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.html for the up
6 to date version. The version of this snapshot can be found at
7 the end of this document.
14 1.1 Where can I get help?
16 1.2 How much does Ethereal cost?
18 1.3 Can I use Ethereal commercially?
20 1.4 Can I use Ethereal as part of my commercial product?
22 1.5 What protocols are currently supported?
24 1.6 Are there any plans to support {your favorite protocol}?
26 1.7 Can Ethereal read capture files from {your favorite network analyzer}?
28 1.8 What devices can Ethereal use to capture packets?
30 1.9 How do you pronounce Ethereal? Where did the name come from?
32 2. Downloading Ethereal:
34 2.1 I downloaded the Win32 installer, but when I try to run it, I get an
37 2.2 When I try to download the WinPcap driver and library, I can't get to
40 3. Installing Ethereal:
42 3.1 I installed an Ethereal RPM, but Ethereal doesn't seem to be installed;
43 only Tethereal is installed.
47 4.1 The configure script can't find pcap.h or bpf.h, but I have libpcap
50 4.2 Why do I get the error
52 dftest_DEPENDENCIES was already defined in condition TRUE, which implies
53 condition HAVE_PLUGINS_TRUE
55 when I try to build Ethereal from SVN or a SVN snapshot?
57 4.3 The link fails with a number of "Output line too long." messages
58 followed by linker errors.
60 4.4 The link fails on Solaris because plugin_list is undefined.
62 4.5 The build fails on Windows because of conflicts between winsock.h and
67 5.1 When I use Ethereal to capture packets, I see only packets to and from
68 my machine, or I'm not seeing all the traffic I'm expecting to see from or
69 to the machine I'm trying to monitor.
71 5.2 I can't see any TCP packets other than packets to and from my machine,
72 even though another analyzer on the network sees those packets.
74 5.3 I'm only seeing ARP packets when I try to capture traffic.
76 5.4 I'm running Ethereal on Windows; why does some network interface on my
77 machine not show up in the list of interfaces in the "Interface:" field in
78 the dialog box popped up by "Capture->Start", and/or why does Ethereal give
79 me an error if I try to capture on that interface?
81 5.5 I'm running Ethereal on Windows; why do no network interfaces show up in
82 the list of interfaces in the "Interface:" field in the dialog box popped up
85 5.6 I'm running Ethereal on Windows; why doesn't my serial port/ADSL
86 modem/ISDN modem show up in the list of interfaces in the "Interface:" field
87 in the dialog box popped up by "Capture->Start"?
89 5.7 I'm running Ethereal on a UNIX-flavored OS; why does some network
90 interface on my machine not show up in the list of interfaces in the
91 "Interface:" field in the dialog box popped up by "Capture->Start", and/or
92 why does Ethereal give me an error if I try to capture on that interface?
94 5.8 I'm running Ethereal on a UNIX-flavored OS; why do no network interfaces
95 show up in the list of interfaces in the "Interface:" field in the dialog
96 box popped up by "Capture->Start"?
98 5.9 Can Ethereal capture on (my T1/E1 line, SS7 links, etc.)?
100 5.10 How do I put an interface into promiscuous mode?
102 5.11 I can set a display filter just fine, but capture filters don't work.
104 5.12 I'm entering valid capture filters, but I still get "parse error"
107 5.13 I saved a filter and tried to use its name to filter the display, but I
108 got an "Unexpected end of filter string" error.
110 5.14 Why am I seeing lots of packets with incorrect TCP checksums?
112 5.15 I've just installed Ethereal, and the traffic on my local LAN is
115 5.16 When I run Ethereal on Solaris 8, it dies with a Bus Error when I start
118 5.17 When I run Ethereal, I get an error
120 Gtk-CRITICAL **: file gtkwindow.c: line 3107 (gtk_window_resize):
121 assertion `height > 0' failed.
123 5.18 When I run Tethereal with the "-x" option, it crashes with an error
125 "** ERROR **: file print.c: line 691 (print_line): should not be reached.
127 5.19 When I run Ethereal on Windows NT, it dies with a Dr. Watson error,
128 reporting an "Integer division by zero" exception, when I start it.
130 5.20 When I try to run Ethereal, it complains about sprint_realloc_objid
133 5.21 I'm running Ethereal on Linux; why do my time stamps have only 100ms
134 resolution, rather than 1us resolution?
136 5.22 I'm capturing packets on {Windows 95, Windows 98, Windows Me}; why are
137 the time stamps on packets wrong?
139 5.23 When I try to run Ethereal on Windows, it fails to run because it can't
142 5.24 I'm running Ethereal on Windows NT 4.0/Windows 2000/Windows XP/Windows
143 Server 2003; my machine has a PPP (dial-up POTS, ISDN, etc.) interface, and
144 it shows up in the "Interface" item in the "Capture Options" dialog box. Why
145 can no packets be sent on or received from that network while I'm trying to
146 capture traffic on that interface?
148 5.25 I'm running Ethereal on Windows 95/98/Me, on a machine with more than
149 one network adapter of the same type; Ethereal shows all of those adapters
150 with the same name, but I can't use any of those adapters other than the
153 5.26 I'm running Ethereal on Windows, and I'm not seeing any traffic being
154 sent by the machine running Ethereal.
156 5.27 I'm trying to capture traffic but I'm not seeing any.
158 5.28 I have an XXX network card on my machine; if I try to capture on it, my
159 machine crashes or resets itself.
161 5.29 My machine crashes or resets itself when I select "Start" from the
162 "Capture" menu or select "Preferences" from the "Edit" menu.
164 5.30 Does Ethereal work on Windows Me?
166 5.31 Does Ethereal work on Windows XP?
168 5.32 Why doesn't Ethereal correctly identify RTP packets? It shows them only
171 5.33 Why doesn't Ethereal show Yahoo Messenger packets in captures that
172 contain Yahoo Messenger traffic?
174 5.34 Why do I get the error
176 Gdk-ERROR **: Palettized display (256-colour) mode not supported on
180 when I try to run Ethereal on Windows?
182 5.35 When I capture on Windows in promiscuous mode, I can see packets other
183 than those sent to or from my machine; however, those packets show up with a
184 "Short Frame" indication, unlike packets to or from my machine. What should
185 I do to arrange that I see those packets in their entirety?
187 5.36 I'm capturing packets on a machine on a VLAN; why don't the packets I'm
188 capturing have VLAN tags?
190 5.37 How can I capture raw 802.11 frames, including non-data (management,
193 5.38 How do I capture on an 802.11 device in monitor mode?
195 5.39 I'm trying to capture 802.11 traffic on Windows; why am I not seeing
198 5.40 I'm trying to capture 802.11 traffic on Windows; why am I seeing
199 packets received by the machine on which I'm capturing traffic, but not
200 packets sent by that machine?
202 5.41 How can I capture packets with CRC errors?
204 5.42 How can I capture entire frames, including the FCS?
206 5.43 Why does Ethereal hang after I stop a capture?
208 5.44 How can I search for, or filter, packets that have a particular string
211 5.45 How do I filter a capture to see traffic for virus XXX?
215 Q 1.1: Where can I get help?
217 A: Support is available on the ethereal-users mailing list. Subscription
218 information and archives for all of Ethereal's mailing lists can be found at
219 http://www.ethereal.com/lists
221 Q 1.2: How much does Ethereal cost?
223 A: Ethereal is "free software"; you can download it without paying any
224 license fee. The version of Ethereal you download isn't a "demo" version,
225 with limitations not present in a "full" version; it is the full version.
227 The license under which Ethereal is issued is the GNU General Public
228 License. See the GNU GPL FAQ for some more information.
230 Q 1.3: Can I use Ethereal commercially?
232 A: Yes, if, for example, you mean "I work for a commercial organization; can
233 I use Ethereal to capture and analyze network traffic in our company's
234 networks or in our customer's networks?"
236 If you mean "Can I use Ethereal as part of my commercial product?", see the
237 next entry in the FAQ.
239 Q 1.4: Can I use Ethereal as part of my commercial product?
241 A: As noted, Ethereal is licensed under the GNU General Public License. The
242 GPL imposes conditions on your use of GPL'ed code in your own products; you
243 cannot, for example, make a "derived work" from Ethereal, by making
244 modifications to it, and then sell the resulting derived work and not allow
245 recipients to give away the resulting work. You must also make the changes
246 you've made to the Ethereal source available to all recipients of your
247 modified version; those changes must also be licensed under the terms of the
248 GPL. See the GPL FAQ for more details; in particular, note the answer to the
249 question about modifying a GPLed program and selling it commercially, and
250 the question about linking GPLed code with other code to make a proprietary
253 You can combine a GPLed program such as Ethereal and a commercial program as
254 long as they communicate "at arm's length", as per this item in the GPL FAQ.
256 Q 1.5: What protocols are currently supported?
258 A: There are currently 706 supported protocols and media, listed below.
259 Descriptions can be found in the ethereal(1) man page.
261 3Com XNS Encapsulation
264 802.1X Authentication
265 AAL type 2 signalling protocol - Capability set 1 (Q.2630.1)
268 AFS (4.0) Replication Server call declarations
271 AIM Buddylist Service
278 AIM Invitation Service
283 AIM Privacy Management Service
285 AIM Server Side Themes
292 ANSI IS-637-A (SMS) Teleservice Layer
293 ANSI IS-637-A (SMS) Transport Layer
294 ANSI IS-683-A (OTA (Mobile))
295 ANSI IS-801 (Location Services (PLD))
296 ANSI Mobile Application Part
297 AOL Instant Messenger
306 AVS WLAN Capture header
308 Active Directory Setup
309 Ad hoc On-demand Distance Vector Routing Protocol
311 Address Resolution Protocol
313 Aggregate Server Access Protocol
315 Alteon - Transparent Proxy Cache Protocol
316 Andrew File System (AFS)
317 Apache JServ Protocol v1.3
318 Apple Filing Protocol
319 Apple IP-over-IEEE 1394
320 AppleTalk Session Protocol
321 AppleTalk Transaction Protocol packet
322 Appletalk Address Resolution Protocol
323 Application Configuration Access Protocol
325 Aruba - Aruba Discovery Protocol
326 Async data over ISDN (V.120)
327 Asynchronous Layered Coding
328 AudioCodes Trunk Trace
329 Authentication Header
330 BACnet Virtual Link Control
335 Banyan Vines Fragmentation Protocol
342 Base Station Subsystem GPRS Protocol
343 Basic Encoding Rules (ASN.1 X.690)
344 Bearer Independent Call Control
345 Bi-directional Fault Detection Control Message
347 Blocks Extensible Exchange Protocol
348 Blubster/Piolet MANOLITO Protocol
352 Border Gateway Protocol
353 Building Automation and Control Network APDU
354 Building Automation and Control Network NPDU
357 CDS Clerk Server Calls
360 Cast Client Control Protocol
361 Certificate Management Protocol
362 Certificate Request Message Format
363 Check Point High Availability Protocol
366 Cisco Discovery Protocol
367 Cisco Group Management Protocol
369 Cisco Hot Standby Router Protocol
371 Cisco Interior Gateway Routing Protocol
374 Cisco Session Management
376 CoSine IPNOS L2 debug output
377 Common Industrial Protocol
378 Common Open Policy Service
379 Common Unix Printing System (CUPS) Browsing Protocol
381 Configuration Test Protocol (loopback)
382 Connectionless Lightweight Directory Access Protocol
383 Coseventcomm Dissector Using GIOP API
384 Cosnaming Dissector Using GIOP API
385 Cross Point Frame Injector
386 Cryptographic Message Syntax
387 DCE Distributed Time Service Local Server
388 DCE Distributed Time Service Provider
391 DCE Security ID Mapper
395 DCE/RPC CDS Solicitation
396 DCE/RPC Conversation Manager
397 DCE/RPC Directory Acl Interface
398 DCE/RPC Endpoint Mapper
399 DCE/RPC Endpoint Mapper v4
401 DCE/RPC FLDB UBIK TRANSFER
402 DCE/RPC FLDB UBIKVOTE
405 DCE/RPC NCS 1.5.1 Local Location Broker
406 DCE/RPC Operations between registry server replicas
413 DCE/RPC Registry Password Management
414 DCE/RPC Registry Server Attributes Schema
415 DCE/RPC Registry server propagation interface - ACLs.
416 DCE/RPC Registry server propagation interface - PGO items
417 DCE/RPC Registry server propagation interface - properties and poli
419 DCE/RPC Remote Management
420 DCE/RPC Repserver Calls
421 DCE/RPC TokenServer Calls
425 DCOM IRemoteActivation
427 DEC DNA Routing Protocol
428 DEC Spanning Tree Protocol
438 DNS Control Program Server
440 DOCSIS Appendix C TLV's
441 DOCSIS Baseline Privacy Key Management Attributes
442 DOCSIS Baseline Privacy Key Management Request
443 DOCSIS Baseline Privacy Key Management Response
444 DOCSIS Dynamic Service Addition Acknowledge
445 DOCSIS Dynamic Service Addition Request
446 DOCSIS Dynamic Service Addition Response
447 DOCSIS Dynamic Service Change Acknowledgement
448 DOCSIS Dynamic Service Change Request
449 DOCSIS Dynamic Service Change Response
450 DOCSIS Dynamic Service Delete Request
451 DOCSIS Dynamic Service Delete Response
452 DOCSIS Initial Ranging Message
453 DOCSIS Mac Management
454 DOCSIS Range Request Message
455 DOCSIS Ranging Response
456 DOCSIS Registration Acknowledge
457 DOCSIS Registration Requests
458 DOCSIS Registration Responses
459 DOCSIS Upstream Bandwidth Allocation
460 DOCSIS Upstream Channel Change Request
461 DOCSIS Upstream Channel Change Response
462 DOCSIS Upstream Channel Descriptor
463 DOCSIS Upstream Channel Descriptor Type 29
464 DOCSIS Vendor Specific Endodings
465 DPNSS/DASS2-User Adaptation Layer
469 Data Stream Interface
470 Datagram Delivery Protocol
471 Decompressed SigComp message as raw text
473 Digital Audio Access Protocol
474 Distance Vector Multicast Routing Protocol
475 Distcc Distributed Compiler
476 Distributed Checksum Clearinghouse Protocol
477 Distributed Interactive Simulation
478 Distributed Network Protocol 3.0
480 Dynamic DNS Tools Protocol
481 Dynamic Trunking Protocol
484 Encapsulating Security Payload
485 Endpoint Name Resolution Protocol
486 Enhanced Interior Gateway Routing Protocol
487 EtherNet/IP (Industrial Protocol)
491 Extended Security Services
492 Extensible Authentication Protocol
494 FC Fabric Configuration Server
499 Fiber Distributed Data Interface
501 Fibre Channel Common Transport
502 Fibre Channel Fabric Zone Server
503 Fibre Channel Name Server
504 Fibre Channel Protocol for SCSI
506 Fibre Channel Security Protocol
507 Fibre Channel Single Byte Command
508 File Transfer Protocol (FTP)
509 Financial Information eXchange Protocol
513 GARP Multicast Registration Protocol
514 GARP VLAN Registration Protocol
516 GPRS Tunneling Protocol
520 GSM Mobile Application
521 GSM SMS TPDU (GSM 03.40)
522 GSM Short Message Service User Data
523 GSS-API Generic Security Service Application Program Interface
524 General Inter-ORB Protocol
525 Generic Routing Encapsulation
529 H235-SECURITY-MESSAGES
530 HP Extended Local-Link Control
531 HP Remote Maintenance Protocol
533 HP-UX Network Tracing and Logging
534 Hummingbird NFS Daemon
536 Hypertext Transfer Protocol
556 ICBAPhysicalDevicePCEvent
564 IEEE 802.11 Radiotap Capture header
565 IEEE 802.11 wireless LAN
566 IEEE 802.11 wireless LAN management frame
567 IEEE802a OUI Extended Ethertype
570 IP Device Control (SS7 over IP)
572 IP Payload Compression
573 IP Virtual Services Sync Daemon
575 IPX Routing Information Protocol
580 ISDN Q.921-User Adaptation Layer
582 ISO 10589 ISIS InTRA Domain Routeing Information Exchange Protocol
583 ISO 8073 COTP Connection-Oriented Transport Protocol
584 ISO 8327-1 OSI Session Protocol
585 ISO 8473 CLNP ConnectionLess Network Protocol
586 ISO 8602 CLTP ConnectionLess Transport Protocol
587 ISO 8823 OSI Presentation Protocol
588 ISO 9542 ESIS Routeing Information Exchange Protocol
590 ISystemActivator ISystemActivator Resolver
592 ITU-T Recommendation H.261
593 ITU-T Recommendation H.263 RTP Payload header (RFC2190)
595 Information Access Protocol
597 Intelligent Platform Management Interface
598 Inter-Access-Point Protocol
599 Inter-Asterisk eXchange v2
600 InterSwitch Message Protocol
602 Internet Cache Protocol
603 Internet Communications Engine Protocol
604 Internet Content Adaptation Protocol
605 Internet Control Message Protocol
606 Internet Control Message Protocol v6
607 Internet Group Management Protocol
608 Internet Group membership Authentication Protocol
609 Internet Message Access Protocol
610 Internet Printing Protocol
612 Internet Protocol Version 6
614 Internet Security Association and Key Management Protocol
615 Internetwork Datagram Protocol
616 Internetwork Packet eXchange
618 IrDA Link Access Protocol
619 IrDA Link Management Protocol
620 JPEG File Interchange Format
621 JXTA Connection Welcome Message
631 Kerberized Internet Negotiation of Key
633 Kerberos Administration
637 LWAPP Encapsulated Packet
639 Label Distribution Protocol
641 Layer 2 Tunneling Protocol
642 Light Weight DNS RESolver (BIND9)
643 Lightweight Directory Access Protocol
644 Line Printer Daemon Protocol
646 Link Access Procedure Balanced (LAPB)
647 Link Access Procedure Balanced Ethernet (LAPBETHER)
648 Link Access Procedure, Channel D (LAPD)
649 Link Management Protocol (LMP)
650 Linux cooked-mode capture
651 Local Management Interface
652 LocalTalk Link Access Protocol
654 Logical Link Control GPRS
656 Logotype Certificate Extensions
657 Lucent/Ascend debug output
662 MIME Multipart Media Encapsulation
664 MMS Message Encapsulation
667 MSN Messenger Service
668 MSNIP: Multicast Source Notification of Interest Protocol
669 MTP 2 Transparent Proxy
670 MTP 2 User Adaptation Layer
671 MTP 3 User Adaptation Layer
672 MTP2 Peer Adaptation Layer
673 Media Gateway Control Protocol
675 Media Type: message/http
676 Message Session Relay Protocol
677 Message Transfer Part Level 2
678 Message Transfer Part Level 3
679 Message Transfer Part Level 3 Management
680 Meta Analysis Tracing Engine
681 Microsoft Distributed File System
682 Microsoft Distributed Link Tracking Server Service
683 Microsoft Encrypted File System Service
684 Microsoft Eventlog Service
685 Microsoft Exchange MAPI
686 Microsoft File Replication Service
687 Microsoft File Replication Service API
688 Microsoft Local Security Architecture
689 Microsoft Media Server
690 Microsoft Messenger Service
691 Microsoft Network Logon
692 Microsoft Plug and Play service
694 Microsoft Routing and Remote Access Service
695 Microsoft Security Account Manager
696 Microsoft Server Service
697 Microsoft Service Control
698 Microsoft Spool Subsystem
699 Microsoft Task Scheduler Service
700 Microsoft Telephony API Service
701 Microsoft Windows Browser Protocol
702 Microsoft Windows Lanman Remote API Protocol
703 Microsoft Windows Logon Protocol (Old)
704 Microsoft Workstation Service
710 MultiProtocol Label Switching Header
711 Multicast Router DISCovery protocol
712 Multicast Source Discovery Protocol
713 Multiprotocol Label Switching Echo
720 NTLM Secure Service Provider
721 Name Binding Protocol
722 Name Management Protocol over IPX
723 Negative-acknowledgment Oriented Reliable Multicast
725 NetBIOS Datagram Service
727 NetBIOS Session Service
729 NetScape Certificate Extensions
730 NetWare Core Protocol
731 NetWare Link Services Protocol
732 NetWare Serialization Protocol
733 Network Data Management Protocol
735 Network Lock Manager Protocol
736 Network News Transfer Protocol
737 Network Service Over IP
738 Network Status Monitor CallBack Protocol
739 Network Status Monitor Protocol
740 Network Time Protocol
742 Novell Distributed Print System
743 Novell Modular Authentication Service
745 Online Certificate Status Protocol
746 Open Policy Service Interface
747 Open Shortest Path First
748 OpenBSD Encapsulating device
749 OpenBSD Packet Filter log file
750 OpenBSD Packet Filter log file, pre 3.4
751 Optimized Link State Routing Protocol
755 PKIX CERT File Format
757 PKIX Time Stamp Protocol
761 PPP Bandwidth Allocation Control Protocol
762 PPP Bandwidth Allocation Protocol
763 PPP CDP Control Protocol
764 PPP Callback Control Protocol
765 PPP Challenge Handshake Authentication Protocol
766 PPP Compressed Datagram
767 PPP Compression Control Protocol
768 PPP IP Control Protocol
769 PPP IPv6 Control Protocol
770 PPP In HDLC-Like Framing
771 PPP Link Control Protocol
772 PPP MPLS Control Protocol
773 PPP Multilink Protocol
775 PPP OSI Control Protocol
776 PPP Password Authentication Protocol
778 PPP-over-Ethernet Discovery
779 PPP-over-Ethernet Session
780 PPPMux Control Protocol
783 PROFINET Real-Time Protocol
784 Packed Encoding Rules (ASN.1 X.691)
785 Packet Cable Lawful Intercept
787 Parlay Dissector Using GIOP API
789 Point-to-Point Protocol
790 Point-to-Point Tunnelling Protocol
791 Port Aggregation Protocol
795 Pragmatic General Multicast
796 Precision Time Protocol (IEEE1588)
798 Privilege Server operations
799 Protocol Independent Multicast
803 Quake II Network Protocol
804 Quake III Arena Network Protocol
805 Quake Network Protocol
806 QuakeWorld Network Protocol
807 Qualified Logical Link Control
813 RS Interface properties
815 RSYNC File Synchroniser
818 Radio Access Network Application Part
822 Real Time Streaming Protocol
823 Real-Time Media Access Control
824 Real-Time Publish-Subscribe Wire Protocol
825 Real-Time Transport Protocol
826 Real-time Transport Control Protocol
828 Redundant Link Management Protocol
829 Registry Server Attributes Manipulation Interface
830 Registry server administration operations.
832 Remote Management Control Protocol
833 Remote Override interface
834 Remote Procedure Call
840 Remote sec_login preauth interface.
841 Resource ReserVation Protocol (RSVP)
842 Retix Spanning Tree Protocol
844 Routing Information Protocol
845 Routing Table Maintenance Protocol
848 SEBEK - Kernel Data Capture
850 SMB (Server Message Block Protocol)
851 SMB MailSlot Protocol
854 SNMP Multiplex Protocol
857 SS7 SCCP-User Adaptation Layer
862 Sequenced Packet Protocol
863 Sequenced Packet eXchange
865 Service Advertisement Protocol
866 Service Location Protocol
867 Session Announcement Protocol
868 Session Description Protocol
869 Session Initiation Protocol
870 Session Initiation Protocol (SIP as raw text)
871 Short Message Peer to Peer
872 Short Message Relaying Service
873 Signaling Compression
874 Signalling Connection Control Part
875 Signalling Connection Control Part Management
876 Simple Mail Transfer Protocol
877 Simple Network Management Protocol
878 Simple Traversal of UDP Through NAT
881 Skinny Client Control Protocol
882 SliMP3 Communication Protocol
886 Spanning Tree Protocol
888 Stream Control Transmission Protocol
889 Subnetwork Dependent Convergence Protocol
890 Symantec Enterprise Firewall
891 Synchronous Data Link Control (SDLC)
894 Systems Network Architecture
895 Systems Network Architecture XID
899 TDMA RTmac Discipline
900 TEI Management Procedure, Channel D (LAPD)
901 TPKT - ISO on TCP - RFC1006
903 Tango Dissector Using GIOP API
904 Tazmen Sniffer Protocol
906 Teredo IPv6 over UDP tunneling
907 The Armagetron Advanced OpenGL Tron clone
909 Time Synchronization Protocol
910 Tiny Transport Protocol
912 Token-Ring Media Access Control
913 Transaction Capabilities Application Part
914 Transmission Control Protocol
915 Transparent Network Substrate Protocol
916 Transport Adapter Layer Interface v1.0, RFC 3094
917 Trivial File Transfer Protocol
918 UDP Encapsulation of IPsec Packets
919 Universal Computer Protocol
920 Unlicensed Mobile Access
921 User Datagram Protocol
922 V5.2-User Adaptation Layer
923 Virtual Network Computing
924 Virtual Router Redundancy Protocol
925 Virtual Trunking Protocol
927 WAP Session Initiation Request
928 Web Cache Coordination Protocol
930 WebSphere MQ Programmable Command Formats
931 Wellfleet Breath of Life
932 Wellfleet Compression
936 Wireless Session Protocol
937 Wireless Transaction Protocol
938 Wireless Transport Layer Security
939 Wlan Certificate Extension
940 X Display Manager Control Protocol
944 X.509 Authentication Framework
945 X.509 Certificate Extensions
946 X.509 Information Framework
947 X.509 Selected Attribute Types
951 Yahoo Messenger Protocol
952 Yahoo YMSG Messenger Protocol
956 Yellow Pages Transfer
958 Zone Information Protocol
960 eXtensible Markup Language
961 giFT Internet File Transfer
969 Q 1.6: Are there any plans to support {your favorite protocol}?
971 A: Support for particular protocols is added to Ethereal as a result of
972 people contributing that support; no formal plans for adding support for
973 particular protocols in particular future releases exist.
975 Q 1.7: Can Ethereal read capture files from {your favorite network
978 A: Support for particular protocols is added to Ethereal as a result of
979 people contributing that support; no formal plans for adding support for
980 particular protocols in particular future releases exist.
982 If a network analyzer writes out files in a format already supported by
983 Ethereal (e.g., in libpcap format), Ethereal may already be able to read
984 them, unless the analyzer has added its own proprietary extensions to that
987 If a network analyzer writes out files in its own format, or has added
988 proprietary extensions to another format, in order to make Ethereal read
989 captures from that network analyzer, we would either have to have a
990 specification for the file format, or the extensions, sufficient to give us
991 enough information to read the parts of the file relevant to Ethereal, or
992 would need at least one capture file in that format AND a detailed textual
993 analysis of the packets in that capture file (showing packet time stamps,
994 packet lengths, and the top-level packet header) in order to
995 reverse-engineer the file format.
997 Note that there is no guarantee that we will be able to reverse-engineer a
1000 Q 1.8: What devices can Ethereal use to capture packets?
1002 A: Ethereal can read live data from Ethernet, Token-Ring, FDDI, serial (PPP
1003 and SLIP) (if the OS on which it's running allows Ethereal to do so), 802.11
1004 wireless LAN (if the OS on which it's running allows Ethereal to do so), ATM
1005 connections (if the OS on which it's running allows Ethereal to do so), and
1006 the "any" device supported on Linux by recent versions of libpcap. See the
1007 list of supported capture media on various OSes for details (several items
1008 in there say "Unknown", which doesn't mean "Ethereal can't capture on them",
1009 it means "we don't know whether it can capture on them"; we expect that it
1010 will be able to capture on many of them, but we haven't tried it ourselves -
1011 if you try one of those types and it works, please send an update to
1012 ethereal-web[AT]ethereal.com ).
1014 It can also read a variety of capture file formats, including:
1015 * AG Group/WildPackets EtherPeek/TokenPeek/AiroPeek/EtherHelp/Packet
1017 * AIX's iptrace captures
1018 * Accellent's 5Views LAN agent output
1019 * Cinco Networks NetXRay captures
1020 * Cisco Secure Intrusion Detection System IPLog output
1021 * CoSine L2 debug output
1022 * DBS Etherwatch VMS text output
1023 * Endace Measurement Systems' ERF format captures
1024 * EyeSDN USB S0 traces
1025 * HP-UX nettl captures
1026 * ISDN4BSD project i4btrace captures
1027 * Linux Bluez Bluetooth stack hcidump -w traces
1028 * Lucent/Ascend router debug output
1029 * Microsoft Network Monitor captures
1030 * Network Associates Windows-based Sniffer captures
1031 * Network General/Network Associates DOS-based Sniffer (compressed or
1032 uncompressed) captures
1033 * Network Instruments Observer version 9 captures
1034 * Novell LANalyzer captures
1035 * RADCOM's WAN/LAN analyzer captures
1036 * Shomiti/Finisar Surveyor captures
1037 * Toshiba's ISDN routers dump output
1038 * VMS TCPIPtrace/TCPtrace/UCX$TRACE output
1039 * Visual Networks' Visual UpTime traffic capture
1040 * libpcap, tcpdump and various other tools using tcpdump's capture format
1041 * snoop and atmsnoop output
1043 so that it can read traces from various network types, as captured by other
1044 applications or equipment, even if it cannot itself capture on those network
1047 Q 1.9: How do you pronounce Ethereal? Where did the name come from?
1049 A: The English pronunciation can be found in Merriam-Webster's online
1051 http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=ethereal.
1053 According to the book "Computer Networks" by Andrew Tannenbaum, Ethernet was
1054 named after the "luminiferous ether" which was once thought to carry
1055 electromagnetic radiation. Taking that into consideration, Ethereal seemed
1056 like an appropriate name for something that started out as an Ethernet
1059 2. Downloading Ethereal
1061 Q 2.1: I downloaded the Win32 installer, but when I try to run it, I get an
1064 A: The program you used to download it may have downloaded it incorrectly.
1065 Web browsers sometimes may do this.
1067 Try downloading it with, for example:
1068 * Wget, for which Windows binaries are available on the SunSITE FTP server
1069 at sunsite.tk or Heiko Herold's windows wget spot - wGetGUI offers a GUI
1070 interface that uses wget;
1071 * WS_FTP from Ipswitch,
1072 * the ftp command that comes with Windows.
1074 If you use the ftp command, make sure you do the transfer in binary mode
1075 rather than ASCII mode, by using the binary command before transferring the
1078 Q 2.2: When I try to download the WinPcap driver and library, I can't get to
1079 the WinPcap Web site.
1081 A: As is the case with all Web sites, that site won't necessarily always be
1082 accessible; the server may be down due to a problem or down for maintenance,
1083 or there may be a networking problem between you and the server. You should
1084 try again later, or try the local mirror or the Wiretapped.net mirror.
1086 3. Installing Ethereal
1088 Q 3.1: I installed an Ethereal RPM, but Ethereal doesn't seem to be
1089 installed; only Tethereal is installed.
1091 A: Older versions of the Red Hat RPMs for Ethereal put only the non-GUI
1092 components into the ethereal RPM, the fact that Ethereal is a GUI program
1093 nonwithstanding; newer versions make it a bit clearer by giving that RPM a
1094 name starting with ethereal-base.
1096 In those older versions, there's a separate ethereal-gnome RPM that includes
1097 GUI components such as Ethereal itself, the fact that Ethereal doesn't use
1098 GNOME nonwithstanding; newer versions make it a bit clearer by giving that
1099 RPM a name starting with ethereal-gtk+.
1101 Find the ethereal-gnome or ethereal-gtk+ RPM, and install that also.
1103 4. Building Ethereal
1105 Q 4.1: The configure script can't find pcap.h or bpf.h, but I have libpcap
1108 A: Are you sure pcap.h and bpf.h are installed? The official distribution of
1109 libpcap only installs the libpcap.a library file when "make install" is run.
1110 To install pcap.h and bpf.h, you must run "make install-incl". If you're
1111 running Debian or Redhat, make sure you have the "libpcap-dev" or
1112 "libpcap-devel" packages installed.
1114 It's also possible that pcap.h and bpf.h have been installed in a strange
1115 location. If this is the case, you may have to tweak aclocal.m4.
1117 Q 4.2: Why do I get the error
1119 dftest_DEPENDENCIES was already defined in condition TRUE, which implies
1120 condition HAVE_PLUGINS_TRUE
1122 when I try to build Ethereal from SVN or a SVN snapshot?
1124 A: You probably have automake 1.5 installed on your machine (the command
1125 automake --version will report the version of automake on your machine).
1126 There is a bug in that version of automake that causes this problem; upgrade
1127 to a later version of automake (1.6 or later).
1129 Q 4.3: The link fails with a number of "Output line too long." messages
1130 followed by linker errors.
1132 A: The version of the sed command on your system is incapable of handling
1133 very long lines. On Solaris, for example, /usr/bin/sed has a line length
1134 limit too low to allow libtool to work; /usr/xpg4/bin/sed can handle it, as
1135 can GNU sed if you have it installed.
1137 On Solaris, changing your command search path to search /usr/xpg4/bin before
1138 /usr/bin should make the problem go away; on any platform on which you have
1139 this problem, installing GNU sed and changing your command path to search
1140 the directory in which it is installed before searching the directory with
1141 the version of sed that came with the OS should make the problem go away.
1143 Q 4.4: The link fails on Solaris because plugin_list is undefined.
1145 A: This appears to be due to a problem with some versions of the GTK+ and
1146 GLib packages from www.sunfreeware.org; un-install those packages, and try
1147 getting the 1.2.10 versions from that site, or the versions from The Written
1148 Word, or the versions from Sun's GNOME distribution, or the versions from
1149 the supplemental software CD that comes with the Solaris media kit, or build
1150 them from source from the GTK Web site. Then re-run the configuration
1151 script, and try rebuilding Ethereal. (If you get the 1.2.10 versions from
1152 www.sunfreeware.org, and the problem persists, un-install them and try
1153 installing one of the other versions mentioned.)
1155 Q 4.5: The build fails on Windows because of conflicts between winsock.h and
1158 A: As of Ethereal 0.9.5, you must install WinPcap 2.3 or later, and the
1159 corresponding version of the developer's pack, in order to be able to
1160 compile Ethereal; it will not compile with older versions of the developer's
1161 pack. The symptoms of this failure are conflicts between definitions in
1162 winsock.h and in winsock2.h; Ethereal uses winsock2.h, but pre-2.3 versions
1163 of the WinPcap developer's packet use winsock.h. (2.3 uses winsock2.h, so if
1164 Ethereal were to use winsock.h, it would not be able to build with current
1165 versions of the WinPcap developer's pack.)
1167 Note that the installed version of the developer's pack should be the same
1168 version as the version of WinPcap you have installed.
1172 Q 5.1: When I use Ethereal to capture packets, I see only packets to and
1173 from my machine, or I'm not seeing all the traffic I'm expecting to see from
1174 or to the machine I'm trying to monitor.
1176 A: This might be because the interface on which you're capturing is plugged
1177 into an Ethernet or Token Ring switch; on a switched network, unicast
1178 traffic between two ports will not necessarily appear on other ports - only
1179 broadcast and multicast traffic will be sent to all ports.
1181 Note that even if your machine is plugged into a hub, the "hub" may be a
1182 switched hub, in which case you're still on a switched network.
1184 Note also that on the Linksys Web site, they say that their auto-sensing
1185 hubs "broadcast the 10Mb packets to the port that operate at 10Mb only and
1186 broadcast the 100Mb packets to the ports that operate at 100Mb only", which
1187 would indicate that if you sniff on a 10Mb port, you will not see traffic
1188 coming sent to a 100Mb port, and vice versa. This problem has also been
1189 reported for Netgear dual-speed hubs, and may exist for other "auto-sensing"
1190 or "dual-speed" hubs.
1192 Some switches have the ability to replicate all traffic on all ports to a
1193 single port so that you can plug your analyzer into that single port to
1194 sniff all traffic. You would have to check the documentation for the switch
1195 to see if this is possible and, if so, to see how to do this. See the switch
1196 reference page on the Ethereal Wiki for information on some switches. (Note
1197 that it's a Wiki, so you can update or fix that information, or add
1198 additional information on those switches or information on new switches,
1201 Note also that many firewall/NAT boxes have a switch built into them; this
1202 includes many of the "cable/DSL router" boxes. If you have a box of that
1203 sort, that has a switch with some number of Ethernet ports into which you
1204 plug machines on your network, and another Ethernet port used to connect to
1205 a cable or DSL modem, you can, at least, sniff traffic between the machines
1206 on your network and the Internet by plugging the Ethernet port on the router
1207 going to the modem, the Ethernet port on the modem, and the machine on which
1208 you're running Ethereal into a hub (make sure it's not a switching hub, and
1209 that, if it's a dual-speed hub, all three of those ports are running at the
1212 If your machine is not plugged into a switched network or a dual-speed hub,
1213 or it is plugged into a switched network but the port is set up to have all
1214 traffic replicated to it, the problem might be that the network interface on
1215 which you're capturing doesn't support "promiscuous" mode, or because your
1216 OS can't put the interface into promiscuous mode. Normally, network
1217 interfaces supply to the host only:
1218 * packets sent to one of that host's link-layer addresses;
1219 * broadcast packets;
1220 * multicast packets sent to a multicast address that the host has
1221 configured the interface to accept.
1223 Most network interfaces can also be put in "promiscuous" mode, in which they
1224 supply to the host all network packets they see. Ethereal will try to put
1225 the interface on which it's capturing into promiscuous mode unless the
1226 "Capture packets in promiscuous mode" option is turned off in the "Capture
1227 Options" dialog box, and Tethereal will try to put the interface on which
1228 it's capturing into promiscuous mode unless the -p option was specified.
1229 However, some network interfaces don't support promiscuous mode, and some
1230 OSes might not allow interfaces to be put into promiscuous mode.
1232 If the interface is not running in promiscuous mode, it won't see any
1233 traffic that isn't intended to be seen by your machine. It will see
1234 broadcast packets, and multicast packets sent to a multicast MAC address the
1235 interface is set up to receive.
1237 You should ask the vendor of your network interface whether it supports
1238 promiscuous mode. If it does, you should ask whoever supplied the driver for
1239 the interface (the vendor, or the supplier of the OS you're running on your
1240 machine) whether it supports promiscuous mode with that network interface.
1242 In the case of token ring interfaces, the drivers for some of them, on
1243 Windows, may require you to enable promiscuous mode in order to capture in
1244 promiscuous mode. See the Ethereal Wiki item on Token Ring capturing for
1247 In the case of wireless LAN interfaces, it appears that, when those
1248 interfaces are promiscuously sniffing, they're running in a significantly
1249 different mode from the mode that they run in when they're just acting as
1250 network interfaces (to the extent that it would be a significant effor for
1251 those drivers to support for promiscuously sniffing and acting as regular
1252 network interfaces at the same time), so it may be that Windows drivers for
1253 those interfaces don't support promiscuous mode.
1255 Q 5.2: I can't see any TCP packets other than packets to and from my
1256 machine, even though another analyzer on the network sees those packets.
1258 A: You're probably not seeing any packets other than unicast packets to or
1259 from your machine, and broadcast and multicast packets; a switch will
1260 normally send to a port only unicast traffic sent to the MAC address for the
1261 interface on that port, and broadcast and multicast traffic - it won't send
1262 to that port unicast traffic sent to a MAC address for some other interface
1263 - and a network interface not in promiscuous mode will receive only unicast
1264 traffic sent to the MAC address for that interface, broadcast traffic, and
1265 multicast traffic sent to a multicast MAC address the interface is set up to
1268 TCP doesn't use broadcast or multicast, so you will only see your own TCP
1269 traffic, but UDP services may use broadcast or multicast so you'll see some
1270 UDP traffic - however, this is not a problem with TCP traffic, it's a
1271 problem with unicast traffic, as you also won't see all UDP traffic between
1274 I.e., this is probably the same question as this earlier one; see the
1275 response to that question.
1277 Q 5.3: I'm only seeing ARP packets when I try to capture traffic.
1279 A: You're probably on a switched network, and running Ethereal on a machine
1280 that's not sending traffic to the switch and not being sent any traffic from
1281 other machines on the switch. ARP packets are often broadcast packets, which
1282 are sent to all switch ports.
1284 I.e., this is probably the same question as this earlier one; see the
1285 response to that question.
1287 Q 5.4: I'm running Ethereal on Windows; why does some network interface on
1288 my machine not show up in the list of interfaces in the "Interface:" field
1289 in the dialog box popped up by "Capture->Start", and/or why does Ethereal
1290 give me an error if I try to capture on that interface?
1292 A: If you are running Ethereal on Windows NT 4.0, Windows 2000, Windows XP,
1293 or Windows Server 2003, and this is the first time you have run a
1294 WinPcap-based program (such as Ethereal, or Tethereal, or WinDump, or
1295 Analyzer, or...) since the machine was rebooted, you need to run that
1296 program from an account with administrator privileges; once you have run
1297 such a program, you will not need administrator privileges to run any such
1298 programs until you reboot.
1300 If you are running on Windows 95/98/Me, or if you are running on Windows NT
1301 4.0/Windows 2000/Windows XP/Windows Server 2003 and have administrator
1302 privileges or a WinPcap-based program has been run with those privileges
1303 since the machine rebooted, this problem might clear up if you completely
1304 un-install WinPcap and then re-install it.
1306 If that doesn't work, then note that Ethereal relies on the WinPcap library,
1307 on the WinPcap device driver, and on the facilities that come with the OS on
1308 which it's running in order to do captures.
1310 Therefore, if the OS, the WinPcap library, or the WinPcap driver don't
1311 support capturing on a particular network interface device, Ethereal won't
1312 be able to capture on that device.
1315 1. 2.02 and earlier versions of the WinPcap driver and library that
1316 Ethereal uses for packet capture didn't support Token Ring interfaces;
1317 versions 2.1 and later support Token Ring, and the current version of
1318 Ethereal works with (and, in fact, requires) WinPcap 2.1 or later.
1319 If you are having problems capturing on Token Ring interfaces, and you
1320 have WinPcap 2.02 or an earlier version of WinPcap installed, you should
1321 uninstall WinPcap, download and install the current version of WinPcap,
1322 and then install the latest version of Ethereal.
1323 2. On Windows 95, 98, or Me, sometimes more than one interface will be
1324 given the same name; if that is the case, you will only be able to
1325 capture on one of those interfaces - it's not clear to which one the
1326 name, when used in a WinPcap-based application, will refer. For example,
1327 if you have a PPP serial interface and a VPN interface, they might show
1328 up with the same name, for example "ppp-mac", and if you try to capture
1329 on "ppp-mac", it might not capture on the interface you're currently
1330 using. In that case, you might, for example, have to remove the VPN
1331 interface from the system in order to capture on the PPP serial
1333 3. WinPcap 2.3 has problems supporting PPP WAN interfaces on Windows NT
1334 4.0, Windows 2000, Windows XP, and Windows Server 2003, and, to avoid
1335 those problems, support for PPP WAN interfaces on those versions of
1336 Windows has been disabled in WinPcap 3.0. Regular dial-up lines, ISDN
1337 lines, ADSL connections using PPPoE or PPPoA, and various other lines
1338 such as T1/E1 lines are all PPP interfaces, so those interfaces might
1339 not show up on the list of interfaces in the "Capture Options" dialog on
1341 On Windows 2000, Windows XP, and Windows Server 2003, but not Windows NT
1342 4.0 or Windows Vista Beta 1, you should be able to capture on the
1343 "GenericDialupAdapter" with WinPcap 3.1. (3.1 beta releases called it
1344 the "NdisWanAdapter"; if you're using a 3.1 beta release, you should
1345 un-install it and install the final 3.1 release.) See the Ethereal Wiki
1346 item on PPP capturing for details.
1347 4. WinPcap prior to 3.0 does not support multiprocessor machines (note that
1348 machines with a single multi-threaded processor, such as Intel's new
1349 multi-threaded x86 processors, are multiprocessor machines as far as the
1350 OS and WinPcap are concerned), and recent 2.x versions of WinPcap refuse
1351 to operate if they detect that they're running on a multiprocessor
1352 machine, which means that they may not show any network interfaces. You
1353 will need to use WinPcap 3.0 to capture on a multiprocessor machine.
1355 If an interface doesn't show up in the list of interfaces in the
1356 "Interface:" field, and you know the name of the interface, try entering
1357 that name in the "Interface:" field and capturing on that device.
1359 If the attempt to capture on it succeeds, the interface is somehow not being
1360 reported by the mechanism Ethereal uses to get a list of interfaces. Try
1361 listing the interfaces with WinDump; see the WinDump Web site or the local
1362 mirror of the WinDump Web site for information on using WinDump.
1364 You would run WinDump with the -D flag; if it lists the interface, please
1365 report this to ethereal-dev@ethereal.com giving full details of the problem,
1367 * the operating system you're using, and the version of that operating
1369 * the type of network device you're using;
1370 * the output of WinDump.
1372 If WinDump does not list the interface, this is almost certainly a problem
1373 with one or more of:
1374 * the operating system you're using;
1375 * the device driver for the interface you're using;
1376 * the WinPcap library and/or the WinPcap device driver;
1378 so first check the WinPcap FAQ, the local mirror of that FAQ, or the
1379 Wiretapped.net mirror of that FAQ, to see if your problem is mentioned
1380 there. If not, then see the WinPcap support page (or the local mirror of
1381 that page) - check the "Submitting bugs" section.
1383 If you are having trouble capturing on a particular network interface, first
1384 try capturing on that device with WinDump; see the WinDump Web site or the
1385 local mirror of the WinDump Web site for information on using WinDump.
1387 If you can capture on the interface with WinDump, send mail to
1388 ethereal-users@ethereal.com giving full details of the problem, including
1389 * the operating system you're using, and the version of that operating
1391 * the type of network device you're using;
1392 * the error message you get from Ethereal.
1394 If you cannot capture on the interface with WinDump, this is almost
1395 certainly a problem with one or more of:
1396 * the operating system you're using;
1397 * the device driver for the interface you're using;
1398 * the WinPcap library and/or the WinPcap device driver;
1400 so first check the WinPcap FAQ, the local mirror of that FAQ, or the
1401 Wiretapped.net mirror of that FAQ, to see if your problem is mentioned
1402 there. If not, then see the WinPcap support page (or the local mirror of
1403 that page) - check the "Submitting bugs" section.
1405 You may also want to ask the ethereal-users@ethereal.com and the
1406 winpcap-users@winpcap.org mailing lists to see if anybody happens to know
1407 about the problem and know a workaround or fix for the problem. (Note that
1408 you will have to subscribe to that list in order to be allowed to mail to
1409 it; see the WinPcap support page, or the local mirror of that page, for
1410 information on the mailing list.) In your mail, please give full details of
1411 the problem, as described above, and also indicate that the problem occurs
1412 with WinDump, not just with Ethereal.
1414 Q 5.5: I'm running Ethereal on Windows; why do no network interfaces show up
1415 in the list of interfaces in the "Interface:" field in the dialog box popped
1416 up by "Capture->Start"?
1418 A: This is really the same question as the previous one; see the response to
1421 Q 5.6: I'm running Ethereal on Windows; why doesn't my serial port/ADSL
1422 modem/ISDN modem show up in the list of interfaces in the "Interface:" field
1423 in the dialog box popped up by "Capture->Start"?
1425 A: Internet access on those devices is often done with the Point-to-Point
1426 (PPP) protocol; WinPcap 2.3 has problems supporting PPP WAN interfaces on
1427 Windows NT 4.0, Windows 2000, Windows XP, and Windows Server 2003, and, to
1428 avoid those problems, support for PPP WAN interfaces on those versions of
1429 Windows has been disabled in WinPcap 3.0.
1431 On Windows 2000, Windows XP, and Windows Server 2003, but not Windows NT 4.0
1432 or Windows Vista Beta 1, you should be able to capture on the
1433 "GenericDialupAdapter" with WinPcap 3.1. (3.1 beta releases called it the
1434 "NdisWanAdapter"; if you're using a 3.1 beta release, you should un-install
1435 it and install the final 3.1 release.) See the Ethereal Wiki item on PPP
1436 capturing for details.
1438 Q 5.7: I'm running Ethereal on a UNIX-flavored OS; why does some network
1439 interface on my machine not show up in the list of interfaces in the
1440 "Interface:" field in the dialog box popped up by "Capture->Start", and/or
1441 why does Ethereal give me an error if I try to capture on that interface?
1443 A: You may need to run Ethereal from an account with sufficient privileges
1444 to capture packets, such as the super-user account, or may need to give your
1445 account sufficient privileges to capture packets. Only those interfaces that
1446 Ethereal can open for capturing show up in that list; if you don't have
1447 sufficient privileges to capture on any interfaces, no interfaces will show
1448 up in the list. See the Ethereal Wiki item on capture privileges for details
1449 on how to give a particular account or account group capture privileges on
1450 platforms where that can be done.
1452 If you are running Ethereal from an account with sufficient privileges, then
1453 note that Ethereal relies on the libpcap library, and on the facilities that
1454 come with the OS on which it's running in order to do captures. On some
1455 OSes, those facilities aren't present by default; see the Ethereal Wiki item
1456 on adding capture support for details.
1458 And, even if you're running with an account that has sufficient privileges
1459 to capture, and capture support is present in your OS, if the OS or the
1460 libpcap library don't support capturing on a particular network interface
1461 device or particular types of devices, Ethereal won't be able to capture on
1464 On Solaris, note that libpcap 0.6.2 and earlier didn't support Token Ring
1465 interfaces; the current version, 0.7.2, does support Token Ring, and the
1466 current version of Ethereal works with libcap 0.7.2 and later.
1468 If an interface doesn't show up in the list of interfaces in the
1469 "Interface:" field, and you know the name of the interface, try entering
1470 that name in the "Interface:" field and capturing on that device.
1472 If the attempt to capture on it succeeds, the interface is somehow not being
1473 reported by the mechanism Ethereal uses to get a list of interfaces; please
1474 report this to ethereal-dev@ethereal.com giving full details of the problem,
1476 * the operating system you're using, and the version of that operating
1477 system (for Linux, give both the version number of the kernel and the
1478 name and version number of the distribution you're using);
1479 * the type of network device you're using.
1481 If you are having trouble capturing on a particular network interface, and
1482 you've made sure that (on platforms that require it) you've arranged that
1483 packet capture support is present, as per the above, first try capturing on
1484 that device with tcpdump.
1486 If you can capture on the interface with tcpdump, send mail to
1487 ethereal-users@ethereal.com giving full details of the problem, including
1488 * the operating system you're using, and the version of that operating
1489 system (for Linux, give both the version number of the kernel and the
1490 name and version number of the distribution you're using);
1491 * the type of network device you're using;
1492 * the error message you get from Ethereal.
1494 If you cannot capture on the interface with tcpdump, this is almost
1495 certainly a problem with one or more of:
1496 * the operating system you're using;
1497 * the device driver for the interface you're using;
1498 * the libpcap library;
1500 so you should report the problem to the company or organization that
1501 produces the OS (in the case of a Linux distribution, report the problem to
1502 whoever produces the distribution).
1504 You may also want to ask the ethereal-users@ethereal.com and the
1505 tcpdump-workers@tcpdump.org mailing lists to see if anybody happens to know
1506 about the problem and know a workaround or fix for the problem. In your
1507 mail, please give full details of the problem, as described above, and also
1508 indicate that the problem occurs with tcpdump not just with Ethereal.
1510 Q 5.8: I'm running Ethereal on a UNIX-flavored OS; why do no network
1511 interfaces show up in the list of interfaces in the "Interface:" field in
1512 the dialog box popped up by "Capture->Start"?
1514 A: This is really the same question as the previous one; see the response to
1517 Q 5.9: Can Ethereal capture on (my T1/E1 line, SS7 links, etc.)?
1519 A: Ethereal can only capture on devices supported by libpcap/WinPcap. On
1520 most OSes, only devices that can act as network interfaces of the type that
1521 support IP are supported as capture devices for libpcap/WinPcap, although
1522 the device doesn't necessarily have to be running as an IP interface in
1523 order to support traffic capture.
1525 On Linux and FreeBSD, libpcap 0.8 and later support the API for Endace
1526 Measurement Systems' DAG cards, so that a system with one of those cards,
1527 and its driver and libraries, installed can capture traffic with those cards
1528 with libpcap-based applications. You would either have to have a version of
1529 Ethereal built with that version of libpcap, or a dynamically-linked version
1530 of Ethereal and a shared libpcap library with DAG support, in order to do so
1531 with Ethereal. You should ask Endace whether that could be used to capture
1532 traffic on, for example, your T1/E1 link.
1533 There is currently no hardware to support capturing on SS7 links with
1534 libpcap. (Note that the fact that Ethereal includes dissectors for many SS7
1535 protocols doesn't imply that it can capture traffic from SS7 links; those
1536 protocols can be run over Internet protocols.)
1538 Q 5.10: How do I put an interface into promiscuous mode?
1540 A: By not disabling promiscuous mode when running Ethereal or Tethereal.
1542 Note, however, that:
1543 * the form of promiscuous mode that libpcap (the library that programs
1544 such as tcpdump, Ethereal, etc. use to do packet capture) turns on will
1545 not necessarily be shown if you run ifconfig on the interface on a UNIX
1547 * some network interfaces might not support promiscuous mode, and some
1548 drivers might not allow promiscuous mode to be turned on - see this
1549 earlier question for more information on that;
1550 * the fact that you're not seeing any traffic, or are only seeing
1551 broadcast traffic, or aren't seeing any non-broadcast traffic other than
1552 traffic to or from the machine running Ethereal, does not mean that
1553 promiscuous mode isn't on - see this earlier question for more
1554 information on that.
1556 I.e., this is probably the same question as this earlier one; see the
1557 response to that question.
1559 Q 5.11: I can set a display filter just fine, but capture filters don't
1562 A: Capture filters currently use a different syntax than display filters.
1563 Here's the corresponding section from the ethereal(1) man page:
1565 "Display filters in Ethereal are very powerful; more fields are filterable
1566 in Ethereal than in other protocol analyzers, and the syntax you can use to
1567 create your filters is richer. As Ethereal progresses, expect more and more
1568 protocol fields to be allowed in display filters.
1570 Packet capturing is performed with the pcap library. The capture filter
1571 syntax follows the rules of the pcap library. This syntax is different from
1572 the display filter syntax."
1574 The capture filter syntax used by libpcap can be found in the tcpdump(8) man
1577 Q 5.12: I'm entering valid capture filters, but I still get "parse error"
1580 A: There is a bug in some versions of libpcap/WinPcap that cause it to
1581 report parse errors even for valid expressions if a previous filter
1582 expression was invalid and got a parse error.
1584 Try exiting and restarting Ethereal; if you are using a version of
1585 libpcap/WinPcap with this bug, this will "erase" its memory of the previous
1586 parse error. If the capture filter that got the "parse error" now works, the
1587 earlier error with that filter was probably due to this bug.
1589 The bug was fixed in libpcap 0.6; 0.4[.x] and 0.5[.x] versions of libpcap
1590 have this bug, but 0.6[.x] and later versions don't.
1592 Versions of WinPcap prior to 2.3 are based on pre-0.6 versions of libpcap,
1593 and have this bug; WinPcap 2.3 is based on libpcap 0.6.2, and doesn't have
1596 If you are running Ethereal on a UNIX-flavored platform, run "ethereal -v",
1597 or select "About Ethereal..." from the "Help" menu in Ethereal, to see what
1598 version of libpcap it's using. If it's not 0.6 or later, you will need
1599 either to upgrade your OS to get a later version of libpcap, or will need to
1600 build and install a later version of libpcap from the tcpdump.org Web site
1601 and then recompile Ethereal from source with that later version of libpcap.
1603 If you are running Ethereal on Windows with a pre-2.3 version of WinPcap,
1604 you will need to un-install WinPcap and then download and install WinPcap
1607 Q 5.13: I saved a filter and tried to use its name to filter the display,
1608 but I got an "Unexpected end of filter string" error.
1610 A: You cannot use the name of a saved display filter as a filter. To filter
1611 the display, you can enter a display filter expression - not the name of a
1612 saved display filter - in the "Filter:" box at the bottom of the display,
1613 and type the key or press the "Apply" button (that does not require you to
1614 have a saved filter), or, if you want to use a saved filter, you can press
1615 the "Filter:" button, select the filter in the dialog box that pops up, and
1616 press the "OK" button.
1618 Q 5.14: Why am I seeing lots of packets with incorrect TCP checksums?
1620 A: If the packets that have incorrect TCP checksums are all being sent by
1621 the machine on which Ethereal is running, this is probably because the
1622 network interface on which you're capturing does TCP checksum offloading.
1623 That means that the TCP checksum is added to the packet by the network
1624 interface, not by the OS's TCP/IP stack; when capturing on an interface,
1625 packets being sent by the host on which you're capturing are directly handed
1626 to the capture interface by the OS, which means that they are handed to the
1627 capture interface without a TCP checksum being added to them.
1629 The only way to prevent this from happening would be to disable TCP checksum
1631 1. that might not even be possible on some OSes;
1632 2. that could reduce networking performance significantly.
1634 However, you can disable the check that Ethereal does of the TCP checksum,
1635 so that it won't report any packets as having TCP checksum errors, and so
1636 that it won't refuse to do TCP reassembly due to a packet having an
1637 incorrect TCP checksum. That can be set as an Ethereal preference by
1638 selecting "Preferences" from the "Edit" menu, opening up the "Protocols"
1639 list in the left-hand pane of the "Preferences" dialog box, selecting "TCP",
1640 from that list, turning off the "Check the validity of the TCP checksum when
1641 possible" option, clicking "Save" if you want to save that setting in your
1642 preference file, and clicking "OK".
1644 It can also be set on the Ethereal or Tethereal command line with a -o
1645 tcp.check_checksum:false command-line flag, or manually set in your
1646 preferences file by adding a tcp.check_checksum:false line.
1648 Q 5.15: I've just installed Ethereal, and the traffic on my local LAN is
1651 A: We have a collection of strange and exotic sample capture files at
1652 http://wiki.ethereal.com/SampleCaptures
1654 Q 5.16: When I run Ethereal on Solaris 8, it dies with a Bus Error when I
1657 A: Some versions of the GTK+ library from www.sunfreeware.org appear to be
1658 buggy, causing Ethereal to drop core with a Bus Error. Un-install those
1659 packages, and try getting the 1.2.10 version from that site, or the version
1660 from The Written Word, or the version from Sun's GNOME distribution, or the
1661 version from the supplemental software CD that comes with the Solaris media
1662 kit, or build it from source from the GTK Web site. Update the GLib library
1663 to the 1.2.10 version, from the same source, as well. (If you get the 1.2.10
1664 versions from www.sunfreeware.org, and the problem persists, un-install them
1665 and try installing one of the other versions mentioned.)
1667 Similar problems may exist with older versions of GTK+ for earlier versions
1670 Q 5.17: When I run Ethereal, I get an error
1672 Gtk-CRITICAL **: file gtkwindow.c: line 3107 (gtk_window_resize):
1673 assertion `height > 0' failed.
1675 A: This is a bug in Ethereal 0.10.5 and 0.10.5a, which is fixed in Ethereal
1676 0.10.6 and later releases.
1678 Q 5.18: When I run Tethereal with the "-x" option, it crashes with an error
1680 "** ERROR **: file print.c: line 691 (print_line): should not be reached.
1682 A: This is a bug in Ethereal 0.10.0a, which is fixed in 0.10.1 and later
1683 releases. To work around the bug, don't use "-x" unless you're also using
1684 "-V"; note that "-V" produces a full dissection of each packet, so you might
1687 Q 5.19: When I run Ethereal on Windows NT, it dies with a Dr. Watson error,
1688 reporting an "Integer division by zero" exception, when I start it.
1690 A: In at least some case, this appears to be due to using the default VGA
1691 driver; if that's not the correct driver for your video card, try running
1692 the correct driver for your video card.
1694 Q 5.20: When I try to run Ethereal, it complains about sprint_realloc_objid
1697 A: Ethereal can only be linked with version 4.2.2 or later of UCD SNMP. Your
1698 version of Ethereal was dynamically linked with such a version of UCD SNMP;
1699 however, you have an older version of UCD SNMP installed, which means that
1700 when Ethereal is run, it tries to link to the older version, and fails. You
1701 will have to replace that version of UCD SNMP with version 4.2.2 or a later
1704 Q 5.21: I'm running Ethereal on Linux; why do my time stamps have only 100ms
1705 resolution, rather than 1us resolution?
1707 A: Ethereal gets time stamps from libpcap/WinPcap, and libpcap/WinPcap get
1708 them from the OS kernel, so Ethereal - and any other program using libpcap,
1709 such as tcpdump - is at the mercy of the time stamping code in the OS for
1712 At least on x86-based machines, Linux can get high-resolution time stamps on
1713 newer processors with the Time Stamp Counter (TSC) register; for example,
1714 Intel x86 processors, starting with the Pentium Pro, and including all x86
1715 processors since then, have had a TSC, and other vendors probably added the
1716 TSC at some point to their families of x86 processors.
1718 The Linux kernel must be configured with the CONFIG_X86_TSC option enabled
1719 in order to use the TSC. Make sure this option is enabled in your kernel.
1721 In addition, some Linux distributions may have bugs in their versions of the
1722 kernel that cause packets not to be given high-resolution time stamps even
1723 if the TSC is enabled. See, for example, bug 61111 for Red Hat Linux 7.2. If
1724 your distribution has a bug such as this, you may have to run a standard
1725 kernel from kernel.org in order to get high-resolution time stamps.
1727 Q 5.22: I'm capturing packets on {Windows 95, Windows 98, Windows Me}; why
1728 are the time stamps on packets wrong?
1730 A: This is due to a bug in WinPcap. The bug should be fixed in WinPcap 3.0.
1732 Q 5.23: When I try to run Ethereal on Windows, it fails to run because it
1733 can't find packet.dll.
1735 A: In older versions of Ethereal, there were two binary distributions
1736 available for Windows, one that supported capturing packets, and one that
1737 didn't. The version that supported capturing packets required that you
1738 install the WinPcap driver; if you didn't install it, it would fail to run
1739 because it couldn't find packet.dll.
1741 The current version of Ethereal has only one binary distribution for
1742 Windows; that version will check whether WinPcap is installed and, if it's
1743 not, will disable support for packet capture.
1745 The WinPcap driver and libraries can be downloaded from the WinPcap Web
1746 site, the local mirror of the WinPcap Web site, or the Wiretapped.net mirror
1747 of the WinPcap site.
1749 Q 5.24: I'm running Ethereal on Windows NT 4.0/Windows 2000/Windows
1750 XP/Windows Server 2003; my machine has a PPP (dial-up POTS, ISDN, etc.)
1751 interface, and it shows up in the "Interface" item in the "Capture Options"
1752 dialog box. Why can no packets be sent on or received from that network
1753 while I'm trying to capture traffic on that interface?
1755 A: Some versions of WinPcap have problems with PPP WAN interfaces on Windows
1756 NT 4.0, Windows 2000, Windows XP, and Windows Server 2003; one symptom that
1757 may be seen is that attempts to capture in promiscuous mode on the interface
1758 cause the interface to be incapable of sending or receiving packets. You can
1759 disable promiscuous mode using the -p command-line flag or the item in the
1760 "Capture Preferences" dialog box, but this may mean that outgoing packets,
1761 or incoming packets, won't be seen in the capture.
1763 On Windows 2000, Windows XP, and Windows Server 2003, but not Windows NT 4.0
1764 or Windows Vista Beta 1, you should be able to capture on the
1765 "GenericDialupAdapter" with WinPcap 3.1. (3.1 beta releases called it the
1766 "NdisWanAdapter"; if you're using a 3.1 beta release, you should un-install
1767 it and install the final 3.1 release.) See the Ethereal Wiki item on PPP
1768 capturing for details.
1770 Q 5.25: I'm running Ethereal on Windows 95/98/Me, on a machine with more
1771 than one network adapter of the same type; Ethereal shows all of those
1772 adapters with the same name, but I can't use any of those adapters other
1775 A: Unfortunately, Windows 95/98/Me gives the same name to multiple instances
1776 of the type of same network adapter. Therefore, WinPcap cannot distinguish
1777 between them, so a WinPcap-based application can capture only on the first
1778 such interface; Ethereal is a libpcap/WinPcap-based application.
1780 Q 5.26: I'm running Ethereal on Windows, and I'm not seeing any traffic
1781 being sent by the machine running Ethereal.
1783 A: If you are running some form of VPN client software, it might be causing
1784 this problem; people have seen this problem when they have Check Point's VPN
1785 software installed on their machine. If that's the cause of the problem, you
1786 will have to remove the VPN software in order to have Ethereal (or any other
1787 application using WinPcap) see outgoing packets; unfortunately, neither we
1788 nor the WinPcap developers know any way to make WinPcap and the VPN software
1791 Also, some drivers for Windows (especially some wireless network interface
1792 drivers) apparently do not, when running in promiscuous mode, arrange that
1793 outgoing packets are delivered to the software that requested that the
1794 interface run promiscuously; try turning promiscuous mode off.
1796 Q 5.27: I'm trying to capture traffic but I'm not seeing any.
1798 A: Is the machine running Ethereal sending out any traffic on the network
1799 interface on which you're capturing, or receiving any traffic on that
1800 network, or is there any broadcast traffic on the network or multicast
1801 traffic to a multicast group to which the machine running Ethereal belongs?
1803 If not, this may just be a problem with promiscuous sniffing, either due to
1804 running on a switched network or a dual-speed hub, or due to problems with
1805 the interface not supporting promiscuous mode; see the response to this
1808 Otherwise, on Windows, see the response to this question and, on a
1809 UNIX-flavored OS, see the response to this question.
1811 Q 5.28: I have an XXX network card on my machine; if I try to capture on it,
1812 my machine crashes or resets itself.
1814 A: This is almost certainly a problem with one or more of:
1815 * the operating system you're using;
1816 * the device driver for the interface you're using;
1817 * the libpcap/WinPcap library and, if this is Windows, the WinPcap device
1821 * if you are using Windows, see the WinPcap support page (or the local
1822 mirror of that page) - check the "Submitting bugs" section;
1823 * if you are using some Linux distribution, some version of BSD, or some
1824 other UNIX-flavored OS, you should report the problem to the company or
1825 organization that produces the OS (in the case of a Linux distribution,
1826 report the problem to whoever produces the distribution).
1828 Q 5.29: My machine crashes or resets itself when I select "Start" from the
1829 "Capture" menu or select "Preferences" from the "Edit" menu.
1831 A: Both of those operations cause Ethereal to try to build a list of the
1832 interfaces that it can open; it does so by getting a list of interfaces and
1833 trying to open them. There is probably an OS, driver, or, for Windows,
1834 WinPcap bug that causes the system to crash when this happens; see the
1837 Q 5.30: Does Ethereal work on Windows Me?
1839 A: Yes, but if you want to capture packets, you will need to install the
1840 latest version of WinPcap, as 2.02 and earlier versions of WinPcap didn't
1841 support Windows Me. You should also install the latest version of Ethereal
1844 Q 5.31: Does Ethereal work on Windows XP?
1846 A: Yes, but if you want to capture packets, you will need to install the
1847 latest version of WinPcap, as 2.2 and earlier versions of WinPcap didn't
1850 Q 5.32: Why doesn't Ethereal correctly identify RTP packets? It shows them
1853 A: Ethereal can identify a UDP datagram as containing a packet of a
1854 particular protocol running atop UDP only if
1855 1. The protocol in question has a particular standard port number, and the
1856 UDP source or destination port number is that port
1857 2. Packets of that protocol can be identified by looking for a "signature"
1858 of some type in the packet - i.e., some data that, if Ethereal finds it
1859 in some particular part of a packet, means that the packet is almost
1860 certainly a packet of that type.
1861 3. Some other traffic earlier in the capture indicated that, for example,
1862 UDP traffic between two particular addresses and ports will be RTP
1865 RTP doesn't have a standard port number, so 1) doesn't work; it doesn't, as
1866 far as I know, have any "signature", so 2) doesn't work.
1868 That leaves 3). If there's RTSP traffic that sets up an RTP session, then,
1869 at least in some cases, the RTSP dissector will set things up so that
1870 subsequent RTP traffic will be identified. Currently, that's the only place
1871 we do that; there may be other places.
1873 However, there will always be places where Ethereal is simply incapable of
1874 deducing that a given UDP flow is RTP; a mechanism would be needed to allow
1875 the user to specify that a given conversation should be treated as RTP. As
1876 of Ethereal 0.8.16, such a mechanism exists; if you select a UDP or TCP
1877 packet, the right mouse button menu will have a "Decode As..." menu item,
1878 which will pop up a dialog box letting you specify that the source port, the
1879 destination port, or both the source and destination ports of the packet
1880 should be dissected as some particular protocol.
1882 Q 5.33: Why doesn't Ethereal show Yahoo Messenger packets in captures that
1883 contain Yahoo Messenger traffic?
1885 A: Ethereal only recognizes as Yahoo Messenger traffic packets to or from
1886 TCP port 3050 that begin with "YPNS", "YHOO", or "YMSG". TCP segments that
1887 start with the middle of a Yahoo Messenger packet that takes more than one
1888 TCP segment will not be recognized as Yahoo Messenger packets (even if the
1889 TCP segment also contains the beginning of another Yahoo Messenger packet).
1891 Q 5.34: Why do I get the error
1893 Gdk-ERROR **: Palettized display (256-colour) mode not supported on
1897 when I try to run Ethereal on Windows?
1899 A: Ethereal is built using the GTK+ toolkit, which supports most
1900 UNIX-flavored OSes, and also supports Windows.
1902 Windows versions of Ethereal before 0.9.14 were built with an older version
1903 of that toolkit, which didn't support 256-color mode on Windows - it
1904 required HiColor (16-bit colors) or more.
1906 Windows versions of Ethereal 0.9.14 and later are built with a version of
1907 that toolkit that supports 256-color mode; upgrade to the current version of
1908 Ethereal if you want to run on a display in 256-color mode.
1910 Q 5.35: When I capture on Windows in promiscuous mode, I can see packets
1911 other than those sent to or from my machine; however, those packets show up
1912 with a "Short Frame" indication, unlike packets to or from my machine. What
1913 should I do to arrange that I see those packets in their entirety?
1915 A: In at least some cases, this appears to be the result of PGPnet running
1916 on the network interface on which you're capturing; turn it off on that
1919 Q 5.36: I'm capturing packets on a machine on a VLAN; why don't the packets
1920 I'm capturing have VLAN tags?
1922 A: You might be capturing on what might be called a "VLAN interface" - the
1923 way a particular OS makes VLANs plug into the networking stack might, for
1924 example, be to have a network device object for the physical interface,
1925 which takes VLAN packets, strips off the VLAN header and constructs an
1926 Ethernet header, and passes that packet to an internal network device object
1927 for the VLAN, which then passes the packets onto various higher-level
1928 protocol implementations.
1930 In order to see the raw Ethernet packets, rather than "de-VLANized" packets,
1931 you would have to capture not on the virtual interface for the VLAN, but on
1932 the interface corresponding to the physical network device, if possible. See
1933 the Ethereal Wiki item on VLAN capturing for details.
1935 Q 5.37: How can I capture raw 802.11 frames, including non-data (management,
1938 A: That depends on the operating system on which you're running, and on the
1939 802.11 interface on which you're capturing.
1941 This would probably require that you capture in promiscuous mode or in the
1942 mode called "monitor mode" or "RFMON mode". On some platforms, or with some
1943 cards, this might require that you capture in monitor mode - promiscuous
1944 mode might not be sufficient. If you want to capture traffic on networks
1945 other than the one with which you're associated, you will have to capture in
1948 Not all operating systems support capturing non-data packets and, even on
1949 operating systems that do support it, not all drivers, and thus not all
1950 interfaces, support it. Even on those that do, monitor mode might not be
1951 supported by the operating system or by the drivers for all interfaces.
1953 NOTE: an interface running in monitor mode will, on most if not all
1954 platforms, not be able to act as a regular network interface; putting it
1955 into monitor mode will, in effect, take your machine off of whatever network
1956 it's on as long as the interface is in monitor mode, allowing it only to
1957 passively capture packets.
1959 This means that you should disable name resolution when capturing in monitor
1960 mode; otherwise, when Ethereal (or Tethereal, or tcpdump) tries to display
1961 IP addresses as host names, it will probably block for a long time trying to
1962 resolve the name because it will not be able to communicate with any DNS or
1965 See the Ethereal Wiki item on 802.11 capturing for details.
1967 Q 5.38: How do I capture on an 802.11 device in monitor mode?
1969 A: Whether you will be able to capture in monitor mode depends on the
1970 operating system, adapter, and driver you're using. See the previous
1971 question for information on monitor mode, including a link to the Ethereal
1972 Wiki page that gives details on 802.11 capturing.
1974 Q 5.39: I'm trying to capture 802.11 traffic on Windows; why am I not seeing
1977 A: At least some 802.11 card drivers on Windows appear not to see any
1978 packets if they're running in promiscuous mode. Try turning promiscuous mode
1979 off; you'll only be able to see packets sent by and received by your
1980 machine, not third-party traffic, and it'll look like Ethernet traffic and
1981 won't include any management or control frames, but that's a limitation of
1984 See MicroLogix's list of cards supported with WinPcap for information on
1985 support of various adapters and drivers with WinPcap.
1987 Q 5.40: I'm trying to capture 802.11 traffic on Windows; why am I seeing
1988 packets received by the machine on which I'm capturing traffic, but not
1989 packets sent by that machine?
1991 A: This appears to be another problem with promiscuous mode; try turning it
1994 Q 5.41: How can I capture packets with CRC errors?
1996 A: Ethereal can capture only the packets that the packet capture library -
1997 libpcap on UNIX-flavored OSes, and the WinPcap port to Windows of libpcap on
1998 Windows - can capture, and libpcap/WinPcap can capture only the packets that
1999 the OS's raw packet capture mechanism (or the WinPcap driver, and the
2000 underlying OS networking code and network interface drivers, on Windows)
2001 will allow it to capture.
2003 Unless the OS always supplies packets with errors such as invalid CRCs to
2004 the raw packet capture mechanism, or can be configured to do so, invalid
2005 CRCs to the raw packet capture mechanism, Ethereal - and other programs that
2006 capture raw packets, such as tcpdump - cannot capture those packets. You
2007 will have to determine whether your OS needs to be so configured and, if so,
2008 can be so configured, configure it if necessary and possible, and make
2009 whatever changes to libpcap and the packet capture program you're using are
2010 necessary, if any, to support capturing those packets.
2012 Most OSes probably do not support capturing packets with invalid CRCs on
2013 Ethernet, and probably do not support it on most other link-layer types.
2014 Some drivers on some OSes do support it, such as some Ethernet drivers on
2015 FreeBSD; in those OSes, you might always get those packets, or you might
2016 only get them if you capture in promiscuous mode (you'd have to determine
2019 Note that libpcap does not currently supply to programs that use it an
2020 indication of whether the packet's CRC was invalid (because the drivers
2021 themselves do not supply that information to the raw packet capture
2022 mechanism); therefore, Ethereal will not indicate which packets had CRC
2023 errors unless the FCS was captured (see the next question) and you're using
2024 Ethereal 0.9.15 and later, in which case Ethereal will check the CRC and
2025 indicate whether it's correct or not.
2027 Q 5.42: How can I capture entire frames, including the FCS?
2029 A: Ethereal can only capture data that the packet capture library - libpcap
2030 on UNIX-flavored OSes, and the WinPcap port to Windows of libpcap on Windows
2031 - can capture, and libpcap/WinPcap can capture only the data that the OS's
2032 raw packet capture mechanism (or the WinPcap driver, and the underlying OS
2033 networking code and network interface drivers, on Windows) will allow it to
2036 For any particular link-layer network type, unless the OS supplies the FCS
2037 of a frame as part of the frame, or can be configured to do so, Ethereal -
2038 and other programs that capture raw packets, such as tcpdump - cannot
2039 capture the FCS of a frame. You will have to determine whether your OS needs
2040 to be so configured and, if so, can be so configured, configure it if
2041 necessary and possible, and make whatever changes to libpcap and the packet
2042 capture program you're using are necessary, if any, to support capturing the
2045 Most OSes do not support capturing the FCS of a frame on Ethernet, and
2046 probably do not support it on most other link-layer types. Some drivres on
2047 some OSes do support it, such as some (all?) Ethernet drivers on NetBSD and
2048 possibly the driver for Apple's gigabit Ethernet interface in Mac OS X; in
2049 those OSes, you might always get the FCS, or you might only get the FCS if
2050 you capture in promiscuous mode (you'd have to determine which is the case).
2052 Versions of Ethereal prior to 0.9.15 will not treat an Ethernet FCS in a
2053 captured packet as an FCS. 0.9.15 and later will attempt to determine
2054 whether there's an FCS at the end of the frame and, if it thinks there is,
2055 will display it as such, and will check whether it's the correct CRC-32
2058 Q 5.43: Why does Ethereal hang after I stop a capture?
2060 A: The most likely reason for this is that Ethereal is trying to look up an
2061 IP address in the capture to convert it to a name (so that, for example, it
2062 can display the name in the source address or destination address columns),
2063 and that lookup process is taking a very long time.
2065 Ethereal calls a routine in the OS of the machine on which it's running to
2066 convert of IP addresses to the corresponding names. That routine probably
2067 does one or more of:
2068 * a search of a system file listing IP addresses and names;
2069 * a lookup using DNS;
2070 * on UNIX systems, a lookup using NIS;
2071 * on Windows systems, a NetBIOS-over-TCP query.
2073 If a DNS server that's used in an address lookup is not responding, the
2074 lookup will fail, but will only fail after a timeout while the system
2075 routine waits for a reply.
2077 In addition, on Windows systems, if the DNS lookup of the address fails,
2078 either because the server isn't responding or because there are no records
2079 in the DNS that could be used to map the address to a name, a
2080 NetBIOS-over-TCP query will be made. That query involves sending a message
2081 to the NetBIOS-over-TCP name service on that machine, asking for the name
2082 and other information about the machine. If the machine isn't running
2083 software that responds to those queries - for example, many non-Windows
2084 machines wouldn't be running that software - the lookup will only fail after
2085 a timeout. Those timeouts can cause the lookup to take a long time.
2087 If you disable network address-to-name translation - for example, by turning
2088 off the "Enable network name resolution" option in the "Capture Options"
2089 dialog box for starting a network capture - the lookups of the address won't
2090 be done, which may speed up the process of reading the capture file after
2091 the capture is stopped. You can make that setting the default by selecting
2092 "Preferences" from the "Edit" menu, turning off the "Enable network name
2093 resolution" option in the "Name resolution" options in the preferences
2094 disalog box, and using the "Save" button in that dialog box; note that this
2095 will save all your current preference settings.
2097 If Ethereal hangs when reading a capture even with network name resolution
2098 turned off, there might, for example, be a bug in one of Ethereal's
2099 dissectors for a protocol causing it to loop infinitely. If you're not
2100 running the most recent release of Ethereal, you should first upgrade to
2101 that release, as, if there's a bug of that sort, it might've been fixed in a
2102 release after the one you're running. If the hang occurs in the most recent
2103 release of Ethereal, the bug should be reported to the Ethereal developers'
2104 mailing list at ethereal-dev@ethereal.com.
2106 On UNIX-flavored OSes, please try to force Ethereal to dump core, by sending
2107 it a SIGABRT signal (usually signal 6) with the kill command, and then get a
2108 stack trace if you have a debugger installed. A stack trace can be obtained
2109 by using your debugger (gdb in this example), the Ethereal binary, and the
2110 resulting core file. Here's an example of how to use the gdb command
2114 ..... prints the stack trace
2118 The core dump file may be named "ethereal.core" rather than "core" on some
2119 platforms (e.g., BSD systems).
2121 Also, if at all possible, please send a copy of the capture file that caused
2122 the problem; when capturing packets, Ethereal normally writes captured
2123 packets to a temporary file, which will probably be in /tmp or /var/tmp on
2124 UNIX-flavored OSes, \TEMP on the main system disk (normally C:) on Windows
2125 9x/Me/NT 4.0, and \Documents and Settings\your login name\Local
2126 Settings\Temp on the main system disk on Windows 2000/Windows XP/Windows
2127 Server 2003, so the capture file will probably be there. It will have a name
2128 beginning with ether, with some mixture of letters and numbers after that.
2129 Please don't send a trace file greater than 1 MB when compressed; instead,
2130 make it available via FTP or HTTP, or say it's available but leave it up to
2131 a developer to ask for it. If the trace file contains sensitive information
2132 (e.g., passwords), then please do not send it.
2134 Q 5.44: How can I search for, or filter, packets that have a particular
2135 string anywhere in them?
2137 A: If you want to do this when capturing, you can't. That's a feature that
2138 would be hard to implement in capture filters without changes to the capture
2139 filter code, which, on many platforms, is in the OS kernel and, on other
2140 platforms, is in the libpcap library.
2142 In releases prior to 0.9.14, you also can't search for, or filter, packets
2143 containing a particular string even after you've captured them.
2145 In 0.9.14, you can search for, but not filter, packets that have a
2146 particular string; this has been added to the "Find Frame" dialog ("Find
2147 Frame" under the "Edit" menu, or control-F).
2149 In 0.9.15 and later, you can search for those packets using either the
2150 mechanism introduced in 0.9.14 or using the new "contains" operator in
2151 filter expressions, which lets you search the entire packet or text string
2152 or byte string fields in the packet; the "contains" operator can also be
2153 used in expressions used to filter the display.
2155 Q 5.45: How do I filter a capture to see traffic for virus XXX?
2157 A: For some viruses/worms there might be a capture filter to recognize the
2158 virus traffic. Check the CaptureFilters page on the Ethereal Wiki to see if
2159 anybody's added such a filter.
2161 Note that Ethereal was not designed to be an intrusion detection system; you
2162 might be able to use it as an IDS, but in most cases software designed to be
2163 an IDS, such as Snort or Prelude, will probably work better.
2165 The Bleeding Edge of Snort has a collection of signatures for Snort to
2166 detect various viruses, worms, and the like.
2168 Please send support questions about Ethereal to the
2169 ethereal-users[AT]ethereal.com mailing list.
2170 For corrections/additions/suggestions for this web page (and not Ethereal
2171 support questions), please send email to ethereal-web[AT]ethereal.com .
2172 Last modified: Thu, September 15 2005.
git.samba.org / obnox / wireshark / wip.git / blob