4 Note: This is just an ASCII snapshot of the faq and may not be up to
5 date. Please go to http://www.ethereal.com/faq for the up to
6 date version. The version of this snapshot can be found at the
13 1.1 Where can I get help?
15 1.2 What protocols are currently supported?
17 1.3 Are there any plans to support {your favorite protocol}?
19 1.4 Can Ethereal read capture files from {your favorite network
22 1.5 What devices can Ethereal use to capture packets?
24 1.6 How do you pronounce Ethereal? Where did the name come from?
28 2.1 I downloaded the Win32 installer, but when I try to run it, I get
31 2.2 When I try to download the WinPcap driver and library, I can't get
32 to the WinPcap Web site.
36 3.1 I installed an Ethereal RPM, but Ethereal doesn't seem to be
37 installed; only Tethereal is installed.
41 4.1 The configure script can't find pcap.h or bpf.h, but I have
44 4.2 Why do I get the error
46 dftest_DEPENDENCIES was already defined in condition TRUE, which
47 implies condition HAVE_PLUGINS_TRUE
49 when I try to build Ethereal from CVS or a CVS snapshot?
51 4.3 The link fails with a number of "Output line too long." messages
52 followed by linker errors.
54 4.4 The link fails on Solaris because plugin_list is undefined.
56 4.5 The build fails on Windows because of conflicts between winsock.h
61 5.1 When I use Ethereal to capture packets, I see only packets to and
62 from my machine, or I'm not seeing all the traffic I'm expecting to
63 see from or to the machine I'm trying to monitor.
65 5.2 I can't see any TCP packets other than packets to and from my
66 machine, even though another analyzer on the network sees those
69 5.3 I'm only seeing ARP packets when I try to capture traffic.
71 5.4 How do I put an interface into promiscuous mode?
73 5.5 I can set a display filter just fine, but capture filters don't
76 5.6 I'm entering valid capture filters, but I still get "parse error"
79 5.7 I saved a filter and tried to use its name to filter the display,
80 but I got an "Unexpected end of filter string" error.
82 5.8 Why am I seeing lots of packets with incorrect TCP checksums?
84 5.9 I've just installed Ethereal, and the traffic on my local LAN is
87 5.10 When I run Ethereal on Solaris 8, it dies with a Bus Error when I
90 5.11 When I run Ethereal on Windows NT, it dies with a Dr. Watson
91 error, reporting an "Integer division by zero" exception, when I start
94 5.12 When I try to run Ethereal, it complains about
95 sprint_realloc_objid being undefined.
97 5.13 I'm running Ethereal on Linux; why do my time stamps have only
98 100ms resolution, rather than 1us resolution?
100 5.14 I'm capturing packets on {Windows 95, Windows 98, Windows Me};
101 why are the time stamps on packets wrong?
103 5.15 When I try to run Ethereal on Windows, it fails to run because it
104 can't find packet.dll.
106 5.16 I'm running Ethereal on Windows; why does some network interface
107 on my machine not show up in the list of interfaces in the
108 "Interface:" field in the dialog box popped up by "Capture->Start",
109 and/or why does Ethereal give me an error if I try to capture on that
112 5.17 I'm running on a UNIX-flavored OS; why does some network
113 interface on my machine not show up in the list of interfaces in the
114 "Interface:" field in the dialog box popped up by "Capture->Start",
115 and/or why does Ethereal give me an error if I try to capture on that
118 5.18 I'm running Ethereal on Windows NT/2000/XP/Server; my machine has
119 a PPP (dial-up POTS, ISDN, etc.) interface, and it shows up in the
120 "Interface" item in the "Capture Options" dialog box. Why can no
121 packets be sent on or received from that network while I'm trying to
122 capture traffic on that interface?
124 5.19 I'm running Ethereal on Windows 95/98/Me, on a machine with more
125 than one network adapter of the same type; Ethereal shows all of those
126 adapters with the same name, but I can't use any of those adapters
127 other than the first one.
129 5.20 I'm running Ethereal on Windows, and I'm not seeing any traffic
130 being sent by the machine running Ethereal.
132 5.21 I'm trying to capture traffic but I'm not seeing any.
134 5.22 I have an XXX network card on my machine; if I try to capture on
135 it, my machine crashes or resets itself.
137 5.23 My machine crashes or resets itself when I select "Start" from
138 the "Capture" menu or select "Preferences" from the "Edit" menu.
140 5.24 Does Ethereal work on Windows ME?
142 5.25 Does Ethereal work on Windows XP?
144 5.26 Why doesn't Ethereal correctly identify RTP packets? It shows
147 5.27 Why doesn't Ethereal show Yahoo Messenger packets in captures
148 that contain Yahoo Messenger traffic?
150 5.28 Why do I get the error
152 Gdk-ERROR **: Palettized display (256-colour) mode not supported on
156 when I try to run Ethereal on Windows?
158 5.29 When I capture on Windows in promiscuous mode, I can see packets
159 other than those sent to or from my machine; however, those packets
160 show up with a "Short Frame" indication, unlike packets to or from my
161 machine. What should I do to arrange that I see those packets in their
164 5.30 How can I capture raw 802.11 packets, including non-data
165 (management, beacon) packets?
167 5.31 How can I capture packets with CRC errors?
169 5.32 How can I capture entire frames, including the FCS?
171 5.33 Ethereal hangs after I stop a capture.
173 5.34 How can I search for, or filter, packets that have a particular
174 string anywhere in them?
177 Q 1.1: Where can I get help?
179 A: Support is available on the ethereal-users mailing list.
180 Subscription information and archives for all of Ethereal's mailing
181 lists can be found at http://www.ethereal.com/lists
183 Q 1.2: What protocols are currently supported?
185 A: There are currently 385 supported protocols and media, listed
186 below. Descriptions can be found in the ethereal(1) man page.
189 802.1x Authentication
190 AFS (4.0) Replication Server call declarations
191 AOL Instant Messenger
198 AVS WLAN Capture header
199 Ad hoc On-demand Distance Vector Routing Protocol
200 Address Resolution Protocol
201 Aggregate Server Access Protocol
203 Andrew File System (AFS)
204 Apache JServ Protocol v1.3
205 AppleTalk Filing Protocol
206 AppleTalk Session Protocol
207 AppleTalk Transaction Protocol packet
208 Appletalk Address Resolution Protocol
209 Application Configuration Access Protocol
210 Async data over ISDN (V.120)
211 Authentication Header
212 BACnet Virtual Link Control
215 Banyan Vines Fragmentation Protocol
222 Blocks Extensible Exchange Protocol
226 Border Gateway Protocol
227 Building Automation and Control Network APDU
228 Building Automation and Control Network NPDU
229 CDS Clerk Server Calls
230 Check Point High Availability Protocol
233 Cisco Discovery Protocol
234 Cisco Group Management Protocol
236 Cisco Hot Standby Router Protocol
238 Cisco Interior Gateway Routing Protocol
242 CoSine IPNOS L2 debug output
243 Common Open Policy Service
244 Common Unix Printing System (CUPS) Browsing Protocol
246 DCE Distributed Time Service Local Server
247 DCE Distributed Time Service Provider
250 DCE Security ID Mapper
252 DCE/RPC CDS Solicitation
253 DCE/RPC Conversation Manager
254 DCE/RPC Endpoint Mapper
256 DCE/RPC FLDB UBIK TRANSFER
257 DCE/RPC FLDB UBIKVOTE
262 DCE/RPC Remote Management
263 DCE/RPC Repserver Calls
264 DCE/RPC TokenServer Calls
267 DCOM Remote Activation
268 DEC Spanning Tree Protocol
270 DNS Control Program Server
273 Data Stream Interface
274 Datagram Delivery Protocol
276 Distance Vector Multicast Routing Protocol
277 Distcc Distributed Compiler
278 Distributed Checksum Clearinghouse Prototocl
280 Dynamic DNS Tools Protocol
281 Encapsulating Security Payload
282 Enhanced Interior Gateway Routing Protocol
283 EtherNet/IP (Industrial Protocol)
286 Extensible Authentication Protocol
288 FC Fabric Configuration Server
292 Fiber Distributed Data Interface
294 Fibre Channel Common Transport
295 Fibre Channel Fabric Zone Server
296 Fibre Channel Name Server
297 Fibre Channel Protocol for SCSI
299 File Transfer Protocol (FTP)
300 Financial Information eXchange Protocol
303 GARP Multicast Registration Protocol
304 GARP VLAN Registration Protocol
305 GPRS Tunneling Protocol
306 GPRS Tunnelling Protocol v0
307 GPRS Tunnelling Protocol v1
308 General Inter-ORB Protocol
309 Generic Routing Encapsulation
310 Generic Security Service Application Program Interface
312 HP Extended Local-Link Control
313 HP Remote Maintenance Protocol
314 Hummingbird NFS Daemon
316 Hypertext Transfer Protocol
318 IEEE 802.11 wireless LAN
319 IEEE 802.11 wireless LAN management frame
322 IP Payload Compression
324 IPX Routing Information Protocol
327 ISDN Q.921-User Adaptation Layer
329 ISO 10589 ISIS InTRA Domain Routeing Information Exchange Protocol
330 ISO 8073 COTP Connection-Oriented Transport Protocol
331 ISO 8473 CLNP ConnectionLess Network Protocol
332 ISO 8602 CLTP ConnectionLess Transport Protocol
333 ISO 9542 ESIS Routeing Information Exchange Protocol
334 ITU-T Recommendation H.261
336 Intelligent Platform Management Interface
337 Inter-Access-Point Protocol
339 Internet Cache Protocol
340 Internet Content Adaptation Protocol
341 Internet Control Message Protocol
342 Internet Control Message Protocol v6
343 Internet Group Management Protocol
344 Internet Message Access Protocol
345 Internet Printing Protocol
347 Internet Protocol Version 6
349 Internet Security Association and Key Management Protocol
350 Internetwork Packet eXchange
354 Kerberos Administration
356 Label Distribution Protocol
357 Layer 2 Tunneling Protocol
358 Lightweight Directory Access Protocol
359 Line Printer Daemon Protocol
360 Link Access Procedure Balanced (LAPB)
361 Link Access Procedure Balanced Ethernet (LAPBETHER)
362 Link Access Procedure, Channel D (LAPD)
363 Link Aggregation Control Protocol
364 Link Management Protocol (LMP)
365 Linux cooked-mode capture
366 Local Management Interface
367 LocalTalk Link Access Protocol
369 Lucent/Ascend debug output
371 MMS Message Encapsulation
373 MSN Messenger Service
374 MSNIP: Multicast Source Notification of Interest Protocol
375 MTP 2 Transparent Proxy
376 MTP 2 User Adaptation Layer
377 MTP 3 User Adaptation Layer
378 MTP2 Peer Adaptation Layer
379 Message Transfer Part Level 2
380 Message Transfer Part Level 3
381 Message Transfer Part Level 3 Management
382 Microsoft Distributed File System
383 Microsoft Exchange MAPI
384 Microsoft Local Security Architecture
385 Microsoft Local Security Architecture (Directory Services)
386 Microsoft Network Logon
388 Microsoft Security Account Manager
389 Microsoft Server Service
390 Microsoft Service Control
391 Microsoft Spool Subsystem
392 Microsoft Task Scheduler Service
393 Microsoft Telephony API Service
394 Microsoft Windows Browser Protocol
395 Microsoft Windows Lanman Remote API Protocol
396 Microsoft Windows Logon Protocol
397 Microsoft Workstation Service
402 MultiProtocol Label Switching Header
403 Multicast Router DISCovery protocol
404 Multicast Source Discovery Protocol
411 NTLM Secure Service Provider
412 Name Binding Protocol
413 Name Management Protocol over IPX
415 NetBIOS Datagram Service
417 NetBIOS Session Service
419 NetWare Core Protocol
420 NetWare Link Services Protocol
421 Network Data Management Protocol
423 Network Lock Manager Protocol
424 Network News Transfer Protocol
425 Network Status Monitor CallBack Protocol
426 Network Status Monitor Protocol
427 Network Time Protocol
428 Novell Distributed Print System
430 Open Shortest Path First
431 OpenBSD Encapsulating device
432 OpenBSD Packet Filter log file
433 OpenBSD Packet Filter log file, pre 3.4
435 PPP Bandwidth Allocation Control Protocol
436 PPP Bandwidth Allocation Protocol
437 PPP CDP Control Protocol
438 PPP Callback Control Protocol
439 PPP Challenge Handshake Authentication Protocol
440 PPP Compressed Datagram
441 PPP Compression Control Protocol
442 PPP IP Control Protocol
443 PPP IPv6 Control Protocol
444 PPP Link Control Protocol
445 PPP MPLS Control Protocol
446 PPP Multilink Protocol
448 PPP Password Authentication Protocol
450 PPP-over-Ethernet Discovery
451 PPP-over-Ethernet Session
452 PPPMux Control Protocol
453 Point-to-Point Protocol
454 Point-to-Point Tunnelling Protocol
457 Pragmatic General Multicast
459 Privilege Server operations
460 Protocol Independent Multicast
463 Quake II Network Protocol
464 Quake III Arena Network Protocol
465 Quake Network Protocol
466 QuakeWorld Network Protocol
467 Qualified Logical Link Control
472 RSYNC File Synchroniser
474 Radio Access Network Application Part
477 Real Time Streaming Protocol
478 Real-Time Transport Protocol
479 Real-time Transport Control Protocol
480 Registry Server Attributes Manipulation Interface
481 Registry server administration operations.
482 Remote Management Control Protocol
483 Remote Override interface
484 Remote Procedure Call
489 Remote sec_login preauth interface.
490 Resource ReserVation Protocol (RSVP)
492 Routing Information Protocol
493 Routing Table Maintenance Protocol
497 SMB (Server Message Block Protocol)
498 SMB MailSlot Protocol
501 SNMP Multiplex Protocol
504 SS7 SCCP-User Adaptation Layer
508 Sequenced Packet eXchange
509 Service Advertisement Protocol
510 Service Location Protocol
511 Session Announcement Protocol
512 Session Description Protocol
513 Session Initiation Protocol
514 Short Message Peer to Peer
515 Signalling Connection Control Part
516 Signalling Connection Control Part Management
517 Simple Mail Transfer Protocol
518 Simple Network Management Protocol
520 Skinny Client Control Protocol
521 SliMP3 Communication Protocol
523 Spanning Tree Protocol
525 Stream Control Transmission Protocol
526 Synchronous Data Link Control (SDLC)
528 Systems Network Architecture
529 Systems Network Architecture XID
534 Tazmen Sniffer Protocol
537 Time Synchronization Protocol
539 Token-Ring Media Access Control
540 Transmission Control Protocol
541 Transparent Network Substrate Protocol
542 Trivial File Transfer Protocol
543 Universal Computer Protocol
544 User Datagram Protocol
545 Virtual Router Redundancy Protocol
546 Virtual Trunking Protocol
548 Web Cache Coordination Protocol
549 Wellfleet Breath of Life
550 Wellfleet Compression
554 Wireless Session Protocol
555 Wireless Transaction Protocol
556 Wireless Transport Layer Security
557 X Display Manager Control Protocol
563 Yahoo Messenger Protocol
564 Yahoo YMSG Messenger Protocol
568 Yellow Pages Transfer
570 Zone Information Protocol
574 Q 1.3: Are there any plans to support {your favorite protocol}?
576 A: Support for particular protocols is added to Ethereal as a result
577 of people contributing that support; no formal plans for adding
578 support for particular protocols in particular future releases exist.
580 Q 1.4: Can Ethereal read capture files from {your favorite network
583 A: Support for particular protocols is added to Ethereal as a result
584 of people contributing that support; no formal plans for adding
585 support for particular protocols in particular future releases exist.
587 If a network analyzer writes out files in a format already supported
588 by Ethereal (e.g., in libpcap format), Ethereal may already be able to
589 read them, unless the analyzer has added its own proprietary
590 extensions to that format.
592 If a network analyzer writes out files in its own format, or has added
593 proprietary extensions to another format, in order to make Ethereal
594 read captures from that network analyzer, we would either have to have
595 a specification for the file format, or the extensions, sufficient to
596 give us enough information to read the parts of the file relevant to
597 Ethereal, or would need at least one capture file in that format AND a
598 detailed textual analysis of the packets in that capture file (showing
599 packet time stamps, packet lengths, and the top-level packet header)
600 in order to reverse-engineer the file format.
602 Note that there is no guarantee that we will be able to
603 reverse-engineer a capture file format.
605 Q 1.5: What devices can Ethereal use to capture packets?
607 A: Ethereal can read live data from Ethernet, Token-Ring, FDDI, serial
608 (PPP and SLIP) (if the OS on which it's running allows Ethereal to do
609 so), 802.11 wireless LAN (if the OS on which it's running allows
610 Ethereal to do so), ATM connections (if the OS on which it's running
611 allows Ethereal to do so), and the "any" device supported on Linux by
612 recent versions of libpcap. See the list of supported capture media on
613 various OSes for details (several items in there say "Unknown", which
614 doesn't mean "Ethereal can't capture on them", it means "we don't know
615 whether it can capture on them"; we expect that it will be able to
616 capture on many of them, but we haven't tried it ourselves - if you
617 try one of those types and it works, please send an update to
618 ethereal-web[AT]ethereal.com).
620 It can also read a variety of capture file formats, including:
623 * Shomiti/Finisar Surveyor
625 * DOS-based Sniffer (compressed and uncompressed)
628 * NetXray and Windows-based Sniffer
629 * EtherPeek/TokenPeek/AiroPeek
630 * RADCOM WAN/LAN analyzer
631 * Lucent/Ascend debug output
632 * Toshiba ISDN router "snoop" output
634 * ISDN4BSD "i4btrace" utility.
636 * pppd log files (pppdump format)
639 * Visual Networks' Visual UpTime
642 so that it can read traces from various network types, as captured by
643 other applications or equipment, even if it cannot itself capture on
646 Q 1.6: How do you pronounce Ethereal? Where did the name come from?
648 A: The English pronunciation can be found in Merriam-Webster's online
650 http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=ethereal.
652 According to the book "Computer Networks" by Andrew Tannenbaum,
653 Ethernet was named after the "luminiferous ether" which was once
654 thought to carry electromagnetic radiation. Taking that into
655 consideration, Ethereal seemed like an appropriate name for an
659 Q 2.1: I downloaded the Win32 installer, but when I try to run it, I
662 A: The program you used to download it may have downloaded it
663 incorrectly. Web browsers sometimes may do this.
665 Try downloading it with, for example:
666 * Wget, for which Windows binaries are available on the SunSITE FTP
667 server at sunsite.tk or Heiko Herold's windows wget spot - wGetGUI
668 offers a GUI interface that uses wget;
669 * WS_FTP from Ipswitch,
670 * the ftp command that comes with Windows.
672 If you use the ftp command, make sure you do the transfer in binary
673 mode rather than ASCII mode, by using the binary command before
674 transferring the file.
676 Q 2.2: When I try to download the WinPcap driver and library, I can't
677 get to the WinPcap Web site.
679 A: As is the case with all Web sites, that site won't necessarily
680 always be accessible; the server may be down due to a problem or down
681 for maintenance, or there may be a networking problem between you and
682 the server. You should try again later, or try the local mirror or the
683 Wiretapped.net mirror.
686 Q 3.1: I installed an Ethereal RPM, but Ethereal doesn't seem to be
687 installed; only Tethereal is installed.
689 A: Red Hat RPMs for Ethereal put only the non-GUI components into the
690 ethereal RPM, the fact that Ethereal is a GUI program nonwithstanding;
691 there's a separate ethereal-gnome RPM that includes GUI components
692 such as Ethereal itself, the fact that Ethereal doesn't use GNOME
693 nonwithstanding. Find the ethereal-gnome RPM, and install that also.
696 Q 4.1: The configure script can't find pcap.h or bpf.h, but I have
699 A: Are you sure pcap.h and bpf.h are installed? The official
700 distribution of libpcap only installs the libpcap.a library file when
701 "make install" is run. To install pcap.h and bpf.h, you must run "make
702 install-incl". If you're running Debian or Redhat, make sure you have
703 the "libpcap-dev" or "libpcap-devel" packages installed.
705 It's also possible that pcap.h and bpf.h have been installed in a
706 strange location. If this is the case, you may have to tweak
709 Q 4.2: Why do I get the error
711 dftest_DEPENDENCIES was already defined in condition TRUE, which
712 implies condition HAVE_PLUGINS_TRUE
714 when I try to build Ethereal from CVS or a CVS snapshot?
716 A: You probably have automake 1.5 installed on your machine (the
717 command automake --version will report the version of automake on your
718 machine). There is a bug in that version of automake that causes this
719 problem; upgrade to a later version of automake (1.6 or later).
721 Q 4.3: The link fails with a number of "Output line too long."
722 messages followed by linker errors.
724 A: The version of the sed command on your system is incapable of
725 handling very long lines. On Solaris, for example, /usr/bin/sed has a
726 line length limit too low to allow libtool to work; /usr/xpg4/bin/sed
727 can handle it, as can GNU sed if you have it installed.
729 On Solaris, changing your command search path to search /usr/xpg4/bin
730 before /usr/bin should make the problem go away; on any platform on
731 which you have this problem, installing GNU sed and changing your
732 command path to search the directory in which it is installed before
733 searching the directory with the version of sed that came with the OS
734 should make the problem go away.
736 Q 4.4: The link fails on Solaris because plugin_list is undefined.
738 A: This appears to be due to a problem with some versions of the GTK+
739 and GLib packages from www.sunfreeware.org; un-install those packages,
740 and try getting the 1.2.10 versions from that site, or the versions
741 from The Written Word, or the versions from Sun's GNOME distribution,
742 or the versions from the supplemental software CD that comes with the
743 Solaris media kit, or build them from source from the GTK Web site.
744 Then re-run the configuration script, and try rebuilding Ethereal. (If
745 you get the 1.2.10 versions from www.sunfreeware.org, and the problem
746 persists, un-install them and try installing one of the other versions
749 Q 4.5: The build fails on Windows because of conflicts between
750 winsock.h and winsock2.h.
752 A: As of Ethereal 0.9.5, you must install WinPcap 2.3 or later, and
753 the corresponding version of the developer's pack, in order to be able
754 to compile Ethereal; it will not compile with older versions of the
755 developer's pack. The symptoms of this failure are conflicts between
756 definitions in winsock.h and in winsock2.h; Ethereal uses winsock2.h,
757 but pre-2.3 versions of the WinPcap developer's packet use winsock.h.
758 (2.3 uses winsock2.h, so if Ethereal were to use winsock.h, it would
759 not be able to build with current versions of the WinPcap developer's
762 Note that the installed version of the developer's pack should be the
763 same version as the version of WinPcap you have installed.
766 Q 5.1: When I use Ethereal to capture packets, I see only packets to
767 and from my machine, or I'm not seeing all the traffic I'm expecting
768 to see from or to the machine I'm trying to monitor.
770 A: This might be because the interface on which you're capturing is
771 plugged into a switch; on a switched network, unicast traffic between
772 two ports will not necessarily appear on other ports - only broadcast
773 and multicast traffic will be sent to all ports.
775 Note that even if your machine is plugged into a hub, the "hub" may be
776 a switched hub, in which case you're still on a switched network.
778 Note also that on the Linksys Web site, they say that their
779 auto-sensing hubs "broadcast the 10Mb packets to the port that operate
780 at 10Mb only and broadcast the 100Mb packets to the ports that operate
781 at 100Mb only", which would indicate that if you sniff on a 10Mb port,
782 you will not see traffic coming sent to a 100Mb port, and vice versa.
783 This problem has also been reported for Netgear dual-speed hubs, and
784 may exist for other "auto-sensing" or "dual-speed" hubs.
786 Some switches have the ability to replicate all traffic on all ports
787 to a single port so that you can plug your analyzer into that single
788 port to sniff all traffic. You would have to check the documentation
789 for the switch to see if this is possible and, if so, to see how to do
790 this. See, for example:
791 * this documentation from Cisco on the Switched Port Analyzer (SPAN)
792 feature on Catalyst switches;
793 * documentation from HP on how to set "monitoring"/"mirroring" on
794 ports on the console for HP Advancestack Switch 208 and 224;
795 * the "Network Monitoring Port Features" section of chapter 6 of
796 documentation from HP for HP ProCurve Switches 1600M, 2424M,
799 Note also that many firewall/NAT boxes have a switch built into them;
800 this includes many of the "cable/DSL router" boxes. If you have a box
801 of that sort, that has a switch with some number of Ethernet ports
802 into which you plug machines on your network, and another Ethernet
803 port used to connect to a cable or DSL modem, you can, at least, sniff
804 traffic between the machines on your network and the Internet by
805 plugging the Ethernet port on the router going to the modem, the
806 Ethernet port on the modem, and the machine on which you're running
807 Ethereal into a hub (make sure it's not a switching hub, and that, if
808 it's a dual-speed hub, all three of those ports are running at the
811 If your machine is not plugged into a switched network or a dual-speed
812 hub, or it is plugged into a switched network but the port is set up
813 to have all traffic replicated to it, the problem might be that the
814 network interface on which you're capturing doesn't support
815 "promiscuous" mode, or because your OS can't put the interface into
816 promiscuous mode. Normally, network interfaces supply to the host
818 * packets sent to one of that host's link-layer addresses;
820 * multicast packets sent to a multicast address that the host has
821 configured the interface to accept.
823 Most network interfaces can also be put in "promiscuous" mode, in
824 which they supply to the host all network packets they see. Ethereal
825 will try to put the interface on which it's capturing into promiscuous
826 mode unless the "Capture packets in promiscuous mode" option is turned
827 off in the "Capture Options" dialog box, and Tethereal will try to put
828 the interface on which it's capturing into promiscuous mode unless the
829 -p option was specified. However, some network interfaces don't
830 support promiscuous mode, and some OSes might not allow interfaces to
831 be put into promiscuous mode.
833 If the interface is not running in promiscuous mode, it won't see any
834 traffic that isn't intended to be seen by your machine. It will see
835 broadcast packets, and multicast packets sent to a multicast MAC
836 address the interface is set up to receive.
838 You should ask the vendor of your network interface whether it
839 supports promiscuous mode. If it does, you should ask whoever supplied
840 the driver for the interface (the vendor, or the supplier of the OS
841 you're running on your machine) whether it supports promiscuous mode
842 with that network interface.
844 In the case of token ring interfaces, the drivers for some of them, on
845 Windows, may require you to enable promiscuous mode in order to
846 capture in promiscuous mode. Ask the vendor of the card how to do
847 this, or see, for example, this information on promiscuous mode on
848 some Madge token ring adapters (note that those cards can have
849 promiscuous mode disabled permanently, in which case you can't enable
852 In the case of wireless LAN interfaces, it appears that, when those
853 interfaces are promiscuously sniffing, they're running in a
854 significantly different mode from the mode that they run in when
855 they're just acting as network interfaces (to the extent that it would
856 be a significant effor for those drivers to support for promiscuously
857 sniffing and acting as regular network interfaces at the same time),
858 so it may be that Windows drivers for those interfaces don't support
861 Q 5.2: I can't see any TCP packets other than packets to and from my
862 machine, even though another analyzer on the network sees those
865 A: You're probably not seeing any packets other than unicast packets
866 to or from your machine, and broadcast and multicast packets; a switch
867 will normally send to a port only unicast traffic sent to the MAC
868 address for the interface on that port, and broadcast and multicast
869 traffic - it won't send to that port unicast traffic sent to a MAC
870 address for some other interface - and a network interface not in
871 promiscuous mode will receive only unicast traffic sent to the MAC
872 address for that interface, broadcast traffic, and multicast traffic
873 sent to a multicast MAC address the interface is set up to receive.
875 TCP doesn't use broadcast or multicast, so you will only see your own
876 TCP traffic, but UDP services may use broadcast or multicast so you'll
877 see some UDP traffic - however, this is not a problem with TCP
878 traffic, it's a problem with unicast traffic, as you also won't see
879 all UDP traffic between other machines.
881 I.e., this is probably the same question as this earlier one; see the
882 response to that question.
884 Q 5.3: I'm only seeing ARP packets when I try to capture traffic.
886 A: You're probably on a switched network, and running Ethereal on a
887 machine that's not sending traffic to the switch and not being sent
888 any traffic from other machines on the switch. ARP packets are often
889 broadcast packets, which are sent to all switch ports.
891 I.e., this is probably the same question as this earlier one; see the
892 response to that question.
894 Q 5.4: How do I put an interface into promiscuous mode?
896 A: By not disabling promiscuous mode when running Ethereal or
900 * the form of promiscuous mode that libpcap (the library that
901 programs such as tcpdump, Ethereal, etc. use to do packet capture)
902 turns on will not necessarily be shown if you run ifconfig on the
903 interface on a UNIX system;
904 * some network interfaces might not support promiscuous mode, and
905 some drivers might not allow promiscuous mode to be turned on -
906 see this earlier question for more information on that;
907 * the fact that you're not seeing any traffic, or are only seeing
908 broadcast traffic, or aren't seeing any non-broadcast traffic
909 other than traffic to or from the machine running Ethereal, does
910 not mean that promiscuous mode isn't on - see this earlier
911 question for more information on that.
913 I.e., this is probably the same question as this earlier one; see the
914 response to that question.
916 Q 5.5: I can set a display filter just fine, but capture filters don't
919 A: Capture filters currently use a different syntax than display
920 filters. Here's the corresponding section from the ethereal(1) man
923 "Display filters in Ethereal are very powerful; more fields are
924 filterable in Ethereal than in other protocol analyzers, and the
925 syntax you can use to create your filters is richer. As Ethereal
926 progresses, expect more and more protocol fields to be allowed in
929 Packet capturing is performed with the pcap library. The capture
930 filter syntax follows the rules of the pcap library. This syntax is
931 different from the display filter syntax."
933 The capture filter syntax used by libpcap can be found in the
936 Q 5.6: I'm entering valid capture filters, but I still get "parse
939 A: There is a bug in some versions of libpcap/WinPcap that cause it to
940 report parse errors even for valid expressions if a previous filter
941 expression was invalid and got a parse error.
943 Try exiting and restarting Ethereal; if you are using a version of
944 libpcap/WinPcap with this bug, this will "erase" its memory of the
945 previous parse error. If the capture filter that got the "parse error"
946 now works, the earlier error with that filter was probably due to this
949 The bug was fixed in libpcap 0.6; 0.4[.x] and 0.5[.x] versions of
950 libpcap have this bug, but 0.6[.x] and later versions don't.
952 Versions of WinPcap prior to 2.3 are based on pre-0.6 versions of
953 libpcap, and have this bug; WinPcap 2.3 is based on libpcap 0.6.2, and
954 doesn't have this bug.
956 If you are running Ethereal on a UNIX-flavored platform, run "ethereal
957 -v", or select "About Ethereal..." from the "Help" menu in Ethereal,
958 to see what version of libpcap it's using. If it's not 0.6 or later,
959 you will need either to upgrade your OS to get a later version of
960 libpcap, or will need to build and install a later version of libpcap
961 from the tcpdump.org Web site and then recompile Ethereal from source
962 with that later version of libpcap.
964 If you are running Ethereal on Windows with a pre-2.3 version of
965 WinPcap, you will need to un-install WinPcap and then download and
968 Q 5.7: I saved a filter and tried to use its name to filter the
969 display, but I got an "Unexpected end of filter string" error.
971 A: You cannot use the name of a saved display filter as a filter. To
972 filter the display, you can enter a display filter expression - not
973 the name of a saved display filter - in the "Filter:" box at the
974 bottom of the display, and type the key or press the "Apply" button
975 (that does not require you to have a saved filter), or, if you want to
976 use a saved filter, you can press the "Filter:" button, select the
977 filter in the dialog box that pops up, and press the "OK" button.
979 Q 5.8: Why am I seeing lots of packets with incorrect TCP checksums?
981 A: If the packets that have incorrect TCP checksums are all being sent
982 by the machine on which Ethereal is running, this is probably because
983 the network interface on which you're capturing does TCP checksum
984 offloading. That means that the TCP checksum is added to the packet by
985 the network interface, not by the OS's TCP/IP stack; when capturing on
986 an interface, packets being sent by the host on which you're capturing
987 are directly handed to the capture interface by the OS, which means
988 that they are handed to the capture interface without a TCP checksum
991 The only way to prevent this from happening would be to disable TCP
992 checksum offloading, but
993 1. that might not even be possible on some OSes;
994 2. that could reduce networking performance significantly.
996 However, you can disable the check that Ethereal does of the TCP
997 checksum, so that it won't report any packets as having TCP checksum
998 errors, and so that it won't refuse to do TCP reassembly due to a
999 packet having an incorrect TCP checksum. That can be set as an
1000 Ethereal preference by selecting "Preferences" from the "Edit" menu,
1001 opening up the "Protocols" list in the left-hand pane of the
1002 "Preferences" dialog box, selecting "TCP", from that list, turning off
1003 the "Check the validity of the TCP checksum when possible" option,
1004 clicking "Save" if you want to save that setting in your preference
1005 file, and clicking "OK".
1007 It can also be set on the Ethereal or Tethereal command line with a -o
1008 tcp.check_checksum:false command-line flag, or manually set in your
1009 preferences file by adding a tcp.check_checksum:false line.
1011 Q 5.9: I've just installed Ethereal, and the traffic on my local LAN
1014 A: We have a collection of strange and exotic sample capture files at
1015 http://www.ethereal.com/sample/
1017 Q 5.10: When I run Ethereal on Solaris 8, it dies with a Bus Error
1020 A: Some versions of the GTK+ library from www.sunfreeware.org appear
1021 to be buggy, causing Ethereal to drop core with a Bus Error.
1022 Un-install those packages, and try getting the 1.2.10 version from
1023 that site, or the version from The Written Word, or the version from
1024 Sun's GNOME distribution, or the version from the supplemental
1025 software CD that comes with the Solaris media kit, or build it from
1026 source from the GTK Web site. Update the GLib library to the 1.2.10
1027 version, from the same source, as well. (If you get the 1.2.10
1028 versions from www.sunfreeware.org, and the problem persists,
1029 un-install them and try installing one of the other versions
1032 Similar problems may exist with older versions of GTK+ for earlier
1033 versions of Solaris.
1035 Q 5.11: When I run Ethereal on Windows NT, it dies with a Dr. Watson
1036 error, reporting an "Integer division by zero" exception, when I start
1039 A: In at least some case, this appears to be due to using the default
1040 VGA driver; if that's not the correct driver for your video card, try
1041 running the correct driver for your video card.
1043 Q 5.12: When I try to run Ethereal, it complains about
1044 sprint_realloc_objid being undefined.
1046 A: Ethereal can only be linked with version 4.2.2 or later of UCD
1047 SNMP. Your version of Ethereal was dynamically linked with such a
1048 version of UCD SNMP; however, you have an older version of UCD SNMP
1049 installed, which means that when Ethereal is run, it tries to link to
1050 the older version, and fails. You will have to replace that version of
1051 UCD SNMP with version 4.2.2 or a later version.
1053 Q 5.13: I'm running Ethereal on Linux; why do my time stamps have only
1054 100ms resolution, rather than 1us resolution?
1056 A: Ethereal gets time stamps from libpcap/WinPcap, and libpcap/WinPcap
1057 get them from the OS kernel, so Ethereal - and any other program using
1058 libpcap, such as tcpdump - is at the mercy of the time stamping code
1059 in the OS for time stamps.
1061 At least on x86-based machines, Linux can get high-resolution time
1062 stamps on newer processors with the Time Stamp Counter (TSC) register;
1063 for example, Intel x86 processors, starting with the Pentium Pro, and
1064 including all x86 processors since then, have had a TSC, and other
1065 vendors probably added the TSC at some point to their families of x86
1068 The Linux kernel must be configured with the CONFIG_X86_TSC option
1069 enabled in order to use the TSC. Make sure this option is enabled in
1072 In addition, some Linux distributions may have bugs in their versions
1073 of the kernel that cause packets not to be given high-resolution time
1074 stamps even if the TSC is enabled. See, for example, bug 61111 for Red
1075 Hat Linux 7.2. If your distribution has a bug such as this, you may
1076 have to run a standard kernel from kernel.org in order to get
1077 high-resolution time stamps.
1079 Q 5.14: I'm capturing packets on {Windows 95, Windows 98, Windows Me};
1080 why are the time stamps on packets wrong?
1082 A: This is due to a bug in WinPcap. The bug should be fixed in WinPcap
1085 Q 5.15: When I try to run Ethereal on Windows, it fails to run because
1086 it can't find packet.dll.
1088 A: In older versions of Ethereal, there were two binary distributions
1089 available for Windows, one that supported capturing packets, and one
1090 that didn't. The version that supported capturing packets required
1091 that you install the WinPcap driver; if you didn't install it, it
1092 would fail to run because it couldn't find packet.dll.
1094 The current version of Ethereal has only one binary distribution for
1095 Windows; that version will check whether WinPcap is installed and, if
1096 it's not, will disable support for packet capture.
1098 The WinPcap driver and libraries can be downloaded from the WinPcap
1099 Web site, the local mirror of the WinPcap Web site, or the
1100 Wiretapped.net mirror of the WinPcap site.
1102 Q 5.16: I'm running Ethereal on Windows; why does some network
1103 interface on my machine not show up in the list of interfaces in the
1104 "Interface:" field in the dialog box popped up by "Capture->Start",
1105 and/or why does Ethereal give me an error if I try to capture on that
1108 A: If you are running Ethereal on Windows NT 4.0, Windows 2000,
1109 Windows XP, or Windows Server, and this is the first time you have run
1110 a WinPcap-based program (such as Ethereal, or Tethereal, or WinDump,
1111 or Analyzer, or...) since the machine was rebooted, you need to run
1112 that program from an account with administrator privileges; once you
1113 have run such a program, you will not need administrator privileges to
1114 run any such programs until you reboot.
1116 If you are running on Windows 95/98/Me, or if you are running on
1117 Windows NT 4.0/2000/XP/Server and have administrator privileges or a
1118 WinPcap-based program has been run with those privileges since the
1119 machine rebooted, then note that Ethereal relies on the WinPcap
1120 library, on the WinPcap device driver, and on the facilities that come
1121 with the OS on which it's running in order to do captures.
1123 Therefore, if the OS, the WinPcap library, or the WinPcap driver don't
1124 support capturing on a particular network interface device, Ethereal
1125 won't be able to capture on that device.
1128 * 2.02 and earlier versions of the WinPcap driver and library that
1129 Ethereal uses for packet capture didn't support Token Ring
1130 interfaces; the current version, 2.3, does support Token Ring, and
1131 the current version of Ethereal works with (and, in fact,
1132 requires) WinPcap 2.1 or later.
1133 If you are having problems capturing on Token Ring interfaces, and
1134 you have WinPcap 2.02 or an earlier version of WinPcap installed,
1135 you should uninstall WinPcap, download and install the current
1136 version of WinPcap, and then install the latest version of
1138 * On Windows 95, 98, or Me, sometimes more than one interface will
1139 be given the same name; if that is the case, you will only be able
1140 to capture on one of those interfaces - it's not clear to which
1141 one the name, when used in a WinPcap-based application, will
1142 refer. For example, if you have a PPP serial interface and a VPN
1143 interface, they might show up with the same name, for example
1144 "ppp-mac", and if you try to capture on "ppp-mac", it might not
1145 capture on the interface you're currently using. In that case, you
1146 might, for example, have to remove the VPN interface from the
1147 system in order to capture on the PPP serial interface.
1148 * WinPcap doesn't support PPP WAN interfaces on Windows
1149 NT/2000/XP/Server, so Ethereal cannot capture packets on those
1150 devices when running on Windows NT/2000/XP/Server. Regular dial-up
1151 lines, ISDN lines, and various other lines such as T1/E1 lines are
1152 all PPP interfaces. This may cause the interface not to show up on
1153 the list of interfaces in the "Capture Options" dialog.
1154 * WinPcap prior to 3.0 does not support multiprocessor machines
1155 (note that machines with a single multi-threaded processor, such
1156 as Intel's new multi-threaded x86 processors, are multiprocessor
1157 machines as far as the OS and WinPcap are concerned), and recent
1158 2.x versions of WinPcap refuse to operate if they detect that
1159 they're running on a multiprocessor machine, which means that they
1160 may not show any network interfaces. You will need to use WinPcap
1161 3.0 to capture on a multiprocessor machine.
1163 If an interface doesn't show up in the list of interfaces in the
1164 "Interface:" field, and you know the name of the interface, try
1165 entering that name in the "Interface:" field and capturing on that
1168 If the attempt to capture on it succeeds, the interface is somehow not
1169 being reported by the mechanism Ethereal uses to get a list of
1170 interfaces; please report this to ethereal-dev@ethereal.com giving
1171 full details of the problem, including
1172 * the operating system you're using, and the version of that
1174 * the type of network device you're using.
1176 If you are having trouble capturing on a particular network interface,
1177 and you've made sure that (on platforms that require it) you've
1178 arranged that packet capture support is present, as per the above,
1179 first try capturing on that device with WinDump; see the WinDump Web
1180 site or the local mirror of the WinDump Web site for information on
1183 If you can capture on the interface with WinDump, send mail to
1184 ethereal-users@ethereal.com giving full details of the problem,
1186 * the operating system you're using, and the version of that
1188 * the type of network device you're using;
1189 * the error message you get from Ethereal.
1191 If you cannot capture on the interface with WinDump, this is almost
1192 certainly a problem with one or more of:
1193 * the operating system you're using;
1194 * the device driver for the interface you're using;
1195 * the WinPcap library and/or the WinPcap device driver;
1197 so first check the WinPcap FAQ, the local mirror of that FAQ, or the
1198 Wiretapped.net mirror of that FAQ, to see if your problem is mentioned
1199 there. If not, then see the WinPcap support page (or the local mirror
1200 of that page) - check the "Submitting bugs" section.
1202 You may also want to ask the ethereal-users@ethereal.com and the
1203 winpcap-users@winpcap.polito.it mailing lists to see if anybody
1204 happens to know about the problem and know a workaround or fix for the
1205 problem. (Note that you will have to subscribe to that list in order
1206 to be allowed to mail to it; see the WinPcap support page, or the
1207 local mirror of that page, for information on the mailing list.) In
1208 your mail, please give full details of the problem, as described
1209 above, and also indicate that the problem occurs with WinDump, not
1212 Q 5.17: I'm running on a UNIX-flavored OS; why does some network
1213 interface on my machine not show up in the list of interfaces in the
1214 "Interface:" field in the dialog box popped up by "Capture->Start",
1215 and/or why does Ethereal give me an error if I try to capture on that
1218 A: You may need to run Ethereal from an account with sufficient
1219 privileges to capture packets, such as the super-user account. Only
1220 those interfaces that Ethereal can open for capturing show up in that
1221 list; if you don't have sufficient privileges to capture on any
1222 interfaces, no interfaces will show up in the list.
1224 If you are running Ethereal from an account with sufficient
1225 privileges, then note that Ethereal relies on the libpcap library, and
1226 on the facilities that come with the OS on which it's running in order
1229 Therefore, if the OS or the libpcap library don't support capturing on
1230 a particular network interface device, Ethereal won't be able to
1231 capture on that device.
1233 On Linux, note that you need to have "packet socket" support enabled
1234 in your kernel; see the "Packet socket" item in the Linux
1235 "Configure.help" file.
1237 On BSD, note that you need to have BPF support enabled in your kernel;
1238 see the documentation for your system for information on how to enable
1239 BPF support (if it's not enabled by default on your system).
1241 On DEC OSF/1, Digital UNIX, or Tru64 UNIX, note that you need to have
1242 packet filtering support in your kernel; the doconfig command will
1243 allow you to configure and build a new kernel with that option.
1245 On Solaris, note that libpcap 0.6.2 and earlier didn't support Token
1246 Ring interfaces; the current version, 0.7.2, does support Token Ring,
1247 and the current version of Ethereal works with libcap 0.7.2 and later.
1249 If an interface doesn't show up in the list of interfaces in the
1250 "Interface:" field, and you know the name of the interface, try
1251 entering that name in the "Interface:" field and capturing on that
1254 If the attempt to capture on it succeeds, the interface is somehow not
1255 being reported by the mechanism Ethereal uses to get a list of
1256 interfaces; please report this to ethereal-dev@ethereal.com giving
1257 full details of the problem, including
1258 * the operating system you're using, and the version of that
1259 operating system (for Linux, give both the version number of the
1260 kernel and the name and version number of the distribution you're
1262 * the type of network device you're using.
1264 If you are having trouble capturing on a particular network interface,
1265 and you've made sure that (on platforms that require it) you've
1266 arranged that packet capture support is present, as per the above,
1267 first try capturing on that device with tcpdump.
1269 If you can capture on the interface with tcpdump, send mail to
1270 ethereal-users@ethereal.com giving full details of the problem,
1272 * the operating system you're using, and the version of that
1273 operating system (for Linux, give both the version number of the
1274 kernel and the name and version number of the distribution you're
1276 * the type of network device you're using;
1277 * the error message you get from Ethereal.
1279 If you cannot capture on the interface with tcpdump, this is almost
1280 certainly a problem with one or more of:
1281 * the operating system you're using;
1282 * the device driver for the interface you're using;
1283 * the libpcap library;
1285 so you should report the problem to the company or organization that
1286 produces the OS (in the case of a Linux distribution, report the
1287 problem to whoever produces the distribution).
1289 You may also want to ask the ethereal-users@ethereal.com and the
1290 tcpdump-workers@tcpdump.org mailing lists to see if anybody happens to
1291 know about the problem and know a workaround or fix for the problem.
1292 In your mail, please give full details of the problem, as described
1293 above, and also indicate that the problem occurs with tcpdump not just
1296 Q 5.18: I'm running Ethereal on Windows NT/2000/XP/Server; my machine
1297 has a PPP (dial-up POTS, ISDN, etc.) interface, and it shows up in the
1298 "Interface" item in the "Capture Options" dialog box. Why can no
1299 packets be sent on or received from that network while I'm trying to
1300 capture traffic on that interface?
1302 A: WinPcap doesn't support PPP WAN interfaces on Windows
1303 NT/2000/XP/Server; one symptom that may be seen is that attempts to
1304 capture in promiscuous mode on the interface cause the interface to be
1305 incapable of sending or receiving packets. You can disable promiscuous
1306 mode using the -p command-line flag or the item in the "Capture
1307 Preferences" dialog box, but this may mean that outgoing packets, or
1308 incoming packets, won't be seen in the capture.
1310 Q 5.19: I'm running Ethereal on Windows 95/98/Me, on a machine with
1311 more than one network adapter of the same type; Ethereal shows all of
1312 those adapters with the same name, but I can't use any of those
1313 adapters other than the first one.
1315 A: Unfortunately, Windows 95/98/Me gives the same name to multiple
1316 instances of the type of same network adapter. Therefore, WinPcap
1317 cannot distinguish between them, so a WinPcap-based application can
1318 capture only on the first such interface; Ethereal is a
1319 libpcap/WinPcap-based application.
1321 Q 5.20: I'm running Ethereal on Windows, and I'm not seeing any
1322 traffic being sent by the machine running Ethereal.
1324 A: If you are running some form of VPN client software, it might be
1325 causing this problem; people have seen this problem when they have
1326 Check Point's VPN software installed on their machine. If that's the
1327 cause of the problem, you will have to remove the VPN software in
1328 order to have Ethereal (or any other application using WinPcap) see
1329 outgoing packets; unfortunately, neither we nor the WinPcap developers
1330 know any way to make WinPcap and the VPN software work well together.
1332 Q 5.21: I'm trying to capture traffic but I'm not seeing any.
1334 A: Is the machine running Ethereal sending out any traffic on the
1335 network interface on which you're capturing, or receiving any traffic
1336 on that network, or is there any broadcast traffic on the network or
1337 multicast traffic to a multicast group to which the machine running
1340 If not, this may just be a problem with promiscuous sniffing, either
1341 due to running on a switched network or a dual-speed hub, or due to
1342 problems with the interface not supporting promiscuous mode; see the
1343 response to this earlier question.
1345 Otherwise, on Windows, see the response to this question and, on a
1346 UNIX-flavored OS, see the response to this question.
1348 Q 5.22: I have an XXX network card on my machine; if I try to capture
1349 on it, my machine crashes or resets itself.
1351 A: This is almost certainly a problem with one or more of:
1352 * the operating system you're using;
1353 * the device driver for the interface you're using;
1354 * the libpcap/WinPcap library and, if this is Windows, the WinPcap
1358 * if you are using Windows, see the WinPcap support page (or the
1359 local mirror of that page) - check the "Submitting bugs" section;
1360 * if you are using some Linux distribution, some version of BSD, or
1361 some other UNIX-flavored OS, you should report the problem to the
1362 company or organization that produces the OS (in the case of a
1363 Linux distribution, report the problem to whoever produces the
1366 Q 5.23: My machine crashes or resets itself when I select "Start" from
1367 the "Capture" menu or select "Preferences" from the "Edit" menu.
1369 A: Both of those operations cause Ethereal to try to build a list of
1370 the interfaces that it can open; it does so by getting a list of
1371 interfaces and trying to open them. There is probably an OS, driver,
1372 or, for Windows, WinPcap bug that causes the system to crash when this
1373 happens; see the previous question.
1375 Q 5.24: Does Ethereal work on Windows ME?
1377 A: Yes, but if you want to capture packets, you will need to install
1378 the latest version of WinPcap, as 2.02 and earlier versions of WinPcap
1379 didn't support Windows ME. You should also install the latest version
1380 of Ethereal as well.
1382 Q 5.25: Does Ethereal work on Windows XP?
1384 A: Yes, but if you want to capture packets, you will need to install
1385 the latest version of WinPcap, as 2.2 and earlier versions of WinPcap
1386 didn't support Windows XP.
1388 Q 5.26: Why doesn't Ethereal correctly identify RTP packets? It shows
1391 A: Ethereal can identify a UDP datagram as containing a packet of a
1392 particular protocol running atop UDP only if
1393 1. The protocol in question has a particular standard port number,
1394 and the UDP source or destination port number is that port
1395 2. Packets of that protocol can be identified by looking for a
1396 "signature" of some type in the packet - i.e., some data that, if
1397 Ethereal finds it in some particular part of a packet, means that
1398 the packet is almost certainly a packet of that type.
1399 3. Some other traffic earlier in the capture indicated that, for
1400 example, UDP traffic between two particular addresses and ports
1401 will be RTP traffic.
1403 RTP doesn't have a standard port number, so 1) doesn't work; it
1404 doesn't, as far as I know, have any "signature", so 2) doesn't work.
1406 That leaves 3). If there's RTSP traffic that sets up an RTP session,
1407 then, at least in some cases, the RTSP dissector will set things up so
1408 that subsequent RTP traffic will be identified. Currently, that's the
1409 only place we do that; there may be other places.
1411 However, there will always be places where Ethereal is simply
1412 incapable of deducing that a given UDP flow is RTP; a mechanism would
1413 be needed to allow the user to specify that a given conversation
1414 should be treated as RTP. As of Ethereal 0.8.16, such a mechanism
1415 exists; if you select a UDP or TCP packet, the right mouse button menu
1416 will have a "Decode As..." menu item, which will pop up a dialog box
1417 letting you specify that the source port, the destination port, or
1418 both the source and destination ports of the packet should be
1419 dissected as some particular protocol.
1421 Q 5.27: Why doesn't Ethereal show Yahoo Messenger packets in captures
1422 that contain Yahoo Messenger traffic?
1424 A: Ethereal only recognizes as Yahoo Messenger traffic packets to or
1425 from TCP port 3050 that begin with "YPNS", "YHOO", or "YMSG". TCP
1426 segments that start with the middle of a Yahoo Messenger packet that
1427 takes more than one TCP segment will not be recognized as Yahoo
1428 Messenger packets (even if the TCP segment also contains the beginning
1429 of another Yahoo Messenger packet).
1431 Q 5.28: Why do I get the error
1433 Gdk-ERROR **: Palettized display (256-colour) mode not supported on
1437 when I try to run Ethereal on Windows?
1439 A: Ethereal is built using the GTK+ toolkit, which supports most
1440 UNIX-flavored OSes, and also supports Windows; that toolkit doesn't
1441 support 256-color mode on Windows - it requires HiColor (16-bit
1442 colors) or more. If your display supports more than 256 colors, switch
1443 to a display mode with more colors; if it doesn't support more than
1444 256 colors, you will be unable to run Ethereal.
1446 Q 5.29: When I capture on Windows in promiscuous mode, I can see
1447 packets other than those sent to or from my machine; however, those
1448 packets show up with a "Short Frame" indication, unlike packets to or
1449 from my machine. What should I do to arrange that I see those packets
1452 A: In at least some cases, this appears to be the result of PGPnet
1453 running on the network interface on which you're capturing; turn it
1454 off on that interface.
1456 Q 5.30: How can I capture raw 802.11 packets, including non-data
1457 (management, beacon) packets?
1459 A: That would require that your 802.11 interface run in the mode
1460 called "monitor mode" or "RFMON mode". Not all operating systems
1461 support that and, even on operating systems that do support it, not
1462 all drivers, and thus not all cards, support it.
1464 Cisco Aironet cards:
1466 The only platforms that allow Ethereal to capture raw 802.11 packets
1467 on Cisco Aironet cards are:
1468 * Linux, with a 2.4.6 or later kernel;
1469 * FreeBSD 4.6 or later, as the driver in FreeBSD 4.5 has bugs that
1470 cause packets not to be captured correctly, and the driver in
1471 releases prior to 4.5 didn't support capturing raw packets.
1473 On FreeBSD, the ancontrol utility must be used; do not enable the full
1474 Aironet header via BPF, as Ethereal doesn't currently support that.
1476 On Linux with the driver in the 2.4.6 through 2.4.19 kernel, you will
1479 echo "Mode: rfmon" >/proc/driver/aironet/ethN/Config
1481 if your Aironet card is ethN. To capture traffic from any BSS, do
1483 echo "Mode: y" >/proc/driver/aironet/ethN/Config
1485 and to return to the normal mode, do
1487 echo "Mode: ess" >/proc/driver/aironet/ethN/Config
1489 On Linux with the driver in the 2.4.20 kernel, or with the CVS drivers
1490 from the airo-linux SourceForge site, you will have to capture on the
1491 wifiN interface if your Aironet card is ethN, after running the
1492 commands listed above.
1494 In all of those cases, Ethereal would have to be linked with libpcap
1495 0.7.1 or later; this means that most Ethereal binary packages won't
1496 work unless they're statically linked with libpcap 0.7.1 or later, or
1497 they're dynamically linked with libpcap and your system has a libpcap
1498 0.7.1 or later shared library installed (note that libpcap source
1499 package from tcpdump.org does not build shared libraries). Some binary
1500 packaging mechanisms might make it difficult to install Ethereal
1501 binary packages built to depend on older libpcap binary packages if
1502 you have a newer libpcap binary package installed; the installer
1503 programs for those packaging mechanisms might support disabling
1504 dependency checking so that they will install Ethereal even though a
1505 newer version of libpcap is installed.
1507 Cards using the Prism II chip set (see this page of Linux 802.11
1508 information for details on wireless cards, including information on
1509 the chips they use):
1511 You can capture raw 802.11 packets with Prism II cards on Linux
1512 systems with the 0.1.14-pre6 or later version of the linux-wlan-ng
1513 drivers (see the linux-wlan page, and the linux-wlan-ng tarball
1516 Those require either Solomon Peachy's patch to libpcap 0.7.1 (see his
1517 libpcap-0.7.1-prism.diff file, or his RPMs of that version of
1518 libpcap), or the current CVS version of libpcap, which includes his
1519 patch (download it from the "Current Tar files" section of the
1520 tcpdump.org Web site). If you apply his patches to libpcap 0.7.1 and
1521 rebuild and install libpcap, or if you build and install the current
1522 CVS version of libpcap, you would have to rebuild Ethereal from
1523 source, linking it with that new version of libpcap; an Ethereal
1524 binary package would not work. Ethereal binary packages might work if
1525 you install the libpcap-0.7.1-1prism.i386.rpm RPM, as it might install
1526 a libpcap shared library in place of the one on your system.
1528 You may have to run a command to put the interface into monitor mode,
1529 or to change other interface settings, and you might have to capture
1530 on a wlanN interface rather than a ethN interface, in order to capture
1531 raw 802.11 packets. The interface settings are available in your
1532 wlan-ng.conf file. See the wlan-ng FAQ for additional information.
1534 On other platforms, capturing raw 802.11 packets on Prism II cards is
1535 not currently supported.
1537 Orinoco Silver and Gold cards:
1539 On Linux systems, there are patches on the Orinoco Monitor Mode Patch
1540 Page that should allow you to do capture raw 802.11 packets. You will
1541 have to determine which version of the driver you have, and select the
1544 Note that the page indicates that not all versions of the Orinoco
1545 firmware support this patch. It says, for some versions of the patch,
1546 "This patch should allow monitor mode with v8.10 firmware (untested w/
1547 8.42);" if you have version 8.10 or later firmware on your Orinoco
1548 cards, you might have to use those patches, with the corresponding
1549 versions of the Orinoco driver, in order to run in monitor mode.
1551 That patch is written for the drivers included with the pcmcia-cs
1552 drivers, but works equally well for the Orinoco drivers provided with
1553 Linux kernels up to 2.4.20. To apply a patch to your kernel drivers,
1554 simply copy the orinoco-09b-patch.diff file to the
1555 /usr/src/linux/drivers/net directory and patch according to the
1556 directions on the Orinoco Monitor Mode Patch Page. You can double-
1557 check the version of the Orinoco drivers that shipped with your kernel
1558 by examining the first few lines of the orinoco.c file.
1560 Te Orinoco patches require either Solomon Peachy's patch to libpcap
1561 0.7.1 (see his libpcap-0.7.1-prism.diff file, or his RPMs of that
1562 version of libpcap), or the current CVS version of libpcap, which
1563 includes his patch (download it from the "Current Tar files" section
1564 of the tcpdump.org Web site). If you apply his patches to libpcap
1565 0.7.1 and rebuild and install libpcap, or if you build and install the
1566 current CVS version of libpcap, you would have to rebuild Ethereal
1567 from source, linking it with that new version of libpcap; an Ethereal
1568 binary package would not work. Ethereal binary packages might work if
1569 you install the libpcap-0.7.1-1prism.i386.rpm RPM, as it might install
1570 a libpcap shared library in place of the one on your system.
1572 On other platforms, capturing raw 802.11 packets on Orinoco cards is
1573 not currently supported.
1575 Other 802.11 interfaces:
1577 With other 802.11 interfaces, no platform allows Ethereal to capture
1578 raw 802.11 packets, as far as we know. If you know of other 802.11
1579 interfaces that are supported (note that there are many "Prism II
1580 cards", so your card might be a Prism II card), please let us know,
1581 and include URLs for sites containing any necessary patches to add
1584 On platforms that don't allow Ethereal to capture raw 802.11 packets,
1585 the 802.11 network will appear like an Ethernet to Ethereal.
1587 Q 5.31: How can I capture packets with CRC errors?
1589 A: Ethereal can capture only the packets that the packet capture
1590 library - libpcap on UNIX-flavored OSes, and the WinPcap port to
1591 Windows of libpcap on Windows - can capture, and libpcap/WinPcap can
1592 capture only the packets that the OS's raw packet capture mechanism
1593 (or the WinPcap driver, and the underlying OS networking code and
1594 network interface drivers, on Windows) will allow it to capture.
1596 Unless the OS can be configured to supply packets with errors such as
1597 invalid CRCs to the raw packet capture mechanism, Ethereal - and other
1598 programs that capture raw packets, such as tcpdump - cannot capture
1599 those packets. You will have to determine whether your OS can be so
1600 configured, configure it if possible, and make whatever changes to
1601 libpcap and the packet capture program you're using are necessary to
1602 support capturing those packets.
1604 Q 5.32: How can I capture entire frames, including the FCS?
1606 A: Ethereal can't capture any data that the packet capture library -
1607 libpcap on UNIX-flavored OSes, and the WinPcap port to Windows of
1608 libpcap on Windows - can capture, and libpcap/WinPcap can capture only
1609 the data that the OS's raw packet capture mechanism (or the WinPcap
1610 driver, and the underlying OS networking code and network interface
1611 drivers, on Windows) will allow it to capture.
1613 For any particular link-layer network type, unless the OS supplies the
1614 FCS of a frame as part of the frame, or can be configured to supply
1615 the FCS of a frame as part of the frame, Ethereal - and other programs
1616 that capture raw packets, such as tcpdump - cannot capture the FCS of
1617 a frame. You will have to determine whether your OS can be so
1618 configured, configure it if possible, and make whatever changes to
1619 libpcap and the packet capture program you're using are necessary to
1620 support capturing the FCS of a frame. Most if not all OSes probably do
1621 not support capturing the FCS of a frame on Ethernet, and probably do
1622 not support it on most other link-layer types.
1624 Q 5.33: Ethereal hangs after I stop a capture.
1626 A: The most likely reason for this is that Ethereal is trying to look
1627 up an IP address in the capture to convert it to a name (so that, for
1628 example, it can display the name in the source address or destination
1629 address columns), and that lookup process is taking a very long time.
1631 Ethereal calls a routine in the OS of the machine on which it's
1632 running to convert of IP addresses to the corresponding names. That
1633 routine probably does one or more of:
1634 * a search of a system file listing IP addresses and names;
1635 * a lookup using DNS;
1636 * on UNIX systems, a lookup using NIS;
1637 * on Windows systems, a NetBIOS-over-TCP query.
1639 If a DNS server that's used in an address lookup is not responding,
1640 the lookup will fail, but will only fail after a timeout while the
1641 system routine waits for a reply.
1643 In addition, on Windows systems, if the DNS lookup of the address
1644 fails, either because the server isn't responding or because there are
1645 no records in the DNS that could be used to map the address to a name,
1646 a NetBIOS-over-TCP query will be made. That query involves sending a
1647 message to the NetBIOS-over-TCP name service on that machine, asking
1648 for the name and other information about the machine. If the machine
1649 isn't running software that responds to those queries - for example,
1650 many non-Windows machines wouldn't be running that software - the
1651 lookup will only fail after a timeout. Those timeouts can cause the
1652 lookup to take a long time.
1654 If you disable network address-to-name translation - for example, by
1655 turning off the "Enable network name resolution" option in the "Name
1656 resolution" options in the dialog box you get by selecting
1657 "Preferences" from the "Edit" menu - the lookups of the address won't
1658 be done, which may speed up the process of reading the capture file
1659 after the capture is stopped. You can make that setting the default by
1660 using the "Save" button in that dialog box; note that this will save
1661 all your current preference settings.
1663 If Ethereal hangs when reading a capture even with network name
1664 resolution turned off, there might, for example, be a bug in one of
1665 Ethereal's dissectors for a protocol causing it to loop infinitely.
1666 The bug should be reported to the Ethereal developers' mailing list at
1667 ethereal-dev@ethereal.com.
1669 On UNIX-flavored OSes, please try to force Ethereal to dump core, by
1670 sending it a SIGABRT signal (usually signal 6) with the kill command,
1671 and then get a stack trace if you have a debugger installed. A stack
1672 trace can be obtained by using your debugger (gdb in this example),
1673 the Ethereal binary, and the resulting core file. Here's an example of
1674 how to use the gdb command backtrace to do so.
1677 ..... prints the stack trace
1681 The core dump file may be named "ethereal.core" rather than "core" on
1682 some platforms (e.g., BSD systems)
1684 Also, if at all possible, please send a copy of the capture file that
1685 caused the problem; when capturing packets, Ethereal normally writes
1686 captured packets to a temporary file, which will probably be in /tmp
1687 or /var/tmp on UNIX-flavored OSes and \TEMP on Windows, so the capture
1688 file will probably be there. It will have a name beginning with ether,
1689 with some mixture of letters and numbers after that. Please don't send
1690 a trace file greater than 1 MB when compressed. If the trace file
1691 contains sensitive information (e.g., passwords), then please do not
1694 Q 5.34: How can I search for, or filter, packets that have a
1695 particular string anywhere in them?
1697 A: Currently, you can't.
1699 That's a feature that would be hard to implement in capture filters
1700 without changes to the capture filter code, which, on many platforms,
1701 is in the OS kernel and, on other platforms, is in the libpcap
1704 It would be easier to implement in display filters, but it hasn't been
1705 implemented yet. It would be best implemented as a display filter
1706 "string match" operator, which would let you check not only the entire
1707 packet for a string, but check portions of the packet for a string. It
1708 should probably not use a naive string matching mechanism, as there
1709 are mechanisms much faster than the naive one.
1712 Support can be found on the ethereal-users[AT]ethereal.com mailing
1714 For corrections/additions/suggestions for this page, please send email
1715 to: ethereal-web[AT]ethereal.com
1716 Last modified: Sat, July 19 2003.
git.samba.org / obnox / wireshark / wip.git / blob