to an NT4 PDC?</h3></div></div></div><p> -<a class="indexterm" name="id339596"></a> -<a class="indexterm" name="id339605"></a> -No. The native NT4 SAM replication protocols have not yet been fully implemented. -</p><p> -<a class="indexterm" name="id339614"></a> -<a class="indexterm" name="id339621"></a> -<a class="indexterm" name="id339627"></a> -Can I get the benefits of a BDC with Samba? Yes, but only to a Samba PDC.The -main reason for implementing a BDC is availability. If the PDC is a Samba -machine, a second Samba machine can be set up to service logon requests whenever -the PDC is down. -</p></div><div class="sect2" title="How Do I Replicate the smbpasswd File?"><div class="titlepage"><div><div><h3 class="title"><a name="id339639"></a>How Do I Replicate the smbpasswd File?</h3></div></div></div><p> -<a class="indexterm" name="id339646"></a> -<a class="indexterm" name="id339655"></a> -<a class="indexterm" name="id339662"></a> -Replication of the smbpasswd file is sensitive. It has to be done whenever changes -to the SAM are made. Every user's password change is done in the smbpasswd file and -has to be replicated to the BDC. So replicating the smbpasswd file very often is necessary. -</p><p> -<a class="indexterm" name="id339674"></a> -<a class="indexterm" name="id339681"></a> -<a class="indexterm" name="id339688"></a> -As the smbpasswd file contains plaintext password equivalents, it must not be -sent unencrypted over the wire. The best way to set up smbpasswd replication from -the PDC to the BDC is to use the utility rsync. rsync can use ssh as a transport. -<code class="literal">ssh</code> itself can be set up to accept <span class="emphasis"><em>only</em></span> -<code class="literal">rsync</code> transfer without requiring the user to type a password. -</p><p> -<a class="indexterm" name="id339715"></a> -<a class="indexterm" name="id339722"></a> -As said a few times before, use of this method is broken and flawed. Machine trust -accounts will go out of sync, resulting in a broken domain. This method is -<span class="emphasis"><em>not</em></span> recommended. Try using LDAP instead. -</p></div><div class="sect2" title="Can I Do This All with LDAP?"><div class="titlepage"><div><div><h3 class="title"><a name="id339736"></a>Can I Do This All with LDAP?</h3></div></div></div><p> -<a class="indexterm" name="id339744"></a> -<a class="indexterm" name="id339751"></a> -The simple answer is yes. Samba's pdb_ldap code supports binding to a replica -LDAP server and will also follow referrals and rebind to the master if it ever -needs to make a modification to the database. (Normally BDCs are read-only, so -this will not occur often). -</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-pdc.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="domain-member.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 4. 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 6. Domain Membership</td></tr></table></div></body></html> |