docs-xml/Samba3-ByExample/SBE-Appendix2.xml

   1 <?xml version="1.0" encoding="iso-8859-1"?>
   2 <!DOCTYPE chapter PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
   3 <chapter id="primer">
   4   <title>Networking Primer</title>
   5
   6         <para>
   7         You are about to use the equivalent of a microscope to look at the information
   8         that runs through the veins of a Windows network. We do more to observe the information than
   9         to interrogate it. When you are done with this primer, you should have a good understanding
  10         of the types of information that flow over the network. Do not worry, this is not
  11         a biology lesson. We won't lose you in unnecessary detail. Think to yourself, <quote>This
  12         is easy,</quote> then tackle each exercise without fear.
  13         </para>
  14
  15         <para>
  16         Samba can be configured with a minimum of complexity. Simplicity should be mastered
  17         before you get too deeply into complexities. Let's get moving: we have work to do.
  18         </para>
  19
  20 <sect1>
  21         <title>Requirements and Notes</title>
  22         <para>
  23         Successful completion of this primer requires two Microsoft Windows 9x/Me Workstations
  24         as well as two Microsoft Windows XP Professional Workstations, each equipped with an Ethernet
  25         card connected using a hub. Also required is one additional server (either Windows
  26         NT4 Server, Windows 2000 Server, or a Samba-3 on UNIX/Linux server) running a network
  27         sniffer and analysis application (Wireshark is a good choice). All work should be undertaken
  28         on a quiet network where there is no other traffic. It is best to use a dedicated hub
  29         with only the machines under test connected at the time of the exercises.
  30         </para>
  31
  32       <para><indexterm>
  33           <primary>Wireshark</primary>
  34         </indexterm>
  35         Wireshark (formerly Ethereal) has become the network protocol analyzer of choice for many network administrators.
  36         You may find more information regarding this tool from the
  37         <ulink url="http://www.wireshark.org">Wireshark</ulink> Web site. Wireshark installation
  38         files for Windows may be obtained from the Wireshark Web site. Wireshark is provided with
  39         SUSE and Red Hat Linux distributions, as well as with many other Linux distributions. It may
  40         not be installed on your system by default. If it is not installed, you may also need
  41         to install the <command>libpcap</command> software before you can install or use Wireshark.
  42         Please refer to the instructions for your operating system or to the Wireshark Web site
  43         for information regarding the installation and operation of Wireshark.
  44         </para>
  45
  46         <para>
  47         To obtain <command>Wireshark</command> for your system, please visit the Wireshark
  48         <ulink url="http://www.wireshark.org/download.html">download site</ulink>.
  49         </para>
  50
  51         <note><para>
  52         The successful completion of this chapter requires that you capture network traffic
  53         using <command>Wireshark</command>. It is recommended that you use a hub, not an
  54         Ethernet switch. It is necessary for the device used to act as a repeater, not as a
  55         filter. Ethernet switches may filter out traffic that is not directed at the machine
  56         that is used to monitor traffic; this would not allow you to complete the projects.
  57         </para></note>
  58
  59         <para>
  60         <indexterm><primary>network</primary><secondary>captures</secondary></indexterm>
  61         Do not worry too much if you do not have access to all this equipment; network captures
  62         from the exercises are provided on the enclosed CD-ROM. This makes it possible to dive directly
  63         into the analytical part of the exercises if you so desire.
  64         </para>
  65
  66       <para><indexterm>
  67           <primary>network</primary>
  68           <secondary>sniffer</secondary>
  69         </indexterm><indexterm>
  70           <primary>protocol analysis</primary>
  71         </indexterm>
  72         Please do not be alarmed at the use of a high-powered analysis tool (Wireshark) in this
  73         primer.  We expose you only to a minimum of detail necessary to complete
  74         the exercises. If you choose to use any other network sniffer and protocol
  75         analysis tool, be advised that it may not allow you to examine the contents of
  76         recently added security protocols used by Windows 200x/XP.
  77         </para>
  78
  79         <para>
  80         You could just skim through the exercises and try to absorb the key points made.
  81         The exercises provide all the information necessary to convince the die-hard network
  82         engineer. You possibly do not require so much convincing and may just want to move on,
  83         in which case you should at least read <link linkend="chap01conc"/>.
  84         </para>
  85
  86         <para>
  87         <link linkend="chap01qa"/> also provides useful information
  88         that may help you to avoid significantly time-consuming networking problems.
  89         </para>
  90 </sect1>
  91
  92 <sect1>
  93         <title>Introduction</title>
  94
  95         <para>
  96         The purpose of this chapter is to create familiarity with key aspects of Microsoft Windows
  97         network computing. If you want a solid technical grounding, do not gloss over these exercises.
  98         The points covered are recurrent issues on the Samba mailing lists.
  99         </para>
 100
 101       <para><indexterm>
 102           <primary>network</primary>
 103           <secondary>broadcast</secondary>
 104         </indexterm>
 105         You can see from these exercises that Windows networking involves quite a lot of network
 106         broadcast traffic. You can look into the contents of some packets, but only to see
 107         some particular information that the Windows client sends to a server in the course of
 108         establishing a network connection.
 109         </para>
 110
 111         <para>
 112         To many people, browsing is everything that happens when one uses Microsoft Internet Explorer.
 113         It is only when you start looking at network traffic and noting the protocols
 114         and types of information that are used that you can begin to appreciate the complexities of
 115         Windows networking and, more importantly, what needs to be configured so that it can work.
 116         Detailed information regarding browsing is provided in the recommended
 117         preparatory reading.
 118         </para>
 119
 120         <para>
 121         Recommended preparatory reading: <emphasis>The Official Samba-3 HOWTO and Reference Guide, Second
 122         Edition</emphasis> (TOSHARG2) Chapter 9, <quote>Network Browsing,</quote> and Chapter 3,
 123         <quote>Server Types and Security Modes.</quote>
 124         </para>
 125
 126         <sect2>
 127         <title>Assignment Tasks</title>
 128
 129         <para><indexterm>
 130             <primary>browsing</primary>
 131           </indexterm>
 132                 You are about to witness how Microsoft Windows computer networking functions. The
 133                 exercises step through identification of how a client machine establishes a
 134                 connection to a remote Windows server. You observe how Windows machines find
 135                 each other (i.e., how browsing works) and how the two key types of user identification
 136                 (share mode security and user mode security) are affected.
 137                 </para>
 138
 139         <para><indexterm>
 140             <primary>network</primary>
 141             <secondary>analyzer</secondary>
 142           </indexterm>
 143                 The networking protocols used by MS Windows networking when working with Samba
 144                 use TCP/IP as the transport protocol. The protocols that are specific to Windows
 145                 networking are encapsulated in TCP/IP. The network analyzer we use (Wireshark)
 146                 is able to show you the contents of the TCP/IP packets (or messages).
 147                 </para>
 148
 149                 <procedure id="chap01tasks">
 150                 <title>Diagnostic Tasks</title>
 151
 152           <step><para><indexterm>
 153                 <primary>network</primary>
 154                 <secondary>trace</secondary>
 155               </indexterm><indexterm>
 156                 <primary>host announcement</primary>
 157               </indexterm><indexterm>
 158                 <primary>name resolution</primary>
 159               </indexterm>
 160                         Examine network traces to witness SMB broadcasts, host announcements,
 161                         and name resolution processes.
 162                         </para></step>
 163
 164                         <step><para>
 165                         Examine network traces to witness how share mode security functions.
 166                         </para></step>
 167
 168                         <step><para>
 169                         Examine network traces to witness the use of user mode security.
 170                         </para></step>
 171
 172                         <step><para>
 173                         Review traces of network logons for a Windows 9x/Me client as well as
 174                         a domain logon for a Windows XP Professional client.
 175                         </para></step>
 176                 </procedure>
 177
 178         </sect2>
 179 </sect1>
 180
 181 <sect1>
 182         <title>Exercises</title>
 183
 184         <para>
 185         <indexterm><primary>wireshark</primary></indexterm>
 186         You are embarking on a course of discovery. The first part of the exercise requires
 187         two MS Windows 9x/Me systems. We called one machine <constant>WINEPRESSME</constant> and the
 188         other <constant>MILGATE98</constant>. Each needs an IP address; we used <literal>10.1.1.10</literal>
 189         and <literal>10.1.1.11</literal>. The test machines need to be networked via a <emphasis>hub</emphasis>. A UNIX/Linux
 190         machine is required to run <command>Wireshark</command> to enable the network activity to be captured.
 191         It is important that the machine from which network activity is captured must not interfere with
 192         the operation of the Windows workstations. It is helpful for this machine to be passive (does not
 193         send broadcast information) to the network.
 194         </para>
 195
 196         <para>
 197         For these exercises, our test environment consisted of a SUSE 9.2 Professional Linux Workstation running
 198         VMWare 4.5. The following VMWare images were prepared:
 199         </para>
 200
 201         <itemizedlist>
 202                 <listitem><para>Windows 98 &smbmdash; name: MILGATE98</para></listitem>
 203                 <listitem><para>Windows Me &smbmdash; name: WINEPRESSME</para></listitem>
 204                 <listitem><para>Windows XP Professional &smbmdash; name: LightrayXP</para></listitem>
 205                 <listitem><para>Samba-3.0.20 running on a SUSE Enterprise Linux 9</para></listitem>
 206         </itemizedlist>
 207
 208         <para>
 209         Choose a workgroup name (MIDEARTH) for each exercise.
 210         </para>
 211
 212         <para>
 213         <indexterm><primary>ethereal</primary></indexterm>
 214         The network captures provided on the CD-ROM included with this book were captured using <constant>Ethereal</constant>
 215         version <literal>0.10.6</literal>. A later version suffices without problems (i.e. you should be using Wireshark), but an earlier version may not
 216         expose all the information needed. Each capture file has been decoded and listed as a trace file. A summary of all
 217         packets has also been included. This makes it possible for you to do all the studying you like without the need to
 218         perform the time-consuming equipment configuration and test work. This is a good time to point out that the value
 219         that can be derived from this book really does warrant your taking sufficient time to practice each exercise with
 220         care and attention to detail.
 221         </para>
 222
 223         <sect2>
 224         <title>Single-Machine Broadcast Activity</title>
 225
 226         <para>
 227         In this section, we start a single Windows 9x/Me machine, then monitor network activity for 30 minutes.
 228         </para>
 229
 230         <procedure>
 231         <title>Monitoring Windows 9x Steps</title>
 232
 233                 <step><para>
 234                 Start the machine from which network activity will be monitored (using <command>Wireshark</command>).
 235                 Launch <command>Wireshark</command>, click
 236                         <menuchoice>
 237                                 <guimenu>Capture</guimenu>
 238                                 <guimenuitem>Start</guimenuitem>
 239                         </menuchoice>.
 240                 </para>
 241
 242                 <para>
 243                 Click the following:
 244                 <orderedlist>
 245                 <listitem><para>Update list of packets in real time</para></listitem>
 246                 <listitem><para>Automatic scrolling in live capture</para></listitem>
 247                 <listitem><para>Enable MAC name resolution</para></listitem>
 248                 <listitem><para>Enable network name resolution</para></listitem>
 249                 <listitem><para>Enable transport name resolution</para></listitem>
 250                 </orderedlist>
 251                 Click <guibutton>OK</guibutton>.
 252                 </para></step>
 253
 254                 <step><para>
 255                 Start the Windows 9x/Me machine to be monitored. Let it run for a full 30 minutes. While monitoring,
 256                 do not press any keyboard keys, do not click any on-screen icons or menus, and do not answer any dialog boxes.
 257                 </para></step>
 258
 259                 <step><para>
 260                 At the conclusion of 30 minutes, stop the capture. Save the capture to a file so you can go back to it later.
 261                 Leave this machine running in preparation for the task in <link linkend="secondmachine"/>.
 262                 </para></step>
 263
 264                 <step><para>
 265                 Analyze the capture. Identify each discrete message type that was captured. Note what transport protocol
 266                 was used. Identify the timing between messages of identical types.
 267                 </para></step>
 268
 269         </procedure>
 270
 271                 <sect3>
 272                 <title>Findings</title>
 273
 274                 <para>
 275                 The summary of the first 10 minutes of the packet capture should look like <link linkend="pktcap01"/>.
 276                 A screenshot of a later stage of the same capture is shown in <link linkend="pktcap02"/>.
 277                 </para>
 278
 279                 <figure id="pktcap01">
 280                         <title>Windows Me &smbmdash; Broadcasts &smbmdash; The First 10 Minutes</title>
 281                         <imagefile scale="40">WINREPRESSME-Capture</imagefile>
 282                 </figure>
 283
 284                 <figure id="pktcap02">
 285                         <title>Windows Me &smbmdash; Later Broadcast Sample</title>
 286                         <imagefile scale="42">WINREPRESSME-Capture2</imagefile>
 287                 </figure>
 288
 289           <para><indexterm>
 290               <primary>Local Master Browser</primary>
 291               <see>LMB</see>
 292             </indexterm><indexterm>
 293               <primary>LMB</primary>
 294             </indexterm>
 295                 Broadcast messages observed are shown in <link linkend="capsstats01"/>.
 296                 Actual observations vary a little, but not by much.
 297                 Early in the startup process, the Windows Me machine broadcasts its name for two reasons:
 298                 first to ensure that its name would not result in a name clash, and second to establish its
 299                 presence with the Local Master Browser (LMB).
 300                 </para>
 301
 302                 <table id="capsstats01">
 303                         <title>Windows Me &smbmdash; Startup Broadcast Capture Statistics</title>
 304                         <tgroup cols="4">
 305                                 <colspec align="left" colwidth="3*"/>
 306                                 <colspec align="center"/>
 307                                 <colspec align="center"/>
 308                                 <colspec align="left" colwidth="3*"/>
 309                                 <thead>
 310                                         <row>
 311                                                 <entry>Message</entry>
 312                                                 <entry>Type</entry>
 313                                                 <entry>Num</entry>
 314                                                 <entry>Notes</entry>
 315                                         </row>
 316                                 </thead>
 317                                 <tbody>
 318                                         <row>
 319                                                 <entry>WINEPRESSME&lt;00&gt;</entry>
 320                                                 <entry>Reg</entry>
 321                                                 <entry>8</entry>
 322                                                 <entry>4 lots of 2, 0.6 sec apart</entry>
 323                                         </row>
 324                                         <row>
 325                                                 <entry>WINEPRESSME&lt;03&gt;</entry>
 326                                                 <entry>Reg</entry>
 327                                                 <entry>8</entry>
 328                                                 <entry>4 lots of 2, 0.6 sec apart</entry>
 329                                         </row>
 330                                         <row>
 331                                                 <entry>WINEPRESSME&lt;20&gt;</entry>
 332                                                 <entry>Reg</entry>
 333                                                 <entry>8</entry>
 334                                                 <entry>4 lots of 2, 0.75 sec apart</entry>
 335                                         </row>
 336                                         <row>
 337                                                 <entry>MIDEARTH&lt;00&gt;</entry>
 338                                                 <entry>Reg</entry>
 339                                                 <entry>8</entry>
 340                                                 <entry>4 lots of 2, 0.75 sec apart</entry>
 341                                         </row>
 342                                         <row>
 343                                                 <entry>MIDEARTH&lt;1d&gt;</entry>
 344                                                 <entry>Reg</entry>
 345                                                 <entry>8</entry>
 346                                                 <entry>4 lots of 2, 0.75 sec apart</entry>
 347                                         </row>
 348                                         <row>
 349                                                 <entry>MIDEARTH&lt;1e&gt;</entry>
 350                                                 <entry>Reg</entry>
 351                                                 <entry>8</entry>
 352                                                 <entry>4 lots of 2, 0.75 sec apart</entry>
 353                                         </row>
 354                                         <row>
 355                                                 <entry>MIDEARTH&lt;1b&gt;</entry>
 356                                                 <entry>Qry</entry>
 357                                                 <entry>84</entry>
 358                                                 <entry>300 sec apart at stable operation</entry>
 359                                         </row>
 360                                         <row>
 361                                                 <entry>__MSBROWSE__</entry>
 362                                                 <entry>Reg</entry>
 363                                                 <entry>8</entry>
 364                                                 <entry>Registered after winning election to Browse Master</entry>
 365                                         </row>
 366                                         <row>
 367                                                 <entry>JHT&lt;03&gt;</entry>
 368                                                 <entry>Reg</entry>
 369                                                 <entry>8</entry>
 370                                                 <entry>4 x 2. This is the name of the user that logged onto Windows</entry>
 371                                         </row>
 372                                         <row>
 373                                                 <entry>Host Announcement WINEPRESSME</entry>
 374                                                 <entry>Ann</entry>
 375                                                 <entry>2</entry>
 376                                                 <entry>Observed at 10 sec</entry>
 377                                         </row>
 378                                         <row>
 379                                                 <entry>Domain/Workgroup Announcement MIDEARTH</entry>
 380                                                 <entry>Ann</entry>
 381                                                 <entry>18</entry>
 382                                                 <entry>300 sec apart at stable operation</entry>
 383                                         </row>
 384                                         <row>
 385                                                 <entry>Local Master Announcement WINEPRESSME</entry>
 386                                                 <entry>Ann</entry>
 387                                                 <entry>18</entry>
 388                                                 <entry>300 sec apart at stable operation</entry>
 389                                         </row>
 390                                         <row>
 391                                                 <entry>Get Backup List Request</entry>
 392                                                 <entry>Qry</entry>
 393                                                 <entry>12</entry>
 394                                                 <entry>6 x 2 early in startup, 0.5 sec apart</entry>
 395                                         </row>
 396                                         <row>
 397                                                 <entry>Browser Election Request</entry>
 398                                                 <entry>Ann</entry>
 399                                                 <entry>10</entry>
 400                                                 <entry>5 x 2 early in startup</entry>
 401                                         </row>
 402                                         <row>
 403                                                 <entry>Request Announcement WINEPRESSME</entry>
 404                                                 <entry>Ann</entry>
 405                                                 <entry>4</entry>
 406                                                 <entry>Early in startup</entry>
 407                                         </row>
 408                                 </tbody>
 409                         </tgroup>
 410                 </table>
 411
 412           <para><indexterm>
 413               <primary>election</primary>
 414             </indexterm><indexterm>
 415               <primary>browse master</primary>
 416             </indexterm>
 417                 From the packet trace, it should be noted that no messages were propagated over TCP/IP;
 418                 all messages employed UDP/IP.  When steady-state operation has been achieved, there is a cycle
 419                 of various announcements, re-election of a browse master, and name queries. These create
 420                 the symphony of announcements by which network browsing is made possible.
 421                 </para>
 422
 423           <para><indexterm>
 424               <primary>CIFS</primary>
 425             </indexterm>
 426                 For detailed information regarding the precise behavior of the CIFS/SMB protocols,
 427                 refer to the book <quote>Implementing CIFS: The Common Internet File System,</quote>
 428                 by Christopher Hertel, (Prentice Hall PTR, ISBN: 013047116X).
 429                 </para>
 430
 431                 </sect3>
 432
 433         </sect2>
 434
 435         <sect2 id="secondmachine">
 436         <title>Second Machine Startup Broadcast Interaction</title>
 437
 438         <para>
 439         At this time, the machine you used to capture the single-system startup trace should still be running.
 440         The objective of this task is to identify the interaction of two machines in respect to broadcast activity.
 441         </para>
 442
 443         <procedure>
 444         <title>Monitoring of Second Machine Activity</title>
 445
 446                 <step><para>
 447                 On the machine from which network activity will be monitored (using <command>Wireshark</command>),
 448                 launch <command>Wireshark</command> and click
 449                         <menuchoice>
 450                                 <guimenu>Capture</guimenu>
 451                                 <guimenuitem>Start</guimenuitem>
 452                         </menuchoice>.
 453                 </para>
 454
 455                 <para>
 456                 Click:
 457                 <orderedlist>
 458                         <listitem><para>Update list of packets in real time</para></listitem>
 459                         <listitem><para>Automatic scrolling in live capture</para></listitem>
 460                         <listitem><para>Enable MAC name resolution</para></listitem>
 461                         <listitem><para>Enable network name resolution</para></listitem>
 462                         <listitem><para>Enable transport name resolution</para></listitem>
 463                 </orderedlist>
 464                 Click <guibutton>OK</guibutton>.
 465                 </para></step>
 466
 467                 <step><para>
 468                 Start the second Windows 9x/Me machine. Let it run for 15 to 20 minutes. While monitoring, do not press
 469                 any keyboard keys, do not click any on-screen icons or menus, and do not answer any dialog boxes.
 470                 </para></step>
 471
 472                 <step><para>
 473                 At the conclusion of the capture time, stop the capture. Be sure to save the captured data so you
 474                 can examine the network data capture again at a later date should that be necessary.
 475                 </para></step>
 476
 477                 <step><para>
 478                 Analyze the capture trace, taking note of the transport protocols used, the types of messages observed,
 479                 and what interaction took place between the two machines. Leave both machines running for the next task.
 480                 </para></step>
 481         </procedure>
 482
 483                 <sect3>
 484                 <title>Findings</title>
 485
 486                 <para>
 487                 <link linkend="capsstats02"/> summarizes capture statistics observed. As in the previous case,
 488                 all announcements used UDP/IP broadcasts. Also, as was observed with the last example, the second
 489                 Windows 9x/Me machine broadcasts its name on startup to ensure that there exists no name clash
 490                 (i.e., the name is already registered by another machine) on the network segment. Those wishing
 491                 to explore the inner details of the precise mechanism of how this functions should refer to
 492                 <quote>Implementing CIFS: The Common Internet File System.</quote>
 493                 </para>
 494
 495                 <table id="capsstats02">
 496                         <title>Second Machine (Windows 98) &smbmdash; Capture Statistics</title>
 497                         <tgroup cols="4">
 498                                 <colspec align="left" colwidth="3*"/>
 499                                 <colspec align="center"/>
 500                                 <colspec align="center"/>
 501                                 <colspec align="left" colwidth="3*"/>
 502                                 <thead>
 503                                         <row>
 504                                                 <entry>Message</entry>
 505                                                 <entry>Type</entry>
 506                                                 <entry>Num</entry>
 507                                                 <entry>Notes</entry>
 508                                         </row>
 509                                 </thead>
 510                                 <tbody>
 511                                         <row>
 512                                                 <entry>MILGATE98&lt;00&gt;</entry>
 513                                                 <entry>Reg</entry>
 514                                                 <entry>8</entry>
 515                                                 <entry>4 lots of 2, 0.6 sec apart</entry>
 516                                         </row>
 517                                         <row>
 518                                                 <entry>MILGATE98&lt;03&gt;</entry>
 519                                                 <entry>Reg</entry>
 520                                                 <entry>8</entry>
 521                                                 <entry>4 lots of 2, 0.6 sec apart</entry>
 522                                         </row>
 523                                         <row>
 524                                                 <entry>MILGATE98&lt;20&gt;</entry>
 525                                                 <entry>Reg</entry>
 526                                                 <entry>8</entry>
 527                                                 <entry>4 lots of 2, 0.75 sec apart</entry>
 528                                         </row>
 529                                         <row>
 530                                                 <entry>MIDEARTH&lt;00&gt;</entry>
 531                                                 <entry>Reg</entry>
 532                                                 <entry>8</entry>
 533                                                 <entry>4 lots of 2, 0.75 sec apart</entry>
 534                                         </row>
 535                                         <row>
 536                                                 <entry>MIDEARTH&lt;1d&gt;</entry>
 537                                                 <entry>Reg</entry>
 538                                                 <entry>8</entry>
 539                                                 <entry>4 lots of 2, 0.75 sec apart</entry>
 540                                         </row>
 541                                         <row>
 542                                                 <entry>MIDEARTH&lt;1e&gt;</entry>
 543                                                 <entry>Reg</entry>
 544                                                 <entry>8</entry>
 545                                                 <entry>4 lots of 2, 0.75 sec apart</entry>
 546                                         </row>
 547                                         <row>
 548                                                 <entry>MIDEARTH&lt;1b&gt;</entry>
 549                                                 <entry>Qry</entry>
 550                                                 <entry>18</entry>
 551                                                 <entry>900 sec apart at stable operation</entry>
 552                                         </row>
 553                                         <row>
 554                                                 <entry>JHT&lt;03&gt;</entry>
 555                                                 <entry>Reg</entry>
 556                                                 <entry>2</entry>
 557                                                 <entry>This is the name of the user that logged onto Windows</entry>
 558                                         </row>
 559                                         <row>
 560                                                 <entry>Host Announcement MILGATE98</entry>
 561                                                 <entry>Ann</entry>
 562                                                 <entry>14</entry>
 563                                                 <entry>Every 120 sec</entry>
 564                                         </row>
 565                                         <row>
 566                                                 <entry>Domain/Workgroup Announcement MIDEARTH</entry>
 567                                                 <entry>Ann</entry>
 568                                                 <entry>6</entry>
 569                                                 <entry>900 sec apart at stable operation</entry>
 570                                         </row>
 571                                         <row>
 572                                                 <entry>Local Master Announcement WINEPRESSME</entry>
 573                                                 <entry>Ann</entry>
 574                                                 <entry>6</entry>
 575                                                 <entry>Insufficient detail to determine frequency</entry>
 576                                         </row>
 577                                 </tbody>
 578                         </tgroup>
 579                 </table>
 580
 581                 <para>
 582                 <indexterm><primary>host announcement</primary></indexterm>
 583                 <indexterm><primary>Local Master Announcement</primary></indexterm>
 584                 <indexterm><primary>Workgroup Announcement</primary></indexterm>
 585                 Observation of the contents of Host Announcements, Domain/Workgroup Announcements,
 586                 and Local Master Announcements is instructive. These messages convey a significant
 587                 level of detail regarding the nature of each machine that is on the network. An example
 588                 dissection of a Host Announcement is given in <link linkend="hostannounce"/>.
 589                 </para>
 590
 591
 592                 <figure id="hostannounce">
 593                         <title>Typical Windows 9x/Me Host Announcement</title>
 594                         <imagefile scale="41">HostAnnouncment</imagefile>
 595                 </figure>
 596                 </sect3>
 597
 598         </sect2>
 599
 600         <sect2>
 601         <title>Simple Windows Client Connection Characteristics</title>
 602
 603         <para>
 604         The purpose of this exercise is to discover how Microsoft Windows clients create (establish)
 605         connections with remote servers. The methodology involves analysis of a key aspect of how
 606         Windows clients access remote servers: the session setup protocol.
 607         </para>
 608
 609         <procedure>
 610         <title>Client Connection Exploration Steps</title>
 611
 612                 <step><para>
 613                 Configure a Windows 9x/Me machine (MILGATE98) with a share called <constant>Stuff</constant>.
 614                 Create a <parameter>Full Access</parameter> control password on this share.
 615                 </para></step>
 616
 617                 <step><para>
 618                 Configure another Windows 9x/Me machine (WINEPRESSME) as a client. Make sure that it exports
 619                 no shared resources.
 620                 </para></step>
 621
 622                 <step><para>
 623                 Start both Windows 9x/Me machines and allow them to stabilize for 10 minutes. Log on to both
 624                 machines using a user name (JHT) of your choice. Wait approximately 2 minutes before proceeding.
 625                 </para></step>
 626
 627                 <step><para>
 628                 Start Wireshark (or the network sniffer of your choice).
 629                 </para></step>
 630
 631                 <step><para>
 632                 From the WINEPRESSME machine, right-click <guimenu>Network Neighborhood</guimenu>, select
 633                 <guimenuitem>Explore</guimenuitem>, select
 634                 <menuchoice>
 635                         <guimenuitem>My Network Places</guimenuitem>
 636                         <guimenuitem>Entire Network</guimenuitem>
 637                         <guimenuitem>MIDEARTH</guimenuitem>
 638                         <guimenuitem>MILGATE98</guimenuitem>
 639                         <guimenuitem>Stuff</guimenuitem>
 640                 </menuchoice>.
 641                 Enter the password you set for the <constant>Full Control</constant> mode for the
 642                 <constant>Stuff</constant> share.
 643                 </para></step>
 644
 645                 <step><para>
 646                 When the share called <constant>Stuff</constant> is being displayed, stop the capture.
 647                 Save the captured data in case it is needed for later analysis.
 648                 </para></step>
 649
 650                 <step><para>
 651                 <indexterm><primary>session setup</primary></indexterm>
 652                 From the top of the packets captured, scan down to locate the first packet that has
 653                 interpreted as <constant>Session Setup AndX, User: anonymous; Tree Connect AndX,
 654                 Path: \\MILGATE98\IPC$</constant>.
 655                 </para></step>
 656
 657           <step><para><indexterm>
 658                 <primary>Session Setup</primary>
 659               </indexterm><indexterm>
 660                 <primary>Tree Connect</primary>
 661               </indexterm>
 662                 In the dissection (analysis) panel, expand the <constant>SMB, Session Setup AndX Request,
 663                 and Tree Connect AndX Request</constant>. Examine both operations. Identify the name of
 664                 the user Account and what password was used. The Account name should be empty.
 665                 This is a <constant>NULL</constant> session setup packet.
 666                 </para></step>
 667
 668                 <step><para>
 669                 Return to the packet capture sequence. There will be a number of packets that have been
 670                 decoded of the type <constant>Session Setup AndX</constant>. Locate the last such packet
 671                 that was targeted at the <constant>\\MILGATE98\IPC$</constant> service.
 672                 </para></step>
 673
 674                 <step><para>
 675                 <indexterm><primary>password length</primary></indexterm>
 676                 <indexterm><primary>User Mode</primary></indexterm>
 677                 Dissect this packet as per the previous one. This packet should have a password length
 678                 of 24 (characters) and should have a password field, the contents of which is a
 679                 long hexadecimal number. Observe the name in the Account field. This is a User Mode
 680                 session setup packet.
 681                 </para></step>
 682         </procedure>
 683
 684                 <sect3>
 685                 <title>Findings and Comments</title>
 686
 687                 <para>
 688                 <indexterm><primary>IPC$</primary></indexterm>
 689                 The <constant>IPC$</constant> share serves a vital purpose<footnote><para>TOSHARG2, Sect 4.5.1</para></footnote>
 690                 in SMB/CIFS-based networking.  A Windows client connects to this resource to obtain the list of
 691                 resources that are available on the server. The server responds with the shares and print queues that
 692                 are available. In most but not all cases, the connection is made with a <constant>NULL</constant>
 693                 username and a <constant>NULL</constant> password.
 694                 </para>
 695
 696                 <para>
 697                 <indexterm><primary>account credentials</primary></indexterm>
 698                 The two packets examined are material evidence of how Windows clients may
 699                 interoperate with Samba. Samba requires every connection setup to be authenticated using
 700                 valid UNIX account credentials (UID/GID). This means that even a <constant>NULL</constant>
 701                 session setup can be established only by automatically mapping it to a valid UNIX
 702                 account.
 703                 </para>
 704
 705                 <para>
 706             <indexterm><primary>NULL session</primary></indexterm><indexterm>
 707               <primary>guest account</primary>
 708             </indexterm>
 709             <indexterm><primary>nobody</primary></indexterm>
 710                 Samba has a special name for the <constant>NULL</constant>, or empty, user account:
 711                 it calls it the <smbconfoption name="guest account"/>. The
 712                 default value of this parameter is <constant>nobody</constant>; however, this can be
 713                 changed to map the function of the guest account to any other UNIX identity. Some
 714                 UNIX administrators prefer to map this account to the system default anonymous
 715                 FTP account. A sample NULL Session Setup AndX packet dissection is shown in
 716                 <link linkend="nullconnect"/>.
 717                 </para>
 718
 719                 <figure id="nullconnect">
 720                         <title>Typical Windows 9x/Me NULL SessionSetUp AndX Request</title>
 721
 722                         <imagefile scale="41">NullConnect</imagefile>
 723                 </figure>
 724
 725                 <para>
 726                 <indexterm><primary>nobody</primary></indexterm>
 727                 <indexterm><primary>/etc/passwd</primary></indexterm>
 728                 <indexterm><primary>guest account</primary></indexterm>
 729                 When a UNIX/Linux system does not have a <constant>nobody</constant> user account
 730                 (<filename>/etc/passwd</filename>), the operation of the <constant>NULL</constant>
 731                 account cannot validate and thus connections that utilize the guest account
 732                 fail. This breaks all ability to browse the Samba server and is a common
 733                 problem reported on the Samba mailing list. A sample User Mode session setup AndX
 734                 is shown in <link linkend="userconnect"/>.
 735                 </para>
 736
 737                 <figure id="userconnect">
 738                         <title>Typical Windows 9x/Me User SessionSetUp AndX Request</title>
 739                         <imagefile scale="41">UserConnect</imagefile>
 740                 </figure>
 741
 742                 <para>
 743                 <indexterm><primary>encrypted</primary></indexterm>
 744                 The User Mode connection packet contains the account name and the domain name.
 745                 The password is provided in Microsoft encrypted form, and its length is shown
 746                 as 24 characters. This is the length of Microsoft encrypted passwords.
 747                 </para>
 748
 749                 </sect3>
 750
 751         </sect2>
 752
 753         <sect2>
 754         <title>Windows 200x/XP Client Interaction with Samba-3</title>
 755
 756         <para>
 757         By now you may be asking, <quote>Why did you choose to work with Windows 9x/Me?</quote>
 758         </para>
 759
 760         <para>
 761         First, we want to demonstrate the simple case. This book is not intended to be a detailed treatise
 762         on the Windows networking protocols, but rather to provide prescriptive guidance for deployment of Samba.
 763         Second, by starting out with the simple protocol, it can be demonstrated that the more complex case mostly
 764         follows the same principles.
 765         </para>
 766
 767         <para>
 768         The following exercise demonstrates the case that even MS Windows XP Professional with up-to-date service
 769         updates also uses the <constant>NULL</constant> account, as well as user accounts. Simply follow the procedure
 770         to complete this exercise.
 771         </para>
 772
 773         <para>
 774         To complete this exercise, you need a Windows XP Professional client that has been configured as
 775         a domain member of either a Samba-controlled domain or a Windows NT4 or 200x Active Directory domain.
 776         Here we do not provide details for how to configure this, as full coverage is provided earlier in this book.
 777         </para>
 778
 779         <procedure>
 780         <title>Steps to Explore Windows XP Pro Connection Set-up</title>
 781
 782                 <step><para>
 783                 Start your domain controller. Also, start the Wireshark monitoring machine, launch Wireshark,
 784                 and then wait for the next step to complete.
 785                 </para></step>
 786
 787                 <step><para>
 788                 Start the Windows XP Client and wait 5 minutes before proceeding.
 789                 </para></step>
 790
 791                 <step><para>
 792                 On the machine from which network activity will be monitored (using <command>Wireshark</command>),
 793                 launch <command>Wireshark</command> and click
 794                         <menuchoice>
 795                                 <guimenu>Capture</guimenu>
 796                                 <guimenuitem>Start</guimenuitem>
 797                         </menuchoice>.
 798                 </para>
 799
 800                 <para>
 801                 Click:
 802                 <orderedlist>
 803                                 <listitem><para>Update list of packets in real time</para></listitem>
 804                                 <listitem><para>Automatic scrolling in live capture</para></listitem>
 805                                 <listitem><para>Enable MAC name resolution</para></listitem>
 806                                 <listitem><para>Enable network name resolution</para></listitem>
 807                                 <listitem><para>Enable transport name resolution</para></listitem>
 808                 </orderedlist>
 809                 Click <guibutton>OK</guibutton>.
 810                 </para></step>
 811
 812                 <step><para>
 813                 On the Windows XP Professional client, press <guimenu>Ctrl-Alt-Delete</guimenu> to bring
 814                 up the domain logon screen. Log in using valid credentials for a domain user account.
 815                 </para></step>
 816
 817                 <step><para>
 818                 Now proceed to connect to the domain controller as follows:
 819                 <menuchoice>
 820                         <guimenu>Start</guimenu>
 821                         <guimenuitem>(right-click) My Network Places</guimenuitem>
 822                         <guimenuitem>Explore</guimenuitem>
 823                         <guimenuitem>{Left Panel} [+] Entire Network</guimenuitem>
 824                         <guimenuitem>{Left Panel} [+] Microsoft Windows Network</guimenuitem>
 825                         <guimenuitem>{Left Panel} [+] Midearth</guimenuitem>
 826                         <guimenuitem>{Left Panel} [+] Frodo</guimenuitem>
 827                         <guimenuitem>{Left Panel} [+] data</guimenuitem>
 828                 </menuchoice>. Close the explorer window.
 829                 </para>
 830
 831                 <para>
 832                 In this step, our domain name is <constant>Midearth</constant>, the domain controller is called
 833                 <constant>Frodo</constant>, and we have connected to a share called <constant>data</constant>.
 834                 </para></step>
 835
 836                 <step><para>
 837                 Stop the capture on the <command>Wireshark</command> monitoring machine. Be sure to save the captured data
 838                 to a file so that you can refer to it again later.
 839                 </para></step>
 840
 841                 <step><para>
 842                 If desired, the Windows XP Professional client and the domain controller are no longer needed for exercises
 843                 in this chapter.
 844                 </para></step>
 845
 846                  <step><para>
 847                 <indexterm><primary>NTLMSSP_AUTH</primary></indexterm>
 848                 <indexterm><primary>session setup</primary></indexterm>
 849                 From the top of the packets captured, scan down to locate the first packet that has
 850                 interpreted as <constant>Session Setup AndX Request, NTLMSSP_AUTH</constant>.
 851                 </para></step>
 852
 853                 <step><para>
 854                 <indexterm><primary>GSS-API</primary></indexterm>
 855                 <indexterm><primary>SPNEGO</primary></indexterm>
 856                 <indexterm><primary>NTLMSSP</primary></indexterm>
 857                 In the dissection (analysis) panel, expand the <constant>SMB, Session Setup AndX Request</constant>.
 858                 Expand the packet decode information, beginning at the <constant>Security Blob:</constant>
 859                 entry. Expand the <constant>GSS-API -> SPNEGO -> netTokenTarg -> responseToken -> NTLMSSP</constant>
 860                 keys.  This should reveal that this is a <constant>NULL</constant> session setup packet.
 861                 The <constant>User name: NULL</constant> so indicates. An example decode is shown in
 862                 <link linkend="XPCap01"/>.
 863                 </para></step>
 864
 865                 <step><para>
 866                 Return to the packet capture sequence. There will be a number of packets that have been
 867                 decoded of the type <constant>Session Setup AndX Request</constant>. Click the last such packet that
 868                 has been decoded as <constant>Session Setup AndX Request, NTLMSSP_AUTH</constant>.
 869                 </para></step>
 870
 871                 <step><para>
 872                 <indexterm><primary>encrypted password</primary></indexterm>
 873                 In the dissection (analysis) panel, expand the <constant>SMB, Session Setup AndX Request</constant>.
 874                 Expand the packet decode information, beginning at the <constant>Security Blob:</constant>
 875                 entry. Expand the <constant>GSS-API -> SPNEGO -> netTokenTarg -> responseToken -> NTLMSSP</constant>
 876                 keys.  This should reveal that this is a <constant>User Mode</constant> session setup packet.
 877                 The <constant>User name: jht</constant> so indicates. An example decode is shown in
 878                 <link linkend="XPCap02"/>. In this case the user name was <constant>jht</constant>. This packet
 879                 decode includes the <constant>Lan Manager Response:</constant> and the <constant>NTLM Response:</constant>.
 880                 The values of these two parameters are the Microsoft encrypted password hashes: respectively, the LanMan
 881                 password and then the NT (case-preserving) password hash.
 882                 </para></step>
 883
 884                 <step><para>
 885                 <indexterm><primary>password length</primary></indexterm>
 886                 <indexterm><primary>User Mode</primary></indexterm>
 887                 The passwords are 24-character hexadecimal numbers. This packet confirms that this is a User Mode
 888                 session setup packet.
 889                 </para></step>
 890
 891         </procedure>
 892
 893         <figure id="XPCap01">
 894         <title>Typical Windows XP NULL Session Setup AndX Request</title>
 895                 <imagefile scale="50">WindowsXP-NullConnection</imagefile>
 896         </figure>
 897
 898         <figure id="XPCap02">
 899         <title>Typical Windows XP User Session Setup AndX Request</title>
 900                 <imagefile scale="50">WindowsXP-UserConnection</imagefile>
 901         </figure>
 902
 903                 <sect3>
 904                 <title>Discussion</title>
 905
 906           <para><indexterm>
 907               <primary>NULL-Session</primary>
 908             </indexterm>
 909                 This exercise demonstrates that, while the specific protocol for the Session Setup AndX is handled
 910                 in a more sophisticated manner by recent MS Windows clients, the underlying rules or principles
 911                 remain the same. Thus it is demonstrated  that MS Windows XP Professional clients still use a
 912                 <constant>NULL-Session</constant> connection to query and locate resources on an advanced network
 913                 technology server (one using Windows NT4/200x or Samba). It also demonstrates that an authenticated
 914                 connection must be made before resources can be used.
 915                 </para>
 916
 917                 </sect3>
 918
 919         </sect2>
 920
 921         <sect2>
 922         <title>Conclusions to Exercises</title>
 923
 924         <para>
 925         In summary, the following points have been established in this chapter:
 926         </para>
 927
 928         <itemizedlist>
 929                 <listitem><para>
 930                 When NetBIOS over TCP/IP protocols are enabled, MS Windows networking employs broadcast-oriented messaging protocols to provide knowledge of network services.
 931                 </para></listitem>
 932
 933                 <listitem><para>
 934                 Network browsing protocols query information stored on browse masters that manage
 935                 information provided by NetBIOS Name Registrations and by way of ongoing host
 936                 announcements and workgroup announcements.
 937                 </para></listitem>
 938
 939                 <listitem><para>
 940                 All Samba servers must be configured with a mechanism for mapping the <constant>NULL-Session</constant>
 941                 to a valid but nonprivileged UNIX system account.
 942                 </para></listitem>
 943
 944                 <listitem><para>
 945                 The use of Microsoft encrypted passwords is built right into the fabric of Windows
 946                 networking operations. Such passwords cannot be provided from the UNIX <filename>/etc/passwd</filename>
 947                 database and thus must be stored elsewhere on the UNIX system in a manner that Samba can
 948                 use. Samba-2.x permitted such encrypted passwords to be stored in the <constant>smbpasswd</constant>
 949                 file or in an LDAP database. Samba-3 permits use of multiple <parameter>passdb backend</parameter>
 950                 databases in concurrent deployment. Refer to <emphasis>TOSHARG2</emphasis>, Chapter 10, <quote>Account Information Databases.</quote>
 951                 </para></listitem>
 952         </itemizedlist>
 953
 954         </sect2>
 955
 956 </sect1>
 957
 958 <sect1 id="chap01conc">
 959         <title>Dissection and Discussion</title>
 960
 961         <para>
 962         <indexterm><primary>guest account</primary></indexterm>
 963         The exercises demonstrate the use of the <constant>guest</constant> account, the way that
 964         MS Windows clients and servers resolve computer names to a TCP/IP address, and how connections
 965         between a client and a server are established.
 966         </para>
 967
 968         <para>
 969         Those wishing background information regarding NetBIOS name types should refer to
 970         the Microsoft knowledgebase article
 971         <ulink url="http://support.microsoft.com/support/kb/articles/Q102/78/8.asp">Q102878.</ulink>
 972         </para>
 973
 974         <sect2>
 975                 <title>Technical Issues</title>
 976
 977                 <para>
 978                 <indexterm><primary>guest account</primary></indexterm>
 979                 Network browsing involves SMB broadcast announcements, SMB enumeration requests,
 980                 connections to the <constant>IPC$</constant> share, share enumerations, and SMB connection
 981                 setup processes. The use of anonymous connections to a Samba server involve the use of
 982                 the <parameter>guest account</parameter> that must map to a valid UNIX UID.
 983                 </para>
 984
 985         </sect2>
 986
 987 </sect1>
 988
 989 <sect1 id="chap01qa">
 990         <title>Questions and Answers</title>
 991
 992         <para>
 993         The questions and answers given in this section are designed to highlight important aspects of Microsoft
 994         Windows networking.
 995         </para>
 996
 997         <qandaset defaultlabel="chap01qa" type="number">
 998         <qandaentry>
 999         <question>
1000
1001                 <para>
1002                 What is the significance of the MIDEARTH&lt;1b&gt; type query?
1003                 </para>
1004
1005         </question>
1006         <answer>
1007
1008                 <para>
1009                 <indexterm><primary>Domain Master Browser</primary><see>DMB</see></indexterm>
1010                 <indexterm><primary>DMB</primary></indexterm>
1011                 This is a broadcast announcement by which the Windows machine is attempting to
1012                 locate a Domain Master Browser (DMB) in the event that it might exist on the network.
1013                 Refer to <emphasis>TOSHARG2,</emphasis> Chapter 9, Section 9.7, <quote>Technical Overview of Browsing,</quote>
1014                 for details regarding the function of the DMB and its role in network browsing.
1015                 </para>
1016
1017         </answer>
1018         </qandaentry>
1019
1020         <qandaentry>
1021         <question>
1022
1023                 <para>
1024                 What is the significance of the MIDEARTH&lt;1d&gt; type name registration?
1025                 </para>
1026
1027         </question>
1028         <answer>
1029
1030                 <para>
1031                 <indexterm><primary>Local Master Browser</primary><see>LMB</see></indexterm>
1032                 <indexterm><primary>LMB</primary></indexterm>
1033                 This name registration records the machine IP addresses of the LMBs.
1034                 Network clients can query this name type to obtain a list of browser servers from the
1035                 master browser.
1036                 </para>
1037
1038                 <para>
1039                 The LMB is responsible for monitoring all host announcements on the local network and for
1040                 collating the information contained within them. Using this information, it can provide answers to other Windows
1041                 network clients that request information such as:
1042                 </para>
1043
1044                 <itemizedlist>
1045                         <listitem><para>
1046                         The list of machines known to the LMB (i.e., the browse list)
1047                         </para></listitem>
1048
1049                         <listitem><para>
1050                         The IP addresses of all domain controllers known for the domain
1051                         </para></listitem>
1052
1053                         <listitem><para>
1054                         The IP addresses of LMBs
1055                         </para></listitem>
1056
1057                         <listitem><para>
1058                         The IP address of the DMB (if one exists)
1059                         </para></listitem>
1060
1061                         <listitem><para>
1062                         The IP address of the LMB on the local segment
1063                         </para></listitem>
1064                 </itemizedlist>
1065
1066         </answer>
1067         </qandaentry>
1068
1069         <qandaentry>
1070         <question>
1071
1072                 <para>
1073                 What is the role and significance of the &lt;01&gt;&lt;02&gt;__MSBROWSE__&lt;02&gt;&lt;01&gt;
1074                 name registration?
1075                 </para>
1076
1077         </question>
1078         <answer>
1079
1080                 <para>
1081                 <indexterm><primary>Browse Master</primary></indexterm>
1082                 This name is registered by the browse master to broadcast and receive domain announcements.
1083                 Its scope is limited to the local network segment, or subnet. By querying this name type,
1084                 master browsers on networks that have multiple domains can find the names of master browsers
1085                 for each domain.
1086                 </para>
1087
1088         </answer>
1089         </qandaentry>
1090
1091         <qandaentry>
1092         <question>
1093
1094                 <para>
1095                 What is the significance of the MIDEARTH&lt;1e&gt; type name registration?
1096                 </para>
1097
1098         </question>
1099         <answer>
1100
1101                 <para>
1102                 <indexterm><primary>Browser Election Service</primary></indexterm>
1103                 This name is registered by all browse masters in a domain or workgroup. The registration
1104                 name type is known as the Browser Election Service. Master browsers register themselves
1105                 with this name type so that DMBs can locate them to perform cross-subnet
1106                 browse list updates. This name type is also used to initiate elections for Master Browsers.
1107                 </para>
1108
1109         </answer>
1110         </qandaentry>
1111
1112         <qandaentry>
1113         <question>
1114
1115                 <para>
1116                 <indexterm><primary>guest account</primary></indexterm>
1117                 What is the significance of the <parameter>guest account</parameter> in smb.conf?
1118                 </para>
1119
1120         </question>
1121         <answer>
1122
1123                 <para>
1124                 This parameter specifies the default UNIX account to which MS Windows networking
1125                 NULL session connections are mapped. The default name for the UNIX account used for
1126                 this mapping is called <constant>nobody</constant>. If the UNIX/Linux system that
1127                 is hosting Samba does not have a <constant>nobody</constant> account and an alternate
1128                 mapping has not been specified, network browsing will not work at all.
1129                 </para>
1130
1131                 <para>
1132                 It should be noted that the <parameter>guest account</parameter> is essential to
1133                 Samba operation. Either the operating system must have an account called <constant>nobody</constant>
1134                 or there must be an entry in the &smb.conf; file with a valid UNIX account, such as
1135                 <smbconfoption name="guest account">ftp</smbconfoption>.
1136                 </para>
1137
1138         </answer>
1139         </qandaentry>
1140
1141         <qandaentry>
1142         <question>
1143
1144                 <para>
1145                 Is it possible to reduce network broadcast activity with Samba-3?
1146                 </para>
1147
1148         </question>
1149         <answer>
1150
1151                 <para>
1152                 <indexterm><primary>WINS</primary></indexterm>
1153                 <indexterm><primary>NetBIOS</primary></indexterm>
1154                 Yes, there are two ways to do this. The first involves use of WINS (See <emphasis>TOSHARG2</emphasis>, Chapter 9,
1155                 Section 9.5, <quote>WINS &smbmdash; The Windows Inter-networking Name Server</quote>); the
1156                 alternate method involves disabling the use of NetBIOS over TCP/IP. This second method requires
1157                 a correctly configured DNS server (see <emphasis>TOSHARG2</emphasis>, Chapter 9, Section 9.3, <quote>Discussion</quote>).
1158                 </para>
1159
1160                 <para>
1161                 <indexterm><primary>broadcast</primary></indexterm>
1162                 <indexterm><primary>NetBIOS</primary><secondary>Node Type</secondary></indexterm>
1163                 <indexterm><primary>Hybrid</primary></indexterm>
1164                 The use of WINS reduces network broadcast traffic. The reduction is greatest when all network
1165                 clients are configured to operate in <parameter>Hybrid Mode</parameter>. This can be effected through
1166                 use of DHCP to set the NetBIOS node type to type 8 for all network clients. Additionally, it is
1167                 beneficial to configure Samba to use <smbconfoption name="name resolve order">wins host cast</smbconfoption>.
1168                 </para>
1169
1170                 <note><para>
1171                 Use of SMB without NetBIOS is possible only on Windows 200x/XP Professional clients and servers, as
1172                 well as with Samba-3.
1173                 </para></note>
1174
1175         </answer>
1176         </qandaentry>
1177
1178         <qandaentry>
1179         <question>
1180
1181                 <para>
1182                 Can I just use plain-text passwords with Samba?
1183                 </para>
1184
1185         </question>
1186         <answer>
1187
1188                 <para>
1189                 Yes, you can configure Samba to use plain-text passwords, though this does create a few problems.
1190                 </para>
1191
1192                 <para>
1193                 First, the use of <filename>/etc/passwd</filename>-based plain-text passwords requires that registry
1194                 modifications be made on all MS Windows client machines to enable plain-text passwords support. This
1195                 significantly diminishes the security of MS Windows client operation. Many network administrators
1196                 are bitterly opposed to doing this.
1197                 </para>
1198
1199                 <para>
1200                 Second, Microsoft has not maintained plain-text password support since the default setting was made
1201                 disabling this. When network connections are dropped by the client, it is not possible to re-establish
1202                 the connection automatically. Users need to log off and then log on again. Plain-text password support
1203                 may interfere with recent enhancements that are part of the Microsoft move toward a more secure computing
1204                 environment.
1205                 </para>
1206
1207                 <para>
1208                 Samba-3 supports Microsoft encrypted passwords. Be advised not to reintroduce plain-text password handling.
1209                 Just create user accounts by running <command>smbpasswd -a 'username'</command>
1210                 </para>
1211
1212                 <para>
1213                 It is not possible to add a user to the <parameter>passdb backend</parameter> database unless there is
1214                 a UNIX system account for that user. On systems that run <command>winbindd</command> to access the Samba
1215                 PDC/BDC to provide Windows user and group accounts, the <parameter>idmap uid, idmap gid</parameter> ranges
1216                 set in the &smb.conf; file provide the local UID/GIDs needed for local identity management purposes.
1217                 </para>
1218
1219         </answer>
1220         </qandaentry>
1221
1222         <qandaentry>
1223         <question>
1224
1225                 <para>
1226                 What parameter in the &smb.conf; file is used to enable the use of encrypted passwords?
1227                 </para>
1228
1229         </question>
1230         <answer>
1231
1232                 <para>
1233                 The parameter in the &smb.conf; file that controls this behavior is known as <parameter>encrypt
1234                 passwords</parameter>. The default setting for this in Samba-3 is <constant>Yes (Enabled)</constant>.
1235                 </para>
1236
1237         </answer>
1238         </qandaentry>
1239
1240         <qandaentry>
1241         <question>
1242
1243                 <para>
1244                 Is it necessary to specify <smbconfoption name="encrypt passwords">Yes</smbconfoption>
1245                 when Samba-3 is configured as a domain member?
1246                 </para>
1247
1248         </question>
1249         <answer>
1250
1251                 <para>
1252                 No. This is the default behavior.
1253                 </para>
1254
1255         </answer>
1256         </qandaentry>
1257
1258         <qandaentry>
1259         <question>
1260
1261                 <para>
1262                 Is it necessary to specify a <parameter>guest account</parameter> when Samba-3 is configured
1263                 as a domain member server?
1264                 </para>
1265
1266         </question>
1267         <answer>
1268
1269                 <para>
1270                 Yes. This is a local function on the server. The default setting is to use the UNIX account
1271                 <constant>nobody</constant>. If this account does not exist on the UNIX server, then it is
1272                 necessary to provide a <smbconfoption name="guest account">an_account</smbconfoption>,
1273                 where <constant>an_account</constant> is a valid local UNIX user account.
1274                 </para>
1275
1276         </answer>
1277         </qandaentry>
1278         </qandaset>
1279
1280 </sect1>
1281
1282 </chapter>
1283