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<chapter id="InterdomainTrusts">
<chapterinfo>
&author.jht;
&author.mimir;
<pubdate>April 3, 2003</pubdate>
</chapterinfo>
<title>Interdomain Trust Relationships</title>
<para>
Samba-3 supports NT4 style domain trust relationships. This is feature that many sites
will want to use if they migrate to Samba-3 from and NT4 style domain and do NOT want to
adopt Active Directory or an LDAP based authentication back end. This section explains
some background information regarding trust relationships and how to create them. It is now
possible for Samba3 to NT4 trust (and vica versa), as well as Samba3 to Samba3 trusts.
</para>
<sect1>
<title>Trust Relationship Background</title>
<para>
MS Windows NT3.x/4.0 type security domains employ a non-hierchical security structure.
The limitations of this architecture as it affects the scalability of MS Windows networking
in large organisations is well known. Additionally, the flat-name space that results from
this design significantly impacts the delegation of administrative responsibilities in
large and diverse organisations.
</para>
<para>
Microsoft developed Active Directory Service (ADS), based on Kerberos and LDAP, as a means
of circumventing the limitations of the older technologies. Not every organisation is ready
or willing to embrace ADS. For small companies the older NT4 style domain security paradigm
is quite adequate, there thus remains an entrenched user base for whom there is no direct
desire to go through a disruptive change to adopt ADS.
</para>
<para>
Microsoft introduced with MS Windows NT the ability to allow differing security domains
to affect a mechanism so that users from one domain may be given access rights and privilidges
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 are available to another security domain is
said to be a trusted domain. The domain in which those users have assigned rights and privilidges
is the trusting domain. With NT3.x/4.0 all trust relationships are always in one direction only,
thus if users in both domains are to have privilidges and rights in each others' domain, then it is
necessary to establish two (2) relationships, one in each direction.
</para>
<para>
In an NT4 style MS security domain, all trusts are non-transitive. This means that if there
are three (3) 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. ie: Relationships are explicit and not
transitive.
</para>
<para>
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 above, with Windows 2000 and ADS the RED and BLUE domains CAN trust each other. This is
an inherent feature of ADS domains.
</para>
</sect1>
<sect1>
<title>MS Windows NT4 Trust Configuration</title>
<para>
There are two steps to creating an inter-domain trust relationship.
<sect2>
<title>NT4 as the Trusting Domain</title>
<para>
For MS Windows NT4, all domain trust relationships are configured using the Domain User Manager.
To affect a two way trust relationship it is necessary for each domain administrator to make
available (for use by an external domain) it's security resources. This is done from the Domain
User Manager Policies entry on the menu bar. From the Policy menu, select Trust Relationships, then
next to the lower box that is labelled "Permitted to Trust this Domain" are two buttons, "Add" and
"Remove". The "Add" button will open a panel in which needs to be entered the remote domain that
will be able to assign user rights to your domain. In addition it is necessary to enter a password
that is specific to this trust relationship. The password is added twice.
</para>
</sect2>
<sect2>
<title>NT4 as the Trusted Domain</title>
<para>
A trust relationship will work only when the other (trusting) domain makes the appropriate connections
with the trusted domain. To consumate the trust relationship the administrator will launch the
Domain User Manager, from the menu select Policies, then select Trust Relationships, then click on the
"Add" button that is next to the box that is labelled "Trusted Domains". A panel will open in
which must be entered the name of the remote domain as well as the password assigned to that trust.
<para>
</sect2>
</sect1>
<sect1>
<title>Configuring Samba Domain Trusts</title>
<para>
This descitpion is meant to be a fairly short introduction about how to set up a Samba server so
that it could participate in interdomain trust relationships. Trust relationship support in Samba
is in its early stage, so lot of things don't work yet. Paricularly, the contents of this document
applies to NT4-style trusts.
</para>
<para>
Each of the procedures described below is treated as they were performed with Windows NT4 Server on
one end. The other end could just as well be another Samba3 domain. It can be clearly seen, after
reading this document, that combining Samba-specific parts of what's written below leads to trust
between domains in purely Samba environment.
</para>
<sect2>
<title>Samba3 as the Trusting Domain</title>
<para>
In order to set Samba PDC to be trusted party of the relationship first you need
to create special account for domain that will be the trusting party. To do that,
you can use 'smbpasswd' utility. Creating the trusted domain account is very
similiar to creating the connection to the trusting machine's account. Suppose,
your domain is called SAMBA, and the remote domain is called RUMBA. Your first
step will be to issue this command from your favourite shell:
</para>
<para>
<programlisting>
deity# smbpasswd -a -i rumba
New SMB password: XXXXXXXX
Retype SMB password: XXXXXXXX
Added user rumba$
where:
-a means to add a new account into the passdb database
-i means create this account with the Inter-Domain trust flag
The account name will be 'rumba$' (the name ofthe remote domain)
</programlisting>
</para>
<para>
fter issuing this command you'll be asked for typing account's
password. You can use any password you want, but be aware that Windows NT will
not change this password until 7 days have passed since account creating.
After command returns successfully, you can look at your new account's entry
(in the way depending on your configuration) and see that account's name is
really RUMBA$ and it has 'I' flag in the flags field. Now you're ready to confirm
the trust by establishing it from Windows NT Server.
</para>
<para>
Open 'User Manager for Domains' and from menu 'Policies' select 'Trust Relationships...'.
Right beside 'Trusted domains' list press 'Add...' button. You'll be prompted for
trusted domain name and the relationship's password. Type in SAMBA, as this is
your domain name and the password you've just used during account creation.
Press OK and if everything went fine, you will see 'Trusted domain relationship
successfully established' message. Well done.
</para>
</sect2>
<sect2>
<title>Samba3 as the Trusted Domain</title>
<para>
This time activities are somewhat reversed. Again, we'll assume that your domain
controlled by Samba PDC is called SAMBA and NT-controlled domain is called RUMBA.
</para>
<para>
The very first thing is to add account for SAMBA domain on RUMBA's PDC.
</para>
<para>
Launch the Domain User Manager, then from the menu select 'Policies', 'Trust Relationships'.
Now, next to 'Trusted Domains' box press the 'Add' button, and type in the name of the trusted
domein (SAMBA) and password securing the relationship.
</para>
<para>
Password can be arbitrarily chosen the more, because it's easy to change it
from Samba server whenever you want. After confirming password your account is
ready and waiting. Now it's Samba's turn.
</para>
<para>
Using your favourite shell while being logged on as root, issue this command:
</para>
<para>
<programlisting>
deity# net rpc trustdom establish rumba
</programlisting>
</para>
<para>
You'll be prompted for password you've just typed on your Windows NT4 Server box.
Don't worry if you will see the error message with returned code of
<filename>NT_STATUS_NOLOGON_INTERDOMAIN_TRUST_ACCOUNT</filename>. It means the
password you gave is correct and the NT4 Server says the account is ready for trusting your domain
and not for ordinary connection. After that, be patient it can take a while (especially
in large networks), you should see 'Success' message. Contgratulations! Your trust
relationship has just been established.
</para>
<note><para>
Note that you have to run this command as root, since you need write access to
your secrets.tdb file.
</para></note>
</sect2>
</sect1>
</chapter>
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