samba-mirror/docs/docbook/projdoc/NT4Migration.xml

<chapter id="NT4Migration">
<chapterinfo>
	&author.jht;
	<pubdate>April 3, 2003</pubdate>
</chapterinfo>

<title>Migration from NT4 PDC to Samba-3 PDC</title>

<para>
This is a rough guide to assist those wishing to migrate from NT4 domain control to
Samba-3 based domain control.
</para>

<sect1>
<title>Planning and Getting Started</title>

<para>
In the IT world there is often a saying that all problems are encountered because of
poor planning. The corrollary to this saying is that not all problems can be anticpated
and planned for. Then again, good planning will anticpate most show stopper type situations.
</para>

<para>
Those wishing to migrate from MS Windows NT4 domain control to a Samba-3 domain control
environment would do well to develop a detailed migration plan. So here are a few pointers to
help migration get under way.
</para>

<sect2>
<title>Objectives</title>

<para>
The key objective for most organisations will be to make the migration from MS Windows NT4 
to Samba-3 domain control as painless as possible. One of the challenges you may experience
in your migration process may well be one of convincing management that the new environment
should remain in place. Many who have introduced open source technologies have experienced
pressure to return to a Microsoft based platform solution at the first sign of trouble. 
</para>

<para>
It is strongly advised that before attempting a migration to a Samba-3 controlled network
that every possible effort be made to gain all-round commitment to the change. Firstly, you
should know precisely <emphasis>why</emphasis> the change is important for the organisation.
Possible motivations to make a change include:
</para>

<simplelist>
    <member>Improve network manageability</member>
    <member>Obtain better user level functionality</member>
    <member>Reduce network operating costs</member>
    <member>Reduce exposure caused by Microsoft withdrawal of NT4 support</member>
    <member>Avoid MS License 6 implications</member>
    <member>Reduce organisation's dependency on Microsoft</member>
</simplelist>

<para>
It is vital that it be well recognised that Samba-3 is NOT MS Windows NT4. Samba-3 offers
an alternative solution that is both different from MS Windows NT4 and that offers some
advantages compared with it. It should also be recognised that Samba-3 lacks many of the
features that Microsoft has promoted as core values in migration from MS Windows NT4 to 
MS Windows 2000 and beyond (with or without Active Directory services).
</para>

<para>
What are the features that Samba-3 can NOT provide?
</para>

<simplelist>
	<member>Active Directory Server</member>
	<member>Group Policy Objects (in Active Direcrtory)</member>
	<member>Machine Policy objects</member>
	<member>Logon Scripts in Active Directorty</member>
	<member>Software Application and Access Controls in Active Directory</member>
</simplelist>

<para>
The features that Samba-3 DOES provide and that may be of compelling interest to your site
includes:
</para>

<simplelist>
	<member>Lower Cost of Ownership</member>
	<member>Global availability of support with no strings attached</member>
	<member>Dynamic SMB Servers (ie:Can run more than one server per Unix/Linux system)</member>
	<member>Creation of on-the-fly logon scripts</member>
	<member>Creation of on-the-fly Policy Files</member>
	<member>Greater Stability, Reliability, Performance and Availability</member>
	<member>Manageability via an ssh connection</member>
	<member>Flexible choices of back-end authentication technologies (tdbsam, ldapsam, mysqlsam)</member>
	<member>Ability to implement a full single-signon architecture</member>
	<member>Ability to distribute authentication systems for absolute minimum wide area network bandwidth demand</member>
</simplelist>

<para>
Before migrating a network from MS Windows NT4 to Samba-3 it is vital that all necessary factors are
considered. Users should be educated about changes they may experience so that the change will be a
welcome one and not become an obstacle to the work they need to do. The following are some of the
factors that will go into a successful migration:
</para>

<sect3>
<title>Domain Layout</title>

<para>
Samba-3 can be configured as a domain controller, a back-up domain controller (probably best called
a secondary controller), a domain member, or as a stand-alone server. The Windows network security
domain context should be sized and scoped before implementation. Particular attention needs to be
paid to the location of the primary domain controller (PDC) as well as backup controllers (BDCs).
It should be noted that one way in which Samba-3 differs from Microsoft technology is that if one
chooses to use an LDAP authentication backend then the same database can be used by several different
domains. This means that in a complex organisation there can be a single LDAP database, that itself
can be distributed, that can simultaneously serve multiple domains (that can also be widely distributed).
</para>

<para>
It is recommended that from a design perspective, the number of users per server, as well as the number
of servers, per domain should be scaled according to needs and should also consider server capacity
and network bandwidth.
</para>

<para>
A physical network segment may house several domains, each of which may span multiple network segments.
Where domains span routed network segments it is most advisable to consider and test the performance
implications of the design and layout of a network. A Centrally located domain controller that is being
designed to serve mulitple routed network segments may result in severe performance problems if the
response time (eg: ping timing) between the remote segment and the PDC is more than 100 ms. In situations
where the delay is too long it is highly recommended to locate a backup controller (BDC) to serve as
the local authentication and access control server.
</para>
</sect3>

<sect3>
<title>Server Share and Directory Layout</title>

<para>
There are few cardinal rules to effective network design that can be broken with impunity.
The most important rule of effective network management is that simplicity is king in every
well controlled network. Every part of the infrastructure must be managed, the more complex
it is, the greater will be the demand of keeping systems secure and functional.
</para>

<para>
The nature of the data that must be stored needs to be born in mind when deciding how many
shares must be created. The physical disk space layout should also be taken into account
when designing where share points will be created. Keep in mind that all data needs to be
backed up, thus the simpler the disk layout the easier it will be to keep track of what must
be backed up to tape or other off-line storage medium. Always plan and implement for minimum
maintenance. Leave nothing to chance in your design, above all, do not leave backups to chance:
Backup and test, validate every backup, create a disaster recovery plan and prove that it works.
</para>

<para>
Users should be grouped according to data access control needs. File and directory access 
is best controlled via group permissions and the use of the "sticky bit" on group controlled
directories may substantially avoid file access complaints from samba share users.
</para>

<para>
Many network administrators who are new to the game will attempt to use elaborate techniques
to set access controls, on files, directories, shares, as well as in share definitions.
There is the ever present danger that that administrator's successor will not understand the
complex mess that has been inherited. Remember, apparent job security through complex design
and implementation may ultimately cause loss of operations and downtime to users as the new
administrator learns to untangle your web. Keep access controls simple and effective and
make sure that users will never be interrupted by the stupidity of complexity.
</para>
</sect3>

<sect3>
<title>Logon Scripts</title>

<para>
Please refer to the section of this document on Advanced Network Adminsitration for information
regarding the network logon script options for Samba-3. Logon scripts can help to ensure that
all users gain share and printer connections they need.
</para>

<para>
Logon scripts can be created on-the-fly so that all commands executed are specific to the
rights and privilidges granted to the user. The preferred controls should be affected through
group membership so that group information can be used to custom create a logong script using
the <parameter>root preexec</parameter> parameters to the <filename>NETLOGON</filename> share.
</para>

<para>
Some sites prefer to use a tool such as <command>kixstart</command> to establish a controlled
user environment. In any case you may wish to do a google search for logon script process controls.
In particular, you may wish to explore the use of the Microsoft knowledgebase article KB189105 that
deals with how to add printers without user intervention via the logon script process.
</para>
</sect3>

<sect3>
<title>Profile Migration/Creation</title>

<para>
User and Group Profiles may be migrated using the tools described in the section titled Desktop Profile
Management.
</para>

<para>
Profiles may also be managed using the Samba-3 tool <command>profiles</command>. This tool allows
the MS Windows NT style security identifiers (SIDs) that are stored inside the profile NTuser.DAT file
to be changed to the SID of the Samba-3 domain.
</para>
</sect3>

<sect3>
<title>User and Group Accounts</title>

<para>
It is possible to migrate all account settings from an MS Windows NT4 domain to Samba-3. Before
attempting to migrate user and group accounts it is STRONGLY advised to create in Samba-3 the
groups that are present on the MS Windows NT4 domain <emphasis>AND</emphasis> to connect these to
suitable Unix/Linux groups. Following this simple advice will mean that all user and group attributes
should migrate painlessly.
</para>
</sect3>

</sect2>

<sect2>
<title>Steps In Migration Process</title>

<para>
The approximate migration process is described below.
</para>

<itemizedlist>
<listitem><para>
You will have an NT4 PDC that has the users, groups, policies and profiles to be migrated
</para></listitem>

<listitem><para>
Samba-3 set up as a DC with netlogon share, profile share, etc.
</para></listitem>
</itemizedlist>

<procedure><title>The Account Migration Process</title>
	<step><para>Create a BDC account for the samba server using NT Server Manager</para>
		<substeps><step><para>Samba must NOT be running</para></step></substeps></step>

	<step>
		<para><userinput>rpcclient <replaceable>NT4PDC</replaceable> -U Administrator%<replaceable>passwd</replaceable></userinput></para>
		<substeps><step><para>lsaquery</para></step>
		 	  <step><para>Note the SID returned</para></step>
		</substeps>
	</step>

	<step><para><userinput>net getsid -S <replaceable>NT4PDC</replaceable> -w <replaceable>DOMNAME</replaceable> -U Administrator%<replaceable>passwd</replaceable></userinput></para>
		<substeps><step><para>Note the SID</para></step></substeps>
	</step>

	<step><para><userinput>net getlocalsid</userinput></para>
		<substeps>
		<step><para>Note the SID, now check that all three SIDS reported are the same!</para></step>
		</substeps>
	</step>

	<step><para><userinput>net rpc join -S <replaceable>NT4PDC</replaceable> -w <replaceable>DOMNAME</replaceable> -U Administrator%<replaceable>passwd</replaceable></userinput></para></step>

	<step><para><userinput>net rpc vampire -S <replaceable>NT4PDC</replaceable> -U administrator%<replaceable>passwd</replaceable></userinput></para></step>

	<step><para><userinput>pdbedit -L</userinput></para>
		<substeps><step><para>Note - did the users migrate?</para></step></substeps>
	</step>

	<step><para><userinput>initGrps.sh <replaceable>DOMNAME</replaceable></userinput></para></step>

	<step><para><userinput>net groupmap list</userinput></para>
		<substeps><step><para>Now check that all groups are recognised</para></step></substeps>
	</step>

	<step><para><userinput>net rpc campire -S <replaceable>NT4PDC</replaceable> -U administrator%<replaceable>passwd</replaceable></userinput></para></step>

	<step><para><userinput>pdbedit -Lv</userinput></para>
		<substeps><step>
			<para>Note - check that all group membership has been migrated</para>
		</step></substeps>
	</step>
</procedure>

<para>
Now it is time to migrate all the profiles, then migrate all policy files.
More later.
</para>

</sect2>
</sect1>

<sect1>
<title>Migration Options</title>

<para>
Based on feedback from many sites as well as from actual installation and maintenance
experience sites that wish to migrate from MS Windows NT4 Domain Control to a Samba
based solution fit into three basic categories.
</para>

<table frame="all"><title>The 3 Major Site Types</title>
<tgroup cols="2">
	<thead>
	<row><entry>Number of Users</entry><entry>Description</entry></row>
	</thead>
	<tbody>
	<row><entry>&lt; 50</entry><entry><para>Want simple conversion with NO pain</para></entry></row>
	<row><entry>50 - 250</entry><entry><para>Want new features, can manage some in-house complexity</para></entry></row>
	<row><entry>&gt; 250</entry><entry><para>Solution/Implementation MUST scale well, complex needs. Cross departmental decision process. Local expertise in most areas</para></entry></row>
	</tbody>
</tgroup>
</table>

<sect2>
<title>Planning for Success</title>

<para>
There are three basic choices for sites that intend to migrate from MS Windwows NT4
to Samba-3.
</para>

<itemizedlist>
	<listitem><para>
	Simple Conversion (total replacement)
	</para></listitem>

	<listitem><para>
	Upgraded Conversion (could be one of integration)
	</para></listitem>

	<listitem><para>
	Complete Redesign (completely new solution)
	</para></listitem>
</itemizedlist>

<para>
No matter what choice you make, the following rules will minimise down-stream problems:
</para>

<itemizedlist>
	<listitem><para>
	Take sufficient time
	</para></listitem>

	<listitem><para>
	Avoid Panic
	</para></listitem>

	<listitem><para>
	Test ALL assumptions
	</para></listitem>

	<listitem><para>
	Test full roll-out program, including workstation deployment
	</para></listitem>
</itemizedlist>

<table frame="top"><title>Nature of the Conversion Choices</title>
<tgroup cols="3">
	<thead>
	<row><entry>Simple</entry><entry>Upgraded</entry><entry>Redesign</entry></row>
	</thead>
	<tbody>
	<row>
	<entry><para>Make use of minimal OS specific features</para></entry>
	<entry><para>Translate NT4 features to new host OS features</para></entry>
	<entry><para>Decide:</para></entry>
	</row>
	<row>
	<entry><para>Suck all accounts from NT4 into Samba-3</para></entry>
	<entry><para>Copy and improve:</para></entry>
	<entry><para>Authentication Regime (database location and access)</para></entry>
	</row>
	<row>
	<entry><para>Make least number of operational changes</para></entry>
	<entry><para>Make progressive improvements</para></entry>
	<entry><para>Desktop Management Methods</para></entry>
	</row>
	<row>
	<entry><para>Take least amount of time to migrate</para></entry>
	<entry><para>Minimise user impact</para></entry>
	<entry><para>Better Control of Desktops / Users</para></entry>
	</row>
	<row>
	<entry><para>Live versus Isolated Conversion</para></entry>
	<entry><para>Maximise functionality</para></entry>
	<entry><para>Identify Needs for: Manageability, Scalability, Security, Availability</para></entry>
	</row>
	<row>
	<entry><para>Integrate Samba-3 then migrate while users are active, then Change of control (ie: swap out)</para></entry>
	<entry><para>Take advantage of lower maintenance opportunity</para></entry>
	<entry><para></para></entry>
	</row>
	</tbody>
</tgroup>
</table>
</sect2>

<sect2>
<title>Samba Implementation Choices</title>

<!-- FIXME: Either a better layout or more written-out text-->
<para><programlisting>
Authentication database back end
	Winbind (external Samba or NT4/200x server)
	Can use pam_mkhomedir.so to auto-create home dirs
	External server could use Active Directory or NT4 Domain

Database type
	smbpasswd, tdbsam, ldapsam, MySQLsam

Access Control Points
	On the Share itself (Use NT4 Server Manager)
	On the file system
	Unix permissions on files and directories
	Posix ACLs enablement in file system?
	Through Samba share parameters
		Not recommended - except as only resort

Policies (migrate or create new ones)
	Group Policy Editor (NT4)
	Watch out for Tattoo effect

User and Group Profiles
	Platform specific so use platform tool to change from a Local
	to a Roaming profile Can use new profiles tool to change SIDs
	(NTUser.DAT)

Logon Scripts (Know how they work)

User and Group mapping to Unix/Linux
	username map facility may be needed
	Use 'net groupmap' to connect NT4 groups to Unix groups
	Use pdbedit to set/change user configuration
NOTE:
If migrating to LDAP back end it may be easier to dump initial LDAP database
to LDIF, then edit, then reload into LDAP

	OS specific scripts / programs may be needed
		Add / delete Users
			Note OS limits on size of name (Linux 8 chars)
				NT4 up to 254 chars
		Add / delete machines
			Applied only to domain members (note up to 16 chars)
		Add / delete Groups
			Note OS limits on size and nature
				Linux limit is 16 char,
				no spaces and no upper case chars (groupadd)

Migration Tools
	Domain Control (NT4 Style)
	Profiles, Policies, Access Controls, Security

Migration Tools
	Samba: net, rpcclient, smbpasswd, pdbedit, profiles
	Windows: NT4 Domain User Manager, Server Manager (NEXUS)

Authentication
	New SAM back end (smbpasswd, tdbsam, ldapsam, mysqlsam)
</programlisting>
</para>

</sect2>

</sect1>

</chapter>