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diff --git a/docs-xml/Samba3-HOWTO/TOSHARG-InterdomainTrusts.xml b/docs-xml/Samba3-HOWTO/TOSHARG-InterdomainTrusts.xml new file mode 100644 index 00000000000..3ea527ba5e1 --- /dev/null +++ b/docs-xml/Samba3-HOWTO/TOSHARG-InterdomainTrusts.xml @@ -0,0 +1,602 @@ +<?xml version="1.0" encoding="iso-8859-1"?> +<!DOCTYPE chapter PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc"> +<chapter id="InterdomainTrusts"> +<chapterinfo> + &author.jht; + &author.mimir; + <author>&person.jelmer;<contrib>drawing</contrib></author> + <author> + <firstname>Stephen</firstname><surname>Langasek</surname> + <affiliation> + <address><email>vorlon@netexpress.net</email></address> + </affiliation> + </author> + <pubdate>April 3, 2003</pubdate> +</chapterinfo> + +<title>Interdomain Trust Relationships</title> + + +<para> +<indexterm><primary>Interdomain Trusts</primary></indexterm> +<indexterm><primary>LDAP</primary></indexterm> +<indexterm><primary>trusts</primary></indexterm> +<indexterm><primary>samba-to-samba trusts</primary></indexterm> +<indexterm><primary>Active Directory</primary></indexterm> +<indexterm><primary>NT4-style domain</primary></indexterm> +<indexterm><primary>trust relationships</primary></indexterm> +<indexterm><primary>ADS</primary></indexterm> +<indexterm><primary>LDAP-based</primary></indexterm> +Samba-3 supports NT4-style domain trust relationships. This is a feature that many sites +will want to use if they migrate to Samba-3 from an NT4-style domain and do not want to +adopt Active Directory or an LDAP-based authentication backend. This chapter explains +some background information regarding trust relationships and how to create them. It is now +possible for Samba-3 to trust NT4 (and vice versa), as well as to create Samba-to-Samba +trusts. +</para> + +<para> +<indexterm><primary>winbind</primary></indexterm> +<indexterm><primary>UID range</primary></indexterm> +<indexterm><primary>GID range</primary></indexterm> +<indexterm><primary>daemon</primary></indexterm> +<indexterm><primary>winbindd</primary></indexterm> +The use of interdomain trusts requires use of <command>winbind</command>, so the +<command>winbindd</command> daemon must be running. Winbind operation in this mode is +dependent on the specification of a valid UID range and a valid GID range in the &smb.conf; file. +These are specified respectively using: +<smbconfblock> +<smbconfoption name="idmap uid">10000-20000</smbconfoption> +<smbconfoption name="idmap gid">10000-20000</smbconfoption> +</smbconfblock> +<indexterm><primary>passdb backend</primary></indexterm> +<indexterm><primary>POSIX user accounts</primary></indexterm> +<indexterm><primary>maximum value</primary></indexterm> +<indexterm><primary>4294967295</primary></indexterm> +The range of values specified must not overlap values used by the host operating system and must +not overlap values used in the passdb backend for POSIX user accounts. The maximum value is +limited by the upper-most value permitted by the host operating system. This is a UNIX kernel +limited parameter. Linux kernel 2.6-based systems support a maximum value of 4294967295 +(32-bit unsigned variable). +</para> + +<note><para> +<indexterm><primary>winbind</primary></indexterm> +<indexterm><primary>trusting domain</primary></indexterm> +<indexterm><primary>trusted domain</primary></indexterm> +The use of winbind is necessary only when Samba is the trusting domain, not when it is the +trusted domain. +</para></note> + +<sect1> +<title>Features and Benefits</title> + +<para> +<indexterm><primary>scalability</primary></indexterm> +<indexterm><primary>trust relationships</primary></indexterm> +Samba-3 can participate in Samba-to-Samba as well as in Samba-to-MS Windows NT4-style +trust relationships. This imparts to Samba scalability similar to that with MS Windows NT4. +</para> + +<para> +<indexterm><primary>scalable backend</primary></indexterm> +<indexterm><primary>authentication database</primary></indexterm> +<indexterm><primary>LDAP</primary></indexterm> +<indexterm><primary>interdomain trusts</primary></indexterm> +<indexterm><primary>ADS</primary></indexterm> +Given that Samba-3 can function with a scalable backend authentication database such as LDAP, and given its +ability to run in primary as well as backup domain control modes, the administrator would be well-advised to +consider alternatives to the use of interdomain trusts simply because, by the very nature of how trusts +function, this system is fragile. That was, after all, a key reason for the development and adoption of +Microsoft Active Directory. +</para> + +</sect1> + +<sect1> +<title>Trust Relationship Background</title> + +<para> +<indexterm><primary>security domains</primary></indexterm> +<indexterm><primary>nonhierarchical</primary></indexterm> +<indexterm><primary>security structure</primary></indexterm> +<indexterm><primary>large organizations</primary></indexterm> +<indexterm><primary>delegation</primary></indexterm> +<indexterm><primary>administrative responsibilities</primary></indexterm> +MS Windows NT3/4-type security domains employ a nonhierarchical security structure. +The limitations of this architecture as it effects the scalability of MS Windows networking +in large organizations is well known. Additionally, the flat namespace that results from +this design significantly impacts the delegation of administrative responsibilities in +large and diverse organizations. +</para> + +<para> +<indexterm><primary>ADS</primary></indexterm> +<indexterm><primary>Kerberos</primary></indexterm> +<indexterm><primary>LDAP</primary></indexterm> +<indexterm><primary>limitations</primary></indexterm> +<indexterm><primary>domain security</primary></indexterm> +Microsoft developed Active Directory Service (ADS), based on Kerberos and LDAP, as a means +of circumventing the limitations of the older technologies. Not every organization is ready +or willing to embrace ADS. For small companies the older NT4-style domain security paradigm +is quite adequate, and so there remains an entrenched user base for whom there is no direct +desire to go through a disruptive change to adopt ADS. +</para> + +<para> +<indexterm><primary>security domains</primary></indexterm> +<indexterm><primary>access rights</primary></indexterm> +<indexterm><primary>privileges</primary></indexterm> +<indexterm><primary>trusts</primary></indexterm> +<indexterm><primary>trusted domain</primary></indexterm> +<indexterm><primary>trusting domain</primary></indexterm> +<indexterm><primary>one direction</primary></indexterm> +With Windows NT, Microsoft introduced the ability to allow different security domains +to effect a mechanism so users from one domain may be given access rights and privileges +in another domain. The language that describes this capability is couched in terms of +<emphasis>trusts</emphasis>. Specifically, one domain will <emphasis>trust</emphasis> the users +from another domain. The domain from which users can access another security domain is +said to be a trusted domain. The domain in which those users have assigned rights and privileges +is the trusting domain. With NT3.x/4.0 all trust relationships are always in one direction only, +so if users in both domains are to have privileges and rights in each others' domain, then it is +necessary to establish two relationships, one in each direction. +</para> + +<para> +<indexterm><primary>security domain</primary></indexterm> +<indexterm><primary>nontransitive</primary></indexterm> +<indexterm><primary>trust relationship</primary></indexterm> +<indexterm><primary>transitive</primary></indexterm> +<indexterm><primary>explicit trust</primary></indexterm> +Further, in an NT4-style MS security domain, all trusts are nontransitive. This means that if there are three +domains (let's call them red, white, and blue), where red and white have a trust relationship, and white and +blue have a trust relationship, then it holds that there is no implied trust between the red and blue domains. +Relationships are explicit and not transitive. +</para> + +<para> +<indexterm><primary>ADS</primary></indexterm> +<indexterm><primary>security contexts</primary></indexterm> +<indexterm><primary>trust relationships</primary></indexterm> +<indexterm><primary>two-way trust</primary></indexterm> +<indexterm><primary>Windows 2000</primary></indexterm> +<indexterm><primary>security domains</primary></indexterm> +<indexterm><primary>NT4-style domains</primary></indexterm> +New to MS Windows 2000 ADS security contexts is the fact that trust relationships are two-way by default. +Also, all inter-ADS domain trusts are transitive. In the case of the red, white, and blue domains, with +Windows 2000 and ADS, the red and blue domains can trust each other. This is an inherent feature of ADS +domains. Samba-3 implements MS Windows NT4-style interdomain trusts and interoperates with MS Windows 200x ADS +security domains in similar manner to MS Windows NT4-style domains. +</para> + +</sect1> + +<sect1> +<title>Native MS Windows NT4 Trusts Configuration</title> + +<para> +<indexterm><primary>Interdomain Trusts</primary><secondary>creating</secondary></indexterm> +<indexterm><primary>two-way trust</primary></indexterm> +<indexterm><primary>security credentials</primary></indexterm> +There are two steps to creating an interdomain trust relationship. To effect a two-way trust +relationship, it is necessary for each domain administrator to create a trust account for the +other domain to use in verifying security credentials. +</para> + + +<sect2> +<title>Creating an NT4 Domain Trust</title> + +<para> +<indexterm><primary>domain trust</primary></indexterm> +<indexterm><primary>trust relationships</primary></indexterm> +<indexterm><primary>>Domain User Manager</primary></indexterm> +<indexterm><primary>remote domain</primary></indexterm> +<indexterm><primary>standard confirmation</primary></indexterm> +For MS Windows NT4, all domain trust relationships are configured using the +<application>Domain User Manager</application>. This is done from the Domain User Manager Policies +entry on the menu bar. From the <guimenu>Policy</guimenu> menu, select +<guimenuitem>Trust Relationships</guimenuitem>. Next to the lower box labeled +<guilabel>Permitted to Trust this Domain</guilabel> are two buttons, <guibutton>Add</guibutton> +and <guibutton>Remove</guibutton>. The <guibutton>Add</guibutton> button will open a panel in which +to enter the name of the remote domain that will be able to assign access rights to users in +your domain. You will also need to enter a password for this trust relationship, which the +trusting domain will use when authenticating users from the trusted domain. +The password needs to be typed twice (for standard confirmation). +</para> + +</sect2> + + +<sect2> +<title>Completing an NT4 Domain Trust</title> + +<para> +<indexterm><primary>trust relationship</primary></indexterm> +<indexterm><primary>trusting domain</primary></indexterm> +<indexterm><primary>trusted domain</primary></indexterm> +<indexterm><primary>remote domain</primary></indexterm> +<indexterm><primary>password assigned</primary></indexterm> +<indexterm><primary>Interdomain Trusts</primary><secondary>Completing</secondary></indexterm> +A trust relationship will work only when the other (trusting) domain makes the appropriate connections +with the trusted domain. To consummate the trust relationship, the administrator launches the +Domain User Manager from the menu selects <guilabel>Policies</guilabel>, then select +<guilabel>Trust Relationships</guilabel>, and clicks on the <guibutton>Add</guibutton> button +next to the box that is labeled <guilabel>Trusted Domains</guilabel>. A panel opens in which +must be entered the name of the remote domain as well as the password assigned to that trust. +</para> + +</sect2> + +<sect2> +<title>Interdomain Trust Facilities</title> + + +<para> +<indexterm><primary>two-way trust</primary></indexterm> +<indexterm><primary>trust relationship</primary></indexterm> +<indexterm><primary>trust established</primary></indexterm> +<indexterm><primary>one-way trust</primary></indexterm> +<indexterm><primary>Windows NT4 domains</primary></indexterm> +<indexterm><primary>Interdomain Trusts</primary><secondary>Facilities</secondary></indexterm> +A two-way trust relationship is created when two one-way trusts are created, one in each direction. +Where a one-way trust has been established between two MS Windows NT4 domains (let's call them +DomA and DomB), the following facilities are created: +</para> + +<figure id="trusts1"> + <title>Trusts overview.</title> + <imagefile>trusts1</imagefile> +</figure> + +<itemizedlist> + <listitem><para> + DomA (completes the trust connection) <parameter>Trusts</parameter> DomB. + </para></listitem> + + <listitem><para> + DomA is the <parameter>Trusting</parameter> domain. + </para></listitem> + + <listitem><para> + DomB is the <parameter>Trusted</parameter> domain (originates the trust account). + </para></listitem> + + <listitem><para> + Users in DomB can access resources in DomA. + </para></listitem> + + <listitem><para> + Users in DomA cannot access resources in DomB. + </para></listitem> + + <listitem><para> + Global groups from DomB can be used in DomA. + </para></listitem> + + <listitem><para> + Global groups from DomA cannot be used in DomB. + </para></listitem> + + <listitem><para> + DomB does appear in the logon dialog box on client workstations in DomA. + </para></listitem> + + <listitem><para> + DomA does not appear in the logon dialog box on client workstations in DomB. + </para></listitem> +</itemizedlist> + +<itemizedlist> + <listitem><para> + Users and groups in a trusting domain cannot be granted rights, permissions, or access + to a trusted domain. + </para></listitem> + + <listitem><para> + The trusting domain can access and use accounts (users/global groups) in the + trusted domain. + </para></listitem> + + <listitem><para> + Administrators of the trusted domain can be granted administrative rights in the + trusting domain. + </para></listitem> + + <listitem><para> + Users in a trusted domain can be given rights and privileges in the trusting + domain. + </para></listitem> + + <listitem><para> + Trusted domain global groups can be given rights and permissions in the trusting + domain. + </para></listitem> + + <listitem><para> + Global groups from the trusted domain can be made members in local groups on + MS Windows domain member machines. + </para></listitem> +</itemizedlist> + +</sect2> + +</sect1> + +<sect1> +<title>Configuring Samba NT-Style Domain Trusts</title> + +<para> +<indexterm><primary>interdomain trust</primary></indexterm> +This description is meant to be a fairly short introduction about how to set up a Samba server so +that it can participate in interdomain trust relationships. Trust relationship support in Samba +is at an early stage, so do not be surprised if something does not function as it should. +</para> + +<para> +<indexterm><primary>peer domain</primary></indexterm> +<indexterm><primary>trust relationship</primary></indexterm> +<indexterm><primary>Windows NT4 Server</primary></indexterm> +<indexterm><primary>between domains</primary></indexterm> +Each of the procedures described next assumes the peer domain in the trust relationship is controlled by a +Windows NT4 server. However, the remote end could just as well be another Samba-3 domain. It can be clearly +seen, after reading this document, that combining Samba-specific parts of what's written in the following +sections leads to trust between domains in a purely Samba environment. +</para> + +<sect2 id="samba-trusted-domain"> +<title>Samba as the Trusted Domain</title> + +<para> +<indexterm><primary>trusted party</primary></indexterm> +<indexterm><primary>special account</primary></indexterm> +<indexterm><primary>trusting party</primary></indexterm> +<indexterm><primary>PDC</primary></indexterm> +<indexterm><primary>smbpasswd</primary></indexterm> +In order to set the Samba PDC to be the trusted party of the relationship, you first need +to create a special account for the domain that will be the trusting party. To do that, +you can use the <command>smbpasswd</command> utility. Creating the trusted domain account is +similar to creating a trusted machine account. Suppose, your domain is +called SAMBA, and the remote domain is called RUMBA. The first step +will be to issue this command from your favorite shell: +</para> + +<para> +<screen> +&rootprompt; <userinput>smbpasswd -a -i rumba</userinput> +New SMB password: <userinput>XXXXXXXX</userinput> +Retype SMB password: <userinput>XXXXXXXX</userinput> +Added user rumba$ +</screen> + +where <option>-a</option> means to add a new account into the +passdb database and <option>-i</option> means to <quote>create this +account with the Interdomain trust flag</quote>. +</para> + +<para> +<indexterm><primary>account name</primary></indexterm> +<indexterm><primary>remote domain</primary></indexterm> +<indexterm><primary>password database</primary></indexterm> +<indexterm><primary>/etc/passwd</primary></indexterm> +The account name will be <quote>rumba$</quote> (the name of the remote domain). +If this fails, you should check that the trust account has been added to the system +password database (<filename>/etc/passwd</filename>). If it has not been added, you +can add it manually and then repeat the previous step. +</para> + +<para> +<indexterm><primary>password</primary></indexterm> +<indexterm><primary>new account</primary></indexterm> +<indexterm><primary>confirm the trust</primary></indexterm> +<indexterm><primary>Windows NT Server</primary></indexterm> +After issuing this command, you will be asked to enter the password for the account. You can use any password +you want, but be aware that Windows NT will not change this password until 7 days following account creation. +After the command returns successfully, you can look at the entry for the new account (in the standard way as +appropriate for your configuration) and see that the account's name is really RUMBA$ and it has the +<quote>I</quote> flag set in the flags field. Now you are ready to confirm the trust by establishing it from +Windows NT Server. +</para> + + +<para> +<indexterm><primary>User Manager</primary></indexterm> +<indexterm><primary>trusted domain name</primary></indexterm> +<indexterm><primary>relationship password</primary></indexterm> +<indexterm><primary>remote domain</primary></indexterm> +<indexterm><primary>established</primary></indexterm> +Open <application>User Manager for Domains</application> and from the <guimenu>Policies</guimenu> menu, select +<guimenuitem>Trust Relationships...</guimenuitem>. Beside the <guilabel>Trusted domains</guilabel> list box, +click the <guimenu>Add...</guimenu> button. You will be prompted for the trusted domain name and the +relationship password. Type in SAMBA, as this is the name of the remote domain and the password used at the +time of account creation. Click on <guibutton>OK</guibutton> and, if everything went without incident, you +will see the <computeroutput>Trusted domain relationship successfully established</computeroutput> message. +</para> + +</sect2> +<sect2> +<title>Samba as the Trusting Domain</title> + +<para> +<indexterm><primary>NT-controlled domain</primary></indexterm> +<indexterm><primary>PDC</primary></indexterm> +This time activities are somewhat reversed. Again, we'll assume that your domain +controlled by the Samba PDC is called SAMBA and the NT-controlled domain is called RUMBA. +</para> + +<para> +The very first step is to add an account for the SAMBA domain on RUMBA's PDC. +</para> + + +<para> +<indexterm><primary>User Manager</primary></indexterm> +<indexterm><primary>trusted domain</primary></indexterm> +<indexterm><primary>password</primary></indexterm> +Launch the <application>Domain User Manager</application>, then from the menu select +<guimenu>Policies</guimenu>, <guimenuitem>Trust Relationships</guimenuitem>. +Now, next to the <guilabel>Trusting Domains</guilabel> box, press the <guibutton>Add</guibutton> +button and type in the name of the trusted domain (SAMBA) and the password to use in securing +the relationship. +</para> + +<para> +<indexterm><primary>password</primary></indexterm> +<indexterm><primary>confirm the password</primary></indexterm> +The password can be arbitrarily chosen. It is easy to change the password from the Samba server whenever you +want. After you confirm the password, your account is ready for use. Now its Samba's turn. +</para> + +<para> +Using your favorite shell while logged in as root, issue this command: +<indexterm><primary>net</primary><secondary>rpc</secondary><tertiary>trustdom establish</tertiary></indexterm> +</para> + +<para> +&rootprompt;<userinput>net rpc trustdom establish rumba</userinput> +</para> + +<para> +<indexterm><primary>password</primary></indexterm> +<indexterm><primary>interdomain connection</primary></indexterm> +<indexterm><primary>ordinary connection</primary></indexterm> +You will be prompted for the password you just typed on your Windows NT4 Server box. +An error message, <literal>"NT_STATUS_NOLOGON_INTERDOMAIN_TRUST_ACCOUNT,"</literal> +that may be reported periodically is of no concern and may safely be ignored. +It means the password you gave is correct and the NT4 server says the account is ready for +interdomain connection and not for ordinary connection. After that, be patient; +it can take a while (especially in large networks), but eventually you should see +the <literal>Success</literal> message. Congratulations! Your trust +relationship has just been established. +</para> + +<note><para> +You have to run this command as root because you must have write access to +the <filename>secrets.tdb</filename> file. +</para></note> + +</sect2> +</sect1> + +<sect1> +<title>NT4-Style Domain Trusts with Windows 2000</title> + +<para> +<indexterm><primary>trust relationship</primary></indexterm> +<indexterm><primary>Windows 2000 server</primary></indexterm> +<indexterm><primary>NT4-style</primary></indexterm> +<indexterm><primary>mixed mode</primary></indexterm> +Although <application>Domain User Manager</application> is not present in Windows 2000, it is +also possible to establish an NT4-style trust relationship with a Windows 2000 domain +controller running in mixed mode as the trusting server. It should also be possible for +Samba to trust a Windows 2000 server; however, more testing is still needed in this area. +</para> + +<para> +<indexterm><primary>interdomain trust</primary></indexterm> +<indexterm><primary>trust account</primary></indexterm> +<indexterm><primary>not transitive</primary></indexterm> +<indexterm><primary>ADS</primary></indexterm> +After <link linkend="samba-trusted-domain">creating the interdomain trust account on the Samba server</link> +as described previously, open <application>Active Directory Domains and Trusts</application> on the AD +controller of the domain whose resources you wish Samba users to have access to. Remember that since NT4-style +trusts are not transitive, if you want your users to have access to multiple mixed-mode domains in your AD +forest, you will need to repeat this process for each of those domains. With <application>Active Directory +domains and trusts</application> open, right-click on the name of the Active Directory domain that will trust +our Samba domain and choose <guimenuitem>Properties</guimenuitem>, then click on the +<guilabel>Trusts</guilabel> tab. In the upper part of the panel, you will see a list box labeled +<guilabel>Domains trusted by this domain:</guilabel> and an <guilabel>Add...</guilabel> button next to it. +Press this button and, just as with NT4, you will be prompted for the trusted domain name and the relationship +password. Press <emphasis>OK</emphasis> and after a moment, Active Directory will respond with +<computeroutput>The trusted domain has been added and the trust has been verified.</computeroutput> Your +Samba users can now be granted access to resources in the AD domain. +</para> +</sect1> + +<sect1> +<title>Common Errors</title> + +<para> +Interdomain trust relationships should not be attempted on networks that are unstable +or that suffer regular outages. Network stability and integrity are key concerns with +distributed trusted domains. +</para> + +<sect2> +<title>Browsing of Trusted Domain Fails</title> + +<para> +<emphasis>Browsing from a machine in a trusted Windows 200x domain to a Windows 200x member of +a trusting Samba domain, I get the following error:</emphasis> +<screen> +The system detected a possible attempt to compromise security. Please +ensure that you can contact the server that authenticated you. +</screen> +</para> + +<para> +<emphasis>The event logs on the box I'm trying to connect to have entries regarding group +policy not being applied because it is a member of a down-level domain.</emphasis> +</para> + +<para>If there is a computer account in the Windows +200x domain for the machine in question, and it is disabled, this problem can +occur. If there is no computer account (removed or never existed), or if that +account is still intact (i.e., you just joined it to another domain), everything +seems to be fine. By default, when you unjoin a domain (the Windows 200x +domain), the computer tries to automatically disable the computer account in +the domain. If you are running as an account that has privileges to do this +when you unjoin the machine, it is done; otherwise it is not done. +</para> + +</sect2> + +<sect2> +<title>Problems with LDAP ldapsam and Older Versions of smbldap-tools</title> + +<para> +If you use the <command>smbldap-useradd</command> script to create a trust +account to set up interdomain trusts, the process of setting up the trust will +fail. The account that was created in the LDAP database will have an account +flags field that has <literal>[W ]</literal>, when it must have +<literal>[I ]</literal> for interdomain trusts to work. +</para> + +<para>Here is a simple solution. +Create a machine account as follows: +<screen> +&rootprompt; smbldap-useradd -w domain_name +</screen> +Then set the desired trust account password as shown here: +<screen> +&rootprompt; smbldap-passwd domain_name\$ +</screen> +Using a text editor, create the following file: +<screen> +dn: uid=domain_name$,ou=People,dc={your-domain},dc={your-top-level-domain} +changetype: modify +sambaAcctFlags: [I ] +</screen> +Then apply the text file to the LDAP database as follows: +<screen> +&rootprompt; ldapmodify -x -h localhost \ + -D "cn=Manager,dc={your-domain},dc={your-top-level-domain}" \ + -W -f /path-to/foobar +</screen> +Create a single-sided trust under the NT4 Domain User Manager, then execute: +<screen> +&rootprompt; net rpc trustdom establish domain_name +</screen> +</para> + +<para> +It works with Samba-3 and NT4 domains, and also with Samba-3 and Windows 200x ADS in mixed mode. +Both domain controllers, Samba and NT must have the same WINS server; otherwise, +the trust will never work. +</para> + +</sect2> + +</sect1> + +</chapter> |