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 @@ -9,7 +10,7 @@ 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 administrators have not been exposed to the intricacies of MS Windows TCP/IP based @@ -17,7 +18,7 @@ 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 @@ -33,10 +34,10 @@ 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`

-Contains a static list of IP Addresses and names. +

/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
@@ -48,7 +49,7 @@ 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 
+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.
 

@@ -92,7 +93,7 @@ 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 @@ -102,7 +103,7 @@ 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 @@ -113,7 +114,7 @@ which name resolution may proceed. The typical structure is:

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:

@@ -149,22 +150,22 @@ 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 
+with appropriate arguments to the make command (i.e.: 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 
+will be possible to ping any MS Windows machine by its 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`

+

`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 +or "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 +simple 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 @@ -199,8 +200,8 @@ 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 -IP address that is returned in the enumerated list of IP addresses. Which -ever machine first replies then ends up providing the logon services. +IP address that is returned in the enumerated list of IP addresses. +Whichever 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 @@ -228,7 +229,7 @@ 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`

+

`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 @@ -246,7 +247,7 @@ 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`

+

`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 @@ -331,25 +332,25 @@ 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`

+

`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`

+

`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 -Node Type parameter is configured to. A Node Type of 0 means use -NetBIOS broadcast (over UDP broadcast) is first used if the name +configuration facility. If enabled, an elaborate name resolution sequence +is followed the precise nature of which is dependant on how the NetBIOS +Node Type parameter is configured. A Node Type of 0 means that +NetBIOS broadcast (over UDP broadcast) is 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. -

`WINS Lookup`

+

`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 @@ -368,11 +369,11 @@ needed in the smb.conf file:

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

`Common Errors`

+

`Common Errors`

TCP/IP network configuration problems find every network administrator sooner or later. 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`

+

`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."

@@ -382,9 +383,9 @@ carelessness. Of course, no one is every deliberately careless!

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`

+

`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? @@ -393,8 +394,8 @@ carelessness. Of course, no one 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
@@ -418,10 +419,10 @@ carelessness. Of course, no one 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 first listing shows the contents of the Local Name Table (i.e.: 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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