4 Note: This is just an ASCII snapshot of the faq and may not be up to
5 date. Please go to http://www.wireshark.org/faq.html for the up
6 to date version. The version of this snapshot can be found at
7 the end of this document.
14 1.1 What is Wireshark?
16 1.2 What's up with the name change? Is Wireshark a fork?
18 1.3 Where can I get help?
20 1.4 What kind of shark is Wireshark?
22 1.5 How is Wireshark pronounced, spelled and capitalized?
24 1.6 How much does Wireshark cost?
26 1.7 Can I use Wireshark commercially?
28 1.8 Can I use Wireshark as part of my commercial product?
30 1.9 What protocols are currently supported?
32 1.10 Are there any plans to support {your favorite protocol}?
34 1.11 Can Wireshark read capture files from {your favorite network
37 1.12 What devices can Wireshark use to capture packets?
39 1.13 Does Wireshark work on Windows Me?
41 1.14 Does Wireshark work on Windows XP?
43 2. Downloading Wireshark:
45 2.1 Why do I get an error when I try to run the Win32 installer?
47 3. Installing Wireshark:
49 3.1 I installed the Wireshark RPM (or other package); why did it
50 install TShark but not Wireshark?
52 4. Building Wireshark:
54 4.1 I have libpcap installed; why did the configure script not find
57 4.2 Why do I get the error
59 dftest_DEPENDENCIES was already defined in condition TRUE, which
60 implies condition HAVE_PLUGINS_TRUE
62 when I try to build Wireshark from SVN or a SVN snapshot?
64 4.3 Why does the linker fail with a number of "Output line too long."
65 messages followed by linker errors when I try to buil Wireshark?
67 4.4 When I try to build Wireshark on Solaris, why does the link fail
68 complaining that plugin_list is undefined?
70 4.5 When I try to build Wireshark on Windows, why does the build fail
71 because of conflicts between winsock.h and winsock2.h?
73 5. Starting Wireshark:
75 5.1 Why does Wireshark crash with a Bus Error when I try to run it on
78 5.2 When I run Wireshark on Windows NT, why does it die with a Dr.
79 Watson error, reporting an "Integer division by zero" exception, when I
82 5.3 When I try to run Wireshark, why does it complain about
83 sprint_realloc_objid being undefined?
85 5.4 When I try to run Wireshark on Windows, why does it fail to run
86 with a complaint that it can't find packet.dll?
88 5.5 I've installed Wireshark from Fink on Mac OS X; why is it very slow
91 6. Crashes and other fatal errors:
93 6.1 I have an XXX network card on my machine; if I try to capture on
94 it, why does my machine crash or reset itself?
96 6.2 Why does my machine crash or reset itself when I select "Start"
97 from the "Capture" menu or select "Preferences" from the "Edit" menu?
101 7.1 When I use Wireshark to capture packets, why do I see only packets
102 to and from my machine, or not see all the traffic I'm expecting to see
103 from or to the machine I'm trying to monitor?
105 7.2 When I capture with Wireshark, why can't I see any TCP packets
106 other than packets to and from my machine, even though another analyzer
107 on the network sees those packets?
109 7.3 Why am I only seeing ARP packets when I try to capture traffic?
111 7.4 Why am I not seeing any traffic when I try to capture traffic?
113 7.5 Can Wireshark capture on (my T1/E1 line, SS7 links, etc.)?
115 7.6 How do I put an interface into promiscuous mode?
117 7.7 I can set a display filter just fine; why don't capture filters
120 7.8 I'm entering valid capture filters; why do I still get "parse
123 7.9 How can I capture packets with CRC errors?
125 7.10 How can I capture entire frames, including the FCS?
127 7.11 I'm capturing packets on a machine on a VLAN; why don't the
128 packets I'm capturing have VLAN tags?
130 7.12 Why does Wireshark hang after I stop a capture?
132 8. Capturing packets on Windows:
134 8.1 I'm running Wireshark on Windows; why does some network interface
135 on my machine not show up in the list of interfaces in the "Interface:"
136 field in the dialog box popped up by "Capture->Start", and/or why does
137 Wireshark give me an error if I try to capture on that interface?
139 8.2 I'm running Wireshark on Windows; why do no network interfaces show
140 up in the list of interfaces in the "Interface:" field in the dialog
141 box popped up by "Capture->Start"?
143 8.3 I'm running Wireshark on Windows; why doesn't my serial port/ADSL
144 modem/ISDN modem show up in the list of interfaces in the "Interface:"
145 field in the dialog box popped up by "Capture->Start"?
147 8.4 I'm running Wireshark on Windows NT 4.0/Windows 2000/Windows
148 XP/Windows Server 2003; my machine has a PPP (dial-up POTS, ISDN, etc.)
149 interface, and it shows up in the "Interface" item in the "Capture
150 Options" dialog box. Why can no packets be sent on or received from
151 that network while I'm trying to capture traffic on that interface?
153 8.5 I'm running Wireshark on Windows 95/98/Me, on a machine with more
154 than one network adapter of the same type; why does Wireshark show all
155 of those adapters with the same name, not letting me use any of those
156 adapters other than the first one?
158 8.6 I'm running Wireshark on Windows; why am I not seeing any traffic
159 being sent by the machine running Wireshark?
161 8.7 When I capture on Windows in promiscuous mode, I can see packets
162 other than those sent to or from my machine; however, those packets
163 show up with a "Short Frame" indication, unlike packets to or from my
164 machine. What should I do to arrange that I see those packets in their
167 8.8 I'm capturing packets on {Windows 95, Windows 98, Windows Me}; why
168 are the time stamps on packets wrong?
170 8.9 I'm trying to capture 802.11 traffic on Windows; why am I not
173 8.10 I'm trying to capture 802.11 traffic on Windows; why am I seeing
174 packets received by the machine on which I'm capturing traffic, but not
175 packets sent by that machine?
177 8.11 I'm trying to capture Ethernet VLAN traffic on Windows, and I'm
178 capturing on a "raw" Ethernet device rather than a "VLAN interface", so
179 that I can see the VLAN headers; why am I seeing packets received by
180 the machine on which I'm capturing traffic, but not packets sent by
183 9. Capturing packets on UN*Xes:
185 9.1 I'm running Wireshark on a UNIX-flavored OS; why does some network
186 interface on my machine not show up in the list of interfaces in the
187 "Interface:" field in the dialog box popped up by "Capture->Start",
188 and/or why does Wireshark give me an error if I try to capture on that
191 9.2 I'm running Wireshark on a UNIX-flavored OS; why do no network
192 interfaces show up in the list of interfaces in the "Interface:" field
193 in the dialog box popped up by "Capture->Start"?
195 9.3 I'm capturing packets on Linux; why do the time stamps have only
196 100ms resolution, rather than 1us resolution?
198 10. Capturing packets on wireless LANs:
200 10.1 How can I capture raw 802.11 frames, including non-data
201 (management, beacon) frames?
203 10.2 How do I capture on an 802.11 device in monitor mode?
207 11.1 Why am I seeing lots of packets with incorrect TCP checksums?
209 11.2 I've just installed Wireshark, and the traffic on my local LAN is
210 boring. Where can I find more interesting captures?
212 11.3 Why doesn't Wireshark correctly identify RTP packets? It shows
215 11.4 Why doesn't Wireshark show Yahoo Messenger packets in captures
216 that contain Yahoo Messenger traffic?
218 12. Filtering traffic:
220 12.1 I saved a filter and tried to use its name to filter the display;
221 why do I get an "Unexpected end of filter string" error?
223 12.2 How can I search for, or filter, packets that have a particular
224 string anywhere in them?
226 12.3 How do I filter a capture to see traffic for virus XXX?
230 Q 1.1: What is Wireshark?
232 A: Wireshark is the world's most popular network protocol analyzer. It
233 has a rich and powerful feature set and runs on most computing
234 platforms including Windows, OS X, and Linux. Network professionals,
235 security experts, developers, and educators around the world use it
236 regularly. It is freely available as open source, and is released under
237 the GNU General Public License.
239 It is developed and maintained by a global team of protocol experts,
240 and it is an example of a disruptive technology. Wireshark used to be
241 known as Ethereal®. See the next question for details about the name
242 change. If you're still using Ethereal, it is strongly recommended that
243 you upgrade to Wireshark.
245 For more information, please see the About Wireshark page.
247 Q 1.2: What's up with the name change? Is Wireshark a fork?
249 A: In May of 2006, Gerald Combs (the original author of Ethereal®) went
250 to work for CACE Technologies (best known for WinPcap). Unfortunately,
251 he had to leave the Ethereal® trademarks behind.
253 This left the project in an awkward position. The only reasonable way
254 to ensure the continued success of the project was to change the name.
255 This is how Wireshark was born.
257 Wireshark is almost (but not quite) a fork. Normally a "fork" of an
258 open source project results in two names, web sites, development teams,
259 support infrastructures, etc. This is the case with Wireshark except
260 for one notable exception -- every member of the core development team
261 is now working on Wireshark. As far as anyone knows, there has been no
262 active development on Ethereal since the name change. Several parts of
263 the Ethereal web site (such as the mailing lists, source code
264 repository, and build farm) have gone offline.
266 More information on the name change can be found here:
270 Q 1.3: Where can I get help?
272 A: Community support is available on the wireshark-users mailing list.
273 Subscription information and archives for all of Wireshark's mailing
274 lists can be found at http://www.wireshark.org/mailman/listinfo. An IRC
275 channel dedicated to Wireshark can be found at
276 irc://irc.freenode.net/wireshark.
278 Self-paced and instructor-led training is available at Wireshark
279 University. A certification program will be announced in Q2 2007.
281 Commercial support and development services are available from CACE
284 Q 1.4: What kind of shark is Wireshark?
286 A: carcharodon photoshopia.
288 Q 1.5: How is Wireshark pronounced, spelled and capitalized?
290 A: Wireshark is pronounced as the word wire followed immediately by the
291 word shark. Exact pronunciation and emphasis may vary depending on your
292 locale (e.g. Arkansas).
294 It's spelled with a capital W, followed by a lower-case ireshark. It is
295 not a CamelCase word, i.e., WireShark is incorrect.
297 Q 1.6: How much does Wireshark cost?
299 A: Wireshark is "free software"; you can download it without paying any
300 license fee. The version of Wireshark you download isn't a "demo"
301 version, with limitations not present in a "full" version; it is the
304 The license under which Wireshark is issued is the GNU General Public
305 License. See the GNU GPL FAQ for some more information.
307 Q 1.7: Can I use Wireshark commercially?
309 A: Yes, if, for example, you mean "I work for a commercial
310 organization; can I use Wireshark to capture and analyze network
311 traffic in our company's networks or in our customer's networks?"
313 If you mean "Can I use Wireshark as part of my commercial product?",
314 see the next entry in the FAQ.
316 Q 1.8: Can I use Wireshark as part of my commercial product?
318 A: As noted, Wireshark is licensed under the GNU General Public
319 License. The GPL imposes conditions on your use of GPL'ed code in your
320 own products; you cannot, for example, make a "derived work" from
321 Wireshark, by making modifications to it, and then sell the resulting
322 derived work and not allow recipients to give away the resulting work.
323 You must also make the changes you've made to the Wireshark source
324 available to all recipients of your modified version; those changes
325 must also be licensed under the terms of the GPL. See the GPL FAQ for
326 more details; in particular, note the answer to the question about
327 modifying a GPLed program and selling it commercially, and the question
328 about linking GPLed code with other code to make a proprietary program.
330 You can combine a GPLed program such as Wireshark and a commercial
331 program as long as they communicate "at arm's length", as per this item
334 Q 1.9: What protocols are currently supported?
336 A: There are currently hundreds of supported protocols and media.
337 Details can be found in the wireshark(1) man page.
339 Q 1.10: Are there any plans to support {your favorite protocol}?
341 A: Support for particular protocols is added to Wireshark as a result
342 of people contributing that support; no formal plans for adding support
343 for particular protocols in particular future releases exist.
345 Q 1.11: Can Wireshark read capture files from {your favorite network
348 A: Support for particular protocols is added to Wireshark as a result
349 of people contributing that support; no formal plans for adding support
350 for particular protocols in particular future releases exist.
352 If a network analyzer writes out files in a format already supported by
353 Wireshark (e.g., in libpcap format), Wireshark may already be able to
354 read them, unless the analyzer has added its own proprietary extensions
357 If a network analyzer writes out files in its own format, or has added
358 proprietary extensions to another format, in order to make Wireshark
359 read captures from that network analyzer, we would either have to have
360 a specification for the file format, or the extensions, sufficient to
361 give us enough information to read the parts of the file relevant to
362 Wireshark, or would need at least one capture file in that format AND a
363 detailed textual analysis of the packets in that capture file (showing
364 packet time stamps, packet lengths, and the top-level packet header) in
365 order to reverse-engineer the file format.
367 Note that there is no guarantee that we will be able to
368 reverse-engineer a capture file format.
370 Q 1.12: What devices can Wireshark use to capture packets?
372 A: Wireshark can read live data from Ethernet, Token-Ring, FDDI, serial
373 (PPP and SLIP) (if the OS on which it's running allows Wireshark to do
374 so), 802.11 wireless LAN (if the OS on which it's running allows
375 Wireshark to do so), ATM connections (if the OS on which it's running
376 allows Wireshark to do so), and the "any" device supported on Linux by
377 recent versions of libpcap.
379 It can also read a variety of capture file formats, including:
380 * AG Group/WildPackets EtherPeek/TokenPeek/AiroPeek/EtherHelp/Packet
382 * AIX's iptrace captures
383 * Accellent's 5Views LAN agent output
384 * Cinco Networks NetXRay captures
385 * Cisco Secure Intrusion Detection System IPLog output
386 * CoSine L2 debug output
387 * DBS Etherwatch VMS text output
388 * Endace Measurement Systems' ERF format captures
389 * EyeSDN USB S0 traces
390 * HP-UX nettl captures
391 * ISDN4BSD project i4btrace captures
392 * Linux Bluez Bluetooth stack hcidump -w traces
393 * Lucent/Ascend router debug output
394 * Microsoft Network Monitor captures
395 * Network Associates Windows-based Sniffer captures
396 * Network General/Network Associates DOS-based Sniffer (compressed or
397 uncompressed) captures
398 * Network Instruments Observer version 9 captures
399 * Novell LANalyzer captures
400 * RADCOM's WAN/LAN analyzer captures
401 * Shomiti/Finisar Surveyor captures
402 * Toshiba's ISDN routers dump output
403 * VMS TCPIPtrace/TCPtrace/UCX$TRACE output
404 * Visual Networks' Visual UpTime traffic capture
405 * libpcap, tcpdump and various other tools using tcpdump's capture
407 * snoop and atmsnoop output
409 so that it can read traces from various network types, as captured by
410 other applications or equipment, even if it cannot itself capture on
413 Q 1.13: Does Wireshark work on Windows Me?
415 A: Yes, but if you want to capture packets, you will need to install
416 the latest version of WinPcap, as 2.02 and earlier versions of WinPcap
417 didn't support Windows Me. You should also install the latest version
418 of Wireshark as well.
420 Q 1.14: Does Wireshark work on Windows XP?
422 A: Yes, but if you want to capture packets, you will need to install
423 the latest version of WinPcap, as 2.2 and earlier versions of WinPcap
424 didn't support Windows XP.
426 2. Downloading Wireshark
428 Q 2.1: Why do I get an error when I try to run the Win32 installer?
430 A: The program you used to download it may have downloaded it
431 incorrectly. Web browsers sometimes may do this.
433 Try downloading it with, for example:
434 * Wget, for which Windows binaries are available on the SunSITE FTP
435 server at sunsite.tk or Heiko Herold's windows wget spot - wGetGUI
436 offers a GUI interface that uses wget;
437 * WS_FTP from Ipswitch,
438 * the ftp command that comes with Windows.
440 If you use the ftp command, make sure you do the transfer in binary
441 mode rather than ASCII mode, by using the binary command before
442 transferring the file.
444 3. Installing Wireshark
446 Q 3.1: I installed the Wireshark RPM (or other package); why did it
447 install TShark but not Wireshark?
449 A: Many distributions have separate Wireshark packages, one for non-GUI
450 components such as TShark, editcap, dumpcap, etc. and one for the GUI.
451 If this is the case on your system, there's probably a separate package
452 named wireshark-gnome or wireshark-gtk+. Find it and install it.
454 4. Building Wireshark
456 Q 4.1: I have libpcap installed; why did the configure script not find
459 A: Are you sure pcap.h and bpf.h are installed? The official
460 distribution of libpcap only installs the libpcap.a library file when
461 "make install" is run. To install pcap.h and bpf.h, you must run "make
462 install-incl". If you're running Debian or Redhat, make sure you have
463 the "libpcap-dev" or "libpcap-devel" packages installed.
465 It's also possible that pcap.h and bpf.h have been installed in a
466 strange location. If this is the case, you may have to tweak
469 Q 4.2: Why do I get the error
471 dftest_DEPENDENCIES was already defined in condition TRUE, which
472 implies condition HAVE_PLUGINS_TRUE
474 when I try to build Wireshark from SVN or a SVN snapshot?
476 A: You probably have automake 1.5 installed on your machine (the
477 command automake --version will report the version of automake on your
478 machine). There is a bug in that version of automake that causes this
479 problem; upgrade to a later version of automake (1.6 or later).
481 Q 4.3: Why does the linker fail with a number of "Output line too
482 long." messages followed by linker errors when I try to buil Wireshark?
484 A: The version of the sed command on your system is incapable of
485 handling very long lines. On Solaris, for example, /usr/bin/sed has a
486 line length limit too low to allow libtool to work; /usr/xpg4/bin/sed
487 can handle it, as can GNU sed if you have it installed.
489 On Solaris, changing your command search path to search /usr/xpg4/bin
490 before /usr/bin should make the problem go away; on any platform on
491 which you have this problem, installing GNU sed and changing your
492 command path to search the directory in which it is installed before
493 searching the directory with the version of sed that came with the OS
494 should make the problem go away.
496 Q 4.4: When I try to build Wireshark on Solaris, why does the link fail
497 complaining that plugin_list is undefined?
499 A: This appears to be due to a problem with some versions of the GTK+
500 and GLib packages from www.sunfreeware.org; un-install those packages,
501 and try getting the 1.2.10 versions from that site, or the versions
502 from The Written Word, or the versions from Sun's GNOME distribution,
503 or the versions from the supplemental software CD that comes with the
504 Solaris media kit, or build them from source from the GTK Web site.
505 Then re-run the configuration script, and try rebuilding Wireshark. (If
506 you get the 1.2.10 versions from www.sunfreeware.org, and the problem
507 persists, un-install them and try installing one of the other versions
510 Q 4.5: When I try to build Wireshark on Windows, why does the build
511 fail because of conflicts between winsock.h and winsock2.h?
513 A: As of Wireshark 0.9.5, you must install WinPcap 2.3 or later, and
514 the corresponding version of the developer's pack, in order to be able
515 to compile Wireshark; it will not compile with older versions of the
516 developer's pack. The symptoms of this failure are conflicts between
517 definitions in winsock.h and in winsock2.h; Wireshark uses winsock2.h,
518 but pre-2.3 versions of the WinPcap developer's packet use winsock.h.
519 (2.3 uses winsock2.h, so if Wireshark were to use winsock.h, it would
520 not be able to build with current versions of the WinPcap developer's
523 Note that the installed version of the developer's pack should be the
524 same version as the version of WinPcap you have installed.
526 5. Starting Wireshark
528 Q 5.1: Why does Wireshark crash with a Bus Error when I try to run it
531 A: Some versions of the GTK+ library from www.sunfreeware.org appear to
532 be buggy, causing Wireshark to drop core with a Bus Error. Un-install
533 those packages, and try getting the 1.2.10 version from that site, or
534 the version from The Written Word, or the version from Sun's GNOME
535 distribution, or the version from the supplemental software CD that
536 comes with the Solaris media kit, or build it from source from the GTK
537 Web site. Update the GLib library to the 1.2.10 version, from the same
538 source, as well. (If you get the 1.2.10 versions from
539 www.sunfreeware.org, and the problem persists, un-install them and try
540 installing one of the other versions mentioned.)
542 Similar problems may exist with older versions of GTK+ for earlier
545 Q 5.2: When I run Wireshark on Windows NT, why does it die with a Dr.
546 Watson error, reporting an "Integer division by zero" exception, when I
549 A: In at least some case, this appears to be due to using the default
550 VGA driver; if that's not the correct driver for your video card, try
551 running the correct driver for your video card.
553 Q 5.3: When I try to run Wireshark, why does it complain about
554 sprint_realloc_objid being undefined?
556 A: Wireshark can only be linked with version 4.2.2 or later of UCD
557 SNMP. Your version of Wireshark was dynamically linked with such a
558 version of UCD SNMP; however, you have an older version of UCD SNMP
559 installed, which means that when Wireshark is run, it tries to link to
560 the older version, and fails. You will have to replace that version of
561 UCD SNMP with version 4.2.2 or a later version.
563 Q 5.4: When I try to run Wireshark on Windows, why does it fail to run
564 with a complaint that it can't find packet.dll?
566 A: In older versions of Wireshark, there were two binary distributions
567 available for Windows, one that supported capturing packets, and one
568 that didn't. The version that supported capturing packets required that
569 you install the WinPcap driver; if you didn't install it, it would fail
570 to run because it couldn't find packet.dll.
572 The current version of Wireshark has only one binary distribution for
573 Windows; that version will check whether WinPcap is installed and, if
574 it's not, will disable support for packet capture.
576 The WinPcap driver and libraries can be downloaded from the WinPcap Web
577 site or the Wiretapped.net mirror of the WinPcap site.
579 Q 5.5: I've installed Wireshark from Fink on Mac OS X; why is it very
582 A: When an application is installed on OS X, prior to 10.4, it is
583 usually "prebound" to speed up launching the application. (That's what
584 the "Optimizing" phase of installation is.) Fink normally performs
585 prebinding automatically when you install a package. However, in some
586 rare cases, for whatever reason the prebinding caches get corrupt, and
587 then not only does prebinding fail, but startup actually becomes much
588 slower, because the system tries in vain to perform prebinding "on the
589 fly" as you launch the application. This fails, causing sometimes huge
590 delays. To fix the prebinding caches, run the command
591 sudo /sw/var/lib/fink/prebound/update-package-prebinding.pl -f
593 6. Crashes and other fatal errors
595 Q 6.1: I have an XXX network card on my machine; if I try to capture on
596 it, why does my machine crash or reset itself?
598 A: This is almost certainly a problem with one or more of:
599 * the operating system you're using;
600 * the device driver for the interface you're using;
601 * the libpcap/WinPcap library and, if this is Windows, the WinPcap
605 * if you are using Windows, see the WinPcap support page - check the
606 "Submitting bugs" section;
607 * if you are using some Linux distribution, some version of BSD, or
608 some other UNIX-flavored OS, you should report the problem to the
609 company or organization that produces the OS (in the case of a
610 Linux distribution, report the problem to whoever produces the
613 Q 6.2: Why does my machine crash or reset itself when I select "Start"
614 from the "Capture" menu or select "Preferences" from the "Edit" menu?
616 A: Both of those operations cause Wireshark to try to build a list of
617 the interfaces that it can open; it does so by getting a list of
618 interfaces and trying to open them. There is probably an OS, driver,
619 or, for Windows, WinPcap bug that causes the system to crash when this
620 happens; see the previous question.
624 Q 7.1: When I use Wireshark to capture packets, why do I see only
625 packets to and from my machine, or not see all the traffic I'm
626 expecting to see from or to the machine I'm trying to monitor?
628 A: This might be because the interface on which you're capturing is
629 plugged into an Ethernet or Token Ring switch; on a switched network,
630 unicast traffic between two ports will not necessarily appear on other
631 ports - only broadcast and multicast traffic will be sent to all ports.
633 Note that even if your machine is plugged into a hub, the "hub" may be
634 a switched hub, in which case you're still on a switched network.
636 Note also that on the Linksys Web site, they say that their
637 auto-sensing hubs "broadcast the 10Mb packets to the port that operate
638 at 10Mb only and broadcast the 100Mb packets to the ports that operate
639 at 100Mb only", which would indicate that if you sniff on a 10Mb port,
640 you will not see traffic coming sent to a 100Mb port, and vice versa.
641 This problem has also been reported for Netgear dual-speed hubs, and
642 may exist for other "auto-sensing" or "dual-speed" hubs.
644 Some switches have the ability to replicate all traffic on all ports to
645 a single port so that you can plug your analyzer into that single port
646 to sniff all traffic. You would have to check the documentation for the
647 switch to see if this is possible and, if so, to see how to do this.
648 See the switch reference page on the Wireshark Wiki for information on
649 some switches. (Note that it's a Wiki, so you can update or fix that
650 information, or add additional information on those switches or
651 information on new switches, yourself.)
653 Note also that many firewall/NAT boxes have a switch built into them;
654 this includes many of the "cable/DSL router" boxes. If you have a box
655 of that sort, that has a switch with some number of Ethernet ports into
656 which you plug machines on your network, and another Ethernet port used
657 to connect to a cable or DSL modem, you can, at least, sniff traffic
658 between the machines on your network and the Internet by plugging the
659 Ethernet port on the router going to the modem, the Ethernet port on
660 the modem, and the machine on which you're running Wireshark into a hub
661 (make sure it's not a switching hub, and that, if it's a dual-speed
662 hub, all three of those ports are running at the same speed.
664 If your machine is not plugged into a switched network or a dual-speed
665 hub, or it is plugged into a switched network but the port is set up to
666 have all traffic replicated to it, the problem might be that the
667 network interface on which you're capturing doesn't support
668 "promiscuous" mode, or because your OS can't put the interface into
669 promiscuous mode. Normally, network interfaces supply to the host only:
670 * packets sent to one of that host's link-layer addresses;
672 * multicast packets sent to a multicast address that the host has
673 configured the interface to accept.
675 Most network interfaces can also be put in "promiscuous" mode, in which
676 they supply to the host all network packets they see. Wireshark will
677 try to put the interface on which it's capturing into promiscuous mode
678 unless the "Capture packets in promiscuous mode" option is turned off
679 in the "Capture Options" dialog box, and TShark will try to put the
680 interface on which it's capturing into promiscuous mode unless the -p
681 option was specified. However, some network interfaces don't support
682 promiscuous mode, and some OSes might not allow interfaces to be put
683 into promiscuous mode.
685 If the interface is not running in promiscuous mode, it won't see any
686 traffic that isn't intended to be seen by your machine. It will see
687 broadcast packets, and multicast packets sent to a multicast MAC
688 address the interface is set up to receive.
690 You should ask the vendor of your network interface whether it supports
691 promiscuous mode. If it does, you should ask whoever supplied the
692 driver for the interface (the vendor, or the supplier of the OS you're
693 running on your machine) whether it supports promiscuous mode with that
696 In the case of token ring interfaces, the drivers for some of them, on
697 Windows, may require you to enable promiscuous mode in order to capture
698 in promiscuous mode. See the Wireshark Wiki item on Token Ring
699 capturing for details.
701 In the case of wireless LAN interfaces, it appears that, when those
702 interfaces are promiscuously sniffing, they're running in a
703 significantly different mode from the mode that they run in when
704 they're just acting as network interfaces (to the extent that it would
705 be a significant effor for those drivers to support for promiscuously
706 sniffing and acting as regular network interfaces at the same time), so
707 it may be that Windows drivers for those interfaces don't support
710 Q 7.2: When I capture with Wireshark, why can't I see any TCP packets
711 other than packets to and from my machine, even though another analyzer
712 on the network sees those packets?
714 A: You're probably not seeing any packets other than unicast packets to
715 or from your machine, and broadcast and multicast packets; a switch
716 will normally send to a port only unicast traffic sent to the MAC
717 address for the interface on that port, and broadcast and multicast
718 traffic - it won't send to that port unicast traffic sent to a MAC
719 address for some other interface - and a network interface not in
720 promiscuous mode will receive only unicast traffic sent to the MAC
721 address for that interface, broadcast traffic, and multicast traffic
722 sent to a multicast MAC address the interface is set up to receive.
724 TCP doesn't use broadcast or multicast, so you will only see your own
725 TCP traffic, but UDP services may use broadcast or multicast so you'll
726 see some UDP traffic - however, this is not a problem with TCP traffic,
727 it's a problem with unicast traffic, as you also won't see all UDP
728 traffic between other machines.
730 I.e., this is probably the same question as this earlier one; see the
731 response to that question.
733 Q 7.3: Why am I only seeing ARP packets when I try to capture traffic?
735 A: You're probably on a switched network, and running Wireshark on a
736 machine that's not sending traffic to the switch and not being sent any
737 traffic from other machines on the switch. ARP packets are often
738 broadcast packets, which are sent to all switch ports.
740 I.e., this is probably the same question as this earlier one; see the
741 response to that question.
743 Q 7.4: Why am I not seeing any traffic when I try to capture traffic?
745 A: Is the machine running Wireshark sending out any traffic on the
746 network interface on which you're capturing, or receiving any traffic
747 on that network, or is there any broadcast traffic on the network or
748 multicast traffic to a multicast group to which the machine running
751 If not, this may just be a problem with promiscuous sniffing, either
752 due to running on a switched network or a dual-speed hub, or due to
753 problems with the interface not supporting promiscuous mode; see the
754 response to this earlier question.
756 Otherwise, on Windows, see the response to this question and, on a
757 UNIX-flavored OS, see the response to this question.
759 Q 7.5: Can Wireshark capture on (my T1/E1 line, SS7 links, etc.)?
761 A: Wireshark can only capture on devices supported by libpcap/WinPcap.
762 On most OSes, only devices that can act as network interfaces of the
763 type that support IP are supported as capture devices for
764 libpcap/WinPcap, although the device doesn't necessarily have to be
765 running as an IP interface in order to support traffic capture.
767 On Linux and FreeBSD, libpcap 0.8 and later support the API for Endace
768 Measurement Systems' DAG cards, so that a system with one of those
769 cards, and its driver and libraries, installed can capture traffic with
770 those cards with libpcap-based applications. You would either have to
771 have a version of Wireshark built with that version of libpcap, or a
772 dynamically-linked version of Wireshark and a shared libpcap library
773 with DAG support, in order to do so with Wireshark. You should ask
774 Endace whether that could be used to capture traffic on, for example,
775 your T1/E1 link. See the SS7 capture setup page on the Wireshark Wiki
776 for current information on capturing SS7 traffic on TDM links.
778 Q 7.6: How do I put an interface into promiscuous mode?
780 A: By not disabling promiscuous mode when running Wireshark or TShark.
783 * the form of promiscuous mode that libpcap (the library that
784 programs such as tcpdump, Wireshark, etc. use to do packet capture)
785 turns on will not necessarily be shown if you run ifconfig on the
786 interface on a UNIX system;
787 * some network interfaces might not support promiscuous mode, and
788 some drivers might not allow promiscuous mode to be turned on - see
789 this earlier question for more information on that;
790 * the fact that you're not seeing any traffic, or are only seeing
791 broadcast traffic, or aren't seeing any non-broadcast traffic other
792 than traffic to or from the machine running Wireshark, does not
793 mean that promiscuous mode isn't on - see this earlier question for
794 more information on that.
796 I.e., this is probably the same question as this earlier one; see the
797 response to that question.
799 Q 7.7: I can set a display filter just fine; why don't capture filters
802 A: Capture filters currently use a different syntax than display
803 filters. Here's the corresponding section from the wireshark(1) man
806 "Display filters in Wireshark are very powerful; more fields are
807 filterable in Wireshark than in other protocol analyzers, and the
808 syntax you can use to create your filters is richer. As Wireshark
809 progresses, expect more and more protocol fields to be allowed in
812 Packet capturing is performed with the pcap library. The capture filter
813 syntax follows the rules of the pcap library. This syntax is different
814 from the display filter syntax."
816 The capture filter syntax used by libpcap can be found in the
819 Q 7.8: I'm entering valid capture filters; why do I still get "parse
822 A: There is a bug in some versions of libpcap/WinPcap that cause it to
823 report parse errors even for valid expressions if a previous filter
824 expression was invalid and got a parse error.
826 Try exiting and restarting Wireshark; if you are using a version of
827 libpcap/WinPcap with this bug, this will "erase" its memory of the
828 previous parse error. If the capture filter that got the "parse error"
829 now works, the earlier error with that filter was probably due to this
832 The bug was fixed in libpcap 0.6; 0.4[.x] and 0.5[.x] versions of
833 libpcap have this bug, but 0.6[.x] and later versions don't.
835 Versions of WinPcap prior to 2.3 are based on pre-0.6 versions of
836 libpcap, and have this bug; WinPcap 2.3 is based on libpcap 0.6.2, and
837 doesn't have this bug.
839 If you are running Wireshark on a UNIX-flavored platform, run
840 "wireshark -v", or select "About Wireshark..." from the "Help" menu in
841 Wireshark, to see what version of libpcap it's using. If it's not 0.6
842 or later, you will need either to upgrade your OS to get a later
843 version of libpcap, or will need to build and install a later version
844 of libpcap from the tcpdump.org Web site and then recompile Wireshark
845 from source with that later version of libpcap.
847 If you are running Wireshark on Windows with a pre-2.3 version of
848 WinPcap, you will need to un-install WinPcap and then download and
851 Q 7.9: How can I capture packets with CRC errors?
853 A: Wireshark can capture only the packets that the packet capture
854 library - libpcap on UNIX-flavored OSes, and the WinPcap port to
855 Windows of libpcap on Windows - can capture, and libpcap/WinPcap can
856 capture only the packets that the OS's raw packet capture mechanism (or
857 the WinPcap driver, and the underlying OS networking code and network
858 interface drivers, on Windows) will allow it to capture.
860 Unless the OS always supplies packets with errors such as invalid CRCs
861 to the raw packet capture mechanism, or can be configured to do so,
862 invalid CRCs to the raw packet capture mechanism, Wireshark - and other
863 programs that capture raw packets, such as tcpdump - cannot capture
864 those packets. You will have to determine whether your OS needs to be
865 so configured and, if so, can be so configured, configure it if
866 necessary and possible, and make whatever changes to libpcap and the
867 packet capture program you're using are necessary, if any, to support
868 capturing those packets.
870 Most OSes probably do not support capturing packets with invalid CRCs
871 on Ethernet, and probably do not support it on most other link-layer
872 types. Some drivers on some OSes do support it, such as some Ethernet
873 drivers on FreeBSD; in those OSes, you might always get those packets,
874 or you might only get them if you capture in promiscuous mode (you'd
875 have to determine which is the case).
877 Note that libpcap does not currently supply to programs that use it an
878 indication of whether the packet's CRC was invalid (because the drivers
879 themselves do not supply that information to the raw packet capture
880 mechanism); therefore, Wireshark will not indicate which packets had
881 CRC errors unless the FCS was captured (see the next question) and
882 you're using Wireshark 0.9.15 and later, in which case Wireshark will
883 check the CRC and indicate whether it's correct or not.
885 Q 7.10: How can I capture entire frames, including the FCS?
887 A: Wireshark can only capture data that the packet capture library -
888 libpcap on UNIX-flavored OSes, and the WinPcap port to Windows of
889 libpcap on Windows - can capture, and libpcap/WinPcap can capture only
890 the data that the OS's raw packet capture mechanism (or the WinPcap
891 driver, and the underlying OS networking code and network interface
892 drivers, on Windows) will allow it to capture.
894 For any particular link-layer network type, unless the OS supplies the
895 FCS of a frame as part of the frame, or can be configured to do so,
896 Wireshark - and other programs that capture raw packets, such as
897 tcpdump - cannot capture the FCS of a frame. You will have to determine
898 whether your OS needs to be so configured and, if so, can be so
899 configured, configure it if necessary and possible, and make whatever
900 changes to libpcap and the packet capture program you're using are
901 necessary, if any, to support capturing the FCS of a frame.
903 Most OSes do not support capturing the FCS of a frame on Ethernet, and
904 probably do not support it on most other link-layer types. Some drivres
905 on some OSes do support it, such as some (all?) Ethernet drivers on
906 NetBSD and possibly the driver for Apple's gigabit Ethernet interface
907 in Mac OS X; in those OSes, you might always get the FCS, or you might
908 only get the FCS if you capture in promiscuous mode (you'd have to
909 determine which is the case).
911 Versions of Wireshark prior to 0.9.15 will not treat an Ethernet FCS in
912 a captured packet as an FCS. 0.9.15 and later will attempt to determine
913 whether there's an FCS at the end of the frame and, if it thinks there
914 is, will display it as such, and will check whether it's the correct
917 Q 7.11: I'm capturing packets on a machine on a VLAN; why don't the
918 packets I'm capturing have VLAN tags?
920 A: You might be capturing on what might be called a "VLAN interface" -
921 the way a particular OS makes VLANs plug into the networking stack
922 might, for example, be to have a network device object for the physical
923 interface, which takes VLAN packets, strips off the VLAN header and
924 constructs an Ethernet header, and passes that packet to an internal
925 network device object for the VLAN, which then passes the packets onto
926 various higher-level protocol implementations.
928 In order to see the raw Ethernet packets, rather than "de-VLANized"
929 packets, you would have to capture not on the virtual interface for the
930 VLAN, but on the interface corresponding to the physical network
931 device, if possible. See the Wireshark Wiki item on VLAN capturing for
934 Q 7.12: Why does Wireshark hang after I stop a capture?
936 A: The most likely reason for this is that Wireshark is trying to look
937 up an IP address in the capture to convert it to a name (so that, for
938 example, it can display the name in the source address or destination
939 address columns), and that lookup process is taking a very long time.
941 Wireshark calls a routine in the OS of the machine on which it's
942 running to convert of IP addresses to the corresponding names. That
943 routine probably does one or more of:
944 * a search of a system file listing IP addresses and names;
945 * a lookup using DNS;
946 * on UNIX systems, a lookup using NIS;
947 * on Windows systems, a NetBIOS-over-TCP query.
949 If a DNS server that's used in an address lookup is not responding, the
950 lookup will fail, but will only fail after a timeout while the system
951 routine waits for a reply.
953 In addition, on Windows systems, if the DNS lookup of the address
954 fails, either because the server isn't responding or because there are
955 no records in the DNS that could be used to map the address to a name,
956 a NetBIOS-over-TCP query will be made. That query involves sending a
957 message to the NetBIOS-over-TCP name service on that machine, asking
958 for the name and other information about the machine. If the machine
959 isn't running software that responds to those queries - for example,
960 many non-Windows machines wouldn't be running that software - the
961 lookup will only fail after a timeout. Those timeouts can cause the
962 lookup to take a long time.
964 If you disable network address-to-name translation - for example, by
965 turning off the "Enable network name resolution" option in the "Capture
966 Options" dialog box for starting a network capture - the lookups of the
967 address won't be done, which may speed up the process of reading the
968 capture file after the capture is stopped. You can make that setting
969 the default by selecting "Preferences" from the "Edit" menu, turning
970 off the "Enable network name resolution" option in the "Name
971 resolution" options in the preferences disalog box, and using the
972 "Save" button in that dialog box; note that this will save all your
973 current preference settings.
975 If Wireshark hangs when reading a capture even with network name
976 resolution turned off, there might, for example, be a bug in one of
977 Wireshark's dissectors for a protocol causing it to loop infinitely. If
978 you're not running the most recent release of Wireshark, you should
979 first upgrade to that release, as, if there's a bug of that sort, it
980 might've been fixed in a release after the one you're running. If the
981 hang occurs in the most recent release of Wireshark, the bug should be
982 reported to the Wireshark developers' mailing list at
983 wireshark-dev@wireshark.org.
985 On UNIX-flavored OSes, please try to force Wireshark to dump core, by
986 sending it a SIGABRT signal (usually signal 6) with the kill command,
987 and then get a stack trace if you have a debugger installed. A stack
988 trace can be obtained by using your debugger (gdb in this example), the
989 Wireshark binary, and the resulting core file. Here's an example of how
990 to use the gdb command backtrace to do so.
993 ..... prints the stack trace
997 The core dump file may be named "wireshark.core" rather than "core" on
998 some platforms (e.g., BSD systems).
1000 Also, if at all possible, please send a copy of the capture file that
1001 caused the problem; when capturing packets, Wireshark normally writes
1002 captured packets to a temporary file, which will probably be in /tmp or
1003 /var/tmp on UNIX-flavored OSes, \TEMP on the main system disk (normally
1004 C:) on Windows 9x/Me/NT 4.0, and \Documents and Settings\your login
1005 name\Local Settings\Temp on the main system disk on Windows
1006 2000/Windows XP/Windows Server 2003, so the capture file will probably
1007 be there. It will have a name beginning with ether, with some mixture
1008 of letters and numbers after that. Please don't send a trace file
1009 greater than 1 MB when compressed; instead, make it available via FTP
1010 or HTTP, or say it's available but leave it up to a developer to ask
1011 for it. If the trace file contains sensitive information (e.g.,
1012 passwords), then please do not send it.
1014 8. Capturing packets on Windows
1016 Q 8.1: I'm running Wireshark on Windows; why does some network
1017 interface on my machine not show up in the list of interfaces in the
1018 "Interface:" field in the dialog box popped up by "Capture->Start",
1019 and/or why does Wireshark give me an error if I try to capture on that
1022 A: If you are running Wireshark on Windows NT 4.0, Windows 2000,
1023 Windows XP, or Windows Server 2003, and this is the first time you have
1024 run a WinPcap-based program (such as Wireshark, or TShark, or WinDump,
1025 or Analyzer, or...) since the machine was rebooted, you need to run
1026 that program from an account with administrator privileges; once you
1027 have run such a program, you will not need administrator privileges to
1028 run any such programs until you reboot.
1030 If you are running on Windows 95/98/Me, or if you are running on
1031 Windows NT 4.0/Windows 2000/Windows XP/Windows Server 2003 and have
1032 administrator privileges or a WinPcap-based program has been run with
1033 those privileges since the machine rebooted, this problem might clear
1034 up if you completely un-install WinPcap and then re-install it.
1036 If that doesn't work, then note that Wireshark relies on the WinPcap
1037 library, on the WinPcap device driver, and on the facilities that come
1038 with the OS on which it's running in order to do captures.
1040 Therefore, if the OS, the WinPcap library, or the WinPcap driver don't
1041 support capturing on a particular network interface device, Wireshark
1042 won't be able to capture on that device.
1045 1. 2.02 and earlier versions of the WinPcap driver and library that
1046 Wireshark uses for packet capture didn't support Token Ring
1047 interfaces; versions 2.1 and later support Token Ring, and the
1048 current version of Wireshark works with (and, in fact, requires)
1049 WinPcap 2.1 or later.
1050 If you are having problems capturing on Token Ring interfaces, and
1051 you have WinPcap 2.02 or an earlier version of WinPcap installed,
1052 you should uninstall WinPcap, download and install the current
1053 version of WinPcap, and then install the latest version of
1055 2. On Windows 95, 98, or Me, sometimes more than one interface will be
1056 given the same name; if that is the case, you will only be able to
1057 capture on one of those interfaces - it's not clear to which one
1058 the name, when used in a WinPcap-based application, will refer. For
1059 example, if you have a PPP serial interface and a VPN interface,
1060 they might show up with the same name, for example "ppp-mac", and
1061 if you try to capture on "ppp-mac", it might not capture on the
1062 interface you're currently using. In that case, you might, for
1063 example, have to remove the VPN interface from the system in order
1064 to capture on the PPP serial interface.
1065 3. WinPcap 2.3 has problems supporting PPP WAN interfaces on Windows
1066 NT 4.0, Windows 2000, Windows XP, and Windows Server 2003, and, to
1067 avoid those problems, support for PPP WAN interfaces on those
1068 versions of Windows has been disabled in WinPcap 3.0. Regular
1069 dial-up lines, ISDN lines, ADSL connections using PPPoE or PPPoA,
1070 and various other lines such as T1/E1 lines are all PPP interfaces,
1071 so those interfaces might not show up on the list of interfaces in
1072 the "Capture Options" dialog on those OSes.
1073 On Windows 2000, Windows XP, and Windows Server 2003, but not
1074 Windows NT 4.0 or Windows Vista Beta 1, you should be able to
1075 capture on the "GenericDialupAdapter" with WinPcap 3.1. (3.1 beta
1076 releases called it the "NdisWanAdapter"; if you're using a 3.1 beta
1077 release, you should un-install it and install the final 3.1
1078 release.) See the Wireshark Wiki item on PPP capturing for details.
1079 4. WinPcap prior to 3.0 does not support multiprocessor machines (note
1080 that machines with a single multi-threaded processor, such as
1081 Intel's new multi-threaded x86 processors, are multiprocessor
1082 machines as far as the OS and WinPcap are concerned), and recent
1083 2.x versions of WinPcap refuse to operate if they detect that
1084 they're running on a multiprocessor machine, which means that they
1085 may not show any network interfaces. You will need to use WinPcap
1086 3.0 to capture on a multiprocessor machine.
1088 If an interface doesn't show up in the list of interfaces in the
1089 "Interface:" field, and you know the name of the interface, try
1090 entering that name in the "Interface:" field and capturing on that
1093 If the attempt to capture on it succeeds, the interface is somehow not
1094 being reported by the mechanism Wireshark uses to get a list of
1095 interfaces. Try listing the interfaces with WinDump; see the WinDump
1096 Web site for information on using WinDump.
1098 You would run WinDump with the -D flag; if it lists the interface,
1099 please report this to wireshark-dev@wireshark.org giving full details
1100 of the problem, including
1101 * the operating system you're using, and the version of that
1103 * the type of network device you're using;
1104 * the output of WinDump.
1106 If WinDump does not list the interface, this is almost certainly a
1107 problem with one or more of:
1108 * the operating system you're using;
1109 * the device driver for the interface you're using;
1110 * the WinPcap library and/or the WinPcap device driver;
1112 so first check the WinPcap FAQ or the Wiretapped.net mirror of that
1113 FAQ, to see if your problem is mentioned there. If not, then see the
1114 WinPcap support page - check the "Submitting bugs" section.
1116 If you are having trouble capturing on a particular network interface,
1117 first try capturing on that device with WinDump; see the WinDump Web
1118 site for information on using WinDump.
1120 If you can capture on the interface with WinDump, send mail to
1121 wireshark-users@wireshark.org giving full details of the problem,
1123 * the operating system you're using, and the version of that
1125 * the type of network device you're using;
1126 * the error message you get from Wireshark.
1128 If you cannot capture on the interface with WinDump, this is almost
1129 certainly a problem with one or more of:
1130 * the operating system you're using;
1131 * the device driver for the interface you're using;
1132 * the WinPcap library and/or the WinPcap device driver;
1134 so first check the WinPcap FAQ or the Wiretapped.net mirror of that
1135 FAQ, to see if your problem is mentioned there. If not, then see the
1136 WinPcap support page - check the "Submitting bugs" section.
1138 You may also want to ask the wireshark-users@wireshark.org and the
1139 winpcap-users@winpcap.org mailing lists to see if anybody happens to
1140 know about the problem and know a workaround or fix for the problem.
1141 (Note that you will have to subscribe to that list in order to be
1142 allowed to mail to it; see the WinPcap support page for information on
1143 the mailing list.) In your mail, please give full details of the
1144 problem, as described above, and also indicate that the problem occurs
1145 with WinDump, not just with Wireshark.
1147 Q 8.2: I'm running Wireshark on Windows; why do no network interfaces
1148 show up in the list of interfaces in the "Interface:" field in the
1149 dialog box popped up by "Capture->Start"?
1151 A: This is really the same question as the previous one; see the
1152 response to that question.
1154 Q 8.3: I'm running Wireshark on Windows; why doesn't my serial
1155 port/ADSL modem/ISDN modem show up in the list of interfaces in the
1156 "Interface:" field in the dialog box popped up by "Capture->Start"?
1158 A: Internet access on those devices is often done with the
1159 Point-to-Point (PPP) protocol; WinPcap 2.3 has problems supporting PPP
1160 WAN interfaces on Windows NT 4.0, Windows 2000, Windows XP, and Windows
1161 Server 2003, and, to avoid those problems, support for PPP WAN
1162 interfaces on those versions of Windows has been disabled in WinPcap
1165 On Windows 2000, Windows XP, and Windows Server 2003, but not Windows
1166 NT 4.0 or Windows Vista Beta 1, you should be able to capture on the
1167 "GenericDialupAdapter" with WinPcap 3.1. (3.1 beta releases called it
1168 the "NdisWanAdapter"; if you're using a 3.1 beta release, you should
1169 un-install it and install the final 3.1 release.) See the Wireshark
1170 Wiki item on PPP capturing for details.
1172 Q 8.4: I'm running Wireshark on Windows NT 4.0/Windows 2000/Windows
1173 XP/Windows Server 2003; my machine has a PPP (dial-up POTS, ISDN, etc.)
1174 interface, and it shows up in the "Interface" item in the "Capture
1175 Options" dialog box. Why can no packets be sent on or received from
1176 that network while I'm trying to capture traffic on that interface?
1178 A: Some versions of WinPcap have problems with PPP WAN interfaces on
1179 Windows NT 4.0, Windows 2000, Windows XP, and Windows Server 2003; one
1180 symptom that may be seen is that attempts to capture in promiscuous
1181 mode on the interface cause the interface to be incapable of sending or
1182 receiving packets. You can disable promiscuous mode using the -p
1183 command-line flag or the item in the "Capture Preferences" dialog box,
1184 but this may mean that outgoing packets, or incoming packets, won't be
1185 seen in the capture.
1187 On Windows 2000, Windows XP, and Windows Server 2003, but not Windows
1188 NT 4.0 or Windows Vista Beta 1, you should be able to capture on the
1189 "GenericDialupAdapter" with WinPcap 3.1. (3.1 beta releases called it
1190 the "NdisWanAdapter"; if you're using a 3.1 beta release, you should
1191 un-install it and install the final 3.1 release.) See the Wireshark
1192 Wiki item on PPP capturing for details.
1194 Q 8.5: I'm running Wireshark on Windows 95/98/Me, on a machine with
1195 more than one network adapter of the same type; why does Wireshark show
1196 all of those adapters with the same name, not letting me use any of
1197 those adapters other than the first one?
1199 A: Unfortunately, Windows 95/98/Me gives the same name to multiple
1200 instances of the type of same network adapter. Therefore, WinPcap
1201 cannot distinguish between them, so a WinPcap-based application can
1202 capture only on the first such interface; Wireshark is a
1203 libpcap/WinPcap-based application.
1205 Q 8.6: I'm running Wireshark on Windows; why am I not seeing any
1206 traffic being sent by the machine running Wireshark?
1208 A: If you are running some form of VPN client software, it might be
1209 causing this problem; people have seen this problem when they have
1210 Check Point's VPN software installed on their machine. If that's the
1211 cause of the problem, you will have to remove the VPN software in order
1212 to have Wireshark (or any other application using WinPcap) see outgoing
1213 packets; unfortunately, neither we nor the WinPcap developers know any
1214 way to make WinPcap and the VPN software work well together.
1216 Also, some drivers for Windows (especially some wireless network
1217 interface drivers) apparently do not, when running in promiscuous mode,
1218 arrange that outgoing packets are delivered to the software that
1219 requested that the interface run promiscuously; try turning promiscuous
1222 Q 8.7: When I capture on Windows in promiscuous mode, I can see packets
1223 other than those sent to or from my machine; however, those packets
1224 show up with a "Short Frame" indication, unlike packets to or from my
1225 machine. What should I do to arrange that I see those packets in their
1228 A: In at least some cases, this appears to be the result of PGPnet
1229 running on the network interface on which you're capturing; turn it off
1232 Q 8.8: I'm capturing packets on {Windows 95, Windows 98, Windows Me};
1233 why are the time stamps on packets wrong?
1235 A: This is due to a bug in WinPcap. The bug should be fixed in WinPcap
1236 3.0 and later releases.
1238 Q 8.9: I'm trying to capture 802.11 traffic on Windows; why am I not
1241 A: At least some 802.11 card drivers on Windows appear not to see any
1242 packets if they're running in promiscuous mode. Try turning promiscuous
1243 mode off; you'll only be able to see packets sent by and received by
1244 your machine, not third-party traffic, and it'll look like Ethernet
1245 traffic and won't include any management or control frames, but that's
1246 a limitation of the card drivers.
1248 See MicroLogix's list of cards supported with WinPcap for information
1249 on support of various adapters and drivers with WinPcap.
1251 Q 8.10: I'm trying to capture 802.11 traffic on Windows; why am I
1252 seeing packets received by the machine on which I'm capturing traffic,
1253 but not packets sent by that machine?
1255 A: This appears to be another problem with promiscuous mode; try
1258 Q 8.11: I'm trying to capture Ethernet VLAN traffic on Windows, and I'm
1259 capturing on a "raw" Ethernet device rather than a "VLAN interface", so
1260 that I can see the VLAN headers; why am I seeing packets received by
1261 the machine on which I'm capturing traffic, but not packets sent by
1264 A: The way the Windows networking code works probably means that
1265 packets are sent on a "VLAN interface" rather than the "raw" device, so
1266 packets sent by the machine will only be seen when you capture on the
1267 "VLAN interface". If so, you will be unable to see outgoing packets
1268 when capturing on the "raw" device, so you are stuck with a choice
1269 between seeing VLAN headers and seeing outgoing packets.
1271 9. Capturing packets on UN*Xes
1273 Q 9.1: I'm running Wireshark on a UNIX-flavored OS; why does some
1274 network interface on my machine not show up in the list of interfaces
1275 in the "Interface:" field in the dialog box popped up by
1276 "Capture->Start", and/or why does Wireshark give me an error if I try
1277 to capture on that interface?
1279 A: You may need to run Wireshark from an account with sufficient
1280 privileges to capture packets, such as the super-user account, or may
1281 need to give your account sufficient privileges to capture packets.
1282 Only those interfaces that Wireshark can open for capturing show up in
1283 that list; if you don't have sufficient privileges to capture on any
1284 interfaces, no interfaces will show up in the list. See the Wireshark
1285 Wiki item on capture privileges for details on how to give a particular
1286 account or account group capture privileges on platforms where that can
1289 If you are running Wireshark from an account with sufficient
1290 privileges, then note that Wireshark relies on the libpcap library, and
1291 on the facilities that come with the OS on which it's running in order
1292 to do captures. On some OSes, those facilities aren't present by
1293 default; see the Wireshark Wiki item on adding capture support for
1296 And, even if you're running with an account that has sufficient
1297 privileges to capture, and capture support is present in your OS, if
1298 the OS or the libpcap library don't support capturing on a particular
1299 network interface device or particular types of devices, Wireshark
1300 won't be able to capture on that device.
1302 On Solaris, note that libpcap 0.6.2 and earlier didn't support Token
1303 Ring interfaces; the current version, 0.7.2, does support Token Ring,
1304 and the current version of Wireshark works with libcap 0.7.2 and later.
1306 If an interface doesn't show up in the list of interfaces in the
1307 "Interface:" field, and you know the name of the interface, try
1308 entering that name in the "Interface:" field and capturing on that
1311 If the attempt to capture on it succeeds, the interface is somehow not
1312 being reported by the mechanism Wireshark uses to get a list of
1313 interfaces; please report this to wireshark-dev@wireshark.org giving
1314 full details of the problem, including
1315 * the operating system you're using, and the version of that
1316 operating system (for Linux, give both the version number of the
1317 kernel and the name and version number of the distribution you're
1319 * the type of network device you're using.
1321 If you are having trouble capturing on a particular network interface,
1322 and you've made sure that (on platforms that require it) you've
1323 arranged that packet capture support is present, as per the above,
1324 first try capturing on that device with tcpdump.
1326 If you can capture on the interface with tcpdump, send mail to
1327 wireshark-users@wireshark.org giving full details of the problem,
1329 * the operating system you're using, and the version of that
1330 operating system (for Linux, give both the version number of the
1331 kernel and the name and version number of the distribution you're
1333 * the type of network device you're using;
1334 * the error message you get from Wireshark.
1336 If you cannot capture on the interface with tcpdump, this is almost
1337 certainly a problem with one or more of:
1338 * the operating system you're using;
1339 * the device driver for the interface you're using;
1340 * the libpcap library;
1342 so you should report the problem to the company or organization that
1343 produces the OS (in the case of a Linux distribution, report the
1344 problem to whoever produces the distribution).
1346 You may also want to ask the wireshark-users@wireshark.org and the
1347 tcpdump-workers@tcpdump.org mailing lists to see if anybody happens to
1348 know about the problem and know a workaround or fix for the problem. In
1349 your mail, please give full details of the problem, as described above,
1350 and also indicate that the problem occurs with tcpdump not just with
1353 Q 9.2: I'm running Wireshark on a UNIX-flavored OS; why do no network
1354 interfaces show up in the list of interfaces in the "Interface:" field
1355 in the dialog box popped up by "Capture->Start"?
1357 A: This is really the same question as the previous one; see the
1358 response to that question.
1360 Q 9.3: I'm capturing packets on Linux; why do the time stamps have only
1361 100ms resolution, rather than 1us resolution?
1363 A: Wireshark gets time stamps from libpcap/WinPcap, and libpcap/WinPcap
1364 get them from the OS kernel, so Wireshark - and any other program using
1365 libpcap, such as tcpdump - is at the mercy of the time stamping code in
1366 the OS for time stamps.
1368 At least on x86-based machines, Linux can get high-resolution time
1369 stamps on newer processors with the Time Stamp Counter (TSC) register;
1370 for example, Intel x86 processors, starting with the Pentium Pro, and
1371 including all x86 processors since then, have had a TSC, and other
1372 vendors probably added the TSC at some point to their families of x86
1375 The Linux kernel must be configured with the CONFIG_X86_TSC option
1376 enabled in order to use the TSC. Make sure this option is enabled in
1379 In addition, some Linux distributions may have bugs in their versions
1380 of the kernel that cause packets not to be given high-resolution time
1381 stamps even if the TSC is enabled. See, for example, bug 61111 for Red
1382 Hat Linux 7.2. If your distribution has a bug such as this, you may
1383 have to run a standard kernel from kernel.org in order to get
1384 high-resolution time stamps.
1386 10. Capturing packets on wireless LANs
1388 Q 10.1: How can I capture raw 802.11 frames, including non-data
1389 (management, beacon) frames?
1391 A: That depends on the operating system on which you're running, and on
1392 the 802.11 interface on which you're capturing.
1394 This would probably require that you capture in promiscuous mode or in
1395 the mode called "monitor mode" or "RFMON mode". On some platforms, or
1396 with some cards, this might require that you capture in monitor mode -
1397 promiscuous mode might not be sufficient. If you want to capture
1398 traffic on networks other than the one with which you're associated,
1399 you will have to capture in monitor mode.
1401 Not all operating systems support capturing non-data packets and, even
1402 on operating systems that do support it, not all drivers, and thus not
1403 all interfaces, support it. Even on those that do, monitor mode might
1404 not be supported by the operating system or by the drivers for all
1407 NOTE: an interface running in monitor mode will, on most if not all
1408 platforms, not be able to act as a regular network interface; putting
1409 it into monitor mode will, in effect, take your machine off of whatever
1410 network it's on as long as the interface is in monitor mode, allowing
1411 it only to passively capture packets.
1413 This means that you should disable name resolution when capturing in
1414 monitor mode; otherwise, when Wireshark (or TShark, or tcpdump) tries
1415 to display IP addresses as host names, it will probably block for a
1416 long time trying to resolve the name because it will not be able to
1417 communicate with any DNS or NIS servers.
1419 See the Wireshark Wiki item on 802.11 capturing for details.
1421 Q 10.2: How do I capture on an 802.11 device in monitor mode?
1423 A: Whether you will be able to capture in monitor mode depends on the
1424 operating system, adapter, and driver you're using. See the previous
1425 question for information on monitor mode, including a link to the
1426 Wireshark Wiki page that gives details on 802.11 capturing.
1430 Q 11.1: Why am I seeing lots of packets with incorrect TCP checksums?
1432 A: If the packets that have incorrect TCP checksums are all being sent
1433 by the machine on which Wireshark is running, this is probably because
1434 the network interface on which you're capturing does TCP checksum
1435 offloading. That means that the TCP checksum is added to the packet by
1436 the network interface, not by the OS's TCP/IP stack; when capturing on
1437 an interface, packets being sent by the host on which you're capturing
1438 are directly handed to the capture interface by the OS, which means
1439 that they are handed to the capture interface without a TCP checksum
1440 being added to them.
1442 The only way to prevent this from happening would be to disable TCP
1443 checksum offloading, but
1444 1. that might not even be possible on some OSes;
1445 2. that could reduce networking performance significantly.
1447 However, you can disable the check that Wireshark does of the TCP
1448 checksum, so that it won't report any packets as having TCP checksum
1449 errors, and so that it won't refuse to do TCP reassembly due to a
1450 packet having an incorrect TCP checksum. That can be set as an
1451 Wireshark preference by selecting "Preferences" from the "Edit" menu,
1452 opening up the "Protocols" list in the left-hand pane of the
1453 "Preferences" dialog box, selecting "TCP", from that list, turning off
1454 the "Check the validity of the TCP checksum when possible" option,
1455 clicking "Save" if you want to save that setting in your preference
1456 file, and clicking "OK".
1458 It can also be set on the Wireshark or TShark command line with a -o
1459 tcp.check_checksum:false command-line flag, or manually set in your
1460 preferences file by adding a tcp.check_checksum:false line.
1462 Q 11.2: I've just installed Wireshark, and the traffic on my local LAN
1463 is boring. Where can I find more interesting captures?
1465 A: We have a collection of strange and exotic sample capture files at
1466 http://wiki.wireshark.org/SampleCaptures
1468 Q 11.3: Why doesn't Wireshark correctly identify RTP packets? It shows
1471 A: Wireshark can identify a UDP datagram as containing a packet of a
1472 particular protocol running atop UDP only if
1473 1. The protocol in question has a particular standard port number, and
1474 the UDP source or destination port number is that port
1475 2. Packets of that protocol can be identified by looking for a
1476 "signature" of some type in the packet - i.e., some data that, if
1477 Wireshark finds it in some particular part of a packet, means that
1478 the packet is almost certainly a packet of that type.
1479 3. Some other traffic earlier in the capture indicated that, for
1480 example, UDP traffic between two particular addresses and ports
1481 will be RTP traffic.
1483 RTP doesn't have a standard port number, so 1) doesn't work; it
1484 doesn't, as far as I know, have any "signature", so 2) doesn't work.
1486 That leaves 3). If there's RTSP traffic that sets up an RTP session,
1487 then, at least in some cases, the RTSP dissector will set things up so
1488 that subsequent RTP traffic will be identified. Currently, that's the
1489 only place we do that; there may be other places.
1491 However, there will always be places where Wireshark is simply
1492 incapable of deducing that a given UDP flow is RTP; a mechanism would
1493 be needed to allow the user to specify that a given conversation should
1494 be treated as RTP. As of Wireshark 0.8.16, such a mechanism exists; if
1495 you select a UDP or TCP packet, the right mouse button menu will have a
1496 "Decode As..." menu item, which will pop up a dialog box letting you
1497 specify that the source port, the destination port, or both the source
1498 and destination ports of the packet should be dissected as some
1499 particular protocol.
1501 Q 11.4: Why doesn't Wireshark show Yahoo Messenger packets in captures
1502 that contain Yahoo Messenger traffic?
1504 A: Wireshark only recognizes as Yahoo Messenger traffic packets to or
1505 from TCP port 3050 that begin with "YPNS", "YHOO", or "YMSG". TCP
1506 segments that start with the middle of a Yahoo Messenger packet that
1507 takes more than one TCP segment will not be recognized as Yahoo
1508 Messenger packets (even if the TCP segment also contains the beginning
1509 of another Yahoo Messenger packet).
1511 12. Filtering traffic
1513 Q 12.1: I saved a filter and tried to use its name to filter the
1514 display; why do I get an "Unexpected end of filter string" error?
1516 A: You cannot use the name of a saved display filter as a filter. To
1517 filter the display, you can enter a display filter expression - not the
1518 name of a saved display filter - in the "Filter:" box at the bottom of
1519 the display, and type the key or press the "Apply" button (that does
1520 not require you to have a saved filter), or, if you want to use a saved
1521 filter, you can press the "Filter:" button, select the filter in the
1522 dialog box that pops up, and press the "OK" button.
1524 Q 12.2: How can I search for, or filter, packets that have a particular
1525 string anywhere in them?
1527 A: If you want to do this when capturing, you can't. That's a feature
1528 that would be hard to implement in capture filters without changes to
1529 the capture filter code, which, on many platforms, is in the OS kernel
1530 and, on other platforms, is in the libpcap library.
1532 In releases prior to 0.9.14, you also can't search for, or filter,
1533 packets containing a particular string even after you've captured them.
1535 In 0.9.14, you can search for, but not filter, packets that have a
1536 particular string; this has been added to the "Find Frame" dialog
1537 ("Find Frame" under the "Edit" menu, or control-F).
1539 In 0.9.15 and later, you can search for those packets using either the
1540 mechanism introduced in 0.9.14 or using the new "contains" operator in
1541 filter expressions, which lets you search the entire packet or text
1542 string or byte string fields in the packet; the "contains" operator can
1543 also be used in expressions used to filter the display.
1545 Q 12.3: How do I filter a capture to see traffic for virus XXX?
1547 A: For some viruses/worms there might be a capture filter to recognize
1548 the virus traffic. Check the CaptureFilters page on the Wireshark Wiki
1549 to see if anybody's added such a filter.
1551 Note that Wireshark was not designed to be an intrusion detection
1552 system; you might be able to use it as an IDS, but in most cases
1553 software designed to be an IDS, such as Snort or Prelude, will probably
1556 The Bleeding Edge of Snort has a collection of signatures for Snort to
1557 detect various viruses, worms, and the like.