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+<?xml version="1.0" encoding="iso-8859-1"?>
+<!DOCTYPE chapter PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
+<chapter id="kerberos">
+  <title>Active Directory, Kerberos, and Security</title>
+
+    <para><indexterm>
+	<primary>experiment</primary>
+      </indexterm>
+	By this point in the book, you have been exposed to many Samba-3 features and capabilities.
+	More importantly, if you have implemented the examples given, you are well on your way to becoming 
+	a Samba-3 networking guru who knows a lot about Microsoft Windows. If you have taken the time to 
+	practice, you likely have thought of improvements and scenarios with which you can experiment. You 
+	are rather well plugged in to the many flexible ways Samba can be used.
+	</para>
+
+    <para><indexterm>
+	<primary>criticism</primary>
+      </indexterm>
+	This is a book about Samba-3. Understandably, its intent is to present it in a positive light. 
+	The casual observer might conclude that this book is one-eyed about Samba. It is &smbmdash; what 
+	would you expect? This chapter exposes some criticisms that have been raised concerning 
+	the use of Samba. For each criticism, there are good answers and appropriate solutions.
+	</para>
+
+	<para>
+	Some criticism always comes from deep inside ranks that one would expect to be supportive of a particular 
+	decision. Criticism can be expected from the outside. Let's see how the interesting dynamic of 
+	criticism develops with respect to Abmas.
+	</para>
+
+    <para><indexterm>
+	<primary>straw-man</primary>
+      </indexterm>
+	This chapter provides a shameless self-promotion of Samba-3. The objections raised were not pulled
+	out of thin air. They were drawn from comments made by Samba users and from criticism during 
+	discussions with Windows network administrators. The tone of the objections reflects as closely 
+	as possible that of the original. The case presented is a straw-man example that is designed to 
+	permit each objection to be answered as it might occur in real life.
+	</para>
+
+<sect1>
+	<title>Introduction</title>
+
+      <para><indexterm>
+	  <primary>acquisitions</primary>
+	</indexterm><indexterm>
+	  <primary>risk</primary>
+	</indexterm><indexterm>
+	  <primary>assessment</primary>
+	</indexterm><indexterm>
+	  <primary>Active Directory</primary>
+	</indexterm><indexterm>
+	  <primary>Windows 2003 Serve</primary>
+	</indexterm>
+	Abmas is continuing its meteoric growth with yet further acquisitions. The investment community took
+	note of the spectacular projection of Abmas onto the global business stage. Abmas is building an
+	interesting portfolio of companies that includes accounting services, financial advice, investment
+	portfolio management, property insurance, risk assessment, and the recent addition of a a video rental
+	business. The pieces do not always appear to fit together, but Mr. Meany is certainly executing an 
+	interesting business growth and development plan. Abmas Video Rentals was recently acquired. 
+	During the time that the acquisition was closing, the Video Rentals business upgraded its Windows 
+	NT4-based network to Windows 2003 Server and Active Directory.
+	</para>
+
+      <para><indexterm>
+	  <primary>Active Directory</primary>
+	</indexterm>
+	You have accepted the fact that Abmas Video Rentals will use Microsoft Active Directory.
+	The IT team, led by Stan Soroka, is committed to Samba-3 and to maintaining a uniform technology platform. 
+	Stan Soroka's team voiced its disapproval over the decision to permit this business to continue to 
+	operate with a solution that is viewed by Christine and her group as <quote>an island of broken 
+	technologies.</quote> This comment was made by one of Christine's staff as they were installing a new 
+	Samba-3 server at the new business.
+	</para>
+
+
+      <para><indexterm>
+	  <primary>consultant</primary>
+	</indexterm><indexterm>
+	  <primary>hypothetical</primary>
+	</indexterm>
+	Abmas Video Rentals' head of IT heard of this criticism. He was offended that a junior engineer
+	should make such a comment. He felt that he had to prepare in case he might be criticized for his 
+	decision to use Active Directory. He decided he would defend his decision by hiring the services 
+	of an outside security systems consultant to report<footnote>This report is entirely fictitious. 
+	Any resemblance to a factual report is purely coincidental.</footnote> on his unit's operations 
+	and to investigate the role of Samba at his site. Here are key extracts from this hypothetical 
+	report:
+	</para>
+
+      <blockquote><para><indexterm>
+	    <primary>vulnerabilities</primary>
+	  </indexterm><indexterm>
+	    <primary>integrity</primary>
+	  </indexterm><indexterm>
+	    <primary>practices</primary>
+	  </indexterm><indexterm>
+	    <primary>Active Directory</primary>
+	  </indexterm>
+	... the implementation of Microsoft Active Directory at the Abmas Video Rentals, Bamingsham site,
+	 has been examined. We find no evidence to support a notion that vulnerabilities exist at your site.  
+	... we took additional steps to validate the integrity of the installation and operation of Active 
+	Directory and are pleased that your staff are following sound practices.
+	</para>
+
+	<para>
+	...
+	</para>
+
+	<para><indexterm>
+	    <primary>accounts</primary>
+	    <secondary>user</secondary>
+	  </indexterm><indexterm>
+	    <primary>accounts</primary>
+	    <secondary>group</secondary>
+	  </indexterm><indexterm>
+	    <primary>Backup</primary>
+	  </indexterm><indexterm>
+	    <primary>disaster recovery</primary>
+	  </indexterm><indexterm>
+	    <primary>validated</primary>
+	  </indexterm><indexterm>
+	    <primary>off-site storage</primary>
+	  </indexterm>
+	User and group accounts, and respective privileges, have been well thought out. File system shares are
+	appropriately secured. Backup and disaster recovery plans are well managed and validated regularly, and
+	effective off-site storage practices are considered to exceed industry norms.
+	</para>
+
+	<para><indexterm>
+	    <primary>compromise</primary>
+	  </indexterm><indexterm>
+	    <primary>secure</primary>
+	  </indexterm><indexterm>
+	    <primary>network</primary>
+	    <secondary>secure</secondary>
+	  </indexterm>
+	Your staff are justifiably concerned that the use of Samba may compromise their good efforts to maintain
+	a secure network. 
+	</para>
+
+	<para><indexterm>
+	    <primary>winbind</primary>
+	  </indexterm><indexterm>
+	    <primary>security</primary>
+	  </indexterm><indexterm>
+	    <primary>secure</primary>
+	  </indexterm><indexterm>
+	    <primary>network</primary>
+	    <secondary>management</secondary>
+	  </indexterm>
+	The recently installed Linux file and application server uses a tool called <command>winbind</command> 
+	that is indiscriminate about security. All user accounts in Active Directory can be used to access data 
+	stored on the Linux system. We are alarmed that secure information is accessible to staff who should 
+	not even be aware that it exists. We share the concerns of your network management staff who have gone 
+	to great lengths to set fine-grained controls that limit information access to those who need access. 
+	It seems incongruous to us that Samba winbind should be permitted to be used considering that it voids this fine work.
+	</para>
+
+	<para><indexterm>
+	    <primary>isolated</primary>
+	  </indexterm><indexterm>
+	    <primary>firewall</primary>
+	  </indexterm><indexterm>
+	    <primary>best practices</primary>
+	  </indexterm>
+	Graham Judd [head of network administration] has locked down the security of all systems and is following 
+	the latest Microsoft guidelines. ... null session connections have been disabled ... the internal network 
+	is isolated from the outside world, the [product name removed] firewall is under current contract 
+	maintenance support from [the manufacturer].  ... our attempts to penetrate security of your systems 
+	failed to find problems common to Windows networking sites. We commend your staff on their attention to 
+	detail and for following Microsoft recommended best practices.
+	</para>
+
+	<para>
+	...
+	</para>
+
+	<para><indexterm>
+	    <primary>security</primary>
+	  </indexterm><indexterm>
+	    <primary>disable</primary>
+	  </indexterm><indexterm>
+	    <primary>essential</primary>
+	  </indexterm><indexterm>
+	    <primary>trusted computing</primary>
+	  </indexterm>
+	Regarding the use of Samba, we offer the following comments: Samba is in use in nearly half of
+	all sites we have surveyed. ... It is our opinion that Samba offers no better security than Microsoft
+	... what worries us regarding Samba is the need to disable essential Windows security features such as
+	secure channel support, digital sign'n'seal on all communication traffic, and running Active Directory in
+	mixed mode so that Samba clients and servers can authenticate all of it. Additionally, we are concerned that
+	Samba is not at the full capabilities of Microsoft Windows NT4 server. Microsoft has moved well beyond that
+	with trusted computing initiatives that the Samba developers do not participate in.
+	</para>
+
+	<para><indexterm>
+	    <primary>integrity</primary>
+	  </indexterm><indexterm>
+	    <primary>hackers</primary>
+	  </indexterm><indexterm>
+	    <primary>accountable</primary>
+	  </indexterm><indexterm>
+	    <primary>flaws</primary>
+	  </indexterm><indexterm>
+	    <primary>updates</primary>
+	  </indexterm><indexterm>
+	    <primary>bug fixes</primary>
+	  </indexterm><indexterm>
+	    <primary>alarm</primary>
+	  </indexterm>
+	One wonders about the integrity of an open source program that is developed by a team of hackers 
+	who cannot be held accountable for the flaws in their code. The sheer number of updates and bug
+	fixes they have released should ring alarm bells in any business.
+	</para>
+
+	<para><indexterm>
+	    <primary>employment</primary>
+	  </indexterm><indexterm>
+	    <primary>jobs</primary>
+	  </indexterm><indexterm>
+	    <primary>risk</primary>
+	  </indexterm>
+	Another factor that should be considered is that buying Microsoft products and services helps to 
+	provide employment in the IT industry. Samba and Open Source software place those jobs at risk.
+	</para></blockquote>
+
+      <para><indexterm>
+	  <primary>Active Directory</primary>
+	</indexterm><indexterm>
+	  <primary>independent expert</primary>
+	</indexterm>
+	This is also a challenge to rise above the trouble spot. You call Stan's team together for a simple 
+	discussion, but it gets further out of hand.  When you return to your office, you find the following 
+	email in your in-box:
+	</para>
+
+	<para>
+	Good afternoon,
+	</para>
+
+	<blockquote><attribution>Stan</attribution><para>
+	I apologize for the leak of internal discussions to the new business. It reflects poorly on our 
+	professionalism and has put you in an unpleasant position. I regret the incident.
+	</para>
+
+	<para>
+	I also wish to advise that two of the recent recruits want to implement Kerberos authentication 
+	across all systems. I concur with the desire to improve security. One of the new guys who is championing
+	the move to Kerberos was responsible for the comment that caused the embarrassment.
+	</para>
+
+	<para><indexterm>
+	    <primary>Kerberos</primary>
+	  </indexterm><indexterm>
+	    <primary>OpenLDAP</primary>
+	  </indexterm><indexterm>
+	    <primary>Active Directory</primary>
+	  </indexterm><indexterm>
+	    <primary>consultant</primary>
+	  </indexterm>
+	I am experiencing difficulty in handling the sharp push for Kerberos. He claims that Kerberos, OpenLDAP, 
+	plus Samba-3 will seamlessly replace Microsoft Active Directory. I am a little out of my depth with respect 
+	to the feasibility of such a move, but have taken steps to pull both of them into line. With your consent, 
+	I would like to hire the services of a well-known Samba consultant to set the record straight.
+	</para>
+
+	<para><indexterm>
+	    <primary>criticism</primary>
+	  </indexterm><indexterm>
+	    <primary>policy</primary>
+	  </indexterm><indexterm>
+	    <primary>Windows Servers</primary>
+	  </indexterm><indexterm>
+	    <primary>Active Directory</primary>
+	  </indexterm><indexterm>
+	    <primary>budgetted</primary>
+	  </indexterm><indexterm>
+	    <primary>financial responsibility</primary>
+	  </indexterm>
+	I intend to use this report to answer the criticism raised and would like to establish a policy that we
+	will approve the use of Microsoft Windows Servers (and Active Directory) subject to all costs being covered 
+	out of the budget of the division that wishes to go its own way. I propose that dissenters will still remain
+	responsible to meet the budgeted contribution to IT operations as a whole. I believe we should not coerce 
+	use of any centrally proposed standards, but make all noncompliance the financial responsibility of the 
+	out-of-step division. Hopefully, this will encourage all divisions to walk with us and not alone.
+	</para></blockquote>
+
+	<sect2>
+		<title>Assignment Tasks</title>
+
+		<para>
+		You agreed with Stan's recommendations and hired a consultant to help defuse the powder
+		keg. The consultant's task is to provide a tractable answer to each of the issues raised. The consultant must be able
+		to support his or her claims, keep emotions to the side, and answer technically.
+		</para>
+
+	</sect2>
+</sect1>
+
+<sect1>
+	<title>Dissection and Discussion</title>
+
+      <para><indexterm>
+	  <primary>tool</primary>
+	</indexterm><indexterm>
+	  <primary>benefit</primary>
+	</indexterm><indexterm>
+	  <primary>choice</primary>
+	</indexterm><indexterm>
+	  <primary>consultant</primary>
+	</indexterm><indexterm>
+	  <primary>installation</primary>
+	</indexterm><indexterm>
+	  <primary>income</primary>
+	</indexterm><indexterm>
+	  <primary>employment</primary>
+	</indexterm>
+	Samba-3 is a tool. No one is pounding your door to make you use Samba. That is a choice that you are free to 
+	make or reject. It is likely that your decision to use Samba can greatly benefit your company. 
+	The Samba Team obviously believes that the Samba software is a worthy choice. 
+	If you hire a consultant to assist with the installation and/or deployment of Samba, or if you hire 
+	someone to help manage your Samba installation, you can create income and employment. Alternately, 
+	money saved by not spending in the IT area can be spent elsewhere in the business. All money saved 
+	or spent creates employment.
+	</para>
+
+      <para><indexterm>
+	  <primary>economically sustainable</primary>
+	</indexterm><indexterm>
+	  <primary>inter-operability</primary>
+	</indexterm><indexterm>
+	  <primary>file and print service</primary>
+	</indexterm><indexterm>
+	  <primary>cost</primary>
+	</indexterm><indexterm>
+	  <primary>alternative</primary>
+	</indexterm>
+	In the long term, the use of Samba must be economically sustainable. In some situations, Samba is adopted
+	purely to provide file and print service interoperability on platforms that otherwise cannot provide 
+	access to data and to printers for Microsoft Windows clients. Samba is used by some businesses to
+	effect a reduction in the cost of providing IT services. Obviously, it is also used by some as an 
+	alternative to the use of a Microsoft file and print serving platforms with no consideration of costs.
+	</para>
+
+      <para><indexterm>
+	  <primary>documentation</primary>
+	</indexterm><indexterm>
+	  <primary>responsibility</primary>
+	</indexterm><indexterm>
+	  <primary>fix</primary>
+	</indexterm><indexterm>
+	  <primary>broken</primary>
+	</indexterm>
+	It would be foolish to adopt a technology that might put any data or users at risk. Security affects 
+	everyone. The Samba-Team is fully cognizant of the responsibility they have to their users. 
+	The Samba documentation clearly reveals that full responsibility is accepted to fix anything 
+	that is broken.
+	</para>
+
+      <para><indexterm>
+	  <primary>commercial</primary>
+	</indexterm><indexterm>
+	  <primary>software</primary>
+	</indexterm><indexterm>
+	  <primary>commercial software</primary>
+	</indexterm><indexterm>
+	  <primary>End User License Agreement</primary>
+	  <see>EULA</see>
+	</indexterm><indexterm>
+	  <primary>accountable</primary>
+	</indexterm><indexterm>
+	  <secondary>liability</secondary>
+	</indexterm><indexterm>
+	  <primary>accepts liability</primary>
+	</indexterm><indexterm>
+	  <primary>price paid</primary>
+	</indexterm><indexterm>
+	  <primary>product defects</primary>
+	</indexterm><indexterm>
+	  <primary>reimburse</primary>
+	</indexterm><indexterm>
+	  <primary>extent</primary>
+	</indexterm>
+	There is a mistaken perception in the IT industry that commercial software providers are fully 
+	accountable for the defects in products. Open Source software comes with no warranty, so it is 
+	often assumed that its use confers a higher degree of risk. Everyone should read commercial software 
+	End User License Agreements (EULAs). You should determine what real warranty is offered and the 
+	extent of liability that is accepted. Doing so soon dispels the popular notion that
+	commercial software vendors are willingly accountable for product defects. In many cases, the
+	commercial vendor accepts liability only to reimburse the price paid for the software. 
+	</para>
+
+      <para><indexterm>
+	  <primary>consumer</primary>
+	</indexterm><indexterm>
+	  <primary>EULA</primary>
+	</indexterm><indexterm>
+	  <primary>track record</primary>
+	</indexterm><indexterm>
+	  <primary>commercial software</primary>
+	</indexterm><indexterm>
+	  <primary>support</primary>
+	</indexterm><indexterm>
+	  <primary>vendor</primary>
+	</indexterm>
+	The real issues that a consumer (like you) needs answered are What is the way of escape from technical 
+	problems, and how long will it take? The average problem turnaround time in the Open Source community is 
+	approximately 48 hours. What does the EULA offer? What is the track record in the commercial software 
+	industry? What happens when your commercial vendor decides to cease providing support?
+	</para>
+
+      <para><indexterm>
+	  <primary>source code</primary>
+	</indexterm><indexterm>
+	  <primary>Open Source</primary>
+	</indexterm><indexterm>
+	  <primary>hire</primary>
+	</indexterm><indexterm>
+	  <primary>programmer</primary>
+	</indexterm><indexterm>
+	  <primary>solve</primary>
+	</indexterm><indexterm>
+	  <primary>fix</primary>
+	</indexterm><indexterm>
+	  <secondary>problem</secondary>
+	</indexterm>
+	Open Source software at least puts you in possession of the source code. This means that when
+	all else fails, you can hire a programmer to solve the problem.
+	</para>
+
+	<sect2>
+		<title>Technical Issues</title>
+
+		<para>
+		Each issue is now discussed and, where appropriate, example implementation steps are
+		provided.
+		</para>
+
+	<variablelist>
+		<varlistentry>
+			<term>Winbind and Security</term>
+	    <listitem><para><indexterm>
+		  <primary>Winbind</primary>
+		</indexterm><indexterm>
+		  <primary>Security</primary>
+		</indexterm><indexterm>
+		  <primary>network</primary>
+		  <secondary>administrators</secondary>
+		</indexterm><indexterm>
+		  <primary>Domain users</primary>
+		</indexterm><indexterm>
+		  <secondary>Domain account</secondary>
+		</indexterm><indexterm>
+		  <primary>credentials</primary>
+		</indexterm><indexterm>
+		  <primary>Network Neighborhood</primary>
+		</indexterm><indexterm>
+		  <primary>UNIX/Linux server</primary>
+		</indexterm><indexterm>
+		  <primary>browse</primary>
+		</indexterm><indexterm>
+		  <primary>shares</primary>
+		</indexterm>
+				Windows network administrators may be dismayed to find that <command>winbind</command> 
+				exposes all domain users so that they may use their domain account credentials to 
+				log on to a UNIX/Linux system. The fact that all users in the domain can see the 
+				UNIX/Linux server in their Network Neighborhood and can browse the shares on the 
+				server seems to excite them further.
+				</para>
+
+	      <para><indexterm>
+		  <primary>Domain Member server</primary>
+		</indexterm><indexterm>
+		  <primary>familiar</primary>
+		</indexterm><indexterm>
+		  <primary>fear</primary>
+		</indexterm><indexterm>
+		  <primary>unknown</primary>
+		</indexterm>
+				<command>winbind</command> provides for the UNIX/Linux domain member server or 
+				client, the same as one would obtain by adding a Microsoft Windows server or 
+				client to the domain. The real objection is the fact that Samba is not MS Windows 
+				and therefore requires handling a little differently from the familiar Windows systems.
+				One must recognize fear of the unknown.
+				</para>
+
+	      <para><indexterm>
+		  <primary>network administrators</primary>
+		</indexterm><indexterm>
+		  <primary>recognize</primary>
+		</indexterm><indexterm>
+		  <primary>winbind</primary>
+		</indexterm><indexterm>
+		  <primary>over-ride</primary>
+		</indexterm><indexterm>
+		  <primary>Active Directory</primary>
+		  <secondary>management tools</secondary>
+		</indexterm><indexterm>
+		  <primary>fears</primary>
+		</indexterm>
+				Windows network administrators need to recognize that <command>winbind</command> does
+				not, and cannot, override account controls set using the Active Directory management
+				tools. The control is the same. Have no fear.
+				</para>
+
+	      <para><indexterm>
+		  <primary>ADS Domain</primary>
+		</indexterm><indexterm>
+		  <primary>account</primary>
+		  <secondary>ADS Domain</secondary>
+		</indexterm><indexterm>
+		  <primary>winbind</primary>
+		</indexterm><indexterm>
+		  <primary>browsing</primary>
+		</indexterm><indexterm>
+		  <primary>permits</primary>
+		</indexterm><indexterm>
+		  <primary>access</primary>
+		</indexterm><indexterm>
+		  <primary>drive mapping</primary>
+		</indexterm><indexterm>
+		  <primary>protected</primary>
+		</indexterm><indexterm>
+		  <primary>security controls</primary>
+		</indexterm><indexterm>
+		  <primary>access controls</primary>
+		</indexterm>
+				Where Samba and the ADS domain account information obtained through the use of
+				<command>winbind</command> permits access, by browsing or by the drive mapping to
+				a share, to data that should be better protected. This can only happen when security
+				controls have not been properly implemented. Samba permits access controls to be set
+				on:
+				</para>
+
+				<itemizedlist>
+					<listitem><para>Shares themselves (i.e., the logical share itself)</para></listitem>
+					<listitem><para>The share definition in &smb.conf;</para></listitem>
+					<listitem><para>The shared directories and files using UNIX permissions</para></listitem>
+                                        <listitem><para>Using Windows 2000 ACLs &smbmdash; if the file system is POSIX enabled</para></listitem>
+				</itemizedlist>
+
+				<para>
+				Examples of each are given in <link linkend="ch10expl"/>.
+				</para>
+				</listitem>
+		</varlistentry>
+
+		<varlistentry>
+			<term>User and Group Controls</term>
+	    <listitem><para><indexterm>
+		  <primary>User and Group Controls</primary>
+		</indexterm><indexterm>
+		  <primary>management</primary>
+		  <secondary>User</secondary>
+		</indexterm><indexterm>
+		  <primary>management</primary>
+		  <secondary>group</secondary>
+		</indexterm><indexterm>
+		  <primary>ADS</primary>
+		</indexterm><indexterm>
+		  <primary>permissions</primary>
+		</indexterm><indexterm>
+		  <primary>privileges</primary>
+		</indexterm><indexterm>
+		  <primary>flexibility</primary>
+		</indexterm><indexterm>
+		  <primary>access controls</primary>
+		</indexterm><indexterm>
+		  <primary>share definition</primary>
+		</indexterm>
+				User and group management facilities as known in the Windows ADS environment may be
+				used to provide equivalent access control constraints or to provide equivalent
+				permissions and privileges on Samba servers. Samba offers greater flexibility in the
+				use of user and group controls because it has additional layers of control compared to
+				Windows 200x/XP. For example, access controls on a Samba server may be set within
+				the share definition in a manner for which Windows has no equivalent.
+				</para>
+
+	      <para><indexterm>
+		  <primary>analysis</primary>
+		</indexterm><indexterm>
+		  <primary>system security</primary>
+		</indexterm><indexterm>
+		  <primary>safe-guards</primary>
+		</indexterm><indexterm>
+		  <primary>permissions</primary>
+		  <secondary>excessive</secondary>
+		</indexterm><indexterm>
+		  <primary>file system</primary>
+		</indexterm><indexterm>
+		  <primary>shared resource</primary>
+		</indexterm><indexterm>
+		  <primary>share definition</primary>
+		</indexterm>
+				In any serious analysis of system security, it is important to examine the safeguards
+				that remain when all other protective measures fail. An administrator may inadvertently
+				set excessive permissions on the file system of a shared resource, or he may set excessive
+				privileges on the share itself. If that were to happen in a Windows 2003 Server environment,
+				the data would indeed be laid bare to abuse. Yet, within a Samba share definition, it is
+				possible to guard against that by enforcing controls on the share definition itself. You
+				see a practical example of this a little later in this chapter.
+				</para>
+
+	      <para><indexterm>
+		  <primary>diligence</primary>
+		</indexterm><indexterm>
+		  <primary>weakness</primary>
+		</indexterm>
+				The report that is critical of Samba really ought to have exercised greater due
+				diligence: the real weakness is on the side of a Microsoft Windows environment.
+				</para></listitem>
+		</varlistentry>
+
+		<varlistentry>
+			<term>Security Overall</term>
+	    <listitem><para><indexterm>
+		  <primary>defects</primary>
+		</indexterm>
+				Samba is designed in such a manner that weaknesses inherent in the design of
+				Microsoft Windows networking ought not to expose the underlying UNIX/Linux file
+				system in any way. All software has potential defects, and Samba is no exception.
+				What matters more is how defects that are discovered get dealt with.
+				</para>
+
+	      <para><indexterm>
+		  <primary>security</primary>
+		</indexterm><indexterm>
+		  <primary>protection</primary>
+		</indexterm><indexterm>
+		  <primary>compromise</primary>
+		</indexterm><indexterm>
+		  <primary>consequential risk</primary>
+		</indexterm>
+				The Samba Team totally agrees with the necessity to observe and fully implement
+				every security facility to provide a level of protection and security that is necessary
+				and that the end user (or network administrator) needs. Never would the Samba Team
+				recommend a compromise to system security, nor would deliberate defoliation of
+				security be publicly condoned; yet this is the practice by many Windows network
+				administrators just to make happy users who have no notion of consequential risk.
+				</para>
+
+	      <para><indexterm>
+		  <primary>condemns</primary>
+		</indexterm><indexterm>
+		  <primary>security fixes</primary>
+		</indexterm><indexterm>
+		  <primary>updates</primary>
+		</indexterm><indexterm>
+		  <primary>development</primary>
+		</indexterm><indexterm>
+		  <primary>documentation</primary>
+		</indexterm><indexterm>
+		  <primary>security updates</primary>
+		</indexterm><indexterm>
+		  <primary>turn-around time</primary>
+		</indexterm>
+				The report condemns Samba for releasing updates and security fixes, yet Microsoft
+				online updates need to be applied almost weekly. The answer to the criticism 
+				lies in the fact that Samba development is continuing, documentation is improving, 
+				user needs are being increasingly met or exceeded, and security updates are issued 
+				with a short turnaround time.
+				</para>
+
+	      <para><indexterm>
+		  <primary>modularization</primary>
+		</indexterm><indexterm>
+		  <primary>next generation</primary>
+		</indexterm><indexterm>
+		  <primary>responsible</primary>
+		</indexterm><indexterm>
+		  <primary>dependability</primary>
+		</indexterm><indexterm>
+		  <primary>road-map</primary>
+		  <secondary>published</secondary>
+		</indexterm>
+				The release of Samba-4 is expected around late 2004 to early 2005 and involves a near 
+				complete rewrite to permit extensive modularization and to prepare Samba for new 
+				functionality planned for addition during the next-generation series. The Samba Team 
+				is responsible and can be depended upon; the history to date suggests a high 
+				degree of dependability and on charter development consistent with published 
+				roadmap projections.
+				</para>
+
+	      <para><indexterm>
+		  <primary>foundation members</primary>
+		</indexterm><indexterm>
+		  <primary>Common Internet File System</primary>
+		  <see>CIFS</see>
+		</indexterm><indexterm>
+		  <primary>network attached storage</primary>
+		  <see>NAS</see>
+		</indexterm><indexterm>
+		  <primary>conferences</primary>
+		</indexterm><indexterm>
+		  <primary>presence and leadership</primary>
+		</indexterm><indexterm>
+		  <primary>leadership</primary>
+		</indexterm><indexterm>
+		  <primary>inter-operability</primary>
+		</indexterm>
+				Not well published is the fact that Microsoft was a foundation member of
+				the Common Internet File System (CIFS) initiative, together with the participation 
+				of the network attached storage (NAS) industry. Unfortunately, for the past few years,
+				Microsoft has been absent from active involvement at CIFS conferences and has
+				not exercised the leadership expected of a major force in the networking technology
+				space. The Samba Team has maintained consistent presence and leadership at all
+				CIFS conferences and at the interoperability laboratories run concurrently with
+				them.
+				</para></listitem>
+		</varlistentry>
+
+		<varlistentry>
+			<term>Cryptographic Controls (schannel, sign'n'seal)</term>
+	    <listitem><para><indexterm>
+		  <primary>Cryptographic</primary>
+		</indexterm><indexterm>
+		  <primary>schannel</primary>
+		</indexterm><indexterm>
+		  <primary>digital sign'n'seal</primary>
+		</indexterm>
+				The report correctly mentions that Samba did not support the most recent
+				<constant>schannel</constant> and <constant>digital sign'n'seal</constant> features
+				of Microsoft Windows NT/200x/XPPro products. This is one of the key features 
+				of the Samba-3 release. Market research reports take so long to generate that they are
+				seldom a reflection of current practice, and in many respects reports are like a
+				pathology report &smbmdash; they reflect accurately (at best) status at a snapshot in time.
+				Meanwhile, the world moves on.
+				</para>
+
+	      <para><indexterm>
+		  <primary>public specifications</primary>
+		</indexterm><indexterm>
+		  <primary>protocols</primary>
+		</indexterm><indexterm>
+		  <primary>algorithm</primary>
+		</indexterm><indexterm>
+		  <primary>compatible</primary>
+		</indexterm><indexterm>
+		  <primary>network</primary>
+		  <secondary>traffic</secondary>
+		  <tertiary>observation</tertiary>
+		</indexterm><indexterm>
+		  <primary>defensible standards</primary>
+		</indexterm><indexterm>
+		  <primary>secure networking</primary>
+		</indexterm>
+				It should be pointed out that had clear public specifications for the protocols
+				been published, it would have been much easier to implement these features and would have
+				taken less time to do. The sole mechanism used to find an algorithm that is compatible
+				with the methods used by Microsoft has been based on observation of network traffic
+				and trial-and-error implementation of potential techniques. The real value of public
+				and defensible standards is obvious to all and would have enabled more secure networking
+				for everyone.
+				</para>
+
+	      <para><indexterm>
+		  <primary>Critics</primary>
+		</indexterm><indexterm>
+		  <primary>digital sign'n'seal</primary>
+		</indexterm>
+				Critics of Samba often ignore fundamental problems that may plague (or may have plagued)
+				the users of Microsoft's products also. Those who are first to criticize Samba
+				for not rushing into release of <constant>digital sign'n'seal</constant> support
+				often dismiss the problems that Microsoft has 
+				<ulink url="http://support.microsoft.com/default.aspx?kbid=321733">acknowledged</ulink>
+				and for which a fix was provided. In fact,
+				<ulink url="http://www.tangent-systems.com/support/delayedwrite.html">Tangent Systems</ulink> 
+				appears even today<footnote>January 2004</footnote> to be unsure whether the problem has been resolved,
+				it is evident that some delay in release of new functionality may have
+				fortuitous consequences.
+				</para>
+
+	      <para><indexterm>
+		  <primary>secure networking protocols</primary>
+		</indexterm><indexterm>
+		  <primary>refereed standards</primary>
+		</indexterm><indexterm>
+		  <primary>proprietary</primary>
+		</indexterm><indexterm>
+		  <primary>digital rights</primary>
+		</indexterm><indexterm>
+		  <primary>protection</primary>
+		</indexterm><indexterm>
+		  <primary>networking protocols</primary>
+		</indexterm><indexterm>
+		  <primary>diffusion</primary>
+		</indexterm><indexterm>
+		  <primary>consumer</primary>
+		</indexterm><indexterm>
+		  <primary>choice</primary>
+		</indexterm>
+				One final comment is warranted. If companies want more secure networking protocols,
+				the most effective method by which this can be achieved is by users seeking
+				and working together to help define open and publicly refereed standards. The
+				development of closed source, proprietary methods that are developed in a
+				clandestine framework of secrecy, under claims of digital rights protection, does
+				not favor the diffusion of safe networking protocols and certainly does not
+				help the consumer to make a better choice.
+				</para></listitem>
+		</varlistentry>
+
+		<varlistentry>
+			<term>Active Directory Replacement with Kerberos, LDAP, and Samba</term>
+	        <indexterm>
+		  <primary>Active Directory</primary>
+		  <secondary>Replacement</secondary>
+		</indexterm><indexterm>
+		  <primary>Kerberos</primary>
+		</indexterm><indexterm>
+		  <primary>LDAP</primary>
+		</indexterm><indexterm>
+		  <primary>remote procedure call</primary>
+		  <see>RPC</see>
+		</indexterm>
+				<listitem><para>
+				<literallayout>    </literallayout>
+				The Microsoft networking protocols extensively make use of remote procedure call (RPC)
+				technology. Active Directory is not a simple mixture of LDAP and Kerberos together
+				with file and print services, but rather is a complex, intertwined implementation
+				of them that uses RPCs that are not supported by any of these component technologies
+				and yet by which they are made to interoperate in ways that the components do not
+				support.
+				</para>
+
+	      <para><indexterm>
+		  <primary>Active Directory</primary>
+		  <secondary>Server</secondary>
+		</indexterm><indexterm>
+		  <primary>OpenLDAP</primary>
+		</indexterm><indexterm>
+		  <primary>Kerberos</primary>
+		</indexterm><indexterm>
+		  <primary>project maintainers</primary>
+		</indexterm><indexterm>
+		  <primary>LDAP</primary>
+		</indexterm>
+				In order to make the popular request for Samba to be an Active Directory Server a
+				reality, it is necessary to add to OpenLDAP, Kerberos, as well as Samba, RPC calls
+				that are not presently supported. The Samba Team has not been able to gain critical
+				overall support for all project maintainers to work together on the complex
+				challenge of developing and integrating the necessary technologies. Therefore, if
+				the Samba Team does not make it a priority to absorb Kerberos and LDAP functionality
+				into the Samba project, this dream request cannot become a reality.
+				</para>
+
+	      <para><indexterm>
+		  <primary>missing RPC's</primary>
+		</indexterm><indexterm>
+		  <primary>road-map</primary>
+		</indexterm><indexterm>
+		  <primary>ADS</primary>
+		  <secondary>server</secondary>
+		</indexterm><indexterm>
+		  <primary>MMC</primary>
+		</indexterm><indexterm>
+		  <primary>managed</primary>
+		</indexterm>
+				At this time, the integration of LDAP, Kerberos, and the missing RPCs is not on the
+				Samba development roadmap. If it is not on the published roadmap, it cannot be delivered
+				anytime soon. Ergo, ADS server support is not a current goal for Samba development.
+				The Samba Team is most committed to permitting Samba to be a full ADS domain member
+				that is increasingly capable of being managed using Microsoft Windows MMC tools.
+				</para></listitem>
+		</varlistentry>
+	</variablelist>
+
+	<sect3>
+	<title>Kerberos Exposed</title>
+
+	  <para><indexterm>
+	      <primary>kerberos</primary>
+	    </indexterm><indexterm>
+	      <primary>unauthorized activities</primary>
+	    </indexterm><indexterm>
+	      <primary>authorized location</primary>
+	    </indexterm>
+	Kerberos is a network authentication protocol that provides secure authentication for 
+	client-server applications by using secret-key cryptography. Firewalls are an insufficient 
+	barrier mechanism in today's networking world; at best they only restrict incoming network 
+	traffic but cannot prevent network traffic that comes from authorized locations from 
+	performing unauthorized activities.
+	</para>
+
+	  <para><indexterm>
+	      <primary>strong cryptography</primary>
+	    </indexterm><indexterm>
+	      <primary>identity</primary>
+	    </indexterm><indexterm>
+	      <primary>integrity</primary>
+	    </indexterm>
+	Kerberos was created by MIT as a solution to network security problems. The Kerberos protocol uses 
+	strong cryptography so that a client can prove its identity to a server (and vice versa) across an 
+	insecure network connection. After a client and server has used Kerberos to prove their identity, 
+	they can also encrypt all of their communications to assure privacy and data integrity as they go 
+	about their business.
+	</para>
+
+	  <para><indexterm>
+	      <primary>trusted third-party</primary>
+	    </indexterm><indexterm>
+	      <primary>principals</primary>
+	    </indexterm><indexterm>
+	      <primary>trusting</primary>
+	    </indexterm><indexterm>
+	      <primary>kerberos</primary>
+	      <secondary>server</secondary>
+	    </indexterm><indexterm>
+	      <primary>secret</primary>
+	    </indexterm>
+	Kerberos is a trusted third-party service. That means that there is a third party (the kerberos 
+	server) that is trusted by all the entities on the network (users and services, usually called 
+	principals). All principals share a secret password (or key) with the kerberos server and this 
+	enables principals to verify that the messages from the kerberos server are authentic. Therefore, 
+	trusting the kerberos server, users and services can authenticate each other.
+	</para>
+
+	  <para><indexterm>
+	      <primary>restricted export</primary>
+	    </indexterm><indexterm>
+	      <primary>MIT Kerberos</primary>
+	    </indexterm><indexterm>
+	      <primary>Heimdal Kerberos</primary>
+	    </indexterm>
+	Kerberos was, until recently, a technology that was restricted from being exported from the United States.
+	For many years that hindered global adoption of more secure networking technologies both within the United States
+	and abroad. A free and unencumbered implementation of MIT Kerberos has been produced in Europe
+	and is available from the University of Paderborn, Sweden. It is known as the Heimdal Kerberos project.
+	In recent times the U.S. government has removed sanctions affecting the global distribution of MIT Kerberos.
+	It is likely that there will be a significant surge forward in the development of Kerberos-enabled applications
+	and in the general deployment and use of Kerberos across the spectrum of the information technology industry.
+	</para>
+
+	  <para><indexterm>
+	      <primary>Kerberos</primary>
+	      <secondary>interoperability</secondary>
+	    </indexterm>
+	A storm has broken out concerning interoperability between MIT Kerberos and Microsofts' implementation
+	of it. For example, a 2002 report by <ulink url="http://www.idg.com.sg/idgwww.nsf/0/5DDA8D153A7505A748256BAB000D992A?OpenDocument">IDG</ulink>
+	states:
+	</para>
+
+	<blockquote><para>
+	A Microsoft Corp. executive testified at the software giant's remedy hearing that the company goes to 
+	great lengths to disclose interfaces and protocols that allow third-party software products to interact 
+	with Windows. But a lawyer with the states suing Microsoft pointed out that when it comes to the company's 
+	use of the Kerberos authentication specification, not everyone agrees.
+	</para>
+
+	    <para><indexterm>
+		<primary>Kerberos</primary>
+		<secondary>unspecified fields</secondary>
+	      </indexterm>
+	Robert Short, vice president of Windows core technology at Microsoft, wrote in his direct testimony prepared 
+	before his appearance that non-Microsoft operating systems can disregard the portion of the Kerberos version 
+	5 specification that Windows clients use for proprietary purposes and still achieve interoperability with 
+	the Microsoft OS. Microsoft takes advantage of unspecified fields in the Kerberos specification for storing 
+	Windows-specific authorization data, Short wrote. The designers of Kerberos left these fields undefined so 
+	that software developers could add their own authorization information, he said.
+	</para></blockquote>
+
+	  <para><indexterm>
+	      <primary>DCE</primary>
+	    </indexterm><indexterm>
+	      <primary>RPC</primary>
+	    </indexterm>
+	It so happens that Microsoft Windows clients depend on and expect the contents of the <emphasis>unspecified
+	fields</emphasis> in the Kerberos 5 communications data stream for their Windows interoperability,
+	particularly when Samba is expected to emulate a Windows Server 200x domain controller. But the interoperability
+	issue goes far deeper than this. In the domain control protocols that are used by MS Windows XP Professional,
+	there is a tight interdependency between the Kerberos protocols and the Microsoft distributed computing environment
+	(DCE) RPCs that themselves are an integral part of the SMB/CIFS protocols as used by
+	Microsoft.
+	</para>
+
+	<para>
+	Microsoft makes the following comment in a reference in a <ulink url="http://www.microsoft.com/technet/itsolutions/interop/mgmt/kerberos.asp">
+	technet</ulink> article:
+	</para>
+
+	  <blockquote><para><indexterm>
+		<primary>Privilege Attribute Certificates</primary>
+		<see>PAC</see>
+	      </indexterm><indexterm>
+		<primary>access control</primary>
+	      </indexterm>
+	The DCE Security Services are also layered on the Kerberos protocol. DCE authentication services use RPC 
+	representation of Kerberos protocol messages. In addition, DCE uses the authorization data field in Kerberos 
+	tickets to convey Privilege Attribute Certificates (PACs) that define user identity and group membership. 
+	The DCE PAC is used in a similar manner as Windows NT Security IDs for user authorization and access control. 
+	Windows NT services will not be able to translate DCE PACs into Windows NT user and group identifiers. This 
+	is not an issue with Kerberos interoperability, but rather an issue of interoperability between DCE and 
+	Windows NT access control information.
+	</para></blockquote>
+
+	</sect3>
+
+	</sect2>
+
+</sect1>
+
+<sect1 id="ch10expl">
+	<title>Implementation</title>
+
+	<para>
+	The following procedures outline the implementation of the security measures discussed so far.
+	</para>
+
+	<sect2>
+	<title>Share Access Controls</title>
+
+	<para><indexterm>
+	    <primary>Share Access Controls</primary>
+	  </indexterm><indexterm>
+	    <primary>filter</primary>
+	  </indexterm><indexterm>
+	    <primary>connection</primary>
+	  </indexterm>
+	Access control entries placed on the share itself act as a filter at the time a when CIFS/SMB client (such as
+	Windows XP Pro) attempts to make a connection to the Samba server.
+	</para>
+
+	<procedure>
+	<title>Create/Edit/Delete Share ACLs</title>
+	  <step><para><indexterm>
+		<primary>Domain Administrator</primary>
+	      </indexterm><indexterm>
+		<primary>account</primary>
+	      </indexterm>
+		From a Windows 200x/XP Professional workstation, log on to the domain using the Domain Administrator 
+		account (on Samba domains, this is usually the account called <constant>root</constant>).
+		</para></step>
+
+		<step><para>
+		Click 
+		<menuchoice>
+			<guimenu>Start</guimenu>
+			<guimenuitem>Settings</guimenuitem>
+			<guimenuitem>Control Panel</guimenuitem>
+			<guimenuitem>Administrative Tools</guimenuitem>
+			<guimenuitem>Computer Management</guimenuitem>
+		</menuchoice>.
+		</para></step>
+
+		<step><para>
+		In the left panel,
+		<menuchoice>
+			<guimenu>[Right mouse menu item] Computer Management (Local)</guimenu>
+			<guimenuitem>Connect to another computer ...</guimenuitem>
+			<guimenuitem>Browse...</guimenuitem>
+			<guimenuitem>Advanced</guimenuitem>
+			<guimenuitem>Find Now</guimenuitem>
+		</menuchoice>. In the lower panel, click on the name of the server you wish to
+		administer. Click <menuchoice>
+				<guimenu>OK</guimenu>
+				<guimenuitem>OK</guimenuitem>
+				<guimenuitem>OK</guimenuitem>
+	      </menuchoice>.<indexterm>
+		<primary>Computer Management</primary>
+	      </indexterm>
+		In the left panel, the entry <guimenu>Computer Management (Local)</guimenu> should now reflect
+		the change made. For example, if the server you are administering is called <constant>FRODO</constant>,
+		the Computer Management entry should now say <guimenu>Computer Management (FRODO)</guimenu>.
+		</para></step>
+
+		<step><para>
+		In the left panel, click <menuchoice>
+			<guimenu>Computer Management (FRODO)</guimenu>
+			<guimenuitem>[+] Shared Folders</guimenuitem>
+			<guimenuitem>Shares</guimenuitem>
+		</menuchoice>.
+		</para></step>
+
+	  <step><para><indexterm>
+		<primary>ACLs</primary>
+	      </indexterm><indexterm>
+		<primary>Share Permissions</primary>
+	      </indexterm>
+		In the right panel, double-click on the share on which you wish to set/edit ACLs. This
+		will bring up the Properties panel. Click the <guimenu>Share Permissions</guimenu> tab.
+		</para></step>
+
+	  <step><para><indexterm>
+		<primary>access control settings</primary>
+	      </indexterm><indexterm>
+		<primary>Everyone</primary>
+	      </indexterm><indexterm>
+		<primary>full control</primary>
+	      </indexterm><indexterm>
+		<primary>over-rule</primary>
+	      </indexterm><indexterm>
+		<primary>permissions</primary>
+	      </indexterm><indexterm>
+		<primary>rejected</primary>
+	      </indexterm>
+		You may now edit/add/remove access control settings. Be very careful. Many problems have been
+		created by people who decided that everyone should be rejected but one particular group should
+		have full control. This is a catch-22 situation because members of that particular group also
+		belong to the group <constant>Everyone</constant>, which therefore overrules any permissions
+		set for the permitted group.
+		</para></step>
+
+		<step><para>
+		When you are done with editing, close all panels by clicking through the <guimenu>OK</guimenu>
+		buttons.
+		</para></step>
+	</procedure>
+
+	</sect2>
+
+	<sect2>
+	<title>Share Definition Controls</title>
+
+	<para><indexterm>
+	    <primary>Share Definition</primary>
+	    <secondary>Controls</secondary>
+	  </indexterm><indexterm>
+	    <primary>check-point</primary>
+	  </indexterm><indexterm>
+	    <primary>pile-driver</primary>
+	  </indexterm><indexterm>
+	    <primary>credential</primary>
+	  </indexterm><indexterm>
+	    <primary>powers</primary>
+	  </indexterm><indexterm>
+	    <primary>privileges</primary>
+	  </indexterm>
+	Share-definition-based access controls can be used like a checkpoint or like a pile-driver. Just as a
+	checkpoint can be used to require someone who wants to get through to meet certain requirements, so
+	it is possible to require the user (or group the user belongs to) to meet specified credential-related 
+	objectives. It can be likened to a pile-driver by overriding default controls in that having met the 
+	credential-related objectives, the user can be granted powers and privileges that would not normally be 
+	available under default settings.
+	</para>
+
+	<para><indexterm>
+	    <primary>access controls</primary>
+	  </indexterm><indexterm>
+	    <primary>ACLs</primary>
+	  </indexterm><indexterm>
+	    <primary>share definition controls</primary>
+	  </indexterm><indexterm>
+	    <primary>hierarchy of control</primary>
+	  </indexterm>
+	It must be emphasized that the controls discussed here can act as a filter or give rights of passage
+	that act as a superstructure over normal directory and file access controls. However, share-level
+	ACLs act at a higher level than do share definition controls because the user must filter through the
+	share-level controls to get to the share-definition controls. The proper hierarchy of controls implemented
+	by Samba and Windows networking consists of:
+	</para>
+
+	<orderedlist>
+		<listitem><para>Share-level ACLs</para></listitem>
+		<listitem><para>Share-definition controls</para></listitem>
+		<listitem><para>Directory and file permissions</para></listitem>
+		<listitem><para>Directory and file POSIX ACLs</para></listitem>
+	</orderedlist>
+
+	<sect3>
+	<title>Checkpoint Controls</title>
+
+	  <para><indexterm>
+	      <primary>Checkpoint Controls</primary>
+	    </indexterm>
+	Consider the following extract from a &smb.conf; file defining the share called <constant>Apps</constant>:
+<screen>
+[Apps]
+	comment = Application Share
+	path = /data/apps
+	read only = Yes
+	valid users = @Employees
+</screen>
+	This definition permits only those who are members of the group called <constant>Employees</constant> to 
+	access the share.
+	</para>
+
+	  <note><para><indexterm>
+		<primary>Domain Member</primary>
+		<secondary>servers</secondary>
+	      </indexterm><indexterm>
+		<primary>winbind use default domain</primary>
+	      </indexterm><indexterm>
+		<primary>fully qualified</primary>
+	      </indexterm><indexterm>
+		<primary>valid users</primary>
+	      </indexterm><indexterm>
+		<primary>delimiter</primary>
+	      </indexterm>
+	On domain member servers and clients, even when the <parameter>winbind use default domain</parameter> has
+	been specified, the use of domain accounts in security controls requires fully qualified domain specification,
+	for example, <smbconfoption name="valid users">@"MEGANET\Northern Engineers"</smbconfoption>. 
+	Note the necessity to use the double quotes to avoid having the space in the Windows group name interpreted as a
+	delimiter. 
+	</para></note>
+
+	  <para><indexterm>
+	      <primary>ACL</primary>
+	    </indexterm><indexterm>
+	      <primary>access</primary>
+	    </indexterm><indexterm>
+	      <primary>validate</primary>
+	    </indexterm>
+	If there is an ACL on the share itself to permit read/write access for all <constant>Employees</constant>
+	as well as read/write for the group <constant>Doctors</constant>, both groups are permitted through
+	to the share. However, at the moment an attempt is made to set up a connection to the share, a member of
+	the group <constant>Doctors</constant>, who is not also a member of the group <constant>Employees</constant>,
+	would immediately fail to validate.
+	</para>
+
+	  <para><indexterm>
+	      <primary>share definition controls</primary>
+	    </indexterm>
+	Consider another example. In this case, you want to permit all members of the group <constant>Employees</constant>
+	except the user <constant>patrickj</constant> to access the <constant>Apps</constant> share. This can be
+	easily achieved by setting a share-level ACL permitting only <constant>Employees</constant> to access the share,
+	and then in the share definition controls excluding just <constant>patrickj</constant>. Here is how that might
+	be done:
+<screen>
+[Apps]
+        comment = Application Share
+        path = /data/apps
+        read only = Yes
+        invalid users = patrickj
+</screen>
+	    <indexterm>
+	      <primary>permissions</primary>
+	    </indexterm>
+	Let us assume that you want to permit the user <constant>gbshaw</constant> to manage any file in the
+	UNIX/Linux file system directory <filename>/data/apps</filename>, but you do not want to grant any write
+	permissions beyond that directory tree. Here is one way this can be done:
+<screen>
+[Apps]
+        comment = Application Share
+        path = /data/apps
+        read only = Yes
+        invalid users = patrickj
+        admin users = gbshaw
+</screen>
+	    <indexterm>
+	      <primary>administrative rights</primary>
+	    </indexterm>
+	Now we have a set of controls that permits only <constant>Employees</constant> who are also members of
+	the group <constant>Doctors</constant>, excluding the user <constant>patrickj</constant>, to have 
+	read-only privilege, but the user <constant>gbshaw</constant> is granted administrative rights.
+	The administrative rights conferred upon the user <constant>gbshaw</constant> permit operation as
+	if that user has logged in as the user <constant>root</constant> on the UNIX/Linux system and thus,
+	for access to the directory tree that has been shared (exported), permit the user to override controls
+	that apply to all other users on that resource.
+	</para>
+
+	<para>
+	There are additional checkpoint controls that may be used. For example, if for the same share we now
+	want to provide the user <constant>peters</constant> with the ability to write to one directory to
+	which he has write privilege in the UNIX file system, you can specifically permit that with the
+	following settings:
+<screen>
+[Apps]
+        comment = Application Share
+        path = /data/apps
+        read only = Yes
+        invalid users = patrickj
+        admin users = gbshaw
+        write list = peters
+</screen>
+	    <indexterm>
+	      <primary>check-point controls</primary>
+	    </indexterm>
+	This is a particularly complex example at this point, but it begins to demonstrate the possibilities.
+	You should refer to the online manual page for the &smb.conf; file for more information regarding
+	the checkpoint controls that Samba implements.
+	</para>
+
+	</sect3>
+
+	<sect3>
+	<title>Override Controls</title>
+
+	  <para><indexterm>
+	      <primary>over-ride controls</primary>
+	    </indexterm>
+	Override controls implemented by Samba permit actions like the adoption of a different identity 
+	during file system operations, the forced overwriting of normal file and directory permissions,
+	and so on. You should refer to the online manual page for the &smb.conf; file for more information regarding
+        the override controls that Samba implements.
+	</para>
+
+	<para>
+	In the following example, you want to create a Windows networking share that any user can access.
+	However, you want all read and write operations to be performed as if the user <constant>billc</constant>
+	and member of the group <constant>Mentors</constant> read/write the files. Here is one way this
+	can be done:
+<screen>
+[someshare]
+	comment = Some Files Everyone May Overwrite
+	path = /data/somestuff
+	read only = No
+	force user = billc
+	force group = Mentors
+</screen>
+	    <indexterm>
+	      <primary>forced settings</primary>
+	    </indexterm><indexterm>
+	      <primary>overheads</primary>
+	    </indexterm>
+	That is all there is to it. Well, it is almost that simple. The downside of this method is that
+	users are logged onto the Windows client as themselves, and then immediately before accessing the
+	file, Samba makes system calls to change the effective user and group to the forced settings
+	specified, completes the file transaction, and then reverts to the actually logged-on identity.
+	This imposes significant overhead on Samba. The alternative way to effectively achieve the same result
+	(but with lower system CPU overheads) is described next.
+	</para>
+
+	  <para><indexterm>
+	      <primary>force user</primary>
+	    </indexterm><indexterm>
+	      <primary>force group</primary>
+	    </indexterm><indexterm>
+	      <primary>opportunistic</primary>
+	      <secondary>locking</secondary>
+	    </indexterm><indexterm>
+	      <primary>oplock break</primary>
+	    </indexterm><indexterm>
+	      <primary>performance degradation</primary>
+	    </indexterm>
+	The use of the <parameter>force user</parameter> or the <parameter>force group</parameter> may
+	also have a severe impact on system (particularly on Windows client) performance. If opportunistic
+	locking is enabled on the share (the default), it causes an <constant>oplock break</constant> to be
+	sent to the client even if the client has not opened the file. On networks that have high traffic
+	density, or on links that are routed to a remote network segment, <constant>oplock breaks</constant>
+	can be lost. This results in possible retransmission of the request, or the client may time-out while
+	waiting for the file system transaction (read or write) to complete. The result can be a profound
+	apparent performance degradation as the client continually attempts to reconnect to overcome the
+	effect of the lost <constant>oplock break</constant>, or time-out.
+	</para>
+	
+	</sect3>
+
+	</sect2>
+
+	<sect2>
+	<title>Share Point Directory and File Permissions</title>
+
+	<para><indexterm>
+	    <primary>security</primary>
+	  </indexterm><indexterm>
+	    <primary>privilege controls</primary>
+	  </indexterm><indexterm>
+	    <primary>permission</primary>
+	  </indexterm><indexterm>
+	    <primary>share definition controls</primary>
+	  </indexterm>
+	Samba has been designed and implemented so that it respects as far as is feasible the security and
+	user privilege controls that are built into the UNIX/Linux operating system. Samba does nothing
+	with respect to file system access that violates file system permission settings, unless it is
+	explicitly instructed to do otherwise through share definition controls. Given that Samba obeys
+	UNIX file system controls, this chapter does not document simple information that can be obtained
+	from a basic UNIX training guide. Instead, one common example of a typical problem is used
+	to demonstrate the most effective solution referred to in the immediately preceding paragraph.
+	</para>
+
+	<para><indexterm>
+	    <primary>Microsoft Office</primary>
+	  </indexterm><indexterm>
+	    <primary>Word</primary>
+	  </indexterm><indexterm>
+	    <primary>Excel</primary>
+	  </indexterm>
+	One of the common issues that repeatedly pops up on the Samba mailing lists involves the saving of
+	Microsoft Office files (Word and Excel) to a network drive. Here is the typical sequence:
+	</para>
+
+	<orderedlist>
+		<listitem><para>
+		A user opens a Work document from a network drive. The file was owned by user <constant>janetp</constant>
+		and <group>users</group>, and was set read/write-enabled for everyone.
+		</para></listitem>
+
+		<listitem><para>
+		File changes and edits are made.
+		</para></listitem>
+
+		<listitem><para>
+		The file is saved, and MS Word is closed.
+		</para></listitem>
+
+		<listitem><para>
+		The file is now owned by the user <constant>billc</constant> and group <constant>doctors</constant>,
+		and is set read/write by <constant>billc</constant>, read-only by <constant>doctors</constant>, and
+		no access by everyone.
+		</para></listitem>
+
+		<listitem><para>
+		The original owner cannot now access her own file and is <quote>justifiably</quote> upset.
+		</para></listitem>
+	</orderedlist>
+
+	<para>
+	There have been many postings over the years that report the same basic problem. Frequently Samba users
+	want to know when this <quote>bug</quote> will be fixed. The fact is, this is not a bug in Samba at all.
+	Here is the real sequence of what happens in this case.
+	</para>
+
+	<para><indexterm>
+	    <primary>MS Word</primary>
+	  </indexterm><indexterm>
+	    <primary>ownership</primary>
+	  </indexterm><indexterm>
+	    <primary>permissions</primary>
+	  </indexterm>
+	When the user saves a file, MS Word creates a new (temporary) file. This file is naturally owned
+	by the user who creates the file (<constant>billc</constant>) and has the permissions that follow
+	that user's default settings within the operating system (UNIX/Linux). When MS Word has finished writing
+	the file to disk, it then renames the new (temporary) file to the name of the old one. MS Word does not
+	change the ownership or permissions to what they were on the original file. The file is thus a totally
+	new file, and the old one has been deleted in the process.
+	</para>
+
+	<para>
+	Samba received a request to create a new file, and then to rename the file to a new name. The old file that
+	has the same name is now automatically deleted. Samba has no way of knowing that the new file should
+	perhaps have the same ownership and permissions as the old file. To Samba, these are entirely independent
+	operations.
+	</para>
+
+	<para>
+	The question is, <quote>How can we solve the problem?</quote>
+	</para>
+
+	<para>
+	The solution is simple. Use UNIX file system permissions and controls to your advantage. Follow these
+	simple steps to create a share in which all files will consistently be owned by the same user and the
+	same group:
+	</para>
+
+
+	<procedure>
+	<title>Using Directory Permissions to Force File User and Group Ownership</title>
+		<step><para>
+		Change your share definition so that it matches this pattern:
+<screen>
+[finance]
+        path = /usr/data/finance
+        browseable = Yes
+        read only = No
+</screen>
+		</para></step>
+
+	  <step><para><indexterm>
+		<primary>permissions</primary>
+		<secondary>user</secondary>
+	      </indexterm><indexterm>
+		<primary>permissions</primary>
+		<secondary>group</secondary>
+	      </indexterm>
+		Set consistent user and group permissions recursively down the directory tree as shown here:
+<screen>
+&rootprompt; chown -R janetp.users /usr/data/finance
+</screen>
+		</para></step>
+
+	  <step><para><indexterm>
+		<primary>accessible</primary>
+	      </indexterm>
+		Set the files and directory permissions to be read/write for owner and group, and not accessible
+		to others (everyone), using the following command:
+<screen>
+&rootprompt; chmod ug+rwx,o-rwx /usr/data/finance
+</screen>
+		</para></step>
+
+	  <step><para><indexterm>
+		<primary>SGID</primary>
+	      </indexterm>
+		Set the SGID (supergroup) bit on all directories from the top down. This means all files 
+		can be created with the permissions of the group set on the directory. It means all users 
+		who are members of the group <constant>finance</constant> can read and write all files in 
+		the directory. The directory is not readable or writable by anyone who is not in the 
+		<constant>finance</constant> group. Simply follow this example:
+<screen>
+&rootprompt; find /usr/data/finance -type d -exec chmod ug+s {}\;
+</screen>
+
+		</para></step>
+
+	  <step><para><indexterm>
+		<primary>group membership</primary>
+	      </indexterm><indexterm>
+		<primary>primary group</primary>
+	      </indexterm><indexterm>
+		<primary>/etc/passwd</primary>
+	      </indexterm>
+		Make sure all users that must have read/write access to the directory have 
+		<constant>finance</constant> group membership as their primary group, 
+		for example, the group they belong to in <filename>/etc/passwd</filename>.
+		</para></step>
+	</procedure>
+
+	</sect2>
+
+	<sect2>
+	<title>Managing Windows 200x ACLs</title>
+
+	<para><indexterm>
+	    <primary>translate</primary>
+	  </indexterm><indexterm>
+	    <primary>Windows 2000 ACLs</primary>
+	  </indexterm><indexterm>
+	    <primary>Posix ACLs</primary>
+	  </indexterm><indexterm>
+	    <primary>side effects</primary>
+	  </indexterm>
+	Samba must translate Windows 2000 ACLs to UNIX POSIX ACLs. This has some interesting side effects because
+	there is not a one-to-one equivalence between them. The as-close-as-possible ACLs match means
+	that some transactions are not possible from MS Windows clients. One of these is to reset the ownership
+	of directories and files. If you want to reset ownership, this must be done from a UNIX/Linux login.
+	</para>
+
+	<para>
+	There are two possible ways to set ACLs on UNIX/Linux file systems from a Windows network workstation,
+	either via File Manager or via the Microsoft Management Console (MMC) Computer Management interface.
+	</para>
+
+	<sect3>
+	<title>Using the MMC Computer Management Interface</title>
+
+	<procedure>
+		<step><para>
+		From a Windows 200x/XP Professional workstation, log on to the domain using the Domain Administrator 
+		account (on Samba domains, this is usually the account called <constant>root</constant>).
+		</para></step>
+
+		<step><para>
+		Click 
+		<menuchoice>
+			<guimenu>Start</guimenu>
+			<guimenuitem>Settings</guimenuitem>
+			<guimenuitem>Control Panel</guimenuitem>
+			<guimenuitem>Administrative Tools</guimenuitem>
+			<guimenuitem>Computer Management</guimenuitem>
+		</menuchoice>.
+		</para></step>
+
+		<step><para>
+		In the left panel,
+		<menuchoice>
+			<guimenu>[Right mouse menu item] Computer Management (Local)</guimenu>
+			<guimenuitem>Connect to another computer ...</guimenuitem>
+			<guimenuitem>Browse...</guimenuitem>
+			<guimenuitem>Advanced</guimenuitem>
+			<guimenuitem>Find Now</guimenuitem>
+		</menuchoice>. In the lower panel, click on the name of the server you wish to
+		administer. Click <menuchoice>
+				<guimenu>OK</guimenu>
+				<guimenuitem>OK</guimenuitem>
+				<guimenuitem>OK</guimenuitem>
+		</menuchoice>.
+		In the left panel, the entry <guimenu>Computer Management (Local)</guimenu> should now reflect
+		the change made. For example, if the server you are administering is called <constant>FRODO</constant>,
+		the Computer Management entry should now say: <guimenu>Computer Management (FRODO)</guimenu>.
+		</para></step>
+
+		<step><para>
+		In the left panel, click <menuchoice>
+			<guimenu>Computer Management (FRODO)</guimenu>
+			<guimenuitem>[+] Shared Folders</guimenuitem>
+			<guimenuitem>Shares</guimenuitem>
+		</menuchoice>.
+		</para></step>
+
+	    <step><para><indexterm>
+		  <primary>Security</primary>
+		</indexterm><indexterm>
+		  <primary>Properties</primary>
+		</indexterm><indexterm>
+		  <primary>Permissions</primary>
+		</indexterm><indexterm>
+		  <primary>Samba Domain server</primary>
+		</indexterm>
+		In the right panel, double-click on the share on which you wish to set/edit ACLs. This
+		brings up the Properties panel. Click the <guimenu>Security</guimenu> tab. It is best
+		to edit ACLs using the <constant>Advanced</constant> editing features. Click the 
+		<guimenu>Advanced</guimenu> button. This opens a panel that has four tabs. Only the 
+		functionality under the <constant>Permissions</constant> tab can be utilized with respect 
+		to a Samba domain server.
+		</para></step>
+
+	    <step><para><indexterm>
+		  <primary>access control</primary>
+		</indexterm><indexterm>
+		  <primary>permitted group</primary>
+		</indexterm>
+		You may now edit/add/remove access control settings. Be very careful. Many problems have been
+		created by people who decided that everyone should be rejected but one particular group should
+		have full control. This is a catch-22 situation because members of that particular group also
+		belong to the group <constant>Everyone</constant>, which therefore overrules any permissions
+		set for the permitted group.
+		</para></step>
+
+		<step><para>
+		When you are done with editing, close all panels by clicking through the <guimenu>OK</guimenu>
+		buttons until the last panel closes.
+		</para></step>
+	</procedure>
+	
+	</sect3>
+
+	<sect3>
+	<title>Using MS Windows Explorer (File Manager)</title>
+
+	<para>
+	The following alternative method may be used from a Windows workstation. In this example we work
+	with a domain called <constant>MEGANET</constant>, a server called <constant>MASSIVE</constant>, and a
+	share called <constant>Apps</constant>. The underlying UNIX/Linux share point for this share is
+	<filename>/data/apps</filename>.
+	</para>
+
+	<procedure>
+		<step><para>
+		Click <menuchoice>
+			<guimenu>Start</guimenu>
+			<guimenuitem>[right-click] My Computer</guimenuitem>
+			<guimenuitem>Explore</guimenuitem>
+			<guimenuitem>[left panel] [+] My Network Places</guimenuitem>
+			<guimenuitem>[+] Entire Network</guimenuitem>
+			<guimenuitem>[+] Microsoft Windows Network</guimenuitem>
+			<guimenuitem>[+] Meganet</guimenuitem>
+			<guimenuitem>[+] Massive</guimenuitem>
+			<guimenuitem>[right-click] Apps</guimenuitem>
+			<guimenuitem>Properties</guimenuitem>
+			<guimenuitem>Security</guimenuitem>
+			<guimenuitem>Advanced</guimenuitem>
+		</menuchoice>. This opens a panel that has four tabs. Only the functionality under the 
+		<constant>Permissions</constant> tab can be utilized for a Samba domain server.
+		</para></step>
+
+	    <step><para><indexterm>
+		  <primary>full control</primary>
+		</indexterm><indexterm>
+		  <primary>over-rule</primary>
+		</indexterm>
+                You may now edit/add/remove access control settings. Be very careful. Many problems have been
+                created by people who decided that everyone should be rejected but one particular group should
+                have full control. This is a catch-22 situation because members of that particular group also
+                belong to the group <constant>Everyone</constant>, which therefore overrules any permissions
+                set for the permitted group.
+                </para></step>
+
+                <step><para>
+                When you are done with editing, close all panels by clicking through the <guimenu>OK</guimenu>
+                buttons until the last panel closes.
+                </para></step>
+	</procedure>
+
+	</sect3>
+
+	<sect3>
+	<title>Setting Posix ACLs in UNIX/Linux</title>
+
+	  <para><indexterm>
+	      <primary>desired security setting</primary>
+	    </indexterm><indexterm>
+	      <primary>shared resource</primary>
+	    </indexterm>
+	Yet another alternative method for setting desired security settings on the shared resource files and
+	directories can be achieved by logging into UNIX/Linux and setting POSIX ACLs directly using command-line
+	tools. Here is an example session on the same resource as in the immediately preceding example on a SUSE 9
+	Linux system:
+	</para>
+
+	<procedure>
+		<step><para>
+		Log into the Linux system as the user <constant>root</constant>.
+		</para></step>
+
+		<step><para>
+		Change directory to the location of the exported (shared) Windows file share (Apps), which is in
+		the directory <filename>/data</filename>. Execute the following:
+<screen>
+&rootprompt; cd /data
+</screen>
+		Retrieve the existing POSIX ACLs entry by executing:
+<screen>
+&rootprompt; getfacl apps
+# file: apps
+# owner: root
+# group: root
+user::rwx
+group::rwx
+other::r-x
+</screen>
+		</para></step>
+
+	    <step><para><indexterm>
+		  <primary>recursively</primary>
+		</indexterm>
+		You want to add permission for <constant>AppsMgrs</constant> to enable them to
+		manage the applications (apps) share. It is important to set the ACL recursively
+		so that the AppsMgrs have this capability throughout the directory tree that is 
+		being shared. This is done using the <constant>-R</constant> option as shown.
+		Execute the following:
+<screen>
+&rootprompt; setfacl -m -R group:AppsMgrs:rwx /data/apps
+</screen>
+		Because setting an ACL does not provide a response, you immediately validate the command executed
+		as follows:
+<screen>
+&rootprompt; getfacl /data/apps
+# file: apps
+# owner: root
+# group: root
+user::rwx
+group::rwx
+group:AppsMgrs:rwx
+mask::rwx
+other::r-x
+</screen>
+		This confirms that the change of POSIX ACL permissions has been effective.
+		</para></step>
+
+	    <step><para><indexterm>
+		  <primary>setfacl</primary>
+		</indexterm><indexterm>
+		  <primary>getfacl</primary>
+		</indexterm><indexterm>
+		  <primary>directory tree</primary>
+		</indexterm><indexterm>
+		  <primary>Windows ACLs</primary>
+		</indexterm><indexterm>
+		  <primary>inheritance</primary>
+		</indexterm>
+		It is highly recommended that you read the online manual page for the <command>setfacl</command>
+		and <command>getfacl</command> commands. This provides information regarding how to set/read the default
+		ACLs and how that may be propagated through the directory tree. In Windows ACLs terms, this is the equivalent
+		of setting <constant>inheritance</constant> properties.
+		</para></step>
+	</procedure>
+
+	</sect3>
+
+	</sect2>
+
+	<sect2>
+		<title>Key Points Learned</title>
+
+		<para>
+		The mish-mash of issues were thrown together into one chapter because it seemed like a good idea.
+		Looking back, this chapter could be broken into two, but it's too late now. It has been done.
+		The highlights covered are as follows:
+		</para>
+
+		<itemizedlist>
+	  <listitem><para><indexterm>
+		<primary>Winbind</primary>
+	      </indexterm><indexterm>
+		<primary>Active Directory</primary>
+	      </indexterm><indexterm>
+		<primary>password change</primary>
+	      </indexterm><indexterm>
+		<primary>logon hours</primary>
+	      </indexterm>
+			Winbind honors and does not override account controls set in Active Directory.
+			This means that password change, logon hours, and so on, are (or soon will be) enforced
+			by Samba winbind. At this time, an out-of-hours login is denied and password
+			change is enforced. At this time, if logon hours expire, the user is not forcibly
+			logged off. That may be implemented at some later date.
+			</para></listitem>
+
+	  <listitem><para><indexterm>
+		<primary>Sign'n'seal</primary>
+	      </indexterm><indexterm>
+		<primary>schannel</primary>
+	      </indexterm>
+			Sign'n'seal (plus schannel support) has been implemented in Samba-3. Beware of potential
+			problems acknowledged by Microsoft as having been fixed but reported by some as still
+			possibly an open issue.
+			</para></listitem>
+
+	  <listitem><para><indexterm>
+		<primary>Kerberos</primary>
+	      </indexterm><indexterm>
+		<primary>OpenLDAP</primary>
+	      </indexterm><indexterm>
+		<primary>Active Directory</primary>
+	      </indexterm><indexterm>
+		<primary>inter-operability</primary>
+	      </indexterm>
+			The combination of Kerberos 5, plus OpenLDAP, plus Samba, cannot replace Microsoft
+			Active Directory. The possibility to do this is not planned in the current Samba-3
+			roadmap. Samba-3 does aim to provide further improvements in interoperability so that
+			UNIX/Linux systems may be fully integrated into Active Directory domains.
+			</para></listitem>
+
+			<listitem><para>
+			This chapter reviewed mechanisms by which Samba servers may be kept secure. Each of
+			the four key methodologies was reviewed with specific reference to example deployment
+			techniques.
+			</para></listitem>
+		</itemizedlist>
+
+	</sect2>
+
+</sect1>
+
+<sect1>
+	<title>Questions and Answers</title>
+
+	<para>
+	</para>
+
+	<qandaset defaultlabel="chap10qa" type="number">
+	<qandaentry>
+	<question>
+
+	    <para><indexterm>
+		<primary>Sign'n'seal</primary>
+	      </indexterm><indexterm>
+		<primary>registry hacks</primary>
+	      </indexterm>
+		Does Samba-3 require the <constant>Sign'n'seal</constant> registry hacks needed by Samba-2?
+		</para>
+
+	</question>
+	<answer>
+
+	    <para><indexterm>
+		<primary>schannel</primary>
+	      </indexterm><indexterm>
+		<primary>Sign'n'seal</primary>
+	      </indexterm><indexterm>
+		<primary>registry change</primary>
+	      </indexterm>
+		No. Samba-3 fully supports <constant>Sign'n'seal</constant> as well as <constant>schannel</constant>
+		operation. The registry change should not be applied when Samba-3 is used as a domain controller.
+		</para>
+
+	</answer>
+	</qandaentry>
+
+	<qandaentry>
+	<question>
+
+		<para>
+		Does Samba-3 support Active Directory?
+		</para>
+
+	</question>
+	<answer>
+
+	    <para><indexterm>
+		<primary>Active Directory</primary>
+	      </indexterm>
+		Yes. Samba-3 can be a fully participating native mode Active Directory client. Samba-3 does not
+		provide Active Directory services. It cannot be used to replace a Microsoft Active Directory
+		server implementation. Samba-3 can function as an Active Directory client (workstation) toolkit,
+		and it can function as an Active Directory domain member server.
+		</para>
+
+	</answer>
+	</qandaentry>
+
+	<qandaentry>
+	<question>
+
+	    <para><indexterm>
+		<primary>mixed-mode</primary>
+	      </indexterm>
+		When Samba-3 is used with Active Directory, is it necessary to run mixed-mode operation, as was
+		necessary with Samba-2?
+		</para>
+
+	</question>
+	<answer>
+
+	    <para><indexterm>
+		<primary>native</primary>
+	      </indexterm>
+		No. Samba-3 can be used with NetBIOS over TCP/IP disabled, just as can be done with Windows 200x
+		Server and 200x/XPPro client products. It is no longer necessary to run mixed-mode operation,
+		because Samba-3 can join a native Windows 2003 Server ADS domain.
+		</para>
+
+	</answer>
+	</qandaentry>
+
+	<qandaentry>
+	<question>
+
+	    <para><indexterm>
+		<primary>share level access controls</primary>
+	      </indexterm>
+		Is it safe to set share-level access controls in Samba?
+		</para>
+
+	</question>
+	<answer>
+
+		<para>
+		Yes. Share-level access controls have been supported since early versions of Samba-2. This is
+		very mature technology. Not enough sites make use of this powerful capability, neither on
+		Windows server or with Samba servers.
+		</para>
+
+	</answer>
+	</qandaentry>
+
+	<qandaentry>
+	<question>
+
+	    <para><indexterm>
+		<primary>share ACLs</primary>
+	      </indexterm>
+		Is it mandatory to set share ACLs to get a secure Samba-3 server?
+		</para>
+
+	</question>
+	<answer>
+
+	    <para><indexterm>
+		<primary>file system security</primary>
+	      </indexterm><indexterm>
+		<primary>Windows 200x ACLs</primary>
+	      </indexterm><indexterm>
+		<primary>share definition controls</primary>
+	      </indexterm><indexterm>
+		<primary>share level ACL</primary>
+	      </indexterm><indexterm>
+		<primary>security</primary>
+	      </indexterm>
+		No. Samba-3 honors UNIX/Linux file system security, supports Windows 200x ACLs, and provides 
+		means of securing shares through share definition controls in the &smb.conf; file. The additional
+		support for share-level ACLs is like frosting on the cake. It adds to security but is not essential
+		to it.
+		</para>
+
+	</answer>
+	</qandaentry>
+
+	<qandaentry>
+	<question>
+
+	    <para><indexterm>
+		<primary>valid users</primary>
+	      </indexterm>
+		The <parameter>valid users</parameter> did not work on the <smbconfsection name="[homes]"/>.
+		Has this functionality been restored yet?
+		</para>
+
+	</question>
+	<answer>
+
+	    <para><indexterm>
+		<primary>meta-service</primary>
+	      </indexterm>
+		Yes. This was fixed in Samba-3.0.2. The use of this parameter is strongly recommended as a safeguard
+		on the <smbconfsection name="[homes]"/> meta-service. The correct way to specify this is:
+		<smbconfoption name="valid users">%S</smbconfoption>.
+		</para>
+
+	</answer>
+	</qandaentry>
+
+	<qandaentry>
+	<question>
+
+	    <para><indexterm>
+		<primary>force user</primary>
+	      </indexterm><indexterm>
+		<primary>force group</primary>
+	      </indexterm><indexterm>
+		<primary>bias</primary>
+	      </indexterm>
+		Is the bias against use of the <parameter>force user</parameter> and <parameter>force group</parameter>
+		really warranted?
+		</para>
+
+	</question>
+	<answer>
+
+	    <para><indexterm>
+		<primary>performance</primary>
+	      </indexterm>
+		There is no bias. There is a determination to recommend the right tool for the task at hand.
+		After all, it is better than putting users through performance problems, isn't it?
+		</para>
+
+	</answer>
+	</qandaentry>
+
+	<qandaentry>
+	<question>
+
+		<para>
+		The example given for file and directory access control forces all files to be owned by one
+		particular user. I do not like that. Is there any way I can see who created the file?
+		</para>
+
+	</question>
+	<answer>
+
+	    <para><indexterm>
+		<primary>SUID</primary>
+	      </indexterm>
+		Sure. You do not have to set the SUID bit on the directory. Simply execute the following command
+		to permit file ownership to be retained by the user who created it:
+<screen>
+&rootprompt; find /usr/data/finance -type d -exec chmod g+s {}\;
+</screen>
+		Note that this required no more than removing the <constant>u</constant> argument so that the
+		SUID bit is not set for the owner.
+		</para>
+
+	</answer>
+	</qandaentry>
+
+	<qandaentry>
+	<question>
+
+	    <para><indexterm>
+		<primary>Computer Management</primary>
+	      </indexterm>
+		In the book, <quote>The Official Samba-3 HOWTO and Reference Guide</quote>, you recommended use
+		of the Windows NT4 Server Manager (part of the <filename>SRVTOOLS.EXE</filename>) utility. Why
+		have you mentioned only the use of the Windows 200x/XP MMC Computer Management utility?
+		</para>
+
+	</question>
+	<answer>
+
+	    <para><indexterm>
+		<primary>MMC</primary>
+	      </indexterm><indexterm>
+		<primary>SRVTOOLS.EXE</primary>
+	      </indexterm>
+		Either tool can be used with equal effect. There is no benefit of one over the other, except that
+		the MMC utility is present on all Windows 200x/XP systems and does not require additional software
+		to be downloaded and installed. Note that if you want to manage user and group accounts in your
+		Samba-controlled domain, the only tool that permits that is the NT4 Domain User Manager, which
+		is provided as part of the <filename>SRVTOOLS.EXE</filename> utility.
+		</para>
+
+	</answer>
+	</qandaentry>
+
+	<qandaentry>
+	<question>
+
+	    <para><indexterm>
+		<primary>valid users</primary>
+	      </indexterm><indexterm>
+		<primary>Active Directory</primary>
+	      </indexterm><indexterm>
+		<primary>Domain Member server</primary>
+	      </indexterm>
+		I tried to set <parameter>valid users = @Engineers</parameter>, but it does not work. My Samba
+		server is an Active Directory domain member server. Has this been fixed now?
+		</para>
+
+	</question>
+	<answer>
+
+		<para>
+		The use of this parameter has always required the full specification of the domain account, for
+		example, <parameter>valid users = @"MEGANET2\Domain Admins"</parameter>.
+		</para>
+
+	</answer>
+	</qandaentry>
+
+	</qandaset>
+
+</sect1>
+
+</chapter>
+