path: root/docs-xml/Samba3-ByExample/SBE-Appendix2.xml

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<!DOCTYPE chapter PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
<chapter id="primer">
  <title>Networking Primer</title>

	<para>
	You are about to use the equivalent of a microscope to look at the information
	that runs through the veins of a Windows network. We do more to observe the information than
	to interrogate it. When you are done with this primer, you should have a good understanding
	of the types of information that flow over the network. Do not worry, this is not
	a biology lesson. We won't lose you in unnecessary detail. Think to yourself, <quote>This
	is easy,</quote> then tackle each exercise without fear.
	</para>

	<para>
	Samba can be configured with a minimum of complexity. Simplicity should be mastered
	before you get too deeply into complexities. Let's get moving: we have work to do.
	</para>

<sect1>
	<title>Requirements and Notes</title>
	<para>
	Successful completion of this primer requires two Microsoft Windows 9x/Me Workstations
	as well as two Microsoft Windows XP Professional Workstations, each equipped with an Ethernet
	card connected using a hub. Also required is one additional server (either Windows
	NT4 Server, Windows 2000 Server, or a Samba on UNIX/Linux server) running a network
	sniffer and analysis application (Wireshark is a good choice). All work should be undertaken
	on a quiet network where there is no other traffic. It is best to use a dedicated hub
	with only the machines under test connected at the time of the exercises.
	</para>

      <para><indexterm>
	  <primary>Wireshark</primary>
	</indexterm>
	Wireshark (formerly Ethereal) has become the network protocol analyzer of choice for many network administrators.
	You may find more information regarding this tool from the
	<ulink url="http://www.wireshark.org">Wireshark</ulink> Web site. Wireshark installation
	files for Windows may be obtained from the Wireshark Web site. Wireshark is provided with
	SUSE and Red Hat Linux distributions, as well as with many other Linux distributions. It may
	not be installed on your system by default. If it is not installed, you may also need
	to install the <command>libpcap</command> software before you can install or use Wireshark.
	Please refer to the instructions for your operating system or to the Wireshark Web site
	for information regarding the installation and operation of Wireshark.
	</para>

	<para>
	To obtain <command>Wireshark</command> for your system, please visit the Wireshark
	<ulink url="http://www.wireshark.org/download.html">download site</ulink>.
	</para>

	<note><para>
	The successful completion of this chapter requires that you capture network traffic
	using <command>Wireshark</command>. It is recommended that you use a hub, not an
	Ethernet switch. It is necessary for the device used to act as a repeater, not as a
	filter. Ethernet switches may filter out traffic that is not directed at the machine
	that is used to monitor traffic; this would not allow you to complete the projects.
	</para></note>

	<para>
	<indexterm><primary>network</primary><secondary>captures</secondary></indexterm>
	Do not worry too much if you do not have access to all this equipment; network captures
	from the exercises are provided on the enclosed CD-ROM. This makes it possible to dive directly
	into the analytical part of the exercises if you so desire.
	</para>

      <para><indexterm>
	  <primary>network</primary>
	  <secondary>sniffer</secondary>
	</indexterm><indexterm>
	  <primary>protocol analysis</primary>
	</indexterm>
	Please do not be alarmed at the use of a high-powered analysis tool (Wireshark) in this
	primer.  We expose you only to a minimum of detail necessary to complete
	the exercises. If you choose to use any other network sniffer and protocol
	analysis tool, be advised that it may not allow you to examine the contents of
	recently added security protocols used by Windows 200x/XP.
	</para>

	<para>
	You could just skim through the exercises and try to absorb the key points made.
	The exercises provide all the information necessary to convince the die-hard network
	engineer. You possibly do not require so much convincing and may just want to move on,
	in which case you should at least read <link linkend="chap01conc"/>.
	</para>

	<para>
	<link linkend="chap01qa"/> also provides useful information
	that may help you to avoid significantly time-consuming networking problems.
	</para>
</sect1>

<sect1>
	<title>Introduction</title>

	<para>
	The purpose of this chapter is to create familiarity with key aspects of Microsoft Windows
	network computing. If you want a solid technical grounding, do not gloss over these exercises.
	The points covered are recurrent issues on the Samba mailing lists.
	</para>

      <para><indexterm>
	  <primary>network</primary>
	  <secondary>broadcast</secondary>
	</indexterm>
	You can see from these exercises that Windows networking involves quite a lot of network
	broadcast traffic. You can look into the contents of some packets, but only to see
	some particular information that the Windows client sends to a server in the course of
	establishing a network connection.
	</para>

	<para>
	To many people, browsing is everything that happens when one uses Microsoft Internet Explorer.
	It is only when you start looking at network traffic and noting the protocols
	and types of information that are used that you can begin to appreciate the complexities of
	Windows networking and, more importantly, what needs to be configured so that it can work.
	Detailed information regarding browsing is provided in the recommended
	preparatory reading.
	</para>

	<para>
	Recommended preparatory reading: <emphasis>The Official Samba HOWTO and Reference Guide, Second
	Edition</emphasis> (TOSHARG2) Chapter 9, <quote>Network Browsing,</quote> and Chapter 3,
	<quote>Server Types and Security Modes.</quote>
	</para>

	<sect2>
	<title>Assignment Tasks</title>

	<para><indexterm>
	    <primary>browsing</primary>
	  </indexterm>
		You are about to witness how Microsoft Windows computer networking functions. The
		exercises step through identification of how a client machine establishes a
		connection to a remote Windows server. You observe how Windows machines find
		each other (i.e., how browsing works) and how the two key types of user identification
		(share mode security and user mode security) are affected.
		</para>

	<para><indexterm>
	    <primary>network</primary>
	    <secondary>analyzer</secondary>
	  </indexterm>
		The networking protocols used by MS Windows networking when working with Samba
		use TCP/IP as the transport protocol. The protocols that are specific to Windows
		networking are encapsulated in TCP/IP. The network analyzer we use (Wireshark)
		is able to show you the contents of the TCP/IP packets (or messages).
		</para>

		<procedure id="chap01tasks">
		<title>Diagnostic Tasks</title>

	  <step><para><indexterm>
		<primary>network</primary>
		<secondary>trace</secondary>
	      </indexterm><indexterm>
		<primary>host announcement</primary>
	      </indexterm><indexterm>
		<primary>name resolution</primary>
	      </indexterm>
			Examine network traces to witness SMB broadcasts, host announcements,
			and name resolution processes.
			</para></step>

			<step><para>
			Examine network traces to witness how share mode security functions.
			</para></step>

			<step><para>
			Examine network traces to witness the use of user mode security.
			</para></step>

			<step><para>
			Review traces of network logons for a Windows 9x/Me client as well as
			a domain logon for a Windows XP Professional client.
			</para></step>
		</procedure>

	</sect2>
</sect1>

<sect1>
	<title>Exercises</title>

	<para>
	<indexterm><primary>wireshark</primary></indexterm>
	You are embarking on a course of discovery. The first part of the exercise requires
	two MS Windows 9x/Me systems. We called one machine <constant>WINEPRESSME</constant> and the
	other <constant>MILGATE98</constant>. Each needs an IP address; we used <literal>10.1.1.10</literal>
	and <literal>10.1.1.11</literal>. The test machines need to be networked via a <emphasis>hub</emphasis>. A UNIX/Linux
	machine is required to run <command>Wireshark</command> to enable the network activity to be captured.
	It is important that the machine from which network activity is captured must not interfere with
	the operation of the Windows workstations. It is helpful for this machine to be passive (does not
	send broadcast information) to the network.
	</para>

	<para>
	For these exercises, our test environment consisted of a SUSE 9.2 Professional Linux Workstation running
	VMWare 4.5. The following VMWare images were prepared:
	</para>

	<itemizedlist>
		<listitem><para>Windows 98 &smbmdash; name: MILGATE98</para></listitem>
		<listitem><para>Windows Me &smbmdash; name: WINEPRESSME</para></listitem>
		<listitem><para>Windows XP Professional &smbmdash; name: LightrayXP</para></listitem>
		<listitem><para>Samba-3.0.20 running on a SUSE Enterprise Linux 9</para></listitem>
	</itemizedlist>

	<para>
	Choose a workgroup name (MIDEARTH) for each exercise.
	</para>

	<para>
	<indexterm><primary>ethereal</primary></indexterm>
	The network captures provided on the CD-ROM included with this book were captured using <constant>Ethereal</constant>
	version <literal>0.10.6</literal>. A later version suffices without problems (i.e. you should be using Wireshark), but an earlier version may not
	expose all the information needed. Each capture file has been decoded and listed as a trace file. A summary of all
	packets has also been included. This makes it possible for you to do all the studying you like without the need to
	perform the time-consuming equipment configuration and test work. This is a good time to point out that the value
	that can be derived from this book really does warrant your taking sufficient time to practice each exercise with
	care and attention to detail.
	</para>

	<sect2>
	<title>Single-Machine Broadcast Activity</title>

	<para>
	In this section, we start a single Windows 9x/Me machine, then monitor network activity for 30 minutes.
	</para>

	<procedure>
	<title>Monitoring Windows 9x Steps</title>

		<step><para>
		Start the machine from which network activity will be monitored (using <command>Wireshark</command>).
		Launch <command>Wireshark</command>, click
			<menuchoice>
				<guimenu>Capture</guimenu>
				<guimenuitem>Start</guimenuitem>
			</menuchoice>.
		</para>

		<para>
		Click the following:
		<orderedlist>
		<listitem><para>Update list of packets in real time</para></listitem>
		<listitem><para>Automatic scrolling in live capture</para></listitem>
		<listitem><para>Enable MAC name resolution</para></listitem>
		<listitem><para>Enable network name resolution</para></listitem>
		<listitem><para>Enable transport name resolution</para></listitem>
		</orderedlist>
		Click <guibutton>OK</guibutton>.
		</para></step>

		<step><para>
		Start the Windows 9x/Me machine to be monitored. Let it run for a full 30 minutes. While monitoring,
		do not press any keyboard keys, do not click any on-screen icons or menus, and do not answer any dialog boxes.
		</para></step>

		<step><para>
		At the conclusion of 30 minutes, stop the capture. Save the capture to a file so you can go back to it later.
		Leave this machine running in preparation for the task in <link linkend="secondmachine"/>.
		</para></step>

		<step><para>
		Analyze the capture. Identify each discrete message type that was captured. Note what transport protocol
		was used. Identify the timing between messages of identical types.
		</para></step>

	</procedure>

		<sect3>
		<title>Findings</title>

		<para>
		The summary of the first 10 minutes of the packet capture should look like <link linkend="pktcap01"/>.
		A screenshot of a later stage of the same capture is shown in <link linkend="pktcap02"/>.
		</para>

		<figure id="pktcap01">
			<title>Windows Me &smbmdash; Broadcasts &smbmdash; The First 10 Minutes</title>
			<imagefile scale="40">WINREPRESSME-Capture</imagefile>
		</figure>

		<figure id="pktcap02">
			<title>Windows Me &smbmdash; Later Broadcast Sample</title>
			<imagefile scale="42">WINREPRESSME-Capture2</imagefile>
		</figure>

	  <para><indexterm>
	      <primary>Local Master Browser</primary>
	      <see>LMB</see>
	    </indexterm><indexterm>
	      <primary>LMB</primary>
	    </indexterm>
		Broadcast messages observed are shown in <link linkend="capsstats01"/>.
		Actual observations vary a little, but not by much.
		Early in the startup process, the Windows Me machine broadcasts its name for two reasons:
		first to ensure that its name would not result in a name clash, and second to establish its
		presence with the Local Master Browser (LMB).
		</para>

		<table id="capsstats01">
			<title>Windows Me &smbmdash; Startup Broadcast Capture Statistics</title>
			<tgroup cols="4">
				<colspec align="left" colwidth="3*"/>
				<colspec align="center"/>
				<colspec align="center"/>
				<colspec align="left" colwidth="3*"/>
				<thead>
					<row>
						<entry>Message</entry>
						<entry>Type</entry>
						<entry>Num</entry>
						<entry>Notes</entry>
					</row>
				</thead>
				<tbody>