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 683 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)
267 AFS (4.0) Replication Server call declarations
270 AIM Buddylist Service
277 AIM Invitation Service
282 AIM Privacy Management Service
284 AIM Server Side Themes
291 ANSI IS-637-A (SMS) Teleservice Layer
292 ANSI IS-637-A (SMS) Transport Layer
293 ANSI IS-683-A (OTA (Mobile))
294 ANSI IS-801 (Location Services (PLD))
295 ANSI Mobile Application Part
296 AOL Instant Messenger
305 AVS WLAN Capture header
307 Active Directory Setup
308 Ad hoc On-demand Distance Vector Routing Protocol
310 Address Resolution Protocol
312 Aggregate Server Access Protocol
314 Alteon - Transparent Proxy Cache Protocol
315 Andrew File System (AFS)
316 Apache JServ Protocol v1.3
317 Apple IP-over-IEEE 1394
318 AppleTalk Filing Protocol
319 AppleTalk Session Protocol
320 AppleTalk Transaction Protocol packet
321 Appletalk Address Resolution Protocol
322 Application Configuration Access Protocol
324 Aruba - Aruba Discovery Protocol
325 Async data over ISDN (V.120)
326 Asynchronous Layered Coding
327 Authentication Header
328 BACnet Virtual Link Control
333 Banyan Vines Fragmentation Protocol
340 Base Station Subsystem GPRS Protocol
341 Basic Encoding Rules (ASN.1 X.690)
342 Bearer Independent Call Control
343 Bi-directional Fault Detection Control Message
345 Blocks Extensible Exchange Protocol
346 Blubster/Piolet MANOLITO Protocol
350 Border Gateway Protocol
351 Building Automation and Control Network APDU
352 Building Automation and Control Network NPDU
355 CDS Clerk Server Calls
357 Cast Client Control Protocol
358 Certificate Management Protocol
359 Certificate Request Message Format
360 Check Point High Availability Protocol
363 Cisco Discovery Protocol
364 Cisco Group Management Protocol
366 Cisco Hot Standby Router Protocol
368 Cisco Interior Gateway Routing Protocol
371 Cisco Session Management
373 CoSine IPNOS L2 debug output
374 Common Industrial Protocol
375 Common Open Policy Service
376 Common Unix Printing System (CUPS) Browsing Protocol
378 Configuration Test Protocol (loopback)
379 Connectionless Lightweight Directory Access Protocol
380 Coseventcomm Dissector Using GIOP API
381 Cosnaming Dissector Using GIOP API
382 Cross Point Frame Injector
383 Cryptographic Message Syntax
384 DCE Distributed Time Service Local Server
385 DCE Distributed Time Service Provider
388 DCE Security ID Mapper
392 DCE/RPC CDS Solicitation
393 DCE/RPC Conversation Manager
394 DCE/RPC Directory Acl Interface
395 DCE/RPC Endpoint Mapper
396 DCE/RPC Endpoint Mapper v4
398 DCE/RPC FLDB UBIK TRANSFER
399 DCE/RPC FLDB UBIKVOTE
402 DCE/RPC NCS 1.5.1 Local Location Broker
403 DCE/RPC Operations between registry server replicas
410 DCE/RPC Registry Password Management
411 DCE/RPC Registry Server Attributes Schema
412 DCE/RPC Registry server propagation interface - ACLs.
413 DCE/RPC Registry server propagation interface - PGO items
414 DCE/RPC Registry server propagation interface - properties and poli
416 DCE/RPC Remote Management
417 DCE/RPC Repserver Calls
418 DCE/RPC TokenServer Calls
422 DCOM IRemoteActivation
424 DEC Spanning Tree Protocol
430 DNS Control Program Server
432 DOCSIS Appendix C TLV's
433 DOCSIS Baseline Privacy Key Management Attributes
434 DOCSIS Baseline Privacy Key Management Request
435 DOCSIS Baseline Privacy Key Management Response
436 DOCSIS Dynamic Service Addition Acknowledge
437 DOCSIS Dynamic Service Addition Request
438 DOCSIS Dynamic Service Addition Response
439 DOCSIS Dynamic Service Change Acknowledgement
440 DOCSIS Dynamic Service Change Request
441 DOCSIS Dynamic Service Change Response
442 DOCSIS Dynamic Service Delete Request
443 DOCSIS Dynamic Service Delete Response
444 DOCSIS Initial Ranging Message
445 DOCSIS Mac Management
446 DOCSIS Range Request Message
447 DOCSIS Ranging Response
448 DOCSIS Registration Acknowledge
449 DOCSIS Registration Requests
450 DOCSIS Registration Responses
451 DOCSIS Upstream Bandwidth Allocation
452 DOCSIS Upstream Channel Change Request
453 DOCSIS Upstream Channel Change Response
454 DOCSIS Upstream Channel Descriptor
455 DOCSIS Upstream Channel Descriptor Type 29
456 DOCSIS Vendor Specific Endodings
457 DPNSS/DASS2-User Adaptation Layer
461 Data Stream Interface
462 Datagram Delivery Protocol
463 Decompressed SigComp message as raw text
465 Digital Audio Access Protocol
466 Distance Vector Multicast Routing Protocol
467 Distcc Distributed Compiler
468 Distributed Checksum Clearinghouse Protocol
469 Distributed Network Protocol 3.0
471 Dynamic DNS Tools Protocol
472 Dynamic Trunking Protocol
475 Encapsulating Security Payload
476 Endpoint Name Resolution Protocol
477 Enhanced Interior Gateway Routing Protocol
478 EtherNet/IP (Industrial Protocol)
482 Extended Security Services
483 Extensible Authentication Protocol
485 FC Fabric Configuration Server
489 Fiber Distributed Data Interface
491 Fibre Channel Common Transport
492 Fibre Channel Fabric Zone Server
493 Fibre Channel Name Server
494 Fibre Channel Protocol for SCSI
496 Fibre Channel Security Protocol
497 Fibre Channel Single Byte Command
498 File Transfer Protocol (FTP)
499 Financial Information eXchange Protocol
503 GARP Multicast Registration Protocol
504 GARP VLAN Registration Protocol
506 GPRS Tunneling Protocol
510 GSM SMS TPDU (GSM 03.40)
511 GSM Short Message Service User Data
512 GSM_MobileAPplication
513 General Inter-ORB Protocol
514 Generic Routing Encapsulation
515 Generic Security Service Application Program Interface
518 H235-SECURITY-MESSAGES
519 HP Extended Local-Link Control
520 HP Remote Maintenance Protocol
522 HP-UX Network Tracing and Logging
523 Hummingbird NFS Daemon
525 Hypertext Transfer Protocol
545 ICBAPhysicalDevicePCEvent
553 IEEE 802.11 Radiotap Capture header
554 IEEE 802.11 wireless LAN
555 IEEE 802.11 wireless LAN management frame
556 IEEE802a OUI Extended Ethertype
559 IP Device Control (SS7 over IP)
561 IP Payload Compression
562 IP Virtual Services Sync Daemon
564 IPX Routing Information Protocol
569 ISDN Q.921-User Adaptation Layer
571 ISO 10589 ISIS InTRA Domain Routeing Information Exchange Protocol
572 ISO 8073 COTP Connection-Oriented Transport Protocol
573 ISO 8327-1 OSI Session Protocol
574 ISO 8473 CLNP ConnectionLess Network Protocol
575 ISO 8602 CLTP ConnectionLess Transport Protocol
576 ISO 8823 OSI Presentation Protocol
577 ISO 9542 ESIS Routeing Information Exchange Protocol
578 ISystemActivator ISystemActivator Resolver
580 ITU-T Recommendation H.261
581 ITU-T Recommendation H.263 RTP Payload header (RFC2190)
583 Information Access Protocol
585 Intelligent Platform Management Interface
586 Inter-Access-Point Protocol
587 Inter-Asterisk eXchange v2
588 InterSwitch Message Protocol
590 Internet Cache Protocol
591 Internet Communications Engine Protocol
592 Internet Content Adaptation Protocol
593 Internet Control Message Protocol
594 Internet Control Message Protocol v6
595 Internet Group Management Protocol
596 Internet Group membership Authentication Protocol
597 Internet Message Access Protocol
598 Internet Printing Protocol
600 Internet Protocol Version 6
602 Internet Security Association and Key Management Protocol
603 Internetwork Datagram Protocol
604 Internetwork Packet eXchange
606 IrDA Link Access Protocol
607 IrDA Link Management Protocol
608 JPEG File Interchange Format
614 Kerberized Internet Negotiation of Key
616 Kerberos Administration
620 LWAPP Encapsulated Packet
622 Label Distribution Protocol
624 Layer 2 Tunneling Protocol
625 Light Weight DNS RESolver (BIND9)
626 Lightweight Directory Access Protocol
627 Line Printer Daemon Protocol
629 Link Access Procedure Balanced (LAPB)
630 Link Access Procedure Balanced Ethernet (LAPBETHER)
631 Link Access Procedure, Channel D (LAPD)
632 Link Management Protocol (LMP)
633 Linux cooked-mode capture
634 Local Management Interface
635 LocalTalk Link Access Protocol
637 Logical Link Control GPRS
639 Logotype Certificate Extensions
640 Lucent/Ascend debug output
645 MIME Multipart Media Encapsulation
646 MMS Message Encapsulation
649 MSN Messenger Service
650 MSNIP: Multicast Source Notification of Interest Protocol
651 MTP 2 Transparent Proxy
652 MTP 2 User Adaptation Layer
653 MTP 3 User Adaptation Layer
654 MTP2 Peer Adaptation Layer
655 Media Gateway Control Protocol
657 Media Type: application/x-jxta-msg
658 Media Type: message/http
659 Message Transfer Part Level 2
660 Message Transfer Part Level 3
661 Message Transfer Part Level 3 Management
662 Meta Analysis Tracing Engine
663 Microsoft Distributed File System
664 Microsoft Distributed Link Tracking Server Service
665 Microsoft Encrypted File System Service
666 Microsoft Eventlog Service
667 Microsoft Exchange MAPI
668 Microsoft File Replication Service
669 Microsoft File Replication Service API
670 Microsoft Local Security Architecture
671 Microsoft Messenger Service
672 Microsoft Network Logon
673 Microsoft Plug and Play service
675 Microsoft Routing and Remote Access Service
676 Microsoft Security Account Manager
677 Microsoft Server Service
678 Microsoft Service Control
679 Microsoft Spool Subsystem
680 Microsoft Task Scheduler Service
681 Microsoft Telephony API Service
682 Microsoft Windows Browser Protocol
683 Microsoft Windows Lanman Remote API Protocol
684 Microsoft Windows Logon Protocol (Old)
685 Microsoft Workstation Service
691 MultiProtocol Label Switching Header
692 Multicast Router DISCovery protocol
693 Multicast Source Discovery Protocol
694 Multiprotocol Label Switching Echo
701 NTLM Secure Service Provider
702 Name Binding Protocol
703 Name Management Protocol over IPX
704 Negative-acknowledgment Oriented Reliable Multicast
706 NetBIOS Datagram Service
708 NetBIOS Session Service
710 NetScape Certificate Extensions
711 NetWare Core Protocol
712 NetWare Link Services Protocol
713 NetWare Serialization Protocol
714 Network Data Management Protocol
716 Network Lock Manager Protocol
717 Network News Transfer Protocol
718 Network Service Over IP
719 Network Status Monitor CallBack Protocol
720 Network Status Monitor Protocol
721 Network Time Protocol
723 Novell Distributed Print System
724 Novell Modular Authentication Service
726 OSI ISO 8571 FTAM Protocol
727 OSI ISO/IEC 10035-1 ACSE Protocol
728 Online Certificate Status Protocol
729 Open Policy Service Interface
730 Open Shortest Path First
731 OpenBSD Encapsulating device
732 OpenBSD Packet Filter log file
733 OpenBSD Packet Filter log file, pre 3.4
734 Optimized Link State Routing Protocol
738 PKIX CERT File Format
740 PKIX Time Stamp Protocol
744 PPP Bandwidth Allocation Control Protocol
745 PPP Bandwidth Allocation Protocol
746 PPP CDP Control Protocol
747 PPP Callback Control Protocol
748 PPP Challenge Handshake Authentication Protocol
749 PPP Compressed Datagram
750 PPP Compression Control Protocol
751 PPP IP Control Protocol
752 PPP IPv6 Control Protocol
753 PPP In HDLC-Like Framing
754 PPP Link Control Protocol
755 PPP MPLS Control Protocol
756 PPP Multilink Protocol
758 PPP OSI Control Protocol
759 PPP Password Authentication Protocol
761 PPP-over-Ethernet Discovery
762 PPP-over-Ethernet Session
763 PPPMux Control Protocol
766 PROFINET Real-Time Protocol
767 Packed Encoding Rules (ASN.1 X.691)
768 Packet Cable Lawful Intercept
771 Point-to-Point Protocol
772 Point-to-Point Tunnelling Protocol
773 Port Aggregation Protocol
777 Pragmatic General Multicast
778 Precision Time Protocol (IEEE1588)
780 Privilege Server operations
781 Protocol Independent Multicast
785 Quake II Network Protocol
786 Quake III Arena Network Protocol
787 Quake Network Protocol
788 QuakeWorld Network Protocol
789 Qualified Logical Link Control
795 RS Interface properties
797 RSYNC File Synchroniser
800 Radio Access Network Application Part
804 Real Time Streaming Protocol
805 Real-Time Media Access Control
806 Real-Time Publish-Subscribe Wire Protocol
807 Real-Time Transport Protocol
808 Real-time Transport Control Protocol
810 Redundant Link Management Protocol
811 Registry Server Attributes Manipulation Interface
812 Registry server administration operations.
814 Remote Management Control Protocol
815 Remote Override interface
816 Remote Procedure Call
822 Remote sec_login preauth interface.
823 Resource ReserVation Protocol (RSVP)
824 Retix Spanning Tree Protocol
826 Routing Information Protocol
827 Routing Table Maintenance Protocol
830 SEBEK - Kernel Data Capture
832 SMB (Server Message Block Protocol)
833 SMB MailSlot Protocol
836 SNMP Multiplex Protocol
839 SS7 SCCP-User Adaptation Layer
844 Sequenced Packet Protocol
845 Sequenced Packet eXchange
847 Service Advertisement Protocol
848 Service Location Protocol
849 Session Announcement Protocol
850 Session Description Protocol
851 Session Initiation Protocol
852 Session Initiation Protocol (SIP as raw text)
853 Short Message Peer to Peer
854 Short Message Relaying Service
855 Signaling Compression
856 Signalling Connection Control Part
857 Signalling Connection Control Part Management
858 Simple Mail Transfer Protocol
859 Simple Network Management Protocol
860 Simple Traversal of UDP Through NAT
863 Skinny Client Control Protocol
864 SliMP3 Communication Protocol
868 Spanning Tree Protocol
870 Stream Control Transmission Protocol
871 Subnetwork Dependent Convergence Protocol
872 Symantec Enterprise Firewall
873 Synchronous Data Link Control (SDLC)
875 Systems Network Architecture
876 Systems Network Architecture XID
880 TDMA RTmac Discipline
881 TEI Management Procedure, Channel D (LAPD)
884 Tazmen Sniffer Protocol
886 Teredo IPv6 over UDP tunneling
888 Time Synchronization Protocol
889 Tiny Transport Protocol
891 Token-Ring Media Access Control
892 Transaction Capabilities Application Part
893 Transmission Control Protocol
894 Transparent Network Substrate Protocol
895 Transport Adapter Layer Interface v1.0, RFC 3094
896 Trivial File Transfer Protocol
897 UDP Encapsulation of IPsec Packets
898 Universal Computer Protocol
899 Unlicensed Mobile Access
900 User Datagram Protocol
901 V5.2-User Adaptation Layer
902 Virtual Network Computing
903 Virtual Router Redundancy Protocol
904 Virtual Trunking Protocol
906 WAP Session Initiation Request
907 Web Cache Coordination Protocol
909 WebSphere MQ Programmable Command Formats
910 Wellfleet Breath of Life
911 Wellfleet Compression
915 Wireless Session Protocol
916 Wireless Transaction Protocol
917 Wireless Transport Layer Security
918 X Display Manager Control Protocol
922 X.509 Authentication Framework
923 X.509 Certificate Extensions
924 X.509 Information Framework
925 X.509 Selected Attribute Types
929 Yahoo Messenger Protocol
930 Yahoo YMSG Messenger Protocol
934 Yellow Pages Transfer
936 Zone Information Protocol
938 eXtensible Markup Language
939 giFT Internet File Transfer
946 Q 1.6: Are there any plans to support {your favorite protocol}?
948 A: Support for particular protocols is added to Ethereal as a result of
949 people contributing that support; no formal plans for adding support for
950 particular protocols in particular future releases exist.
952 Q 1.7: Can Ethereal read capture files from {your favorite network
955 A: Support for particular protocols is added to Ethereal as a result of
956 people contributing that support; no formal plans for adding support for
957 particular protocols in particular future releases exist.
959 If a network analyzer writes out files in a format already supported by
960 Ethereal (e.g., in libpcap format), Ethereal may already be able to read
961 them, unless the analyzer has added its own proprietary extensions to that
964 If a network analyzer writes out files in its own format, or has added
965 proprietary extensions to another format, in order to make Ethereal read
966 captures from that network analyzer, we would either have to have a
967 specification for the file format, or the extensions, sufficient to give us
968 enough information to read the parts of the file relevant to Ethereal, or
969 would need at least one capture file in that format AND a detailed textual
970 analysis of the packets in that capture file (showing packet time stamps,
971 packet lengths, and the top-level packet header) in order to
972 reverse-engineer the file format.
974 Note that there is no guarantee that we will be able to reverse-engineer a
977 Q 1.8: What devices can Ethereal use to capture packets?
979 A: Ethereal can read live data from Ethernet, Token-Ring, FDDI, serial (PPP
980 and SLIP) (if the OS on which it's running allows Ethereal to do so), 802.11
981 wireless LAN (if the OS on which it's running allows Ethereal to do so), ATM
982 connections (if the OS on which it's running allows Ethereal to do so), and
983 the "any" device supported on Linux by recent versions of libpcap. See the
984 list of supported capture media on various OSes for details (several items
985 in there say "Unknown", which doesn't mean "Ethereal can't capture on them",
986 it means "we don't know whether it can capture on them"; we expect that it
987 will be able to capture on many of them, but we haven't tried it ourselves -
988 if you try one of those types and it works, please send an update to
989 ethereal-web[AT]ethereal.com ).
991 It can also read a variety of capture file formats, including:
992 * AG Group/WildPackets EtherPeek/TokenPeek/AiroPeek/EtherHelp/Packet
994 * AIX's iptrace captures
995 * Accellent's 5Views LAN agent output
996 * Cinco Networks NetXRay captures
997 * Cisco Secure Intrusion Detection System IPLog output
998 * CoSine L2 debug output
999 * DBS Etherwatch VMS text output
1000 * Endace Measurement Systems' ERF format captures
1001 * EyeSDN USB S0 traces
1002 * HP-UX nettl captures
1003 * ISDN4BSD project i4btrace captures
1004 * Linux Bluez Bluetooth stack hcidump -w traces
1005 * Lucent/Ascend router debug output
1006 * Microsoft Network Monitor captures
1007 * Network Associates Windows-based Sniffer captures
1008 * Network General/Network Associates DOS-based Sniffer (compressed or
1009 uncompressed) captures
1010 * Network Instruments Observer version 9 captures
1011 * Novell LANalyzer captures
1012 * RADCOM's WAN/LAN analyzer captures
1013 * Shomiti/Finisar Surveyor captures
1014 * Toshiba's ISDN routers dump output
1015 * VMS TCPIPtrace/TCPtrace/UCX$TRACE output
1016 * Visual Networks' Visual UpTime traffic capture
1017 * libpcap, tcpdump and various other tools using tcpdump's capture format
1018 * snoop and atmsnoop output
1020 so that it can read traces from various network types, as captured by other
1021 applications or equipment, even if it cannot itself capture on those network
1024 Q 1.9: How do you pronounce Ethereal? Where did the name come from?
1026 A: The English pronunciation can be found in Merriam-Webster's online
1028 http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=ethereal.
1030 According to the book "Computer Networks" by Andrew Tannenbaum, Ethernet was
1031 named after the "luminiferous ether" which was once thought to carry
1032 electromagnetic radiation. Taking that into consideration, Ethereal seemed
1033 like an appropriate name for something that started out as an Ethernet
1036 2. Downloading Ethereal
1038 Q 2.1: I downloaded the Win32 installer, but when I try to run it, I get an
1041 A: The program you used to download it may have downloaded it incorrectly.
1042 Web browsers sometimes may do this.
1044 Try downloading it with, for example:
1045 * Wget, for which Windows binaries are available on the SunSITE FTP server
1046 at sunsite.tk or Heiko Herold's windows wget spot - wGetGUI offers a GUI
1047 interface that uses wget;
1048 * WS_FTP from Ipswitch,
1049 * the ftp command that comes with Windows.
1051 If you use the ftp command, make sure you do the transfer in binary mode
1052 rather than ASCII mode, by using the binary command before transferring the
1055 Q 2.2: When I try to download the WinPcap driver and library, I can't get to
1056 the WinPcap Web site.
1058 A: As is the case with all Web sites, that site won't necessarily always be
1059 accessible; the server may be down due to a problem or down for maintenance,
1060 or there may be a networking problem between you and the server. You should
1061 try again later, or try the local mirror or the Wiretapped.net mirror.
1063 3. Installing Ethereal
1065 Q 3.1: I installed an Ethereal RPM, but Ethereal doesn't seem to be
1066 installed; only Tethereal is installed.
1068 A: Older versions of the Red Hat RPMs for Ethereal put only the non-GUI
1069 components into the ethereal RPM, the fact that Ethereal is a GUI program
1070 nonwithstanding; newer versions make it a bit clearer by giving that RPM a
1071 name starting with ethereal-base.
1073 In those older versions, there's a separate ethereal-gnome RPM that includes
1074 GUI components such as Ethereal itself, the fact that Ethereal doesn't use
1075 GNOME nonwithstanding; newer versions make it a bit clearer by giving that
1076 RPM a name starting with ethereal-gtk+.
1078 Find the ethereal-gnome or ethereal-gtk+ RPM, and install that also.
1080 4. Building Ethereal
1082 Q 4.1: The configure script can't find pcap.h or bpf.h, but I have libpcap
1085 A: Are you sure pcap.h and bpf.h are installed? The official distribution of
1086 libpcap only installs the libpcap.a library file when "make install" is run.
1087 To install pcap.h and bpf.h, you must run "make install-incl". If you're
1088 running Debian or Redhat, make sure you have the "libpcap-dev" or
1089 "libpcap-devel" packages installed.
1091 It's also possible that pcap.h and bpf.h have been installed in a strange
1092 location. If this is the case, you may have to tweak aclocal.m4.
1094 Q 4.2: Why do I get the error
1096 dftest_DEPENDENCIES was already defined in condition TRUE, which implies
1097 condition HAVE_PLUGINS_TRUE
1099 when I try to build Ethereal from SVN or a SVN snapshot?
1101 A: You probably have automake 1.5 installed on your machine (the command
1102 automake --version will report the version of automake on your machine).
1103 There is a bug in that version of automake that causes this problem; upgrade
1104 to a later version of automake (1.6 or later).
1106 Q 4.3: The link fails with a number of "Output line too long." messages
1107 followed by linker errors.
1109 A: The version of the sed command on your system is incapable of handling
1110 very long lines. On Solaris, for example, /usr/bin/sed has a line length
1111 limit too low to allow libtool to work; /usr/xpg4/bin/sed can handle it, as
1112 can GNU sed if you have it installed.
1114 On Solaris, changing your command search path to search /usr/xpg4/bin before
1115 /usr/bin should make the problem go away; on any platform on which you have
1116 this problem, installing GNU sed and changing your command path to search
1117 the directory in which it is installed before searching the directory with
1118 the version of sed that came with the OS should make the problem go away.
1120 Q 4.4: The link fails on Solaris because plugin_list is undefined.
1122 A: This appears to be due to a problem with some versions of the GTK+ and
1123 GLib packages from www.sunfreeware.org; un-install those packages, and try
1124 getting the 1.2.10 versions from that site, or the versions from The Written
1125 Word, or the versions from Sun's GNOME distribution, or the versions from
1126 the supplemental software CD that comes with the Solaris media kit, or build
1127 them from source from the GTK Web site. Then re-run the configuration
1128 script, and try rebuilding Ethereal. (If you get the 1.2.10 versions from
1129 www.sunfreeware.org, and the problem persists, un-install them and try
1130 installing one of the other versions mentioned.)
1132 Q 4.5: The build fails on Windows because of conflicts between winsock.h and
1135 A: As of Ethereal 0.9.5, you must install WinPcap 2.3 or later, and the
1136 corresponding version of the developer's pack, in order to be able to
1137 compile Ethereal; it will not compile with older versions of the developer's
1138 pack. The symptoms of this failure are conflicts between definitions in
1139 winsock.h and in winsock2.h; Ethereal uses winsock2.h, but pre-2.3 versions
1140 of the WinPcap developer's packet use winsock.h. (2.3 uses winsock2.h, so if
1141 Ethereal were to use winsock.h, it would not be able to build with current
1142 versions of the WinPcap developer's pack.)
1144 Note that the installed version of the developer's pack should be the same
1145 version as the version of WinPcap you have installed.
1149 Q 5.1: When I use Ethereal to capture packets, I see only packets to and
1150 from my machine, or I'm not seeing all the traffic I'm expecting to see from
1151 or to the machine I'm trying to monitor.
1153 A: This might be because the interface on which you're capturing is plugged
1154 into an Ethernet or Token Ring switch; on a switched network, unicast
1155 traffic between two ports will not necessarily appear on other ports - only
1156 broadcast and multicast traffic will be sent to all ports.
1158 Note that even if your machine is plugged into a hub, the "hub" may be a
1159 switched hub, in which case you're still on a switched network.
1161 Note also that on the Linksys Web site, they say that their auto-sensing
1162 hubs "broadcast the 10Mb packets to the port that operate at 10Mb only and
1163 broadcast the 100Mb packets to the ports that operate at 100Mb only", which
1164 would indicate that if you sniff on a 10Mb port, you will not see traffic
1165 coming sent to a 100Mb port, and vice versa. This problem has also been
1166 reported for Netgear dual-speed hubs, and may exist for other "auto-sensing"
1167 or "dual-speed" hubs.
1169 Some switches have the ability to replicate all traffic on all ports to a
1170 single port so that you can plug your analyzer into that single port to
1171 sniff all traffic. You would have to check the documentation for the switch
1172 to see if this is possible and, if so, to see how to do this. See the switch
1173 reference page on the Ethereal Wiki for information on some switches. (Note
1174 that it's a Wiki, so you can update or fix that information, or add
1175 additional information on those switches or information on new switches,
1178 Note also that many firewall/NAT boxes have a switch built into them; this
1179 includes many of the "cable/DSL router" boxes. If you have a box of that
1180 sort, that has a switch with some number of Ethernet ports into which you
1181 plug machines on your network, and another Ethernet port used to connect to
1182 a cable or DSL modem, you can, at least, sniff traffic between the machines
1183 on your network and the Internet by plugging the Ethernet port on the router
1184 going to the modem, the Ethernet port on the modem, and the machine on which
1185 you're running Ethereal into a hub (make sure it's not a switching hub, and
1186 that, if it's a dual-speed hub, all three of those ports are running at the
1189 If your machine is not plugged into a switched network or a dual-speed hub,
1190 or it is plugged into a switched network but the port is set up to have all
1191 traffic replicated to it, the problem might be that the network interface on
1192 which you're capturing doesn't support "promiscuous" mode, or because your
1193 OS can't put the interface into promiscuous mode. Normally, network
1194 interfaces supply to the host only:
1195 * packets sent to one of that host's link-layer addresses;
1196 * broadcast packets;
1197 * multicast packets sent to a multicast address that the host has
1198 configured the interface to accept.
1200 Most network interfaces can also be put in "promiscuous" mode, in which they
1201 supply to the host all network packets they see. Ethereal will try to put
1202 the interface on which it's capturing into promiscuous mode unless the
1203 "Capture packets in promiscuous mode" option is turned off in the "Capture
1204 Options" dialog box, and Tethereal will try to put the interface on which
1205 it's capturing into promiscuous mode unless the -p option was specified.
1206 However, some network interfaces don't support promiscuous mode, and some
1207 OSes might not allow interfaces to be put into promiscuous mode.
1209 If the interface is not running in promiscuous mode, it won't see any
1210 traffic that isn't intended to be seen by your machine. It will see
1211 broadcast packets, and multicast packets sent to a multicast MAC address the
1212 interface is set up to receive.
1214 You should ask the vendor of your network interface whether it supports
1215 promiscuous mode. If it does, you should ask whoever supplied the driver for
1216 the interface (the vendor, or the supplier of the OS you're running on your
1217 machine) whether it supports promiscuous mode with that network interface.
1219 In the case of token ring interfaces, the drivers for some of them, on
1220 Windows, may require you to enable promiscuous mode in order to capture in
1221 promiscuous mode. See the Ethereal Wiki item on Token Ring capturing for
1224 In the case of wireless LAN interfaces, it appears that, when those
1225 interfaces are promiscuously sniffing, they're running in a significantly
1226 different mode from the mode that they run in when they're just acting as
1227 network interfaces (to the extent that it would be a significant effor for
1228 those drivers to support for promiscuously sniffing and acting as regular
1229 network interfaces at the same time), so it may be that Windows drivers for
1230 those interfaces don't support promiscuous mode.
1232 Q 5.2: I can't see any TCP packets other than packets to and from my
1233 machine, even though another analyzer on the network sees those packets.
1235 A: You're probably not seeing any packets other than unicast packets to or
1236 from your machine, and broadcast and multicast packets; a switch will
1237 normally send to a port only unicast traffic sent to the MAC address for the
1238 interface on that port, and broadcast and multicast traffic - it won't send
1239 to that port unicast traffic sent to a MAC address for some other interface
1240 - and a network interface not in promiscuous mode will receive only unicast
1241 traffic sent to the MAC address for that interface, broadcast traffic, and
1242 multicast traffic sent to a multicast MAC address the interface is set up to
1245 TCP doesn't use broadcast or multicast, so you will only see your own TCP
1246 traffic, but UDP services may use broadcast or multicast so you'll see some
1247 UDP traffic - however, this is not a problem with TCP traffic, it's a
1248 problem with unicast traffic, as you also won't see all UDP traffic between
1251 I.e., this is probably the same question as this earlier one; see the
1252 response to that question.
1254 Q 5.3: I'm only seeing ARP packets when I try to capture traffic.
1256 A: You're probably on a switched network, and running Ethereal on a machine
1257 that's not sending traffic to the switch and not being sent any traffic from
1258 other machines on the switch. ARP packets are often broadcast packets, which
1259 are sent to all switch ports.
1261 I.e., this is probably the same question as this earlier one; see the
1262 response to that question.
1264 Q 5.4: I'm running Ethereal on Windows; why does some network interface on
1265 my machine not show up in the list of interfaces in the "Interface:" field
1266 in the dialog box popped up by "Capture->Start", and/or why does Ethereal
1267 give me an error if I try to capture on that interface?
1269 A: If you are running Ethereal on Windows NT 4.0, Windows 2000, Windows XP,
1270 or Windows Server 2003, and this is the first time you have run a
1271 WinPcap-based program (such as Ethereal, or Tethereal, or WinDump, or
1272 Analyzer, or...) since the machine was rebooted, you need to run that
1273 program from an account with administrator privileges; once you have run
1274 such a program, you will not need administrator privileges to run any such
1275 programs until you reboot.
1277 If you are running on Windows 95/98/Me, or if you are running on Windows NT
1278 4.0/Windows 2000/Windows XP/Windows Server 2003 and have administrator
1279 privileges or a WinPcap-based program has been run with those privileges
1280 since the machine rebooted, this problem might clear up if you completely
1281 un-install WinPcap and then re-install it.
1283 If that doesn't work, then note that Ethereal relies on the WinPcap library,
1284 on the WinPcap device driver, and on the facilities that come with the OS on
1285 which it's running in order to do captures.
1287 Therefore, if the OS, the WinPcap library, or the WinPcap driver don't
1288 support capturing on a particular network interface device, Ethereal won't
1289 be able to capture on that device.
1292 1. 2.02 and earlier versions of the WinPcap driver and library that
1293 Ethereal uses for packet capture didn't support Token Ring interfaces;
1294 versions 2.1 and later support Token Ring, and the current version of
1295 Ethereal works with (and, in fact, requires) WinPcap 2.1 or later.
1296 If you are having problems capturing on Token Ring interfaces, and you
1297 have WinPcap 2.02 or an earlier version of WinPcap installed, you should
1298 uninstall WinPcap, download and install the current version of WinPcap,
1299 and then install the latest version of Ethereal.
1300 2. On Windows 95, 98, or Me, sometimes more than one interface will be
1301 given the same name; if that is the case, you will only be able to
1302 capture on one of those interfaces - it's not clear to which one the
1303 name, when used in a WinPcap-based application, will refer. For example,
1304 if you have a PPP serial interface and a VPN interface, they might show
1305 up with the same name, for example "ppp-mac", and if you try to capture
1306 on "ppp-mac", it might not capture on the interface you're currently
1307 using. In that case, you might, for example, have to remove the VPN
1308 interface from the system in order to capture on the PPP serial
1310 3. WinPcap 2.3 has problems supporting PPP WAN interfaces on Windows NT
1311 4.0, Windows 2000, Windows XP, and Windows Server 2003, and, to avoid
1312 those problems, support for PPP WAN interfaces on those versions of
1313 Windows has been disabled in WinPcap 3.0. Regular dial-up lines, ISDN
1314 lines, ADSL connections using PPPoE or PPPoA, and various other lines
1315 such as T1/E1 lines are all PPP interfaces, so those interfaces might
1316 not show up on the list of interfaces in the "Capture Options" dialog on
1318 On Windows 2000 and later, installing the beta version of WinPcap 3.1
1319 might help, although, as it's a beta version, that might cause some
1320 other problems that don't occur with older versions of WinPcap; you
1321 should report those problems to the WinPcap developers, so that they can
1322 try to fix those problems before the final version of WinPcap 3.1 is
1323 released. WinPcap 3.1 will not support PPP captures on Windows NT 4.0.
1324 See the Ethereal Wiki item on PPP capturing for details.
1325 4. WinPcap prior to 3.0 does not support multiprocessor machines (note that
1326 machines with a single multi-threaded processor, such as Intel's new
1327 multi-threaded x86 processors, are multiprocessor machines as far as the
1328 OS and WinPcap are concerned), and recent 2.x versions of WinPcap refuse
1329 to operate if they detect that they're running on a multiprocessor
1330 machine, which means that they may not show any network interfaces. You
1331 will need to use WinPcap 3.0 to capture on a multiprocessor machine.
1333 If an interface doesn't show up in the list of interfaces in the
1334 "Interface:" field, and you know the name of the interface, try entering
1335 that name in the "Interface:" field and capturing on that device.
1337 If the attempt to capture on it succeeds, the interface is somehow not being
1338 reported by the mechanism Ethereal uses to get a list of interfaces. Try
1339 listing the interfaces with WinDump; see the WinDump Web site or the local
1340 mirror of the WinDump Web site for information on using WinDump.
1342 You would run WinDump with the -D flag; if it lists the interface, please
1343 report this to ethereal-dev@ethereal.com giving full details of the problem,
1345 * the operating system you're using, and the version of that operating
1347 * the type of network device you're using;
1348 * the output of WinDump.
1350 If WinDump does not list the interface, this is almost certainly a problem
1351 with one or more of:
1352 * the operating system you're using;
1353 * the device driver for the interface you're using;
1354 * the WinPcap library and/or the WinPcap device driver;
1356 so first check the WinPcap FAQ, the local mirror of that FAQ, or the
1357 Wiretapped.net mirror of that FAQ, to see if your problem is mentioned
1358 there. If not, then see the WinPcap support page (or the local mirror of
1359 that page) - check the "Submitting bugs" section.
1361 If you are having trouble capturing on a particular network interface, first
1362 try capturing on that device with WinDump; see the WinDump Web site or the
1363 local mirror of the WinDump Web site for information on using WinDump.
1365 If you can capture on the interface with WinDump, send mail to
1366 ethereal-users@ethereal.com giving full details of the problem, including
1367 * the operating system you're using, and the version of that operating
1369 * the type of network device you're using;
1370 * the error message you get from Ethereal.
1372 If you cannot capture on the interface with WinDump, this is almost
1373 certainly a problem 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 You may also want to ask the ethereal-users@ethereal.com and the
1384 winpcap-users@winpcap.org mailing lists to see if anybody happens to know
1385 about the problem and know a workaround or fix for the problem. (Note that
1386 you will have to subscribe to that list in order to be allowed to mail to
1387 it; see the WinPcap support page, or the local mirror of that page, for
1388 information on the mailing list.) In your mail, please give full details of
1389 the problem, as described above, and also indicate that the problem occurs
1390 with WinDump, not just with Ethereal.
1392 Q 5.5: I'm running Ethereal on Windows; why do no network interfaces show up
1393 in the list of interfaces in the "Interface:" field in the dialog box popped
1394 up by "Capture->Start"?
1396 A: This is really the same question as the previous one; see the response to
1399 Q 5.6: I'm running Ethereal on Windows; why doesn't my serial port/ADSL
1400 modem/ISDN modem show up in the list of interfaces in the "Interface:" field
1401 in the dialog box popped up by "Capture->Start"?
1403 A: Internet access on those devices is often done with the Point-to-Point
1404 (PPP) protocol; WinPcap 2.3 has problems supporting PPP WAN interfaces on
1405 Windows NT 4.0, Windows 2000, Windows XP, and Windows Server 2003, and, to
1406 avoid those problems, support for PPP WAN interfaces on those versions of
1407 Windows has been disabled in WinPcap 3.0.
1409 On Windows 2000 and later, installing the beta version of WinPcap 3.1 might
1410 help, although, as it's a beta version, that might cause some other problems
1411 that don't occur with older versions of WinPcap; you should report those
1412 problems to the WinPcap developers, so that they can try to fix those
1413 problems before the final version of WinPcap 3.1 is released. WinPcap 3.1
1414 will not support PPP captures on Windows NT 4.0. See the Ethereal Wiki item
1415 on PPP capturing for details.
1417 Q 5.7: I'm running Ethereal on a UNIX-flavored OS; why does some network
1418 interface on my machine not show up in the list of interfaces in the
1419 "Interface:" field in the dialog box popped up by "Capture->Start", and/or
1420 why does Ethereal give me an error if I try to capture on that interface?
1422 A: You may need to run Ethereal from an account with sufficient privileges
1423 to capture packets, such as the super-user account, or may need to give your
1424 account sufficient privileges to capture packets. Only those interfaces that
1425 Ethereal can open for capturing show up in that list; if you don't have
1426 sufficient privileges to capture on any interfaces, no interfaces will show
1427 up in the list. See the Ethereal Wiki item on capture privileges for details
1428 on how to give a particular account or account group capture privileges on
1429 platforms where that can be done.
1431 If you are running Ethereal from an account with sufficient privileges, then
1432 note that Ethereal relies on the libpcap library, and on the facilities that
1433 come with the OS on which it's running in order to do captures. On some
1434 OSes, those facilities aren't present by default; see the Ethereal Wiki item
1435 on adding capture support for details.
1437 And, even if you're running with an account that has sufficient privileges
1438 to capture, and capture support is present in your OS, if the OS or the
1439 libpcap library don't support capturing on a particular network interface
1440 device or particular types of devices, Ethereal won't be able to capture on
1443 On Solaris, note that libpcap 0.6.2 and earlier didn't support Token Ring
1444 interfaces; the current version, 0.7.2, does support Token Ring, and the
1445 current version of Ethereal works with libcap 0.7.2 and later.
1447 If an interface doesn't show up in the list of interfaces in the
1448 "Interface:" field, and you know the name of the interface, try entering
1449 that name in the "Interface:" field and capturing on that device.
1451 If the attempt to capture on it succeeds, the interface is somehow not being
1452 reported by the mechanism Ethereal uses to get a list of interfaces; please
1453 report this to ethereal-dev@ethereal.com giving full details of the problem,
1455 * the operating system you're using, and the version of that operating
1456 system (for Linux, give both the version number of the kernel and the
1457 name and version number of the distribution you're using);
1458 * the type of network device you're using.
1460 If you are having trouble capturing on a particular network interface, and
1461 you've made sure that (on platforms that require it) you've arranged that
1462 packet capture support is present, as per the above, first try capturing on
1463 that device with tcpdump.
1465 If you can capture on the interface with tcpdump, send mail to
1466 ethereal-users@ethereal.com giving full details of the problem, including
1467 * the operating system you're using, and the version of that operating
1468 system (for Linux, give both the version number of the kernel and the
1469 name and version number of the distribution you're using);
1470 * the type of network device you're using;
1471 * the error message you get from Ethereal.
1473 If you cannot capture on the interface with tcpdump, this is almost
1474 certainly a problem with one or more of:
1475 * the operating system you're using;
1476 * the device driver for the interface you're using;
1477 * the libpcap library;
1479 so you should report the problem to the company or organization that
1480 produces the OS (in the case of a Linux distribution, report the problem to
1481 whoever produces the distribution).
1483 You may also want to ask the ethereal-users@ethereal.com and the
1484 tcpdump-workers@tcpdump.org mailing lists to see if anybody happens to know
1485 about the problem and know a workaround or fix for the problem. In your
1486 mail, please give full details of the problem, as described above, and also
1487 indicate that the problem occurs with tcpdump not just with Ethereal.
1489 Q 5.8: I'm running Ethereal on a UNIX-flavored OS; why do no network
1490 interfaces show up in the list of interfaces in the "Interface:" field in
1491 the dialog box popped up by "Capture->Start"?
1493 A: This is really the same question as the previous one; see the response to
1496 Q 5.9: Can Ethereal capture on (my T1/E1 line, SS7 links, etc.)?
1498 A: Ethereal can only capture on devices supported by libpcap/WinPcap. On
1499 most OSes, only devices that can act as network interfaces of the type that
1500 support IP are supported as capture devices for libpcap/WinPcap, although
1501 the device doesn't necessarily have to be running as an IP interface in
1502 order to support traffic capture.
1504 On Linux and FreeBSD, libpcap 0.8 and later support the API for Endace
1505 Measurement Systems' DAG cards, so that a system with one of those cards,
1506 and its driver and libraries, installed can capture traffic with those cards
1507 with libpcap-based applications. You would either have to have a version of
1508 Ethereal built with that version of libpcap, or a dynamically-linked version
1509 of Ethereal and a shared libpcap library with DAG support, in order to do so
1510 with Ethereal. You should ask Endace whether that could be used to capture
1511 traffic on, for example, your T1/E1 link.
1512 There is currently no hardware to support capturing on SS7 links with
1513 libpcap. (Note that the fact that Ethereal includes dissectors for many SS7
1514 protocols doesn't imply that it can capture traffic from SS7 links; those
1515 protocols can be run over Internet protocols.)
1517 Q 5.10: How do I put an interface into promiscuous mode?
1519 A: By not disabling promiscuous mode when running Ethereal or Tethereal.
1521 Note, however, that:
1522 * the form of promiscuous mode that libpcap (the library that programs
1523 such as tcpdump, Ethereal, etc. use to do packet capture) turns on will
1524 not necessarily be shown if you run ifconfig on the interface on a UNIX
1526 * some network interfaces might not support promiscuous mode, and some
1527 drivers might not allow promiscuous mode to be turned on - see this
1528 earlier question for more information on that;
1529 * the fact that you're not seeing any traffic, or are only seeing
1530 broadcast traffic, or aren't seeing any non-broadcast traffic other than
1531 traffic to or from the machine running Ethereal, does not mean that
1532 promiscuous mode isn't on - see this earlier question for more
1533 information on that.
1535 I.e., this is probably the same question as this earlier one; see the
1536 response to that question.
1538 Q 5.11: I can set a display filter just fine, but capture filters don't
1541 A: Capture filters currently use a different syntax than display filters.
1542 Here's the corresponding section from the ethereal(1) man page:
1544 "Display filters in Ethereal are very powerful; more fields are filterable
1545 in Ethereal than in other protocol analyzers, and the syntax you can use to
1546 create your filters is richer. As Ethereal progresses, expect more and more
1547 protocol fields to be allowed in display filters.
1549 Packet capturing is performed with the pcap library. The capture filter
1550 syntax follows the rules of the pcap library. This syntax is different from
1551 the display filter syntax."
1553 The capture filter syntax used by libpcap can be found in the tcpdump(8) man
1556 Q 5.12: I'm entering valid capture filters, but I still get "parse error"
1559 A: There is a bug in some versions of libpcap/WinPcap that cause it to
1560 report parse errors even for valid expressions if a previous filter
1561 expression was invalid and got a parse error.
1563 Try exiting and restarting Ethereal; if you are using a version of
1564 libpcap/WinPcap with this bug, this will "erase" its memory of the previous
1565 parse error. If the capture filter that got the "parse error" now works, the
1566 earlier error with that filter was probably due to this bug.
1568 The bug was fixed in libpcap 0.6; 0.4[.x] and 0.5[.x] versions of libpcap
1569 have this bug, but 0.6[.x] and later versions don't.
1571 Versions of WinPcap prior to 2.3 are based on pre-0.6 versions of libpcap,
1572 and have this bug; WinPcap 2.3 is based on libpcap 0.6.2, and doesn't have
1575 If you are running Ethereal on a UNIX-flavored platform, run "ethereal -v",
1576 or select "About Ethereal..." from the "Help" menu in Ethereal, to see what
1577 version of libpcap it's using. If it's not 0.6 or later, you will need
1578 either to upgrade your OS to get a later version of libpcap, or will need to
1579 build and install a later version of libpcap from the tcpdump.org Web site
1580 and then recompile Ethereal from source with that later version of libpcap.
1582 If you are running Ethereal on Windows with a pre-2.3 version of WinPcap,
1583 you will need to un-install WinPcap and then download and install WinPcap
1586 Q 5.13: I saved a filter and tried to use its name to filter the display,
1587 but I got an "Unexpected end of filter string" error.
1589 A: You cannot use the name of a saved display filter as a filter. To filter
1590 the display, you can enter a display filter expression - not the name of a
1591 saved display filter - in the "Filter:" box at the bottom of the display,
1592 and type the key or press the "Apply" button (that does not require you to
1593 have a saved filter), or, if you want to use a saved filter, you can press
1594 the "Filter:" button, select the filter in the dialog box that pops up, and
1595 press the "OK" button.
1597 Q 5.14: Why am I seeing lots of packets with incorrect TCP checksums?
1599 A: If the packets that have incorrect TCP checksums are all being sent by
1600 the machine on which Ethereal is running, this is probably because the
1601 network interface on which you're capturing does TCP checksum offloading.
1602 That means that the TCP checksum is added to the packet by the network
1603 interface, not by the OS's TCP/IP stack; when capturing on an interface,
1604 packets being sent by the host on which you're capturing are directly handed
1605 to the capture interface by the OS, which means that they are handed to the
1606 capture interface without a TCP checksum being added to them.
1608 The only way to prevent this from happening would be to disable TCP checksum
1610 1. that might not even be possible on some OSes;
1611 2. that could reduce networking performance significantly.
1613 However, you can disable the check that Ethereal does of the TCP checksum,
1614 so that it won't report any packets as having TCP checksum errors, and so
1615 that it won't refuse to do TCP reassembly due to a packet having an
1616 incorrect TCP checksum. That can be set as an Ethereal preference by
1617 selecting "Preferences" from the "Edit" menu, opening up the "Protocols"
1618 list in the left-hand pane of the "Preferences" dialog box, selecting "TCP",
1619 from that list, turning off the "Check the validity of the TCP checksum when
1620 possible" option, clicking "Save" if you want to save that setting in your
1621 preference file, and clicking "OK".
1623 It can also be set on the Ethereal or Tethereal command line with a -o
1624 tcp.check_checksum:false command-line flag, or manually set in your
1625 preferences file by adding a tcp.check_checksum:false line.
1627 Q 5.15: I've just installed Ethereal, and the traffic on my local LAN is
1630 A: We have a collection of strange and exotic sample capture files at
1631 http://wiki.ethereal.com/SampleCaptures
1633 Q 5.16: When I run Ethereal on Solaris 8, it dies with a Bus Error when I
1636 A: Some versions of the GTK+ library from www.sunfreeware.org appear to be
1637 buggy, causing Ethereal to drop core with a Bus Error. Un-install those
1638 packages, and try getting the 1.2.10 version from that site, or the version
1639 from The Written Word, or the version from Sun's GNOME distribution, or the
1640 version from the supplemental software CD that comes with the Solaris media
1641 kit, or build it from source from the GTK Web site. Update the GLib library
1642 to the 1.2.10 version, from the same source, as well. (If you get the 1.2.10
1643 versions from www.sunfreeware.org, and the problem persists, un-install them
1644 and try installing one of the other versions mentioned.)
1646 Similar problems may exist with older versions of GTK+ for earlier versions
1649 Q 5.17: When I run Ethereal, I get an error
1651 Gtk-CRITICAL **: file gtkwindow.c: line 3107 (gtk_window_resize):
1652 assertion `height > 0' failed.
1654 A: This is a bug in Ethereal 0.10.5 and 0.10.5a, which is fixed in Ethereal
1655 0.10.6 and later releases.
1657 Q 5.18: When I run Tethereal with the "-x" option, it crashes with an error
1659 "** ERROR **: file print.c: line 691 (print_line): should not be reached.
1661 A: This is a bug in Ethereal 0.10.0a, which is fixed in 0.10.1 and later
1662 releases. To work around the bug, don't use "-x" unless you're also using
1663 "-V"; note that "-V" produces a full dissection of each packet, so you might
1666 Q 5.19: When I run Ethereal on Windows NT, it dies with a Dr. Watson error,
1667 reporting an "Integer division by zero" exception, when I start it.
1669 A: In at least some case, this appears to be due to using the default VGA
1670 driver; if that's not the correct driver for your video card, try running
1671 the correct driver for your video card.
1673 Q 5.20: When I try to run Ethereal, it complains about sprint_realloc_objid
1676 A: Ethereal can only be linked with version 4.2.2 or later of UCD SNMP. Your
1677 version of Ethereal was dynamically linked with such a version of UCD SNMP;
1678 however, you have an older version of UCD SNMP installed, which means that
1679 when Ethereal is run, it tries to link to the older version, and fails. You
1680 will have to replace that version of UCD SNMP with version 4.2.2 or a later
1683 Q 5.21: I'm running Ethereal on Linux; why do my time stamps have only 100ms
1684 resolution, rather than 1us resolution?
1686 A: Ethereal gets time stamps from libpcap/WinPcap, and libpcap/WinPcap get
1687 them from the OS kernel, so Ethereal - and any other program using libpcap,
1688 such as tcpdump - is at the mercy of the time stamping code in the OS for
1691 At least on x86-based machines, Linux can get high-resolution time stamps on
1692 newer processors with the Time Stamp Counter (TSC) register; for example,
1693 Intel x86 processors, starting with the Pentium Pro, and including all x86
1694 processors since then, have had a TSC, and other vendors probably added the
1695 TSC at some point to their families of x86 processors.
1697 The Linux kernel must be configured with the CONFIG_X86_TSC option enabled
1698 in order to use the TSC. Make sure this option is enabled in your kernel.
1700 In addition, some Linux distributions may have bugs in their versions of the
1701 kernel that cause packets not to be given high-resolution time stamps even
1702 if the TSC is enabled. See, for example, bug 61111 for Red Hat Linux 7.2. If
1703 your distribution has a bug such as this, you may have to run a standard
1704 kernel from kernel.org in order to get high-resolution time stamps.
1706 Q 5.22: I'm capturing packets on {Windows 95, Windows 98, Windows Me}; why
1707 are the time stamps on packets wrong?
1709 A: This is due to a bug in WinPcap. The bug should be fixed in WinPcap 3.0.
1711 Q 5.23: When I try to run Ethereal on Windows, it fails to run because it
1712 can't find packet.dll.
1714 A: In older versions of Ethereal, there were two binary distributions
1715 available for Windows, one that supported capturing packets, and one that
1716 didn't. The version that supported capturing packets required that you
1717 install the WinPcap driver; if you didn't install it, it would fail to run
1718 because it couldn't find packet.dll.
1720 The current version of Ethereal has only one binary distribution for
1721 Windows; that version will check whether WinPcap is installed and, if it's
1722 not, will disable support for packet capture.
1724 The WinPcap driver and libraries can be downloaded from the WinPcap Web
1725 site, the local mirror of the WinPcap Web site, or the Wiretapped.net mirror
1726 of the WinPcap site.
1728 Q 5.24: I'm running Ethereal on Windows NT 4.0/Windows 2000/Windows
1729 XP/Windows Server 2003; my machine has a PPP (dial-up POTS, ISDN, etc.)
1730 interface, and it shows up in the "Interface" item in the "Capture Options"
1731 dialog box. Why can no packets be sent on or received from that network
1732 while I'm trying to capture traffic on that interface?
1734 A: Some versions of WinPcap have problems with PPP WAN interfaces on Windows
1735 NT 4.0, Windows 2000, Windows XP, and Windows Server 2003; one symptom that
1736 may be seen is that attempts to capture in promiscuous mode on the interface
1737 cause the interface to be incapable of sending or receiving packets. You can
1738 disable promiscuous mode using the -p command-line flag or the item in the
1739 "Capture Preferences" dialog box, but this may mean that outgoing packets,
1740 or incoming packets, won't be seen in the capture.
1742 On Windows 2000 and later, installing the beta version of WinPcap 3.1 might
1743 help, although, as it's a beta version, that might cause some other problems
1744 that don't occur with older versions of WinPcap; you should report those
1745 problems to the WinPcap developers, so that they can try to fix those
1746 problems before the final version of WinPcap 3.1 is released. WinPcap 3.1
1747 will not support PPP captures on Windows NT 4.0. See the Ethereal Wiki item
1748 on PPP capturing for details.
1750 Q 5.25: I'm running Ethereal on Windows 95/98/Me, on a machine with more
1751 than one network adapter of the same type; Ethereal shows all of those
1752 adapters with the same name, but I can't use any of those adapters other
1755 A: Unfortunately, Windows 95/98/Me gives the same name to multiple instances
1756 of the type of same network adapter. Therefore, WinPcap cannot distinguish
1757 between them, so a WinPcap-based application can capture only on the first
1758 such interface; Ethereal is a libpcap/WinPcap-based application.
1760 Q 5.26: I'm running Ethereal on Windows, and I'm not seeing any traffic
1761 being sent by the machine running Ethereal.
1763 A: If you are running some form of VPN client software, it might be causing
1764 this problem; people have seen this problem when they have Check Point's VPN
1765 software installed on their machine. If that's the cause of the problem, you
1766 will have to remove the VPN software in order to have Ethereal (or any other
1767 application using WinPcap) see outgoing packets; unfortunately, neither we
1768 nor the WinPcap developers know any way to make WinPcap and the VPN software
1771 Also, some drivers for Windows (especially some wireless network interface
1772 drivers) apparently do not, when running in promiscuous mode, arrange that
1773 outgoing packets are delivered to the software that requested that the
1774 interface run promiscuously; try turning promiscuous mode off.
1776 Q 5.27: I'm trying to capture traffic but I'm not seeing any.
1778 A: Is the machine running Ethereal sending out any traffic on the network
1779 interface on which you're capturing, or receiving any traffic on that
1780 network, or is there any broadcast traffic on the network or multicast
1781 traffic to a multicast group to which the machine running Ethereal belongs?
1783 If not, this may just be a problem with promiscuous sniffing, either due to
1784 running on a switched network or a dual-speed hub, or due to problems with
1785 the interface not supporting promiscuous mode; see the response to this
1788 Otherwise, on Windows, see the response to this question and, on a
1789 UNIX-flavored OS, see the response to this question.
1791 Q 5.28: I have an XXX network card on my machine; if I try to capture on it,
1792 my machine crashes or resets itself.
1794 A: This is almost certainly a problem with one or more of:
1795 * the operating system you're using;
1796 * the device driver for the interface you're using;
1797 * the libpcap/WinPcap library and, if this is Windows, the WinPcap device
1801 * if you are using Windows, see the WinPcap support page (or the local
1802 mirror of that page) - check the "Submitting bugs" section;
1803 * if you are using some Linux distribution, some version of BSD, or some
1804 other UNIX-flavored OS, you should report the problem to the company or
1805 organization that produces the OS (in the case of a Linux distribution,
1806 report the problem to whoever produces the distribution).
1808 Q 5.29: My machine crashes or resets itself when I select "Start" from the
1809 "Capture" menu or select "Preferences" from the "Edit" menu.
1811 A: Both of those operations cause Ethereal to try to build a list of the
1812 interfaces that it can open; it does so by getting a list of interfaces and
1813 trying to open them. There is probably an OS, driver, or, for Windows,
1814 WinPcap bug that causes the system to crash when this happens; see the
1817 Q 5.30: Does Ethereal work on Windows Me?
1819 A: Yes, but if you want to capture packets, you will need to install the
1820 latest version of WinPcap, as 2.02 and earlier versions of WinPcap didn't
1821 support Windows Me. You should also install the latest version of Ethereal
1824 Q 5.31: Does Ethereal work on Windows XP?
1826 A: Yes, but if you want to capture packets, you will need to install the
1827 latest version of WinPcap, as 2.2 and earlier versions of WinPcap didn't
1830 Q 5.32: Why doesn't Ethereal correctly identify RTP packets? It shows them
1833 A: Ethereal can identify a UDP datagram as containing a packet of a
1834 particular protocol running atop UDP only if
1835 1. The protocol in question has a particular standard port number, and the
1836 UDP source or destination port number is that port
1837 2. Packets of that protocol can be identified by looking for a "signature"
1838 of some type in the packet - i.e., some data that, if Ethereal finds it
1839 in some particular part of a packet, means that the packet is almost
1840 certainly a packet of that type.
1841 3. Some other traffic earlier in the capture indicated that, for example,
1842 UDP traffic between two particular addresses and ports will be RTP
1845 RTP doesn't have a standard port number, so 1) doesn't work; it doesn't, as
1846 far as I know, have any "signature", so 2) doesn't work.
1848 That leaves 3). If there's RTSP traffic that sets up an RTP session, then,
1849 at least in some cases, the RTSP dissector will set things up so that
1850 subsequent RTP traffic will be identified. Currently, that's the only place
1851 we do that; there may be other places.
1853 However, there will always be places where Ethereal is simply incapable of
1854 deducing that a given UDP flow is RTP; a mechanism would be needed to allow
1855 the user to specify that a given conversation should be treated as RTP. As
1856 of Ethereal 0.8.16, such a mechanism exists; if you select a UDP or TCP
1857 packet, the right mouse button menu will have a "Decode As..." menu item,
1858 which will pop up a dialog box letting you specify that the source port, the
1859 destination port, or both the source and destination ports of the packet
1860 should be dissected as some particular protocol.
1862 Q 5.33: Why doesn't Ethereal show Yahoo Messenger packets in captures that
1863 contain Yahoo Messenger traffic?
1865 A: Ethereal only recognizes as Yahoo Messenger traffic packets to or from
1866 TCP port 3050 that begin with "YPNS", "YHOO", or "YMSG". TCP segments that
1867 start with the middle of a Yahoo Messenger packet that takes more than one
1868 TCP segment will not be recognized as Yahoo Messenger packets (even if the
1869 TCP segment also contains the beginning of another Yahoo Messenger packet).
1871 Q 5.34: Why do I get the error
1873 Gdk-ERROR **: Palettized display (256-colour) mode not supported on
1877 when I try to run Ethereal on Windows?
1879 A: Ethereal is built using the GTK+ toolkit, which supports most
1880 UNIX-flavored OSes, and also supports Windows.
1882 Windows versions of Ethereal before 0.9.14 were built with an older version
1883 of that toolkit, which didn't support 256-color mode on Windows - it
1884 required HiColor (16-bit colors) or more.
1886 Windows versions of Ethereal 0.9.14 and later are built with a version of
1887 that toolkit that supports 256-color mode; upgrade to the current version of
1888 Ethereal if you want to run on a display in 256-color mode.
1890 Q 5.35: When I capture on Windows in promiscuous mode, I can see packets
1891 other than those sent to or from my machine; however, those packets show up
1892 with a "Short Frame" indication, unlike packets to or from my machine. What
1893 should I do to arrange that I see those packets in their entirety?
1895 A: In at least some cases, this appears to be the result of PGPnet running
1896 on the network interface on which you're capturing; turn it off on that
1899 Q 5.36: I'm capturing packets on a machine on a VLAN; why don't the packets
1900 I'm capturing have VLAN tags?
1902 A: You might be capturing on what might be called a "VLAN interface" - the
1903 way a particular OS makes VLANs plug into the networking stack might, for
1904 example, be to have a network device object for the physical interface,
1905 which takes VLAN packets, strips off the VLAN header and constructs an
1906 Ethernet header, and passes that packet to an internal network device object
1907 for the VLAN, which then passes the packets onto various higher-level
1908 protocol implementations.
1910 In order to see the raw Ethernet packets, rather than "de-VLANized" packets,
1911 you would have to capture not on the virtual interface for the VLAN, but on
1912 the interface corresponding to the physical network device, if possible. See
1913 the Ethereal Wiki item on VLAN capturing for details.
1915 Q 5.37: How can I capture raw 802.11 frames, including non-data (management,
1918 A: That depends on the operating system on which you're running, and on the
1919 802.11 interface on which you're capturing.
1921 This would probably require that you capture in promiscuous mode or in the
1922 mode called "monitor mode" or "RFMON mode". On some platforms, or with some
1923 cards, this might require that you capture in monitor mode - promiscuous
1924 mode might not be sufficient. If you want to capture traffic on networks
1925 other than the one with which you're associated, you will have to capture in
1928 Not all operating systems support capturing non-data packets and, even on
1929 operating systems that do support it, not all drivers, and thus not all
1930 interfaces, support it. Even on those that do, monitor mode might not be
1931 supported by the operating system or by the drivers for all interfaces.
1933 NOTE: an interface running in monitor mode will, on most if not all
1934 platforms, not be able to act as a regular network interface; putting it
1935 into monitor mode will, in effect, take your machine off of whatever network
1936 it's on as long as the interface is in monitor mode, allowing it only to
1937 passively capture packets.
1939 This means that you should disable name resolution when capturing in monitor
1940 mode; otherwise, when Ethereal (or Tethereal, or tcpdump) tries to display
1941 IP addresses as host names, it will probably block for a long time trying to
1942 resolve the name because it will not be able to communicate with any DNS or
1945 See the Ethereal Wiki item on 802.11 capturing for details.
1947 Q 5.38: How do I capture on an 802.11 device in monitor mode?
1949 A: Whether you will be able to capture in monitor mode depends on the
1950 operating system, adapter, and driver you're using. See the previous
1951 question for information on monitor mode, including a link to the Ethereal
1952 Wiki page that gives details on 802.11 capturing.
1954 Q 5.39: I'm trying to capture 802.11 traffic on Windows; why am I not seeing
1957 A: At least some 802.11 card drivers on Windows appear not to see any
1958 packets if they're running in promiscuous mode. Try turning promiscuous mode
1959 off; you'll only be able to see packets sent by and received by your
1960 machine, not third-party traffic, and it'll look like Ethernet traffic and
1961 won't include any management or control frames, but that's a limitation of
1964 See MicroLogix's list of cards supported with WinPcap for information on
1965 support of various adapters and drivers with WinPcap.
1967 Q 5.40: I'm trying to capture 802.11 traffic on Windows; why am I seeing
1968 packets received by the machine on which I'm capturing traffic, but not
1969 packets sent by that machine?
1971 A: This appears to be another problem with promiscuous mode; try turning it
1974 Q 5.41: How can I capture packets with CRC errors?
1976 A: Ethereal can capture only the packets that the packet capture library -
1977 libpcap on UNIX-flavored OSes, and the WinPcap port to Windows of libpcap on
1978 Windows - can capture, and libpcap/WinPcap can capture only the packets that
1979 the OS's raw packet capture mechanism (or the WinPcap driver, and the
1980 underlying OS networking code and network interface drivers, on Windows)
1981 will allow it to capture.
1983 Unless the OS always supplies packets with errors such as invalid CRCs to
1984 the raw packet capture mechanism, or can be configured to do so, invalid
1985 CRCs to the raw packet capture mechanism, Ethereal - and other programs that
1986 capture raw packets, such as tcpdump - cannot capture those packets. You
1987 will have to determine whether your OS needs to be so configured and, if so,
1988 can be so configured, configure it if necessary and possible, and make
1989 whatever changes to libpcap and the packet capture program you're using are
1990 necessary, if any, to support capturing those packets.
1992 Most OSes probably do not support capturing packets with invalid CRCs on
1993 Ethernet, and probably do not support it on most other link-layer types.
1994 Some drivers on some OSes do support it, such as some Ethernet drivers on
1995 FreeBSD; in those OSes, you might always get those packets, or you might
1996 only get them if you capture in promiscuous mode (you'd have to determine
1999 Note that libpcap does not currently supply to programs that use it an
2000 indication of whether the packet's CRC was invalid (because the drivers
2001 themselves do not supply that information to the raw packet capture
2002 mechanism); therefore, Ethereal will not indicate which packets had CRC
2003 errors unless the FCS was captured (see the next question) and you're using
2004 Ethereal 0.9.15 and later, in which case Ethereal will check the CRC and
2005 indicate whether it's correct or not.
2007 Q 5.42: How can I capture entire frames, including the FCS?
2009 A: Ethereal can only capture data that the packet capture library - libpcap
2010 on UNIX-flavored OSes, and the WinPcap port to Windows of libpcap on Windows
2011 - can capture, and libpcap/WinPcap can capture only the data that the OS's
2012 raw packet capture mechanism (or the WinPcap driver, and the underlying OS
2013 networking code and network interface drivers, on Windows) will allow it to
2016 For any particular link-layer network type, unless the OS supplies the FCS
2017 of a frame as part of the frame, or can be configured to do so, Ethereal -
2018 and other programs that capture raw packets, such as tcpdump - cannot
2019 capture the FCS of a frame. You will have to determine whether your OS needs
2020 to be so configured and, if so, can be so configured, configure it if
2021 necessary and possible, and make whatever changes to libpcap and the packet
2022 capture program you're using are necessary, if any, to support capturing the
2025 Most OSes do not support capturing the FCS of a frame on Ethernet, and
2026 probably do not support it on most other link-layer types. Some drivres on
2027 some OSes do support it, such as some (all?) Ethernet drivers on NetBSD and
2028 possibly the driver for Apple's gigabit Ethernet interface in Mac OS X; in
2029 those OSes, you might always get the FCS, or you might only get the FCS if
2030 you capture in promiscuous mode (you'd have to determine which is the case).
2032 Versions of Ethereal prior to 0.9.15 will not treat an Ethernet FCS in a
2033 captured packet as an FCS. 0.9.15 and later will attempt to determine
2034 whether there's an FCS at the end of the frame and, if it thinks there is,
2035 will display it as such, and will check whether it's the correct CRC-32
2038 Q 5.43: Why does Ethereal hang after I stop a capture?
2040 A: The most likely reason for this is that Ethereal is trying to look up an
2041 IP address in the capture to convert it to a name (so that, for example, it
2042 can display the name in the source address or destination address columns),
2043 and that lookup process is taking a very long time.
2045 Ethereal calls a routine in the OS of the machine on which it's running to
2046 convert of IP addresses to the corresponding names. That routine probably
2047 does one or more of:
2048 * a search of a system file listing IP addresses and names;
2049 * a lookup using DNS;
2050 * on UNIX systems, a lookup using NIS;
2051 * on Windows systems, a NetBIOS-over-TCP query.
2053 If a DNS server that's used in an address lookup is not responding, the
2054 lookup will fail, but will only fail after a timeout while the system
2055 routine waits for a reply.
2057 In addition, on Windows systems, if the DNS lookup of the address fails,
2058 either because the server isn't responding or because there are no records
2059 in the DNS that could be used to map the address to a name, a
2060 NetBIOS-over-TCP query will be made. That query involves sending a message
2061 to the NetBIOS-over-TCP name service on that machine, asking for the name
2062 and other information about the machine. If the machine isn't running
2063 software that responds to those queries - for example, many non-Windows
2064 machines wouldn't be running that software - the lookup will only fail after
2065 a timeout. Those timeouts can cause the lookup to take a long time.
2067 If you disable network address-to-name translation - for example, by turning
2068 off the "Enable network name resolution" option in the "Capture Options"
2069 dialog box for starting a network capture - the lookups of the address won't
2070 be done, which may speed up the process of reading the capture file after
2071 the capture is stopped. You can make that setting the default by selecting
2072 "Preferences" from the "Edit" menu, turning off the "Enable network name
2073 resolution" option in the "Name resolution" options in the preferences
2074 disalog box, and using the "Save" button in that dialog box; note that this
2075 will save all your current preference settings.
2077 If Ethereal hangs when reading a capture even with network name resolution
2078 turned off, there might, for example, be a bug in one of Ethereal's
2079 dissectors for a protocol causing it to loop infinitely. If you're not
2080 running the most recent release of Ethereal, you should first upgrade to
2081 that release, as, if there's a bug of that sort, it might've been fixed in a
2082 release after the one you're running. If the hang occurs in the most recent
2083 release of Ethereal, the bug should be reported to the Ethereal developers'
2084 mailing list at ethereal-dev@ethereal.com.
2086 On UNIX-flavored OSes, please try to force Ethereal to dump core, by sending
2087 it a SIGABRT signal (usually signal 6) with the kill command, and then get a
2088 stack trace if you have a debugger installed. A stack trace can be obtained
2089 by using your debugger (gdb in this example), the Ethereal binary, and the
2090 resulting core file. Here's an example of how to use the gdb command
2094 ..... prints the stack trace
2098 The core dump file may be named "ethereal.core" rather than "core" on some
2099 platforms (e.g., BSD systems).
2101 Also, if at all possible, please send a copy of the capture file that caused
2102 the problem; when capturing packets, Ethereal normally writes captured
2103 packets to a temporary file, which will probably be in /tmp or /var/tmp on
2104 UNIX-flavored OSes, \TEMP on the main system disk (normally C:) on Windows
2105 9x/Me/NT 4.0, and \Documents and Settings\your login name\Local
2106 Settings\Temp on the main system disk on Windows 2000/Windows XP/Windows
2107 Server 2003, so the capture file will probably be there. It will have a name
2108 beginning with ether, with some mixture of letters and numbers after that.
2109 Please don't send a trace file greater than 1 MB when compressed; instead,
2110 make it available via FTP or HTTP, or say it's available but leave it up to
2111 a developer to ask for it. If the trace file contains sensitive information
2112 (e.g., passwords), then please do not send it.
2114 Q 5.44: How can I search for, or filter, packets that have a particular
2115 string anywhere in them?
2117 A: If you want to do this when capturing, you can't. That's a feature that
2118 would be hard to implement in capture filters without changes to the capture
2119 filter code, which, on many platforms, is in the OS kernel and, on other
2120 platforms, is in the libpcap library.
2122 In releases prior to 0.9.14, you also can't search for, or filter, packets
2123 containing a particular string even after you've captured them.
2125 In 0.9.14, you can search for, but not filter, packets that have a
2126 particular string; this has been added to the "Find Frame" dialog ("Find
2127 Frame" under the "Edit" menu, or control-F).
2129 In 0.9.15 and later, you can search for those packets using either the
2130 mechanism introduced in 0.9.14 or using the new "contains" operator in
2131 filter expressions, which lets you search the entire packet or text string
2132 or byte string fields in the packet; the "contains" operator can also be
2133 used in expressions used to filter the display.
2135 Q 5.45: How do I filter a capture to see traffic for virus XXX?
2137 A: For some viruses/worms there might be a capture filter to recognize the
2138 virus traffic. Check the CaptureFilters page on the Ethereal Wiki to see if
2139 anybody's added such a filter.
2141 Note that Ethereal was not designed to be an intrusion detection system; you
2142 might be able to use it as an IDS, but in most cases software designed to be
2143 an IDS, such as Snort or Prelude, will probably work better.
2145 The Bleeding Edge of Snort has a collection of signatures for Snort to
2146 detect various viruses, worms, and the like.
2148 Please send support questions about Ethereal to the
2149 ethereal-users[AT]ethereal.com mailing list.
2150 For corrections/additions/suggestions for this web page (and not Ethereal
2151 support questions), please send email to ethereal-web[AT]ethereal.com .
2152 Last modified: Wed, May 25 2005.
git.samba.org / obnox / wireshark / wip.git / blob