Chapter 26. Integrating MS Windows networks with Samba

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 @@ -10,15 +9,15 @@ NetBIOS over TCP/IP then this section may help you to resolve networking problem 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 +Linux administrators 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 @@ -34,9 +33,9 @@ disable NetBIOS over TCP/IP today use MS Active Directory Service (ADS). ADS req 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`

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

`/etc/hosts`

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

@@ -60,7 +59,7 @@ as two digit hexadecimal numbers separated by colons. eg:
 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 
+are arbitrary 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 
@@ -87,13 +86,13 @@ contain the MAC address and the primary IP address for each
 interface.
 

 The /etc/hosts file is foundational to all 
-Unix/Linux TCP/IP installations and as a minumum will contain 
+Unix/Linux TCP/IP installations and as a minimum 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.
-

`/etc/resolv.conf`

This file tells the name resolution libraries:

The name of the domain to which the machine belongs @@ -103,18 +102,18 @@ This file tells the name resolution libraries:
The name or IP address of available Domain Name Servers that may be asked to perform name to address translation lookups -

`/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: +which name resolution may proceed. 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:

@@ -131,7 +130,7 @@ file typically has resolver object specifications as follows:
 
 	hosts:		files nis dns
 	# Alternative entries for host name resolution are:
-	# hosts:	files dns nis nis+ hesoid db compat ldap wins
+	# hosts:	files dns nis nis+ hesiod db compat ldap wins
 	networks:	nis files dns
 
 	ethers:		nis files
@@ -158,7 +157,7 @@ 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.
-

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", @@ -229,7 +228,7 @@ 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. -

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 @@ -247,7 +246,7 @@ 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 @@ -264,7 +263,7 @@ It typically looks like: # 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 + # corresponding computername. The address and the computername # 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). @@ -296,7 +295,7 @@ It typically looks like: # 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 + # In addition 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 @@ -332,14 +331,14 @@ It typically looks like: # 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. -

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. -

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 is dependant on what the NetBIOS @@ -350,8 +349,8 @@ 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. -

WINS Lookup

-A WINS (Windows Internet Name Server) service is the equivaent of the +

WINS Lookup

+A WINS (Windows Internet Name Server) service is the equivalent 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. @@ -369,23 +368,23 @@ needed in the smb.conf file:

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

+The cause can be anything from keyboard mishaps, forgetfulness, simple mistakes, and +carelessness. Of course, no one 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. + Samba server (Linux) was at IP Address 192.168.1.130 with netmask 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

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? @@ -394,8 +393,8 @@ carelessness. Of course, noone is every deliberately careless!

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
 
 	              NetBIOS Local Name Table
@@ -403,7 +402,7 @@ carelessness. Of course, noone is every deliberately careless!
 	   Name                 Type          Status
 	------------------------------------------------
 	SLACK            <03>  UNIQUE      Registered
-	ADMININSTRATOR   <03>  UNIQUE      Registered
+	ADMINISTRATOR    <03>  UNIQUE      Registered
 	SLACK            <00>  UNIQUE      Registered
 	SARDON           <00>  GROUP       Registered
 	SLACK            <20>  UNIQUE      Registered
@@ -419,8 +418,8 @@ carelessness. Of course, noone is every deliberately careless!
 	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. -- cgit