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diff --git a/docs/docbook/projdoc/Integrating-with-Windows.xml b/docs/docbook/projdoc/Integrating-with-Windows.xml new file mode 100644 index 0000000000..9f0de0a56a --- /dev/null +++ b/docs/docbook/projdoc/Integrating-with-Windows.xml @@ -0,0 +1,545 @@ +<chapter id="integrate-ms-networks"> + +<chapterinfo> + &author.jht; + <pubdate> (Jan 01 2001) </pubdate> +</chapterinfo> + +<title>Integrating MS Windows networks with Samba</title> + +<para> +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. +</para> + +<note> +<para> + 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. +</para> +</note> + +<para> +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. +</para> + +<note> +<para> +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). +</para> +</note> + +<para> +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. +</para> + + +<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 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. +</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. +</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:<domain> + # #INCLUDE <filename> + # #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:<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) + # 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 + # 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 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. +</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 &smb.conf; 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> + +</chapter> |