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| author | Gerald Carter <jerry@samba.org> | 2002-10-02 14:08:40 +0000 |
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| committer | Gerald Carter <jerry@samba.org> | 2002-10-02 14:08:40 +0000 |
| commit | 53b16591832dc07e9e15a9078f08a899503bbaa6 (patch) | |
| tree | f4f7d49b37c6289f94235a0056bd7aa0a3a23522 /docs/htmldocs/integrate-ms-networks.html | |
| parent | eb17f95e164520e0e5b0c665ad1ffc8323c7293f (diff) | |
| download | samba-53b16591832dc07e9e15a9078f08a899503bbaa6.tar.gz samba-53b16591832dc07e9e15a9078f08a899503bbaa6.tar.bz2 samba-53b16591832dc07e9e15a9078f08a899503bbaa6.zip | |
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diff --git a/docs/htmldocs/integrate-ms-networks.html b/docs/htmldocs/integrate-ms-networks.html new file mode 100644 index 0000000000..5d2d759817 --- /dev/null +++ b/docs/htmldocs/integrate-ms-networks.html @@ -0,0 +1,1143 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> +<HTML +><HEAD +><TITLE +>Integrating MS Windows networks with Samba</TITLE +><META +NAME="GENERATOR" +CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ +"><LINK +REL="HOME" +TITLE="SAMBA Project Documentation" +HREF="Samba-HOWTO.html"><LINK +REL="PREVIOUS" +TITLE="Diagnosing your samba server" +HREF="diagnosis.html"><LINK +REL="NEXT" +TITLE="Configuring PAM for distributed but centrally +managed authentication" +HREF="pam.html"></HEAD +><BODY +CLASS="CHAPTER" +BGCOLOR="#FFFFFF" +TEXT="#000000" +LINK="#0000FF" +VLINK="#840084" +ALINK="#0000FF" +><DIV +CLASS="NAVHEADER" +><TABLE +SUMMARY="Header navigation table" +WIDTH="100%" +BORDER="0" +CELLPADDING="0" +CELLSPACING="0" +><TR +><TH +COLSPAN="3" +ALIGN="center" +>SAMBA Project Documentation</TH +></TR +><TR +><TD +WIDTH="10%" +ALIGN="left" +VALIGN="bottom" +><A +HREF="diagnosis.html" +ACCESSKEY="P" +>Prev</A +></TD +><TD +WIDTH="80%" +ALIGN="center" +VALIGN="bottom" +></TD +><TD +WIDTH="10%" +ALIGN="right" +VALIGN="bottom" +><A +HREF="pam.html" +ACCESSKEY="N" +>Next</A +></TD +></TR +></TABLE +><HR +ALIGN="LEFT" +WIDTH="100%"></DIV +><DIV +CLASS="CHAPTER" +><H1 +><A +NAME="INTEGRATE-MS-NETWORKS">Chapter 3. Integrating MS Windows networks with Samba</H1 +><DIV +CLASS="SECT1" +><H1 +CLASS="SECT1" +><A +NAME="AEN362">3.1. Agenda</H1 +><P +>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.</P +><P +>We will examine:</P +><P +></P +><OL +TYPE="1" +><LI +><P +>Name resolution in a pure Unix/Linux TCP/IP + environment + </P +></LI +><LI +><P +>Name resolution as used within MS Windows + networking + </P +></LI +><LI +><P +>How browsing functions and how to deploy stable + and dependable browsing using Samba + </P +></LI +><LI +><P +>MS Windows security options and how to + configure Samba for seemless integration + </P +></LI +><LI +><P +>Configuration of Samba as:</P +><P +></P +><OL +TYPE="a" +><LI +><P +>A stand-alone server</P +></LI +><LI +><P +>An MS Windows NT 3.x/4.0 security domain member + </P +></LI +><LI +><P +>An alternative to an MS Windows NT 3.x/4.0 Domain Controller + </P +></LI +></OL +></LI +></OL +></DIV +><DIV +CLASS="SECT1" +><H1 +CLASS="SECT1" +><A +NAME="AEN384">3.2. Name Resolution in a pure Unix/Linux world</H1 +><P +>The key configuration files covered in this section are:</P +><P +></P +><UL +><LI +><P +><TT +CLASS="FILENAME" +>/etc/hosts</TT +></P +></LI +><LI +><P +><TT +CLASS="FILENAME" +>/etc/resolv.conf</TT +></P +></LI +><LI +><P +><TT +CLASS="FILENAME" +>/etc/host.conf</TT +></P +></LI +><LI +><P +><TT +CLASS="FILENAME" +>/etc/nsswitch.conf</TT +></P +></LI +></UL +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN400">3.2.1. <TT +CLASS="FILENAME" +>/etc/hosts</TT +></H2 +><P +>Contains a static list of IP Addresses and names. +eg:</P +><P +><PRE +CLASS="PROGRAMLISTING" +> 127.0.0.1 localhost localhost.localdomain + 192.168.1.1 bigbox.caldera.com bigbox alias4box</PRE +></P +><P +>The purpose of <TT +CLASS="FILENAME" +>/etc/hosts</TT +> is to provide a +name resolution mechanism so that uses do not need to remember +IP addresses.</P +><P +>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</P +><P +>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</P +><P +>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.</P +><P +>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 +<TT +CLASS="FILENAME" +>/etc/hosts</TT +> is one such file.</P +><P +>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.</P +><P +>The <TT +CLASS="FILENAME" +>/etc/hosts</TT +> 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.</P +></DIV +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN416">3.2.2. <TT +CLASS="FILENAME" +>/etc/resolv.conf</TT +></H2 +><P +>This file tells the name resolution libraries:</P +><P +></P +><UL +><LI +><P +>The name of the domain to which the machine + belongs + </P +></LI +><LI +><P +>The name(s) of any domains that should be + automatically searched when trying to resolve unqualified + host names to their IP address + </P +></LI +><LI +><P +>The name or IP address of available Domain + Name Servers that may be asked to perform name to address + translation lookups + </P +></LI +></UL +></DIV +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN427">3.2.3. <TT +CLASS="FILENAME" +>/etc/host.conf</TT +></H2 +><P +><TT +CLASS="FILENAME" +>/etc/host.conf</TT +> 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:</P +><P +><PRE +CLASS="PROGRAMLISTING" +> order hosts,bind + multi on</PRE +></P +><P +>then both addresses should be returned. Please refer to the +man page for host.conf for further details.</P +></DIV +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN435">3.2.4. <TT +CLASS="FILENAME" +>/etc/nsswitch.conf</TT +></H2 +><P +>This file controls the actual name resolution targets. The +file typically has resolver object specifications as follows:</P +><P +><PRE +CLASS="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</PRE +></P +><P +>Of course, each of these mechanisms requires that the appropriate +facilities and/or services are correctly configured.</P +><P +>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.</P +><P +>Samba version 2.2.0 will add 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: <B +CLASS="COMMAND" +>make +nsswitch/libnss_wins.so</B +>). The resulting library should +then be installed in the <TT +CLASS="FILENAME" +>/lib</TT +> directory and +the "wins" parameter needs to be added to the "hosts:" line in +the <TT +CLASS="FILENAME" +>/etc/nsswitch.conf</TT +> 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.</P +></DIV +></DIV +><DIV +CLASS="SECT1" +><H1 +CLASS="SECT1" +><A +NAME="AEN447">3.3. Name resolution as used within MS Windows networking</H1 +><P +>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.</P +><P +>The following are typical NetBIOS name/service type registrations:</P +><P +><PRE +CLASS="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</PRE +></P +><P +>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.</P +><P +>One further point of clarification should be noted, the <TT +CLASS="FILENAME" +>/etc/hosts</TT +> +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.</P +><P +>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.</P +><P +>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.</P +><P +>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.</P +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN459">3.3.1. The NetBIOS Name Cache</H2 +><P +>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.</P +><P +>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.</P +><P +>The MS Windows utility that allows examination of the NetBIOS +name cache is called "nbtstat". The Samba equivalent of this +is called "nmblookup".</P +></DIV +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN464">3.3.2. The LMHOSTS file</H2 +><P +>This file is usually located in MS Windows NT 4.0 or +2000 in <TT +CLASS="FILENAME" +>C:\WINNT\SYSTEM32\DRIVERS\ETC</TT +> and contains +the IP Address and the machine name in matched pairs. The +<TT +CLASS="FILENAME" +>LMHOSTS</TT +> file performs NetBIOS name +to IP address mapping oriented.</P +><P +>It typically looks like:</P +><P +><PRE +CLASS="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.</PRE +></P +></DIV +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN472">3.3.3. HOSTS file</H2 +><P +>This file is usually located in MS Windows NT 4.0 or 2000 in +<TT +CLASS="FILENAME" +>C:\WINNT\SYSTEM32\DRIVERS\ETC</TT +> 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 <TT +CLASS="FILENAME" +>/etc/hosts</TT +> file.</P +></DIV +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN477">3.3.4. DNS Lookup</H2 +><P +>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.</P +></DIV +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN480">3.3.5. WINS Lookup</H2 +><P +>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.</P +><P +>To configure Samba to be a WINS server the following parameter needs +to be added to the <TT +CLASS="FILENAME" +>smb.conf</TT +> file:</P +><P +><PRE +CLASS="PROGRAMLISTING" +> wins support = Yes</PRE +></P +><P +>To configure Samba to use a WINS server the following parameters are +needed in the smb.conf file:</P +><P +><PRE +CLASS="PROGRAMLISTING" +> wins support = No + wins server = xxx.xxx.xxx.xxx</PRE +></P +><P +>where <TT +CLASS="REPLACEABLE" +><I +>xxx.xxx.xxx.xxx</I +></TT +> is the IP address +of the WINS server.</P +></DIV +></DIV +><DIV +CLASS="SECT1" +><H1 +CLASS="SECT1" +><A +NAME="AEN492">3.4. How browsing functions and how to deploy stable and +dependable browsing using Samba</H1 +><P +>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.</P +><P +>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).</P +><P +>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.</P +><P +>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.</P +><P +>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. </P +><P +>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.</P +><P +>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, <TT +CLASS="FILENAME" +>/etc/hosts</TT +>, +and so on.</P +></DIV +><DIV +CLASS="SECT1" +><H1 +CLASS="SECT1" +><A +NAME="AEN502">3.5. MS Windows security options and how to configure +Samba for seemless integration</H1 +><P +>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.</P +><P +>When encrypted passwords are used a password that has been +entered by the user is encrypted in two ways:</P +><P +></P +><UL +><LI +><P +>An MD4 hash of the UNICODE of the password + string. This is known as the NT hash. + </P +></LI +><LI +><P +>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. + </P +></LI +></UL +><P +>You should refer to the <A +HREF="ENCRYPTION.html" +TARGET="_top" +>Password Encryption</A +> chapter in this HOWTO collection +for more details on the inner workings</P +><P +>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.</P +><P +>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.</P +><P +>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.</P +><P +>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.</P +><P +><PRE +CLASS="PROGRAMLISTING" +> <A +HREF="smb.conf.5.html#PASSWORDLEVEL" +TARGET="_top" +>passsword level</A +> = <TT +CLASS="REPLACEABLE" +><I +>integer</I +></TT +> + <A +HREF="smb.conf.5.html#USERNAMELEVEL" +TARGET="_top" +>username level</A +> = <TT +CLASS="REPLACEABLE" +><I +>integer</I +></TT +></PRE +></P +><P +>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 <TT +CLASS="PARAMETER" +><I +>username level</I +></TT +> parameter +is rarely even needed.</P +><P +>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 <TT +CLASS="PARAMETER" +><I +>password level</I +></TT +> must be set to the maximum +number of upper case letter which <SPAN +CLASS="emphasis" +><I +CLASS="EMPHASIS" +>could</I +></SPAN +> appear +is a password. Note that is the server OS uses the traditional +DES version of crypt(), then a <TT +CLASS="PARAMETER" +><I +>password level</I +></TT +> +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).</P +><P +>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:</P +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN530">3.5.1. Use MS Windows NT as an authentication server</H2 +><P +>This method involves the additions of the following parameters +in the smb.conf file:</P +><P +><PRE +CLASS="PROGRAMLISTING" +> encrypt passwords = Yes + security = server + password server = "NetBIOS_name_of_PDC"</PRE +></P +><P +>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.</P +><P +>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.</P +><P +>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.</P +></DIV +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN538">3.5.2. Make Samba a member of an MS Windows NT security domain</H2 +><P +>This method involves additon of the following paramters in the smb.conf file:</P +><P +><PRE +CLASS="PROGRAMLISTING" +> encrypt passwords = Yes + security = domain + workgroup = "name of NT domain" + password server = *</PRE +></P +><P +>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.</P +><P +>In order for this method to work the Samba server needs to join the +MS Windows NT security domain. This is done as follows:</P +><P +></P +><UL +><LI +><P +>On the MS Windows NT domain controller using + the Server Manager add a machine account for the Samba server. + </P +></LI +><LI +><P +>Next, on the Linux system execute: + <B +CLASS="COMMAND" +>smbpasswd -r PDC_NAME -j DOMAIN_NAME</B +> + </P +></LI +></UL +><P +>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 <TT +CLASS="FILENAME" +>/etc/passwd</TT +> entry.</P +><P +>An alternative to assigning UIDs to Windows users on a +Samba member server is presented in the <A +HREF="winbind.html" +TARGET="_top" +>Winbind Overview</A +> chapter in +this HOWTO collection.</P +></DIV +><DIV +CLASS="SECT2" +><H2 +CLASS="SECT2" +><A +NAME="AEN555">3.5.3. Configure Samba as an authentication server</H2 +><P +>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.</P +><P +>This method involves addition of the following parameters to +the smb.conf file:</P +><P +><PRE +CLASS="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</PRE +></P +><P +>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.</P +><DIV +CLASS="SECT3" +><H3 +CLASS="SECT3" +><A +NAME="AEN562">3.5.3.1. Users</H3 +><P +>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.</P +><P +><PRE +CLASS="PROGRAMLISTING" +> # useradd -s /bin/bash -d /home/"userid" -m "userid" + # passwd "userid" + Enter Password: <pw> + + # smbpasswd -a "userid" + Enter Password: <pw></PRE +></P +></DIV +><DIV +CLASS="SECT3" +><H3 +CLASS="SECT3" +><A +NAME="AEN567">3.5.3.2. MS Windows NT Machine Accounts</H3 +><P +>These are required only when Samba is used as a domain +controller. Refer to the Samba-PDC-HOWTO for more details.</P +><P +><PRE +CLASS="PROGRAMLISTING" +> # useradd -s /bin/false -d /dev/null "machine_name"\$ + # passwd -l "machine_name"\$ + # smbpasswd -a -m "machine_name"</PRE +></P +></DIV +></DIV +></DIV +><DIV +CLASS="SECT1" +><H1 +CLASS="SECT1" +><A +NAME="AEN572">3.6. Conclusions</H1 +><P +>Samba provides a flexible means to operate as...</P +><P +></P +><UL +><LI +><P +>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. + </P +></LI +><LI +><P +>An MS Windows NT 3.x/4.0 security domain member. + </P +></LI +><LI +><P +>An alternative to an MS Windows NT 3.x/4.0 + Domain Controller. + </P +></LI +></UL +></DIV +></DIV +><DIV +CLASS="NAVFOOTER" +><HR +ALIGN="LEFT" +WIDTH="100%"><TABLE +SUMMARY="Footer navigation table" +WIDTH="100%" +BORDER="0" +CELLPADDING="0" +CELLSPACING="0" +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +><A +HREF="diagnosis.html" +ACCESSKEY="P" +>Prev</A +></TD +><TD +WIDTH="34%" +ALIGN="center" +VALIGN="top" +><A +HREF="Samba-HOWTO.html" +ACCESSKEY="H" +>Home</A +></TD +><TD +WIDTH="33%" +ALIGN="right" +VALIGN="top" +><A +HREF="pam.html" +ACCESSKEY="N" +>Next</A +></TD +></TR +><TR +><TD +WIDTH="33%" +ALIGN="left" +VALIGN="top" +>Diagnosing your samba server</TD +><TD +WIDTH="34%" +ALIGN="center" +VALIGN="top" +> </TD +><TD +WIDTH="33%" +ALIGN="right" +VALIGN="top" +>Configuring PAM for distributed but centrally +managed authentication</TD +></TR +></TABLE +></DIV +></BODY +></HTML +>
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