Context Navigation

← Previous Revision
Next Revision →
Blame
Revision Log

source: branches/samba-3.3.x/docs/htmldocs/using_samba/ch01.html

Visit:

Last change on this file was 218, checked in by Herwig Bauernfeind, 16 years ago
Import Samba 3.3 branch at 3.3.0 level docs htmldocs (psmedley's port)
File size: 108.0 KB

Line
1	<html>
2	<body bgcolor="#ffffff">
3
4	<img src="samba2_xs.gif" border="0" alt=" " height="100" width="76"
5	hspace="10" align="left" />
6
7	<h1 class="head0">Chapter 1. Learning the Samba</h1>
8
9
10	<p><a name="INDEX-1"/>Samba
11	is an extremely useful networking tool for anyone who has both
12	Windows and Unix systems on his network. Running on a Unix system, it
13	allows Windows to share files and printers on the Unix host, and it
14	also allows Unix users to access resources shared by Windows systems.</p>
15
16	<p>Although it might seem natural to use a Windows server to serve files
17	and printers to a network containing Windows clients, there are good
18	reasons for preferring a Samba server for this duty. Samba is
19	reliable software that runs on reliable Unix operating systems,
20	resulting in fewer problems and a low cost of maintenance. Samba also
21	offers better performance under heavy loads, outperforming Windows
22	2000 Server by a factor of 2 to 1 on identical PC hardware, according
23	to published third-party benchmarks. When common, inexpensive PC
24	hardware fails to meet the demands of a huge client load, the Samba
25	server can easily be moved to a proprietary "big
26	iron" Unix mainframe, which can outperform Windows
27	running on a PC many times. If all that weren't
28	enough, Samba has a very nice cost advantage: it's
29	free. Not only is the software itself freely available, but also no
30	client licenses are required, and it runs on high-quality, free
31	operating systems such as Linux and FreeBSD.</p>
32
33	<p>After reading the previous paragraph, you might come to the
34	conclusion that Samba is commonly used by large organizations with
35	thousands of users on their networks—and you'd
36	be right! But Samba's user base includes
37	organizations all over the planet, of all types and sizes: from
38	international corporations, to medium and small businesses, to
39	individuals who run Samba on their Linux laptops. In the last case, a
40	tool such as VMware is used to run Windows on the same computer, with
41	Samba enabling the two operating systems to share files.</p>
42
43	<p>The types of users vary even more—Samba is used by
44	corporations, banks and other financial institutions, government and
45	military organizations, schools, public libraries, art galleries,
46	families, and even authors! This book was developed on a Linux system
47	running VMware and Windows 2000, with Adobe FrameMaker running on
48	Windows and the document files served by Samba from the Linux
49	filesystem.</p>
50
51	<p>Does all this whet your technological appetite? If so, we encourage
52	you to keep reading, learn about Samba, and follow our examples to
53	set up a Samba server of your own. In this and upcoming chapters, we
54	will tell you exactly how to get started.</p>
55
56
57
58	<div class="sect1"><a name="samba2-CHP-1-SECT-1"/>
59
60	<h2 class="head1">What Is Samba?</h2>
61
62	<p><a name="INDEX-2"/>Samba
63	is a suite of Unix applications that speak the
64	<a name="INDEX-3"/><a name="INDEX-4"/>Server
65	Message Block (SMB) protocol. Microsoft Windows operating systems and
66	the OS/2 operating system use SMB to perform client-server networking
67	for file and printer sharing and associated operations. By supporting
68	this protocol, Samba enables computers running Unix to get in on the
69	action, communicating with the same networking protocol as Microsoft
70	Windows and appearing as another Windows system on the network from
71	the perspective of a Windows client. A <a name="INDEX-5"/>Samba
72	server offers the following services:</p>
73
74	<ul><li>
75	<p>Share one or more directory trees</p>
76	</li><li>
77	<p>Share one or more Distributed filesystem (Dfs) trees</p>
78	</li><li>
79	<p>Share printers installed on the server among Windows clients on the
80	network</p>
81	</li><li>
82	<p>Assist clients with network browsing</p>
83	</li><li>
84	<p>Authenticate clients logging onto a Windows domain</p>
85	</li><li>
86	<p>Provide or assist with Windows Internet Name Service (WINS)
87	name-server resolution</p>
88	</li></ul>
89	<p>The Samba suite also includes client tools that allow users on a Unix
90	system to access folders and printers that Windows systems and Samba
91	servers offer on the network.</p>
92
93	<p>Samba is the brainchild of Andrew <a name="INDEX-6"/>Tridgell, who currently heads the Samba
94	development team. Andrew started the project in 1991, while working
95	with a Digital Equipment Corporation (DEC) software suite called
96	Pathworks, created for connecting DEC VAX computers to computers made
97	by other companies. Without knowing the significance of what he was
98	doing, Andrew created a file-server program for an odd protocol that
99	was part of Pathworks. That protocol later turned out to be SMB. A
100	few years later, he expanded upon his custom-made SMB server and
101	began distributing it as a product on the Internet under the name
102	"SMB Server." However, Andrew
103	couldn't keep that name—it already belonged to
104	another company's product—so he tried the
105	following Unix renaming approach:</p>
106
107	<blockquote><pre class="code">$ <tt class="userinput"><b>grep -i '^s.m.b' /usr/dict/words</b></tt></pre></blockquote>
108
109	<p>And the response was:</p>
110
111	<blockquote><pre class="code">salmonberry
112	samba
113	sawtimber
114	scramble</pre></blockquote>
115
116	<p>Thus, the name "Samba" was born.</p>
117
118	<p>Today, the Samba suite revolves around a pair of Unix daemons that
119	provide shared resources—called <em class="firstterm">shares
120	</em>or s<em class="firstterm">ervices</em>—to SMB clients
121	on the network. These are:</p>
122
123	<dl>
124	<dt><b><a name="INDEX-7"/>smbd</b></dt>
125	<dd>
126	<p>A daemon that handles file and printer sharing and provides
127	authentication and authorization for SMB clients.</p>
128	</dd>
129
130
131
132	<dt><b><a name="INDEX-8"/>nmbd</b></dt>
133	<dd>
134	<p>A daemon that supports NetBIOS Name Service and WINS, which is
135	Microsoft's implementation of a NetBIOS Name Server
136	(NBNS). It also assists with network browsing.</p>
137	</dd>
138
139	</dl>
140
141	<p>Samba is currently maintained and extended by a group of volunteers
142	under the active supervision of Andrew Tridgell. Like the Linux
143	operating system, Samba is distributed as open source software
144	(<a href="http://opensource.org">http://opensource.org</a>) by its
145	authors and is distributed under the GNU General Public License
146	(GPL). Since its inception, development of Samba has been sponsored
147	in part by the Australian National University, where Andrew Tridgell
148	earned his Ph.D. Since then, many other organizations have sponsored
149	Samba developers, including LinuxCare, VA Linux Systems,
150	Hewlett-Packard, and IBM. It is a true testament to Samba that both
151	commercial and noncommercial entities are prepared to spend money to
152	support an open source effort.</p>
153
154	<p>Microsoft has also contributed by offering its definition of the SMB
155	protocol to the Internet Engineering Task Force (IETF) in 1996 as the
156	<a name="INDEX-9"/><a name="INDEX-10"/>Common
157	Internet File System (CIFS). Although we prefer to use the term
158	"SMB" in this book, you will also
159	often find the protocol being referred to as
160	"CIFS." This is especially true on
161	Microsoft's web site.</p>
162
163
164	</div>
165
166
167
168	<div class="sect1"><a name="samba2-CHP-1-SECT-2"/>
169
170	<h2 class="head1">What Can Samba Do for Me?</h2>
171
172	<p><a name="INDEX-11"/>As explained earlier, Samba can help
173	Windows and Unix computers coexist in the same network. However,
174	there are some specific reasons why you might want to set up a Samba
175	server on your network:</p>
176
177	<ul><li>
178	<p>You don't want to pay for—or
179	can't afford—a full-fledged Windows server,
180	yet you still need the functionality that one provides.</p>
181	</li><li>
182	<p>The Client Access Licenses (CALs) that Microsoft requires for each
183	Windows client to access a Windows server are unaffordable.</p>
184	</li><li>
185	<p>You want to provide a common area for data or user directories to
186	transition from a Windows server to a Unix one, or vice versa.</p>
187	</li><li>
188	<p>You want to share printers among Windows and Unix workstations.</p>
189	</li><li>
190	<p>You are supporting a group of computer users who have a mixture of
191	Windows and Unix computers.</p>
192	</li><li>
193	<p>You want to integrate Unix and Windows authentication, maintaining a
194	single database of user accounts that works with both systems.</p>
195	</li><li>
196	<p>You want to network Unix, Windows, Macintosh (OS X), and other
197	systems using a single protocol.</p>
198	</li></ul>
199	<p>Let's take a quick tour of
200	<a name="INDEX-12"/>Samba in action. Assume that we have
201	the following basic network configuration: a Samba-enabled Unix
202	system, to which we will assign the name <tt class="literal">toltec</tt>,
203	and a pair of Windows clients, to which we will assign the names
204	<tt class="literal">maya</tt> and <tt class="literal">aztec</tt>, all connected
205	via a local area network (LAN). Let's also assume
206	that <tt class="literal">toltec</tt> also has a local inkjet printer
207	connected to it, <tt class="literal">lp</tt>, and a disk share named
208	<tt class="literal">spirit</tt>—both of which it can offer to the
209	other two computers. A graphic of this network is shown in <a href="ch01.html#samba2-CHP-1-FIG-1">Figure 1-1</a>.</p>
210
211	<div class="figure"><a name="samba2-CHP-1-FIG-1"/><img src="figs/sam2_0101.gif"/></div><h4 class="head4">Figure 1-1. A simple network set up with a Samba server</h4>
212
213	<p>In this network, each computer listed shares the same
214	<em class="firstterm">workgroup</em>. A workgroup is a group name tag
215	that identifies an arbitrary collection of computers and their
216	resources on an SMB network. Several workgroups can be on the network
217	at any time, but for our basic network example,
218	we'll have only one: the METRAN workgroup.</p>
219
220
221	<div class="sect2"><a name="samba2-CHP-1-SECT-2.1"/>
222
223	<h3 class="head2">Sharing a Disk Service</h3>
224
225	<p><a name="INDEX-13"/><a name="INDEX-14"/><a name="INDEX-15"/>If everything is properly
226	configured, we should be able to see the Samba server,
227	<tt class="literal">toltec</tt>, through the Network Neighborhood of the
228	<tt class="literal">maya</tt> Windows desktop. In fact, <a href="ch01.html#samba2-CHP-1-FIG-2">Figure 1-2</a> shows the Network Neighborhood of the
229	<tt class="literal">maya</tt> computer, including <tt class="literal">toltec</tt>
230	and each computer that resides in the METRAN workgroup. Note the
231	Entire Network icon at the top of the list. As we just mentioned,
232	more than one workgroup can be on an SMB network at any given time.
233	If a user clicks the Entire Network icon, she will see a list of all
234	the workgroups that currently exist on the network.</p>
235
236	<div class="figure"><a name="samba2-CHP-1-FIG-2"/><img src="figs/sam2_0102.gif"/></div><h4 class="head4">Figure 1-2. The Network Neighborhood directory</h4>
237
238	<p>We can take a closer look at the <tt class="literal">toltec</tt> server by
239	double-clicking its icon. This contacts <tt class="literal">toltec</tt>
240	itself and requests a list of its
241	<em class="firstterm">shares</em>—the file and printer
242	resources—that the computer provides. In this case, a printer
243	named <tt class="literal">lp</tt>, a home directory named
244	<tt class="literal">jay</tt>, and a disk share named
245	<tt class="literal">spirit</tt> are on the server, as shown in <a href="ch01.html#samba2-CHP-1-FIG-3">Figure 1-3</a>. Note that the Windows display shows hostnames
246	in mixed case (Toltec). Case is irrelevant in hostnames, so you might
247	see toltec, Toltec, and TOLTEC in various displays or command output,
248	but they all refer to a single system. Thanks to Samba, Windows 98
249	sees the Unix server as a valid SMB server and can access the
250	<tt class="literal">spirit</tt> folder as if it were just another system
251	folder.</p>
252
253	<div class="figure"><a name="samba2-CHP-1-FIG-3"/><img src="figs/sam2_0103.gif"/></div><h4 class="head4">Figure 1-3. Shares available on the Toltec server as viewed from maya</h4>
254
255	<p>One popular Windows feature is the ability to map a drive letter
256	(such as E:, F:, or Z:) to a shared directory on the network using
257	the Map Network Drive option in Windows Explorer.<a name="FNPTR-1"/><a href="#FOOTNOTE-1">[1]</a>
258	Once you do so, your applications can access the folder across the
259	network using the drive letter. You can store data on it, install and
260	run programs from it, and even password-protect it against unwanted
261	visitors. See <a href="ch01.html#samba2-CHP-1-FIG-4">Figure 1-4</a> for an example of mapping
262	a <a name="INDEX-16"/><a name="INDEX-17"/>drive letter to a network
263	directory.</p>
264
265	<div class="figure"><a name="samba2-CHP-1-FIG-4"/><img src="figs/sam2_0104.gif"/></div><h4 class="head4">Figure 1-4. Mapping a network drive to a Windows drive letter</h4>
266
267	<p>Take a look at the Path: entry in the dialog box of <a href="ch01.html#samba2-CHP-1-FIG-4">Figure 1-4</a>. An equivalent way to represent a directory on
268	a network computer is by using two backslashes, followed by the name
269	of the networked computer, another backslash, and the networked
270	directory of the computer, as shown here:</p>
271
272	<blockquote><pre class="code">\\<em class="replaceable">network-computer</em>\<em class="replaceable">directory</em></pre></blockquote>
273
274	<p>This is known as the <em class="firstterm"/><a name="INDEX-18"/>Universal
275	Naming Convention (UNC)</em> in the Windows world. For example, the dialog
276	box in <a href="ch01.html#samba2-CHP-1-FIG-4">Figure 1-4</a> represents the network directory
277	on the <tt class="literal">toltec</tt> server as:</p>
278
279	<blockquote><pre class="code">\\toltec\spirit</pre></blockquote>
280
281	<p>If this looks somewhat familiar to you, you're
282	probably thinking of <em class="firstterm">uniform resource
283	locators</em><a name="INDEX-19"/><a name="INDEX-20"/> (URLs), which are addresses that web
284	browsers such as Netscape Navigator and Internet Explorer use to
285	resolve systems across the Internet. Be sure not to confuse the two:
286	URLs such as <a href="http://www.oreilly.com">http://www.oreilly.com</a> use forward slashes
287	instead of backslashes, and they precede the initial slashes with the
288	data transfer protocol (i.e., ftp, http) and a colon (:). In reality,
289	URLs and UNCs are two completely separate things, although sometimes
290	you can specify an SMB share using a URL rather than a UNC. As a URL,
291	the <em class="filename">\\toltec\spirit</em> share would be specified as
292	<em class="filename">smb://toltec/spirit</em>.</p>
293
294	<p>Once the network drive is set up, Windows and its programs behave as
295	if the networked directory were a local disk. If you have any
296	applications that support multiuser functionality on a network, you
297	can install those programs on the network drive.<a name="FNPTR-2"/><a href="#FOOTNOTE-2">[2]</a> <a href="ch01.html#samba2-CHP-1-FIG-5">Figure 1-5</a> shows the
298	resulting network drive as it would appear with other storage devices
299	in the Windows 98 client. Note the pipeline attachment in the icon
300	for the J: drive; this indicates that it is a network drive rather
301	than a fixed drive.</p>
302
303	<div class="figure"><a name="samba2-CHP-1-FIG-5"/><img src="figs/sam2_0105.gif"/></div><h4 class="head4">Figure 1-5. The Network directory mapped to the client drive letter J</h4>
304
305	<p>My Network Places, found in Windows Me, 2000, and XP, works
306	differently from Network Neighborhood. It is necessary to click a few
307	more icons, but eventually we can get to the view of the
308	<tt class="literal">toltec</tt> server as shown in <a href="ch01.html#samba2-CHP-1-FIG-6">Figure 1-6</a>. This is from a Windows 2000 system. Setting
309	up the network drive using the Map Network Drive option in Windows
310	2000 works similarly to other Windows versions. <a name="INDEX-21"/><a name="INDEX-22"/><a name="INDEX-23"/></p>
311
312	<div class="figure"><a name="samba2-CHP-1-FIG-6"/><img src="figs/sam2_0106.gif"/></div><h4 class="head4">Figure 1-6. Shares available on Toltec (viewed from dine)</h4>
313
314
315	</div>
316
317
318	<div class="sect2"><a name="samba2-CHP-1-SECT-2.2"/>
319
320	<h3 class="head2">Sharing a Printer</h3>
321
322	<p><a name="INDEX-24"/><a name="INDEX-25"/><a name="INDEX-26"/>You probably noticed that the printer
323	<tt class="literal">lp</tt> appeared under the available shares for
324	<tt class="literal">toltec</tt> in <a href="ch01.html#samba2-CHP-1-FIG-3">Figure 1-3</a>. This
325	indicates that the Unix server has a printer that can be shared by
326	the various SMB clients in the workgroup. Data sent to the printer
327	from any of the clients will be spooled on the Unix server and
328	printed in the order in which it is received.</p>
329
330	<p><a name="INDEX-27"/><a name="INDEX-28"/>Setting up a Samba-enabled
331	printer on the Windows side is even easier than setting up a disk
332	share. By double-clicking the printer and identifying the
333	manufacturer and model, you can install a driver for this printer on
334	the Windows client. Windows can then properly format any information
335	sent to the network printer and access it as if it were a local
336	printer. On Windows 98, double-clicking the Printers icon in the
337	Control Panel opens the Printers window shown in <a href="ch01.html#samba2-CHP-1-FIG-7">Figure 1-7</a>. Again, note the pipeline attachment below the
338	printer, which identifies it as being on a network.</p>
339
340	<div class="figure"><a name="samba2-CHP-1-FIG-7"/><img src="figs/sam2_0107.gif"/></div><h4 class="head4">Figure 1-7. A network printer available on Toltec</h4>
341
342
343	<div class="sect3"><a name="samba2-CHP-1-SECT-2.2.1"/>
344
345	<h3 class="head3">Seeing things from the Unix side</h3>
346
347	<p><a name="INDEX-29"/><a name="INDEX-30"/>As mentioned earlier, Samba
348	appears in Unix as a set of daemon programs. You can view them with
349	the Unix <a name="INDEX-31"/><em class="emphasis">ps</em> command; you can
350	read any messages they generate through custom debug files or the
351	Unix <em class="emphasis">syslog</em> (depending on how Samba is set up);
352	and you can configure them from a single Samba configuration file:
353	<em class="emphasis">smb.conf</em>. In addition, if you want to get an idea of
354	what the daemons are doing, Samba has a program called
355	<em class="emphasis">smbstatus</em><a name="INDEX-32"/> that will lay it all on the line. Here
356	is how it works:</p>
357
358	<blockquote><pre class="code"># <tt class="userinput"><b>smbstatus</b></tt>
359	Processing section "[homes]"
360	Processing section "[printers]"
361	Processing section "[spirit]"
362
363	Samba version 2.2.6
364	Service uid gid pid machine
365	-----------------------------------------
366	spirit jay jay 7735 maya (172.16.1.6) Sun Aug 12 12:17:14 2002
367	spirit jay jay 7779 aztec (172.16.1.2) Sun Aug 12 12:49:11 2002
368	jay jay jay 7735 maya (172.16.1.6) Sun Aug 12 12:56:19 2002
369
370	Locked files:
371	Pid DenyMode R/W Oplock Name
372	--------------------------------------------------
373	7735 DENY_WRITE RDONLY NONE /u/RegClean.exe Sun Aug 12 13:01:22 2002
374
375	Share mode memory usage (bytes):
376	1048368(99%) free + 136(0%) used + 72(0%) overhead = 1048576(100%) total</pre></blockquote>
377
378	<p>The Samba status from this output provides three sets of data, each
379	divided into separate sections. The first section tells which systems
380	have connected to the Samba server, identifying each client by its
381	machine name (<tt class="literal">maya</tt> and <tt class="literal">aztec</tt>)
382	and IP (Internet Protocol) address. The second section reports the
383	name and status of the files that are currently in use on a share on
384	the server, including the read/write status and any locks on the
385	files. Finally, Samba reports the amount of memory it has currently
386	allocated to the shares that it administers, including the amount
387	actively used by the shares plus additional overhead. (Note that this
388	is not the same as the total amount of memory that the
389	<em class="emphasis">smbd</em> or <em class="emphasis">nmbd</em> processes are
390	using.)</p>
391
392	<p>Don't worry if you don't understand
393	these statistics; they will become easier to understand as you move
394	through the book.</p>
395
396
397	</div>
398
399
400	</div>
401
402
403	</div>
404
405
406
407	<div class="sect1"><a name="samba2-CHP-1-SECT-3"/>
408
409	<h2 class="head1">Getting Familiar with an SMB Network</h2>
410
411	<p><a name="INDEX-33"/>Now that you have had a brief tour of
412	Samba, let's take some time to get familiar with
413	Samba's adopted environment: an SMB network.
414	Networking with SMB is significantly different from working with
415	common TCP/IP protocols such as FTP and Telnet because there are
416	several new concepts to learn and a lot of information to cover.
417	First, we will discuss the basic concepts behind an SMB network,
418	followed by some Microsoft implementations of it, and finally we will
419	show you where a Samba server can and cannot fit into the picture.</p>
420
421
422	<div class="sect2"><a name="samba2-CHP-1-SECT-3.1"/>
423
424	<h3 class="head2">Understanding NetBIOS</h3>
425
426	<p>To begin, let's step back in time. In 1984, IBM
427	authored a simple application programming interface (API) for
428	networking its computers, called the <em class="firstterm">Network Basic
429	Input/Output System
430	</em>(<a name="INDEX-34"/>NetBIOS).
431	The NetBIOS API provided a rudimentary design for an application to
432	connect and share data with other computers.</p>
433
434	<p>It's helpful to think of the NetBIOS API as
435	networking extensions to the standard BIOS API calls. The BIOS
436	contains low-level code for performing filesystem operations on the
437	local computer. NetBIOS originally had to exchange instructions with
438	computers across IBM PC or Token Ring networks. It therefore required
439	a low-level transport protocol to carry its requests from one
440	computer to the next.</p>
441
442	<p>In late 1985, IBM released one such protocol, which it merged with
443	the NetBIOS API to become the <em class="firstterm">NetBIOS Extended User
444	Interface</em> (<em class="emphasis">NetBEUI</em> ).
445	<a name="INDEX-35"/>NetBEUI was
446	designed for small LANs, and it let each computer claim a name (up to
447	15 characters) that wasn't already in use on the
448	network. By a "small LAN," we mean
449	fewer than 255 nodes on the network—which was considered a
450	generous number in 1985!</p>
451
452	<p>The NetBEUI protocol was very popular with networking applications,
453	including those running under Windows for Workgroups. Later,
454	implementations of NetBIOS over Novell's IPX
455	networking protocols also emerged, which competed with NetBEUI.
456	However, the networking protocols of choice for the burgeoning
457	Internet community were TCP/IP and UDP/IP, and implementing the
458	NetBIOS APIs over those protocols soon became a necessity.</p>
459
460	<p>Recall that TCP/IP uses numbers to represent computer addresses
461	(192.168.220.100, for instance) while NetBIOS uses only names. This
462	was a major issue when trying to mesh the two protocols together. In
463	1987, the IETF published standardization documents, titled RFC 1001
464	and 1002, that outlined how NetBIOS would work over a TCP/UDP
465	network. This set of documents still governs each implementation that
466	exists today, including those provided by Microsoft with its Windows
467	operating systems, as well as the Samba suite.</p>
468
469	<p>Since then, the standard that this document governs has become known
470	as <em class="firstterm">NetBIOS over
471	TCP/IP</em><a name="INDEX-36"/><a name="INDEX-37"/><a name="INDEX-38"/>, or NBT for short.<a name="FNPTR-3"/><a href="#FOOTNOTE-3">[3]</a> </p>
472
473	<p>The NBT standard (RFC 1001/1002)
474	currently outlines a trio of services on a network:</p>
475
476	<ul><li>
477	<p>A name service</p>
478	</li><li>
479	<p>Two communication services:</p>
480	<ul><li>
481	<p>Datagrams</p>
482	</li>
483
484	<li>
485	<p>Sessions</p>
486	</li></ul>
487	</li>
488	</ul>
489
490	<p>The <a name="INDEX-39"/>name
491	service solves the name-to-address problem mentioned earlier; it
492	allows each computer to declare a specific name on the network that
493	can be translated to a machine-readable IP address, much like
494	today's Domain Name System (DNS) on the Internet.
495	The <a name="INDEX-40"/>datagram and <a name="INDEX-41"/>session services are both
496	secondary communication protocols used to transmit data back and
497	forth from NetBIOS computers across the network.</p>
498
499
500	</div>
501
502
503	<div class="sect2"><a name="samba2-CHP-1-SECT-3.2"/>
504
505	<h3 class="head2">Getting a Name</h3>
506
507	<p><a name="INDEX-42"/><a name="INDEX-43"/>In the NetBIOS world, when each
508	computer comes online, it wants to claim a name for itself; this is
509	called <em class="firstterm">name registration</em>. However, no two
510	computers in the same workgroup should be able to claim the same
511	name; this would cause endless confusion for any computer that wanted
512	to communicate with either of them. There are two different
513	approaches to ensuring that this doesn't happen:</p>
514
515	<ul><li>
516	<p>Use an <em class="firstterm"/>NBNS</em> to keep track of which hosts have
517	registered a NetBIOS name.</p>
518	</li><li>
519	<p>Allow each computer on the network to defend its name in the event
520	that another computer attempts to use it.</p>
521	</li></ul>
522	<p><a href="ch01.html#samba2-CHP-1-FIG-8">Figure 1-8</a> illustrates a (failed) name
523	registration, with and without an NBNS.</p>
524
525	<div class="figure"><a name="samba2-CHP-1-FIG-8"/><img src="figs/sam2_0108.gif"/></div><h4 class="head4">Figure 1-8. Broadcast versus NBNS name registration</h4>
526
527	<p><a name="INDEX-44"/><a name="INDEX-45"/>As mentioned earlier,
528	there must be a way to resolve a NetBIOS name to a specific IP
529	address; this is known as <em class="firstterm">name resolution</em>.
530	There are two different approaches with NBT here as well:</p>
531
532	<ul><li>
533	<p>Have each computer report back its IP address when it
534	"hears" a broadcast request for its
535	NetBIOS name.</p>
536	</li><li>
537	<p>Use an NBNS to help resolve NetBIOS names to IP addresses.</p>
538	</li></ul>
539	<p><a href="ch01.html#samba2-CHP-1-FIG-9">Figure 1-9</a> illustrates the two types of name
540	resolution.</p>
541
542	<div class="figure"><a name="samba2-CHP-1-FIG-9"/><img src="figs/sam2_0109.gif"/></div><h4 class="head4">Figure 1-9. Broadcast versus NBNS name resolution</h4>
543
544	<p>As you might expect, having an NBNS on your network can help out
545	tremendously. To see exactly why, let's look at the
546	broadcast method.</p>
547
548	<p>Here, when a client computer boots, it will
549	<a name="INDEX-46"/>broadcast a
550	message declaring that it wishes to register a specified NetBIOS name
551	as its own. If nobody objects to the use of the name, it keeps the
552	name. On the other hand, if another computer on the local subnet is
553	currently using the requested name, it will send a message back to
554	the requesting client that the name is already taken. This is known
555	as <em class="firstterm">defending</em><a name="INDEX-47"/><a name="INDEX-48"/> the hostname. This type of system
556	comes in handy when one client has unexpectedly dropped off the
557	network—another can take its name unchallenged—but it
558	does incur an inordinate amount of traffic on the network for
559	something as simple as name registration.</p>
560
561	<p>With an NBNS, the same thing occurs, except the communication is
562	confined to the requesting computer and the NBNS. No broadcasting
563	occurs when the computer wishes to register the name; the
564	registration message is simply sent directly from the client to the
565	NBNS, and the NBNS replies regardless of whether the name is already
566	taken. This is known as <em class="firstterm">point-to-point
567	communication</em><a name="INDEX-49"/>, and it is often beneficial on
568	networks with more than one subnet. This is because routers are
569	generally configured to block incoming packets that are broadcast to
570	all computers in the subnet.</p>
571
572	<p>The same principles apply to name resolution. Without an NBNS,
573	NetBIOS name resolution would also be done with a broadcast
574	mechanism. All request packets would be sent to each computer in the
575	network, with the hope that one computer that might be affected will
576	respond directly back to the computer that asked. Using an NBNS and
577	point-to-point communication for this purpose is far less taxing on
578	the network than flooding the network with broadcasts for every
579	name-resolution request.</p>
580
581	<p>It can be argued that broadcast packets do not cause significant
582	problems in modern, high-bandwidth networks of hosts with fast CPUs,
583	if only a small number of hosts are on the network, or the demand for
584	bandwidth is low. There are certainly cases where this is true;
585	however, our advice throughout this book is to avoid relying on
586	broadcasts as much as possible. This is a good rule to follow for
587	large, busy networks, and if you follow our advice when configuring a
588	small network, your network will be able to grow without encountering
589	problems later on that might be difficult to diagnose. <a name="INDEX-50"/><a name="INDEX-51"/></p>
590
591
592	</div>
593
594
595	<div class="sect2"><a name="samba2-CHP-1-SECT-3.3"/>
596
597	<h3 class="head2">Node Types</h3>
598
599	<p><a name="INDEX-52"/><a name="INDEX-53"/>How can you tell what strategy each
600	client on your network will use when performing name registration and
601	resolution? Each computer on an NBT network earns one of the
602	following designations, depending on how it handles name registration
603	and resolution: <a name="INDEX-54"/><a name="INDEX-55"/><a name="INDEX-56"/><a name="INDEX-57"/>b-node, p-node, m-node, and h-node. The
604	behaviors of each type of node are summarized in <a href="ch01.html#samba2-CHP-1-TABLE-1">Table 1-1</a>.</p>
605
606	<a name="samba2-CHP-1-TABLE-1"/><h4 class="head4">Table 1-1. NetBIOS node types</h4><table border="1">
607
608
609
610	<tr>
611	<th>
612	<p>Role</p>
613	</th>
614	<th>
615	<p>Value</p>
616	</th>
617	</tr>
618
619
620	<tr>
621	<td>
622	<p>b-node</p>
623	</td>
624	<td>
625	<p>Uses broadcast registration and resolution only.</p>
626	</td>
627	</tr>
628	<tr>
629	<td>
630	<p>p-node</p>
631	</td>
632	<td>
633	<p>Uses point-to-point registration and resolution only.</p>
634	</td>
635	</tr>
636	<tr>
637	<td>
638	<p>m-node (mixed)</p>
639	</td>
640	<td>
641	<p>Uses broadcast for registration. If successful, it notifies the NBNS
642	of the result. Uses broadcast for resolution; uses the NBNS if
643	broadcast is unsuccessful.</p>
644	</td>
645	</tr>
646	<tr>
647	<td>
648	<p>h-node (hybrid)</p>
649	</td>
650	<td>
651	<p>Uses the NBNS for registration and resolution; uses broadcast if the
652	NBNS is unresponsive or inoperative.</p>
653	</td>
654	</tr>
655
656	</table>
657
658	<p>In the case of Windows clients, you will usually find them listed as
659	h-nodes or hybrid nodes. The first three node types appear in RFC
660	1001/1002, and h-nodes were invented later by Microsoft, as a more
661	fault-tolerant method.</p>
662
663	<p>You can find the node type of a Windows 95/98/Me computer by running
664	the <em class="emphasis">winipcfg</em><a name="INDEX-58"/><a name="INDEX-59"/> command from the Start
665	→ Run dialog (or from an MS-DOS prompt) and clicking
666	the More Info>> button. On Windows NT/2000/XP, you can use the
667	<tt class="literal">ipconfig</tt><a name="INDEX-60"/><a name="INDEX-61"/><a name="INDEX-62"/><a name="INDEX-63"/>
668	<tt class="literal">/all</tt> command in a command-prompt window. In either
669	case, search for the line that says <tt class="literal">Node Type</tt>.</p>
670
671
672	</div>
673
674
675	<div class="sect2"><a name="samba2-CHP-1-SECT-3.4"/>
676
677	<h3 class="head2">What's in a Name?</h3>
678
679	<p>The names <a name="INDEX-64"/><a name="INDEX-65"/>NetBIOS uses are quite different
680	from the DNS hostnames you might be familiar with. First, NetBIOS
681	names exist in a flat namespace. In other words, there are no
682	hierarchical levels, such as in <tt class="literal">oreilly.com</tt> (two
683	levels) or <em class="emphasis">ftp</em><em class="emphasis">.samba.org</em> (three
684	levels). NetBIOS names consist of a single unique string such as
685	<tt class="literal">navaho</tt> or <tt class="literal">hopi</tt> within each
686	workgroup or domain. Second, NetBIOS names are allowed to be only 15
687	characters and can consist only of standard alphanumeric characters
688	(a-z, A-Z, 0-9) and the following:</p>
689
690	<blockquote><pre class="code">! @ # $ % ^ & ( ) - ' { } . ~</pre></blockquote>
691
692	<p>Although you are allowed to use a <a name="INDEX-66"/><a name="INDEX-67"/><a name="INDEX-68"/>period (.) in a NetBIOS name, we recommend
693	against it because those names are not guaranteed to work in future
694	versions of NBT.</p>
695
696	<p>It's not a coincidence that all valid DNS names are
697	also valid NetBIOS names. In fact, the unqualified DNS name for a
698	Samba server is often reused as its NetBIOS name. For example, if you
699	had a system with a hostname of <tt class="literal">mixtec.ora.com</tt> ,
700	its NetBIOS name would likely be MIXTEC (followed by 9 spaces).</p>
701
702
703	<div class="sect3"><a name="samba2-CHP-1-SECT-3.4.1"/>
704
705	<h3 class="head3">Resource names and types</h3>
706
707	<p><a name="INDEX-69"/><a name="INDEX-70"/>With NetBIOS, a computer not
708	only advertises its presence, but also tells others what types of
709	services it offers. For example, <tt class="literal">mixtec</tt> can
710	indicate that it's not just a workstation, but that
711	it's also a file server and can receive Windows
712	Messenger messages. This is done by adding a 16th byte to the end of
713	the machine (resource) name, called the <em class="firstterm">resource
714	type</em>, and registering the name multiple times, once for
715	each service that it offers. See <a href="ch01.html#samba2-CHP-1-FIG-10">Figure 1-10</a>.</p>
716
717	<div class="figure"><a name="samba2-CHP-1-FIG-10"/><img src="figs/sam2_0110.gif"/></div><h4 class="head4">Figure 1-10. The structure of NetBIOS names</h4>
718
719	<p>The 1-byte resource type indicates a unique service that the named
720	computer provides. In this book, you will often see the resource type
721	shown in angled brackets (<>) after the NetBIOS name, such as:</p>
722
723	<blockquote><pre class="code">MIXTEC<00></pre></blockquote>
724
725	<p>You can see which names are registered for a particular NBT computer
726	using the Windows command-line
727	<em class="emphasis">nbtstat</em><a name="INDEX-71"/> utility.
728	Because these services are unique (i.e., there cannot be more than
729	one registered), you will see them listed as type UNIQUE in the
730	output. For example, the following partial output describes the
731	<tt class="literal">toltec</tt> server:</p>
732
733	<blockquote><pre class="code">C:\><tt class="userinput"><b>nbtstat -a toltec</b></tt>
734
735	NetBIOS Remote Machine Name Table
736	Name Type Status
737	---------------------------------------------
738	TOLTEC <00> UNIQUE Registered
739	TOLTEC <03> UNIQUE Registered
740	TOLTEC <20> UNIQUE Registered
741	...</pre></blockquote>
742
743	<p>This says the server has registered the NetBIOS name
744	<tt class="literal">toltec</tt> as a machine (computer) name, as a
745	recipient of messages from the Windows Messenger service, and as a
746	file server. Some possible attributes a name can have are listed in
747	<a href="ch01.html#samba2-CHP-1-TABLE-2">Table 1-2</a>.</p>
748
749	<a name="samba2-CHP-1-TABLE-2"/><h4 class="head4">Table 1-2. NetBIOS unique resource types</h4><table border="1">
750
751
752
753	<tr>
754	<th>
755	<p>Named resource</p>
756	</th>
757	<th>
758	<p>Hexadecimal byte value</p>
759	</th>
760	</tr>
761
762
763	<tr>
764	<td>
765	<p>Standard Workstation Service</p>
766	</td>
767	<td>
768	<p>00</p>
769	</td>
770	</tr>
771	<tr>
772	<td>
773	<p>Messenger Service</p>
774	</td>
775	<td>
776	<p>03</p>
777	</td>
778	</tr>
779	<tr>
780	<td>
781	<p>RAS Server Service</p>
782	</td>
783	<td>
784	<p>06</p>
785	</td>
786	</tr>
787	<tr>
788	<td>
789	<p>Domain Master Browser Service (associated with primary domain controller)</p>
790	</td>
791	<td>
792	<p>1B</p>
793	</td>
794	</tr>
795	<tr>
796	<td>
797	<p>Master Browser name</p>
798	</td>
799	<td>
800	<p>1D</p>
801	</td>
802	</tr>
803	<tr>
804	<td>
805	<p>NetDDE Service</p>
806	</td>
807	<td>
808	<p>1F</p>
809	</td>
810	</tr>
811	<tr>
812	<td>
813	<p>Fileserver (including printer server)</p>
814	</td>
815	<td>
816	<p>20</p>
817	</td>
818	</tr>
819	<tr>
820	<td>
821	<p>RAS Client Service</p>
822	</td>
823	<td>
824	<p>21</p>
825	</td>
826	</tr>
827	<tr>
828	<td>
829	<p>Network Monitor Agent</p>
830	</td>
831	<td>
832	<p>BE</p>
833	</td>
834	</tr>
835	<tr>
836	<td>
837	<p>Network Monitor Utility</p>
838	</td>
839	<td>
840	<p>BF</p>
841	</td>
842	</tr>
843
844	</table>
845
846
847	</div>
848
849
850
851	<div class="sect3"><a name="samba2-CHP-1-SECT-3.4.2"/>
852
853	<h3 class="head3">Group names and types</h3>
854
855	<p>SMB also uses the concept of groups, with which computers can
856	register themselves. Earlier we mentioned that the computers in our
857	example belonged to a
858	<em class="firstterm">workgroup</em><a name="INDEX-73"/>,
859	which is a partition of computers on the same network. For example, a
860	business might very easily have an ACCOUNTING and a SALES workgroup,
861	each with different servers and printers. In the Windows world, a
862	workgroup and an
863	<a name="INDEX-74"/>SMB
864	group are the same thing.</p>
865
866	<p>Continuing our
867	<em class="emphasis">nbtstat</em><a name="INDEX-75"/> example,
868	the <tt class="literal">toltec</tt> Samba server is also a member of the
869	METRAN workgroup (the GROUP attribute hex 00) and will participate in
870	elections for the browse master (GROUP attribute 1E). Here is the
871	remainder of the <em class="emphasis">nbtstat</em> output:</p>
872
873	<blockquote><pre class="code"> NetBIOS Remote Machine Name Table
874	Name Type Status
875	---------------------------------------------
876	METRAN <00> GROUP Registered
877	METRAN <1E> GROUP Registered
878	..__MSBROWSE__.<01> GROUP Registered</pre></blockquote>
879
880	<p>The possible group attributes a computer can have are illustrated in
881	<a href="ch01.html#samba2-CHP-1-TABLE-3">Table 1-3</a>. More
882	<a name="INDEX-76"/><a name="INDEX-77"/>information
883	is available in <em class="emphasis">Windows NT in a Nutshell</em> by Eric
884	<a name="INDEX-78"/>Pearce, also
885	published by O'Reilly.</p>
886
887	<a name="samba2-CHP-1-TABLE-3"/><h4 class="head4">Table 1-3. NetBIOS group resource types</h4><table border="1">
888
889
890
891	<tr>
892	<th>
893	<p>Named resource</p>
894	</th>
895	<th>
896	<p>Hexadecimal byte value</p>
897	</th>
898	</tr>
899
900
901	<tr>
902	<td>
903	<p>Standard Workstation group</p>
904	</td>
905	<td>
906	<p>00</p>
907	</td>
908	</tr>
909	<tr>
910	<td>
911	<p>Logon server</p>
912	</td>
913	<td>
914	<p>1C</p>
915	</td>
916	</tr>
917	<tr>
918	<td>
919	<p>Master Browser name</p>
920	</td>
921	<td>
922	<p>1D</p>
923	</td>
924	</tr>
925	<tr>
926	<td>
927	<p>Normal Group name (used in browser elections)</p>
928	</td>
929	<td>
930	<p>1E</p>
931	</td>
932	</tr>
933	<tr>
934	<td>
935	<p>Internet Group name (administrative)</p>
936	</td>
937	<td>
938	<p>20</p>
939	</td>
940	</tr>
941	<tr>
942	<td>
943	<p><tt class="literal"><01><02>_ _MSBROWSE_ _<02></tt></p>
944	</td>
945	<td>
946	<p>01</p>
947	</td>
948	</tr>
949
950	</table>
951
952	<p>The final entry, <tt class="literal">_ _ MSBROWSE _ _</tt>
953	<a name="INDEX-80"/>, is used to announce a group to other
954	master browsers. The nonprinting characters in the name show up as
955	dots in an <em class="emphasis">nbtstat</em> printout.
956	Don't worry if you don't understand
957	all of the resource or group types. Some of them you will not need
958	with Samba, and others you will pick up as you move through the rest
959	of the chapter. The important thing to remember here is the logistics
960	of the naming mechanism.</p>
961
962
963	</div>
964
965
966
967	<div class="sect3"><a name="samba2-CHP-1-SECT-3.4.3"/>
968
969	<h3 class="head3">Scope ID</h3>
970
971	<p>In the dark ages of SMB networking before NetBIOS groups were
972	introduced, you could use a very primitive method to isolate groups
973	of computers from the rest of the network. Each SMB packet contains a
974	field called the <em class="firstterm">scope
975	ID</em><a name="INDEX-81"/><a name="INDEX-82"/>, with the idea being that
976	systems on the network could be configured to accept only packets
977	with a scope ID matching that of their configuration. This feature
978	was hardly ever used and unfortunately lingers in modern
979	implementations. Some of the utilities included in the Samba
980	distribution allow the scope ID to be set. Setting the scope ID in a
981	network is likely to cause problems, and we are mentioning scope ID
982	only so that you will not be confused by it when you later encounter
983	it in various places.</p>
984
985
986	</div>
987
988
989	</div>
990
991
992	<div class="sect2"><a name="samba2-CHP-1-SECT-3.5"/>
993
994	<h3 class="head2">Datagrams and Sessions</h3>
995
996	<p>At this point, let's digress to discuss the
997	responsibility of NBT: to provide connection services between two
998	NetBIOS computers.
999	<a name="INDEX-83"/>NBT
1000	offers two services: the <em class="firstterm">session
1001	service</em><a name="INDEX-84"/> and the
1002	<em class="firstterm">datagram service</em><a name="INDEX-85"/>.
1003	Understanding how these two services work is not essential to using
1004	Samba, but it does give you an idea of how NBT works and how to
1005	troubleshoot Samba when it doesn't work.</p>
1006
1007	<p>The datagram service has no stable connection between computers.
1008	Packets of data are simply sent or broadcast from one computer to
1009	another, without regard to the order in which they arrive at the
1010	destination, or even if they arrive at all. The use of datagrams
1011	requires less processing overhead than sessions, although the
1012	reliability of the connection can suffer. Datagrams, therefore, are
1013	used for quickly sending nonvital blocks of data to one or more
1014	computers. The datagram service communicates using the simple
1015	primitives shown in <a href="ch01.html#samba2-CHP-1-TABLE-4">Table 1-4</a>.</p>
1016
1017	<a name="samba2-CHP-1-TABLE-4"/><h4 class="head4">Table 1-4. Datagram primitives</h4><table border="1">
1018
1019
1020
1021	<tr>
1022	<th>
1023	<p>Primitive</p>
1024	</th>
1025	<th>
1026	<p>Description</p>
1027	</th>
1028	</tr>
1029
1030
1031	<tr>
1032	<td>
1033	<p>Send Datagram</p>
1034	</td>
1035	<td>
1036	<p>Send datagram packet to computer or groups of computers.</p>
1037	</td>
1038	</tr>
1039	<tr>
1040	<td>
1041	<p>Send Broadcast Datagram</p>
1042	</td>
1043	<td>
1044	<p>Broadcast datagram to any computer waiting with a Receive Broadcast
1045	datagram.</p>
1046	</td>
1047	</tr>
1048	<tr>
1049	<td>
1050	<p>Receive Datagram</p>
1051	</td>
1052	<td>
1053	<p>Receive a datagram from a computer.</p>
1054	</td>
1055	</tr>
1056	<tr>
1057	<td>
1058	<p>Receive Broadcast Datagram</p>
1059	</td>
1060	<td>
1061	<p>Wait for a Broadcast datagram.</p>
1062	</td>
1063	</tr>
1064
1065	</table>
1066
1067	<p>The session service is more complex. Sessions are a communication
1068	method that, in theory, offers the ability to detect problematic or
1069	inoperable connections between two NetBIOS applications. It helps to
1070	think of an NBT session as being similar to a telephone call, an
1071	analogy that obviously influenced the design of the CIFS standard.</p>
1072
1073	<p>Once the connection is made, it remains open throughout the duration
1074	of the conversation, each side knows who the caller and the called
1075	computer are, and each can communicate with the simple primitives
1076	shown in <a href="ch01.html#samba2-CHP-1-TABLE-5">Table 1-5</a>.</p>
1077
1078	<a name="samba2-CHP-1-TABLE-5"/><h4 class="head4">Table 1-5. Session primitives</h4><table border="1">
1079
1080
1081
1082	<tr>
1083	<th>
1084	<p>Primitive</p>
1085	</th>
1086	<th>
1087	<p>Description</p>
1088	</th>
1089	</tr>
1090
1091
1092	<tr>
1093	<td>
1094	<p>Call</p>
1095	</td>
1096	<td>
1097	<p>Initiate a session with a computer listening under a specified name.</p>
1098	</td>
1099	</tr>
1100	<tr>
1101	<td>
1102	<p>Listen</p>
1103	</td>
1104	<td>
1105	<p>Wait for a call from a known caller or any caller.</p>
1106	</td>
1107	</tr>
1108	<tr>
1109	<td>
1110	<p>Hang-up</p>
1111	</td>
1112	<td>
1113	<p>Exit a call.</p>
1114	</td>
1115	</tr>
1116	<tr>
1117	<td>
1118	<p>Send</p>
1119	</td>
1120	<td>
1121	<p>Send data to the other computer.</p>
1122	</td>
1123	</tr>
1124	<tr>
1125	<td>
1126	<p>Receive</p>
1127	</td>
1128	<td>
1129	<p>Receive data from the other computer.</p>
1130	</td>
1131	</tr>
1132	<tr>
1133	<td>
1134	<p>Session Status</p>
1135	</td>
1136	<td>
1137	<p>Get information on requested sessions.</p>
1138	</td>
1139	</tr>
1140
1141	</table>
1142
1143	<p>Sessions are the backbone of resource sharing on an NBT network. They
1144	are typically used for establishing stable connections from client
1145	computers to disk or printer shares on a server. The client
1146	"calls" the server and starts
1147	trading information such as which files it wishes to open, which data
1148	it wishes to exchange, etc. These calls can last a long
1149	time—hours, even days—and all of this occurs within the
1150	context of a single connection. If there is an error, the session
1151	software (TCP) will retransmit until the data is received properly,
1152	unlike the "punt-and-pray" approach
1153	of the datagram service (UDP).</p>
1154
1155	<p>In truth, while sessions are supposed to handle problematic
1156	communications, they sometimes don't. If the
1157	connection is interrupted, session information that is open between
1158	the two computers might become invalid. If that happens, the only way
1159	to regain the session information is for the same two computers to
1160	call each other again and start over.</p>
1161
1162	<p>If you want more information on each service, we recommend you look
1163	at RFC 1001. However, there are two important things to remember
1164	here:</p>
1165
1166	<ul><li>
1167	<p><a name="INDEX-88"/>Sessions always
1168	occur between two NetBIOS computers. If a session service is
1169	interrupted, the client is supposed to store sufficient state
1170	information for it to reestablish the connection. However, in
1171	practice, this often does not happen.</p>
1172	</li><li>
1173	<p><a name="INDEX-89"/>Datagrams can
1174	be broadcast to multiple computers, but they are unreliable. In other
1175	words, there is no way for the source to know that the datagrams it
1176	sent have indeed arrived at their destinations. <a name="INDEX-90"/></p>
1177	</li></ul>
1178
1179	</div>
1180
1181
1182	</div>
1183
1184
1185
1186	<div class="sect1"><a name="samba2-CHP-1-SECT-4"/>
1187
1188	<h2 class="head1">An Introduction to the SMB Protocol</h2>
1189
1190	<p><a name="INDEX-91"/>Now
1191	we're going to cover some low-level technical
1192	details and explore the elementals of the SMB protocol. You probably
1193	don't need to know much about this to implement a
1194	simple Samba network, and therefore you might want to skip or skim
1195	over this section and go on to the next one
1196	("Windows Workgroups and Domains")
1197	on your first reading. However, assuming you are going to be
1198	responsible for long-term maintenance of a Samba network, it will
1199	help if you understand how it actually works. You will more easily be
1200	able to diagnose and correct any odd problems that pop up.</p>
1201
1202	<p>At a high level, the SMB protocol suite is relatively simple. It
1203	includes commands for all the file and print operations that you
1204	might perform on a local disk or printer, such as:</p>
1205
1206	<ul><li>
1207	<p>Opening and closing files</p>
1208	</li><li>
1209	<p>Creating and deleting files and directories</p>
1210	</li><li>
1211	<p>Reading and writing files</p>
1212	</li><li>
1213	<p>Searching for files</p>
1214	</li><li>
1215	<p>Queueing and dequeueing files in a print spool</p>
1216	</li></ul>
1217	<p>Each operation can be encoded into an SMB message and transmitted to
1218	and from a server. The original name
1219	"SMB" comes from the way in which
1220	the commands are formatted: they are versions of the standard DOS
1221	system-call data structures, or <em class="firstterm">Server Message
1222	Blocks</em>, redesigned for transmitting to another computer
1223	across a network.</p>
1224
1225
1226	<div class="sect2"><a name="samba2-CHP-1-SECT-4.1"/>
1227
1228	<h3 class="head2">SMB Format</h3>
1229
1230	<p>Richard <a name="INDEX-92"/>Sharpe of the Samba team defines SMB as
1231	a <em class="firstterm">request-response</em> protocol.<a name="FNPTR-4"/><a href="#FOOTNOTE-4">[4]</a> In effect,
1232	this means that a client sends an SMB request to a server and the
1233	server sends an SMB response back to the client. In only one rare
1234	circumstance does a server send a message that is not in response to
1235	a client.</p>
1236
1237	<p>An <a name="INDEX-94"/>SMB message is not as complex as you
1238	might think. Let's take a closer look at the
1239	internal structure of such a message. It can be broken down into two
1240	parts: the <em class="firstterm">header</em>, which is a fixed size, and
1241	the <em class="firstterm">command string</em>, whose size can vary
1242	dramatically based on the contents of the message.</p>
1243
1244
1245	<div class="sect3"><a name="samba2-CHP-1-SECT-4.1.1"/>
1246
1247	<h3 class="head3">SMB header format</h3>
1248
1249	<p><a href="ch01.html#samba2-CHP-1-TABLE-6">Table 1-6</a> shows the format of an
1250	<a name="INDEX-95"/>SMB header. The COM field identifies
1251	the command being performed. SMB commands are not required to use all
1252	the fields in the SMB header. For example, when a client first
1253	attempts to connect to a server, it does not yet have a tree
1254	identifier (TID) value—one is assigned after it successfully
1255	connects—so a null TID is placed in its header field. Other
1256	fields can be padded with zeros when not used.</p>
1257
1258	<p>The <a name="INDEX-96"/>SMB header fields are listed in <a href="ch01.html#samba2-CHP-1-TABLE-6">Table 1-6</a>.</p>
1259
1260	<a name="samba2-CHP-1-TABLE-6"/><h4 class="head4">Table 1-6. SMB header fields</h4><table border="1">
1261
1262
1263
1264
1265	<tr>
1266	<th>
1267	<p>Field</p>
1268	</th>
1269	<th>
1270	<p>Size (bytes)</p>
1271	</th>
1272	<th>
1273	<p>Description</p>
1274	</th>
1275	</tr>
1276
1277
1278	<tr>
1279	<td>
1280	<p><tt class="literal">0xFF 'SMB</tt>'</p>
1281	</td>
1282	<td>
1283	<p><tt class="literal">1</tt></p>
1284	</td>
1285	<td>
1286	<p>Protocol identifier</p>
1287	</td>
1288	</tr>
1289	<tr>
1290	<td>
1291	<p><tt class="literal">COM</tt></p>
1292	</td>
1293	<td>
1294	<p><tt class="literal">1</tt></p>
1295	</td>
1296	<td>
1297	<p>Command code, from 0x00 to 0xFF</p>
1298	</td>
1299	</tr>
1300	<tr>
1301	<td>
1302	<p><tt class="literal">RCLS</tt></p>
1303	</td>
1304	<td>
1305	<p><tt class="literal">1</tt></p>
1306	</td>
1307	<td>
1308	<p>Error class</p>
1309	</td>
1310	</tr>
1311	<tr>
1312	<td>
1313	<p><tt class="literal">REH</tt></p>
1314	</td>
1315	<td>
1316	<p><tt class="literal">1</tt></p>
1317	</td>
1318	<td>
1319	<p>Reserved</p>
1320	</td>
1321	</tr>
1322	<tr>
1323	<td>
1324	<p><tt class="literal">ERR</tt></p>
1325	</td>
1326	<td>
1327	<p><tt class="literal">2</tt></p>
1328	</td>
1329	<td>
1330	<p>Error code</p>
1331	</td>
1332	</tr>
1333	<tr>
1334	<td>
1335	<p><tt class="literal">REB</tt></p>
1336	</td>
1337	<td>
1338	<p><tt class="literal">1</tt></p>
1339	</td>
1340	<td>
1341	<p>Reserved</p>
1342	</td>
1343	</tr>
1344	<tr>
1345	<td>
1346	<p><tt class="literal">RES</tt></p>
1347	</td>
1348	<td>
1349	<p><tt class="literal">14</tt></p>
1350	</td>
1351	<td>
1352	<p>Reserved</p>
1353	</td>
1354	</tr>
1355	<tr>
1356	<td>
1357	<p><tt class="literal">TID</tt></p>
1358	</td>
1359	<td>
1360	<p><tt class="literal">2</tt></p>
1361	</td>
1362	<td>
1363	<p>TID; a unique ID for a resource in use by the client</p>
1364	</td>
1365	</tr>
1366	<tr>
1367	<td>
1368	<p><tt class="literal">PID</tt></p>
1369	</td>
1370	<td>
1371	<p><tt class="literal">2</tt></p>
1372	</td>
1373	<td>
1374	<p>Caller process ID</p>
1375	</td>
1376	</tr>
1377	<tr>
1378	<td>
1379	<p><tt class="literal">UID</tt></p>
1380	</td>
1381	<td>
1382	<p><tt class="literal">2</tt></p>
1383	</td>
1384	<td>
1385	<p>User identifier</p>
1386	</td>
1387	</tr>
1388	<tr>
1389	<td>
1390	<p><tt class="literal">MID</tt></p>
1391	</td>
1392	<td>
1393	<p><tt class="literal">2</tt></p>
1394	</td>
1395	<td>
1396	<p>Multiplex identifier; used to route requests inside a process</p>
1397	</td>
1398	</tr>
1399
1400	</table>
1401
1402
1403	</div>
1404
1405
1406
1407	<div class="sect3"><a name="samba2-CHP-1-SECT-4.1.2"/>
1408
1409	<h3 class="head3">SMB command format</h3>
1410
1411	<p>Immediately after the header is a variable number of bytes that
1412	constitute an <a name="INDEX-97"/>SMB command or reply. Each command,
1413	such as Open File (COM field identifier: <tt class="literal">SMBopen</tt>)
1414	or Get Print Queue (<tt class="literal">SMBsplretq</tt> ), has its own set
1415	of parameters and data. Like the SMB header fields, not all of the
1416	command fields need to be filled, depending on the specific command.
1417	For example, the Get Server Attributes
1418	(<tt class="literal">SMBdskattr</tt>) command sets the WCT and BCC fields
1419	to zero. The fields of the command segment are shown in <a href="ch01.html#samba2-CHP-1-TABLE-7">Table 1-7</a>.</p>
1420
1421	<a name="samba2-CHP-1-TABLE-7"/><h4 class="head4">Table 1-7. SMB command contents</h4><table border="1">
1422
1423
1424
1425
1426	<tr>
1427	<th>
1428	<p>Field</p>
1429	</th>
1430	<th>
1431	<p>Size (bytes)</p>
1432	</th>
1433	<th>
1434	<p>Description</p>
1435	</th>
1436	</tr>
1437
1438
1439	<tr>
1440	<td>
1441	<p><tt class="literal">WCT</tt></p>
1442	</td>
1443	<td>
1444	<p><tt class="literal">1</tt></p>
1445	</td>
1446	<td>
1447	<p>Word count</p>
1448	</td>
1449	</tr>
1450	<tr>
1451	<td>
1452	<p><tt class="literal">VWV</tt></p>
1453	</td>
1454	<td>
1455	<p>Variable</p>
1456	</td>
1457	<td>
1458	<p>Parameter words (size given by WCT)</p>
1459	</td>
1460	</tr>
1461	<tr>
1462	<td>
1463	<p><tt class="literal">BCC</tt></p>
1464	</td>
1465	<td>
1466	<p><tt class="literal">2</tt></p>
1467	</td>
1468	<td>
1469	<p>Parameter byte count</p>
1470	</td>
1471	</tr>
1472	<tr>
1473	<td>
1474	<p><tt class="literal">DATA</tt></p>
1475	</td>
1476	<td>
1477	<p>Variable</p>
1478	</td>
1479	<td>
1480	<p>Data (size given by BCC)</p>
1481	</td>
1482	</tr>
1483
1484	</table>
1485
1486	<p>Don't worry if you don't understand
1487	each field; they are not necessary for using Samba at an
1488	administrator level. However, they do come in handy when debugging
1489	system messages. We will show you some of the more common SMB
1490	messages that clients and servers send using a modified version of
1491	<em class="filename">tcpdump</em> later in this section. (If you prefer an
1492	<a name="INDEX-98"/><a name="INDEX-99"/>SMB sniffer with a graphical
1493	interface, try Ethereal, which uses the GTK libraries; see
1494	<a href="http://www.ethereal.com">http://www.ethereal.com</a> for more
1495	information on this tool.)</p>
1496
1497	<a name="samba2-CHP-1-NOTE-84"/><blockquote class="note"><h4 class="objtitle">TIP</h4>
1498	<p>For more information on each command in the
1499	<a name="INDEX-100"/>SMB protocol, see the
1500	<em class="citetitle">CIFS Technical
1501	Reference</em><a name="INDEX-101"/> at <a href="http://www.snia.org/tech_activities/CIFS">http://www.snia.org/tech_activities/CIFS</a>.</p>
1502	</blockquote>
1503
1504
1505	</div>
1506
1507
1508
1509	<div class="sect3"><a name="samba2-CHP-1-SECT-4.1.3"/>
1510
1511	<h3 class="head3">SMB variations</h3>
1512
1513	<p>The SMB protocol has been extended with new commands several times
1514	since its inception. Each new version is backward-compatible with the
1515	previous versions, so it is possible for a LAN to have clients and
1516	servers concurrently running different versions of the SMB protocol.</p>
1517
1518	<p><a href="ch01.html#samba2-CHP-1-TABLE-8">Table 1-8</a> outlines the major versions of the
1519	<a name="INDEX-102"/>SMB
1520	protocol. Within each "dialect" of
1521	SMB are many sub-versions that include commands supporting particular
1522	releases of major operating systems. The ID string in column 2 is
1523	used by clients and servers to determine in which level of the
1524	protocol they will speak to each other.</p>
1525
1526	<a name="samba2-CHP-1-TABLE-8"/><h4 class="head4">Table 1-8. SMB protocol dialects</h4><table border="1">
1527
1528
1529
1530
1531	<tr>
1532	<th>
1533	<p>Protocol name</p>
1534	</th>
1535	<th>
1536	<p>ID string</p>
1537	</th>
1538	<th>
1539	<p>Used by</p>
1540	</th>
1541	</tr>
1542
1543
1544	<tr>
1545	<td>
1546	<p>Core</p>
1547	</td>
1548	<td>
1549	<p><tt class="literal">PC NETWORK PROGRAM 1.0</tt></p>
1550	</td>
1551	<td>
1552	</td>
1553	</tr>
1554	<tr>
1555	<td>
1556	<p><a name="INDEX-103"/>Core Plus</p>
1557	</td>
1558	<td>
1559	<p><tt class="literal">MICROSOFT NETWORKS 1.03</tt></p>
1560	</td>
1561	<td>
1562	</td>
1563	</tr>
1564	<tr>
1565	<td>
1566	<p><a name="INDEX-104"/>LAN Manager 1.0</p>
1567	</td>
1568	<td>
1569	<p><tt class="literal">LANMAN1.0</tt></p>
1570	</td>
1571	<td>
1572	</td>
1573	</tr>
1574	<tr>
1575	<td>
1576	<p>LAN Manager 2.0</p>
1577	</td>
1578	<td>
1579	<p><tt class="literal">LM1.2X002</tt></p>
1580	</td>
1581	<td>
1582	</td>
1583	</tr>
1584	<tr>
1585	<td>
1586	<p>LAN Manager 2.1</p>
1587	</td>
1588	<td>
1589	<p><tt class="literal">LANMAN2.1</tt></p>
1590	</td>
1591	<td>
1592	</td>
1593	</tr>
1594	<tr>
1595	<td>
1596	<p><a name="INDEX-105"/>NT LAN
1597	Manager 1.0</p>
1598	</td>
1599	<td>
1600	<p><tt class="literal">NT LM 0.12</tt></p>
1601	</td>
1602	<td>
1603	<p>Windows NT 4.0</p>
1604	</td>
1605	</tr>
1606	<tr>
1607	<td>
1608	<p><a name="INDEX-106"/>Samba's NT LM 0.12</p>
1609	</td>
1610	<td>
1611	<p><tt class="literal">Samba</tt></p>
1612	</td>
1613	<td>
1614	<p>Samba</p>
1615	</td>
1616	</tr>
1617	<tr>
1618	<td>
1619	<p><a name="INDEX-107"/><a name="INDEX-108"/>Common
1620	Internet File System</p>
1621	</td>
1622	<td>
1623	<p><tt class="literal">CIFS 1.0</tt></p>
1624	</td>
1625	<td>
1626	<p>Windows 2000/XP</p>
1627	</td>
1628	</tr>
1629
1630	</table>
1631
1632	<p>Samba implements the NT LM 0.12 specification for NT LAN Manager 1.0.
1633	It is backward-compatible with all the other SMB variants. The CIFS
1634	specification is, in reality, LAN Manager 0.12 with a few specific
1635	additions.</p>
1636
1637
1638	</div>
1639
1640
1641	</div>
1642
1643
1644	<div class="sect2"><a name="samba2-CHP-1-SECT-4.2"/>
1645
1646	<h3 class="head2">SMB Clients and Servers</h3>
1647
1648	<p><a name="INDEX-109"/><a name="INDEX-110"/>As
1649	mentioned earlier, SMB is a client/server protocol. In the purest
1650	sense, this means that a client sends a request to a server, which
1651	acts on the request and returns a reply. However, the client/server
1652	roles can often be reversed, sometimes within the context of a single
1653	SMB session. For example, consider the two Windows 95/98/Me computers
1654	in <a href="ch01.html#samba2-CHP-1-FIG-11">Figure 1-11</a>. The computer named
1655	<tt class="literal">maya</tt> shares a printer to the network, and the
1656	computer named <tt class="literal">toltec</tt> shares a disk directory.
1657	<tt class="literal">maya</tt> is in the client role when accessing
1658	<tt class="literal">toltec</tt>'s network drive and in the
1659	server role when printing a job for <tt class="literal">toltec</tt>.</p>
1660
1661	<div class="figure"><a name="samba2-CHP-1-FIG-11"/><img src="figs/sam2_0111.gif"/></div><h4 class="head4">Figure 1-11. Two computers that both have resources to share</h4>
1662
1663	<p>This brings out an important point in Samba terminology:</p>
1664
1665	<ul><li>
1666	<p>A <em class="firstterm">server</em> is a computer with a resource to
1667	share.</p>
1668	</li><li>
1669	<p>A <em class="firstterm">client</em> is a computer that wishes to use that
1670	resource.</p>
1671	</li><li>
1672	<p>A computer can be a client, a server, or both, or it can be neither
1673	at any given time.</p>
1674	</li></ul>
1675	<p>Microsoft Windows products have both the SMB client and server built
1676	into the operating system, and it is common to find Windows acting as
1677	a server, client, both, or neither at any given time in a production
1678	network. Although Samba has been developed primarily to function as a
1679	server, there are also ways that it and associated software can act
1680	as an SMB client. As with Windows, it is even possible to set up a
1681	Unix system to act as an SMB client and not as a server. See <a href="ch05.html">Chapter 5</a> for more details on this topic.</p>
1682
1683
1684	</div>
1685
1686
1687	<div class="sect2"><a name="samba2-CHP-1-SECT-4.3"/>
1688
1689	<h3 class="head2">A Simple SMB Connection</h3>
1690
1691	<p><a name="INDEX-111"/>The client and server must complete
1692	three steps to establish a connection to a resource:</p>
1693
1694	<ol><li>
1695	<p>Establish a NetBIOS session.</p>
1696	</li><li>
1697	<p>Negotiate the protocol variant.</p>
1698	</li><li>
1699	<p>Set session parameters, and make a tree connection to a resource.</p>
1700	</li></ol>
1701	<p>We will examine each step through the eyes of a useful tool that we
1702	mentioned earlier: the modified
1703	<em class="filename">tcpdump</em><a name="INDEX-112"/> that is
1704	available from the Samba web site.</p>
1705
1706	<a name="samba2-CHP-1-NOTE-85"/><blockquote class="note"><h4 class="objtitle">TIP</h4>
1707	<p>You can download the tcpdump program at <a href="http://www.samba.org">http://www.samba.org</a> in the
1708	<em class="filename">samba/ftp/tcpdump-smb</em> directory; the latest
1709	version as of this writing is 3.4-10. Use this program as you would
1710	use the standard <em class="filename">tcpdump</em> application, but add
1711	the <tt class="literal">-s 1500</tt> switch to ensure that you get the
1712	whole packet and not just the first few bytes.</p>
1713	</blockquote>
1714
1715
1716	</div>
1717
1718
1719	<div class="sect2"><a name="samba2-CHP-1-SECT-4.4"/>
1720
1721	<h3 class="head2">Establishing a NetBIOS Session</h3>
1722
1723	<p><a name="INDEX-113"/>When a user first makes a request
1724	to access a network disk or send a print job to a remote printer,
1725	NetBIOS takes care of making a connection at the session layer. The
1726	result is a bidirectional channel between the client and server. The
1727	client and server need only two messages to establish this
1728	connection. This is shown in the following example session request
1729	and response, as captured by <em class="filename">tcpdump</em> .</p>
1730
1731	<p>First, the client sends a request to open a session, and
1732	<em class="filename">tcpdump </em><a name="INDEX-114"/>reports:</p>
1733
1734	<blockquote><pre class="code">>>> NBT Packet
1735	NBT Session Request
1736	Flags=0x81000044
1737	Destination=TOLTEC NameType=0x20 (Server)
1738	Source=MAYA NameType=0x00 (Workstation)</pre></blockquote>
1739
1740	<p>Then the server responds, granting a session to the client:</p>
1741
1742	<blockquote><pre class="code">>>> NBT Packet
1743	NBT Session Granted
1744	Flags=0x82000000</pre></blockquote>
1745
1746	<p>At this point, there is an open channel between the client and server.</p>
1747
1748
1749	</div>
1750
1751
1752	<div class="sect2"><a name="samba2-CHP-1-SECT-4.5"/>
1753
1754	<h3 class="head2">Negotiating the Protocol Variant</h3>
1755
1756	<p>Next, the client sends a message to the server to negotiate an
1757	<a name="INDEX-115"/>SMB protocol. As mentioned
1758	earlier, the client sets its <a name="INDEX-116"/>tree identifier (TID) field to
1759	zero, because it does not yet know what TID to use. A <em class="emphasis">tree
1760	identifier</em> is a number that represents a connection to a
1761	share on a server.</p>
1762
1763	<p>The command in the message is <tt class="literal">SMBnegprot</tt>, a
1764	request to negotiate a protocol variant that will be used for the
1765	entire session. Note that the client sends to the server a list of
1766	all the variants that it can speak, not vice versa:</p>
1767
1768	<blockquote><pre class="code">>>> NBT Packet
1769	NBT Session Packet
1770	Flags=0x0
1771	Length=154
1772
1773	SMB PACKET: SMBnegprot (REQUEST)
1774	SMB Command = 0x72
1775	Error class = 0x0
1776	Error code = 0
1777	Flags1 = 0x0
1778	Flags2 = 0x0
1779	Tree ID = 0
1780	Proc ID = 5315
1781	UID = 0
1782	MID = 257
1783	Word Count = 0
1784	Dialect=PC NETWORK PROGRAM 1.0
1785	Dialect=MICROSOFT NETWORKS 3.0
1786	Dialect=DOS LM1.2X002
1787	Dialect=DOS LANMAN2.1
1788	Dialect=Windows for Workgroups 3.1a
1789	Dialect=NT LM 0.12</pre></blockquote>
1790
1791	<p>The server responds to the
1792	<tt class="literal">SMBnegprot</tt><a name="INDEX-117"/> request with an index (with counting
1793	starting at 0) into the list of variants that the client offered, or
1794	with the value 0xFF if none of the protocol variants is acceptable:</p>
1795
1796	<blockquote><pre class="code">>>> NBT Packet
1797	NBT Session Packet
1798	Flags=0x0
1799	Length=84
1800
1801	SMB PACKET: SMBnegprot (REPLY)
1802	SMB Command = 0x72
1803	Error class = 0x0
1804	Error code = 0
1805	Flags1 = 0x80
1806	Flags2 = 0x1
1807	Tree ID = 0
1808	Proc ID = 5315
1809	UID = 0
1810	MID = 257
1811	Word Count = 17
1812	NT1 Protocol
1813	DialectIndex=5
1814	[...]</pre></blockquote>
1815
1816	<p>In this example, the server responds with the value 5, which
1817	indicates that the <tt class="literal">NT</tt> <tt class="literal">LM</tt>
1818	<tt class="literal">0.12</tt> dialect will be used for the remainder of the
1819	session.</p>
1820
1821
1822	</div>
1823
1824
1825	<div class="sect2"><a name="samba2-CHP-1-SECT-4.6"/>
1826
1827	<h3 class="head2">Set Session and Login Parameters</h3>
1828
1829	<p><a name="INDEX-118"/><a name="INDEX-119"/>The next step is to transmit session and
1830	login parameters for the session, which you do using the
1831	<a name="INDEX-120"/><tt class="literal">SMBSesssetupX</tt>
1832	command. The parameters include the following:</p>
1833
1834	<ul><li>
1835	<p>The account name and password (if there is one)</p>
1836	</li><li>
1837	<p>The workgroup name</p>
1838	</li><li>
1839	<p>The maximum size of data that can be transferred</p>
1840	</li><li>
1841	<p>The number of pending requests that can be in the queue at a time</p>
1842	</li></ul>
1843	<p>The resulting output from <em class="filename">tcpdump </em>is:</p>
1844
1845	<blockquote><pre class="code">>>> NBT Packet
1846	NBT Session Packet
1847	Flags=0x0
1848	Length=150
1849
1850	SMB PACKET: SMBsesssetupX (REQUEST)
1851	SMB Command = 0x73
1852	Error class = 0x0
1853	Error code = 0
1854	Flags1 = 0x10
1855	Flags2 = 0x0
1856	Tree ID = 0
1857	Proc ID = 5315
1858	UID = 1
1859	MID = 257
1860	Word Count = 13
1861	Com2=0x75
1862	Res1=0x0
1863	Off2=120
1864	MaxBuffer=2920
1865	MaxMpx=50
1866	VcNumber=0
1867	SessionKey=0x1380
1868	CaseInsensitivePasswordLength=24
1869	CaseSensitivePasswordLength=0
1870	Res=0x0
1871	Capabilities=0x1
1872	Pass1&Pass2&Account&Domain&OS&LanMan=
1873	JAY METRAN Windows 4.0 Windows 4.0
1874
1875	SMB PACKET: SMBtconX (REQUEST) (CHAINED)
1876	smbvwv[]=
1877	Com2=0xFF
1878	Off2=0
1879	Flags=0x2
1880	PassLen=1
1881	Passwd&Path&Device=
1882	smb_bcc=23
1883	smb_buf[]=\\TOLTEC\SPIRIT</pre></blockquote>
1884
1885	<p>In this example, the <tt class="literal">SMBsesssetupX</tt> Session Setup
1886	command allows for an additional SMB command to be piggybacked onto
1887	it (indicated by the letter X at the end of the command name). The
1888	hexadecimal code of the second command is given in the
1889	<tt class="literal">Com2</tt> field. In this case the command is
1890	<tt class="literal">0x75</tt>, which is the <tt class="literal">SMBtconX</tt>
1891	<tt class="literal">(</tt>Tree Connect and X) command. The
1892	<tt class="literal">SMBtconX</tt><a name="INDEX-121"/> message looks for the name of the
1893	resource in the <em class="emphasis">smb_buf</em> buffer. In this example,
1894	<em class="emphasis">smb_buf</em> contains the string
1895	<tt class="literal">\\TOLTEC\SPIRIT</tt>, which is the full pathname to a
1896	shared directory on <tt class="literal">toltec</tt>. Using the
1897	"and X" commands like this speeds
1898	up each transaction because the server doesn't have
1899	to wait on the client to make a second request.</p>
1900
1901	<p>Note that the TID is still zero. Finally, the server returns a TID to
1902	the client, indicating that the user has been authorized access and
1903	that the resource is ready to be used:</p>
1904
1905	<blockquote><pre class="code">>>> NBT Packet
1906	NBT Session Packet
1907	Flags=0x0
1908	Length=85
1909
1910	SMB PACKET: SMBsesssetupX (REPLY)
1911	SMB Command = 0x73
1912	Error class = 0x0
1913	Error code = 0
1914	Flags1 = 0x80
1915	Flags2 = 0x1
1916	Tree ID = 1
1917	Proc ID = 5315
1918	UID = 100
1919	MID = 257
1920	Word Count = 3
1921	Com2=0x75
1922	Off2=68
1923	Action=0x1
1924	[000] Unix Samba 2.2.6
1925	[010] METRAN
1926
1927	SMB PACKET: SMBtconX (REPLY) (CHAINED)
1928	smbvwv[]=
1929	Com2=0xFF
1930	Off2=0
1931	smbbuf[]=
1932	ServiceType=A:</pre></blockquote>
1933
1934	<p>The <em class="emphasis">ServiceType</em> field is set to
1935	"A" to indicate that this is a file
1936	service. Available service types are:</p>
1937
1938	<ul><li>
1939	<p>"A" for a disk or file</p>
1940	</li><li>
1941	<p>"LPT1" for a spooled output</p>
1942	</li><li>
1943	<p>"COMM" for a direct-connect printer
1944	or modem</p>
1945	</li><li>
1946	<p>"IPC" for a named pipe</p>
1947	</li></ul>
1948	<p>Now that a TID has been assigned, the client can use it as a handle
1949	to perform any operation that it would use on a local disk drive. It
1950	can open files, read and write to them, delete them, create new
1951	files, search for filenames, and so on. <a name="INDEX-122"/></p>
1952
1953
1954	</div>
1955
1956
1957	</div>
1958
1959
1960
1961	<div class="sect1"><a name="samba2-CHP-1-SECT-5"/>
1962
1963	<h2 class="head1">Windows Workgroups and Domains</h2>
1964
1965	<p>Up to now, we've covered basic SMB technology, which
1966	is all you would need if you had nothing more advanced than MS-DOS
1967	clients on your network. We do assume you want to support Windows
1968	clients, especially the more recent versions, so next
1969	we'll describe the enhancements Microsoft has added
1970	to SMB networking—namely, Windows for Workgroups and Windows
1971	domains.</p>
1972
1973
1974	<div class="sect2"><a name="samba2-CHP-1-SECT-5.1"/>
1975
1976	<h3 class="head2">Windows Workgroups</h3>
1977
1978	<p><a name="INDEX-123"/><a name="INDEX-124"/>Windows
1979	Workgroups are very similar to the SMB groups already described. You
1980	need to know just a few additional things.</p>
1981
1982
1983	<div class="sect3"><a name="samba2-CHP-1-SECT-5.1.1"/>
1984
1985	<h3 class="head3">Browsing</h3>
1986
1987	<p><a name="INDEX-125"/>Browsing
1988	is the process of finding the other computers and shared resources in
1989	the Windows network. Note that there is no connection with a World
1990	Wide Web browser, apart from the general idea of
1991	"discovering what's
1992	there." On the other hand, browsing the Windows
1993	network is like the Web in that what's out there can
1994	change without warning.</p>
1995
1996	<p>Before browsing existed, users had to know the name of the computer
1997	they wanted to connect to on the network and then manually enter a
1998	UNC such as the following into an application or file manager to
1999	access resources:</p>
2000
2001	<blockquote><pre class="code">\\toltec\spirit\</pre></blockquote>
2002
2003	<p>Browsing is much more convenient, making it possible to examine the
2004	contents of a network by using the point-and-click GUI interface of
2005	the Network Neighborhood (or My Network Places<a name="FNPTR-5"/><a href="#FOOTNOTE-5">[5]</a>) on a Windows client.</p>
2006
2007	<p>You will encounter two types of browsing in an SMB network:</p>
2008
2009	<ul><li>
2010	<p><a name="INDEX-129"/>Browsing a list
2011	of computers and shared resources</p>
2012	</li><li>
2013	<p><a name="INDEX-130"/>Browsing the shared resource
2014	of a specific computer</p>
2015	</li></ul>
2016	<p>Let's look at the first one. On each LAN (or subnet)
2017	with a Windows workgroup or domain, one computer has the
2018	responsibility of maintaining a list of the computers that are
2019	currently accessible through the network. This computer is called the
2020	<em class="firstterm">local master
2021	browser</em><a name="INDEX-131"/><a name="INDEX-132"/>, and the list that it maintains is
2022	called the <em class="firstterm">browse
2023	list</em><a name="INDEX-133"/>. Computers on a subnet use the browse
2024	list to cut down on the amount of network traffic generated while
2025	browsing. Instead of each computer dynamically polling to determine a
2026	list of the currently available computers, the computer can simply
2027	query the local master browser to obtain a complete, up-to-date list.</p>
2028
2029	<p>To browse the resources on a computer, a user must connect to the
2030	specific computer; this information cannot be obtained from the
2031	browse list. Browsing the list of resources on a computer can be done
2032	by double-clicking the computer's icon when it is
2033	presented in the Network Neighborhood. As you saw at the opening of
2034	the chapter, the computer will respond with a list of shared
2035	resources that can be accessed after the user is successfully
2036	authenticated.</p>
2037
2038	<p>Each server on a Windows workgroup is required to announce its
2039	presence to the local master browser after it has registered a
2040	NetBIOS name, and (theoretically) announce that it is leaving the
2041	workgroup when it is shut down. It is the local master
2042	browser's responsibility to record what the servers
2043	have announced.</p>
2044	<a name="samba2-CHP-1-NOTE-86"/><blockquote class="note"><h4 class="objtitle">WARNING</h4>
2045	<p>The Windows <a name="INDEX-134"/>Network Neighborhood can behave
2046	oddly: until you select a particular computer to browse, the Network
2047	Neighborhood window might contain data that is not up-to-date. That
2048	means the Network Neighborhood window can be showing computers that
2049	have crashed or can be missing computers that
2050	haven't been noticed yet. Put succinctly, once
2051	you've selected a server and connected to it, you
2052	can be a lot more confident that the shares and printers really exist
2053	on the network.</p>
2054	</blockquote>
2055
2056	<p>Unlike the roles you've seen earlier, almost any
2057	Windows system (including Windows for Workgroups and Windows 95/98/Me
2058	or NT/2000/XP) can act as a local master browser. The local master
2059	browser can have one or more
2060	<em class="firstterm"/><a name="INDEX-135"/><a name="INDEX-136"/>backup
2061	browsers</em> on the local subnet
2062	that will take over in the event that the local master browser fails
2063	or becomes inaccessible. To ensure fluid operation, the local backup
2064	browsers will frequently synchronize their browse list with the local
2065	master browser.</p>
2066
2067	<p>Here is how to calculate the minimum number of backup browsers that
2068	will be allocated on a workgroup:</p>
2069
2070	<ul><li>
2071	<p>If up to 32 Windows NT/2000/XP workstations are on the network, or up
2072	to 16 Windows 95/98/Me computers are on the network, the local master
2073	browser allocates one backup browser in addition to the local master
2074	browser.</p>
2075	</li><li>
2076	<p>If the number of Windows NT/2000/XP workstations falls between 33 and
2077	64, or the number of Windows 95/98/Me workstations falls between 17
2078	and 32, the local master browser allocates two backup browsers.</p>
2079	</li><li>
2080	<p>For each group of 32 NT/2000/XP workstations or 16 Windows 95/98/Me
2081	computers beyond this, the local master browser allocates another
2082	backup browser.</p>
2083	</li></ul>
2084	<p>There is currently no upper limit on the number of backup browsers
2085	that can be allocated by the local master browser.</p>
2086
2087
2088	</div>
2089
2090
2091
2092	<div class="sect3"><a name="samba2-CHP-1-SECT-5.1.2"/>
2093
2094	<h3 class="head3">Browsing elections</h3>
2095
2096	<p><a name="INDEX-137"/>Browsing
2097	is a critical aspect of any Windows workgroup. However, not
2098	everything runs perfectly on any network. For example,
2099	let's say that a computer running Windows on the
2100	desk of a small company's CEO is the local master
2101	browser—that is, until he switches it off while plugging in his
2102	massage chair. At this point the Windows NT Workstation in the spare
2103	parts department might agree to take over the job. However, that
2104	computer is currently running a large, poorly written program that
2105	has brought its processor to its knees. The moral: browsing has to be
2106	very tolerant of servers coming and going. Because nearly every
2107	Windows system can serve as a browser, there has to be a way of
2108	deciding at any time who will take on the job. This decision-making
2109	process is called an <em class="firstterm">election</em>.</p>
2110
2111	<p>An election algorithm is built into nearly all Windows operating
2112	systems such that they can each agree who is going to be a local
2113	master browser and who will be local backup browsers. An election can
2114	be forced at any time. For example, let's assume
2115	that the CEO has finished his massage and reboots his server. As the
2116	server comes online, it will announce its presence, and an election
2117	will take place to see if the PC in the spare parts department should
2118	still be the master browser.</p>
2119
2120	<p>When an election is performed, each computer broadcasts information
2121	about itself via datagrams. This information includes the following:</p>
2122
2123	<ul><li>
2124	<p>The version of the election protocol used</p>
2125	</li><li>
2126	<p>The operating system on the computer</p>
2127	</li><li>
2128	<p>The amount of time the client has been on the network</p>
2129	</li><li>
2130	<p>The hostname of the client</p>
2131	</li></ul>
2132	<p>These values determine which operating system has seniority and will
2133	fulfill the role of the local master browser. (<a href="ch07.html">Chapter 7</a> describes the election process in more
2134	detail.) The architecture developed to achieve this is not elegant
2135	and has built-in security problems. While a browsing domain can be
2136	integrated with domain security, the election algorithm does not take
2137	into consideration which computers become browsers. Thus it is
2138	possible for any computer running a browser service to register
2139	itself as participating in the browsing election and (after winning)
2140	being able to change the browse list. Nevertheless, browsing is a key
2141	feature of Windows networking, and backward-compatibility
2142	requirements will ensure that it is in use for years to come.
2143	<a name="INDEX-138"/></p>
2144
2145
2146	</div>
2147
2148
2149
2150	<div class="sect3"><a name="samba2-CHP-1-SECT-5.1.3"/>
2151
2152	<h3 class="head3">Windows 95/98/Me authentication</h3>
2153
2154	<p>Three types of passwords arise when
2155	<a name="INDEX-139"/><a name="INDEX-140"/>Windows
2156	95/98/Me is operating in a Windows workgroup:</p>
2157
2158	<ul><li>
2159	<p>A Windows password</p>
2160	</li><li>
2161	<p>A Windows Networking password</p>
2162	</li><li>
2163	<p>A password for each shared resource that has been assigned password
2164	protection</p>
2165	</li></ul>
2166	<p>The Windows <a name="INDEX-141"/>password functions in a manner
2167	that might be a source of confusion for Unix system administrators.
2168	It is not there to prevent unauthorized users from using the
2169	computer. (If you don't believe that, try clicking
2170	the Cancel button on the password dialog box and see what happens!)
2171	Instead, the Windows password is used to gain access to a file that
2172	contains the Windows Networking and network resource passwords. There
2173	is one such file per registered user of the system, and they can be
2174	found in the <em class="filename">C:\Windows</em> directory with a name
2175	composed of the user's account name, followed by a
2176	<em class="filename">.pwl</em><a name="INDEX-142"/><a name="INDEX-143"/><a name="INDEX-144"/> extension. For example, if the
2177	user's account name is
2178	"sarah," the file will be
2179	<em class="filename">C:\Windows\sarah.pwl</em>. This file is encrypted
2180	using the Windows password as the encryption key.</p>
2181
2182	<a name="samba2-CHP-1-NOTE-87"/><blockquote class="note"><h4 class="objtitle">TIP</h4>
2183	<p>As a security measure, you might want to check for junk
2184	<em class="filename">.pwl</em> files on Windows 95/98/Me clients, which
2185	might have been created by mistakes users made while attempting to
2186	log on. A <em class="filename">.pwl</em> file is easily cracked and can
2187	contain valid passwords for Samba accounts and network shares.</p>
2188	</blockquote>
2189
2190	<p>The first time the network is accessed, Windows attempts to use the
2191	Windows password as the Windows Networking password. If this is
2192	successful, the user will not be prompted for two separate passwords,
2193	and subsequent logins to the Windows system will automatically result
2194	in logging on to the Windows network as well, making things much
2195	simpler for the user.</p>
2196
2197	<p>Shared network resources in the workgroup can also have passwords
2198	assigned to them to limit their accessibility. The first time a user
2199	attempts to access the resource, she is asked for its password, and a
2200	checkbox in the password dialog box gives the user the option to add
2201	the password to her password list. This is the default; if it is
2202	accepted, Windows will store the password in the
2203	user's <em class="filename">.pwl</em> file, and all
2204	further authentication to the resource will be handled automatically
2205	by Windows.</p>
2206
2207	<p>Samba's approach to workgroup authentication is a
2208	little different, which is a result of blending the Windows workgroup
2209	model with that of the Unix host upon which Samba runs. This will be
2210	discussed further in <a href="ch09.html">Chapter 9</a>. <a name="INDEX-145"/></p>
2211
2212
2213	</div>
2214
2215
2216	</div>
2217
2218
2219	<div class="sect2"><a name="samba2-CHP-1-SECT-5.2"/>
2220
2221	<h3 class="head2">Windows NT Domains</h3>
2222
2223	<p><a name="INDEX-146"/>The
2224	peer-to-peer networking model of
2225	<a name="INDEX-147"/>workgroups functions fairly well as long as
2226	the number of computers on the network is small and there is a
2227	close-knit community of users. However, in larger networks the
2228	simplicity of workgroups becomes a limiting factor. Workgroups offer
2229	only the most basic level of security, and because each resource can
2230	have its own password, it is inconvenient (to say the least) for
2231	users to remember the password for each resource in a large network.
2232	Even if that were not a problem, many people find it frustrating to
2233	have to interrupt their creative workflow to enter a shared password
2234	into a dialog box every time another network resource is accessed.</p>
2235
2236	<p>To support the needs of larger networks, such as those found in
2237	departmental computing environments, Microsoft introduced domains
2238	with Windows NT 3.51. A <em class="firstterm">Windows NT domain</em> is
2239	essentially a workgroup of SMB computers that has one addition: a
2240	server acting as a <em class="firstterm">domain
2241	controller</em><a name="INDEX-148"/> (see <a href="ch01.html#samba2-CHP-1-FIG-12">Figure 1-12</a>).</p>
2242
2243	<div class="figure"><a name="samba2-CHP-1-FIG-12"/><img src="figs/sam2_0112.gif"/></div><h4 class="head4">Figure 1-12. A simple Windows domain</h4>
2244
2245
2246	<div class="sect3"><a name="samba2-CHP-1-SECT-5.2.1"/>
2247
2248	<h3 class="head3">Domain controllers</h3>
2249
2250	<p>A domain controller in a Windows NT domain functions much like a
2251	<a name="INDEX-149"/><a name="INDEX-150"/>Network
2252	Information Service (NIS) server in a Unix network, maintaining a
2253	domain-wide database of user and group information, as well as
2254	performing related services. The responsibilities of a domain
2255	controller are mainly centered around security, including
2256	<em class="firstterm">authentication</em><a name="INDEX-151"/>,
2257	the process of granting or denying a user access to the resources of
2258	the domain. This is typically done through the use of a username and
2259	password. The service that maintains the database on the domain
2260	controllers is called the <a name="INDEX-152"/><a name="INDEX-153"/>Security Account Manager (SAM).</p>
2261
2262	<p>The <a name="INDEX-154"/>Windows NT security model revolves
2263	around <em class="firstterm">security
2264	identifiers</em><a name="INDEX-155"/><a name="INDEX-156"/> (SIDs) and <em class="firstterm">access
2265	control lists</em><a name="INDEX-157"/><a name="INDEX-158"/>
2266	(ACLs). Security identifiers are used to represent objects in the
2267	domain, which include (but are not limited to) users, groups,
2268	computers, and processes. SIDs are commonly written in ASCII form as
2269	hyphen-separated fields, like this:</p>
2270
2271	<blockquote><pre class="code">S-1-5-21-1638239387-7675610646-9254035128-545</pre></blockquote>
2272
2273	<p>The part of the SID starting with the
2274	"S" and leading up to the rightmost
2275	hyphen identifies a domain. The number after the rightmost hyphen is
2276	called a <a name="INDEX-159"/>relative identifier (RID) and is a unique
2277	number within the domain that identifies the user, group, computer,
2278	or other object. The RID is the analog of a <a name="INDEX-160"/>user ID (UID) or
2279	<a name="INDEX-161"/>group ID
2280	(GID) on a Unix system or within an NIS domain.</p>
2281
2282	<p>ACLs supply the same function as
2283	"rwx"
2284	<a name="INDEX-162"/><a name="INDEX-163"/><a name="INDEX-164"/><a name="INDEX-165"/><a name="INDEX-166"/>file permissions that are common in Unix
2285	systems. However, ACLs are more versatile. Unix file permissions only
2286	set permissions for the owner and group to which the file belongs,
2287	and "other," meaning everyone else.
2288	Windows NT/2000/XP ACLs allow permissions to be set individually for
2289	any number of arbitrary users and/or groups. ACLs are made up of one
2290	or more <em class="firstterm">access control
2291	entries</em><a name="INDEX-167"/> (ACEs), each of which contains an SID
2292	and the access rights associated with it.</p>
2293
2294	<p>ACL support has been added as a standard feature for some Unix
2295	variants and is available as an add-on for others. Samba supports
2296	mappings between Windows and Unix ACLs, and this will be covered in
2297	<a href="ch08.html">Chapter 8</a>.</p>
2298
2299
2300	</div>
2301
2302
2303
2304	<div class="sect3"><a name="samba2-CHP-1-SECT-5.2.2"/>
2305
2306	<h3 class="head3">Primary and backup domain controllers</h3>
2307
2308	<p>You've already read about master and backup
2309	browsers. Domain controllers are similar in that a domain has a
2310	<em class="firstterm">primary domain
2311	controller</em><a name="INDEX-168"/><a name="INDEX-169"/><a name="INDEX-170"/> (PDC) and can have
2312	one or more <em class="firstterm">backup domain
2313	controllers</em><a name="INDEX-171"/> (BDCs) as well. If the PDC fails or
2314	becomes inaccessible, its duties are automatically taken over by one
2315	of the BDCs. BDCs frequently synchronize their SAM data with the PDC
2316	so if the need arises, any one of them can immediately begin
2317	performing domain-controller services without impacting the clients.
2318	However, note that BDCs have read-only copies of the SAM database;
2319	they can update their data only by synchronizing with a PDC. A server
2320	in a Windows domain can use the SAM of any PDC or BDC to authenticate
2321	a user who attempts to access its resources and log on to the domain.</p>
2322
2323	<p>All recent versions of Windows can log on to a domain as clients to
2324	access the resources of the domain servers. The systems that are
2325	considered members of the domain are a more exclusive class, composed
2326	of the PDC and BDCs, as well as domain member servers, which are
2327	systems that have joined a domain as members, and are known to the
2328	domain controllers by having a computer account in the SAM database.</p>
2329
2330
2331	</div>
2332
2333
2334
2335	<div class="sect3"><a name="samba2-CHP-1-SECT-5.2.3"/>
2336
2337	<h3 class="head3">Authentication</h3>
2338
2339	<p><a name="INDEX-172"/>When
2340	a user logs on to a Windows domain by typing in a username and
2341	password, a secure challenge and response protocol is invoked between
2342	the client computer and a domain controller to verify that the
2343	username and password are valid. Then the domain controller sends a
2344	SID back to the client, which uses it to create a
2345	<a name="INDEX-173"/>Security Access Token (SAT) that is valid
2346	only for that system, to be used for further authentication. This
2347	access token has information about the user coded into it, including
2348	the username, the group, and the rights the user has within the
2349	domain. At this point, the user is logged on to the domain.</p>
2350
2351	<p>Subsequently, when the client attempts to access a shared resource
2352	within the domain, the client system enters into a secure challenge
2353	and response exchange with the server of the resource. The server
2354	then enters into another secure challenge and response conversation
2355	with a domain controller to check that the client is valid. (What
2356	actually happens is that the server uses information it gets from the
2357	client to pretend to be the client and authenticate itself with the
2358	domain controller. If the domain controller validates the
2359	credentials, it sends an SID back to the server, which uses the SID
2360	to create its own SAT for the client to enable access to its local
2361	resources on the client's behalf.) At this point,
2362	the client is authenticated for resources on the server and is
2363	allowed to access them. The server then uses the SID in the access
2364	token to determine what permissions the client has to use and modify
2365	the requested resource by comparing them to entries in the ACL of the
2366	resource.</p>
2367
2368	<p>Although this method of authentication might seem overly complicated,
2369	it allows clients to authenticate without having plain-text passwords
2370	travel through the network, and it is much more difficult to crack
2371	than the relatively weak workgroup security we described earlier.</p>
2372
2373
2374	</div>
2375
2376
2377
2378	<div class="sect3"><a name="samba2-CHP-1-SECT-5.2.4"/>
2379
2380	<h3 class="head3">Name service with WINS and DNS</h3>
2381
2382	<p>The <a name="INDEX-174"/><a name="INDEX-175"/>Windows
2383	Internet Name Service (WINS) is Microsoft's
2384	implementation of a NetBIOS name server (NBNS). As such, WINS
2385	inherits much of NetBIOS's characteristics. First,
2386	WINS is flat; you can have only simple machine names such as
2387	<tt class="literal">inca</tt>, <tt class="literal">mixtec</tt>, or
2388	<tt class="literal">navaho</tt>, and workgroups such as PERU, MEXICO, or
2389	USA. In addition, WINS is dynamic: when a client first comes online,
2390	it is required to report its hostname, its address, and its workgroup
2391	to the local WINS server. This WINS server will retain the
2392	information so long as the client periodically refreshes its WINS
2393	registration, which indicates that it's still
2394	connected to the network. Note that WINS servers are not workgroup-
2395	or domain-specific; they can contain information for multiple domains
2396	and/or workgroups, which might exist on more than one subnet.</p>
2397
2398	<p>Multiple <a name="INDEX-176"/>WINS
2399	servers can be set to synchronize with each other. This allows
2400	entries for computers that come online and go offline in the network
2401	to propagate from one WINS server to another. While in theory this
2402	seems efficient, it can quickly become cumbersome if several WINS
2403	servers are covering a network. Because WINS services can cross
2404	multiple subnets (you'll either hardcode the address
2405	of a WINS server in each of your clients or obtain it via DHCP), it
2406	is often more efficient to have each Windows client, regardless of
2407	the number of Windows domains, point themselves to the same WINS
2408	server. That way, only one authoritative WINS server will have the
2409	correct information, instead of several WINS servers continually
2410	struggling to synchronize themselves with the most recent changes.</p>
2411
2412	<p>The currently active WINS server is known as the <em class="firstterm">primary
2413	WINS server</em><a name="INDEX-177"/><a name="INDEX-178"/>. You can also install a secondary WINS
2414	server, which will take over if the primary WINS server fails or
2415	becomes inaccessible. Both the primary and any other WINS servers
2416	will synchronize their address databases on a periodic basis.</p>
2417
2418	<p>In the Windows family of operating systems, only a server edition of
2419	Windows NT/2000 can act as a WINS server. Samba 2.2 can function as a
2420	primary WINS server, but cannot <a name="INDEX-179"/><a name="INDEX-180"/>synchronize
2421	its database with other WINS servers. It therefore cannot act as a
2422	secondary WINS server or as a primary WINS server for a Windows
2423	secondary WINS server.</p>
2424
2425	<p>WINS handles name service by default, although Microsoft added DNS
2426	starting with Windows NT 4 Server. It is compatible with DNS that is
2427	standard on virtually every Unix system, and a Unix server (such as
2428	the Samba host) can also be used for DNS.</p>
2429
2430
2431	</div>
2432
2433
2434
2435	<div class="sect3"><a name="samba2-CHP-1-SECT-5.2.5"/>
2436
2437	<h3 class="head3">Trust relationships</h3>
2438
2439	<p>One additional aspect of Windows NT domains not yet supported in
2440	Samba 2.2 is that it is possible to set up a <em class="emphasis">trust
2441	relationship</em><a name="INDEX-181"/><a name="INDEX-182"/><a name="INDEX-183"/> between domains, allowing clients
2442	within one domain to access the resources within another without the
2443	user having to go through additional authentication. The protocol
2444	that is followed is called <em class="emphasis">pass-through authentication</em>,
2445	<a name="INDEX-184"/><a name="INDEX-185"/>in which the
2446	user's credentials are passed from the client system
2447	in the first domain to the server in the second domain, which
2448	consults a domain controller in the first (trusted) domain to check
2449	that the user is valid before granting access to the resource.</p>
2450
2451	<p>Note that in many aspects, the behaviors of a Windows workgroup and a
2452	Windows NT domain overlap. For example, the master and backup
2453	browsers in a domain are always the PDC and BDC, respectively.
2454	Let's update our Windows domain diagram to include
2455	both a local master and local backup browser. The result is shown in
2456	<a href="ch01.html#samba2-CHP-1-FIG-13">Figure 1-13</a>.</p>
2457
2458	<div class="figure"><a name="samba2-CHP-1-FIG-13"/><a name="INDEX-186"/><img src="figs/sam2_0113.gif"/></div><h4 class="head4">Figure 1-13. A Windows domain with a local master and local backup browser</h4>
2459
2460	<p>The similarity between workgroups and NT domains is not accidental
2461	because the concept of Windows domains did not evolve until Windows
2462	NT 3.5 was introduced, and Windows domains were forced to remain
2463	backward-compatible with the workgroups present in Windows for
2464	Workgroups.</p>
2465
2466	<p>Samba can function as a primary domain controller for Windows
2467	95/98/Me and Windows NT/2000/XP clients with the limitation that it
2468	can act as a PDC only, and not as a BDC.</p>
2469
2470	<p>Samba can also function as a <em class="firstterm">domain member
2471	server</em><a name="INDEX-187"/><a name="INDEX-188"/>, meaning that it has a computer account
2472	in the PDC's account database and is therefore
2473	recognized as being part of the domain. A domain member server does
2474	not authenticate users logging on to the domain, but still handles
2475	security functions (such as file permissions) for domain users
2476	accessing its resources.</p>
2477
2478
2479	</div>
2480
2481
2482	</div>
2483
2484
2485	<div class="sect2"><a name="samba2-CHP-1-SECT-5.3"/>
2486
2487	<h3 class="head2">Active Directory Domains</h3>
2488
2489	<p>Starting with Windows 2000, Microsoft has introduced
2490	<a name="INDEX-189"/><a name="INDEX-190"/>Active
2491	Directory, the next step beyond Windows NT domains. We
2492	won't go into much detail concerning Active
2493	Directory because it is a huge topic. <a name="INDEX-191"/>Samba 2.2 doesn't
2494	support Active Directory at all, and support in Samba 3.0 is limited
2495	to acting as a client. For now, be aware that with Active Directory,
2496	the authentication model is centered around
2497	<a name="INDEX-192"/>Lightweight Directory
2498	Access Protocol (LDAP), and name service is provided by DNS instead
2499	of WINS. Domains in Active Directory can be organized in a
2500	hierarchical tree structure, in which each domain controller operates
2501	as a peer, with no distinction between primary and backup controllers
2502	as in Windows NT domains.</p>
2503
2504	<p>Windows 2000/XP systems can be set up as simple workgroup or Windows
2505	NT domain clients (which will function with Samba). The server
2506	editions of Windows 2000 can be set up to run Active Directory and
2507	support Windows NT domains for backward compatibility
2508	(<em class="firstterm">mixed mode</em>). In this case, Samba 2.2 works
2509	with Windows 2000 servers in the same way it works with Windows NT
2510	4.0 servers. When set up to operate in <em class="firstterm">native mode,
2511	</em><a name="INDEX-193"/>Windows 2000 servers support only
2512	Active Directory. Even so, <a name="INDEX-194"/>Samba 2.2 can operate as a server
2513	in a domain hosted by a native-mode Windows 2000 server, using the
2514	<a name="INDEX-195"/>Windows 2000 server's
2515	<em class="firstterm">PDC emulation mode</em>. However, it is not
2516	possible for Samba 2.2 or 3.0 to operate as a domain controller in a
2517	Windows 2000 Active Directory domain.</p>
2518
2519	<p>If you want to know more about Active Directory, we encourage you to
2520	obtain a copy of the O'Reilly book,
2521	<em class="emphasis">Windows 2000 Active Directory</em>. <a name="INDEX-196"/></p>
2522
2523
2524	</div>
2525
2526
2527	<div class="sect2"><a name="samba2-CHP-1-SECT-5.4"/>
2528
2529	<h3 class="head2">Can a Windows Workgroup Span Multiple Subnets?</h3>
2530
2531	<p><a name="INDEX-197"/><a name="INDEX-198"/>Yes, but most people who have
2532	done it have had their share of headaches. Spanning multiple subnets
2533	was not part of the initial design of Windows NT 3.5 or Windows for
2534	Workgroups. As a result, a Windows domain that spans two or more
2535	subnets is, in reality, the
2536	"gluing" together of two or more
2537	workgroups that share an identical name. The good news is that you
2538	can still use a PDC to control authentication across each subnet. The
2539	bad news is that things are not as simple with browsing.</p>
2540
2541	<p>As mentioned previously, each subnet must have its own local master
2542	browser. When a Windows domain spans multiple subnets, a system
2543	administrator will have to assign one of the computers as the
2544	<em class="firstterm">domain master
2545	browser</em><a name="INDEX-199"/><a name="INDEX-200"/>. The domain master browser will keep a
2546	browse list for the entire Windows domain. This browse list is
2547	created by periodically synchronizing the browse lists of each local
2548	master browser with the browse list of the domain master browser.
2549	After the synchronization, the local master browser and the domain
2550	master browser should contain identical entries. See <a href="ch01.html#samba2-CHP-1-FIG-14">Figure 1-14</a> for an illustration.</p>
2551
2552	<div class="figure"><a name="samba2-CHP-1-FIG-14"/><img src="figs/sam2_0114.gif"/></div><h4 class="head4">Figure 1-14. A workgroup that spans more than one subnet</h4>
2553
2554	<p>Sound good? <a name="INDEX-201"/>Well, it's not quite
2555	nirvana for the following reasons:</p>
2556
2557	<ul><li>
2558	<p>If it exists, a PDC always plays the role of the domain master
2559	browser. By Microsoft design, the two always share the NetBIOS
2560	resource type <tt class="literal"><1B></tt> and (unfortunately)
2561	cannot be separated.</p>
2562	</li><li>
2563	<p>Windows 95/98/Me computers cannot become <em class="emphasis">or</em>
2564	<em class="emphasis">even contact</em> a domain master browser. This means
2565	that it is necessary to have at least one Windows NT/2000/XP system
2566	(or Samba server) on each subnet of a multisubnet workgroup.</p>
2567	</li></ul>
2568	<p>Each subnet's local master browser continues to
2569	maintain the browse list for its subnet, for which it becomes
2570	authoritative. So if a computer wants to see a list of servers within
2571	its own subnet, the local master browser of that subnet will be
2572	queried. If a computer wants to see a list of servers outside the
2573	subnet, it can still go only as far as the local master browser. This
2574	works because at appointed intervals, the authoritative browse list
2575	of a subnet's local master browser is synchronized
2576	with the domain master browser, which is synchronized with the local
2577	master browser of the other subnets in the domain. This is called
2578	<em class="firstterm">browse list propagation</em>.</p>
2579
2580	<p>Samba can act as a domain master browser in a Windows NT domain, or
2581	it can act as a local master browser for a subnet, synchronizing its
2582	browse list with the domain master browser.</p>
2583
2584
2585	</div>
2586
2587
2588	</div>
2589
2590
2591
2592	<div class="sect1"><a name="samba2-CHP-1-SECT-6"/>
2593
2594	<h2 class="head1">What's New in Samba 2.2?</h2>
2595
2596	<p><a name="INDEX-202"/><a name="INDEX-203"/>In
2597	Version 2.2, Samba has more advanced support for Windows networking,
2598	including the ability to perform the more important tasks necessary
2599	for acting in a Windows NT domain. In addition, Samba 2.2 has some
2600	support for technologies that Microsoft introduced in Windows 2000,
2601	although the Samba team has saved Active Directory support for
2602	Version 3.0.</p>
2603
2604
2605	<div class="sect2"><a name="samba2-CHP-1-SECT-6.1"/>
2606
2607	<h3 class="head2">PDC Support for Windows 2000/XP Clients</h3>
2608
2609	<p>Samba previously could act as a PDC to authenticate Windows 95/98/Me
2610	and Windows NT 4 systems. This functionality has been extended in
2611	Release 2.2 to include Windows 2000 and Windows XP. Thus, it is
2612	possible to have a Samba server supporting domain logons for a
2613	network of Windows clients, including the most recent releases from
2614	Microsoft. This can result in a very stable, high-performance, and
2615	more secure network, and gives you the added benefit of not having to
2616	purchase per-seat Windows CALs from Microsoft.</p>
2617
2618
2619	</div>
2620
2621
2622	<div class="sect2"><a name="samba2-CHP-1-SECT-6.2"/>
2623
2624	<h3 class="head2">Microsoft Dfs Support</h3>
2625
2626	<p><a name="INDEX-204"/>Microsoft Dfs allows shared resources that
2627	are dispersed among a number of servers in the network to be gathered
2628	together and appear to users as if they all exist in a single
2629	directory tree on one server. This method of organization makes life
2630	much simpler for users. Instead of having to browse around the
2631	network on a treasure hunt to locate the resource they want to use,
2632	they can go directly to the Dfs server and grab what they want. Samba
2633	2.2 offers support for serving Dfs, so a Windows server is no longer
2634	needed for this purpose.</p>
2635
2636
2637	</div>
2638
2639
2640	<div class="sect2"><a name="samba2-CHP-1-SECT-6.3"/>
2641
2642	<h3 class="head2">Windows NT/2000/XP Printing Support</h3>
2643
2644	<p>Windows NT/2000/XP has a different Remote Procedure Call (RPC)-based
2645	printer interface than Windows 95/98/Me does. In Samba 2.2, the
2646	Windows NT/2000/XP interface is supported. Along with this, the Samba
2647	team has been adding support for automatically downloading the
2648	printer driver from the Samba server while adding a new printer to a
2649	Windows client.</p>
2650
2651
2652	</div>
2653
2654
2655	<div class="sect2"><a name="samba2-CHP-1-SECT-6.4"/>
2656
2657	<h3 class="head2">ACLs</h3>
2658
2659	<p>Samba now supports
2660	<a name="INDEX-205"/>ACLs on its Unix host for Unix variants
2661	that support them. The list includes Solaris 2.6, 7, and 8, Irix,
2662	AIX, Linux (with either the ACL patch for the
2663	<a name="INDEX-206"/>ext2/ext3 filesystem from <a href="http://acl.bestbits.at">http://acl.bestbits.at</a> or when using the
2664	<a name="INDEX-207"/>XFS
2665	filesystem), and FreeBSD (Version 5.0 and later). When using ACL
2666	support, Samba translates between Unix ACLs and Windows NT/2000/XP
2667	ACLs, making the Samba host look and act more like a Windows
2668	NT/2000/XP server from the point of view of Windows clients.</p>
2669
2670
2671	</div>
2672
2673
2674	<div class="sect2"><a name="samba2-CHP-1-SECT-6.5"/>
2675
2676	<h3 class="head2">Support for Windows Client Administration Tools</h3>
2677
2678	<p>Windows comes with tools that can be used from a client to manage
2679	shared resources remotely on a Windows server. Samba 2.2 allows these
2680	tools to operate on shares on the Samba server as well.</p>
2681
2682
2683	</div>
2684
2685
2686	<div class="sect2"><a name="samba2-CHP-1-SECT-6.6"/>
2687
2688	<h3 class="head2">Integration with Winbind</h3>
2689
2690	<p><a name="INDEX-208"/>Winbind is a
2691	facility that allows users whose account information is stored in a
2692	Windows domain database to authenticate on a Unix system. The result
2693	is a unified logon environment, in which a user account can be kept
2694	on either the Unix system or a Windows NT/2000 domain controller.
2695	This greatly facilitates account management because administrators no
2696	longer need to keep the two systems synchronized, and it is possible
2697	for users whose accounts are held in a Windows domain to authenticate
2698	when accessing Samba shares.</p>
2699
2700
2701	</div>
2702
2703
2704	<div class="sect2"><a name="samba2-CHP-1-SECT-6.7"/>
2705
2706	<h3 class="head2">Unix CIFS Extensions</h3>
2707
2708	<p>The <a name="INDEX-209"/><a name="INDEX-210"/>Unix CIFS extensions were developed
2709	at Hewlett-Packard and introduced in Samba 2.2.4. They allow Samba
2710	servers to support Unix filesystem attributes, such as links and
2711	permissions, when sharing files with other Unix systems. This allows
2712	Samba to be used as an alternative to network file sharing (NFS) for
2713	Unix-to-Unix file sharing. An advantage of using Samba is that it
2714	authenticates individual users, whereas NFS authenticates only
2715	clients (based on their IP addresses, which is a poor security
2716	model). This gives Samba an edge in the area of security, along with
2717	its much greater configurability. See <a href="ch05.html">Chapter 5</a>
2718	for information on how to operate Unix systems as Samba clients.</p>
2719
2720
2721	</div>
2722
2723
2724	<div class="sect2"><a name="samba2-CHP-1-SECT-6.8"/>
2725
2726	<h3 class="head2">And More...</h3>
2727
2728	<p>As usual, the code has numerous improvements that do not show up at
2729	the administrative level in an immediate or obvious way. Samba now
2730	functions better on systems that employ <a name="INDEX-211"/>PAM
2731	(Pluggable Authentication Modules), and there is new support for
2732	profiling. Samba's support for oplocks has been
2733	strengthened, offering better integration with NFS server-terminated
2734	leases (currently on Irix and Linux only) and in the local filesystem
2735	with SMB locks mapped to POSIX locks (which is dependent on each Unix
2736	variant's implementation of POSIX locks). And of
2737	course there have been the usual bug fixes.</p>
2738
2739
2740	</div>
2741
2742
2743	</div>
2744
2745
2746
2747	<div class="sect1"><a name="samba2-CHP-1-SECT-7"/>
2748
2749	<h2 class="head1">What's New in Samba 3.0?</h2>
2750
2751	<p>The main distinguishing feature of <a name="INDEX-212"/><a name="INDEX-213"/>Samba 3.0
2752	is that it includes support for <a name="INDEX-214"/>Kerberos 5 authentication and
2753	<a name="INDEX-215"/>LDAP, which are
2754	required to act as clients in an Active Directory domain. Another
2755	feature that appeared in Samba 3.0 is support for Unicode, which
2756	greatly simplifies supporting international languages.</p>
2757
2758	<p>In later Version 3 releases, the Samba team plans to develop support
2759	for
2760	<a name="INDEX-216"/>WINS
2761	replication, allowing Samba to act as a secondary WINS server or as a
2762	primary WINS server with Windows or Samba secondary WINS servers.
2763	Also planned are support for acting as a Windows NT BDC and support
2764	for Windows NT domain trust relationships.</p>
2765
2766
2767	</div>
2768
2769
2770
2771	<div class="sect1"><a name="samba2-CHP-1-SECT-8"/>
2772
2773	<h2 class="head1">What Can Samba Do?</h2>
2774
2775	<p>Now let's wrap up by showing where Samba can help
2776	out and where it is limited. <a href="ch01.html#samba2-CHP-1-TABLE-9">Table 1-9</a> summarizes
2777	which roles Samba can and cannot play in a Windows NT or Active
2778	Directory domain or a Windows workgroup. Many of the Windows domain
2779	protocols are proprietary and have not been documented by Microsoft
2780	and therefore must be reverse-engineered by the Samba team before
2781	Samba can support them. As of Version 3.0, Samba cannot act as a
2782	backup in most roles and does not yet fully support Active Directory.</p>
2783
2784	<a name="samba2-CHP-1-TABLE-9"/><h4 class="head4">Table 1-9. Samba roles (as of Version 3.0)</h4><table border="1">
2785
2786
2787
2788	<tr>
2789	<th>
2790	<p>Role</p>
2791	</th>
2792	<th>
2793	<p>Can perform?</p>
2794	</th>
2795	</tr>
2796
2797
2798	<tr>
2799	<td>
2800	<p><a name="INDEX-217"/>File server</p>
2801	</td>
2802	<td>
2803	<p>Yes</p>
2804	</td>
2805	</tr>
2806	<tr>
2807	<td>
2808	<p>Printer server</p>
2809	</td>
2810	<td>
2811	<p>Yes</p>
2812	</td>
2813	</tr>
2814	<tr>
2815	<td>
2816	<p>Microsoft Dfs server</p>
2817	</td>
2818	<td>
2819	<p>Yes</p>
2820	</td>
2821	</tr>
2822	<tr>
2823	<td>
2824	<p>Primary domain controller</p>
2825	</td>
2826	<td>
2827	<p>Yes</p>
2828	</td>
2829	</tr>
2830	<tr>
2831	<td>
2832	<p>Backup domain controller</p>
2833	</td>
2834	<td>
2835	<p>No</p>
2836	</td>
2837	</tr>
2838	<tr>
2839	<td>
2840	<p>Active Directory domain controller</p>
2841	</td>
2842	<td>
2843	<p>No</p>
2844	</td>
2845	</tr>
2846	<tr>
2847	<td>
2848	<p>Windows 95/98/Me authentication</p>
2849	</td>
2850	<td>
2851	<p>Yes</p>
2852	</td>
2853	</tr>
2854	<tr>
2855	<td>
2856	<p>Windows NT/2000/XP authentication</p>
2857	</td>
2858	<td>
2859	<p>Yes</p>
2860	</td>
2861	</tr>
2862	<tr>
2863	<td>
2864	<p>Local master browser</p>
2865	</td>
2866	<td>
2867	<p>Yes</p>
2868	</td>
2869	</tr>
2870	<tr>
2871	<td>
2872	<p>Local backup browser</p>
2873	</td>
2874	<td>
2875	<p>Yes</p>
2876	</td>
2877	</tr>
2878	<tr>
2879	<td>
2880	<p>Domain master browser</p>
2881	</td>
2882	<td>
2883	<p>Yes</p>
2884	</td>
2885	</tr>
2886	<tr>
2887	<td>
2888	<p>Primary WINS server</p>
2889	</td>
2890	<td>
2891	<p>Yes</p>
2892	</td>
2893	</tr>
2894	<tr>
2895	<td>
2896	<p>Secondary WINS server</p>
2897	</td>
2898	<td>
2899	<p>No</p>
2900	</td>
2901	</tr>
2902
2903	</table>
2904
2905
2906	</div>
2907
2908
2909
2910	<div class="sect1"><a name="samba2-CHP-1-SECT-9"/>
2911
2912	<h2 class="head1">An Overview of the Samba Distribution</h2>
2913
2914	<p><a name="INDEX-218"/>As mentioned earlier, Samba actually
2915	contains several programs that serve different but related purposes.
2916	These programs are documented more fully in <a href="appc.html">Appendix C</a>. For now, we will introduce each of them
2917	briefly and describe how they work together.</p>
2918
2919	<p>The majority of the programs that come with Samba center on its two
2920	daemons. Let's take a refined look at the
2921	responsibilities of each daemon:</p>
2922
2923	<dl>
2924	<dt><b><em class="emphasis">nmbd</em></b></dt>
2925	<dd>
2926	<p>The <em class="emphasis">nmbd</em><a name="INDEX-219"/> daemon is a simple name server that
2927	supplies WINS functionality. This daemon listens for name-server
2928	requests and provides the appropriate IP addresses when called upon.
2929	It also provides browse lists for the Network Neighborhood and
2930	participates in browsing elections.</p>
2931	</dd>
2932
2933
2934
2935	<dt><b><em class="emphasis">smbd</em></b></dt>
2936	<dd>
2937	<p>The <em class="emphasis">smbd</em><a name="INDEX-220"/> daemon manages the shared resources
2938	between the Samba server and its clients. It provides file, print,
2939	and browse services to <span class="acronym">SMB</span> clients across one or
2940	more networks and handles all notifications between the Samba server
2941	and the network clients. In addition, it is responsible for user
2942	authentication, resource locking, and data sharing through the
2943	<span class="acronym">SMB</span> protocol.</p>
2944	</dd>
2945
2946	</dl>
2947
2948	<p>New with Version 2.2, there is an additional daemon:</p>
2949
2950	<dl>
2951	<dt><b><a name="INDEX-221"/><em class="emphasis">winbindd</em></b></dt>
2952	<dd>
2953	<p>This daemon is used along with the name service switch to get
2954	information on users and groups from a Windows NT server and allows
2955	Samba to authorize users through a Windows NT/2000 server.</p>
2956	</dd>
2957
2958	</dl>
2959
2960	<p>The Samba distribution also comes with a small set of Unix
2961	command-line tools:</p>
2962
2963	<dl>
2964	<dt><b><em class="emphasis">findsmb</em><a name="INDEX-222"/></b></dt>
2965	<dd>
2966	<p>A program that searches the local network for computers that respond
2967	to SMB protocol and prints information on them.</p>
2968	</dd>
2969
2970
2971
2972	<dt><b><em class="emphasis">make_smbcodepage</em><a name="INDEX-223"/></b></dt>
2973	<dd>
2974	<p>A program used when working with Samba's
2975	internationalization features for telling Samba how to convert
2976	between upper- and lowercase in different character sets.</p>
2977	</dd>
2978
2979
2980
2981	<dt><b><em class="emphasis">make_unicodemap</em><a name="INDEX-224"/></b></dt>
2982	<dd>
2983	<p>Another internationalization program used with Samba for compiling
2984	Unicode map files that Samba uses to translate DOS codepages or Unix
2985	character sets into 16-bit unicode.</p>
2986	</dd>
2987
2988
2989
2990	<dt><b><a name="INDEX-225"/><em class="emphasis">net</em></b></dt>
2991	<dd>
2992	<p>A new program distributed with Samba 3.0 that can be used to perform
2993	remote administration of servers.</p>
2994	</dd>
2995
2996
2997
2998	<dt><b><em class="emphasis">nmblookup</em><a name="INDEX-226"/></b></dt>
2999	<dd>
3000	<p>A program that provides NBT name lookups to find a
3001	computer's IP address when given its machine name.</p>
3002	</dd>
3003
3004
3005
3006	<dt><b><a name="INDEX-227"/><em class="emphasis">pdbedit</em></b></dt>
3007	<dd>
3008	<p>A new program distributed with Samba 3.0 that is helpful for managing
3009	user accounts held in SAM databases.</p>
3010	</dd>
3011
3012
3013
3014	<dt><b><em class="emphasis">rpcclient</em><a name="INDEX-228"/></b></dt>
3015	<dd>
3016	<p>A program that can be used to run MS-RPC functions on Windows clients.</p>
3017	</dd>
3018
3019
3020
3021	<dt><b><em class="emphasis">smbcacls</em><a name="INDEX-229"/></b></dt>
3022	<dd>
3023	<p>A program that is used to set or show ACLs on Windows NT filesystems.</p>
3024	</dd>
3025
3026
3027
3028	<dt><b><em class="emphasis">smbclient</em><a name="INDEX-230"/></b></dt>
3029	<dd>
3030	<p>An <em class="emphasis">ftp</em>-like Unix client that can be used to connect to
3031	SMB shares and operate on them. The <em class="emphasis">smbclient</em>
3032	command is discussed in detail in <a href="ch05.html">Chapter 5</a>.</p>
3033	</dd>
3034
3035
3036
3037	<dt><b><em class="emphasis">smbcontrol</em><a name="INDEX-231"/></b></dt>
3038	<dd>
3039	<p>A simple administrative utility that sends messages to <em class="emphasis">nmbd</em>
3040	or <em class="emphasis">smbd</em>.</p>
3041	</dd>
3042
3043
3044
3045	<dt><b><a name="INDEX-232"/><em class="emphasis">smbgroupedit</em></b></dt>
3046	<dd>
3047	<p>A command that can be used to define mappings between Windows NT
3048	groups and Unix groups. It is new in Samba 3.0.</p>
3049	</dd>
3050
3051
3052
3053	<dt><b><em class="emphasis">smbmnt</em><a name="INDEX-233"/></b></dt>
3054	<dd>
3055	<p>A helper utility used along with <em class="emphasis">smbmount.</em></p>
3056	</dd>
3057
3058
3059
3060	<dt><b><em class="emphasis">smbmount</em><a name="INDEX-234"/></b></dt>
3061	<dd>
3062	<p>A program that mounts an smbfs filesystem, allowing remote SMB shares
3063	to be mounted in the filesystem of the Samba host.</p>
3064	</dd>
3065
3066
3067
3068	<dt><b><em class="emphasis">smbpasswd</em><a name="INDEX-235"/></b></dt>
3069	<dd>
3070	<p>A program that allows an administrator to change the passwords used
3071	by Samba.</p>
3072	</dd>
3073
3074
3075
3076	<dt><b><em class="emphasis">smbsh</em><a name="INDEX-236"/></b></dt>
3077	<dd>
3078	<p>A tool that functions like a command shell to allow access to a
3079	remote SMB filesystem and allow Unix utilities to operate on it. This
3080	command is covered in <a href="ch05.html">Chapter 5</a>.</p>
3081	</dd>
3082
3083
3084
3085	<dt><b><em class="emphasis">smbspool</em><a name="INDEX-237"/></b></dt>
3086	<dd>
3087	<p>A print-spooling program used to send files to remote printers that
3088	are shared on the SMB network.</p>
3089	</dd>
3090
3091
3092
3093	<dt><b><em class="emphasis">smbstatus</em><a name="INDEX-238"/></b></dt>
3094	<dd>
3095	<p>A program that reports the current network connections to the shares
3096	on a Samba server.</p>
3097	</dd>
3098
3099
3100
3101	<dt><b><em class="emphasis">smbtar</em><a name="INDEX-239"/></b></dt>
3102	<dd>
3103	<p>A program similar to the Unix <em class="filename">tar</em> command, for
3104	backing up data in SMB shares.</p>
3105	</dd>
3106
3107
3108
3109	<dt><b><em class="emphasis">smbumount</em><a name="INDEX-240"/></b></dt>
3110	<dd>
3111	<p>A program that works along with <em class="emphasis">smbmount</em> to unmount
3112	smbfs filesystems.</p>
3113	</dd>
3114
3115
3116
3117	<dt><b><em class="emphasis">testparm</em><a name="INDEX-241"/></b></dt>
3118	<dd>
3119	<p>A simple program for checking the Samba configuration file.</p>
3120	</dd>
3121
3122
3123
3124	<dt><b><em class="emphasis">testprns</em><a name="INDEX-242"/></b></dt>
3125	<dd>
3126	<p>A program that tests whether printers on the Samba host are
3127	recognized by the <em class="filename">smbd</em> daemon.</p>
3128	</dd>
3129
3130
3131
3132	<dt><b><em class="emphasis">wbinfo</em><a name="INDEX-243"/></b></dt>
3133	<dd>
3134	<p>A utility used to query the <em class="filename">winbindd
3135	</em><a name="INDEX-244"/>daemon.</p>
3136	</dd>
3137
3138	</dl>
3139
3140	<p>Each major release of Samba goes through an exposure test before
3141	it's announced. In addition, it is quickly updated
3142	afterward if problems or unwanted side effects are found. The latest
3143	stable distribution as of this writing is Samba 2.2.6, and this book
3144	focuses mainly on the functionality supported in Samba 2.2.6, as
3145	opposed to older versions of Samba.</p>
3146
3147
3148	</div>
3149
3150
3151
3152	<div class="sect1"><a name="samba2-CHP-1-SECT-10"/>
3153
3154	<h2 class="head1">How Can I Get Samba?</h2>
3155
3156	<p><a name="INDEX-245"/><a name="INDEX-246"/>Source
3157	and binary distributions of Samba are available from mirror sites
3158	across the Internet. The primary web site for Samba is located at
3159	<a href="http://www.samba.org/">http://www.samba.org/</a>. From there, you
3160	can select a mirror site that is geographically near you.</p>
3161
3162	<p>Most Linux and many Unix vendors provide binary packages. These can
3163	be more convenient to install and maintain than the Samba
3164	team's source or binary packages, due to the
3165	vendor's efforts to supply a package that matches
3166	its specific products. <a name="INDEX-247"/></p>
3167
3168
3169	</div>
3170
3171	<hr/><h4 class="head4">Footnotes</h4><blockquote><a name="FOOTNOTE-1"/> <p><a href="#FNPTR-1">[1]</a> You
3172	can also right-click the shared resource in the Network Neighborhood
3173	and then select the Map Network Drive menu item.</p> <a name="FOOTNOTE-2"/> <p><a href="#FNPTR-2">[2]</a> Be
3174	warned that many end-user license agreements forbid installing a
3175	program on a network so that multiple clients can access it. Check
3176	the legal agreements that accompany the product to be absolutely
3177	sure.</p> <a name="FOOTNOTE-3"/> <p><a href="#FNPTR-3">[3]</a> You
3178	might also see the abbreviation NetBT, which is common in Microsoft
3179	literature.</p> <a name="FOOTNOTE-4"/>
3180	<p><a href="#FNPTR-4">[4]</a> See
3181	<a href="http://www.samba.org/cifs/docs/what-is-smb.html">http://www.samba.org/cifs/docs/what-is-smb.html</a>
3182	for Richard's excellent summary of
3183	<a name="INDEX-93"/>SMB.</p> <a name="FOOTNOTE-5"/> <p><a href="#FNPTR-5">[5]</a> This
3184	was originally called <a name="INDEX-126"/><a name="INDEX-127"/><a name="INDEX-128"/>Network Neighborhood in Windows 95/98/NT,
3185	but Microsoft has changed the name to My Network Places in the more
3186	recent Windows Me/2000/XP. We will continue to call it Network
3187	Neighborhood, and if you're using a new version of
3188	Windows, be aware that My Network Places can act a little differently
3189	in some ways.</p> </blockquote>
3190
3191
3192	<hr/><h4 class="head4"><a href="toc.html">TOC</a></h4>
3193	</body></html>

Note: See TracBrowser for help on using the repository browser.

Download in other formats: