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Chapter 10. Integrating MS Windows networks with Samba

10.1. Agenda

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.

We will examine:

Name resolution in a pure Unix/Linux TCP/IP - environment -
Name resolution as used within MS Windows - networking -
How browsing functions and how to deploy stable - and dependable browsing using Samba -
MS Windows security options and how to - configure Samba for seemless integration -
Configuration of Samba as:

10.2. Name Resolution in a pure Unix/Linux world

The key configuration files covered in this section are:

/etc/hosts
/etc/resolv.conf
/etc/host.conf
/etc/nsswitch.conf

10.2.1. `/etc/hosts`

Contains a static list of IP Addresses and names. -eg:

	127.0.0.1	localhost localhost.localdomain
-	192.168.1.1	bigbox.caldera.com	bigbox	alias4box

The purpose of /etc/hosts is to provide a +Chapter 26. Integrating MS Windows networks with Samba

Chapter 26. Integrating MS Windows networks with Samba
Prev	Part III. Advanced Configuration	Next

Chapter 26. Integrating MS Windows networks with Samba

John H. Terpstra

Samba Team

<jht@samba.org>

(Jan 01 2001)

Table of Contents

Features and Benefits

Background Information

Name Resolution in a pure Unix/Linux world

/etc/hosts
/etc/resolv.conf
/etc/host.conf
/etc/nsswitch.conf

Name resolution as used within MS Windows networking

The NetBIOS Name Cache
The LMHOSTS file
HOSTS file
DNS Lookup
WINS Lookup

Common Errors

My Boomerang Won't Come Back
Very Slow Network Connections
Samba server name change problem

+This section deals with NetBIOS over TCP/IP name to IP address resolution. If +your MS Windows clients are NOT configured to use NetBIOS over TCP/IP then this +section does not apply to your installation. If your installation involves use of +NetBIOS over TCP/IP then this section may help you to resolve networking problems. +

Note

+ NetBIOS over TCP/IP has nothing to do with NetBEUI. NetBEUI is NetBIOS + over Logical Link Control (LLC). On modern networks it is highly advised + to NOT run NetBEUI at all. Note also that there is NO such thing as + NetBEUI over TCP/IP - the existence of such a protocol is a complete + and utter mis-apprehension. +

Features and Benefits

+Many MS Windows network administrators have never been exposed to basic TCP/IP +networking as it is implemented in a Unix/Linux operating system. Likewise, many Unix and +Linux adminsitrators have not been exposed to the intricacies of MS Windows TCP/IP based +networking (and may have no desire to be either). +

+This chapter gives a short introduction to the basics of how a name can be resolved to +it's IP address for each operating system environment. +

Background Information

+Since the introduction of MS Windows 2000 it is possible to run MS Windows networking +without the use of NetBIOS over TCP/IP. NetBIOS over TCP/IP uses UDP port 137 for NetBIOS +name resolution and uses TCP port 139 for NetBIOS session services. When NetBIOS over +TCP/IP is disabled on MS Windows 2000 and later clients then only TCP port 445 will be +used and UDP port 137 and TCP port 139 will not. +

Note

+When using Windows 2000 or later clients, if NetBIOS over TCP/IP is NOT disabled, then +the client will use UDP port 137 (NetBIOS Name Service, also known as the Windows Internet +Name Service or WINS), TCP port 139 AND TCP port 445 (for actual file and print traffic). +

+When NetBIOS over TCP/IP is disabled the use of DNS is essential. Most installations that +disable NetBIOS over TCP/IP today use MS Active Directory Service (ADS). ADS requires +Dynamic DNS with Service Resource Records (SRV RR) and with Incremental Zone Transfers (IXFR). +Use of DHCP with ADS is recommended as a further means of maintaining central control +over client workstation network configuration. +

Name Resolution in a pure Unix/Linux world

+The key configuration files covered in this section are: +

/etc/hosts
/etc/resolv.conf
/etc/host.conf
/etc/nsswitch.conf

`/etc/hosts`

+Contains a static list of IP Addresses and names. +eg: +

+	127.0.0.1	localhost localhost.localdomain
+	192.168.1.1	bigbox.caldera.com	bigbox	alias4box
+

+The purpose of /etc/hosts is to provide a name resolution mechanism so that uses do not need to remember -IP addresses.

Network packets that are sent over the physical network transport +IP addresses. +

+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

MAC Addresses use 48 bits (or 6 bytes) and are typically represented +numbers that are separated by a dot (or period). eg: 168.192.1.1. +

+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

Every network interfrace must have an MAC address. Associated with +40:8e:0a:12:34:56 +

+Every network interface 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 @@ -224,18 +65,15 @@ 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.

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 +this is the address that will be returned in the ARP reply. +

+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 -/etc/hosts is one such file.

When the IP address of the destination interface has been +/etc/hosts is one such file. +

+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 @@ -245,98 +83,41 @@ 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.

The /etc/hosts file is foundational to all +interface. +

+The /etc/hosts 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.

10.2.2. `/etc/resolv.conf`

This file tells the name resolution libraries:

The name of the domain to which the machine +becomes available. +

`/etc/resolv.conf`

+This file tells the name resolution libraries: +

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

10.2.3. `/etc/host.conf`

/etc/host.conf is the primary means by +

`/etc/host.conf`

+/etc/host.conf 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:

	order hosts,bind
-	multi on

then both addresses should be returned. Please refer to the -man page for host.conf for further details.

10.2.4. `/etc/nsswitch.conf`

This file controls the actual name resolution targets. The -file typically has resolver object specifications as follows:

	# /etc/nsswitch.conf
+which name resolution may procede. The typical structure is:
+
+	order hosts,bind
+	multi on
+

+then both addresses should be returned. Please refer to the 
+man page for host.conf for further details.
+

`/etc/nsswitch.conf`

+This file controls the actual name resolution targets. The +file typically has resolver object specifications as follows: +

+	# /etc/nsswitch.conf
 	#
 	# Name Service Switch configuration file.
 	#
@@ -355,99 +136,75 @@ CLASS="PROGRAMLISTING"
 	ethers:		nis files
 	protocols:	nis files
 	rpc:		nis files
-	services:	nis files

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

It should be noted that unless a network request/message must be + services: nis files +

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

+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.

Starting with version 2.2.0 samba has Linux support for extensions to +principal of speaking only when necessary. +

+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: make -nsswitch/libnss_wins.so). The resulting library should -then be installed in the /lib directory and -the "wins" parameter needs to be added to the "hosts:" line in -the /etc/nsswitch.conf file. At this point it +with appropriate arguments to the make command (ie: make +nsswitch/libnss_wins.so). The resulting library should +then be installed in the /lib directory and +the "wins" parameter needs to be added to the "hosts:" line in +the /etc/nsswitch.conf 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.

10.3. Name resolution as used within MS Windows networking

MS Windows networking is predicated about the name each machine +which both the samba machine and the MS Windows machine belong. +

Name resolution as used within MS Windows networking

+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 +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.

The following are typical NetBIOS name/service type registrations:

	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
+the client/server.
+

+The following are typical NetBIOS name/service type registrations:
+
+	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
It should be noted that all NetBIOS machines register their own 
+		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
+

+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.

One further point of clarification should be noted, the /etc/hosts +are associated with each IP address. +

+One further point of clarification should be noted, the /etc/hosts 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 +wants to locate a domain logon server. It finds 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 +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.

The name "workgroup" or "domain" really can be confusing since these +ever machine first replies then ends up providing the logon services. +

+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 +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 @@ -455,9 +212,9 @@ 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.

MS Windows networking is thus predetermined to use machine names +of a user name and a matching password. +

+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 @@ -466,60 +223,39 @@ 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.

MS Windows machines use a complex array of name resolution mechanisms. +NBT or NetBT, the NetBIOS over TCP/IP. +

+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.

10.3.1. The NetBIOS Name Cache

All MS Windows machines employ an in memory buffer in which is +limited to this area. +

The NetBIOS Name Cache

+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.

If a machine whose name is in the local name cache has been shut +configured name resolution mechanisms. +

+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.

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

10.3.2. The LMHOSTS file

This file is usually located in MS Windows NT 4.0 or -2000 in C:\WINNT\SYSTEM32\DRIVERS\ETC and contains +frustrating for users - but it is a characteristic of the protocol. +

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

The LMHOSTS file

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

It typically looks like:

	# Copyright (c) 1998 Microsoft Corp.
+LMHOSTS file performs NetBIOS name 
+to IP address mapping.
+

+It typically looks like:
+
+	# Copyright (c) 1998 Microsoft Corp.
 	#
 	# This is a sample LMHOSTS file used by the Microsoft Wins Client (NetBIOS
 	# over TCP/IP) stack for Windows98
@@ -528,7 +264,7 @@ CLASS="PROGRAMLISTING"
 	# (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
+	# 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).
 	#
@@ -542,28 +278,28 @@ CLASS="PROGRAMLISTING"
 	#      #END_ALTERNATE
 	#      \0xnn (non-printing character support)
 	#
-	# Following any entry in the file with the characters "#PRE" will cause
+	# 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:<domain>" tag will associate the
+	# Following an entry with the "#DOM:<domain>" tag will associate the
 	# entry with the domain specified by <domain>. 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 <domain> is always preloaded although it will not
 	# be shown when the name cache is viewed.
 	#
-	# Specifying "#INCLUDE <filename>" will force the RFC NetBIOS (NBT)
+	# Specifying "#INCLUDE <filename>" will force the RFC NetBIOS (NBT)
 	# software to seek the specified <filename> and parse it as if it were
 	# local. <filename> 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
+	# 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.
+	# 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
@@ -576,7 +312,7 @@ CLASS="PROGRAMLISTING"
 	# 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
+	# 102.54.94.102    "appname  \0x14"                    #special app server
 	# 102.54.94.123    popular            #PRE             #source server
 	# 102.54.94.117    localsrv           #PRE             #needed for the include
 	#
@@ -585,564 +321,107 @@ CLASS="PROGRAMLISTING"
 	# #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"
+	# 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.

10.3.3. HOSTS file

This file is usually located in MS Windows NT 4.0 or 2000 in -C:\WINNT\SYSTEM32\DRIVERS\ETC and contains + # end of this file. +

HOSTS file

+This file is usually located in MS Windows NT 4.0 or 2000 in +C:\WINNT\SYSTEM32\DRIVERS\ETC 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 /etc/hosts file.

10.3.4. DNS Lookup

This capability is configured in the TCP/IP setup area in the network +every way the equivalent of the Unix/Linux /etc/hosts file. +

DNS Lookup

+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 +is followed the precise nature of which is dependant 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.

10.3.5. WINS Lookup

A WINS (Windows Internet Name Server) service is the equivaent of the +lookup is used. +

WINS Lookup

+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.

To configure Samba to be a WINS server the following parameter needs -to be added to the smb.conf file:

	wins support = Yes

To configure Samba to use a WINS server the following parameters are -needed in the smb.conf file:

	wins support = No
-	wins server = xxx.xxx.xxx.xxx

where xxx.xxx.xxx.xxx is the IP address -of the WINS server.

10.4. How browsing functions and how to deploy stable and -dependable browsing using Samba

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.

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).

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.

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.

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.

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.

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, /etc/hosts, -and so on.

10.5. MS Windows security options and how to configure -Samba for seemless integration

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.

When encrypted passwords are used a password that has been -entered by the user is encrypted in two ways:

An MD4 hash of the UNICODE of the password - string. This is known as the NT hash. -
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. -

You should refer to the Password Encryption chapter in this HOWTO collection -for more details on the inner workings

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.

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.

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.

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.

	passsword level = integer
-	username level = integer

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 username level parameter -is rarely even needed.

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 password level must be set to the maximum -number of upper case letter which could appear -is a password. Note that is the server OS uses the traditional -DES version of crypt(), then a password level -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).

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:

10.5.1. Use MS Windows NT as an authentication server

This method involves the additions of the following parameters -in the smb.conf file:

	encrypt passwords = Yes
-	security = server
-	password server = "NetBIOS_name_of_PDC"

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.

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.

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.

10.5.2. Make Samba a member of an MS Windows NT security domain

This method involves additon of the following paramters in the smb.conf file:

	encrypt passwords = Yes
-	security = domain
-	workgroup = "name of NT domain"
-	password server = *

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.

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

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

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 /etc/passwd entry.

An alternative to assigning UIDs to Windows users on a -Samba member server is presented in the Winbind Overview chapter in -this HOWTO collection.

10.5.3. Configure Samba as an authentication server

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.

This method involves addition of the following parameters to -the smb.conf file:

## 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
+if the TCP/IP setup has been given at least one WINS Server IP Address.
+

+To configure Samba to be a WINS server the following parameter needs 
+to be added to the smb.conf file:
+
+	wins support = Yes
+

+To configure Samba to use a WINS server the following parameters are 
+needed in the smb.conf file:
+
+	wins support = No
+	wins server = xxx.xxx.xxx.xxx
+

+where xxx.xxx.xxx.xxx is the IP address 
+of the WINS server.
+

Common Errors

+TCP/IP network configuration problems find every network administrator sooner or later. +The cause can be anything from keybaord mishaps, forgetfulness, simple mistakes, and +carelessness. Of course, noone is every deliberately careless! +

My Boomerang Won't Come Back

+ Well, the real complaint said, "I can ping my samba server from Windows, but I can + not ping my Windows machine from the samba server." +

+ The Windows machine was at IP Address 192.168.1.2 with netmask 255.255.255.0, the + Samba server (Linux) was at IP Address 192.168.1.130 with netmast 255.255.255.128. + The machines were on a local network with no external connections. +

+ Due to inconsistent netmasks, the Windows machine was on network 192.168.1.0/24, while + the Samba server was on network 192.168.1.128/25 - logically a different network. +

Very Slow Network Connections

+ A common causes of slow network response includes: +

Client is configured to use DNS and DNS server is down
Client is configured to use remote DNS server, but remote connection is down
Client is configured to use a WINS server, but there is no WINS server
Client is NOT configured to use a WINS server, but there is a WINS server
Firewall is filtering our DNS or WINS traffic

Samba server name change problem

+ The name of the samba server was changed, samba was restarted, samba server can not be + pinged by new name from MS Windows NT4 Workstation, but it does still respond to ping using + the old name. Why? +

+ From this description three (3) things are rather obvious: +

WINS is NOT in use, only broadcast based name resolution is used
The samba server was renamed and restarted within the last 10-15 minutes
The old samba server name is still in the NetBIOS name cache on the MS Windows NT4 Workstation

+ To find what names are present in the NetBIOS name cache on the MS Windows NT4 machine, + open a cmd shell, then: +

+	C:\temp\>nbtstat -n
 
-[NETLOGON]
-	path = /somewhare/in/file/system
-	read only = yes

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.

10.5.3.1. Users

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.

	# useradd -s /bin/bash -d /home/"userid" -m "userid"
-	# passwd "userid"
-	  Enter Password: <pw>
-	  
-	# smbpasswd -a "userid"
-	  Enter Password: <pw>

10.5.3.2. MS Windows NT Machine Accounts

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

	# useradd -s /bin/false -d /dev/null "machine_name"\$
-	# passwd -l "machine_name"\$
-	# smbpasswd -a -m "machine_name"

10.6. Conclusions

Samba provides a flexible means to operate as...

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. -
An MS Windows NT 3.x/4.0 security domain member. -
An alternative to an MS Windows NT 3.x/4.0 - Domain Controller. -

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\ No newline at end of file + NetBIOS Local Name Table + + Name Type Status + ------------------------------------------------ + SLACK <03> UNIQUE Registered + ADMININSTRATOR <03> UNIQUE Registered + SLACK <00> UNIQUE Registered + SARDON <00> GROUP Registered + SLACK <20> UNIQUE Registered + SLACK <1F> UNIQUE Registered + + + C:\Temp\>nbtstat -c + + NetBIOS Remote Cache Name Table + + Name Type Host Address Life [sec] + -------------------------------------------------------------- + FRODO <20> UNIQUE 192.168.1.1 240 + + C:\Temp\> +

+ In the above example, FRODO is the Samba server and SLACK is the MS Windows NT4 Workstation. + The first listing shows the contents of the Local Name Table (ie: Identity information on + the MS Windows workstation), the second shows the NetBIOS name in the NetBIOS name cache. + The name cache contains the remote machines known to this workstation. +

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