| 1 | <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 29. Integrating MS Windows Networks with Samba</title><link rel="stylesheet" href="../samba.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.74.0"><link rel="home" href="index.html" title="The Official Samba 3.2.x HOWTO and Reference Guide"><link rel="up" href="optional.html" title="Part III. Advanced Configuration"><link rel="prev" href="pam.html" title="Chapter 28. PAM-Based Distributed Authentication"><link rel="next" href="unicode.html" title="Chapter 30. Unicode/Charsets"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 29. Integrating MS Windows Networks with Samba</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="pam.html">Prev</a> </td><th width="60%" align="center">Part III. Advanced Configuration</th><td width="20%" align="right"> <a accesskey="n" href="unicode.html">Next</a></td></tr></table><hr></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="integrate-ms-networks"></a>Chapter 29. Integrating MS Windows Networks with Samba</h2></div><div><div class="author"><h3 class="author"><span class="firstname">John</span> <span class="othername">H.</span> <span class="orgname">Samba Team</span> <span class="surname">Terpstra</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><code class="email"><<a class="email" href="mailto:jht@samba.org">jht@samba.org</a>></code></p></div></div></div></div><div><p class="pubdate"> (Jan 01 2001) </p></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="integrate-ms-networks.html#id2668091">Features and Benefits</a></span></dt><dt><span class="sect1"><a href="integrate-ms-networks.html#id2668111">Background Information</a></span></dt><dt><span class="sect1"><a href="integrate-ms-networks.html#id2668240">Name Resolution in a Pure UNIX/Linux World</a></span></dt><dd><dl><dt><span class="sect2"><a href="integrate-ms-networks.html#id2668313">/etc/hosts</a></span></dt><dt><span class="sect2"><a href="integrate-ms-networks.html#id2668502">/etc/resolv.conf</a></span></dt><dt><span class="sect2"><a href="integrate-ms-networks.html#id2668538">/etc/host.conf</a></span></dt><dt><span class="sect2"><a href="integrate-ms-networks.html#id2668589">/etc/nsswitch.conf</a></span></dt></dl></dd><dt><span class="sect1"><a href="integrate-ms-networks.html#id2668713">Name Resolution as Used within MS Windows Networking</a></span></dt><dd><dl><dt><span class="sect2"><a href="integrate-ms-networks.html#id2669148">The NetBIOS Name Cache</a></span></dt><dt><span class="sect2"><a href="integrate-ms-networks.html#id2669234">The LMHOSTS File</a></span></dt><dt><span class="sect2"><a href="integrate-ms-networks.html#id2669410">HOSTS File</a></span></dt><dt><span class="sect2"><a href="integrate-ms-networks.html#id2669438">DNS Lookup</a></span></dt><dt><span class="sect2"><a href="integrate-ms-networks.html#id2669465">WINS Lookup</a></span></dt></dl></dd><dt><span class="sect1"><a href="integrate-ms-networks.html#id2669603">Common Errors</a></span></dt><dd><dl><dt><span class="sect2"><a href="integrate-ms-networks.html#id2669616">Pinging Works Only One Way</a></span></dt><dt><span class="sect2"><a href="integrate-ms-networks.html#id2669647">Very Slow Network Connections</a></span></dt><dt><span class="sect2"><a href="integrate-ms-networks.html#id2669689">Samba Server Name-Change Problem</a></span></dt></dl></dd></dl></div><p>
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| 2 | <a class="indexterm" name="id2668049"></a>
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| 3 | This chapter deals with NetBIOS over TCP/IP name to IP address resolution. If
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| 4 | your MS Windows clients are not configured to use NetBIOS over TCP/IP, then this
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| 5 | section does not apply to your installation. If your installation involves the use of
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| 6 | NetBIOS over TCP/IP, then this chapter may help you to resolve networking problems.
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| 7 | </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
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| 8 | <a class="indexterm" name="id2668066"></a>
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| 9 | <a class="indexterm" name="id2668073"></a>
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| 10 | NetBIOS over TCP/IP has nothing to do with NetBEUI. NetBEUI is NetBIOS
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| 11 | over Logical Link Control (LLC). On modern networks it is highly advised
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| 12 | to not run NetBEUI at all. Note also that there is no such thing as
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| 13 | NetBEUI over TCP/IP the existence of such a protocol is a complete
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| 14 | and utter misapprehension.
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| 15 | </p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2668091"></a>Features and Benefits</h2></div></div></div><p>
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| 16 | Many MS Windows network administrators have never been exposed to basic TCP/IP
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| 17 | networking as it is implemented in a UNIX/Linux operating system. Likewise, many UNIX and
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| 18 | Linux administrators have not been exposed to the intricacies of MS Windows TCP/IP-based
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| 19 | networking (and may have no desire to be, either).
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| 20 | </p><p>
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| 21 | This chapter gives a short introduction to the basics of how a name can be resolved to
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| 22 | its IP address for each operating system environment.
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| 23 | </p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2668111"></a>Background Information</h2></div></div></div><p>
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| 24 | <a class="indexterm" name="id2668119"></a>
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| 25 | <a class="indexterm" name="id2668126"></a>
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| 26 | <a class="indexterm" name="id2668133"></a>
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| 27 | <a class="indexterm" name="id2668140"></a>
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| 28 | <a class="indexterm" name="id2668147"></a>
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| 29 | Since the introduction of MS Windows 2000, it is possible to run MS Windows networking
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| 30 | without the use of NetBIOS over TCP/IP. NetBIOS over TCP/IP uses UDP port 137 for NetBIOS
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| 31 | name resolution and uses TCP port 139 for NetBIOS session services. When NetBIOS over
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| 32 | TCP/IP is disabled on MS Windows 2000 and later clients, then only the TCP port 445 is
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| 33 | used, and the UDP port 137 and TCP port 139 are not.
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| 34 | </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
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| 35 | When using Windows 2000 or later clients, if NetBIOS over TCP/IP is not disabled, then
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| 36 | the client will use UDP port 137 (NetBIOS Name Service, also known as the Windows Internet
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| 37 | Name Service, or WINS), TCP port 139, and TCP port 445 (for actual file and print traffic).
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| 38 | </p></div><p>
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| 39 | <a class="indexterm" name="id2668175"></a>
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| 40 | <a class="indexterm" name="id2668181"></a>
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| 41 | <a class="indexterm" name="id2668188"></a>
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| 42 | <a class="indexterm" name="id2668195"></a>
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| 43 | <a class="indexterm" name="id2668201"></a>
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| 44 | <a class="indexterm" name="id2668208"></a>
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| 45 | When NetBIOS over TCP/IP is disabled, the use of DNS is essential. Most installations that disable NetBIOS
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| 46 | over TCP/IP today use MS Active Directory Service (ADS). ADS requires
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| 47 | <a class="indexterm" name="id2668218"></a> dynamic DNS with Service Resource
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| 48 | Records (SRV RR) and with Incremental Zone Transfers (IXFR). <a class="indexterm" name="id2668229"></a>
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| 49 | Use of DHCP with ADS is recommended as a further means of maintaining central control over the client
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| 50 | workstation network configuration.
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| 51 | </p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2668240"></a>Name Resolution in a Pure UNIX/Linux World</h2></div></div></div><p>
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| 52 | The key configuration files covered in this section are:
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| 53 | </p><a class="indexterm" name="id2668250"></a><a class="indexterm" name="id2668257"></a><a class="indexterm" name="id2668264"></a><a class="indexterm" name="id2668271"></a><div class="itemizedlist"><ul type="disc"><li><p><code class="filename">/etc/hosts</code></p></li><li><p><code class="filename">/etc/resolv.conf</code></p></li><li><p><code class="filename">/etc/host.conf</code></p></li><li><p><code class="filename">/etc/nsswitch.conf</code></p></li></ul></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2668313"></a><code class="filename">/etc/hosts</code></h3></div></div></div><p>
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| 54 | This file contains a static list of IP addresses and names.
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| 55 | </p><pre class="programlisting">
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| 56 | 127.0.0.1 localhost localhost.localdomain
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| 57 | 192.168.1.1 bigbox.quenya.org bigbox alias4box
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| 58 | </pre><p>
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| 59 | </p><p>
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| 60 | <a class="indexterm" name="id2668336"></a>
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| 61 | <a class="indexterm" name="id2668343"></a>
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| 62 | The purpose of <code class="filename">/etc/hosts</code> is to provide a
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| 63 | name resolution mechanism so users do not need to remember
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| 64 | IP addresses.
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| 65 | </p><p>
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| 66 | <a class="indexterm" name="id2668361"></a>
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| 67 | <a class="indexterm" name="id2668368"></a>
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| 68 | <a class="indexterm" name="id2668375"></a>
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| 69 | Network packets that are sent over the physical network transport
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| 70 | layer communicate not via IP addresses but rather using the Media
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| 71 | Access Control address, or MAC address. IP addresses are currently
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| 72 | 32 bits in length and are typically presented as four decimal
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| 73 | numbers that are separated by a dot (or period) for example, 168.192.1.1.
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| 74 | </p><p>
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| 75 | <a class="indexterm" name="id2668393"></a>
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| 76 | MAC addresses use 48 bits (or 6 bytes) and are typically represented
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| 77 | as two-digit hexadecimal numbers separated by colons: 40:8e:0a:12:34:56.
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| 78 | </p><p>
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| 79 | Every network interface must have a MAC address. Associated with a MAC address may be one or more IP
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| 80 | addresses. There is no relationship between an IP address and a MAC address; all such assignments are
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| 81 | arbitrary or discretionary in nature. At the most basic level, all network communications take place using MAC
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| 82 | addressing. Since MAC addresses must be globally unique and generally remain fixed for any particular
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| 83 | interface, the assignment of an IP address makes sense from a network management perspective. More than one IP
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| 84 | address can be assigned per MAC address. One address must be the primary IP address this is the
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| 85 | address that will be returned in the Address Resolution Protocol (ARP) reply.
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| 86 | </p><p>
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| 87 | <a class="indexterm" name="id2668424"></a>
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| 88 | When a user or a process wants to communicate with another machine,
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| 89 | the protocol implementation ensures that the “<span class="quote">machine name</span>” or “<span class="quote">host
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| 90 | name</span>” is resolved to an IP address in a manner that is controlled
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| 91 | by the TCP/IP configuration control files. The file
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| 92 | <code class="filename">/etc/hosts</code> is one such file.
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| 93 | </p><p>
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| 94 | <a class="indexterm" name="id2668451"></a>
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| 95 | When the IP address of the destination interface has been determined, a protocol called ARP/RARP is used to
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| 96 | identify the MAC address of the target interface. ARP is a broadcast-oriented method that uses User Datagram
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| 97 | Protocol (UDP) to send a request to all interfaces on the local network segment using the all 1s MAC address.
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| 98 | Network interfaces are programmed to respond to two MAC addresses only; their own unique address and the
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| 99 | address ff:ff:ff:ff:ff:ff. The reply packet from an ARP request will contain the MAC address and the primary
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| 100 | IP address for each interface.
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| 101 | </p><p>
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| 102 | <a class="indexterm" name="id2668480"></a>
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| 103 | The <code class="filename">/etc/hosts</code> file is foundational to all
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| 104 | UNIX/Linux TCP/IP installations and as a minimum will contain
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| 105 | the localhost and local network interface IP addresses and the
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| 106 | primary names by which they are known within the local machine.
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| 107 | This file helps to prime the pump so a basic level of name
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| 108 | resolution can exist before any other method of name resolution
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| 109 | becomes available.
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| 110 | </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2668502"></a><code class="filename">/etc/resolv.conf</code></h3></div></div></div><p>
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| 111 | This file tells the name resolution libraries:
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| 112 | </p><div class="itemizedlist"><ul type="disc"><li><p>The name of the domain to which the machine
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| 113 | belongs.
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| 114 | </p></li><li><p>The name(s) of any domains that should be
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| 115 | automatically searched when trying to resolve unqualified
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| 116 | host names to their IP address.
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| 117 | </p></li><li><p>The name or IP address of available domain
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| 118 | name servers that may be asked to perform name-to-address
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| 119 | translation lookups.
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| 120 | </p></li></ul></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2668538"></a><code class="filename">/etc/host.conf</code></h3></div></div></div><p>
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| 121 | <a class="indexterm" name="id2668549"></a>
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| 122 | <code class="filename">/etc/host.conf</code> is the primary means by which the setting in
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| 123 | <code class="filename">/etc/resolv.conf</code> may be effected. It is a critical configuration file. This file controls
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| 124 | the order by which name resolution may proceed. The typical structure is:
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| 125 | </p><pre class="programlisting">
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| 126 | order hosts,bind
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| 127 | multi on
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| 128 | </pre><p>Both addresses should be returned. Please refer to the
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| 129 | man page for <code class="filename">host.conf</code> for further details.
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| 130 | </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2668589"></a><code class="filename">/etc/nsswitch.conf</code></h3></div></div></div><p>
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| 131 | <a class="indexterm" name="id2668600"></a>
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| 132 | This file controls the actual name resolution targets. The
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| 133 | file typically has resolver object specifications as follows:
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| 134 | </p><pre class="programlisting">
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| 135 | # /etc/nsswitch.conf
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| 136 | #
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| 137 | # Name Service Switch configuration file.
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| 138 | #
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| 139 |
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| 140 | passwd: compat
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| 141 | # Alternative entries for password authentication are:
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| 142 | # passwd: compat files nis ldap winbind
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| 143 | shadow: compat
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| 144 | group: compat
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| 145 |
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| 146 | hosts: files nis dns
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| 147 | # Alternative entries for host name resolution are:
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| 148 | # hosts: files dns nis nis+ hesiod db compat ldap wins
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| 149 | networks: nis files dns
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| 150 |
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| 151 | ethers: nis files
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| 152 | protocols: nis files
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| 153 | rpc: nis files
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| 154 | services: nis files
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| 155 | </pre><p>
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| 156 | Of course, each of these mechanisms requires that the appropriate
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| 157 | facilities and/or services are correctly configured.
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| 158 | </p><p>
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| 159 | It should be noted that unless a network request/message must be
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| 160 | sent, TCP/IP networks are silent. All TCP/IP communications assume a
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| 161 | principal of speaking only when necessary.
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| 162 | </p><p>
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| 163 | <a class="indexterm" name="id2668636"></a>
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| 164 | <a class="indexterm" name="id2668643"></a>
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| 165 | <a class="indexterm" name="id2668650"></a>
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| 166 | <a class="indexterm" name="id2668657"></a>
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| 167 | <a class="indexterm" name="id2668664"></a>
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| 168 | Starting with version 2.2.0, Samba has Linux support for extensions to
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| 169 | the name service switch infrastructure so Linux clients will
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| 170 | be able to obtain resolution of MS Windows NetBIOS names to IP
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| 171 | addresses. To gain this functionality, Samba needs to be compiled
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| 172 | with appropriate arguments to the make command (i.e., <strong class="userinput"><code>make
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| 173 | nsswitch/libnss_wins.so</code></strong>). The resulting library should
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| 174 | then be installed in the <code class="filename">/lib</code> directory, and
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| 175 | the <em class="parameter"><code>wins</code></em> parameter needs to be added to the “<span class="quote">hosts:</span>” line in
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| 176 | the <code class="filename">/etc/nsswitch.conf</code> file. At this point, it
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| 177 | will be possible to ping any MS Windows machine by its NetBIOS
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| 178 | machine name, as long as that machine is within the workgroup to
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| 179 | which both the Samba machine and the MS Windows machine belong.
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| 180 | </p></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2668713"></a>Name Resolution as Used within MS Windows Networking</h2></div></div></div><p>
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| 181 | <a class="indexterm" name="id2668722"></a>
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| 182 | <a class="indexterm" name="id2668728"></a>
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| 183 | <a class="indexterm" name="id2668735"></a>
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| 184 | <a class="indexterm" name="id2668742"></a>
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| 185 | MS Windows networking is predicated on the name each machine is given. This name is known variously (and
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| 186 | inconsistently) as the “<span class="quote">computer name,</span>” “<span class="quote">machine name,</span>” “<span class="quote">networking
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| 187 | name,</span>” “<span class="quote">NetBIOS name,</span>” or “<span class="quote">SMB name.</span>” All terms mean the same thing with the
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| 188 | exception of “<span class="quote">NetBIOS name,</span>” which can also apply to the name of the workgroup or the domain
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| 189 | name. The terms “<span class="quote">workgroup</span>” and “<span class="quote">domain</span>” are really just a simple name with which
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| 190 | the machine is associated. All NetBIOS names are exactly 16 characters in length. The
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| 191 | 16<sup>th</sup> character is reserved. It is used to store a 1-byte value that indicates
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| 192 | service level information for the NetBIOS name that is registered. A NetBIOS machine name is therefore
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| 193 | registered for each service type that is provided by the client/server.
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| 194 | </p><p>
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| 195 | <a class="link" href="integrate-ms-networks.html#uniqnetbiosnames" title="Table 29.1. Unique NetBIOS Names">Unique NetBIOS names</a> and <a class="link" href="integrate-ms-networks.html#netbiosnamesgrp" title="Table 29.2. Group Names">group names</a> tables
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| 196 | list typical NetBIOS name/service type registrations.
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| 197 | </p><div class="table"><a name="uniqnetbiosnames"></a><p class="title"><b>Table 29.1. Unique NetBIOS Names</b></p><div class="table-contents"><table summary="Unique NetBIOS Names" border="1"><colgroup><col align="left"><col align="justify"></colgroup><tbody><tr><td align="left">MACHINENAME<00></td><td align="justify">Server Service is running on MACHINENAME</td></tr><tr><td align="left">MACHINENAME<03></td><td align="justify">Generic machine name (NetBIOS name)</td></tr><tr><td align="left">MACHINENAME<20></td><td align="justify">LanMan server service is running on MACHINENAME</td></tr><tr><td align="left">WORKGROUP<1b></td><td align="justify">Domain master browser</td></tr></tbody></table></div></div><br class="table-break"><div class="table"><a name="netbiosnamesgrp"></a><p class="title"><b>Table 29.2. Group Names</b></p><div class="table-contents"><table summary="Group Names" border="1"><colgroup><col align="left"><col align="justify"></colgroup><tbody><tr><td align="left">WORKGROUP<03></td><td align="justify">Generic name registered by all members of WORKGROUP</td></tr><tr><td align="left">WORKGROUP<1c></td><td align="justify">Domain cntrollers/netlogon servers</td></tr><tr><td align="left">WORKGROUP<1d></td><td align="justify">Local master browsers</td></tr><tr><td align="left">WORKGROUP<1e></td><td align="justify">Browser election service</td></tr></tbody></table></div></div><br class="table-break"><p>
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| 198 | <a class="indexterm" name="id2668939"></a>
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| 199 | It should be noted that all NetBIOS machines register their own
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| 200 | names as per <a class="link" href="integrate-ms-networks.html#uniqnetbiosnames" title="Table 29.1. Unique NetBIOS Names">Unique NetBIOS names</a> and <a class="link" href="integrate-ms-networks.html#netbiosnamesgrp" title="Table 29.2. Group Names">group names</a>. This is in vast contrast to TCP/IP
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| 201 | installations where the system administrator traditionally
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| 202 | determines in the <code class="filename">/etc/hosts</code> or in the DNS database what names
|
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| 203 | are associated with each IP address.
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| 204 | </p><p>
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| 205 | <a class="indexterm" name="id2668974"></a>
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| 206 | <a class="indexterm" name="id2668981"></a>
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| 207 | <a class="indexterm" name="id2668987"></a>
|
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| 208 | One further point of clarification should be noted. The <code class="filename">/etc/hosts</code>
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| 209 | file and the DNS records do not provide the NetBIOS name information
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| 210 | that MS Windows clients depend on to locate the type of service that may
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| 211 | be needed. An example of this is what happens when an MS Windows client
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| 212 | wants to locate a domain logon server. It finds this service and the IP
|
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| 213 | address of a server that provides it by performing a lookup (via a
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| 214 | NetBIOS broadcast) for enumeration of all machines that have
|
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| 215 | registered the name type *<1C>. A logon request is then sent to each
|
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| 216 | IP address that is returned in the enumerated list of IP addresses.
|
|---|
| 217 | Whichever machine first replies, it then ends up providing the logon services.
|
|---|
| 218 | </p><p>
|
|---|
| 219 | <a class="indexterm" name="id2669019"></a>
|
|---|
| 220 | <a class="indexterm" name="id2669026"></a>
|
|---|
| 221 | The name “<span class="quote">workgroup</span>” or “<span class="quote">domain</span>” really can be confusing, since these
|
|---|
| 222 | have the added significance of indicating what is the security
|
|---|
| 223 | architecture of the MS Windows network. The term “<span class="quote">workgroup</span>” indicates
|
|---|
| 224 | that the primary nature of the network environment is that of a
|
|---|
| 225 | peer-to-peer design. In a workgroup, all machines are responsible for
|
|---|
| 226 | their own security, and generally such security is limited to the use of
|
|---|
| 227 | just a password (known as share-level security). In most situations
|
|---|
| 228 | with peer-to-peer networking, the users who control their own machines
|
|---|
| 229 | will simply opt to have no security at all. It is possible to have
|
|---|
| 230 | user-level security in a workgroup environment, thus requiring the use
|
|---|
| 231 | of a username and a matching password.
|
|---|
| 232 | </p><p>
|
|---|
| 233 | <a class="indexterm" name="id2669059"></a>
|
|---|
| 234 | <a class="indexterm" name="id2669065"></a>
|
|---|
| 235 | <a class="indexterm" name="id2669075"></a>
|
|---|
| 236 | <a class="indexterm" name="id2669084"></a>
|
|---|
| 237 | <a class="indexterm" name="id2669094"></a>
|
|---|
| 238 | <a class="indexterm" name="id2669103"></a>
|
|---|
| 239 | <a class="indexterm" name="id2669110"></a>
|
|---|
| 240 | <a class="indexterm" name="id2669117"></a>
|
|---|
| 241 | MS Windows networking is thus predetermined to use machine names
|
|---|
| 242 | for all local and remote machine message passing. The protocol used is
|
|---|
| 243 | called Server Message Block (SMB), and this is implemented using
|
|---|
| 244 | the NetBIOS protocol (Network Basic Input/Output System). NetBIOS can
|
|---|
| 245 | be encapsulated using LLC (Logical Link Control) protocol in which case
|
|---|
| 246 | the resulting protocol is called NetBEUI (Network Basic Extended User
|
|---|
| 247 | Interface). NetBIOS can also be run over IPX (Internetworking Packet
|
|---|
| 248 | Exchange) protocol as used by Novell NetWare, and it can be run
|
|---|
| 249 | over TCP/IP protocols in which case the resulting protocol is called
|
|---|
| 250 | NBT or NetBT, the NetBIOS over TCP/IP.
|
|---|
| 251 | </p><p>
|
|---|
| 252 | MS Windows machines use a complex array of name resolution mechanisms.
|
|---|
| 253 | Since we are primarily concerned with TCP/IP, this demonstration is
|
|---|
| 254 | limited to this area.
|
|---|
| 255 | </p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2669148"></a>The NetBIOS Name Cache</h3></div></div></div><p>
|
|---|
| 256 | <a class="indexterm" name="id2669155"></a>
|
|---|
| 257 | <a class="indexterm" name="id2669162"></a>
|
|---|
| 258 | <a class="indexterm" name="id2669169"></a>
|
|---|
| 259 | All MS Windows machines employ an in-memory buffer in which is
|
|---|
| 260 | stored the NetBIOS names and IP addresses for all external
|
|---|
| 261 | machines that machine has communicated with over the
|
|---|
| 262 | past 10 to 15 minutes. It is more efficient to obtain an IP address
|
|---|
| 263 | for a machine from the local cache than it is to go through all the
|
|---|
| 264 | configured name resolution mechanisms.
|
|---|
| 265 | </p><p>
|
|---|
| 266 | <a class="indexterm" name="id2669184"></a>
|
|---|
| 267 | If a machine whose name is in the local name cache is shut
|
|---|
| 268 | down before the name is expired and flushed from the cache, then
|
|---|
| 269 | an attempt to exchange a message with that machine will be subject
|
|---|
| 270 | to timeout delays. Its name is in the cache, so a name resolution
|
|---|
| 271 | lookup will succeed, but the machine cannot respond. This can be
|
|---|
| 272 | frustrating for users but is a characteristic of the protocol.
|
|---|
| 273 | </p><p>
|
|---|
| 274 | <a class="indexterm" name="id2669200"></a>
|
|---|
| 275 | <a class="indexterm" name="id2669207"></a>
|
|---|
| 276 | <a class="indexterm" name="id2669214"></a>
|
|---|
| 277 | The MS Windows utility that allows examination of the NetBIOS
|
|---|
| 278 | name cache is called “<span class="quote">nbtstat.</span>” The Samba equivalent
|
|---|
| 279 | is called <code class="literal">nmblookup</code>.
|
|---|
| 280 | </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2669234"></a>The LMHOSTS File</h3></div></div></div><p>
|
|---|
| 281 | <a class="indexterm" name="id2669242"></a>
|
|---|
| 282 | This file is usually located in MS Windows NT 4.0 or Windows 200x/XP in the directory
|
|---|
| 283 | <code class="filename">%SystemRoot%\SYSTEM32\DRIVERS\ETC</code> and contains the IP address
|
|---|
| 284 | and the machine name in matched pairs. The <code class="filename">LMHOSTS</code> file
|
|---|
| 285 | performs NetBIOS name to IP address mapping.
|
|---|
| 286 | </p><p>
|
|---|
| 287 | It typically looks like this:
|
|---|
| 288 | </p><pre class="programlisting">
|
|---|
| 289 | # Copyright (c) 1998 Microsoft Corp.
|
|---|
| 290 | #
|
|---|
| 291 | # This is a sample LMHOSTS file used by the Microsoft Wins Client (NetBIOS
|
|---|
| 292 | # over TCP/IP) stack for Windows98
|
|---|
| 293 | #
|
|---|
| 294 | # This file contains the mappings of IP addresses to NT computer names
|
|---|
| 295 | # (NetBIOS) names. Each entry should be kept on an individual line.
|
|---|
| 296 | # The IP address should be placed in the first column followed by the
|
|---|
| 297 | # corresponding computer name. The address and the computer name
|
|---|
| 298 | # should be separated by at least one space or tab. The "#" character
|
|---|
| 299 | # is generally used to denote the start of a comment (see the exceptions
|
|---|
| 300 | # below).
|
|---|
| 301 | #
|
|---|
| 302 | # This file is compatible with Microsoft LAN Manager 2.x TCP/IP lmhosts
|
|---|
| 303 | # files and offers the following extensions:
|
|---|
| 304 | #
|
|---|
| 305 | # #PRE
|
|---|
| 306 | # #DOM:<domain>
|
|---|
| 307 | # #INCLUDE <filename>
|
|---|
| 308 | # #BEGIN_ALTERNATE
|
|---|
| 309 | # #END_ALTERNATE
|
|---|
| 310 | # \0xnn (non-printing character support)
|
|---|
| 311 | #
|
|---|
| 312 | # Following any entry in the file with the characters "#PRE" will cause
|
|---|
| 313 | # the entry to be preloaded into the name cache. By default, entries are
|
|---|
| 314 | # not preloaded, but are parsed only after dynamic name resolution fails.
|
|---|
| 315 | #
|
|---|
| 316 | # Following an entry with the "#DOM:<domain>" tag will associate the
|
|---|
| 317 | # entry with the domain specified by <domain>. This effects how the
|
|---|
| 318 | # browser and logon services behave in TCP/IP environments. To preload
|
|---|
| 319 | # the host name associated with #DOM entry, it is necessary to also add a
|
|---|
| 320 | # #PRE to the line. The <domain> is always pre-loaded although it will not
|
|---|
| 321 | # be shown when the name cache is viewed.
|
|---|
| 322 | #
|
|---|
| 323 | # Specifying "#INCLUDE <filename>" will force the RFC NetBIOS (NBT)
|
|---|
| 324 | # software to seek the specified <filename> and parse it as if it were
|
|---|
| 325 | # local. <filename> is generally a UNC-based name, allowing a
|
|---|
| 326 | # centralized lmhosts file to be maintained on a server.
|
|---|
| 327 | # It is ALWAYS necessary to provide a mapping for the IP address of the
|
|---|
| 328 | # server prior to the #INCLUDE. This mapping must use the #PRE directive.
|
|---|
| 329 | # In addition the share "public" in the example below must be in the
|
|---|
| 330 | # LanMan Server list of "NullSessionShares" in order for client machines to
|
|---|
| 331 | # be able to read the lmhosts file successfully. This key is under
|
|---|
| 332 | # \machine\system\currentcontrolset\services\lanmanserver\
|
|---|
| 333 | # parameters\nullsessionshares
|
|---|
| 334 | # in the registry. Simply add "public" to the list found there.
|
|---|
| 335 | #
|
|---|
| 336 | # The #BEGIN_ and #END_ALTERNATE keywords allow multiple #INCLUDE
|
|---|
| 337 | # statements to be grouped together. Any single successful include
|
|---|
| 338 | # will cause the group to succeed.
|
|---|
| 339 | #
|
|---|
| 340 | # Finally, non-printing characters can be embedded in mappings by
|
|---|
| 341 | # first surrounding the NetBIOS name in quotations, then using the
|
|---|
| 342 | # \0xnn notation to specify a hex value for a non-printing character.
|
|---|
| 343 | #
|
|---|
| 344 | # The following example illustrates all of these extensions:
|
|---|
| 345 | #
|
|---|
| 346 | # 102.54.94.97 rhino #PRE #DOM:networking #net group's DC
|
|---|
| 347 | # 102.54.94.102 "appname \0x14" #special app server
|
|---|
| 348 | # 102.54.94.123 popular #PRE #source server
|
|---|
| 349 | # 102.54.94.117 localsrv #PRE #needed for the include
|
|---|
| 350 | #
|
|---|
| 351 | # #BEGIN_ALTERNATE
|
|---|
| 352 | # #INCLUDE \\localsrv\public\lmhosts
|
|---|
| 353 | # #INCLUDE \\rhino\public\lmhosts
|
|---|
| 354 | # #END_ALTERNATE
|
|---|
| 355 | #
|
|---|
| 356 | # In the above example, the "appname" server contains a special
|
|---|
| 357 | # character in its name, the "popular" and "localsrv" server names are
|
|---|
| 358 | # pre-loaded, and the "rhino" server name is specified so it can be used
|
|---|
| 359 | # to later #INCLUDE a centrally maintained lmhosts file if the "localsrv"
|
|---|
| 360 | # system is unavailable.
|
|---|
| 361 | #
|
|---|
| 362 | # Note that the whole file is parsed including comments on each lookup,
|
|---|
| 363 | # so keeping the number of comments to a minimum will improve performance.
|
|---|
| 364 | # Therefore it is not advisable to simply add lmhosts file entries onto the
|
|---|
| 365 | # end of this file.
|
|---|
| 366 | </pre></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2669410"></a>HOSTS File</h3></div></div></div><p>
|
|---|
| 367 | This file is usually located in MS Windows NT 4.0 or Windows 200x/XP in
|
|---|
| 368 | the directory <code class="filename">%SystemRoot%\SYSTEM32\DRIVERS\ETC</code> and contains
|
|---|
| 369 | the IP address and the IP hostname in matched pairs. It can be
|
|---|
| 370 | used by the name resolution infrastructure in MS Windows, depending
|
|---|
| 371 | on how the TCP/IP environment is configured. This file is in
|
|---|
| 372 | every way the equivalent of the UNIX/Linux <code class="filename">/etc/hosts</code> file.
|
|---|
| 373 | </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2669438"></a>DNS Lookup</h3></div></div></div><p>
|
|---|
| 374 | <a class="indexterm" name="id2669446"></a>
|
|---|
| 375 | This capability is configured in the TCP/IP setup area in the network
|
|---|
| 376 | configuration facility. If enabled, an elaborate name resolution sequence
|
|---|
| 377 | is followed, the precise nature of which is dependent on how the NetBIOS
|
|---|
| 378 | Node Type parameter is configured. A Node Type of 0 means that
|
|---|
| 379 | NetBIOS broadcast (over UDP broadcast) is used if the name
|
|---|
| 380 | that is the subject of a name lookup is not found in the NetBIOS name
|
|---|
| 381 | cache. If that fails, then DNS, HOSTS, and LMHOSTS are checked. If set to
|
|---|
| 382 | Node Type 8, then a NetBIOS Unicast (over UDP Unicast) is sent to the
|
|---|
| 383 | WINS server to obtain a lookup before DNS, HOSTS, LMHOSTS, or broadcast
|
|---|
| 384 | lookup is used.
|
|---|
| 385 | </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2669465"></a>WINS Lookup</h3></div></div></div><p>
|
|---|
| 386 | <a class="indexterm" name="id2669473"></a>
|
|---|
| 387 | <a class="indexterm" name="id2669480"></a>
|
|---|
| 388 | <a class="indexterm" name="id2669489"></a>
|
|---|
| 389 | A WINS (Windows Internet Name Server) service is the equivalent of the
|
|---|
| 390 | rfc1001/1002 specified NBNS (NetBIOS Name Server). A WINS server stores
|
|---|
| 391 | the names and IP addresses that are registered by a Windows client
|
|---|
| 392 | if the TCP/IP setup has been given at least one WINS server IP address.
|
|---|
| 393 | </p><p>
|
|---|
| 394 | To configure Samba to be a WINS server, the following parameter needs
|
|---|
| 395 | to be added to the <code class="filename">smb.conf</code> file:
|
|---|
| 396 | </p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2669522"></a><em class="parameter"><code>wins support = Yes</code></em></td></tr></table><p>
|
|---|
| 397 | <a class="indexterm" name="id2669536"></a>
|
|---|
| 398 | To configure Samba to use a WINS server, the following parameters are
|
|---|
| 399 | needed in the <code class="filename">smb.conf</code> file:
|
|---|
| 400 | </p><table class="simplelist" border="0" summary="Simple list"><tr><td><a class="indexterm" name="id2669558"></a><em class="parameter"><code>wins support = No</code></em></td></tr><tr><td><a class="indexterm" name="id2669570"></a><em class="parameter"><code>wins server = xxx.xxx.xxx.xxx</code></em></td></tr></table><p>
|
|---|
| 401 | where <em class="replaceable"><code>xxx.xxx.xxx.xxx</code></em> is the IP address
|
|---|
| 402 | of the WINS server.
|
|---|
| 403 | </p><p>For information about setting up Samba as a WINS server, read
|
|---|
| 404 | <a class="link" href="NetworkBrowsing.html" title="Chapter 10. Network Browsing">Network Browsing</a>.</p></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2669603"></a>Common Errors</h2></div></div></div><p>
|
|---|
| 405 | TCP/IP network configuration problems find every network administrator sooner or later.
|
|---|
| 406 | The cause can be anything from keyboard mishaps to forgetfulness to simple mistakes to
|
|---|
| 407 | carelessness. Of course, no one is ever deliberately careless!
|
|---|
| 408 | </p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2669616"></a>Pinging Works Only One Way</h3></div></div></div><p>
|
|---|
| 409 | “<span class="quote">I can ping my Samba server from Windows, but I cannot ping my Windows
|
|---|
| 410 | machine from the Samba server.</span>”
|
|---|
| 411 | </p><p>
|
|---|
| 412 | The Windows machine was at IP address 192.168.1.2 with netmask 255.255.255.0, the
|
|---|
| 413 | Samba server (Linux) was at IP address 192.168.1.130 with netmask 255.255.255.128.
|
|---|
| 414 | The machines were on a local network with no external connections.
|
|---|
| 415 | </p><p>
|
|---|
| 416 | Due to inconsistent netmasks, the Windows machine was on network 192.168.1.0/24, while
|
|---|
| 417 | the Samba server was on network 192.168.1.128/25 logically a different network.
|
|---|
| 418 | </p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2669647"></a>Very Slow Network Connections</h3></div></div></div><p>
|
|---|
| 419 | A common cause of slow network response includes:
|
|---|
| 420 | </p><div class="itemizedlist"><ul type="disc"><li><p>Client is configured to use DNS and the DNS server is down.</p></li><li><p>Client is configured to use remote DNS server, but the
|
|---|
| 421 | remote connection is down.</p></li><li><p>Client is configured to use a WINS server, but there is no WINS server.</p></li><li><p>Client is not configured to use a WINS server, but there is a WINS server.</p></li><li><p>Firewall is filtering out DNS or WINS traffic.</p></li></ul></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2669689"></a>Samba Server Name-Change Problem</h3></div></div></div><p>
|
|---|
| 422 | “<span class="quote">The name of the Samba server was changed, Samba was restarted, and now the Samba server cannot be
|
|---|
| 423 | pinged by its new name from an MS Windows NT4 workstation, but it does still respond to pinging using
|
|---|
| 424 | the old name. Why?</span>”
|
|---|
| 425 | </p><p>
|
|---|
| 426 | From this description, three things are obvious:
|
|---|
| 427 | </p><div class="itemizedlist"><ul type="disc"><li><p>WINS is not in use; only broadcast-based name resolution is used.</p></li><li><p>The Samba server was renamed and restarted within the last 10 or 15 minutes.</p></li><li><p>The old Samba server name is still in the NetBIOS name cache on the MS Windows NT4 workstation.</p></li></ul></div><p>
|
|---|
| 428 | To find what names are present in the NetBIOS name cache on the MS Windows NT4 machine,
|
|---|
| 429 | open a <code class="literal">cmd</code> shell and then:
|
|---|
| 430 | </p><p>
|
|---|
| 431 | </p><pre class="screen">
|
|---|
| 432 | <code class="prompt">C:\> </code><strong class="userinput"><code>nbtstat -n</code></strong>
|
|---|
| 433 |
|
|---|
| 434 | NetBIOS Local Name Table
|
|---|
| 435 |
|
|---|
| 436 | Name Type Status
|
|---|
| 437 | ------------------------------------------------
|
|---|
| 438 | FRODO <03> UNIQUE Registered
|
|---|
| 439 | ADMINISTRATOR <03> UNIQUE Registered
|
|---|
| 440 | FRODO <00> UNIQUE Registered
|
|---|
| 441 | SARDON <00> GROUP Registered
|
|---|
| 442 | FRODO <20> UNIQUE Registered
|
|---|
| 443 | FRODO <1F> UNIQUE Registered
|
|---|
| 444 |
|
|---|
| 445 |
|
|---|
| 446 | <code class="prompt">C:\> </code>nbtstat -c
|
|---|
| 447 |
|
|---|
| 448 | NetBIOS Remote Cache Name Table
|
|---|
| 449 |
|
|---|
| 450 | Name Type Host Address Life [sec]
|
|---|
| 451 | --------------------------------------------------------------
|
|---|
| 452 | GANDALF <20> UNIQUE 192.168.1.1 240
|
|---|
| 453 |
|
|---|
| 454 | <code class="prompt">C:\> </code>
|
|---|
| 455 | </pre><p>
|
|---|
| 456 | </p><p>
|
|---|
| 457 | In this example, GANDALF is the Samba server and FRODO is the MS Windows NT4 workstation.
|
|---|
| 458 | The first listing shows the contents of the Local Name Table (i.e., identity information on
|
|---|
| 459 | the MS Windows workstation), and the second shows the NetBIOS name in the NetBIOS name cache.
|
|---|
| 460 | The name cache contains the remote machines known to this workstation.
|
|---|
| 461 | </p></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="pam.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="optional.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="unicode.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 28. PAM-Based Distributed Authentication </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 30. Unicode/Charsets</td></tr></table></div></body></html>
|
|---|
