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 sniffer 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 I'm running Ethereal on Linux; why do my time stamps have only
91 100ms resolution, rather than 1us resolution?
93 5.12 I'm capturing packets on {Windows 95, Windows 98, Windows Me};
94 why are the time stamps on packets wrong?
96 5.13 When I try to run Ethereal on Windows, it fails to run because it
97 can't find packet.dll.
99 5.14 I'm running on Windows; why does some network interface on my
100 machine not show up in the list of interfaces in the "Interface:"
101 field in the dialog box popped up by "Capture->Start", and/or why does
102 Ethereal give me an error if I try to capture on that interface?
104 5.15 I'm running on a UNIX-flavored OS; why does some network
105 interface on my machine not show up in the list of interfaces in the
106 "Interface:" field in the dialog box popped up by "Capture->Start",
107 and/or why does Ethereal give me an error if I try to capture on that
110 5.16 I'm running Ethereal on Windows NT/2000/XP/Server; my machine has
111 a PPP (dial-up POTS, ISDN, etc.) interface, and it shows up in the
112 "Interface" item in the "Capture Options" dialog box. Why can no
113 packets be sent on or received from that network while I'm trying to
114 capture traffic on that interface?
116 5.17 I'm running Ethereal on Windows 95/98/Me, on a machine with more
117 than one network adapter of the same type; Ethereal shows all of those
118 adapters with the same name, but I can't use any of those adapters
119 other than the first one.
121 5.18 I'm running Ethereal on Windows, and I'm not seeing any traffic
122 being sent by the machine running Ethereal.
124 5.19 I have an XXX network card on my machine; if I try to capture on
125 it, my machine crashes or resets itself.
127 5.20 My machine crashes or resets itself when I select "Start" from
128 the "Capture" menu or select "Preferences" from the "Edit" menu.
130 5.21 Does Ethereal work on Windows ME?
132 5.22 Does Ethereal work on Windows XP?
134 5.23 Why doesn't Ethereal correctly identify RTP packets? It shows
137 5.24 Why doesn't Ethereal show Yahoo Messenger packets in captures
138 that contain Yahoo Messenger traffic?
140 5.25 Why do I get the error
142 Gdk-ERROR **: Palettized display (256-colour) mode not supported on
146 when I try to run Ethereal on Windows?
148 5.26 When I capture on Windows in promiscuous mode, I can see packets
149 other than those sent to or from my machine; however, those packets
150 show up with a "Short Frame" indication, unlike packets to or from my
151 machine. What should I do to arrange that I see those packets in their
154 5.27 How can I capture raw 802.11 packets, including non-data
155 (management, beacon) packets?
157 5.28 How can I capture packets with CRC errors?
159 5.29 How can I capture entire frames, including the FCS?
161 5.30 Ethereal hangs after I stop a capture.
163 5.31 How can I search for, or filter, packets that have a particular
164 string anywhere in them?
167 Q 1.1: Where can I get help?
169 A: Support is available on the ethereal-users mailing list.
170 Subscription information and archives for all of Ethereal's mailing
171 lists can be found at http://www.ethereal.com/lists
173 Q 1.2: What protocols are currently supported?
175 A: There are currently 366 supported protocols and media, listed
176 below. Descriptions can be found in the ethereal(1) man page.
179 802.1x Authentication
180 AFS (4.0) Replication Server call declarations
181 AOL Instant Messenger
188 AVS WLAN Capture header
189 Ad hoc On-demand Distance Vector Routing Protocol
190 Ad hoc On-demand Distance Vector Routing Protocol v6
191 Address Resolution Protocol
192 Aggregate Server Access Protocol
193 Andrew File System (AFS)
194 Apache JServ Protocol v1.3
195 AppleTalk Filing Protocol
196 AppleTalk Session Protocol
197 AppleTalk Transaction Protocol packet
198 Appletalk Address Resolution Protocol
199 Async data over ISDN (V.120)
200 Authentication Header
201 BACnet Virtual Link Control
203 Banyan Vines Fragmentation Protocol
205 Blocks Extensible Exchange Protocol
209 Border Gateway Protocol
210 Building Automation and Control Network APDU
211 Building Automation and Control Network NPDU
212 CDS Clerk Server Calls
213 Check Point High Availability Protocol
216 Cisco Discovery Protocol
217 Cisco Group Management Protocol
219 Cisco Hot Standby Router Protocol
221 Cisco Interior Gateway Routing Protocol
225 CoSine IPNOS L2 debug output
226 Common Open Policy Service
227 Common Unix Printing System (CUPS) Browsing Protocol
229 DCE Distributed Time Service Local Server
230 DCE Distributed Time Service Provider
233 DCE Security ID Mapper
235 DCE/RPC CDS Solicitation
236 DCE/RPC Conversation Manager
237 DCE/RPC Endpoint Mapper
239 DCE/RPC FLDB UBIK TRANSFER
240 DCE/RPC FLDB UBIKVOTE
245 DCE/RPC Remote Management
246 DCE/RPC Repserver Calls
247 DCE/RPC TokenServer Calls
250 DCOM Remote Activation
251 DEC Spanning Tree Protocol
253 DNS Control Program Server
256 Data Stream Interface
257 Datagram Delivery Protocol
259 Distance Vector Multicast Routing Protocol
260 Distributed Checksum Clearinghouse Prototocl
262 Dynamic DNS Tools Protocol
263 Encapsulating Security Payload
264 Enhanced Interior Gateway Routing Protocol
267 Extensible Authentication Protocol
269 FC Fabric Configuration Server
273 Fiber Distributed Data Interface
275 Fibre Channel Common Transport
276 Fibre Channel Fabric Zone Server
277 Fibre Channel Name Server
278 Fibre Channel Protocol for SCSI
280 File Transfer Protocol (FTP)
281 Financial Information eXchange Protocol
284 GARP Multicast Registration Protocol
285 GARP VLAN Registration Protocol
286 GPRS Tunneling Protocol
287 GPRS Tunnelling Protocol v0
288 GPRS Tunnelling Protocol v1
289 General Inter-ORB Protocol
290 Generic Routing Encapsulation
291 Generic Security Service Application Program Interface
293 HP Extended Local-Link Control
294 HP Remote Maintenance Protocol
295 Hummingbird NFS Daemon
297 Hypertext Transfer Protocol
299 IEEE 802.11 wireless LAN
300 IEEE 802.11 wireless LAN management frame
303 IP Payload Compression
305 IPX Routing Information Protocol
307 ISDN Q.921-User Adaptation Layer
309 ISO 10589 ISIS InTRA Domain Routeing Information Exchange Protocol
310 ISO 8073 COTP Connection-Oriented Transport Protocol
311 ISO 8473 CLNP ConnectionLess Network Protocol
312 ISO 8602 CLTP ConnectionLess Transport Protocol
313 ISO 9542 ESIS Routeing Information Exchange Protocol
314 ITU-T Recommendation H.261
315 Inter-Access-Point Protocol
317 Internet Cache Protocol
318 Internet Content Adaptation Protocol
319 Internet Control Message Protocol
320 Internet Control Message Protocol v6
321 Internet Group Management Protocol
322 Internet Message Access Protocol
323 Internet Printing Protocol
325 Internet Protocol Version 6
327 Internet Security Association and Key Management Protocol
328 Internetwork Packet eXchange
333 Label Distribution Protocol
334 Layer 2 Tunneling Protocol
335 Lightweight Directory Access Protocol
336 Line Printer Daemon Protocol
337 Link Access Procedure Balanced (LAPB)
338 Link Access Procedure Balanced Ethernet (LAPBETHER)
339 Link Access Procedure, Channel D (LAPD)
340 Link Aggregation Control Protocol
341 Link Management Protocol (LMP)
342 Linux cooked-mode capture
343 Local Management Interface
344 LocalTalk Link Access Protocol
346 Lucent/Ascend debug output
348 MMS Message Encapsulation
350 MSN Messenger Service
351 MSNIP: Multicast Source Notification of Interest Protocol
352 MTP 2 Transparent Proxy
353 MTP 2 User Adaptation Layer
354 MTP 3 User Adaptation Layer
355 MTP2 Peer Adaptation Layer
356 Message Transfer Part Level 2
357 Message Transfer Part Level 3
358 Message Transfer Part Level 3 Management
359 Microsoft Distributed File System
360 Microsoft Exchange MAPI
361 Microsoft Local Security Architecture
362 Microsoft Local Security Architecture (Directory Services)
363 Microsoft Network Logon
365 Microsoft Security Account Manager
366 Microsoft Server Service
367 Microsoft Spool Subsystem
368 Microsoft Telephony API Service
369 Microsoft Windows Browser Protocol
370 Microsoft Windows Lanman Remote API Protocol
371 Microsoft Windows Logon Protocol
372 Microsoft Workstation Service
377 MultiProtocol Label Switching Header
378 Multicast Router DISCovery protocol
379 Multicast Source Discovery Protocol
386 NTLM Secure Service Provider
387 Name Binding Protocol
388 Name Management Protocol over IPX
390 NetBIOS Datagram Service
392 NetBIOS Session Service
394 NetWare Core Protocol
395 Network Data Management Protocol
397 Network Lock Manager Protocol
398 Network News Transfer Protocol
399 Network Status Monitor CallBack Protocol
400 Network Status Monitor Protocol
401 Network Time Protocol
402 Novell Distributed Print System
404 Open Shortest Path First
405 OpenBSD Encapsulating device
406 OpenBSD Packet Filter log file
408 PPP Bandwidth Allocation Control Protocol
409 PPP Bandwidth Allocation Protocol
410 PPP CDP Control Protocol
411 PPP Callback Control Protocol
412 PPP Challenge Handshake Authentication Protocol
413 PPP Compressed Datagram
414 PPP Compression Control Protocol
415 PPP IP Control Protocol
416 PPP IPv6 Control Protocol
417 PPP Link Control Protocol
418 PPP MPLS Control Protocol
419 PPP Multilink Protocol
421 PPP Password Authentication Protocol
423 PPP-over-Ethernet Discovery
424 PPP-over-Ethernet Session
425 PPPMux Control Protocol
426 Point-to-Point Protocol
427 Point-to-Point Tunnelling Protocol
430 Pragmatic General Multicast
432 Privilege Server operations
433 Protocol Independent Multicast
436 Quake II Network Protocol
437 Quake III Arena Network Protocol
438 Quake Network Protocol
439 QuakeWorld Network Protocol
440 Qualified Logical Link Control
445 RSYNC File Synchroniser
447 Radio Access Network Application Part
450 Real Time Streaming Protocol
451 Real-Time Transport Protocol
452 Real-time Transport Control Protocol
453 Registry Server Attributes Manipulation Interface
454 Registry server administration operations.
455 Remote Override interface
456 Remote Procedure Call
461 Remote sec_login preauth interface.
462 Resource ReserVation Protocol (RSVP)
464 Routing Information Protocol
465 Routing Table Maintenance Protocol
469 SMB (Server Message Block Protocol)
470 SMB MailSlot Protocol
473 SNMP Multiplex Protocol
476 SS7 SCCP-User Adaptation Layer
480 Sequenced Packet eXchange
481 Service Advertisement Protocol
482 Service Location Protocol
483 Session Announcement Protocol
484 Session Description Protocol
485 Session Initiation Protocol
486 Short Message Peer to Peer
487 Signalling Connection Control Part
488 Signalling Connection Control Part Management
489 Simple Mail Transfer Protocol
490 Simple Network Management Protocol
492 Skinny Client Control Protocol
493 SliMP3 Communication Protocol
495 Spanning Tree Protocol
497 Stream Control Transmission Protocol
498 Synchronous Data Link Control (SDLC)
500 Systems Network Architecture
501 Systems Network Architecture XID
506 Tazmen Sniffer Protocol
509 Time Synchronization Protocol
511 Token-Ring Media Access Control
512 Transmission Control Protocol
513 Transparent Network Substrate Protocol
514 Trivial File Transfer Protocol
515 Universal Computer Protocol
516 User Datagram Protocol
517 Virtual Router Redundancy Protocol
518 Virtual Trunking Protocol
520 Web Cache Coordination Protocol
521 Wellfleet Breath of Life
522 Wellfleet Compression
526 Wireless Session Protocol
527 Wireless Transaction Protocol
528 Wireless Transport Layer Security
529 X Display Manager Control Protocol
535 Yahoo Messenger Protocol
536 Yahoo YMSG Messenger Protocol
540 Yellow Pages Transfer
542 Zone Information Protocol
545 Q 1.3: Are there any plans to support {your favorite protocol}?
547 A: Support for particular protocols is added to Ethereal as a result
548 of people contributing that support; no formal plans for adding
549 support for particular protocols in particular future releases exist.
551 Q 1.4: Can Ethereal read capture files from {your favorite network
554 A: Support for particular protocols is added to Ethereal as a result
555 of people contributing that support; no formal plans for adding
556 support for particular protocols in particular future releases exist.
558 If a network analyzer writes out files in a format already supported
559 by Ethereal (e.g., in libpcap format), Ethereal may already be able to
560 read them, unless the analyzer has added its own proprietary
561 extensions to that format.
563 If a network analyzer writes out files in its own format, or has added
564 proprietary extensions to another format, in order to make Ethereal
565 read captures from that network analyzer, we would either have to have
566 a specification for the file format, or the extensions, sufficient to
567 give us enough information to read the parts of the file relevant to
568 Ethereal, or would need at least one capture file in that format AND a
569 detailed textual analysis of the packets in that capture file (showing
570 packet time stamps, packet lengths, and the top-level packet header)
571 in order to reverse-engineer the file format.
573 Note that there is no guarantee that we will be able to
574 reverse-engineer a capture file format.
576 Q 1.5: What devices can Ethereal use to capture packets?
578 A: Ethereal can read live data from Ethernet, Token-Ring, FDDI, serial
579 (PPP and SLIP) (if the OS on which it's running allows Ethereal to do
580 so), 802.11 wireless LAN (if the OS on which it's running allows
581 Ethereal to do so), ATM connections (if the OS on which it's running
582 allows Ethereal to do so), and the "any" device supported on Linux by
583 recent versions of libpcap. See the list of supported capture media on
584 various OSes for details (several items in there say "Unknown", which
585 doesn't mean "Ethereal can't capture on them", it means "we don't know
586 whether it can capture on them"; we expect that it will be able to
587 capture on many of them, but we haven't tried it ourselves - if you
588 try one of those types and it works, please send an update to
589 ethereal-web[AT]ethereal.com).
591 It can also read a variety of capture file formats, including:
594 * Shomiti/Finisar Surveyor
596 * DOS-based Sniffer (compressed and uncompressed)
599 * NetXray and Windows-based Sniffer
600 * EtherPeek/TokenPeek/AiroPeek
601 * RADCOM WAN/LAN analyzer
602 * Lucent/Ascend debug output
603 * Toshiba ISDN router "snoop" output
605 * ISDN4BSD "i4btrace" utility.
607 * pppd log files (pppdump format)
610 * Visual Networks' Visual UpTime
613 so that it can read traces from various network types, as captured by
614 other applications or equipment, even if it cannot itself capture on
617 Q 1.6: How do you pronounce Ethereal? Where did the name come from?
619 A: The English pronunciation can be found in Merriam-Webster's online
621 http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=ethereal.
623 According to the book "Computer Networks" by Andrew Tannenbaum,
624 Ethernet was named after the "luminiferous ether" which was once
625 thought to carry electromagnetic radiation. Taking that into
626 consideration, Ethereal seemed like an appropriate name for an
630 Q 2.1: I downloaded the Win32 installer, but when I try to run it, I
633 A: The program you used to download it may have downloaded it
634 incorrectly. Web browsers sometimes may do this.
636 Try downloading it with, for example:
637 * Wget, for which Windows binaries are available on the SunSITE FTP
638 server at sunsite.tk or Heiko Herold's windows wget spot - wGetGUI
639 offers a GUI interface that uses wget;
640 * WS_FTP from Ipswitch,
641 * the ftp command that comes with Windows.
643 If you use the ftp command, make sure you do the transfer in binary
644 mode rather than ASCII mode, by using the binary command before
645 transferring the file.
647 Q 2.2: When I try to download the WinPcap driver and library, I can't
648 get to the WinPcap Web site.
650 A: As is the case with all Web sites, that site won't necessarily
651 always be accessible; the server may be down due to a problem or down
652 for maintenance, or there may be a networking problem between you and
653 the server. You should try again later, or try the local mirror or the
654 Wiretapped.net mirror.
657 Q 3.1: I installed an Ethereal RPM, but Ethereal doesn't seem to be
658 installed; only Tethereal is installed.
660 A: Red Hat RPMs for Ethereal put only the non-GUI components into the
661 ethereal RPM, the fact that Ethereal is a GUI program nonwithstanding;
662 there's a separate ethereal-gnome RPM that includes GUI components
663 such as Ethereal itself, the fact that Ethereal doesn't use GNOME
664 nonwithstanding. Find the ethereal-gnome RPM, and install that also.
667 Q 4.1: The configure script can't find pcap.h or bpf.h, but I have
670 A: Are you sure pcap.h and bpf.h are installed? The official
671 distribution of libpcap only installs the libpcap.a library file when
672 "make install" is run. To install pcap.h and bpf.h, you must run "make
673 install-incl". If you're running Debian or Redhat, make sure you have
674 the "libpcap-dev" or "libpcap-devel" packages installed.
676 It's also possible that pcap.h and bpf.h have been installed in a
677 strange location. If this is the case, you may have to tweak
680 Q 4.2: Why do I get the error
682 dftest_DEPENDENCIES was already defined in condition TRUE, which
683 implies condition HAVE_PLUGINS_TRUE
685 when I try to build Ethereal from CVS or a CVS snapshot?
687 A: You probably have automake 1.5 installed on your machine (the
688 command automake --version will report the version of automake on your
689 machine). There is a bug in that version of automake that causes this
690 problem; upgrade to a later version of automake (1.6 or later).
692 Q 4.3: The link fails with a number of "Output line too long."
693 messages followed by linker errors.
695 A: The version of the sed command on your system is incapable of
696 handling very long lines. On Solaris, for example, /usr/bin/sed has a
697 line length limit too low to allow libtool to work; /usr/xpg4/bin/sed
698 can handle it, as can GNU sed if you have it installed.
700 On Solaris, changing your command search path to search /usr/xpg4/bin
701 before /usr/bin should make the problem go away; on any platform on
702 which you have this problem, installing GNU sed and changing your
703 command path to search the directory in which it is installed before
704 searching the directory with the version of sed that came with the OS
705 should make the problem go away.
707 Q 4.4: The link fails on Solaris because plugin_list is undefined.
709 A: This appears to be due to a problem with some versions of the GTK+
710 and GLib packages from www.sunfreeware.org; un-install those packages,
711 and try getting the 1.2.10 versions from that site, or the versions
712 from The Written Word, or the versions from Sun's GNOME distribution,
713 or the versions from the supplemental software CD that comes with the
714 Solaris media kit, or build them from source from the GTK Web site.
715 Then re-run the configuration script, and try rebuilding Ethereal. (If
716 you get the 1.2.10 versions from www.sunfreeware.org, and the problem
717 persists, un-install them and try installing one of the other versions
720 Q 4.5: The build fails on Windows because of conflicts between
721 winsock.h and winsock2.h.
723 A: As of Ethereal 0.9.5, you must install WinPcap 2.3 or later, and
724 the corresponding version of the developer's pack, in order to be able
725 to compile Ethereal; it will not compile with older versions of the
726 developer's pack. The symptoms of this failure are conflicts between
727 definitions in winsock.h and in winsock2.h; Ethereal uses winsock2.h,
728 but pre-2.3 versions of the WinPcap developer's packet use winsock.h.
729 (2.3 uses winsock2.h, so if Ethereal were to use winsock.h, it would
730 not be able to build with current versions of the WinPcap developer's
733 Note that the installed version of the developer's pack should be the
734 same version as the version of WinPcap you have installed.
737 Q 5.1: When I use Ethereal to capture packets, I see only packets to
738 and from my machine, or I'm not seeing all the traffic I'm expecting
739 to see from or to the machine I'm trying to monitor.
741 A: This might be because the interface on which you're capturing is
742 plugged into a switch; on a switched network, unicast traffic between
743 two ports will not necessarily appear on other ports - only broadcast
744 and multicast traffic will be sent to all ports.
746 Note that even if your machine is plugged into a hub, the "hub" may be
747 a switched hub, in which case you're still on a switched network.
749 Note also that on the Linksys Web site, they say that their
750 auto-sensing hubs "broadcast the 10Mb packets to the port that operate
751 at 10Mb only and broadcast the 100Mb packets to the ports that operate
752 at 100Mb only", which would indicate that if you sniff on a 10Mb port,
753 you will not see traffic coming sent to a 100Mb port, and vice versa.
754 This problem has also been reported for Netgear dual-speed hubs, and
755 may exist for other "auto-sensing" or "dual-speed" hubs.
757 Some switches have the ability to replicate all traffic on all ports
758 to a single port so that you can plug your sniffer into that single
759 port to sniff all traffic. You would have to check the documentation
760 for the switch to see if this is possible and, if so, to see how to do
761 this. See, for example:
762 * this documentation from Cisco on the Switched Port Analyzer (SPAN)
763 feature on Catalyst switches;
764 * documentation from HP on how to set "monitoring"/"mirroring" on
765 ports on the console for HP Advancestack Switch 208 and 224;
766 * the "Network Monitoring Port Features" section of chapter 6 of
767 documentation from HP for HP ProCurve Switches 1600M, 2424M,
770 Note also that many firewall/NAT boxes have a switch built into them;
771 this includes many of the "cable/DSL router" boxes. If you have a box
772 of that sort, that has a switch with some number of Ethernet ports
773 into which you plug machines on your network, and another Ethernet
774 port used to connect to a cable or DSL modem, you can, at least, sniff
775 traffic between the machines on your network and the Internet by
776 plugging the Ethernet port on the router going to the modem, the
777 Ethernet port on the modem, and the machine on which you're running
778 Ethereal into a hub (make sure it's not a switching hub, and that, if
779 it's a dual-speed hub, all three of those ports are running at the
782 If your machine is not plugged into a switched network or a dual-speed
783 hub, or it is plugged into a switched network but the port is set up
784 to have all traffic replicated to it, the problem might be that the
785 network interface on which you're capturing doesn't support
786 "promiscuous" mode, or because your OS can't put the interface into
787 promiscuous mode. Normally, network interfaces supply to the host
789 * packets sent to one of that host's link-layer addresses;
791 * multicast packets sent to a multicast address that the host has
792 configured the interface to accept.
794 Most network interfaces can also be put in "promiscuous" mode, in
795 which they supply to the host all network packets they see. Ethereal
796 will try to put the interface on which it's capturing into promiscuous
797 mode unless the "Capture packets in promiscuous mode" option is turned
798 off in the "Capture Options" dialog box, and Tethereal will try to put
799 the interface on which it's capturing into promiscuous mode unless the
800 -p option was specified. However, some network interfaces don't
801 support promiscuous mode, and some OSes might not allow interfaces to
802 be put into promiscuous mode.
804 If the interface is not running in promiscuous mode, it won't see any
805 traffic that isn't intended to be seen by your machine. It will see
806 broadcast packets, and multicast packets sent to a multicast MAC
807 address the interface is set up to receive.
809 You should ask the vendor of your network interface whether it
810 supports promiscuous mode. If it does, you should ask whoever supplied
811 the driver for the interface (the vendor, or the supplier of the OS
812 you're running on your machine) whether it supports promiscuous mode
813 with that network interface.
815 In the case of token ring interfaces, the drivers for some of them, on
816 Windows, may require you to enable promiscuous mode in order to
817 capture in promiscuous mode. Ask the vendor of the card how to do
818 this, or see, for example, this information on promiscuous mode on
819 some Madge token ring adapters (note that those cards can have
820 promiscuous mode disabled permanently, in which case you can't enable
823 In the case of wireless LAN interfaces, it appears that, when those
824 interfaces are promiscuously sniffing, they're running in a
825 significantly different mode from the mode that they run in when
826 they're just acting as network interfaces (to the extent that it would
827 be a significant effor for those drivers to support for promiscuously
828 sniffing and acting as regular network interfaces at the same time),
829 so it may be that Windows drivers for those interfaces don't support
832 Q 5.2: I can't see any TCP packets other than packets to and from my
833 machine, even though another sniffer on the network sees those
836 A: You're probably not seeing any packets other than unicast packets
837 to or from your machine, and broadcast and multicast packets; a switch
838 will normally send to a port only unicast traffic sent to the MAC
839 address for the interface on that port, and broadcast and multicast
840 traffic - it won't send to that port unicast traffic sent to a MAC
841 address for some other interface - and a network interface not in
842 promiscuous mode will receive only unicast traffic sent to the MAC
843 address for that interface, broadcast traffic, and multicast traffic
844 sent to a multicast MAC address the interface is set up to receive.
846 TCP doesn't use broadcast or multicast, so you will only see your own
847 TCP traffic, but UDP services may use broadcast or multicast so you'll
848 see some UDP traffic - however, this is not a problem with TCP
849 traffic, it's a problem with unicast traffic, as you also won't see
850 all UDP traffic between other machines.
852 I.e., this is probably the same question as this earlier one; see the
853 response to that question.
855 Q 5.3: I'm only seeing ARP packets when I try to capture traffic.
857 A: You're probably on a switched network, and running Ethereal on a
858 machine that's not sending traffic to the switch and not being sent
859 any traffic from other machines on the switch. ARP packets are often
860 broadcast packets, which are sent to all switch ports.
862 I.e., this is probably the same question as this earlier one; see the
863 response to that question.
865 Q 5.4: How do I put an interface into promiscuous mode?
867 A: By not disabling promiscuous mode when running Ethereal or
871 * the form of promiscuous mode that libpcap (the library that
872 programs such as tcpdump, Ethereal, etc. use to do packet capture)
873 turns on will not necessarily be shown if you run ifconfig on the
874 interface on a UNIX system;
875 * some network interfaces might not support promiscuous mode, and
876 some drivers might not allow promiscuous mode to be turned on -
877 see this earlier question for more information on that;
878 * the fact that you're not seeing any traffic, or are only seeing
879 broadcast traffic, or aren't seeing any non-broadcast traffic
880 other than traffic to or from the machine running Ethereal, does
881 not mean that promiscuous mode isn't on - see this earlier
882 question for more information on that.
884 I.e., this is probably the same question as this earlier one; see the
885 response to that question.
887 Q 5.5: I can set a display filter just fine, but capture filters don't
890 A: Capture filters currently use a different syntax than display
891 filters. Here's the corresponding section from the ethereal(1) man
894 "Display filters in Ethereal are very powerful; more fields are
895 filterable in Ethereal than in other protocol analyzers, and the
896 syntax you can use to create your filters is richer. As Ethereal
897 progresses, expect more and more protocol fields to be allowed in
900 Packet capturing is performed with the pcap library. The capture
901 filter syntax follows the rules of the pcap library. This syntax is
902 different from the display filter syntax."
904 The capture filter syntax used by libpcap can be found in the
907 Q 5.6: I'm entering valid capture filters, but I still get "parse
910 A: There is a bug in some versions of libpcap/WinPcap that cause it to
911 report parse errors even for valid expressions if a previous filter
912 expression was invalid and got a parse error.
914 Try exiting and restarting Ethereal; if you are using a version of
915 libpcap/WinPcap with this bug, this will "erase" its memory of the
916 previous parse error. If the capture filter that got the "parse error"
917 now works, the earlier error with that filter was probably due to this
920 The bug was fixed in libpcap 0.6; 0.4[.x] and 0.5[.x] versions of
921 libpcap have this bug, but 0.6[.x] and later versions don't.
923 Versions of WinPcap prior to 2.3 are based on pre-0.6 versions of
924 libpcap, and have this bug; WinPcap 2.3 is based on libpcap 0.6.2, and
925 doesn't have this bug.
927 If you are running Ethereal on a UNIX-flavored platform, run "ethereal
928 -v", or select "About Ethereal..." from the "Help" menu in Ethereal,
929 to see what version of libpcap it's using. If it's not 0.6 or later,
930 you will need either to upgrade your OS to get a later version of
931 libpcap, or will need to build and install a later version of libpcap
932 from the tcpdump.org Web site and then recompile Ethereal from source
933 with that later version of libpcap.
935 If you are running Ethereal on Windows with a pre-2.3 version of
936 WinPcap, you will need to un-install WinPcap and then download and
939 Q 5.7: I saved a filter and tried to use its name to filter the
940 display, but I got an "Unexpected end of filter string" error.
942 A: You cannot use the name of a saved display filter as a filter. To
943 filter the display, you can enter a display filter expression - not
944 the name of a saved display filter - in the "Filter:" box at the
945 bottom of the display, and type the key or press the "Apply" button
946 (that does not require you to have a saved filter), or, if you want to
947 use a saved filter, you can press the "Filter:" button, select the
948 filter in the dialog box that pops up, and press the "OK" button.
950 Q 5.8: Why am I seeing lots of packets with incorrect TCP checksums?
952 A: If the packets that have incorrect TCP checksums are all being sent
953 by the machine on which Ethereal is running, this is probably because
954 the network interface on which you're capturing does TCP checksum
955 offloading. That means that the TCP checksum is added to the packet by
956 the network interface, not by the OS's TCP/IP stack; when capturing on
957 an interface, packets being sent by the host on which you're capturing
958 are directly handed to the capture interface by the OS, which means
959 that they are handed to the capture interface without a TCP checksum
962 The only way to prevent this from happening would be to disable TCP
963 checksum offloading, but
964 1. that might not even be possible on some OSes;
965 2. that could reduce networking performance significantly.
967 However, you can disable the check that Ethereal does of the TCP
968 checksum, so that it won't report any packets as having TCP checksum
969 errors, and so that it won't refuse to do TCP reassembly due to a
970 packet having an incorrect TCP checksum. That can be set as an
971 Ethereal preference by selecting "Preferences" from the "Edit" menu,
972 opening up the "Protocols" list in the left-hand pane of the
973 "Preferences" dialog box, selecting "TCP", from that list, turning off
974 the "Check the validity of the TCP checksum when possible" option,
975 clicking "Save" if you want to save that setting in your preference
976 file, and clicking "OK".
978 It can also be set on the Ethereal or Tethereal command line with a -o
979 tcp.check_checksum:false command-line flag, or manually set in your
980 preferences file by adding a tcp.check_checksum:false line.
982 Q 5.9: I've just installed Ethereal, and the traffic on my local LAN
985 A: We have a collection of strange and exotic sample capture files at
986 http://www.ethereal.com/sample/
988 Q 5.10: When I run Ethereal on Solaris 8, it dies with a Bus Error
991 A: Some versions of the GTK+ library from www.sunfreeware.org appear
992 to be buggy, causing Ethereal to drop core with a Bus Error.
993 Un-install those packages, and try getting the 1.2.10 version from
994 that site, or the version from The Written Word, or the version from
995 Sun's GNOME distribution, or the version from the supplemental
996 software CD that comes with the Solaris media kit, or build it from
997 source from the GTK Web site. Update the GLib library to the 1.2.10
998 version, from the same source, as well. (If you get the 1.2.10
999 versions from www.sunfreeware.org, and the problem persists,
1000 un-install them and try installing one of the other versions
1003 Similar problems may exist with older versions of GTK+ for earlier
1004 versions of Solaris.
1006 Q 5.11: I'm running Ethereal on Linux; why do my time stamps have only
1007 100ms resolution, rather than 1us resolution?
1009 A: Ethereal gets time stamps from libpcap/WinPcap, and libpcap/WinPcap
1010 get them from the OS kernel, so Ethereal - and any other program using
1011 libpcap, such as tcpdump - is at the mercy of the time stamping code
1012 in the OS for time stamps.
1014 At least on x86-based machines, Linux can get high-resolution time
1015 stamps on newer processors with the Time Stamp Counter (TSC) register;
1016 for example, Intel x86 processors, starting with the Pentium Pro, and
1017 including all x86 processors since then, have had a TSC, and other
1018 vendors probably added the TSC at some point to their families of x86
1021 The Linux kernel must be configured with the CONFIG_X86_TSC option
1022 enabled in order to use the TSC. Make sure this option is enabled in
1025 In addition, some Linux distributions may have bugs in their versions
1026 of the kernel that cause packets not to be given high-resolution time
1027 stamps even if the TSC is enabled. See, for example, bug 61111 for Red
1028 Hat Linux 7.2. If your distribution has a bug such as this, you may
1029 have to run a standard kernel from kernel.org in order to get
1030 high-resolution time stamps.
1032 Q 5.12: I'm capturing packets on {Windows 95, Windows 98, Windows Me};
1033 why are the time stamps on packets wrong?
1035 A: This is due to a bug in WinPcap. The bug should be fixed in WinPcap
1038 Q 5.13: When I try to run Ethereal on Windows, it fails to run because
1039 it can't find packet.dll.
1041 A: In older versions of Ethereal, there were two binary distributions
1042 available for Windows, one that supported capturing packets, and one
1043 that didn't. The version that supported capturing packets required
1044 that you install the WinPcap driver; if you didn't install it, it
1045 would fail to run because it couldn't find packet.dll.
1047 The current version of Ethereal has only one binary distribution for
1048 Windows; that version will check whether WinPcap is installed and, if
1049 it's not, will disable support for packet capture.
1051 The WinPcap driver and libraries can be downloaded from the WinPcap
1052 Web site, the local mirror of the WinPcap Web site, or the
1053 Wiretapped.net mirror of the WinPcap site.
1055 Q 5.14: I'm running on Windows; why does some network interface on my
1056 machine not show up in the list of interfaces in the "Interface:"
1057 field in the dialog box popped up by "Capture->Start", and/or why does
1058 Ethereal give me an error if I try to capture on that interface?
1060 A: If you are running Ethereal on Windows NT 4.0, Windows 2000,
1061 Windows XP, or Windows Server, and this is the first time you have run
1062 a WinPcap-based program (such as Ethereal, or Tethereal, or WinDump,
1063 or Analyzer, or...) since the machine was rebooted, you need to run
1064 that program from an account with administrator privileges; once you
1065 have run such a program, you will not need administrator privileges to
1066 run any such programs until you reboot.
1068 If you are running on Windows 95/98/Me, or if you are running on
1069 Windows NT 4.0/2000/XP/Server and have administrator privileges or a
1070 WinPcap program has been run with those privileges since the machine
1071 rebooted, then note that Ethereal relies on the WinPcap library, on
1072 the WinPcap device driver, and on the facilities that come with the OS
1073 on which it's running in order to do captures.
1075 Therefore, if the OS, the WinPcap library, or the WinPcap driver don't
1076 support capturing on a particular network interface device, Ethereal
1077 won't be able to capture on that device.
1080 * 2.02 and earlier versions of the WinPcap driver and library that
1081 Ethereal uses for packet capture didn't support Token Ring
1082 interfaces; the current version, 2.3, does support Token Ring, and
1083 the current version of Ethereal works with (and, in fact,
1084 requires) WinPcap 2.1 or later.
1085 If you are having problems capturing on Token Ring interfaces, and
1086 you have WinPcap 2.02 or an earlier version of WinPcap installed,
1087 you should uninstall WinPcap, download and install the current
1088 version of WinPcap, and then install the latest version of
1090 * On Windows 95, 98, or Me, sometimes more than one interface will
1091 be given the same name; if that is the case, you will only be able
1092 to capture on one of those interfaces - it's not clear to which
1093 one the name, when used in a WinPcap application, will refer. For
1094 example, if you have a PPP serial interface and a VPN interface,
1095 they might show up with the same name, for example "ppp-mac", and
1096 if you try to capture on "ppp-mac", it might not capture on the
1097 interface you're currently using. In that case, you might, for
1098 example, have to remove the VPN interface from the system in order
1099 to capture on the PPP serial interface.
1100 * WinPcap doesn't support PPP WAN interfaces on Windows
1101 NT/2000/XP/Server, so Ethereal cannot capture packets on those
1102 devices when running on Windows NT/2000/XP/Server. Regular dial-up
1103 lines, ISDN lines, and various other lines such as T1/E1 lines are
1104 all PPP interfaces. This may cause the interface not to show up on
1105 the list of interfaces in the "Capture Options" dialog.
1106 * WinPcap prior to 3.0 does not support multiprocessor machines
1107 (note that machines with a single multi-threaded processor, such
1108 as Intel's new multi-threaded x86 processors, are multiprocessor
1109 machines as far as the OS and WinPcap are concerned), and recent
1110 2.x versions of WinPcap refuse to operate if they detect that
1111 they're running on a multiprocessor machine, which means that they
1112 may not show any network interfaces. You will need to use WinPcap
1113 3.0 to capture on a multiprocessor machine.
1115 If an interface doesn't show up in the list of interfaces in the
1116 "Interface:" field, and you know the name of the interface, try
1117 entering that name in the "Interface:" field and capturing on that
1120 If the attempt to capture on it succeeds, the interface is somehow not
1121 being reported by the mechanism Ethereal uses to get a list of
1122 interfaces; please report this to ethereal-dev@ethereal.com giving
1123 full details of the problem, including
1124 * the operating system you're using, and the version of that
1126 * the type of network device you're using.
1128 If you are having trouble capturing on a particular network interface,
1129 and you've made sure that (on platforms that require it) you've
1130 arranged that packet capture support is present, as per the above,
1131 first try capturing on that device with WinDump; see the WinDump Web
1132 site or the local mirror of the WinDump Web site for information on
1135 If you can capture on the interface with WinDump, send mail to
1136 ethereal-users@ethereal.com giving full details of the problem,
1138 * the operating system you're using, and the version of that
1140 * the type of network device you're using;
1141 * the error message you get from Ethereal.
1143 If you cannot capture on the interface with WinDump, this is almost
1144 certainly a problem with one or more of:
1145 * the operating system you're using;
1146 * the device driver for the interface you're using;
1147 * the WinPcap library and/or the WinPcap device driver;
1149 so first check the WinPcap FAQ, the local mirror of that FAQ, or the
1150 Wiretapped.net mirror of that FAQ, to see if your problem is mentioned
1151 there. If not, then see the WinPcap support page (or the local mirror
1152 of that page) - check the "Submitting bugs" section.
1154 You may also want to ask the ethereal-users@ethereal.com and the
1155 winpcap-users@winpcap.polito.it mailing lists to see if anybody
1156 happens to know about the problem and know a workaround or fix for the
1157 problem. (Note that you will have to subscribe to that list in order
1158 to be allowed to mail to it; see the WinPcap support page, or the
1159 local mirror of that page, for information on the mailing list.) In
1160 your mail, please give full details of the problem, as described
1161 above, and also indicate that the problem occurs with WinDump, not
1164 Q 5.15: I'm running on a UNIX-flavored OS; why does some network
1165 interface on my machine not show up in the list of interfaces in the
1166 "Interface:" field in the dialog box popped up by "Capture->Start",
1167 and/or why does Ethereal give me an error if I try to capture on that
1170 A: You may need to run Ethereal from an account with sufficient
1171 privileges to capture packets, such as the super-user account. Only
1172 those interfaces that Ethereal can open for capturing show up in that
1173 list; if you don't have sufficient privileges to capture on any
1174 interfaces, no interfaces will show up in the list.
1176 If you are running Ethereal from an account with sufficient
1177 privileges, then note that Ethereal relies on the libpcap library, and
1178 on the facilities that come with the OS on which it's running in order
1181 Therefore, if the OS or the libpcap library don't support capturing on
1182 a particular network interface device, Ethereal won't be able to
1183 capture on that device.
1185 On Linux, note that you need to have "packet socket" support enabled
1186 in your kernel; see the "Packet socket" item in the Linux
1187 "Configure.help" file.
1189 On BSD, note that you need to have BPF support enabled in your kernel;
1190 see the documentation for your system for information on how to enable
1191 BPF support (if it's not enabled by default on your system).
1193 On DEC OSF/1, Digital UNIX, or Tru64 UNIX, note that you need to have
1194 packet filtering support in your kernel; the doconfig command will
1195 allow you to configure and build a new kernel with that option.
1197 On Solaris, note that libpcap 0.6.2 and earlier didn't support Token
1198 Ring interfaces; the current version, 0.7.2, does support Token Ring,
1199 and the current version of Ethereal works with libcap 0.7.2 and later.
1201 If an interface doesn't show up in the list of interfaces in the
1202 "Interface:" field, and you know the name of the interface, try
1203 entering that name in the "Interface:" field and capturing on that
1206 If the attempt to capture on it succeeds, the interface is somehow not
1207 being reported by the mechanism Ethereal uses to get a list of
1208 interfaces; please report this to ethereal-dev@ethereal.com giving
1209 full details of the problem, including
1210 * the operating system you're using, and the version of that
1211 operating system (for Linux, give both the version number of the
1212 kernel and the name and version number of the distribution you're
1214 * the type of network device you're using.
1216 If you are having trouble capturing on a particular network interface,
1217 and you've made sure that (on platforms that require it) you've
1218 arranged that packet capture support is present, as per the above,
1219 first try capturing on that device with tcpdump.
1221 If you can capture on the interface with tcpdump, send mail to
1222 ethereal-users@ethereal.com giving full details of the problem,
1224 * the operating system you're using, and the version of that
1225 operating system (for Linux, give both the version number of the
1226 kernel and the name and version number of the distribution you're
1228 * the type of network device you're using;
1229 * the error message you get from Ethereal.
1231 If you cannot capture on the interface with tcpdump, this is almost
1232 certainly a problem with one or more of:
1233 * the operating system you're using;
1234 * the device driver for the interface you're using;
1235 * the libpcap library;
1237 so you should report the problem to the company or organization that
1238 produces the OS (in the case of a Linux distribution, report the
1239 problem to whoever produces the distribution).
1241 You may also want to ask the ethereal-users@ethereal.com and the
1242 tcpdump-workers@tcpdump.org mailing lists to see if anybody happens to
1243 know about the problem and know a workaround or fix for the problem.
1244 In your mail, please give full details of the problem, as described
1245 above, and also indicate that the problem occurs with tcpdump not just
1248 Q 5.16: I'm running Ethereal on Windows NT/2000/XP/Server; my machine
1249 has a PPP (dial-up POTS, ISDN, etc.) interface, and it shows up in the
1250 "Interface" item in the "Capture Options" dialog box. Why can no
1251 packets be sent on or received from that network while I'm trying to
1252 capture traffic on that interface?
1254 A: WinPcap doesn't support PPP WAN interfaces on Windows
1255 NT/2000/XP/Server; one symptom that may be seen is that attempts to
1256 capture in promiscuous mode on the interface cause the interface to be
1257 incapable of sending or receiving packets. You can disable promiscuous
1258 mode using the -p command-line flag or the item in the "Capture
1259 Preferences" dialog box, but this may mean that outgoing packets, or
1260 incoming packets, won't be seen in the capture.
1262 Q 5.17: I'm running Ethereal on Windows 95/98/Me, on a machine with
1263 more than one network adapter of the same type; Ethereal shows all of
1264 those adapters with the same name, but I can't use any of those
1265 adapters other than the first one.
1267 A: Unfortunately, Windows 95/98/Me gives the same name to multiple
1268 instances of the type of same network adapter. Therefore, WinPcap
1269 cannot distinguish between them, so a WinPcap-based application can
1270 capture only on the first such interface; Ethereal is a
1271 libpcap/WinPcap-based application.
1273 Q 5.18: I'm running Ethereal on Windows, and I'm not seeing any
1274 traffic being sent by the machine running Ethereal.
1276 A: If you are running some form of VPN client software, it might be
1277 causing this problem; people have seen this problem when they have
1278 Check Point's VPN software installed on their machine. If that's the
1279 cause of the problem, you will have to remove the VPN software in
1280 order to have Ethereal (or any other application using WinPcap) see
1281 outgoing packets; unfortunately, neither we nor the WinPcap developers
1282 know any way to make WinPcap and the VPN software work well together.
1284 Q 5.19: I have an XXX network card on my machine; if I try to capture
1285 on it, my machine crashes or resets itself.
1287 A: This is almost certainly a problem with one or more of:
1288 * the operating system you're using;
1289 * the device driver for the interface you're using;
1290 * the libpcap/WinPcap library and, if this is Windows, the WinPcap
1294 * if you are using Windows, see the WinPcap support page (or the
1295 local mirror of that page) - check the "Submitting bugs" section;
1296 * if you are using some Linux distribution, some version of BSD, or
1297 some other UNIX-flavored OS, you should report the problem to the
1298 company or organization that produces the OS (in the case of a
1299 Linux distribution, report the problem to whoever produces the
1302 Q 5.20: My machine crashes or resets itself when I select "Start" from
1303 the "Capture" menu or select "Preferences" from the "Edit" menu.
1305 A: Both of those operations cause Ethereal to try to build a list of
1306 the interfaces that it can open; it does so by getting a list of
1307 interfaces and trying to open them. There is probably an OS, driver,
1308 or, for Windows, WinPcap bug that causes the system to crash when this
1309 happens; see the previous question.
1311 Q 5.21: Does Ethereal work on Windows ME?
1313 A: Yes, but if you want to capture packets, you will need to install
1314 the latest version of WinPcap, as 2.02 and earlier versions of WinPcap
1315 didn't support Windows ME. You should also install the latest version
1316 of Ethereal as well.
1318 Q 5.22: Does Ethereal work on Windows XP?
1320 A: Yes, but if you want to capture packets, you will need to install
1321 the latest version of WinPcap, as 2.2 and earlier versions of WinPcap
1322 didn't support Windows XP.
1324 Q 5.23: Why doesn't Ethereal correctly identify RTP packets? It shows
1327 A: Ethereal can identify a UDP datagram as containing a packet of a
1328 particular protocol running atop UDP only if
1329 1. The protocol in question has a particular standard port number,
1330 and the UDP source or destination port number is that port
1331 2. Packets of that protocol can be identified by looking for a
1332 "signature" of some type in the packet - i.e., some data that, if
1333 Ethereal finds it in some particular part of a packet, means that
1334 the packet is almost certainly a packet of that type.
1335 3. Some other traffic earlier in the capture indicated that, for
1336 example, UDP traffic between two particular addresses and ports
1337 will be RTP traffic.
1339 RTP doesn't have a standard port number, so 1) doesn't work; it
1340 doesn't, as far as I know, have any "signature", so 2) doesn't work.
1342 That leaves 3). If there's RTSP traffic that sets up an RTP session,
1343 then, at least in some cases, the RTSP dissector will set things up so
1344 that subsequent RTP traffic will be identified. Currently, that's the
1345 only place we do that; there may be other places.
1347 However, there will always be places where Ethereal is simply
1348 incapable of deducing that a given UDP flow is RTP; a mechanism would
1349 be needed to allow the user to specify that a given conversation
1350 should be treated as RTP. As of Ethereal 0.8.16, such a mechanism
1351 exists; if you select a UDP or TCP packet, the right mouse button menu
1352 will have a "Decode As..." menu item, which will pop up a dialog box
1353 letting you specify that the source port, the destination port, or
1354 both the source and destination ports of the packet should be
1355 dissected as some particular protocol.
1357 Q 5.24: Why doesn't Ethereal show Yahoo Messenger packets in captures
1358 that contain Yahoo Messenger traffic?
1360 A: Ethereal only recognizes as Yahoo Messenger traffic packets to or
1361 from TCP port 3050 that begin with "YPNS", "YHOO", or "YMSG". TCP
1362 segments that start with the middle of a Yahoo Messenger packet that
1363 takes more than one TCP segment will not be recognized as Yahoo
1364 Messenger packets (even if the TCP segment also contains the beginning
1365 of another Yahoo Messenger packet).
1367 Q 5.25: Why do I get the error
1369 Gdk-ERROR **: Palettized display (256-colour) mode not supported on
1373 when I try to run Ethereal on Windows?
1375 A: Ethereal is built using the GTK+ toolkit, which supports most
1376 UNIX-flavored OSes, and also supports Windows; that toolkit doesn't
1377 support 256-color mode on Windows - it requires HiColor (16-bit
1378 colors) or more. If your display supports more than 256 colors, switch
1379 to a display mode with more colors; if it doesn't support more than
1380 256 colors, you will be unable to run Ethereal.
1382 Q 5.26: When I capture on Windows in promiscuous mode, I can see
1383 packets other than those sent to or from my machine; however, those
1384 packets show up with a "Short Frame" indication, unlike packets to or
1385 from my machine. What should I do to arrange that I see those packets
1388 A: In at least some cases, this appears to be the result of PGPnet
1389 running on the network interface on which you're capturing; turn it
1390 off on that interface.
1392 Q 5.27: How can I capture raw 802.11 packets, including non-data
1393 (management, beacon) packets?
1395 A: That would require that your 802.11 interface run in the mode
1396 called "monitor mode" or "RFMON mode". Not all operating systems
1397 support that and, even on operating systems that do support it, not
1398 all drivers, and thus not all cards, support it.
1400 Cisco Aironet cards:
1402 The only platforms that allow Ethereal to capture raw 802.11 packets
1403 on Cisco Aironet cards are:
1404 * Linux, with a 2.4.6 or later kernel;
1405 * FreeBSD 4.6 or later, as the driver in FreeBSD 4.5 has bugs that
1406 cause packets not to be captured correctly, and the driver in
1407 releases prior to 4.5 didn't support capturing raw packets.
1409 On FreeBSD, the ancontrol utility must be used; do not enable the full
1410 Aironet header via BPF, as Ethereal doesn't currently support that.
1412 On Linux with the driver in the 2.4.6 through 2.4.19 kernel, you will
1415 echo "Mode: rfmon" >/proc/driver/aironet/ethN/Config
1417 if your Aironet card is ethN. To capture traffic from any BSS, do
1419 echo "Mode: y" >/proc/driver/aironet/ethN/Config
1421 and to return to the normal mode, do
1423 echo "Mode: ess" >/proc/driver/aironet/ethN/Config
1425 On Linux with the driver in the 2.4.20 kernel, or with the CVS drivers
1426 from the airo-linux SourceForge site, you will have to capture on the
1427 wifiN interface if your Aironet card is ethN, after running the
1428 commands listed above.
1430 In all of those cases, Ethereal would have to be linked with libpcap
1431 0.7.1 or later; this means that most Ethereal binary packages won't
1432 work unless they're statically linked with libpcap 0.7.1 or later, or
1433 they're dynamically linked with libpcap and your system has a libpcap
1434 0.7.1 or later shared library installed (note that libpcap source
1435 package from tcpdump.org does not build shared libraries). Some binary
1436 packaging mechanisms might make it difficult to install Ethereal
1437 binary packages built to depend on older libpcap binary packages if
1438 you have a newer libpcap binary package installed; the installer
1439 programs for those packaging mechanisms might support disabling
1440 dependency checking so that they will install Ethereal even though a
1441 newer version of libpcap is installed.
1443 Cards using the Prism II chip set (see this page of Linux 802.11
1444 information for details on wireless cards, including information on
1445 the chips they use):
1447 You can capture raw 802.11 packets with Prism II cards on Linux
1448 systems with the 0.1.14-pre6 or later version of the linux-wlan-ng
1449 drivers (see the linux-wlan page, and the linux-wlan-ng tarball
1452 Those require either Solomon Peachy's patch to libpcap 0.7.1 (see his
1453 libpcap-0.7.1-prism.diff file, or his RPMs of that version of
1454 libpcap), or the current CVS version of libpcap, which includes his
1455 patch (download it from the "Current Tar files" section of the
1456 tcpdump.org Web site). If you apply his patches to libpcap 0.7.1 and
1457 rebuild and install libpcap, or if you build and install the current
1458 CVS version of libpcap, you would have to rebuild Ethereal from
1459 source, linking it with that new version of libpcap; an Ethereal
1460 binary package would not work. Ethereal binary packages might work if
1461 you install the libpcap-0.7.1-1prism.i386.rpm RPM, as it might install
1462 a libpcap shared library in place of the one on your system.
1464 You may have to run a command to put the interface into monitor mode,
1465 or to change other interface settings, and you might have to capture
1466 on a wlanN interface rather than a ethN interface, in order to capture
1467 raw 802.11 packets. The interface settings are available in your
1468 wlan-ng.conf file. See the wlan-ng FAQ for additional information.
1470 On other platforms, capturing raw 802.11 packets on Prism II cards is
1471 not currently supported.
1473 Orinoco Silver and Gold cards:
1475 On Linux systems, there are patches on the Orinoco Monitor Mode Patch
1476 Page that should allow you to do capture raw 802.11 packets. You will
1477 have to determine which version of the driver you have, and select the
1480 Note that the page indicates that not all versions of the Orinoco
1481 firmware support this patch. It says, for some versions of the patch,
1482 "This patch should allow monitor mode with v8.10 firmware (untested w/
1483 8.42);" if you have version 8.10 or later firmware on your Orinoco
1484 cards, you might have to use those patches, with the corresponding
1485 versions of the Orinoco driver, in order to run in monitor mode.
1487 That patch is written for the drivers included with the pcmcia-cs
1488 drivers, but works equally well for the Orinoco drivers provided with
1489 Linux kernels up to 2.4.20. To apply a patch to your kernel drivers,
1490 simply copy the orinoco-09b-patch.diff file to the
1491 /usr/src/linux/drivers/net directory and patch according to the
1492 directions on the Orinoco Monitor Mode Patch Page. You can double-
1493 check the version of the Orinoco drivers that shipped with your kernel
1494 by examining the first few lines of the orinoco.c file.
1496 Te Orinoco patches require either Solomon Peachy's patch to libpcap
1497 0.7.1 (see his libpcap-0.7.1-prism.diff file, or his RPMs of that
1498 version of libpcap), or the current CVS version of libpcap, which
1499 includes his patch (download it from the "Current Tar files" section
1500 of the tcpdump.org Web site). If you apply his patches to libpcap
1501 0.7.1 and rebuild and install libpcap, or if you build and install the
1502 current CVS version of libpcap, you would have to rebuild Ethereal
1503 from source, linking it with that new version of libpcap; an Ethereal
1504 binary package would not work. Ethereal binary packages might work if
1505 you install the libpcap-0.7.1-1prism.i386.rpm RPM, as it might install
1506 a libpcap shared library in place of the one on your system.
1508 On other platforms, capturing raw 802.11 packets on Orinoco cards is
1509 not currently supported.
1511 Other 802.11 interfaces:
1513 With other 802.11 interfaces, no platform allows Ethereal to capture
1514 raw 802.11 packets, as far as we know. If you know of other 802.11
1515 interfaces that are supported (note that there are many "Prism II
1516 cards", so your card might be a Prism II card), please let us know,
1517 and include URLs for sites containing any necessary patches to add
1520 On platforms that don't allow Ethereal to capture raw 802.11 packets,
1521 the 802.11 network will appear like an Ethernet to Ethereal.
1523 Q 5.28: How can I capture packets with CRC errors?
1525 A: Ethereal can capture only the packets that the packet capture
1526 library - libpcap on UNIX-flavored OSes, and the WinPcap port to
1527 Windows of libpcap on Windows - can capture, and libpcap/WinPcap can
1528 capture only the packets that the OS's raw packet capture mechanism
1529 (or the WinPcap driver, and the underlying OS networking code and
1530 network interface drivers, on Windows) will allow it to capture.
1532 Unless the OS can be configured to supply packets with errors such as
1533 invalid CRCs to the raw packet capture mechanism, Ethereal - and other
1534 programs that capture raw packets, such as tcpdump - cannot capture
1535 those packets. You will have to determine whether your OS can be so
1536 configured, configure it if possible, and make whatever changes to
1537 libpcap and the packet capture program you're using are necessary to
1538 support capturing those packets.
1540 Q 5.29: How can I capture entire frames, including the FCS?
1542 A: Ethereal can't capture any data that the packet capture library -
1543 libpcap on UNIX-flavored OSes, and the WinPcap port to Windows of
1544 libpcap on Windows - can capture, and libpcap/WinPcap can capture only
1545 the data that the OS's raw packet capture mechanism (or the WinPcap
1546 driver, and the underlying OS networking code and network interface
1547 drivers, on Windows) will allow it to capture.
1549 For any particular link-layer network type, unless the OS supplies the
1550 FCS of a frame as part of the frame, or can be configured to supply
1551 the FCS of a frame as part of the frame, Ethereal - and other programs
1552 that capture raw packets, such as tcpdump - cannot capture the FCS of
1553 a frame. You will have to determine whether your OS can be so
1554 configured, configure it if possible, and make whatever changes to
1555 libpcap and the packet capture program you're using are necessary to
1556 support capturing the FCS of a frame. Most if not all OSes probably do
1557 not support capturing the FCS of a frame on Ethernet, and probably do
1558 not support it on most other link-layer types.
1560 Q 5.30: Ethereal hangs after I stop a capture.
1562 A: The most likely reason for this is that Ethereal is trying to look
1563 up an IP address in the capture to convert it to a name (so that, for
1564 example, it can display the name in the source address or destination
1565 address columns), and that lookup process is taking a very long time.
1567 Ethereal calls a routine in the OS of the machine on which it's
1568 running to convert of IP addresses to the corresponding names. That
1569 routine probably does one or more of:
1570 * a search of a system file listing IP addresses and names;
1571 * a lookup using DNS;
1572 * on UNIX systems, a lookup using NIS;
1573 * on Windows systems, a NetBIOS-over-TCP query.
1575 If a DNS server that's used in an address lookup is not responding,
1576 the lookup will fail, but will only fail after a timeout while the
1577 system routine waits for a reply.
1579 In addition, on Windows systems, if the DNS lookup of the address
1580 fails, either because the server isn't responding or because there are
1581 no records in the DNS that could be used to map the address to a name,
1582 a NetBIOS-over-TCP query will be made. That query involves sending a
1583 message to the NetBIOS-over-TCP name service on that machine, asking
1584 for the name and other information about the machine. If the machine
1585 isn't running software that responds to those queries - for example,
1586 many non-Windows machines wouldn't be running that software - the
1587 lookup will only fail after a timeout. Those timeouts can cause the
1588 lookup to take a long time.
1590 If you disable network address-to-name translation - for example, by
1591 turning off the "Enable network name resolution" option in the "Name
1592 resolution" options in the dialog box you get by selecting
1593 "Preferences" from the "Edit" menu - the lookups of the address won't
1594 be done, which may speed up the process of reading the capture file
1595 after the capture is stopped. You can make that setting the default by
1596 using the "Save" button in that dialog box; note that this will save
1597 all your current preference settings.
1599 If Ethereal hangs when reading a capture even with network name
1600 resolution turned off, there might, for example, be a bug in one of
1601 Ethereal's dissectors for a protocol causing it to loop infinitely.
1602 The bug should be reported to the Ethereal developers' mailing list at
1603 ethereal-dev@ethereal.com.
1605 On UNIX-flavored OSes, please try to force Ethereal to dump core, by
1606 sending it a SIGABRT signal (usually signal 6) with the kill command,
1607 and then get a stack trace if you have a debugger installed. A stack
1608 trace can be obtained by using your debugger (gdb in this example),
1609 the Ethereal binary, and the resulting core file. Here's an example of
1610 how to use the gdb command backtrace to do so.
1613 ..... prints the stack trace
1617 The core dump file may be named "ethereal.core" rather than "core" on
1618 some platforms (e.g., BSD systems)
1620 Also, if at all possible, please send a copy of the capture file that
1621 caused the problem; when capturing packets, Ethereal normally writes
1622 captured packets to a temporary file, which will probably be in /tmp
1623 or /var/tmp on UNIX-flavored OSes and \TEMP on Windows, so the capture
1624 file will probably be there. It will have a name beginning with ether,
1625 with some mixture of letters and numbers after that. Please don't send
1626 a trace file greater than 1 MB when compressed. If the trace file
1627 contains sensitive information (e.g., passwords), then please do not
1630 Q 5.31: How can I search for, or filter, packets that have a
1631 particular string anywhere in them?
1633 A: Currently, you can't.
1635 That's a feature that would be hard to implement in capture filters
1636 without changes to the capture filter code, which, on many platforms,
1637 is in the OS kernel and, on other platforms, is in the libpcap
1640 It would be easier to implement in display filters, but it hasn't been
1641 implemented yet. It would be best implemented as a display filter
1642 "string match" operator, which would let you check not only the entire
1643 packet for a string, but check portions of the packet for a string. It
1644 should probably not use a naive string matching mechanism, as there
1645 are mechanisms much faster than the naive one.
1648 Support can be found on the ethereal-users[AT]ethereal.com mailing
1650 For corrections/additions/suggestions for this page, please send email
1651 to: ethereal-web[AT]ethereal.com
1652 Last modified: Thu, April 10 2003.
git.samba.org / obnox / wireshark / wip.git / blob