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1284 lines
50 KiB
XML
<?xml version="1.0" encoding="iso-8859-1"?>
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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">
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<chapter id="primer">
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<title>Networking Primer</title>
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<para>
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You are about to use the equivalent of a microscope to look at the information
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that runs through the veins of a Windows network. We do more to observe the information than
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to interrogate it. When you are done with this primer, you should have a good understanding
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of the types of information that flow over the network. Do not worry, this is not
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a biology lesson. We won't lose you in unnecessary detail. Think to yourself, <quote>This
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is easy,</quote> then tackle each exercise without fear.
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</para>
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<para>
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Samba can be configured with a minimum of complexity. Simplicity should be mastered
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before you get too deeply into complexities. Let's get moving: we have work to do.
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</para>
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<sect1>
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<title>Requirements and Notes</title>
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<para>
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Successful completion of this primer requires two Microsoft Windows 9x/Me Workstations
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as well as two Microsoft Windows XP Professional Workstations, each equipped with an Ethernet
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card connected using a hub. Also required is one additional server (either Windows
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NT4 Server, Windows 2000 Server, or a Samba-3 on UNIX/Linux server) running a network
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sniffer and analysis application (Wireshark is a good choice). All work should be undertaken
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on a quiet network where there is no other traffic. It is best to use a dedicated hub
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with only the machines under test connected at the time of the exercises.
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</para>
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<para><indexterm>
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<primary>Wireshark</primary>
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</indexterm>
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Wireshark (formerly Ethereal) has become the network protocol analyzer of choice for many network administrators.
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You may find more information regarding this tool from the
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<ulink url="http://www.wireshark.org">Wireshark</ulink> Web site. Wireshark installation
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files for Windows may be obtained from the Wireshark Web site. Wireshark is provided with
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SUSE and Red Hat Linux distributions, as well as with many other Linux distributions. It may
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not be installed on your system by default. If it is not installed, you may also need
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to install the <command>libpcap</command> software before you can install or use Wireshark.
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Please refer to the instructions for your operating system or to the Wireshark Web site
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for information regarding the installation and operation of Wireshark.
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</para>
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<para>
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To obtain <command>Wireshark</command> for your system, please visit the Wireshark
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<ulink url="http://www.wireshark.org/download.html">download site</ulink>.
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</para>
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<note><para>
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The successful completion of this chapter requires that you capture network traffic
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using <command>Wireshark</command>. It is recommended that you use a hub, not an
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Ethernet switch. It is necessary for the device used to act as a repeater, not as a
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filter. Ethernet switches may filter out traffic that is not directed at the machine
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that is used to monitor traffic; this would not allow you to complete the projects.
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</para></note>
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<para>
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<indexterm><primary>network</primary><secondary>captures</secondary></indexterm>
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Do not worry too much if you do not have access to all this equipment; network captures
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from the exercises are provided on the enclosed CD-ROM. This makes it possible to dive directly
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into the analytical part of the exercises if you so desire.
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</para>
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<para><indexterm>
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<primary>network</primary>
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<secondary>sniffer</secondary>
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</indexterm><indexterm>
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<primary>protocol analysis</primary>
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</indexterm>
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Please do not be alarmed at the use of a high-powered analysis tool (Wireshark) in this
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primer. We expose you only to a minimum of detail necessary to complete
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the exercises. If you choose to use any other network sniffer and protocol
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analysis tool, be advised that it may not allow you to examine the contents of
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recently added security protocols used by Windows 200x/XP.
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</para>
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<para>
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You could just skim through the exercises and try to absorb the key points made.
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The exercises provide all the information necessary to convince the die-hard network
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engineer. You possibly do not require so much convincing and may just want to move on,
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in which case you should at least read <link linkend="chap01conc"/>.
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</para>
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<para>
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<link linkend="chap01qa"/> also provides useful information
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that may help you to avoid significantly time-consuming networking problems.
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</para>
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</sect1>
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<sect1>
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<title>Introduction</title>
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<para>
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The purpose of this chapter is to create familiarity with key aspects of Microsoft Windows
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network computing. If you want a solid technical grounding, do not gloss over these exercises.
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The points covered are recurrent issues on the Samba mailing lists.
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</para>
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<para><indexterm>
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<primary>network</primary>
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<secondary>broadcast</secondary>
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</indexterm>
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You can see from these exercises that Windows networking involves quite a lot of network
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broadcast traffic. You can look into the contents of some packets, but only to see
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some particular information that the Windows client sends to a server in the course of
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establishing a network connection.
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</para>
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<para>
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To many people, browsing is everything that happens when one uses Microsoft Internet Explorer.
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It is only when you start looking at network traffic and noting the protocols
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and types of information that are used that you can begin to appreciate the complexities of
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Windows networking and, more importantly, what needs to be configured so that it can work.
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Detailed information regarding browsing is provided in the recommended
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preparatory reading.
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</para>
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<para>
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Recommended preparatory reading: <emphasis>The Official Samba-3 HOWTO and Reference Guide, Second
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Edition</emphasis> (TOSHARG2) Chapter 9, <quote>Network Browsing,</quote> and Chapter 3,
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<quote>Server Types and Security Modes.</quote>
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</para>
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<sect2>
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<title>Assignment Tasks</title>
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<para><indexterm>
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<primary>browsing</primary>
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</indexterm>
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You are about to witness how Microsoft Windows computer networking functions. The
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exercises step through identification of how a client machine establishes a
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connection to a remote Windows server. You observe how Windows machines find
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each other (i.e., how browsing works) and how the two key types of user identification
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(share mode security and user mode security) are affected.
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</para>
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<para><indexterm>
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<primary>network</primary>
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<secondary>analyzer</secondary>
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</indexterm>
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The networking protocols used by MS Windows networking when working with Samba
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use TCP/IP as the transport protocol. The protocols that are specific to Windows
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networking are encapsulated in TCP/IP. The network analyzer we use (Wireshark)
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is able to show you the contents of the TCP/IP packets (or messages).
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</para>
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<procedure id="chap01tasks">
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<title>Diagnostic Tasks</title>
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<step><para><indexterm>
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<primary>network</primary>
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<secondary>trace</secondary>
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</indexterm><indexterm>
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<primary>host announcement</primary>
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</indexterm><indexterm>
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<primary>name resolution</primary>
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</indexterm>
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Examine network traces to witness SMB broadcasts, host announcements,
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and name resolution processes.
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</para></step>
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<step><para>
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Examine network traces to witness how share mode security functions.
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</para></step>
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<step><para>
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Examine network traces to witness the use of user mode security.
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</para></step>
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<step><para>
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Review traces of network logons for a Windows 9x/Me client as well as
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a domain logon for a Windows XP Professional client.
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</para></step>
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</procedure>
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</sect2>
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</sect1>
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<sect1>
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<title>Exercises</title>
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<para>
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<indexterm><primary>wireshark</primary></indexterm>
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You are embarking on a course of discovery. The first part of the exercise requires
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two MS Windows 9x/Me systems. We called one machine <constant>WINEPRESSME</constant> and the
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other <constant>MILGATE98</constant>. Each needs an IP address; we used <literal>10.1.1.10</literal>
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and <literal>10.1.1.11</literal>. The test machines need to be networked via a <emphasis>hub</emphasis>. A UNIX/Linux
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machine is required to run <command>Wireshark</command> to enable the network activity to be captured.
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It is important that the machine from which network activity is captured must not interfere with
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the operation of the Windows workstations. It is helpful for this machine to be passive (does not
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send broadcast information) to the network.
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</para>
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<para>
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For these exercises, our test environment consisted of a SUSE 9.2 Professional Linux Workstation running
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VMWare 4.5. The following VMWare images were prepared:
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</para>
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<itemizedlist>
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<listitem><para>Windows 98 &smbmdash; name: MILGATE98</para></listitem>
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<listitem><para>Windows Me &smbmdash; name: WINEPRESSME</para></listitem>
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<listitem><para>Windows XP Professional &smbmdash; name: LightrayXP</para></listitem>
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<listitem><para>Samba-3.0.20 running on a SUSE Enterprise Linux 9</para></listitem>
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</itemizedlist>
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<para>
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Choose a workgroup name (MIDEARTH) for each exercise.
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</para>
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<para>
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<indexterm><primary>ethereal</primary></indexterm>
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The network captures provided on the CD-ROM included with this book were captured using <constant>Ethereal</constant>
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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
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expose all the information needed. Each capture file has been decoded and listed as a trace file. A summary of all
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packets has also been included. This makes it possible for you to do all the studying you like without the need to
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perform the time-consuming equipment configuration and test work. This is a good time to point out that the value
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that can be derived from this book really does warrant your taking sufficient time to practice each exercise with
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care and attention to detail.
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</para>
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<sect2>
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<title>Single-Machine Broadcast Activity</title>
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<para>
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In this section, we start a single Windows 9x/Me machine, then monitor network activity for 30 minutes.
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</para>
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<procedure>
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<title>Monitoring Windows 9x Steps</title>
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<step><para>
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Start the machine from which network activity will be monitored (using <command>Wireshark</command>).
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Launch <command>Wireshark</command>, click
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<menuchoice>
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<guimenu>Capture</guimenu>
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<guimenuitem>Start</guimenuitem>
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</menuchoice>.
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</para>
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<para>
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Click the following:
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<orderedlist>
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<listitem><para>Update list of packets in real time</para></listitem>
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<listitem><para>Automatic scrolling in live capture</para></listitem>
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<listitem><para>Enable MAC name resolution</para></listitem>
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<listitem><para>Enable network name resolution</para></listitem>
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<listitem><para>Enable transport name resolution</para></listitem>
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</orderedlist>
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Click <guibutton>OK</guibutton>.
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</para></step>
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<step><para>
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Start the Windows 9x/Me machine to be monitored. Let it run for a full 30 minutes. While monitoring,
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do not press any keyboard keys, do not click any on-screen icons or menus, and do not answer any dialog boxes.
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</para></step>
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<step><para>
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At the conclusion of 30 minutes, stop the capture. Save the capture to a file so you can go back to it later.
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Leave this machine running in preparation for the task in <link linkend="secondmachine"/>.
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</para></step>
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<step><para>
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Analyze the capture. Identify each discrete message type that was captured. Note what transport protocol
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was used. Identify the timing between messages of identical types.
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</para></step>
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</procedure>
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<sect3>
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<title>Findings</title>
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<para>
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The summary of the first 10 minutes of the packet capture should look like <link linkend="pktcap01"/>.
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A screenshot of a later stage of the same capture is shown in <link linkend="pktcap02"/>.
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</para>
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<figure id="pktcap01">
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<title>Windows Me &smbmdash; Broadcasts &smbmdash; The First 10 Minutes</title>
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<imagefile scale="40">WINREPRESSME-Capture</imagefile>
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</figure>
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<figure id="pktcap02">
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<title>Windows Me &smbmdash; Later Broadcast Sample</title>
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<imagefile scale="42">WINREPRESSME-Capture2</imagefile>
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</figure>
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<para><indexterm>
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<primary>Local Master Browser</primary>
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<see>LMB</see>
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</indexterm><indexterm>
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<primary>LMB</primary>
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</indexterm>
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Broadcast messages observed are shown in <link linkend="capsstats01"/>.
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Actual observations vary a little, but not by much.
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Early in the startup process, the Windows Me machine broadcasts its name for two reasons:
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first to ensure that its name would not result in a name clash, and second to establish its
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presence with the Local Master Browser (LMB).
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</para>
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<table id="capsstats01">
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<title>Windows Me &smbmdash; Startup Broadcast Capture Statistics</title>
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<tgroup cols="4">
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<colspec align="left" colwidth="3*"/>
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<colspec align="center"/>
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<colspec align="center"/>
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<colspec align="left" colwidth="3*"/>
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<thead>
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<row>
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<entry>Message</entry>
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<entry>Type</entry>
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<entry>Num</entry>
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<entry>Notes</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>WINEPRESSME<00></entry>
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<entry>Reg</entry>
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<entry>8</entry>
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<entry>4 lots of 2, 0.6 sec apart</entry>
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</row>
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<row>
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<entry>WINEPRESSME<03></entry>
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<entry>Reg</entry>
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<entry>8</entry>
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<entry>4 lots of 2, 0.6 sec apart</entry>
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</row>
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<row>
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<entry>WINEPRESSME<20></entry>
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<entry>Reg</entry>
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<entry>8</entry>
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<entry>4 lots of 2, 0.75 sec apart</entry>
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</row>
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<row>
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<entry>MIDEARTH<00></entry>
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<entry>Reg</entry>
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<entry>8</entry>
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<entry>4 lots of 2, 0.75 sec apart</entry>
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</row>
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<row>
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<entry>MIDEARTH<1d></entry>
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<entry>Reg</entry>
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<entry>8</entry>
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<entry>4 lots of 2, 0.75 sec apart</entry>
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</row>
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<row>
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<entry>MIDEARTH<1e></entry>
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<entry>Reg</entry>
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<entry>8</entry>
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<entry>4 lots of 2, 0.75 sec apart</entry>
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</row>
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<row>
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<entry>MIDEARTH<1b></entry>
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<entry>Qry</entry>
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<entry>84</entry>
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<entry>300 sec apart at stable operation</entry>
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</row>
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<row>
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<entry>__MSBROWSE__</entry>
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<entry>Reg</entry>
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<entry>8</entry>
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<entry>Registered after winning election to Browse Master</entry>
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</row>
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<row>
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<entry>JHT<03></entry>
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<entry>Reg</entry>
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<entry>8</entry>
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<entry>4 x 2. This is the name of the user that logged onto Windows</entry>
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</row>
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<row>
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<entry>Host Announcement WINEPRESSME</entry>
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<entry>Ann</entry>
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<entry>2</entry>
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<entry>Observed at 10 sec</entry>
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</row>
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<row>
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<entry>Domain/Workgroup Announcement MIDEARTH</entry>
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<entry>Ann</entry>
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<entry>18</entry>
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<entry>300 sec apart at stable operation</entry>
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</row>
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<row>
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<entry>Local Master Announcement WINEPRESSME</entry>
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<entry>Ann</entry>
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<entry>18</entry>
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<entry>300 sec apart at stable operation</entry>
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</row>
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<row>
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<entry>Get Backup List Request</entry>
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<entry>Qry</entry>
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<entry>12</entry>
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<entry>6 x 2 early in startup, 0.5 sec apart</entry>
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</row>
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<row>
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<entry>Browser Election Request</entry>
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<entry>Ann</entry>
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<entry>10</entry>
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<entry>5 x 2 early in startup</entry>
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</row>
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<row>
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<entry>Request Announcement WINEPRESSME</entry>
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<entry>Ann</entry>
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<entry>4</entry>
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<entry>Early in startup</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<para><indexterm>
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<primary>election</primary>
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</indexterm><indexterm>
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<primary>browse master</primary>
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</indexterm>
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From the packet trace, it should be noted that no messages were propagated over TCP/IP;
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all messages employed UDP/IP. When steady-state operation has been achieved, there is a cycle
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of various announcements, re-election of a browse master, and name queries. These create
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the symphony of announcements by which network browsing is made possible.
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</para>
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<para><indexterm>
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<primary>CIFS</primary>
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</indexterm>
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|
For detailed information regarding the precise behavior of the CIFS/SMB protocols,
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refer to the book <quote>Implementing CIFS: The Common Internet File System,</quote>
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|
by Christopher Hertel, (Prentice Hall PTR, ISBN: 013047116X).
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|
</para>
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</sect3>
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</sect2>
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|
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<sect2 id="secondmachine">
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<title>Second Machine Startup Broadcast Interaction</title>
|
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|
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<para>
|
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At this time, the machine you used to capture the single-system startup trace should still be running.
|
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The objective of this task is to identify the interaction of two machines in respect to broadcast activity.
|
|
</para>
|
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|
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<procedure>
|
|
<title>Monitoring of Second Machine Activity</title>
|
|
|
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<step><para>
|
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On the machine from which network activity will be monitored (using <command>Wireshark</command>),
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launch <command>Wireshark</command> and click
|
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<menuchoice>
|
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<guimenu>Capture</guimenu>
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<guimenuitem>Start</guimenuitem>
|
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</menuchoice>.
|
|
</para>
|
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|
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<para>
|
|
Click:
|
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<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>
|
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</orderedlist>
|
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Click <guibutton>OK</guibutton>.
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|
</para></step>
|
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|
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<step><para>
|
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Start the second Windows 9x/Me machine. Let it run for 15 to 20 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 the capture time, stop the capture. Be sure to save the captured data so you
|
|
can examine the network data capture again at a later date should that be necessary.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
Analyze the capture trace, taking note of the transport protocols used, the types of messages observed,
|
|
and what interaction took place between the two machines. Leave both machines running for the next task.
|
|
</para></step>
|
|
</procedure>
|
|
|
|
<sect3>
|
|
<title>Findings</title>
|
|
|
|
<para>
|
|
<link linkend="capsstats02"/> summarizes capture statistics observed. As in the previous case,
|
|
all announcements used UDP/IP broadcasts. Also, as was observed with the last example, the second
|
|
Windows 9x/Me machine broadcasts its name on startup to ensure that there exists no name clash
|
|
(i.e., the name is already registered by another machine) on the network segment. Those wishing
|
|
to explore the inner details of the precise mechanism of how this functions should refer to
|
|
<quote>Implementing CIFS: The Common Internet File System.</quote>
|
|
</para>
|
|
|
|
<table id="capsstats02">
|
|
<title>Second Machine (Windows 98) &smbmdash; 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>
|
|
<row>
|
|
<entry>MILGATE98<00></entry>
|
|
<entry>Reg</entry>
|
|
<entry>8</entry>
|
|
<entry>4 lots of 2, 0.6 sec apart</entry>
|
|
</row>
|
|
<row>
|
|
<entry>MILGATE98<03></entry>
|
|
<entry>Reg</entry>
|
|
<entry>8</entry>
|
|
<entry>4 lots of 2, 0.6 sec apart</entry>
|
|
</row>
|
|
<row>
|
|
<entry>MILGATE98<20></entry>
|
|
<entry>Reg</entry>
|
|
<entry>8</entry>
|
|
<entry>4 lots of 2, 0.75 sec apart</entry>
|
|
</row>
|
|
<row>
|
|
<entry>MIDEARTH<00></entry>
|
|
<entry>Reg</entry>
|
|
<entry>8</entry>
|
|
<entry>4 lots of 2, 0.75 sec apart</entry>
|
|
</row>
|
|
<row>
|
|
<entry>MIDEARTH<1d></entry>
|
|
<entry>Reg</entry>
|
|
<entry>8</entry>
|
|
<entry>4 lots of 2, 0.75 sec apart</entry>
|
|
</row>
|
|
<row>
|
|
<entry>MIDEARTH<1e></entry>
|
|
<entry>Reg</entry>
|
|
<entry>8</entry>
|
|
<entry>4 lots of 2, 0.75 sec apart</entry>
|
|
</row>
|
|
<row>
|
|
<entry>MIDEARTH<1b></entry>
|
|
<entry>Qry</entry>
|
|
<entry>18</entry>
|
|
<entry>900 sec apart at stable operation</entry>
|
|
</row>
|
|
<row>
|
|
<entry>JHT<03></entry>
|
|
<entry>Reg</entry>
|
|
<entry>2</entry>
|
|
<entry>This is the name of the user that logged onto Windows</entry>
|
|
</row>
|
|
<row>
|
|
<entry>Host Announcement MILGATE98</entry>
|
|
<entry>Ann</entry>
|
|
<entry>14</entry>
|
|
<entry>Every 120 sec</entry>
|
|
</row>
|
|
<row>
|
|
<entry>Domain/Workgroup Announcement MIDEARTH</entry>
|
|
<entry>Ann</entry>
|
|
<entry>6</entry>
|
|
<entry>900 sec apart at stable operation</entry>
|
|
</row>
|
|
<row>
|
|
<entry>Local Master Announcement WINEPRESSME</entry>
|
|
<entry>Ann</entry>
|
|
<entry>6</entry>
|
|
<entry>Insufficient detail to determine frequency</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>
|
|
<indexterm><primary>host announcement</primary></indexterm>
|
|
<indexterm><primary>Local Master Announcement</primary></indexterm>
|
|
<indexterm><primary>Workgroup Announcement</primary></indexterm>
|
|
Observation of the contents of Host Announcements, Domain/Workgroup Announcements,
|
|
and Local Master Announcements is instructive. These messages convey a significant
|
|
level of detail regarding the nature of each machine that is on the network. An example
|
|
dissection of a Host Announcement is given in <link linkend="hostannounce"/>.
|
|
</para>
|
|
|
|
|
|
<figure id="hostannounce">
|
|
<title>Typical Windows 9x/Me Host Announcement</title>
|
|
<imagefile scale="41">HostAnnouncment</imagefile>
|
|
</figure>
|
|
</sect3>
|
|
|
|
</sect2>
|
|
|
|
<sect2>
|
|
<title>Simple Windows Client Connection Characteristics</title>
|
|
|
|
<para>
|
|
The purpose of this exercise is to discover how Microsoft Windows clients create (establish)
|
|
connections with remote servers. The methodology involves analysis of a key aspect of how
|
|
Windows clients access remote servers: the session setup protocol.
|
|
</para>
|
|
|
|
<procedure>
|
|
<title>Client Connection Exploration Steps</title>
|
|
|
|
<step><para>
|
|
Configure a Windows 9x/Me machine (MILGATE98) with a share called <constant>Stuff</constant>.
|
|
Create a <parameter>Full Access</parameter> control password on this share.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
Configure another Windows 9x/Me machine (WINEPRESSME) as a client. Make sure that it exports
|
|
no shared resources.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
Start both Windows 9x/Me machines and allow them to stabilize for 10 minutes. Log on to both
|
|
machines using a user name (JHT) of your choice. Wait approximately 2 minutes before proceeding.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
Start Wireshark (or the network sniffer of your choice).
|
|
</para></step>
|
|
|
|
<step><para>
|
|
From the WINEPRESSME machine, right-click <guimenu>Network Neighborhood</guimenu>, select
|
|
<guimenuitem>Explore</guimenuitem>, select
|
|
<menuchoice>
|
|
<guimenuitem>My Network Places</guimenuitem>
|
|
<guimenuitem>Entire Network</guimenuitem>
|
|
<guimenuitem>MIDEARTH</guimenuitem>
|
|
<guimenuitem>MILGATE98</guimenuitem>
|
|
<guimenuitem>Stuff</guimenuitem>
|
|
</menuchoice>.
|
|
Enter the password you set for the <constant>Full Control</constant> mode for the
|
|
<constant>Stuff</constant> share.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
When the share called <constant>Stuff</constant> is being displayed, stop the capture.
|
|
Save the captured data in case it is needed for later analysis.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
<indexterm><primary>session setup</primary></indexterm>
|
|
From the top of the packets captured, scan down to locate the first packet that has
|
|
interpreted as <constant>Session Setup AndX, User: anonymous; Tree Connect AndX,
|
|
Path: \\MILGATE98\IPC$</constant>.
|
|
</para></step>
|
|
|
|
<step><para><indexterm>
|
|
<primary>Session Setup</primary>
|
|
</indexterm><indexterm>
|
|
<primary>Tree Connect</primary>
|
|
</indexterm>
|
|
In the dissection (analysis) panel, expand the <constant>SMB, Session Setup AndX Request,
|
|
and Tree Connect AndX Request</constant>. Examine both operations. Identify the name of
|
|
the user Account and what password was used. The Account name should be empty.
|
|
This is a <constant>NULL</constant> session setup packet.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
Return to the packet capture sequence. There will be a number of packets that have been
|
|
decoded of the type <constant>Session Setup AndX</constant>. Locate the last such packet
|
|
that was targeted at the <constant>\\MILGATE98\IPC$</constant> service.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
<indexterm><primary>password length</primary></indexterm>
|
|
<indexterm><primary>User Mode</primary></indexterm>
|
|
Dissect this packet as per the previous one. This packet should have a password length
|
|
of 24 (characters) and should have a password field, the contents of which is a
|
|
long hexadecimal number. Observe the name in the Account field. This is a User Mode
|
|
session setup packet.
|
|
</para></step>
|
|
</procedure>
|
|
|
|
<sect3>
|
|
<title>Findings and Comments</title>
|
|
|
|
<para>
|
|
<indexterm><primary>IPC$</primary></indexterm>
|
|
The <constant>IPC$</constant> share serves a vital purpose<footnote><para>TOSHARG2, Sect 4.5.1</para></footnote>
|
|
in SMB/CIFS-based networking. A Windows client connects to this resource to obtain the list of
|
|
resources that are available on the server. The server responds with the shares and print queues that
|
|
are available. In most but not all cases, the connection is made with a <constant>NULL</constant>
|
|
username and a <constant>NULL</constant> password.
|
|
</para>
|
|
|
|
<para>
|
|
<indexterm><primary>account credentials</primary></indexterm>
|
|
The two packets examined are material evidence of how Windows clients may
|
|
interoperate with Samba. Samba requires every connection setup to be authenticated using
|
|
valid UNIX account credentials (UID/GID). This means that even a <constant>NULL</constant>
|
|
session setup can be established only by automatically mapping it to a valid UNIX
|
|
account.
|
|
</para>
|
|
|
|
<para>
|
|
<indexterm><primary>NULL session</primary></indexterm><indexterm>
|
|
<primary>guest account</primary>
|
|
</indexterm>
|
|
<indexterm><primary>nobody</primary></indexterm>
|
|
Samba has a special name for the <constant>NULL</constant>, or empty, user account:
|
|
it calls it the <smbconfoption name="guest account"/>. The
|
|
default value of this parameter is <constant>nobody</constant>; however, this can be
|
|
changed to map the function of the guest account to any other UNIX identity. Some
|
|
UNIX administrators prefer to map this account to the system default anonymous
|
|
FTP account. A sample NULL Session Setup AndX packet dissection is shown in
|
|
<link linkend="nullconnect"/>.
|
|
</para>
|
|
|
|
<figure id="nullconnect">
|
|
<title>Typical Windows 9x/Me NULL SessionSetUp AndX Request</title>
|
|
|
|
<imagefile scale="41">NullConnect</imagefile>
|
|
</figure>
|
|
|
|
<para>
|
|
<indexterm><primary>nobody</primary></indexterm>
|
|
<indexterm><primary>/etc/passwd</primary></indexterm>
|
|
<indexterm><primary>guest account</primary></indexterm>
|
|
When a UNIX/Linux system does not have a <constant>nobody</constant> user account
|
|
(<filename>/etc/passwd</filename>), the operation of the <constant>NULL</constant>
|
|
account cannot validate and thus connections that utilize the guest account
|
|
fail. This breaks all ability to browse the Samba server and is a common
|
|
problem reported on the Samba mailing list. A sample User Mode session setup AndX
|
|
is shown in <link linkend="userconnect"/>.
|
|
</para>
|
|
|
|
<figure id="userconnect">
|
|
<title>Typical Windows 9x/Me User SessionSetUp AndX Request</title>
|
|
<imagefile scale="41">UserConnect</imagefile>
|
|
</figure>
|
|
|
|
<para>
|
|
<indexterm><primary>encrypted</primary></indexterm>
|
|
The User Mode connection packet contains the account name and the domain name.
|
|
The password is provided in Microsoft encrypted form, and its length is shown
|
|
as 24 characters. This is the length of Microsoft encrypted passwords.
|
|
</para>
|
|
|
|
</sect3>
|
|
|
|
</sect2>
|
|
|
|
<sect2>
|
|
<title>Windows 200x/XP Client Interaction with Samba-3</title>
|
|
|
|
<para>
|
|
By now you may be asking, <quote>Why did you choose to work with Windows 9x/Me?</quote>
|
|
</para>
|
|
|
|
<para>
|
|
First, we want to demonstrate the simple case. This book is not intended to be a detailed treatise
|
|
on the Windows networking protocols, but rather to provide prescriptive guidance for deployment of Samba.
|
|
Second, by starting out with the simple protocol, it can be demonstrated that the more complex case mostly
|
|
follows the same principles.
|
|
</para>
|
|
|
|
<para>
|
|
The following exercise demonstrates the case that even MS Windows XP Professional with up-to-date service
|
|
updates also uses the <constant>NULL</constant> account, as well as user accounts. Simply follow the procedure
|
|
to complete this exercise.
|
|
</para>
|
|
|
|
<para>
|
|
To complete this exercise, you need a Windows XP Professional client that has been configured as
|
|
a domain member of either a Samba-controlled domain or a Windows NT4 or 200x Active Directory domain.
|
|
Here we do not provide details for how to configure this, as full coverage is provided earlier in this book.
|
|
</para>
|
|
|
|
<procedure>
|
|
<title>Steps to Explore Windows XP Pro Connection Set-up</title>
|
|
|
|
<step><para>
|
|
Start your domain controller. Also, start the Wireshark monitoring machine, launch Wireshark,
|
|
and then wait for the next step to complete.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
Start the Windows XP Client and wait 5 minutes before proceeding.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
On the machine from which network activity will be monitored (using <command>Wireshark</command>),
|
|
launch <command>Wireshark</command> and click
|
|
<menuchoice>
|
|
<guimenu>Capture</guimenu>
|
|
<guimenuitem>Start</guimenuitem>
|
|
</menuchoice>.
|
|
</para>
|
|
|
|
<para>
|
|
Click:
|
|
<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>
|
|
On the Windows XP Professional client, press <guimenu>Ctrl-Alt-Delete</guimenu> to bring
|
|
up the domain logon screen. Log in using valid credentials for a domain user account.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
Now proceed to connect to the domain controller as follows:
|
|
<menuchoice>
|
|
<guimenu>Start</guimenu>
|
|
<guimenuitem>(right-click) My Network Places</guimenuitem>
|
|
<guimenuitem>Explore</guimenuitem>
|
|
<guimenuitem>{Left Panel} [+] Entire Network</guimenuitem>
|
|
<guimenuitem>{Left Panel} [+] Microsoft Windows Network</guimenuitem>
|
|
<guimenuitem>{Left Panel} [+] Midearth</guimenuitem>
|
|
<guimenuitem>{Left Panel} [+] Frodo</guimenuitem>
|
|
<guimenuitem>{Left Panel} [+] data</guimenuitem>
|
|
</menuchoice>. Close the explorer window.
|
|
</para>
|
|
|
|
<para>
|
|
In this step, our domain name is <constant>Midearth</constant>, the domain controller is called
|
|
<constant>Frodo</constant>, and we have connected to a share called <constant>data</constant>.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
Stop the capture on the <command>Wireshark</command> monitoring machine. Be sure to save the captured data
|
|
to a file so that you can refer to it again later.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
If desired, the Windows XP Professional client and the domain controller are no longer needed for exercises
|
|
in this chapter.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
<indexterm><primary>NTLMSSP_AUTH</primary></indexterm>
|
|
<indexterm><primary>session setup</primary></indexterm>
|
|
From the top of the packets captured, scan down to locate the first packet that has
|
|
interpreted as <constant>Session Setup AndX Request, NTLMSSP_AUTH</constant>.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
<indexterm><primary>GSS-API</primary></indexterm>
|
|
<indexterm><primary>SPNEGO</primary></indexterm>
|
|
<indexterm><primary>NTLMSSP</primary></indexterm>
|
|
In the dissection (analysis) panel, expand the <constant>SMB, Session Setup AndX Request</constant>.
|
|
Expand the packet decode information, beginning at the <constant>Security Blob:</constant>
|
|
entry. Expand the <constant>GSS-API -> SPNEGO -> netTokenTarg -> responseToken -> NTLMSSP</constant>
|
|
keys. This should reveal that this is a <constant>NULL</constant> session setup packet.
|
|
The <constant>User name: NULL</constant> so indicates. An example decode is shown in
|
|
<link linkend="XPCap01"/>.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
Return to the packet capture sequence. There will be a number of packets that have been
|
|
decoded of the type <constant>Session Setup AndX Request</constant>. Click the last such packet that
|
|
has been decoded as <constant>Session Setup AndX Request, NTLMSSP_AUTH</constant>.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
<indexterm><primary>encrypted password</primary></indexterm>
|
|
In the dissection (analysis) panel, expand the <constant>SMB, Session Setup AndX Request</constant>.
|
|
Expand the packet decode information, beginning at the <constant>Security Blob:</constant>
|
|
entry. Expand the <constant>GSS-API -> SPNEGO -> netTokenTarg -> responseToken -> NTLMSSP</constant>
|
|
keys. This should reveal that this is a <constant>User Mode</constant> session setup packet.
|
|
The <constant>User name: jht</constant> so indicates. An example decode is shown in
|
|
<link linkend="XPCap02"/>. In this case the user name was <constant>jht</constant>. This packet
|
|
decode includes the <constant>Lan Manager Response:</constant> and the <constant>NTLM Response:</constant>.
|
|
The values of these two parameters are the Microsoft encrypted password hashes: respectively, the LanMan
|
|
password and then the NT (case-preserving) password hash.
|
|
</para></step>
|
|
|
|
<step><para>
|
|
<indexterm><primary>password length</primary></indexterm>
|
|
<indexterm><primary>User Mode</primary></indexterm>
|
|
The passwords are 24-character hexadecimal numbers. This packet confirms that this is a User Mode
|
|
session setup packet.
|
|
</para></step>
|
|
|
|
</procedure>
|
|
|
|
<figure id="XPCap01">
|
|
<title>Typical Windows XP NULL Session Setup AndX Request</title>
|
|
<imagefile scale="50">WindowsXP-NullConnection</imagefile>
|
|
</figure>
|
|
|
|
<figure id="XPCap02">
|
|
<title>Typical Windows XP User Session Setup AndX Request</title>
|
|
<imagefile scale="50">WindowsXP-UserConnection</imagefile>
|
|
</figure>
|
|
|
|
<sect3>
|
|
<title>Discussion</title>
|
|
|
|
<para><indexterm>
|
|
<primary>NULL-Session</primary>
|
|
</indexterm>
|
|
This exercise demonstrates that, while the specific protocol for the Session Setup AndX is handled
|
|
in a more sophisticated manner by recent MS Windows clients, the underlying rules or principles
|
|
remain the same. Thus it is demonstrated that MS Windows XP Professional clients still use a
|
|
<constant>NULL-Session</constant> connection to query and locate resources on an advanced network
|
|
technology server (one using Windows NT4/200x or Samba). It also demonstrates that an authenticated
|
|
connection must be made before resources can be used.
|
|
</para>
|
|
|
|
</sect3>
|
|
|
|
</sect2>
|
|
|
|
<sect2>
|
|
<title>Conclusions to Exercises</title>
|
|
|
|
<para>
|
|
In summary, the following points have been established in this chapter:
|
|
</para>
|
|
|
|
<itemizedlist>
|
|
<listitem><para>
|
|
When NetBIOS over TCP/IP protocols are enabled, MS Windows networking employs broadcast-oriented messaging protocols to provide knowledge of network services.
|
|
</para></listitem>
|
|
|
|
<listitem><para>
|
|
Network browsing protocols query information stored on browse masters that manage
|
|
information provided by NetBIOS Name Registrations and by way of ongoing host
|
|
announcements and workgroup announcements.
|
|
</para></listitem>
|
|
|
|
<listitem><para>
|
|
All Samba servers must be configured with a mechanism for mapping the <constant>NULL-Session</constant>
|
|
to a valid but nonprivileged UNIX system account.
|
|
</para></listitem>
|
|
|
|
<listitem><para>
|
|
The use of Microsoft encrypted passwords is built right into the fabric of Windows
|
|
networking operations. Such passwords cannot be provided from the UNIX <filename>/etc/passwd</filename>
|
|
database and thus must be stored elsewhere on the UNIX system in a manner that Samba can
|
|
use. Samba-2.x permitted such encrypted passwords to be stored in the <constant>smbpasswd</constant>
|
|
file or in an LDAP database. Samba-3 permits use of multiple <parameter>passdb backend</parameter>
|
|
databases in concurrent deployment. Refer to <emphasis>TOSHARG2</emphasis>, Chapter 10, <quote>Account Information Databases.</quote>
|
|
</para></listitem>
|
|
</itemizedlist>
|
|
|
|
</sect2>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="chap01conc">
|
|
<title>Dissection and Discussion</title>
|
|
|
|
<para>
|
|
<indexterm><primary>guest account</primary></indexterm>
|
|
The exercises demonstrate the use of the <constant>guest</constant> account, the way that
|
|
MS Windows clients and servers resolve computer names to a TCP/IP address, and how connections
|
|
between a client and a server are established.
|
|
</para>
|
|
|
|
<para>
|
|
Those wishing background information regarding NetBIOS name types should refer to
|
|
the Microsoft knowledgebase article
|
|
<ulink url="http://support.microsoft.com/support/kb/articles/Q102/78/8.asp">Q102878.</ulink>
|
|
</para>
|
|
|
|
<sect2>
|
|
<title>Technical Issues</title>
|
|
|
|
<para>
|
|
<indexterm><primary>guest account</primary></indexterm>
|
|
Network browsing involves SMB broadcast announcements, SMB enumeration requests,
|
|
connections to the <constant>IPC$</constant> share, share enumerations, and SMB connection
|
|
setup processes. The use of anonymous connections to a Samba server involve the use of
|
|
the <parameter>guest account</parameter> that must map to a valid UNIX UID.
|
|
</para>
|
|
|
|
</sect2>
|
|
|
|
</sect1>
|
|
|
|
<sect1 id="chap01qa">
|
|
<title>Questions and Answers</title>
|
|
|
|
<para>
|
|
The questions and answers given in this section are designed to highlight important aspects of Microsoft
|
|
Windows networking.
|
|
</para>
|
|
|
|
<qandaset defaultlabel="chap01qa" type="number">
|
|
<qandaentry>
|
|
<question>
|
|
|
|
<para>
|
|
What is the significance of the MIDEARTH<1b> type query?
|
|
</para>
|
|
|
|
</question>
|
|
<answer>
|
|
|
|
<para>
|
|
<indexterm><primary>Domain Master Browser</primary><see>DMB</see></indexterm>
|
|
<indexterm><primary>DMB</primary></indexterm>
|
|
This is a broadcast announcement by which the Windows machine is attempting to
|
|
locate a Domain Master Browser (DMB) in the event that it might exist on the network.
|
|
Refer to <emphasis>TOSHARG2,</emphasis> Chapter 9, Section 9.7, <quote>Technical Overview of Browsing,</quote>
|
|
for details regarding the function of the DMB and its role in network browsing.
|
|
</para>
|
|
|
|
</answer>
|
|
</qandaentry>
|
|
|
|
<qandaentry>
|
|
<question>
|
|
|
|
<para>
|
|
What is the significance of the MIDEARTH<1d> type name registration?
|
|
</para>
|
|
|
|
</question>
|
|
<answer>
|
|
|
|
<para>
|
|
<indexterm><primary>Local Master Browser</primary><see>LMB</see></indexterm>
|
|
<indexterm><primary>LMB</primary></indexterm>
|
|
This name registration records the machine IP addresses of the LMBs.
|
|
Network clients can query this name type to obtain a list of browser servers from the
|
|
master browser.
|
|
</para>
|
|
|
|
<para>
|
|
The LMB is responsible for monitoring all host announcements on the local network and for
|
|
collating the information contained within them. Using this information, it can provide answers to other Windows
|
|
network clients that request information such as:
|
|
</para>
|
|
|
|
<itemizedlist>
|
|
<listitem><para>
|
|
The list of machines known to the LMB (i.e., the browse list)
|
|
</para></listitem>
|
|
|
|
<listitem><para>
|
|
The IP addresses of all domain controllers known for the domain
|
|
</para></listitem>
|
|
|
|
<listitem><para>
|
|
The IP addresses of LMBs
|
|
</para></listitem>
|
|
|
|
<listitem><para>
|
|
The IP address of the DMB (if one exists)
|
|
</para></listitem>
|
|
|
|
<listitem><para>
|
|
The IP address of the LMB on the local segment
|
|
</para></listitem>
|
|
</itemizedlist>
|
|
|
|
</answer>
|
|
</qandaentry>
|
|
|
|
<qandaentry>
|
|
<question>
|
|
|
|
<para>
|
|
What is the role and significance of the <01><02>__MSBROWSE__<02><01>
|
|
name registration?
|
|
</para>
|
|
|
|
</question>
|
|
<answer>
|
|
|
|
<para>
|
|
<indexterm><primary>Browse Master</primary></indexterm>
|
|
This name is registered by the browse master to broadcast and receive domain announcements.
|
|
Its scope is limited to the local network segment, or subnet. By querying this name type,
|
|
master browsers on networks that have multiple domains can find the names of master browsers
|
|
for each domain.
|
|
</para>
|
|
|
|
</answer>
|
|
</qandaentry>
|
|
|
|
<qandaentry>
|
|
<question>
|
|
|
|
<para>
|
|
What is the significance of the MIDEARTH<1e> type name registration?
|
|
</para>
|
|
|
|
</question>
|
|
<answer>
|
|
|
|
<para>
|
|
<indexterm><primary>Browser Election Service</primary></indexterm>
|
|
This name is registered by all browse masters in a domain or workgroup. The registration
|
|
name type is known as the Browser Election Service. Master browsers register themselves
|
|
with this name type so that DMBs can locate them to perform cross-subnet
|
|
browse list updates. This name type is also used to initiate elections for Master Browsers.
|
|
</para>
|
|
|
|
</answer>
|
|
</qandaentry>
|
|
|
|
<qandaentry>
|
|
<question>
|
|
|
|
<para>
|
|
<indexterm><primary>guest account</primary></indexterm>
|
|
What is the significance of the <parameter>guest account</parameter> in smb.conf?
|
|
</para>
|
|
|
|
</question>
|
|
<answer>
|
|
|
|
<para>
|
|
This parameter specifies the default UNIX account to which MS Windows networking
|
|
NULL session connections are mapped. The default name for the UNIX account used for
|
|
this mapping is called <constant>nobody</constant>. If the UNIX/Linux system that
|
|
is hosting Samba does not have a <constant>nobody</constant> account and an alternate
|
|
mapping has not been specified, network browsing will not work at all.
|
|
</para>
|
|
|
|
<para>
|
|
It should be noted that the <parameter>guest account</parameter> is essential to
|
|
Samba operation. Either the operating system must have an account called <constant>nobody</constant>
|
|
or there must be an entry in the &smb.conf; file with a valid UNIX account, such as
|
|
<smbconfoption name="guest account">ftp</smbconfoption>.
|
|
</para>
|
|
|
|
</answer>
|
|
</qandaentry>
|
|
|
|
<qandaentry>
|
|
<question>
|
|
|
|
<para>
|
|
Is it possible to reduce network broadcast activity with Samba-3?
|
|
</para>
|
|
|
|
</question>
|
|
<answer>
|
|
|
|
<para>
|
|
<indexterm><primary>WINS</primary></indexterm>
|
|
<indexterm><primary>NetBIOS</primary></indexterm>
|
|
Yes, there are two ways to do this. The first involves use of WINS (See <emphasis>TOSHARG2</emphasis>, Chapter 9,
|
|
Section 9.5, <quote>WINS &smbmdash; The Windows Inter-networking Name Server</quote>); the
|
|
alternate method involves disabling the use of NetBIOS over TCP/IP. This second method requires
|
|
a correctly configured DNS server (see <emphasis>TOSHARG2</emphasis>, Chapter 9, Section 9.3, <quote>Discussion</quote>).
|
|
</para>
|
|
|
|
<para>
|
|
<indexterm><primary>broadcast</primary></indexterm>
|
|
<indexterm><primary>NetBIOS</primary><secondary>Node Type</secondary></indexterm>
|
|
<indexterm><primary>Hybrid</primary></indexterm>
|
|
The use of WINS reduces network broadcast traffic. The reduction is greatest when all network
|
|
clients are configured to operate in <parameter>Hybrid Mode</parameter>. This can be effected through
|
|
use of DHCP to set the NetBIOS node type to type 8 for all network clients. Additionally, it is
|
|
beneficial to configure Samba to use <smbconfoption name="name resolve order">wins host cast</smbconfoption>.
|
|
</para>
|
|
|
|
<note><para>
|
|
Use of SMB without NetBIOS is possible only on Windows 200x/XP Professional clients and servers, as
|
|
well as with Samba-3.
|
|
</para></note>
|
|
|
|
</answer>
|
|
</qandaentry>
|
|
|
|
<qandaentry>
|
|
<question>
|
|
|
|
<para>
|
|
Can I just use plain-text passwords with Samba?
|
|
</para>
|
|
|
|
</question>
|
|
<answer>
|
|
|
|
<para>
|
|
Yes, you can configure Samba to use plain-text passwords, though this does create a few problems.
|
|
</para>
|
|
|
|
<para>
|
|
First, the use of <filename>/etc/passwd</filename>-based plain-text passwords requires that registry
|
|
modifications be made on all MS Windows client machines to enable plain-text passwords support. This
|
|
significantly diminishes the security of MS Windows client operation. Many network administrators
|
|
are bitterly opposed to doing this.
|
|
</para>
|
|
|
|
<para>
|
|
Second, Microsoft has not maintained plain-text password support since the default setting was made
|
|
disabling this. When network connections are dropped by the client, it is not possible to re-establish
|
|
the connection automatically. Users need to log off and then log on again. Plain-text password support
|
|
may interfere with recent enhancements that are part of the Microsoft move toward a more secure computing
|
|
environment.
|
|
</para>
|
|
|
|
<para>
|
|
Samba-3 supports Microsoft encrypted passwords. Be advised not to reintroduce plain-text password handling.
|
|
Just create user accounts by running <command>smbpasswd -a 'username'</command>
|
|
</para>
|
|
|
|
<para>
|
|
It is not possible to add a user to the <parameter>passdb backend</parameter> database unless there is
|
|
a UNIX system account for that user. On systems that run <command>winbindd</command> to access the Samba
|
|
PDC/BDC to provide Windows user and group accounts, the <parameter>idmap uid, idmap gid</parameter> ranges
|
|
set in the &smb.conf; file provide the local UID/GIDs needed for local identity management purposes.
|
|
</para>
|
|
|
|
</answer>
|
|
</qandaentry>
|
|
|
|
<qandaentry>
|
|
<question>
|
|
|
|
<para>
|
|
What parameter in the &smb.conf; file is used to enable the use of encrypted passwords?
|
|
</para>
|
|
|
|
</question>
|
|
<answer>
|
|
|
|
<para>
|
|
The parameter in the &smb.conf; file that controls this behavior is known as <parameter>encrypt
|
|
passwords</parameter>. The default setting for this in Samba-3 is <constant>Yes (Enabled)</constant>.
|
|
</para>
|
|
|
|
</answer>
|
|
</qandaentry>
|
|
|
|
<qandaentry>
|
|
<question>
|
|
|
|
<para>
|
|
Is it necessary to specify <smbconfoption name="encrypt passwords">Yes</smbconfoption>
|
|
when Samba-3 is configured as a domain member?
|
|
</para>
|
|
|
|
</question>
|
|
<answer>
|
|
|
|
<para>
|
|
No. This is the default behavior.
|
|
</para>
|
|
|
|
</answer>
|
|
</qandaentry>
|
|
|
|
<qandaentry>
|
|
<question>
|
|
|
|
<para>
|
|
Is it necessary to specify a <parameter>guest account</parameter> when Samba-3 is configured
|
|
as a domain member server?
|
|
</para>
|
|
|
|
</question>
|
|
<answer>
|
|
|
|
<para>
|
|
Yes. This is a local function on the server. The default setting is to use the UNIX account
|
|
<constant>nobody</constant>. If this account does not exist on the UNIX server, then it is
|
|
necessary to provide a <smbconfoption name="guest account">an_account</smbconfoption>,
|
|
where <constant>an_account</constant> is a valid local UNIX user account.
|
|
</para>
|
|
|
|
</answer>
|
|
</qandaentry>
|
|
</qandaset>
|
|
|
|
</sect1>
|
|
|
|
</chapter>
|
|
|