/help/faq.py
Python | 2107 lines | 2034 code | 28 blank | 45 comment | 45 complexity | ec25bd3ea2d2aaf3475f12acc5b37f08 MD5 | raw file
Possible License(s): GPL-2.0, BSD-3-Clause
- #!/usr/bin/env python
- #
- # faq.py
- #
- # Routines to assemble a FAQ list for the Wireshark web site.
- # Questions and answer content can be found below. Section and
- # question numbers will be automatically generated.
- #
- # $Id: faq.py 36221 2011-03-20 23:09:36Z gerald $
- import sys
- import string
- class faq_section:
- def __init__(self, name, secnum):
- self.name = name
- self.secnum = secnum
- self.qa = []
- self.subsecs = []
- def add_qa(self, question, answer, tag):
- q_num = len(self.qa) + 1
- q_id = "%s.%d" % (self.get_num_string(), q_num)
- self.qa.append( (q_id, question, answer, tag) )
- def get_all_qa(self):
- return self.qa
- def add_subsec(self, subsec):
- self.subsecs.append(subsec)
- def get_all_subsecs(self):
- return self.subsecs
- def get_num_string(self):
- return "%d" % (self.secnum)
- def get_name(self):
- return self.name
- def get_num_name(self):
- return "%s. %s" % (self.get_num_string(), self.name)
- def get_header_level(self):
- return 3
- def print_index(self):
- print("<a href=#sec%s><h%d>%s:</h%d></a>\n" % (self.get_num_string(), self.get_header_level(), self.get_num_name(), self.get_header_level()))
- for qa in self.qa:
- id = qa[0]
- question = qa[1]
- print('<p class="faq_q">')
- print('<a class="faq_qnum" href=#q%s>%s %s</a>\n' % (id, id, question))
- print('</p>')
- for subsec in self.subsecs:
- subsec.print_index()
- def print_contents(self):
- # Table header
- print("""
- <a name="sec%s">
- <h%d>%s</h%d>
- </a>
- """ % (self.get_num_string(), self.get_header_level(), self.get_num_name(), self.get_header_level()))
- # Questions and Answers
- for qa in self.qa:
- id = qa[0]
- question = qa[1]
- answer = qa[2]
- tag = qa[3]
- print('<p class="faq_q">')
- print('<a class="faq_qnum" name=q%s>Q %s:</a>' % (id, id))
- if tag is not None:
- print('<a name=%s>' % tag)
- print('<span>%s</span>' % (question))
- if tag is not None:
- print('</a>')
- print('</p>')
- print('<p class="faq_a">')
- print('<span class="faq_anum">A:</span>\n')
- print(answer)
- print('</p>')
- # Subsections
- for subsec in self.subsecs:
- subsec.print_contents()
- # Table footer
- print("")
- class faq_subsection(faq_section):
- def __init__(self, name, secnum, subsecnum):
- self.name = name
- self.secnum = secnum
- self.subsecnum = subsecnum
- self.qa = []
- self.subsecs = []
- def get_num_string(self):
- return "%d.%d" % (self.secnum, self.subsecnum)
- def get_header_level(self):
- return 2
- class faq_subsubsection(faq_section):
- def __init__(self, name, secnum, subsecnum, subsubsecnum):
- self.name = name
- self.secnum = secnum
- self.subsecnum = subsecnum
- self.subsubsecnum = subsubsecnum
- self.qa = []
- self.subsecs = []
- def get_num_string(self):
- return "%d.%d.%d" % (self.secnum, self.subsecnum, self.subsubsecnum)
- def get_header_level(self):
- return 2
- sec_num = 0
- subsec_num = 0
- subsubsec_num = 0
- sections = []
- current_section = None
- parent_section = None
- grandparent_section = None
- current_question = None
- current_tag = None
- # Make a URL of itself
- def selflink(text):
- return "<a href=\"%s\">%s</a>" % (text, text)
- # Add a section
- def section(name):
- global sec_num
- global subsec_num
- global subsubsec_num
- global current_section
- global grandparent_section
- assert not current_question
- sec_num = sec_num + 1
- subsec_num = 0
- subsubsec_num = 0
- sec = faq_section(name, sec_num)
- sections.append(sec)
- current_section = sec
- grandparent_section = sec
- # Add a subsection
- def subsection(name):
- global subsec_num
- global subsubsec_num
- global current_section
- global parent_section
- global grandparent_section
- assert not current_question
- subsec_num = subsec_num + 1
- subsubsec_num = 0
- sec = faq_subsection(name, sec_num, subsec_num)
- grandparent_section.add_subsec(sec)
- current_section = sec
- parent_section = sec
- # Add a subsubsection
- def subsubsection(name):
- global subsubsec_num
- global current_section
- global parent_section
- assert not current_question
- subsubsec_num = subsubsec_num + 1
- sec = faq_subsubsection(name, sec_num, subsec_num, subsubsec_num)
- parent_section.add_subsec(sec)
- current_section = sec
- # Add a question
- def question(text, tag=None):
- global current_question
- global current_tag
- assert current_section
- assert not current_question
- assert not current_tag
- current_question = text
- current_tag = tag
- # Add an answer
- def answer(text):
- global current_question
- global current_tag
- assert current_section
- assert current_question
- current_section.add_qa(current_question, text, current_tag)
- current_question = None
- current_tag = None
- # Create the index
- def create_index():
- print("""
- <a name="index">
- <h1>Index</h1>
- </a>
- """)
- for sec in sections:
- sec.print_index()
- print("""
- """)
- # Print result
- def create_output(header='', footer=''):
- print(header)
- create_index()
- for sec in sections:
- sec.print_contents()
- print(footer)
- def main():
- header = '''\
- <?xml version="1.0" encoding="UTF-8"?>
- <!DOCTYPE html
- PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
- "DTD/xhtml1-strict.dtd">
- <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
- <head>
- <title>Wireshark FAQ</title>
- <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
- </head>
- <body>
- '''
- footer = '''\
- </body>
- </html>
- '''
- if len(sys.argv) > 1 and sys.argv[1] == '-b': # Only print the document body
- header = ''
- footer = ''
- create_output(header, footer)
- #################################################################
- section("General Questions")
- #################################################################
- question("What is Wireshark?")
- answer("""
- Wireshark® is a network protocol analyzer. It lets you capture and
- interactively browse the traffic running on a computer network. It has
- a rich and powerful feature set and is world's most popular tool of its
- kind. It runs on most computing platforms including Windows, OS X,
- Linux, and UNIX. Network professionals, security experts, developers,
- and educators around the world use it regularly. It is freely available
- as open source, and is released under the GNU General Public License
- version 2.
- <br />
- It is developed and maintained by a global team of protocol experts, and
- it is an example of a
- <a href="http://en.wikipedia.org/wiki/Disruptive_technology">disruptive
- technology</a>.
- <br />
- Wireshark used to be known as Ethereal®. See the next question
- for details about the name change. If you're still using Ethereal, it
- is <a href="http://www.ethereal.com/appnotes/enpa-sa-00024.html">strongly
- recommended that you upgrade to Wireshark</a>.
- <br />
- For more information, please see the
- <a href="/about.html">About Wireshark</a>
- page.
- """)
- question("What's up with the name change? Is Wireshark a fork?")
- answer("""
- In May of 2006, Gerald Combs (the original author of Ethereal)
- went to work for CACE Technologies (best known for WinPcap).
- Unfortunately, he had to leave the Ethereal trademarks behind.
- <br />
- This left the project in an awkward position. The only reasonable way
- to ensure the continued success of the project was to change the name.
- This is how Wireshark was born.
- <br />
- Wireshark is almost (but not quite) a fork. Normally a "fork" of an open source
- project results in two names, web sites, development teams, support
- infrastructures, etc. This is the case with Wireshark except for one notable
- exception -- every member of the core development team is now working on
- Wireshark. There has been no active development on Ethereal since the name
- change. Several parts of the Ethereal web site (such as the mailing lists,
- source code repository, and build farm) have gone offline.
- <br />
- More information on the name change can be found here:
- <ul class="item_list">
- <li><href url="http://www.prweb.com/releases/2006/6/prweb396098.htm" name="Original press release">
- <li><href url="http://trends.newsforge.com/article.pl?sid=06/06/09/1349255&from=rss" name="NewsForge article">
- <li>Many other articles in <href url="bibliography.html" name="our bibliography">
- </ul>
- """)
- question("Where can I get help?")
- answer("""
- Community support is available on the wireshark-users mailing list.
- Subscription information and archives for all of Wireshark's mailing
- lists can be found at %s. An IRC channel dedicated to Wireshark can
- be found at %s.
- <br />
- Self-paced and instructor-led training is available at
- <a href="http://www.wiresharku.com">Wireshark University</a>. A
- certification program will be announced in Q3 2007.
- <br />
- Commercial support and development services are available
- from <a href="http://www.cacetech.com/">CACE Technologies</a>.
- """ % (selflink("https://www.wireshark.org/mailman/listinfo"),
- selflink("irc://irc.freenode.net/wireshark")
- ))
- question("What kind of shark is Wireshark?")
- answer("""
- <i>carcharodon photoshopia</i>.
- """)
- question("How is Wireshark pronounced, spelled and capitalized?")
- answer("""
- Wireshark is pronounced as the word <i>wire</i> followed immediately by
- the word <i>shark</i>. Exact pronunciation and emphasis may vary
- depending on your locale (e.g. Arkansas).
- <br />
- It's spelled with a capital <i>W</i>, followed by a lower-case
- <i>ireshark</i>. It is not a CamelCase word, i.e., <i>WireShark</i>
- is incorrect.
- """)
- question("How much does Wireshark cost?", "but_thats_not_all")
- answer("""
- Wireshark is "free software"; you can download it without paying any
- license fee. The version of Wireshark you download isn't a "demo"
- version, with limitations not present in a "full" version; it
- <em>is</em> the full version.
- <br />
- The license under which Wireshark is issued is <a
- href="http://www.gnu.org/licenses/gpl.html">the GNU General Public
- License version 2</a>. See <a href="http://www.gnu.org/licenses/gpl-faq.html">the
- GNU GPL FAQ</a> for some more information.
- """)
- question("But I just paid someone on eBay for a copy of Wireshark! Did I get ripped off?")
- answer("""
- That depends. Did they provide any sort of value-added product or service, such
- as installation support, installation media, training, trace file analysis, or
- funky-colored shark-themed socks? Probably not.
- <br />
- Wireshark is <a href="/download.html">available for anyone to download,
- absolutely free, at any time</a>. Paying for a copy implies that you should
- get something for your money.
- """)
- question("Can I use Wireshark commercially?")
- answer("""
- Yes, if, for example, you mean "I work for a commercial organization;
- can I use Wireshark to capture and analyze network traffic in our
- company's networks or in our customer's networks?"
- <br />
- If you mean "Can I use Wireshark as part of my commercial product?", see
- <a href="#derived_work_gpl">the next entry in the FAQ</a>.
- """)
- question("Can I use Wireshark as part of my commercial product?",
- "derived_work_gpl")
- answer("""
- As noted, Wireshark is licensed under <a
- href="http://www.gnu.org/licenses/gpl.html">the GNU General Public
- License</a>. The GPL imposes conditions on your use of GPL'ed code in
- your own products; you cannot, for example, make a "derived work" from
- Wireshark, by making modifications to it, and then sell the resulting
- derived work and not allow recipients to give away the resulting work.
- You must also make the changes you've made to the Wireshark source
- available to all recipients of your modified version; those changes
- must also be licensed under the terms of the GPL. See the <a
- href="http://www.gnu.org/licenses/gpl-faq.html">GPL FAQ</a> for more
- details; in particular, note the answer to <a
- href="http://www.gnu.org/licenses/gpl-faq.html#GPLCommercially">the
- question about modifying a GPLed program and selling it
- commercially</a>, and <a
- href="http://www.gnu.org/licenses/gpl-faq.html#LinkingWithGPL">the
- question about linking GPLed code with other code to make a proprietary
- program</a>.
- <br />
- You can combine a GPLed program such as Wireshark and a commercial
- program as long as they communicate "at arm's length", as per <a
- href="http://www.gnu.org/licenses/gpl-faq.html#GPLInProprietarySystem">this
- item in the GPL FAQ</a>.
- <br />
- We recommend keeping Wireshark and your product completely separate,
- communicating over sockets or pipes. If you're loading any part of
- Wireshark as a DLL, you're probably doing it wrong.
- """)
- question("What protocols are currently supported?")
- answer("""
- There are currently hundreds of supported
- protocols and media. Details can be found in the
- <a href="/docs/man-pages/wireshark.html">wireshark(1)</a> man page.
- """)
- question("Are there any plans to support {your favorite protocol}?")
- answer("""
- Support for particular protocols is added to Wireshark as a result of
- people contributing that support; no formal plans for adding support for
- particular protocols in particular future releases exist.
- """)
- question("""Can Wireshark read capture files from {your favorite network
- analyzer}?""")
- answer("""
- Support for particular protocols is added to Wireshark as a result of
- people contributing that support; no formal plans for adding support for
- particular protocols in particular future releases exist.
- <br />
- If a network analyzer writes out files in a format already supported by
- Wireshark (e.g., in libpcap format), Wireshark may already be able to read
- them, unless the analyzer has added its own proprietary extensions to
- that format.
- <br />
- If a network analyzer writes out files in its own format, or has added
- proprietary extensions to another format, in order to make Wireshark read
- captures from that network analyzer, we would either have to have a
- specification for the file format, or the extensions, sufficient to give
- us enough information to read the parts of the file relevant to
- Wireshark, or would need at least one capture file in that format
- <strong>AND</strong> a detailed textual analysis of the packets in that
- capture file (showing packet time stamps, packet lengths, and the
- top-level packet header) in order to reverse-engineer the file
- format.
- <br />
- Note that there is no guarantee that we will be able to reverse-engineer
- a capture file format.
- """)
- question("What devices can Wireshark use to capture packets?")
- answer("""
- Wireshark can read live data from Ethernet, Token-Ring, FDDI, serial (PPP
- and SLIP) (if the OS on which it's running allows Wireshark to do so),
- 802.11 wireless LAN (if the OS on which it's running allows Wireshark to
- do so), ATM connections (if the OS on which it's running allows Wireshark
- to do so), and the "any" device supported on Linux by recent versions of
- libpcap.
- <br />
- See <a href="http://wiki.wireshark.org/CaptureSetup/NetworkMedia">the list of
- supported capture media on various OSes</a> for details (several items
- in there say "Unknown", which doesn't mean "Wireshark can't capture on
- them", it means "we don't know whether it can capture on them"; we
- expect that it will be able to capture on many of them, but we haven't
- tried it ourselves - if you try one of those types and it works, please
- update the wiki page accordingly.
- <br />
- It can also read a variety of capture file formats, including:
- <ul>
- <li> AG Group/WildPackets EtherPeek/TokenPeek/AiroPeek/EtherHelp/Packet Grabber captures
- <li> AIX's iptrace captures
- <li> Accellent's 5Views LAN agent output
- <li> Cinco Networks NetXRay captures
- <li> Cisco Secure Intrusion Detection System IPLog output
- <li> CoSine L2 debug output
- <li> DBS Etherwatch VMS text output
- <li> Endace Measurement Systems' ERF format captures
- <li> EyeSDN USB S0 traces
- <li> HP-UX nettl captures
- <li> ISDN4BSD project i4btrace captures
- <li> Linux Bluez Bluetooth stack hcidump -w traces
- <li> Lucent/Ascend router debug output
- <li> Microsoft Network Monitor captures
- <li> Network Associates Windows-based Sniffer captures
- <li> Network General/Network Associates DOS-based Sniffer (compressed or uncompressed) captures
- <li> Network Instruments Observer version 9 captures
- <li> Novell LANalyzer captures
- <li> RADCOM's WAN/LAN analyzer captures
- <li> Shomiti/Finisar Surveyor captures
- <li> Toshiba's ISDN routers dump output
- <li> VMS TCPIPtrace/TCPtrace/UCX$TRACE output
- <li> Visual Networks' Visual UpTime traffic capture
- <li> libpcap, tcpdump and various other tools using tcpdump's capture format
- <li> snoop and atmsnoop output
- </ul>
- so that it can read traces from various network types, as captured by
- other applications or equipment, even if it cannot itself capture on
- those network types.
- """)
- question("""
- Does Wireshark work on Windows Vista or Windows Server 2008?
- """)
- answer("""
- Yes, but if you want to capture packets as a normal user, you must make sure
- npf.sys is loaded. Wireshark's installer enables this by default. This is not a
- concern if you run Wireshark as Administrator, but this is discouraged. See the
- <a
- href="http://wiki.wireshark.org/CaptureSetup/CapturePrivileges#windows">CapturePrivileges</a>
- page on the wiki for more details.
- """)
- #################################################################
- section("Downloading Wireshark")
- #################################################################
- question("""Why do I get an error when I try to run the Win32 installer?""")
- answer("""
- The program you used to download it may have downloaded it incorrectly.
- Web browsers and download accelerators sometimes may do this.
- <br />
- Try downloading it with, for example:
- <ul>
- <li>Wget, for which Windows binaries are available from <a
- href="http://www.christopherlewis.com/WGet/WGetFiles.htm">Christopher Lewis</a>
- or
- <a href="http://www.jensroesner.de/wgetgui/">wGetGUI</a>, which offers a GUI
- interface that uses wget;
- <li>WS_FTP from <a href="http://www.ipswitch.com/">Ipswitch</a>,
- <li>the <tt>ftp</tt> command that comes with Windows.
- </ul>
- If you use the <tt>ftp</tt> command, make sure you do the transfer in
- binary mode rather than ASCII mode, by using the <tt>binary</tt> command
- before transferring the file.
- """)
- #################################################################
- section("Installing Wireshark")
- #################################################################
- question("""I installed the Wireshark RPM (or other package); why did
- it install TShark but not Wireshark?""")
- answer("""
- Many distributions have separate Wireshark packages, one for non-GUI
- components such as TShark, editcap, dumpcap, etc. and one for the GUI.
- If this is the case on your system, there's probably a separate package
- named <tt>wireshark-gnome</tt> or <tt>wireshark-gtk+</tt>. Find it and
- install it.
- """)
- #################################################################
- section("Building Wireshark")
- #################################################################
- question("""I have libpcap installed; why did the configure script not
- find pcap.h or bpf.h?""")
- answer("""
- Are you sure pcap.h and bpf.h are installed? The official distribution
- of libpcap only installs the libpcap.a library file when "make install"
- is run. To install pcap.h and bpf.h, you must run "make install-incl".
- If you're running Debian or Redhat, make sure you have the "libpcap-dev"
- or "libpcap-devel" packages installed.
- <br />
- It's also possible that pcap.h and bpf.h have been installed in a strange
- location. If this is the case, you may have to tweak aclocal.m4.
- """)
- question("""
- Why do I get the error
- <blockquote><samp>dftest_DEPENDENCIES was already defined in condition TRUE,
- which implies condition HAVE_PLUGINS_TRUE</samp></blockquote>
- when I try to build Wireshark from SVN or a SVN snapshot?
- """)
- answer("""
- You probably have automake 1.5 installed on your machine (the command
- <kbd>automake --version</kbd> will report the version of automake on
- your machine). There is a bug in that version of automake that causes
- this problem; upgrade to a later version of automake (1.6 or later).
- """)
- question("""
- Why does the linker fail with a number of "Output line too long." messages
- followed by linker errors when I try to build Wireshark?
- """)
- answer("""
- The version of the <tt>sed</tt> command on your system is incapable of
- handling very long lines. On Solaris, for example,
- <tt>/usr/bin/sed</tt> has a line length limit too low to allow
- <tt>libtool</tt> to work; <tt>/usr/xpg4/bin/sed</tt> can handle it, as
- can GNU <tt>sed</tt> if you have it installed.
- <br />
- On Solaris, changing your command search path to search
- <tt>/usr/xpg4/bin</tt> before <tt>/usr/bin</tt> should make the problem
- go away; on any platform on which you have this problem, installing GNU
- <tt>sed</tt> and changing your command path to search the directory in
- which it is installed before searching the directory with the version of
- <tt>sed</tt> that came with the OS should make the problem go away.
- """)
- question("""
- When I try to build Wireshark on Solaris, why does the link fail
- complaining that <tt>plugin_list</tt> is undefined?
- """)
- answer("""
- This appears to be due to a problem with some versions of the GTK+ and
- GLib packages from www.sunfreeware.org; un-install those packages, and
- try getting the 1.2.10 versions from that site, or the versions from <a
- href="http://www.thewrittenword.com">The Written Word</a>, or the
- versions from Sun's GNOME distribution, or the versions from the
- supplemental software CD that comes with the Solaris media kit, or build
- them from source from <a href="http://www.gtk.org/">the GTK Web
- site</a>. Then re-run the configuration script, and try rebuilding
- Wireshark. (If you get the 1.2.10 versions from www.sunfreeware.org, and
- the problem persists, un-install them and try installing one of the
- other versions mentioned.)
- """)
- question("""
- When I try to build Wireshark on Windows, why does the build fail because
- of conflicts between <tt>winsock.h</tt> and <tt>winsock2.h</tt>?
- """)
- answer("""
- As of Wireshark 0.9.5, you must install WinPcap 2.3 or later, and the
- corresponding version of the developer's pack, in order to be able to
- compile Wireshark; it will not compile with older versions of the
- developer's pack. The symptoms of this failure are conflicts between
- definitions in <tt>winsock.h</tt> and in <tt>winsock2.h</tt>; Wireshark
- uses <tt>winsock2.h</tt>, but pre-2.3 versions of the WinPcap
- developer's packet use <tt>winsock.h</tt>. (2.3 uses
- <tt>winsock2.h</tt>, so if Wireshark were to use <tt>winsock.h</tt>, it
- would not be able to build with current versions of the WinPcap
- developer's pack.)
- <br />
- Note that the installed version of the developer's pack should be the
- same version as the version of WinPcap you have installed.
- """)
- #################################################################
- section("Starting Wireshark")
- #################################################################
- question("""Why does Wireshark crash with a Bus Error when I try to run
- it on Solaris 8?""")
- answer("""
- Some versions of the GTK+ library from www.sunfreeware.org appear to be
- buggy, causing Wireshark to drop core with a Bus Error. Un-install those
- packages, and try getting the 1.2.10 version from that site, or the
- version from <a href="http://www.thewrittenword.com">The Written
- Word</a>, or the version from Sun's GNOME distribution, or the version
- from the supplemental software CD that comes with the Solaris media kit,
- or build it from source from <a href="http://www.gtk.org/">the GTK Web
- site</a>. Update the GLib library to the 1.2.10 version, from the same
- source, as well. (If you get the 1.2.10 versions from
- www.sunfreeware.org, and the problem persists, un-install them and try
- installing one of the other versions mentioned.)
- <br />
- Similar problems may exist with older versions of GTK+ for earlier
- versions of Solaris.
- """)
- question("""When I run Wireshark on Windows NT, why does it die with a Dr.
- Watson error, reporting an "Integer division by zero" exception, when I
- start it?""")
- answer("""
- In at least some case, this appears to be due to using the
- default VGA driver; if that's not the correct driver for your video
- card, try running the correct driver for your video card.
- """)
- question("""When I try to run Wireshark, why does it complain about
- <tt>sprint_realloc_objid</tt> being undefined?""")
- answer("""
- Wireshark can only be linked with version 4.2.2 or later of UCD SNMP.
- Your version of Wireshark was dynamically linked with such a version of
- UCD SNMP; however, you have an older version of UCD SNMP installed,
- which means that when Wireshark is run, it tries to link to the older
- version, and fails. You will have to replace that version of UCD SNMP
- with version 4.2.2 or a later version.
- """)
- question("""
- I've installed Wireshark from Fink on Mac OS X; why is it very slow to
- start up?
- """)
- answer("""
- When an application is installed on OS X, prior to 10.4, it is usually
- "prebound" to speed up launching the application. (That's what the
- "Optimizing" phase of installation is.)
- <br />
- Fink normally performs prebinding automatically when you install a
- package. However, in some rare cases, for whatever reason the prebinding
- caches get corrupt, and then not only does prebinding fail, but startup
- actually becomes much slower, because the system tries in vain to
- perform prebinding "on the fly" as you launch the application. This
- fails, causing sometimes huge delays.
- <br />
- To fix the prebinding caches, run the command
- <pre>
- sudo /sw/var/lib/fink/prebound/update-package-prebinding.pl -f
- </pre>
- """)
- #################################################################
- section("Crashes and other fatal errors")
- #################################################################
- question("""
- I have an XXX network card on my machine; if I try to capture on it, why
- does my machine crash or reset itself?
- """)
- answer("""
- This is almost certainly a problem with one or more of:
- <ul>
- <li>the operating system you're using;
- <li>the device driver for the interface you're using;
- <li>the libpcap/WinPcap library and, if this is Windows, the WinPcap
- device driver;
- </ul>
- so:
- <ul>
- <li>if you are using Windows, see <a
- href="http://www.winpcap.org/contact.htm">the WinPcap support
- page</a> - check the "Submitting bugs" section;
- <li>if you are using some Linux distribution, some version of BSD, or
- some other UNIX-flavored OS, you should report the problem to the
- company or organization that produces the OS (in the case of a Linux
- distribution, report the problem to whoever produces the distribution).
- </ul>
- """)
- question("""
- Why does my machine crash or reset itself when I select "Start" from the
- "Capture" menu or select "Preferences" from the "Edit" menu?
- """)
- answer("""
- Both of those operations cause Wireshark to try to build a list of the
- interfaces that it can open; it does so by getting a list of interfaces
- and trying to open them. There is probably an OS, driver, or, for
- Windows, WinPcap bug that causes the system to crash when this happens;
- see the previous question.
- """)
- #################################################################
- section("Capturing packets")
- #################################################################
- question("""When I use Wireshark to capture packets, why do I see only
- packets to and from my machine, or not see all the traffic I'm expecting
- to see from or to the machine I'm trying to monitor?""", "promiscsniff")
- answer("""
- This might be because the interface on which you're capturing is plugged
- into an Ethernet or Token Ring switch; on a switched network, unicast
- traffic between two ports will not necessarily appear on other ports -
- only broadcast and multicast traffic will be sent to all ports.
- <br />
- Note that even if your machine is plugged into a hub, the "hub" may be
- a switched hub, in which case you're still on a switched network.
- <br />
- Note also that on the Linksys Web site, they say that their
- auto-sensing hubs "broadcast the 10Mb packets to the port that operate
- at 10Mb only and broadcast the 100Mb packets to the ports that operate
- at 100Mb only", which would indicate that if you sniff on a 10Mb port,
- you will not see traffic coming sent to a 100Mb port, and <i>vice
- versa</i>. This problem has also been reported for Netgear dual-speed
- hubs, and may exist for other "auto-sensing" or "dual-speed" hubs.
- <br />
- Some switches have the ability to replicate all traffic on all ports to
- a single port so that you can plug your analyzer into that single port to
- sniff all traffic. You would have to check the documentation for the
- switch to see if this is possible and, if so, to see how to do this.
- See <a href="http://wiki.wireshark.org/SwitchReference">the switch
- reference page</a> on <a href="http://wiki.wireshark.org/">the Wireshark
- Wiki</a> for information on some switches. (Note that it's a Wiki, so
- you can update or fix that information, or add additional information on
- those switches or information on new switches, yourself.)
- <br />
- Note also that many firewall/NAT boxes have a switch built into them;
- this includes many of the "cable/DSL router" boxes. If you have a box
- of that sort, that has a switch with some number of Ethernet ports into
- which you plug machines on your network, and another Ethernet port used
- to connect to a cable or DSL modem, you can, at least, sniff traffic
- between the machines on your network and the Internet by plugging
- the Ethernet port on the router going to the modem, the Ethernet port on
- the modem, and the machine on which you're running Wireshark into a hub
- (make sure it's not a switching hub, and that, if it's a dual-speed hub,
- all three of those ports are running at the same speed.
- <br />
- If your machine is <em>not</em> plugged into a switched network or a
- dual-speed hub, or it is plugged into a switched network but the port is
- set up to have all traffic replicated to it, the problem might be that
- the network interface on which you're capturing doesn't support
- "promiscuous" mode, or because your OS can't put the interface into
- promiscuous mode. Normally, network interfaces supply to the host only:
- <ul>
- <li>packets sent to one of that host's link-layer addresses;
- <li>broadcast packets;
- <li>multicast packets sent to a multicast address that the host has
- configured the interface to accept.
- </ul>
- Most network interfaces can also be put in "promiscuous" mode, in which
- they supply to the host all network packets they see. Wireshark will try
- to put the interface on which it's capturing into promiscuous mode
- unless the "Capture packets in promiscuous mode" option is turned off in
- the "Capture Options" dialog box, and TShark will try to put the
- interface on which it's capturing into promiscuous mode unless the
- <tt>-p</tt> option was specified. However, some network interfaces
- don't support promiscuous mode, and some OSes might not allow interfaces
- to be put into promiscuous mode.
- <br />
- If the interface is not running in promiscuous mode, it won't see any
- traffic that isn't intended to be seen by your machine. It
- <strong>will</strong> see broadcast packets, and multicast packets sent
- to a multicast MAC address the interface is set up to receive.
- <br />
- You should ask the vendor of your network interface whether it supports
- promiscuous mode. If it does, you should ask whoever supplied the
- driver for the interface (the vendor, or the supplier of the OS you're
- running on your machine) whether it supports promiscuous mode with that
- network interface.
- <br />
- In the case of token ring interfaces, the drivers for some of them, on
- Windows, may require you to enable promiscuous mode in order to capture
- in promiscuous mode. See <a
- href="http://wiki.wireshark.org/CaptureSetup/TokenRing">the Wireshark
- Wiki item on Token Ring capturing</a> for details.
- <br />
- In the case of wireless LAN interfaces, it appears that, when those
- interfaces are promiscuously sniffing, they're running in a
- significantly different mode from the mode that they run in when they're
- just acting as network interfaces (to the extent that it would be a
- significant effort for those drivers to support for promiscuously
- sniffing <em>and</em> acting as regular network interfaces at the same
- time), so it may be that Windows drivers for those interfaces don't
- support promiscuous mode.
- """)
- question("""When I capture with Wireshark, why can't I see any TCP
- packets other than packets to and from my machine, even though another
- analyzer on the network sees those packets?""")
- answer("""
- You're probably not seeing <em>any</em> packets other than unicast
- packets to or from your machine, and broadcast and multicast packets; a
- switch will normally send to a port only unicast traffic sent to the MAC
- address for the interface on that port, and broadcast and multicast
- traffic - it won't send to that port unicast traffic sent to a MAC
- address for some other interface - and a network interface not in
- promiscuous mode will receive only unicast traffic sent to the MAC
- address for that interface, broadcast traffic, and multicast traffic
- sent to a multicast MAC address the interface is set up to receive.
- <br />
- TCP doesn't use broadcast or multicast, so you will only see your own
- TCP traffic, but UDP services may use broadcast or multicast so you'll
- see some UDP traffic - however, this is not a problem with TCP traffic,
- it's a problem with unicast traffic, as you also won't see all UDP
- traffic between other machines.
- <br />
- I.e., this is probably <a href="#promiscsniff">the same question
- as this earlier one</a>; see the response to that question.
- """)
- question("""Why am I only seeing ARP packets when I try to capture
- traffic?""")
- answer("""
- You're probably on a switched network, and running Wireshark on a machine
- that's not sending traffic to the switch and not being sent any traffic
- from other machines on the switch. ARP packets are often broadcast
- packets, which are sent to all switch ports.
- <br />
- I.e., this is probably <a href="#promiscsniff">the same question
- as this earlier one</a>; see the response to that question.
- """)
- question("""
- Why am I not seeing any traffic when I try to capture traffic?""")
- answer("""
- Is the machine running Wireshark sending out any traffic on the network
- interface on which you're capturing, or receiving any traffic on that
- network, or is there any broadcast traffic on the network or multicast
- traffic to a multicast group to which the machine running Wireshark
- belongs?
- <br />
- If not, this may just be a problem with promiscuous sniffing, either due
- to running on a switched network or a dual-speed hub, or due to problems
- with the interface not supporting promiscuous mode; see the response to
- <a href="#promiscsniff">this earlier question</a>.
- <br />
- Otherwise, on Windows, see the response to <a href="#capprobwin">this
- question</a> and, on a UNIX-flavored OS, see the response to <a
- href="#capprobunix">this question</a>.
- """)
- question("""
- Can Wireshark capture on (my T1/E1 line, SS7 links, etc.)?
- """)
- answer("""
- Wireshark can only capture on devices supported by libpcap/WinPcap. On
- most OSes, only devices that can act as network interfaces of the type
- that support IP are supported as capture devices for libpcap/WinPcap,
- although the device doesn't necessarily have to be running as an IP
- interface in order to support traffic capture.
- <br />
- On Linux and FreeBSD, libpcap 0.8 and later support the API for <a
- href="http://www.endace.com/products.htm">Endace Measurement Systems'
- DAG cards</a>, so that a system with one of those cards, and its driver
- and libraries, installed can capture traffic with those cards with
- libpcap-based applications. You would either have to have a version of
- Wireshark built with that version of libpcap, or a dynamically-linked
- version of Wireshark and a shared libpcap library with DAG support, in
- order to do so with Wireshark. You should ask Endace whether that could
- be used to capture traffic on, for example, your T1/E1 link.
- <br />
- See <a href="http://wiki.wireshark.org/CaptureSetup/SS7">the SS7 capture
- setup page</a> on <a href="http://wiki.wireshark.org/">the Wireshark
- Wiki</a> for current information on capturing SS7 traffic on TDM
- links.
- """)
- question("""How do I put an interface into promiscuous mode?""")
- answer("""
- By not disabling promiscuous mode when running Wireshark or TShark.
- <br />
- Note, however, that:
- <ul>
- <li>the form of promiscuous mode that libpcap (the library that
- programs such as tcpdump, Wireshark, etc. use to do packet capture)
- turns on will <strong>not</strong> necessarily be shown if you run
- <tt>ifconfig</tt> on the interface on a UNIX system;
- <li>some network interfaces might not support promiscuous mode, and some
- drivers might not allow promiscuous mode to be turned on - see <a
- href="#promiscsniff">this earlier question</a> for more information on
- that;
- <li>the fact that you're not seeing any traffic, or are only seeing
- broadcast traffic, or aren't seeing any non-broadcast traffic other than
- traffic to or from the machine running Wireshark, does not mean that
- promiscuous mode isn't on - see <a href="#promiscsniff">this earlier
- question</a> for more information on that.
- </ul>
- I.e., this is probably <a href="#promiscsniff">the same question
- as this earlier one</a>; see the response to that question.
- """)
- question("""
- I can set a display filter just fine; why don't capture filters work?
- """)
- answer("""
- Capture filters currently use a different syntax than display filters. Here's
- the corresponding section from the
- <a href="/docs/man-pages/wireshark.html">wireshark(1)</a>
- man page:
- <br />
- "Display filters in Wireshark are very powerful; more fields are filterable
- in Wireshark than in other protocol analyzers, and the syntax you can
- use to create your filters is richer. As Wireshark progresses, expect
- more and more protocol fields to be allowed in display filters.
- <br />
- Packet capturing is performed with the pcap library. The capture filter
- syntax follows the rules of the pcap library. This syntax is different
- from the display filter syntax."
- <br />
- The capture filter syntax used by libpcap can be found in the
- <a href="http://www.tcpdump.org/tcpdump_man.html">tcpdump(8)</a>
- man page.
- """)
- question("""I'm entering valid capture filters; why do I still get
- "parse error" errors?""")
- answer("""
- There is a bug in some versions of libpcap/WinPcap that cause it to
- report parse errors even for valid expressions if a previous filter
- expression was invalid and got a parse error.
- <br />
- Try exiting and restarting Wireshark; if you are using a version of
- libpcap/WinPcap with this bug, this will "erase" its memory of the
- previous parse error. If the capture filter that got the "parse error"
- now works, the earlier error with that filter was probably due to this
- bug.
- <br />
- The bug was fixed in libpcap 0.6; 0.4[.x] and 0.5[.x] versions of
- libpcap have this bug, but 0.6[.x] and later versions don't.
- <br />
- Versions of WinPcap prior to 2.3 are based on pre-0.6 versions of
- libpcap, and have this bug; WinPcap 2.3 is based on libpcap 0.6.2, and
- doesn't have this bug.
- <br />
- If you are running Wireshark on a UNIX-flavored platform, run "wireshark
- -v", or select "About Wireshark..." from the "Help" menu in Wireshark, to
- see what version of libpcap it's using. If it's not 0.6 or later, you
- will need either to upgrade your OS to get a later version of libpcap,
- or will need to build and install a later version of libpcap from <a
- href="http://www.tcpdump.org/">the tcpdump.org Web site</a> and then
- recompile Wireshark from source with that later version of libpcap.
- <br />
- If you are running Wireshark on Windows with a pre-2.3 version of
- WinPcap, you will need to un-install WinPcap and then download and
- install WinPcap 2.3.
- """)
- question("""
- How can I capture packets with CRC errors?
- """)
- answer("""
- Wireshark can capture only the packets that the packet capture library -
- libpcap on UNIX-flavored OSes, and the WinPcap port to Windows of libpcap
- on Windows - can capture, and libpcap/WinPcap can capture only the
- packets that the OS's raw packet capture mechanism (or the WinPcap
- driver, and the underlying OS networking code and network interface
- drivers, on Windows) will allow it to capture.
- <br />
- Unless the OS always supplies packets with errors such as invalid CRCs
- to the raw packet capture mechanism, or can be configured to do so,
- invalid CRCs to the raw packet capture mechanism, Wireshark - and other
- programs that capture raw packets, such as tcpdump - cannot capture
- those packets. You will have to determine whether your OS needs to be
- so configured and, if so, can be so configured, configure it if
- necessary and possible, and make whatever changes to libpcap and the
- packet capture program you're using are necessary, if any, to support
- capturing those packets.
- <br />
- Most OSes probably do <strong>not</strong> support capturing packets
- with invalid CRCs on Ethernet, and probably do not support it on most
- other link-layer types. Some drivers on some OSes do support it, such
- as some Ethernet drivers on FreeBSD; in those OSes, you might always get
- those packets, or you might only get them if you capture in promiscuous
- mode (you'd have to determine which is the case).
- <br />
- Note that libpcap does not currently supply to programs that use it an
- indication of whether the packet's CRC was invalid (because the drivers
- themselves do not supply that information to the raw packet capture
- mechanism); therefore, Wireshark will not indicate which packets had CRC
- errors unless the FCS was captured (see the next question) and you're
- using Wireshark 0.9.15 and later, in which case Wireshark will check the
- CRC and indicate whether it's correct or not.
- """)
- question("""
- How can I capture entire frames, including the FCS?
- """)
- answer("""
- Wireshark can only capture data that the packet capture library -
- libpcap on UNIX-flavored OSes, and the WinPcap port to Windows of
- libpcap on Windows - can capture, and libpcap/WinPcap can capture only
- the data that the OS's raw packet capture mechanism (or the WinPcap
- driver, and the underlying OS networking code and network interface
- drivers, on Windows) will allow it to capture.
- <br />
- For any particular link-layer network type, unless the OS supplies the
- FCS of a frame as part of the frame, or can be configured to do so,
- Wireshark - and other programs that capture raw packets, such as tcpdump
- - cannot capture the FCS of a frame. You will have to determine whether
- your OS needs to be so configured and, if so, can be so configured,
- configure it if necessary and possible, and make whatever changes to
- libpcap and the packet capture program you're using are necessary, if
- any, to support capturing the FCS of a frame.
- <br />
- Most OSes do <strong>not</strong> support capturing the FCS of a frame
- on Ethernet, and probably do not support it on most other link-layer
- types. Some drivres on some OSes do support it, such as some (all?)
- Ethernet drivers on NetBSD and possibly the driver for Apple's gigabit
- Ethernet interface in Mac OS X; in those OSes, you might always get the
- FCS, or you might only get the FCS if you capture in promiscuous mode
- (you'd have to determine which is the case).
- <br />
- Versions of Wireshark prior to 0.9.15 will not treat an Ethernet FCS in a
- captured packet as an FCS. 0.9.15 and later will attempt to determine
- whether there's an FCS at the end of the frame and, if it thinks there
- is, will display it as such, and will check whether it's the correct
- CRC-32 value or not.
- """)
- question("""
- I'm capturing packets on a machine on a VLAN; why don't the packets I'm
- capturing have VLAN tags?
- """)
- answer("""
- You might be capturing on what might be called a "VLAN interface" - the
- way a particular OS makes VLANs plug into the networking stack might,
- for example, be to have a network device object for the physical
- interface, which takes VLAN packets, strips off the VLAN header and
- constructs an Ethernet header, and passes that packet to an internal
- network device object for the VLAN, which then passes the packets onto
- various higher-level protocol implementations.
- <br />
- In order to see the raw Ethernet packets, rather than "de-VLANized"
- packets, you would have to capture not on the virtual interface for the
- VLAN, but on the interface corresponding to the physical network device,
- if possible. See <a
- href="http://wiki.wireshark.org/CaptureSetup/VLAN">the Wireshark Wiki
- item on VLAN capturing</a> for details.
- """)
- question("""
- Why does Wireshark hang after I stop a capture?
- """)
- answer("""
- The most likely reason for this is that Wireshark is trying to look up an
- IP address in the capture to convert it to a name (so that, for example,
- it can display the name in the source address or destination address
- columns), and that lookup process is taking a very long time.
- <br />
- Wireshark calls a routine in the OS of the machine on which it's running
- to convert of IP addresses to the corresponding names. That routine
- probably does one or more of:
- <ul><li>a search of a system file listing IP addresses and names;
- <li>a lookup using DNS;
- <li>on UNIX systems, a lookup using NIS;
- <li>on Windows systems, a NetBIOS-over-TCP query.
- </ul>
- If a DNS server that's used in an address lookup is not responding, the
- lookup will fail, but will only fail after a timeout while the system
- routine waits for a reply.
- <br />
- In addition, on Windows systems, if the DNS lookup of the address fails,
- either because the server isn't responding or because there are no
- records in the DNS that could be used to map the address to a name, a
- NetBIOS-over-TCP query will be made. That query involves sending a
- message to the NetBIOS-over-TCP name service on that machine, asking for
- the name and other information about the machine. If the machine isn't
- running software that responds to those queries - for example, many
- non-Windows machines wouldn't be running that software - the lookup will
- only fail after a timeout. Those timeouts can cause the lookup to take
- a long time.
- <br />
- If you disable network address-to-name translation - for example, by
- turning off the "Enable network name resolution" option in the "Capture
- Options" dialog box for starting a network capture - the lookups of the
- address won't be done, which may speed up the process of reading the
- capture file after the capture is stopped. You can make that setting
- the default by selecting "Preferences" from the "Edit" menu, turning off
- the "Enable network name resolution" option in the "Name resolution"
- options in the preferences disalog box, and using the "Save" button in
- that dialog box; note that this will save <em>all</em> your current
- preference settings.
- <br />
- If Wireshark hangs when reading a capture even with network name
- resolution turned off, there might, for example, be a bug in one of
- Wireshark's dissectors for a protocol causing it to loop infinitely. If
- you're not running the most recent release of Wireshark, you should first
- upgrade to that release, as, if there's a bug of that sort, it might've
- been fixed in a release after the one you're running. If the hang
- occurs in the most recent release of Wireshark, the bug should be
- reported to <a href="mailto:wireshark-dev@wireshark.org">the Wireshark
- developers' mailing list</a> at <tt>wireshark-dev@wireshark.org</tt>.
- <br />
- On UNIX-flavored OSes, please try to force Wireshark to dump core, by
- sending it a <tt>SIGABRT</tt> signal (usually signal 6) with the
- <tt>kill</tt> command, and then get a stack trace if you have a debugger
- installed. A stack trace can be obtained by using your debugger
- (<tt>gdb</tt> in this example), the Wireshark binary, and the resulting
- core file. Here's an example of how to use the gdb command
- <tt>backtrace</tt> to do so.
- <pre>
- $ gdb wireshark core
- (gdb) backtrace
- ..... prints the stack trace
- (gdb) quit
- $
- </pre>
- The core dump file may be named "wireshark.core" rather than "core" on
- some platforms (e.g., BSD systems).
- <br />
- Also, if at all possible, please send a copy of the capture file that
- caused the problem; when capturing packets, Wireshark normally writes
- captured packets to a temporary file, which will probably be in
- <tt>/tmp</tt> or <tt>/var/tmp</tt> on UNIX-flavored OSes, <tt>\TEMP</tt>
- on the main system disk (normally <tt>C:</tt>) on Windows 9x/Me/NT 4.0,
- and <tt>\Documents and Settings\</tt><var>your login
- name</var><tt>\Local Settings\Temp</tt> on the main system disk on
- Windows 2000/Windows XP/Windows Server 2003, so the capture file will
- probably be there. It will have a name of the form,
- <tt>wireshark_iface_YYYYmmddHHMMSS_XXXXXX</tt>. Please don't send
- a trace file greater than 1 MB when compressed; instead, make it
- available via FTP or HTTP, or say it's available but leave it up to a
- developer to ask for it. If the trace file contains sensitive
- information (e.g., passwords), then please do not send it.
- """)
- #################################################################
- section("Capturing packets on Windows")
- #################################################################
- question("""
- I'm running Wireshark on Windows; why does some network interface on my
- machine not show up in the list of interfaces in the "Interface:" field
- in the dialog box popped up by "Capture->Start", and/or why does
- Wireshark give me an error if I try to capture on that interface?
- """, "capprobwin")
- answer("""
- If you are running Wireshark on Windows NT 4.0, Windows 2000, Windows XP,
- or Windows Server 2003, and this is the first time you have run a
- WinPcap-based program (such as Wireshark, or TShark, or WinDump, or
- Analyzer, or...) since the machine was rebooted, you need to run that
- program from an account with administrator privileges; once you have run
- such a program, you will not need administrator privileges to run any
- such programs until you reboot.
- <br />
- If you are running on Windows Windows 2000/Windows XP/Windows Server
- 2003 and have administrator privileges or a WinPcap-based program has
- been run with those privileges since the machine rebooted, this problem
- <em>might</em> clear up if you completely un-install WinPcap and then
- re-install it.
- <br />
- If that doesn't work, then note that Wireshark relies on the WinPcap
- library, on the WinPcap device driver, and on the facilities that come
- with the OS on which it's running in order to do captures.
- <br />
- Therefore, if the OS, the WinPcap library, or the WinPcap driver don't
- support capturing on a particular network interface device, Wireshark
- won't be able to capture on that device.
- <br />
- Note that:
- <ol>
- <li>2.02 and earlier versions of the WinPcap driver and library that
- Wireshark uses for packet capture didn't support Token Ring interfaces;
- versions 2.1 and later support Token Ring, and the current version of
- Wireshark works with (and, in fact, requires) WinPcap 2.1 or later.
- <br />
- If you are having problems capturing on Token Ring interfaces, and you
- have WinPcap 2.02 or an earlier version of WinPcap installed, you should
- uninstall WinPcap, download and install the current version of WinPcap,
- and then install the latest version of Wireshark.
- <br >
- <li>WinPcap 2.3 has problems supporting PPP WAN interfaces on Windows NT
- 4.0, Windows 2000, Windows XP, and Windows Server 2003, and, to avoid
- those problems, support for PPP WAN interfaces on those versions of
- Windows has been disabled in WinPcap 3.0. Regular dial-up lines, ISDN
- lines, ADSL connections using PPPoE or PPPoA, and various other lines
- such as T1/E1 lines are all PPP interfaces, so those interfaces might
- not show up on the list of interfaces in the "Capture Options"
- dialog on those OSes.
- <br />
- On Windows 2000, Windows XP, and Windows Server 2003, but
- <strong>not</strong> Windows NT 4.0 or Windows Vista Beta 1, you should
- be able to capture on the "GenericDialupAdapter" with WinPcap 3.1. (3.1
- beta releases called it the "NdisWanAdapter"; if you're using a 3.1 beta
- release, you should un-install it and install the final 3.1 release.)
- See <a href="http://wiki.wireshark.org/CaptureSetup/PPP">the Wireshark
- Wiki item on PPP capturing</a> for details.
- <br />
- <li>WinPcap prior to 3.0 does not support multiprocessor machines (note
- that machines with a single multi-threaded processor, such as Intel's
- new multi-threaded x86 processors, are multiprocessor machines as far as
- the OS and WinPcap are concerned), and recent 2.x versions of WinPcap
- refuse to operate if they detect that they're running on a
- multiprocessor machine, which means that they may not show any network
- interfaces. You will need to use WinPcap 3.0 to capture on a
- multiprocessor machine.
- </ol>
- <br />
- If an interface doesn't show up in the list of interfaces in the
- "Interface:" field, and you know the name of the interface, try entering
- that name in the "Interface:" field and capturing on that device.
- <br />
- If the attempt to capture on it succeeds, the interface is somehow not
- being reported by the mechanism Wireshark uses to get a list of
- interfaces. Try listing the interfaces with WinDump; see <a
- href="http://www.windump.org/">the WinDump Web site</a>
- for information on using WinDump.
- <br />
- You would run WinDump with the <tt>-D</tt> flag; if it lists the
- interface, please report this to <a
- href="mailto:wireshark-dev@wireshark.org">wireshark-dev@wireshark.org</a>
- giving full details of the problem, including
- <ul>
- <li>the operating system you're using, and the version of that operating
- system;
- <li>the type of network device you're using;
- <li>the output of WinDump.
- </ul>
- If WinDump does <em>not</em> list the interface,
- this is almost certainly a problem with one or more of:
- <ul>
- <li>the operating system you're using;
- <li>the device driver for the interface you're using;
- <li>the WinPcap library and/or the WinPcap device driver;
- </ul>
- so first check <a href="http://www.winpcap.org/misc/faq.htm">the
- WinPcap FAQ</a> or <a
- href="http://www.mirrors.wiretapped.net/security/packet-capture/winpcap/misc/faq.htm">
- the Wiretapped.net mirror of that FAQ</a>, to see if your problem is
- mentioned there. If not, then see <a
- href="http://www.winpcap.org/contact.htm">the WinPcap support page</a>
- - check the "Submitting bugs" section.
- <br />
- If you are having trouble capturing on a particular network interface,
- first try capturing on that device with WinDump; see <a
- href="http://www.windump.org/">the WinDump Web site</a>
- for information on using WinDump.
- <br />
- If you can capture on the interface with WinDump, send mail to <a
- href="mailto:wireshark-users@wireshark.org">wireshark-users@wireshark.org</a>
- giving full details of the problem, including
- <ul>
- <li>the operating system you're using, and the version of that operating
- system;
- <li>the type of network device you're using;
- <li>the error message you get from Wireshark.
- </ul>
- If you <em>cannot</em> capture on the interface with WinDump,
- this is almost certainly a problem with one or more of:
- <ul>
- <li>the operating system you're using;
- <li>the device driver for the interface you're using;
- <li>the WinPcap library and/or the WinPcap device driver;
- </ul>
- so first check <a href="http://www.winpcap.org/misc/faq.htm">the
- WinPcap FAQ</a> or <a
- href="http://www.mirrors.wiretapped.net/security/packet-capture/winpcap/misc/faq.htm">
- the Wiretapped.net mirror of that FAQ</a>, to see if your problem is
- mentioned there. If not, then see <a
- href="http://www.winpcap.org/contact.htm">the WinPcap support page</a>
- - check the "Submitting bugs" section.
- <br />
- You may also want to ask the <a
- href="mailto:wireshark-users@wireshark.org">wireshark-users@wireshark.org</a>
- and the <a
- href="mailto:winpcap-users@winpcap.org">winpcap-users@winpcap.org</a>
- mailing lists to see if anybody happens to know about the problem and
- know a workaround or fix for the problem. (Note that you will have to
- subscribe to that list in order to be allowed to mail to it; see <a
- href="http://www.winpcap.org/contact.htm">the WinPcap support
- page</a> for information on the mailing list.) In your mail,
- please give full details of the problem, as described above, and also
- indicate that the problem occurs with WinDump, not just with Wireshark.
- """)
- question("""
- I'm running Wireshark on Windows; why do no network interfaces show up in
- the list of interfaces in the "Interface:" field in the dialog box
- popped up by "Capture->Start"?
- """)
- answer("""
- This is really <a href="#capprobwin">the same question as a previous
- one</a>; see the response to that question.
- """)
- question("""
- I'm running Wireshark on Windows; why doesn't my serial port/ADSL
- modem/ISDN modem show up in the list of interfaces in the "Interface:"
- field in the dialog box popped up by "Capture->Start"?
- """)
- answer("""
- Internet access on those devices is often done with the Point-to-Point
- (PPP) protocol; WinPcap 2.3 has problems supporting PPP WAN interfaces
- on Windows NT 4.0, Windows 2000, Windows XP, and Windows Server 2003,
- and, to avoid those problems, support for PPP WAN interfaces on those
- versions of Windows has been disabled in WinPcap 3.0.
- <br />
- On Windows 2000, Windows XP, and Windows Server 2003, but
- <strong>not</strong> Windows NT 4.0 or Windows Vista Beta 1, you should
- be able to capture on the "GenericDialupAdapter" with WinPcap 3.1. (3.1
- beta releases called it the "NdisWanAdapter"; if you're using a 3.1 beta
- release, you should un-install it and install the final 3.1 release.)
- See <a href="http://wiki.wireshark.org/CaptureSetup/PPP">the Wireshark
- Wiki item on PPP capturing</a> for details.
- """)
- question("""
- I'm running Wireshark on Windows NT 4.0/Windows 2000/Windows XP/Windows
- Server 2003; my machine has a PPP (dial-up POTS, ISDN, etc.) interface,
- and it shows up in the "Interface" item in the "Capture Options" dialog
- box. Why can no packets be sent on or received from that network while
- I'm trying to capture traffic on that interface?""", "nt_ppp_sniff")
- answer("""
- Some versions of WinPcap have problems with PPP WAN interfaces on
- Windows NT 4.0, Windows 2000, Windows XP, and Windows Server 2003; one
- symptom that may be seen is that attempts to capture in promiscuous mode
- on the interface cause the interface to be incapable of sending or
- receiving packets. You can disable promiscuous mode using the
- <tt>-p</tt> command-line flag or the item in the "Capture Preferences"
- dialog box, but this may mean that outgoing packets, or incoming
- packets, won't be seen in the capture.
- <br />
- On Windows 2000, Windows XP, and Windows Server 2003, but
- <strong>not</strong> Windows NT 4.0 or Windows Vista Beta 1, you should
- be able to capture on the "GenericDialupAdapter" with WinPcap 3.1. (3.1
- beta releases called it the "NdisWanAdapter"; if you're using a 3.1 beta
- release, you should un-install it and install the final 3.1 release.)
- See <a href="http://wiki.wireshark.org/CaptureSetup/PPP">the Wireshark
- Wiki item on PPP capturing</a> for details.
- """)
- question("""
- I'm running Wireshark on Windows; why am I not seeing any traffic being
- sent by the machine running Wireshark?""")
- answer("""
- If you are running some form of VPN client software, it might be causing
- this problem; people have seen this problem when they have Check Point's
- VPN software installed on their machine. If that's the cause of the
- problem, you will have to remove the VPN software in order to have
- Wireshark (or any other application using WinPcap) see outgoing packets;
- unfortunately, neither we nor the WinPcap developers know any way to
- make WinPcap and the VPN software work well together.
- <br />
- Also, some drivers for Windows (especially some wireless network
- interface drivers) apparently do not, when running in promiscuous mode,
- arrange that outgoing packets are delivered to the software that
- requested that the interface run promiscuously; try turning promiscuous
- mode off.
- """)
- question("""
- When I capture on Windows in promiscuous mode, I can see packets other
- than those sent to or from my machine; however, those packets show up
- with a "Short Frame" indication, unlike packets to or from my machine.
- What should I do to arrange that I see those packets in their entirety?
- """)
- answer("""
- In at least some cases, this appears to be the result of PGPnet running
- on the network interface on which you're capturing; turn it off on that
- interface.
- """)
- question("""
- I'm trying to capture 802.11 traffic on Windows; why am I not seeing any
- packets?
- """, "win802_11promisc")
- answer("""
- At least some 802.11 card drivers on Windows appear not to see any
- packets if they're running in promiscuous mode. Try turning promiscuous
- mode off; you'll only be able to see packets sent by and received by
- your machine, not third-party traffic, and it'll look like Ethernet
- traffic and won't include any management or control frames, but that's a
- limitation of the card drivers.
- <br />
- See <a
- href="http://www.micro-logix.com/WinPcap/Supported.asp">MicroLogix's
- list of cards supported with WinPcap</a> for information on
- support of various adapters and drivers with WinPcap.
- """)
- question("""
- I'm trying to capture 802.11 traffic on Windows; why am I seeing packets
- received by the machine on which I'm capturing traffic, but not packets
- sent by that machine?
- """)
- answer("""
- This appears to be another problem with promiscuous mode; try turning it
- off.
- """)
- question("""
- I'm trying to capture Ethernet VLAN traffic on Windows, and I'm
- capturing on a "raw" Ethernet device rather than a "VLAN interface", so
- that I can see the VLAN headers; why am I seeing packets received by the
- machine on which I'm capturing traffic, but not packets sent by that
- machine?
- """)
- answer("""
- The way the Windows networking code works probably means that packets
- are sent on a "VLAN interface" rather than the "raw" device, so packets
- sent by the machine will only be seen when you capture on the "VLAN
- interface". If so, you will be unable to see outgoing packets when
- capturing on the "raw" device, so you are stuck with a choice between
- seeing VLAN headers and seeing outgoing packets.
- """)
- #################################################################
- section("Capturing packets on UN*Xes")
- #################################################################
- question("""
- I'm running Wireshark on a UNIX-flavored OS; why does some network
- interface on my machine not show up in the list of interfaces in the
- "Interface:" field in the dialog box popped up by "Capture->Start",
- and/or why does Wireshark give me an error if I try to capture on that
- interface? """, "capprobunix")
- answer("""
- You may need to run Wireshark from an account with sufficient privileges
- to capture packets, such as the super-user account, or may need to give
- your account sufficient privileges to capture packets. Only those
- interfaces that Wireshark can open for capturing show up in that list; if
- you don't have sufficient privileges to capture on any interfaces, no
- interfaces will show up in the list. See
- <a href="http://wiki.wireshark.org/CaptureSetup/CapturePrivileges">the
- Wireshark Wiki item on capture privileges</a> for details on how to give
- a particular account or account group capture privileges on platforms
- where that can be done.
- <br />
- If you are running Wireshark from an account with sufficient privileges,
- then note that Wireshark relies on the libpcap library, and on the
- facilities that come with the OS on which it's running in order to do
- captures. On some OSes, those facilities aren't present by default; see
- <a href="http://wiki.wireshark.org/CaptureSetup/CaptureSupport">the
- Wireshark Wiki item on adding capture support</a> for details.
- <br />
- And, even if you're running with an account that has sufficient
- privileges to capture, and capture support is present in your OS, if the
- OS or the libpcap library don't support capturing on a particular
- network interface device or particular types of devices, Wireshark won't
- be able to capture on that device.
- <br />
- On Solaris, note that libpcap 0.6.2 and earlier didn't support Token
- Ring interfaces; the current version, 0.7.2, does support Token Ring,
- and the current version of Wireshark works with libpcap 0.7.2 and later.
- <br />
- If an interface doesn't show up in the list of interfaces in the
- "Interface:" field, and you know the name of the interface, try entering
- that name in the "Interface:" field and capturing on that device.
- <br />
- If the attempt to capture on it succeeds, the interface is somehow not
- being reported by the mechanism Wireshark uses to get a list of
- interfaces; please report this to <a
- href="mailto:wireshark-dev@wireshark.org">wireshark-dev@wireshark.org</a>
- giving full details of the problem, including
- <ul>
- <li>the operating system you're using, and the version of that operating
- system (for Linux, give both the version number of the kernel and the
- name and version number of the distribution you're using);
- <li>the type of network device you're using.
- </ul>
- If you are having trouble capturing on a particular network interface,
- and you've made sure that (on platforms that require it) you've arranged
- that packet capture support is present, as per the above, first try
- capturing on that device with <tt>tcpdump</tt>.
- <br />
- If you can capture on the interface with <tt>tcpdump</tt>, send mail to
- <a
- href="mailto:wireshark-users@wireshark.org">wireshark-users@wireshark.org</a>
- giving full details of the problem, including
- <ul>
- <li>the operating system you're using, and the version of that operating
- system (for Linux, give both the version number of the kernel and the
- name and version number of the distribution you're using);
- <li>the type of network device you're using;
- <li>the error message you get from Wireshark.
- </ul>
- If you <em>cannot</em> capture on the interface with <tt>tcpdump</tt>,
- this is almost certainly a problem with one or more of:
- <ul>
- <li>the operating system you're using;
- <li>the device driver for the interface you're using;
- <li>the libpcap library;
- </ul>
- so you should report the problem to the company or organization that
- produces the OS (in the case of a Linux distribution, report the problem
- to whoever produces the distribution).
- <br />
- You may also want to ask the <a
- href="mailto:wireshark-users@wireshark.org">wireshark-users@wireshark.org</a>
- and the <a
- href="mailto:tcpdump-workers@lists.tcpdump.org">tcpdump-workers@lists.tcpdump.org</a>
- mailing lists to see if anybody happens to know about the problem and
- know a workaround or fix for the problem. In your mail, please give
- full details of the problem, as described above, and also indicate that
- the problem occurs with <tt>tcpdump</tt> not just with Wireshark.
- """)
- question("""
- I'm running Wireshark on a UNIX-flavored OS; why do no network interfaces
- show up in the list of interfaces in the "Interface:" field in the
- dialog box popped up by "Capture->Start"?
- """)
- answer("""
- This is really <a href="#capprobunix">the same question as the previous
- one</a>; see the response to that question.
- """)
- question("""I'm capturing packets on Linux; why do the time stamps have
- only 100ms resolution, rather than 1us resolution?""")
- answer("""
- Wireshark gets time stamps from libpcap/WinPcap, and
- libpcap/WinPcap get them from the OS kernel, so Wireshark - and any other
- program using libpcap, such as tcpdump - is at the mercy of the time
- stamping code in the OS for time stamps.
- <br />
- At least on x86-based machines, Linux can get high-resolution time
- stamps on newer processors with the Time Stamp Counter (TSC) register;
- for example, Intel x86 processors, starting with the Pentium Pro, and
- including all x86 processors since then, have had a TSC, and other
- vendors probably added the TSC at some point to their families of x86
- processors.
- The Linux kernel must be configured with the CONFIG_X86_TSC option
- enabled in order to use the TSC. Make sure this option is enabled in
- your kernel.
- <br />
- In addition, some Linux distributions may have bugs in their versions of
- the kernel that cause packets not to be given high-resolution time
- stamps even if the TSC is enabled. See, for example, bug 61111 for Red
- Hat Linux 7.2. If your distribution has a bug such as this, you may
- have to run a standard kernel from kernel.org in order to get
- high-resolution time stamps.
- """)
- #################################################################
- section("Capturing packets on wireless LANs")
- #################################################################
- question("""
- How can I capture raw 802.11 frames, including non-data (management,
- beacon) frames?
- """, "raw_80211_sniff")
- answer("""
- That depends on the operating system on which you're running, and on the
- 802.11 interface on which you're capturing.
- <br />
- This would probably require that you capture in promiscuous mode or in
- the mode called "monitor mode" or "RFMON mode". On some platforms, or
- with some cards, this might require that you capture in monitor mode -
- promiscuous mode might not be sufficient. If you want to capture
- traffic on networks other than the one with which you're associated, you
- will have to capture in monitor mode.
- <br />
- Not all operating systems support capturing non-data packets and, even
- on operating systems that do support it, not all drivers, and thus not
- all interfaces, support it. Even on those that do, monitor mode might
- not be supported by the operating system or by the drivers for all
- interfaces.
- <br />
- <strong>NOTE:</strong> an interface running in monitor mode will, on
- most if not all platforms, not be able to act as a regular network
- interface; putting it into monitor mode will, in effect, take your
- machine off of whatever network it's on as long as the interface is in
- monitor mode, allowing it only to passively capture packets.
- <br />
- This means that you should disable name resolution when capturing in
- monitor mode; otherwise, when Wireshark (or TShark, or tcpdump) tries
- to display IP addresses as host names, it will probably block for a long
- time trying to resolve the name because it will not be able to
- communicate with any DNS or NIS servers.
- <br />
- See <a
- href="http://wiki.wireshark.org/CaptureSetup/WLAN">the Wireshark
- Wiki item on 802.11 capturing</a> for details.
- """)
- question("""
- How do I capture on an 802.11 device in monitor mode?""",
- "monitor")
- answer("""
- Whether you will be able to capture in monitor mode depends on the
- operating system, adapter, and driver you're using.
- See <a href="#raw_80211_sniff">the previous question</a> for information
- on monitor mode, including a link to the Wireshark Wiki page that gives
- details on 802.11 capturing.
- """)
- #################################################################
- section("Viewing traffic")
- #################################################################
- question("Why am I seeing lots of packets with incorrect TCP checksums?")
- answer("""
- If the packets that have incorrect TCP checksums are all being sent by
- the machine on which Wireshark is running, this is probably because the
- network interface on which you're capturing does TCP checksum
- offloading. That means that the TCP checksum is added to the packet by
- the network interface, not by the OS's TCP/IP stack; when capturing on
- an interface, packets being sent by the host on which you're capturing
- are directly handed to the capture interface by the OS, which means that
- they are handed to the capture interface without a TCP checksum being
- added to them.
- <br />
- The only way to prevent this from happening would be to disable TCP
- checksum offloading, but
- <ol>
- <li>that might not even be possible on some OSes;
- <li>that could reduce networking performance significantly.
- </ol>
- However, you can disable the check that Wireshark does of the TCP
- checksum, so that it won't report any packets as having TCP checksum
- errors, and so that it won't refuse to do TCP reassembly due to a packet
- having an incorrect TCP checksum. That can be set as an Wireshark
- preference by selecting "Preferences" from the "Edit" menu, opening up
- the "Protocols" list in the left-hand pane of the "Preferences" dialog
- box, selecting "TCP", from that list, turning off the "Check the
- validity of the TCP checksum when possible" option, clicking "Save" if
- you want to save that setting in your preference file, and clicking
- "OK".
- <br />
- It can also be set on the Wireshark or TShark command line with a
- <tt>-o tcp.check_checksum:false</tt> command-line flag, or manually set
- in your preferences file by adding a <tt>tcp.check_checksum:false</tt>
- line.
- """)
- question("""
- I've just installed Wireshark, and the traffic on my local LAN
- is boring. Where can I find more interesting captures?
- """)
- answer("""
- We have a collection of strange and exotic sample capture
- files at %s""" % (selflink("http://wiki.wireshark.org/SampleCaptures")))
- question("""
- Why doesn't Wireshark correctly identify RTP packets? It shows them
- only as UDP.""")
- answer("""
- Wireshark can identify a UDP datagram as containing a packet of a
- particular protocol running atop UDP only if
- <ol>
- <li> The protocol in question has a particular standard port
- number, and the UDP source or destination port number is that port
- <li> Packets of that protocol can be identified by looking for a
- "signature" of some type in the packet - i.e., some data
- that, if Wireshark finds it in some particular part of a
- packet, means that the packet is almost certainly a packet of
- that type.
- <li> Some <em>other</em> traffic earlier in the capture indicated that,
- for example, UDP traffic between two particular addresses and
- ports will be RTP traffic.
- </ol>
- RTP doesn't have a standard port number, so 1) doesn't work; it doesn't,
- as far as I know, have any "signature", so 2) doesn't work.
- <br />
- That leaves 3). If there's RTSP traffic that sets up an RTP session,
- then, at least in some cases, the RTSP dissector will set things up so
- that subsequent RTP traffic will be identified. Currently, that's the
- only place we do that; there may be other places.
- <br />
- However, there will always be places where Wireshark is simply
- <b>incapable</b> of deducing that a given UDP flow is RTP; a mechanism
- would be needed to allow the user to specify that a given conversation
- should be treated as RTP. As of Wireshark 0.8.16, such a mechanism
- exists; if you select a UDP or TCP packet, the right mouse button menu
- will have a "Decode As..." menu item, which will pop up a dialog box
- letting you specify that the source port, the destination port, or both
- the source and destination ports of the packet should be dissected as
- some particular protocol.
- """)
- question("""
- Why doesn't Wireshark show Yahoo Messenger packets in captures that
- contain Yahoo Messenger traffic?""")
- answer("""
- Wireshark only recognizes as Yahoo Messenger traffic packets to or from TCP
- port 3050 that begin with "YPNS", "YHOO", or "YMSG". TCP segments that
- start with the middle of a Yahoo Messenger packet that takes more than one
- TCP segment will not be recognized as Yahoo Messenger packets (even if the
- TCP segment also contains the beginning of another Yahoo Messenger
- packet).
- """)
- #################################################################
- section("Filtering traffic")
- #################################################################
- question("""I saved a filter and tried to use its name to filter the
- display; why do I get an "Unexpected end of filter string" error?""")
- answer("""
- You cannot use the name of a saved display filter as a filter. To
- filter the display, you can enter a display filter expression -
- <strong>not</strong> the name of a saved display filter - in the
- "Filter:" box at the bottom of the display, and type the <Enter> key or
- press the "Apply" button (that does not require you to have a saved
- filter), or, if you want to use a saved filter, you can press the
- "Filter:" button, select the filter in the dialog box that pops up, and
- press the "OK" button.""")
- question("""
- How can I search for, or filter, packets that have a particular string
- anywhere in them?
- """)
- answer("""
- If you want to do this when capturing, you can't. That's a feature that
- would be hard to implement in capture filters without changes to the
- capture filter code, which, on many platforms, is in the OS kernel and,
- on other platforms, is in the libpcap library.
- <br />
- After capture, you can search for text by selecting <i>Edit→Find
- Packet...</i> and making sure <i>String</i> is selected. Alternately, you can
- use the "contains" display filter operator or "matches" operator if it's
- supported on your system.
- """)
- question("""
- How do I filter a capture to see traffic for virus XXX?
- """)
- answer("""
- For some viruses/worms there might be a capture filter to recognize the
- virus traffic. Check the <a
- href="http://wiki.wireshark.org/CaptureFilters">CaptureFilters</a> page
- on the <a href="http://wiki.wireshark.org/">Wireshark Wiki</a> to see if
- anybody's added such a filter.
- <br />
- Note that Wireshark was not designed to be an intrusion detection system;
- you might be able to use it as an IDS, but in most cases software
- designed to be an IDS, such as <a href="http://www.snort.org/">Snort</a>
- or <a href="http://www.prelude-ids.org/">Prelude</a>, will probably work
- better.
- <br />
- The <a href="http://www.bleedingsnort.com/">Bleeding Edge of Snort</a>
- has a collection of signatures for Snort to detect various viruses,
- worms, and the like.
- """)
- #################################################################
- if __name__ == '__main__':
- sys.exit(main())
- #################################################################