wireshark/docbook/wsug_src/WSUG_chapter_introduction.xml

<!-- 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>
	  Wireshark can capture traffic from many different network media types
	  - and despite its name - including wireless LAN as well.
	  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 License</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>System Requirements</title>
    <para>What you'll need to get Wireshark up and running ...</para>

	<section><title>General Remarks</title>
    <para>
	<itemizedlist>
	<listitem><para>The values below are the minimum requirements and only
	"rules of thumb" for use on a moderately used network</para></listitem>
	<listitem><para>Working with a busy network can easily produce huge
	memory and disk space usage! For example: Capturing on a fully saturated
	100MBit/s Ethernet will produce ~ 750MBytes/min! Having a fast processor,
	lots of memory and disk space is a good idea in that case.</para></listitem>
	<listitem><para>If Wireshark is running out of memory it crashes,
	see: <ulink url="http://wiki.wireshark.org/KnownBugs/OutOfMemory"/>
	for details and workarounds</para></listitem>
	<listitem><para>Wireshark won't benefit much from Multiprocessor/Hyperthread
	systems as time consuming tasks like filtering packets are single threaded.
	No rule is without exception: during an "Update list of packets in real
	time" capture, capturing traffic runs in one process and dissecting and
	displaying packets runs in another process - which should benefit from two
	processors.</para></listitem>
	</itemizedlist>
    </para>
    </section>

	<section><title>Microsoft Windows</title>
    <para>
	<itemizedlist>
	<listitem><para>Windows XP Home, XP Pro, XP Tablet PC, XP Media
	Center, Server 2003, Vista, 2008, 7, or 2008 R2
	</para></listitem>
	<listitem><para>Any modern 32-bit x86 or 64-bit AMD64/x86-64 processor.
	</para></listitem>
	<listitem><para>128MB available RAM. Larger capture files require more RAM.
	</para></listitem>
	<listitem><para>75MB available disk space. Capture files require additional disk space.
	</para></listitem>
	<listitem><para>800*600 (1280*1024 or higher recommended) resolution with
	at least 65536 (16bit) colors (256 colors should work if Wireshark is
	installed with the "legacy GTK1" selection of the Wireshark 1.0.x releases)
	</para></listitem>
	<listitem><para>A supported network card for capturing:
	</para>
	<itemizedlist>
	<listitem><para>
	  Ethernet: Any card supported by Windows should work. See the wiki
	  pages on <ulink
	  url="http://wiki.wireshark.org/CaptureSetup/Ethernet">Ethernet
	  capture</ulink> and <ulink
	  url="http://wiki.wireshark.org/CaptureSetup/Offloading">offloading</ulink>
	  for issues that may affect your environment.
	</para></listitem>
	<listitem><para>
	  802.11: See the <ulink
	  url="http://wiki.wireshark.org/CaptureSetup/WLAN#head-02456742c655394c9e948a4c9a59d3441c92782f">Wireshark
	  wiki page</ulink>. Capturing raw 802.11 information may be difficult without special equipment.
	</para></listitem>
	<listitem><para>
	  Other media: See <ulink
	  url="http://wiki.wireshark.org/CaptureSetup/NetworkMedia"/>
	</para></listitem>
	</itemizedlist>
	</listitem>
	</itemizedlist>

	Remarks:

	<itemizedlist>
	<listitem><para>
	  Many older Windows versions are no longer supported for three reasons:
	  None of the developers use those systems which makes support
	  difficult. The libraries Wireshark depends on (GTK, WinPcap, …) have
	  dropped support for older releases. Microsoft <ulink
	  url="http://support.microsoft.com/gp/lifeselect">has also dropped
	  support for these systems</ulink>.
	</para></listitem>
	<listitem><para>
	  Windows 95, 98 and ME are no longer supported. The "old technology"
	  releases of Windows lack memory protection (specifically <ulink
	  url="http://msdn.microsoft.com/en-us/library/aa366898.aspx">VirtualProtect</ulink>)
	  which we use to improve program safety and security. The last known
	  version to work was Ethereal 0.10.14 (which includes WinPcap 3.1). You
	  can get it from <ulink url="http://ethereal.com/download.html" />.
	  According to <ulink
	  url="https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=1130">this
	  bug report</ulink>, you may need to install Ethereal 0.10.0 on some
	  systems.
	</para>
	<para>
          Microsoft retired support for Windows 98 and ME in 2006.
	</para></listitem>
	<listitem><para>
	  Windows NT 4.0 no longer works with Wireshark. The last known version
	  to work was Wireshark 0.99.4 (which includes WinPcap 3.1). You still
	  can get it from <ulink
	  url="http://www.wireshark.org/download/win32/all-versions/wireshark-setup-0.99.4.exe"
	  />.
	</para>
	<para>
	  Microsoft retired support for Windows NT 4.0 in 2004.
	</para></listitem>
	<listitem><para>
	  Windows 2000 no longer works with Wireshark. The last known version
	  to work was Wireshark 1.2.x (which includes WinPcap 4.1.2). You still
	  can get it from <ulink
	  url="http://www.wireshark.org/download/win32/all-versions/" />.
	</para>
	<para>
	  Microsoft retired support for Windows 2000 in 2010.
	</para></listitem>
	<listitem><para>
	  Windows CE and the embedded versions of Windows are not currently supported.
	</para></listitem>
	<listitem><para>
	  Multiple monitor setups are supported but may behave a bit
  	  strangely.
	</para></listitem>
	</itemizedlist>
    </para>
	</section>

	<section><title>Unix / Linux</title>
    <para>
      Wireshark currently runs on most UNIX platforms.
	  The system requirements should be comparable to the Windows values
	  listed above.
    </para>
    <para>
      Binary packages are available for at least the following platforms:
    </para>
	<para>
	<itemizedlist>
	<listitem><para>Apple Mac OS X</para></listitem>
	<listitem><para>Debian GNU/Linux</para></listitem>
	<listitem><para>FreeBSD</para></listitem>
	<listitem><para>Gentoo Linux</para></listitem>
	<listitem><para>HP-UX</para></listitem>
	<listitem><para>Mandriva Linux</para></listitem>
	<listitem><para>NetBSD</para></listitem>
	<listitem><para>OpenPKG</para></listitem>
	<listitem><para>Red Hat Fedora/Enterprise Linux</para></listitem>
	<listitem><para>rPath Linux</para></listitem>
	<listitem><para>Sun Solaris/i386</para></listitem>
	<listitem><para>Sun Solaris/Sparc</para></listitem>
	<listitem><para>Canonical Ubuntu</para></listitem>
	</itemizedlist>
	</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>
	</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 months.
    </para>
    <para>
	If you want to be notified about new Wireshark releases, you should
	subscribe to the wireshark-announce mailing list. You will find more
	details in <xref linkend="ChIntroMailingLists"/>.
    </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 Ethereal (the former name of the Wireshark project)
	  as a way to solve both problems.
    </para>
    <para>
      Ethereal 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 Ethereal 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 Ethereal.
    </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 the project has become very
      long since then, and almost all of them started with a protocol that they
      needed that Wireshark or Ethereal did not already handle. So they copied
      an existing dissector and contributed the code back to the team.
    </para>
    <para>
      In 2006 the project moved house and re-emerged under a new name: Wireshark.
    </para>
    <para>
      In 2008, after ten years of development, Wireshark finally arrived at
      version 1.0. This release was the first deemed complete, with the minimum
      features implemented. Its release coincided with the first Wireshark
      Developer and User Conference, called SharkFest.
    </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 License</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 improvement. 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, besides this guide of
	  course).
	</para>

	<section id="ChIntroHomepage"><title>Website</title>
    <para>
	You will find lots 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 web browser.
	</para>
	</section>

	<section id="ChIntroQA"><title>Q&amp;A Forum</title>
	<para>
	The Wireshark Q and A forum at
	<ulink url="&WiresharkQASite;">&WiresharkQASite;</ulink> offers a resource
	where questions and answers come together. You have the option to search
	what questions were asked before and what answers were given by people who
	knew about the issue. Answers are graded, so you can pick out the best ones
	easily. If your issue isn't discussed before you can post one yourself.
	</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 dialog shown.
    </para>
    <para>
	An online version is available at the Wireshark 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>wireshark-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>wireshark-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>wireshark-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, e.g. GTK+, etc. You can obtain this from the about dialog box
	    of Wireshark, or with the command <command>wireshark -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 wireshark | 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 -->