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 393 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
282 Encapsulating Security Payload
283 Enhanced Interior Gateway Routing Protocol
284 EtherNet/IP (Industrial Protocol)
287 Extensible Authentication Protocol
289 FC Fabric Configuration Server
293 Fiber Distributed Data Interface
295 Fibre Channel Common Transport
296 Fibre Channel Fabric Zone Server
297 Fibre Channel Name Server
298 Fibre Channel Protocol for SCSI
300 File Transfer Protocol (FTP)
301 Financial Information eXchange Protocol
304 GARP Multicast Registration Protocol
305 GARP VLAN Registration Protocol
306 GPRS Tunneling Protocol
307 GPRS Tunnelling Protocol v0
308 GPRS Tunnelling Protocol v1
309 General Inter-ORB Protocol
310 Generic Routing Encapsulation
311 Generic Security Service Application Program Interface
314 HP Extended Local-Link Control
315 HP Remote Maintenance Protocol
316 Hummingbird NFS Daemon
318 Hypertext Transfer Protocol
320 IEEE 802.11 wireless LAN
321 IEEE 802.11 wireless LAN management frame
324 IP Payload Compression
326 IPX Routing Information Protocol
329 ISDN Q.921-User Adaptation Layer
331 ISO 10589 ISIS InTRA Domain Routeing Information Exchange Protocol
332 ISO 8073 COTP Connection-Oriented Transport Protocol
333 ISO 8473 CLNP ConnectionLess Network Protocol
334 ISO 8602 CLTP ConnectionLess Transport Protocol
335 ISO 9542 ESIS Routeing Information Exchange Protocol
336 ITU-T Recommendation H.261
339 Intelligent Platform Management Interface
340 Inter-Access-Point Protocol
342 Internet Cache Protocol
343 Internet Content Adaptation Protocol
344 Internet Control Message Protocol
345 Internet Control Message Protocol v6
346 Internet Group Management Protocol
347 Internet Message Access Protocol
348 Internet Printing Protocol
350 Internet Protocol Version 6
352 Internet Security Association and Key Management Protocol
353 Internetwork Packet eXchange
358 Kerberos Administration
360 Label Distribution Protocol
361 Layer 2 Tunneling Protocol
362 Lightweight Directory Access Protocol
363 Line Printer Daemon Protocol
364 Link Access Procedure Balanced (LAPB)
365 Link Access Procedure Balanced Ethernet (LAPBETHER)
366 Link Access Procedure, Channel D (LAPD)
367 Link Aggregation Control Protocol
368 Link Management Protocol (LMP)
369 Linux cooked-mode capture
370 Local Management Interface
371 LocalTalk Link Access Protocol
373 Lucent/Ascend debug output
375 MMS Message Encapsulation
377 MSN Messenger Service
378 MSNIP: Multicast Source Notification of Interest Protocol
379 MTP 2 Transparent Proxy
380 MTP 2 User Adaptation Layer
381 MTP 3 User Adaptation Layer
382 MTP2 Peer Adaptation Layer
383 Message Transfer Part Level 2
384 Message Transfer Part Level 3
385 Message Transfer Part Level 3 Management
386 Microsoft Distributed File System
387 Microsoft Exchange MAPI
388 Microsoft Local Security Architecture
389 Microsoft Local Security Architecture (Directory Services)
390 Microsoft Messenger Service
391 Microsoft Network Logon
393 Microsoft Security Account Manager
394 Microsoft Server Service
395 Microsoft Service Control
396 Microsoft Spool Subsystem
397 Microsoft Task Scheduler Service
398 Microsoft Telephony API Service
399 Microsoft Windows Browser Protocol
400 Microsoft Windows Lanman Remote API Protocol
401 Microsoft Windows Logon Protocol
402 Microsoft Workstation Service
407 MultiProtocol Label Switching Header
408 Multicast Router DISCovery protocol
409 Multicast Source Discovery Protocol
416 NTLM Secure Service Provider
417 Name Binding Protocol
418 Name Management Protocol over IPX
420 NetBIOS Datagram Service
422 NetBIOS Session Service
424 NetWare Core Protocol
425 NetWare Link Services Protocol
426 Network Data Management Protocol
428 Network Lock Manager Protocol
429 Network News Transfer Protocol
430 Network Status Monitor CallBack Protocol
431 Network Status Monitor Protocol
432 Network Time Protocol
433 Novell Distributed Print System
435 Open Shortest Path First
436 OpenBSD Encapsulating device
437 OpenBSD Packet Filter log file
438 OpenBSD Packet Filter log file, pre 3.4
440 PPP Bandwidth Allocation Control Protocol
441 PPP Bandwidth Allocation Protocol
442 PPP CDP Control Protocol
443 PPP Callback Control Protocol
444 PPP Challenge Handshake Authentication Protocol
445 PPP Compressed Datagram
446 PPP Compression Control Protocol
447 PPP IP Control Protocol
448 PPP IPv6 Control Protocol
449 PPP Link Control Protocol
450 PPP MPLS Control Protocol
451 PPP Multilink Protocol
453 PPP Password Authentication Protocol
455 PPP-over-Ethernet Discovery
456 PPP-over-Ethernet Session
457 PPPMux Control Protocol
458 Packet Encoding Rules (ASN.1 X.691)
459 Point-to-Point Protocol
460 Point-to-Point Tunnelling Protocol
463 Pragmatic General Multicast
465 Privilege Server operations
466 Protocol Independent Multicast
469 Quake II Network Protocol
470 Quake III Arena Network Protocol
471 Quake Network Protocol
472 QuakeWorld Network Protocol
473 Qualified Logical Link Control
478 RSYNC File Synchroniser
480 Radio Access Network Application Part
483 Real Time Streaming Protocol
484 Real-Time Transport Protocol
485 Real-time Transport Control Protocol
486 Registry Server Attributes Manipulation Interface
487 Registry server administration operations.
488 Remote Management Control Protocol
489 Remote Override interface
490 Remote Procedure Call
495 Remote sec_login preauth interface.
496 Resource ReserVation Protocol (RSVP)
498 Routing Information Protocol
499 Routing Table Maintenance Protocol
503 SMB (Server Message Block Protocol)
504 SMB MailSlot Protocol
507 SNMP Multiplex Protocol
510 SS7 SCCP-User Adaptation Layer
514 Sequenced Packet eXchange
515 Service Advertisement Protocol
516 Service Location Protocol
517 Session Announcement Protocol
518 Session Description Protocol
519 Session Initiation Protocol
520 Short Message Peer to Peer
521 Signalling Connection Control Part
522 Signalling Connection Control Part Management
523 Simple Mail Transfer Protocol
524 Simple Network Management Protocol
526 Skinny Client Control Protocol
527 SliMP3 Communication Protocol
529 Spanning Tree Protocol
531 Stream Control Transmission Protocol
532 Synchronous Data Link Control (SDLC)
534 Systems Network Architecture
535 Systems Network Architecture XID
540 Tazmen Sniffer Protocol
543 Time Synchronization Protocol
545 Token-Ring Media Access Control
546 Transmission Control Protocol
547 Transparent Network Substrate Protocol
548 Trivial File Transfer Protocol
549 UDP Encapsulation of IPsec Packets
550 Universal Computer Protocol
551 User Datagram Protocol
552 Virtual Router Redundancy Protocol
553 Virtual Trunking Protocol
555 Web Cache Coordination Protocol
556 Wellfleet Breath of Life
557 Wellfleet Compression
561 Wireless Session Protocol
562 Wireless Transaction Protocol
563 Wireless Transport Layer Security
564 X Display Manager Control Protocol
570 Yahoo Messenger Protocol
571 Yahoo YMSG Messenger Protocol
575 Yellow Pages Transfer
577 Zone Information Protocol
582 Q 1.3: Are there any plans to support {your favorite protocol}?
584 A: Support for particular protocols is added to Ethereal as a result
585 of people contributing that support; no formal plans for adding
586 support for particular protocols in particular future releases exist.
588 Q 1.4: Can Ethereal read capture files from {your favorite network
591 A: Support for particular protocols is added to Ethereal as a result
592 of people contributing that support; no formal plans for adding
593 support for particular protocols in particular future releases exist.
595 If a network analyzer writes out files in a format already supported
596 by Ethereal (e.g., in libpcap format), Ethereal may already be able to
597 read them, unless the analyzer has added its own proprietary
598 extensions to that format.
600 If a network analyzer writes out files in its own format, or has added
601 proprietary extensions to another format, in order to make Ethereal
602 read captures from that network analyzer, we would either have to have
603 a specification for the file format, or the extensions, sufficient to
604 give us enough information to read the parts of the file relevant to
605 Ethereal, or would need at least one capture file in that format AND a
606 detailed textual analysis of the packets in that capture file (showing
607 packet time stamps, packet lengths, and the top-level packet header)
608 in order to reverse-engineer the file format.
610 Note that there is no guarantee that we will be able to
611 reverse-engineer a capture file format.
613 Q 1.5: What devices can Ethereal use to capture packets?
615 A: Ethereal can read live data from Ethernet, Token-Ring, FDDI, serial
616 (PPP and SLIP) (if the OS on which it's running allows Ethereal to do
617 so), 802.11 wireless LAN (if the OS on which it's running allows
618 Ethereal to do so), ATM connections (if the OS on which it's running
619 allows Ethereal to do so), and the "any" device supported on Linux by
620 recent versions of libpcap. See the list of supported capture media on
621 various OSes for details (several items in there say "Unknown", which
622 doesn't mean "Ethereal can't capture on them", it means "we don't know
623 whether it can capture on them"; we expect that it will be able to
624 capture on many of them, but we haven't tried it ourselves - if you
625 try one of those types and it works, please send an update to
626 ethereal-web[AT]ethereal.com).
628 It can also read a variety of capture file formats, including:
631 * Shomiti/Finisar Surveyor
633 * DOS-based Sniffer (compressed and uncompressed)
636 * NetXray and Windows-based Sniffer
637 * EtherPeek/TokenPeek/AiroPeek
638 * RADCOM WAN/LAN analyzer
639 * Lucent/Ascend debug output
640 * Toshiba ISDN router "snoop" output
642 * ISDN4BSD "i4btrace" utility.
644 * pppd log files (pppdump format)
647 * Visual Networks' Visual UpTime
650 so that it can read traces from various network types, as captured by
651 other applications or equipment, even if it cannot itself capture on
654 Q 1.6: How do you pronounce Ethereal? Where did the name come from?
656 A: The English pronunciation can be found in Merriam-Webster's online
658 http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=ethereal.
660 According to the book "Computer Networks" by Andrew Tannenbaum,
661 Ethernet was named after the "luminiferous ether" which was once
662 thought to carry electromagnetic radiation. Taking that into
663 consideration, Ethereal seemed like an appropriate name for an
667 Q 2.1: I downloaded the Win32 installer, but when I try to run it, I
670 A: The program you used to download it may have downloaded it
671 incorrectly. Web browsers sometimes may do this.
673 Try downloading it with, for example:
674 * Wget, for which Windows binaries are available on the SunSITE FTP
675 server at sunsite.tk or Heiko Herold's windows wget spot - wGetGUI
676 offers a GUI interface that uses wget;
677 * WS_FTP from Ipswitch,
678 * the ftp command that comes with Windows.
680 If you use the ftp command, make sure you do the transfer in binary
681 mode rather than ASCII mode, by using the binary command before
682 transferring the file.
684 Q 2.2: When I try to download the WinPcap driver and library, I can't
685 get to the WinPcap Web site.
687 A: As is the case with all Web sites, that site won't necessarily
688 always be accessible; the server may be down due to a problem or down
689 for maintenance, or there may be a networking problem between you and
690 the server. You should try again later, or try the local mirror or the
691 Wiretapped.net mirror.
694 Q 3.1: I installed an Ethereal RPM, but Ethereal doesn't seem to be
695 installed; only Tethereal is installed.
697 A: Red Hat RPMs for Ethereal put only the non-GUI components into the
698 ethereal RPM, the fact that Ethereal is a GUI program nonwithstanding;
699 there's a separate ethereal-gnome RPM that includes GUI components
700 such as Ethereal itself, the fact that Ethereal doesn't use GNOME
701 nonwithstanding. Find the ethereal-gnome RPM, and install that also.
704 Q 4.1: The configure script can't find pcap.h or bpf.h, but I have
707 A: Are you sure pcap.h and bpf.h are installed? The official
708 distribution of libpcap only installs the libpcap.a library file when
709 "make install" is run. To install pcap.h and bpf.h, you must run "make
710 install-incl". If you're running Debian or Redhat, make sure you have
711 the "libpcap-dev" or "libpcap-devel" packages installed.
713 It's also possible that pcap.h and bpf.h have been installed in a
714 strange location. If this is the case, you may have to tweak
717 Q 4.2: Why do I get the error
719 dftest_DEPENDENCIES was already defined in condition TRUE, which
720 implies condition HAVE_PLUGINS_TRUE
722 when I try to build Ethereal from CVS or a CVS snapshot?
724 A: You probably have automake 1.5 installed on your machine (the
725 command automake --version will report the version of automake on your
726 machine). There is a bug in that version of automake that causes this
727 problem; upgrade to a later version of automake (1.6 or later).
729 Q 4.3: The link fails with a number of "Output line too long."
730 messages followed by linker errors.
732 A: The version of the sed command on your system is incapable of
733 handling very long lines. On Solaris, for example, /usr/bin/sed has a
734 line length limit too low to allow libtool to work; /usr/xpg4/bin/sed
735 can handle it, as can GNU sed if you have it installed.
737 On Solaris, changing your command search path to search /usr/xpg4/bin
738 before /usr/bin should make the problem go away; on any platform on
739 which you have this problem, installing GNU sed and changing your
740 command path to search the directory in which it is installed before
741 searching the directory with the version of sed that came with the OS
742 should make the problem go away.
744 Q 4.4: The link fails on Solaris because plugin_list is undefined.
746 A: This appears to be due to a problem with some versions of the GTK+
747 and GLib packages from www.sunfreeware.org; un-install those packages,
748 and try getting the 1.2.10 versions from that site, or the versions
749 from The Written Word, or the versions from Sun's GNOME distribution,
750 or the versions from the supplemental software CD that comes with the
751 Solaris media kit, or build them from source from the GTK Web site.
752 Then re-run the configuration script, and try rebuilding Ethereal. (If
753 you get the 1.2.10 versions from www.sunfreeware.org, and the problem
754 persists, un-install them and try installing one of the other versions
757 Q 4.5: The build fails on Windows because of conflicts between
758 winsock.h and winsock2.h.
760 A: As of Ethereal 0.9.5, you must install WinPcap 2.3 or later, and
761 the corresponding version of the developer's pack, in order to be able
762 to compile Ethereal; it will not compile with older versions of the
763 developer's pack. The symptoms of this failure are conflicts between
764 definitions in winsock.h and in winsock2.h; Ethereal uses winsock2.h,
765 but pre-2.3 versions of the WinPcap developer's packet use winsock.h.
766 (2.3 uses winsock2.h, so if Ethereal were to use winsock.h, it would
767 not be able to build with current versions of the WinPcap developer's
770 Note that the installed version of the developer's pack should be the
771 same version as the version of WinPcap you have installed.
774 Q 5.1: When I use Ethereal to capture packets, I see only packets to
775 and from my machine, or I'm not seeing all the traffic I'm expecting
776 to see from or to the machine I'm trying to monitor.
778 A: This might be because the interface on which you're capturing is
779 plugged into a switch; on a switched network, unicast traffic between
780 two ports will not necessarily appear on other ports - only broadcast
781 and multicast traffic will be sent to all ports.
783 Note that even if your machine is plugged into a hub, the "hub" may be
784 a switched hub, in which case you're still on a switched network.
786 Note also that on the Linksys Web site, they say that their
787 auto-sensing hubs "broadcast the 10Mb packets to the port that operate
788 at 10Mb only and broadcast the 100Mb packets to the ports that operate
789 at 100Mb only", which would indicate that if you sniff on a 10Mb port,
790 you will not see traffic coming sent to a 100Mb port, and vice versa.
791 This problem has also been reported for Netgear dual-speed hubs, and
792 may exist for other "auto-sensing" or "dual-speed" hubs.
794 Some switches have the ability to replicate all traffic on all ports
795 to a single port so that you can plug your analyzer into that single
796 port to sniff all traffic. You would have to check the documentation
797 for the switch to see if this is possible and, if so, to see how to do
798 this. See, for example:
799 * this documentation from Cisco on the Switched Port Analyzer (SPAN)
800 feature on Catalyst switches;
801 * documentation from HP on how to set "monitoring"/"mirroring" on
802 ports on the console for HP Advancestack Switch 208 and 224;
803 * the "Network Monitoring Port Features" section of chapter 6 of
804 documentation from HP for HP ProCurve Switches 1600M, 2424M,
807 Note also that many firewall/NAT boxes have a switch built into them;
808 this includes many of the "cable/DSL router" boxes. If you have a box
809 of that sort, that has a switch with some number of Ethernet ports
810 into which you plug machines on your network, and another Ethernet
811 port used to connect to a cable or DSL modem, you can, at least, sniff
812 traffic between the machines on your network and the Internet by
813 plugging the Ethernet port on the router going to the modem, the
814 Ethernet port on the modem, and the machine on which you're running
815 Ethereal into a hub (make sure it's not a switching hub, and that, if
816 it's a dual-speed hub, all three of those ports are running at the
819 If your machine is not plugged into a switched network or a dual-speed
820 hub, or it is plugged into a switched network but the port is set up
821 to have all traffic replicated to it, the problem might be that the
822 network interface on which you're capturing doesn't support
823 "promiscuous" mode, or because your OS can't put the interface into
824 promiscuous mode. Normally, network interfaces supply to the host
826 * packets sent to one of that host's link-layer addresses;
828 * multicast packets sent to a multicast address that the host has
829 configured the interface to accept.
831 Most network interfaces can also be put in "promiscuous" mode, in
832 which they supply to the host all network packets they see. Ethereal
833 will try to put the interface on which it's capturing into promiscuous
834 mode unless the "Capture packets in promiscuous mode" option is turned
835 off in the "Capture Options" dialog box, and Tethereal will try to put
836 the interface on which it's capturing into promiscuous mode unless the
837 -p option was specified. However, some network interfaces don't
838 support promiscuous mode, and some OSes might not allow interfaces to
839 be put into promiscuous mode.
841 If the interface is not running in promiscuous mode, it won't see any
842 traffic that isn't intended to be seen by your machine. It will see
843 broadcast packets, and multicast packets sent to a multicast MAC
844 address the interface is set up to receive.
846 You should ask the vendor of your network interface whether it
847 supports promiscuous mode. If it does, you should ask whoever supplied
848 the driver for the interface (the vendor, or the supplier of the OS
849 you're running on your machine) whether it supports promiscuous mode
850 with that network interface.
852 In the case of token ring interfaces, the drivers for some of them, on
853 Windows, may require you to enable promiscuous mode in order to
854 capture in promiscuous mode. Ask the vendor of the card how to do
855 this, or see, for example, this information on promiscuous mode on
856 some Madge token ring adapters (note that those cards can have
857 promiscuous mode disabled permanently, in which case you can't enable
860 In the case of wireless LAN interfaces, it appears that, when those
861 interfaces are promiscuously sniffing, they're running in a
862 significantly different mode from the mode that they run in when
863 they're just acting as network interfaces (to the extent that it would
864 be a significant effor for those drivers to support for promiscuously
865 sniffing and acting as regular network interfaces at the same time),
866 so it may be that Windows drivers for those interfaces don't support
869 Q 5.2: I can't see any TCP packets other than packets to and from my
870 machine, even though another analyzer on the network sees those
873 A: You're probably not seeing any packets other than unicast packets
874 to or from your machine, and broadcast and multicast packets; a switch
875 will normally send to a port only unicast traffic sent to the MAC
876 address for the interface on that port, and broadcast and multicast
877 traffic - it won't send to that port unicast traffic sent to a MAC
878 address for some other interface - and a network interface not in
879 promiscuous mode will receive only unicast traffic sent to the MAC
880 address for that interface, broadcast traffic, and multicast traffic
881 sent to a multicast MAC address the interface is set up to receive.
883 TCP doesn't use broadcast or multicast, so you will only see your own
884 TCP traffic, but UDP services may use broadcast or multicast so you'll
885 see some UDP traffic - however, this is not a problem with TCP
886 traffic, it's a problem with unicast traffic, as you also won't see
887 all UDP traffic between other machines.
889 I.e., this is probably the same question as this earlier one; see the
890 response to that question.
892 Q 5.3: I'm only seeing ARP packets when I try to capture traffic.
894 A: You're probably on a switched network, and running Ethereal on a
895 machine that's not sending traffic to the switch and not being sent
896 any traffic from other machines on the switch. ARP packets are often
897 broadcast packets, which are sent to all switch ports.
899 I.e., this is probably the same question as this earlier one; see the
900 response to that question.
902 Q 5.4: How do I put an interface into promiscuous mode?
904 A: By not disabling promiscuous mode when running Ethereal or
908 * the form of promiscuous mode that libpcap (the library that
909 programs such as tcpdump, Ethereal, etc. use to do packet capture)
910 turns on will not necessarily be shown if you run ifconfig on the
911 interface on a UNIX system;
912 * some network interfaces might not support promiscuous mode, and
913 some drivers might not allow promiscuous mode to be turned on -
914 see this earlier question for more information on that;
915 * the fact that you're not seeing any traffic, or are only seeing
916 broadcast traffic, or aren't seeing any non-broadcast traffic
917 other than traffic to or from the machine running Ethereal, does
918 not mean that promiscuous mode isn't on - see this earlier
919 question for more information on that.
921 I.e., this is probably the same question as this earlier one; see the
922 response to that question.
924 Q 5.5: I can set a display filter just fine, but capture filters don't
927 A: Capture filters currently use a different syntax than display
928 filters. Here's the corresponding section from the ethereal(1) man
931 "Display filters in Ethereal are very powerful; more fields are
932 filterable in Ethereal than in other protocol analyzers, and the
933 syntax you can use to create your filters is richer. As Ethereal
934 progresses, expect more and more protocol fields to be allowed in
937 Packet capturing is performed with the pcap library. The capture
938 filter syntax follows the rules of the pcap library. This syntax is
939 different from the display filter syntax."
941 The capture filter syntax used by libpcap can be found in the
944 Q 5.6: I'm entering valid capture filters, but I still get "parse
947 A: There is a bug in some versions of libpcap/WinPcap that cause it to
948 report parse errors even for valid expressions if a previous filter
949 expression was invalid and got a parse error.
951 Try exiting and restarting Ethereal; if you are using a version of
952 libpcap/WinPcap with this bug, this will "erase" its memory of the
953 previous parse error. If the capture filter that got the "parse error"
954 now works, the earlier error with that filter was probably due to this
957 The bug was fixed in libpcap 0.6; 0.4[.x] and 0.5[.x] versions of
958 libpcap have this bug, but 0.6[.x] and later versions don't.
960 Versions of WinPcap prior to 2.3 are based on pre-0.6 versions of
961 libpcap, and have this bug; WinPcap 2.3 is based on libpcap 0.6.2, and
962 doesn't have this bug.
964 If you are running Ethereal on a UNIX-flavored platform, run "ethereal
965 -v", or select "About Ethereal..." from the "Help" menu in Ethereal,
966 to see what version of libpcap it's using. If it's not 0.6 or later,
967 you will need either to upgrade your OS to get a later version of
968 libpcap, or will need to build and install a later version of libpcap
969 from the tcpdump.org Web site and then recompile Ethereal from source
970 with that later version of libpcap.
972 If you are running Ethereal on Windows with a pre-2.3 version of
973 WinPcap, you will need to un-install WinPcap and then download and
976 Q 5.7: I saved a filter and tried to use its name to filter the
977 display, but I got an "Unexpected end of filter string" error.
979 A: You cannot use the name of a saved display filter as a filter. To
980 filter the display, you can enter a display filter expression - not
981 the name of a saved display filter - in the "Filter:" box at the
982 bottom of the display, and type the key or press the "Apply" button
983 (that does not require you to have a saved filter), or, if you want to
984 use a saved filter, you can press the "Filter:" button, select the
985 filter in the dialog box that pops up, and press the "OK" button.
987 Q 5.8: Why am I seeing lots of packets with incorrect TCP checksums?
989 A: If the packets that have incorrect TCP checksums are all being sent
990 by the machine on which Ethereal is running, this is probably because
991 the network interface on which you're capturing does TCP checksum
992 offloading. That means that the TCP checksum is added to the packet by
993 the network interface, not by the OS's TCP/IP stack; when capturing on
994 an interface, packets being sent by the host on which you're capturing
995 are directly handed to the capture interface by the OS, which means
996 that they are handed to the capture interface without a TCP checksum
999 The only way to prevent this from happening would be to disable TCP
1000 checksum offloading, but
1001 1. that might not even be possible on some OSes;
1002 2. that could reduce networking performance significantly.
1004 However, you can disable the check that Ethereal does of the TCP
1005 checksum, so that it won't report any packets as having TCP checksum
1006 errors, and so that it won't refuse to do TCP reassembly due to a
1007 packet having an incorrect TCP checksum. That can be set as an
1008 Ethereal preference by selecting "Preferences" from the "Edit" menu,
1009 opening up the "Protocols" list in the left-hand pane of the
1010 "Preferences" dialog box, selecting "TCP", from that list, turning off
1011 the "Check the validity of the TCP checksum when possible" option,
1012 clicking "Save" if you want to save that setting in your preference
1013 file, and clicking "OK".
1015 It can also be set on the Ethereal or Tethereal command line with a -o
1016 tcp.check_checksum:false command-line flag, or manually set in your
1017 preferences file by adding a tcp.check_checksum:false line.
1019 Q 5.9: I've just installed Ethereal, and the traffic on my local LAN
1022 A: We have a collection of strange and exotic sample capture files at
1023 http://www.ethereal.com/sample/
1025 Q 5.10: When I run Ethereal on Solaris 8, it dies with a Bus Error
1028 A: Some versions of the GTK+ library from www.sunfreeware.org appear
1029 to be buggy, causing Ethereal to drop core with a Bus Error.
1030 Un-install those packages, and try getting the 1.2.10 version from
1031 that site, or the version from The Written Word, or the version from
1032 Sun's GNOME distribution, or the version from the supplemental
1033 software CD that comes with the Solaris media kit, or build it from
1034 source from the GTK Web site. Update the GLib library to the 1.2.10
1035 version, from the same source, as well. (If you get the 1.2.10
1036 versions from www.sunfreeware.org, and the problem persists,
1037 un-install them and try installing one of the other versions
1040 Similar problems may exist with older versions of GTK+ for earlier
1041 versions of Solaris.
1043 Q 5.11: When I run Ethereal on Windows NT, it dies with a Dr. Watson
1044 error, reporting an "Integer division by zero" exception, when I start
1047 A: In at least some case, this appears to be due to using the default
1048 VGA driver; if that's not the correct driver for your video card, try
1049 running the correct driver for your video card.
1051 Q 5.12: When I try to run Ethereal, it complains about
1052 sprint_realloc_objid being undefined.
1054 A: Ethereal can only be linked with version 4.2.2 or later of UCD
1055 SNMP. Your version of Ethereal was dynamically linked with such a
1056 version of UCD SNMP; however, you have an older version of UCD SNMP
1057 installed, which means that when Ethereal is run, it tries to link to
1058 the older version, and fails. You will have to replace that version of
1059 UCD SNMP with version 4.2.2 or a later version.
1061 Q 5.13: I'm running Ethereal on Linux; why do my time stamps have only
1062 100ms resolution, rather than 1us resolution?
1064 A: Ethereal gets time stamps from libpcap/WinPcap, and libpcap/WinPcap
1065 get them from the OS kernel, so Ethereal - and any other program using
1066 libpcap, such as tcpdump - is at the mercy of the time stamping code
1067 in the OS for time stamps.
1069 At least on x86-based machines, Linux can get high-resolution time
1070 stamps on newer processors with the Time Stamp Counter (TSC) register;
1071 for example, Intel x86 processors, starting with the Pentium Pro, and
1072 including all x86 processors since then, have had a TSC, and other
1073 vendors probably added the TSC at some point to their families of x86
1076 The Linux kernel must be configured with the CONFIG_X86_TSC option
1077 enabled in order to use the TSC. Make sure this option is enabled in
1080 In addition, some Linux distributions may have bugs in their versions
1081 of the kernel that cause packets not to be given high-resolution time
1082 stamps even if the TSC is enabled. See, for example, bug 61111 for Red
1083 Hat Linux 7.2. If your distribution has a bug such as this, you may
1084 have to run a standard kernel from kernel.org in order to get
1085 high-resolution time stamps.
1087 Q 5.14: I'm capturing packets on {Windows 95, Windows 98, Windows Me};
1088 why are the time stamps on packets wrong?
1090 A: This is due to a bug in WinPcap. The bug should be fixed in WinPcap
1093 Q 5.15: When I try to run Ethereal on Windows, it fails to run because
1094 it can't find packet.dll.
1096 A: In older versions of Ethereal, there were two binary distributions
1097 available for Windows, one that supported capturing packets, and one
1098 that didn't. The version that supported capturing packets required
1099 that you install the WinPcap driver; if you didn't install it, it
1100 would fail to run because it couldn't find packet.dll.
1102 The current version of Ethereal has only one binary distribution for
1103 Windows; that version will check whether WinPcap is installed and, if
1104 it's not, will disable support for packet capture.
1106 The WinPcap driver and libraries can be downloaded from the WinPcap
1107 Web site, the local mirror of the WinPcap Web site, or the
1108 Wiretapped.net mirror of the WinPcap site.
1110 Q 5.16: I'm running Ethereal on Windows; why does some network
1111 interface on my machine not show up in the list of interfaces in the
1112 "Interface:" field in the dialog box popped up by "Capture->Start",
1113 and/or why does Ethereal give me an error if I try to capture on that
1116 A: If you are running Ethereal on Windows NT 4.0, Windows 2000,
1117 Windows XP, or Windows Server, and this is the first time you have run
1118 a WinPcap-based program (such as Ethereal, or Tethereal, or WinDump,
1119 or Analyzer, or...) since the machine was rebooted, you need to run
1120 that program from an account with administrator privileges; once you
1121 have run such a program, you will not need administrator privileges to
1122 run any such programs until you reboot.
1124 If you are running on Windows 95/98/Me, or if you are running on
1125 Windows NT 4.0/2000/XP/Server and have administrator privileges or a
1126 WinPcap-based program has been run with those privileges since the
1127 machine rebooted, then note that Ethereal relies on the WinPcap
1128 library, on the WinPcap device driver, and on the facilities that come
1129 with the OS on which it's running in order to do captures.
1131 Therefore, if the OS, the WinPcap library, or the WinPcap driver don't
1132 support capturing on a particular network interface device, Ethereal
1133 won't be able to capture on that device.
1136 * 2.02 and earlier versions of the WinPcap driver and library that
1137 Ethereal uses for packet capture didn't support Token Ring
1138 interfaces; the current version, 2.3, does support Token Ring, and
1139 the current version of Ethereal works with (and, in fact,
1140 requires) WinPcap 2.1 or later.
1141 If you are having problems capturing on Token Ring interfaces, and
1142 you have WinPcap 2.02 or an earlier version of WinPcap installed,
1143 you should uninstall WinPcap, download and install the current
1144 version of WinPcap, and then install the latest version of
1146 * On Windows 95, 98, or Me, sometimes more than one interface will
1147 be given the same name; if that is the case, you will only be able
1148 to capture on one of those interfaces - it's not clear to which
1149 one the name, when used in a WinPcap-based application, will
1150 refer. For example, if you have a PPP serial interface and a VPN
1151 interface, they might show up with the same name, for example
1152 "ppp-mac", and if you try to capture on "ppp-mac", it might not
1153 capture on the interface you're currently using. In that case, you
1154 might, for example, have to remove the VPN interface from the
1155 system in order to capture on the PPP serial interface.
1156 * WinPcap doesn't support PPP WAN interfaces on Windows
1157 NT/2000/XP/Server, so Ethereal cannot capture packets on those
1158 devices when running on Windows NT/2000/XP/Server. Regular dial-up
1159 lines, ISDN lines, and various other lines such as T1/E1 lines are
1160 all PPP interfaces. This may cause the interface not to show up on
1161 the list of interfaces in the "Capture Options" dialog.
1162 * WinPcap prior to 3.0 does not support multiprocessor machines
1163 (note that machines with a single multi-threaded processor, such
1164 as Intel's new multi-threaded x86 processors, are multiprocessor
1165 machines as far as the OS and WinPcap are concerned), and recent
1166 2.x versions of WinPcap refuse to operate if they detect that
1167 they're running on a multiprocessor machine, which means that they
1168 may not show any network interfaces. You will need to use WinPcap
1169 3.0 to capture on a multiprocessor machine.
1171 If an interface doesn't show up in the list of interfaces in the
1172 "Interface:" field, and you know the name of the interface, try
1173 entering that name in the "Interface:" field and capturing on that
1176 If the attempt to capture on it succeeds, the interface is somehow not
1177 being reported by the mechanism Ethereal uses to get a list of
1178 interfaces; please report this to ethereal-dev@ethereal.com giving
1179 full details of the problem, including
1180 * the operating system you're using, and the version of that
1182 * the type of network device you're using.
1184 If you are having trouble capturing on a particular network interface,
1185 and you've made sure that (on platforms that require it) you've
1186 arranged that packet capture support is present, as per the above,
1187 first try capturing on that device with WinDump; see the WinDump Web
1188 site or the local mirror of the WinDump Web site for information on
1191 If you can capture on the interface with WinDump, send mail to
1192 ethereal-users@ethereal.com giving full details of the problem,
1194 * the operating system you're using, and the version of that
1196 * the type of network device you're using;
1197 * the error message you get from Ethereal.
1199 If you cannot capture on the interface with WinDump, this is almost
1200 certainly a problem with one or more of:
1201 * the operating system you're using;
1202 * the device driver for the interface you're using;
1203 * the WinPcap library and/or the WinPcap device driver;
1205 so first check the WinPcap FAQ, the local mirror of that FAQ, or the
1206 Wiretapped.net mirror of that FAQ, to see if your problem is mentioned
1207 there. If not, then see the WinPcap support page (or the local mirror
1208 of that page) - check the "Submitting bugs" section.
1210 You may also want to ask the ethereal-users@ethereal.com and the
1211 winpcap-users@winpcap.polito.it mailing lists to see if anybody
1212 happens to know about the problem and know a workaround or fix for the
1213 problem. (Note that you will have to subscribe to that list in order
1214 to be allowed to mail to it; see the WinPcap support page, or the
1215 local mirror of that page, for information on the mailing list.) In
1216 your mail, please give full details of the problem, as described
1217 above, and also indicate that the problem occurs with WinDump, not
1220 Q 5.17: I'm running on a UNIX-flavored OS; why does some network
1221 interface on my machine not show up in the list of interfaces in the
1222 "Interface:" field in the dialog box popped up by "Capture->Start",
1223 and/or why does Ethereal give me an error if I try to capture on that
1226 A: You may need to run Ethereal from an account with sufficient
1227 privileges to capture packets, such as the super-user account. Only
1228 those interfaces that Ethereal can open for capturing show up in that
1229 list; if you don't have sufficient privileges to capture on any
1230 interfaces, no interfaces will show up in the list.
1232 If you are running Ethereal from an account with sufficient
1233 privileges, then note that Ethereal relies on the libpcap library, and
1234 on the facilities that come with the OS on which it's running in order
1237 Therefore, if the OS or the libpcap library don't support capturing on
1238 a particular network interface device, Ethereal won't be able to
1239 capture on that device.
1241 On Linux, note that you need to have "packet socket" support enabled
1242 in your kernel; see the "Packet socket" item in the Linux
1243 "Configure.help" file.
1245 On BSD, note that you need to have BPF support enabled in your kernel;
1246 see the documentation for your system for information on how to enable
1247 BPF support (if it's not enabled by default on your system).
1249 On DEC OSF/1, Digital UNIX, or Tru64 UNIX, note that you need to have
1250 packet filtering support in your kernel; the doconfig command will
1251 allow you to configure and build a new kernel with that option.
1253 On Solaris, note that libpcap 0.6.2 and earlier didn't support Token
1254 Ring interfaces; the current version, 0.7.2, does support Token Ring,
1255 and the current version of Ethereal works with libcap 0.7.2 and later.
1257 If an interface doesn't show up in the list of interfaces in the
1258 "Interface:" field, and you know the name of the interface, try
1259 entering that name in the "Interface:" field and capturing on that
1262 If the attempt to capture on it succeeds, the interface is somehow not
1263 being reported by the mechanism Ethereal uses to get a list of
1264 interfaces; please report this to ethereal-dev@ethereal.com giving
1265 full details of the problem, including
1266 * the operating system you're using, and the version of that
1267 operating system (for Linux, give both the version number of the
1268 kernel and the name and version number of the distribution you're
1270 * the type of network device you're using.
1272 If you are having trouble capturing on a particular network interface,
1273 and you've made sure that (on platforms that require it) you've
1274 arranged that packet capture support is present, as per the above,
1275 first try capturing on that device with tcpdump.
1277 If you can capture on the interface with tcpdump, send mail to
1278 ethereal-users@ethereal.com giving full details of the problem,
1280 * the operating system you're using, and the version of that
1281 operating system (for Linux, give both the version number of the
1282 kernel and the name and version number of the distribution you're
1284 * the type of network device you're using;
1285 * the error message you get from Ethereal.
1287 If you cannot capture on the interface with tcpdump, this is almost
1288 certainly a problem with one or more of:
1289 * the operating system you're using;
1290 * the device driver for the interface you're using;
1291 * the libpcap library;
1293 so you should report the problem to the company or organization that
1294 produces the OS (in the case of a Linux distribution, report the
1295 problem to whoever produces the distribution).
1297 You may also want to ask the ethereal-users@ethereal.com and the
1298 tcpdump-workers@tcpdump.org mailing lists to see if anybody happens to
1299 know about the problem and know a workaround or fix for the problem.
1300 In your mail, please give full details of the problem, as described
1301 above, and also indicate that the problem occurs with tcpdump not just
1304 Q 5.18: I'm running Ethereal on Windows NT/2000/XP/Server; my machine
1305 has a PPP (dial-up POTS, ISDN, etc.) interface, and it shows up in the
1306 "Interface" item in the "Capture Options" dialog box. Why can no
1307 packets be sent on or received from that network while I'm trying to
1308 capture traffic on that interface?
1310 A: WinPcap doesn't support PPP WAN interfaces on Windows
1311 NT/2000/XP/Server; one symptom that may be seen is that attempts to
1312 capture in promiscuous mode on the interface cause the interface to be
1313 incapable of sending or receiving packets. You can disable promiscuous
1314 mode using the -p command-line flag or the item in the "Capture
1315 Preferences" dialog box, but this may mean that outgoing packets, or
1316 incoming packets, won't be seen in the capture.
1318 Q 5.19: I'm running Ethereal on Windows 95/98/Me, on a machine with
1319 more than one network adapter of the same type; Ethereal shows all of
1320 those adapters with the same name, but I can't use any of those
1321 adapters other than the first one.
1323 A: Unfortunately, Windows 95/98/Me gives the same name to multiple
1324 instances of the type of same network adapter. Therefore, WinPcap
1325 cannot distinguish between them, so a WinPcap-based application can
1326 capture only on the first such interface; Ethereal is a
1327 libpcap/WinPcap-based application.
1329 Q 5.20: I'm running Ethereal on Windows, and I'm not seeing any
1330 traffic being sent by the machine running Ethereal.
1332 A: If you are running some form of VPN client software, it might be
1333 causing this problem; people have seen this problem when they have
1334 Check Point's VPN software installed on their machine. If that's the
1335 cause of the problem, you will have to remove the VPN software in
1336 order to have Ethereal (or any other application using WinPcap) see
1337 outgoing packets; unfortunately, neither we nor the WinPcap developers
1338 know any way to make WinPcap and the VPN software work well together.
1340 Also, some drivers for Windows (especially some wireless network
1341 interface drivers) apparently do not, when running in promiscuous
1342 mode, arrange that outgoing packets are delivered to the software that
1343 requested that the interface run promiscuously; try turning
1344 promiscuous mode off.
1346 Q 5.21: I'm trying to capture traffic but I'm not seeing any.
1348 A: Is the machine running Ethereal sending out any traffic on the
1349 network interface on which you're capturing, or receiving any traffic
1350 on that network, or is there any broadcast traffic on the network or
1351 multicast traffic to a multicast group to which the machine running
1354 If not, this may just be a problem with promiscuous sniffing, either
1355 due to running on a switched network or a dual-speed hub, or due to
1356 problems with the interface not supporting promiscuous mode; see the
1357 response to this earlier question.
1359 Otherwise, on Windows, see the response to this question and, on a
1360 UNIX-flavored OS, see the response to this question.
1362 Q 5.22: I have an XXX network card on my machine; if I try to capture
1363 on it, my machine crashes or resets itself.
1365 A: This is almost certainly a problem with one or more of:
1366 * the operating system you're using;
1367 * the device driver for the interface you're using;
1368 * the libpcap/WinPcap library and, if this is Windows, the WinPcap
1372 * if you are using Windows, see the WinPcap support page (or the
1373 local mirror of that page) - check the "Submitting bugs" section;
1374 * if you are using some Linux distribution, some version of BSD, or
1375 some other UNIX-flavored OS, you should report the problem to the
1376 company or organization that produces the OS (in the case of a
1377 Linux distribution, report the problem to whoever produces the
1380 Q 5.23: My machine crashes or resets itself when I select "Start" from
1381 the "Capture" menu or select "Preferences" from the "Edit" menu.
1383 A: Both of those operations cause Ethereal to try to build a list of
1384 the interfaces that it can open; it does so by getting a list of
1385 interfaces and trying to open them. There is probably an OS, driver,
1386 or, for Windows, WinPcap bug that causes the system to crash when this
1387 happens; see the previous question.
1389 Q 5.24: Does Ethereal work on Windows ME?
1391 A: Yes, but if you want to capture packets, you will need to install
1392 the latest version of WinPcap, as 2.02 and earlier versions of WinPcap
1393 didn't support Windows ME. You should also install the latest version
1394 of Ethereal as well.
1396 Q 5.25: Does Ethereal work on Windows XP?
1398 A: Yes, but if you want to capture packets, you will need to install
1399 the latest version of WinPcap, as 2.2 and earlier versions of WinPcap
1400 didn't support Windows XP.
1402 Q 5.26: Why doesn't Ethereal correctly identify RTP packets? It shows
1405 A: Ethereal can identify a UDP datagram as containing a packet of a
1406 particular protocol running atop UDP only if
1407 1. The protocol in question has a particular standard port number,
1408 and the UDP source or destination port number is that port
1409 2. Packets of that protocol can be identified by looking for a
1410 "signature" of some type in the packet - i.e., some data that, if
1411 Ethereal finds it in some particular part of a packet, means that
1412 the packet is almost certainly a packet of that type.
1413 3. Some other traffic earlier in the capture indicated that, for
1414 example, UDP traffic between two particular addresses and ports
1415 will be RTP traffic.
1417 RTP doesn't have a standard port number, so 1) doesn't work; it
1418 doesn't, as far as I know, have any "signature", so 2) doesn't work.
1420 That leaves 3). If there's RTSP traffic that sets up an RTP session,
1421 then, at least in some cases, the RTSP dissector will set things up so
1422 that subsequent RTP traffic will be identified. Currently, that's the
1423 only place we do that; there may be other places.
1425 However, there will always be places where Ethereal is simply
1426 incapable of deducing that a given UDP flow is RTP; a mechanism would
1427 be needed to allow the user to specify that a given conversation
1428 should be treated as RTP. As of Ethereal 0.8.16, such a mechanism
1429 exists; if you select a UDP or TCP packet, the right mouse button menu
1430 will have a "Decode As..." menu item, which will pop up a dialog box
1431 letting you specify that the source port, the destination port, or
1432 both the source and destination ports of the packet should be
1433 dissected as some particular protocol.
1435 Q 5.27: Why doesn't Ethereal show Yahoo Messenger packets in captures
1436 that contain Yahoo Messenger traffic?
1438 A: Ethereal only recognizes as Yahoo Messenger traffic packets to or
1439 from TCP port 3050 that begin with "YPNS", "YHOO", or "YMSG". TCP
1440 segments that start with the middle of a Yahoo Messenger packet that
1441 takes more than one TCP segment will not be recognized as Yahoo
1442 Messenger packets (even if the TCP segment also contains the beginning
1443 of another Yahoo Messenger packet).
1445 Q 5.28: Why do I get the error
1447 Gdk-ERROR **: Palettized display (256-colour) mode not supported on
1451 when I try to run Ethereal on Windows?
1453 A: Ethereal is built using the GTK+ toolkit, which supports most
1454 UNIX-flavored OSes, and also supports Windows.
1456 Windows versions of Ethereal before 0.9.14 were built with an older
1457 version of that toolkit, which didn't support 256-color mode on
1458 Windows - it required HiColor (16-bit colors) or more.
1460 Windows versions of Ethereal 0.9.14 and later are built with a version
1461 of that toolkit that supports 256-color mode; upgrade to the current
1462 version of Ethereal if you want to run on a display in 256-color mode.
1464 Q 5.29: When I capture on Windows in promiscuous mode, I can see
1465 packets other than those sent to or from my machine; however, those
1466 packets show up with a "Short Frame" indication, unlike packets to or
1467 from my machine. What should I do to arrange that I see those packets
1470 A: In at least some cases, this appears to be the result of PGPnet
1471 running on the network interface on which you're capturing; turn it
1472 off on that interface.
1474 Q 5.30: How can I capture raw 802.11 packets, including non-data
1475 (management, beacon) packets?
1477 A: That would require that your 802.11 interface run in the mode
1478 called "monitor mode" or "RFMON mode". Not all operating systems
1479 support that and, even on operating systems that do support it, not
1480 all drivers, and thus not all cards, support it.
1482 Cisco Aironet cards:
1484 The only platforms that allow Ethereal to capture raw 802.11 packets
1485 on Cisco Aironet cards are:
1486 * Linux, with a 2.4.6 or later kernel;
1487 * FreeBSD 4.6 or later, as the driver in FreeBSD 4.5 has bugs that
1488 cause packets not to be captured correctly, and the driver in
1489 releases prior to 4.5 didn't support capturing raw packets.
1491 On FreeBSD, the ancontrol utility must be used; do not enable the full
1492 Aironet header via BPF, as Ethereal doesn't currently support that.
1494 On Linux with the driver in the 2.4.6 through 2.4.19 kernel, you will
1497 echo "Mode: rfmon" >/proc/driver/aironet/ethN/Config
1499 if your Aironet card is ethN. To capture traffic from any BSS, do
1501 echo "Mode: y" >/proc/driver/aironet/ethN/Config
1503 and to return to the normal mode, do
1505 echo "Mode: ess" >/proc/driver/aironet/ethN/Config
1507 On Linux with the driver in the 2.4.20 kernel, or with the CVS drivers
1508 from the airo-linux SourceForge site, you will have to capture on the
1509 wifiN interface if your Aironet card is ethN, after running the
1510 commands listed above.
1512 In all of those cases, Ethereal would have to be linked with libpcap
1513 0.7.1 or later; this means that most Ethereal binary packages won't
1514 work unless they're statically linked with libpcap 0.7.1 or later, or
1515 they're dynamically linked with libpcap and your system has a libpcap
1516 0.7.1 or later shared library installed (note that libpcap source
1517 package from tcpdump.org does not build shared libraries). Some binary
1518 packaging mechanisms might make it difficult to install Ethereal
1519 binary packages built to depend on older libpcap binary packages if
1520 you have a newer libpcap binary package installed; the installer
1521 programs for those packaging mechanisms might support disabling
1522 dependency checking so that they will install Ethereal even though a
1523 newer version of libpcap is installed.
1525 Cards using the Prism II chip set (see this page of Linux 802.11
1526 information for details on wireless cards, including information on
1527 the chips they use):
1529 You can capture raw 802.11 packets with Prism II cards on Linux
1530 systems with the 0.1.14-pre6 or later version of the linux-wlan-ng
1531 drivers (see the linux-wlan page, and the linux-wlan-ng tarball
1534 Those require either Solomon Peachy's patch to libpcap 0.7.1 (see his
1535 libpcap-0.7.1-prism.diff file, or his RPMs of that version of
1536 libpcap), or the current CVS version of libpcap, which includes his
1537 patch (download it from the "Current Tar files" section of the
1538 tcpdump.org Web site). If you apply his patches to libpcap 0.7.1 and
1539 rebuild and install libpcap, or if you build and install the current
1540 CVS version of libpcap, you would have to rebuild Ethereal from
1541 source, linking it with that new version of libpcap; an Ethereal
1542 binary package would not work. Ethereal binary packages might work if
1543 you install the libpcap-0.7.1-1prism.i386.rpm RPM, as it might install
1544 a libpcap shared library in place of the one on your system.
1546 You may have to run a command to put the interface into monitor mode,
1547 or to change other interface settings, and you might have to capture
1548 on a wlanN interface rather than a ethN interface, in order to capture
1549 raw 802.11 packets. The interface settings are available in your
1550 wlan-ng.conf file. See the wlan-ng FAQ for additional information.
1552 On other platforms, capturing raw 802.11 packets on Prism II cards is
1553 not currently supported.
1555 Orinoco Silver and Gold cards:
1557 On Linux systems, there are patches on the Orinoco Monitor Mode Patch
1558 Page that should allow you to do capture raw 802.11 packets. You will
1559 have to determine which version of the driver you have, and select the
1562 Note that the page indicates that not all versions of the Orinoco
1563 firmware support this patch. It says, for some versions of the patch,
1564 "This patch should allow monitor mode with v8.10 firmware (untested w/
1565 8.42);" if you have version 8.10 or later firmware on your Orinoco
1566 cards, you might have to use those patches, with the corresponding
1567 versions of the Orinoco driver, in order to run in monitor mode.
1569 That patch is written for the drivers included with the pcmcia-cs
1570 drivers, but works equally well for the Orinoco drivers provided with
1571 Linux kernels up to 2.4.20. To apply a patch to your kernel drivers,
1572 simply copy the orinoco-09b-patch.diff file to the
1573 /usr/src/linux/drivers/net directory and patch according to the
1574 directions on the Orinoco Monitor Mode Patch Page. You can double-
1575 check the version of the Orinoco drivers that shipped with your kernel
1576 by examining the first few lines of the orinoco.c file.
1578 Te Orinoco patches require either Solomon Peachy's patch to libpcap
1579 0.7.1 (see his libpcap-0.7.1-prism.diff file, or his RPMs of that
1580 version of libpcap), or the current CVS version of libpcap, which
1581 includes his patch (download it from the "Current Tar files" section
1582 of the tcpdump.org Web site). If you apply his patches to libpcap
1583 0.7.1 and rebuild and install libpcap, or if you build and install the
1584 current CVS version of libpcap, you would have to rebuild Ethereal
1585 from source, linking it with that new version of libpcap; an Ethereal
1586 binary package would not work. Ethereal binary packages might work if
1587 you install the libpcap-0.7.1-1prism.i386.rpm RPM, as it might install
1588 a libpcap shared library in place of the one on your system.
1590 On other platforms, capturing raw 802.11 packets on Orinoco cards is
1591 not currently supported.
1593 Other 802.11 interfaces:
1595 With other 802.11 interfaces, no platform allows Ethereal to capture
1596 raw 802.11 packets, as far as we know. If you know of other 802.11
1597 interfaces that are supported (note that there are many "Prism II
1598 cards", so your card might be a Prism II card), please let us know,
1599 and include URLs for sites containing any necessary patches to add
1602 On platforms that don't allow Ethereal to capture raw 802.11 packets,
1603 the 802.11 network will appear like an Ethernet to Ethereal.
1605 Q 5.31: How can I capture packets with CRC errors?
1607 A: Ethereal can capture only the packets that the packet capture
1608 library - libpcap on UNIX-flavored OSes, and the WinPcap port to
1609 Windows of libpcap on Windows - can capture, and libpcap/WinPcap can
1610 capture only the packets that the OS's raw packet capture mechanism
1611 (or the WinPcap driver, and the underlying OS networking code and
1612 network interface drivers, on Windows) will allow it to capture.
1614 Unless the OS can be configured to supply packets with errors such as
1615 invalid CRCs to the raw packet capture mechanism, Ethereal - and other
1616 programs that capture raw packets, such as tcpdump - cannot capture
1617 those packets. 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 those packets.
1622 Q 5.32: How can I capture entire frames, including the FCS?
1624 A: Ethereal can't capture any data that the packet capture library -
1625 libpcap on UNIX-flavored OSes, and the WinPcap port to Windows of
1626 libpcap on Windows - can capture, and libpcap/WinPcap can capture only
1627 the data that the OS's raw packet capture mechanism (or the WinPcap
1628 driver, and the underlying OS networking code and network interface
1629 drivers, on Windows) will allow it to capture.
1631 For any particular link-layer network type, unless the OS supplies the
1632 FCS of a frame as part of the frame, or can be configured to supply
1633 the FCS of a frame as part of the frame, Ethereal - and other programs
1634 that capture raw packets, such as tcpdump - cannot capture the FCS of
1635 a frame. You will have to determine whether your OS can be so
1636 configured, configure it if possible, and make whatever changes to
1637 libpcap and the packet capture program you're using are necessary to
1638 support capturing the FCS of a frame. Most if not all OSes probably do
1639 not support capturing the FCS of a frame on Ethernet, and probably do
1640 not support it on most other link-layer types.
1642 Q 5.33: Ethereal hangs after I stop a capture.
1644 A: The most likely reason for this is that Ethereal is trying to look
1645 up an IP address in the capture to convert it to a name (so that, for
1646 example, it can display the name in the source address or destination
1647 address columns), and that lookup process is taking a very long time.
1649 Ethereal calls a routine in the OS of the machine on which it's
1650 running to convert of IP addresses to the corresponding names. That
1651 routine probably does one or more of:
1652 * a search of a system file listing IP addresses and names;
1653 * a lookup using DNS;
1654 * on UNIX systems, a lookup using NIS;
1655 * on Windows systems, a NetBIOS-over-TCP query.
1657 If a DNS server that's used in an address lookup is not responding,
1658 the lookup will fail, but will only fail after a timeout while the
1659 system routine waits for a reply.
1661 In addition, on Windows systems, if the DNS lookup of the address
1662 fails, either because the server isn't responding or because there are
1663 no records in the DNS that could be used to map the address to a name,
1664 a NetBIOS-over-TCP query will be made. That query involves sending a
1665 message to the NetBIOS-over-TCP name service on that machine, asking
1666 for the name and other information about the machine. If the machine
1667 isn't running software that responds to those queries - for example,
1668 many non-Windows machines wouldn't be running that software - the
1669 lookup will only fail after a timeout. Those timeouts can cause the
1670 lookup to take a long time.
1672 If you disable network address-to-name translation - for example, by
1673 turning off the "Enable network name resolution" option in the "Name
1674 resolution" options in the dialog box you get by selecting
1675 "Preferences" from the "Edit" menu - the lookups of the address won't
1676 be done, which may speed up the process of reading the capture file
1677 after the capture is stopped. You can make that setting the default by
1678 using the "Save" button in that dialog box; note that this will save
1679 all your current preference settings.
1681 If Ethereal hangs when reading a capture even with network name
1682 resolution turned off, there might, for example, be a bug in one of
1683 Ethereal's dissectors for a protocol causing it to loop infinitely.
1684 The bug should be reported to the Ethereal developers' mailing list at
1685 ethereal-dev@ethereal.com.
1687 On UNIX-flavored OSes, please try to force Ethereal to dump core, by
1688 sending it a SIGABRT signal (usually signal 6) with the kill command,
1689 and then get a stack trace if you have a debugger installed. A stack
1690 trace can be obtained by using your debugger (gdb in this example),
1691 the Ethereal binary, and the resulting core file. Here's an example of
1692 how to use the gdb command backtrace to do so.
1695 ..... prints the stack trace
1699 The core dump file may be named "ethereal.core" rather than "core" on
1700 some platforms (e.g., BSD systems)
1702 Also, if at all possible, please send a copy of the capture file that
1703 caused the problem; when capturing packets, Ethereal normally writes
1704 captured packets to a temporary file, which will probably be in /tmp
1705 or /var/tmp on UNIX-flavored OSes and \TEMP on Windows, so the capture
1706 file will probably be there. It will have a name beginning with ether,
1707 with some mixture of letters and numbers after that. Please don't send
1708 a trace file greater than 1 MB when compressed. If the trace file
1709 contains sensitive information (e.g., passwords), then please do not
1712 Q 5.34: How can I search for, or filter, packets that have a
1713 particular string anywhere in them?
1715 A: If you want to do this when capturing, you can't. That's a feature
1716 that would be hard to implement in capture filters without changes to
1717 the capture filter code, which, on many platforms, is in the OS kernel
1718 and, on other platforms, is in the libpcap library.
1720 In releases prior to 0.9.14, you also can't search for, or filter,
1721 packets containing a particular string even after you've captured
1724 In 0.9.14, you can search for, but not filter, packets that have a
1725 particular string; this has been added to the "Find Frame" dialog
1726 ("Find Frame" under the "Edit" menu, or control-F).
1729 Support can be found on the ethereal-users[AT]ethereal.com mailing
1731 For corrections/additions/suggestions for this page, please send email
1732 to: ethereal-web[AT]ethereal.com
1733 Last modified: Tue, August 19 2003.
git.samba.org / obnox / wireshark / wip.git / blob