samba-mirror/docs/docbook/projdoc/Integrating-with-Windows.sgml

<chapter id="integrate-ms-networks">
 
 
<chapterinfo>
        <author>
		<firstname>John</firstname><surname>Terpstra</surname>
                <affiliation>
                        <orgname>Samba Team</orgname>
			<address>
			<email>jht@samba.org</email>
			</address>
                </affiliation>
        </author>
 
 
        <pubdate> (Jan 01 2001) </pubdate>
</chapterinfo>
 
<title>Integrating MS Windows networks with Samba</title>
 
<sect1>
<title>Agenda</title>

<para>
To identify the key functional mechanisms of MS Windows networking 
to enable the deployment of Samba as a means of extending and/or 
replacing MS Windows NT/2000 technology.
</para>

<para>
We will examine:
</para>

<orderedlist>
	<listitem><para>Name resolution in a pure Unix/Linux TCP/IP 
	environment
	</para></listitem>

	<listitem><para>Name resolution as used within MS Windows 
	networking
	</para></listitem>

	<listitem><para>How browsing functions and how to deploy stable 
	and dependable browsing using Samba
	</para></listitem>
	
	<listitem><para>MS Windows security options and how to 
	configure Samba for seemless integration
	</para></listitem>

	<listitem><para>Configuration of Samba as:</para>
		<orderedlist>
		<listitem><para>A stand-alone server</para></listitem>
		<listitem><para>An MS Windows NT 3.x/4.0 security domain member
		</para></listitem>
		<listitem><para>An alternative to an MS Windows NT 3.x/4.0 Domain Controller
		</para></listitem>
		</orderedlist>
	</listitem>
</orderedlist>

</sect1>


<sect1>
<title>Name Resolution in a pure Unix/Linux world</title>

<para>
The key configuration files covered in this section are:
</para>

<itemizedlist>
	<listitem><para><filename>/etc/hosts</filename></para></listitem>
	<listitem><para><filename>/etc/resolv.conf</filename></para></listitem>
	<listitem><para><filename>/etc/host.conf</filename></para></listitem>
	<listitem><para><filename>/etc/nsswitch.conf</filename></para></listitem>
</itemizedlist>

<sect2>
<title><filename>/etc/hosts</filename></title>

<para>
Contains a static list of IP Addresses and names.
eg:
</para>
<para><programlisting>
	127.0.0.1	localhost localhost.localdomain
	192.168.1.1	bigbox.caldera.com	bigbox	alias4box
</programlisting></para>

<para>
The purpose of <filename>/etc/hosts</filename> is to provide a 
name resolution mechanism so that uses do not need to remember 
IP addresses.
</para>


<para>
Network packets that are sent over the physical network transport 
layer communicate not via IP addresses but rather using the Media 
Access Control address, or MAC address. IP Addresses are currently 
32 bits in length and are typically presented as four (4) decimal 
numbers that are separated by a dot (or period). eg: 168.192.1.1
</para>

<para>
MAC Addresses use 48 bits (or 6 bytes) and are typically represented 
as two digit hexadecimal numbers separated by colons. eg: 
40:8e:0a:12:34:56
</para>

<para>
Every network interfrace must have an MAC address. Associated with 
a MAC address there may be one or more IP addresses. There is NO 
relationship between an IP address and a MAC address, all such assignments 
are arbitary or discretionary in nature. At the most basic level all 
network communications takes place using MAC addressing. Since MAC 
addresses must be globally unique, and generally remains fixed for 
any particular interface, the assignment of an IP address makes sense 
from a network management perspective. More than one IP address can 
be assigned per MAC address. One address must be the primary IP address, 
this is the address that will be returned in the ARP reply.
</para>

<para>
When a user or a process wants to communicate with another machine 
the protocol implementation ensures that the "machine name" or "host 
name" is resolved to an IP address in a manner that is controlled 
by the TCP/IP configuration control files. The file 
<filename>/etc/hosts</filename> is one such file.
</para>

<para>
When the IP address of the destination interface has been 
determined a protocol called ARP/RARP is used to identify 
the MAC address of the target interface. ARP stands for Address 
Resolution Protocol, and is a broadcast oriented method that 
uses UDP (User Datagram Protocol) to send a request to all 
interfaces on the local network segment using the all 1's MAC 
address. Network interfaces are programmed to respond to two 
MAC addresses only; their own unique address and the address 
ff:ff:ff:ff:ff:ff. The reply packet from an ARP request will 
contain the MAC address and the primary IP address for each 
interface.
</para>

<para>
The <filename>/etc/hosts</filename> file is foundational to all 
Unix/Linux TCP/IP installations and as a minumum will contain 
the localhost and local network interface IP addresses and the 
primary names by which they are known within the local machine. 
This file helps to prime the pump so that a basic level of name 
resolution can exist before any other method of name resolution 
becomes available.
</para>

</sect2>


<sect2>
<title><filename>/etc/resolv.conf</filename></title>

<para>
This file tells the name resolution libraries:
</para>

<itemizedlist>
	<listitem><para>The name of the domain to which the machine 
	belongs
	</para></listitem>
	
	<listitem><para>The name(s) of any domains that should be 
	automatically searched when trying to resolve unqualified 
	host names to their IP address
	</para></listitem>
	
	<listitem><para>The name or IP address of available Domain 
	Name Servers that may be asked to perform name to address 
	translation lookups
	</para></listitem>
</itemizedlist>

</sect2>


<sect2>
<title><filename>/etc/host.conf</filename></title>


<para>
<filename>/etc/host.conf</filename> is the primary means by 
which the setting in /etc/resolv.conf may be affected. It is a 
critical configuration file.  This file controls the order by 
which name resolution may procede. The typical structure is:
</para>

<para><programlisting>
	order hosts,bind
	multi on
</programlisting></para>

<para>
then both addresses should be returned. Please refer to the 
man page for host.conf for further details.
</para>


</sect2>



<sect2>
<title><filename>/etc/nsswitch.conf</filename></title>

<para>
This file controls the actual name resolution targets. The 
file typically has resolver object specifications as follows:
</para>


<para><programlisting>
	# /etc/nsswitch.conf
	#
	# Name Service Switch configuration file.
	#

	passwd:		compat
	# Alternative entries for password authentication are:
	# passwd:	compat files nis ldap winbind
	shadow:		compat
	group:		compat

	hosts:		files nis dns
	# Alternative entries for host name resolution are:
	# hosts:	files dns nis nis+ hesoid db compat ldap wins
	networks:	nis files dns

	ethers:		nis files
	protocols:	nis files
	rpc:		nis files
	services:	nis files
</programlisting></para>

<para>
Of course, each of these mechanisms requires that the appropriate 
facilities and/or services are correctly configured.
</para>

<para>
It should be noted that unless a network request/message must be 
sent, TCP/IP networks are silent. All TCP/IP communications assumes a 
principal of speaking only when necessary.
</para>

<para>
Starting with version 2.2.0 samba has Linux support for extensions to 
the name service switch infrastructure so that linux clients will 
be able to obtain resolution of MS Windows NetBIOS names to IP 
Addresses. To gain this functionality Samba needs to be compiled 
with appropriate arguments to the make command (ie: <command>make 
nsswitch/libnss_wins.so</command>). The resulting library should 
then be installed in the <filename>/lib</filename> directory and 
the "wins" parameter needs to be added to the "hosts:" line in 
the <filename>/etc/nsswitch.conf</filename> file. At this point it 
will be possible to ping any MS Windows machine by it's NetBIOS 
machine name, so long as that machine is within the workgroup to 
which both the samba machine and the MS Windows machine belong.
</para>

</sect2>
</sect1>


<sect1>
<title>Name resolution as used within MS Windows networking</title>

<para>
MS Windows networking is predicated about the name each machine 
is given. This name is known variously (and inconsistently) as 
the "computer name", "machine name", "networking name", "netbios name", 
"SMB name". All terms mean the same thing with the exception of 
"netbios name" which can apply also to the name of the workgroup or the 
domain name. The terms "workgroup" and "domain" are really just a 
simply name with which the machine is associated. All NetBIOS names 
are exactly 16 characters in length. The 16th character is reserved. 
It is used to store a one byte value that indicates service level 
information for the NetBIOS name that is registered. A NetBIOS machine 
name is therefore registered for each service type that is provided by 
the client/server.
</para>

<para>
The following are typical NetBIOS name/service type registrations:
</para>

<para><programlisting>
	Unique NetBIOS Names:
		MACHINENAME<00>	= Server Service is running on MACHINENAME
		MACHINENAME<03> = Generic Machine Name (NetBIOS name)
		MACHINENAME<20> = LanMan Server service is running on MACHINENAME
		WORKGROUP<1b> = Domain Master Browser

	Group Names:
		WORKGROUP<03> = Generic Name registered by all members of WORKGROUP
		WORKGROUP<1c> = Domain Controllers / Netlogon Servers
		WORKGROUP<1d> = Local Master Browsers
		WORKGROUP<1e> = Internet Name Resolvers
</programlisting></para>

<para>
It should be noted that all NetBIOS machines register their own 
names as per the above. This is in vast contrast to TCP/IP 
installations where traditionally the system administrator will 
determine in the /etc/hosts or in the DNS database what names 
are associated with each IP address.
</para>

<para>
One further point of clarification should be noted, the <filename>/etc/hosts</filename> 
file and the DNS records do not provide the NetBIOS name type information 
that MS Windows clients depend on to locate the type of service that may 
be needed. An example of this is what happens when an MS Windows client 
wants to locate a domain logon server. It find this service and the IP 
address of a server that provides it by performing a lookup (via a 
NetBIOS broadcast) for enumeration of all machines that have 
registered the name type *<1c>. A logon request is then sent to each 
IP address that is returned in the enumerated list of IP addresses. Which 
ever machine first replies then ends up providing the logon services.
</para>

<para>
The name "workgroup" or "domain" really can be confusing since these 
have the added significance of indicating what is the security 
architecture of the MS Windows network. The term "workgroup" indicates 
that the primary nature of the network environment is that of a 
peer-to-peer design. In a WORKGROUP all machines are responsible for 
their own security, and generally such security is limited to use of 
just a password (known as SHARE MODE security). In most situations 
with peer-to-peer networking the users who control their own machines 
will simply opt to have no security at all. It is possible to have 
USER MODE security in a WORKGROUP environment, thus requiring use 
of a user name and a matching password.
</para>

<para>
MS Windows networking is thus predetermined to use machine names 
for all local and remote machine message passing. The protocol used is 
called Server Message Block (SMB) and this is implemented using 
the NetBIOS protocol (Network Basic Input Output System). NetBIOS can 
be encapsulated using LLC (Logical Link Control) protocol - in which case 
the resulting protocol is called NetBEUI (Network Basic Extended User 
Interface). NetBIOS can also be run over IPX (Internetworking Packet 
Exchange) protocol as used by Novell NetWare, and it can be run 
over TCP/IP protocols - in which case the resulting protocol is called 
NBT or NetBT, the NetBIOS over TCP/IP.
</para>

<para>
MS Windows machines use a complex array of name resolution mechanisms. 
Since we are primarily concerned with TCP/IP this demonstration is 
limited to this area.
</para>

<sect2>
<title>The NetBIOS Name Cache</title>

<para>
All MS Windows machines employ an in memory buffer in which is 
stored the NetBIOS names and IP addresses for all external 
machines that that machine has communicated with over the 
past 10-15 minutes. It is more efficient to obtain an IP address 
for a machine from the local cache than it is to go through all the 
configured name resolution mechanisms.
</para>

<para>
If a machine whose name is in the local name cache has been shut 
down before the name had been expired and flushed from the cache, then 
an attempt to exchange a message with that machine will be subject 
to time-out delays. i.e.: Its name is in the cache, so a name resolution 
lookup will succeed, but the machine can not respond. This can be 
frustrating for users - but it is a characteristic of the protocol.
</para>

<para>
The MS Windows utility that allows examination of the NetBIOS 
name cache is called "nbtstat". The Samba equivalent of this 
is called "nmblookup".
</para>

</sect2>

<sect2>
<title>The LMHOSTS file</title>

<para>
This file is usually located in MS Windows NT 4.0 or 
2000 in <filename>C:\WINNT\SYSTEM32\DRIVERS\ETC</filename> and contains 
the IP Address and the machine name in matched pairs. The 
<filename>LMHOSTS</filename> file performs NetBIOS name 
to IP address mapping oriented.
</para>

<para>
It typically looks like:
</para>

<para><programlisting>
	# Copyright (c) 1998 Microsoft Corp.
	#
	# This is a sample LMHOSTS file used by the Microsoft Wins Client (NetBIOS
	# over TCP/IP) stack for Windows98
	#
	# This file contains the mappings of IP addresses to NT computernames
	# (NetBIOS) names.  Each entry should be kept on an individual line.
	# The IP address should be placed in the first column followed by the
	# corresponding computername. The address and the comptername
	# should be separated by at least one space or tab. The "#" character
	# is generally used to denote the start of a comment (see the exceptions
	# below).
	#
	# This file is compatible with Microsoft LAN Manager 2.x TCP/IP lmhosts
	# files and offers the following extensions:
	#
	#      #PRE
	#      #DOM:&lt;domain&gt;
	#      #INCLUDE &lt;filename&gt;
	#      #BEGIN_ALTERNATE
	#      #END_ALTERNATE
	#      \0xnn (non-printing character support)
	#
	# Following any entry in the file with the characters "#PRE" will cause
	# the entry to be preloaded into the name cache. By default, entries are
	# not preloaded, but are parsed only after dynamic name resolution fails.
	#
	# Following an entry with the "#DOM:&lt;domain&gt;" tag will associate the
	# entry with the domain specified by &lt;domain&gt;. This affects how the
	# browser and logon services behave in TCP/IP environments. To preload
	# the host name associated with #DOM entry, it is necessary to also add a
	# #PRE to the line. The &lt;domain&gt; is always preloaded although it will not
	# be shown when the name cache is viewed.
	#
	# Specifying "#INCLUDE &lt;filename&gt;" will force the RFC NetBIOS (NBT)
	# software to seek the specified &lt;filename&gt; and parse it as if it were
	# local. &lt;filename&gt; is generally a UNC-based name, allowing a
	# centralized lmhosts file to be maintained on a server.
	# It is ALWAYS necessary to provide a mapping for the IP address of the
	# server prior to the #INCLUDE. This mapping must use the #PRE directive.
	# In addtion the share "public" in the example below must be in the
	# LanManServer list of "NullSessionShares" in order for client machines to
	# be able to read the lmhosts file successfully. This key is under
	# \machine\system\currentcontrolset\services\lanmanserver\parameters\nullsessionshares
	# in the registry. Simply add "public" to the list found there.
	#
	# The #BEGIN_ and #END_ALTERNATE keywords allow multiple #INCLUDE
	# statements to be grouped together. Any single successful include
	# will cause the group to succeed.
	#
	# Finally, non-printing characters can be embedded in mappings by
	# first surrounding the NetBIOS name in quotations, then using the
	# \0xnn notation to specify a hex value for a non-printing character.
	#
	# The following example illustrates all of these extensions:
	#
	# 102.54.94.97     rhino         #PRE #DOM:networking  #net group's DC
	# 102.54.94.102    "appname  \0x14"                    #special app server
	# 102.54.94.123    popular            #PRE             #source server
	# 102.54.94.117    localsrv           #PRE             #needed for the include
	#
	# #BEGIN_ALTERNATE
	# #INCLUDE \\localsrv\public\lmhosts
	# #INCLUDE \\rhino\public\lmhosts
	# #END_ALTERNATE
	#
	# In the above example, the "appname" server contains a special
	# character in its name, the "popular" and "localsrv" server names are
	# preloaded, and the "rhino" server name is specified so it can be used
	# to later #INCLUDE a centrally maintained lmhosts file if the "localsrv"
	# system is unavailable.
	#
	# Note that the whole file is parsed including comments on each lookup,
	# so keeping the number of comments to a minimum will improve performance.
	# Therefore it is not advisable to simply add lmhosts file entries onto the
	# end of this file.
</programlisting></para>

</sect2>

<sect2>
<title>HOSTS file</title>

<para>
This file is usually located in MS Windows NT 4.0 or 2000 in 
<filename>C:\WINNT\SYSTEM32\DRIVERS\ETC</filename> and contains 
the IP Address and the IP hostname in matched pairs. It can be 
used by the name resolution infrastructure in MS Windows, depending 
on how the TCP/IP environment is configured. This file is in 
every way the equivalent of the Unix/Linux <filename>/etc/hosts</filename> file.
</para>
</sect2>


<sect2>
<title>DNS Lookup</title>

<para>
This capability is configured in the TCP/IP setup area in the network 
configuration facility. If enabled an elaborate name resolution sequence 
is followed the precise nature of which isdependant on what the NetBIOS 
Node Type parameter is configured to. A Node Type of 0 means use 
NetBIOS broadcast (over UDP broadcast) is first used if the name 
that is the subject of a name lookup is not found in the NetBIOS name 
cache. If that fails then DNS, HOSTS and LMHOSTS are checked. If set to 
Node Type 8, then a NetBIOS Unicast (over UDP Unicast) is sent to the 
WINS Server to obtain a lookup before DNS, HOSTS, LMHOSTS, or broadcast 
lookup is used.
</para>

</sect2>

<sect2>
<title>WINS Lookup</title>

<para>
A WINS (Windows Internet Name Server) service is the equivaent of the 
rfc1001/1002 specified NBNS (NetBIOS Name Server). A WINS server stores 
the names and IP addresses that are registered by a Windows client 
if the TCP/IP setup has been given at least one WINS Server IP Address.
</para>

<para>
To configure Samba to be a WINS server the following parameter needs 
to be added to the <filename>smb.conf</filename> file:
</para>

<para><programlisting>
	wins support = Yes
</programlisting></para>

<para>
To configure Samba to use a WINS server the following parameters are 
needed in the smb.conf file:
</para>

<para><programlisting>
	wins support = No
	wins server = xxx.xxx.xxx.xxx
</programlisting></para>

<para>
where <replaceable>xxx.xxx.xxx.xxx</replaceable> is the IP address 
of the WINS server.
</para>

</sect2>
</sect1>


<sect1>
<title>How browsing functions and how to deploy stable and 
dependable browsing using Samba</title>


<para>
As stated above, MS Windows machines register their NetBIOS names 
(i.e.: the machine name for each service type in operation) on start 
up. Also, as stated above, the exact method by which this name registration 
takes place is determined by whether or not the MS Windows client/server 
has been given a WINS server address, whether or not LMHOSTS lookup 
is enabled, or if DNS for NetBIOS name resolution is enabled, etc.
</para>

<para>
In the case where there is no WINS server all name registrations as 
well as name lookups are done by UDP broadcast. This isolates name 
resolution to the local subnet, unless LMHOSTS is used to list all 
names and IP addresses. In such situations Samba provides a means by 
which the samba server name may be forcibly injected into the browse 
list of a remote MS Windows network (using the "remote announce" parameter).
</para>

<para>
Where a WINS server is used, the MS Windows client will use UDP 
unicast to register with the WINS server. Such packets can be routed 
and thus WINS allows name resolution to function across routed networks.
</para>

<para>
During the startup process an election will take place to create a 
local master browser if one does not already exist. On each NetBIOS network 
one machine will be elected to function as the domain master browser. This 
domain browsing has nothing to do with MS security domain control. 
Instead, the domain master browser serves the role of contacting each local 
master browser (found by asking WINS or from LMHOSTS) and exchanging browse 
list contents. This way every master browser will eventually obtain a complete 
list of all machines that are on the network. Every 11-15 minutes an election 
is held to determine which machine will be the master browser. By the nature of 
the election criteria used, the machine with the highest uptime, or the 
most senior protocol version, or other criteria, will win the election 
as domain master browser.
</para>

<para>
Clients wishing to browse the network make use of this list, but also depend 
on the availability of correct name resolution to the respective IP 
address/addresses. 
</para>

<para>
Any configuration that breaks name resolution and/or browsing intrinsics 
will annoy users because they will have to put up with protracted 
inability to use the network services.
</para>

<para>
Samba supports a feature that allows forced synchonisation 
of browse lists across routed networks using the "remote 
browse sync" parameter in the smb.conf file. This causes Samba 
to contact the local master browser on a remote network and 
to request browse list synchronisation. This effectively bridges 
two networks that are separated by routers. The two remote 
networks may use either broadcast based name resolution or WINS 
based name resolution, but it should be noted that the "remote 
browse sync" parameter provides browse list synchronisation - and 
that is distinct from name to address resolution, in other 
words, for cross subnet browsing to function correctly it is 
essential that a name to address resolution mechanism be provided. 
This mechanism could be via DNS, <filename>/etc/hosts</filename>, 
and so on.
</para>

</sect1>

<sect1>
<title>MS Windows security options and how to configure 
Samba for seemless integration</title>

<para>
MS Windows clients may use encrypted passwords as part of a 
challenege/response authentication model (a.k.a. NTLMv1) or 
alone, or clear text strings for simple password based 
authentication. It should be realized that with the SMB 
protocol the password is passed over the network either 
in plain text or encrypted, but not both in the same 
authentication requets.
</para>

<para>
When encrypted passwords are used a password that has been 
entered by the user is encrypted in two ways:
</para>

<itemizedlist>
	<listitem><para>An MD4 hash of the UNICODE of the password
	string.  This is known as the NT hash.
	</para></listitem>

	<listitem><para>The password is converted to upper case,
	and then padded or trucated to 14 bytes.  This string is 
	then appended with 5 bytes of NULL characters and split to
	form two 56 bit DES keys to encrypt a "magic" 8 byte value.
	The resulting 16 bytes for the LanMan hash.
	</para></listitem>	
</itemizedlist>

<para>
You should refer to the <ulink url="ENCRYPTION.html">
Password Encryption</ulink> chapter in this HOWTO collection
for more details on the inner workings
</para>

<para>
MS Windows 95 pre-service pack 1, MS Windows NT versions 3.x 
and version 4.0 pre-service pack 3 will use either mode of 
password authentication. All versions of MS Windows that follow 
these versions no longer support plain text passwords by default.
</para>

<para>
MS Windows clients have a habit of dropping network mappings that 
have been idle for 10 minutes or longer. When the user attempts to 
use the mapped drive connection that has been dropped, the client
re-establishes the connection using 
a cached copy of the password.
</para>

<para>
When Microsoft changed the default password mode, they dropped support for 
caching of the plain text password. This means that when the registry 
parameter is changed to re-enable use of plain text passwords it appears to 
work, but when a dropped mapping attempts to revalidate it will fail if 
the remote authentication server does not support encrypted passwords. 
This means that it is definitely not a good idea to re-enable plain text 
password support in such clients.
</para>

<para>
The following parameters can be used to work around the 
issue of Windows 9x client upper casing usernames and
password before transmitting them to the SMB server
when using clear text authentication.
</para>

<para><programlisting>
	<ulink url="smb.conf.5.html#PASSWORDLEVEL">passsword level</ulink> = <replaceable>integer</replaceable>
	<ulink url="smb.conf.5.html#USERNAMELEVEL">username level</ulink> = <replaceable>integer</replaceable>
</programlisting></para>

<para>
By default Samba will lower case the username before attempting
to lookup the user in the database of local system accounts.
Because UNIX usernames conventionally only contain lower case
character, the <parameter>username level</parameter> parameter
is rarely even needed.
</para>

<para>
However, password on UNIX systems often make use of mixed case
characters.  This means that in order for a user on a Windows 9x
client to connect to a Samba server using clear text authentication,
the <parameter>password level</parameter> must be set to the maximum
number of upper case letter which <emphasis>could</emphasis> appear
is a password.  Note that is the server OS uses the traditional
DES version of crypt(), then a <parameter>password level</parameter>
of 8 will result in case insensitive passwords as seen from Windows
users.  This will also result in longer login times as Samba
hash to compute the permutations of the password string and 
try them one by one until a match is located (or all combinations fail).
</para>

<para>
The best option to adopt is to enable support for encrypted passwords 
where ever Samba is used. There are three configuration possibilities 
for support of encrypted passwords:
</para>


<sect2>
<title>Use MS Windows NT as an authentication server</title>

<para>
This method involves the additions of the following parameters 
in the smb.conf file:
</para>

<para><programlisting>
	encrypt passwords = Yes
	security = server
	password server = "NetBIOS_name_of_PDC"
</programlisting></para>


<para>
There are two ways of identifying whether or not a username and 
password pair was valid or not. One uses the reply information provided 
as part of the authentication messaging process, the other uses 
just and error code.
</para>

<para>
The down-side of this mode of configuration is the fact that 
for security reasons Samba will send the password server a bogus 
username and a bogus password and if the remote server fails to 
reject the username and password pair then an alternative mode 
of identification of validation is used. Where a site uses password 
lock out after a certain number of failed authentication attempts 
this will result in user lockouts.
</para>

<para>
Use of this mode of authentication does require there to be 
a standard Unix account for the user, this account can be blocked 
to prevent logons by other than MS Windows clients.
</para>

</sect2>

<sect2>
<title>Make Samba a member of an MS Windows NT security domain</title>

<para>
This method involves additon of the following paramters in the smb.conf file:
</para>

<para><programlisting>
	encrypt passwords = Yes
	security = domain
	workgroup = "name of NT domain"
	password server = *
</programlisting></para>

<para>
The use of the "*" argument to "password server" will cause samba 
to locate the domain controller in a way analogous to the way 
this is done within MS Windows NT.
</para>

<para>
In order for this method to work the Samba server needs to join the 
MS Windows NT security domain. This is done as follows:
</para>

<itemizedlist>
	<listitem><para>On the MS Windows NT domain controller using 
	the Server Manager add a machine account for the Samba server.
	</para></listitem>
	
	<listitem><para>Next, on the Linux system execute: 
	<command>smbpasswd -r PDC_NAME -j DOMAIN_NAME</command>
	</para></listitem>
</itemizedlist>

<para>
Use of this mode of authentication does require there to be 
a standard Unix account for the user in order to assign
a uid once the account has been authenticated by the remote
Windows DC.  This account can be blocked to prevent logons by 
other than MS Windows clients by things such as setting an invalid
shell in the <filename>/etc/passwd</filename> entry.
</para>

<para>
An alternative to assigning UIDs to Windows users on a 
Samba member server is presented in the <ulink
url="winbind.html">Winbind Overview</ulink> chapter in
this HOWTO collection.
</para>


</sect2>


<sect2>
<title>Configure Samba as an authentication server</title>

<para>
This mode of authentication demands that there be on the 
Unix/Linux system both a Unix style account as well as an 
smbpasswd entry for the user. The Unix system account can be 
locked if required as only the encrypted password will be 
used for SMB client authentication.
</para>

<para>
This method involves addition of the following parameters to 
the smb.conf file:
</para>

<para><programlisting>
## please refer to the Samba PDC HOWTO chapter later in 
## this collection for more details
[global]
	encrypt passwords = Yes
	security = user
	domain logons = Yes
	; an OS level of 33 or more is recommended
	os level = 33

[NETLOGON]
	path = /somewhare/in/file/system
	read only = yes
</programlisting></para>

<para>
in order for this method to work a Unix system account needs 
to be created for each user, as well as for each MS Windows NT/2000 
machine. The following structure is required.
</para>

<sect3>
<title>Users</title>

<para>
A user account that may provide a home directory should be 
created. The following Linux system commands are typical of 
the procedure for creating an account.
</para>

<para><programlisting>
	# useradd -s /bin/bash -d /home/"userid" -m "userid"
	# passwd "userid"
	  Enter Password: &lt;pw&gt;
	  
	# smbpasswd -a "userid"
	  Enter Password: &lt;pw&gt;
</programlisting></para>
</sect3>

<sect3>
<title>MS Windows NT Machine Accounts</title>

<para>
These are required only when Samba is used as a domain 
controller.  Refer to the Samba-PDC-HOWTO for more details.
</para>

<para><programlisting>
	# useradd -s /bin/false -d /dev/null "machine_name"\$
	# passwd -l "machine_name"\$
	# smbpasswd -a -m "machine_name"
</programlisting></para>
</sect3>
</sect2>
</sect1>


<sect1>
<title>Conclusions</title>

<para>
Samba provides a flexible means to operate as...
</para>

<itemizedlist>
	<listitem><para>A Stand-alone server - No special action is needed 
	other than to create user accounts. Stand-alone servers do NOT 
	provide network logon services, meaning that machines that use this 
	server do NOT perform a domain logon but instead make use only of 
	the MS Windows logon which is local to the MS Windows 
	workstation/server.
	</para></listitem>
	
	<listitem><para>An MS Windows NT 3.x/4.0 security domain member.
	</para></listitem>
	

	<listitem><para>An alternative to an MS Windows NT 3.x/4.0 
	Domain Controller.
	</para></listitem>

</itemizedlist>

</sect1>

</chapter>