source: vendor/3.5.0/docs/htmldocs/Samba3-ByExample/primer.html

Last change on this file was 414, checked in by Herwig Bauernfeind, 15 years ago

Samba 3.5.0: Initial import
File size: 56.1 KB
Line 
1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 16. Networking Primer</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="Samba-3 by Example"><link rel="up" href="RefSection.html" title="Part III. Reference Section"><link rel="prev" href="appendix.html" title="Chapter 15. A Collection of Useful Tidbits"><link rel="next" href="apa.html" title="Appendix A.  GNU General Public License version 3"></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 16. Networking Primer</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="appendix.html">Prev</a> </td><th width="60%" align="center">Part III. Reference Section</th><td width="20%" align="right"> <a accesskey="n" href="apa.html">Next</a></td></tr></table><hr></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="primer"></a>Chapter 16. Networking Primer</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="primer.html#id2625280">Requirements and Notes</a></span></dt><dt><span class="sect1"><a href="primer.html#id2625441">Introduction</a></span></dt><dd><dl><dt><span class="sect2"><a href="primer.html#id2625502">Assignment Tasks</a></span></dt></dl></dd><dt><span class="sect1"><a href="primer.html#id2625618">Exercises</a></span></dt><dd><dl><dt><span class="sect2"><a href="primer.html#id2625744">Single-Machine Broadcast Activity</a></span></dt><dt><span class="sect2"><a href="primer.html#secondmachine">Second Machine Startup Broadcast Interaction</a></span></dt><dt><span class="sect2"><a href="primer.html#id2626892">Simple Windows Client Connection Characteristics</a></span></dt><dt><span class="sect2"><a href="primer.html#id2627394">Windows 200x/XP Client Interaction with Samba-3</a></span></dt><dt><span class="sect2"><a href="primer.html#id2627962">Conclusions to Exercises</a></span></dt></dl></dd><dt><span class="sect1"><a href="primer.html#chap01conc">Dissection and Discussion</a></span></dt><dd><dl><dt><span class="sect2"><a href="primer.html#id2628077">Technical Issues</a></span></dt></dl></dd><dt><span class="sect1"><a href="primer.html#chap01qa">Questions and Answers</a></span></dt></dl></div><p>
2 You are about to use the equivalent of a microscope to look at the information
3 that runs through the veins of a Windows network. We do more to observe the information than
4 to interrogate it. When you are done with this primer, you should have a good understanding
5 of the types of information that flow over the network. Do not worry, this is not
6 a biology lesson. We won't lose you in unnecessary detail. Think to yourself, &#8220;<span class="quote">This
7 is easy,</span>&#8221; then tackle each exercise without fear.
8 </p><p>
9 Samba can be configured with a minimum of complexity. Simplicity should be mastered
10 before you get too deeply into complexities. Let's get moving: we have work to do.
11 </p><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2625280"></a>Requirements and Notes</h2></div></div></div><p>
12 Successful completion of this primer requires two Microsoft Windows 9x/Me Workstations
13 as well as two Microsoft Windows XP Professional Workstations, each equipped with an Ethernet
14 card connected using a hub. Also required is one additional server (either Windows
15 NT4 Server, Windows 2000 Server, or a Samba-3 on UNIX/Linux server) running a network
16 sniffer and analysis application (Wireshark is a good choice). All work should be undertaken
17 on a quiet network where there is no other traffic. It is best to use a dedicated hub
18 with only the machines under test connected at the time of the exercises.
19 </p><p><a class="indexterm" name="id2625300"></a>
20 Wireshark (formerly Ethereal) has become the network protocol analyzer of choice for many network administrators.
21 You may find more information regarding this tool from the
22 <a class="ulink" href="http://www.wireshark.org" target="_top">Wireshark</a> Web site. Wireshark installation
23 files for Windows may be obtained from the Wireshark Web site. Wireshark is provided with
24 SUSE and Red Hat Linux distributions, as well as with many other Linux distributions. It may
25 not be installed on your system by default. If it is not installed, you may also need
26 to install the <code class="literal">libpcap</code> software before you can install or use Wireshark.
27 Please refer to the instructions for your operating system or to the Wireshark Web site
28 for information regarding the installation and operation of Wireshark.
29 </p><p>
30 To obtain <code class="literal">Wireshark</code> for your system, please visit the Wireshark
31 <a class="ulink" href="http://www.wireshark.org/download.html" target="_top">download site</a>.
32 </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
33 The successful completion of this chapter requires that you capture network traffic
34 using <code class="literal">Wireshark</code>. It is recommended that you use a hub, not an
35 Ethernet switch. It is necessary for the device used to act as a repeater, not as a
36 filter. Ethernet switches may filter out traffic that is not directed at the machine
37 that is used to monitor traffic; this would not allow you to complete the projects.
38 </p></div><p>
39 <a class="indexterm" name="id2625370"></a>
40 Do not worry too much if you do not have access to all this equipment; network captures
41 from the exercises are provided on the enclosed CD-ROM. This makes it possible to dive directly
42 into the analytical part of the exercises if you so desire.
43 </p><p><a class="indexterm" name="id2625386"></a><a class="indexterm" name="id2625397"></a>
44 Please do not be alarmed at the use of a high-powered analysis tool (Wireshark) in this
45 primer. We expose you only to a minimum of detail necessary to complete
46 the exercises. If you choose to use any other network sniffer and protocol
47 analysis tool, be advised that it may not allow you to examine the contents of
48 recently added security protocols used by Windows 200x/XP.
49 </p><p>
50 You could just skim through the exercises and try to absorb the key points made.
51 The exercises provide all the information necessary to convince the die-hard network
52 engineer. You possibly do not require so much convincing and may just want to move on,
53 in which case you should at least read <a class="link" href="primer.html#chap01conc" title="Dissection and Discussion">&#8220;Dissection and Discussion&#8221;</a>.
54 </p><p>
55 <a class="link" href="primer.html#chap01qa" title="Questions and Answers">&#8220;Questions and Answers&#8221;</a> also provides useful information
56 that may help you to avoid significantly time-consuming networking problems.
57 </p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2625441"></a>Introduction</h2></div></div></div><p>
58 The purpose of this chapter is to create familiarity with key aspects of Microsoft Windows
59 network computing. If you want a solid technical grounding, do not gloss over these exercises.
60 The points covered are recurrent issues on the Samba mailing lists.
61 </p><p><a class="indexterm" name="id2625456"></a>
62 You can see from these exercises that Windows networking involves quite a lot of network
63 broadcast traffic. You can look into the contents of some packets, but only to see
64 some particular information that the Windows client sends to a server in the course of
65 establishing a network connection.
66 </p><p>
67 To many people, browsing is everything that happens when one uses Microsoft Internet Explorer.
68 It is only when you start looking at network traffic and noting the protocols
69 and types of information that are used that you can begin to appreciate the complexities of
70 Windows networking and, more importantly, what needs to be configured so that it can work.
71 Detailed information regarding browsing is provided in the recommended
72 preparatory reading.
73 </p><p>
74 Recommended preparatory reading: <span class="emphasis"><em>The Official Samba-3 HOWTO and Reference Guide, Second
75 Edition</em></span> (TOSHARG2) Chapter 9, &#8220;<span class="quote">Network Browsing,</span>&#8221; and Chapter 3,
76 &#8220;<span class="quote">Server Types and Security Modes.</span>&#8221;
77 </p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2625502"></a>Assignment Tasks</h3></div></div></div><p><a class="indexterm" name="id2625508"></a>
78 You are about to witness how Microsoft Windows computer networking functions. The
79 exercises step through identification of how a client machine establishes a
80 connection to a remote Windows server. You observe how Windows machines find
81 each other (i.e., how browsing works) and how the two key types of user identification
82 (share mode security and user mode security) are affected.
83 </p><p><a class="indexterm" name="id2625526"></a>
84 The networking protocols used by MS Windows networking when working with Samba
85 use TCP/IP as the transport protocol. The protocols that are specific to Windows
86 networking are encapsulated in TCP/IP. The network analyzer we use (Wireshark)
87 is able to show you the contents of the TCP/IP packets (or messages).
88 </p><div class="procedure"><a name="chap01tasks"></a><p class="title"><b>Procedure 16.1. Diagnostic Tasks</b></p><ol type="1"><li><p><a class="indexterm" name="id2625559"></a><a class="indexterm" name="id2625570"></a><a class="indexterm" name="id2625578"></a>
89 Examine network traces to witness SMB broadcasts, host announcements,
90 and name resolution processes.
91 </p></li><li><p>
92 Examine network traces to witness how share mode security functions.
93 </p></li><li><p>
94 Examine network traces to witness the use of user mode security.
95 </p></li><li><p>
96 Review traces of network logons for a Windows 9x/Me client as well as
97 a domain logon for a Windows XP Professional client.
98 </p></li></ol></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2625618"></a>Exercises</h2></div></div></div><p>
99 <a class="indexterm" name="id2625626"></a>
100 You are embarking on a course of discovery. The first part of the exercise requires
101 two MS Windows 9x/Me systems. We called one machine <code class="constant">WINEPRESSME</code> and the
102 other <code class="constant">MILGATE98</code>. Each needs an IP address; we used <code class="literal">10.1.1.10</code>
103 and <code class="literal">10.1.1.11</code>. The test machines need to be networked via a <span class="emphasis"><em>hub</em></span>. A UNIX/Linux
104 machine is required to run <code class="literal">Wireshark</code> to enable the network activity to be captured.
105 It is important that the machine from which network activity is captured must not interfere with
106 the operation of the Windows workstations. It is helpful for this machine to be passive (does not
107 send broadcast information) to the network.
108 </p><p>
109 For these exercises, our test environment consisted of a SUSE 9.2 Professional Linux Workstation running
110 VMWare 4.5. The following VMWare images were prepared:
111 </p><div class="itemizedlist"><ul type="disc"><li><p>Windows 98 name: MILGATE98</p></li><li><p>Windows Me name: WINEPRESSME</p></li><li><p>Windows XP Professional name: LightrayXP</p></li><li><p>Samba-3.0.20 running on a SUSE Enterprise Linux 9</p></li></ul></div><p>
112 Choose a workgroup name (MIDEARTH) for each exercise.
113 </p><p>
114 <a class="indexterm" name="id2625715"></a>
115 The network captures provided on the CD-ROM included with this book were captured using <code class="constant">Ethereal</code>
116 version <code class="literal">0.10.6</code>. A later version suffices without problems (i.e. you should be using Wireshark), but an earlier version may not
117 expose all the information needed. Each capture file has been decoded and listed as a trace file. A summary of all
118 packets has also been included. This makes it possible for you to do all the studying you like without the need to
119 perform the time-consuming equipment configuration and test work. This is a good time to point out that the value
120 that can be derived from this book really does warrant your taking sufficient time to practice each exercise with
121 care and attention to detail.
122 </p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2625744"></a>Single-Machine Broadcast Activity</h3></div></div></div><p>
123 In this section, we start a single Windows 9x/Me machine, then monitor network activity for 30 minutes.
124 </p><div class="procedure"><a name="id2625755"></a><p class="title"><b>Procedure 16.2. Monitoring Windows 9x Steps</b></p><ol type="1"><li><p>
125 Start the machine from which network activity will be monitored (using <code class="literal">Wireshark</code>).
126 Launch <code class="literal">Wireshark</code>, click
127 <span class="guimenu">Capture</span> &#8594; <span class="guimenuitem">Start</span>.
128 </p><p>
129 Click the following:
130 </p><div class="orderedlist"><ol type="1"><li><p>Update list of packets in real time</p></li><li><p>Automatic scrolling in live capture</p></li><li><p>Enable MAC name resolution</p></li><li><p>Enable network name resolution</p></li><li><p>Enable transport name resolution</p></li></ol></div><p>
131 Click <span class="guibutton">OK</span>.
132 </p></li><li><p>
133 Start the Windows 9x/Me machine to be monitored. Let it run for a full 30 minutes. While monitoring,
134 do not press any keyboard keys, do not click any on-screen icons or menus, and do not answer any dialog boxes.
135 </p></li><li><p>
136 At the conclusion of 30 minutes, stop the capture. Save the capture to a file so you can go back to it later.
137 Leave this machine running in preparation for the task in <a class="link" href="primer.html#secondmachine" title="Second Machine Startup Broadcast Interaction">&#8220;Second Machine Startup Broadcast Interaction&#8221;</a>.
138 </p></li><li><p>
139 Analyze the capture. Identify each discrete message type that was captured. Note what transport protocol
140 was used. Identify the timing between messages of identical types.
141 </p></li></ol></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2625878"></a>Findings</h4></div></div></div><p>
142 The summary of the first 10 minutes of the packet capture should look like <a class="link" href="primer.html#pktcap01" title="Figure 16.1. Windows Me Broadcasts The First 10 Minutes">&#8220;Windows Me Broadcasts The First 10 Minutes&#8221;</a>.
143 A screenshot of a later stage of the same capture is shown in <a class="link" href="primer.html#pktcap02" title="Figure 16.2. Windows Me Later Broadcast Sample">&#8220;Windows Me Later Broadcast Sample&#8221;</a>.
144 </p><div class="figure"><a name="pktcap01"></a><p class="title"><b>Figure 16.1. Windows Me Broadcasts The First 10 Minutes</b></p><div class="figure-contents"><div class="mediaobject"><img src="images/WINREPRESSME-Capture.png" width="216" alt="Windows Me Broadcasts The First 10 Minutes"></div></div></div><br class="figure-break"><div class="figure"><a name="pktcap02"></a><p class="title"><b>Figure 16.2. Windows Me Later Broadcast Sample</b></p><div class="figure-contents"><div class="mediaobject"><img src="images/WINREPRESSME-Capture2.png" width="226.8" alt="Windows Me Later Broadcast Sample"></div></div></div><br class="figure-break"><p><a class="indexterm" name="id2625995"></a><a class="indexterm" name="id2626006"></a>
145 Broadcast messages observed are shown in <a class="link" href="primer.html#capsstats01" title="Table 16.1. Windows Me Startup Broadcast Capture Statistics">&#8220;Windows Me Startup Broadcast Capture Statistics&#8221;</a>.
146 Actual observations vary a little, but not by much.
147 Early in the startup process, the Windows Me machine broadcasts its name for two reasons:
148 first to ensure that its name would not result in a name clash, and second to establish its
149 presence with the Local Master Browser (LMB).
150 </p><div class="table"><a name="capsstats01"></a><p class="title"><b>Table 16.1. Windows Me Startup Broadcast Capture Statistics</b></p><div class="table-contents"><table summary="Windows Me Startup Broadcast Capture Statistics" border="1"><colgroup><col align="left"><col align="center"><col align="center"><col align="left"></colgroup><thead><tr><th align="left">Message</th><th align="center">Type</th><th align="center">Num</th><th align="left">Notes</th></tr></thead><tbody><tr><td align="left">WINEPRESSME&lt;00&gt;</td><td align="center">Reg</td><td align="center">8</td><td align="left">4 lots of 2, 0.6 sec apart</td></tr><tr><td align="left">WINEPRESSME&lt;03&gt;</td><td align="center">Reg</td><td align="center">8</td><td align="left">4 lots of 2, 0.6 sec apart</td></tr><tr><td align="left">WINEPRESSME&lt;20&gt;</td><td align="center">Reg</td><td align="center">8</td><td align="left">4 lots of 2, 0.75 sec apart</td></tr><tr><td align="left">MIDEARTH&lt;00&gt;</td><td align="center">Reg</td><td align="center">8</td><td align="left">4 lots of 2, 0.75 sec apart</td></tr><tr><td align="left">MIDEARTH&lt;1d&gt;</td><td align="center">Reg</td><td align="center">8</td><td align="left">4 lots of 2, 0.75 sec apart</td></tr><tr><td align="left">MIDEARTH&lt;1e&gt;</td><td align="center">Reg</td><td align="center">8</td><td align="left">4 lots of 2, 0.75 sec apart</td></tr><tr><td align="left">MIDEARTH&lt;1b&gt;</td><td align="center">Qry</td><td align="center">84</td><td align="left">300 sec apart at stable operation</td></tr><tr><td align="left">__MSBROWSE__</td><td align="center">Reg</td><td align="center">8</td><td align="left">Registered after winning election to Browse Master</td></tr><tr><td align="left">JHT&lt;03&gt;</td><td align="center">Reg</td><td align="center">8</td><td align="left">4 x 2. This is the name of the user that logged onto Windows</td></tr><tr><td align="left">Host Announcement WINEPRESSME</td><td align="center">Ann</td><td align="center">2</td><td align="left">Observed at 10 sec</td></tr><tr><td align="left">Domain/Workgroup Announcement MIDEARTH</td><td align="center">Ann</td><td align="center">18</td><td align="left">300 sec apart at stable operation</td></tr><tr><td align="left">Local Master Announcement WINEPRESSME</td><td align="center">Ann</td><td align="center">18</td><td align="left">300 sec apart at stable operation</td></tr><tr><td align="left">Get Backup List Request</td><td align="center">Qry</td><td align="center">12</td><td align="left">6 x 2 early in startup, 0.5 sec apart</td></tr><tr><td align="left">Browser Election Request</td><td align="center">Ann</td><td align="center">10</td><td align="left">5 x 2 early in startup</td></tr><tr><td align="left">Request Announcement WINEPRESSME</td><td align="center">Ann</td><td align="center">4</td><td align="left">Early in startup</td></tr></tbody></table></div></div><br class="table-break"><p><a class="indexterm" name="id2626353"></a><a class="indexterm" name="id2626361"></a>
151 From the packet trace, it should be noted that no messages were propagated over TCP/IP;
152 all messages employed UDP/IP. When steady-state operation has been achieved, there is a cycle
153 of various announcements, re-election of a browse master, and name queries. These create
154 the symphony of announcements by which network browsing is made possible.
155 </p><p><a class="indexterm" name="id2626379"></a>
156 For detailed information regarding the precise behavior of the CIFS/SMB protocols,
157 refer to the book &#8220;<span class="quote">Implementing CIFS: The Common Internet File System,</span>&#8221;
158 by Christopher Hertel, (Prentice Hall PTR, ISBN: 013047116X).
159 </p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="secondmachine"></a>Second Machine Startup Broadcast Interaction</h3></div></div></div><p>
160 At this time, the machine you used to capture the single-system startup trace should still be running.
161 The objective of this task is to identify the interaction of two machines in respect to broadcast activity.
162 </p><div class="procedure"><a name="id2626415"></a><p class="title"><b>Procedure 16.3. Monitoring of Second Machine Activity</b></p><ol type="1"><li><p>
163 On the machine from which network activity will be monitored (using <code class="literal">Wireshark</code>),
164 launch <code class="literal">Wireshark</code> and click
165 <span class="guimenu">Capture</span> &#8594; <span class="guimenuitem">Start</span>.
166 </p><p>
167 Click:
168 </p><div class="orderedlist"><ol type="1"><li><p>Update list of packets in real time</p></li><li><p>Automatic scrolling in live capture</p></li><li><p>Enable MAC name resolution</p></li><li><p>Enable network name resolution</p></li><li><p>Enable transport name resolution</p></li></ol></div><p>
169 Click <span class="guibutton">OK</span>.
170 </p></li><li><p>
171 Start the second Windows 9x/Me machine. Let it run for 15 to 20 minutes. While monitoring, do not press
172 any keyboard keys, do not click any on-screen icons or menus, and do not answer any dialog boxes.
173 </p></li><li><p>
174 At the conclusion of the capture time, stop the capture. Be sure to save the captured data so you
175 can examine the network data capture again at a later date should that be necessary.
176 </p></li><li><p>
177 Analyze the capture trace, taking note of the transport protocols used, the types of messages observed,
178 and what interaction took place between the two machines. Leave both machines running for the next task.
179 </p></li></ol></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2626531"></a>Findings</h4></div></div></div><p>
180 <a class="link" href="primer.html#capsstats02" title="Table 16.2. Second Machine (Windows 98) Capture Statistics">&#8220;Second Machine (Windows 98) Capture Statistics&#8221;</a> summarizes capture statistics observed. As in the previous case,
181 all announcements used UDP/IP broadcasts. Also, as was observed with the last example, the second
182 Windows 9x/Me machine broadcasts its name on startup to ensure that there exists no name clash
183 (i.e., the name is already registered by another machine) on the network segment. Those wishing
184 to explore the inner details of the precise mechanism of how this functions should refer to
185 &#8220;<span class="quote">Implementing CIFS: The Common Internet File System.</span>&#8221;
186 </p><div class="table"><a name="capsstats02"></a><p class="title"><b>Table 16.2. Second Machine (Windows 98) Capture Statistics</b></p><div class="table-contents"><table summary="Second Machine (Windows 98) Capture Statistics" border="1"><colgroup><col align="left"><col align="center"><col align="center"><col align="left"></colgroup><thead><tr><th align="left">Message</th><th align="center">Type</th><th align="center">Num</th><th align="left">Notes</th></tr></thead><tbody><tr><td align="left">MILGATE98&lt;00&gt;</td><td align="center">Reg</td><td align="center">8</td><td align="left">4 lots of 2, 0.6 sec apart</td></tr><tr><td align="left">MILGATE98&lt;03&gt;</td><td align="center">Reg</td><td align="center">8</td><td align="left">4 lots of 2, 0.6 sec apart</td></tr><tr><td align="left">MILGATE98&lt;20&gt;</td><td align="center">Reg</td><td align="center">8</td><td align="left">4 lots of 2, 0.75 sec apart</td></tr><tr><td align="left">MIDEARTH&lt;00&gt;</td><td align="center">Reg</td><td align="center">8</td><td align="left">4 lots of 2, 0.75 sec apart</td></tr><tr><td align="left">MIDEARTH&lt;1d&gt;</td><td align="center">Reg</td><td align="center">8</td><td align="left">4 lots of 2, 0.75 sec apart</td></tr><tr><td align="left">MIDEARTH&lt;1e&gt;</td><td align="center">Reg</td><td align="center">8</td><td align="left">4 lots of 2, 0.75 sec apart</td></tr><tr><td align="left">MIDEARTH&lt;1b&gt;</td><td align="center">Qry</td><td align="center">18</td><td align="left">900 sec apart at stable operation</td></tr><tr><td align="left">JHT&lt;03&gt;</td><td align="center">Reg</td><td align="center">2</td><td align="left">This is the name of the user that logged onto Windows</td></tr><tr><td align="left">Host Announcement MILGATE98</td><td align="center">Ann</td><td align="center">14</td><td align="left">Every 120 sec</td></tr><tr><td align="left">Domain/Workgroup Announcement MIDEARTH</td><td align="center">Ann</td><td align="center">6</td><td align="left">900 sec apart at stable operation</td></tr><tr><td align="left">Local Master Announcement WINEPRESSME</td><td align="center">Ann</td><td align="center">6</td><td align="left">Insufficient detail to determine frequency</td></tr></tbody></table></div></div><br class="table-break"><p>
187 <a class="indexterm" name="id2626813"></a>
188 <a class="indexterm" name="id2626820"></a>
189 <a class="indexterm" name="id2626827"></a>
190 Observation of the contents of Host Announcements, Domain/Workgroup Announcements,
191 and Local Master Announcements is instructive. These messages convey a significant
192 level of detail regarding the nature of each machine that is on the network. An example
193 dissection of a Host Announcement is given in <a class="link" href="primer.html#hostannounce" title="Figure 16.3. Typical Windows 9x/Me Host Announcement">&#8220;Typical Windows 9x/Me Host Announcement&#8221;</a>.
194 </p><div class="figure"><a name="hostannounce"></a><p class="title"><b>Figure 16.3. Typical Windows 9x/Me Host Announcement</b></p><div class="figure-contents"><div class="mediaobject"><img src="images/HostAnnouncment.png" width="221.4" alt="Typical Windows 9x/Me Host Announcement"></div></div></div><br class="figure-break"></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2626892"></a>Simple Windows Client Connection Characteristics</h3></div></div></div><p>
195 The purpose of this exercise is to discover how Microsoft Windows clients create (establish)
196 connections with remote servers. The methodology involves analysis of a key aspect of how
197 Windows clients access remote servers: the session setup protocol.
198 </p><div class="procedure"><a name="id2626906"></a><p class="title"><b>Procedure 16.4. Client Connection Exploration Steps</b></p><ol type="1"><li><p>
199 Configure a Windows 9x/Me machine (MILGATE98) with a share called <code class="constant">Stuff</code>.
200 Create a <em class="parameter"><code>Full Access</code></em> control password on this share.
201 </p></li><li><p>
202 Configure another Windows 9x/Me machine (WINEPRESSME) as a client. Make sure that it exports
203 no shared resources.
204 </p></li><li><p>
205 Start both Windows 9x/Me machines and allow them to stabilize for 10 minutes. Log on to both
206 machines using a user name (JHT) of your choice. Wait approximately 2 minutes before proceeding.
207 </p></li><li><p>
208 Start Wireshark (or the network sniffer of your choice).
209 </p></li><li><p>
210 From the WINEPRESSME machine, right-click <span class="guimenu">Network Neighborhood</span>, select
211 <span class="guimenuitem">Explore</span>, select
212 <span class="guimenuitem">My Network Places</span> &#8594; <span class="guimenuitem">Entire Network</span> &#8594; <span class="guimenuitem">MIDEARTH</span> &#8594; <span class="guimenuitem">MILGATE98</span> &#8594; <span class="guimenuitem">Stuff</span>.
213 Enter the password you set for the <code class="constant">Full Control</code> mode for the
214 <code class="constant">Stuff</code> share.
215 </p></li><li><p>
216 When the share called <code class="constant">Stuff</code> is being displayed, stop the capture.
217 Save the captured data in case it is needed for later analysis.
218 </p></li><li><p>
219 <a class="indexterm" name="id2627037"></a>
220 From the top of the packets captured, scan down to locate the first packet that has
221 interpreted as <code class="constant">Session Setup AndX, User: anonymous; Tree Connect AndX,
222 Path: \\MILGATE98\IPC$</code>.
223 </p></li><li><p><a class="indexterm" name="id2627056"></a><a class="indexterm" name="id2627064"></a>
224 In the dissection (analysis) panel, expand the <code class="constant">SMB, Session Setup AndX Request,
225 and Tree Connect AndX Request</code>. Examine both operations. Identify the name of
226 the user Account and what password was used. The Account name should be empty.
227 This is a <code class="constant">NULL</code> session setup packet.
228 </p></li><li><p>
229 Return to the packet capture sequence. There will be a number of packets that have been
230 decoded of the type <code class="constant">Session Setup AndX</code>. Locate the last such packet
231 that was targeted at the <code class="constant">\\MILGATE98\IPC$</code> service.
232 </p></li><li><p>
233 <a class="indexterm" name="id2627108"></a>
234 <a class="indexterm" name="id2627115"></a>
235 Dissect this packet as per the previous one. This packet should have a password length
236 of 24 (characters) and should have a password field, the contents of which is a
237 long hexadecimal number. Observe the name in the Account field. This is a User Mode
238 session setup packet.
239 </p></li></ol></div><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2627129"></a>Findings and Comments</h4></div></div></div><p>
240 <a class="indexterm" name="id2627138"></a>
241 The <code class="constant">IPC$</code> share serves a vital purpose<sup>[<a name="id2627149" href="#ftn.id2627149" class="footnote">15</a>]</sup>
242 in SMB/CIFS-based networking. A Windows client connects to this resource to obtain the list of
243 resources that are available on the server. The server responds with the shares and print queues that
244 are available. In most but not all cases, the connection is made with a <code class="constant">NULL</code>
245 username and a <code class="constant">NULL</code> password.
246 </p><p>
247 <a class="indexterm" name="id2627169"></a>
248 The two packets examined are material evidence of how Windows clients may
249 interoperate with Samba. Samba requires every connection setup to be authenticated using
250 valid UNIX account credentials (UID/GID). This means that even a <code class="constant">NULL</code>
251 session setup can be established only by automatically mapping it to a valid UNIX
252 account.
253 </p><p>
254 <a class="indexterm" name="id2627189"></a><a class="indexterm" name="id2627195"></a>
255 <a class="indexterm" name="id2627204"></a>
256 Samba has a special name for the <code class="constant">NULL</code>, or empty, user account:
257 it calls it the <a class="link" href="smb.conf.5.html#GUESTACCOUNT" target="_top">guest account</a>. The
258 default value of this parameter is <code class="constant">nobody</code>; however, this can be
259 changed to map the function of the guest account to any other UNIX identity. Some
260 UNIX administrators prefer to map this account to the system default anonymous
261 FTP account. A sample NULL Session Setup AndX packet dissection is shown in
262 <a class="link" href="primer.html#nullconnect" title="Figure 16.4. Typical Windows 9x/Me NULL SessionSetUp AndX Request">&#8220;Typical Windows 9x/Me NULL SessionSetUp AndX Request&#8221;</a>.
263 </p><div class="figure"><a name="nullconnect"></a><p class="title"><b>Figure 16.4. Typical Windows 9x/Me NULL SessionSetUp AndX Request</b></p><div class="figure-contents"><div class="mediaobject"><img src="images/NullConnect.png" width="221.4" alt="Typical Windows 9x/Me NULL SessionSetUp AndX Request"></div></div></div><br class="figure-break"><p>
264 <a class="indexterm" name="id2627289"></a>
265 <a class="indexterm" name="id2627296"></a>
266 <a class="indexterm" name="id2627303"></a>
267 When a UNIX/Linux system does not have a <code class="constant">nobody</code> user account
268 (<code class="filename">/etc/passwd</code>), the operation of the <code class="constant">NULL</code>
269 account cannot validate and thus connections that utilize the guest account
270 fail. This breaks all ability to browse the Samba server and is a common
271 problem reported on the Samba mailing list. A sample User Mode session setup AndX
272 is shown in <a class="link" href="primer.html#userconnect" title="Figure 16.5. Typical Windows 9x/Me User SessionSetUp AndX Request">&#8220;Typical Windows 9x/Me User SessionSetUp AndX Request&#8221;</a>.
273 </p><div class="figure"><a name="userconnect"></a><p class="title"><b>Figure 16.5. Typical Windows 9x/Me User SessionSetUp AndX Request</b></p><div class="figure-contents"><div class="mediaobject"><img src="images/UserConnect.png" width="221.4" alt="Typical Windows 9x/Me User SessionSetUp AndX Request"></div></div></div><br class="figure-break"><p>
274 <a class="indexterm" name="id2627380"></a>
275 The User Mode connection packet contains the account name and the domain name.
276 The password is provided in Microsoft encrypted form, and its length is shown
277 as 24 characters. This is the length of Microsoft encrypted passwords.
278 </p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2627394"></a>Windows 200x/XP Client Interaction with Samba-3</h3></div></div></div><p>
279 By now you may be asking, &#8220;<span class="quote">Why did you choose to work with Windows 9x/Me?</span>&#8221;
280 </p><p>
281 First, we want to demonstrate the simple case. This book is not intended to be a detailed treatise
282 on the Windows networking protocols, but rather to provide prescriptive guidance for deployment of Samba.
283 Second, by starting out with the simple protocol, it can be demonstrated that the more complex case mostly
284 follows the same principles.
285 </p><p>
286 The following exercise demonstrates the case that even MS Windows XP Professional with up-to-date service
287 updates also uses the <code class="constant">NULL</code> account, as well as user accounts. Simply follow the procedure
288 to complete this exercise.
289 </p><p>
290 To complete this exercise, you need a Windows XP Professional client that has been configured as
291 a domain member of either a Samba-controlled domain or a Windows NT4 or 200x Active Directory domain.
292 Here we do not provide details for how to configure this, as full coverage is provided earlier in this book.
293 </p><div class="procedure"><a name="id2627437"></a><p class="title"><b>Procedure 16.5. Steps to Explore Windows XP Pro Connection Set-up</b></p><ol type="1"><li><p>
294 Start your domain controller. Also, start the Wireshark monitoring machine, launch Wireshark,
295 and then wait for the next step to complete.
296 </p></li><li><p>
297 Start the Windows XP Client and wait 5 minutes before proceeding.
298 </p></li><li><p>
299 On the machine from which network activity will be monitored (using <code class="literal">Wireshark</code>),
300 launch <code class="literal">Wireshark</code> and click
301 <span class="guimenu">Capture</span> &#8594; <span class="guimenuitem">Start</span>.
302 </p><p>
303 Click:
304 </p><div class="orderedlist"><ol type="1"><li><p>Update list of packets in real time</p></li><li><p>Automatic scrolling in live capture</p></li><li><p>Enable MAC name resolution</p></li><li><p>Enable network name resolution</p></li><li><p>Enable transport name resolution</p></li></ol></div><p>
305 Click <span class="guibutton">OK</span>.
306 </p></li><li><p>
307 On the Windows XP Professional client, press <span class="guimenu">Ctrl-Alt-Delete</span> to bring
308 up the domain logon screen. Log in using valid credentials for a domain user account.
309 </p></li><li><p>
310 Now proceed to connect to the domain controller as follows:
311 <span class="guimenu">Start</span> &#8594; <span class="guimenuitem">(right-click) My Network Places</span> &#8594; <span class="guimenuitem">Explore</span> &#8594; <span class="guimenuitem">{Left Panel} [+] Entire Network</span> &#8594; <span class="guimenuitem">{Left Panel} [+] Microsoft Windows Network</span> &#8594; <span class="guimenuitem">{Left Panel} [+] Midearth</span> &#8594; <span class="guimenuitem">{Left Panel} [+] Frodo</span> &#8594; <span class="guimenuitem">{Left Panel} [+] data</span>. Close the explorer window.
312 </p><p>
313 In this step, our domain name is <code class="constant">Midearth</code>, the domain controller is called
314 <code class="constant">Frodo</code>, and we have connected to a share called <code class="constant">data</code>.
315 </p></li><li><p>
316 Stop the capture on the <code class="literal">Wireshark</code> monitoring machine. Be sure to save the captured data
317 to a file so that you can refer to it again later.
318 </p></li><li><p>
319 If desired, the Windows XP Professional client and the domain controller are no longer needed for exercises
320 in this chapter.
321 </p></li><li><p>
322 <a class="indexterm" name="id2627663"></a>
323 <a class="indexterm" name="id2627670"></a>
324 From the top of the packets captured, scan down to locate the first packet that has
325 interpreted as <code class="constant">Session Setup AndX Request, NTLMSSP_AUTH</code>.
326 </p></li><li><p>
327 <a class="indexterm" name="id2627690"></a>
328 <a class="indexterm" name="id2627697"></a>
329 <a class="indexterm" name="id2627704"></a>
330 In the dissection (analysis) panel, expand the <code class="constant">SMB, Session Setup AndX Request</code>.
331 Expand the packet decode information, beginning at the <code class="constant">Security Blob:</code>
332 entry. Expand the <code class="constant">GSS-API -&gt; SPNEGO -&gt; netTokenTarg -&gt; responseToken -&gt; NTLMSSP</code>
333 keys. This should reveal that this is a <code class="constant">NULL</code> session setup packet.
334 The <code class="constant">User name: NULL</code> so indicates. An example decode is shown in
335 <a class="link" href="primer.html#XPCap01" title="Figure 16.6. Typical Windows XP NULL Session Setup AndX Request">&#8220;Typical Windows XP NULL Session Setup AndX Request&#8221;</a>.
336 </p></li><li><p>
337 Return to the packet capture sequence. There will be a number of packets that have been
338 decoded of the type <code class="constant">Session Setup AndX Request</code>. Click the last such packet that
339 has been decoded as <code class="constant">Session Setup AndX Request, NTLMSSP_AUTH</code>.
340 </p></li><li><p>
341 <a class="indexterm" name="id2627766"></a>
342 In the dissection (analysis) panel, expand the <code class="constant">SMB, Session Setup AndX Request</code>.
343 Expand the packet decode information, beginning at the <code class="constant">Security Blob:</code>
344 entry. Expand the <code class="constant">GSS-API -&gt; SPNEGO -&gt; netTokenTarg -&gt; responseToken -&gt; NTLMSSP</code>
345 keys. This should reveal that this is a <code class="constant">User Mode</code> session setup packet.
346 The <code class="constant">User name: jht</code> so indicates. An example decode is shown in
347 <a class="link" href="primer.html#XPCap02" title="Figure 16.7. Typical Windows XP User Session Setup AndX Request">&#8220;Typical Windows XP User Session Setup AndX Request&#8221;</a>. In this case the user name was <code class="constant">jht</code>. This packet
348 decode includes the <code class="constant">Lan Manager Response:</code> and the <code class="constant">NTLM Response:</code>.
349 The values of these two parameters are the Microsoft encrypted password hashes: respectively, the LanMan
350 password and then the NT (case-preserving) password hash.
351 </p></li><li><p>
352 <a class="indexterm" name="id2627828"></a>
353 <a class="indexterm" name="id2627835"></a>
354 The passwords are 24-character hexadecimal numbers. This packet confirms that this is a User Mode
355 session setup packet.
356 </p></li></ol></div><div class="figure"><a name="XPCap01"></a><p class="title"><b>Figure 16.6. Typical Windows XP NULL Session Setup AndX Request</b></p><div class="figure-contents"><div class="mediaobject"><img src="images/WindowsXP-NullConnection.png" width="270" alt="Typical Windows XP NULL Session Setup AndX Request"></div></div></div><br class="figure-break"><div class="figure"><a name="XPCap02"></a><p class="title"><b>Figure 16.7. Typical Windows XP User Session Setup AndX Request</b></p><div class="figure-contents"><div class="mediaobject"><img src="images/WindowsXP-UserConnection.png" width="270" alt="Typical Windows XP User Session Setup AndX Request"></div></div></div><br class="figure-break"><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2627931"></a>Discussion</h4></div></div></div><p><a class="indexterm" name="id2627938"></a>
357 This exercise demonstrates that, while the specific protocol for the Session Setup AndX is handled
358 in a more sophisticated manner by recent MS Windows clients, the underlying rules or principles
359 remain the same. Thus it is demonstrated that MS Windows XP Professional clients still use a
360 <code class="constant">NULL-Session</code> connection to query and locate resources on an advanced network
361 technology server (one using Windows NT4/200x or Samba). It also demonstrates that an authenticated
362 connection must be made before resources can be used.
363 </p></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2627962"></a>Conclusions to Exercises</h3></div></div></div><p>
364 In summary, the following points have been established in this chapter:
365 </p><div class="itemizedlist"><ul type="disc"><li><p>
366 When NetBIOS over TCP/IP protocols are enabled, MS Windows networking employs broadcast-oriented messaging protocols to provide knowledge of network services.
367 </p></li><li><p>
368 Network browsing protocols query information stored on browse masters that manage
369 information provided by NetBIOS Name Registrations and by way of ongoing host
370 announcements and workgroup announcements.
371 </p></li><li><p>
372 All Samba servers must be configured with a mechanism for mapping the <code class="constant">NULL-Session</code>
373 to a valid but nonprivileged UNIX system account.
374 </p></li><li><p>
375 The use of Microsoft encrypted passwords is built right into the fabric of Windows
376 networking operations. Such passwords cannot be provided from the UNIX <code class="filename">/etc/passwd</code>
377 database and thus must be stored elsewhere on the UNIX system in a manner that Samba can
378 use. Samba-2.x permitted such encrypted passwords to be stored in the <code class="constant">smbpasswd</code>
379 file or in an LDAP database. Samba-3 permits use of multiple <em class="parameter"><code>passdb backend</code></em>
380 databases in concurrent deployment. Refer to <span class="emphasis"><em>TOSHARG2</em></span>, Chapter 10, &#8220;<span class="quote">Account Information Databases.</span>&#8221;
381 </p></li></ul></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="chap01conc"></a>Dissection and Discussion</h2></div></div></div><p>
382 <a class="indexterm" name="id2628050"></a>
383 The exercises demonstrate the use of the <code class="constant">guest</code> account, the way that
384 MS Windows clients and servers resolve computer names to a TCP/IP address, and how connections
385 between a client and a server are established.
386 </p><p>
387 Those wishing background information regarding NetBIOS name types should refer to
388 the Microsoft knowledgebase article
389 <a class="ulink" href="http://support.microsoft.com/support/kb/articles/Q102/78/8.asp" target="_top">Q102878.</a>
390 </p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2628077"></a>Technical Issues</h3></div></div></div><p>
391 <a class="indexterm" name="id2628085"></a>
392 Network browsing involves SMB broadcast announcements, SMB enumeration requests,
393 connections to the <code class="constant">IPC$</code> share, share enumerations, and SMB connection
394 setup processes. The use of anonymous connections to a Samba server involve the use of
395 the <em class="parameter"><code>guest account</code></em> that must map to a valid UNIX UID.
396 </p></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="chap01qa"></a>Questions and Answers</h2></div></div></div><p>
397 The questions and answers given in this section are designed to highlight important aspects of Microsoft
398 Windows networking.
399 </p><div class="qandaset"><dl><dt> <a href="primer.html#id2628131">
400 What is the significance of the MIDEARTH&lt;1b&gt; type query?
401 </a></dt><dt> <a href="primer.html#id2628177">
402 What is the significance of the MIDEARTH&lt;1d&gt; type name registration?
403 </a></dt><dt> <a href="primer.html#id2628251">
404 What is the role and significance of the &lt;01&gt;&lt;02&gt;__MSBROWSE__&lt;02&gt;&lt;01&gt;
405 name registration?
406 </a></dt><dt> <a href="primer.html#id2628284">
407 What is the significance of the MIDEARTH&lt;1e&gt; type name registration?
408 </a></dt><dt> <a href="primer.html#id2628315">
409
410 What is the significance of the guest account in smb.conf?
411 </a></dt><dt> <a href="primer.html#id2628393">
412 Is it possible to reduce network broadcast activity with Samba-3?
413 </a></dt><dt> <a href="primer.html#id2628502">
414 Can I just use plain-text passwords with Samba?
415 </a></dt><dt> <a href="primer.html#id2628589">
416 What parameter in the smb.conf file is used to enable the use of encrypted passwords?
417 </a></dt><dt> <a href="primer.html#id2628630">
418 Is it necessary to specify encrypt passwords = Yes
419 when Samba-3 is configured as a domain member?
420 </a></dt><dt> <a href="primer.html#id2628662">
421 Is it necessary to specify a guest account when Samba-3 is configured
422 as a domain member server?
423 </a></dt></dl><table border="0" summary="Q and A Set"><col align="left" width="1%"><tbody><tr class="question"><td align="left" valign="top"><a name="id2628131"></a><a name="id2628133"></a></td><td align="left" valign="top"><p>
424 What is the significance of the MIDEARTH&lt;1b&gt; type query?
425 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
426 <a class="indexterm" name="id2628145"></a>
427 <a class="indexterm" name="id2628155"></a>
428 This is a broadcast announcement by which the Windows machine is attempting to
429 locate a Domain Master Browser (DMB) in the event that it might exist on the network.
430 Refer to <span class="emphasis"><em>TOSHARG2,</em></span> Chapter 9, Section 9.7, &#8220;<span class="quote">Technical Overview of Browsing,</span>&#8221;
431 for details regarding the function of the DMB and its role in network browsing.
432 </p></td></tr><tr class="question"><td align="left" valign="top"><a name="id2628177"></a><a name="id2628179"></a></td><td align="left" valign="top"><p>
433 What is the significance of the MIDEARTH&lt;1d&gt; type name registration?
434 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
435 <a class="indexterm" name="id2628192"></a>
436 <a class="indexterm" name="id2628201"></a>
437 This name registration records the machine IP addresses of the LMBs.
438 Network clients can query this name type to obtain a list of browser servers from the
439 master browser.
440 </p><p>
441 The LMB is responsible for monitoring all host announcements on the local network and for
442 collating the information contained within them. Using this information, it can provide answers to other Windows
443 network clients that request information such as:
444 </p><div class="itemizedlist"><ul type="disc"><li><p>
445 The list of machines known to the LMB (i.e., the browse list)
446 </p></li><li><p>
447 The IP addresses of all domain controllers known for the domain
448 </p></li><li><p>
449 The IP addresses of LMBs
450 </p></li><li><p>
451 The IP address of the DMB (if one exists)
452 </p></li><li><p>
453 The IP address of the LMB on the local segment
454 </p></li></ul></div></td></tr><tr class="question"><td align="left" valign="top"><a name="id2628251"></a><a name="id2628254"></a></td><td align="left" valign="top"><p>
455 What is the role and significance of the &lt;01&gt;&lt;02&gt;__MSBROWSE__&lt;02&gt;&lt;01&gt;
456 name registration?
457 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
458 <a class="indexterm" name="id2628269"></a>
459 This name is registered by the browse master to broadcast and receive domain announcements.
460 Its scope is limited to the local network segment, or subnet. By querying this name type,
461 master browsers on networks that have multiple domains can find the names of master browsers
462 for each domain.
463 </p></td></tr><tr class="question"><td align="left" valign="top"><a name="id2628284"></a><a name="id2628286"></a></td><td align="left" valign="top"><p>
464 What is the significance of the MIDEARTH&lt;1e&gt; type name registration?
465 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
466 <a class="indexterm" name="id2628298"></a>
467 This name is registered by all browse masters in a domain or workgroup. The registration
468 name type is known as the Browser Election Service. Master browsers register themselves
469 with this name type so that DMBs can locate them to perform cross-subnet
470 browse list updates. This name type is also used to initiate elections for Master Browsers.
471 </p></td></tr><tr class="question"><td align="left" valign="top"><a name="id2628315"></a><a name="id2628317"></a></td><td align="left" valign="top"><p>
472 <a class="indexterm" name="id2628321"></a>
473 What is the significance of the <em class="parameter"><code>guest account</code></em> in smb.conf?
474 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
475 This parameter specifies the default UNIX account to which MS Windows networking
476 NULL session connections are mapped. The default name for the UNIX account used for
477 this mapping is called <code class="constant">nobody</code>. If the UNIX/Linux system that
478 is hosting Samba does not have a <code class="constant">nobody</code> account and an alternate
479 mapping has not been specified, network browsing will not work at all.
480 </p><p>
481 It should be noted that the <em class="parameter"><code>guest account</code></em> is essential to
482 Samba operation. Either the operating system must have an account called <code class="constant">nobody</code>
483 or there must be an entry in the <code class="filename">smb.conf</code> file with a valid UNIX account, such as
484 <a class="link" href="smb.conf.5.html#GUESTACCOUNT" target="_top">guest account = ftp</a>.
485 </p></td></tr><tr class="question"><td align="left" valign="top"><a name="id2628393"></a><a name="id2628395"></a></td><td align="left" valign="top"><p>
486 Is it possible to reduce network broadcast activity with Samba-3?
487 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
488 <a class="indexterm" name="id2628407"></a>
489 <a class="indexterm" name="id2628413"></a>
490 Yes, there are two ways to do this. The first involves use of WINS (See <span class="emphasis"><em>TOSHARG2</em></span>, Chapter 9,
491 Section 9.5, &#8220;<span class="quote">WINS The Windows Inter-networking Name Server</span>&#8221;); the
492 alternate method involves disabling the use of NetBIOS over TCP/IP. This second method requires
493 a correctly configured DNS server (see <span class="emphasis"><em>TOSHARG2</em></span>, Chapter 9, Section 9.3, &#8220;<span class="quote">Discussion</span>&#8221;).
494 </p><p>
495 <a class="indexterm" name="id2628445"></a>
496 <a class="indexterm" name="id2628452"></a>
497 <a class="indexterm" name="id2628461"></a>
498 The use of WINS reduces network broadcast traffic. The reduction is greatest when all network
499 clients are configured to operate in <em class="parameter"><code>Hybrid Mode</code></em>. This can be effected through
500 use of DHCP to set the NetBIOS node type to type 8 for all network clients. Additionally, it is
501 beneficial to configure Samba to use <a class="link" href="smb.conf.5.html#NAMERESOLVEORDER" target="_top">name resolve order = wins host cast</a>.
502 </p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
503 Use of SMB without NetBIOS is possible only on Windows 200x/XP Professional clients and servers, as
504 well as with Samba-3.
505 </p></div></td></tr><tr class="question"><td align="left" valign="top"><a name="id2628502"></a><a name="id2628504"></a></td><td align="left" valign="top"><p>
506 Can I just use plain-text passwords with Samba?
507 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
508 Yes, you can configure Samba to use plain-text passwords, though this does create a few problems.
509 </p><p>
510 First, the use of <code class="filename">/etc/passwd</code>-based plain-text passwords requires that registry
511 modifications be made on all MS Windows client machines to enable plain-text passwords support. This
512 significantly diminishes the security of MS Windows client operation. Many network administrators
513 are bitterly opposed to doing this.
514 </p><p>
515 Second, Microsoft has not maintained plain-text password support since the default setting was made
516 disabling this. When network connections are dropped by the client, it is not possible to re-establish
517 the connection automatically. Users need to log off and then log on again. Plain-text password support
518 may interfere with recent enhancements that are part of the Microsoft move toward a more secure computing
519 environment.
520 </p><p>
521 Samba-3 supports Microsoft encrypted passwords. Be advised not to reintroduce plain-text password handling.
522 Just create user accounts by running <code class="literal">smbpasswd -a 'username'</code>
523 </p><p>
524 It is not possible to add a user to the <em class="parameter"><code>passdb backend</code></em> database unless there is
525 a UNIX system account for that user. On systems that run <code class="literal">winbindd</code> to access the Samba
526 PDC/BDC to provide Windows user and group accounts, the <em class="parameter"><code>idmap uid, idmap gid</code></em> ranges
527 set in the <code class="filename">smb.conf</code> file provide the local UID/GIDs needed for local identity management purposes.
528 </p></td></tr><tr class="question"><td align="left" valign="top"><a name="id2628589"></a><a name="id2628591"></a></td><td align="left" valign="top"><p>
529 What parameter in the <code class="filename">smb.conf</code> file is used to enable the use of encrypted passwords?
530 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
531 The parameter in the <code class="filename">smb.conf</code> file that controls this behavior is known as <em class="parameter"><code>encrypt
532 passwords</code></em>. The default setting for this in Samba-3 is <code class="constant">Yes (Enabled)</code>.
533 </p></td></tr><tr class="question"><td align="left" valign="top"><a name="id2628630"></a><a name="id2628632"></a></td><td align="left" valign="top"><p>
534 Is it necessary to specify <a class="link" href="smb.conf.5.html#ENCRYPTPASSWORDS" target="_top">encrypt passwords = Yes</a>
535 when Samba-3 is configured as a domain member?
536 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
537 No. This is the default behavior.
538 </p></td></tr><tr class="question"><td align="left" valign="top"><a name="id2628662"></a><a name="id2628664"></a></td><td align="left" valign="top"><p>
539 Is it necessary to specify a <em class="parameter"><code>guest account</code></em> when Samba-3 is configured
540 as a domain member server?
541 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
542 Yes. This is a local function on the server. The default setting is to use the UNIX account
543 <code class="constant">nobody</code>. If this account does not exist on the UNIX server, then it is
544 necessary to provide a <a class="link" href="smb.conf.5.html#GUESTACCOUNT" target="_top">guest account = an_account</a>,
545 where <code class="constant">an_account</code> is a valid local UNIX user account.
546 </p></td></tr></tbody></table></div></div><div class="footnotes"><br><hr width="100" align="left"><div class="footnote"><p><sup>[<a name="ftn.id2627149" href="#id2627149" class="para">15</a>] </sup>TOSHARG2, Sect 4.5.1</p></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="appendix.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="RefSection.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="apa.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 15. A Collection of Useful Tidbits </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Appendix A. 
547 GNU General Public License version 3
548 </td></tr></table></div></body></html>
Note: See TracBrowser for help on using the repository browser.