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diff --git a/docs/howto/DOMAIN_MEMBER.xml b/docs/howto/DOMAIN_MEMBER.xml new file mode 100644 index 0000000000..72b00663f7 --- /dev/null +++ b/docs/howto/DOMAIN_MEMBER.xml @@ -0,0 +1,1105 @@ +<chapter id="domain-member"> + +<chapterinfo> + &author.jht; + &author.jeremy; + &author.jerry; + &author.tridge; + &author.jelmer; + <author>&person.gd;<contrib>LDAP updates</contrib></author> +</chapterinfo> + +<title>Domain Membership</title> + +<para> +Domain Membership is a subject of vital concern. Samba must be able to +participate as a member server in a Microsoft Domain Security context, and +Samba must be capable of providing Domain machine member trust accounts, +otherwise it would not be able to offer a viable option for many users. +</para> + +<para> +This chapter covers background information pertaining to Domain Membership, +the Samba configuration for it, and MS Windows client procedures for joining a +domain. Why is this necessary? Because both are areas in which there exists +within the current MS Windows networking world and particularly in the +UNIX/Linux networking and administration world, a considerable level of +misinformation, incorrect understanding and a lack of knowledge. Hopefully +this chapter will fill the voids. +</para> + +<sect1> +<title>Features and Benefits</title> + +<para> +MS Windows workstations and servers that want to participate in Domain Security need to +be made Domain Members. Participating in Domain Security is often called +<emphasis>Single Sign On</emphasis> or <acronym>SSO</acronym> for short. This +chapter describes the process that must be followed to make a workstation +(or another server &smbmdash; be it an <application>MS Windows NT4 / 200x</application> +server) or a Samba server a member of an MS Windows Domain Security context. +</para> + +<para> +<indexterm><primary>Server Type</primary><secondary>Domain Member</secondary></indexterm> +Samba-3 can join an MS Windows NT4-style domain as a native member server, an +MS Windows Active Directory Domain as a native member server, or a Samba Domain +Control network. Domain Membership has many advantages: +</para> + +<itemizedlist> + <listitem><para> +<indexterm><primary>SAM</primary></indexterm> + MS Windows workstation users get the benefit of SSO. + </para></listitem> + + <listitem><para> + Domain user access rights and file ownership/access controls can be set + from the single Domain Security Account Manager (SAM) database + (works with Domain Member servers as well as with MS Windows workstations + that are Domain Members). + </para></listitem> + + <listitem><para> + Only <application>MS Windows NT4/200x/XP Professional</application> + workstations that are Domain Members can use network logon facilities. + </para></listitem> + + <listitem><para> + Domain Member workstations can be better controlled through the use of + Policy files (<filename>NTConfig.POL</filename>) and Desktop Profiles. + </para></listitem> + + <listitem><para> + Through the use of logon scripts, users can be given transparent access to network + applications that run off application servers. + </para></listitem> + + <listitem><para> + Network administrators gain better application and user access management + abilities because there is no need to maintain user accounts on any network + client or server, other than the central Domain database + (either NT4/Samba SAM style Domain, NT4 Domain that is backend-ed with an + LDAP directory, or via an Active Directory infrastructure). + </para></listitem> +</itemizedlist> + +</sect1> + +<sect1 id="machine-trust-accounts"> +<title>MS Windows Workstation/Server Machine Trust Accounts</title> + +<para> +<indexterm><primary>Machine Trust Accounts</primary></indexterm> +A Machine Trust Account is an account that is used to authenticate a client +machine (rather than a user) to the Domain Controller server. In Windows terminology, +this is known as a <quote>Computer Account.</quote> The purpose of the machine account +is to prevent a rogue user and Domain Controller from colluding to gain access to a +domain member workstation. +</para> + +<para> +The password of a Machine Trust Account acts as the shared secret for +secure communication with the Domain Controller. This is a security +feature to prevent an unauthorized machine with the same NetBIOS name +from joining the domain and gaining access to domain user/group +accounts. Windows NT/200x/XP Professional clients use machine trust +accounts, but Windows 9x/Me/XP Home clients do not. Hence, a +Windows 9x/Me/XP Home client is never a true member of a Domain +because it does not possess a Machine Trust Account, and, thus, has no +shared secret with the Domain Controller. +</para> + +<para> +A Windows NT4 PDC stores each Machine Trust Account in the Windows Registry. +The introduction of MS Windows 2000 saw the introduction of Active Directory, +the new repository for Machine Trust Accounts. A Samba PDC, however, stores +each Machine Trust Account in two parts, +as follows: + +<itemizedlist> + <listitem><para> + A Domain Security Account (stored in the + <smbconfoption><name>passdb backend</name></smbconfoption> that has been configured in the + &smb.conf; file. The precise nature of the account information that is + stored depends on the type of backend database that has been chosen. + </para> + + <para> + The older format of this data is the <filename>smbpasswd</filename> database + that contains the UNIX login ID, the UNIX user identifier (UID), and the + LanMan and NT encrypted passwords. There is also some other information in + this file that we do not need to concern ourselves with here. + </para> + + <para> + The two newer database types are called ldapsam, and + tdbsam. Both store considerably more data than the + older <filename>smbpasswd</filename> file did. The extra information + enables new user account controls to be implemented. + </para></listitem> + + <listitem><para> + A corresponding UNIX account, typically stored in + <filename>/etc/passwd</filename>. Work is in progress to allow a + simplified mode of operation that does not require UNIX user accounts, but + this may not be a feature of the early releases of Samba-3. + </para></listitem> +</itemizedlist> +</para> + +<para> +<indexterm><primary>Machine Trust Accounts</primary><secondary>creating</secondary></indexterm> +There are three ways to create Machine Trust Accounts: +</para> + +<itemizedlist> + <listitem><para> + Manual creation from the UNIX/Linux command line. Here, both the Samba and + corresponding UNIX account are created by hand. + </para></listitem> + + <listitem><para> + <indexterm><primary>Server Manager</primary></indexterm> + Using the MS Windows NT4 Server Manager, either from an NT4 Domain Member + server, or using the Nexus toolkit available from the Microsoft Web site. + This tool can be run from any MS Windows machine as long as the user is + logged on as the administrator account. + </para></listitem> + + <listitem><para> + <quote>On-the-fly</quote> creation. The Samba Machine Trust Account is automatically + created by Samba at the time the client is joined to the domain. + (For security, this is the recommended method.) The corresponding UNIX + account may be created automatically or manually. + </para></listitem> +</itemizedlist> + +<sect2> +<title>Manual Creation of Machine Trust Accounts</title> + +<para> +The first step in manually creating a Machine Trust Account is to manually +create the corresponding UNIX account in <filename>/etc/passwd</filename>. +This can be done using <command>vipw</command> or another <quote>add user</quote> command +that is normally used to create new UNIX accounts. The following is an example for +a Linux-based Samba server: +</para> + +<para> +<indexterm><primary>useradd</primary></indexterm> +<indexterm><primary>vipw</primary></indexterm> +<screen> +&rootprompt;<userinput>/usr/sbin/useradd -g machines -d /dev/null -c <replaceable>"machine nickname"</replaceable> \ + -s /bin/false <replaceable>machine_name</replaceable>$ </userinput> + +&rootprompt;<userinput>passwd -l <replaceable>machine_name</replaceable>$</userinput> +</screen> +</para> + +<para>In the above example above there is an existing system group <quote>machines</quote> which is used +as the primary group for all machine accounts. In the following examples the <quote>machines</quote> group has +numeric GID equal 100.</para> + +<para> +<indexterm><primary>chpass</primary></indexterm> +On *BSD systems, this can be done using the <command>chpass</command> utility: +</para> + +<para> +<screen> +&rootprompt;<userinput>chpass -a \ +'<replaceable>machine_name</replaceable>$:*:101:100::0:0:Windows <replaceable>machine_name</replaceable>:/dev/null:/sbin/nologin'</userinput> +</screen> +</para> + +<para> +The <filename>/etc/passwd</filename> entry will list the machine name +with a <quote>$</quote> appended, will not have a password, will have a null shell and no +home directory. For example, a machine named <quote>doppy</quote> would have an +<filename>/etc/passwd</filename> entry like this: +</para> + +<programlisting> +doppy$:x:505:100:<replaceable>machine_nickname</replaceable>:/dev/null:/bin/false +</programlisting> + +<para> +Above, <replaceable>machine_nickname</replaceable> can be any +descriptive name for the client, i.e., BasementComputer. +<replaceable>machine_name</replaceable> absolutely must be the NetBIOS +name of the client to be joined to the domain. The <quote>$</quote> must be +appended to the NetBIOS name of the client or Samba will not recognize +this as a Machine Trust Account. +</para> + +<para> +Now that the corresponding UNIX account has been created, the next step is to create +the Samba account for the client containing the well-known initial +Machine Trust Account password. This can be done using the +<command>smbpasswd</command> command +as shown here: +</para> + +<para> +<screen> +&rootprompt;<userinput>smbpasswd -a -m <replaceable>machine_name</replaceable></userinput> +</screen> +</para> + +<para> +where <replaceable>machine_name</replaceable> is the machine's NetBIOS +name. The RID of the new machine account is generated from the UID of +the corresponding UNIX account. +</para> + +<warning> +<title>Join the client to the domain immediately</title> + +<para> +Manually creating a Machine Trust Account using this method is the +equivalent of creating a Machine Trust Account on a Windows NT PDC using +<indexterm><primary>Server Manager</primary></indexterm> +the <application>Server Manager</application>. From the time at which the +account is created to the time the client joins the domain and +changes the password, your domain is vulnerable to an intruder joining +your domain using a machine with the same NetBIOS name. A PDC inherently +trusts members of the domain and will serve out a large degree of user +information to such clients. You have been warned! +</para> +</warning> +</sect2> + +<sect2> +<title>Managing Domain Machine Accounts using NT4 Server Manager</title> + +<para> +A working <smbconfoption><name>add machine script</name></smbconfoption> script is essential +for machine trust accounts to be automatically created. This applies no matter whether +one uses automatic account creation, or if one wishes to use the NT4 Domain Server Manager. +</para> + +<para> +<indexterm><primary>SRVTOOLS.EXE</primary></indexterm> +If the machine from which you are trying to manage the domain is an +<application>MS Windows NT4 workstation or MS Windows 200x/XP Professional</application>, +the tool of choice is the package called <command>SRVTOOLS.EXE</command>. +When executed in the target directory it will unpack <command>SrvMgr.exe</command> +and <command>UsrMgr.exe</command> (both are domain management tools for MS Windows NT4 workstation). +</para> + +<para> +<indexterm><primary>Nexus.exe</primary></indexterm> +If your workstation is a <application>Microsoft Windows 9x/Me</application> family product + you should download the <command>Nexus.exe</command> package from the Microsoft web site. +When executed from the target directory this will unpack the same tools but for use on +this platform. +</para> + +<para> +Further information about these tools may be obtained from the following locations: +</para> + +<para> +<simplelist> +<member><ulink noescape="1" url="http://support.microsoft.com/default.aspx?scid=kb;en-us;173673"/></member> +<member><ulink noescape="1" url="http://support.microsoft.com/default.aspx?scid=kb;en-us;172540"/></member> +</simplelist> +</para> + +<para> +Launch the <command>srvmgr.exe</command> (Server Manager for Domains) and follow these steps: +</para> + +<procedure> +<title>Server Manager Account Machine Account Management</title> + <step><para> + From the menu select <guimenu>Computer</guimenu>. + </para></step> + + <step><para> + Click <guimenuitem>Select Domain</guimenuitem>. + </para></step> + + <step><para> + Click the name of the domain you wish to administer in the + <guilabel>Select Domain</guilabel> panel and then click + <guibutton>OK</guibutton>. + </para></step> + + <step><para> + Again from the menu select <guimenu>Computer</guimenu>. + </para></step> + + <step><para> + Select <guimenuitem>Add to Domain</guimenuitem>. + </para></step> + + <step><para> + In the dialog box, click the radio button to + <guilabel>Add NT Workstation of Server</guilabel>, then + enter the machine name in the field provided, and click the + <guibutton>Add</guibutton> button. + </para></step> +</procedure> + +</sect2> + +<sect2> +<title>On-the-Fly Creation of Machine Trust Accounts</title> + +<para> +The second (and recommended) way of creating Machine Trust Accounts is +simply to allow the Samba server to create them as needed when the client +is joined to the domain. +</para> + +<para>Since each Samba Machine Trust Account requires a corresponding UNIX account, a method +for automatically creating the UNIX account is usually supplied; this requires configuration of the +add machine script option in &smb.conf;. This method is not required, however, corresponding UNIX +accounts may also be created manually. +</para> + + +<para> +Here is an example for a Red Hat Linux system. +</para> + +<para><smbconfblock> +<smbconfsection>[global]</smbconfsection> +<smbconfcomment><...remainder of parameters...></smbconfcomment> +<smbconfoption><name>add machine script</name><value>/usr/sbin/useradd -d /dev/null -g 100 \</value></smbconfoption> +<member><parameter> -s /bin/false -M %u</parameter></member> +</smbconfblock></para> + + +</sect2> + + +<sect2><title>Making an MS Windows Workstation or Server a Domain Member</title> + +<para> +The procedure for making an MS Windows workstation or server a member of the domain varies +with the version of Windows. +</para> + +<sect3> + <title>Windows 200x/XP Professional Client</title> + + <para> + When the user elects to make the client a Domain Member, Windows 200x prompts for + an account and password that has privileges to create machine accounts in the domain. + A Samba Administrator Account (i.e., a Samba account that has <constant>root</constant> privileges on the + Samba server) must be entered here; the operation will fail if an ordinary user + account is given. + </para> + + <para> + For security reasons, the password for this Administrator Account should be set + to a password that is other than that used for the root user in <filename>/etc/passwd</filename>. + </para> + + <para> + The name of the account that is used to create Domain Member machine accounts can be + anything the network administrator may choose. If it is other than <constant>root</constant> + then this is easily mapped to <constant>root</constant> in the file named in the &smb.conf; parameter + <smbconfoption><name>username map</name><value>/etc/samba/smbusers</value></smbconfoption>. + </para> + + <para> + The session key of the Samba Administrator Account acts as an encryption key for setting the password of the machine trust + account. The Machine Trust Account will be created on-the-fly, or updated if it already exists. + </para> +</sect3> + +<sect3> + <title>Windows NT4 Client</title> + + <para> + If the Machine Trust Account was created manually, on the + Identification Changes menu enter the domain name, but do not + check the box <guilabel>Create a Computer Account in the Domain</guilabel>. + In this case, the existing Machine Trust Account is used to join the machine + to the domain. + </para> + + <para> + If the Machine Trust Account is to be created on-the-fly, on the Identification Changes menu enter the domain + name and check the box <guilabel>Create a Computer Account in the Domain</guilabel>. In this case, joining + the domain proceeds as above for Windows 2000 (i.e., you must supply a Samba Administrator Account when + prompted). + </para> +</sect3> + +<sect3> + <title>Samba Client</title> + + <para>Joining a Samba client to a domain is documented in + <link linkend="domain-member-server">Domain Member Server</link>. + </para> +</sect3> + +</sect2> +</sect1> + +<sect1 id="domain-member-server"> +<title>Domain Member Server</title> + +<para> +This mode of server operation involves the Samba machine being made a member +of a domain security context. This means by definition that all user +authentication will be done from a centrally defined authentication regime. +The authentication regime may come from an NT3/4-style (old domain technology) +server, or it may be provided from an Active Directory server (ADS) running on +MS Windows 2000 or later. +</para> + +<para> +<emphasis> +Of course it should be clear that the authentication backend itself could be +from any distributed directory architecture server that is supported by Samba. +This can be LDAP (from OpenLDAP), or Sun's iPlanet, or NetWare Directory +Server, and so on. +</emphasis> +</para> + +<para><note> +When Samba is configured to use an LDAP, or other identity management and/or +directory service, it is Samba that continues to perform user and machine +authentication. It should be noted that the LDAP server does not perform +authentication handling in place of what Samba is designed to do. +</note></para> + +<para> +Please refer to <link linkend="samba-pdc">Domain Control</link>, for more information regarding +how to create a domain machine account for a Domain Member server as well as for +information on how to enable the Samba Domain Member machine to join the domain +and be fully trusted by it. +</para> + +<sect2> +<title>Joining an NT4-type Domain with Samba-3</title> + +<para><link linkend="assumptions">Next table</link> lists names that have been used in the remainder of this chapter.</para> + +<table frame="all" id="assumptions"><title>Assumptions</title> + <tgroup cols="2"> + <colspec align="right"/> + <colspec align="left"/> + <tbody> + <row> + <entry>NetBIOS name:</entry><entry>SERV1</entry> + </row> + <row> + <entry>Windows 200x/NT domain name:</entry><entry>&example.workgroup;</entry> + </row> + <row> + <entry>Domain's PDC NetBIOS name:</entry><entry>DOMPDC</entry> + </row> + <row> + <entry>Domain's BDC NetBIOS names:</entry><entry>DOMBDC1 and DOMBDC2</entry> + </row> + </tbody> + </tgroup> +</table> + +<para> +First, you must edit your &smb.conf; file to tell Samba it should now use domain security. +</para> + +<para> + Change (or add) your + <smbconfoption><name>security</name></smbconfoption> line in the [global] section +of your &smb.conf; to read: +</para> + +<para> +<smbconfblock> +<smbconfoption><name>security</name><value>domain</value></smbconfoption> +</smbconfblock> +</para> + +<para> +Next change the <smbconfoption><name>workgroup</name></smbconfoption> line in the <smbconfsection>[global]</smbconfsection> +section to read: +</para> + +<para> +<smbconfblock> +<smbconfoption><name>workgroup</name><value>&example.workgroup;</value></smbconfoption> +</smbconfblock> +</para> + +<para> +This is the name of the domain we are joining. +</para> + +<para> +You must also have the parameter <smbconfoption><name>encrypt passwords</name></smbconfoption> +set to <constant>yes</constant> in order for your users to authenticate to the NT PDC. +This is the default setting if this parameter is not specified. There is no need to specify this +parameter, but if it is specified in the &smb.conf; file, it must be set to <constant>Yes</constant>. +</para> + +<para> +Finally, add (or modify) a <smbconfoption><name>password server</name></smbconfoption> line in the [global] +section to read: +</para> + +<para> +<smbconfblock> +<smbconfoption><name>password server</name><value>DOMPDC DOMBDC1 DOMBDC2</value></smbconfoption> +</smbconfblock> +</para> + +<para> +These are the primary and backup Domain Controllers Samba +will attempt to contact in order to authenticate users. Samba will +try to contact each of these servers in order, so you may want to +rearrange this list in order to spread out the authentication load +among Domain Controllers. +</para> + +<para> +Alternately, if you want smbd to automatically determine +the list of Domain Controllers to use for authentication, you may +set this line to be: +</para> + +<para> +<smbconfblock> +<smbconfoption><name>password server</name><value>*</value></smbconfoption> +</smbconfblock> +</para> + +<para> +This method allows Samba to use exactly the same mechanism that NT does. The +method either uses broadcast-based name resolution, performs a WINS database +lookup in order to find a Domain Controller against which to authenticate, +or locates the Domain Controller using DNS name resolution. +</para> + +<para> +To join the domain, run this command: +</para> + +<para> +<screen> +&rootprompt;<userinput>net join -S DOMPDC -U<replaceable>Administrator%password</replaceable></userinput> +</screen> +</para> + +<para> +If the <option>-S DOMPDC</option> argument is not given, the domain name will be obtained from &smb.conf;. +</para> + +<para> +The machine is joining the domain DOM, and the PDC for that domain (the only machine +that has write access to the domain SAM database) is DOMPDC, therefore use the <option>-S</option> +option. The <replaceable>Administrator%password</replaceable> is the login name and +password for an account that has the necessary privilege to add machines to the +domain. If this is successful, you will see the message in your terminal window the +text shown below. Where the older NT4 style domain architecture is used: +<screen> +<computeroutput>Joined domain DOM.</computeroutput> +</screen> +</para> + +<para> +Where Active Directory is used: +<screen> +<computeroutput>Joined SERV1 to realm MYREALM.</computeroutput> +</screen> +</para> + +<para> +Refer to the <command>net</command> man page for further information. +</para> + +<para> +This process joins the server to the domain without having to create the machine +trust account on the PDC beforehand. +</para> + +<para> +This command goes through the machine account password change protocol, then writes +the new (random) machine account password for this Samba server into a file in the +same directory in which a smbpasswd file would be normally stored: +<screen> +<filename>/usr/local/samba/private/secrets.tdb</filename> +or +<filename>/etc/samba/secrets.tdb</filename>. +</screen> +</para> + +<para> +This file is created and owned by root and is not readable by any other user. It is +the key to the Domain-level security for your system, and should be treated as carefully +as a shadow password file. +</para> + +<para> +Finally, restart your Samba daemons and get ready for clients to begin using domain +security. The way you can restart your Samba daemons depends on your distribution, +but in most cases the following will suffice: +<screen> +&rootprompt;/etc/init.d/samba restart +</screen> +</para> + +</sect2> + +<sect2> +<title>Why Is This Better Than <parameter>security = server</parameter>?</title> + +<para> +Currently, domain security in Samba does not free you from +having to create local UNIX users to represent the users attaching +to your server. This means that if Domain user <constant>DOM\fred +</constant> attaches to your Domain Security Samba server, there needs +to be a local UNIX user fred to represent that user in the UNIX +file system. This is similar to the older Samba security mode +<smbconfoption><name>security</name><value>server</value></smbconfoption>, +where Samba would pass through the authentication request to a Windows +NT server in the same way as a Windows 95 or Windows 98 server would. +</para> + +<para> +Please refer to <link linkend="winbind">Winbind: Use of Domain Accounts</link> chapter, for information on a system +to automatically assign UNIX UIDs and GIDs to Windows NT Domain users and groups. +</para> + +<para> +The advantage to Domain-level security is that the +authentication in Domain-level security is passed down the authenticated +RPC channel in exactly the same way that an NT server would do it. This +means Samba servers now participate in domain trust relationships in +exactly the same way NT servers do (i.e., you can add Samba servers into +a resource domain and have the authentication passed on from a resource +domain PDC to an account domain PDC). +</para> + +<para> +In addition, with <smbconfoption><name>security</name><value>server</value></smbconfoption>, every Samba +daemon on a server has to keep a connection open to the +authenticating server for as long as that daemon lasts. This can drain +the connection resources on a Microsoft NT server and cause it to run +out of available connections. With <smbconfoption><name>security</name><value>domain</value></smbconfoption>, +however, the Samba daemons connect to the PDC/BDC only for as long +as is necessary to authenticate the user and then drop the connection, +thus conserving PDC connection resources. +</para> + +<para> +And finally, acting in the same manner as an NT server +authenticating to a PDC means that as part of the authentication +reply, the Samba server gets the user identification information such +as the user SID, the list of NT groups the user belongs to, and so on. +</para> + +<note> +<para> +Much of the text of this document was first published in the Web magazine +<ulink url="http://www.linuxworld.com">LinuxWorld</ulink> as the article <ulink +url="http://www.linuxworld.com/linuxworld/lw-1998-10/lw-10-samba.html"/> +<emphasis>Doing the NIS/NT Samba</emphasis>. +</para> +</note> + +</sect2> +</sect1> + +<sect1 id="ads-member"> +<title>Samba ADS Domain Membership</title> + +<para> +<indexterm significance="preferred"><primary>Active Directory</primary></indexterm> +<indexterm significance="preferred"><primary>ADS</primary><see>Active Directory</see></indexterm> +<indexterm><primary>KDC</primary></indexterm> +<indexterm><primary>Kerberos</primary></indexterm> +This is a rough guide to setting up Samba-3 with Kerberos authentication against a +Windows 200x KDC. A familiarity with Kerberos is assumed. +</para> + +<sect2> +<title>Configure &smb.conf;</title> + +<para> +You must use at least the following three options in &smb.conf;: +</para> + +<para><smbconfblock> +<smbconfoption><name>realm</name><value>your.kerberos.REALM</value></smbconfoption> +<smbconfoption><name>security</name><value>ADS</value></smbconfoption> +<smbconfcomment>The following parameter need only be specified if present.</smbconfcomment> +<smbconfcomment>The default setting is not present is Yes.</smbconfcomment> +<smbconfoption><name>encrypt passwords</name><value>yes</value></smbconfoption> +</smbconfblock></para> + +<para> +In case samba cannot correctly identify the appropriate ADS server using the realm name, use the +<smbconfoption><name>password server</name></smbconfoption> option in &smb.conf;: +<smbconfblock> +<smbconfoption><name>password server</name><value>your.kerberos.server</value></smbconfoption> +</smbconfblock> +</para> + +<note><para> +You do <emphasis>not</emphasis> need a smbpasswd file, and older clients will be authenticated as +if <smbconfoption><name>security</name><value>domain</value></smbconfoption>, although it will not do any harm and +allows you to have local users not in the domain. +</para></note> + +</sect2> + +<sect2> +<title>Configure <filename>/etc/krb5.conf</filename></title> + +<para> +<indexterm><primary>/etc/krb5.conf</primary></indexterm> +<indexterm><primary>Kerberos</primary><secondary>/etc/krb5.conf</secondary></indexterm> +With both MIT and Heimdal Kerberos, it is unnecessary to configure the +<filename>/etc/krb5.conf</filename>, and it may be detrimental. +</para> + +<para> +Microsoft Active Directory servers automatically create SRV records in the DNS zone +<parameter>_kerberos.REALM.NAME</parameter> for each KDC in the realm. This is part +of the installation and configuration process used to create an Active Directory Domain. +</para> + +<para> +MIT's, as well as Heimdal's, recent KRB5 libraries default to checking for SRV records, so they will +automatically find the KDCs. In addition, <filename>krb5.conf</filename> only allows specifying +a single KDC, even there if there may be more than one. Using the DNS lookup allows the KRB5 +libraries to use whichever KDCs are available. +</para> + +<para> +When manually configuring <filename>krb5.conf</filename>, the minimal configuration is: +</para> + +<para> + <smbfile name="krb5.conf"> + <programlisting> +[libdefaults] + default_realm = YOUR.KERBEROS.REALM + +[realms] + YOUR.KERBEROS.REALM = { + kdc = your.kerberos.server + } + +[domain_realms] + .kerberos.server = YOUR.KERBEROS.REALM +</programlisting></smbfile></para> + +<para> +When using Heimdal versions before 0.6 use the following configuration settings: +<screen> +[libdefaults] + default_realm = YOUR.KERBEROS.REALM + default_etypes = des-cbc-crc des-cbc-md5 + default_etypes_des = des-cbc-crc des-cbc-md5 + +[realms] + YOUR.KERBEROS.REALM = { + kdc = your.kerberos.server + } + +[domain_realms] + .kerberos.server = YOUR.KERBEROS.REALM +</screen> +</para> + +<para> +<indexterm><primary>kinit</primary></indexterm> +Test your config by doing a <userinput>kinit +<replaceable>USERNAME</replaceable>@<replaceable>REALM</replaceable></userinput> and +making sure that your password is accepted by the Win2000 KDC. +</para> + +<para> +With Heimdal versions earlier than 0.6.x you only can use newly created accounts +in ADS or accounts that have had the password changed once after migration, or +in case of <constant>Administrator</constant> after installation. At the +moment, a Windows 2003 KDC can only be used with a Heimdal releases later than 0.6 +(and no default etypes in krb5.conf). Unfortunately this whole area is still +in a state of flux. +</para> + +<note><para> +The realm must be in uppercase or you will get <quote><errorname>Cannot find KDC for +requested realm while getting initial credentials</errorname></quote> error (Kerberos +is case-sensitive!). +</para></note> + +<note><para> +Time between the two servers must be synchronized. You will get a +<quote><errorname>kinit(v5): Clock skew too great while getting initial credentials</errorname></quote> +if the time difference is more than five minutes. +</para></note> + +<para> +Clock skew limits are configurable in the Kerberos protocols. The default setting is +five minutes. +</para> + +<para> +You also must ensure that you can do a reverse DNS lookup on the IP +address of your KDC. Also, the name that this reverse lookup maps to +must either be the NetBIOS name of the KDC (i.e., the hostname with no +domain attached) or it can alternately be the NetBIOS name followed by the realm. +</para> + +<para> +The easiest way to ensure you get this right is to add a +<filename>/etc/hosts</filename> entry mapping the IP address of your KDC to +its NetBIOS name. If you do not get this correct then you will get a +<errorname>local error</errorname> when you try to join the realm. +</para> + +<para> +If all you want is Kerberos support in &smbclient; then you can skip +directly to <link linkend="ads-test-smbclient">Testing with &smbclient;</link> now. +<link linkend="ads-create-machine-account">Create the Computer Account</link> and +<link linkend="ads-test-server">Testing Server Setup</link> +are needed only if you want Kerberos support for &smbd; and &winbindd;. +</para> + +</sect2> + +<sect2 id="ads-create-machine-account"> +<title>Create the Computer Account</title> + +<para> +As a user who has write permission on the Samba private directory (usually root), run: +<screen> +&rootprompt; <userinput>net ads join -U Administrator%password</userinput> +</screen> +</para> + +<para> +When making a Windows client a member of an ADS domain within a complex organization, you +may want to create the machine account within a particular organizational unit. Samba-3 permits +this to be done using the following syntax: +<screen> +&rootprompt; <userinput>kinit Administrator@your.kerberos.REALM</userinput> +&rootprompt; <userinput>net ads join <quote>organizational_unit</quote></userinput> +</screen> +</para> + +<para> +For example, you may want to create the machine account in a container called <quote>Servers</quote> +under the organizational directory <quote>Computers\BusinessUnit\Department</quote> like this: +<screen> +&rootprompt; <userinput>net ads join "Computers\BusinessUnit\Department\Servers"</userinput> +</screen> +</para> + +<?latex \newpage ?> + +<sect3> +<title>Possible Errors</title> + +<para> +<variablelist> + <varlistentry><term><errorname>ADS support not compiled in</errorname></term> + <listitem><para>Samba must be reconfigured (remove config.cache) and recompiled + (make clean all install) after the Kerberos libraries and headers files are installed. + </para></listitem></varlistentry> + + <varlistentry><term><errorname>net ads join prompts for user name</errorname></term> + <listitem><para>You need to login to the domain using <userinput>kinit + <replaceable>USERNAME</replaceable>@<replaceable>REALM</replaceable></userinput>. + <replaceable>USERNAME</replaceable> must be a user who has rights to add a machine + to the domain. </para></listitem></varlistentry> + + <varlistentry><term>Unsupported encryption/or checksum types</term> + <listitem><para> + Make sure that the <filename>/etc/krb5.conf</filename> is correctly configured + for the type and version of Kerberos installed on the system. + </para></listitem></varlistentry> +</variablelist> +</para> + +</sect3> + +</sect2> + +<sect2 id="ads-test-server"> +<title>Testing Server Setup</title> + +<para> +If the join was successful, you will see a new computer account with the +NetBIOS name of your Samba server in Active Directory (in the <quote>Computers</quote> +folder under Users and Computers. +</para> + +<para> +On a Windows 2000 client, try <userinput>net use * \\server\share</userinput>. You should +be logged in with Kerberos without needing to know a password. If this fails then run +<userinput>klist tickets</userinput>. Did you get a ticket for the server? Does it have +an encryption type of DES-CBC-MD5? +</para> + +<para><note> +Samba can use both DES-CBC-MD5 encryption as well as ARCFOUR-HMAC-MD5 encoding. +</note></para> + +</sect2> + +<sect2 id="ads-test-smbclient"> +<title>Testing with &smbclient;</title> + + +<para> +<indexterm><primary>smbclient</primary></indexterm> +On your Samba server try to login to a Win2000 server or your Samba +server using &smbclient; and Kerberos. Use &smbclient; as usual, but +specify the <option>-k</option> option to choose Kerberos authentication. +</para> + +</sect2> + +<sect2> +<title>Notes</title> + +<para> +You must change administrator password at least once after DC +install, to create the right encryption types. +</para> + +<para> +Windows 200x does not seem to create the <parameter>_kerberos._udp</parameter> and <parameter>_ldap._tcp</parameter> in +the default DNS setup. Perhaps this will be fixed later in service packs. +</para> + +</sect2> +</sect1> + +<sect1> +<title>Sharing User ID Mappings between Samba Domain Members</title> + +<para> +Samba maps UNIX users and groups (identified by UIDs and GIDs) to Windows users and groups (identified by SIDs). +These mappings are done by the <parameter>idmap</parameter> subsystem of Samba. +</para> + +<para> +In some cases it is useful to share these mappings between Samba Domain Members, +so <emphasis>name->id</emphasis> mapping is identical on all machines. +This may be needed in particular when sharing files over both CIFS and NFS. +</para> + +<para>To use the <emphasis>LDAP</emphasis> <parameter>ldap idmap suffix</parameter>, set:</para> + +<smbconfblock> +<smbconfoption><name>ldap idmap suffix</name><value>ou=Idmap,dc=quenya,dc=org</value></smbconfoption> +</smbconfblock> + +<para>See the &smb.conf; man page entry for the <smbconfoption><name>ldap idmap suffix</name><value></value></smbconfoption> +parameter for further information.</para> + +<para> +Do not forget to specify also the <smbconfoption><name>ldap admin dn</name></smbconfoption> +and to make certain to set the LDAP administrative password into the <filename>secrets.tdb</filename> using: +<screen> +&rootprompt; smbpasswd -w ldap-admin-password +</screen></para> + +</sect1> + +<sect1> +<title>Common Errors</title> + +<para> +In the process of adding/deleting/re-adding Domain Member machine accounts, there are +many traps for the unwary player and many <quote>little</quote> things that can go wrong. +It is particularly interesting how often subscribers on the Samba mailing list have concluded +after repeated failed attempts to add a machine account that it is necessary to <quote>re-install</quote> +MS Windows on the machine. In truth, it is seldom necessary to reinstall because of this type +of problem. The real solution is often quite simple and with an understanding of how MS Windows +networking functions, it is easy to overcome. +</para> + +<sect2> +<title>Cannot Add Machine Back to Domain</title> + +<para> +<quote>A Windows workstation was re-installed. The original domain machine +account was deleted and added immediately. The workstation will not join the domain if I use +the same machine name. Attempts to add the machine fail with a message that the machine already +exists on the network &smbmdash; I know it does not. Why is this failing?</quote> +</para> + +<para> +The original name is still in the NetBIOS name cache and must expire after machine account +deletion before adding that same name as a Domain Member again. The best advice is to delete +the old account and then add the machine with a new name. +</para> + +</sect2> + +<sect2> +<title>Adding Machine to Domain Fails</title> + +<para> +<quote>Adding a Windows 200x or XP Professional machine to the Samba PDC Domain fails with a +message that, <errorname>`The machine could not be added at this time, there is a network problem. +Please try again later.'</errorname> Why?</quote> +</para> + +<para> +You should check that there is an <smbconfoption><name>add machine script</name></smbconfoption> in your &smb.conf; +file. If there is not, please add one that is appropriate for your OS platform. If a script +has been defined, you will need to debug its operation. Increase the <smbconfoption><name>log level</name><value></value></smbconfoption> +in the &smb.conf; file to level 10, then try to rejoin the domain. Check the logs to see which +operation is failing. +</para> + +<para> +Possible causes include: +</para> + +<itemizedlist> + <listitem><para> + The script does not actually exist, or could not be located in the path specified. + </para> + + <para> + <emphasis>Corrective action:</emphasis> Fix it. Make sure when run manually + that the script will add both the UNIX system account and the Samba SAM account. + </para></listitem> + + <listitem><para> + The machine could not be added to the UNIX system accounts file <filename>/etc/passwd</filename>. + </para> + + <para> + <emphasis>Corrective action:</emphasis> Check that the machine name is a legal UNIX + system account name. If the UNIX utility <command>useradd</command> is called, + then make sure that the machine name you are trying to add can be added using this + tool. <command>Useradd</command> on some systems will not allow any upper case characters + nor will it allow spaces in the name. + </para></listitem> +</itemizedlist> + +<para> +The <smbconfoption><name>add machine script</name></smbconfoption> does not create the +machine account in the Samba backend database, it is there only to create a UNIX system +account to which the Samba backend database account can be mapped. +</para> + +</sect2> + +<sect2> + <title>I Can't Join a Windows 2003 PDC</title> + + <para>Windows 2003 requires SMB signing. Client side SMB signing has been implemented in Samba-3.0. + Set <smbconfoption><name>client use spnego</name><value>yes</value></smbconfoption> when communicating + with a Windows 2003 server.</para> +</sect2> + +</sect1> +</chapter> |