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6
7<h1 class="head0">Chapter 7. Name Resolution and Browsing</h1>
8
9
10
11
12<p><a name="INDEX-1"/><em class="firstterm">Name
13resolution</em> is critical to Samba's
14operation because names are used to find the servers that share files
15or printers. <em class="firstterm">Browsing</em> takes the task of
16finding servers to a new level of sophistication by allowing a user
17to delve down into a hierarchy of networks, domains, hosts, and
18services offered by each server.</p>
19
20<p>While name resolution and
21<a name="INDEX-2"/>browsing are not
22difficult to configure, some complexity is introduced by the variety
23of available name-resolution systems. Historically, Unix and other
24TCP/IP users have moved from a flat hosts file to the Domain Name
25System, with the Network Information System being another popular
26choice. Meanwhile, Microsoft has moved from a broadcasting system to
27a simple, LAN-only name server called WINS and ultimately to DNS.</p>
28
29<p>The reason for going over that history is that all previous systems
30of name resolution are still in use today! Finding a host is so
31crucial to networking that sites want robust (if limited)
32name-resolution systems to fall back on in case the main system
33fails. Browsing is also complicated by the frequent need to show
34hosts in other subnets. This chapter shows you how to configure your
35network to handle name resolution and browsing any way you want.</p>
36
37<p>Some of the differences between Unix and Microsoft networking
38implementations are the result of fundamental design goals. Unix
39networking was originally designed largely to implement a relatively
40formal group of systems that were assumed to be small in number,
41well-maintained, and highly available, that have static IP addresses,
42and that wouldn't physically move around from place
43to place. Bringing a new server online was a labor-intensive task,
44but it did not have to be performed frequently. In contrast, Windows
45networking was originally developed as a peer-to-peer collection of
46small personal computers on a single subnet, having no centrally or
47hierarchically organized structure.</p>
48
49<p>SMB networking is dynamic. Computers are allowed to leave the network
50at any time, sometimes without warning, and also to join or rejoin
51the network at any time. Furthermore, any user in a Windows network
52can add a new shared resource to the network or remove a resource
53that he had previously added. The change in the
54network's configuration is handled automatically by
55the rest of the network without requiring a system administrator to
56take any action.</p>
57
58
59
60<div class="sect1"><a name="samba2-CHP-7-SECT-1"/>
61
62<h2 class="head1">Name Resolution</h2>
63
64<p>TCP/IP networks identify systems by IP addresses and always associate
65these addresses with more human-readable text names. In
66Microsoft's earliest networking implementations (for
67MS-DOS and Windows for Workgroups), the translation of names to
68network addresses was carried out in a manner that was very simple,
69yet very inefficient. When a system on the network needed an IP
70address corresponding to a name, it broadcasted the name to every
71other system on the network and waited for the system that owned the
72name to respond with its IP address.</p>
73
74<p>The main problem with performing <a name="INDEX-3"/>name resolution using broadcast
75packets is poor performance of the network as a whole, including CPU
76time consumed by each host on the network, which has to accept every
77broadcast packet and decide whether to respond to it. Also, broadcast
78packets usually aren't forwarded by routers,
79limiting name resolution to the local subnet.
80Microsoft's solution was to add WINS (Windows
81Internet Name Service) support to Windows NT so that the computers on
82the network can perform a direct query of the WINS server instead of
83using broadcast packets.</p>
84
85<p>Modern Windows clients use a variety of methods for translating
86hostnames into IP addresses. The exact method varies depending on the
87version of Windows the client is running, how the client is
88configured (i.e., whether DNS server and/or WINS server IP addresses
89are provided), and whether the application software is accessing the
90network through Microsoft's Winsock or TCP/IP API.
91In general, Windows uses some combination of the following
92methods:<a name="INDEX-4"/></p>
93
94<ul><li>
95<p>Looking up the name in its cache of recently resolved names</p>
96</li><li>
97<p>Querying DNS servers</p>
98</li><li>
99<p>Using the DNS <em class="filename">Hosts</em> file</p>
100</li><li>
101<p>Querying WINS servers</p>
102</li><li>
103<p>Using the WINS <em class="filename">LMHOSTS</em> file</p>
104</li><li>
105<p>Performing broadcast name resolution</p>
106</li></ul>
107<p>The first method is pretty much self-explanatory. A hostname is
108checked against a cache of hostnames that have been recently resolved
109to IP addresses. This helps to save time and network bandwidth for
110resolving names that are used frequently.</p>
111
112<p>When a Windows system is configured with the IP address of at least
113one <a name="INDEX-5"/>DNS server, it can use DNS to
114resolve fully qualified domain names, such as those for sites on the
115Internet. The DNS servers can be either Windows NT/2000 or Unix
116systems. You can learn more about DNS and DNS server configuration in
117the O'Reilly book <em class="citetitle">DNS and
118BIND</em>.</p>
119
120<p>In this chapter, we focus mainly on name resolution using WINS, which
121is supported by Samba with the <em class="emphasis">nmbd</em> daemon.</p>
122
123
124<div class="sect2"><a name="samba2-CHP-7-SECT-1.1"/>
125
126<h3 class="head2">WINS Clients and Server Interaction</h3>
127
128<p>There are two types of interaction between a
129<a name="INDEX-6"/>WINS client and a server: the
130client keeps its own NetBIOS name<a name="FNPTR-1"/><a href="#FOOTNOTE-1">[1]</a> registered with the server and
131queries the server to get the IP address corresponding to the NetBIOS
132name of another system.</p>
133
134<p>When a WINS client joins the network, it registers its NetBIOS name
135with the WINS server, which stores it along with the
136client's IP address in the WINS database. This entry
137is marked <em class="firstterm">active</em>. The client is then expected
138to renew the registration of its name periodically (typically, every
139four days) to inform the server that it is still using the name. This
140period is called the <em class="firstterm">time to live</em>, or TTL.
141When the client leaves the network by being shut down gracefully, it
142informs the server, and the server marks the
143client's entry in its database as
144<em class="firstterm">released</em>.</p>
145
146<p>When a client leaves the network without telling the WINS server to
147release its name, the server waits until after it fails to receive
148the expected registration renewal from the client and then marks the
149entry as released.</p>
150
151<p>In either case, the released name is available for use by other
152clients joining the network. It might persist in the released state
153in the WINS database, and if it is not reregistered, the entry will
154eventually be deleted.</p>
155
156<p>More information on WINS can be found in the Microsoft white paper
157<em class="citetitle">Windows Internet Naming Service (WINS) Architecture and
158Capacity Planning</em><a name="INDEX-7"/>. It can be downloaded from the
159Microsoft web site at <a href="http://www.microsoft.com">http://www.microsoft.com</a>.</p>
160
161
162</div>
163
164
165<div class="sect2"><a name="samba2-CHP-7-SECT-1.2"/>
166
167<h3 class="head2">The lmhosts File</h3>
168
169<p>In <a href="ch03.html">Chapter 3</a> we showed you how to configure
170Windows systems to use the
171<em class="filename">LMHOSTS</em><a name="INDEX-8"/>
172file as an alternative to the WINS server for name resolution. Samba
173also can use an <em class="filename">LMHOSTS</em> file, which by default
174is <em class="filename">/usr/local/samba/lib/lmhosts</em>.
175Samba's <em class="filename">lmhosts</em> is the same
176format as the Windows version. A simple <em class="filename">lmhosts</em>
177file might look like this:</p>
178
179<blockquote><pre class="code">172.16.1.1 toltec
180172.16.1.6 maya</pre></blockquote>
181
182<p>The names on the right side of the entries are NetBIOS names, so you
183can assign resource types to them and add additional entries for
184computers:</p>
185
186<blockquote><pre class="code">172.16.1.1 toltec#20
187172.16.1.1 metran#1b
188172.16.1.6 maya#20</pre></blockquote>
189
190<p>Here, we've made <tt class="literal">toltec</tt> the
191primary domain controller of the <tt class="literal">METRAN</tt> domain on
192the second line. This line starts with
193<tt class="literal">toltec</tt>'s IP address, followed by
194the name metran and the resource type &lt;1B&gt;. The other lines are
195entries for <tt class="literal">toltec</tt> and <tt class="literal">maya</tt> as
196standard workstations.</p>
197
198<p>If you wish to place an <em class="emphasis">lmhosts</em> file somewhere
199other than the default location, you will need to notify the
200<em class="emphasis">nmbd</em> process upon startup using the
201<em class="emphasis">-H</em> option, followed by the name of your
202<em class="filename">lmhosts</em> file, as follows:</p>
203
204<blockquote><pre class="code"># <tt class="userinput"><b>nmbd -H /etc/samba/lmhosts -D</b></tt></pre></blockquote>
205
206
207</div>
208
209
210<div class="sect2"><a name="samba2-CHP-7-SECT-1.3"/>
211
212<h3 class="head2">Configuring Name Resolution for the Samba Suite</h3>
213
214<p>Various daemons and tools in the Samba suite need to perform
215<a name="INDEX-9"/>name resolution. You can define the
216order in which the programs try each name-resolution method through
217the <tt class="literal">name</tt><a name="INDEX-10"/><a name="INDEX-11"/>
218<tt class="literal">resolve</tt> <tt class="literal">order</tt> parameter, like
219this:</p>
220
221<blockquote><pre class="code">[global]
222 name resolve order = wins lmhosts hosts bcast</pre></blockquote>
223
224<p>The string used to define the parameter can take up to four values:</p>
225
226<dl>
227<dt><b>lmhosts</b></dt>
228<dd>
229<p>Uses the Samba server's local
230<em class="filename">lmhosts</em> file</p>
231</dd>
232
233
234
235<dt><b>hosts</b></dt>
236<dd>
237<p>Uses the standard Unix name-resolution methods, which can be
238<em class="emphasis">/etc/hosts</em>, DNS, NIS, or a combination,
239depending on how the local system is configured</p>
240</dd>
241
242
243
244<dt><b>wins</b></dt>
245<dd>
246<p>Uses the WINS server</p>
247</dd>
248
249
250
251<dt><b>bcast</b></dt>
252<dd>
253<p>Uses the broadcast method</p>
254</dd>
255
256</dl>
257
258<p>The order in which they are specified is the order in which name
259resolution will be attempted. In our example, Samba will attempt to
260use its WINS server first for name resolution, followed by the
261<em class="emphasis">lmhosts</em> file on the local system. Next, the
262<tt class="literal">hosts</tt> value tells it to use Unix name-resolution
263methods. The word <tt class="literal">hosts</tt> can be misleading; it
264covers not only the <em class="filename">/etc/hosts</em> file, but also
265the use of DNS or NIS (as configured on the Unix host). Finally, if
266those three do not work, it will perform a broadcast name resolution.</p>
267
268
269</div>
270
271
272<div class="sect2"><a name="samba2-CHP-7-SECT-1.4"/>
273
274<h3 class="head2">Setting Up Samba as a WINS Server</h3>
275
276<p>You can set up Samba as a <a name="INDEX-12"/>WINS server by setting the
277<tt class="literal">wins</tt><a name="INDEX-13"/> <tt class="literal">support</tt>
278parameter in the configuration file, like this:</p>
279
280<blockquote><pre class="code">[global]
281 wins support = yes</pre></blockquote>
282
283<p>Believe it or not, that's all you need to do! The
284<tt class="literal">wins</tt> <tt class="literal">support</tt> option turns Samba
285into a WINS server. For most installations, Samba's
286default configuration is sufficient.</p>
287<a name="samba2-CHP-7-NOTE-137"/><blockquote class="note"><h4 class="objtitle">WARNING</h4>
288<p>Remember, Samba cannot communicate with Windows WINS servers. If you
289are using Samba as your WINS server, you must make sure not to allow
290any Windows systems or other Samba servers on your network to be
291configured as WINS servers. If you do, their WINS databases will not
292synchronize, resulting in inconsistent name resolution.</p>
293</blockquote>
294
295
296<div class="sect3"><a name="samba2-CHP-7-SECT-1.4.1"/>
297
298<h3 class="head3">Configuring a DNS proxy</h3>
299
300<p>A Samba <a name="INDEX-14"/><a name="INDEX-15"/>WINS server can check with the
301system's DNS server if a requested host cannot be
302found in its WINS database. With a typical Linux system, for example,
303you can find the IP address of the DNS server by searching the
304<em class="filename">/etc/resolv.conf</em><a name="INDEX-16"/><a name="INDEX-17"/> file. In it, you might see an entry such
305as the following:</p>
306
307<blockquote><pre class="code">nameserver 127.0.0.1
308nameserver 172.16.1.192</pre></blockquote>
309
310<p>This tells us that the Linux system is configured to use a DNS server
311located at 172.16.1.192. (The 127.0.0.1 is the
312<tt class="literal">localhost</tt> address and is never a valid DNS server
313address.)</p>
314
315<p>Now it is a simple matter of using the
316<tt class="literal">dns</tt><a name="INDEX-18"/> <tt class="literal">proxy</tt> option to tell
317Samba to use the DNS server:</p>
318
319<blockquote><pre class="code">[global]
320 dns proxy = yes</pre></blockquote>
321
322<a name="samba2-CHP-7-NOTE-138"/><blockquote class="note"><h4 class="objtitle">TIP</h4>
323<p>Although this allows Windows clients to resolve fully qualified
324Internet domain names through the Samba WINS server, it will work
325only for domain names that fit within the 15-character limitation of
326NetBIOS names. For this reason, we recommend you use <tt class="literal">dns
327proxy</tt> only to act as a supplement to your WINS server,
328rather than as a replacement for a DNS server.</p>
329</blockquote>
330
331
332</div>
333
334
335</div>
336
337
338<div class="sect2"><a name="samba2-CHP-7-SECT-1.5"/>
339
340<h3 class="head2">Setting Up Samba to Use Another WINS Server</h3>
341
342<p>You can configure Samba to use a <a name="INDEX-19"/>WINS server somewhere else on the
343network by simply providing it with the IP address of the WINS
344server. This is done with the global
345<tt class="literal">wins</tt><a name="INDEX-20"/> <tt class="literal">server</tt>
346configuration option, as shown here:</p>
347
348<blockquote><pre class="code">[global]
349 wins server = 172.16.1.1</pre></blockquote>
350
351<p>With this option enabled, Samba will direct all WINS requests to the
352server located at 172.16.1.1. Note that because the request is
353directed at a single machine, we don't have to worry
354about any of the problems inherent in broadcasting. However, Samba
355will not necessarily use the WINS server before other forms of name
356resolution. The order in which Samba attempts various name-resolution
357techniques is given with the <tt class="literal">name</tt>
358<tt class="literal">resolve</tt> <tt class="literal">order</tt> configuration
359option, which we discussed earlier.</p>
360
361<p>The <tt class="literal">wins</tt> <tt class="literal">support</tt> and the
362<tt class="literal">wins</tt> <tt class="literal">server</tt> parameters are
363mutually exclusive; you cannot simultaneously offer Samba as the WINS
364server and use another system as the server! Typically, one Samba
365server is set up as the WINS server using <tt class="literal">wins</tt>
366<tt class="literal">support</tt>, and all other Samba servers are
367configured with the <tt class="literal">wins</tt> <tt class="literal">server</tt>
368parameter pointing to the Samba WINS server.</p>
369
370
371<div class="sect3"><a name="samba2-CHP-7-SECT-1.5.1"/>
372
373<h3 class="head3">Configuring a WINS proxy</h3>
374
375<p><a name="INDEX-21"/>If you have a Samba server on a
376subnet that doesn't have a WINS server, and the
377Samba server has been configured with a WINS server on another
378subnet, you can tell the Samba server to forward any name-resolution
379requests with the <tt class="literal">wins</tt><a name="INDEX-22"/>
380<tt class="literal">proxy</tt> option:</p>
381
382<blockquote><pre class="code">[global]
383 wins server = 172.16.200.12
384 wins proxy = yes</pre></blockquote>
385
386<p>Use this only in situations where the WINS server resides on another
387subnet. Otherwise, the broadcast will reach the WINS server
388regardless of any proxying.</p>
389
390
391</div>
392
393
394</div>
395
396
397<div class="sect2"><a name="samba2-CHP-7-SECT-1.6"/>
398
399<h3 class="head2">Name-Resolution Configuration Options</h3>
400
401<p><a name="INDEX-23"/>Samba's <a name="INDEX-24"/>name-resolution options
402are shown in <a href="ch07.html#samba2-CHP-7-TABLE-1">Table 7-1</a>.</p>
403
404<a name="samba2-CHP-7-TABLE-1"/><h4 class="head4">Table 7-1. Name-resolution options</h4><table border="1">
405
406
407
408
409
410
411<tr>
412<th>
413<p>Option</p>
414</th>
415<th>
416<p>Parameters</p>
417</th>
418<th>
419<p>Function</p>
420</th>
421<th>
422<p>Default</p>
423</th>
424<th>
425<p>Scope</p>
426</th>
427</tr>
428
429
430<tr>
431<td>
432<p><tt class="literal">wins support</tt></p>
433</td>
434<td>
435<p>boolean</p>
436</td>
437<td>
438<p>If set to <tt class="literal">yes</tt>, allows Samba to act as a WINS server</p>
439</td>
440<td>
441<p><tt class="literal">no</tt></p>
442</td>
443<td>
444<p>Global</p>
445</td>
446</tr>
447<tr>
448<td>
449<p><tt class="literal">wins server</tt></p>
450</td>
451<td>
452<p>string (IP address or DNS name)</p>
453</td>
454<td>
455<p>Identifies a WINS server for Samba to use for name registration and
456resolution</p>
457</td>
458<td>
459<p>None</p>
460</td>
461<td>
462<p>Global</p>
463</td>
464</tr>
465<tr>
466<td>
467<p><tt class="literal">wins proxy</tt></p>
468</td>
469<td>
470<p>boolean</p>
471</td>
472<td>
473<p>Allows Samba to act as a proxy to a WINS server on another subnet</p>
474</td>
475<td>
476<p><tt class="literal">no</tt></p>
477</td>
478<td>
479<p>Global</p>
480</td>
481</tr>
482<tr>
483<td>
484<p><tt class="literal">wins hook</tt></p>
485</td>
486<td>
487<p>string</p>
488</td>
489<td>
490<p>Command to run when the WINS database changes</p>
491</td>
492<td>
493<p>None</p>
494</td>
495<td>
496<p>Global</p>
497</td>
498</tr>
499<tr>
500<td>
501<p><tt class="literal">dns proxy</tt></p>
502</td>
503<td>
504<p>boolean</p>
505</td>
506<td>
507<p>If set to <tt class="literal">yes</tt>, allows a Samba WINS server to
508search DNS if it cannot find a name in WINS</p>
509</td>
510<td>
511<p><tt class="literal">no</tt></p>
512</td>
513<td>
514<p>Global</p>
515</td>
516</tr>
517<tr>
518<td>
519<p><tt class="literal">name resolve</tt> <tt class="literal">order</tt></p>
520</td>
521<td>
522<p>string</p>
523</td>
524<td>
525<p>The order of methods used to resolve NetBIOS names</p>
526</td>
527<td>
528<p><tt class="literal">lmhosts</tt> <tt class="literal">hosts wins bcast</tt></p>
529</td>
530<td>
531<p>Global</p>
532</td>
533</tr>
534<tr>
535<td>
536<p><tt class="literal">max ttl</tt></p>
537</td>
538<td>
539<p>numeric</p>
540</td>
541<td>
542<p>Maximum TTL in seconds for a requested NetBIOS name</p>
543</td>
544<td>
545<p><tt class="literal">259200</tt> ( 3 days)</p>
546</td>
547<td>
548<p>Global</p>
549</td>
550</tr>
551<tr>
552<td>
553<p><tt class="literal">max wins ttl</tt></p>
554</td>
555<td>
556<p>numeric</p>
557</td>
558<td>
559<p>Maximum TTL in seconds for NetBIOS names given out by Samba as a WINS
560server</p>
561</td>
562<td>
563<p><tt class="literal">518400</tt> (6 days)</p>
564</td>
565<td>
566<p>Global</p>
567</td>
568</tr>
569<tr>
570<td>
571<p><tt class="literal">min wins ttl</tt></p>
572</td>
573<td>
574<p>numeric</p>
575</td>
576<td>
577<p>Minimum TTL in seconds for NetBIOS names given out by Samba as a WINS
578server</p>
579</td>
580<td>
581<p><tt class="literal">21600</tt> (6 hours)</p>
582</td>
583<td>
584<p>Global</p>
585</td>
586</tr>
587
588</table>
589
590
591<div class="sect3"><a name="samba2-CHP-7-SECT-1.6.1"/>
592
593<a name="INDEX-25"/><h3 class="head3">wins support</h3>
594
595<p>Samba will provide WINS name service to all machines in the network
596if you set the following in the <tt class="literal">[global]</tt> section
597of the <em class="filename">smb.conf</em> file:</p>
598
599<blockquote><pre class="code">[global]
600 wins support = yes</pre></blockquote>
601
602<p>The default value is <tt class="literal">no</tt>, which is typically used
603to allow a Windows NT/2000 server or another Samba server to be the
604WINS server. If you enable this option, remember that a Samba WINS
605server currently cannot exchange data with other WINS servers, so do
606not allow any other WINS servers on the network. When set to
607<tt class="literal">yes</tt>, this option is mutually exclusive with the
608<tt class="literal">wins</tt> <tt class="literal">server</tt> parameter.</p>
609
610
611</div>
612
613
614
615<div class="sect3"><a name="samba2-CHP-7-SECT-1.6.2"/>
616
617<a name="INDEX-26"/><h3 class="head3">wins server</h3>
618
619<p>Samba will use an existing WINS server on the network if you specify
620the <tt class="literal">wins</tt> <tt class="literal">server</tt> global option
621in your configuration file. The value of this option is either the IP
622address or DNS name (not NetBIOS name) of the WINS server. For
623example:</p>
624
625<blockquote><pre class="code">[global]
626 wins server = 172.16.220.110</pre></blockquote>
627
628<p>or:</p>
629
630<blockquote><pre class="code">[global]
631 wins server = wins.metran.cx</pre></blockquote>
632
633<p>For this option to work, the <tt class="literal">wins</tt>
634<tt class="literal">support</tt> option must be set to
635<tt class="literal">no</tt> (the default). Otherwise, Samba will report an
636error. You can specify only one WINS server using this option.</p>
637
638
639</div>
640
641
642
643<div class="sect3"><a name="samba2-CHP-7-SECT-1.6.3"/>
644
645<a name="INDEX-27"/><h3 class="head3">wins proxy</h3>
646
647<p>This option allows Samba to act as a proxy to another WINS server,
648and thus relay name registration and resolution requests from itself
649to the real WINS server, often outside the current subnet. The WINS
650server can be indicated through the <tt class="literal">wins</tt>
651<tt class="literal">server</tt> option. The proxy will then return the WINS
652response back to the client. You can enable this option by specifying
653the following in the <tt class="literal">[global]</tt> section:</p>
654
655<blockquote><pre class="code">[global]
656 wins proxy = yes</pre></blockquote>
657
658
659</div>
660
661
662
663<div class="sect3"><a name="samba2-CHP-7-SECT-1.6.4"/>
664
665<a name="INDEX-28"/><h3 class="head3">wins hook</h3>
666
667<p>This option allows you to run a script or other program whenever the
668WINS database is modified. One application might be to set up another
669Samba server to act as a backup for another Samba WINS server. This
670is done by having the <tt class="literal">wins</tt> <tt class="literal">hook</tt>
671script call <em class="emphasis">rsync</em> to synchronize the WINS
672databases (<em class="filename">/usr/local/samba/var/locks/wins.dat</em>)
673on the two systems whenever an entry is added or deleted. The script
674would be specified in the Samba configuration file like this:</p>
675
676<blockquote><pre class="code">[global]
677 wins hook = /usr/local/bin/sync_wins</pre></blockquote>
678
679
680</div>
681
682
683
684<div class="sect3"><a name="samba2-CHP-7-SECT-1.6.5"/>
685
686<a name="INDEX-29"/><h3 class="head3">dns proxy</h3>
687
688<p>If you want the DNS to be used if a NetBIOS name
689isn't found in WINS, you can set the following
690option:</p>
691
692<blockquote><pre class="code">[global]
693 dns proxy = yes</pre></blockquote>
694
695<p>This will permit <em class="filename">nmbd</em> to query the
696server's standard DNS. You might wish to deactivate
697this option if you do not have a permanent connection to your DNS
698server. This option should not be used in place of a DNS server on
699your network; it is intended for resolving NetBIOS names rather than
700fully qualified Internet domain names.</p>
701
702
703</div>
704
705
706
707<div class="sect3"><a name="samba2-CHP-7-SECT-1.6.6"/>
708
709<h3 class="head3">name resolve order</h3>
710
711<p>The global <tt class="literal">name</tt><a name="INDEX-30"/>
712<tt class="literal">resolve</tt> <tt class="literal">order</tt> option specifies
713the order of services that Samba will use in performing name
714resolution. The default order is to use the
715<em class="emphasis">lmhosts</em> file, followed by standard Unix
716name-resolution methods (some combination of
717<em class="filename">/etc/hosts</em>, DNS, and NIS), then to query a WINS
718server, and finally to use broadcasting to determine the address of a
719NetBIOS name. You can override this option by specifying something
720like the following:</p>
721
722<blockquote><pre class="code">[global]
723 name resolve order = lmhosts wins hosts bcast</pre></blockquote>
724
725<p>This causes resolution to use the <em class="emphasis">lmhosts</em> file
726first, followed by a query to a WINS server, the
727<em class="filename">/etc/hosts</em> file, and finally broadcasting. You
728need not use all four options. This option is covered in more detail
729in <a href="ch07.html#samba2-CHP-7-SECT-1.4">Section 7.1.4</a>,
730earlier in this chapter.</p>
731
732
733</div>
734
735
736
737<div class="sect3"><a name="samba2-CHP-7-SECT-1.6.7"/>
738
739<a name="INDEX-31"/><h3 class="head3">max ttl</h3>
740
741<p>This option is used when Samba is not acting as a WINS server but is
742using another system on the network for its WINS server. It sets the
743maximum T T L for NetBIOS names registered by the Samba server with
744the WINS server. You should never need to alter this value.</p>
745
746
747</div>
748
749
750
751<div class="sect3"><a name="samba2-CHP-7-SECT-1.6.8"/>
752
753<a name="INDEX-32"/><h3 class="head3">max wins ttl</h3>
754
755<p>This option is used when Samba is providing WINS name service, and it
756sets the maximum T T L for NetBIOS names registered with Samba. You
757should never need to change this value from its default.</p>
758
759
760</div>
761
762
763
764<div class="sect3"><a name="samba2-CHP-7-SECT-1.6.9"/>
765
766<a name="INDEX-33"/><h3 class="head3">min wins ttl</h3>
767
768<p>This option is used when Samba is providing WINS name service, and it
769sets the minimum T T L for NetBIOS names registered with Samba. You
770should never need to alter this value from its default. <a name="INDEX-34"/> <a name="INDEX-35"/> <a name="INDEX-36"/></p>
771
772
773</div>
774
775
776</div>
777
778
779</div>
780
781
782
783<div class="sect1"><a name="samba2-CHP-7-SECT-2"/>
784
785<h2 class="head1">Browsing</h2>
786
787<p><a name="INDEX-37"/>Browsing
788was developed by Microsoft to help users find shared resources on the
789network. In a networked computing environment where users can add or
790remove shares at any time, it is important to have some automatic
791means of keeping track of the shared resources and allowing users to
792&quot;browse&quot; through them to find the
793ones they wish to use.</p>
794
795<p>Before browsing was added to SMB networking, when anyone added a new
796share, the people with whom they wished to share the data or printer
797would have to be informed of the share's UNC, using
798some relatively low-tech method such as speaking to them in person or
799over the phone, or sending email. Already, this was very inconvenient
800in large organizations. To further complicate matters, the users
801working on client computers had to type in the
802share's UNC to connect to it. The only way to get
803around typing in the share's UNC every time it was
804used was to map a network drive to it, and with a large number of
805shares on the network, this could easily get out of hand.</p>
806
807
808<div class="sect2"><a name="samba2-CHP-7-SECT-2.1"/>
809
810<h3 class="head2">Browsing in a Windows Network</h3>
811
812<p><a name="INDEX-38"/>To keep things simple, we will
813first describe network browsing in a network that contains only
814Windows systems and then show you how to add a Samba server.</p>
815
816<p>The basic way browsing works is that one computer in the network
817takes on the role of the <em class="firstterm">master
818browser</em><a name="INDEX-39"/> (also
819called <em class="firstterm">local master
820browser</em><a name="INDEX-40"/>,<em class="firstterm"> browse
821master</em><a name="INDEX-41"/>, or
822<em class="firstterm">browse server</em><a name="INDEX-42"/>) and
823keeps a list of all the computers on the local subnet that are acting
824as SMB servers. The list of computers is called the <em class="firstterm">browse
825list</em><a name="INDEX-43"/> and includes all Samba servers, Windows
826NT/2000/XP systems, and any Windows 95/98/Me systems that have the
827&quot;File and printer sharing for Microsoft
828Networks&quot; networking component installed. The browse
829list also contains the names of all workgroups and domains. At this
830level, browsing is limited to the local subnet because the browsing
831protocol depends on broadcast packets, which are typically not
832forwarded to other subnets by routers.</p>
833
834<p>A user at any Windows system can view the browse list by opening up
835the Network Neighborhood (or My Network Places), as we showed you in
836<a href="ch01.html">Chapter 1</a>. Or, the <em class="emphasis">net
837view</em><a name="INDEX-44"/> command can be used from a Windows
838command prompt:</p>
839
840<blockquote><pre class="code">C:\&gt;<tt class="userinput"><b>net view</b></tt>
841Server Name Remark
842
843-------------------------------------------------------------------------------
844\\MAYA Windows 98
845\\MIXTEC Samba 2.2.5
846\\OLMEC Windows XP Pro on Pentium/ASUS
847\\TOLTEC Samba 2.2.5
848\\YAQUI Windows 95 on mixtec/VMware
849\\ZAPOTEC
850The command completed successfully.</pre></blockquote>
851
852<p>Then, <em class="emphasis">net view</em> can be used with a computer name
853as an argument to contact a server directly and list the resources it
854is sharing:</p>
855
856<blockquote><pre class="code">C:\&gt;<tt class="userinput"><b>net view \\maya</b></tt>
857Shared resources at \\maya
858
859Windows 98
860
861Share name Type Used as Comment
862
863-------------------------------------------------------------------------------
864D Disk
865E Disk
866HP Print
867The command completed successfully.</pre></blockquote>
868
869<p>The computers on the network involved in browsing are more than just
870the master browser and its clients. There are also backup browsers,
871which maintain copies of the browse list and respond to client
872requests for it. Backup browsers are therefore able to take over the
873role of master browser seamlessly in case it fails. The master
874browser usually doesn't serve the browse list
875directly to clients. Instead, its job is mainly to keep the master
876copy of the browse list up-to-date, and also periodically update the
877backup browsers. Clients are expected to get their copies of the
878browse list from backup browsers, selecting among them randomly to
879help to distribute the load on the backup browsers more evenly.
880Ideally, the interaction between any client and the master browser is
881limited to the client announcing when it joins or leaves the network
882(if it is a server) and requesting a list of backup browsers.</p>
883
884<p>There can be more than one <a name="INDEX-45"/>backup browser. A workgroup will have a
885backup browser if two or more computers are running Windows 95/98/Me
886or Windows NT Workstation (or another nonserver version of Windows
887NT/2000/XP) on the subnet. For every 32 additional computers, another
888backup browser is added.</p>
889
890<p>In a Windows NT domain, the <a name="INDEX-46"/>primary domain controller is
891always the local master browser, and if it fails, another Windows
892NT/2000 server (if one exists) will take over the role of local
893master browser. Other versions of Windows can function as backup
894browsers, but will never become a master browser if a Windows NT/2000
895server is available.</p>
896
897<p>In addition to acting as the local master browser, the primary domain
898controller also acts as the <em class="firstterm">domain master
899browser</em><a name="INDEX-47"/>, which ties subnets together and allows
900browse lists to be shared between master and backup browsers on
901separate subnets. This is how browsing is extended to function beyond
902the local subnet. Each subnet functions as a separate browsing
903entity, and the domain master browser synchronizes the master
904browsers of each subnet. In a Windows-only network, browsing cannot
905function across subnets unless a Windows NT/2000 PDC exists on the
906network. Samba can act as a domain master browser and can perform
907that task even in a workgroup network, which means that the Windows
908PDC is not required for this task. (It is also possible to use the
909<tt class="literal">remote</tt> <tt class="literal">browse</tt>
910<tt class="literal">sync</tt> parameter to configure a Samba server to
911synchronize its browse list with a Samba server on another subnet. In
912this case, each server must be acting as the local master browser of
913its subnet.)</p>
914
915<p>Unless it is configured never to act as a browser, each computer on
916the subnet is considered a <em class="firstterm">potential browser</em>
917and can be ordered by the browse master to become a backup browser,
918or it can identify itself as a backup browser and accept the role on
919its own.</p>
920
921
922</div>
923
924
925<div class="sect2"><a name="samba2-CHP-7-SECT-2.2"/>
926
927<h3 class="head2">Browser Elections</h3>
928
929<p><a name="INDEX-48"/>When no master browser is running on
930the subnet, potential browsers choose a new master browser among
931themselves in a process called an <em class="firstterm">election</em>. An
932election is started by a computer in the subnet when it discovers
933that no master browser is currently running. If a master browser is
934shut down gracefully, it will broadcast an election request datagram,
935initiating an election by the remaining computers. If the master
936browser fails, the election can be started by a client computer that
937requests a list of backup browsers from the master browser or by a
938backup browser that requests to have its browse list updated from the
939master browser. In each case, the system fails to receive a reply
940from the master browser and initiates the election.</p>
941
942<p>Browser elections are decided in multiple rounds of self-elimination.
943During each round, potential browsers broadcast election request
944datagrams containing their qualifications to notify other potential
945browsers that an election is happening and that if the recipient is
946more qualified, it should also broadcast a bid. When a potential
947browser receives an election request datagram from a more qualified
948opponent, it drops out, disqualifying itself from becoming the master
949browser. Otherwise, it responds with its own election request
950datagram. After a few rounds, only one potential browser is left in
951the election. After an additional four rounds of sending out an
952election request datagram and receiving no response, it becomes the
953master browser and sends a broadcast datagram announcing itself as
954the local master browser for the subnet. It then assigns runners-up
955in the election as backup browsers, as needed.</p>
956
957<p>A potential browser's qualifications include the
958following:</p>
959
960<ul><li>
961<p>Whether it has recently lost an election</p>
962</li><li>
963<p>The version of the election protocol it is running</p>
964</li><li>
965<p>Its election criteria</p>
966</li><li>
967<p>The amount of time the system has been up</p>
968</li><li>
969<p>The computer's NetBIOS name</p>
970</li></ul>
971<p>If the potential browser has lost an election recently, it
972immediately disqualifies itself. The version of the election protocol
973it is running is checked, but so far, all Windows systems (and Samba)
974use the same election protocol, so the check is not very meaningful.
975The election criteria are usually what determine which computer
976becomes the local master browser. There are two parts to the election
977criteria, shown in Tables <a href="ch07.html#samba2-CHP-7-TABLE-2">Table 7-2</a> and <a href="ch07.html#samba2-CHP-7-TABLE-3">Table 7-3</a>.</p>
978
979<a name="samba2-CHP-7-TABLE-2"/><h4 class="head4">Table 7-2. Operating-system values in an election</h4><table border="1">
980
981
982
983<tr>
984<th>
985<p>Operating system</p>
986</th>
987<th>
988<p>Value</p>
989</th>
990</tr>
991
992
993<tr>
994<td>
995<p>Windows NT/2000 Server, running as PDC</p>
996</td>
997<td>
998<p>32</p>
999</td>
1000</tr>
1001<tr>
1002<td>
1003<p>Windows NT/2000/XP, if not the PDC</p>
1004</td>
1005<td>
1006<p>16</p>
1007</td>
1008</tr>
1009<tr>
1010<td>
1011<p>Windows 95/98/Me</p>
1012</td>
1013<td>
1014<p>1</p>
1015</td>
1016</tr>
1017<tr>
1018<td>
1019<p>Windows for Workgroups</p>
1020</td>
1021<td>
1022<p>1</p>
1023</td>
1024</tr>
1025
1026</table>
1027
1028<a name="samba2-CHP-7-TABLE-3"/><h4 class="head4">Table 7-3. Computer-role settings in an election</h4><table border="1">
1029
1030
1031
1032<tr>
1033<th>
1034<p>Role</p>
1035</th>
1036<th>
1037<p>Value</p>
1038</th>
1039</tr>
1040
1041
1042<tr>
1043<td>
1044<p>Domain master browser</p>
1045</td>
1046<td>
1047<p>128</p>
1048</td>
1049</tr>
1050<tr>
1051<td>
1052<p>WINS client</p>
1053</td>
1054<td>
1055<p>32</p>
1056</td>
1057</tr>
1058<tr>
1059<td>
1060<p>Preferred master</p>
1061</td>
1062<td>
1063<p>8</p>
1064</td>
1065</tr>
1066<tr>
1067<td>
1068<p>Running master</p>
1069</td>
1070<td>
1071<p>4</p>
1072</td>
1073</tr>
1074<tr>
1075<td>
1076<p>Recent backup browser</p>
1077</td>
1078<td>
1079<p>2</p>
1080</td>
1081</tr>
1082<tr>
1083<td>
1084<p>Backup browser</p>
1085</td>
1086<td>
1087<p>1</p>
1088</td>
1089</tr>
1090
1091</table>
1092
1093<p>The operating-system type is compared first, and the system with the
1094highest value wins. The values have been chosen to cause the primary
1095domain controller, if there is one, to become the local master
1096browser. Otherwise, a Windows NT/2000/XP system will win over a
1097Windows for Workgroups or Windows 95/98/Me system.</p>
1098
1099<p>When an operating-system type comparison results in a tie, the role
1100of the computer is compared. A computer can have more than one of the
1101values in <a href="ch07.html#samba2-CHP-7-TABLE-3">Table 7-3</a>, in which case the values are
1102added.</p>
1103
1104<p>A domain master browser has a role value of 128 to weight the
1105election so heavily in its favor that it will also become the local
1106master browser on its own subnet. Although the primary domain
1107controller (which is always the domain master browser) will win the
1108election based solely on its operating system value, sometimes there
1109is no primary domain controller on the network, and the domain master
1110browser would not otherwise be distinguished from other potential
1111browsers.</p>
1112
1113<p>Systems that are using a WINS server for name resolution are weighted
1114heavily over ones that use broadcast name resolution with a role
1115value of 32.</p>
1116
1117<p>A <em class="firstterm">preferred master</em> is a computer that has been
1118selected and configured manually by a system administrator to be
1119favored as the choice master browser. When a preferred master starts
1120up, it forces a browser election, even if an existing master browser
1121is still active. A preferred master has a role value of 8, and the
1122existing master browser gets a value of 4.</p>
1123
1124<p>A backup browser that has recently been a master browser and still
1125has an up-to-date browse list is given a role value of 2, and a
1126potential browser that has been running as a backup browser gets a
1127value of 1.</p>
1128
1129<p>If comparing the operating-system type and role results in a tie, the
1130computer that has been running the longest wins. In the unlikely
1131event that the two have been up for the same amount of time, the
1132computer that wins is the one with the NetBIOS name that sorts first
1133alphabetically.</p>
1134
1135<p>You can tell if a machine is a local master browser by using the
1136Windows <em class="emphasis">nbtstat</em><a name="INDEX-49"/> command. Place the NetBIOS name of the
1137machine you wish to check after the <em class="emphasis">-a</em> option:</p>
1138
1139<blockquote><pre class="code">C:\&gt;<tt class="userinput"><b>nbtstat -a toltec</b></tt>
1140
1141Local Area Connection:
1142Node IpAddress: [172.16.1.4] Scope Id: []
1143
1144 NetBIOS Remote Machine Name Table
1145
1146 Name Type Status
1147 ---------------------------------------------
1148 TOLTEC &lt;00&gt; UNIQUE Registered
1149 TOLTEC &lt;03&gt; UNIQUE Registered
1150 TOLTEC &lt;20&gt; UNIQUE Registered
1151 ..__MSBROWSE__.&lt;01&gt; GROUP Registered
1152 METRAN &lt;00&gt; GROUP Registered
1153 METRAN &lt;1B&gt; UNIQUE Registered
1154 METRAN &lt;1C&gt; GROUP Registered
1155 METRAN &lt;1D&gt; UNIQUE Registered
1156 METRAN &lt;1E&gt; GROUP Registered
1157
1158 MAC Address = 00-00-00-00-00-00</pre></blockquote>
1159
1160<p>The resource entry that you're looking for is
1161<tt class="literal">.._ _MSBROWSE_ _.&lt;01&gt;</tt><a name="INDEX-50"/>. This indicates
1162that the server is currently acting as the local master browser for
1163the current subnet. If the machine is a Samba server, you can check
1164the Samba <em class="filename">nmbd</em> log file for an entry such as:</p>
1165
1166<blockquote><pre class="code">nmbd/nmbd_become_lmb.c:become_local_master_stage2(406)
1167*****
1168Samba name server TOLTEC is now a local master browser for
1169workgroup METRAN on subnet 172.16.1.0</pre></blockquote>
1170
1171<p>Or, you can use the
1172<em class="emphasis">nmblookup</em><a name="INDEX-51"/> command with the
1173<em class="emphasis">-M</em> option and the workgroup or domain name on
1174any Samba server to find the IP address of the local master:</p>
1175
1176<a name="INDEX-52"/><blockquote><pre class="code">$ <tt class="userinput"><b>nmblookup -M metran</b></tt>
1177querying metran on 172.16.1.255
1178172.16.1.1 metran&lt;1d&gt;</pre></blockquote>
1179
1180
1181</div>
1182
1183
1184<div class="sect2"><a name="samba2-CHP-7-SECT-2.3"/>
1185
1186<h3 class="head2">Server Announcements</h3>
1187
1188<p><a name="INDEX-53"/>After
1189the master browser election is decided, each server on the network
1190announces itself to the network to allow the master and backup
1191browsers to build their browse lists. At first, the server
1192announcements happen every minute, but the interval is gradually
1193stretched out to every 12 minutes. When a server is shut down
1194gracefully, it sends an announcement that it is going offline to
1195allow the master and backup browsers to remove it from the browse
1196list. However, when a server goes offline by crashing or by some
1197other failure, the master browser notices its disappearance only
1198because it stops receiving server announcements. The master browser
1199waits for three of the server's announcement periods
1200before deciding that it is offline, which can take up to 36 minutes.
1201Because backup browsers have their browse lists updated from the
1202master browser once every 15 minutes, it can take up to 51 minutes
1203for clients to be informed of a failed server.</p>
1204
1205<p>For more detailed information on Microsoft's
1206browsing protocols, consult the Microsoft documents
1207<em class="citetitle">Browsing and Windows 95
1208Networking</em><a name="INDEX-54"/> and
1209<em class="citetitle">CIFS/E Browser Protocol</em>. You can find these by
1210searching for the titles on the Microsoft web site at <a href="http://www.microsoft.com">http://www.microsoft.com</a>.</p>
1211
1212<p>More information on configuring Samba for browsing can be found in
1213<em class="filename">BROWSING.txt</em><a name="INDEX-55"/> and
1214<em class="filename">BROWSING-Config.txt</em> in the Samba
1215distribution's <em class="filename">docs/textdocs</em>
1216directory. <a name="INDEX-56"/></p>
1217
1218
1219</div>
1220
1221
1222<div class="sect2"><a name="samba2-CHP-7-SECT-2.4"/>
1223
1224<h3 class="head2">Configuring Samba for Browsing</h3>
1225
1226<p><a name="INDEX-57"/><a name="INDEX-58"/><a name="INDEX-59"/>Samba has full support for browsing
1227and can participate as a master browser, a backup browser, a domain
1228master browser, a potential browser, or just a server that
1229doesn't participate in browsing elections. If you
1230want to make sure your Samba server never becomes a master or backup
1231browser, simply set:</p>
1232
1233<a name="INDEX-60"/><blockquote><pre class="code">[global]
1234 local master = no</pre></blockquote>
1235
1236<p>Usually, you will want Samba to be available as a local master or at
1237least a backup browser. In the simplest case, you
1238don't need to do anything because
1239Samba's default is to participate in browsing
1240elections with its operating system value set to 20, which will beat
1241any Windows system less than a Windows NT/2000 primary domain
1242controller (see <a href="ch07.html#samba2-CHP-7-TABLE-2">Table 7-2</a>). The operating-system
1243value Samba reports for itself in browser elections can be set using
1244the <tt class="literal">os</tt><a name="INDEX-61"/> <tt class="literal">level</tt>
1245parameter:</p>
1246
1247<blockquote><pre class="code">[global]
1248 os level = 33</pre></blockquote>
1249
1250<p>The preceding value will allow Samba to beat even a Windows 2000
1251Advanced Server acting as a primary domain controller. As we show in
1252the following section, though, forcing Samba to win this way is not
1253recommended.</p>
1254
1255<p>If you want to allow a Windows XP Professional system to be the
1256master browser, you would need to set Samba lower:</p>
1257
1258<blockquote><pre class="code">[global]
1259 os level = 8</pre></blockquote>
1260
1261<p>The maximum value for <tt class="literal">os</tt> <tt class="literal">level</tt>
1262is 255 because it is handled as an 8-bit unsigned integer. Supposing
1263we wanted to make absolutely sure our Samba server will be the local
1264master browser at all times, we might say:</p>
1265
1266<blockquote><pre class="code">[global]
1267 local master = yes
1268 os level = 255
1269 preferred master = yes</pre></blockquote>
1270
1271<p>The addition of the
1272<tt class="literal">preferred</tt><a name="INDEX-62"/>
1273<tt class="literal">master</tt> parameter causes Samba to start a browser
1274election as soon as it starts up, and the <tt class="literal">os</tt>
1275<tt class="literal">level</tt> of 255 allows it to beat any other system on
1276the network. This includes other Samba servers, assuming they are
1277configured properly! If another server is using a similar
1278configuration file (with <tt class="literal">os</tt>
1279<tt class="literal">level</tt> <tt class="literal">=</tt> <tt class="literal">255</tt>
1280and <tt class="literal">preferred</tt> <tt class="literal">master</tt>
1281<tt class="literal">=</tt> <tt class="literal">yes</tt>), the two will fight each
1282other for the master browser role, winning elections based on minor
1283criteria, such as uptime or their current role. To avoid this, other
1284Samba servers should be set with a lower <tt class="literal">os</tt>
1285<tt class="literal">level</tt> and not configured to be the preferred
1286master.</p>
1287
1288
1289</div>
1290
1291
1292<div class="sect2"><a name="samba2-CHP-7-SECT-2.5"/>
1293
1294<h3 class="head2">Samba as the Domain Master Browser</h3>
1295
1296<p><a name="INDEX-63"/>Previously we mentioned that for a Windows
1297workgroup or domain to extend into multiple subnets, one system would
1298have to take the role of the domain master browser. The domain master
1299browser propagates browse lists across each subnet in the workgroup.
1300This works because each local master browser periodically
1301synchronizes its browse list with the domain master browser. During
1302this synchronization, the local master browser passes on the name of
1303any server that the domain master browser does not have in its browse
1304list, and vice versa. Each local master browser eventually holds the
1305browse list for the entire domain.</p>
1306
1307<p>There is no election to determine which machine assumes the role of
1308the domain master browser. Instead, the administrator has to set it
1309manually. By Microsoft design, however, the domain master browser and
1310the PDC both register a resource type of &lt;1B&gt;, so the
1311roles&mdash;and the machines&mdash;are inseparable.</p>
1312
1313<p>If you have a Windows NT server on the network acting as a PDC, we
1314recommend that you do not try to use Samba to become the domain
1315master browser. The reverse is true as well: if Samba is taking on
1316the responsibilities of a PDC, we recommend making it the domain
1317master browser as well. Although it is possible to split the roles
1318with Samba, this is not a good idea. Using two different machines to
1319serve as the PDC and the domain master browser can cause random
1320errors to occur in a Windows workgroup.</p>
1321
1322<p>Samba can assume the role of a domain master browser for all subnets
1323in the workgroup with the following options:</p>
1324
1325<blockquote><pre class="code">[global]
1326 domain master = yes
1327 preferred master = yes
1328 local master = yes
1329 os level = 255</pre></blockquote>
1330
1331<p>The final three parameters ensure that the server is also the local
1332master browser, which is vital for it to work properly as the domain
1333master browser. You can verify that a Samba machine is in fact the
1334<a name="INDEX-64"/>domain master browser by checking the
1335<em class="emphasis">nmbd</em><a name="INDEX-65"/><a name="INDEX-66"/> log file:</p>
1336
1337<blockquote><pre class="code">nmbd/nmbd_become_dmb.c:become_domain_master_stage2(118)
1338*****
1339Samba name server TOLTEC is now a domain master browser for
1340workgroup METRAN on subnet 172.16.1.0</pre></blockquote>
1341
1342<p>Or you can use the
1343<em class="emphasis">nmblookup</em><a name="INDEX-67"/> command that comes with the Samba
1344distribution to query for a unique &lt;1B&gt; resource type in the
1345workgroup:</p>
1346
1347<blockquote><pre class="code"># <tt class="userinput"><b>nmblookup METRAN#1B</b></tt>
1348Sending queries to 172.16.1.255
1349172.16.1.1 METRAN&lt;1b&gt;</pre></blockquote>
1350
1351
1352<div class="sect3"><a name="samba2-CHP-7-SECT-2.5.1"/>
1353
1354<h3 class="head3">Multiple subnets</h3>
1355
1356<p><a name="INDEX-68"/>You must
1357remember three rules when creating a
1358<a name="INDEX-69"/>workgroup/domain
1359that spans more than one subnet:</p>
1360
1361<ul><li>
1362<p>You must have either a Windows NT/2000 or Samba server acting as a
1363local master browser on each subnet in the workgroup/domain.</p>
1364</li><li>
1365<p>You must have a Windows NT/2000 Server edition or a Samba server
1366acting as a domain master browser somewhere in the workgroup/domain.</p>
1367</li><li>
1368<p>A WINS server should be on the network, with each system on the
1369network configured to use it for name resolution.</p>
1370</li></ul>
1371<p>Samba has some additional features you can use if you
1372don't have or want a domain master browser on your
1373network and still need to have <a name="INDEX-70"/>cross-subnet browsing. Consider the
1374subnets shown in <a href="ch07.html#samba2-CHP-7-FIG-1">Figure 7-1</a>.</p>
1375
1376<div class="figure"><a name="samba2-CHP-7-FIG-1"/><a name="INDEX-71"/><a name="INDEX-72"/><img src="figs/sam2_0701.gif"/></div><h4 class="head4">Figure 7-1. Multiple subnets with Samba servers</h4>
1377
1378<p>First, a Samba server that is a local master browser can use the
1379<tt class="literal">remote</tt><a name="INDEX-73"/> <tt class="literal">announce</tt>
1380configuration option to make sure that computers in different subnets
1381are sent broadcast announcements about the server. This has the
1382effect of ensuring that the Samba server appears in the browse lists
1383of foreign subnets. To achieve this, however, the directed broadcasts
1384must reach the local master browser on the other subnet. Be aware
1385that many routers do not allow directed broadcasts by default; you
1386might have to change this setting on the router for the directed
1387broadcasts to get through to its subnet.</p>
1388
1389<p>With the <tt class="literal">remote</tt> <tt class="literal">announce</tt>
1390option, list the subnets and the workgroup that should receive the
1391broadcast. For example, to ensure that machines in the 172.16.2 and
1392172.16.3 subnets and the METRAN workgroup are sent broadcast
1393information from our Samba server, we could specify the following:</p>
1394
1395<blockquote><pre class="code">[global]
1396 remote announce = 172.16.2.255/METRAN \
1397 172.16.3.255/METRAN</pre></blockquote>
1398
1399<p>Instead of supplying a broadcast address of the remote subnet, you
1400are allowed to specify the exact address where broadcasts should be
1401sent if the local master browser on the foreign subnet is guaranteed
1402to always have the same IP address.</p>
1403
1404<p>A Samba local master browser can synchronize its browse list directly
1405with one or more Samba servers, each acting as a local master browser
1406on a different subnet. This is another way to implement browsing
1407across subnets. For example, let's assume that Samba
1408is configured as a local master browser, and Samba local master
1409browsers exist at 172.16.2.130 and 172.16.3.120. We can use the
1410<tt class="literal">remote</tt> <tt class="literal">browse</tt>
1411<tt class="literal">sync</tt> option to sync directly with the Samba
1412servers, as follows:</p>
1413
1414<blockquote><pre class="code">[global]
1415 remote browse sync = 172.16.2.130 172.16.3.120</pre></blockquote>
1416
1417<p>For this to work, the other Samba machines must also be local master
1418browsers. You can also use directed broadcasts with this option if
1419you do not know specific IP addresses of local master browsers.</p>
1420
1421
1422</div>
1423
1424
1425</div>
1426
1427
1428<div class="sect2"><a name="samba2-CHP-7-SECT-2.6"/>
1429
1430<h3 class="head2">Making a Share Invisible</h3>
1431
1432<p><a name="INDEX-74"/><a name="INDEX-75"/><a name="INDEX-76"/>You can keep a share from being in the
1433browse list by using the
1434<tt class="literal">browsable</tt><a name="INDEX-77"/> option. This Boolean option
1435prevents a share from being seen in the Network Neighborhood or My
1436Network Places. For example, to prevent the <tt class="literal">[data]</tt>
1437share from being visible, we could write:</p>
1438
1439<blockquote><pre class="code">[data]
1440 path = /export/samba/userdata
1441 browsable = no</pre></blockquote>
1442
1443<p>Although you typically don't want to do this to an
1444ordinary disk share, the <tt class="literal">browsable</tt> option is
1445useful in the event that you need to create a share with contents
1446that you do not want others to see, such as a
1447<tt class="literal">[netlogon]</tt><a name="INDEX-78"/> share for storing logon scripts
1448for Windows domain control (see <a href="ch04.html">Chapter 4</a> for more
1449information on logon scripts).</p>
1450
1451<p>Another example is the
1452<tt class="literal">[homes]</tt><a name="INDEX-79"/> share. This share is often marked
1453nonbrowsable so that a share named <tt class="literal">[homes]</tt>
1454won't appear when its machine's
1455resources are browsed. However, if a user <tt class="literal">alice</tt>
1456logs on and looks at the machine's shares, an
1457<tt class="literal">[alice]</tt> share will appear under the machine.</p>
1458
1459<p>What if we wanted to make sure
1460<tt class="literal">alice</tt>'s share appeared to
1461everyone before she logs on? This could be done with the global
1462<tt class="literal">auto</tt><a name="INDEX-80"/> <tt class="literal">services</tt>
1463option. This option preloads shares into the browse list to ensure
1464that they are always visible:</p>
1465
1466<blockquote><pre class="code">[global]
1467 auto services = alice</pre></blockquote>
1468
1469
1470</div>
1471
1472
1473<div class="sect2"><a name="samba2-CHP-7-SECT-2.7"/>
1474
1475<h3 class="head2">Browsing Options</h3>
1476
1477<p><a href="ch07.html#samba2-CHP-7-TABLE-4">Table 7-4</a> <a name="INDEX-81"/><a name="INDEX-82"/>shows
1478options that define how Samba handles browsing tasks.</p>
1479
1480<a name="samba2-CHP-7-TABLE-4"/><h4 class="head4">Table 7-4. Browsing configuration options</h4><table border="1">
1481
1482
1483
1484
1485
1486
1487<tr>
1488<th>
1489<p>Option</p>
1490</th>
1491<th>
1492<p>Parameters</p>
1493</th>
1494<th>
1495<p>Function</p>
1496</th>
1497<th>
1498<p>Default</p>
1499</th>
1500<th>
1501<p>Scope</p>
1502</th>
1503</tr>
1504
1505
1506<tr>
1507<td>
1508<p><tt class="literal">announce as</tt></p>
1509</td>
1510<td>
1511<p>string</p>
1512</td>
1513<td>
1514<p>Operating system that Samba will announce itself as.</p>
1515</td>
1516<td>
1517<p><tt class="literal">N T Server</tt></p>
1518</td>
1519<td>
1520<p>Global</p>
1521</td>
1522</tr>
1523<tr>
1524<td>
1525<p><tt class="literal">announce</tt> <tt class="literal">version</tt></p>
1526</td>
1527<td>
1528<p>numeric</p>
1529</td>
1530<td>
1531<p>Version of the operating system that Samba will announce itself as.</p>
1532</td>
1533<td>
1534<p><tt class="literal">4.5</tt></p>
1535</td>
1536<td>
1537<p>Global</p>
1538</td>
1539</tr>
1540<tr>
1541<td>
1542<p><tt class="literal">browsable</tt> <tt class="literal">(browseable)</tt></p>
1543</td>
1544<td>
1545<p>Boolean</p>
1546</td>
1547<td>
1548<p>Allows share to be displayed in list of machine resources.</p>
1549</td>
1550<td>
1551<p><tt class="literal">yes</tt></p>
1552</td>
1553<td>
1554<p>Share</p>
1555</td>
1556</tr>
1557<tr>
1558<td>
1559<p><tt class="literal">browse list</tt></p>
1560</td>
1561<td>
1562<p>Boolean</p>
1563</td>
1564<td>
1565<p>If <tt class="literal">yes</tt>, allows Samba to provide a browse list on
1566this server.</p>
1567</td>
1568<td>
1569<p><tt class="literal">yes</tt></p>
1570</td>
1571<td>
1572<p>Global</p>
1573</td>
1574</tr>
1575<tr>
1576<td>
1577<p><tt class="literal">auto services</tt> <tt class="literal">(preload)</tt></p>
1578</td>
1579<td>
1580<p>string (share list)</p>
1581</td>
1582<td>
1583<p>List of shares that will always appear in the browse list.</p>
1584</td>
1585<td>
1586<p>None</p>
1587</td>
1588<td>
1589<p>Global</p>
1590</td>
1591</tr>
1592<tr>
1593<td>
1594<p><tt class="literal">default</tt> <tt class="literal">service (default)</tt></p>
1595</td>
1596<td>
1597<p>string (share name)</p>
1598</td>
1599<td>
1600<p>Name of a share (service) that will be provided if the client
1601requests a share not listed in <em class="emphasis">smb.conf</em>.</p>
1602</td>
1603<td>
1604<p>None</p>
1605</td>
1606<td>
1607<p>Global</p>
1608</td>
1609</tr>
1610<tr>
1611<td>
1612<p><tt class="literal">local master</tt></p>
1613</td>
1614<td>
1615<p>Boolean</p>
1616</td>
1617<td>
1618<p>If <tt class="literal">yes</tt>, allows Samba to participate in browsing
1619elections.</p>
1620</td>
1621<td>
1622<p><tt class="literal">yes</tt></p>
1623</td>
1624<td>
1625<p>Global</p>
1626</td>
1627</tr>
1628<tr>
1629<td>
1630<p><tt class="literal">lm announce</tt></p>
1631</td>
1632<td>
1633<p><tt class="literal">yes</tt>, <tt class="literal">no</tt>, or
1634<tt class="literal">auto</tt></p>
1635</td>
1636<td>
1637<p>Enables or disables LAN Manager-style host announcements.</p>
1638</td>
1639<td>
1640<p><tt class="literal">auto</tt></p>
1641</td>
1642<td>
1643<p>Global</p>
1644</td>
1645</tr>
1646<tr>
1647<td>
1648<p><tt class="literal">lm interval</tt></p>
1649</td>
1650<td>
1651<p>numeric</p>
1652</td>
1653<td>
1654<p>Frequency in seconds that LAN Manager announcements will be made if
1655activated.</p>
1656</td>
1657<td>
1658<p><tt class="literal">60</tt></p>
1659</td>
1660<td>
1661<p>Global</p>
1662</td>
1663</tr>
1664<tr>
1665<td>
1666<p><tt class="literal">preferred</tt> <tt class="literal">master (prefered
1667master)</tt></p>
1668</td>
1669<td>
1670<p>Boolean</p>
1671</td>
1672<td>
1673<p>If <tt class="literal">yes</tt>, allows Samba to use the preferred master
1674browser bit to attempt to become the local master browser.</p>
1675</td>
1676<td>
1677<p><tt class="literal">no</tt></p>
1678</td>
1679<td>
1680<p>Global</p>
1681</td>
1682</tr>
1683<tr>
1684<td>
1685<p><tt class="literal">domain master</tt></p>
1686</td>
1687<td>
1688<p>Boolean</p>
1689</td>
1690<td>
1691<p>If <tt class="literal">yes</tt>, allows Samba to become the domain browser
1692master for the workgroup or domain.</p>
1693</td>
1694<td>
1695<p><tt class="literal">no</tt></p>
1696</td>
1697<td>
1698<p>Global</p>
1699</td>
1700</tr>
1701<tr>
1702<td>
1703<p><tt class="literal">os level</tt></p>
1704</td>
1705<td>
1706<p>numeric</p>
1707</td>
1708<td>
1709<p>Operating system level of Samba in an election for local master
1710browser.</p>
1711</td>
1712<td>
1713<p><tt class="literal">0</tt></p>
1714</td>
1715<td>
1716<p>Global</p>
1717</td>
1718</tr>
1719<tr>
1720<td>
1721<p><tt class="literal">remote browse</tt> <tt class="literal">sync</tt></p>
1722</td>
1723<td>
1724<p>string (list of IP addresses)</p>
1725</td>
1726<td>
1727<p>Samba servers to synchronize browse lists with.</p>
1728</td>
1729<td>
1730<p>None</p>
1731</td>
1732<td>
1733<p>Global</p>
1734</td>
1735</tr>
1736<tr>
1737<td>
1738<p><tt class="literal">remote</tt> <tt class="literal">announce</tt></p>
1739</td>
1740<td>
1741<p>string (IP address/workgroup pairs)</p>
1742</td>
1743<td>
1744<p>Subnets and workgroups to send directed broadcast packets to,
1745allowing Samba to appear in their browse lists.</p>
1746</td>
1747<td>
1748<p>None</p>
1749</td>
1750<td>
1751<p>Global</p>
1752</td>
1753</tr>
1754
1755</table>
1756
1757
1758<div class="sect3"><a name="samba2-CHP-7-SECT-2.7.1"/>
1759
1760<a name="INDEX-83"/><h3 class="head3">announce as</h3>
1761
1762<p>This global configuration option specifies the type of operating
1763system that Samba announces to other machines on the network. The
1764default value for this option is <tt class="literal">N T</tt>
1765<tt class="literal">Server</tt>, which causes Samba to masquerade as a
1766Windows NT Server operating system. Other possible values are
1767<tt class="literal">NT</tt>, <tt class="literal">NT</tt>
1768<tt class="literal">Workstation</tt>, <tt class="literal">Win95</tt>, and
1769<tt class="literal">W f W</tt> for a Windows for Workgroup operating
1770system. You can override the default value with the following:</p>
1771
1772<blockquote><pre class="code">[global]
1773 announce as = Win95</pre></blockquote>
1774
1775<p>We recommend against changing the default value of this configuration
1776option.</p>
1777
1778
1779</div>
1780
1781
1782
1783<div class="sect3"><a name="samba2-CHP-7-SECT-2.7.2"/>
1784
1785<a name="INDEX-84"/><h3 class="head3">announce version</h3>
1786
1787<p>This global option is frequently used with the
1788<tt class="literal">announce</tt> <tt class="literal">as</tt> configuration
1789option; it specifies the version of the operating system that Samba
1790announces to other machines on the network. The default value of this
1791option is 4.5, which places Samba above Windows NT Version 4.0, but
1792below Windows 2000. You can specify a new value with a global entry
1793such as the following:</p>
1794
1795<blockquote><pre class="code">[global]
1796 announce version = 4.3</pre></blockquote>
1797
1798<p>We recommend against changing the default value of this configuration
1799option.</p>
1800
1801
1802</div>
1803
1804
1805
1806<div class="sect3"><a name="samba2-CHP-7-SECT-2.7.3"/>
1807
1808<h3 class="head3">browsable</h3>
1809
1810<p>The <tt class="literal">browsable</tt><a name="INDEX-85"/> option (also spelled
1811<tt class="literal">browseable</tt>) indicates whether the share referenced
1812should appear in the list of available resources for the system on
1813which it resides. This option is always set to <tt class="literal">yes</tt>
1814by default. If you wish to prevent the share from being seen in a
1815client's browser, you can reset this option to
1816<tt class="literal">no</tt>.</p>
1817
1818<p>Note that this does not prevent someone from accessing the share
1819using other means, such as specifying a UNC location (e.g.,
1820<tt class="literal">\\server\accounting)</tt> in Windows Explorer. It only
1821prevents the share from being listed under the
1822system's resources when being browsed.</p>
1823
1824
1825</div>
1826
1827
1828
1829<div class="sect3"><a name="samba2-CHP-7-SECT-2.7.4"/>
1830
1831<a name="INDEX-86"/><h3 class="head3">browse list</h3>
1832
1833<p>You should never need to change this parameter from its default value
1834of <tt class="literal">yes</tt>. If your Samba server is acting as a local
1835master browser (i.e., it has won the browsing election), you can use
1836the global <tt class="literal">browse</tt> <tt class="literal">list</tt> option
1837to instruct Samba to provide or withhold its browse list to all
1838clients. By default, Samba always provides a browse list. You can
1839withhold this information by specifying the following:</p>
1840
1841<blockquote><pre class="code">[global]
1842 browse list = no</pre></blockquote>
1843
1844<p>If you disable the browse list, clients cannot browse the names of
1845other machines, their services, and other domains currently available
1846on the network. Note that this won't make any
1847particular machine inaccessible; if someone knows a valid machine
1848name/address and a share on that machine, he can still connect to it
1849explicitly using the Windows <em class="emphasis">net use</em> command or
1850by mapping a drive letter to it using Windows Explorer. It simply
1851prevents information in the browse list from being retrieved by any
1852client that requests it.</p>
1853
1854
1855</div>
1856
1857
1858
1859<div class="sect3"><a name="samba2-CHP-7-SECT-2.7.5"/>
1860
1861<h3 class="head3">auto services</h3>
1862
1863<p>The global <tt class="literal">auto</tt><a name="INDEX-87"/>
1864<tt class="literal">services</tt> option, which is also called
1865<tt class="literal">preload</tt> <a name="INDEX-88"/>, ensures that the specified
1866shares are always visible in the browse list. One common use for this
1867option is to advertise specific user or printer shares that are
1868created by the <tt class="literal">[homes]</tt> or
1869<tt class="literal">[printers]</tt> shares, but are not otherwise
1870browsable.</p>
1871
1872<p>This option works best with disk shares. If you wish to force each of
1873your system printers (i.e., those listed in the printer capabilities
1874file) to appear in the browse list, we recommend using the
1875<tt class="literal">load</tt> <tt class="literal">printers</tt> option instead.</p>
1876
1877<p>Shares listed with the <tt class="literal">auto</tt>
1878<tt class="literal">services</tt> option will not be displayed if the
1879<tt class="literal">browse</tt> <tt class="literal">list</tt> option is set to
1880<tt class="literal">no</tt>.</p>
1881
1882
1883</div>
1884
1885
1886
1887<div class="sect3"><a name="samba2-CHP-7-SECT-2.7.6"/>
1888
1889<h3 class="head3">default service</h3>
1890
1891<p>The global <tt class="literal">default</tt><a name="INDEX-89"/>
1892<tt class="literal">service</tt> option (sometimes called
1893<tt class="literal">default</tt>) names a
1894&quot;last-ditch&quot; share. The value is
1895set to an existing share name without the enclosing brackets. When a
1896client requests a nonexistent disk or printer share, Samba will
1897attempt to connect the user to the share specified by this option
1898instead. The option is specified as follows:</p>
1899
1900<blockquote><pre class="code">[global]
1901 default service = helpshare</pre></blockquote>
1902
1903<p>When Samba redirects the requested, nonexistent service to the
1904service specified by <tt class="literal">default</tt>
1905<tt class="literal">service</tt>, the <tt class="literal">%S</tt> option takes on
1906the value of the requested service, with any underscores (
1907<tt class="literal">_</tt> ) in the requested service replaced by forward slashes
1908(<tt class="literal">/</tt>).</p>
1909
1910
1911</div>
1912
1913
1914
1915<div class="sect3"><a name="samba2-CHP-7-SECT-2.7.7"/>
1916
1917<a name="INDEX-90"/><h3 class="head3">local master</h3>
1918
1919<p>This global option specifies whether Samba will attempt to become the
1920local master browser for the subnet when it starts up. If this option
1921is set to <tt class="literal">yes</tt>, Samba will participate in
1922elections. However, setting this option by itself does not guarantee
1923victory. (Other parameters, such as <tt class="literal">preferred</tt>
1924<tt class="literal">master</tt> and <tt class="literal">os</tt>
1925<tt class="literal">level</tt>, help Samba win browsing elections.) If this
1926option is set to <tt class="literal">no</tt>, Samba will lose all browsing
1927elections, regardless of which values are specified by the other
1928configuration options. The default value is <tt class="literal">yes</tt>.</p>
1929
1930
1931</div>
1932
1933
1934
1935<div class="sect3"><a name="samba2-CHP-7-SECT-2.7.8"/>
1936
1937<h3 class="head3">lm announce</h3>
1938
1939<p>The global <tt class="literal">lm</tt><a name="INDEX-91"/>
1940<tt class="literal">announce</tt> option tells Samba's
1941<em class="emphasis">nmbd</em> whether to send <a name="INDEX-92"/>LAN Manager host
1942announcements on behalf of the server. These host announcements might
1943be required by older clients, such as IBM's OS/2
1944operating system. This announcement allows the server to be added to
1945the browse lists of the client. If activated, Samba will announce
1946itself repetitively at the number of seconds specified by the
1947<tt class="literal">lm</tt> <tt class="literal">interval</tt> option.</p>
1948
1949<p>You can specify the option as follows:</p>
1950
1951<blockquote><pre class="code">[global]
1952 lm announce = yes</pre></blockquote>
1953
1954<p>This configuration option takes the standard Boolean values,
1955<tt class="literal">yes</tt> and <tt class="literal">no</tt>, which enable or
1956disable LAN Manager announcements, respectively. In addition, a third
1957option, <tt class="literal">auto</tt>, causes <em class="emphasis">nmbd</em> to
1958listen passively for LAN Manager announcements, but not to send any
1959of its own initially. If LAN Manager announcements are detected for
1960another machine on the network, <em class="emphasis">nmbd</em> will start
1961sending its own LAN Manager announcements to ensure that it is
1962visible. The default value is <tt class="literal">auto</tt>. You probably
1963won't need to change this value from its default.</p>
1964
1965
1966</div>
1967
1968
1969
1970<div class="sect3"><a name="samba2-CHP-7-SECT-2.7.9"/>
1971
1972<a name="INDEX-93"/><h3 class="head3">lm interval</h3>
1973
1974<p>This option, which is used in conjunction with <tt class="literal">lm</tt>
1975<tt class="literal">announce</tt>, indicates the number of seconds
1976<em class="emphasis">nmbd</em> will wait before repeatedly broadcasting
1977LAN Manager-style announcements. LAN Manager announcements must be
1978enabled for this option to work. The default value is 60 seconds. If
1979you set this value to 0, Samba will not send any LAN Manager host
1980announcements, regardless of the value of the <tt class="literal">lm</tt>
1981<tt class="literal">announce</tt> option. You can reset the value of this
1982option as follows:</p>
1983
1984<blockquote><pre class="code">[global]
1985 lm interval = 90</pre></blockquote>
1986
1987
1988</div>
1989
1990
1991
1992<div class="sect3"><a name="samba2-CHP-7-SECT-2.7.10"/>
1993
1994<h3 class="head3">preferred master</h3>
1995
1996<p>The <tt class="literal">preferred</tt><a name="INDEX-94"/>
1997<tt class="literal">master</tt> option requests that Samba set the
1998preferred master bit when participating in an election. This gives
1999the server a higher preferred status in the workgroup than other
2000machines at the same operating-system level. If you are configuring
2001your Samba machine to become the local master browser, it is wise to
2002set the following value:</p>
2003
2004<blockquote><pre class="code">[global]
2005 preferred master = yes</pre></blockquote>
2006
2007<p>Otherwise, you should leave it set to its default,
2008<tt class="literal">no</tt>. If Samba is configured as a preferred master
2009browser, it will force an election when it first comes online.</p>
2010
2011
2012</div>
2013
2014
2015
2016<div class="sect3"><a name="samba2-CHP-7-SECT-2.7.11"/>
2017
2018<a name="INDEX-95"/><h3 class="head3">domain master</h3>
2019
2020<p>If Samba is the primary domain controller for your workgroup or NT
2021domain, it should also be made the domain master browser. The domain
2022master browser is a special machine that has the NetBIOS resource
2023type &lt;1B&gt; and is used to propagate browse lists to and from
2024each local master browser in individual subnets across the domain. To
2025force Samba to become the <a name="INDEX-96"/>domain master browser, set the following in
2026the <tt class="literal">[global]</tt> section of the
2027<em class="filename">smb.conf</em>:</p>
2028
2029<blockquote><pre class="code">[global]
2030 domain master = yes</pre></blockquote>
2031
2032<p>If you have a Windows NT server on the network acting as a primary
2033domain controller (PDC), we recommend that you do not use Samba to
2034become the domain master browser. The reverse is true as well: if
2035Samba is taking on the responsibilities of a PDC, we recommend making
2036it the domain master browser. Splitting the PDC and the domain master
2037browser will cause unpredictable errors to occur on the network.</p>
2038
2039
2040</div>
2041
2042
2043
2044<div class="sect3"><a name="samba2-CHP-7-SECT-2.7.12"/>
2045
2046<h3 class="head3">os level</h3>
2047
2048<p>The global <tt class="literal">os</tt><a name="INDEX-97"/> <tt class="literal">level</tt> option
2049defines the operating-system value with which Samba will masquerade
2050during a browser election. If you wish to have Samba win an election
2051and become the master browser, set the <tt class="literal">os</tt>
2052<tt class="literal">level</tt> higher than that of any other system on the
2053subnet. The values are shown in <a href="ch07.html#samba2-CHP-7-TABLE-2">Table 7-2</a>. The
2054default level is 20, which means that Samba will win elections
2055against all versions of Windows, except Windows NT/2000 if it is
2056operating as the PDC. If you wish Samba to win all elections, you can
2057set its operating system value as follows:</p>
2058
2059<blockquote><pre class="code">[global]
2060 os level = 255</pre></blockquote>
2061
2062
2063</div>
2064
2065
2066
2067<div class="sect3"><a name="samba2-CHP-7-SECT-2.7.13"/>
2068
2069<h3 class="head3">remote browse sync</h3>
2070
2071<p>The global <tt class="literal">remote</tt><a name="INDEX-98"/>
2072<tt class="literal">browse</tt> <tt class="literal">sync</tt> option specifies
2073that Samba should synchronize its browse lists with local master
2074browsers in other subnets. However, the synchronization can occur
2075only with other Samba servers and not with Windows computers. For
2076example, if your Samba server were a master browser on the subnet
2077172.16.235, and Samba local master browsers existed on other subnets
2078located at 172.16.234.92 and 172.16.236.2, you would specify the
2079following:</p>
2080
2081<blockquote><pre class="code">[global]
2082 remote browse sync = 172.16.234.92 172.16.236.2</pre></blockquote>
2083
2084<p>The Samba server would then directly contact the other machines on
2085the address list and synchronize browse lists. You can also say:</p>
2086
2087<blockquote><pre class="code">[global]
2088 remote browse sync = 172.16.234.255 172.16.236.255</pre></blockquote>
2089
2090<p>This forces Samba to broadcast queries to determine the IP addresses
2091of the local master browser on each subnet, with which it will then
2092synchronize browse lists. This works, however, only if your router
2093doesn't block directed broadcast requests ending in
2094255.</p>
2095
2096
2097</div>
2098
2099
2100
2101<div class="sect3"><a name="samba2-CHP-7-SECT-2.7.14"/>
2102
2103<h3 class="head3">remote announce</h3>
2104
2105<p>Samba servers are capable of providing browse lists to foreign
2106subnets with the <tt class="literal">remote</tt><a name="INDEX-99"/>
2107<tt class="literal">announce</tt> option. This is typically sent to the
2108local master browser of the foreign subnet in question. However, if
2109you do not know the address of the local master browser, you can do
2110the following:</p>
2111
2112<blockquote><pre class="code">[global]
2113 remote announce = 172.16.234.255/ACCOUNTING \
2114 172.16.236.255/ACCOUNTING</pre></blockquote>
2115
2116<p>With this, Samba will broadcast host announcements to all machines on
2117subnets 172.16.234 and 172.16.236, which will hopefully reach the
2118local master browser of the subnet.</p>
2119
2120<p>You can also specify exact IP addresses, if they are known, but this
2121works only if the systems are guaranteed to maintain the role of
2122master browser on their subnets. By appending a workgroup or domain
2123name to the IP address, Samba announces that it is in that workgroup
2124or domain. If this is left out, the workgroup set by the
2125<tt class="literal">workgroup</tt> parameter is used. <a name="INDEX-100"/> <a name="INDEX-101"/><a name="INDEX-102"/></p>
2126
2127
2128</div>
2129
2130
2131</div>
2132
2133
2134</div>
2135
2136<hr/><h4 class="head4">Footnotes</h4><blockquote><a name="FOOTNOTE-1"/> <p><a href="#FNPTR-1">[1]</a> As we explained in
2137<a href="ch01.html">Chapter 1</a>, a system can register under more than
2138one NetBIOS name. We use the singular here only to keep our
2139explanation simple.</p> </blockquote><hr/><h4 class="head4"><a href="toc.html">TOC</a></h4></body></html>
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