Wireshark Documentation - Bandwidthco Computer Security

Wireshark Documentation - Bandwidthco Computer Security
Wireshark User's Guide
28442 for Wireshark 1.0.0
Ulf Lamping,
Richard Sharpe, NS Computer Software and Services P/L
Ed Warnicke,
Wireshark User's Guide: 28442
for Wireshark 1.0.0
by Ulf Lamping, Richard Sharpe, and Ed Warnicke
Copyright © 2004-2008 Ulf Lamping Richard Sharpe Ed Warnicke
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU General Public License, Version 2 or any later version published by the Free Software Foundation.
All logos and trademarks in this document are property of their respective owner.
Table of Contents
Preface ..................................................................................................................... ix
1. Foreword ...................................................................................................... ix
2. Who should read this document? ........................................................................ x
3. Acknowledgements ......................................................................................... xi
4. About this document ...................................................................................... xii
5. Where to get the latest copy of this document? ................................................... xiii
6. Providing feedback about this document ........................................................... xiv
1. Introduction ............................................................................................................ 1
1.1. What is Wireshark? ....................................................................................... 1
1.1.1. Some intended purposes ....................................................................... 1
1.1.2. Features ............................................................................................ 1
1.1.3. Live capture from many different network media ...................................... 2
1.1.4. Import files from many other capture programs ........................................ 2
1.1.5. Export files for many other capture programs ........................................... 2
1.1.6. Many protocol decoders ....................................................................... 3
1.1.7. Open Source Software ......................................................................... 3
1.1.8. What Wireshark is not ......................................................................... 3
1.2. System Requirements ..................................................................................... 4
1.2.1. General Remarks ................................................................................ 4
1.2.2. Microsoft Windows ............................................................................. 4
1.2.3. Unix / Linux ...................................................................................... 5
1.3. Where to get Wireshark? ................................................................................ 6
1.4. A brief history of Wireshark ............................................................................ 7
1.5. Development and maintenance of Wireshark ...................................................... 8
1.6. Reporting problems and getting help ................................................................. 9
1.6.1. Website ............................................................................................ 9
1.6.2. Wiki ................................................................................................. 9
1.6.3. FAQ ................................................................................................. 9
1.6.4. Mailing Lists ..................................................................................... 9
1.6.5. Reporting Problems ........................................................................... 10
1.6.6. Reporting Crashes on UNIX/Linux platforms ......................................... 10
1.6.7. Reporting Crashes on Windows platforms ............................................. 11
2. Building and Installing Wireshark ............................................................................. 13
2.1. Introduction ............................................................................................... 13
2.2. Obtaining the source and binary distributions .................................................... 14
2.3. Before you build Wireshark under UNIX ......................................................... 15
2.4. Building Wireshark from source under UNIX ................................................... 18
2.5. Installing the binaries under UNIX ................................................................. 20
2.5.1. Installing from rpm's under Red Hat and alike ........................................ 20
2.5.2. Installing from deb's under Debian ....................................................... 20
2.5.3. Installing from portage under Gentoo Linux ........................................... 20
2.5.4. Installing from packages under FreeBSD ............................................... 20
2.6. Troubleshooting during the install on Unix ....................................................... 21
2.7. Building from source under Windows ............................................................. 22
2.8. Installing Wireshark under Windows .............................................................. 23
2.8.1. Install Wireshark .............................................................................. 23
2.8.2. Manual WinPcap Installation .............................................................. 25
2.8.3. Update Wireshark ............................................................................. 25
2.8.4. Update WinPcap ............................................................................... 25
2.8.5. Uninstall Wireshark .......................................................................... 26
2.8.6. Uninstall WinPcap ............................................................................ 26
3. User Interface ....................................................................................................... 28
3.1. Introduction ............................................................................................... 28
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3.2. Start Wireshark ........................................................................................... 29
3.3. The Main window ....................................................................................... 30
3.3.1. Main Window Navigation .................................................................. 31
3.4. The Menu .................................................................................................. 32
3.5. The "File" menu .......................................................................................... 34
3.6. The "Edit" menu ......................................................................................... 37
3.7. The "View" menu ........................................................................................ 39
3.8. The "Go" menu ........................................................................................... 44
3.9. The "Capture" menu .................................................................................... 46
3.10. The "Analyze" menu .................................................................................. 48
3.11. The "Statistics" menu ................................................................................. 50
3.12. The "Tools" menu ...................................................................................... 53
3.13. The "Help" menu ....................................................................................... 54
3.14. The "Main" toolbar .................................................................................... 56
3.15. The "Filter" toolbar .................................................................................... 59
3.16. The "Packet List" pane ............................................................................... 61
3.17. The "Packet Details" pane ........................................................................... 62
3.18. The "Packet Bytes" pane ............................................................................. 63
3.19. The Statusbar ............................................................................................ 64
4. Capturing Live Network Data .................................................................................. 67
4.1. Introduction ............................................................................................... 67
4.2. Prerequisites ............................................................................................... 68
4.3. Start Capturing ........................................................................................... 69
4.4. The "Capture Interfaces" dialog box ................................................................ 70
4.5. The "Capture Options" dialog box .................................................................. 72
4.5.1. Capture frame .................................................................................. 73
4.5.2. Capture File(s) frame ......................................................................... 74
4.5.3. Stop Capture... frame ......................................................................... 74
4.5.4. Display Options frame ....................................................................... 75
4.5.5. Name Resolution frame ..................................................................... 75
4.5.6. Buttons ........................................................................................... 75
4.6. The "Interface Details" dialog box .................................................................. 76
4.7. Capture files and file modes .......................................................................... 77
4.8. Link-layer header type ................................................................................. 79
4.9. Filtering while capturing ............................................................................... 80
4.9.1. Automatic Remote Traffic Filtering ...................................................... 81
4.10. While a Capture is running ... ....................................................................... 83
4.10.1. Stop the running capture ................................................................... 83
4.10.2. Restart a running capture .................................................................. 84
5. File Input / Output and Printing ................................................................................ 86
5.1. Introduction ............................................................................................... 86
5.2. Open capture files ....................................................................................... 87
5.2.1. The "Open Capture File" dialog box ..................................................... 87
5.2.2. Input File Formats ............................................................................. 89
5.3. Saving captured packets ............................................................................... 92
5.3.1. The "Save Capture File As" dialog box ................................................. 92
5.3.2. Output File Formats .......................................................................... 94
5.4. Merging capture files ................................................................................... 96
5.4.1. The "Merge with Capture File" dialog box ............................................. 96
5.5. File Sets .................................................................................................... 98
5.5.1. The "List Files" dialog box ................................................................. 98
5.6. Exporting data .......................................................................................... 100
5.6.1. The "Export as Plain Text File" dialog box .......................................... 100
5.6.2. The "Export as PostScript File" dialog box .......................................... 101
5.6.3. The "Export as CSV (Comma Separated Values) File" dialog box ............ 101
5.6.4. The "Export as C Arrays (packet bytes) file" dialog box ......................... 102
5.6.5. The "Export as PSML File" dialog box ............................................... 102
5.6.6. The "Export as PDML File" dialog box ............................................... 103
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5.6.7. The "Export selected packet bytes" dialog box ......................................
5.6.8. The "Export Objects" dialog box ........................................................
5.7. Printing packets ........................................................................................
5.7.1. The "Print" dialog box .....................................................................
5.8. The Packet Range frame .............................................................................
5.9. The Packet Format frame ............................................................................
6. Working with captured packets ...............................................................................
6.1. Viewing packets you have captured ..............................................................
6.2. Pop-up menus ...........................................................................................
6.2.1. Pop-up menu of the "Packet List" pane ...............................................
6.2.2. Pop-up menu of the "Packet Details" pane ...........................................
6.3. Filtering packets while viewing ....................................................................
6.4. Building display filter expressions ................................................................
6.4.1. Display filter fields .........................................................................
6.4.2. Comparing values ...........................................................................
6.4.3. Combining expressions ....................................................................
6.4.4. A common mistake .........................................................................
6.5. The "Filter Expression" dialog box ...............................................................
6.6. Defining and saving filters ..........................................................................
6.7. Defining and saving filter macros .................................................................
6.8. Finding packets .........................................................................................
6.8.1. The "Find Packet" dialog box ............................................................
6.8.2. The "Find Next" command ...............................................................
6.8.3. The "Find Previous" command ..........................................................
6.9. Go to a specific packet ...............................................................................
6.9.1. The "Go Back" command .................................................................
6.9.2. The "Go Forward" command ............................................................
6.9.3. The "Go to Packet" dialog box ..........................................................
6.9.4. The "Go to Corresponding Packet" command .......................................
6.9.5. The "Go to First Packet" command ....................................................
6.9.6. The "Go to Last Packet" command .....................................................
6.10. Marking packets ......................................................................................
6.11. Time display formats and time references .....................................................
6.11.1. Packet time referencing ..................................................................
7. Advanced Topics .................................................................................................
7.1. Introduction .............................................................................................
7.2. Following TCP streams ..............................................................................
7.2.1. The "Follow TCP Stream" dialog box .................................................
7.3. Expert Infos .............................................................................................
7.3.1. Expert Info Entries ..........................................................................
7.3.2. "Expert Info Composite" dialog .........................................................
7.3.3. "Colorized" Protocol Details Tree ......................................................
7.3.4. "Expert" Packet List Column (optional) ..............................................
7.4. Time Stamps ............................................................................................
7.4.1. Wireshark internals .........................................................................
7.4.2. Capture file formats ........................................................................
7.4.3. Accuracy .......................................................................................
7.5. Time Zones ..............................................................................................
7.5.1. Set your computer's time correctly! ....................................................
7.5.2. Wireshark and Time Zones ...............................................................
7.6. Packet Reassembling .................................................................................
7.6.1. What is it? .....................................................................................
7.6.2. How Wireshark handles it ................................................................
7.7. Name Resolution .......................................................................................
7.7.1. Name Resolution drawbacks .............................................................
7.7.2. Ethernet name resolution (MAC layer) ................................................
7.7.3. IP name resolution (network layer) .....................................................
7.7.4. IPX name resolution (network layer) ..................................................
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7.7.5. TCP/UDP port name resolution (transport layer) ...................................
7.8. Checksums ..............................................................................................
7.8.1. Wireshark checksum validation .........................................................
7.8.2. Checksum offloading .......................................................................
8. Statistics ............................................................................................................
8.1. Introduction .............................................................................................
8.2. The "Summary" window .............................................................................
8.3. The "Protocol Hierarchy" window ................................................................
8.4. Conversations ...........................................................................................
8.4.1. What is a Conversation? ...................................................................
8.4.2. The "Conversations" window ............................................................
8.4.3. The protocol specific "Conversation List" windows ...............................
8.5. Endpoints ................................................................................................
8.5.1. What is an Endpoint? .......................................................................
8.5.2. The "Endpoints" window ..................................................................
8.5.3. The protocol specific "Endpoint List" windows ....................................
8.6. The "IO Graphs" window ............................................................................
8.7. Compare two capture files ...........................................................................
8.8. WLAN Traffic Statistics .............................................................................
8.9. LTE MAC Traffic Statistics ........................................................................
8.10. Service Response Time .............................................................................
8.10.1. The "Service Response Time DCE-RPC" window ...............................
8.11. The protocol specific statistics windows .......................................................
9. Customizing Wireshark .........................................................................................
9.1. Introduction .............................................................................................
9.2. Start Wireshark from the command line .........................................................
9.3. Packet colorization ....................................................................................
9.4. Control Protocol dissection .........................................................................
9.4.1. The "Enabled Protocols" dialog box ...................................................
9.4.2. User Specified Decodes ...................................................................
9.4.3. Show User Specified Decodes ...........................................................
9.5. Preferences ..............................................................................................
9.5.1. Interface Options ............................................................................
9.6. Configuration Profiles ................................................................................
9.7. User Table ...............................................................................................
9.8. Display Filter Macros .................................................................................
9.9. GeoIP Database Paths ................................................................................
9.10. Tektronix K12xx/15 RF5 protocols Table .....................................................
9.11. PRES Users Context List ..........................................................................
9.12. SCCP users Table ....................................................................................
9.13. SMI (MIB and PIB) Modules .....................................................................
9.14. SMI (MIB and PIB) Paths .........................................................................
9.15. SNMP users Table ...................................................................................
9.16. User DLTs protocol table ..........................................................................
9.17. IKEv2 decryption table .............................................................................
10. Lua Support in Wireshark ....................................................................................
10.1. Introduction ............................................................................................
10.2. Example of Dissector written in Lua ............................................................
10.3. Example of Listener written in Lua .............................................................
10.4. Wireshark's Lua API Reference Manual .......................................................
10.4.1. Saving capture files .......................................................................
10.4.2. Obtaining dissection data ................................................................
10.4.3. GUI support .................................................................................
10.4.4. Post-dissection packet analysis ........................................................
10.4.5. Obtaining packet information ..........................................................
10.4.6. Functions for writing dissectors .......................................................
10.4.7. Adding information to the dissection tree ...........................................
10.4.8. Functions for handling packet data ...................................................
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10.4.9. Utility Functions ...........................................................................
A. Files and Folders .................................................................................................
A.1. Capture Files ...........................................................................................
A.1.1. Libpcap File Contents .....................................................................
A.1.2. Not Saved in the Capture File ...........................................................
A.2. Configuration Files and Folders ...................................................................
A.3. Windows folders ......................................................................................
A.3.1. Windows profiles ...........................................................................
A.3.2. Windows Vista/XP/2000/NT roaming profiles .....................................
A.3.3. Windows temporary folder ..............................................................
B. Protocols and Protocol Fields ................................................................................
C. Wireshark Messages ............................................................................................
C.1. Packet List Messages .................................................................................
C.1.1. [Malformed Packet] ........................................................................
C.1.2. [Packet size limited during capture] ...................................................
C.2. Packet Details Messages ............................................................................
C.2.1. [Response in frame: 123] .................................................................
C.2.2. [Request in frame: 123] ...................................................................
C.2.3. [Time from request: 0.123 seconds] ...................................................
C.2.4. [Stream setup by PROTOCOL (frame 123)] ........................................
D. Related command line tools ..................................................................................
D.1. Introduction .............................................................................................
D.2. tshark: Terminal-based Wireshark ..............................................................
D.3. tcpdump: Capturing with tcpdump for viewing with Wireshark ........................
D.4. dumpcap: Capturing with dumpcap for viewing with Wireshark .......................
D.5. capinfos: Print information about capture files ...............................................
D.6. editcap: Edit capture files ..........................................................................
D.7. mergecap: Merging multiple capture files into one .........................................
D.8. text2pcap: Converting ASCII hexdumps to network captures ...........................
D.9. idl2wrs: Creating dissectors from CORBA IDL files .......................................
D.9.1. What is it? ....................................................................................
D.9.2. Why do this? .................................................................................
D.9.3. How to use idl2wrs .........................................................................
D.9.4. TODO .........................................................................................
D.9.5. Limitations ...................................................................................
D.9.6. Notes ...........................................................................................
E. This Document's License (GPL) .............................................................................
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Preface
1. Foreword
Wireshark is one of those programs that many network managers would love to be able to use, but they
are often prevented from getting what they would like from Wireshark because of the lack of documentation.
This document is part of an effort by the Wireshark team to improve the usability of Wireshark.
We hope that you find it useful, and look forward to your comments.
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Preface
2. Who should read this document?
The intended audience of this book is anyone using Wireshark.
This book will explain all the basics and also some of the advanced features that Wireshark provides. As
Wireshark has become a very complex program since the early days, not every feature of Wireshark
may be explained in this book.
This book is not intended to explain network sniffing in general and it will not provide details about specific network protocols. A lot of useful information regarding these topics can be found at the Wireshark
Wiki at http://wiki.wireshark.org
By reading this book, you will learn how to install Wireshark, how to use the basic elements of the
graphical user interface (such as the menu) and what's behind some of the advanced features that are not
always obvious at first sight. It will hopefully guide you around some common problems that frequently
appear for new (and sometimes even advanced) users of Wireshark.
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Preface
3. Acknowledgements
The authors would like to thank the whole Wireshark team for their assistance. In particular, the authors
would like to thank:
•
Gerald Combs, for initiating the Wireshark project and funding to do this documentation.
•
Guy Harris, for many helpful hints and a great deal of patience in reviewing this document.
•
Gilbert Ramirez, for general encouragement and helpful hints along the way.
The authors would also like to thank the following people for their helpful feedback on this document:
•
Pat Eyler, for his suggestions on improving the example on generating a backtrace.
•
Martin Regner, for his various suggestions and corrections.
•
Graeme Hewson, for a lot of grammatical corrections.
The authors would like to acknowledge those man page and README authors for the Wireshark project
from who sections of this document borrow heavily:
•
Scott Renfro from whose mergecap man page Section D.7, “mergecap: Merging multiple capture
files into one ” is derived.
•
Ashok Narayanan from whose text2pcap man page Section D.8, “text2pcap: Converting ASCII
hexdumps to network captures ” is derived.
•
Frank Singleton from whose README.idl2wrs Section D.9, “idl2wrs: Creating dissectors from
CORBA IDL files ” is derived.
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4. About this document
This book was originally developed by Richard Sharpe with funds provided from the Wireshark Fund. It
was updated by Ed Warnicke and more recently redesigned and updated by Ulf Lamping.
It is written in DocBook/XML.
You will find some specially marked parts in this book:
This is a warning!
You should pay attention to a warning, as otherwise data loss might occur.
This is a note!
A note will point you to common mistakes and things that might not be obvious.
This is a tip!
Tips will be helpful for your everyday work using Wireshark.
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5. Where to get the latest copy of this
document?
The latest copy of this documentation can always be found at: http://www.wireshark.org/docs/.
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6. Providing feedback about this document
Should you have any feedback about this document, please send it to the authors through wiresharkdev[AT]wireshark.org.
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Chapter 1. Introduction
1.1. What is Wireshark?
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.
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).
In the past, such tools were either very expensive, proprietary, or both. However, with the advent of
Wireshark, all that has changed.
Wireshark is perhaps one of the best open source packet analyzers available today.
1.1.1. Some intended purposes
Here are some examples people use Wireshark for:
•
network administrators use it to troubleshoot network problems
•
network security engineers use it to examine security problems
•
developers use it to debug protocol implementations
•
people use it to learn network protocol internals
Beside these examples, Wireshark can be helpful in many other situations too.
1.1.2. Features
The following are some of the many features Wireshark provides:
•
Available for UNIX and Windows.
•
Capture live packet data from a network interface.
•
Display packets with very detailed protocol information.
•
Open and Save packet data captured.
•
Import and Export packet data from and to a lot of other capture programs.
•
Filter packets on many criteria.
•
Search for packets on many criteria.
•
Colorize packet display based on filters.
•
Create various statistics.
•
... and a lot more!
1
Introduction
However, to really appreciate its power, you have to start using it.
Figure 1.1, “ Wireshark captures packets and allows you to examine their content. ” shows Wireshark
having captured some packets and waiting for you to examine them.
Figure 1.1. Wireshark captures packets and allows you to examine their content.
1.1.3. Live capture from many different network media
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: http:/ /
wiki.wireshark.org/CaptureSetup/NetworkMedia.
1.1.4. Import files from many other capture programs
Wireshark can open packets captured from a large number of other capture programs. For a list of input
formats see Section 5.2.2, “Input File Formats”.
1.1.5. Export files for many other capture programs
Wireshark can save packets captured in a large number of formats of other capture programs. For a list
of output formats see Section 5.3.2, “Output File Formats”.
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Introduction
1.1.6. Many protocol decoders
There are protocol decoders (or dissectors, as they are known in Wireshark) for a great many protocols:
see Appendix B, Protocols and Protocol Fields.
1.1.7. Open Source Software
Wireshark is an open source software project, and is released under the GNU General Public License
(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!
1.1.8. What Wireshark is not
Here are some things Wireshark does not provide:
•
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.
•
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).
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Introduction
1.2. System Requirements
What you'll need to get Wireshark up and running ...
1.2.1. General Remarks
•
The values below are the minimum requirements and only "rules of thumb" for use on a moderately
used network
•
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.
•
If Wireshark is running out of memory it crashes, see: http:/ / wiki.wireshark.org/ KnownBugs/
OutOfMemory for details and workarounds
•
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.
1.2.2. Microsoft Windows
•
Windows 2000, XP Home, XP Pro, XP Tablet PC, XP Media Center, Server 2003, Vista or Windows 2008 (XP Pro recommended)
•
32-bit Pentium or alike (recommended: 400MHz or greater), 64-bit processors in WoW64 emulation
- see remarks below
•
128MB RAM system memory (recommended: 256MBytes or more)
•
75MB available disk space (plus size of user's capture files, e.g. 100MB extra)
•
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)
•
A supported network card for capturing:
•
Ethernet: any card supported by Windows should do
•
WLAN: see the MicroLogix support list, no capturing of 802.11 headers and non-data frames
•
Other media: See http://wiki.wireshark.org/CaptureSetup/NetworkMedia
Remarks:
•
Older Windows versions are no longer supported because of three reasons: None of the developers
actively use those systems any longer which makes support difficult. The libraries Wireshark depends on (GTK, WinPCap, ...) are also dropping support for these systems. Microsoft also dropped
support for these systems.
4
Introduction
•
Windows 95, 98 and ME will no longer work with Wireshark. The last known version to work was
Ethereal 0.99.0 (which includes WinPcap 3.1). You can get it from http:/ / ethereal.com/ download.html. According to this bug report, you may need to install Ethereal 0.10.0 on some systems.
BTW: Microsoft no longer supports 98/ME since July 11, 2006!
•
Windows NT 4.0 will no longer work with Wireshark. The last known version to work was Wireshark 0.99.4 (which includes WinPcap 3.1), you still can get it from: http:/ / prdownloads.sourceforge.net/wireshark/wireshark-setup-0.99.4.exe. BTW: Microsoft no longer supports NT
4.0 since December 31, 2005!
•
Windows CE and the embedded (NT/XP) versions are not supported!
•
64-bit processors run Wireshark in 32 bit emulation (called WoW64), at least WinPcap 4.0 is required for that
•
Multi monitor setups are supported but may behave a bit strangely
1.2.3. Unix / Linux
Wireshark currently runs on most UNIX platforms. The system requirements should be comparable to
the Windows values listed above.
Binary packages are available for at least the following platforms:
•
Apple Mac OS X
•
Debian GNU/Linux
•
FreeBSD
•
Gentoo Linux
•
HP-UX
•
Mandriva Linux
•
NetBSD
•
OpenPKG
•
Red Hat Fedora/Enterprise Linux
•
rPath Linux
•
Sun Solaris/i386
•
Sun Solaris/Sparc
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 wireshark-dev[AT]wireshark.org .
5
Introduction
1.3. Where to get Wireshark?
You can get the latest copy of the program from the Wireshark website: http://www.wireshark.org/download.html. The website allows you to choose from among several mirrors
for downloading.
A new Wireshark version will typically become available every 4-8 months.
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 Section 1.6.4, “Mailing Lists”.
6
Introduction
1.4. A brief history of Wireshark
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.
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.
Not long after that, Gilbert Ramirez saw its potential and contributed a low-level dissector to it.
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.
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.
The list of people who have contributed to Ethereal has become very long since then, and almost all of
them started with a protocol that they needed that Ethereal did not already handle. So they copied an existing dissector and contributed the code back to the team.
In 2006 the project moved house and re-emerged under a new name: Wireshark.
7
Introduction
1.5. Development and maintenance of
Wireshark
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.
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 authors page on the Wireshark web
site.
Wireshark is an open source software project, and is released under the GNU General Public License
(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.
You gain three benefits by contributing your improvements back to the community:
•
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.
•
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.
•
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.
The Wireshark source code and binary kits for some platforms are all available on the download page of
the Wireshark website: http://www.wireshark.org/download.html.
8
Introduction
1.6. Reporting problems and getting help
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).
1.6.1. Website
You will find lots of useful information on the Wireshark homepage at http://www.wireshark.org.
1.6.2. Wiki
The Wireshark Wiki at http://wiki.wireshark.org 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.
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.
1.6.3. FAQ
The "Frequently Asked Questions" will list often asked questions and the corresponding answers.
Read the FAQ!
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).
You will find the FAQ inside Wireshark by clicking the menu item Help/Contents and selecting the
FAQ page in the dialog shown.
An online version is available at the Wireshark website: http://www.wireshark.org/faq.html. You might
prefer this online version, as it's typically more up to date and the HTML format is easier to use.
1.6.4. Mailing Lists
There are several mailing lists of specific Wireshark topics available:
wireshark-announce
This mailing list will inform you about new program releases, which usually appear about every 4-8 weeks.
wireshark-users
This list is for users of Wireshark. People post questions about building
and using Wireshark, others (hopefully) provide answers.
wireshark-dev
This list is for Wireshark developers. If you want to start developing a protocol dissector, join this list.
You can subscribe to each of these lists from the Wireshark web site: http://www.wireshark.org. Simply
select the mailing lists link on the left hand side of the site. The lists are archived at the Wireshark web
site as well.
9
Introduction
Tip!
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.
1.6.5. Reporting Problems
Note!
Before reporting any problems, please make sure you have installed the latest version of
Wireshark.
When reporting problems with Wireshark, it is helpful if you supply the following information:
1.
The version number of Wireshark and the dependent libraries linked with it, e.g. GTK+, etc. You
can obtain this with the command wireshark -v.
2.
Information about the platform you run Wireshark on.
3.
A detailed description of your problem.
4.
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.
Don't send large files!
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.
Don't send confidential information!
If you send captured data to the mailing lists, be sure they don't contain any sensitive or
confidential information like passwords or such.
1.6.6. Reporting Crashes on UNIX/Linux platforms
When reporting crashes with Wireshark, it is helpful if you supply the traceback information (besides
the information mentioned in "Reporting Problems").
You can obtain this traceback information with the following commands:
$ gdb `whereis wireshark | cut -f2 -d: | cut -d' ' -f2` core >& bt.txt
backtrace
^D
$
10
Introduction
Note
Type the characters in the first line verbatim! Those are back-tics there!
Note
backtrace is a gdb 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 gdb to exit. This will leave you with a file called bt.txt in the current directory. Include the file with your bug report.
Note
If you do not have gdb available, you will have to check out your operating system's debugger.
You should mail the traceback to the wireshark-dev[AT]wireshark.org mailing list.
1.6.7. Reporting Crashes on Windows platforms
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.
11
Introduction
12
Chapter 2. Building and Installing
Wireshark
2.1. Introduction
As with all things, there must be a beginning, and so it is with Wireshark. To use Wireshark, you must:
•
Obtain a binary package for your operating system, or
•
Obtain the source and build Wireshark for your operating system.
Currently, only two or three Linux distributions ship Wireshark, and they are commonly shipping an
out-of-date version. No other versions of UNIX ship Wireshark so far, and Microsoft does not ship it
with any version of Windows. For that reason, you will need to know where to get the latest version of
Wireshark and how to install it.
This chapter shows you how to obtain source and binary packages, and how to build Wireshark from
source, should you choose to do so.
The following are the general steps you would use:
1.
Download the relevant package for your needs, e.g. source or binary distribution.
2.
Build the source into a binary, if you have downloaded the source.
This may involve building and/or installing other necessary packages.
3.
Install the binaries into their final destinations.
13
Building and Installing Wireshark
2.2. Obtaining the source and binary
distributions
You can obtain both source and binary distributions from the Wireshark web site: http://www.wireshark.org. Simply select the download link, and then select either the source package or
binary package of your choice from the mirror site closest to you.
Download all required files!
In general, unless you have already downloaded Wireshark before, you will most likely
need to download several source packages if you are building Wireshark from source. This
is covered in more detail below.
Once you have downloaded the relevant files, you can go on to the next step.
Note!
While you will find a number of binary packages available on the Wireshark web site, you
might not find one for your platform, and they often tend to be several versions behind the
current released version, as they are contributed by people who have the platforms they are
built for.
For this reason, you might want to pull down the source distribution and build it, as the
process is relatively simple.
14
Building and Installing Wireshark
2.3. Before you build Wireshark under UNIX
Before you build Wireshark from sources, or install a binary package, you must ensure that you have the
following other packages installed:
•
GTK+, The GIMP Tool Kit.
You will also need Glib. Both can be obtained from www.gtk.org
•
libpcap, the packet capture software that Wireshark uses.
You can obtain libpcap from www.tcpdump.org
Depending on your system, you may be able to install these from binaries, e.g. RPMs, or you may need
to obtain them in source code form and build them.
If you have downloaded the source for GTK+, the instructions shown in Example 2.1, “Building GTK+
from source” may provide some help in building it:
Example 2.1. Building GTK+ from source
gzip -dc gtk+-1.2.10.tar.gz | tar xvf <much output removed>
cd gtk+-1.2.10
./configure
<much output removed>
make
<much output removed>
make install
<much output removed>
Note!
You may need to change the version number of gtk+ in Example 2.1, “Building GTK+
from source” to match the version of GTK+ you have downloaded. The directory you
change to will change if the version of GTK+ changes, and in all cases, tar xvf - will show
you the name of the directory you should change to.
Note!
If you use Linux, or have GNU tar installed, you can use tar zxvf gtk+-1.2.10.tar.gz. It is
also possible to use gunzip -c or gzcat rather than gzip -dc on many UNIX systems.
Note!
If you downloaded gtk+ or any other tar file using Windows, you may find your file called
gtk+-1_2_8_tar.gz.
You should consult the GTK+ web site if any errors occur in carrying out the instructions in Example 2.1, “Building GTK+ from source”.
15
Building and Installing Wireshark
If you have downloaded the source to libpcap, the general instructions shown in Example 2.2, “Building
and installing libpcap” will assist in building it. Also, if your operating system does not support tcpdump, you might also want to download it from the tcpdump web site and install it.
Example 2.2. Building and installing libpcap
gzip -dc libpcap-0.9.4.tar.Z | tar xvf <much output removed>
cd libpcap-0.9.4
./configure
<much output removed>
make
<much output removed>
make install
<much output removed>
Note!
The directory you should change to will depend on the version of libpcap you have downloaded. In all cases, tar xvf - will show you the name of the directory that has been unpacked.
Under Red Hat 6.x and beyond (and distributions based on it, like Mandrake) you can simply install
each of the packages you need from RPMs. Most Linux systems will install GTK+ and GLib in any
case, however you will probably need to install the devel versions of each of these packages. The commands shown in Example 2.3, “ Installing required RPMs under Red Hat Linux 6.2 and beyond ” will
install all the needed RPMs if they are not already installed.
Example 2.3. Installing required RPMs under Red Hat Linux 6.2 and beyond
cd /mnt/cdrom/RedHat/RPMS
rpm -ivh glib-1.2.6-3.i386.rpm
rpm -ivh glib-devel-1.2.6-3.i386.rpm
rpm -ivh gtk+-1.2.6-7.i386.rpm
rpm -ivh gtk+-devel-1.2.6-7.i386.rpm
rpm -ivh libpcap-0.4-19.i386.rpm
Note
If you are using a version of Red Hat later than 6.2, the required RPMs have most likely
changed. Simply use the correct RPMs from your distribution.
Under Debian you can install Wireshark using aptitude. aptitude will handle any dependency issues for
you. Example 2.4, “Installing debs under Debian” shows how to do this.
Example 2.4. Installing debs under Debian
aptitude install wireshark-dev
16
Building and Installing Wireshark
17
Building and Installing Wireshark
2.4. Building Wireshark from source under
UNIX
Use the following general steps if you are building Wireshark from source under a UNIX operating system:
1.
Unpack the source from its gzip'd tar file. If you are using Linux, or your version of UNIX uses
GNU tar, you can use the following command:
tar zxvf wireshark-1.0.0-tar.gz
For other versions of UNIX, you will want to use the following commands:
gzip -d wireshark-1.0.0-tar.gz
tar xvf wireshark-1.0.0-tar
Note!
The pipeline gzip -dc wireshark-1.0.0-tar.gz | tar xvf - will work here as well.
Note!
If you have downloaded the Wireshark tarball under Windows, you may find that
your browser has created a file with underscores rather than periods in its file name.
2.
Change directory to the Wireshark source directory.
3.
Configure your source so it will build correctly for your version of UNIX. You can do this with the
following command:
./configure
If this step fails, you will have to rectify the problems and rerun configure. Troubleshooting hints
are provided in Section 2.6, “Troubleshooting during the install on Unix”.
4.
Build the sources into a binary, with the make command. For example:
make
5.
Install the software in its final destination, using the command:
make install
Once you have installed Wireshark with make install above, you should be able to run it by entering
18
Building and Installing Wireshark
wireshark.
19
Building and Installing Wireshark
2.5. Installing the binaries under UNIX
In general, installing the binary under your version of UNIX will be specific to the installation methods
used with your version of UNIX. For example, under AIX, you would use smit to install the Wireshark
binary package, while under Tru64 UNIX (formerly Digital UNIX) you would use setld.
2.5.1. Installing from rpm's under Red Hat and alike
Use the following command to install the Wireshark RPM that you have downloaded from the Wireshark web site:
rpm -ivh wireshark-1.0.0.i386.rpm
If the above step fails because of missing dependencies, install the dependencies first, and then retry the
step above. See Example 2.3, “ Installing required RPMs under Red Hat Linux 6.2 and beyond ” for information on what RPMs you will need to have installed.
2.5.2. Installing from deb's under Debian
Use the following command to install Wireshark under Debian:
aptitude install wireshark
aptitude should take care of all of the dependency issues for you.
2.5.3. Installing from portage under Gentoo Linux
Use the following command to install Wireshark under Gentoo Linux with all of the extra features:
USE="adns gtk ipv6 portaudio snmp ssl kerberos threads selinux" emerge wireshark
2.5.4. Installing from packages under FreeBSD
Use the following command to install Wireshark under FreeBSD:
pkg_add -r wireshark
pkg_add should take care of all of the dependency issues for you.
20
Building and Installing Wireshark
2.6. Troubleshooting during the install on Unix
A number of errors can occur during the installation process. Some hints on solving these are provided
here.
If the configure stage fails, you will need to find out why. You can check the file config.log in the
source directory to find out what failed. The last few lines of this file should help in determining the
problem.
The standard problems are that you do not have GTK+ on your system, or you do not have a recent
enough version of GTK+. The configure will also fail if you do not have libpcap (at least the required
include files) on your system.
Another common problem is for the final compile and link stage to terminate with a complaint of: Output too long. This is likely to be caused by an antiquated sed (such as the one shipped with Solaris).
Since sed is used by the libtool script to construct the final link command, this leads to mysterious problems. This can be resolved by downloading a recent version of sed from http://directory.fsf.org/GNU/
sed.html.
If you cannot determine what the problems are, send mail to the wireshark-dev mailing list explaining
your problem, and including the output from config.log and anything else you think is relevant, like
a trace of the make stage.
21
Building and Installing Wireshark
2.7. Building from source under Windows
It is recommended to use the binary installer for Windows, until you want to start developing Wireshark
on the Windows platform.
For further information how to build Wireshark for Windows from the sources, have a look at the Development Wiki: http://wiki.wireshark.org/Development for the latest available development documentation.
22
Building and Installing Wireshark
2.8. Installing Wireshark under Windows
In this section we explore installing Wireshark under Windows from the binary packages.
2.8.1. Install Wireshark
You may acquire a binary installer of Wireshark named something like: wiresharksetup-x.y.z.exe. The Wireshark installer includes WinPcap, so you don't need to download and
install two separate packages.
Simply download the Wireshark installer from: http://www.wireshark.org/download.html and execute it.
Beside the usual installer options like where to install the program, there are several optional components.
Tip: Just keep the defaults!
If you are unsure which settings to select, just keep the defaults.
2.8.1.1. "Choose Components" page
Wireshark
•
Wireshark GTK - Wireshark is a GUI network protocol analyzer.
•
GTK MS Windows Engine - GTK MS Windows Engine (native Win32 look and feel, recommended).
TShark - TShark is a command-line based network protocol analyzer.
Plugins / Extensions (for the Wireshark and TShark dissection engines):
•
Dissector Plugins - Plugins with some extended dissections.
•
Tree Statistics Plugins - Plugins with some extended statistics.
•
Mate - Meta Analysis and Tracing Engine (experimental) - user configurable extension(s) of the
display filter engine, see http://wiki.wireshark.org/Mate for details.
•
SNMP MIBs - SNMP MIBs for a more detailed SNMP dissection.
Tools (additional command line tools to work with capture files):
•
Editcap - Editcap is a program that reads a capture file and writes some or all of the packets into another capture file.
•
Text2Pcap - Text2pcap is a program that reads in an ASCII hex dump and writes the data into a
libpcap-style capture file.
•
Mergecap - Mergecap is a program that combines multiple saved capture files into a single output
file.
•
Capinfos - Capinfos is a program that provides information on capture files.
23
Building and Installing Wireshark
User's Guide - Local installation of the User's Guide. The Help buttons on most dialogs will require an
internet connection to show help pages if the User's Guide is not installed locally.
2.8.1.2. "Additional Tasks" page
•
Start Menu Shortcuts - add some start menu shortcuts.
•
Desktop Icon - add a Wireshark icon to the desktop.
•
Quick Launch Icon - add a Wireshark icon to the Explorer quick launch toolbar.
•
Associate file extensions to Wireshark - Associate standard network trace files to Wireshark.
2.8.1.3. "Install WinPcap?" page
The Wireshark installer contains the latest released WinPcap installer.
If you don't have WinPcap installed, you won't be able to capture live network traffic, but you will still
be able to open saved capture files.
•
Currently installed WinPcap version - the Wireshark installer detects the currently installed WinPcap version.
•
Install WinPcap x.x - if the currently installed version is older than the one which comes with the
Wireshark installer (or WinPcap is not installed at all), this will be selected by default.
•
Start WinPcap service "NPF" at startup - so users without administrative privileges can capture.
More WinPcap info:
•
Wireshark related: http://wiki.wireshark.org/WinPcap
•
General WinPcap info: http://www.winpcap.org
2.8.1.4. Command line options
You can simply start the Wireshark installer without any command line parameters, it will show you the
usual interactive installer.
For special cases, there are some command line parameters available:
•
/NCRC disables the CRC check
•
/S runs the installer or uninstaller silently with default values. Please note: The silent installer won't
install WinPCap!
•
/desktopicon installation of the desktop icon, =yes - force installation, =no - don't install, otherwise
use defaults / user settings. This option can be useful for a silent installer.
•
/quicklaunchicon installation of the quick launch icon, =yes - force installation, =no - don't install,
24
Building and Installing Wireshark
otherwise use defaults / user settings.
•
/D sets the default installation directory ($INSTDIR), overriding InstallDir and InstallDirRegKey. It
must be the last parameter used in the command line and must not contain any quotes, even if the
path contains spaces.
Example:
wireshark-setup-1.0.0.exe /NCRC /S /desktopicon=yes
/quicklaunchicon=no /D=C:\Program Files\Foo
2.8.2. Manual WinPcap Installation
Note!
As mentioned above, the Wireshark installer takes care of the installation of WinPcap, so usually you don't have to worry about WinPcap at all!
The following is only necessary if you want to try a different version than the one included in the Wireshark installer, e.g. because a new WinPcap (beta) version was released.
Additional WinPcap versions (including newer alpha or beta releases) can be downloaded from the following locations:
•
The main WinPcap site: http://www.winpcap.org
•
The Wiretapped.net mirror: http://www.mirrors.wiretapped.net/security/packet-capture/winpcap
At the download page you will find a single installer exe called something like "auto-installer", which
can be installed under various Windows systems, including NT4.0/2000/XP/Vista.
2.8.3. Update Wireshark
From time to time you may want to update your installed Wireshark to a more recent version. If you join
Wireshark's announce mailing list, you will be informed about new Wireshark versions, see Section 1.6.4, “Mailing Lists” for details how to subscribe to this list.
New versions of Wireshark usually become available every 4 to 8 months. Updating Wireshark is done
the same way as installing it, you simply download and start the installer exe. A reboot is usually not required and all your personal settings remain unchanged.
2.8.4. Update WinPcap
New versions of WinPcap are less frequently available, maybe only once in a year. You will find WinPcap update instructions where you can download new WinPcap versions. Usually you have to reboot
the machine after installing a new WinPcap version.
Warning!
If you have an older version of WinPcap installed, you must uninstall it before installing
the current version. Recent versions of the WinPcap installer will take care of this.
25
Building and Installing Wireshark
2.8.5. Uninstall Wireshark
You can uninstall Wireshark the usual way, using the "Add or Remove Programs" option inside the
Control Panel. Select the "Wireshark" entry to start the uninstallation procedure.
The Wireshark uninstaller will provide several options as to which things are to be uninstalled; the default is to remove the core components but keep the personal settings, WinPcap and alike.
WinPcap won't be uninstalled by default, as other programs than Wireshark may use it as well.
2.8.6. Uninstall WinPcap
You can uninstall WinPcap independently of Wireshark, using the "WinPcap" entry in the "Add or Remove Programs" of the Control Panel.
Note!
After uninstallation of WinPcap you can't capture anything with Wireshark.
It might be a good idea to reboot Windows afterwards.
26
Building and Installing Wireshark
27
Chapter 3. User Interface
3.1. Introduction
By now you have installed Wireshark and are most likely keen to get started capturing your first packets.
In the next chapters we will explore:
•
How the Wireshark user interface works
•
How to capture packets in Wireshark
•
How to view packets in Wireshark
•
How to filter packets in Wireshark
•
... and many other things!
28
User Interface
3.2. Start Wireshark
You can start Wireshark from your shell or window manager.
Tip!
When starting Wireshark it's possible to specify optional settings using the command line.
See Section 9.2, “Start Wireshark from the command line” for details.
Note!
In the following chapters, a lot of screenshots from Wireshark will be shown. As Wireshark runs on many different platforms and there are different versions of the underlying
GUI toolkit (GTK 1.x / 2.x) used, your screen might look different from the provided
screenshots. But as there are no real differences in functionality, these screenshots should
still be well understandable.
29
User Interface
3.3. The Main window
Let's look at Wireshark's user interface. Figure 3.1, “The Main window” shows Wireshark as you would
usually see it after some packets are captured or loaded (how to do this will be described later).
Figure 3.1. The Main window
Wireshark's main window consists of parts that are commonly known from many other GUI programs.
1.
The menu (see Section 3.4, “The Menu”) is used to start actions.
2.
The main toolbar (see Section 3.14, “The "Main" toolbar”) provides quick access to frequently
used items from the menu.
3.
The filter toolbar (see Section 3.15, “The "Filter" toolbar”) provides a way to directly manipulate
the currently used display filter (see Section 6.3, “Filtering packets while viewing”).
4.
The packet list pane (see Section 3.16, “The "Packet List" pane”) displays a summary of each packet captured. By clicking on packets in this pane you control what is displayed in the other two
panes.
5.
The packet details pane (see Section 3.17, “The "Packet Details" pane”) displays the packet selected in the packet list pane in more detail.
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User Interface
6.
The packet bytes pane (see Section 3.18, “The "Packet Bytes" pane”) displays the data from the
packet selected in the packet list pane, and highlights the field selected in the packet details pane.
7.
The statusbar (see Section 3.19, “The Statusbar”) shows some detailed information about the current program state and the captured data.
Tip!
The layout of the main window can be customized by changing preference settings. See
Section 9.5, “Preferences” for details!
3.3.1. Main Window Navigation
Packet list and detail navigation can be done entirely from the keyboard. Table 3.1, “Keyboard Navigation” shows a list of keystrokes that will let you quickly move around a capture file. See Table 3.5, “Go
menu items” for additional navigation keystrokes.
Table 3.1. Keyboard Navigation
Accelerator
Description
Tab, Shift+Tab
Move between screen elements, e.g. from the toolbars to the packet list to the packet
detail.
Down
Move to the next packet or detail item.
Up
Move to the previous packet or detail item.
Ctrl+Down, F8
Move to the next packet, even if the packet list isn't focused.
Ctrl+Up, F7
Move to the previous packet, even if the packet list isn't focused.
Left
In the packet detail, closes the selected tree item. If it's already closed, jumps to the
parent node.
Right
In the packet detail, opens the selected tree item.
Shift+Right
In the packet detail, opens the selected tree item and all of its subtrees.
Ctrl+Right
In the packet detail, opens all tree items.
Ctrl+Left
In the packet detail, closes all tree items.
Backspace
In the packet detail, jumps to the parent node.
Return, Enter
In the packet detail, toggles the selected tree item.
Additionally, typing anywhere in the main window will start filling in a display filter.
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User Interface
3.4. The Menu
The Wireshark menu sits on top of the Wireshark window. An example is shown in Figure 3.2, “The
Menu”.
Note!
Menu items will be greyed out if the corresponding feature isn't available. For example,
you cannot save a capture file if you didn't capture or load any data before.
Figure 3.2. The Menu
It contains the following items:
File
This menu contains items to open and merge capture files, save / print / export capture
files in whole or in part, and to quit from Wireshark. See Section 3.5, “The "File"
menu”.
Edit
This menu contains items to find a packet, time reference or mark one or more packets,
handle configuration profiles, and set your preferences; (cut, copy, and paste are not
presently implemented). See Section 3.6, “The "Edit" menu”.
View
This menu controls the display of the captured data, including colorization of packets,
zooming the font, showing a packet in a separate window, expanding and collapsing
trees in packet details, .... See Section 3.7, “The "View" menu”.
Go
This menu contains items to go to a specific packet. See Section 3.8, “The "Go"
menu”.
Capture
This menu allows you to start and stop captures and to edit capture filters. See Section 3.9, “The "Capture" menu”.
Analyze
This menu contains items to manipulate display filters, enable or disable the dissection
of protocols, configure user specified decodes and follow a TCP stream. See Section 3.10, “The "Analyze" menu”.
Statistics
This menu contains items to display various statistic windows, including a summary of
the packets that have been captured, display protocol hierarchy statistics and much
more. See Section 3.11, “The "Statistics" menu”.
Tools
This menu contains various tools available in Wireshark, such as creating Firewall
ACL Rules. See Section 3.12, “The "Tools" menu”.
Help
This menu contains items to help the user, e.g. access to some basic help, a list of the
supported protocols, manual pages, online access to some of the webpages, and the
usual about dialog. See Section 3.13, “The "Help" menu”.
Each of these menu items is described in more detail in the sections that follow.
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User Interface
Tip!
You can access menu items directly or by pressing the corresponding accelerator keys
which are shown at the right side of the menu. For example, you can press the Control (or
Strg in German) and the K keys together to open the capture dialog.
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User Interface
3.5. The "File" menu
The Wireshark file menu contains the fields shown in Table 3.2, “File menu items”.
Figure 3.3. The "File" Menu
Table 3.2. File menu items
Menu Item
Accelerator
Open...
Ctrl+O
Description
This menu item brings up the file open dialog box that allows you
to load a capture file for viewing. It is discussed in more detail in
Section 5.2.1, “The "Open Capture File" dialog box”.
Open Recent
This menu item shows a submenu containing the recently opened
capture files. Clicking on one of the submenu items will open the
corresponding capture file directly.
Merge...
This menu item brings up the merge file dialog box that allows
you to merge a capture file into the currently loaded one. It is discussed in more detail in Section 5.4, “Merging capture files”.
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User Interface
Menu Item
Accelerator
Close
Ctrl+W
Description
This menu item closes the current capture. If you haven't saved
the capture, you will be asked to do so first (this can be disabled
by a preference setting).
-----Save
Ctrl+S
This menu item saves the current capture. If you have not set a
default capture file name (perhaps with the -w <capfile> option),
Wireshark pops up the Save Capture File As dialog box (which is
discussed further in Section 5.3.1, “The "Save Capture File As"
dialog box”).
Note!
If you have already saved the current capture, this
menu item will be greyed out.
Note!
You cannot save a live capture while the capture is
in progress. You must stop the capture in order to
save.
Save As...
Shift+Ctrl+S
This menu item allows you to save the current capture file to
whatever file you would like. It pops up the Save Capture File As
dialog box (which is discussed further in Section 5.3.1, “The
"Save Capture File As" dialog box”).
-----File Set > List
Files
File Set > Next
File
File Set > Previous File
This menu item allows you to show a list of files in a file set. It
pops up the Wireshark List File Set dialog box (which is discussed further in Section 5.5, “File Sets”).
If the currently loaded file is part of a file set, jump to the next
file in the set. If it isn't part of a file set or just the last file in that
set, this item is greyed out.
If the currently loaded file is part of a file set, jump to the previous file in the set. If it isn't part of a file set or just the first file in
that set, this item is greyed out.
-----Export
"Plain
file...
> as
Text"
Export > as
"PostScript"
file...
This menu item allows you to export all (or some) of the packets
in the capture file to a plain ASCII text file. It pops up the Wireshark Export dialog box (which is discussed further in Section 5.6.1, “The "Export as Plain Text File" dialog box”).
This menu item allows you to export all (or some) of the packets
in the capture file to a PostScript file. It pops up the Wireshark
Export dialog box (which is discussed further in Section 5.6.2,
“The "Export as PostScript File" dialog box”).
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User Interface
Menu Item
Accelerator
Export > as
"CSV"
(Comma Separated Values
packet
summary) file...
Description
This menu item allows you to export all (or some) of the packet
summaries in the capture file to a .csv file (e.g. used by spreadsheet programs). It pops up the Wireshark Export dialog box
(which is discussed further in Section 5.6.3, “The "Export as
CSV (Comma Separated Values) File" dialog box”).
Export > as "C
Arrays"
(packet bytes)
file...
This menu item allows you to export all (or some) of the packet
bytes in the capture file to a .c file so you can import the stream
data into your own C program. It pops up the Wireshark Export
dialog box (which is discussed further in Section 5.6.4, “The "Export as C Arrays (packet bytes) file" dialog box”).
-----Export > as
"PSML" file...
This menu item allows you to export all (or some) of the packets
in the capture file to a PSML (packet summary markup language)
XML file. It pops up the Wireshark Export dialog box (which is
discussed further in Section 5.6.5, “The "Export as PSML File"
dialog box”).
Export > as
"PDML" file...
This menu item allows you to export all (or some) of the packets
in the capture file to a PDML (packet details markup language)
XML file. It pops up the Wireshark Export dialog box (which is
discussed further in Section 5.6.6, “The "Export as PDML File"
dialog box”).
-----Export > Selec- Ctrl+H
ted
Packet
Bytes...
Objects > HTTP
This menu item allows you to export the currently selected bytes
in the packet bytes pane to a binary file. It pops up the Wireshark
Export dialog box (which is discussed further in Section 5.6.7,
“The "Export selected packet bytes" dialog box”)
This menu item allows you to export all or some of the captured
HTTP objects into local files. It pops up the Wireshark HTTP object list (which is discussed further in Section 5.6.8, “The "Export
Objects" dialog box”)
-----Print...
Ctrl+P
This menu item allows you to print all (or some) of the packets in
the capture file. It pops up the Wireshark Print dialog box (which
is discussed further in Section 5.7, “Printing packets”).
-----Quit
Ctrl+Q
This menu item allows you to quit from Wireshark. Wireshark
will ask to save your capture file if you haven't previously saved
it (this can be disabled by a preference setting).
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User Interface
3.6. The "Edit" menu
The Wireshark Edit menu contains the fields shown in Table 3.3, “Edit menu items”.
Figure 3.4. The "Edit" Menu
Table 3.3. Edit menu items
Menu Item
Copy >
scription
Accelerator
Description
De- Shift+Ctrl+D
This menu item will copy the description of the selected item in
the detail view to the clipboard.
Copy > Field- Shift+Ctrl+F
name
Copy > Value
This menu item will copy the fieldname of the selected item in
the detail view to the clipboard.
Shift+Ctrl+V
This menu item will copy the value of the selected item in the detail view to the clipboard.
Copy > As Fil- Shift+Ctrl+C
ter
This menu item will use the selected item in the detail view to
create a display filter. This display filter is then copied to the
clipboard.
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User Interface
Menu Item
Accelerator
Description
-----Find Packet...
Ctrl+F
This menu item brings up a dialog box that allows you to find a
packet by many criteria. There is further information on finding
packets in Section 6.8, “Finding packets”.
Find Next
Ctrl+N
This menu item tries to find the next packet matching the settings
from "Find Packet...".
Find Previous
Ctrl+B
This menu item tries to find the previous packet matching the settings from "Find Packet...".
-----Mark Packet Ctrl+M
(toggle)
Find
Mark
This menu item "marks" the currently selected packet. See Section 6.10, “Marking packets” for details.
Next Shift+Ctrl+N
Find the next marked packet.
Find Previous Shift+Ctrl+B
Mark
Find the previous marked packet.
Mark All Packets
This menu item "marks" all packets.
Unmark
Packets
This menu item "unmarks" all marked packets.
All
-----Set Time Refer- Ctrl+T
ence (toggle)
This menu item set a time reference on the currently selected
packet. See Section 6.11.1, “Packet time referencing” for more
information about the time referenced packets.
Find Next Reference
This menu item tries to find the next time referenced packet.
Find Previous
Reference
This menu item tries to find the previous time referenced packet.
-----Configuration
Profiles...
Shift-Ctrl-A
Preferences...
Shift+Ctrl+P
This menu item brings up a dialog box for handling configuration
profiles. More detail is provided in Section 9.6, “Configuration
Profiles”.
This menu item brings up a dialog box that allows you to set
preferences for many parameters that control Wireshark. You can
also save your preferences so Wireshark will use them the next
time you start it. More detail is provided in Section 9.5,
“Preferences”.
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User Interface
3.7. The "View" menu
The Wireshark View menu contains the fields shown in Table 3.4, “View menu items”.
Figure 3.5. The "View" Menu
Table 3.4. View menu items
Menu Item
Accelerator
Description
Main Toolbar
This menu item hides or shows the main toolbar, see Section 3.14, “The "Main" toolbar”.
Filter Toolbar
This menu item hides or shows the filter toolbar, see Section 3.15, “The "Filter" toolbar”.
Statusbar
This menu item hides or shows the statusbar, see Section 3.19,
“The Statusbar”.
-----Packet List
This menu item hides or shows the packet list pane, see Sec39
User Interface
Menu Item
Accelerator
Description
tion 3.16, “The "Packet List" pane”.
Packet Details
This menu item hides or shows the packet details pane, see Section 3.17, “The "Packet Details" pane”.
Packet Bytes
This menu item hides or shows the packet bytes pane, see Section 3.18, “The "Packet Bytes" pane”.
-----Time Display
Format > Date
and Time of
Day:
1970-01-01
01:02:03.12345
6
Selecting this tells Wireshark to display the time stamps in date
and time of day format, see Section 6.11, “Time display formats
and time references”.
Note!
The fields "Time of Day", "Date and Time of Day",
"Seconds Since Beginning of Capture", "Seconds
Since Previous Captured Packet" and "Seconds
Since Previous Displayed Packet" are mutually exclusive.
Time Display
Format > Time
of
Day:
01:02:03.12345
6
Time Display
Format
>
Seconds Since
Beginning
of
Capture:
123.123456
Time Display
Format
>
Seconds Since
Previous Captured Packet:
1.123456
Time Display
Format
>
Seconds Since
Previous Displayed Packet:
1.123456
Time Display
Format
>
Seconds Since
Epoch
(1970-01-01):
1234567890.123
456
Selecting this tells Wireshark to display time stamps in time of
day format, see Section 6.11, “Time display formats and time references”.
Selecting this tells Wireshark to display time stamps in seconds
since beginning of capture format, see Section 6.11, “Time display formats and time references”.
Selecting this tells Wireshark to display time stamps in seconds
since previous captured packet format, see Section 6.11, “Time
display formats and time references”.
Selecting this tells Wireshark to display time stamps in seconds
since previous displayed packet format, see Section 6.11, “Time
display formats and time references”.
Selecting this tells Wireshark to display time stamps in seconds
since 1970-01-01 00:00:00, see Section 6.11, “Time display
formats and time references”.
Time Display
Format > -----40
User Interface
Menu Item
Accelerator
Time Display
Format > Automatic
(File
Format Precision)
Description
Selecting this tells Wireshark to display time stamps with the precision given by the capture file format used, see Section 6.11,
“Time display formats and time references”.
Note!
The fields "Automatic", "Seconds" and "...seconds"
are mutually exclusive.
Time Display
Format
>
Seconds: 0
Selecting this tells Wireshark to display time stamps with a precision of one second, see Section 6.11, “Time display formats and
time references”.
Time Display
Format
>
...seconds: 0....
Selecting this tells Wireshark to display time stamps with a precision of one second, decisecond, centisecond, millisecond, microsecond or nanosecond, see Section 6.11, “Time display formats
and time references”.
Name Resolution > Resolve
Name
This item allows you to trigger a name resolve of the current
packet only, see Section 7.7, “Name Resolution”.
Name Resolution > Enable
for MAC Layer
This item allows you to control whether or not Wireshark translates MAC addresses into names, see Section 7.7, “Name Resolution”.
Name Resolution > Enable
for
Network
Layer
This item allows you to control whether or not Wireshark translates network addresses into names, see Section 7.7, “Name Resolution”.
Name Resolution > Enable
for Transport
Layer
This item allows you to control whether or not Wireshark translates transport addresses into names, see Section 7.7, “Name Resolution”.
Colorize Packet
List
This item allows you to control whether or not Wireshark should
colorize the packet list.
Note!
Enabling colorization will slow down the display of
new packets while capturing / loading capture files.
Auto Scroll in
Live Capture
This item allows you to specify that Wireshark should scroll the
packet list pane as new packets come in, so you are always looking at the last packet. If you do not specify this, Wireshark simply
adds new packets onto the end of the list, but does not scroll the
packet list pane.
-----Zoom In
Ctrl++
Zoom into the packet data (increase the font size).
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User Interface
Menu Item
Accelerator
Zoom Out
Ctrl+-
Description
Zoom out of the packet data (decrease the font size).
Normal Size
Ctrl+=
Set zoom level back to 100% (set font size back to normal).
Resize
Columns
All
Resize all column widths so the content will fit into it.
Note!
Resizing may take a significant amount of time, especially if a large capture file is loaded.
-----Expand
trees
SubThis menu item expands the currently selected subtree in the
packet details tree.
Expand All
Wireshark keeps a list of all the protocol subtrees that are expanded, and uses it to ensure that the correct subtrees are expanded
when you display a packet. This menu item expands all subtrees
in all packets in the capture.
Collapse All
This menu item collapses the tree view of all packets in the capture list.
-----Colorize Conversation
This menu item brings up a submenu that allows you to color
packets in the packet list pane based on the addresses of the currently selected packet. This makes it easy to distinguish packets
belonging to different conversations. Section 9.3, “Packet colorization”.
Colorize Conversation
>
Color 1-10
These menu items enable one of the ten temporary color filters
based on the currently selected conversation.
Colorize Conversation > Reset coloring
This menu item clears all temporary coloring rules.
Colorize Conversation
>
New Coloring
Rule...
This menu item opens a dialog window in which a new permanent coloring rule can be created based on the currently selected
conversation.
Coloring
Rules...
This menu item brings up a dialog box that allows you to color
packets in the packet list pane according to filter expressions you
choose. It can be very useful for spotting certain types of packets,
see Section 9.3, “Packet colorization”.
-----Show Packet in
New Window
This menu item brings up the selected packet in a separate window. The separate window shows only the tree view and byte
view panes.
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User Interface
Menu Item
Accelerator
Reload
Ctrl-R
Description
This menu item allows you to reload the current capture file.
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User Interface
3.8. The "Go" menu
The Wireshark Go menu contains the fields shown in Table 3.5, “Go menu items”.
Figure 3.6. The "Go" Menu
Table 3.5. Go menu items
Menu Item
Accelerator
Back
Alt+Left
Description
Jump to the recently visited packet in the packet history, much
like the page history in a web browser.
Forward
Alt+Right
Jump to the next visited packet in the packet history, much like
the page history in a web browser.
Go to Packet... Ctrl-G
Bring up a dialog box that allows you to specify a packet number,
and then goes to that packet. See Section 6.9, “Go to a specific
packet” for details.
Go to Corresponding Packet
Go to the corresponding packet of the currently selected protocol
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User Interface
Menu Item
Accelerator
Description
field. If the selected field doesn't correspond to a packet, this item
is greyed out.
-----Previous Pack- Ctrl+Up
et
Next Packet
Move to the previous packet in the list. This can be used to move
to the previous packet even if the packet list doesn't have keyboard focus.
Ctrl+Down
Move to the next packet in the list. This can be used to move to
the previous packet even if the packet list doesn't have keyboard
focus.
First Packet
Jump to the first packet of the capture file.
Last Packet
Jump to the last packet of the capture file.
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User Interface
3.9. The "Capture" menu
The Wireshark Capture menu contains the fields shown in Table 3.6, “Capture menu items”.
Figure 3.7. The "Capture" Menu
Table 3.6. Capture menu items
Menu Item
Accelerator
Description
Interfaces...
This menu item brings up a dialog box that shows what's going
on at the network interfaces Wireshark knows of, see Section 4.4,
“The "Capture Interfaces" dialog box”) .
Options...
Ctrl+K
This menu item brings up the Capture Options dialog box
(discussed further in Section 4.5, “The "Capture Options" dialog
box”) and allows you to start capturing packets.
Start
Immediately start capturing packets with the same settings than
the last time.
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User Interface
Menu Item
Accelerator
Stop
Ctrl+E
Description
This menu item stops the currently running capture, see Section 4.10.1, “Stop the running capture”) .
Restart
This menu item stops the currently running capture and starts
again with the same options, this is just for convenience.
Capture
ters...
FilThis menu item brings up a dialog box that allows you to create
and edit capture filters. You can name filters, and you can save
them for future use. More detail on this subject is provided in
Section 6.6, “Defining and saving filters”
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User Interface
3.10. The "Analyze" menu
The Wireshark Analyze menu contains the fields shown in Table 3.7, “Analyze menu items”.
Figure 3.8. The "Analyze" Menu
Table 3.7. Analyze menu items
Menu Item
Display
ters...
Accelerator
Description
Fil-
Display Filter
Macros...
Apply as Filter
> ...
This menu item brings up a dialog box that allows you to create
and edit display filters. You can name filters, and you can save
them for future use. More detail on this subject is provided in
Section 6.6, “Defining and saving filters”
This menu item brings up a dialog box that allows you to create
and edit display filter macros. You can name filter macros, and
you can save them for future use. More detail on this subject is
provided in Section 6.7, “Defining and saving filter macros”
These menu items will change the current display filter and apply
the changed filter immediately. Depending on the chosen menu
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User Interface
Menu Item
Accelerator
Description
item, the current display filter string will be replaced or appended
to by the selected protocol field in the packet details pane.
Prepare a Filter > ...
These menu items will change the current display filter but won't
apply the changed filter. Depending on the chosen menu item, the
current display filter string will be replaced or appended to by the
selected protocol field in the packet details pane.
-----Enabled Proto- Shift+Ctrl+R
cols...
This menu item allows the user to enable/disable protocol dissectors, see Section 9.4.1, “The "Enabled Protocols" dialog box”
Decode As...
This menu item allows the user to force Wireshark to decode certain packets as a particular protocol, see Section 9.4.2, “User Specified Decodes”
User Specified
Decodes...
This menu item allows the user to force Wireshark to decode certain packets as a particular protocol, see Section 9.4.3, “Show
User Specified Decodes”
-----Follow
Stream
TCP
Follow
Stream
UDP
Follow
Stream
SSL
This menu item brings up a separate window and displays all the
TCP segments captured that are on the same TCP connection as a
selected packet, see Section 7.2, “Following TCP streams”
Same functionality as "Follow TCP Stream" but for UDP
streams.
Same functionality as "Follow TCP Stream" but for SSL streams.
XXX - how to provide the SSL keys?
Expert Info
Open a dialog showing some expert information about the captured packets in a log style display. The amount of information
will depend on the protocol and varies from very detailed to none
existing. This is currently a work in progress. XXX - add a new
section about this and link from here
Expert
Info
Composite
Conversation
Filter > ...
Same information as in "Expert Info" but trying to group items
together for faster analysis.
In this menu you will find conversation filter for various protocols.
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User Interface
3.11. The "Statistics" menu
The Wireshark Statistics menu contains the fields shown in Table 3.8, “Statistics menu items”.
Figure 3.9. The "Statistics" Menu
All menu items will bring up a new window showing specific statistical information.
Table 3.8. Statistics menu items
Menu Item
Accelerator
Description
Summary
Show information about the data captured, see Section 8.2, “The
"Summary" window”.
Protocol Hierarchy
Display a hierarchical tree of protocol statistics, see Section 8.3,
“The "Protocol Hierarchy" window”.
Conversations
Display a list of conversations (traffic between two endpoints),
see Section 8.4.2, “The "Conversations" window”.
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User Interface
Menu Item
Accelerator
Description
Endpoints
Display a list of endpoints (traffic to/from an address), see Section 8.5.2, “The "Endpoints" window”.
IO Graphs
Display user specified graphs (e.g. the number of packets in the
course of time), see Section 8.6, “The "IO Graphs" window”.
-----Conversation
List
Display a list of conversations, obsoleted by the combined window of Conversations above, see Section 8.4.3, “The protocol
specific "Conversation List" windows”.
Endpoint List
Display a list of endpoints, obsoleted by the combined window of
Endpoints above, see Section 8.5.3, “The protocol specific "Endpoint List" windows”.
Service
Response Time
Display the time between a request and the corresponding response, see Section 8.10, “Service Response Time”.
-----ANSI
See Section 8.11, “The protocol specific statistics windows”
Fax T38 Analysis...
See Section 8.11, “The protocol specific statistics windows”
GSM
See Section 8.11, “The protocol specific statistics windows”
H.225...
See Section 8.11, “The protocol specific statistics windows”
LTE MAC
See Section 8.9, “LTE MAC Traffic Statistics”
MTP3
See Section 8.11, “The protocol specific statistics windows”
RTP
See Section 8.11, “The protocol specific statistics windows”
SCTP
See Section 8.11, “The protocol specific statistics windows”
SIP
See Section 8.11, “The protocol specific statistics windows”
VoIP Calls...
See Section 8.11, “The protocol specific statistics windows”
WAP-WSP...
See Section 8.11, “The protocol specific statistics windows”
-----BOOTP-DHCP...
See Section 8.11, “The protocol specific statistics windows”
Flow Graph...
See Section 8.11, “The protocol specific statistics windows”
HTTP
HTTP request/response statistics, see Section 8.11, “The protocol
specific statistics windows”
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User Interface
Menu Item
Accelerator
Description
IP Addresses...
See Section 8.11, “The protocol specific statistics windows”
IP
Destinations...
See Section 8.11, “The protocol specific statistics windows”
IP
Protocol
Types...
See Section 8.11, “The protocol specific statistics windows”
ISUP Messages
See Section 8.11, “The protocol specific statistics windows”
ONC-RPC Programs
See Section 8.11, “The protocol specific statistics windows”
Packet
Lengths...
See Section 8.11, “The protocol specific statistics windows”
SMPP Operations...
See Section 8.11, “The protocol specific statistics windows”
TCP
Stream
Graph
See Section 8.11, “The protocol specific statistics windows”
UCP
sages...
See Section 8.11, “The protocol specific statistics windows”
Mes-
UDP Multicast
Streams
See Section 8.11, “The protocol specific statistics windows”
WLAN Traffic
See Section 8.8, “WLAN Traffic Statistics”
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User Interface
3.12. The "Tools" menu
The Wireshark Tools menu contains the fields shown in Table 3.9, “Tools menu items”.
Table 3.9. Tools menu items
Menu Item
Firewall
Rules
Accelerator
Description
ACL
This allows you to create command-line ACL rules for many different firewall products, including Cisco IOS, Linux Netfilter
(iptables), OpenBSD pf and Windows Firewall (via netsh). Rules
for MAC addresses, IPv4 addresses, TCP and UDP ports, and
IPv4+port combinations are supported.
It is assumed that the rules will be applied to an outside interface.
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User Interface
3.13. The "Help" menu
The Wireshark Help menu contains the fields shown in Table 3.10, “Help menu items”.
Figure 3.10. The "Help" Menu
Table 3.10. Help menu items
Menu Item
Accelerator
Contents
F1
Description
This menu item brings up a basic help system.
FAQ's
This menu item starts a Web browser showing various FAQ's.
Manual Pages
> ...
This menu item starts a Web browser showing one of the locally
installed html manual pages.
-----Wireshark Online > ...
This menu item starts a Web browser showing the chosen
webpage from: http://www.wireshark.org.
-----54
User Interface
Menu Item
Accelerator
Supported Protocols (slow!)
Description
This menu item brings up a dialog box showing the supported
protocols and protocol fields.
-----About
shark
WireThis menu item brings up an information window that provides
some information on Wireshark, such as the plugins, the used
folders, ...
Note!
Calling a Web browser might be unsupported in your version of Wireshark. If this is the
case, the corresponding menu items will be hidden.
Note!
If calling a Web browser fails on your machine, maybe because just nothing happens or the
browser is started but no page is shown, have a look at the web browser setting in the preferences dialog.
55
User Interface
3.14. The "Main" toolbar
The main toolbar provides quick access to frequently used items from the menu. This toolbar cannot be
customized by the user, but it can be hidden using the View menu, if the space on the screen is needed to
show even more packet data.
As in the menu, only the items useful in the current program state will be available. The others will be
greyed out (e.g. you cannot save a capture file if you haven't loaded one).
Figure 3.11. The "Main" toolbar
Table 3.11. Main toolbar items
Toolbar Toolbar Item
Icon
Interfaces...
Options...
Corresponding
Menu Item
Capture/Interfaces...
Description
This item brings up the Capture Interfaces List dialog
box (discussed further in Section 4.3, “Start Capturing”).
Capture/Options...
This item brings up the Capture Options dialog box
(discussed further in Section 4.3, “Start Capturing”)
and allows you to start capturing packets.
Start
Capture/Start
This item starts capturing packets with the options
form the last time.
Stop
Capture/Stop
This item stops the currently running live capture
process Section 4.3, “Start Capturing”).
Restart
Capture/Restart
This item stops the currently running live capture
process and restarts it again, for convenience.
-----Open...
File/Open...
This item brings up the file open dialog box that allows you to load a capture file for viewing. It is discussed in more detail in Section 5.2.1, “The "Open
Capture File" dialog box”.
Save As...
File/Save As...
This item allows you to save the current capture file
to whatever file you would like. It pops up the Save
Capture File As dialog box (which is discussed further in Section 5.3.1, “The "Save Capture File As"
dialog box”).
Note!
If you currently have a temporary cap56
User Interface
Toolbar Toolbar Item
Icon
Corresponding
Menu Item
Description
ture file, the Save icon
will be
shown instead.
Close
File/Close
This item closes the current capture. If you have not
saved the capture, you will be asked to save it first.
Reload
View/Reload
This item allows you to reload the current capture
file.
Print...
File/Print...
This item allows you to print all (or some of) the
packets in the capture file. It pops up the Wireshark
Print dialog box (which is discussed further in Section 5.7, “Printing packets”).
-----Find Packet...
Edit/Find Packet...
This item brings up a dialog box that allows you to
find a packet. There is further information on finding
packets in Section 6.8, “Finding packets”.
Go Back
Go/Go Back
This item jumps back in the packet history.
Go Forward
Go/Go Forward
This item jumps forward in the packet history.
Go to Packet...
Go/Go to Packet...
This item brings up a dialog box that allows you to
specify a packet number to go to that packet.
Go
To
Packet
First Go/First Packet
This item jumps to the first packet of the capture file.
Go To Last Pack- Go/Last Packet
et
This item jumps to the last packet of the capture file.
-----Colorize
View/Colorize
Colorize the packet list (or not).
Auto Scroll
Live Capture
in View/Auto Scroll
Auto scroll packet list while doing a live capture (or
in Live Capture
not).
-----Zoom In
View/Zoom In
Zoom into the packet data (increase the font size).
Zoom Out
View/Zoom Out
Zoom out of the packet data (decrease the font size).
Normal Size
View/Normal Size
Set zoom level back to 100%.
57
User Interface
Toolbar Toolbar Item
Icon
Resize Columns
Corresponding
Menu Item
View/Resize
Columns
Description
Resize columns, so the content fits into them.
-----Capture Filters... Capture/Capture
Filters...
Display Filters...
Analyze/Display
Filters...
Coloring Rules... View/Coloring
Rules...
Preferences...
This item brings up a dialog box that allows you to
create and edit capture filters. You can name filters,
and you can save them for future use. More detail on
this subject is provided in Section 6.6, “Defining and
saving filters”.
This item brings up a dialog box that allows you to
create and edit display filters. You can name filters,
and you can save them for future use. More detail on
this subject is provided in Section 6.6, “Defining and
saving filters”.
This item brings up a dialog box that allows you color packets in the packet list pane according to filter
expressions you choose. It can be very useful for
spotting certain types of packets. More detail on this
subject is provided in Section 9.3, “Packet colorization”.
Edit/Preferences
This item brings up a dialog box that allows you to
set preferences for many parameters that control
Wireshark. You can also save your preferences so
Wireshark will use them the next time you start it.
More detail is provided in Section 9.5, “Preferences”
-----Help
Help/Contents
This item brings up help dialog box.
58
User Interface
3.15. The "Filter" toolbar
The filter toolbar lets you quickly edit and apply display filters. More information on display filters is
available in Section 6.3, “Filtering packets while viewing”.
Figure 3.12. The "Filter" toolbar
Table 3.12. Filter toolbar items
Toolbar Toolbar Item
Icon
Description
Filter:
Brings up the filter construction dialog, described in Figure 6.7, “The
"Capture Filters" and "Display Filters" dialog boxes”.
Filter input
The area to enter or edit a display filter string, see Section 6.4, “Building
display filter expressions” . A syntax check of your filter string is done
while you are typing. The background will turn red if you enter an incomplete or invalid string, and will become green when you enter a valid
string. You can click on the pull down arrow to select a previouslyentered filter string from a list. The entries in the pull down list will remain available even after a program restart.
Note!
After you've changed something in this field, don't forget to
press the Apply button (or the Enter/Return key), to apply
this filter string to the display.
Note!
This field is also where the current filter in effect is displayed.
Expression...
The middle button labeled "Add Expression..." opens a dialog box that
lets you edit a display filter from a list of protocol fields, described in
Section 6.5, “The "Filter Expression" dialog box”
Clear
Reset the current display filter and clears the edit area.
Apply
Apply the current value in the edit area as the new display filter.
Note!
Applying a display filter on large capture files might take
quite a long time!
59
User Interface
Toolbar Toolbar Item
Icon
Description
60
User Interface
3.16. The "Packet List" pane
The packet list pane displays all the packets in the current capture file.
Figure 3.13. The "Packet List" pane
Each line in the packet list corresponds to one packet in the capture file. If you select a line in this pane,
more details will be displayed in the "Packet Details" and "Packet Bytes" panes.
While dissecting a packet, Wireshark will place information from the protocol dissectors into the
columns. As higher level protocols might overwrite information from lower levels, you will typically see
the information from the highest possible level only.
For example, let's look at a packet containing TCP inside IP inside an Ethernet packet. The Ethernet dissector will write its data (such as the Ethernet addresses), the IP dissector will overwrite this by its own
(such as the IP addresses), the TCP dissector will overwrite the IP information, and so on.
There are a lot of different columns available. Which columns are displayed can be selected by preference settings, see Section 9.5, “Preferences”.
The default columns will show:
•
No. The number of the packet in the capture file. This number won't change, even if a display filter
is used.
•
Time The timestamp of the packet. The presentation format of this timestamp can be changed, see
Section 6.11, “Time display formats and time references”.
•
Source The address where this packet is coming from.
•
Destination The address where this packet is going to.
•
Protocol The protocol name in a short (perhaps abbreviated) version.
•
Info Additional information about the packet content.
There is a context menu (right mouse click) available, see details in Figure 6.3, “Pop-up menu of the
"Packet List" pane”.
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User Interface
3.17. The "Packet Details" pane
The packet details pane shows the current packet (selected in the "Packet List" pane) in a more detailed
form.
Figure 3.14. The "Packet Details" pane
This pane shows the protocols and protocol fields of the packet selected in the "Packet List" pane. The
protocols and fields of the packet are displayed using a tree, which can be expanded and collapsed.
There is a context menu (right mouse click) available, see details in Figure 6.4, “Pop-up menu of the
"Packet Details" pane”.
Some protocol fields are specially displayed.
•
Generated fields Wireshark itself will generate additional protocol fields which are surrounded by
brackets. The information in these fields is derived from the known context to other packets in the
capture file. For example, Wireshark is doing a sequence/acknowledge analysis of each TCP stream,
which is displayed in the [SEQ/ACK analysis] fields of the TCP protocol.
•
Links If Wireshark detected a relationship to another packet in the capture file, it will generate a link
to that packet. Links are underlined and displayed in blue. If double-clicked, Wireshark jumps to the
corresponding packet.
62
User Interface
3.18. The "Packet Bytes" pane
The packet bytes pane shows the data of the current packet (selected in the "Packet List" pane) in a hexdump style.
Figure 3.15. The "Packet Bytes" pane
As usual for a hexdump, the left side shows the offset in the packet data, in the middle the packet data is
shown in a hexadecimal representation and on the right the corresponding ASCII characters (or . if not
appropriate) are displayed.
Depending on the packet data, sometimes more than one page is available, e.g. when Wireshark has reassembled some packets into a single chunk of data, see Section 7.6, “Packet Reassembling”. In this
case there are some additional tabs shown at the bottom of the pane to let you select the page you want
to see.
Figure 3.16. The "Packet Bytes" pane with tabs
Note!
The additional pages might contain data picked from multiple packets.
The context menu (right mouse click) of the tab labels will show a list of all available pages. This can be
helpful if the size in the pane is too small for all the tab labels.
63
User Interface
3.19. The Statusbar
The statusbar displays informational messages.
In general, the left side will show context related information, the middle part will show the current
number of packets, and the right side will show the selected configuration profile. Drag the handles
between the text areas to change the size.
Figure 3.17. The initial Statusbar
This statusbar is shown while no capture file is loaded, e.g. when Wireshark is started.
Figure 3.18. The Statusbar with a loaded capture file
•
The colorized bullet on the left shows the highest expert info level found in the currently loaded
capture file. Hovering the mouse over this icon will show a textual description of the expert info
level, and clicking the icon will bring up the Expert Infos dialog box. For a detailed description of
expert info, see Section 7.3, “Expert Infos”.
•
The left side shows information about the capture file, its name, its size and the elapsed time while it
was being captured.
•
The middle part shows the current number of packets in the capture file. The following values are
displayed:
•
•
Packets: the number of captured packets
•
Displayed: the number of packets currently being displayed
•
Marked: the number of marked packets
•
Dropped: the number of dropped packets (only displayed if Wireshark was unable to capture all
packets)
The right side shows the selected configuration profile. Clicking in this part of the statusbar will
bring up a menu with all available configuration profiles, and selecting from this list will change the
configuration profile.
Figure 3.19. The Statusbar with a configuration profile menu
64
User Interface
For a detailed description of configuration profiles, see Section 9.6, “Configuration Profiles”.
Figure 3.20. The Statusbar with a selected protocol field
This is displayed if you have selected a protocol field from the "Packet Details" pane.
Tip!
The value between the brackets (in this example arp.opcode) can be used as a display filter string, representing the selected protocol field.
Figure 3.21. The Statusbar with a display filter message
This is displayed if you are trying to use a display filter which may have unexpected results. For a detailed description, see Section 6.4.4, “A common mistake”.
65
User Interface
66
Chapter 4. Capturing Live Network
Data
4.1. Introduction
Capturing live network data is one of the major features of Wireshark.
The Wireshark capture engine provides the following features:
•
Capture from different kinds of network hardware (Ethernet, Token Ring, ATM, ...).
•
Stop the capture on different triggers like: amount of captured data, captured time, captured number
of packets.
•
Simultaneously show decoded packets while Wireshark keeps on capturing.
•
Filter packets, reducing the amount of data to be captured, see Section 4.9, “Filtering while capturing”.
•
Capturing into multiple files while doing a long term capture, and in addition the option to form a
ringbuffer of these files, keeping only the last x files, useful for a "very long term" capture, see Section 4.7, “Capture files and file modes”.
The capture engine still lacks the following features:
•
Simultaneous capturing from multiple network interfaces (however, you can start multiple instances
of Wireshark and merge capture files later).
•
Stop capturing (or doing some other action), depending on the captured data.
67
Capturing Live Network Data
4.2. Prerequisites
Setting up Wireshark to capture packets for the first time can be tricky.
Tip!
A comprehensive guide "How To
tp://wiki.wireshark.org/CaptureSetup.
setup
a
Capture"
is
available
at:
ht-
Here are some common pitfalls:
•
You need to have root / Administrator privileges to start a live capture.
•
You need to choose the right network interface to capture packet data from.
•
You need to capture at the right place in the network to see the traffic you want to see.
•
... and a lot more!.
If you have any problems setting up your capture environment, you should have a look at the guide mentioned above.
68
Capturing Live Network Data
4.3. Start Capturing
One of the following methods can be used to start capturing packets with Wireshark:
•
You can get an overview of the available local interfaces using the "
Capture Interfaces" dialog
box, see Figure 4.1, “The "Capture Interfaces" dialog box on Microsoft Windows” or Figure 4.2,
“The "Capture Interfaces" dialog box on Unix/Linux”. You can start a capture from this dialog box,
using (one of) the "Capture" button(s).
•
You can start capturing using the "
Capture Options" dialog box, see Figure 4.3, “The "Cap-
ture Options" dialog box”.
•
If you have selected the right capture options before, you can immediately start a capture using the "
Capture Start" menu / toolbar item. The capture process will start immediately.
•
If you already know the name of the capture interface, you can start Wireshark from the command
line and use the following:
wireshark -i eth0 -k
This will start Wireshark capturing on interface eth0, more details can be found at: Section 9.2,
“Start Wireshark from the command line”.
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Capturing Live Network Data
4.4. The "Capture Interfaces" dialog box
When you select "Interfaces..." from the Capture menu, Wireshark pops up the "Capture Interfaces" dialog box as shown in Figure 4.1, “The "Capture Interfaces" dialog box on Microsoft Windows” or Figure 4.2, “The "Capture Interfaces" dialog box on Unix/Linux”.
This dialog consumes lot's of system resources!
As the "Capture Interfaces" dialog is showing live captured data, it is consuming a lot of
system resources. Close this dialog as soon as possible to prevent excessive system load.
Not all available interfaces may be displayed!
This dialog box will only show the local interfaces Wireshark knows of. It will not show
interfaces marked as hidden in the "Interface Options" preferences dialog. As Wireshark
might not be able to detect all local interfaces, and it cannot detect the remote interfaces
available, there could be more capture interfaces available than listed.
Figure 4.1. The "Capture Interfaces" dialog box on Microsoft Windows
Figure 4.2. The "Capture Interfaces" dialog box on Unix/Linux
Device (Unix/Linux only)
The interface device name.
Description
The interface description provided by the operating system.
70
Capturing Live Network Data
IP
The first IP address Wireshark could resolve from this interface.
If no address could be resolved (e.g. no DHCP server available),
"unknown" will be displayed. If more than one IP address could
be resolved, only the first is shown (unpredictable which one in
that case).
Packets
The number of packets captured from this interface, since this dialog was opened. Will be greyed out, if no packet was captured in
the last second.
Packets/s
Number of packets captured in the last second. Will be greyed
out, if no packet was captured in the last second.
Stop
Stop a currently running capture.
Start
Start a capture on this interface immediately, using the settings
from the last capture.
Options
Open the Capture Options dialog with this interface selected, see
Section 4.5, “The "Capture Options" dialog box”.
Details (Microsoft Windows only)
Open a dialog with detailed information about the interface, see
Section 4.6, “The "Interface Details" dialog box”.
Help
Show this help page.
Close
Close this dialog box.
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Capturing Live Network Data
4.5. The "Capture Options" dialog box
When you select Start... from the Capture menu (or use the corresponding item in the "Main" toolbar),
Wireshark pops up the "Capture Options" dialog box as shown in Figure 4.3, “The "Capture Options"
dialog box”.
Figure 4.3. The "Capture Options" dialog box
Tip!
If you are unsure which options to choose in this dialog box, just try keeping the defaults
as this should work well in many cases.
You can set the following fields in this dialog box:
72
Capturing Live Network Data
4.5.1. Capture frame
Interface
This field specifies the interface you want to capture on. You can
only capture on one interface, and you can only capture on interfaces that Wireshark has found on the system. It is a drop-down
list, so simply click on the button on the right hand side and select
the interface you want. It defaults to the first non-loopback interface that supports capturing, and if there are none, the first loopback interface. On some systems, loopback interfaces cannot be
used for capturing (loopback interfaces are not available on Windows platforms).
This field performs the same function as the -i <interface> command line option.
IP address
The IP address(es) of the selected interface. If no address could be
resolved from the system, "unknown" will be shown.
Link-layer header type
Unless you are in the rare situation that you need this, just keep
the default. For a detailed description, see Section 4.8,
“Link-layer header type”
Buffer size: n megabyte(s)
Enter the buffer size to be used while capturing. This is the size of
the kernel buffer which will keep the captured packets, until they
are written to disk. If you encounter packet drops, try increasing
this value.
Note
This option is only available on Windows platforms.
Capture packets in promiscuous
mode
This checkbox allows you to specify that Wireshark should put
the interface in promiscuous mode when capturing. If you do not
specify this, Wireshark will only capture the packets going to or
from your computer (not all packets on your LAN segment).
Note
If some other process has put the interface in
promiscuous mode you may be capturing in promiscuous mode even if you turn off this option
Note
Even in promiscuous mode you still won't necessarily see all packets on your LAN segment, see http://
www.wireshark.org/faq.html#promiscsniff for some
more explanations.
Limit each packet to n bytes
This field allows you to specify the maximum amount of data that
will be captured for each packet, and is sometimes referred to as
the snaplen. If disabled, the default is 65535, which will be sufficient for most protocols. Some rules of thumb:
73
Capturing Live Network Data
Capture Filter
•
If you are unsure, just keep the default value.
•
If you don't need all of the data in a packet - for example, if
you only need the link-layer, IP, and TCP headers - you might
want to choose a small snapshot length, as less CPU time is
required for copying packets, less buffer space is required for
packets, and thus perhaps fewer packets will be dropped if
traffic is very heavy.
•
If you don't capture all of the data in a packet, you might find
that the packet data you want is in the part that's dropped, or
that reassembly isn't possible as the data required for reassembly is missing.
This field allows you to specify a capture filter. Capture filters are
discussed in more details in Section 4.9, “Filtering while capturing”. It defaults to empty, or no filter.
You can also click on the button labeled "Capture Filter", and
Wireshark will bring up the Capture Filters dialog box and allow
you to create and/or select a filter. Please see Section 6.6,
“Defining and saving filters”
4.5.2. Capture File(s) frame
An explanation about capture file usage can be found in Section 4.7, “Capture files and file modes”.
File
This field allows you to specify the file name that will be used for
the capture file. This field is left blank by default. If the field is
left blank, the capture data will be stored in a temporary file, see
Section 4.7, “Capture files and file modes” for details.
You can also click on the button to the right of this field to
browse through the filesystem.
Use multiple files
Instead of using a single file, Wireshark will automatically switch
to a new one, if a specific trigger condition is reached.
Next file every n megabyte(s)
Multiple files only: Switch to the next file after the given number
of byte(s)/kilobyte(s)/megabyte(s)/gigabyte(s) have been captured.
Next file every n minute(s)
Multiple files only: Switch to the next file after the given number
of second(s)/minutes(s)/hours(s)/days(s) have elapsed.
Ring buffer with n files
Multiple files only: Form a ring buffer of the capture files, with
the given number of files.
Stop capture after n file(s)
Multiple files only: Stop capturing after switching to the next file
the given number of times.
4.5.3. Stop Capture... frame
74
Capturing Live Network Data
... after n packet(s)
Stop capturing after the given number of packets have been captured.
... after n megabytes(s)
Stop
capturing
after
the
given
number
of
byte(s)/kilobyte(s)/megabyte(s)/gigabyte(s) have been captured.
This option is greyed out, if "Use multiple files" is selected.
... after n minute(s)
Stop
capturing
after
the
given
number
second(s)/minutes(s)/hours(s)/days(s) have elapsed.
of
4.5.4. Display Options frame
Update list of packets in real time
This option allows you to specify that Wireshark should update
the packet list pane in real time. If you do not specify this, Wireshark does not display any packets until you stop the capture.
When you check this, Wireshark captures in a separate process
and feeds the captures to the display process.
Automatic scrolling in live capture
This option allows you to specify that Wireshark should scroll the
packet list pane as new packets come in, so you are always looking at the last packet. If you do not specify this, Wireshark simply
adds new packets onto the end of the list, but does not scroll the
packet list pane. This option is greyed out if "Update list of packets in real time" is disabled.
Hide capture info dialog
If this option is checked, the capture info dialog described in Section 4.10, “While a Capture is running ...” will be hidden.
4.5.5. Name Resolution frame
Enable MAC name resolution
This option allows you to control whether or not Wireshark translates MAC addresses into names, see Section 7.7, “Name Resolution”.
Enable network name resolution
This option allows you to control whether or not Wireshark translates network addresses into names, see Section 7.7, “Name Resolution”.
Enable transport name resolution
This option allows you to control whether or not Wireshark translates transport addresses into protocols, see Section 7.7, “Name
Resolution”.
4.5.6. Buttons
Once you have set the values you desire and have selected the options you need, simply click on Start to
commence the capture, or Cancel to cancel the capture.
If you start a capture, Wireshark allows you to stop capturing when you have enough packets captured,
for details see Section 4.10, “While a Capture is running ...”.
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Capturing Live Network Data
4.6. The "Interface Details" dialog box
When you select Details from the Capture Interface menu, Wireshark pops up the "Interface Details"
dialog box as shown in Figure 4.4, “The "Interface Details" dialog box”. This dialog shows various
characteristics and statistics for the selected interface.
Microsoft Windows only
This dialog is only available on Microsoft Windows
Figure 4.4. The "Interface Details" dialog box
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Capturing Live Network Data
4.7. Capture files and file modes
While capturing, the underlying libpcap capturing engine will grab the packets from the network card
and keep the packet data in a (relatively) small kernel buffer. This data is read by Wireshark and saved
into the capture file(s) the user specified.
Different modes of operation are available when saving this packet data to the capture file(s).
Tip!
Working with large files (several 100 MB's) can be quite slow. If you plan to do a long
term capture or capturing from a high traffic network, think about using one of the "Multiple files" options. This will spread the captured packets over several smaller files which
can be much more pleasant to work with.
Note!
Using Multiple files may cut context related information. Wireshark keeps context information of the loaded packet data, so it can report context related problems (like a stream error) and keeps information about context related protocols (e.g. where data is exchanged at
the establishing phase and only referred to in later packets). As it keeps this information
only for the loaded file, using one of the multiple file modes may cut these contexts. If the
establishing phase is saved in one file and the things you would like to see is in another,
you might not see some of the valuable context related information.
Tip!
Information about the folders used for the capture file(s), can be found in Appendix A,
Files and Folders.
Table 4.1. Capture file mode selected by capture options
"File" option
"Use
multiple "Ring
buffer Mode
files" option
with n files" option
-
-
-
Single temporary etherXXXXXX (where
file
XXXXXX is a unique
number)
foo.cap
-
-
Single named file foo.cap
foo.cap
x
-
Multiple
files, foo_00001_20040205110
continuous
102.cap,
foo_00002_20040205110
102.cap, ...
foo.cap
x
x
Multiple
files, foo_00001_20040205110
ring buffer
102.cap,
foo_00002_20040205110
102.cap, ...
Single temporary file
Resulting
used
filename(s)
A temporary file will be created and used (this is the default).
77
Capturing Live Network Data
After the capturing is stopped, this file can be saved later under a
user specified name.
Single named file
A single capture file will be used. If you want to place the new
capture file to a specific folder, choose this mode.
Multiple files, continuous
Like the "Single named file" mode, but a new file is created and
used, after reaching one of the multiple file switch conditions (one
of the "Next file every ..." values).
Multiple files, ring buffer
Much like "Multiple files continuous", reaching one of the multiple files switch conditions (one of the "Next file every ..." values) will switch to the next file. This will be a newly created file
if value of "Ring buffer with n files" is not reached, otherwise it
will replace the oldest of the formerly used files (thus forming a
"ring").
This mode will limit the maximum disk usage, even for an unlimited amount of capture input data, keeping the latest captured
data.
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Capturing Live Network Data
4.8. Link-layer header type
In the usual case, you won't have to choose this link-layer header type. The following paragraphs describe the exceptional cases, where selecting this type is possible, so you will have a guide of what to
do:
If you are capturing on an 802.11 device on some versions of BSD, this might offer a choice of "Ethernet" or "802.11". "Ethernet" will cause the captured packets to have fake Ethernet headers; "802.11" will
cause them to have IEEE 802.11 headers. Unless the capture needs to be read by an application that
doesn't support 802.11 headers, you should select "802.11".
If you are capturing on an Endace DAG card connected to a synchronous serial line, this might offer a
choice of "PPP over serial" or "Cisco HDLC"; if the protocol on the serial line is PPP, select "PPP over
serial", and if the protocol on the serial line is Cisco HDLC, select "Cisco HDLC".
If you are capturing on an Endace DAG card connected to an ATM network, this might offer a choice of
"RFC 1483 IP-over-ATM" or "Sun raw ATM". If the only traffic being captured is RFC 1483 LLCencapsulated IP, or if the capture needs to be read by an application that doesn't support SunATM headers, select "RFC 1483 IP-over-ATM", otherwise select "Sun raw ATM".
If you are capturing on an Ethernet device, this might offer a choice of "Ethernet" or "DOCSIS". If you
are capturing traffic from a Cisco Cable Modem Termination System that is putting DOCSIS traffic onto
the Ethernet to be captured, select "DOCSIS", otherwise select "Ethernet".
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4.9. Filtering while capturing
Wireshark uses the libpcap filter language for capture filters. This is explained in the tcpdump man page,
which can be hard to understand, so it's explained here to some extent.
Tip!
You will find a lot of Capture Filter examples at http://wiki.wireshark.org/CaptureFilters.
You enter the capture filter into the Filter field of the Wireshark Capture Options dialog box, as shown
in Figure 4.3, “The "Capture Options" dialog box”. The following is an outline of the syntax of the tcpdump capture filter language. See the expression option at the tcpdump manual page for details: http://
www.tcpdump.org/tcpdump_man.html.
A capture filter takes the form of a series of primitive expressions connected by conjunctions (and/or)
and optionally preceded by not:
[not] primitive [and|or [not] primitive ...]
An example is shown in Example 4.1, “ A capture filter for telnet that captures traffic to and from a particular host ”.
Example 4.1. A capture filter for telnet that captures traffic to and from a
particular host
tcp port 23 and host 10.0.0.5
This example captures telnet traffic to and from the host 10.0.0.5, and shows how to use two primitives
and the and conjunction. Another example is shown in Example 4.2, “ Capturing all telnet traffic not
from 10.0.0.5”, and shows how to capture all telnet traffic except that from 10.0.0.5.
Example 4.2. Capturing all telnet traffic not from 10.0.0.5
tcp port 23 and not src host 10.0.0.5
XXX - add examples to the following list.
A primitive is simply one of the following:
[src|dst] host <host>
This primitive allows you to filter on a host IP address or name.
You can optionally precede the primitive with the keyword
src|dst to specify that you are only interested in source or destination addresses. If these are not present, packets where the specified address appears as either the source or the destination address will be selected.
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Capturing Live Network Data
ether [src|dst] host <ehost>
This primitive allows you to filter on Ethernet host addresses.
You can optionally include the keyword src|dst between the
keywords ether and host to specify that you are only interested in
source or destination addresses. If these are not present, packets
where the specified address appears in either the source or destination address will be selected.
gateway host <host>
This primitive allows you to filter on packets that used host as a
gateway. That is, where the Ethernet source or destination was
host but neither the source nor destination IP address was host.
[src|dst] net <net> [{mask
<mask>}|{len <len>}]
This primitive allows you to filter on network numbers. You can
optionally precede this primitive with the keyword src|dst to specify that you are only interested in a source or destination network. If neither of these are present, packets will be selected that
have the specified network in either the source or destination address. In addition, you can specify either the netmask or the CIDR
prefix for the network if they are different from your own.
[tcp|udp] [src|dst] port <port>
This primitive allows you to filter on TCP and UDP port numbers. You can optionally precede this primitive with the keywords
src|dst and tcp|udp which allow you to specify that you are only
interested in source or destination ports and TCP or UDP packets
respectively. The keywords tcp|udp must appear before src|dst.
If these are not specified, packets will be selected for both the
TCP and UDP protocols and when the specified address appears
in either the source or destination port field.
less|greater <length>
This primitive allows you to filter on packets whose length was
less than or equal to the specified length, or greater than or equal
to the specified length, respectively.
ip|ether proto <protocol>
This primitive allows you to filter on the specified protocol at
either the Ethernet layer or the IP layer.
ether|ip broadcast|multicast
This primitive allows you to filter on either Ethernet or IP broadcasts or multicasts.
<expr> relop <expr>
This primitive allows you to create complex filter expressions that
select bytes or ranges of bytes in packets. Please see the tcpdump
man page at http:/ / www.tcpdump.org/ tcpdump_man.html for
more details.
4.9.1. Automatic Remote Traffic Filtering
If Wireshark is running remotely (using e.g. SSH, an exported X11 window, a terminal server, ...), the
remote content has to be transported over the network, adding a lot of (usually unimportant) packets to
the actually interesting traffic.
To avoid this, Wireshark tries to figure out if it's remotely connected (by looking at some specific environment variables) and automatically creates a capture filter that matches aspects of the connection.
The following environment variables are analyzed:
SSH_CONNECTION (ssh)
<remote IP> <remote port> <local IP> <local port>
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Capturing Live Network Data
SSH_CLIENT (ssh)
<remote IP> <remote port> <local port>
REMOTEHOST (tcsh, others?)
<remote name>
DISPLAY (x11)
[remote name]:<display num>
SESSIONNAME (terminal server)
<remote name>
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Capturing Live Network Data
4.10. While a Capture is running ...
While a capture is running, the following dialog box is shown:
Figure 4.5. The "Capture Info" dialog box
This dialog box will inform you about the number of captured packets and the time since the capture
was started. The selection of which protocols are counted cannot be changed.
Tip!
This Capture Info dialog box can be hidden, using the "Hide capture info dialog" option in
the Capture Options dialog box.
4.10.1. Stop the running capture
A running capture session will be stopped in one of the following ways:
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Capturing Live Network Data
1.
Using the "
Stop" button from the Capture Info dialog box .
Note!
The Capture Info dialog box might be hidden, if the option "Hide capture info dialog"
is used.
2.
Using the menu item "Capture/
Stop".
3.
Using the toolbar item "
4.
Pressing the accelerator keys: Ctrl+E.
5.
The capture will be automatically stopped, if one of the Stop Conditions is exceeded, e.g. the maximum amount of data was captured.
Stop".
4.10.2. Restart a running capture
A running capture session can be restarted with the same capture options as the last time, this will remove all packets previously captured. This can be useful, if some uninteresting packets are captured and
there's no need to keep them.
Restart is a convenience function and equivalent to a capture stop following by an immediate capture
start. A restart can be triggered in one of the following ways:
1.
Using the menu item "Capture/
2.
Using the toolbar item "
Restart".
Restart".
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85
Chapter 5. File Input / Output and
Printing
5.1. Introduction
This chapter will describe input and output of capture data.
•
Open/Import capture files in various capture file formats
•
Save/Export capture files in various capture file formats
•
Merge capture files together
•
Print packets
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File Input / Output and Printing
5.2. Open capture files
Wireshark can read in previously saved capture files. To read them, simply select the menu or toolbar
item: "File/
Open". Wireshark will then pop up the File Open dialog box, which is discussed in
more detail in Section 5.2.1, “The "Open Capture File" dialog box”.
It's convenient to use drag-and-drop!
... to open a file, by simply dragging the desired file from your file manager and dropping
it onto Wireshark's main window. However, drag-and-drop is not available/won't work in
all desktop environments.
If you haven't previously saved the current capture file, you will be asked to do so, to prevent data loss
(this behaviour can be disabled in the preferences).
In addition to its native file format (libpcap format, also used by tcpdump/WinDump and other libpcap/
WinPcap-based programs), Wireshark can read capture files from a large number of other packet capture
programs as well. See Section 5.2.2, “Input File Formats” for the list of capture formats Wireshark understands.
5.2.1. The "Open Capture File" dialog box
The "Open Capture File" dialog box allows you to search for a capture file containing previously captured packets for display in Wireshark. Table 5.1, “The system specific "Open Capture File" dialog box”
shows some examples of the Wireshark Open File Dialog box.
The dialog appearance depends on your system!
The appearance of this dialog depends on the system and/or GTK+ toolkit version used.
However, the functionality remains basically the same on any particular system.
Common dialog behaviour on all systems:
•
Select files and directories.
•
Click the Open/Ok button to accept your selected file and open it.
•
Click the Cancel button to go back to Wireshark and not load a capture file.
Wireshark extensions to the standard behaviour of these dialogs:
•
View file preview information (like the filesize, the number of packets, ...), if you've selected a capture file.
•
Specify a display filter with the "Filter:" button and filter field. This filter will be used when opening
the new file. The text field background becomes green for a valid filter string and red for an invalid
one. Clicking on the Filter button causes Wireshark to pop up the Filters dialog box (which is discussed further in Section 6.3, “Filtering packets while viewing”).
XXX - we need a better description of these read filters
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•
Specify which type of name resolution is to be performed for all packets by clicking on one of the
"... name resolution" check buttons. Details about name resolution can be found in Section 7.7,
“Name Resolution”.
Save a lot of time loading huge capture files!
You can change the display filter and name resolution settings later while viewing the
packets. However, loading huge capture files can take a significant amount of extra time if
these settings are changed later, so in such situations it can be a good idea to set at least the
filter in advance here.
Table 5.1. The system specific "Open Capture File" dialog box
Microsoft Windows
Figure 5.1. "Open" on native Windows This is the common Windows file open dialog plus some Wireshark extensions.
Specific for this dialog:
•
If available, the "Help" button will lead you to
this section of this "User's Guide".
•
XXX - the "Filter:" button currently doesn't
work on Windows!
•
XXX - missing feature: If Wireshark doesn't
recognize the selected file as a capture file, it
should grey out the "Open" button.
Unix/Linux: GTK version >= 2.4
Figure 5.2. "Open" - new GTK version This is the common Gimp/GNOME file open dialog - plus some Wireshark extensions.
Specific for this dialog:
88
•
The "+ Add" button allows you to add a directory, selected in the right-hand pane, to the favorites list on the left. Those changes are persistent.
•
The "- Remove" button allows you to remove a
selected directory from that list again (the
File Input / Output and Printing
items like: "Home", "Desktop", and "Filesystem" cannot be removed).
•
If Wireshark doesn't recognize the selected file
as a capture file, it will grey out the "Open"
button.
Unix/Linux: GTK version < 2.4
Figure 5.3. "Open" - old GTK version
This is the file open dialog of former Gimp/
GNOME versions - plus some Wireshark extensions.
Specific for this dialog:
•
If Wireshark doesn't recognize the selected file
as a capture file, it will grey out the "Ok" button.
5.2.2. Input File Formats
The following file formats from other capture tools can be opened by Wireshark:
•
libpcap, tcpdump and various other tools using tcpdump's capture format
•
Sun snoop and atmsnoop
•
Shomiti/Finisar Surveyor captures
•
Novell LANalyzer captures
•
Microsoft Network Monitor captures
•
AIX's iptrace captures
•
Cinco Networks NetXray captures
•
Network Associates Windows-based Sniffer and Sniffer Pro captures
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File Input / Output and Printing
•
Network General/Network Associates DOS-based Sniffer (compressed or uncompressed) captures
•
AG Group/WildPackets EtherPeek/TokenPeek/AiroPeek/EtherHelp/PacketGrabber captures
•
RADCOM's WAN/LAN Analyzer captures
•
Network Instruments Observer version 9 captures
•
Lucent/Ascend router debug output
•
HP-UX's nettl
•
Toshiba's ISDN routers dump output
•
ISDN4BSD i4btrace utility
•
traces from the EyeSDN USB S0
•
IPLog format from the Cisco Secure Intrusion Detection System
•
pppd logs (pppdump format)
•
the output from VMS's TCPIPtrace/TCPtrace/UCX$TRACE utilities
•
the text output from the DBS Etherwatch VMS utility
•
Visual Networks' Visual UpTime traffic capture
•
the output from CoSine L2 debug
•
the output from Accellent's 5Views LAN agents
•
Endace Measurement Systems' ERF format captures
•
Linux Bluez Bluetooth stack hcidump -w traces
•
Catapult DCT2000 .out files
•
Gammu generated text output from Nokia DCT3 phones in Netmonitor mode
•
IBM Series (OS/400) Comm traces (ASCII & UNICODE)
•
Juniper Netscreen snoop captures
•
Symbian OS btsnoop captures
•
Tamosoft CommView captures
•
Textronix K12xx 32bit .rf5 format captures
•
Textronix K12 text file format captures
•
Wireshark .pcapng captures (Experimental)
•
... new file formats are added from time to time
Opening a file may fail due to invalid packet types!
It may not be possible to read some formats dependent on the packet types captured. Ether90
File Input / Output and Printing
net captures are usually supported for most file formats but it may not be possible to read
other packet types (e.g. token ring packets) from all file formats.
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5.3. Saving captured packets
You can save captured packets simply by using the Save As... menu item from the File menu under
Wireshark. You can choose which packets to save and which file format to be used.
Saving may reduce the available information!
Saving the captured packets will slightly reduce the amount of information, e.g. the number of dropped packets will be lost; see Section A.1, “Capture Files” for details.
5.3.1. The "Save Capture File As" dialog box
The "Save Capture File As" dialog box allows you to save the current capture to a file. Table 5.2, “The
system specific "Save Capture File As" dialog box” shows some examples of this dialog box.
The dialog appearance depends on your system!
The appearance of this dialog depends on the system and GTK+ toolkit version used.
However, the functionality remains basically the same on any particular system.
Table 5.2. The system specific "Save Capture File As" dialog box
Microsoft Windows
Figure 5.4. "Save" on native Windows
This is the common Windows file save dialog plus some Wireshark extensions.
Specific for this dialog:
•
If available, the "Help" button will lead you to
this section of this "User's Guide".
•
If you don't provide a file extension to the filename - e.g. .pcap, Wireshark will append the
standard file extension for that file format.
Unix/Linux: GTK version >= 2.4
Figure 5.5. "Save" - new GTK version
This is the common Gimp/GNOME file save dialog - plus some Wireshark extensions.
Specific for this dialog:
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File Input / Output and Printing
•
Clicking on the + at "Browse for other folders"
will allow you to browse files and folders in
your file system.
Unix/Linux: GTK version < 2.4
Figure 5.6. "Save" - old GTK version
This is the file save dialog of former Gimp/
GNOME versions - plus some Wireshark extensions.
With this dialog box, you can perform the following actions:
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1.
Type in the name of the file you wish to save the captured packets in, as a standard file name in
your file system.
2.
Select the directory to save the file into.
3.
Select the range of the packets to be saved, see Section 5.8, “The Packet Range frame”
4.
Specify the format of the saved capture file by clicking on the File type drop down box. You can
choose from the types, described in Section 5.3.2, “Output File Formats”.
The selection of capture formats may be reduced!
Some capture formats may not be available, depending on the packet types captured.
File formats can be converted!
You can convert capture files from one format to another by reading in a capture file
and writing it out using a different format.
5.
Click on the Save/Ok button to accept your selected file and save to it. If Wireshark has a problem
saving the captured packets to the file you specified, it will display an error dialog box. After clicking OK on that error dialog box, you can try again.
6.
Click on the Cancel button to go back to Wireshark and not save the captured packets.
5.3.2. Output File Formats
Wireshark can save the packet data in its "native" file format (libpcap) and in the file formats of some
other protocol analyzers, so other tools can read the capture data.
File formats have different time stamp accuracies!
Saving from the currently used file format to a different format may reduce the time stamp
accuracy; see the Section 7.4, “Time Stamps” for details.
The following file formats can be saved by Wireshark (with the known file extensions):
•
libpcap, tcpdump and various other tools using tcpdump's capture format (*.pcap,*.cap,*.dmp)
•
Accellent 5Views (*.5vw)
•
HP-UX's nettl (*.TRC0,*.TRC1)
•
Microsoft Network Monitor - NetMon (*.cap)
•
Network Associates Sniffer - DOS (*.cap,*.enc,*.trc,*fdc,*.syc)
•
Network Associates Sniffer - Windows (*.cap)
•
Network Instruments Observer version 9 (*.bfr)
•
Novell LANalyzer (*.tr1)
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File Input / Output and Printing
•
Sun snoop (*.snoop,*.cap)
•
Visual Networks Visual UpTime traffic (*.*)
•
... new file formats are added from time to time
If the above tools will be more helpful than Wireshark is a different question ;-)
Third party protocol analyzers may require specific file
extensions!
Other protocol analyzers than Wireshark may require that the file has a certain file extension in order to read the files you generate with Wireshark, e.g.:
".cap" for Network Associates Sniffer - Windows
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5.4. Merging capture files
Sometimes you need to merge several capture files into one. For example this can be useful, if you have
captured simultaneously from multiple interfaces at once (e.g. using multiple instances of Wireshark).
Merging capture files can be done in three ways:
•
Use the menu item "Merge" from the "File" menu, to open the merge dialog, see Section 5.4.1,
“The "Merge with Capture File" dialog box”. This menu item will be disabled, until you have loaded
a capture file.
•
Use drag-and-drop to drop multiple files on the main window. Wireshark will try to merge the
packets in chronological order from the dropped files into a newly created temporary file. If you
drop only a single file, it will simply replace a (maybe) existing one.
•
Use the mergecap tool, which is a command line tool to merge capture files. This tool provides the
most options to merge capture files, see Section D.7, “mergecap: Merging multiple capture files into
one ”.
5.4.1. The "Merge with Capture File" dialog box
This dialog box let you select a file to be merged into the currently loaded file.
You will be prompted for an unsaved file first!
If your current data wasn't saved before, you will be asked to save it first, before this dialog
box is shown.
Most controls of this dialog will work the same way as described in the "Open Capture File" dialog box,
see Section 5.2.1, “The "Open Capture File" dialog box”.
Specific controls of this merge dialog are:
Prepend packets to existing file
Prepend the packets from the selected file before the currently
loaded packets.
Merge packets chronologically
Merge both the packets from the selected and currently loaded file
in chronological order.
Append packets to existing file
Append the packets from the selected file after the currently
loaded packets.
Table 5.3. The system specific "Merge Capture File As" dialog box
Microsoft Windows
Figure 5.7. "Merge" on native Windows This is the common Windows file open dialog plus some Wireshark extensions.
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File Input / Output and Printing
Unix/Linux: GTK version >= 2.4
Figure 5.8. "Merge" - new GTK version This is the common Gimp/GNOME file open dialog - plus some Wireshark extensions.
Unix/Linux: GTK version < 2.4
Figure 5.9. "Merge" - old GTK version This is the file open dialog of former Gimp/
GNOME versions - plus some Wireshark extensions.
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5.5. File Sets
When using the "Multiple Files" option while doing a capture (see: Section 4.7, “Capture files and file
modes”), the capture data is spread over several capture files, called a file set.
As it can become tedious to work with a file set by hand, Wireshark provides some features to handle
these file sets in a convenient way.
How does Wireshark detect the files of a file set?
A filename in a file set uses the format Prefix_Number_DateTimeSuffix which might look like
this: "test_00001_20060420183910.pcap". All files of a file set share the same prefix (e.g. "test")
and suffix (e.g. ".pcap") and a varying middle part.
To find the files of a file set, Wireshark scans the directory where the currently loaded file resides
and checks for files matching the filename pattern (prefix and suffix) of the currently loaded file.
This simple mechanism usually works well, but has its drawbacks. If several file sets were captured with the same prefix and suffix, Wireshark will detect them as a single file set. If files were
renamed or spread over several directories the mechanism will fail to find all files of a set.
The following features in the "File Set" submenu of the "File" menu are available to work with file sets
in a convenient way:
•
The List Files dialog box will list the files Wireshark has recognized as being part of the current file
set.
•
Next File closes the current and opens the next file in the file set.
•
Previous File closes the current and opens the previous file in the file set.
5.5.1. The "List Files" dialog box
Figure 5.10. The "List Files" dialog box
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File Input / Output and Printing
Each line contains information about a file of the file set:
•
Filename the name of the file. If you click on the filename (or the radio button left to it), the current
file will be closed and the corresponding capture file will be opened.
•
Created the creation time of the file
•
Last Modified the last time the file was modified
•
Size the size of the file
The last line will contain info about the currently used directory where all of the files in the file set can
be found.
The content of this dialog box is updated each time a capture file is opened/closed.
The Close button will, well, close the dialog box.
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5.6. Exporting data
Wireshark provides several ways and formats to export packet data. This section describes general ways
to export data from Wireshark.
Note!
There are more specialized functions to export specific data, which will be described at the
appropriate places.
XXX - add detailed descriptions of the output formats and some sample output, too.
5.6.1. The "Export as Plain Text File" dialog box
Export packet data into a plain ASCII text file, much like the format used to print packets.
Figure 5.11. The "Export as Plain Text File" dialog box
•
Export to file: frame chooses the file to export the packet data to.
•
The Packet Range frame is described in Section 5.8, “The Packet Range frame”.
•
The Packet Details frame is described in Section 5.9, “The Packet Format frame”.
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File Input / Output and Printing
5.6.2. The "Export as PostScript File" dialog box
Export packet data into PostScript, much like the format used to print packets.
Tip!
You can easily convert PostScript files to PDF files using ghostscript. For example: export
to a file named foo.ps and then call: ps2pdf foo.ps
Figure 5.12. The "Export as PostScript File" dialog box
•
Export to file: frame chooses the file to export the packet data to.
•
The Packet Range frame is described in Section 5.8, “The Packet Range frame”.
•
The Packet Details frame is described in Section 5.9, “The Packet Format frame”.
5.6.3. The "Export as CSV (Comma Separated Values)
File" dialog box
XXX - add screenshot
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File Input / Output and Printing
Export packet summary into CSV, used e.g. by spreadsheet programs to im-/export data.
•
Export to file: frame chooses the file to export the packet data to.
•
The Packet Range frame is described in Section 5.8, “The Packet Range frame”.
5.6.4. The "Export as C Arrays (packet bytes) file" dialog
box
XXX - add screenshot
Export packet bytes into C arrays so you can import the stream data into your own C program.
•
Export to file: frame chooses the file to export the packet data to.
•
The Packet Range frame is described in Section 5.8, “The Packet Range frame”.
5.6.5. The "Export as PSML File" dialog box
Export packet data into PSML. This is an XML based format including only the packet summary. The
PSML file specification is available at: http://www.nbee.org/doku.php?id=netpdl:psml_specification.
Figure 5.13. The "Export as PSML File" dialog box
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File Input / Output and Printing
•
Export to file: frame chooses the file to export the packet data to.
•
The Packet Range frame is described in Section 5.8, “The Packet Range frame”.
There's no such thing as a packet details frame for PSML export, as the packet format is defined by the
PSML specification.
5.6.6. The "Export as PDML File" dialog box
Export packet data into PDML. This is an XML based format including the packet details. The PDML
file specification is available at: http://www.nbee.org/doku.php?id=netpdl:pdml_specification.
The PDML specification is not officially released and Wireshark's implementation of it is
still in an early beta state, so please expect changes in future Wireshark versions.
Figure 5.14. The "Export as PDML File" dialog box
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•
Export to file: frame chooses the file to export the packet data to.
•
The Packet Range frame is described in Section 5.8, “The Packet Range frame”.
There's no such thing as a packet details frame for PDML export, as the packet format is defined by the
PDML specification.
5.6.7. The "Export selected packet bytes" dialog box
Export the bytes selected in the "Packet Bytes" pane into a raw binary file.
Figure 5.15. The "Export Selected Packet Bytes" dialog box
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•
Name: the filename to export the packet data to.
•
The Save in folder: field lets you select the folder to save to (from some predefined folders).
•
Browse for other folders provides a flexible way to choose a folder.
5.6.8. The "Export Objects" dialog box
This feature scans through HTTP streams in the currently open capture file or running capture and takes
reassembled objects such as HTML documents, image files, executables and anything else that can be
transferred over HTTP and lets you save them to disk. If you have a capture running, this list is automatically updated every few seconds with any new objects seen. The saved objects can then be opened with
the proper viewer or executed in the case of executables (if it is for the same platform you are running
Wireshark on) without any further work on your part. This feature is not available when using GTK2
versions below 2.4.
Figure 5.16. The "Export Objects" dialog box
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Columns:
•
Packet num: The packet number in which this object was found. In some cases, there can be multiple objects in the same packet.
•
Hostname: The hostname of the server that sent the object as a response to an HTTP request.
•
Content Type: The HTTP content type of this object.
•
Bytes: The size of this object in bytes.
•
Filename: The final part of the URI (after the last slash). This is typically a filename, but may be a
long complex looking string, which typically indicates that the file was received in response to a HTTP POST request.
Buttons:
•
Help: Opens this section in the user's guide.
•
Close: Closes this dialog.
•
Save As: Saves the currently selected object as a filename you specify. The default filename to save
as is taken from the filename column of the objects list.
•
Save All: Saves all objects in the list using the filename from the filename column. You will be
asked what directory / folder to save them in. If the filename is invalid for the operating system / file
system you are running Wireshark on, then an error will appear and that object will not be saved (but
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all of the others will be).
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5.7. Printing packets
To print packets, select the "Print..." menu item from the File menu. When you do this, Wireshark pops
up the Print dialog box as shown in Figure 5.17, “The "Print" dialog box”.
5.7.1. The "Print" dialog box
Figure 5.17. The "Print" dialog box
The following fields are available in the Print dialog box:
Printer
This field contains a pair of mutually exclusive radio buttons:
•
Plain Text specifies that the packet print should be in plain text.
•
PostScript specifies that the packet print process should use PostScript to generate a better print output on PostScript aware printers.
•
Output to file: specifies that printing be done to a file, using the filename
entered in the field or selected with the browse button.
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File Input / Output and Printing
This field is where you enter the file to print to if you have selected Print to a
file, or you can click the button to browse the filesystem. It is greyed out if
Print to a file is not selected.
•
Print command specifies that a command be used for printing.
Note!
These Print command fields are not available on windows platforms.
This field specifies the command to use for printing. It is typically lpr. You
would change it to specify a particular queue if you need to print to a queue
other than the default. An example might be:
lpr -Pmypostscript
This field is greyed out if Output to file: is checked above.
Packet Range
Select the packets to be printed, see Section 5.8, “The Packet Range frame”
Packet Format
Select the output format of the packets to be printed. You can choose, how each
packet is printed, see Figure 5.19, “The "Packet Format" frame”
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File Input / Output and Printing
5.8. The Packet Range frame
The packet range frame is a part of various output related dialog boxes. It provides options to select
which packets should be processed by the output function.
Figure 5.18. The "Packet Range" frame
If the Captured button is set (default), all packets from the selected rule will be processed. If the Displayed button is set, only the currently displayed packets are taken into account to the selected rule.
•
All packets will process all packets.
•
Selected packet only process only the selected packet.
•
Marked packets only process only the marked packets.
•
From first to last marked packet process the packets from the first to the last marked one.
•
Specify a packet range process a user specified range of packets, e.g. specifying 5,10-15,20- will
process the packet number five, the packets from packet number ten to fifteen (inclusive) and every
packet from number twenty to the end of the capture.
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File Input / Output and Printing
5.9. The Packet Format frame
The packet format frame is a part of various output related dialog boxes. It provides options to select
which parts of a packet should be used for the output function.
Figure 5.19. The "Packet Format" frame
•
Packet summary line enable the output of the summary line, just as in the "Packet List" pane.
•
Packet details enable the output of the packet details tree.
•
All collapsed the info from the "Packet Details" pane in "all collapsed" state.
•
As displayed the info from the "Packet Details" pane in the current state.
•
All expanded the info from the "Packet Details" pane in "all expanded" state.
•
Packet bytes enable the output of the packet bytes, just as in the "Packet Bytes" pane.
•
Each packet on a new page put each packet on a separate page (e.g. when saving/printing to a text
file, this will put a form feed character between the packets).
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File Input / Output and Printing
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Chapter 6. Working with captured
packets
6.1. Viewing packets you have captured
Once you have captured some packets, or you have opened a previously saved capture file, you can view
the packets that are displayed in the packet list pane by simply clicking on a packet in the packet list
pane, which will bring up the selected packet in the tree view and byte view panes.
You can then expand any part of the tree view by clicking on the plus sign (the symbol itself may vary)
to the left of that part of the payload, and you can select individual fields by clicking on them in the tree
view pane. An example with a TCP packet selected is shown in Figure 6.1, “Wireshark with a TCP
packet selected for viewing”. It also has the Acknowledgment number in the TCP header selected,
which shows up in the byte view as the selected bytes.
Figure 6.1. Wireshark with a TCP packet selected for viewing
You can also select and view packets the same way, while Wireshark is capturing, if you selected "Update list of packets in real time" in the Wireshark Capture Preferences dialog box.
In addition, you can view individual packets in a separate window as shown in Figure 6.2, “Viewing a
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Working with captured packets
packet in a separate window”. Do this by selecting the packet in which you are interested in the packet
list pane, and then select "Show Packet in New Windows" from the Display menu. This allows you to
easily compare two or even more packets.
Figure 6.2. Viewing a packet in a separate window
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Working with captured packets
6.2. Pop-up menus
You can bring up a pop-up menu over either the "Packet List" or "Packet Details" pane by clicking your
right mouse button at the corresponding pane.
6.2.1. Pop-up menu of the "Packet List" pane
Figure 6.3. Pop-up menu of the "Packet List" pane
The following table gives an overview of which functions are available in this pane, where to find the
corresponding function in the main menu, and a short description of each item.
Table 6.1. The menu items of the "Packet List" pop-up menu
Item
Mark
(toggle)
Identical to main Description
menu's item:
Packet Edit
Mark/unmark a packet.
Set Time Refer- Edit
ence (toggle)
Set/reset a time reference.
----Apply as Filter
Analyze
Prepare and apply a display filter based on the currently selected item.
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Item
Identical to main Description
menu's item:
Prepare a Filter
Analyze
Prepare a display filter based on the currently selected item.
Conversation Fil- ter
Colorize Conver- sation
SCTP
This menu item applies a display filter with the address information from the selected packet. E.g. the IP menu entry will set a
filter to show the traffic between the two IP addresses of the
current packet. XXX - add a new section describing this better.
This menu item uses a display filter with the address information from the selected packet to build a new colorizing rule.
XXX - add an explanation of this.
Follow
Stream
TCP Analyze
Follow
Stream
SSL Analyze
Allows you to view all the data on a TCP stream between a pair
of nodes.
Same as "Follow TCP Stream" but for SSL. XXX - add a new
section describing this better.
----Copy/ Summary (Text)
Copy/ Summary (CSV)
Copy the summary fields as displayed to the clipboard, as tabseparated text.
Copy the summary fields as displayed to the clipboard, as
comma-separated text.
Copy/ As Filter
Prepare a display filter based on the currently selected item and
copy that filter to the clipboard.
Copy/
Bytes (Offset Hex Text)
Copy/
Bytes (Offset Hex)
Copy/
Bytes (Printable Text
Only)
Copy/ Bytes (Hex Stream)
Copy/
Bytes (Binary Stream)
Copy the packet bytes to the clipboard in hexdump-like format.
Copy the packet bytes to the clipboard in hexdump-like format,
but without the text portion.
Copy the packet bytes to the clipboard as ASCII text, excluding
non-printable characters.
Copy the packet bytes to the clipboard as an unpunctuated list
of hex digits.
Copy the packet bytes to the clipboard as raw binary. The data
is stored in the clipboard as MIME-type "application/octet-stream".
This option is not available in versions of Wireshark built using
GTK+ 1.x.
Export Selected File
Packet Bytes...
This menu item is the same as the File menu item of the same
name. It allows you to export raw packet bytes to a binary file.
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Item
Identical to main Description
menu's item:
Decode As...
Analyze
Change or apply a new relation between two dissectors.
Print...
File
Print packets.
Show Packet in View
New Window
Display the selected packet in a new window.
6.2.2. Pop-up menu of the "Packet Details" pane
Figure 6.4. Pop-up menu of the "Packet Details" pane
The following table gives an overview of which functions are available in this pane, where to find the
corresponding function in the main menu, and a short description of each item.
Table 6.2. The menu items of the "Packet Details" pop-up menu
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Item
Identical to main Description
menu's item:
Expand Subtrees View
Expand the currently selected subtree.
Expand All
View
Expand all subtrees in all packets in the capture.
Collapse All
View
Wireshark keeps a list of all the protocol subtrees that are expanded, and uses it to ensure that the correct subtrees are expanded when you display a packet. This menu item collapses
the tree view of all packets in the capture list.
----Copy/
tion
Descrip- Edit
Copy the displayed text of the selected field to the system clipboard.
Copy/ Fieldname Edit
Copy the name of the selected field to the system clipboard.
Copy/ Value
Edit
Copy the value of the selected field to the system clipboard.
Copy/ As Filter
Edit
Prepare a display filter based on the currently selected item and
copy it to the clipboard.
Copy/
Bytes (Offset Hex Text)
Copy/
Bytes (Offset Hex)
Copy/
Bytes (Printable Text
Only)
Copy/ Bytes (Hex Stream)
Copy/
Bytes (Binary Stream)
Copy the packet bytes to the clipboard in hexdump-like format;
similar to the Packet List Pane command, but copies only the
bytes relevant to the selected part of the tree (the bytes selected
in the Packet Bytes Pane).
Copy the packet bytes to the clipboard in hexdump-like format,
but without the text portion; similar to the Packet List Pane
command, but copies only the bytes relevant to the selected
part of the tree (the bytes selected in the Packet Bytes Pane).
Copy the packet bytes to the clipboard as ASCII text, excluding
non-printable characters; similar to the Packet List Pane command, but copies only the bytes relevant to the selected part of
the tree (the bytes selected in the Packet Bytes Pane).
Copy the packet bytes to the clipboard as an unpunctuated list
of hex digits; similar to the Packet List Pane command, but
copies only the bytes relevant to the selected part of the tree
(the bytes selected in the Packet Bytes Pane).
Copy the packet bytes to the clipboard as raw binary; similar to
the Packet List Pane command, but copies only the bytes relevant to the selected part of the tree (the bytes selected in the
Packet Bytes Pane). The data is stored in the clipboard as
MIME-type "application/octet-stream".
This option is not available in versions of Wireshark built using
GTK+ 1.x.
Export Selected File
Packet Bytes...
This menu item is the same as the File menu item of the same
name. It allows you to export raw packet bytes to a binary file.
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Item
Identical to main Description
menu's item:
----Apply as Filter
Analyze
Prepare and apply a display filter based on the currently selected item.
Prepare a Filter
Analyze
Prepare a display filter based on the currently selected item.
Colorize with Fil- ter
Follow
Stream
TCP Analyze
Follow
Stream
SSL Analyze
Prepare a display filter based on the currently selected item and
use it to prepare a new colorize rule.
Allows you to view all the data on a TCP stream between a pair
of nodes.
Same as "Follow TCP Stream" but for SSL. XXX - add a new
section describing this better.
----Wiki
Page
Protocol Show the wiki page corresponding to the currently selected
protocol in your web browser.
Filter Field Ref- erence
Protocol Prefer- ences...
Show the filter field reference web page corresponding to the
currently selected protocol in your web browser.
The menu item takes you to the properties dialog and selects
the page corresponding to the protocol if there are properties
associated with the highlighted field. More information on preferences can be found in Figure 9.8, “The preferences dialog
box”.
----Decode As...
Analyze
Resolve Name
View
Change or apply a new relation between two dissectors.
Causes a name resolution to be performed for the selected
packet, but NOT every packet in the capture.
Go to Corres- Go
ponding Packet
If the selected field has a corresponding packet, go to it. Corresponding packets will usually be a request/response packet
pair or such.
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6.3. Filtering packets while viewing
Wireshark has two filtering languages: One used when capturing packets, and one used when displaying
packets. In this section we explore that second type of filter: Display filters. The first one has already
been dealt with in Section 4.9, “Filtering while capturing”.
Display filters allow you to concentrate on the packets you are interested in while hiding the currently
uninteresting ones. They allow you to select packets by:
•
Protocol
•
The presence of a field
•
The values of fields
•
A comparison between fields
•
... and a lot more!
To select packets based on protocol type, simply type the protocol in which you are interested in the Filter: field in the filter toolbar of the Wireshark window and press enter to initiate the filter. Figure 6.5,
“Filtering on the TCP protocol” shows an example of what happens when you type tcp in the filter field.
Note!
All protocol and field names are entered in lowercase. Also, don't forget to press enter after
entering the filter expression.
Figure 6.5. Filtering on the TCP protocol
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As you might have noticed, only packets of the TCP protocol are displayed now (e.g. packets 1-10 are
hidden). The packet numbering will remain as before, so the first packet shown is now packet number
11.
Note!
When using a display filter, all packets remain in the capture file. The display filter only
changes the display of the capture file but not its content!
You can filter on any protocol that Wireshark understands. You can also filter on any field that a dissector adds to the tree view, but only if the dissector has added an abbreviation for the field. A list of such
fields is available in Wireshark in the Add Expression... dialog box. You can find more information on
the Add Expression... dialog box in Section 6.5, “The "Filter Expression" dialog box”.
For example, to narrow the packet list pane down to only those packets to or from the IP address
192.168.0.1, use ip.addr==192.168.0.1.
Note!
To remove the filter, click on the Clear button to the right of the filter field.
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6.4. Building display filter expressions
Wireshark provides a simple but powerful display filter language that allows you to build quite complex
filter expressions. You can compare values in packets as well as combine expressions into more specific
expressions. The following sections provide more information on doing this.
Tip!
You will find a lot of Display Filter examples at the Wireshark Wiki Display Filter page
at http://wiki.wireshark.org/DisplayFilters.
6.4.1. Display filter fields
Every field in the packet details pane can be used as a filter string, this will result in showing only the
packets where this field exists. For example: the filter string: tcp will show all packets containing the tcp
protocol.
There is a complete list of all filter fields available through the menu item "Help/Supported Protocols" in
the page "Display Filter Fields" of the Supported Protocols dialog.
XXX - add some more info here and a link to the statusbar info.
6.4.2. Comparing values
You can build display filters that compare values using a number of different comparison operators.
They are shown in Table 6.3, “Display Filter comparison operators”.
Tip!
You can use English and C-like terms in the same way, they can even be mixed in a filter
string!
Table 6.3. Display Filter comparison operators
English
eq
C-like
Description and example
==
Equal
ip.src==10.0.0.5
ne
!=
Not equal
ip.src!=10.0.0.5
gt
>
Greater than
frame.len > 10
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English
lt
C-like
Description and example
<
Less than
frame.len < 128
ge
>=
Greater than or equal to
frame.len ge 0x100
le
<=
Less than or equal to
frame.len <= 0x20
In addition, all protocol fields are typed. Table 6.4, “Display Filter Field Types” provides a list of the
types and example of how to express them.
Table 6.4. Display Filter Field Types
Type
Example
Unsigned integer (8-bit, 16-bit, 24-bit, 32-bit)
You can express integers in decimal, octal, or
hexadecimal. The following display filters are
equivalent:
ip.len le 1500
ip.len le 02734
ip.len le 0x436
Signed integer (8-bit, 16-bit, 24-bit, 32-bit)
Boolean
A boolean field is present in the protocol decode
only if its value is true. For example, tcp.flags.syn
is present, and thus true, only if the SYN flag is
present in a TCP segment header.
Thus the filter expression tcp.flags.syn will select
only those packets for which this flag exists, that
is, TCP segments where the segment header contains the SYN flag. Similarly, to find source-routed
token ring packets, use a filter expression of tr.sr.
Ethernet address (6 bytes)
Separators can be a colon (:), dot (.) or dash (-) and
can have one or two bytes between separators:
eth.dst == ff:ff:ff:ff:ff:ff
eth.dst == ff-ff-ff-ff-ff-ff
eth.dst == ffff.ffff.ffff
IPv4 address
ip.addr == 192.168.0.1
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Type
Example
Classless InterDomain Routing (CIDR) notation
can be used to test if an IPv4 address is in a certain
subnet. For example, this display filter will find all
packets in the 129.111 Class-B network:
ip.addr == 129.111.0.0/16
IPv6 address
ipv6.addr == ::1
IPX address
ipx.addr == 00000000.ffffffffffff
String (text)
http.request.uri == "http://www.wireshark.org/"
6.4.3. Combining expressions
You can combine filter expressions in Wireshark using the logical operators shown in Table 6.5,
“Display Filter Logical Operations”
Table 6.5. Display Filter Logical Operations
English
C-like
and
&&
Description and example
Logical AND
ip.src==10.0.0.5 and tcp.flags.fin
or
||
Logical OR
ip.scr==10.0.0.5 or ip.src==192.1.1.1
xor
^^
Logical XOR
tr.dst[0:3] == 0.6.29 xor tr.src[0:3] == 0.6.29
not
!
Logical NOT
not llc
[...]
Substring Operator
Wireshark allows you to select subsequences of a sequence in rather elaborate
ways. After a label you can place a pair of brackets [] containing a comma
separated list of range specifiers.
eth.src[0:3] == 00:00:83
The example above uses the n:m format to specify a single range. In this case
n is the beginning offset and m is the length of the range being specified.
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English
C-like
Description and example
eth.src[1-2] == 00:83
The example above uses the n-m format to specify a single range. In this case
n is the beginning offset and m is the ending offset.
eth.src[:4] == 00:00:83:00
The example above uses the :m format, which takes everything from the beginning of a sequence to offset m. It is equivalent to 0:m
eth.src[4:] == 20:20
The example above uses the n: format, which takes everything from offset n to
the end of the sequence.
eth.src[2] == 83
The example above uses the n format to specify a single range. In this case the
element in the sequence at offset n is selected. This is equivalent to n:1.
eth.src[0:3,1-2,:4,4:,2] ==
00:00:83:00:83:00:00:83:00:20:20:83
Wireshark allows you to string together single ranges in a comma separated
list to form compound ranges as shown above.
6.4.4. A common mistake
Warning!
Using the != operator on combined expressions like: eth.addr, ip.addr, tcp.port, udp.port
and alike will probably not work as expected!
Often people use a filter string to display something like ip.addr == 1.2.3.4 which will display all packets containing the IP address 1.2.3.4.
Then they use ip.addr != 1.2.3.4 to see all packets not containing the IP address 1.2.3.4 in it. Unfortunately, this does not do the expected.
Instead, that expression will even be true for packets where either source or destination IP address
equals 1.2.3.4. The reason for this, is that the expression ip.addr != 1.2.3.4 must be read as "the packet
contains a field named ip.addr with a value different from 1.2.3.4". As an IP datagram contains both a
source and a destination address, the expression will evaluate to true whenever at least one of the two
addresses differs from 1.2.3.4.
If you want to filter out all packets containing IP datagrams to or from IP address 1.2.3.4, then the correct filter is !(ip.addr == 1.2.3.4) as it reads "show me all the packets for which it is not true that a field
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named ip.addr exists with a value of 1.2.3.4", or in other words, "filter out all packets for which there are
no occurrences of a field named ip.addr with the value 1.2.3.4".
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6.5. The "Filter Expression" dialog box
When you are accustomed to Wireshark's filtering system and know what labels you wish to use in your
filters it can be very quick to simply type a filter string. However if you are new to Wireshark or are
working with a slightly unfamiliar protocol it can be very confusing to try to figure out what to type. The
Filter Expression dialog box helps with this.
Tip!
The "Filter Expression" dialog box is an excellent way to learn how to write Wireshark
display filter strings.
Figure 6.6. The "Filter Expression" dialog box
When you first bring up the Filter Expression dialog box you are shown a tree list of field names, organized by protocol, and a box for selecting a relation.
Field Name
Select a protocol field from the protocol field tree. Every protocol with filterable fields
is listed at the top level. (You can search for a particular protocol entry by entering the
first few letters of the protocol name). By clicking on the "+" next to a protocol name
you can get a list of the field names available for filtering for that protocol.
Relation
Select a relation from the list of available relation. The is present is a unary relation
which is true if the selected field is present in a packet. All other listed relations are
binary relations which require additional data (e.g. a Value to match) to complete.
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When you select a field from the field name list and select a binary relation (such as the equality relation
==) you will be given the opportunity to enter a value, and possibly some range information.
Value
You may enter an appropriate value in the Value text box. The Value will
also indicate the type of value for the field name you have selected (like
character string).
Predefined values
Some of the protocol fields have predefined values available, much like
enum's in C. If the selected protocol field has such values defined, you can
choose one of them here.
Range
XXX - add an explanation here!
OK
When you have built a satisfactory expression click OK and a filter string
will be built for you.
Cancel
You can leave the Add Expression... dialog box without any effect by
clicking the Cancel button.
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6.6. Defining and saving filters
You can define filters with Wireshark and give them labels for later use. This can save time in remembering and retyping some of the more complex filters you use.
To define a new filter or edit an existing one, select the Capture Filters... menu item from the Capture
menu or the Display Filters... menu item from the Analyze menu. Wireshark will then pop up the Filters
dialog as shown in Figure 6.7, “The "Capture Filters" and "Display Filters" dialog boxes”.
Note!
The mechanisms for defining and saving capture filters and display filters are almost
identical. So both will be described here, differences between these two will be marked as
such.
Warning!
You must use Save to save your filters permanently. Ok or Apply will not save the filters,
so they will be lost when you close Wireshark.
Figure 6.7. The "Capture Filters" and "Display Filters" dialog boxes
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New
This button adds a new filter to the list of filters. The currently entered values from Filter name and Filter string will be used. If any of these fields are
empty, it will be set to "new".
Delete
This button deletes the selected filter. It will be greyed out, if no filter is selected.
Filter
You can select a filter from this list (which will fill in the filter name and filter string in the fields down at the bottom of the dialog box).
Filter name:
You can change the name of the currently selected filter here.
Note!
The filter name will only be used in this dialog to identify the
filter for your convenience, it will not be used elsewhere. You
can add multiple filters with the same name, but this is not
very useful.
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Filter string:
You can change the filter string of the currently selected filter here. Display
Filter only: the string will be syntax checked while you are typing.
Add Expression...
Display Filter only: This button brings up the Add Expression dialog box
which assists in building filter strings. You can find more information about
the Add Expression dialog in Section 6.5, “The "Filter Expression" dialog
box”
OK
Display Filter only: This button applies the selected filter to the current display and closes the dialog.
Apply
Display Filter only: This button applies the selected filter to the current display, and keeps the dialog open.
Save
Save the current settings in this dialog. The file location and format is explained in Appendix A, Files and Folders.
Close
Close this dialog. This will discard unsaved settings.
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6.7. Defining and saving filter macros
You can define filter macros with Wireshark and give them labels for later use. This can save time in remembering and retyping some of the more complex filters you use.
XXX - add an explanation of this.
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6.8. Finding packets
You can easily find packets once you have captured some packets or have read in a previously saved
capture file. Simply select the Find Packet... menu item from the Edit menu. Wireshark will pop up the
dialog box shown in Figure 6.8, “The "Find Packet" dialog box”.
6.8.1. The "Find Packet" dialog box
Figure 6.8. The "Find Packet" dialog box
You might first select the kind of thing to search for:
•
Display filter
Simply enter a display filter string into the Filter: field, select a direction, and click on OK.
For example, to find the three way handshake for a connection from host 192.168.0.1, use the following filter string:
ip.src==192.168.0.1 and tcp.flags.syn==1
For more details on display filters, see Section 6.3, “Filtering packets while viewing”
•
Hex Value
Search for a specific byte sequence in the packet data.
For example, use "00:00" to find the next packet including two null bytes in the packet data.
•
String
Find a string in the packet data, with various options.
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The value to be found will be syntax checked while you type it in. If the syntax check of your value succeeds, the background of the entry field will turn green, if it fails, it will turn red.
You can choose the search direction:
•
Up
Search upwards in the packet list (decreasing packet numbers).
•
Down
Search downwards in the packet list (increasing packet numbers).
6.8.2. The "Find Next" command
"Find Next" will continue searching with the same options used in the last "Find Packet".
6.8.3. The "Find Previous" command
"Find Previous" will do the same thing as "Find Next", but with reverse search direction.
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6.9. Go to a specific packet
You can easily jump to specific packets with one of the menu items in the Go menu.
6.9.1. The "Go Back" command
Go back in the packet history, works much like the page history in current web browsers.
6.9.2. The "Go Forward" command
Go forward in the packet history, works much like the page history in current web browsers.
6.9.3. The "Go to Packet" dialog box
Figure 6.9. The "Go To Packet" dialog box
This dialog box will let you enter a packet number. When you press OK, Wireshark will jump to that
packet.
6.9.4. The "Go to Corresponding Packet" command
If a protocol field is selected which points to another packet in the capture file, this command will jump
to that packet.
Note!
As these protocol fields now work like links (just as in your Web browser), it's easier to
simply double-click on the field to jump to the corresponding field.
6.9.5. The "Go to First Packet" command
This command will simply jump to the first packet displayed.
6.9.6. The "Go to Last Packet" command
This command will simply jump to the last packet displayed.
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6.10. Marking packets
You can mark packets in the "Packet List" pane. A marked packet will be shown with black background,
regardless of the coloring rules set. Marking a packet can be useful to find it later while analyzing in a
large capture file.
Warning!
The packet marks are not stored in the capture file or anywhere else, so all packet marks
will be lost if you close the capture file.
You can use packet marking to control the output of packets when saving/exporting/printing. To do so,
an option in the packet range is available, see Section 5.8, “The Packet Range frame”.
There are three functions to manipulate the marked state of a packet:
•
Mark packet (toggle) toggles the marked state of a single packet.
•
Mark all packets set the mark state of all packets.
•
Unmark all packets reset the mark state of all packets.
These mark function are available from the "Edit" menu, and the "Mark packet (toggle)" function is also
available from the pop-up menu of the "Packet List" pane.
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6.11. Time display formats and time references
While packets are captured, each packet is timestamped. These timestamps will be saved to the capture
file, so they will be available for later analysis.
A detailed description of timestamps, timezones and alike can be found at: Section 7.4, “Time Stamps”.
The timestamp presentation format and the precision in the packet list can be chosen using the View
menu, see Figure 3.5, “The "View" Menu”.
The available presentation formats are:
•
Date and Time of Day: 1970-01-01 01:02:03.123456 The absolute date and time of the day when
the packet was captured.
•
Time of Day: 01:02:03.123456 The absolute time of the day when the packet was captured.
•
Seconds Since Beginning of Capture: 123.123456 The time relative to the start of the capture file
or the first "Time Reference" before this packet (see Section 6.11.1, “Packet time referencing”).
•
Seconds Since Previous Captured Packet: 1.123456 The time relative to the previous captured
packet.
•
Seconds Since Previous Displayed Packet: 1.123456 The time relative to the previous displayed
packet.
•
Seconds Since Epoch (1970-01-01): 1234567890.123456 The time relative to epoch (midnight
UTC of January 1, 1970).
The available precisions (aka. the number of displayed decimal places) are:
•
Automatic The timestamp precision of the loaded capture file format will be used (the default).
•
Seconds, Deciseconds, Centiseconds, Milliseconds, Microseconds or Nanoseconds The
timestamp precision will be forced to the given setting. If the actually available precision is smaller,
zeros will be appended. If the precision is larger, the remaining decimal places will be cut off.
Precision example: If you have a timestamp and it's displayed using, "Seconds Since Previous Packet", :
the value might be 1.123456. This will be displayed using the "Automatic" setting for libpcap files
(which is microseconds). If you use Seconds it would show simply 1 and if you use Nanoseconds it
shows 1.123456000.
6.11.1. Packet time referencing
The user can set time references to packets. A time reference is the starting point for all subsequent
packet time calculations. It will be useful, if you want to see the time values relative to a special packet,
e.g. the start of a new request. It's possible to set multiple time references in the capture file.
Warning!
The time references will not be saved permanently and will be lost when you close the capture file.
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Note!
Time referencing will only be useful, if the time display format is set to "Seconds Since
Beginning of Capture". If one of the other time display formats are used, time referencing
will have no effect (and will make no sense either).
To work with time references, choose one of the "Time Reference" items in the "Edit" menu , see Section 3.6, “The "Edit" menu”, or from the pop-up menu of the "Packet List" pane.
•
Set Time Reference (toggle) Toggles the time reference state of the currently selected packet to on
or off.
•
Find Next Find the next time referenced packet in the "Packet List" pane.
•
Find Previous Find the previous time referenced packet in the "Packet List" pane.
Figure 6.10. Wireshark showing a time referenced packet
A time referenced packet will be marked with the string *REF* in the Time column (see packet number
10). All subsequent packets will show the time since the last time reference.
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Chapter 7. Advanced Topics
7.1. Introduction
In this chapter some of the advanced features of Wireshark will be described.
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7.2. Following TCP streams
If you are working with TCP based protocols it can be very helpful to see the data from a TCP stream in
the way that the application layer sees it. Perhaps you are looking for passwords in a Telnet stream, or
you are trying to make sense of a data stream. Maybe you just need a display filter to show only the
packets of that TCP stream. If so, Wireshark's ability to follow a TCP stream will be useful to you.
Simply select a TCP packet in the packet list of the stream/connection you are interested in and then select the Follow TCP Stream menu item from the Wireshark Tools menu (or use the context menu in the
packet list). Wireshark will set an appropriate display filter and pop up a dialog box with all the data
from the TCP stream laid out in order, as shown in Figure 7.1, “The "Follow TCP Stream" dialog box”.
Note!
It is worthwhile noting that Follow TCP Stream installs a display filter to select all the
packets in the TCP stream you have selected.
7.2.1. The "Follow TCP Stream" dialog box
Figure 7.1. The "Follow TCP Stream" dialog box
The stream content is displayed in the same sequence as it appeared on the network. Traffic from A to B
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is marked in red, while traffic from B to A is marked in blue. If you like, you can change these colors in
the Edit/Preferences "Colors" page.
Non-printable characters will be replaced by dots. XXX - What about line wrapping (maximum line
length) and CRNL conversions?
The stream content won't be updated while doing a live capture. To get the latest content you'll have to
reopen the dialog.
You can choose from the following actions:
1.
Save As: Save the stream data in the currently selected format.
2.
Print: Print the stream data in the currently selected format.
3.
Direction: Choose the stream direction to be displayed ("Entire conversation", "data from A to B
only" or "data from B to A only").
4.
Filter out this stream: Apply a display filter removing the current TCP stream data from the display.
5.
Close: Close this dialog box, leaving the current display filter in effect.
You can choose to view the data in one of the following formats:
1.
ASCII: In this view you see the data from each direction in ASCII. Obviously best for ASCII based
protocols, e.g. HTTP.
2.
EBCDIC: For the big-iron freaks out there.
3.
HEX Dump: This allows you to see all the data. This will require a lot of screen space and is best
used with binary protocols.
4.
C Arrays: This allows you to import the stream data into your own C program.
5.
Raw: This allows you to load the unaltered stream data into a different program for further examination. The display will look the same as the ASCII setting, but "Save As" will result in a binary file.
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7.3. Expert Infos
The expert infos is a kind of log of the anomalies found by Wireshark in a capture file.
The general idea behind the following "Expert Info" is to have a better display of "uncommon" or just
notable network behaviour. This way, both novice and expert users will hopefully find probable network
problems a lot faster, compared to scanning the packet list "manually" .
Expert infos are only a hint!
Take expert infos as a hint what's worth looking at, but not more. For example: The absence of expert infos doesn't necessarily mean everything is ok!
The amount of expert infos largely depends on the protocol
being used!
While some common protocols like TCP/IP will show detailed expert infos, most other
protocols currently won't show any expert infos at all.
The following will first describe the components of a single expert info, then the User Interface.
7.3.1. Expert Info Entries
Each expert info will contain the following things which will be described in detail below:
Table 7.1. Some example expert infos
Packet #
Severity
Group
Protocol
Summary
1
Note
Sequence
TCP
Duplicate
ACK (#1)
2
Chat
Sequence
TCP
Connection
reset (RST)
8
Note
Sequence
TCP
Keep-Alive
9
Warn
Sequence
TCP
Fast retransmission
(suspected)
7.3.1.1. Severity
Every expert info has a specific severity level. The following severity levels are used, in parentheses are
the colors in which the items will be marked in the GUI:
•
Chat (grey): information about usual workflow, e.g. a TCP packet with the SYN flag set
•
Note (cyan): notable things, e.g. an application returned an "usual" error code like HTTP 404
•
Warn (yellow): warning, e.g. application returned an "unusual" error code like a connection problem
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•
Error (red): serious problem, e.g. [Malformed Packet]
7.3.1.2. Group
There are some common groups of expert infos. The following are currently implemented:
•
Checksum: a checksum was invalid
•
Sequence: protocol sequence suspicious, e.g. sequence wasn't continuous or a retransmission was
detected or ...
•
Response Code: problem with application response code, e.g. HTTP 404 page not found
•
Request Code: an application request (e.g. File Handle == x), usually Chat level
•
Undecoded: dissector incomplete or data can't be decoded for other reasons
•
Reassemble: problems while reassembling, e.g. not all fragments were available or an exception
happened while reassembling
•
Malformed: malformed packet or dissector has a bug, dissection of this packet aborted
•
Debug: debugging (should not occur in release versions)
It's possible that more such group values will be added in the future ...
7.3.1.3. Protocol
The protocol in which the expert info was caused.
7.3.1.4. Summary
Each expert info will also have a short additional text with some further explanation.
7.3.2. "Expert Info Composite" dialog
From the main menu you can open the expert info dialog, using: "Analyze/Expert Info Composite"
XXX - "Analyze/Expert Info" also exists but is subject to removal and therefore not explained here.
XXX - add explanation of the dialogs context menu.
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7.3.2.1. Errors / Warnings / Notes / Chats tabs
An easy and quick way to find the most interesting infos (rather than using the Details tab), is to have a
look at the separate tabs for each severity level. As the tab label also contains the number of existing
entries, it's easy to find the tab with the most important entries.
There are usually a lot of identical expert infos only differing in the packet number. These identical infos
will be combined into a single line - with a count column showing how often they appeared in the capture file. Clicking on the plus sign shows the individual packet numbers in a tree view.
7.3.2.2. Details tab
The Details tab provides the expert infos in a "log like" view, each entry on its own line (much like the
packet list). As the amount of expert infos for a capture file can easily become very large, getting an idea
of the interesting infos with this view can take quite a while. The advantage of this tab is to have all
entries in the sequence as they appeared, this is sometimes a help to pinpoint problems.
7.3.3. "Colorized" Protocol Details Tree
The protocol field causing an expert info is colorized, e.g. uses a cyan background for a note severity
level. This color is propagated to the toplevel protocol item in the tree, so it's easy to find the field that
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caused the expert info.
For the example screenshot above, the IP "Time to live" value is very low (only 1), so the corresponding
protocol field is marked with a cyan background. To easier find that item in the packet tree, the IP protocol toplevel item is marked cyan as well.
7.3.4. "Expert" Packet List Column (optional)
An optional "Expert Info Severity" packet list column is available (since SVN 22387 -> 0.99.7), that displays the most significant severity of a packet, or stays empty if everything seems ok. This column is not
displayed by default, but can be easily added using the Preferences Columns page described in Section 9.5, “Preferences”.
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7.4. Time Stamps
Time stamps, their precisions and all that can be quite confusing. This section will provide you with information about what's going on while Wireshark processes time stamps.
While packets are captured, each packet is time stamped as it comes in. These time stamps will be saved
to the capture file, so they also will be available for (later) analysis.
So where do these time stamps come from? While capturing, Wireshark gets the time stamps from the
libpcap (WinPcap) library, which in turn gets them from the operating system kernel. If the capture data
is loaded from a capture file, Wireshark obviously gets the data from that file.
7.4.1. Wireshark internals
The internal format that Wireshark uses to keep a packet time stamp consists of the date (in days since
1.1.1970) and the time of day (in nanoseconds since midnight). You can adjust the way Wireshark displays the time stamp data in the packet list, see the "Time Display Format" item in the Section 3.7, “The
"View" menu” for details.
While reading or writing capture files, Wireshark converts the time stamp data between the capture file
format and the internal format as required.
While capturing, Wireshark uses the libpcap (WinPcap) capture library which supports microsecond resolution. Unless you are working with specialized capturing hardware, this resolution should be adequate.
7.4.2. Capture file formats
Every capture file format that Wireshark knows supports time stamps. The time stamp precision supported by a specific capture file format differs widely and varies from one second "0" to one nanosecond
"0.123456789". Most file formats store the time stamps with a fixed precision (e.g. microseconds),
while some file formats are even capable of storing the time stamp precision itself (whatever the benefit
may be).
The common libpcap capture file format that is used by Wireshark (and a lot of other tools) supports a
fixed microsecond resolution "0.123456" only.
Note!
Writing data into a capture file format that doesn't provide the capability to store the actual
precision will lead to loss of information. Example: If you load a capture file with nanosecond resolution and store the capture data to a libpcap file (with microsecond resolution)
Wireshark obviously must reduce the precision from nanosecond to microsecond.
7.4.3. Accuracy
It's often asked: "Which time stamp accuracy is provided by Wireshark?". Well, Wireshark doesn't create any time stamps itself but simply gets them from "somewhere else" and displays them. So accuracy
will depend on the capture system (operating system, performance, ...) that you use. Because of this, the
above question is difficult to answer in a general way.
Note!
USB connected network adapters often provide a very bad time stamp accuracy. The incoming packets have to take "a long and winding road" to travel through the USB cable
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until they actually reach the kernel. As the incoming packets are time stamped when they
are processed by the kernel, this time stamping mechanism becomes very inaccurate.
Conclusion: don't use USB connected NIC's when you need precise time stamp accuracy!
(XXX - are there any such NIC's that generate time stamps on the USB hardware?)
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7.5. Time Zones
If you travel across the planet, time zones can be confusing. If you get a capture file from somewhere
around the world time zones can even be a lot more confusing ;-)
First of all, there are two reasons why you may not need to think about time zones at all:
•
You are only interested in the time differences between the packet time stamps and don't need to
know the exact date and time of the captured packets (which is often the case).
•
You don't get capture files from different time zones than your own, so there are simply no time
zone problems. For example: everyone in your team is working in the same time zone as yourself.
What are time zones?
People expect that the time reflects the sunset. Dawn should be in the morning maybe around
06:00 and dusk in the evening maybe at 20:00. These times will obviously vary depending on the
season. It would be very confusing if everyone on earth would use the same global time as this
would correspond to the sunset only at a small part of the world.
For that reason, the earth is split into several different time zones, each zone with a local time that
corresponds to the local sunset.
The time zone's base time is UTC (Coordinated Universal Time) or Zulu Time (military and aviation). The older term GMT (Greenwich Mean Time) shouldn't be used as it is slightly incorrect
(up to 0.9 seconds difference to UTC). The UTC base time equals to 0 (based at Greenwich, England) and all time zones have an offset to UTC between -12 to +14 hours!
For example: If you live in Berlin you are in a time zone one hour earlier than UTC, so you are in
time zone "+1" (time difference in hours compared to UTC). If it's 3 o'clock in Berlin it's 2 o'clock
in UTC "at the same moment".
Be aware that at a few places on earth don't use time zones with even hour offsets (e.g. New Delhi
uses UTC+05:30)!
Further information can be found at: http://en.wikipedia.org/wiki/Time_zone and http://en.wikipedia.org/wiki/Coordinated_Universal_Time.
What is daylight saving time (DST)?
Daylight Saving Time (DST), also known as Summer Time, is intended to "save" some daylight
during the summer months. To do this, a lot of countries (but not all!) add a DST hour to the
already existing UTC offset. So you may need to take another hour (or in very rare cases even two
hours!) difference into your "time zone calculations".
Unfortunately, the date at which DST actually takes effect is different throughout the world. You
may also note, that the northern and southern hemispheres have opposite DST's (e.g. while it's
summer in Europe it's winter in Australia).
Keep in mind: UTC remains the same all year around, regardless of DST!
Further information can be found at: http://en.wikipedia.org/wiki/Daylight_saving.
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Further time zone and DST information can be found at: http://wwp.greenwichmeantime.com/ and http://www.timeanddate.com/worldclock/.
7.5.1. Set your computer's time correctly!
If you work with people around the world, it's very helpful to set your computer's time and time zone
right.
You should set your computers time and time zone in the correct sequence:
1.
Set your time zone to your current location
2.
Set your computer's clock to the local time
This way you will tell your computer both the local time and also the time offset to UTC.
Tip!
If you travel around the world, it's an often made mistake to adjust the hours of your computer clock to the local time. Don't adjust the hours but your time zone setting instead! For
your computer, the time is essentially the same as before, you are simply in a different time
zone with a different local time!
Tip!
You can use the Network Time Protocol (NTP) to automatically adjust your computer to
the correct time, by synchronizing it to Internet NTP clock servers. NTP clients are available for all operating systems that Wireshark supports (and for a lot more), for examples
see: http://www.ntp.org/.
7.5.2. Wireshark and Time Zones
So what's the relationship between Wireshark and time zones anyway?
Wireshark's native capture file format (libpcap format), and some other capture file formats, such as the
Windows Sniffer, EtherPeek, AiroPeek, and Sun snoop formats, save the arrival time of packets as UTC
values. UN*X systems, and "Windows NT based" systems (Windows NT 4.0, 2000, XP, Server 2003,
Vista, Server 2008) represent time internally as UTC. When Wireshark is capturing, no conversion is necessary. However, if the system time zone is not set correctly, the system's UTC time might not be correctly set even if the system clock appears to display correct local time. "Windows 9x based" systems
(Windows 95, Windows 98, Windows Me) represent time internally as local time. When capturing,
WinPcap has to convert the time to UTC before supplying it to Wireshark. If the system's time zone is
not set correctly, that conversion will not be done correctly.
Other capture file formats, such as the Microsoft Network Monitor, DOS-based Sniffer, and Network Instruments Observer formats, save the arrival time of packets as local time values.
Internally to Wireshark, time stamps are represented in UTC; this means that, when reading capture files
that save the arrival time of packets as local time values, Wireshark must convert those local time values
to UTC values.
Wireshark in turn will display the time stamps always in local time. The displaying computer will convert them from UTC to local time and displays this (local) time. For capture files saving the arrival time
of packets as UTC values, this means that the arrival time will be displayed as the local time in your
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time zone, which might not be the same as the arrival time in the time zone in which the packet was captured. For capture files saving the arrival time of packets as local time values, the conversion to UTC
will be done using your time zone's offset from UTC and DST rules, which means the conversion will
not be done correctly; the conversion back to local time for display might undo this correctly, in which
case the arrival time will be displayed as the arrival time in which the packet was captured.
Table 7.2. Time zone examples for UTC arrival times (without DST)
Los Angeles New York
Madrid
London
Berlin
Tokyo
Capture File 10:00
(UTC)
10:00
10:00
10:00
10:00
10:00
Local Offset -8
to UTC
-5
-1
0
+1
+9
Displayed
02:00
Time (Local
Time)
05:00
09:00
10:00
11:00
19:00
An example: Let's assume that someone in Los Angeles captured a packet with Wireshark at exactly 2
o'clock local time and sends you this capture file. The capture file's time stamp will be represented in
UTC as 10 o'clock. You are located in Berlin and will see 11 o'clock on your Wireshark display.
Now you have a phone call, video conference or Internet meeting with that one to talk about that capture
file. As you are both looking at the displayed time on your local computers, the one in Los Angeles still
sees 2 o'clock but you in Berlin will see 11 o'clock. The time displays are different as both Wireshark
displays will show the (different) local times at the same point in time.
Conclusion: You may not bother about the date/time of the time stamp you currently look at, unless you
must make sure that the date/time is as expected. So, if you get a capture file from a different time zone
and/or DST, you'll have to find out the time zone/DST difference between the two local times and "mentally adjust" the time stamps accordingly. In any case, make sure that every computer in question has the
correct time and time zone setting.
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7.6. Packet Reassembling
7.6.1. What is it?
Network protocols often need to transport large chunks of data, which are complete in themselves, e.g.
when transferring a file. The underlying protocol might not be able to handle that chunk size (e.g. limitation of the network packet size), or is stream-based like TCP, which doesn't know data chunks at all.
In that case the network protocol has to handle the chunk boundaries itself and (if required) spread the
data over multiple packets. It obviously also needs a mechanism to determine the chunk boundaries on
the receiving side.
Tip!
Wireshark calls this mechanism reassembling, although a specific protocol specification
might use a different term for this (e.g. desegmentation, defragmentation, ...).
7.6.2. How Wireshark handles it
For some of the network protocols Wireshark knows of, a mechanism is implemented to find, decode
and display these chunks of data. Wireshark will try to find the corresponding packets of this chunk, and
will show the combined data as additional pages in the "Packet Bytes" pane (for information about this
pane, see Section 3.18, “The "Packet Bytes" pane”).
Figure 7.2. The "Packet Bytes" pane with a reassembled tab
Note!
Reassembling might take place at several protocol layers, so it's possible that multiple tabs
in the "Packet Bytes" pane appear.
Note!
You will find the reassembled data in the last packet of the chunk.
An example: In a HTTP GET response, the requested data (e.g. an HTML page) is returned. Wireshark
will show the hex dump of the data in a new tab "Uncompressed entity body" in the "Packet Bytes"
pane.
Reassembling is enabled in the preferences by default. The defaults were changed from disabled to enabled in September 2005. If you created your preference settings before this date, you might look if reassembling is actually enabled, as it can be extremely helpful while analyzing network packets.
The enabling or disabling of the reassemble settings of a protocol typically requires two things:
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1.
the lower level protocol (e.g., TCP) must support reassembly. Often this reassembly can be enabled
or disabled via the protocol preferences.
2.
the higher level protocol (e.g., HTTP) must use the reassembly mechanism to reassemble fragmented protocol data. This too can often be enabled or disabled via the protocol preferences.
The tooltip of the higher level protocol setting will notify you if and which lower level protocol setting
also has to be considered.
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7.7. Name Resolution
Name resolution tries to resolve some of the numerical address values into a human readable format.
There are two possible ways to do these conversations, depending on the resolution to be done: calling
system/network services (like the gethostname function) and/or evaluate from Wireshark specific configuration files. For details about the configuration files Wireshark uses for name resolution and alike,
see Appendix A, Files and Folders.
The name resolution feature can be en-/disabled separately for the protocol layers of the following sections.
7.7.1. Name Resolution drawbacks
Name resolution can be invaluable while working with Wireshark and may even save you hours of
work. Unfortunately, it also has its drawbacks.
•
Name resolution will often fail. The name to be resolved might simply be unknown by the name
servers asked or the servers are just not available and the name is also not found in Wireshark's configuration files.
•
The resolved names are not stored in the capture file or somewhere else. So the resolved names
might not be available if you open the capture file later or on a different machine. Each time you
open a capture file it may look "slightly different", maybe simply because you can't connect to a
name server (which you could connect before).
•
DNS may add additional packets to your capture file. You may see packets to/from your machine
in your capture file, which are caused by name resolution network services of the machine Wireshark captures from. XXX - are there any other such packets than DNS ones?
•
Resolved DNS names are cached by Wireshark. This is required for acceptable performance.
However, if the name resolution information should change while Wireshark is running, Wireshark
won't notice a change to the name resolution information once it gets cached. If this information
changes while Wireshark is running, e.g. a new DHCP lease takes effect, Wireshark won't notice it.
XXX - is this true for all or only for DNS info?
Tip!
The name resolution in the packet list is done while the list is filled. If a name could be resolved after a packet was added to the list, that former entry won't be changed. As the
name resolution results are cached, you can use "View/Reload" to rebuild the packet list,
this time with the correctly resolved names. However, this isn't possible while a capture is
in progress.
7.7.2. Ethernet name resolution (MAC layer)
Try to resolve an Ethernet MAC address (e.g. 00:09:5b:01:02:03) to something more "human readable".
ARP name resolution (system service): Wireshark will ask the operating system to convert an Ethernet
address to the corresponding IP address (e.g. 00:09:5b:01:02:03 -> 192.168.0.1).
Ethernet codes (ethers file): If the ARP name resolution failed, Wireshark tries to convert the Ethernet
address to a known device name, which has been assigned by the user using an ethers file (e.g.
00:09:5b:01:02:03 -> homerouter).
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Ethernet manufacturer codes (manuf file): If neither ARP or ethers returns a result, Wireshark tries to
convert the first 3 bytes of an ethernet address to an abbreviated manufacturer name, which has been assigned by the IEEE (e.g. 00:09:5b:01:02:03 -> Netgear_01:02:03).
7.7.3. IP name resolution (network layer)
Try to resolve an IP address (e.g. 216.239.37.99) to something more "human readable".
DNS/ADNS name resolution (system/library service): Wireshark will ask the operating system (or the
ADNS library), to convert an IP address to the hostname associated with it (e.g. 216.239.37.99 ->
www.1.google.com). The DNS service is using synchronous calls to the DNS server. So Wireshark will
stop responding until a response to a DNS request is returned. If possible, you might consider using the
ADNS library (which won't wait for a network response).
Warning!
Enabling network name resolution when your name server is unavailable may significantly
slow down Wireshark while it waits for all of the name server requests to time out. Use
ADNS in that case.
DNS vs. ADNS: here's a short comparison: Both mechanisms are used to convert an IP address to some
human readable (domain) name. The usual DNS call gethostname() will try to convert the address to a
name. To do this, it will first ask the systems hosts file (e.g. /etc/hosts) if it finds a matching entry. If that
fails, it will ask the configured DNS server(s) about the name.
So the real difference between DNS and ADNS comes when the system has to wait for the DNS server
about a name resolution. The system call gethostname() will wait until a name is resolved or an error occurs. If the DNS server is unavailable, this might take quite a while (several seconds). The ADNS service will work a bit differently. It will also ask the DNS server, but it won't wait for the answer. It will
just return to Wireshark in a very short amount of time. The actual (and the following) address fields
won't show the resolved name until the ADNS call returned. As mentioned above, the values get cached,
so you can use View/Reload to "update" these fields to show the resolved values.
hosts name resolution (hosts file): If DNS name resolution failed, Wireshark will try to convert an IP
address to the hostname associated with it, using a hosts file provided by the user (e.g. 216.239.37.99 ->
www.google.com).
7.7.4. IPX name resolution (network layer)
ipxnet name resolution (ipxnets file): XXX - add ipxnets name resolution explanation.
7.7.5. TCP/UDP port name resolution (transport layer)
Try to resolve a TCP/UDP port (e.g. 80) to something more "human readable".
TCP/UDP port conversion (system service): Wireshark will ask the operating system to convert a TCP
or UDP port to its well known name (e.g. 80 -> http).
XXX - mention the role of the /etc/services file (but don't forget the files and folders section)!
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7.8. Checksums
Several network protocols use checksums to ensure data integrity.
Tip!
Applying checksums as described here is also known as redundancy checking.
What are checksums for?
Checksums are used to ensure the integrity of data portions for data transmission or storage. A
checksum is basically a calculated summary of such a data portion.
Network data transmissions often produce errors, such as toggled, missing or duplicated bits. As a
result, the data received might not be identical to the data transmitted, which is obviously a bad
thing.
Because of these transmission errors, network protocols very often use checksums to detect such
errors. The transmitter will calculate a checksum of the data and transmits the data together with
the checksum. The receiver will calculate the checksum of the received data with the same algorithm as the transmitter. If the received and calculated checksums don't match a transmission
error has occurred.
Some checksum algorithms are able to recover (simple) errors by calculating where the expected
error must be and repairing it.
If there are errors that cannot be recovered, the receiving side throws away the packet. Depending
on the network protocol, this data loss is simply ignored or the sending side needs to detect this
loss somehow and retransmits the required packet(s).
Using a checksum drastically reduces the number of undetected transmission errors. However, the
usual checksum algorithms cannot guarantee an error detection of 100%, so a very small number
of transmission errors may remain undetected.
There are several different kinds of checksum algorithms; an example of an often used checksum
algorithm is CRC32. The checksum algorithm actually chosen for a specific network protocol will
depend on the expected error rate of the network medium, the importance of error detection, the
processor load to perform the calculation, the performance needed and many other things.
Further information about checksums can be found at: http://en.wikipedia.org/wiki/Checksum.
7.8.1. Wireshark checksum validation
Wireshark will validate the checksums of several protocols, e.g.: IP, TCP, UDP, ...
It will do the same calculation as a "normal receiver" would do, and shows the checksum fields in the
packet details with a comment, e.g.: [correct], [invalid, must be 0x12345678] or alike.
Checksum validation can be switched off for various protocols in the Wireshark protocol preferences,
e.g. to (very slightly) increase performance.
If the checksum validation is enabled and it detected an invalid checksum, features like packet reassembling won't be processed. This is avoided as incorrect connection data could "confuse" the internal
database.
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Advanced Topics
7.8.2. Checksum offloading
The checksum calculation might be done by the network driver, protocol driver or even in hardware.
For example: The Ethernet transmitting hardware calculates the Ethernet CRC32 checksum and the receiving hardware validates this checksum. If the received checksum is wrong Wireshark won't even see
the packet, as the Ethernet hardware internally throws away the packet.
Higher level checksums are "traditionally" calculated by the protocol implementation and the completed
packet is then handed over to the hardware.
Recent network hardware can perform advanced features such as IP checksum calculation, also known
as checksum offloading. The network driver won't calculate the checksum itself but will simply hand
over an empty (zero or garbage filled) checksum field to the hardware.
Note!
Checksum offloading often causes confusion as the network packets to be transmitted are
handed over to Wireshark before the checksums are actually calculated. Wireshark gets
these "empty" checksums and displays them as invalid, even though the packets will contain valid checksums when they leave the network hardware later.
Checksum offloading can be confusing and having a lot of [invalid] messages on the screen can be quite
annoying. As mentioned above, invalid checksums may lead to unreassembled packets, making the analysis of the packet data much harder.
You can do two things to avoid this checksum offloading problem:
•
Turn off the checksum offloading in the network driver, if this option is available.
•
Turn off checksum validation of the specific protocol in the Wireshark preferences.
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Advanced Topics
158
Chapter 8. Statistics
8.1. Introduction
Wireshark provides a wide range of network statistics which can be accessed via the Statistics menu.
These statistics range from general information about the loaded capture file (like the number of captured packets), to statistics about specific protocols (e.g. statistics about the number of HTTP requests
and responses captured).
•
•
General statistics:
•
Summary about the capture file.
•
Protocol Hierarchy of the captured packets.
•
Conversations e.g. traffic between specific IP addresses.
•
Endpoints e.g. traffic to and from an IP addresses.
•
IO Graphs visualizing the number of packets (or similar) in time.
Protocol specific statistics:
•
Service Response Time between request and response of some protocols.
•
Various other protocol specific statistics.
Note!
The protocol specific statistics requires detailed knowledge about the specific protocol.
Unless you are familiar with that protocol, statistics about it will be pretty hard to understand.
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Statistics
8.2. The "Summary" window
General statistics about the current capture file.
Figure 8.1. The "Summary" window
160
Statistics
•
File: general information about the capture file.
•
Time: the timestamps when the first and the last packet were captured (and the time between them).
161
Statistics
•
Capture: information from the time when the capture was done (only available if the packet data
was captured from the network and not loaded from a file).
•
Display: some display related information.
•
Traffic: some statistics of the network traffic seen. If a display filter is set, you will see values in the
Captured column, and if any packages are marked, you will see values in the Marked column. The
values in the Captured column will remain the same as before, while the values in the Displayed
column will reflect the values corresponding to the packets shown in the display. The values in the
Marked column will reflect the values corresponding to the marked packages.
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Statistics
8.3. The "Protocol Hierarchy" window
The protocol hierarchy of the captured packets.
Figure 8.2. The "Protocol Hierarchy" window
This is a tree of all the protocols in the capture. You can collapse or expand subtrees, by clicking on the
plus / minus icons. By default, all trees are expanded.
Each row contains the statistical values of one protocol. The Display filter will show the current display
filter.
The following columns containing the statistical values are available:
•
Protocol: this protocol's name
•
% Packets: the percentage of protocol packets, relative to all packets in the capture
•
Packets: the absolute number of packets of this protocol
•
Bytes: the absolute number of bytes of this protocol
•
MBit/s: the bandwidth of this protocol, relative to the capture time
•
End Packets: the absolute number of packets of this protocol (where this protocol was the highest
protocol to decode)
•
End Bytes: the absolute number of bytes of this protocol (where this protocol was the highest pro163
Statistics
tocol to decode)
•
End MBit/s: the bandwidth of this protocol, relative to the capture time (where this protocol was the
highest protocol to decode)
Note!
Packets will usually contain multiple protocols, so more than one protocol will be counted
for each packet. Example: In the screenshot IP has 99,17% and TCP 85,83% (which is together much more than 100%).
Note!
Protocol layers can consist of packets that won't contain any higher layer protocol, so the
sum of all higher layer packets may not sum up to the protocols packet count. Example: In
the screenshot TCP has 85,83% but the sum of the subprotocols (HTTP, ...) is much less.
This may be caused by TCP protocol overhead, e.g. TCP ACK packets won't be counted as
packets of the higher layer).
Note!
A single packet can contain the same protocol more than once. In this case, the protocol is
counted more than once. For example: in some tunneling configurations the IP layer can
appear twice.
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Statistics
8.4. Conversations
Statistics of the captured conversations.
8.4.1. What is a Conversation?
A network conversation is the traffic between two specific endpoints. For example, an IP conversation is
all the traffic between two IP addresses. The description of the known endpoint types can be found in
Section 8.5.1, “What is an Endpoint?”.
8.4.2. The "Conversations" window
The conversations window is similar to the endpoint Window; see Section 8.5.2, “The "Endpoints" window” for a description of their common features. Along with addresses, packet counters, and byte counters the conversation window adds four columns: the time in seconds between the start of the capture
and the start of the conversation ("Rel Start"), the duration of the conversation in seconds, and the average bits (not bytes) per second in each direction.
Figure 8.3. The "Conversations" window
Each row in the list shows the statistical values for exactly one conversation.
Name resolution will be done if selected in the window and if it is active for the specific protocol layer
(MAC layer for the selected Ethernet endpoints page).
Limit to display filter will only show conversations matching the current display filter.
The copy button will copy the list values to the clipboard in CSV (Comma Separated Values) format.
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Statistics
Tip!
This window will be updated frequently, so it will be useful, even if you open it before (or
while) you are doing a live capture.
8.4.3. The protocol specific "Conversation List" windows
Before the combined window described above was available, each of its pages was shown as a separate
window. Even though the combined window is much more convenient to use, these separate windows
are still available. The main reason is that they might process faster for very large capture files.
However, as the functionality is exactly the same as in the combined window, they won't be discussed in
detail here.
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Statistics
8.5. Endpoints
Statistics of the endpoints captured.
Tip!
If you are looking for a feature other network tools call a hostlist, here is the right place to
look. The list of Ethernet or IP endpoints is usually what you're looking for.
8.5.1. What is an Endpoint?
A network endpoint is the logical endpoint of separate protocol traffic of a specific protocol layer. The
endpoint statistics of Wireshark will take the following endpoints into account:
•
Ethernet: an Ethernet endpoint is identical to the Ethernet's MAC address.
•
Fibre Channel: XXX - insert info here.
•
FDDI: a FDDI endpoint is identical to the FDDI MAC address.
•
IPv4: an IP endpoint is identical to its IP address.
•
IPX: XXX - insert info here.
•
TCP: a TCP endpoint is a combination of the IP address and the TCP port used, so different TCP
ports on the same IP address are different TCP endpoints.
•
Token Ring: a Token Ring endpoint is identical to the Token Ring MAC address.
•
UDP: a UDP endpoint is a combination of the IP address and the UDP port used, so different UDP
ports on the same IP address are different UDP endpoints.
Broadcast / multicast endpoints
Broadcast / multicast traffic will be shown separately as additional endpoints. Of course, as
these endpoints are virtual endpoints, the real traffic will be received by all (multicast:
some) of the listed unicast endpoints.
8.5.2. The "Endpoints" window
This window shows statistics about the endpoints captured.
Figure 8.4. The "Endpoints" window
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Statistics
For each supported protocol, a tab is shown in this window. Each tab label shows the number of endpoints captured (e.g. the tab label "Ethernet: 5" tells you that five ethernet endpoints have been captured). If no endpoints of a specific protocol were captured, the tab label will be greyed out (although the
related page can still be selected).
Each row in the list shows the statistical values for exactly one endpoint.
Name resolution will be done if selected in the window and if it is active for the specific protocol layer
(MAC layer for the selected Ethernet endpoints page). As you might have noticed, the first row has a
name resolution of the first three bytes "Netgear", the second row's address was resolved to an IP address (using ARP) and the third was resolved to a broadcast (unresolved this would still be:
ff:ff:ff:ff:ff:ff); the last two Ethernet addresses remain unresolved.
Limit to display filter will only show conversations matching the current display filter.
The copy button will copy the list values to the clipboard in CSV (Comma Separated Values) format.
Tip!
This window will be updated frequently, so it will be useful, even if you open it before (or
while) you are doing a live capture.
8.5.3. The protocol specific "Endpoint List" windows
Before the combined window described above was available, each of its pages was shown as a separate
window. Even though the combined window is much more convenient to use, these separate windows
are still available. The main reason is that they might process faster for very large capture files.
However, as the functionality is exactly the same as in the combined window, they won't be discussed in
detail here.
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Statistics
8.6. The "IO Graphs" window
User configurable graph of the captured network packets.
You can define up to five differently colored graphs.
Figure 8.5. The "IO Graphs" window
The user can configure the following things:
•
•
Graphs
•
Graph 1-5: enable the specific graph 1-5 (only graph 1 is enabled by default)
•
Color: the color of the graph (cannot be changed)
•
Filter: a display filter for this graph (only the packets that pass this filter will be taken into account for this graph)
•
Style: the style of the graph (Line/Impulse/FBar/Dot)
X Axis
•
Tick interval: an interval in x direction lasts (10/1 minutes or 10/1/0.1/0.01/0.001 seconds)
•
Pixels per tick: use 10/5/2/1 pixels per tick interval
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Statistics
•
•
View as time of day: option to view x direction labels as time of day instead of seconds or
minutes since beginning of capture
Y Axis
•
Unit: the unit for the y direction (Packets/Tick, Bytes/Tick, Bits/Tick, Advanced...) [XXX - describe the Advanced feature.]
•
Scale: the scale for the y unit (Logarithmic,Auto,10,20,50,100,200,500,...)
The save button will save the currently displayed portion of the graph as one of various file formats. The
save feature is only available when using GTK version 2.6 or higher (the latest Windows versions comply with this requirement) and Wireshark version 0.99.7 or higher.
The copy button will copy values from selected graphs to the clipboard in CSV (Comma Separated Values) format. The copy feature is only available in Wireshark version 0.99.8 or higher.
Tip!
Click in the graph to select the first package in the selected interval.
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Statistics
8.7. Compare two capture files
Compare two capture files.
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Statistics
8.8. WLAN Traffic Statistics
Statistics of the captured WLAN traffic. This window will summarize the wireless network traffic found
in the capture. Probe requests will be merged into an existing network if the SSID matches.
Figure 8.6. The "WLAN Traffic Statistics" window
Each row in the list shows the statistical values for exactly one wireless network.
Name resolution will be done if selected in the window and if it is active for the MAC layer.
Only show existing networks will exclude probe requests with a SSID not matching any network from
the list.
The copy button will copy the list values to the clipboard in CSV (Comma Separated Values) format.
Tip!
This window will be updated frequently, so it will be useful, even if you open it before (or
while) you are doing a live capture.
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Statistics
8.9. LTE MAC Traffic Statistics
Statistics of the captured LTE MAC traffic. This window will summarize the LTE MAC traffic found in
the capture.
Figure 8.7. The "LTE MAC Traffic Statistics" window
The top pane shows statistics for common channels. Each row in the middle pane shows statistical highlights for exactly one UE/C-RNTI. In the lower pane, you can see the for the currently selected UE/
C-RNTI the traffic broken down by individual channel.
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Statistics
8.10. Service Response Time
The service response time is the time between a request and the corresponding response. This information is available for many protocols.
Service response time statistics are currently available for the following protocols:
•
DCE-RPC
•
Fibre Channel
•
H.225 RAS
•
LDAP
•
LTE MAC
•
MGCP
•
ONC-RPC
•
SMB
As an example, the DCE-RPC service response time is described in more detail.
Note!
The other Service Response Time windows will work the same way (or only slightly different) compared to the following description.
8.10.1. The "Service Response Time DCE-RPC" window
The service response time of DCE-RPC is the time between the request and the corresponding response.
First of all, you have to select the DCE-RPC interface:
Figure 8.8. The "Compute DCE-RPC statistics" window
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Statistics
You can optionally set a display filter, to reduce the amount of packets.
Figure 8.9. The "DCE-RPC Statistic for ..." window
Each row corresponds to a method of the interface selected (so the EPM interface in version 3 has 7
methods). For each method the number of calls, and the statistics of the SRT time is calculated.
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Statistics
8.11. The protocol specific statistics windows
The protocol specific statistics windows display detailed information of specific protocols and might be
described in a later version of this document.
Some of these statistics are described at the http://wiki.wireshark.org/Statistics pages.
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Statistics
177
Chapter 9. Customizing Wireshark
9.1. Introduction
Wireshark's default behaviour will usually suit your needs pretty well. However, as you become more
familiar with Wireshark, it can be customized in various ways to suit your needs even better. In this
chapter we explore:
•
How to start Wireshark with command line parameters
•
How to colorize the packet list
•
How to control protocol dissection
•
How to use the various preference settings
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Customizing Wireshark
9.2. Start Wireshark from the command line
You can start Wireshark from the command line, but it can also be started from most Window managers
as well. In this section we will look at starting it from the command line.
Wireshark supports a large number of command line parameters. To see what they are, simply enter the
command wireshark -h and the help information shown in Example 9.1, “Help information available
from Wireshark” (or something similar) should be printed.
Example 9.1. Help information available from Wireshark
Wireshark 0.99.6
Interactively dump and analyze network traffic.
See http://www.wireshark.org for more information.
Copyright 1998-2007 Gerald Combs <[email protected]> and contributors.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Usage: wireshark [options] ... [ <infile> ]
Capture interface:
-i <interface>
-f <capture filter>
-s <snaplen>
-p
-k
-Q
-S
-l
-B <buffer size>
-y <link type>
-D
-L
Capture stop conditions:
-c <packet count>
-a <autostop cond.> ...
name or idx of interface (def: first non-loopback)
packet filter in libpcap filter syntax
packet snapshot length (def: 65535)
don't capture in promiscuous mode
start capturing immediately (def: do nothing)
quit Wireshark after capturing
update packet display when new packets are captured
turn on automatic scrolling while -S is in use
size of kernel buffer (def: 1MB)
link layer type (def: first appropriate)
print list of interfaces and exit
print list of link-layer types of iface and exit
stop after n
duration:NUM
filesize:NUM
files:NUM
packets (def: infinite)
- stop after NUM seconds
- stop this file after NUM KB
- stop after NUM files
Capture output:
-b <ringbuffer opt.> ... duration:NUM - switch to next file after NUM secs
filesize:NUM - switch to next file after NUM KB
files:NUM - ringbuffer: replace after NUM files
Input file:
-r <infile>
set the filename to read from (no pipes or stdin!)
Processing:
-R <read filter>
-n
-N <name resolve flags>
packet filter in Wireshark display filter syntax
disable all name resolutions (def: all enabled)
enable specific name resolution(s): "mntC"
User
-g
-m
-t
-X
-z
go to specified packet number after "-r"
set the font name used for most text
output format of time stamps (def: r: rel. to first)
eXtension options, see man page for details
show various statistics, see man page for details
interface:
<packet number>
<font>
ad|a|r|d|dd|e
<key>:<value>
<statistics>
Output:
-w <outfile|->
Miscellaneous:
-h
-v
-P <key:path>
-o <name>:<value> ...
set the output filename (or '-' for stdout)
display this help and exit
display version info and exit
persconf:path - personal configuration files
persdata:path - personal data files
override preference or recent setting
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Customizing Wireshark
We will examine each of the command line options in turn.
The first thing to notice is that issuing the command wireshark by itself will bring up Wireshark.
However, you can include as many of the command line parameters as you like. Their meanings are as
follows ( in alphabetical order ): XXX - is the alphabetical order a good choice? Maybe better task
based?
-a <capture autostop condition>
-b <capture ring buffer option>
Specify a criterion that specifies when Wireshark is to stop writing to a capture file. The criterion is of the form test:value, where
test is one of:
duration:value
Stop writing to a capture file after value of
seconds have elapsed.
filesize:value
Stop writing to a capture file after it
reaches a size of value kilobytes (where a
kilobyte is 1000 bytes, not 1024 bytes). If
this option is used together with the -b option, Wireshark will stop writing to the
current capture file and switch to the next
one if filesize is reached.
files:value
Stop writing to capture files after value
number of files were written.
If a maximum capture file size was specified, this option causes
Wireshark to run in "ring buffer" mode, with the specified number
of files. In "ring buffer" mode, Wireshark will write to several
capture files. Their name is based on the number of the file and on
the creation date and time.
When the first capture file fills up, Wireshark will switch to writing to the next file, until it fills up the last file, at which point it'll
discard the data in the first file (unless 0 is specified, in which
case, the number of files is unlimited) and start writing to that file
and so on.
If the optional duration is specified, Wireshark will also switch to
the next file when the specified number of seconds has elapsed
even if the current file is not completely fills up.
-B <capture buffer size (Win32
only)>
duration:value
Switch to the next file after value seconds
have elapsed, even if the current file is not
completely filled up.
filesize:value
Switch to the next file after it reaches a
size of value kilobytes (where a kilobyte is
1000 bytes, not 1024 bytes).
files:value
Begin again with the first file after value
number of files were written (form a ring
buffer).
Win32 only: set capture buffer size (in MB, default is 1MB). This
is used by the the capture driver to buffer packet data until that
data can be written to disk. If you encounter packet drops while
capturing, try to increase this size.
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Customizing Wireshark
-c <capture packet count>
This option specifies the maximum number of packets to capture
when capturing live data. It would be used in conjunction with the
-k option.
-D
Print a list of the interfaces on which Wireshark can capture, and
exit. For each network interface, a number and an interface name,
possibly followed by a text description of the interface, is printed.
The interface name or the number can be supplied to the -i flag to
specify an interface on which to capture.
This can be useful on systems that don't have a command to list
them (e.g., Windows systems, or UNIX systems lacking ifconfig a); the number can be useful on Windows 2000 and later systems,
where the interface name is a somewhat complex string.
Note that "can capture" means that Wireshark was able to open
that device to do a live capture; if, on your system, a program doing a network capture must be run from an account with special
privileges (for example, as root), then, if Wireshark is run with
the -D flag and is not run from such an account, it will not list any
interfaces.
-f <capture filter>
This option sets the initial capture filter expression to be used
when capturing packets.
-g <packet number>
After reading in a capture file using the -r flag, go to the given
packet number.
-h
The -h option requests Wireshark to print its version and usage instructions (as shown above) and exit.
-i <capture interface>
Set the name of the network interface or pipe to use for live packet capture.
Network interface names should match one of the names listed in
wireshark -D (described above); a number, as reported by wireshark -D, can also be used. If you're using UNIX, netstat -i or ifconfig -a might also work to list interface names, although not all
versions of UNIX support the -a flag to ifconfig.
If no interface is specified, Wireshark searches the list of interfaces, choosing the first non-loopback interface if there are any
non-loopback interfaces, and choosing the first loopback interface
if there are no non-loopback interfaces; if there are no interfaces,
Wireshark reports an error and doesn't start the capture.
Pipe names should be either the name of a FIFO (named pipe) or
``-'' to read data from the standard input. Data read from pipes
must be in standard libpcap format.
-k
The -k option specifies that Wireshark should start capturing
packets immediately. This option requires the use of the -i parameter to specify the interface that packet capture will occur from.
-l
This option turns on automatic scrolling if the packet list pane is
being updated automatically as packets arrive during a capture (
as specified by the -S flag).
-L
List the data link types supported by the interface and exit.
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Customizing Wireshark
-m <font>
This option sets the name of the font used for most text displayed
by Wireshark. XXX - add an example!
-n
Disable network object name resolution (such as hostname, TCP
and UDP port names).
-N <name resolving flags>
Turns on name resolving for particular types of addresses and port
numbers; the argument is a string that may contain the letters m to
enable MAC address resolution, n to enable network address resolution, and t to enable transport-layer port number resolution.
This overrides -n if both -N and -n are present. The letter C enables concurrent (asynchronous) DNS lookups.
-o <preference/recent settings>
Sets a preference or recent value, overriding the default value and
any value read from a preference/recent file. The argument to the
flag is a string of the form prefname:value, where prefname is the
name of the preference (which is the same name that would appear in the preference/recent file), and value is the value to which
it should be set. Multiple instances of -o <preference settings>
can be given on a single command line.
An example of setting a single preference would be:
wireshark -o mgcp.display_dissect_tree:TRUE
An example of setting multiple preferences would be:
wireshark
-o
mgcp.display_dissect_tree:TRUE
mgcp.udp.callagent_port:2627
-o
Tip!
You can get a list of all available preference strings
from the preferences file, see Appendix A, Files and
Folders.
User access tables can be overridden using "uat," followed by the
UAT file name and a valid record for the file:
wireshark
-o
"uat:user_dlts:\"User
(DLT=147)\",\"http\",\"0\",\"\",\"0\",\"\""
0
The example above would dissect packets with a libpcap data link
type 147 as HTTP, just as if you had configured it in the
DLT_USER protocol preferences.
-p
Don't put the interface into promiscuous mode. Note that the interface might be in promiscuous mode for some other reason;
hence, -p cannot be used to ensure that the only traffic that is captured is traffic sent to or from the machine on which Wireshark is
running, broadcast traffic, and multicast traffic to addresses received by that machine.
-P <path setting>
Special path settings usually detected automatically. This is used
for special cases, e.g. starting Wireshark from a known location
on an USB stick.
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Customizing Wireshark
The criterion is of the form key:path, where key is one of:
persconf:path
path of personal configuration files, like the
preferences files.
persdata:path
path of personal data files, it's the folder initially opened. After the initialization, the recent file will keep the folder last used.
-Q
This option forces Wireshark to exit when capturing is complete.
It can be used with the -c option. It must be used in conjunction
with the -i and -w options.
-r <infile>
This option provides the name of a capture file for Wireshark to
read and display. This capture file can be in one of the formats
Wireshark understands.
-R <read (display) filter>
This option specifies a display filter to be applied when reading
packets from a capture file. The syntax of this filter is that of the
display filters discussed in Section 6.3, “Filtering packets while
viewing”. Packets not matching the filter are discarded.
-s <capture snaplen>
This option specifies the snapshot length to use when capturing
packets. Wireshark will only capture <snaplen> bytes of data for
each packet.
-S
This option specifies that Wireshark will display packets as it captures them. This is done by capturing in one process and displaying them in a separate process. This is the same as "Update list of
packets in real time" in the Capture Options dialog box.
-t <time stamp format>
This option sets the format of packet timestamps that are displayed in the packet list window. The format can be one of:
•
r relative, which specifies timestamps are displayed relative to
the first packet captured.
•
a absolute, which specifies that actual times be displayed for
all packets.
•
ad absolute with date, which specifies that actual dates and
times be displayed for all packets.
•
d delta, which specifies that timestamps are relative to the previous packet.
•
e epoch, which specifies that timestamps are seconds since
epoch (Jan 1, 1970 00:00:00)
-v
The -v option requests Wireshark to print out its version information and exit.
-w <savefile>
This option sets the name of the savefile to be used when saving a
capture file.
-y <capture link type>
If a capture is started from the command line with -k, set the data
link type to use while capturing packets. The values reported by L are the values that can be used.
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-X <eXtension option>
Specify an option to be passed to a TShark module. The eXtension option is in the form extension_key:value, where extension_key can be:
lua_script:lua_script_filename; Tells Wireshark to load the given
script in addition to the default Lua scripts.
-z <statistics-string>
Get Wireshark to collect various types of statistics and display the
result in a window that updates in semi-real time. XXX - add
more details here!
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9.3. Packet colorization
A very useful mechanism available in Wireshark is packet colorization. You can set-up Wireshark so
that it will colorize packets according to a filter. This allows you to emphasize the packets you are
(usually) interested in.
Tip!
You will find a lot of Coloring Rule examples at the Wireshark Wiki Coloring Rules
page at http://wiki.wireshark.org/ColoringRules.
There are two types of coloring rules in Wireshark. Temporary ones that are only used until you quit the
program. And permanent ones that will be saved to a preference file so that they are available on a next
session.
Temporary coloring rules can be added by selecting a packet and pressing the <ctrl> key together with
one of the number keys. This will create a coloring rule based on the currently selected conversation. It
will try to create a conversation filter based on TCP first, then UDP, then IP and at last Ethernet. Temporary filters can also be created by selecting the "Colorize with Filter > Color X" menu items when
rightclicking in the packet-detail pane.
To permanently colorize packets, select the Coloring Rules... menu item from the View menu; Wireshark will pop up the "Coloring Rules" dialog box as shown in Figure 9.1, “The "Coloring Rules" dialog
box”.
Figure 9.1. The "Coloring Rules" dialog box
Once the Coloring Rules dialog box is up, there are a number of buttons you can use, depending on
whether or not you have any color filters installed already.
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Note!
You will need to carefully select the order the coloring rules are listed as they are applied
in order from top to bottom. So, more specific rules need to be listed before more general
rules. For example, if you have a color rule for UDP before the one for DNS, the color rule
for DNS will never be applied (as DNS uses UDP, so the UDP rule will match first).
If this is the first time you have used Coloring Rules, click on the New button which will bring up the
Edit color filter dialog box as shown in Figure 9.2, “The "Edit Color Filter" dialog box”.
Figure 9.2. The "Edit Color Filter" dialog box
In the Edit Color dialog box, simply enter a name for the color filter, and enter a filter string in the Filter
text field. Figure 9.2, “The "Edit Color Filter" dialog box” shows the values arp and arp which means
that the name of the color filter is arp and the filter will select protocols of type arp. Once you have
entered these values, you can choose a foreground and background color for packets that match the filter
expression. Click on Foreground color... or Background color... to achieve this and Wireshark will
pop up the Choose foreground/background color for protocol dialog box as shown in Figure 9.3, “The
"Choose color" dialog box”.
Figure 9.3. The "Choose color" dialog box
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Select the color you desire for the selected packets and click on OK.
Note!
You must select a color in the colorbar next to the colorwheel to load values into the RGB
values. Alternatively, you can set the values to select the color you want.
Figure 9.4, “Using color filters with Wireshark” shows an example of several color filters being used in
Wireshark. You may not like the color choices, however, feel free to choose your own.
If you are uncertain which coloring rule actually took place for a specific packet, have a look at the
[Coloring Rule Name: ...] and [Coloring Rule String: ...] fields.
Figure 9.4. Using color filters with Wireshark
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9.4. Control Protocol dissection
The user can control how protocols are dissected.
Each protocol has its own dissector, so dissecting a complete packet will typically involve several dissectors. As Wireshark tries to find the right dissector for each packet (using static "routes" and heuristics
"guessing"), it might choose the wrong dissector in your specific case. For example, Wireshark won't
know if you use a common protocol on an uncommon TCP port, e.g. using HTTP on TCP port 800 instead of the standard port 80.
There are two ways to control the relations between protocol dissectors: disable a protocol dissector
completely or temporarily divert the way Wireshark calls the dissectors.
9.4.1. The "Enabled Protocols" dialog box
The Enabled Protocols dialog box lets you enable or disable specific protocols; all protocols are enabled
by default. When a protocol is disabled, Wireshark stops processing a packet whenever that protocol is
encountered.
Note!
Disabling a protocol will prevent information about higher-layer protocols from being displayed. For example, suppose you disabled the IP protocol and selected a packet containing Ethernet, IP, TCP, and HTTP information. The Ethernet information would be displayed, but the IP, TCP and HTTP information would not - disabling IP would prevent it
and the other protocols from being displayed.
To enable/disable protocols select the Enabled Protocols... item from the Analyze menu; Wireshark
will pop up the "Enabled Protocols" dialog box as shown in Figure 9.5, “The "Enabled Protocols" dialog
box”.
Figure 9.5. The "Enabled Protocols" dialog box
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To disable or enable a protocol, simply click on it using the mouse or press the space bar when the protocol is highlighted. Note that typing the first few letters of the protocol name when the Enabled Protocols dialog box is active will temporarily open a search text box and automatically select the first matching protocol name (if it exists).
Warning!
You have to use the Save button to save your settings. The OK or Apply buttons will not
save your changes permanently, so they will be lost when Wireshark is closed.
You can choose from the following actions:
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1.
Enable All: Enable all protocols in the list.
2.
Disable All: Disable all protocols in the list.
3.
Invert: Toggle the state of all protocols in the list.
4.
OK: Apply the changes and close the dialog box.
5.
Apply: Apply the changes and keep the dialog box open.
6.
Save: Save the settings to the disabled_protos, see Appendix A, Files and Folders for details.
7.
Cancel: Cancel the changes and close the dialog box.
9.4.2. User Specified Decodes
The "Decode As" functionality let you temporarily divert specific protocol dissections. This might be
useful for example, if you do some uncommon experiments on your network.
Decode As is accessed by selecting the Decode As... item from the Analyze menu; Wireshark will pop
up the "Decode As" dialog box as shown in Figure 9.6, “The "Decode As" dialog box”.
Figure 9.6. The "Decode As" dialog box
The content of this dialog box depends on the selected packet when it was opened.
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Warning!
The user specified decodes can not be saved. If you quit Wireshark, these settings will be
lost.
1.
Decode: Decode packets the selected way.
2.
Do not decode: Do not decode packets the selected way.
3.
Link/Network/Transport: Specify the network layer at which "Decode As" should take place.
Which of these pages are available depends on the content of the selected packet when this dialog
box is opened.
4.
Show Current: Open a dialog box showing the current list of user specified decodes.
5.
OK: Apply the currently selected decode and close the dialog box.
6.
Apply: Apply the currently selected decode and keep the dialog box open.
7.
Cancel: Cancel the changes and close the dialog box.
9.4.3. Show User Specified Decodes
This dialog box shows the currently active user specified decodes.
Figure 9.7. The "Decode As: Show" dialog box
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1.
OK: Close this dialog box.
2.
Clear: Removes all user specified decodes.
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9.5. Preferences
There are a number of preferences you can set. Simply select the Preferences... menu item from the
Edit menu; and Wireshark will pop up the Preferences dialog box as shown in Figure 9.8, “The preferences dialog box”, with the "User Interface" page as default. On the left side is a tree where you can select the page to be shown.
Note!
Preference settings are added frequently. For a recent explanation of the preference pages
and their settings have a look at the Wireshark Wiki Preferences page at http://wiki.wireshark.org/Preferences.
Warning!
The OK or Apply button will not save the preference settings, you'll have to save the settings by clicking the Save button.
•
The OK button will apply the preferences settings and close the dialog.
•
The Apply button will apply the preferences settings and keep the dialog open.
•
The Save button will apply the preferences settings, save the settings on the hard disk and keep the
dialog open.
•
The Cancel button will restore all preferences settings to the last saved state.
Figure 9.8. The preferences dialog box
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9.5.1. Interface Options
In the Capture preferences it is possible to configure several options for the interfaces available on your
computer. Select the Capture pane and press the Interfaces: Edit button. In this window it is possible to
change the default link-layer header type for the interface, add a comment or choose to hide a interface
from other parts of the program.
Figure 9.9. The interface options dialog box
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Each row contains options for each interface available on your computer.
•
Device: the device name provided by the operating system.
•
Description: provided by the operating system.
•
Default link-layer: each interface may provide several link-layer header types. The default linklayer chosen here is the one used when you first start Wireshark. It is also possible to change this
value in Section 4.5, “The "Capture Options" dialog box” when you start a capture. For a detailed
description, see Section 4.8, “Link-layer header type”.
•
Comment: a user provided description of the interface. This comment will be used as a description
instead of the operating system description.
•
Hide?: enable this option to hide the interface from other parts of the program.
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9.6. Configuration Profiles
Configuration Profiles can be used to configure and use more than one set of preferences and configurations. Select the Configuration Profiles... menu item from the Edit menu, or simply press Shift-Ctrl-A;
and Wireshark will pop up the Configuration Profiles dialog box as shown in Figure 9.10, “The configuration profiles dialog box”. It is also possible to click in the "Profile" part of the statusbar to popup a
menu with available Configuration Profiles (Figure 3.19, “The Statusbar with a configuration profile
menu”).
Configuration files stored in the Profiles:
•
Preferences (preferences) (Section 9.5, “Preferences”)
•
Capture Filters (cfilters) (Section 6.6, “Defining and saving filters”)
•
Display Filters (dfilters) (Section 6.6, “Defining and saving filters”)
•
Coloring Rules (colorfilters) (Section 9.3, “Packet colorization”)
•
Disabled Protocols (disabled_protos) (Section 9.4.1, “The "Enabled Protocols" dialog box”)
•
User Accessible Tables:
•
•
Display Filter Macros (dfilter_macros) (Section 9.8, “Display Filter Macros”)
•
GeoIP Database Paths (geoip_db_paths) (Section 9.9, “GeoIP Database Paths”)
•
K12 Protocols (k12_protos) (Section 9.10, “Tektronix K12xx/15 RF5 protocols Table”)
•
PRES Users Context List (pres_context_list) (Section 9.11, “PRES Users Context List”)
•
SCCP Users Table (sccp_users) (Section 9.12, “SCCP users Table”)
•
SMI Modules (smi_modules) (Section 9.13, “SMI (MIB and PIB) Modules”)
•
SMI Paths (smi_paths) (Section 9.14, “SMI (MIB and PIB) Paths”)
•
SNMP Users (snmp_users) (Section 9.15, “SNMP users Table”)
•
User DLTs Table (user_dlts) (Section 9.16, “User DLTs protocol table”)
Some recent settings (recent), such as pane sizes in the Main window (Section 3.3, “The Main window”), column widths in the packet list (Section 3.16, “The "Packet List" pane”), all selections in the
"View" menu (Section 3.7, “The "View" menu”) and the last directory navigated to in the File Open
dialog.
Other configurations
All other configurations are stored in the personal configuration folder, and are common to
all profiles.
Figure 9.10. The configuration profiles dialog box
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New
This button adds a new profile to the profiles list. The name of the
created profile is "New profile" and can be changed in the Properties
field.
Delete
This button deletes the selected profile, including all configuration
files used in this profile. It is not possible to delete the "Default" profile.
Configuration Profiles
You can select a configuration profile from this list (which will fill in
the profile name in the fields down at the bottom of the dialog box).
Profile name:
You can change the name of the currently selected profile here.
Used as a folder name
The profile name will be used as a folder name in the
configured "Personal configurations" folder. If adding
multiple profiles with the same name, only one profile
will be created.
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Illegal characters
On Windows the profile name cannot start or end with
a period (.), and cannot contain any of the following
characters: \ / : * ? " < > |
On Unix the profile name cannot contain the '/' character.
OK
This button saves all changes, applies the selected profile and closes
the dialog.
Apply
This button saves all changes, applies the selected profile and keeps
the dialog open.
Cancel
Close this dialog. This will discard unsaved settings, new profiles
will not be added and deleted profiles will not be deleted.
Help
Show this help page.
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9.7. User Table
The User Table editor is used for managing various tables in wireshark. Its main dialog works very similarly to that of Section 9.3, “Packet colorization”.
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9.8. Display Filter Macros
Display Filter Macros are a mechanism to create shortcuts for complex filters. For example defining a
display filter macro named tcp_conv whose text is ( (ip.src == $1 and ip.dst == $2 and tcp.srcport ==
$3 and tcp.dstport == $4) or (ip.src == $2 and ip.dst == $1 and tcp.srcport == $4 and tcp.dstport
== $3) ) would allow to use a display filter like ${tcp_conv:10.1.1.2;10.1.1.3;1200;1400} instead of
typing the whole filter.
Display Filter Macros can be managed with a Section 9.7, “User Table” by selecting the Display Filter
Macros menu item from the View Menu. The User Table has the following fields
Nam
e
Text
The name of the macro.
The replacement text for the macro it uses $1, $2, $3, ... as the input arguments.
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9.9. GeoIP Database Paths
If your copy of Wireshark supports MaxMind's GeoIP library, you can use their databases to match IP
addresses to countries, cites, autonomous system numbers, ISPs, and other bits of information. Some
databases are available at no cost, while others require a licensing fee. See the MaxMind web site for
more information.
This table is handled by an Section 9.7, “User Table” with the following fields.
Database pathname
This specifies a directory containing GeoIP data files. Any files beginning
with Geo and ending with .dat will be automatically loaded. A total of 8
files can be loaded.
The locations for your data files are up to you, but /usr/share/GeoIP
(Linux),
C:\GeoIP
(Windows),
C:\Program
Files\Wireshark\GeoIP (Windows) might be good choices.
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9.10. Tektronix K12xx/15 RF5 protocols Table
The Tektronix K12xx/15 rf5 file format uses helper files (*.stk) to identify the various protocols that are
used by a certain interface. Wireshark doesn't read these stk files, it uses a table that helps it identify
which lowest layer protocol to use.
Stk file to protocol matching is handled by an Section 9.7, “User Table” with the following fields.
Match string
A partial match for an stk filename, the first match wins, so if you have a specific
case and a general one the specific one must appear first in the list.
Protocol
This is the name of the encapsulating protocol (the lowest layer in the packet data) it
can be either just the name of the protocol (e.g. mtp2, eth_witoutfcs, sscf-nni ) or
the name of the encapsulation protocol and the "application" protocol over it separated by a colon (e.g sscop:sscf-nni, sscop:alcap, sscop:nbap, ...)
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9.11. PRES Users Context List
Wireshark uses this table to map a presentation context identifier to a given object identifier when the
capture does not contain a PRES package with a presentation context definition list for the conversation.
This table is handled by an Section 9.7, “User Table” with the following fields.
Context Id
An Integer representing the presentation context identifier for which this association is valid.
Syntax Name OID
The object identifier representing the abstract syntax name, which defines the
protocol that is carried over this association.
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9.12. SCCP users Table
Wireshark uses this table to map specific protocols to a certain DPC/SSN combination for SCCP.
This table is handled by an Section 9.7, “User Table” with the following fields.
Network Indicator
An Integer representing the network indicator for which this association is
valid.
Called DPCs
An range of integers representing the dpcs for which this association is valid.
Called SSNs
An range of integers representing the ssns for which this association is valid.
User protocol
The protocol that is carried over this association
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9.13. SMI (MIB and PIB) Modules
If your copy of Wireshark supports libSMI, you can specify a list of MIB and PIB modules here. The
COPS and SNMP dissectors can use them to resolve OIDs.
Module name
The name of the module, e.g. IF-MIB.
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9.14. SMI (MIB and PIB) Paths
If your copy of Wireshark supports libSMI, you can specify one or more paths to MIB and PIB modules
here.
Directory name
A module directory, e.g. /usr/local/snmp/mibs. Wireshark automatically
uses the standard SMI path for your system, so you usually don't have to add
anything here.
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9.15. SNMP users Table
Wireshark uses this table to verify authentication and to decrypt encrypted SNMPv3 packets.
This table is handled by an Section 9.7, “User Table” with the following fields.
Engine ID
If given this entry will be used only for packets whose engine id is this.
This field takes an hexadecimal string in the form 0102030405.
Username
This is the userName. When a single user has more than one password
for different SNMP-engines the first entry to match both is taken, if you
need a catch all engine-id (empty) that entry should be the last one.
Authentication model
Which auth model to use (either "MD5" or "SHA1").
Password
The authentication password. Use '\xDD' for unprintable characters. An
hexadecimal password must be entered as a sequence of '\xDD' characters. For example the hex password 010203040506 must be entered as
'\x01\x02\x03\x04\x05\x06'.
Privacy protocol
Which encryption algorithm to use (either "DES" or "AES").
Privacy password
The privacy password. Use '\xDD' for unprintable characters. An hexadecimal password must be entered as a sequence of '\xDD' characters.
For example the hex password 010203040506 must be entered as
'\x01\x02\x03\x04\x05\x06'.
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9.16. User DLTs protocol table
When a pcap file uses one of the user DLTs (147 to 162) wireshark uses this table to know which protocol(s) to use for each user DLT.
This table is handled by an Section 9.7, “User Table” with the following fields.
DLT
One of the user dlts.
Payload protocol
This is the name of the payload protocol (the lowest layer in the packet data).
(e.g. "eth" for ethernet, "ip" for IPv4)
Header size
If there is a header protocol (before the payload protocol) this tells which size
this header is. A value of 0 disables the header protocol.
Header protocol
The name of the header protocol to be used (uses "data" as default).
Trailer size
If there is a trailer protocol (after the payload protocol) this tells which size
this trailer is. A value of 0 disables the trailer protocol.
Trailer protocol
The name of the trailer protocol to be used (uses "data" as default).
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9.17. IKEv2 decryption table
Wireshark can decrypt Encrypted Payloads of IKEv2 (Internet Key Exchange version 2) packets if necessary information is provided. Note that you can decrypt only IKEv2 packets with this feature. If you
want to decrypt IKEv1 packets or ESP packets, use Log Filename setting under ISAKMP protocol preference or settings under ESP protocol preference respectively.
This table is handled by an Section 9.7, “User Table” with the following fields.
Initiator's SPI
Initiator's SPI of the IKE_SA. This field takes hexadecimal string
without "0x" prefix and the length must be 16 hex chars (represents 8
octets).
Responder's SPI
Responder's SPI of the IKE_SA. This field takes hexadecimal string
without "0x" prefix and the length must be 16 hex chars (represents 8
octets).
SK_ei
Key used to encrypt/decrypt IKEv2 packets from initiator to responder.
This field takes hexadecimal string without "0x" prefix and its length
must meet the requirement of the encryption algorithm selected.
SK_er
Key used to encrypt/decrypt IKEv2 packets from responder to initiator.
This field takes hexadecimal string without "0x" prefix and its length
must meet the requirement of the encryption algorithm selected.
Encryption Algorithm
Encryption algorithm of the IKE_SA.
SK_ai
Key used to calculate Integrity Checksum Data for IKEv2 packets from
responder to initiator. This field takes hexadecimal string without "0x"
prefix and its length must meet the requirement of the integrity algorithm selected.
SK_ar
Key used to calculate Integrity Checksum Data for IKEv2 packets from
initiator to responder. This field takes hexadecimal string without "0x"
prefix and its length must meet the requirement of the integrity algorithm selected.
Integrity Algorithm
Integrity algorithm of the IKE_SA.
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Chapter 10. Lua Support in Wireshark
10.1. Introduction
Wireshark has an embedded Lua interpreter. Lua is a powerful light-weight programming language designed for extending applications. Lua is designed and implemented by a team at PUC-Rio, the Pontifical Catholic University of Rio de Janeiro in Brazil. Lua was born and raised at Tecgraf, the Computer
Graphics Technology Group of PUC-Rio, and is now housed at Lua.org. Both Tecgraf and Lua.org are
laboratories of the Department of Computer Science.
In Wireshark Lua can be used to write dissectors and taps.
Wireshark's Lua interpreter starts by loading init.lua that is located in the global configuration directory
of Wireshark. Lua is disabled by default by setting the variable disable_lua to true in init.lua. To enable
lua the line that sets that variable must be removed or commented out.
After loading init.lua from the data directory if lua is enabled Wireshark will try to load a file named
init.lua in the user's directory.
The command line option -X lua_script:<file.lua> can be used to load lua scripts as well.
The Lua code will be executed once after all the protocols have being initialized and before reading any
file.
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10.2. Example of Dissector written in Lua
do
local p_multi = Proto("multi","MultiProto");
local vs_protos = {
[2] = "mtp2",
[3] = "mtp3",
[4] = "alcap",
[5] = "h248",
[6] = "ranap",
[7] = "rnsap",
[8] = "nbap"
}
local f_proto = ProtoField.uint8("multi.protocol","Protocol",base.DEC,vs_protos)
local f_dir = ProtoField.uint8("multi.direction","Direction",base.DEC,{ [1] = "incoming", [0] =
local f_text = ProtoField.string("multi.text","Text")
p_multi.fields = { f_proto, f_dir, f_text }
local data_dis = Dissector.get("data")
local protos = {
[2] = Dissector.get("mtp2"),
[3] = Dissector.get("mtp3"),
[4] = Dissector.get("alcap"),
[5] = Dissector.get("h248"),
[6] = Dissector.get("ranap"),
[7] = Dissector.get("rnsap"),
[8] = Dissector.get("nbap"),
[9] = Dissector.get("rrc"),
[10] = DissectorTable.get("sctp.ppi"):get_dissector(3), -- m3ua
[11] = DissectorTable.get("ip.proto"):get_dissector(132), -- sctp
}
function p_multi.dissector(buf,pkt,root)
local t = root:add(p_multi,buf(0,2))
t:add(f_proto,buf(0,1))
t:add(f_dir,buf(1,1))
local proto_id = buf(0,1):uint()
local dissector = protos[proto_id]
if dissector ~= nil then
dissector:call(buf(2):tvb(),pkt,root)
elseif proto_id < 2 then
t:add(f_text,buf(2))
-- pkt.cols.info:set(buf(2,buf:len() - 3):string())
else
data_dis:call(buf(2):tvb(),pkt,root)
end
end
local wtap_encap_table = DissectorTable.get("wtap_encap")
local udp_encap_table = DissectorTable.get("udp.port")
wtap_encap_table:add(wtap.USER15,p_multi)
wtap_encap_table:add(wtap.USER12,p_multi)
udp_encap_table:add(7555,p_multi)
end
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10.3. Example of Listener written in Lua
-- This program will register a menu that will open a window with a count of occurrences
-- of every address in the capture
do
local function menuable_tap()
-- Declare the window we will use
local tw = TextWindow.new("Address Counter")
-- This will contain a hash of counters of appearances of a certain address
local ips = {}
-- this is our tap
local tap = Listener.new();
function remove()
-- this way we remove the listener than otherwise will remain running indifinit
tap:remove();
end
-- we tell the window to call the remove() function when closed
tw:set_atclose(remove)
-- this function will be called once for each packet
function tap.packet(pinfo,tvb)
local src = ips[tostring(pinfo.src)] or 0
local dst = ips[tostring(pinfo.dst)] or 0
ips[tostring(pinfo.src)] = src + 1
ips[tostring(pinfo.dst)] = dst + 1
end
-- this function will be called once every few seconds to update our window
function tap.draw(t)
tw:clear()
for ip,num in pairs(ips) do
tw:append(ip .. "\t" .. num .. "\n");
end
end
-- this function will be called whenever a reset is needed
-- e.g. when reloading the capture file
function tap.reset()
tw:clear()
ips = {}
end
end
-- using this function we register our fuction
-- to be called when the user selects the Tools->Test->Packets menu
register_menu("Test/Packets", menuable_tap, MENU_TOOLS)
end
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10.4. Wireshark's Lua API Reference Manual
This Part of the User Guide describes the Wireshark specific functions in the embedded Lua.
10.4.1. Saving capture files
10.4.1.1. Dumper
10.4.1.1.1. Dumper.new(filename, [filetype], [encap])
Creates a file to write packets. Dumper:new_for_current() will probably be a better choice.
10.4.1.1.1.1. Arguments
filename
The name of the capture file to be created
filetype (optional)
The type of the file to be created
encap (optional)
The encapsulation to be used in the file to be created
10.4.1.1.1.2. Returns
The newly created Dumper object
10.4.1.1.1.3. Errors
•
Not every filetype handles every encap
10.4.1.1.2. dumper:close()
Closes a dumper
10.4.1.1.2.1. Errors
•
Cannot operate on a closed dumper
10.4.1.1.3. dumper:flush()
Writes all unsaved data of a dumper to the disk.
10.4.1.1.4. dumper:dump(timestamp, pseudoheader, bytearray)
Dumps an arbitrary packet. Note: Dumper:dump_current() will fit best in most cases.
10.4.1.1.4.1. Arguments
timestamp
The absolute timestamp the packet will have
pseudoheader
The Pseudoheader to use.
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bytearray
the data to be saved
10.4.1.1.5. dumper:new_for_current([filetype])
Creates a capture file using the same encapsulation as the one of the cuurrent packet
10.4.1.1.5.1. Arguments
filetype (optional)
The file type. Defaults to pcap.
10.4.1.1.5.2. Returns
The newly created Dumper Object
10.4.1.1.5.3. Errors
•
Cannot be used outside a tap or a dissector
10.4.1.1.6. dumper:dump_current()
Dumps the current packet as it is.
10.4.1.1.6.1. Errors
•
Cannot be used outside a tap or a dissector
10.4.1.2. PseudoHeader
A pseudoheader to be used to save captured frames.
10.4.1.2.1. PseudoHeader.none()
Creates a "no" pseudoheader.
10.4.1.2.1.1. Returns
A null pseudoheader
10.4.1.2.2. PseudoHeader.eth([fcslen])
Creates an ethernet pseudoheader
10.4.1.2.2.1. Arguments
fcslen (optional)
The fcs length
10.4.1.2.2.2. Returns
The ethernet pseudoheader
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10.4.1.2.3. PseudoHeader.atm([aal], [vpi], [vci], [channel], [cells], [aal5u2u],
[aal5len])
Creates an ATM pseudoheader
10.4.1.2.3.1. Arguments
aal (optional)
AAL number
vpi (optional)
VPI
vci (optional)
VCI
channel (optional)
Channel
cells (optional)
Number of cells in the PDU
aal5u2u (optional)
AAL5 User to User indicator
aal5len (optional)
AAL5 Len
10.4.1.2.3.2. Returns
The ATM pseudoheader
10.4.1.2.4. PseudoHeader.mtp2()
Creates an MTP2 PseudoHeader
10.4.1.2.4.1. Returns
The MTP2 pseudoheader
10.4.2. Obtaining dissection data
10.4.2.1. Field
A Field extractor to to obtain field values.
10.4.2.1.1. Field.new(fieldname)
Create a Field extractor
10.4.2.1.1.1. Arguments
fieldname
The filter name of the field (e.g. ip.addr)
10.4.2.1.1.2. Returns
The field extractor
10.4.2.1.1.3. Errors
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•
A Field extractor must be defined before Taps or Dissectors get called
10.4.2.1.2. field:__call()
Obtain all values (see FieldInfo) for this field.
10.4.2.1.2.1. Returns
All the values of this field
10.4.2.1.2.2. Errors
•
Fields cannot be used outside dissectors or taps
10.4.2.2. FieldInfo
An extracted Field
10.4.2.2.1. fieldinfo:__len()
Obtain the Length of the field
10.4.2.2.2. fieldinfo:__unm()
Obtain the Offset of the field
10.4.2.2.3. fieldinfo:__call()
Obtain the Value of the field
10.4.2.2.4. fieldinfo:__tostring()
The string representation of the field
10.4.2.2.5. fieldinfo:__eq()
Checks whether lhs is within rhs
10.4.2.2.5.1. Errors
•
Data source must be the same for both fields
10.4.2.2.6. fieldinfo:__le()
Checks whether the end byte of lhs is before the end of rhs
10.4.2.2.7. fieldinfo:__lt()
Checks whether the end byte of rhs is before the beginning of rhs
10.4.2.2.7.1. Errors
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•
Data source must be the same for both fields
10.4.2.2.8. fieldinfo.name
The name of this field
10.4.2.2.9. fieldinfo.label
The string representing this field
10.4.2.2.10. fieldinfo.value
The value of this field
10.4.2.2.11. fieldinfo.len
The length of this field
10.4.2.2.12. fieldinfo.offset
The offset of this field
10.4.2.3. Non Method Functions
10.4.2.3.1. all_field_infos()
Obtain all fields from the current tree
10.4.2.3.1.1. Errors
•
Cannot be called outside a listener or dissector
10.4.3. GUI support
10.4.3.1. ProgDlg
Manages a progress bar dialog.
10.4.3.1.1. ProgDlg.new([title], [task])
Creates a new TextWindow.
10.4.3.1.1.1. Arguments
title (optional)
Title of the new window, defaults to "Progress".
task (optional)
Current task, defaults to "".
10.4.3.1.1.2. Returns
The newly created TextWindow object.
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10.4.3.1.2. progdlg:update(progress, [task])
Appends text
10.4.3.1.2.1. Arguments
progress
Part done ( e.g. 0.75 ).
task (optional)
Current task, defaults to "".
10.4.3.1.2.2. Errors
•
Cannot be called for something not a ProgDlg
•
Progress value out of range (must be between 0.0 and 1.0)
10.4.3.1.3. progdlg:stopped()
Checks wheher the user has pressed the stop button.
10.4.3.1.3.1. Returns
true if the user has asked to stop the progress.
10.4.3.1.3.2. Errors
•
Cannot be called for something not a ProgDlg
10.4.3.1.4. progdlg:close()
Appends text
10.4.3.1.4.1. Errors
•
Cannot be called for something not a ProgDlg
10.4.3.2. TextWindow
Manages a text window.
10.4.3.2.1. TextWindow.new([title])
Creates a new TextWindow.
10.4.3.2.1.1. Arguments
title (optional)
Title of the new window.
10.4.3.2.1.2. Returns
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The newly created TextWindow object.
10.4.3.2.2. textwindow:set_atclose(action)
Set the function that will be called when the window closes
10.4.3.2.2.1. Arguments
action
A function to be executed when the user closes the window
10.4.3.2.2.2. Returns
The TextWindow object.
10.4.3.2.2.3. Errors
•
Cannot be called for something not a TextWindow
10.4.3.2.3. textwindow:set(text)
Sets the text.
10.4.3.2.3.1. Arguments
text
The text to be used.
10.4.3.2.3.2. Returns
The TextWindow object.
10.4.3.2.3.3. Errors
•
Cannot be called for something not a TextWindow
10.4.3.2.4. textwindow:append(text)
Appends text
10.4.3.2.4.1. Arguments
text
The text to be appended
10.4.3.2.4.2. Returns
The TextWindow object.
10.4.3.2.4.3. Errors
•
Cannot be called for something not a TextWindow
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10.4.3.2.5. textwindow:prepend(text)
Prepends text
10.4.3.2.5.1. Arguments
text
The text to be appended
10.4.3.2.5.2. Returns
The TextWindow object.
10.4.3.2.5.3. Errors
•
Cannot be called for something not a TextWindow
10.4.3.2.6. textwindow:clear()
Erases all text in the window.
10.4.3.2.6.1. Returns
The TextWindow object.
10.4.3.2.6.2. Errors
•
Cannot be called for something not a TextWindow
10.4.3.2.7. textwindow:get_text()
Get the text of the window
10.4.3.2.7.1. Returns
The TextWindow's text.
10.4.3.2.7.2. Errors
•
Cannot be called for something not a TextWindow
10.4.3.2.8. textwindow:set_editable([editable])
Make this window editable
10.4.3.2.8.1. Arguments
editable (optional)
A boolean flag, defaults to true
10.4.3.2.8.2. Returns
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The TextWindow object.
10.4.3.2.8.3. Errors
•
Cannot be called for something not a TextWindow
10.4.3.2.9. textwindow:add_button(label, function)
10.4.3.2.9.1. Arguments
label
The label of the button
function
The function to be called when clicked
10.4.3.2.9.2. Returns
The TextWindow object.
10.4.3.2.9.3. Errors
•
Cannot be called for something not a TextWindow
10.4.3.3. Non Method Functions
10.4.3.3.1. gui_enabled()
Checks whether the GUI facility is enabled.
10.4.3.3.1.1. Returns
A boolean: true if it is enabled, false if it isn't.
10.4.3.3.2. register_menu(name, action, [group])
Register a menu item in one of the main menus.
10.4.3.3.2.1. Arguments
name
The name of the menu item. The submenus are to be separated by '/'s. (string)
action
The function to be called when the menu item is invoked. (function taking no
arguments and returning nothing)
group (optional)
The menu group into which the menu item is to be inserted. If omitted, defaults to MENU_STAT_GENERIC. One of MENU_STAT (Statistics),
MENU_STAT_GENERIC
(Statistics,
first
section),
MENU_STAT_CONVERSATION
(Statistics/Conversation
List),
MENU_STAT_ENDPOINT
(Statistics/Endpoint
List),
MENU_STAT_RESPONSE
(Statistics/Service
Response
Time),
MENU_STAT_TELEPHONY (Telephony), MENU_ANALYZE (Analyze),
MENU_ANALYZE_CONVERSATION (Analyze/Conversation Filter),
MENU_TOOLS (Tools). (number)
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10.4.3.3.3. new_dialog(title, action, ...)
Pops up a new dialog
10.4.3.3.3.1. Arguments
title
Title of the dialog's window.
action
Action to be performed when OKd.
...
A series of strings to be used as labels of the dialog's fields
10.4.3.3.3.2. Errors
•
At least one field required
•
All fields must be strings
10.4.3.3.4. retap_packets()
Rescan all packets and just run taps - don't reconstruct the display.
10.4.3.3.5. copy_to_clipboard(text)
Copy a string into the clipboard
10.4.3.3.5.1. Arguments
text
The string to be copied into the clipboard.
10.4.3.3.6. open_capture_file(filename, filter)
Open and display a capture file
10.4.3.3.6.1. Arguments
filename
The name of the file to be opened.
filter
A filter to be applied as the file gets opened.
10.4.3.3.7. set_filter(text)
Set the main filter text
10.4.3.3.7.1. Arguments
text
The filter's text.
10.4.3.3.8. apply_filter()
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Apply the filter in the main filter box
10.4.3.3.9. reload()
Reload the current capture file
10.4.3.3.10. browser_open_url(url)
Open an url in a browser
10.4.3.3.10.1. Arguments
url
The url.
10.4.3.3.11. browser_open_data_file(filename)
Open an file in a browser
10.4.3.3.11.1. Arguments
filename
The url.
10.4.4. Post-dissection packet analysis
10.4.4.1. Listener
A Listener, is called once for every packet that matches a certain filter or has a certain tap. It can read
the tree, the packet's Tvb eventually the tapped data but it cannot add elements to the tree.
10.4.4.1.1. Listener.new([tap], [filter])
Creates a new Listener listener
10.4.4.1.1.1. Arguments
tap (optional)
The name of this tap
filter (optional)
A filter that when matches the tap.packet function gets called (use nil to be
called for every packet)
10.4.4.1.1.2. Returns
The newly created Listener listener object
10.4.4.1.1.3. Errors
•
tap registration error
10.4.4.1.2. listener:remove()
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Removes a tap listener
10.4.4.1.3. listener.packet
A function that will be called once every packet matches the Listener listener filter. function
tap.packet(pinfo,tvb,userdata) ... end
10.4.4.1.4. listener.draw
A function that will be called once every few seconds to redraw the gui objects in tshark this funtion is
called oly at the very end of the capture file. function tap.draw(userdata) ... end
10.4.4.1.5. listener.reset
A function that will be called at the end of the capture run. function tap.reset(userdata) ... end
10.4.5. Obtaining packet information
10.4.5.1. Address
Represents an address
10.4.5.1.1. Address.ip(hostname)
Creates an Address Object representing an IP address.
10.4.5.1.1.1. Arguments
hostname
The address or name of the IP host.
10.4.5.1.1.2. Returns
The Address object
10.4.5.1.2. address:__tostring()
10.4.5.1.2.1. Returns
The string representing the address.
10.4.5.1.3. address:__eq()
Compares two Addresses
10.4.5.1.4. address:__le()
Compares two Addresses
10.4.5.1.5. address:__lt()
Compares two Addresses
10.4.5.2. Column
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A Column in the packet list
10.4.5.2.1. column:__tostring()
10.4.5.2.1.1. Returns
A string representing the column
10.4.5.2.2. column:clear()
Clears a Column
10.4.5.2.3. column:set(text)
Sets the text of a Column
10.4.5.2.3.1. Arguments
text
The text to which to set the Column
10.4.5.2.4. column:append(text)
Appends text to a Column
10.4.5.2.4.1. Arguments
text
The text to append to the Column
10.4.5.2.5. column:preppend(text)
Prepends text to a Column
10.4.5.2.5.1. Arguments
text
The text to prepend to the Column
10.4.5.3. Columns
The Columns of the packet list.
10.4.5.3.1. columns:__tostring()
10.4.5.3.1.1. Returns
The string "Columns", no real use, just for debugging purposes.
10.4.5.3.2. columns:__newindex(column, text)
Sets the text of a specific column
10.4.5.3.2.1. Arguments
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column
The name of the column to set
text
The text for the column
10.4.5.4. Pinfo
Packet information
10.4.5.4.1. pinfo.number
The number of this packet in the current file
10.4.5.4.2. pinfo.len
The length of the frame
10.4.5.4.3. pinfo.caplen
The captured length of the frame
10.4.5.4.4. pinfo.abs_ts
When the packet was captured
10.4.5.4.5. pinfo.rel_ts
Number of seconds passed since beginning of capture
10.4.5.4.6. pinfo.delta_ts
Number of seconds passed since the last captured packet
10.4.5.4.7. pinfo.delta_dis_ts
Number of seconds passed since the last displayed packet
10.4.5.4.8. pinfo.visited
Whether this packet hass been already visited
10.4.5.4.9. pinfo.src
Source Address of this Packet
10.4.5.4.10. pinfo.dst
Destination Address of this Packet
10.4.5.4.11. pinfo.lo
lower Address of this Packet
10.4.5.4.12. pinfo.hi
higher Address of this Packet
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10.4.5.4.13. pinfo.dl_src
Data Link Source Address of this Packet
10.4.5.4.14. pinfo.dl_dst
Data Link Destination Address of this Packet
10.4.5.4.15. pinfo.net_src
Network Layer Source Address of this Packet
10.4.5.4.16. pinfo.net_dst
Network Layer Destination Address of this Packet
10.4.5.4.17. pinfo.ptype
Type of Port of .src_port and .dst_port
10.4.5.4.18. pinfo.src_port
Source Port of this Packet
10.4.5.4.19. pinfo.dst_port
Source Address of this Packet
10.4.5.4.20. pinfo.ipproto
IP Protocol id
10.4.5.4.21. pinfo.circuit_id
For circuit based protocols
10.4.5.4.22. pinfo.match
Port/Data we are matching
10.4.5.4.23. pinfo.curr_proto
Which Protocol are we dissecting
10.4.5.4.24. pinfo.columns
Accesss to the packet list columns
10.4.5.4.25. pinfo.cols
Accesss to the packet list columns (equivalent to pinfo.columns)
10.4.5.4.26. pinfo.desegment_len
Estimated number of additional bytes required for completing the PDU
10.4.5.4.27. pinfo.desegment_offset
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Offset in the tvbuff at which the dissector will continue processing when next called
10.4.5.4.28. pinfo.private_data
Access to private data
10.4.6. Functions for writing dissectors
10.4.6.1. Dissector
A refererence to a dissector, used to call a dissector against a packet or a part of it.
10.4.6.1.1. Dissector.get(name)
Obtains a dissector reference by name
10.4.6.1.1.1. Arguments
name
The name of the dissector
10.4.6.1.1.2. Returns
The Dissector reference
10.4.6.1.2. dissector:call(tvb, pinfo, tree)
Calls a dissector against a given packet (or part of it)
10.4.6.1.2.1. Arguments
tvb
The buffer to dissect
pinfo
The packet info
tree
The tree on which to add the protocol items
10.4.6.2. DissectorTable
A table of subdissectors of a particular protocol (e.g. TCP subdissectors like http, smtp, sip are added to
table "tcp.port"). Useful to add more dissectors to a table so that they appear in the Decode As... dialog.
10.4.6.2.1. DissectorTable.new(tablename, [uiname], [type], [base])
Creates a new DissectorTable for your dissector's use.
10.4.6.2.1.1. Arguments
tablename
The short name of the table.
uiname (optional)
The name of the table in the User Interface (defaults to the name given).
type (optional)
Either FT_UINT* or FT_STRING (defaults to FT_UINT32)
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base (optional)
Either
BASE_NONE,
BASE_DEC,
BASE_HEX,
BASE_OCT,
BASE_DEC_HEX or BASE_HEX_DEC (defaults to BASE_DEC)
10.4.6.2.1.2. Returns
The newly created DissectorTable
10.4.6.2.2. DissectorTable.get(tablename)
Obtain a reference to an existing dissector table.
10.4.6.2.2.1. Arguments
tablename
The short name of the table.
10.4.6.2.2.2. Returns
The DissectorTable
10.4.6.2.3. dissectortable:add(pattern, dissector)
Add a dissector to a table.
10.4.6.2.3.1. Arguments
pattern
The pattern to match (either an integer or a string depending on the table's type).
dissector
The dissector to add (either an Proto or a Dissector).
10.4.6.2.4. dissectortable:remove(pattern, dissector)
Remove a dissector from a table
10.4.6.2.4.1. Arguments
pattern
The pattern to match (either an integer or a string depending on the table's type).
dissector
The dissector to add (either an Proto or a Dissector).
10.4.6.2.5. dissectortable:try(pattern, tvb, pinfo, tree)
Try to call a dissector from a table
10.4.6.2.5.1. Arguments
pattern
The pattern to be matched (either an integer or a string depending on the table's type).
tvb
The buffer to dissect
pinfo
The packet info
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tree
The tree on which to add the protocol items
10.4.6.2.6. dissectortable:get_dissector(pattern)
Try to obtain a dissector from a table.
10.4.6.2.6.1. Arguments
pattern
The pattern to be matched (either an integer or a string depending on the table's type).
10.4.6.2.6.2. Returns
The dissector handle if found
nil if not found
10.4.6.3. Pref
A preference of a Protocol.
10.4.6.3.1. Pref.bool(label, default, descr)
Creates a boolean preference to be added to a Protocol's prefs table.
10.4.6.3.1.1. Arguments
label
The Label (text in the right side of the preference input) for this preference
default
The default value for this preference
descr
A description of what this preference is
10.4.6.3.2. Pref.uint(label, default, descr)
Creates an (unsigned) integer preference to be added to a Protocol's prefs table.
10.4.6.3.2.1. Arguments
label
The Label (text in the right side of the preference input) for this preference
default
The default value for this preference
descr
A description of what this preference is
10.4.6.3.3. Pref.string(label, default, descr)
Creates a string preference to be added to a Protocol's prefs table.
10.4.6.3.3.1. Arguments
label
The Label (text in the right side of the preference input) for this preference
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default
The default value for this preference
descr
A description of what this preference is
10.4.6.3.4. Pref.enum(label, default, descr, enum, radio)
Creates an enum preference to be added to a Protocol's prefs table.
10.4.6.3.4.1. Arguments
label
The Label (text in the right side of the preference input) for this preference
default
The default value for this preference
descr
A description of what this preference is
enum
A enum table
radio
Radio button (true) or Combobox (false)
10.4.6.3.5. Pref.range(label, default, descr, range, max)
Creates a range preference to be added to a Protocol's prefs table.
10.4.6.3.5.1. Arguments
label
The Label (text in the right side of the preference input) for this preference
default
The default value for this preference
descr
A description of what this preference is
range
The range
max
The maximum value
10.4.6.3.6. Pref.statictext(label, descr)
Creates a static text preference to be added to a Protocol's prefs table.
10.4.6.3.6.1. Arguments
label
The static text
descr
The static text description
10.4.6.4. Prefs
The table of preferences of a protocol
10.4.6.4.1. prefs:__newindex(name, pref)
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Creates a new preference
10.4.6.4.1.1. Arguments
name
The abbreviation of this preference
pref
A valid but still unassigned Pref object
10.4.6.4.1.2. Errors
•
Unknow Pref type
10.4.6.4.2. prefs:__index(name)
Get the value of a preference setting
10.4.6.4.2.1. Arguments
name
The abbreviation of this preference
10.4.6.4.2.2. Returns
The current value of the preference
10.4.6.4.2.3. Errors
•
Unknow Pref type
10.4.6.5. Proto
A new protocol in wireshark. Protocols have more uses, the main one is to dissect a protocol. But they
can be just dummies used to register preferences for other purposes.
10.4.6.5.1. Proto.new(name, desc)
10.4.6.5.1.1. Arguments
name
The name of the protocol
desc
A Long Text description of the protocol (usually lowercase)
10.4.6.5.1.2. Returns
The newly created protocol
10.4.6.5.2. proto.dissector
The protocol's dissector, a function you define
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10.4.6.5.3. proto.fields
The Fields Table of this dissector
10.4.6.5.4. proto.prefs
The preferences of this dissector
10.4.6.5.5. proto.init
The init routine of this dissector, a function you define
10.4.6.5.6. proto.name
The name given to this dissector
10.4.6.6. ProtoField
A Protocol field (to be used when adding items to the dissection tree)
10.4.6.6.1. ProtoField.new(name, abbr, type, [valuestring], [base], [mask], [descr])
Creates a new field to be used in a protocol.
10.4.6.6.1.1. Arguments
name
Actual name of the field (the string that appears in the tree).
abbr
Filter name of the field (the string that is used in filters).
type
Field Type (FT_*).
valuestring (optional)
A ValueString object.
base (optional)
The representation BASE_*.
mask (optional)
The bitmask to be used.
descr (optional)
The description of the field.
10.4.6.6.1.2. Returns
The newly created ProtoField object
10.4.6.6.2. ProtoField.uint8(abbr, [name], [base], [valuestring], [mask], [desc])
10.4.6.6.2.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
base (optional)
One of base.DEC, base.HEX or base.OCT
valuestring (optional)
A table containing the text that corresponds to the values
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mask (optional)
Integer mask of this field
desc (optional)
Description of the field
10.4.6.6.2.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.3. ProtoField.uint16(abbr, [name], [base], [valuestring], [mask], [desc])
10.4.6.6.3.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
base (optional)
One of base.DEC, base.HEX or base.OCT
valuestring (optional)
A table containing the text that corresponds to the values
mask (optional)
Integer mask of this field
desc (optional)
Description of the field
10.4.6.6.3.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.4. ProtoField.uint24(abbr, [name], [base], [valuestring], [mask], [desc])
10.4.6.6.4.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
base (optional)
One of base.DEC, base.HEX or base.OCT
valuestring (optional)
A table containing the text that corresponds to the values
mask (optional)
Integer mask of this field
desc (optional)
Description of the field
10.4.6.6.4.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.5. ProtoField.uint32(abbr, [name], [base], [valuestring], [mask], [desc])
10.4.6.6.5.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
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name (optional)
Actual name of the field (the string that appears in the tree)
base (optional)
One of base.DEC, base.HEX or base.OCT
valuestring (optional)
A table containing the text that corresponds to the values
mask (optional)
Integer mask of this field
desc (optional)
Description of the field
10.4.6.6.5.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.6. ProtoField.uint64(abbr, [name], [base], [valuestring], [mask], [desc])
10.4.6.6.6.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
base (optional)
One of base.DEC, base.HEX or base.OCT
valuestring (optional)
A table containing the text that corresponds to the values
mask (optional)
Integer mask of this field
desc (optional)
Description of the field
10.4.6.6.6.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.7. ProtoField.int8(abbr, [name], [base], [valuestring], [mask], [desc])
10.4.6.6.7.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
base (optional)
One of base.DEC, base.HEX or base.OCT
valuestring (optional)
A table containing the text that corresponds to the values
mask (optional)
Integer mask of this field
desc (optional)
Description of the field
10.4.6.6.7.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.8. ProtoField.int16(abbr, [name], [base], [valuestring], [mask], [desc])
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10.4.6.6.8.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
base (optional)
One of base.DEC, base.HEX or base.OCT
valuestring (optional)
A table containing the text that corresponds to the values
mask (optional)
Integer mask of this field
desc (optional)
Description of the field
10.4.6.6.8.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.9. ProtoField.int24(abbr, [name], [base], [valuestring], [mask], [desc])
10.4.6.6.9.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
base (optional)
One of base.DEC, base.HEX or base.OCT
valuestring (optional)
A table containing the text that corresponds to the values
mask (optional)
Integer mask of this field
desc (optional)
Description of the field
10.4.6.6.9.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.10. ProtoField.int32(abbr, [name], [base], [valuestring], [mask], [desc])
10.4.6.6.10.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
base (optional)
One of base.DEC, base.HEX or base.OCT
valuestring (optional)
A table containing the text that corresponds to the values
mask (optional)
Integer mask of this field
desc (optional)
Description of the field
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10.4.6.6.10.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.11. ProtoField.int64(abbr, [name], [base], [valuestring], [mask], [desc])
10.4.6.6.11.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
base (optional)
One of base.DEC, base.HEX or base.OCT
valuestring (optional)
A table containing the text that corresponds to the values
mask (optional)
Integer mask of this field
desc (optional)
Description of the field
10.4.6.6.11.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.12. ProtoField.framenum(abbr, [name], [base], [valuestring], [mask],
[desc])
A frame number (for hyperlinks between frames)
10.4.6.6.12.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
base (optional)
One of base.DEC, base.HEX or base.OCT
valuestring (optional)
A table containing the text that corresponds to the values
mask (optional)
Integer mask of this field
desc (optional)
Description of the field
10.4.6.6.12.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.13. ProtoField.ipv4(abbr, [name], [desc])
10.4.6.6.13.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
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desc (optional)
Description of the field
10.4.6.6.13.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.14. ProtoField.ipv6(abbr, [name], [desc])
10.4.6.6.14.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
desc (optional)
Description of the field
10.4.6.6.14.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.15. ProtoField.ether(abbr, [name], [desc])
10.4.6.6.15.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
desc (optional)
Description of the field
10.4.6.6.15.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.16. ProtoField.float(abbr, [name], [desc])
10.4.6.6.16.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
desc (optional)
Description of the field
10.4.6.6.16.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.17. ProtoField.double(abbr, [name], [desc])
10.4.6.6.17.1. Arguments
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abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
desc (optional)
Description of the field
10.4.6.6.17.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.18. ProtoField.string(abbr, [name], [desc])
10.4.6.6.18.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
desc (optional)
Description of the field
10.4.6.6.18.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.19. ProtoField.stringz(abbr, [name], [desc])
10.4.6.6.19.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
desc (optional)
Description of the field
10.4.6.6.19.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.20. ProtoField.bytes(abbr, [name], [desc])
10.4.6.6.20.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
desc (optional)
Description of the field
10.4.6.6.20.2. Returns
A protofield item to be added to a ProtoFieldArray
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10.4.6.6.21. ProtoField.ubytes(abbr, [name], [desc])
10.4.6.6.21.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
desc (optional)
Description of the field
10.4.6.6.21.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.22. ProtoField.guid(abbr, [name], [desc])
10.4.6.6.22.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
desc (optional)
Description of the field
10.4.6.6.22.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.23. ProtoField.oid(abbr, [name], [desc])
10.4.6.6.23.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
desc (optional)
Description of the field
10.4.6.6.23.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.6.24. ProtoField.bool(abbr, [name], [desc])
10.4.6.6.24.1. Arguments
abbr
Abbreviated name of the field (the string used in filters)
name (optional)
Actual name of the field (the string that appears in the tree)
desc (optional)
Description of the field
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10.4.6.6.24.2. Returns
A protofield item to be added to a ProtoFieldArray
10.4.6.7. Non Method Functions
10.4.6.7.1. register_postdissector(proto)
Make a protocol (with a dissector) a postdissector. It will be called for every frame after dissection
10.4.6.7.1.1. Arguments
proto
the protocol to be used as postdissector
10.4.7. Adding information to the dissection tree
10.4.7.1. TreeItem
TreeItems represent information in the packet-details pane. A root TreeItem is passed to dissectors as
first argument.
10.4.7.1.1. treeitem:add()
Adds an child item to a given item, returning the child. tree_item:add([proto_field | proto], [tvbrange],
[label], ...) if the proto_field represents a numeric value (int, uint or float) is to be treated as a Big Endian (network order) Value.
10.4.7.1.1.1. Returns
The child item
10.4.7.1.2. treeitem:add_le()
Adds (and returns) an child item to a given item, returning the child. tree_item:add([proto_field | proto],
[tvbrange], [label], ...) if the proto_field represents a numeric value (int, uint or float) is to be treated as a
Little Endian Value.
10.4.7.1.2.1. Returns
The child item
10.4.7.1.3. treeitem:set_text(text)
Sets the text of the label
10.4.7.1.3.1. Arguments
text
The text to be used.
10.4.7.1.4. treeitem:append_text(text)
Appends text to the label
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10.4.7.1.4.1. Arguments
text
The text to be appended.
10.4.7.1.5. treeitem:set_expert_flags([group], [severity])
Sets the expert flags of the item.
10.4.7.1.5.1. Arguments
group (optional)
One of PI_CHECKSUM, PI_SEQUENCE, PI_RESPONSE_CODE,
PI_REQUEST_CODE,
PI_UNDECODED,
PI_REASSEMBLE,
PI_MALFORMED or PI_DEBUG
severity (optional)
One of PI_CHAT, PI_NOTE, PI_WARN, PI_ERROR
10.4.7.1.6. treeitem:add_expert_info([group], [severity], [text])
Sets the expert flags of the item and adds expert info to the packet.
10.4.7.1.6.1. Arguments
group (optional)
One of PI_CHECKSUM, PI_SEQUENCE, PI_RESPONSE_CODE,
PI_REQUEST_CODE,
PI_UNDECODED,
PI_REASSEMBLE,
PI_MALFORMED or PI_DEBUG
severity (optional)
One of PI_CHAT, PI_NOTE, PI_WARN, PI_ERROR
text (optional)
The text for the expert info
10.4.7.1.7. treeitem:set_generated()
Marks the TreeItem as a generated field (with data infered but not contained in the packet).
10.4.7.1.8. treeitem:set_hidden()
Should not be used
10.4.8. Functions for handling packet data
10.4.8.1. ByteArray
10.4.8.1.1. ByteArray.new([hexbytes])
Creates a ByteArray Object
10.4.8.1.1.1. Arguments
hexbytes (optional)
A string consisting of hexadecimal bytes like "00 B1 A2" or "1a2b3c4d"
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10.4.8.1.1.2. Returns
The new ByteArray object.
10.4.8.1.2. bytearray:__concat(first, second)
Concatenate two ByteArrays
10.4.8.1.2.1. Arguments
first
First array
second
Second array
10.4.8.1.2.2. Returns
The new composite ByteArray.
10.4.8.1.2.3. Errors
•
Both arguments must be ByteArrays
10.4.8.1.3. bytearray:prepend(prepended)
Prepend a ByteArray to this ByteArray
10.4.8.1.3.1. Arguments
prepended
Array to be prepended
10.4.8.1.3.2. Errors
•
Both arguments must be ByteArrays
10.4.8.1.4. bytearray:append(appended)
Append a ByteArray to this ByteArray
10.4.8.1.4.1. Arguments
appended
Array to be appended
10.4.8.1.4.2. Errors
•
Both arguments must be ByteArrays
10.4.8.1.5. bytearray:set_size(size)
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Lua Support in Wireshark
Sets the size of a ByteArray, either truncating it or filling it with zeros.
10.4.8.1.5.1. Arguments
size
New size of the array
10.4.8.1.5.2. Errors
•
ByteArray size must be non-negative
10.4.8.1.6. bytearray:set_index(index, value)
Sets the value of an index of a ByteArray.
10.4.8.1.6.1. Arguments
index
The position of the byte to be set
value
The char value to set [0-255]
10.4.8.1.7. bytearray:get_index(index)
Set the value of a byte in a ByteArray
10.4.8.1.7.1. Arguments
index
The position of the byte to be set
10.4.8.1.7.2. Returns
The value [0-255] of the byte.
10.4.8.1.8. bytearray:len()
Obtain the length of a ByteArray
10.4.8.1.8.1. Returns
The length of the ByteArray.
10.4.8.1.9. bytearray:subset(offset, length)
Obtain a segment of a ByteArray
10.4.8.1.9.1. Arguments
offset
The position of the first byte
length
The length of the segment
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10.4.8.1.9.2. Returns
A ByteArray contaning the requested segment.
A string contaning a representaion of the ByteArray.
10.4.8.2. Int
Int64 represents a 64 bit integer. Lua uses one single number representation which can be chosen at
compile time and since it is often set to IEEE 754 double precision floating point, we cannot store a 64
bit integer with full precision. For details, see: http://lua-users.org/wiki/FloatingPoint
10.4.8.3. Tvb
A Tvb represents the packet's buffer. It is passed as an argument to listeners and dissectors, and can be
used to extract information (via TvbRange) from the packet's data. Beware that Tvbs are usable only by
the current listener or dissector call and are destroyed as soon as the listener/dissector returns, so references to them are unusable once the function has returned. To create a tvbrange the tvb must be called
with offset and length as optional arguments ( the offset defaults to 0 and the length to tvb:len() )
10.4.8.3.1. Tvb.new_real(bytearray, name)
Creates a new Tvb from a bytearray (it gets added to the current frame too)
10.4.8.3.1.1. Arguments
bytearray
The data source for this Tvb.
name
The name to be given to the new data-source.
10.4.8.3.1.2. Returns
The created Tvb.
10.4.8.3.2. Tvb.tvb(range)
Creates a (sub)Tvb from using a TvbRange
10.4.8.3.2.1. Arguments
range
The TvbRange from which to create the new Tvb.
10.4.8.3.3. tvb:__tostring()
Convert the bytes of a Tvb into a string, to be used for debugging purposes as '...' will be appended in
case the string is too long.
10.4.8.3.3.1. Returns
The string.
10.4.8.3.4. tvb:len()
Obtain the length of a TVB
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10.4.8.3.4.1. Returns
The length of the Tvb.
10.4.8.3.5. tvb:offset()
Returns the raw offset (from the beginning of the source Tvb) of a sub Tvb.
10.4.8.3.5.1. Returns
The raw offset of the Tvb.
10.4.8.3.6. tvb:__call()
Equivalent to tvb:range(...)
10.4.8.4. TvbRange
A TvbRange represents an usable range of a Tvb and is used to extract data from the Tvb that generated
it TvbRanges are created by calling a tvb (e.g. tvb(offset,length)). If the TvbRange span is outside the
Tvb's range the creation will cause a runtime error.
10.4.8.4.1. tvb:range([offset], [length])
Creates a tvbr from this Tvb. This is used also as the Tvb:__call() metamethod.
10.4.8.4.1.1. Arguments
offset (optional)
The offset (in octets) from the begining of the Tvb. Defaults to 0.
length (optional)
The length (in octets) of the range. Defaults to until the end of the Tvb.
10.4.8.4.1.2. Returns
The TvbRange
10.4.8.4.2. tvbrange:uint()
Get a Big Endian (network order) unsigned integer from a TvbRange. The range must be 1, 2, 3 or 4 octets long.
10.4.8.4.2.1. Returns
The unsigned integer value
10.4.8.4.3. tvbrange:le_uint()
Get a Little Endian unsigned integer from a TvbRange. The range must be 1, 2, 3 or 4 octets long.
10.4.8.4.3.1. Returns
The unsigned integer value
10.4.8.4.4. tvbrange:uint64()
Get a Big Endian (network order) unsigned 64 bit integer from a TvbRange. The range must be 1-8 oct248
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ets long.
10.4.8.4.5. tvbrange:le_uint64()
Get a Little Endian unsigned 64 bit integer from a TvbRange. The range must be 1-8 octets long.
10.4.8.4.6. tvbrange:float()
Get a Big Endian (network order) floating point number from a TvbRange. The range must be 4 or 8
octets long.
10.4.8.4.6.1. Returns
The flaoting point value
10.4.8.4.7. tvbrange:le_float()
Get a Little Endian floating point number from a TvbRange. The range must be 4 or 8 octets long.
10.4.8.4.7.1. Returns
The flaoting point value
10.4.8.4.8. tvbrange:ipv4()
Get an IPv4 Address from a TvbRange.
10.4.8.4.8.1. Returns
The IPv4 Address
10.4.8.4.9. tvbrange:le_ipv4()
Get an Little Endian IPv4 Address from a TvbRange.
10.4.8.4.9.1. Returns
The IPv4 Address
10.4.8.4.10. tvbrange:ether()
Get an Ethernet Address from a TvbRange.
10.4.8.4.10.1. Returns
The Ethernet Address
10.4.8.4.10.2. Errors
•
The range must be 6 bytes long
10.4.8.4.11. tvbrange:string()
Obtain a string from a TvbRange
10.4.8.4.11.1. Returns
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Lua Support in Wireshark
The string
10.4.8.4.12. tvbrange:bytes()
Obtain a ByteArray
10.4.8.4.12.1. Returns
The ByteArray
10.4.8.4.13. tvbrange:len()
Obtain the length of a TvbRange
10.4.8.4.14. tvbrange:offset()
Obtain the offset in a TvbRange
10.4.8.4.15. tvbrange:__tostring()
Converts the TvbRange into a string. As the string gets truncated you should use this only for debugging
purposes or if what you want is to have a truncated string in the format 67:89:AB:...
10.4.8.5. UInt
Int64 represents a 64 bit integer.
10.4.9. Utility Functions
10.4.9.1. Dir
A Directory
10.4.9.1.1. Dir.open(pathname, [extension])
Usage: for filename in Dir.open(path) do ... end
10.4.9.1.1.1. Arguments
pathname
The pathname of the directory
extension (optional)
If given, only file with this extension will be returned
10.4.9.1.1.2. Returns
the Dir object
10.4.9.1.2. dir:__call()
At every invocation will return one file (nil when done)
10.4.9.1.3. dir:close()
Closes the directory
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10.4.9.2. Non Method Functions
10.4.9.2.1. format_date(timestamp)
Formats an absolute timestamp into a human readable date
10.4.9.2.1.1. Arguments
timestamp
A timestamp value to convert.
10.4.9.2.1.2. Returns
A string with the formated date
10.4.9.2.2. format_time(timestamp)
Formats a relative timestamp in a human readable form
10.4.9.2.2.1. Arguments
timestamp
A timestamp value to convert
10.4.9.2.2.2. Returns
A string with the formated time
10.4.9.2.3. report_failure(text)
Reports a failure to the user
10.4.9.2.3.1. Arguments
text
Message
10.4.9.2.4. critical(...)
Will add a log entry with critical severity
10.4.9.2.4.1. Arguments
...
objects to be printed
10.4.9.2.5. warn(...)
Will add a log entry with warn severity
10.4.9.2.5.1. Arguments
...
objects to be printed
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10.4.9.2.6. message(...)
Will add a log entry with message severity
10.4.9.2.6.1. Arguments
...
objects to be printed
10.4.9.2.7. info(...)
Will add a log entry with info severity
10.4.9.2.7.1. Arguments
...
objects to be printed
10.4.9.2.8. debug(...)
Will add a log entry with debug severity
10.4.9.2.8.1. Arguments
...
objects to be printed
10.4.9.2.9. loadfile(filename)
Lua's loadfile() has been modified so that if a file does not exist in the current directory it will look for it
in wireshark's user and system directories
10.4.9.2.9.1. Arguments
filename
Name of the file to be loaded
10.4.9.2.10. dofile(filename)
Lua's dofile() has been modified so that if a file does not exist in the current directory it will look for it
in wireshark's user and system directories
10.4.9.2.10.1. Arguments
filename
Name of the file to be run
10.4.9.2.11. persconffile_path([filename])
10.4.9.2.11.1. Arguments
filename (optional)
A filename
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10.4.9.2.11.2. Returns
The full pathname for a file in the personal configuration directory
10.4.9.2.12. datafile_path([filename])
10.4.9.2.12.1. Arguments
filename (optional)
A filename
10.4.9.2.12.2. Returns
The full pathname for a file in wireshark's configuration directory
10.4.9.2.13. register_stat_cmd_arg(argument, [action])
Register a function to handle a -z option
10.4.9.2.13.1. Arguments
argument
Argument
action (optional)
Action
253
Lua Support in Wireshark
254
Appendix A. Files and Folders
A.1. Capture Files
To understand which information will remain available after the captured packets are saved to a capture
file, it's helpful to know a bit about the capture file contents.
Wireshark uses the libpcap file format as the default format to save captured packets; this format has existed for a long time and it's pretty simple. However, it has some drawbacks: it's not extensible and lacks
some information that would be really helpful (e.g. being able to add a comment to a packet such as "the
problems start here" would be really nice).
In addition to the libpcap format, Wireshark supports several different capture file formats. However,
the problems described above also applies for these formats.
A new capture file format "PCAP Next Generation Dump File Format" is currently under development,
which will fix these drawbacks. However, it still might take a while until the new file format is ready
and Wireshark can use it.
A.1.1. Libpcap File Contents
At the start of each libpcap capture file some basic information is stored like a magic number to identify
the libpcap file format. The most interesting information of this file start is the link layer type (Ethernet,
Token Ring, ...).
The following data is saved for each packet:
•
the timestamp with millisecond resolution
•
the packet length as it was "on the wire"
•
the packet length as it's saved in the file
•
the packet's raw bytes
A detailed description of the libpcap file format can be found at: http://wiki.wireshark.org/Development/
LibpcapFileFormat
A.1.2. Not Saved in the Capture File
Probably even more interesting for everyday Wireshark usage is to know the things that are not saved in
the capture file:
•
current selections (selected packet, ...)
•
name resolution information, see Section 7.7, “Name Resolution” for details
Warning!
The name resolution information is rebuilt each time Wireshark is restarted so this information might even change when the capture file is reopened on the same machine
later!
255
Files and Folders
•
the number of packets dropped while capturing
•
packet marks set with "Edit/Mark Packet"
•
time references set with "Edit/Time Reference"
•
the current display filter
•
...
256
Files and Folders
A.2. Configuration Files and Folders
Wireshark uses a number of files and folders while it is running. Some of these reside in the personal
configuration folder and are used to maintain information between runs of Wireshark, while some of
them are maintained in system areas.
Tip
A list of the folders Wireshark actually uses can be found under the Folders tab in the dialog box shown when you select About Wireshark from the Help menu.
The content format of the configuration files is the same on all platforms. However, to match the different policies for Unix and Windows platforms, different folders are used for these files.
Table A.1. Configuration files and folders overview
File/Folder
Description
Unix/Linux
folders
Windows folders
preferences
Settings from the /
%WIRESHARK%\wireshark.conf,
Preferences dialog etc/wire%APPDATA%\Wireshark\preferences
box.
shark.conf,
$HOME/.wireshar
k/preferences
recent
Recent GUI set- $HOME/.wireshar %APPDATA%\Wireshark\recent
tings (e.g. recent k/recent
files lists).
cfilters
Capture filters.
$HOME/.wireshar %WIRESHARK%\cfilters,
k/cfilters
%APPDATA%\Wireshark\cfilters
dfilters
Display filters.
$HOME/.wireshar %WIRESHARK%\dfilters,
k/dfilters
%APPDATA%\Wireshark\dfilters
colorfilters
Coloring rules.
$HOME/.wireshar %WIRESHARK%\colorfilters,
k/colorfilters
%APPDATA%\Wireshark\colorfilters
disabled_protos
Disabled
cols.
ethers
Ethernet name res- /etc/ethers,
%WIRESHARK%\ethers,
olution.
$HOME/.wireshar %APPDATA%\Wireshark\ethers
k/ethers
manuf
Ethernet name res- /etc/manuf,
%WIRESHARK%\manuf,
olution.
$HOME/.wireshar %APPDATA%\Wireshark\manuf
k/manuf
hosts
IPv4 and IPv6 /etc/hosts,
%WIRESHARK%\hosts,
name resolution. $HOME/.wireshar %APPDATA%\Wireshark\hosts
k/hosts
services
Network services. /etc/services,
%WIRESHARK%\services,
$HOME/.wireshar %APPDATA%\Wireshark\services
k/services
subnets
IPv4 subnet name /etc/subnets,
%WIRESHARK%\subnets,
resolution.
$HOME/.wireshar %APPDATA%\Wireshark\subnets
k/subnets
ipxnets
IPX name resolu- /etc/ipxnets,
proto- $HOME/.wireshar %WIRESHARK%\disabled_protos,
k/disabled_protos %APPDATA%\Wireshark\disabled_protos
257
%WIRESHARK%\ipxnets,
Files and Folders
File/Folder
Description
Unix/Linux
folders
Windows folders
tion.
$HOME/.wireshar %APPDATA%\Wireshark\ipxnets
k/ipxnets
plugins
Plugin directories. /
%WIRESHARK%\plugins\<version>,
usr/
%APPDATA%\Wireshark\plugins
share/wireshark/plugins,
/
usr/local/
share/wireshark/plugins,
$HOME/.wireshar
k/plugins
temp
Temporary files.
Environment:
TMPDIR
Environment: TMPDIR or TEMP
Windows folders
%APPDATA% points to the personal configuration folder, e.g.: C:\Documents and
Settings\<username>\Application Data (details can be found at: Section A.3.1, “Windows profiles”),
%WIRESHARK% points to the Wireshark program folder, e.g.: C:\Program
Files\Wireshark
Unix/Linux folders
The /etc folder is the global Wireshark configuration folder. The folder actually used on
your system may vary, maybe something like: /usr/local/etc.
$HOME is usually something like: /home/<username>
preferences/wireshark.conf
This file contains your Wireshark preferences, including defaults
for capturing and displaying packets. It is a simple text file containing statements of the form:
variable: value
The settings from this file are read in at program start and written
to disk when you press the Save button in the "Preferences" dialog box.
recent
This file contains various GUI related settings like the main window position and size, the recent files list and such. It is a simple
text file containing statements of the form:
variable: value
It is read at program start and written at program exit.
258
Files and Folders
cfilters
This file contains all the capture filters that you have defined and
saved. It consists of one or more lines, where each line has the
following format:
"<filter name>" <filter string>
The settings from this file are read in at program start and written
to disk when you press the Save button in the "Capture Filters"
dialog box.
dfilters
This file contains all the display filters that you have defined and
saved. It consists of one or more lines, where each line has the
following format:
"<filter name>" <filter string>
The settings from this file are read in at program start and written
to disk when you press the Save button in the "Display Filters"
dialog box.
colorfilters
This file contains all the color filters that you have defined and
saved. It consists of one or more lines, where each line has the
following format:
@<filter name>@<filter string>@[<bg RGB(16-bit)>][<fg RGB(16-bit)>]
The settings from this file are read in at program start and written
to disk when you press the Save button in the "Coloring Rules"
dialog box.
disabled_protos
Each line in this file specifies a disabled protocol name. The following are some examples:
tcp
udp
The settings from this file are read in at program start and written
to disk when you press the Save button in the "Enabled Protocols"
dialog box.
ethers
When Wireshark is trying to translate Ethernet hardware addresses to names, it consults the files listed in Table A.1,
“Configuration files and folders overview”. If an address is not
found
in
/etc/ethers,
Wireshark
looks
in
$HOME/.wireshark/ethers
Each line in these files consists of one hardware address and name
separated by whitespace. The digits of hardware addresses are
separated by colons (:), dashes (-) or periods(.). The following are
some examples:
ff-ff-ff-ff-ff-ff
c0-00-ff-ff-ff-ff
00.2b.08.93.4b.a1
259
Broadcast
TR_broadcast
Freds_machine
Files and Folders
The settings from this file are read in at program start and never
written by Wireshark.
manuf
Wireshark uses the files listed in Table A.1, “Configuration files
and folders overview” to translate the first three bytes of an Ethernet address into a manufacturers name. This file has the same
format as the ethers file, except addresses are three bytes long.
An example is:
00:00:01 Xerox
# XEROX CORPORATION
The settings from this file are read in at program start and never
written by Wireshark.
hosts
Wireshark uses the files listed in Table A.1, “Configuration files
and folders overview” to translate IPv4 and IPv6 addresses into
names.
This file has the same format as the usual /etc/hosts file on Unix
systems.
An example is:
# Comments must be prepended by the # sign!
192.168.0.1 homeserver
The settings from this file are read in at program start and never
written by Wireshark.
services
Wireshark uses the files listed in Table A.1, “Configuration files
and folders overview” to translate port numbers into names.
An example is:
mydns
mydns
5045/udp
5045/tcp
# My own Domain Name Server
# My own Domain Name Server
The settings from this file are read in at program start and never
written by Wireshark.
subnets
Wireshark uses the files listed in Table A.1, “Configuration files
and folders overview” to translate an IPv4 address into a subnet
name. If no exact match from the hosts file or from DNS is found,
Wireshark will attempt a partial match for the subnet of the address.
Each line of this file consists of an IPv4 address, a subnet mask
length separated only by a '/' and a name separated by whitespace.
While the address must be a full IPv4 address, any values beyond
the mask length are subsequently ignored.
An example is:
260
Files and Folders
# Comments must be prepended by the # sign!
192.168.0.0/24 ws_test_network
A partially matched name will be printed as "subnetname.remaining-address". For example, "192.168.0.1" under the
subnet above would be printed as "ws_test_network.1"; if the
mask length above had been 16 rather than 24, the printed address
would be "ws_test_network.0.1".
The settings from this file are read in at program start and never
written by Wireshark.
ipxnets
Wireshark uses the files listed in Table A.1, “Configuration files
and folders overview” to translate IPX network numbers into
names.
An example is:
C0.A8.2C.00
c0-a8-1c-00
00:00:BE:EF
110f
HR
CEO
IT_Server1
FileServer3
The settings from this file are read in at program start and never
written by Wireshark.
plugins folder
Wireshark searches for plugins in the directories listed in Table A.1, “Configuration files and folders overview”. They are
searched in the order listed.
temp folder
If you start a new capture and don't specify a filename for it,
Wireshark uses this directory to store that file; see Section 4.7,
“Capture files and file modes”.
261
Files and Folders
A.3. Windows folders
Here you will find some details about the folders used in Wireshark on different Windows versions.
As already mentioned, you can find the currently used folders in the About Wireshark dialog.
A.3.1. Windows profiles
Windows uses some special directories to store user configuration files which define the "user profile".
This can be confusing, as the default directory location changed from Windows version to version and
might also be different for English and internationalized versions of Windows.
Note!
If you've upgraded to a new Windows version, your profile might be kept in the former
location, so the defaults mentioned here might not apply.
The following guides you to the right place where to look for Wireshark's profile data.
Vista
C:\Users\<username>\AppData\Roaming\Wireshar
k
XP/2000
C:\Documents
and
Settings\<username>\Application Data, "Documents
and Settings" and "Application Data" might be internationalized.
NT 4 (no longer supported by
Wireshark)
C:\WINNT\Profiles\<username>\Application
Data\Wireshark
ME/98 - with enabled user profiles (no longer supported by
Wireshark)
In Windows ME and 98 you can enable separate user profiles. In
that
case,
something
like:
C:\windows\Profiles\<username>\Application
Data\Wireshark is used.
ME/98/95 (no longer supported
by Wireshark)
The default in Windows ME/98/95 is: all users work with the
same
profile,
which
is
located
at:
C:\windows\Application Data\Wireshark
A.3.2. Windows Vista/XP/2000/NT roaming profiles
The following will only be applicable if you are using roaming profiles. This might be the case, if you
work in a Windows domain environment (used in company networks). The configurations of all programs you use won't be saved on the local hard drive of the computer you are currently working on, but
on the domain server.
As Wireshark is using the correct places to store its profile data, your settings will travel with you, if you
logon to a different computer the next time.
There is an exception to this: The "Local Settings" folder in your profile data (typically something like:
C:\Documents and Settings\<username>\Local Settings) will not be transferred to
the domain server. This is the default for temporary capture files.
262
Files and Folders
A.3.3. Windows temporary folder
Wireshark uses the folder which is set by the TMPDIR or TEMP environment variable. This variable
will be set by the Windows installer.
Vista
XXX - could someone give information about this?
XP/2000
C:\Documents and Settings\<username>\Local Settings\Temp
NT 4
C:\TEMP
263
Files and Folders
264
Appendix B. Protocols and Protocol
Fields
Wireshark distinguishes between protocols (e.g. tcp) and protocol fields (e.g. tcp.port).
A comprehensive list of all
tp://www.wireshark.org/docs/dfref/
protocols
265
and
protocol
fields
can
be
found
at:
ht-
Appendix C. Wireshark Messages
Wireshark provides you with additional information generated out of the plain packet data or it may
need to indicate dissection problems. Messages generated by Wireshark are usually placed in [] parentheses.
C.1. Packet List Messages
These messages might appear in the packet list.
C.1.1. [Malformed Packet]
Malformed packet means that the protocol dissector can't dissect the contents of the packet any further.
There can be various reasons:
•
Wrong dissector: Wireshark erroneously has chosen the wrong protocol dissector for this packet.
This will happen e.g. if you are using a protocol not on its well known TCP or UDP port. You may
try Analyze|Decode As to circumvent this problem.
•
Packet not reassembled: The packet is longer than a single frame and it is not reassembled, see
Section 7.6, “Packet Reassembling” for further details.
•
Packet is malformed: The packet is actually wrong (malformed), meaning that a part of the packet
is just not as expected (not following the protocol specifications).
•
Dissector is buggy: The corresponding protocol dissector is simply buggy or still incomplete.
Any of the above is possible. You'll have to look into the specific situation to determine the reason. You
could disable the dissector by disabling the protocol on the Analyze menu and check how Wireshark displays the packet then. You could (if it's TCP) enable reassembly for TCP and the specific dissector (if
possible) in the Edit|Preferences menu. You could check the packet contents yourself by reading the
packet bytes and comparing it to the protocol specification. This could reveal a dissector bug. Or you
could find out that the packet is indeed wrong.
C.1.2. [Packet size limited during capture]
The packet size was limited during capture, see "Limit each packet to n bytes" at the Section 4.5, “The
"Capture Options" dialog box”. While dissecting, the current protocol dissector was simply running out
of packet bytes and had to give up. There's nothing else you can do now, except to repeat the whole capture process again with a higher (or no) packet size limitation.
266
Wireshark Messages
C.2. Packet Details Messages
These messages might appear in the packet details.
C.2.1. [Response in frame: 123]
The current packet is the request of a detected request/response pair. You can directly jump to the corresponding response packet just by double clicking on this message.
C.2.2. [Request in frame: 123]
Same as "Response in frame: 123" above, but the other way round.
C.2.3. [Time from request: 0.123 seconds]
The time between the request and the response packets.
C.2.4. [Stream setup by PROTOCOL (frame 123)]
The session control protocol (SDP, H225, etc) message which signaled the creation of this session. You
can directly jump to the corresponding packet just by double clicking on this message.
267
Wireshark Messages
268
Appendix D. Related command line
tools
D.1. Introduction
Besides the Wireshark GUI application, there are some command line tools which can be helpful for doing some more specialized things. These tools will be described in this chapter.
269
Related command line tools
D.2. tshark: Terminal-based Wireshark
TShark is a terminal oriented version of Wireshark designed for capturing and displaying packets when
an interactive user interface isn't necessary or available. It supports the same options as wireshark. For
more information on tshark, see the manual pages (man tshark).
270
Related command line tools
D.3. tcpdump: Capturing with tcpdump for
viewing with Wireshark
There are occasions when you want to capture packets using tcpdump rather than wireshark, especially
when you want to do a remote capture and do not want the network load associated with running Wireshark remotely (not to mention all the X traffic polluting your capture).
However, the default tcpdump parameters result in a capture file where each packet is truncated, because tcpdump, by default, only captures the first 68 bytes of each packet.
To ensure that you capture complete packets, use the following command:
tcpdump -i <interface> -s 1500 -w <some-file>
You will have to specify the correct interface and the name of a file to save into. In addition, you will
have to terminate the capture with ^C when you believe you have captured enough packets.
Note!
tcpdump is not part of the Wireshark distribution. You can get it from: http://www.tcpdump.org for various platforms.
271
Related command line tools
D.4. dumpcap: Capturing with dumpcap for
viewing with Wireshark
Dumpcap is a network traffic dump tool. It captures packet data from a live network and writes the
packets to a file. Dumpcap's native capture file format is libpcap format, which is also the format used
by Wireshark, tcpdump and various other tools.
Without any options set it will use the pcap library to capture traffic from the first available network interface and write the received raw packet data, along with the packets' time stamps into a libpcap file.
Packet capturing is performed with the pcap library. The capture filter syntax follows the rules of the
pcap library.
Example D.1. Help information available from dumpcap
dumpcap -h
Dumpcap 1.1.4
Capture network packets and dump them into a libpcap file.
See http://www.wireshark.org for more information.
Usage: dumpcap [options] ...
Capture interface:
-i <interface>
-f <capture filter>
-s <snaplen>
-p
-B <buffer size>
-y <link type>
-D
-L
-S
-M
Stop conditions:
-c <packet count>
-a <autostop cond.> ...
name or idx of interface (def: first non-loopback)
packet filter in libpcap filter syntax
packet snapshot length (def: 65535)
don't capture in promiscuous mode
size of kernel buffer (def: 1MB)
link layer type (def: first appropriate)
print list of interfaces and exit
print list of link-layer types of iface and exit
print statistics for each interface once every second
for -D, -L, and -S produce machine-readable output
stop after n
duration:NUM
filesize:NUM
files:NUM
packets (def: infinite)
- stop after NUM seconds
- stop this file after NUM KB
- stop after NUM files
Output (files):
-w <filename>
name of file to save (def: tempfile)
-b <ringbuffer opt.> ... duration:NUM - switch to next file after NUM secs
filesize:NUM - switch to next file after NUM KB
files:NUM - ringbuffer: replace after NUM files
-n
use pcapng format instead of pcap
Miscellaneous:
-v
print version information and exit
-h
display this help and exit
Example: dumpcap -i eth0 -a duration:60 -w output.pcap
"Capture network packets from interface eth0 until 60s passed into output.pcap"
Use Ctrl-C to stop capturing at any time.
272
Related command line tools
D.5. capinfos: Print information about capture
files
Included with Wireshark is a small utility called capinfos, which is a command-line utility to print information about binary capture files.
Example D.2. Help information available from capinfos
$ capinfos -h
Capinfos 1.1.4
Prints information about capture files.
See http://www.wireshark.org for more information.
Usage: capinfos [options] <infile> ...
General:
-t display the capture file type
-E display the capture file encapsulation
Size:
-c display the number of packets
-s display the size of the file (in bytes)
-d display the total length of all packets (in bytes)
Time:
-u display the capture duration (in seconds)
-a display the capture start time
-e display the capture end time
Statistic:
-y display
-i display
-z display
-x display
average
average
average
average
data rate (in bytes/sec)
data rate (in bits/sec)
packet size (in bytes)
packet rate (in packets/sec)
Miscellaneous:
-h display this help and exit
If no options are given the default is to display all infos
273
Related command line tools
D.6. editcap: Edit capture files
Included with Wireshark is a small utility called editcap, which is a command-line utility for working
with capture files. Its main function is to remove packets from capture files, but it can also be used to
convert capture files from one format to another, as well as to print information about capture files.
Example D.3. Help information available from editcap
$ editcap -h
Editcap 1.1.4
Edit and/or translate the format of capture files.
See http://www.wireshark.org for more information.
Usage: editcap [options] ... <infile> <outfile> [ <packet#>[-<packet#>] ... ]
<infile> and <outfile> must both be present.
A single packet or a range of packets can be selected.
Packet selection:
-r
-A <start time>
-B <stop time>
keep the selected packets; default is to delete them.
don't output packets whose timestamp is before the
given time (format as YYYY-MM-DD hh:mm:ss).
don't output packets whose timestamp is after the
given time (format as YYYY-MM-DD hh:mm:ss).
Duplicate packet removal:
-d
remove packet if duplicate (window == 5).
-D <dup window>
remove packet if duplicate; configurable <dup window>
Valid <dup window> values are 0 to 1000000.
NOTE: A <dup window> of 0 with -v (verbose option) is
useful to print MD5 hashes.
-w <dup time window>
remove packet if duplicate packet is found EQUAL TO OR
LESS THAN <dup time window> prior to current packet.
A <dup time window> is specified in relative seconds
(e.g. 0.000001).
NOTE: The use of the 'Duplicate packet removal' options with
other editcap options except -v may not always work as expected.
Specifically the -r and -t options will very likely NOT have the
desired effect if combined with the -d, -D or -w.
Packet manipulation:
-s <snaplen>
-C <choplen>
-t <time adjustment>
truncate each packet to max. <snaplen> bytes of data.
chop each packet at the end by <choplen> bytes.
adjust the timestamp of each packet;
<time adjustment> is in relative seconds (e.g. -0.5).
-E <error probability> set the probability (between 0.0 and 1.0 incl.)
that a particular packet byte will be randomly changed.
Output File(s):
-c <packets per file>
-i <seconds per file>
-F <capture type>
-T <encap type>
Miscellaneous:
-h
-v
split the packet output to different files
based on uniform packet counts
with a maximum of <packets per file> each.
split the packet output to different files
based on uniform time intervals
with a maximum of <seconds per file> each.
set the output file type; default is libpcap.
an empty "-F" option will list the file types.
set the output file encapsulation type;
default is the same as the input file.
an empty "-T" option will list the encapsulation types.
display this help and exit.
verbose output.
If -v is used with any of the 'Duplicate Packet
Removal' options (-d, -D or -w) then Packet lengths
and MD5 hashes are printed to standard-out.
$ editcap -F
editcap: option requires an argument -- F
274
Related command line tools
editcap: The available capture file types for "F":
libpcap - Wireshark/tcpdump/... - libpcap
nseclibpcap - Wireshark - nanosecond libpcap
modlibpcap - Modified tcpdump - libpcap
nokialibpcap - Nokia tcpdump - libpcap
rh6_1libpcap - RedHat 6.1 tcpdump - libpcap
suse6_3libpcap - SuSE 6.3 tcpdump - libpcap
5views - Accellent 5Views capture
dct2000 - Catapult DCT2000 trace (.out format)
nettl - HP-UX nettl trace
netmon1 - Microsoft NetMon 1.x
netmon2 - Microsoft NetMon 2.x
ngsniffer - NA Sniffer (DOS)
ngwsniffer_1_1 - NA Sniffer (Windows) 1.1
ngwsniffer_2_0 - NA Sniffer (Windows) 2.00x
niobserverv9 - Network Instruments Observer (V9)
lanalyzer - Novell LANalyzer
snoop - Sun snoop
rf5 - Tektronix K12xx 32-bit .rf5 format
visual - Visual Networks traffic capture
k12text - K12 text file
commview - TamoSoft CommView
pcapng - Wireshark - pcapng (experimental)
$ editcap -T
editcap: option requires an argument -- T
editcap: The available encapsulation types for "T":
ether - Ethernet
tr - Token Ring
slip - SLIP
ppp - PPP
fddi - FDDI
fddi-swapped - FDDI with bit-swapped MAC addresses
rawip - Raw IP
arcnet - ARCNET
arcnet_linux - Linux ARCNET
atm-rfc1483 - RFC 1483 ATM
linux-atm-clip - Linux ATM CLIP
lapb - LAPB
atm-pdus - ATM PDUs
atm-pdus-untruncated - ATM PDUs - untruncated
null - NULL
ascend - Lucent/Ascend access equipment
isdn - ISDN
ip-over-fc - RFC 2625 IP-over-Fibre Channel
ppp-with-direction - PPP with Directional Info
ieee-802-11 - IEEE 802.11 Wireless LAN
prism - IEEE 802.11 plus Prism II monitor mode header
ieee-802-11-radio - IEEE 802.11 Wireless LAN with radio information
ieee-802-11-radiotap - IEEE 802.11 plus radiotap WLAN header
ieee-802-11-avs - IEEE 802.11 plus AVS WLAN header
linux-sll - Linux cooked-mode capture
frelay - Frame Relay
frelay-with-direction - Frame Relay with Directional Info
chdlc - Cisco HDLC
ios - Cisco IOS internal
ltalk - Localtalk
pflog-old - OpenBSD PF Firewall logs, pre-3.4
hhdlc - HiPath HDLC
docsis - Data Over Cable Service Interface Specification
cosine - CoSine L2 debug log
whdlc - Wellfleet HDLC
sdlc - SDLC
tzsp - Tazmen sniffer protocol
enc - OpenBSD enc(4) encapsulating interface
pflog - OpenBSD PF Firewall logs
chdlc-with-direction - Cisco HDLC with Directional Info
bluetooth-h4 - Bluetooth H4
mtp2 - SS7 MTP2
mtp3 - SS7 MTP3
irda - IrDA
user0 - USER 0
user1 - USER 1
user2 - USER 2
user3 - USER 3
user4 - USER 4
user5 - USER 5
user6 - USER 6
user7 - USER 7
user8 - USER 8
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user9 - USER 9
user10 - USER 10
user11 - USER 11
user12 - USER 12
user13 - USER 13
user14 - USER 14
user15 - USER 15
symantec - Symantec Enterprise Firewall
ap1394 - Apple IP-over-IEEE 1394
bacnet-ms-tp - BACnet MS/TP
raw-icmp-nettl - Raw ICMP with nettl headers
raw-icmpv6-nettl - Raw ICMPv6 with nettl headers
gprs-llc - GPRS LLC
juniper-atm1 - Juniper ATM1
juniper-atm2 - Juniper ATM2
redback - Redback SmartEdge
rawip-nettl - Raw IP with nettl headers
ether-nettl - Ethernet with nettl headers
tr-nettl - Token Ring with nettl headers
fddi-nettl - FDDI with nettl headers
unknown-nettl - Unknown link-layer type with nettl headers
mtp2-with-phdr - MTP2 with pseudoheader
juniper-pppoe - Juniper PPPoE
gcom-tie1 - GCOM TIE1
gcom-serial - GCOM Serial
x25-nettl - X25 with nettl headers
k12 - K12 protocol analyzer
juniper-mlppp - Juniper MLPPP
juniper-mlfr - Juniper MLFR
juniper-ether - Juniper Ethernet
juniper-ppp - Juniper PPP
juniper-frelay - Juniper Frame-Relay
juniper-chdlc - Juniper C-HDLC
juniper-ggsn - Juniper GGSN
lapd - LAPD
dct2000 - Catapult DCT2000
ber - ASN.1 Basic Encoding Rules
juniper-vp - Juniper Voice PIC
usb - Raw USB packets
ieee-802-16-mac-cps - IEEE 802.16 MAC Common Part Sublayer
raw-telnet-nettl - Raw telnet with nettl headers
usb-linux - USB packets with Linux header
mpeg - MPEG
ppi - Per-Packet Information header
erf - Endace Record File
bluetooth-h4 - Bluetooth H4 with linux header
sita-wan - SITA WAN packets
sccp - SS7 SCCP
bluetooth-hci - Bluetooth without transport layer
ipmb - Intelligent Platform Management Bus
wpan - IEEE 802.15.4 Wireless PAN
x2e-xoraya - X2E Xoraya
flexray - FlexRay
lin - Local Interconnect Network
most - Media Oriented Systems Transport
can20b - Controller Area Network 2.0B
layer1-event - EyeSDN Layer 1 event
x2e-serial - X2E serial line capture
i2c - I2C
wpan-nonask-phy - IEEE 802.15.4 Wireless PAN non-ASK PHY
tnef - Transport-Neutral Encapsulation Format
usb-linux-mmap - USB packets with Linux header and padding
gsm_um - GSM Um Interface
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D.7. mergecap: Merging multiple capture files
into one
Mergecap is a program that combines multiple saved capture files into a single output file specified by
the -w argument. Mergecap knows how to read libpcap capture files, including those of tcpdump. In addition, Mergecap can read capture files from snoop (including Shomiti) and atmsnoop, LanAlyzer,
Sniffer (compressed or uncompressed), Microsoft Network Monitor, AIX's iptrace, NetXray, Sniffer
Pro, RADCOM's WAN/LAN analyzer, Lucent/Ascend router debug output, HP-UX's nettl, and the
dump output from Toshiba's ISDN routers. There is no need to tell Mergecap what type of file you are
reading; it will determine the file type by itself. Mergecap is also capable of reading any of these file
formats if they are compressed using gzip. Mergecap recognizes this directly from the file; the '.gz' extension is not required for this purpose.
By default, it writes the capture file in libpcap format, and writes all of the packets in the input capture
files to the output file. The -F flag can be used to specify the format in which to write the capture file; it
can write the file in libpcap format (standard libpcap format, a modified format used by some patched
versions of libpcap, the format used by Red Hat Linux 6.1, or the format used by SuSE Linux 6.3),
snoop format, uncompressed Sniffer format, Microsoft Network Monitor 1.x format, and the format
used by Windows-based versions of the Sniffer software.
Packets from the input files are merged in chronological order based on each frame's timestamp, unless
the -a flag is specified. Mergecap assumes that frames within a single capture file are already stored in
chronological order. When the -a flag is specified, packets are copied directly from each input file to the
output file, independent of each frame's timestamp.
If the -s flag is used to specify a snapshot length, frames in the input file with more captured data than
the specified snapshot length will have only the amount of data specified by the snapshot length written
to the output file. This may be useful if the program that is to read the output file cannot handle packets
larger than a certain size (for example, the versions of snoop in Solaris 2.5.1 and Solaris 2.6 appear to
reject Ethernet frames larger than the standard Ethernet MTU, making them incapable of handling gigabit Ethernet captures if jumbo frames were used).
If the -T flag is used to specify an encapsulation type, the encapsulation type of the output capture file
will be forced to the specified type, rather than being the type appropriate to the encapsulation type of
the input capture file. Note that this merely forces the encapsulation type of the output file to be the specified type; the packet headers of the packets will not be translated from the encapsulation type of the input capture file to the specified encapsulation type (for example, it will not translate an Ethernet capture
to an FDDI capture if an Ethernet capture is read and '-T fddi' is specified).
Example D.4. Help information available from mergecap
$ mergecap -h
Mergecap 1.1.4
Merge two or more capture files into one.
See http://www.wireshark.org for more information.
Usage: mergecap [options] -w <outfile>|- <infile> ...
Output:
-a
-s
-w
-F
-T
concatenate rather than merge files.
default is to merge based on frame timestamps.
<snaplen>
truncate packets to <snaplen> bytes of data.
<outfile>|set the output filename to <outfile> or '-' for stdout.
<capture type> set the output file type; default is libpcap.
an empty "-F" option will list the file types.
<encap type>
set the output file encapsulation type;
default is the same as the first input file.
an empty "-T" option will list the encapsulation types.
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Miscellaneous:
-h
-v
display this help and exit.
verbose output.
A simple example merging dhcp-capture.libpcap and imap-1.libpcap into outfile.libpcap is shown below.
Example D.5. Simple example of using mergecap
$ mergecap -w outfile.libpcap dhcp-capture.libpcap imap-1.libpcap
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Related command line tools
D.8. text2pcap: Converting ASCII hexdumps to
network captures
There may be some occasions when you wish to convert a hex dump of some network traffic into a libpcap file.
Text2pcap is a program that reads in an ASCII hex dump and writes the data described into a libpcapstyle capture file. text2pcap can read hexdumps with multiple packets in them, and build a capture file of
multiple packets. text2pcap is also capable of generating dummy Ethernet, IP and UDP headers, in order
to build fully processable packet dumps from hexdumps of application-level data only.
Text2pcap understands a hexdump of the form generated by od -A x -t x1. In other words, each byte is
individually displayed and surrounded with a space. Each line begins with an offset describing the position in the file. The offset is a hex number (can also be octal - see -o), of more than two hex digits. Here
is a sample dump that text2pcap can recognize:
000000
000008
000010
000018
000020
000028
000030
00
5a
03
ee
03
16
01
e0
a0
68
33
80
a2
01
1e
b9
00
0f
94
0a
0f
a7
12
00
19
04
00
19
05
08
00
08
00
03
03
6f
00
00
7f
00
50
80
00
46
0a
0f
10
00
11
10
00
2e
19
01
0c
01
........
........
........
........
........
........
........
There is no limit on the width or number of bytes per line. Also the text dump at the end of the line is ignored. Bytes/hex numbers can be uppercase or lowercase. Any text before the offset is ignored, including email forwarding characters '>'. Any lines of text between the bytestring lines is ignored. The offsets
are used to track the bytes, so offsets must be correct. Any line which has only bytes without a leading
offset is ignored. An offset is recognized as being a hex number longer than two characters. Any text
after the bytes is ignored (e.g. the character dump). Any hex numbers in this text are also ignored. An
offset of zero is indicative of starting a new packet, so a single text file with a series of hexdumps can be
converted into a packet capture with multiple packets. Multiple packets are read in with timestamps differing by one second each. In general, short of these restrictions, text2pcap is pretty liberal about reading
in hexdumps and has been tested with a variety of mangled outputs (including being forwarded through
email multiple times, with limited line wrap etc.)
There are a couple of other special features to note. Any line where the first non-whitespace character is
'#' will be ignored as a comment. Any line beginning with #TEXT2PCAP is a directive and options can
be inserted after this command to be processed by text2pcap. Currently there are no directives implemented; in the future, these may be used to give more fine grained control on the dump and the way it
should be processed e.g. timestamps, encapsulation type etc.
Text2pcap also allows the user to read in dumps of application-level data, by inserting dummy L2, L3
and L4 headers before each packet. Possiblities include inserting headers such as Ethernet, Ethernet +
IP, Ethernet + IP + UDP, or Ethernet + Ip + TCP before each packet. This allows Wireshark or any other
full-packet decoder to handle these dumps.
Example D.6. Help information available for text2pcap
$ text2pcap -h
Text2pcap 1.1.4
Generate a capture file from an ASCII hexdump of packets.
See http://www.wireshark.org for more information.
Usage: text2pcap [options] <infile> <outfile>
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Related command line tools
where
<infile> specifies input filename (use - for standard input)
<outfile> specifies output filename (use - for standard output)
Input:
-o hex|oct|dec
-t <timefmt>
Output:
-l <typenum>
-m <max-packet>
parse offsets as (h)ex, (o)ctal or (d)ecimal; default is hex.
treats the text before the packet as a date/time code;
the specified argument is a format string of the sort
supported by strptime.
Example: The time "10:15:14.5476" has the format code
"%H:%M:%S."
NOTE: The subsecond component delimiter must be given
(.) but no pattern is required; the remaining number
is assumed to be fractions of a second.
NOTE: Date/time fields from the current date/time are
used as the default for unspecified fields.
link-layer type number; default is 1 (Ethernet).
See the file net/bpf.h for list of numbers.
Use this option if your dump is a complete hex dump
of an encapsulated packet and you wish to specify
the exact type of encapsulation.
Example: -l 7 for ARCNet packets.
max packet length in output; default is 64000
Prepend dummy header:
-e <l3pid>
prepend dummy Ethernet II header with specified L3PID
(in HEX).
Example: -e 0x806 to specify an ARP packet.
-i <proto>
prepend dummy IP header with specified IP protocol
(in DECIMAL).
Automatically prepends Ethernet header as well.
Example: -i 46
-u <srcp>,<destp>
prepend dummy UDP header with specified
dest and source ports (in DECIMAL).
Automatically prepends Ethernet & IP headers as well.
Example: -u 1000 69 to make the packets look like TFTP/UDP packets.
-T <srcp>,<destp>
prepend dummy TCP header with specified
dest and source ports (in DECIMAL).
Automatically prepends Ethernet & IP headers as well.
Example: -T 50,60
-s <srcp>,<dstp>,<tag> prepend dummy SCTP header with specified
dest/source ports and verification tag (in DECIMAL).
Automatically prepends Ethernet & IP headers as well.
Example: -s 30,40,34
-S <srcp>,<dstp>,<ppi> prepend dummy SCTP header with specified
dest/source ports and verification tag 0.
Automatically prepends a dummy SCTP DATA
chunk header with payload protocol identifier ppi.
Example: -S 30,40,34
Miscellaneous:
-h
-d
-q
display this help and exit.
detailed debug of parser states.
generate no output at all (automatically turns off -d).
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D.9. idl2wrs: Creating dissectors from CORBA
IDL files
In an ideal world idl2wrs would be mentioned in the users guide in passing and documented in the developers guide. As the developers guide has not yet been completed it will be documented here.
D.9.1. What is it?
As you have probably guessed from the name, idl2wrs takes a user specified IDL file and attempts to
build a dissector that can decode the IDL traffic over GIOP. The resulting file is "C" code, that should
compile okay as a Wireshark dissector.
idl2wrs basically parses the data struct given to it by the omniidl compiler, and using the GIOP API
available in packet-giop.[ch], generates get_CDR_xxx calls to decode the CORBA traffic on the wire.
It consists of 4 main files.
README.idl2wrs
This document
wireshark_be.py
The main compiler backend
wireshark_gen.py
A helper class, that generates the C code.
idl2wrs
A simple shell script wrapper that the end user should use to generate the dissector from the IDL file(s).
D.9.2. Why do this?
It is important to understand what CORBA traffic looks like over GIOP/IIOP, and to help build a tool
that can assist in troubleshooting CORBA interworking. This was especially the case after seeing a lot of
discussions about how particular IDL types are represented inside an octet stream.
I have also had comments/feedback that this tool would be good for say a CORBA class when teaching
students what CORBA traffic looks like "on the wire".
It is also COOL to work on a great Open Source project such as the case with "Wireshark" ( http://www.wireshark.org )
D.9.3. How to use idl2wrs
To use the idl2wrs to generate Wireshark dissectors, you need the following:
Prerequisites to using idl2wrs
1.
Python must be installed. See http://python.org/
2.
omniidl from the the omniORB package must be available. See http://omniorb.sourceforge.net/
3.
Of course you need Wireshark installed to compile the code and tweak it if required. idl2wrs is part
of the standard Wireshark distribution
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Related command line tools
To use idl2wrs to generate an Wireshark dissector from an idl file use the following procedure:
Procedure for converting a CORBA idl file into a Wireshark dissector
1.
To write the C code to stdout.
idl2wrs
<your file.idl>
e.g.:
idl2wrs echo.idl
2.
To write to a file, just redirect the output.
idl2wrs echo.idl > packet-test-idl.c
You may wish to comment out the register_giop_user_module() code and that will leave you with
heuristic dissection.
If you don't want to use the shell script wrapper, then try steps 3 or 4 instead.
3.
To write the C code to stdout.
Usage: omniidl
-p ./ -b wireshark_be <your file.idl>
e.g.:
omniidl
4.
-p ./ -b wireshark_be echo.idl
To write to a file, just redirect the output.
omniidl
-p ./ -b wireshark_be echo.idl > packet-test-idl.c
You may wish to comment out the register_giop_user_module() code and that will leave you with
heuristic dissection.
5.
Copy the resulting C code to subdirectory epan/dissectors/ inside your Wireshark source directory.
cp packet-test-idl.c /dir/where/wireshark/lives/epan/dissectors/
The new dissector has to be added to Makefile.common in the same directory. Look for the declaration CLEAN_DISSECTOR_SRC and add the new dissector there. For example,
CLEAN_DISSECTOR_SRC = \
packet-2dparityfec.c
packet-3com-njack.c
...
\
\
becomes
CLEAN_DISSECTOR_SRC = \
packet-test-idl.c
packet-2dparityfec.c
packet-3com-njack.c
...
\
\
\
For the next steps, go up to the top of your Wireshark source directory.
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6.
Run configure
./configure (or ./autogen.sh)
7.
Compile the code
make
8.
Good Luck !!
D.9.4. TODO
1.
Exception code not generated (yet), but can be added manually.
2.
Enums not converted to symbolic values (yet), but can be added manually.
3.
Add command line options etc
4.
More I am sure :-)
D.9.5. Limitations
See the TODO list inside packet-giop.c
D.9.6. Notes
1.
The "-p ./" option passed to omniidl indicates that the wireshark_be.py and wireshark_gen.py are
residing in the current directory. This may need tweaking if you place these files somewhere else.
2.
If it complains about being unable to find some modules (e.g. tempfile.py), you may want to check
if PYTHONPATH is set correctly. On my Linux box, it is PYTHONPATH=/usr/lib/python2.4/
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284
Appendix E. This Document's License
(GPL)
As with the original licence and documentation distributed with Wireshark, this document is covered by
the GNU General Public Licence (GNU GPL).
If you haven't read the GPL before, please do so. It explains all the things that you are allowed to do
with this code and documentation.
GNU GENERAL PUBLIC LICENSE
Version 2, June 1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
Preamble
The licenses for most software are designed to take away your
freedom to share and change it. By contrast, the GNU General Public
License is intended to guarantee your freedom to share and change free
software--to make sure the software is free for all its users. This
General Public License applies to most of the Free Software
Foundation's software and to any other program whose authors commit to
using it. (Some other Free Software Foundation software is covered by
the GNU Library General Public License instead.) You can apply it to
your programs, too.
When we speak of free software, we are referring to freedom, not
price. Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it
in new free programs; and that you know you can do these things.
To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
distribute copies of the software, or if you modify it.
For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
you have. You must make sure that they, too, receive or can get the
source code. And you must show them these terms so they know their
rights.
We protect your rights with two steps: (1) copyright the software, and
(2) offer you this license which gives you legal permission to copy,
distribute and/or modify the software.
Also, for each author's protection and ours, we want to make certain
that everyone understands that there is no warranty for this free
software. If the software is modified by someone else and passed on, we
want its recipients to know that what they have is not the original, so
that any problems introduced by others will not reflect on the original
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Finally, any free program is threatened constantly by software
patents. We wish to avoid the danger that redistributors of a free
program will individually obtain patent licenses, in effect making the
program proprietary. To prevent this, we have made it clear that any
patent must be licensed for everyone's free use or not licensed at all.
The precise terms and conditions for copying, distribution and
modification follow.
GNU GENERAL PUBLIC LICENSE
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
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0. This License applies to any program or other work which contains
a notice placed by the copyright holder saying it may be distributed
under the terms of this General Public License. The "Program", below,
refers to any such program or work, and a "work based on the Program"
means either the Program or any derivative work under copyright law:
that is to say, a work containing the Program or a portion of it,
either verbatim or with modifications and/or translated into another
language. (Hereinafter, translation is included without limitation in
the term "modification".) Each licensee is addressed as "you".
Activities other than copying, distribution and modification are not
covered by this License; they are outside its scope. The act of
running the Program is not restricted, and the output from the Program
is covered only if its contents constitute a work based on the
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Whether that is true depends on what the Program does.
1. You may copy and distribute verbatim copies of the Program's
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conspicuously and appropriately publish on each copy an appropriate
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You may charge a fee for the physical act of transferring a copy, and
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In addition, mere aggregation of another work not based on the Program
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the scope of this License.
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under Section 2) in object code or executable form under the terms of
Sections 1 and 2 above provided that you also do one of the following:
a) Accompany it with the complete corresponding machine-readable
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b) Accompany it with a written offer, valid for at least three
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Each version is given a distinguishing version number. If the Program
specifies a version number of this License which applies to it and "any
later version", you have the option of following the terms and conditions
either of that version or of any later version published by the Free
Software Foundation. If the Program does not specify a version number of
this License, you may choose any version ever published by the Free Software
Foundation.
10. If you wish to incorporate parts of the Program into other free
programs whose distribution conditions are different, write to the author
to ask for permission. For software which is copyrighted by the Free
Software Foundation, write to the Free Software Foundation; we sometimes
make exceptions for this. Our decision will be guided by the two goals
of preserving the free status of all derivatives of our free software and
of promoting the sharing and reuse of software generally.
NO WARRANTY
11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS
TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
REPAIR OR CORRECTION.
12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.
END OF TERMS AND CONDITIONS
How to Apply These Terms to Your New Programs
If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.
To do so, attach the following notices to the
to attach them to the start of each source file
convey the exclusion of warranty; and each file
the "copyright" line and a pointer to where the
program. It is safest
to most effectively
should have at least
full notice is found.
<one line to give the program's name and a brief idea of what it does.>
Copyright (C) <year> <name of author>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
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This Document's License (GPL)
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
USA
Also add information on how to contact you by electronic and paper mail.
If the program is interactive, make it output a short notice like this
when it starts in an interactive mode:
Gnomovision version 69, Copyright (C) year name of author
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
This is free software, and you are welcome to redistribute it
under certain conditions; type `show c' for details.
The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License. Of course, the commands you use may
be called something other than `show w' and `show c'; they could even be
mouse-clicks or menu items--whatever suits your program.
You should also get your employer (if you work as a programmer) or your
school, if any, to sign a "copyright disclaimer" for the program, if
necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright interest in the program
`Gnomovision' (which makes passes at compilers) written by James Hacker.
<signature of Ty Coon>, 1 April 1989
Ty Coon, President of Vice
This General Public License does not permit incorporating your program into
proprietary programs. If your program is a subroutine library, you may
consider it more useful to permit linking proprietary applications with the
library. If this is what you want to do, use the GNU Library General
Public License instead of this License.
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