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
29 1.8 What devices can Ethereal use to capture packets?
31 1.9 How do you pronounce Ethereal? Where did the name come from?
35 2.1 I downloaded the Win32 installer, but when I try to run it, I get
38 2.2 When I try to download the WinPcap driver and library, I can't get
39 to the WinPcap Web site.
43 3.1 I installed an Ethereal RPM, but Ethereal doesn't seem to be
44 installed; only Tethereal is installed.
48 4.1 The configure script can't find pcap.h or bpf.h, but I have
51 4.2 Why do I get the error
53 dftest_DEPENDENCIES was already defined in condition TRUE, which
54 implies condition HAVE_PLUGINS_TRUE
56 when I try to build Ethereal from SVN or a SVN snapshot?
58 4.3 The link fails with a number of "Output line too long." messages
59 followed by linker errors.
61 4.4 The link fails on Solaris because plugin_list is undefined.
63 4.5 The build fails on Windows because of conflicts between winsock.h
68 5.1 When I use Ethereal to capture packets, I see only packets to and
69 from my machine, or I'm not seeing all the traffic I'm expecting to
70 see from or to the machine I'm trying to monitor.
72 5.2 I can't see any TCP packets other than packets to and from my
73 machine, even though another analyzer on the network sees those
76 5.3 I'm only seeing ARP packets when I try to capture traffic.
78 5.4 I'm running Ethereal on Windows; why does some network interface
79 on my machine not show up in the list of interfaces in the
80 "Interface:" field in the dialog box popped up by "Capture->Start",
81 and/or why does Ethereal give me an error if I try to capture on that
84 5.5 I'm running Ethereal on Windows; why do no network interfaces show
85 up in the list of interfaces in the "Interface:" field in the dialog
86 box popped up by "Capture->Start"?
88 5.6 I'm running Ethereal on Windows; why doesn't my serial port/ADSL
89 modem/ISDN modem/show up in the list of interfaces in the "Interface:"
90 field in the dialog box popped up by "Capture->Start"?
92 5.7 I'm running Ethereal on a UNIX-flavored OS; why does some network
93 interface on my machine not show up in the list of interfaces in the
94 "Interface:" field in the dialog box popped up by "Capture->Start",
95 and/or why does Ethereal give me an error if I try to capture on that
98 5.8 I'm running Ethereal on a UNIX-flavored OS; why do no network
99 interfaces show up in the list of interfaces in the "Interface:" field
100 in the dialog box popped up by "Capture->Start"?
102 5.9 Can Ethereal capture on (my T1/E1 line, SS7 links, etc.)?
104 5.10 How do I put an interface into promiscuous mode?
106 5.11 I can set a display filter just fine, but capture filters don't
109 5.12 I'm entering valid capture filters, but I still get "parse error"
112 5.13 I saved a filter and tried to use its name to filter the display,
113 but I got an "Unexpected end of filter string" error.
115 5.14 Why am I seeing lots of packets with incorrect TCP checksums?
117 5.15 I've just installed Ethereal, and the traffic on my local LAN is
120 5.16 When I run Ethereal on Solaris 8, it dies with a Bus Error when I
123 5.17 When I run Ethereal, I get an error
125 Gtk-CRITICAL **: file gtkwindow.c: line 3107 (gtk_window_resize):
126 assertion `height > 0' failed.
128 5.18 When I run Tethereal with the "-x" option, it crashes with an
131 "** ERROR **: file print.c: line 691 (print_line): should not be
134 5.19 When I run Ethereal on Windows NT, it dies with a Dr. Watson
135 error, reporting an "Integer division by zero" exception, when I start
138 5.20 When I try to run Ethereal, it complains about
139 sprint_realloc_objid being undefined.
141 5.21 I'm running Ethereal on Linux; why do my time stamps have only
142 100ms resolution, rather than 1us resolution?
144 5.22 I'm capturing packets on {Windows 95, Windows 98, Windows Me};
145 why are the time stamps on packets wrong?
147 5.23 When I try to run Ethereal on Windows, it fails to run because it
148 can't find packet.dll.
150 5.24 I'm running Ethereal on Windows NT/2000/XP/Server; my machine has
151 a PPP (dial-up POTS, ISDN, etc.) interface, and it shows up in the
152 "Interface" item in the "Capture Options" dialog box. Why can no
153 packets be sent on or received from that network while I'm trying to
154 capture traffic on that interface?
156 5.25 I'm running Ethereal on Windows 95/98/Me, on a machine with more
157 than one network adapter of the same type; Ethereal shows all of those
158 adapters with the same name, but I can't use any of those adapters
159 other than the first one.
161 5.26 I'm running Ethereal on Windows, and I'm not seeing any traffic
162 being sent by the machine running Ethereal.
164 5.27 I'm trying to capture traffic but I'm not seeing any.
166 5.28 I have an XXX network card on my machine; if I try to capture on
167 it, my machine crashes or resets itself.
169 5.29 My machine crashes or resets itself when I select "Start" from
170 the "Capture" menu or select "Preferences" from the "Edit" menu.
172 5.30 Does Ethereal work on Windows Me?
174 5.31 Does Ethereal work on Windows XP?
176 5.32 Why doesn't Ethereal correctly identify RTP packets? It shows
179 5.33 Why doesn't Ethereal show Yahoo Messenger packets in captures
180 that contain Yahoo Messenger traffic?
182 5.34 Why do I get the error
184 Gdk-ERROR **: Palettized display (256-colour) mode not supported on
188 when I try to run Ethereal on Windows?
190 5.35 When I capture on Windows in promiscuous mode, I can see packets
191 other than those sent to or from my machine; however, those packets
192 show up with a "Short Frame" indication, unlike packets to or from my
193 machine. What should I do to arrange that I see those packets in their
196 5.36 I'm capturing packets on a machine on a VLAN; why don't the
197 packets I'm capturing have VLAN tags?
199 5.37 How can I capture raw 802.11 packets, including non-data
200 (management, beacon) packets?
202 5.38 How do I capture on an 802.11 device in monitor mode on Linux?
204 5.39 How do I capture on an 802.11 device in monitor mode on FreeBSD?
206 5.40 How do I capture on an 802.11 device in monitor mode on NetBSD?
208 5.41 I'm trying to capture 802.11 traffic on Windows; why am I not
211 5.42 I'm trying to capture 802.11 traffic on Windows; why am I seeing
212 packets received by the machine on which I'm capturing traffic, but
213 not packets sent by that machine?
215 5.43 How can I capture packets with CRC errors?
217 5.44 How can I capture entire frames, including the FCS?
219 5.45 Why does Ethereal hang after I stop a capture?
221 5.46 How can I search for, or filter, packets that have a particular
222 string anywhere in them?
224 5.47 How do I filter a capture to see traffic for virus XXX?
228 Q 1.1: Where can I get help?
230 A: Support is available on the ethereal-users mailing list.
231 Subscription information and archives for all of Ethereal's mailing
232 lists can be found at http://www.ethereal.com/lists
234 Q 1.2: How much does Ethereal cost?
236 A: Ethereal is "free software"; you can download it without paying any
237 license fee. The version of Ethereal you download isn't a "demo"
238 version, with limitations not present in a "full" version; it is the
241 The license under which Ethereal is issued is the GNU General Public
242 License. See the GNU GPL FAQ for some more information.
244 Q 1.3: Can I use Ethereal commercially?
246 A: Yes, if, for example, you mean "I work for a commercial
247 organization; can I use Ethereal to capture and analyze network
248 traffic in our company's networks or in our customer's networks?"
250 If you mean "Can I use Ethereal as part of my commercial product?",
251 see the next entry in the FAQ.
253 Q 1.4: Can I use Ethereal as part of my commercial product?
255 A: As noted, Ethereal is licended under the GNU General Public
256 License. The GPL imposes conditions on your use of GPL'ed code in your
257 own products; you cannot, for example, make a "derived work" from
258 Ethereal, by making modifications to it, and then sell the resulting
259 derived work and not allow recipients to give away the resulting work.
260 You must also make the changes you've made to the Ethereal source
261 available to all recipients of your modified version; those changes
262 must also be licensed under the terms of the GPL. See the GPL FAQ for
263 more details; in particular, note the answer to the question about
264 modifying a GPLed program and selling it commercially, and the
265 question about linking GPLed code with other code to make a
268 You can combine a GPLed program such as Ethereal and a commercial
269 program as long as they communicate "at arm's length", as per this
272 Q 1.5: What protocols are currently supported?
274 A: There are currently 602 supported protocols and media, listed
275 below. Descriptions can be found in the ethereal(1) man page.
279 802.1x Authentication
280 AAL type 2 signalling protocol - Capability set 1 (Q.2630.1)
282 AFS (4.0) Replication Server call declarations
285 AIM Buddylist Service
292 AIM Invitation Service
297 AIM Privacy Management Service
299 AIM Server Side Themes
306 ANSI IS-637-A (SMS) Teleservice Layer
307 ANSI IS-637-A (SMS) Transport Layer
308 ANSI IS-683-A (OTA (Mobile))
309 ANSI IS-801 (Location Services (PLD))
310 ANSI Mobile Application Part
311 AOL Instant Messenger
319 AVS WLAN Capture header
321 Ad hoc On-demand Distance Vector Routing Protocol
322 Address Resolution Protocol
323 Aggregate Server Access Protocol
325 Alteon - Transparent Proxy Cache Protocol
326 Andrew File System (AFS)
327 Apache JServ Protocol v1.3
328 Apple IP-over-IEEE 1394
329 AppleTalk Filing Protocol
330 AppleTalk Session Protocol
331 AppleTalk Transaction Protocol packet
332 Appletalk Address Resolution Protocol
333 Application Configuration Access Protocol
335 Async data over ISDN (V.120)
336 Authentication Header
337 BACnet Virtual Link Control
343 Banyan Vines Fragmentation Protocol
350 Basic Encoding Rules (ASN.1 X.690)
351 Bearer Independent Call Control
352 Bi-directional Fault Detection Control Message
353 Blocks Extensible Exchange Protocol
354 Blubster/Piolet MANOLITO Protocol
358 Border Gateway Protocol
359 Building Automation and Control Network APDU
360 Building Automation and Control Network NPDU
362 CDS Clerk Server Calls
363 Cast Client Control Protocol
364 Check Point High Availability Protocol
367 Cisco Discovery Protocol
368 Cisco Group Management Protocol
370 Cisco Hot Standby Router Protocol
372 Cisco Interior Gateway Routing Protocol
375 Cisco Session Management
377 CoSine IPNOS L2 debug output
378 Common Industrial Protocol
379 Common Open Policy Service
380 Common Unix Printing System (CUPS) Browsing Protocol
382 Configuration Test Protocol (loopback)
383 Connectionless Lightweight Directory Access Protocol
384 Coseventcomm Dissector Using GIOP API
385 Cosnaming Dissector Using GIOP API
386 Cross Point Frame Injector
387 Cryptographic Message Syntax
388 DCE Distributed Time Service Local Server
389 DCE Distributed Time Service Provider
392 DCE Security ID Mapper
396 DCE/RPC CDS Solicitation
397 DCE/RPC Conversation Manager
398 DCE/RPC Directory Acl Interface
399 DCE/RPC Endpoint Mapper
400 DCE/RPC Endpoint Mapper4
402 DCE/RPC FLDB UBIK TRANSFER
403 DCE/RPC FLDB UBIKVOTE
406 DCE/RPC NCS 1.5.1 Local Location Broker
407 DCE/RPC Operations between registry server replicas
414 DCE/RPC Registry Password Management
415 DCE/RPC Registry Server Attributes Schema
416 DCE/RPC Registry server propagation interface - ACLs.
417 DCE/RPC Registry server propagation interface - PGO items
418 DCE/RPC Registry server propagation interface - properties and poli
420 DCE/RPC Remote Management
421 DCE/RPC Repserver Calls
422 DCE/RPC TokenServer Calls
425 DCOM Remote Activation
426 DEC Spanning Tree Protocol
432 DNS Control Program Server
434 DOCSIS Appendix C TLV's
435 DOCSIS Baseline Privacy Key Management Attributes
436 DOCSIS Baseline Privacy Key Management Request
437 DOCSIS Baseline Privacy Key Management Response
438 DOCSIS Dynamic Service Addition Acknowledge
439 DOCSIS Dynamic Service Addition Request
440 DOCSIS Dynamic Service Addition Response
441 DOCSIS Dynamic Service Change Acknowledgement
442 DOCSIS Dynamic Service Change Request
443 DOCSIS Dynamic Service Change Response
444 DOCSIS Dynamic Service Delete Request
445 DOCSIS Dynamic Service Delete Response
446 DOCSIS Initial Ranging Message
447 DOCSIS Mac Management
448 DOCSIS Range Request Message
449 DOCSIS Ranging Response
450 DOCSIS Registration Acknowledge
451 DOCSIS Registration Requests
452 DOCSIS Registration Responses
453 DOCSIS Upstream Bandwidth Allocation
454 DOCSIS Upstream Channel Change Request
455 DOCSIS Upstream Channel Change Response
456 DOCSIS Upstream Channel Descriptor
457 DOCSIS Upstream Channel Descriptor Type 29
458 DOCSIS Vendor Specific Endodings
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
474 Encapsulating Security Payload
475 Endpoint Name Resolution Protocol
476 Enhanced Interior Gateway Routing Protocol
477 EtherNet/IP (Industrial Protocol)
481 Extensible Authentication Protocol
483 FC Fabric Configuration Server
487 Fiber Distributed Data Interface
489 Fibre Channel Common Transport
490 Fibre Channel Fabric Zone Server
491 Fibre Channel Name Server
492 Fibre Channel Protocol for SCSI
494 Fibre Channel Security Protocol
495 Fibre Channel Single Byte Command
496 File Transfer Protocol (FTP)
497 Financial Information eXchange Protocol
500 GARP Multicast Registration Protocol
501 GARP VLAN Registration Protocol
503 GPRS Tunneling Protocol
507 GSM Mobile Application Part
508 GSM SMS TPDU (GSM 03.40)
509 GSM Short Message Service User Data
510 General Inter-ORB Protocol
511 Generic Routing Encapsulation
512 Generic Security Service Application Program Interface
516 H235-SECURITY-MESSAGES
519 HP Extended Local-Link Control
520 HP Remote Maintenance Protocol
521 Hummingbird NFS Daemon
523 Hypertext Transfer Protocol
525 IEEE 802.11 Radiotap Capture header
526 IEEE 802.11 wireless LAN
527 IEEE 802.11 wireless LAN management frame
529 IP Device Control (SS7 over IP)
531 IP Payload Compression
532 IP Virtual Services Sync Daemon
534 IPX Routing Information Protocol
536 IRemUnknown IRemUnknown Resolver
537 IRemUnknown2 IRemUnknown2 Resolver
539 ISDN Q.921-User Adaptation Layer
541 ISO 10589 ISIS InTRA Domain Routeing Information Exchange Protocol
542 ISO 8073 COTP Connection-Oriented Transport Protocol
543 ISO 8327-1 OSI Session Protocol
544 ISO 8473 CLNP ConnectionLess Network Protocol
545 ISO 8602 CLTP ConnectionLess Transport Protocol
546 ISO 8823 OSI Presentation Protocol
547 ISO 9542 ESIS Routeing Information Exchange Protocol
548 ISystemActivator ISystemActivator Resolver
550 ITU-T Recommendation H.261
551 ITU-T Recommendation H.263 RTP Payload header (RFC2190)
553 Information Access Protocol
555 Intelligent Platform Management Interface
556 Inter-Access-Point Protocol
557 Inter-Asterisk eXchange v2
558 InterSwitch Message Protocol
560 Internet Cache Protocol
561 Internet Communications Engine Protocol
562 Internet Content Adaptation Protocol
563 Internet Control Message Protocol
564 Internet Control Message Protocol v6
565 Internet Group Management Protocol
566 Internet Group membership Authentication Protocol
567 Internet Message Access Protocol
568 Internet Printing Protocol
570 Internet Protocol Version 6
572 Internet Security Association and Key Management Protocol
573 Internetwork Packet eXchange
575 IrDA Link Access Protocol
576 IrDA Link Management Protocol
577 JPEG File Interchange Format
582 Kerberos Administration
586 LWAPP Encapsulated Packet
588 Label Distribution Protocol
590 Layer 2 Tunneling Protocol
591 Light Weight DNS RESolver (BIND9)
592 Lightweight Directory Access Protocol
593 Line Printer Daemon Protocol
595 Link Access Procedure Balanced (LAPB)
596 Link Access Procedure Balanced Ethernet (LAPBETHER)
597 Link Access Procedure, Channel D (LAPD)
598 Link Aggregation Control Protocol
599 Link Management Protocol (LMP)
600 Linux cooked-mode capture
601 Local Management Interface
602 LocalTalk Link Access Protocol
604 Logical Link Control GPRS
606 Lucent/Ascend debug output
610 MIME Multipart Media Encapsulation
611 MMS Message Encapsulation
614 MSN Messenger Service
615 MSNIP: Multicast Source Notification of Interest Protocol
616 MTP 2 Transparent Proxy
617 MTP 2 User Adaptation Layer
618 MTP 3 User Adaptation Layer
619 MTP2 Peer Adaptation Layer
620 Media Gateway Control Protocol
622 Media Type: message/http
623 Message Transfer Part Level 2
624 Message Transfer Part Level 3
625 Message Transfer Part Level 3 Management
626 Microsoft Directory Replication Service
627 Microsoft Distributed File System
628 Microsoft Distributed Link Tracking Server Service
629 Microsoft Encrypted File System Service
630 Microsoft Eventlog Service
631 Microsoft Exchange MAPI
632 Microsoft File Replication Service
633 Microsoft File Replication Service API
634 Microsoft Local Security Architecture
635 Microsoft Local Security Architecture (Directory Services)
636 Microsoft Messenger Service
637 Microsoft Network Logon
639 Microsoft Security Account Manager
640 Microsoft Server Service
641 Microsoft Service Control
642 Microsoft Spool Subsystem
643 Microsoft Task Scheduler Service
644 Microsoft Telephony API Service
645 Microsoft Windows Browser Protocol
646 Microsoft Windows Lanman Remote API Protocol
647 Microsoft Windows Logon Protocol
648 Microsoft Workstation Service
653 MultiProtocol Label Switching Header
654 Multicast Router DISCovery protocol
655 Multicast Source Discovery Protocol
656 Multiprotocol Label Switching Echo
663 NTLM Secure Service Provider
664 Name Binding Protocol
665 Name Management Protocol over IPX
667 NetBIOS Datagram Service
669 NetBIOS Session Service
671 NetScape Certificate Extensions
672 NetWare Core Protocol
673 NetWare Link Services Protocol
674 NetWare Serialization Protocol
675 Network Data Management Protocol
677 Network Lock Manager Protocol
678 Network News Transfer Protocol
679 Network Status Monitor CallBack Protocol
680 Network Status Monitor Protocol
681 Network Time Protocol
683 Novell Distributed Print System
684 Novell Modular Authentication Service
686 OSI ISO 8571 FTAM Protocol
687 OSI ISO/IEC 10035-1 ACSE Protocol
688 Open Policy Service Interface
689 Open Shortest Path First
690 OpenBSD Encapsulating device
691 OpenBSD Packet Filter log file
692 OpenBSD Packet Filter log file, pre 3.4
693 Optimized Link State Routing Protocol
700 PPP Bandwidth Allocation Control Protocol
701 PPP Bandwidth Allocation Protocol
702 PPP CDP Control Protocol
703 PPP Callback Control Protocol
704 PPP Challenge Handshake Authentication Protocol
705 PPP Compressed Datagram
706 PPP Compression Control Protocol
707 PPP IP Control Protocol
708 PPP IPv6 Control Protocol
709 PPP Link Control Protocol
710 PPP MPLS Control Protocol
711 PPP Multilink Protocol
713 PPP OSI Control Protocol
714 PPP Password Authentication Protocol
716 PPP-over-Ethernet Discovery
717 PPP-over-Ethernet Session
718 PPPMux Control Protocol
719 Packed Encoding Rules (ASN.1 X.691)
720 Packet Cable Lawful Intercept
722 Point-to-Point Protocol
723 Point-to-Point Tunnelling Protocol
724 Port Aggregation Protocol
727 Pragmatic General Multicast
728 Precision Time Protocol (IEEE1588)
730 Privilege Server operations
731 Protocol Independent Multicast
735 Quake II Network Protocol
736 Quake III Arena Network Protocol
737 Quake Network Protocol
738 QuakeWorld Network Protocol
739 Qualified Logical Link Control
745 RS Interface properties
747 RSYNC File Synchroniser
751 Radio Access Network Application Part
754 Real Time Streaming Protocol
755 Real-Time Publish-Subscribe Wire Protocol
756 Real-Time Transport Protocol
757 Real-time Transport Control Protocol
758 Redundant Link Management Protocol
759 Registry Server Attributes Manipulation Interface
760 Registry server administration operations.
762 Remote Management Control Protocol
763 Remote Override interface
764 Remote Procedure Call
770 Remote sec_login preauth interface.
771 Resource ReserVation Protocol (RSVP)
773 Routing Information Protocol
774 Routing Table Maintenance Protocol
777 SEBEK - Kernel Data Capture
779 SMB (Server Message Block Protocol)
780 SMB MailSlot Protocol
783 SNMP Multiplex Protocol
786 SS7 SCCP-User Adaptation Layer
790 Sequenced Packet eXchange
792 Service Advertisement Protocol
793 Service Location Protocol
794 Session Announcement Protocol
795 Session Description Protocol
796 Session Initiation Protocol
797 Session Initiation Protocol (SIP as raw text)
798 Short Message Peer to Peer
799 Signaling Compression
800 Signalling Connection Control Part
801 Signalling Connection Control Part Management
802 Simple Mail Transfer Protocol
803 Simple Network Management Protocol
804 Simple Traversal of UDP Through NAT
807 Skinny Client Control Protocol
808 SliMP3 Communication Protocol
811 Spanning Tree Protocol
813 Stream Control Transmission Protocol
814 Subnetwork Dependent Convergence Protocol
815 Symantec Enterprise Firewall
816 Synchronous Data Link Control (SDLC)
818 Systems Network Architecture
819 Systems Network Architecture XID
823 TEI Management Procedure, Channel D (LAPD)
826 Tazmen Sniffer Protocol
828 Teredo IPv6 over UDP tunneling
830 Time Synchronization Protocol
831 Tiny Transport Protocol
833 Token-Ring Media Access Control
834 Transaction Capabilities Application Part
835 Transmission Control Protocol
836 Transparent Network Substrate Protocol
837 Transport Adapter Layer Interface v1.0, RFC 3094
838 Trivial File Transfer Protocol
839 UDP Encapsulation of IPsec Packets
840 Universal Computer Protocol
841 User Datagram Protocol
842 V5.2-User Adaptation Layer
843 Virtual Router Redundancy Protocol
844 Virtual Trunking Protocol
846 WAP Session Initiation Request
847 Web Cache Coordination Protocol
849 WebSphere MQ Programmable Command Formats
850 Wellfleet Breath of Life
851 Wellfleet Compression
855 Wireless Session Protocol
856 Wireless Transaction Protocol
857 Wireless Transport Layer Security
858 X Display Manager Control Protocol
862 X.509 Authentication Framework
863 X.509 Certificate Extensions
864 X.509 Information Framework
865 X.509 Selected Attribute Types
868 Yahoo Messenger Protocol
869 Yahoo YMSG Messenger Protocol
873 Yellow Pages Transfer
875 Zone Information Protocol
877 giFT Internet File Transfer
881 Q 1.6: Are there any plans to support {your favorite protocol}?
883 A: Support for particular protocols is added to Ethereal as a result
884 of people contributing that support; no formal plans for adding
885 support for particular protocols in particular future releases exist.
887 Q 1.7: Can Ethereal read capture files from {your favorite network
890 A: Support for particular protocols is added to Ethereal as a result
891 of people contributing that support; no formal plans for adding
892 support for particular protocols in particular future releases exist.
894 If a network analyzer writes out files in a format already supported
895 by Ethereal (e.g., in libpcap format), Ethereal may already be able to
896 read them, unless the analyzer has added its own proprietary
897 extensions to that format.
899 If a network analyzer writes out files in its own format, or has added
900 proprietary extensions to another format, in order to make Ethereal
901 read captures from that network analyzer, we would either have to have
902 a specification for the file format, or the extensions, sufficient to
903 give us enough information to read the parts of the file relevant to
904 Ethereal, or would need at least one capture file in that format AND a
905 detailed textual analysis of the packets in that capture file (showing
906 packet time stamps, packet lengths, and the top-level packet header)
907 in order to reverse-engineer the file format.
909 Note that there is no guarantee that we will be able to
910 reverse-engineer a capture file format.
912 Q 1.8: What devices can Ethereal use to capture packets?
914 A: Ethereal can read live data from Ethernet, Token-Ring, FDDI, serial
915 (PPP and SLIP) (if the OS on which it's running allows Ethereal to do
916 so), 802.11 wireless LAN (if the OS on which it's running allows
917 Ethereal to do so), ATM connections (if the OS on which it's running
918 allows Ethereal to do so), and the "any" device supported on Linux by
919 recent versions of libpcap. See the list of supported capture media on
920 various OSes for details (several items in there say "Unknown", which
921 doesn't mean "Ethereal can't capture on them", it means "we don't know
922 whether it can capture on them"; we expect that it will be able to
923 capture on many of them, but we haven't tried it ourselves - if you
924 try one of those types and it works, please send an update to
927 It can also read a variety of capture file formats, including:
930 * Shomiti/Finisar Surveyor
932 * DOS-based Sniffer (compressed and uncompressed)
935 * NetXray and Windows-based Sniffer
936 * EtherPeek/TokenPeek/AiroPeek
937 * RADCOM WAN/LAN analyzer
938 * Lucent/Ascend debug output
939 * Toshiba ISDN router "snoop" output
941 * ISDN4BSD "i4btrace" utility.
943 * pppd log files (pppdump format)
946 * Visual Networks' Visual UpTime
949 so that it can read traces from various network types, as captured by
950 other applications or equipment, even if it cannot itself capture on
953 Q 1.9: How do you pronounce Ethereal? Where did the name come from?
955 A: The English pronunciation can be found in Merriam-Webster's online
957 http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=ethereal.
959 According to the book "Computer Networks" by Andrew Tannenbaum,
960 Ethernet was named after the "luminiferous ether" which was once
961 thought to carry electromagnetic radiation. Taking that into
962 consideration, Ethereal seemed like an appropriate name for something
963 that started out as an Ethernet analyzer.
967 Q 2.1: I downloaded the Win32 installer, but when I try to run it, I
970 A: The program you used to download it may have downloaded it
971 incorrectly. Web browsers sometimes may do this.
973 Try downloading it with, for example:
974 * Wget, for which Windows binaries are available on the SunSITE FTP
975 server at sunsite.tk or Heiko Herold's windows wget spot - wGetGUI
976 offers a GUI interface that uses wget;
977 * WS_FTP from Ipswitch,
978 * the ftp command that comes with Windows.
980 If you use the ftp command, make sure you do the transfer in binary
981 mode rather than ASCII mode, by using the binary command before
982 transferring the file.
984 Q 2.2: When I try to download the WinPcap driver and library, I can't
985 get to the WinPcap Web site.
987 A: As is the case with all Web sites, that site won't necessarily
988 always be accessible; the server may be down due to a problem or down
989 for maintenance, or there may be a networking problem between you and
990 the server. You should try again later, or try the local mirror or the
991 Wiretapped.net mirror.
995 Q 3.1: I installed an Ethereal RPM, but Ethereal doesn't seem to be
996 installed; only Tethereal is installed.
998 A: Older versions of the Red Hat RPMs for Ethereal put only the
999 non-GUI components into the ethereal RPM, the fact that Ethereal is a
1000 GUI program nonwithstanding; newer versions make it a bit clearer by
1001 giving that RPM a name starting with ethereal-base.
1003 In those older versions, there's a separate ethereal-gnome RPM that
1004 includes GUI components such as Ethereal itself, the fact that
1005 Ethereal doesn't use GNOME nonwithstanding; newer versions make it a
1006 bit clearer by giving that RPM a name starting with ethereal-gtk+.
1008 Find the ethereal-gnome or ethereal-gtk+ RPM, and install that also.
1012 Q 4.1: The configure script can't find pcap.h or bpf.h, but I have
1015 A: Are you sure pcap.h and bpf.h are installed? The official
1016 distribution of libpcap only installs the libpcap.a library file when
1017 "make install" is run. To install pcap.h and bpf.h, you must run "make
1018 install-incl". If you're running Debian or Redhat, make sure you have
1019 the "libpcap-dev" or "libpcap-devel" packages installed.
1021 It's also possible that pcap.h and bpf.h have been installed in a
1022 strange location. If this is the case, you may have to tweak
1025 Q 4.2: Why do I get the error
1027 dftest_DEPENDENCIES was already defined in condition TRUE, which
1028 implies condition HAVE_PLUGINS_TRUE
1030 when I try to build Ethereal from SVN or a SVN snapshot?
1032 A: You probably have automake 1.5 installed on your machine (the
1033 command automake --version will report the version of automake on your
1034 machine). There is a bug in that version of automake that causes this
1035 problem; upgrade to a later version of automake (1.6 or later).
1037 Q 4.3: The link fails with a number of "Output line too long."
1038 messages followed by linker errors.
1040 A: The version of the sed command on your system is incapable of
1041 handling very long lines. On Solaris, for example, /usr/bin/sed has a
1042 line length limit too low to allow libtool to work; /usr/xpg4/bin/sed
1043 can handle it, as can GNU sed if you have it installed.
1045 On Solaris, changing your command search path to search /usr/xpg4/bin
1046 before /usr/bin should make the problem go away; on any platform on
1047 which you have this problem, installing GNU sed and changing your
1048 command path to search the directory in which it is installed before
1049 searching the directory with the version of sed that came with the OS
1050 should make the problem go away.
1052 Q 4.4: The link fails on Solaris because plugin_list is undefined.
1054 A: This appears to be due to a problem with some versions of the GTK+
1055 and GLib packages from www.sunfreeware.org; un-install those packages,
1056 and try getting the 1.2.10 versions from that site, or the versions
1057 from The Written Word, or the versions from Sun's GNOME distribution,
1058 or the versions from the supplemental software CD that comes with the
1059 Solaris media kit, or build them from source from the GTK Web site.
1060 Then re-run the configuration script, and try rebuilding Ethereal. (If
1061 you get the 1.2.10 versions from www.sunfreeware.org, and the problem
1062 persists, un-install them and try installing one of the other versions
1065 Q 4.5: The build fails on Windows because of conflicts between
1066 winsock.h and winsock2.h.
1068 A: As of Ethereal 0.9.5, you must install WinPcap 2.3 or later, and
1069 the corresponding version of the developer's pack, in order to be able
1070 to compile Ethereal; it will not compile with older versions of the
1071 developer's pack. The symptoms of this failure are conflicts between
1072 definitions in winsock.h and in winsock2.h; Ethereal uses winsock2.h,
1073 but pre-2.3 versions of the WinPcap developer's packet use winsock.h.
1074 (2.3 uses winsock2.h, so if Ethereal were to use winsock.h, it would
1075 not be able to build with current versions of the WinPcap developer's
1078 Note that the installed version of the developer's pack should be the
1079 same version as the version of WinPcap you have installed.
1083 Q 5.1: When I use Ethereal to capture packets, I see only packets to
1084 and from my machine, or I'm not seeing all the traffic I'm expecting
1085 to see from or to the machine I'm trying to monitor.
1087 A: This might be because the interface on which you're capturing is
1088 plugged into a switch; on a switched network, unicast traffic between
1089 two ports will not necessarily appear on other ports - only broadcast
1090 and multicast traffic will be sent to all ports.
1092 Note that even if your machine is plugged into a hub, the "hub" may be
1093 a switched hub, in which case you're still on a switched network.
1095 Note also that on the Linksys Web site, they say that their
1096 auto-sensing hubs "broadcast the 10Mb packets to the port that operate
1097 at 10Mb only and broadcast the 100Mb packets to the ports that operate
1098 at 100Mb only", which would indicate that if you sniff on a 10Mb port,
1099 you will not see traffic coming sent to a 100Mb port, and vice versa.
1100 This problem has also been reported for Netgear dual-speed hubs, and
1101 may exist for other "auto-sensing" or "dual-speed" hubs.
1103 Some switches have the ability to replicate all traffic on all ports
1104 to a single port so that you can plug your analyzer into that single
1105 port to sniff all traffic. You would have to check the documentation
1106 for the switch to see if this is possible and, if so, to see how to do
1107 this. See the switch reference page on the Ethereal Wiki for
1108 information on some switches. (Note that it's a Wiki, so you can
1109 update or fix that information, or add additional information on those
1110 switches or information on new switches, yourself.)
1112 Note also that many firewall/NAT boxes have a switch built into them;
1113 this includes many of the "cable/DSL router" boxes. If you have a box
1114 of that sort, that has a switch with some number of Ethernet ports
1115 into which you plug machines on your network, and another Ethernet
1116 port used to connect to a cable or DSL modem, you can, at least, sniff
1117 traffic between the machines on your network and the Internet by
1118 plugging the Ethernet port on the router going to the modem, the
1119 Ethernet port on the modem, and the machine on which you're running
1120 Ethereal into a hub (make sure it's not a switching hub, and that, if
1121 it's a dual-speed hub, all three of those ports are running at the
1124 If your machine is not plugged into a switched network or a dual-speed
1125 hub, or it is plugged into a switched network but the port is set up
1126 to have all traffic replicated to it, the problem might be that the
1127 network interface on which you're capturing doesn't support
1128 "promiscuous" mode, or because your OS can't put the interface into
1129 promiscuous mode. Normally, network interfaces supply to the host
1131 * packets sent to one of that host's link-layer addresses;
1132 * broadcast packets;
1133 * multicast packets sent to a multicast address that the host has
1134 configured the interface to accept.
1136 Most network interfaces can also be put in "promiscuous" mode, in
1137 which they supply to the host all network packets they see. Ethereal
1138 will try to put the interface on which it's capturing into promiscuous
1139 mode unless the "Capture packets in promiscuous mode" option is turned
1140 off in the "Capture Options" dialog box, and Tethereal will try to put
1141 the interface on which it's capturing into promiscuous mode unless the
1142 -p option was specified. However, some network interfaces don't
1143 support promiscuous mode, and some OSes might not allow interfaces to
1144 be put into promiscuous mode.
1146 If the interface is not running in promiscuous mode, it won't see any
1147 traffic that isn't intended to be seen by your machine. It will see
1148 broadcast packets, and multicast packets sent to a multicast MAC
1149 address the interface is set up to receive.
1151 You should ask the vendor of your network interface whether it
1152 supports promiscuous mode. If it does, you should ask whoever supplied
1153 the driver for the interface (the vendor, or the supplier of the OS
1154 you're running on your machine) whether it supports promiscuous mode
1155 with that network interface.
1157 In the case of token ring interfaces, the drivers for some of them, on
1158 Windows, may require you to enable promiscuous mode in order to
1159 capture in promiscuous mode. Ask the vendor of the card how to do
1160 this, or see, for example, this information on promiscuous mode on
1161 some Madge token ring adapters (note that those cards can have
1162 promiscuous mode disabled permanently, in which case you can't enable
1165 In the case of wireless LAN interfaces, it appears that, when those
1166 interfaces are promiscuously sniffing, they're running in a
1167 significantly different mode from the mode that they run in when
1168 they're just acting as network interfaces (to the extent that it would
1169 be a significant effor for those drivers to support for promiscuously
1170 sniffing and acting as regular network interfaces at the same time),
1171 so it may be that Windows drivers for those interfaces don't support
1174 Q 5.2: I can't see any TCP packets other than packets to and from my
1175 machine, even though another analyzer on the network sees those
1178 A: You're probably not seeing any packets other than unicast packets
1179 to or from your machine, and broadcast and multicast packets; a switch
1180 will normally send to a port only unicast traffic sent to the MAC
1181 address for the interface on that port, and broadcast and multicast
1182 traffic - it won't send to that port unicast traffic sent to a MAC
1183 address for some other interface - and a network interface not in
1184 promiscuous mode will receive only unicast traffic sent to the MAC
1185 address for that interface, broadcast traffic, and multicast traffic
1186 sent to a multicast MAC address the interface is set up to receive.
1188 TCP doesn't use broadcast or multicast, so you will only see your own
1189 TCP traffic, but UDP services may use broadcast or multicast so you'll
1190 see some UDP traffic - however, this is not a problem with TCP
1191 traffic, it's a problem with unicast traffic, as you also won't see
1192 all UDP traffic between other machines.
1194 I.e., this is probably the same question as this earlier one; see the
1195 response to that question.
1197 Q 5.3: I'm only seeing ARP packets when I try to capture traffic.
1199 A: You're probably on a switched network, and running Ethereal on a
1200 machine that's not sending traffic to the switch and not being sent
1201 any traffic from other machines on the switch. ARP packets are often
1202 broadcast packets, which are sent to all switch ports.
1204 I.e., this is probably the same question as this earlier one; see the
1205 response to that question.
1207 Q 5.4: I'm running Ethereal on Windows; why does some network
1208 interface on my machine not show up in the list of interfaces in the
1209 "Interface:" field in the dialog box popped up by "Capture->Start",
1210 and/or why does Ethereal give me an error if I try to capture on that
1213 A: If you are running Ethereal on Windows NT 4.0, Windows 2000,
1214 Windows XP, or Windows Server, and this is the first time you have run
1215 a WinPcap-based program (such as Ethereal, or Tethereal, or WinDump,
1216 or Analyzer, or...) since the machine was rebooted, you need to run
1217 that program from an account with administrator privileges; once you
1218 have run such a program, you will not need administrator privileges to
1219 run any such programs until you reboot.
1221 If you are running on Windows 95/98/Me, or if you are running on
1222 Windows NT 4.0/2000/XP/Server and have administrator privileges or a
1223 WinPcap-based program has been run with those privileges since the
1224 machine rebooted, then note that Ethereal relies on the WinPcap
1225 library, on the WinPcap device driver, and on the facilities that come
1226 with the OS on which it's running in order to do captures.
1228 Therefore, if the OS, the WinPcap library, or the WinPcap driver don't
1229 support capturing on a particular network interface device, Ethereal
1230 won't be able to capture on that device.
1233 1. 2.02 and earlier versions of the WinPcap driver and library that
1234 Ethereal uses for packet capture didn't support Token Ring
1235 interfaces; versions 2.1 and later support Token Ring, and the
1236 current version of Ethereal works with (and, in fact, requires)
1237 WinPcap 2.1 or later.
1238 If you are having problems capturing on Token Ring interfaces, and
1239 you have WinPcap 2.02 or an earlier version of WinPcap installed,
1240 you should uninstall WinPcap, download and install the current
1241 version of WinPcap, and then install the latest version of
1243 2. On Windows 95, 98, or Me, sometimes more than one interface will
1244 be given the same name; if that is the case, you will only be able
1245 to capture on one of those interfaces - it's not clear to which
1246 one the name, when used in a WinPcap-based application, will
1247 refer. For example, if you have a PPP serial interface and a VPN
1248 interface, they might show up with the same name, for example
1249 "ppp-mac", and if you try to capture on "ppp-mac", it might not
1250 capture on the interface you're currently using. In that case, you
1251 might, for example, have to remove the VPN interface from the
1252 system in order to capture on the PPP serial interface.
1253 3. WinPcap 3.0 doesn't support PPP WAN interfaces, and WinPcap 2.3
1254 doesn't support PPP WAN interfaces on Windows NT/2000/XP/Server,
1255 so Ethereal cannot capture packets on those devices with WinPcap
1256 3.0, or with WInPcap 2.x when running on Windows
1257 NT/2000/XP/Server. Regular dial-up lines, ISDN lines, and various
1258 other lines such as T1/E1 lines are all PPP interfaces. This may
1259 cause the interface not to show up on the list of interfaces in
1260 the "Capture Options" dialog.
1261 4. WinPcap prior to 3.0 does not support multiprocessor machines
1262 (note that machines with a single multi-threaded processor, such
1263 as Intel's new multi-threaded x86 processors, are multiprocessor
1264 machines as far as the OS and WinPcap are concerned), and recent
1265 2.x versions of WinPcap refuse to operate if they detect that
1266 they're running on a multiprocessor machine, which means that they
1267 may not show any network interfaces. You will need to use WinPcap
1268 3.0 to capture on a multiprocessor machine.
1270 If an interface doesn't show up in the list of interfaces in the
1271 "Interface:" field, and you know the name of the interface, try
1272 entering that name in the "Interface:" field and capturing on that
1275 If the attempt to capture on it succeeds, the interface is somehow not
1276 being reported by the mechanism Ethereal uses to get a list of
1277 interfaces. Try listing the interfaces with WinDump; see the WinDump
1278 Web site or the local mirror of the WinDump Web site for information
1281 You would run WinDump with the -D flag; if it lists the interface,
1282 please report this to ethereal-dev@ethereal.com giving full details of
1283 the problem, including
1284 * the operating system you're using, and the version of that
1286 * the type of network device you're using;
1287 * the output of WinDump.
1289 If WinDump does not list the interface, this is almost certainly a
1290 problem with one or more of:
1291 * the operating system you're using;
1292 * the device driver for the interface you're using;
1293 * the WinPcap library and/or the WinPcap device driver;
1295 so first check the WinPcap FAQ, the local mirror of that FAQ, or the
1296 Wiretapped.net mirror of that FAQ, to see if your problem is mentioned
1297 there. If not, then see the WinPcap support page (or the local mirror
1298 of that page) - check the "Submitting bugs" section.
1300 If you are having trouble capturing on a particular network interface,
1301 first try capturing on that device with WinDump; see the WinDump Web
1302 site or the local mirror of the WinDump Web site for information on
1305 If you can capture on the interface with WinDump, send mail to
1306 ethereal-users@ethereal.com giving full details of the problem,
1308 * the operating system you're using, and the version of that
1310 * the type of network device you're using;
1311 * the error message you get from Ethereal.
1313 If you cannot capture on the interface with WinDump, this is almost
1314 certainly a problem with one or more of:
1315 * the operating system you're using;
1316 * the device driver for the interface you're using;
1317 * the WinPcap library and/or the WinPcap device driver;
1319 so first check the WinPcap FAQ, the local mirror of that FAQ, or the
1320 Wiretapped.net mirror of that FAQ, to see if your problem is mentioned
1321 there. If not, then see the WinPcap support page (or the local mirror
1322 of that page) - check the "Submitting bugs" section.
1324 You may also want to ask the ethereal-users@ethereal.com and the
1325 winpcap-users@winpcap.polito.it mailing lists to see if anybody
1326 happens to know about the problem and know a workaround or fix for the
1327 problem. (Note that you will have to subscribe to that list in order
1328 to be allowed to mail to it; see the WinPcap support page, or the
1329 local mirror of that page, for information on the mailing list.) In
1330 your mail, please give full details of the problem, as described
1331 above, and also indicate that the problem occurs with WinDump, not
1334 Q 5.5: I'm running Ethereal on Windows; why do no network interfaces
1335 show up in the list of interfaces in the "Interface:" field in the
1336 dialog box popped up by "Capture->Start"?
1338 A: This is really the same question as the previous one; see the
1339 response to that question.
1341 Q 5.6: I'm running Ethereal on Windows; why doesn't my serial
1342 port/ADSL modem/ISDN modem/show up in the list of interfaces in the
1343 "Interface:" field in the dialog box popped up by "Capture->Start"?
1345 A: All of those devices support Internet access using the
1346 Point-to-Point (PPP) protocol; WinPcap 3.0 doesn't support PPP
1347 interfaces, and WinPcap 2.x doesn't support PPP interfaces on Windows
1348 NT/2000/XP/Server, so Ethereal cannot capture packets on those devices
1349 with WinPcap 3.0, or with WinPcap 2.x when running on Windows
1350 NT/2000/XP/Server. This may cause the interface not to show up on the
1351 list of interfaces in the "Capture Options" dialog.
1353 Q 5.7: I'm running Ethereal on a UNIX-flavored OS; why does some
1354 network interface on my machine not show up in the list of interfaces
1355 in the "Interface:" field in the dialog box popped up by
1356 "Capture->Start", and/or why does Ethereal give me an error if I try
1357 to capture on that interface?
1359 A: You may need to run Ethereal from an account with sufficient
1360 privileges to capture packets, such as the super-user account. Only
1361 those interfaces that Ethereal can open for capturing show up in that
1362 list; if you don't have sufficient privileges to capture on any
1363 interfaces, no interfaces will show up in the list.
1365 If you are running Ethereal from an account with sufficient
1366 privileges, then note that Ethereal relies on the libpcap library, and
1367 on the facilities that come with the OS on which it's running in order
1370 Therefore, if the OS or the libpcap library don't support capturing on
1371 a particular network interface device, Ethereal won't be able to
1372 capture on that device.
1374 On Linux, note that you need to have "packet socket" support enabled
1375 in your kernel; see the "Packet socket" item in the Linux
1376 "Configure.help" file.
1378 On BSD, note that you need to have BPF support enabled in your kernel;
1379 see the documentation for your system for information on how to enable
1380 BPF support (if it's not enabled by default on your system).
1382 On DEC OSF/1, Digital UNIX, or Tru64 UNIX, note that you need to have
1383 packet filtering support in your kernel; the doconfig command will
1384 allow you to configure and build a new kernel with that option.
1386 On Solaris, note that libpcap 0.6.2 and earlier didn't support Token
1387 Ring interfaces; the current version, 0.7.2, does support Token Ring,
1388 and the current version of Ethereal works with libcap 0.7.2 and later.
1390 If an interface doesn't show up in the list of interfaces in the
1391 "Interface:" field, and you know the name of the interface, try
1392 entering that name in the "Interface:" field and capturing on that
1395 If the attempt to capture on it succeeds, the interface is somehow not
1396 being reported by the mechanism Ethereal uses to get a list of
1397 interfaces; please report this to ethereal-dev@ethereal.com giving
1398 full details of the problem, including
1399 * the operating system you're using, and the version of that
1400 operating system (for Linux, give both the version number of the
1401 kernel and the name and version number of the distribution you're
1403 * the type of network device you're using.
1405 If you are having trouble capturing on a particular network interface,
1406 and you've made sure that (on platforms that require it) you've
1407 arranged that packet capture support is present, as per the above,
1408 first try capturing on that device with tcpdump.
1410 If you can capture on the interface with tcpdump, send mail to
1411 ethereal-users@ethereal.com giving full details of the problem,
1413 * the operating system you're using, and the version of that
1414 operating system (for Linux, give both the version number of the
1415 kernel and the name and version number of the distribution you're
1417 * the type of network device you're using;
1418 * the error message you get from Ethereal.
1420 If you cannot capture on the interface with tcpdump, this is almost
1421 certainly a problem with one or more of:
1422 * the operating system you're using;
1423 * the device driver for the interface you're using;
1424 * the libpcap library;
1426 so you should report the problem to the company or organization that
1427 produces the OS (in the case of a Linux distribution, report the
1428 problem to whoever produces the distribution).
1430 You may also want to ask the ethereal-users@ethereal.com and the
1431 tcpdump-workers@tcpdump.org mailing lists to see if anybody happens to
1432 know about the problem and know a workaround or fix for the problem.
1433 In your mail, please give full details of the problem, as described
1434 above, and also indicate that the problem occurs with tcpdump not just
1437 Q 5.8: I'm running Ethereal on a UNIX-flavored OS; why do no network
1438 interfaces show up in the list of interfaces in the "Interface:" field
1439 in the dialog box popped up by "Capture->Start"?
1441 A: This is really the same question as the previous one; see the
1442 response to that question.
1444 Q 5.9: Can Ethereal capture on (my T1/E1 line, SS7 links, etc.)?
1446 A: Ethereal can only capture on devices supported by libpcap/WinPcap.
1447 On most OSes, only devices that can act as network interfaces of the
1448 type that support IP are supported as capture devices for
1449 libpcap/WinPcap, although the device doesn't necessarily have to be
1450 running as an IP interface in order to support traffic capture.
1452 On Linux and FreeBSD, libpcap 0.8 and later support the API for Endace
1453 Measurement Systems' DAG cards, so that a system with one of those
1454 cards, and its driver and libraries, installed can capture traffic
1455 with those cards with libpcap-based applications. You would either
1456 have to have a version of Ethereal built with that version of libpcap,
1457 or a dynamically-linked version of Ethereal and a shared libpcap
1458 library with DAG support, in order to do so with Ethereal. You should
1459 ask Endace whether that could be used to capture traffic on, for
1460 example, your T1/E1 link.
1461 There is currently no hardware to support capturing on SS7 links with
1462 libpcap. (Note that the fact that Ethereal includes dissectors for
1463 many SS7 protocols doesn't imply that it can capture traffic from SS7
1464 links; those protocols can be run over Internet protocols.)
1466 Q 5.10: How do I put an interface into promiscuous mode?
1468 A: By not disabling promiscuous mode when running Ethereal or
1471 Note, however, that:
1472 * the form of promiscuous mode that libpcap (the library that
1473 programs such as tcpdump, Ethereal, etc. use to do packet capture)
1474 turns on will not necessarily be shown if you run ifconfig on the
1475 interface on a UNIX system;
1476 * some network interfaces might not support promiscuous mode, and
1477 some drivers might not allow promiscuous mode to be turned on -
1478 see this earlier question for more information on that;
1479 * the fact that you're not seeing any traffic, or are only seeing
1480 broadcast traffic, or aren't seeing any non-broadcast traffic
1481 other than traffic to or from the machine running Ethereal, does
1482 not mean that promiscuous mode isn't on - see this earlier
1483 question for more information on that.
1485 I.e., this is probably the same question as this earlier one; see the
1486 response to that question.
1488 Q 5.11: I can set a display filter just fine, but capture filters
1491 A: Capture filters currently use a different syntax than display
1492 filters. Here's the corresponding section from the ethereal(1) man
1495 "Display filters in Ethereal are very powerful; more fields are
1496 filterable in Ethereal than in other protocol analyzers, and the
1497 syntax you can use to create your filters is richer. As Ethereal
1498 progresses, expect more and more protocol fields to be allowed in
1501 Packet capturing is performed with the pcap library. The capture
1502 filter syntax follows the rules of the pcap library. This syntax is
1503 different from the display filter syntax."
1505 The capture filter syntax used by libpcap can be found in the
1506 tcpdump(8) man page.
1508 Q 5.12: I'm entering valid capture filters, but I still get "parse
1511 A: There is a bug in some versions of libpcap/WinPcap that cause it to
1512 report parse errors even for valid expressions if a previous filter
1513 expression was invalid and got a parse error.
1515 Try exiting and restarting Ethereal; if you are using a version of
1516 libpcap/WinPcap with this bug, this will "erase" its memory of the
1517 previous parse error. If the capture filter that got the "parse error"
1518 now works, the earlier error with that filter was probably due to this
1521 The bug was fixed in libpcap 0.6; 0.4[.x] and 0.5[.x] versions of
1522 libpcap have this bug, but 0.6[.x] and later versions don't.
1524 Versions of WinPcap prior to 2.3 are based on pre-0.6 versions of
1525 libpcap, and have this bug; WinPcap 2.3 is based on libpcap 0.6.2, and
1526 doesn't have this bug.
1528 If you are running Ethereal on a UNIX-flavored platform, run "ethereal
1529 -v", or select "About Ethereal..." from the "Help" menu in Ethereal,
1530 to see what version of libpcap it's using. If it's not 0.6 or later,
1531 you will need either to upgrade your OS to get a later version of
1532 libpcap, or will need to build and install a later version of libpcap
1533 from the tcpdump.org Web site and then recompile Ethereal from source
1534 with that later version of libpcap.
1536 If you are running Ethereal on Windows with a pre-2.3 version of
1537 WinPcap, you will need to un-install WinPcap and then download and
1538 install WinPcap 2.3.
1540 Q 5.13: I saved a filter and tried to use its name to filter the
1541 display, but I got an "Unexpected end of filter string" error.
1543 A: You cannot use the name of a saved display filter as a filter. To
1544 filter the display, you can enter a display filter expression - not
1545 the name of a saved display filter - in the "Filter:" box at the
1546 bottom of the display, and type the key or press the "Apply" button
1547 (that does not require you to have a saved filter), or, if you want to
1548 use a saved filter, you can press the "Filter:" button, select the
1549 filter in the dialog box that pops up, and press the "OK" button.
1551 Q 5.14: Why am I seeing lots of packets with incorrect TCP checksums?
1553 A: If the packets that have incorrect TCP checksums are all being sent
1554 by the machine on which Ethereal is running, this is probably because
1555 the network interface on which you're capturing does TCP checksum
1556 offloading. That means that the TCP checksum is added to the packet by
1557 the network interface, not by the OS's TCP/IP stack; when capturing on
1558 an interface, packets being sent by the host on which you're capturing
1559 are directly handed to the capture interface by the OS, which means
1560 that they are handed to the capture interface without a TCP checksum
1561 being added to them.
1563 The only way to prevent this from happening would be to disable TCP
1564 checksum offloading, but
1565 1. that might not even be possible on some OSes;
1566 2. that could reduce networking performance significantly.
1568 However, you can disable the check that Ethereal does of the TCP
1569 checksum, so that it won't report any packets as having TCP checksum
1570 errors, and so that it won't refuse to do TCP reassembly due to a
1571 packet having an incorrect TCP checksum. That can be set as an
1572 Ethereal preference by selecting "Preferences" from the "Edit" menu,
1573 opening up the "Protocols" list in the left-hand pane of the
1574 "Preferences" dialog box, selecting "TCP", from that list, turning off
1575 the "Check the validity of the TCP checksum when possible" option,
1576 clicking "Save" if you want to save that setting in your preference
1577 file, and clicking "OK".
1579 It can also be set on the Ethereal or Tethereal command line with a -o
1580 tcp.check_checksum:false command-line flag, or manually set in your
1581 preferences file by adding a tcp.check_checksum:false line.
1583 Q 5.15: I've just installed Ethereal, and the traffic on my local LAN
1586 A: We have a collection of strange and exotic sample capture files at
1587 http://www.ethereal.com/sample/
1589 Q 5.16: When I run Ethereal on Solaris 8, it dies with a Bus Error
1592 A: Some versions of the GTK+ library from www.sunfreeware.org appear
1593 to be buggy, causing Ethereal to drop core with a Bus Error.
1594 Un-install those packages, and try getting the 1.2.10 version from
1595 that site, or the version from The Written Word, or the version from
1596 Sun's GNOME distribution, or the version from the supplemental
1597 software CD that comes with the Solaris media kit, or build it from
1598 source from the GTK Web site. Update the GLib library to the 1.2.10
1599 version, from the same source, as well. (If you get the 1.2.10
1600 versions from www.sunfreeware.org, and the problem persists,
1601 un-install them and try installing one of the other versions
1604 Similar problems may exist with older versions of GTK+ for earlier
1605 versions of Solaris.
1607 Q 5.17: When I run Ethereal, I get an error
1609 Gtk-CRITICAL **: file gtkwindow.c: line 3107 (gtk_window_resize):
1610 assertion `height > 0' failed.
1612 A: This is a bug in Ethereal 0.10.5 and 0.10.5a, which is fixed in
1613 Ethereal 0.10.6 and later releases.
1615 Q 5.18: When I run Tethereal with the "-x" option, it crashes with an
1618 "** ERROR **: file print.c: line 691 (print_line): should not be
1621 A: This is a bug in Ethereal 0.10.0a, which is fixed in 0.10.1 and
1622 later releases. To work around the bug, don't use "-x" unless you're
1623 also using "-V"; note that "-V" produces a full dissection of each
1624 packet, so you might not want to use it.
1626 To get a fixed version, either build the current SVN version from
1627 anonymous SVN or a nightly SVN snapshot, or apply to tethereal.c in
1628 the 0.10.0a source tarball the changes between the broken and the
1629 fixed versions, which you can download with the URL
1630 http://www.ethereal.com/cgi-bin/viewcvs.cgi/ethereal/tethereal.c.diff?
1631 r2=1.211&r1=1.210&diff_format=u and (re-)build from source. It might
1632 be easier to get the SVN version than to get the patch and apply it to
1633 the 0.10.0a source tarball, but it's probably easier to build from the
1634 source tarball than from the SVN version, as you'll need to have more
1635 tools and make more steps to generate from the SVN version some files
1636 that are bundled with the source tarball.
1638 Note that to build from the 0.10.0a source tarball on Windows with
1639 Microsoft Visual C++, you will need to get a file that was missing
1640 from the 0.10.0a source tarball; see the FAQ for that problem.
1642 Q 5.19: When I run Ethereal on Windows NT, it dies with a Dr. Watson
1643 error, reporting an "Integer division by zero" exception, when I start
1646 A: In at least some case, this appears to be due to using the default
1647 VGA driver; if that's not the correct driver for your video card, try
1648 running the correct driver for your video card.
1650 Q 5.20: When I try to run Ethereal, it complains about
1651 sprint_realloc_objid being undefined.
1653 A: Ethereal can only be linked with version 4.2.2 or later of UCD
1654 SNMP. Your version of Ethereal was dynamically linked with such a
1655 version of UCD SNMP; however, you have an older version of UCD SNMP
1656 installed, which means that when Ethereal is run, it tries to link to
1657 the older version, and fails. You will have to replace that version of
1658 UCD SNMP with version 4.2.2 or a later version.
1660 Q 5.21: I'm running Ethereal on Linux; why do my time stamps have only
1661 100ms resolution, rather than 1us resolution?
1663 A: Ethereal gets time stamps from libpcap/WinPcap, and libpcap/WinPcap
1664 get them from the OS kernel, so Ethereal - and any other program using
1665 libpcap, such as tcpdump - is at the mercy of the time stamping code
1666 in the OS for time stamps.
1668 At least on x86-based machines, Linux can get high-resolution time
1669 stamps on newer processors with the Time Stamp Counter (TSC) register;
1670 for example, Intel x86 processors, starting with the Pentium Pro, and
1671 including all x86 processors since then, have had a TSC, and other
1672 vendors probably added the TSC at some point to their families of x86
1675 The Linux kernel must be configured with the CONFIG_X86_TSC option
1676 enabled in order to use the TSC. Make sure this option is enabled in
1679 In addition, some Linux distributions may have bugs in their versions
1680 of the kernel that cause packets not to be given high-resolution time
1681 stamps even if the TSC is enabled. See, for example, bug 61111 for Red
1682 Hat Linux 7.2. If your distribution has a bug such as this, you may
1683 have to run a standard kernel from kernel.org in order to get
1684 high-resolution time stamps.
1686 Q 5.22: I'm capturing packets on {Windows 95, Windows 98, Windows Me};
1687 why are the time stamps on packets wrong?
1689 A: This is due to a bug in WinPcap. The bug should be fixed in WinPcap
1692 Q 5.23: When I try to run Ethereal on Windows, it fails to run because
1693 it can't find packet.dll.
1695 A: In older versions of Ethereal, there were two binary distributions
1696 available for Windows, one that supported capturing packets, and one
1697 that didn't. The version that supported capturing packets required
1698 that you install the WinPcap driver; if you didn't install it, it
1699 would fail to run because it couldn't find packet.dll.
1701 The current version of Ethereal has only one binary distribution for
1702 Windows; that version will check whether WinPcap is installed and, if
1703 it's not, will disable support for packet capture.
1705 The WinPcap driver and libraries can be downloaded from the WinPcap
1706 Web site, the local mirror of the WinPcap Web site, or the
1707 Wiretapped.net mirror of the WinPcap site.
1709 Q 5.24: I'm running Ethereal on Windows NT/2000/XP/Server; my machine
1710 has a PPP (dial-up POTS, ISDN, etc.) interface, and it shows up in the
1711 "Interface" item in the "Capture Options" dialog box. Why can no
1712 packets be sent on or received from that network while I'm trying to
1713 capture traffic on that interface?
1715 A: WinPcap doesn't support PPP WAN interfaces on Windows
1716 NT/2000/XP/Server; one symptom that may be seen is that attempts to
1717 capture in promiscuous mode on the interface cause the interface to be
1718 incapable of sending or receiving packets. You can disable promiscuous
1719 mode using the -p command-line flag or the item in the "Capture
1720 Preferences" dialog box, but this may mean that outgoing packets, or
1721 incoming packets, won't be seen in the capture.
1723 Q 5.25: I'm running Ethereal on Windows 95/98/Me, on a machine with
1724 more than one network adapter of the same type; Ethereal shows all of
1725 those adapters with the same name, but I can't use any of those
1726 adapters other than the first one.
1728 A: Unfortunately, Windows 95/98/Me gives the same name to multiple
1729 instances of the type of same network adapter. Therefore, WinPcap
1730 cannot distinguish between them, so a WinPcap-based application can
1731 capture only on the first such interface; Ethereal is a
1732 libpcap/WinPcap-based application.
1734 Q 5.26: I'm running Ethereal on Windows, and I'm not seeing any
1735 traffic being sent by the machine running Ethereal.
1737 A: If you are running some form of VPN client software, it might be
1738 causing this problem; people have seen this problem when they have
1739 Check Point's VPN software installed on their machine. If that's the
1740 cause of the problem, you will have to remove the VPN software in
1741 order to have Ethereal (or any other application using WinPcap) see
1742 outgoing packets; unfortunately, neither we nor the WinPcap developers
1743 know any way to make WinPcap and the VPN software work well together.
1745 Also, some drivers for Windows (especially some wireless network
1746 interface drivers) apparently do not, when running in promiscuous
1747 mode, arrange that outgoing packets are delivered to the software that
1748 requested that the interface run promiscuously; try turning
1749 promiscuous mode off.
1751 Q 5.27: I'm trying to capture traffic but I'm not seeing any.
1753 A: Is the machine running Ethereal sending out any traffic on the
1754 network interface on which you're capturing, or receiving any traffic
1755 on that network, or is there any broadcast traffic on the network or
1756 multicast traffic to a multicast group to which the machine running
1759 If not, this may just be a problem with promiscuous sniffing, either
1760 due to running on a switched network or a dual-speed hub, or due to
1761 problems with the interface not supporting promiscuous mode; see the
1762 response to this earlier question.
1764 Otherwise, on Windows, see the response to this question and, on a
1765 UNIX-flavored OS, see the response to this question.
1767 Q 5.28: I have an XXX network card on my machine; if I try to capture
1768 on it, my machine crashes or resets itself.
1770 A: This is almost certainly a problem with one or more of:
1771 * the operating system you're using;
1772 * the device driver for the interface you're using;
1773 * the libpcap/WinPcap library and, if this is Windows, the WinPcap
1777 * if you are using Windows, see the WinPcap support page (or the
1778 local mirror of that page) - check the "Submitting bugs" section;
1779 * if you are using some Linux distribution, some version of BSD, or
1780 some other UNIX-flavored OS, you should report the problem to the
1781 company or organization that produces the OS (in the case of a
1782 Linux distribution, report the problem to whoever produces the
1785 Q 5.29: My machine crashes or resets itself when I select "Start" from
1786 the "Capture" menu or select "Preferences" from the "Edit" menu.
1788 A: Both of those operations cause Ethereal to try to build a list of
1789 the interfaces that it can open; it does so by getting a list of
1790 interfaces and trying to open them. There is probably an OS, driver,
1791 or, for Windows, WinPcap bug that causes the system to crash when this
1792 happens; see the previous question.
1794 Q 5.30: Does Ethereal work on Windows Me?
1796 A: Yes, but if you want to capture packets, you will need to install
1797 the latest version of WinPcap, as 2.02 and earlier versions of WinPcap
1798 didn't support Windows Me. You should also install the latest version
1799 of Ethereal as well.
1801 Q 5.31: Does Ethereal work on Windows XP?
1803 A: Yes, but if you want to capture packets, you will need to install
1804 the latest version of WinPcap, as 2.2 and earlier versions of WinPcap
1805 didn't support Windows XP.
1807 Q 5.32: Why doesn't Ethereal correctly identify RTP packets? It shows
1810 A: Ethereal can identify a UDP datagram as containing a packet of a
1811 particular protocol running atop UDP only if
1812 1. The protocol in question has a particular standard port number,
1813 and the UDP source or destination port number is that port
1814 2. Packets of that protocol can be identified by looking for a
1815 "signature" of some type in the packet - i.e., some data that, if
1816 Ethereal finds it in some particular part of a packet, means that
1817 the packet is almost certainly a packet of that type.
1818 3. Some other traffic earlier in the capture indicated that, for
1819 example, UDP traffic between two particular addresses and ports
1820 will be RTP traffic.
1822 RTP doesn't have a standard port number, so 1) doesn't work; it
1823 doesn't, as far as I know, have any "signature", so 2) doesn't work.
1825 That leaves 3). If there's RTSP traffic that sets up an RTP session,
1826 then, at least in some cases, the RTSP dissector will set things up so
1827 that subsequent RTP traffic will be identified. Currently, that's the
1828 only place we do that; there may be other places.
1830 However, there will always be places where Ethereal is simply
1831 incapable of deducing that a given UDP flow is RTP; a mechanism would
1832 be needed to allow the user to specify that a given conversation
1833 should be treated as RTP. As of Ethereal 0.8.16, such a mechanism
1834 exists; if you select a UDP or TCP packet, the right mouse button menu
1835 will have a "Decode As..." menu item, which will pop up a dialog box
1836 letting you specify that the source port, the destination port, or
1837 both the source and destination ports of the packet should be
1838 dissected as some particular protocol.
1840 Q 5.33: Why doesn't Ethereal show Yahoo Messenger packets in captures
1841 that contain Yahoo Messenger traffic?
1843 A: Ethereal only recognizes as Yahoo Messenger traffic packets to or
1844 from TCP port 3050 that begin with "YPNS", "YHOO", or "YMSG". TCP
1845 segments that start with the middle of a Yahoo Messenger packet that
1846 takes more than one TCP segment will not be recognized as Yahoo
1847 Messenger packets (even if the TCP segment also contains the beginning
1848 of another Yahoo Messenger packet).
1850 Q 5.34: Why do I get the error
1852 Gdk-ERROR **: Palettized display (256-colour) mode not supported on
1856 when I try to run Ethereal on Windows?
1858 A: Ethereal is built using the GTK+ toolkit, which supports most
1859 UNIX-flavored OSes, and also supports Windows.
1861 Windows versions of Ethereal before 0.9.14 were built with an older
1862 version of that toolkit, which didn't support 256-color mode on
1863 Windows - it required HiColor (16-bit colors) or more.
1865 Windows versions of Ethereal 0.9.14 and later are built with a version
1866 of that toolkit that supports 256-color mode; upgrade to the current
1867 version of Ethereal if you want to run on a display in 256-color mode.
1869 Q 5.35: When I capture on Windows in promiscuous mode, I can see
1870 packets other than those sent to or from my machine; however, those
1871 packets show up with a "Short Frame" indication, unlike packets to or
1872 from my machine. What should I do to arrange that I see those packets
1875 A: In at least some cases, this appears to be the result of PGPnet
1876 running on the network interface on which you're capturing; turn it
1877 off on that interface.
1879 Q 5.36: I'm capturing packets on a machine on a VLAN; why don't the
1880 packets I'm capturing have VLAN tags?
1882 A: You might be capturing on what might be called a "VLAN interface" -
1883 the way a particular OS makes VLANs plug into the networking stack
1884 might, for example, be to have a network device object for the
1885 physical interface, which takes VLAN packets, strips off the VLAN
1886 header and constructs an Ethernet header, and passes that packet to an
1887 internal network device object for the VLAN, which then passes the
1888 packets onto various higher-level protocol implementations.
1890 In order to see the raw Ethernet packets, rather than "de-VLANized"
1891 packets, you would have to capture not on the virtual interface for
1892 the VLAN, but on the interface corresponding to the physical network
1893 device, if possible.
1895 Q 5.37: How can I capture raw 802.11 packets, including non-data
1896 (management, beacon) packets?
1898 A: That depends on the operating system on which you're running, and
1899 on the 802.11 interface on which you're capturing.
1901 This would probably require that you capture in promiscuous mode or in
1902 the mode called "monitor mode" or "RFMON mode". On some platforms, or
1903 with some cards, this might require that you capture in monitor mode -
1904 promiscuous mode might not be sufficient. If you want to capture
1905 traffic on networks other than the one with which you're associated,
1906 you will have to capture in monitor mode.
1908 Not all operating systems support capturing non-data packets and, even
1909 on operating systems that do support it, not all drivers, and thus not
1910 all interfaces, support it. Even on those that do, monitor mode might
1911 not be supported by the operating system or by the drivers for all
1914 NOTE: an interface running in monitor mode will, on most if not all
1915 platforms, not be able to act as a regular network interface; putting
1916 it into monitor mode will, in effect, take your machine off of
1917 whatever network it's on as long as the interface is in monitor mode,
1918 allowing it only to passively capture packets.
1920 This means that you should disable name resolution when capturing in
1921 monitor mode; otherwise, when Ethereal (or Tethereal, or tcpdump)
1922 tries to display IP addresses as host names, it will probably block
1923 for a long time trying to resolve the name because it will not be able
1924 to communicate with any DNS or NIS servers.
1926 There are FAQ items below with information on capturing in monitor
1927 mode on Linux, FreeBSD, and NetBSD.
1929 On Windows, you will not be able to capture in monitor mode on any
1930 interfaces, and you might not be able to capture in promiscuous mode,
1931 either. You might have some success in promiscuous mode with Centrino
1932 interfaces, although you will need Ethereal 0.10.6 or later in order
1933 to have the non-data packets recognized and properly dissected.
1935 You will not be able to capture in monitor mode on any other platforms
1936 (including Mac OS X). You might be able to capture in promiscuous
1937 mode, but this won't capture non-data packets.
1939 Q 5.38: How do I capture on an 802.11 device in monitor mode on Linux?
1941 A: Whether you will be able to capture in monitor mode depends on the
1942 card and driver you're using. See this page of Linux 802.11b
1943 information for details on 802.11b wireless cards, including
1944 information on the chips they use, and see this page of Linux
1945 802.11b+/a/g information for details on 802.11b+, 802.11a, and 802.11g
1946 wireless cards, including information on the chips they use.
1948 Cisco Aironet cards:
1950 On Linux with the driver in the 2.4.6 through 2.4.19 kernel:
1951 1. Put the card into monitor mode with the command echo "Mode: rfmon"
1952 >/proc/driver/aironet/interface/Config. If you want to capture
1953 traffic for any BSS rather than just the BSS with which the card
1954 is associated, use "Mode: y" rather than "Mode: rfmon".
1955 2. When the capture completes, turn off monitor mode with the command
1956 echo "Mode: ess" >/proc/driver/aironet/interface/Config.
1958 On Linux with the driver in the 2.4.20 or later kernel, or with the
1959 CVS drivers from the airo-linux SourceForge site, you will have to
1960 capture on the wifiN interface if your Aironet card is ethN, after
1961 running the commands listed above.
1963 In all of those cases, Ethereal would have to be linked with libpcap
1964 0.7.1 or later; this means that most Ethereal binary packages won't
1965 work unless they're statically linked with libpcap 0.7.1 or later, or
1966 they're dynamically linked with libpcap and your system has a libpcap
1967 0.7.1 or later shared library installed (note that libpcap source
1968 package from tcpdump.org does not build shared libraries). Some binary
1969 packaging mechanisms might make it difficult to install Ethereal
1970 binary packages built to depend on older libpcap binary packages if
1971 you have a newer libpcap binary package installed; the installer
1972 programs for those packaging mechanisms might support disabling
1973 dependency checking so that they will install Ethereal even though a
1974 newer version of libpcap is installed.
1976 Cards using the Prism II chip set:
1978 You can capture raw 802.11 packets with Prism II cards on Linux
1979 systems with the 0.1.14-pre6 or later version of the linux-wlan-ng
1980 drivers (see the linux-wlan page, and the linux-wlan-ng tarball
1981 directory), or with the hostap driver for Prism II/2.5/3.
1983 Those require either Solomon Peachy's patch to libpcap 0.7.1 (see his
1984 libpcap-0.7.1-prism.diff file, or his RPMs of that version of
1985 libpcap), or the current CVS version of libpcap, which includes his
1986 patch (download it from the "Current Tar files" section of the
1987 tcpdump.org Web site). If you apply his patches to libpcap 0.7.1 and
1988 rebuild and install libpcap, or if you build and install the current
1989 CVS version of libpcap, you would have to rebuild Ethereal from
1990 source, linking it with that new version of libpcap; an Ethereal
1991 binary package would not work. Ethereal binary packages might work if
1992 you install the libpcap-0.7.1-1prism.i386.rpm RPM, as it might install
1993 a libpcap shared library in place of the one on your system.
1995 With the linux-wlan-ng driver, you should:
1996 1. Put the card into monitor mode with the command wlanctl-ng
1997 interface lnxreq_wlansniffer enable=true. You should request
1998 802.11 headers by adding to that command the option
1999 prismheader=true or, if supported, wlanheader=true; the latter
2000 might require libpcap 0.8.1 or later. You can also set the channel
2001 to monitor by adding the argument channel=channel_number to that
2003 2. When the capture completes, turn off monitor mode with the command
2004 wlanctl-ng interface enable=false. You might also have to turn
2005 802.11 headers off with prismheader=false or wlanheader=false.
2007 See the wlan-ng FAQ for additional information, although note that it
2008 does not appear to be up-to-date.
2010 With the hostap driver, you should:
2011 1. Put the card into monitor mode with the command iwpriv interface
2012 monitor mode, where mode is 2 or 3 (mode 3 would require libpcap
2014 2. When the capture completes, turn off monitor mode with the command
2015 iwpriv interface monitor 0.
2017 Orinoco Silver and Gold cards:
2019 On Linux systems, the current version of the SourceForge orinoco_cs
2020 driver should support monitor mode. There also exist patches to
2021 earlier versions of the Orinoco driver, on the Orinoco Monitor Mode
2022 Patch Page, to add support for monitor mode. You will have to
2023 determine which version of the driver you have, and select the
2024 appropriate patch, if one is necessary.
2026 Note that the page indicates that not all versions of the Orinoco
2027 firmware support this patch. It says, for some versions of the patch,
2028 "This patch should allow monitor mode with v8.10 firmware (untested w/
2029 8.42);" if you have version 8.10 or later firmware on your Orinoco
2030 cards, you might have to use those patches, with the corresponding
2031 versions of the Orinoco driver, in order to run in monitor mode.
2033 That patch is written for the drivers included with the pcmcia-cs
2034 drivers, but works equally well for the Orinoco drivers provided with
2035 Linux kernels up to 2.4.20. To apply a patch to your kernel drivers,
2036 simply copy the orinoco-09b-patch.diff file to the
2037 /usr/src/linux/drivers/net directory and patch according to the
2038 directions on the Orinoco Monitor Mode Patch Page. You can double-
2039 check the version of the Orinoco drivers that shipped with your kernel
2040 by examining the first few lines of the orinoco.c file.
2042 The Orinoco patches and SourceForge driver require either Solomon
2043 Peachy's patch to libpcap 0.7.1 (see his libpcap-0.7.1-prism.diff
2044 file, or his RPMs of that version of libpcap), or the current CVS
2045 version of libpcap, which includes his patch (download it from the
2046 "Current Tar files" section of the tcpdump.org Web site). If you apply
2047 his patches to libpcap 0.7.1 and rebuild and install libpcap, or if
2048 you build and install the current CVS version of libpcap, you would
2049 have to rebuild Ethereal from source, linking it with that new version
2050 of libpcap; an Ethereal binary package would not work. Ethereal binary
2051 packages might work if you install the libpcap-0.7.1-1prism.i386.rpm
2052 RPM, as it might install a libpcap shared library in place of the one
2055 With a driver that supports monitor mode, you should:
2056 1. Put the card into monitor mode with the command iwpriv interface
2057 monitor mode channel_number, where mode is 1 or 2, and
2058 channel_number is the number of the channel to monitor.
2059 2. When the capture completes, turn off monitor mode with the command
2060 iwpriv interface monitor 0.
2062 Cards with the Texas Instruments ACX100 chipset:
2064 You can capture raw 802.11 packets with ACX100 cards on Linux systems
2065 with the ACX100 OSS drivers available from the ACX100 wireless network
2066 driver project SourceForge site.
2070 1. Put the card into monitor mode with the command iwpriv interface
2071 monitor 2 channel_number, where channel_number is the number of
2072 the channel to monitor.
2073 2. When the capture completes, turn off monitor mode with the command
2074 iwpriv interface monitor 0.
2076 Cards with Atheros Communications chipsets:
2078 You can capture raw 802.11 packets with AR5K cards on Linux systems
2079 with the v5_ar5k or madwifi drivers. For the v5ar5k driver you will
2080 need the Linux wireless-tools version 25 or higher to put the card
2081 into monitor mode. If you're using the madwifi driver, you can put the
2082 card into monitor mode using iwconfig interface mode monitor, followed
2083 by iwconfig interface channel channel to select a channel (if needed).
2087 It might be possible to capture in monitor mode on other cards. If so,
2088 please supply us with information on how to do so, so that we can
2089 incorporate that information into this FAQ in the future.
2091 Q 5.39: How do I capture on an 802.11 device in monitor mode on
2094 A: On FreeBSD 5.2 and later, you should be able to capture in monitor
2095 mode on 802.11 interfaces supported by the wi and acx drivers, if
2096 Ethereal is linked with libpcap 0.8.1 or later, and on 802.11
2097 interfaces supported by the an driver, if Ethereal is linked with
2098 libpcap 0.7.1 or later.
2100 For cards supported by the wi and acx drivers, you should:
2101 1. Put the card into monitor mode with the command ifconfig interface
2102 monitor. You can also set the channel to monitor by adding the
2103 argument channel channel_number to that command.
2104 2. When you start the capture, in Ethereal select "802.11" as the
2105 "Link-layer header type", and in Tethereal add the command-line
2107 3. When the capture completes, turn off monitor mode with the command
2108 ifconfig interface -monitor.
2110 For cards supported by the an driver, you should:
2111 1. Put the card into monitor mode with the command ancontrol -i
2112 interface -M flag, where flag should be the sum of:
2113 + 1, to turn monitor mode on;
2114 + 2, if you want to capture traffic from any BSS rather than
2115 just the BSS with which the card is associated;
2116 + 4, if you want to see beacon packets (capturing beacon
2117 packets increases the CPU requirements of capturing).
2118 2. When the capture completes, turn off monitor mode with the command
2119 ancontrol -i interface -M 0.
2121 Don't add 8 in to flag; Ethereal currently doesn't support the full
2124 On FreeBSD 4.6 through 5.1, you should be able to capture in monitor
2125 mode on 802.11 interfaces supported by the an driver, but not on any
2126 other interfaces; see the instructions for FreeBSD 5.2 or later for
2129 In FreeBSD 4.5 and earlier, you will not be able to capture in monitor
2130 mode on 802.11 interfaces (no drivers supported it prior to 4.5, and
2131 in 4.5 the an driver had bugs that caused packets not to be captured
2134 Q 5.40: How do I capture on an 802.11 device in monitor mode on
2137 A: On NetBSD 2.0-beta and later, you should be able to capture in
2138 monitor mode on 802.11 interfaces supported by the wi and acx drivers,
2139 if Ethereal is linked with libpcap 0.8.1 or later. The instructions
2140 are the same as for FreeBSD 5.2 and later.
2142 Q 5.41: I'm trying to capture 802.11 traffic on Windows; why am I not
2145 A: At least some 802.11 card drivers on Windows appear not to see any
2146 packets if they're running in promiscuous mode. Try turning
2147 promiscuous mode off; you'll only be able to see packets sent by and
2148 received by your machine, not third-party traffic, and it'll look like
2149 Ethernet traffic and won't include any management or control frames,
2150 but that's a limitation of the card drivers.
2152 Q 5.42: I'm trying to capture 802.11 traffic on Windows; why am I
2153 seeing packets received by the machine on which I'm capturing traffic,
2154 but not packets sent by that machine?
2156 A: This appears to be another problem with promiscuous mode; try
2159 Q 5.43: How can I capture packets with CRC errors?
2161 A: Ethereal can capture only the packets that the packet capture
2162 library - libpcap on UNIX-flavored OSes, and the WinPcap port to
2163 Windows of libpcap on Windows - can capture, and libpcap/WinPcap can
2164 capture only the packets that the OS's raw packet capture mechanism
2165 (or the WinPcap driver, and the underlying OS networking code and
2166 network interface drivers, on Windows) will allow it to capture.
2168 Unless the OS always supplies packets with errors such as invalid CRCs
2169 to the raw packet capture mechanism, or can be configured to do so,
2170 invalid CRCs to the raw packet capture mechanism, Ethereal - and other
2171 programs that capture raw packets, such as tcpdump - cannot capture
2172 those packets. You will have to determine whether your OS needs to be
2173 so configured and, if so, can be so configured, configure it if
2174 necessary and possible, and make whatever changes to libpcap and the
2175 packet capture program you're using are necessary, if any, to support
2176 capturing those packets.
2178 Most OSes probably do not support capturing packets with invalid CRCs
2179 on Ethernet, and probably do not support it on most other link-layer
2180 types. Some drivers on some OSes do support it, such as some Ethernet
2181 drivers on FreeBSD; in those OSes, you might always get those packets,
2182 or you might only get them if you capture in promiscuous mode (you'd
2183 have to determine which is the case).
2185 Note that libpcap does not currently supply to programs that use it an
2186 indication of whether the packet's CRC was invalid (because the
2187 drivers themselves do not supply that information to the raw packet
2188 capture mechanism); therefore, Ethereal will not indicate which
2189 packets had CRC errors unless the FCS was captured (see the next
2190 question) and you're using Ethereal 0.9.15 and later, in which case
2191 Ethereal will check the CRC and indicate whether it's correct or not.
2193 Q 5.44: How can I capture entire frames, including the FCS?
2195 A: Ethereal can only capture data that the packet capture library -
2196 libpcap on UNIX-flavored OSes, and the WinPcap port to Windows of
2197 libpcap on Windows - can capture, and libpcap/WinPcap can capture only
2198 the data that the OS's raw packet capture mechanism (or the WinPcap
2199 driver, and the underlying OS networking code and network interface
2200 drivers, on Windows) will allow it to capture.
2202 For any particular link-layer network type, unless the OS supplies the
2203 FCS of a frame as part of the frame, or can be configured to do so,
2204 Ethereal - and other programs that capture raw packets, such as
2205 tcpdump - cannot capture the FCS of a frame. You will have to
2206 determine whether your OS needs to be so configured and, if so, can be
2207 so configured, configure it if necessary and possible, and make
2208 whatever changes to libpcap and the packet capture program you're
2209 using are necessary, if any, to support capturing the FCS of a frame.
2211 Most OSes do not support capturing the FCS of a frame on Ethernet, and
2212 probably do not support it on most other link-layer types. Some
2213 drivres on some OSes do support it, such as some (all?) Ethernet
2214 drivers on NetBSD and possibly the driver for Apple's gigabit Ethernet
2215 interface in Mac OS X; in those OSes, you might always get the FCS, or
2216 you might only get the FCS if you capture in promiscuous mode (you'd
2217 have to determine which is the case).
2219 Versions of Ethereal prior to 0.9.15 will not treat an Ethernet FCS in
2220 a captured packet as an FCS. 0.9.15 and later will attempt to
2221 determine whether there's an FCS at the end of the frame and, if it
2222 thinks there is, will display it as such, and will check whether it's
2223 the correct CRC-32 value or not.
2225 Q 5.45: Why does Ethereal hang after I stop a capture?
2227 A: The most likely reason for this is that Ethereal is trying to look
2228 up an IP address in the capture to convert it to a name (so that, for
2229 example, it can display the name in the source address or destination
2230 address columns), and that lookup process is taking a very long time.
2232 Ethereal calls a routine in the OS of the machine on which it's
2233 running to convert of IP addresses to the corresponding names. That
2234 routine probably does one or more of:
2235 * a search of a system file listing IP addresses and names;
2236 * a lookup using DNS;
2237 * on UNIX systems, a lookup using NIS;
2238 * on Windows systems, a NetBIOS-over-TCP query.
2240 If a DNS server that's used in an address lookup is not responding,
2241 the lookup will fail, but will only fail after a timeout while the
2242 system routine waits for a reply.
2244 In addition, on Windows systems, if the DNS lookup of the address
2245 fails, either because the server isn't responding or because there are
2246 no records in the DNS that could be used to map the address to a name,
2247 a NetBIOS-over-TCP query will be made. That query involves sending a
2248 message to the NetBIOS-over-TCP name service on that machine, asking
2249 for the name and other information about the machine. If the machine
2250 isn't running software that responds to those queries - for example,
2251 many non-Windows machines wouldn't be running that software - the
2252 lookup will only fail after a timeout. Those timeouts can cause the
2253 lookup to take a long time.
2255 If you disable network address-to-name translation - for example, by
2256 turning off the "Enable network name resolution" option in the
2257 "Capture Options" dialog box for starting a network capture - the
2258 lookups of the address won't be done, which may speed up the process
2259 of reading the capture file after the capture is stopped. You can make
2260 that setting the default by selecting "Preferences" from the "Edit"
2261 menu, turning off the "Enable network name resolution" option in the
2262 "Name resolution" options in the preferences disalog box, and using
2263 the "Save" button in that dialog box; note that this will save all
2264 your current preference settings.
2266 If Ethereal hangs when reading a capture even with network name
2267 resolution turned off, there might, for example, be a bug in one of
2268 Ethereal's dissectors for a protocol causing it to loop infinitely. If
2269 you're not running the most recent release of Ethereal, you should
2270 first upgrade to that release, as, if there's a bug of that sort, it
2271 might've been fixed in a release after the one you're running. If the
2272 hang occurs in the most recent release of Ethereal, the bug should be
2273 reported to the Ethereal developers' mailing list at
2274 ethereal-dev@ethereal.com.
2276 On UNIX-flavored OSes, please try to force Ethereal to dump core, by
2277 sending it a SIGABRT signal (usually signal 6) with the kill command,
2278 and then get a stack trace if you have a debugger installed. A stack
2279 trace can be obtained by using your debugger (gdb in this example),
2280 the Ethereal binary, and the resulting core file. Here's an example of
2281 how to use the gdb command backtrace to do so.
2284 ..... prints the stack trace
2288 The core dump file may be named "ethereal.core" rather than "core" on
2289 some platforms (e.g., BSD systems).
2291 Also, if at all possible, please send a copy of the capture file that
2292 caused the problem; when capturing packets, Ethereal normally writes
2293 captured packets to a temporary file, which will probably be in /tmp
2294 or /var/tmp on UNIX-flavored OSes, \TEMP on the main system disk
2295 (normally C:) on Windows 9x/Me/NT 4.0, and \Documents and
2296 Settings\your login name\Local Settings\Temp on the main system disk
2297 on Windows 2000/XP/Server 2003, so the capture file will probably be
2298 there. It will have a name beginning with ether, with some mixture of
2299 letters and numbers after that. Please don't send a trace file greater
2300 than 1 MB when compressed; instead, make it available via FTP or HTTP,
2301 or say it's available but leave it up to a developer to ask for it. If
2302 the trace file contains sensitive information (e.g., passwords), then
2303 please do not send it.
2305 Q 5.46: How can I search for, or filter, packets that have a
2306 particular string anywhere in them?
2308 A: If you want to do this when capturing, you can't. That's a feature
2309 that would be hard to implement in capture filters without changes to
2310 the capture filter code, which, on many platforms, is in the OS kernel
2311 and, on other platforms, is in the libpcap library.
2313 In releases prior to 0.9.14, you also can't search for, or filter,
2314 packets containing a particular string even after you've captured
2317 In 0.9.14, you can search for, but not filter, packets that have a
2318 particular string; this has been added to the "Find Frame" dialog
2319 ("Find Frame" under the "Edit" menu, or control-F).
2321 In 0.9.15 and later, you can search for those packets using either the
2322 mechanism introduced in 0.9.14 or using the new "contains" operator in
2323 filter expressions, which lets you search the entire packet or text
2324 string or byte string fields in the packet; the "contains" operator
2325 can also be used in expressions used to filter the display.
2327 Q 5.47: How do I filter a capture to see traffic for virus XXX?
2329 A: For some viruses/worms there might be a capture filter to recognize
2330 the virus traffic. Check the CaptureFilters page on the Ethereal Wiki
2331 to see if anybody's added such a filter.
2333 Note that Ethereal was not designed to be an intrusion detection
2334 system; you might be able to use it as an IDS, but in most cases
2335 software designed to be an IDS, such as Snort or Prelude, will
2336 probably work better.
2338 The Bleeding Edge of Snort has a collection of signatures for Snort to
2339 detect various viruses, worms, and the like.
2341 Please send support questions about Ethereal to the
2342 ethereal-users[AT]ethereal.com mailing list.
2343 For corrections/additions/suggestions for this web page (and not
2344 Ethereal support questions), please send email to
2345 ethereal-web[AT]ethereal.com .
2346 Last modified: Thu, November 18 2004.
git.samba.org / obnox / wireshark / wip.git / blob