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<chapter id="domain-security">
<chapterinfo>
<author>
<firstname>Jeremy</firstname><surname>Allison</surname>
<affiliation>
<orgname>Samba Team</orgname>
<address>
<email>samba@samba.org</email>
</address>
</affiliation>
</author>
<author>
<firstname>Jerry</firstname><surname>Carter</surname>
<affiliation>
<orgname>Samba Team</orgname>
<address>
<email>jerry@samba.org</email>
</address>
</affiliation>
</author>
<pubdate>16 Apr 2001</pubdate>
</chapterinfo>
<title>security = domain in Samba 2.x</title>
<sect1>
<title>Joining an NT Domain with Samba 2.2</title>
<para>In order for a Samba-2 server to join an NT domain,
you must first add the NetBIOS name of the Samba server to the
NT domain on the PDC using Server Manager for Domains. This creates
the machine account in the domain (PDC) SAM. Note that you should
add the Samba server as a "Windows NT Workstation or Server",
<emphasis>NOT</emphasis> as a Primary or backup domain controller.</para>
<para>Assume you have a Samba-2 server with a NetBIOS name of
<constant>SERV1</constant> and are joining an NT domain called
<constant>DOM</constant>, which has a PDC with a NetBIOS name
of <constant>DOMPDC</constant> and two backup domain controllers
with NetBIOS names <constant>DOMBDC1</constant> and <constant>DOMBDC2
</constant>.</para>
<para>In order to join the domain, first stop all Samba daemons
and run the command:</para>
<para><prompt>root# </prompt><userinput>smbpasswd -j DOM -r DOMPDC
</userinput></para>
<para>as we are joining the domain DOM and the PDC for that domain
(the only machine that has write access to the domain SAM database)
is DOMPDC. If this is successful you will see the message:</para>
<para><computeroutput>smbpasswd: Joined domain DOM.</computeroutput>
</para>
<para>in your terminal window. See the <ulink url="smbpasswd.8.html">
smbpasswd(8)</ulink> man page for more details.</para>
<para>There is existing development code to join a domain
without having to create the machine trust account on the PDC
beforehand. This code will hopefully be available soon
in release branches as well.</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 an smbpasswd file would be stored - normally :</para>
<para><filename>/usr/local/samba/private</filename></para>
<para>In Samba 2.0.x, the filename looks like this:</para>
<para><filename><replaceable><NT DOMAIN NAME></replaceable>.<replaceable><Samba
Server Name></replaceable>.mac</filename></para>
<para>The <filename>.mac</filename> suffix stands for machine account
password file. So in our example above, the file would be called:</para>
<para><filename>DOM.SERV1.mac</filename></para>
<para>In Samba 2.2, this file has been replaced with a TDB
(Trivial Database) file named <filename>secrets.tdb</filename>.
</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>Now, before restarting the Samba daemons you must
edit your <ulink url="smb.conf.5.html"><filename>smb.conf(5)</filename>
</ulink> file to tell Samba it should now use domain security.</para>
<para>Change (or add) your <ulink url="smb.conf.5.html#SECURITY">
<parameter>security =</parameter></ulink> line in the [global] section
of your smb.conf to read:</para>
<para><command>security = domain</command></para>
<para>Next change the <ulink url="smb.conf.5.html#WORKGROUP"><parameter>
workgroup =</parameter></ulink> line in the [global] section to read: </para>
<para><command>workgroup = DOM</command></para>
<para>as this is the name of the domain we are joining. </para>
<para>You must also have the parameter <ulink url="smb.conf.5.html#ENCRYPTPASSWORDS">
<parameter>encrypt passwords</parameter></ulink> set to <constant>yes
</constant> in order for your users to authenticate to the NT PDC.</para>
<para>Finally, add (or modify) a <ulink url="smb.conf.5.html#PASSWORDSERVER">
<parameter>password server =</parameter></ulink> line in the [global]
section to read: </para>
<para><command>password server = DOMPDC DOMBDC1 DOMBDC2</command></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>Alternatively, 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><command>password server = *</command></para>
<para>This method, which was introduced in Samba 2.0.6,
allows Samba to use exactly the same mechanism that NT does. This
method either broadcasts or uses a WINS database in order to
find domain controllers to authenticate against.</para>
<para>Finally, restart your Samba daemons and get ready for
clients to begin using domain security!</para>
</sect1>
<sect1>
<title>Samba and Windows 2000 Domains</title>
<para>
Many people have asked regarding the state of Samba's ability to participate in
a Windows 2000 Domain. Samba 2.2 is able to act as a member server of a Windows
2000 domain operating in mixed or native mode.
</para>
<para>
There is much confusion between the circumstances that require a "mixed" mode
Win2k DC and a when this host can be switched to "native" mode. A "mixed" mode
Win2k domain controller is only needed if Windows NT BDCs must exist in the same
domain. By default, a Win2k DC in "native" mode will still support
NetBIOS and NTLMv1 for authentication of legacy clients such as Windows 9x and
NT 4.0. Samba has the same requirements as a Windows NT 4.0 member server.
</para>
<para>
The steps for adding a Samba 2.2 host to a Win2k domain are the same as those
for adding a Samba server to a Windows NT 4.0 domain. The only exception is that
the "Server Manager" from NT 4 has been replaced by the "Active Directory Users and
Computers" MMC (Microsoft Management Console) plugin.
</para>
</sect1>
<sect1>
<title>Why is this better than security = server?</title>
<para>Currently, domain security in Samba doesn't 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
filesystem. This is very similar to the older Samba security mode
<ulink url="smb.conf.5.html#SECURITYEQUALSSERVER">security = server</ulink>,
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 the <ulink url="winbind.html">Winbind
paper</ulink> for information on a system to automatically
assign UNIX uids and gids to Windows NT Domain users and groups.
This code is available in development branches only at the moment,
but will be moved to release branches soon.</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 <command>security = server</command> 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 <command>security = domain</command>,
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, etc. All
this information will allow Samba to be extended in the future into
a mode the developers currently call appliance mode. In this mode,
no local Unix users will be necessary, and Samba will generate Unix
uids and gids from the information passed back from the PDC when a
user is authenticated, making a Samba server truly plug and play
in an NT domain environment. Watch for this code soon.</para>
<para><emphasis>NOTE:</emphasis> 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">Doing
the NIS/NT Samba</ulink>.</para>
</sect1>
</chapter>
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