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<!-- WSUG Chapter Introduction -->
<!-- $Id$ -->

<chapter id="ChapterIntroduction">
  <title>Introduction</title>
  <!-- Introduction -->
  <section id="ChIntroWhatIs">
    <title>What is <application>Wireshark?</application></title>
    <para>
	Wireshark is a network packet analyzer. A network packet 
	analyzer will try to capture network packets and tries to display
	that packet data as detailed as possible.
    </para>
    <para>
	You could think of a network packet analyzer as a measuring device used to 
	examine what's going on inside a network cable, just like a voltmeter is 
	used by an electrician to examine what's going on inside an electric cable 
	(but at a higher level, of course).
    </para>
    <para>
	In the past, such tools were either very expensive, proprietary, or both.
	However, with the advent of Wireshark, all that has changed.
    </para>
    <para>
	<application>Wireshark</application> is perhaps one of the best open 
	source packet analyzers available today.
	</para>
	
  <section id="ChIntroPurposes"><title>Some intended purposes</title>
	<para>
	Here are some examples people use Wireshark for:
      <itemizedlist>
	<listitem><para>
	  network administrators use it to <command>troubleshoot network
	   problems</command>
	</para></listitem>
	<listitem><para>
	  network security engineers use it to <command>examine security 
	  problems</command>
	</para></listitem>
	<listitem><para>
	  developers use it to <command>debug protocol implementations</command> 
	</para></listitem>
	<listitem><para>
	  people use it to <command>learn network protocol</command> 
	  internals
	</para></listitem>
      </itemizedlist>
	  Beside these examples, Wireshark can be helpful in many other situations 
	  too.
	</para>
  </section>

  <section id="ChIntroFeatures"><title>Features</title>
	<para>
	The following are some of the many features Wireshark provides:
      <itemizedlist>
	<listitem>
	  <para>Available for <command>UNIX</command> and <command>Windows</command>.</para>
	</listitem>
	<listitem>
	  <para>
	    <command>Capture</command> live packet data from a network interface.
	  </para>
	</listitem>
	<listitem>
	  <para>
	    Display packets with <command>very detailed protocol information</command>.
	  </para>
	</listitem>
	<listitem>
	  <para>
	    <command>Open and Save</command> packet data captured.
	  </para>
	</listitem>
	<listitem>
	  <para>
	    <command>Import and Export</command> packet data from and to a lot of 
		other capture programs.
	  </para>
	</listitem>
	<listitem>
	  <para><command>Filter packets</command> on many criteria.</para>
	</listitem>
	<listitem>
	  <para><command>Search</command> for packets on many criteria.</para>
	</listitem>
	<listitem>
	  <para><command>Colorize</command> packet display based on filters.</para>
	</listitem>
	<listitem>
	  <para>Create various <command>statistics</command>.</para>
	</listitem>
	<listitem>
	  <para>... and <command>a lot more!</command></para>
	</listitem>
      </itemizedlist> 
      However, to really appreciate its power, you have to start using it.
    </para>
    <para>
      <xref linkend="ChIntroFig1"/> shows <application>Wireshark</application> 
	having captured some packets and waiting for you to examine 
	them.
	<figure id="ChIntroFig1">
	  <title>
	    <application>Wireshark</application> captures packets and allows 
	    you to examine their content.
	  </title>
	  <graphic entityref="WiresharkMain1" format="PNG"/>
	</figure>
    </para>
	</section>
	
	<section>
	<title>Live capture from many different network media</title>
	<para>
	  Despite its name, Wireshark can capture traffic from 
	  network media other than Ethernet. Which media types are 
	  supported, depends on many things like the operating system you are 
	  using. An overview of the supported media types can be found at: 
	  <ulink url="&WiresharkMediaPage;"/>.
	</para>
	</section>
	
    <section><title>Import files from many other capture programs</title>
	<para>
	    Wireshark can open packets captured from a large number of 
		other capture programs. For a list of input formats see 
		<xref linkend="ChIOInputFormatsSection"/>.
	</para>
    </section>
    <section><title>Export files for many other capture programs</title>
	<para>
	    Wireshark can save packets captured in a large number of formats of
		other capture programs. For a list of output formats see 
		<xref linkend="ChIOOutputFormatsSection"/>.
	</para>
    </section>
	
	<section>
	<title>Many protocol decoders</title>
	<para>
      There are protocol decoders (or dissectors, as they are 
      known in Wireshark) for a great many protocols: 
	  see <xref linkend="AppProtocols"/>.
	</para>
	</section>
	
	<section><title>Open Source Software</title>
    <para>
      Wireshark is an open source software project, and is released under 
      the <ulink url="&GPLWebsite;">GNU General Public Licence</ulink> (GPL). 
	  You can freely use Wireshark on any number of computers you like, without 
	  worrying about license keys or fees or such. In addition, all source 
	  code is freely available under the GPL. Because of that, it is very easy 
	  for people to add new protocols to Wireshark, either as plugins, or built 
	  into the source, and they often do!
    </para>
	</section>
	
    <section id="ChIntroNoFeatures"><title>What Wireshark is not</title>
	<para>
	Here are some things Wireshark does not provide:
      <itemizedlist>
	<listitem><para>
	  Wireshark isn't an intrusion detection system.  It will not warn you when 
	  someone does strange things on your network that he/she isn't allowed to 
	  do. However, if strange things happen, Wireshark might help you figure 
	  out what is really going on.
	</para></listitem>
	<listitem><para>
	  Wireshark will not manipulate things on the network, it will only 
	  "measure" things from it. Wireshark doesn't send packets on the network 
	  or do other active things (except for name resolutions, but even 
	  that can be disabled).
	</para></listitem>
      </itemizedlist>
	</para>
    </section>	
  </section>
  
  <section id="ChIntroPlatforms">
    <title>Platforms Wireshark runs on</title>
    <para>
      Wireshark currently runs on most UNIX platforms and various Windows 
      platforms. It requires GTK+, GLib, libpcap and some other libraries in 
	  order to run.
    </para>
    <para>
      If a binary package is not available for your platform, you should 
      download the source and try to build it. Please report your experiences
	  to <ulink url="mailto:&WiresharkDevMailList;">&WiresharkDevMailList;</ulink>.
    </para>
    <para>
      Binary packages are available for at least the following platforms:
    </para>

	<section><title>Unix</title>
	<para>
	<itemizedlist>
	<listitem><para>Apple Mac OS X</para></listitem>
	<listitem><para>BeOS</para></listitem>
	<listitem><para>FreeBSD</para></listitem>
	<listitem><para>HP-UX</para></listitem>
	<listitem><para>IBM AIX</para></listitem>
	<listitem><para>NetBSD</para></listitem>
	<listitem><para>OpenBSD</para></listitem>
	<listitem><para>SCO UnixWare/OpenUnix</para></listitem>
	<listitem><para>SGI Irix</para></listitem>
	<listitem><para>Sun Solaris/Intel</para></listitem>
	<listitem><para>Sun Solaris/Sparc</para></listitem>
	<listitem><para>Tru64 UNIX (formerly Digital UNIX)</para></listitem>
	</itemizedlist>
	</para>
	</section>
	
	<section><title>Linux</title>
	<para>
	<itemizedlist>
	<listitem><para>Debian GNU/Linux</para></listitem>
	<listitem><para>Gentoo Linux</para></listitem>
	<listitem><para>IBM S/390 Linux (Red Hat)</para></listitem>
	<listitem><para>Mandrake Linux</para></listitem>
	<listitem><para>PLD Linux</para></listitem>
	<listitem><para>Red Hat Linux</para></listitem>
	<listitem><para>Rock Linux</para></listitem>
	<listitem><para>Slackware Linux</para></listitem>
	<listitem><para>Suse Linux</para></listitem>
	</itemizedlist>
	</para>
	</section>
	
	<section><title>Microsoft Windows</title>
    <para>
	Maintained: 
	<itemizedlist>
	<listitem><para>Windows Server 2003 / XP / 2000 / NT 4.0</para></listitem>
	<listitem><para>Windows Me / 98</para></listitem>
	</itemizedlist>
    </para>
    <para>
	Unsupported/Unmaintained (because lack of required libraries):
	<itemizedlist>
	<listitem><para>Windows CE</para></listitem>
	<listitem><para>Windows NT / XP Embedded</para></listitem>
	<listitem><para>Windows 95 is no longer actively maintained by WinPcap,
	but still may work perfectly</para></listitem>
	</itemizedlist>
    </para>
    <para>
	No experiences (fresh versions):
	<itemizedlist>
	<listitem><para>Windows XP 64-bit Edition</para></listitem>
	<listitem><para>Windows Vista (aka Longhorn)</para></listitem>
	</itemizedlist>
	Please provide your experiences about these fresh versions to: 
	<ulink url="mailto:&WiresharkDevMailList;">&WiresharkDevMailList;</ulink>.
    </para>
	</section>
	
  </section>
  
  <section id="ChIntroDownload">
    <title>Where to get Wireshark?</title>
    <para>
      You can get the latest copy of the program from the Wireshark website: 
      <ulink url="&WiresharkDownloadPage;">&WiresharkDownloadPage;</ulink>.  The 
      website allows you to choose from among several mirrors for 
      downloading.
    </para>
    <para>
	A new Wireshark version will typically become available every 4-8 weeks.
    </para>
    <para>
	If you want to be notified about new Wireshark releases, you should 
	subscribe to the ethereal-announce mailing list. You will find more 
	details in <xref linkend="ChIntroMailingLists"/>.
    </para>
  </section>
  
  <section id="ChIntroPronounce">
    <title>A rose by any other name</title>
    <para>
      William Shakespeare wrote: 
      <emphasis>
	&quot;A rose by any other name would smell as sweet.&quot;
      </emphasis>  
      And so it is with Wireshark, as there appears to be two different 
      ways that people pronounce the name. 
    </para>
    <para>
      Some people pronounce it ether-real, while others pronounce it 
      e-the-real, as in ghostly, insubstantial, etc.
    </para>
    <para>
      You are welcome to call it what you like, as long as you find it 
      useful. The FAQ gives the official pronunciation as "e-the-real".
    </para>
  </section>
  
  <section id="ChIntroHistory">
    <title>A brief history of Wireshark</title>
    <para>
      In late 1997, Gerald Combs needed a tool for tracking down 
      networking problems and wanted to learn more about networking, so 
      he started writing Wireshark as a way to solve both problems.
    </para>
    <para>
      Wireshark was initially released, after several pauses in development, 
      in July 1998 as version 0.2.0.  Within days, patches, bug reports, 
      and words of encouragement started arriving, so Wireshark was on its 
      way to success.
    </para>
    <para>
      Not long after that Gilbert Ramirez saw its potential and contributed 
      a low-level dissector to it.
    </para>
    <para>
      In October, 1998, Guy Harris of Network Appliance was looking for 
	  something better than tcpview, so he started applying patches and 
	  contributing dissectors to Wireshark.
    </para>
    <para>
      In late 1998, Richard Sharpe, who was giving TCP/IP courses, saw its 
      potential on such courses, and started looking at it to see if it 
      supported the protocols he needed. While it didn't at that point, 
      new protocols could be easily added.  So he started contributing 
      dissectors and contributing patches.
    </para>
    <para>
      The list of people who have contributed to Wireshark has become very long 
	  since then, and almost all of them started with a protocol that they 
	  needed that Wireshark did not already handle. So they copied an existing 
	  dissector and contributed the code back to the team.
    </para>
  </section>
  
  <section id="ChIntroMaintenance">
    <title>
      Development and maintenance of <application>Wireshark</application>
    </title>
    <para>
      Wireshark was initially developed by Gerald Combs. Ongoing development 
      and maintenance of Wireshark is handled by the Wireshark team, a loose 
      group of individuals who fix bugs and provide new functionality.  
    </para>
    <para>
      There have also been a large number of people who have contributed 
      protocol dissectors to Wireshark, and it is expected that this will 
      continue.  You can find a list of the people who have contributed 
      code to Wireshark by checking the about dialog box of Wireshark, or at 
	  the <ulink url="&WiresharkAuthorsPage;">authors</ulink> page on the 
      Wireshark web site.
    </para>
    <para>
      Wireshark is an open source software project, and is released under 
      the <ulink url="&GPLWebsite;">GNU General Public Licence</ulink> (GPL). 
	  All source code is freely available under the GPL.  You are welcome to 
      modify Wireshark to suit your own needs, and it would be appreciated 
      if you contribute your improvements back to the Wireshark team.
    </para>
    <para>
      You gain three benefits by contributing your improvements back to the 
      community:
      <itemizedlist>
	<listitem>
	  <para>
	    Other people who find your contributions useful will appreciate 
	    them, and you will know that you have helped people in the 
	    same way that the developers of Wireshark have helped people.
	  </para>
	</listitem>
	<listitem>
	  <para>
	    The developers of Wireshark might improve your changes even more,
		as there's always room for improvements. Or they may implement some 
		advanced things on top of your code, which can be useful for yourself
		too.
	  </para>
	</listitem>
	<listitem>
	  <para>
	    The maintainers and developers of Wireshark will maintain your 
	    code as well, fixing it when API changes or other changes are 
	    made, and generally keeping it in tune with what is happening 
	    with Wireshark. So if Wireshark is updated (which is done often),
		you can get a new Wireshark version from the website and your changes 
		will already be included without any effort for you.
	  </para>
	</listitem>
      </itemizedlist>
    </para>
    <para>
      The Wireshark source code and binary kits for some platforms are all 
      available on the download page of the Wireshark website: 
      <ulink url="&WiresharkDownloadPage;">&WiresharkDownloadPage;</ulink>.
    </para>
  </section>
  
  <section id="ChIntroHelp">
    <title>Reporting problems and getting help</title>
	<para>
      If you have problems, or need help with Wireshark, there are several 
      places that may be of interest to you (well, beside this guide of 
	  course).
	</para>

	<section id="ChIntroHomepage"><title>Website</title>
    <para>
	You will find lot's of useful information on the Wireshark homepage at
	<ulink url="&WiresharkWebSite;">&WiresharkWebSite;</ulink>.
	</para>
	</section>

	<section id="ChIntroWiki"><title>Wiki</title>
    <para>
	The Wireshark Wiki at <ulink 
	url="&WiresharkWikiPage;">&WiresharkWikiPage;</ulink> provides a wide range 
	of information related to Wireshark and packet capturing in general.
	You will find a lot of information not part of this user's guide. For 
	example, there is an explanation how to capture on a switched network, 
	an ongoing effort to build a protocol reference and a lot more. 
	</para>
	<para>
	And best of all, if you would like to contribute your knowledge on a 
	specific topic (maybe a network protocol you know well), you can edit the 
	wiki pages by simply using your webbrowser.
	</para>
	</section>

	<section id="ChIntroFAQ"><title>FAQ</title>
    <para>
	The "Frequently Asked Questions" will list often asked questions and 
	the corresponding answers.
	<note><title>Read the FAQ!</title>
	<para>
	Before sending any mail to the mailing lists below, be sure to read the 
	FAQ, as it will often answer the question(s) you might have. This will save 
	yourself and others a lot of time (keep in mind that a lot of people are 
	subscribed to the mailing lists). 
    </para>
    </note>
	You will find the FAQ inside Wireshark by clicking the menu item 
	Help/Contents and selecting the FAQ page in the upcoming dialog. 
    </para>
    <para>
	An online version is available at the ethereal website:
	<ulink url="&WiresharkFAQPage;">&WiresharkFAQPage;</ulink>. You might 
	prefer this online version, as it's typically more up to date and the HTML 
	format is easier to use.
    </para>
	</section>
	
	<section id="ChIntroMailingLists"><title>Mailing Lists</title>
    <para>
      There are several mailing lists of specific Wireshark topics available:
      <variablelist>
	<varlistentry><term><command>ethereal-announce</command></term>
	  <listitem>
	    <para>
	      This mailing list will inform you about new program 
		  releases, which usually appear about every 4-8 weeks.
	    </para>
	  </listitem>
	</varlistentry>
	<varlistentry><term><command>ethereal-users</command></term>
	  <listitem>
	    <para>
	      This list is for users of Wireshark.  People post 
	      questions about building and using Wireshark, others (hopefully) 
		  provide answers. 
	    </para>
	  </listitem>
	</varlistentry>
	<varlistentry><term><command>ethereal-dev</command></term>
	  <listitem>
	    <para>
	      This list is for Wireshark developers. If you want to start 
	      developing a protocol dissector, join this list.
	    </para>
	  </listitem>
	</varlistentry>
      </variablelist>
      You can subscribe to each of these lists from the Wireshark web site: 
      <ulink url="&WiresharkWebSite;">&WiresharkWebSite;</ulink>.  Simply 
      select the <command>mailing lists</command> link on the left hand 
      side of the site. The lists are archived at the Wireshark web site 
      as well.
	<tip><title>Tip!</title>
	<para>
	You can search in the list archives to see if someone asked the same 
	question some time before and maybe already got an answer. That way you 
	don't have to wait until someone answers your question.
	</para>
	</tip>
    </para>
	</section>
	
	<section><title>Reporting Problems</title>
	<note><title>Note!</title>
	<para>
	Before reporting any problems, please make sure you have installed the 
	latest version of Wireshark.
	</para>
	</note>
    <para>
      When reporting problems with Wireshark, it is helpful if you supply the 
      following information:
      <orderedlist>
	<listitem>
	  <para>
	    The version number of Wireshark and the dependent libraries linked with 
		it, eg GTK+, etc. You can obtain this with the command 
	    <command>ethereal -v</command>.
	  </para>
	</listitem>
	<listitem>
	  <para>
	    Information about the platform you run Wireshark on.
	  </para>
	</listitem>
	<listitem>
	  <para>
	    A detailed description of your problem.
	  </para>
	</listitem>
	<listitem>
	  <para>
		If you get an error/warning message, copy the text of that message 
		(and also a few lines before and after it, if there are some), so 
		others may find the place where things go wrong. Please don't 
		give something like: "I get a warning while doing x" as this won't 
		give a good idea where to look at.
	  </para>
	</listitem>
      </orderedlist>
    </para>
	<note><title>Don't send large files!</title>
	<para>
	Do not send large files (>100KB) to the mailing lists, just place a note 
	that further data is available on request. Large files will only annoy a 
	lot of people on the list who are not interested in your specific problem. 
	If required, you will be asked for further data by the persons who really 
	can help you.
	</para>
	</note>
	<warning><title>Don't send confidential information!</title>
	<para>
	If you send captured data to the mailing lists, be sure they don't contain 
	any sensitive or confidential information like passwords or such.
	</para>
	</warning>
  </section>
  
	<section><title>Reporting Crashes on UNIX/Linux platforms</title>
    <para>
      When reporting crashes with Wireshark, it is helpful if you supply the 
      traceback information (besides the information mentioned in "Reporting 
	  Problems").
    </para>
	  <para>
	    You can obtain this traceback information with the following commands:
	    <programlisting>
<![CDATA[
$ gdb `whereis ethereal | cut -f2 -d: | cut -d' ' -f2` core >& bt.txt
backtrace
^D
$
]]>
		</programlisting>
	    <note>
	      <para>
		Type the characters in the first line verbatim! Those are 
		back-tics there!
	      </para>
	    </note>
	    <note>
	      <para>
		backtrace is a <command>gdb</command> command. You should 
		enter it verbatim after the first line shown above, but it will not be 
		echoed. The ^D 
		(Control-D, that is, press the Control key and the D key 
		together) will cause <command>gdb</command> to exit. This will 
		leave you with a file called 
		<filename>bt.txt</filename> in the current directory. 
		Include the file with your bug report.
	      </para>
	    </note>
	    <note>
	      <para>
		If you do not have <command>gdb</command> available, you 
		will have to check out your operating system's debugger.  
	      </para>
	    </note>
	  </para>
	  <para>
	    You should mail the traceback to the 
		<ulink url="mailto:&WiresharkDevMailList;">&WiresharkDevMailList;</ulink>
	    mailing list.
	  </para>
  </section>
  
	<section><title>Reporting Crashes on Windows platforms</title>
    <para>
	The Windows distributions don't contain the symbol files (.pdb), because 
	they are very large. For this reason it's not possible to create 
	a meaningful backtrace file from it. You should report your crash just
	like other problems, using the mechanism described above.
    </para>
  </section>
  </section>
  
</chapter>
<!-- End of WSUG Chapter 1 -->