- The Ethereal FAQ
+ The Wireshark FAQ
Note: This is just an ASCII snapshot of the faq and may not be up to
- date. Please go to http://www.ethereal.com/faq.html for the up
+ date. Please go to http://www.wireshark.org/faq.html for the up
to date version. The version of this snapshot can be found at
the end of this document.
INDEX
-General Questions:
+1. General Questions:
- 1.1 Where can I get help?
+ 1.1 What is Wireshark?
- 1.2 What protocols are currently supported?
+ 1.2 What's up with the name change? Is Wireshark a fork?
- 1.3 Are there any plans to support {your favorite protocol}?
+ 1.3 Where can I get help?
- 1.4 Can Ethereal read capture files from {your favorite network
+ 1.4 How much does Wireshark cost?
+
+ 1.5 Can I use Wireshark commercially?
+
+ 1.6 Can I use Wireshark as part of my commercial product?
+
+ 1.7 What protocols are currently supported?
+
+ 1.8 Are there any plans to support {your favorite protocol}?
+
+ 1.9 Can Wireshark read capture files from {your favorite network
analyzer}?
- 1.5 What devices can Ethereal use to capture packets?
+ 1.10 What devices can Wireshark use to capture packets?
- 1.6 How do you pronounce Ethereal? Where did the name come from?
+ 1.11 Does Wireshark work on Windows Me?
-Downloading Ethereal:
+ 1.12 Does Wireshark work on Windows XP?
- 2.1 I downloaded the Win32 installer, but when I try to run it, I get
- an error.
+2. Downloading Wireshark:
- 2.2 When I try to download the WinPcap driver and library, I can't get
- to the WinPcap Web site.
+ 2.1 Why do I get an error when I try to run the Win32 installer?
-Installing Ethereal:
+3. Installing Wireshark:
- 3.1 I installed an Ethereal RPM, but Ethereal doesn't seem to be
- installed; only Tethereal is installed.
+ 3.1 I installed the Wireshark RPM (or other package); why did it
+ install TShark but not Wireshark?
-Building Ethereal:
+4. Building Wireshark:
- 4.1 The configure script can't find pcap.h or bpf.h, but I have
- libpcap installed.
+ 4.1 I have libpcap installed; why did the configure script not find
+ pcap.h or bpf.h?
- 4.2 Why do I get the error
+ 4.2 Why do I get the error
dftest_DEPENDENCIES was already defined in condition TRUE, which
implies condition HAVE_PLUGINS_TRUE
- when I try to build Ethereal from CVS or a CVS snapshot?
+ when I try to build Wireshark from SVN or a SVN snapshot?
- 4.3 The link fails with a number of "Output line too long." messages
- followed by linker errors.
+ 4.3 Why does the linker fail with a number of "Output line too long."
+ messages followed by linker errors when I try to buil Wireshark?
- 4.4 The link fails on Solaris because plugin_list is undefined.
+ 4.4 When I try to build Wireshark on Solaris, why does the link fail
+ complaining that plugin_list is undefined?
- 4.5 The build fails on Windows because of conflicts between winsock.h
- and winsock2.h.
+ 4.5 When I try to build Wireshark on Windows, why does the build fail
+ because of conflicts between winsock.h and winsock2.h?
- 4.6 I'm trying to build Ethereal 0.10.0a on Windows; why is the the
- build failing with an error saying it can't find "Makefile.nmake"?
+5. Starting Wireshark:
-Using Ethereal:
+ 5.1 Why does Wireshark crash with a Bus Error when I try to run it on
+ Solaris 8?
- 5.1 When I use Ethereal to capture packets, I see only packets to and
- from my machine, or I'm not seeing all the traffic I'm expecting to
- see from or to the machine I'm trying to monitor.
+ 5.2 When I run Wireshark on Windows NT, why does it die with a Dr.
+ Watson error, reporting an "Integer division by zero" exception, when I
+ start it?
- 5.2 I can't see any TCP packets other than packets to and from my
- machine, even though another analyzer on the network sees those
- packets.
+ 5.3 When I try to run Wireshark, why does it complain about
+ sprint_realloc_objid being undefined?
- 5.3 I'm only seeing ARP packets when I try to capture traffic.
+ 5.4 When I try to run Wireshark on Windows, why does it fail to run
+ with a complaint that it can't find packet.dll?
- 5.4 I'm running Ethereal on Windows; why does some network interface
- on my machine not show up in the list of interfaces in the
- "Interface:" field in the dialog box popped up by "Capture->Start",
- and/or why does Ethereal give me an error if I try to capture on that
- interface?
+ 5.5 I've installed Wireshark from Fink on Mac OS X; why is it very slow
+ to start up?
+
+6. Crashes and other fatal errors:
+
+ 6.1 I have an XXX network card on my machine; if I try to capture on
+ it, why does my machine crash or reset itself?
+
+ 6.2 Why does my machine crash or reset itself when I select "Start"
+ from the "Capture" menu or select "Preferences" from the "Edit" menu?
+
+7. Capturing packets:
+
+ 7.1 When I use Wireshark to capture packets, why do I see only packets
+ to and from my machine, or not see all the traffic I'm expecting to see
+ from or to the machine I'm trying to monitor?
+
+ 7.2 When I capture with Wireshark, why can't I see any TCP packets
+ other than packets to and from my machine, even though another analyzer
+ on the network sees those packets?
+
+ 7.3 Why am I only seeing ARP packets when I try to capture traffic?
+
+ 7.4 Why am I not seeing any traffic when I try to capture traffic?
+
+ 7.5 Can Wireshark capture on (my T1/E1 line, SS7 links, etc.)?
+
+ 7.6 How do I put an interface into promiscuous mode?
- 5.5 I'm running Ethereal on Windows; why do no network interfaces show
+ 7.7 I can set a display filter just fine; why don't capture filters
+ work?
+
+ 7.8 I'm entering valid capture filters; why do I still get "parse
+ error" errors?
+
+ 7.9 How can I capture packets with CRC errors?
+
+ 7.10 How can I capture entire frames, including the FCS?
+
+ 7.11 I'm capturing packets on a machine on a VLAN; why don't the
+ packets I'm capturing have VLAN tags?
+
+ 7.12 Why does Wireshark hang after I stop a capture?
+
+8. Capturing packets on Windows:
+
+ 8.1 I'm running Wireshark on Windows; why does some network interface
+ on my machine not show up in the list of interfaces in the "Interface:"
+ field in the dialog box popped up by "Capture->Start", and/or why does
+ Wireshark give me an error if I try to capture on that interface?
+
+ 8.2 I'm running Wireshark on Windows; why do no network interfaces show
up in the list of interfaces in the "Interface:" field in the dialog
- box popped up by "Capture->Start"?
+ box popped up by "Capture->Start"?
+
+ 8.3 I'm running Wireshark on Windows; why doesn't my serial port/ADSL
+ modem/ISDN modem show up in the list of interfaces in the "Interface:"
+ field in the dialog box popped up by "Capture->Start"?
+
+ 8.4 I'm running Wireshark on Windows NT 4.0/Windows 2000/Windows
+ XP/Windows Server 2003; my machine has a PPP (dial-up POTS, ISDN, etc.)
+ interface, and it shows up in the "Interface" item in the "Capture
+ Options" dialog box. Why can no packets be sent on or received from
+ that network while I'm trying to capture traffic on that interface?
+
+ 8.5 I'm running Wireshark on Windows 95/98/Me, on a machine with more
+ than one network adapter of the same type; why does Wireshark show all
+ of those adapters with the same name, not letting me use any of those
+ adapters other than the first one?
+
+ 8.6 I'm running Wireshark on Windows; why am I not seeing any traffic
+ being sent by the machine running Wireshark?
+
+ 8.7 When I capture on Windows in promiscuous mode, I can see packets
+ other than those sent to or from my machine; however, those packets
+ show up with a "Short Frame" indication, unlike packets to or from my
+ machine. What should I do to arrange that I see those packets in their
+ entirety?
+
+ 8.8 I'm capturing packets on {Windows 95, Windows 98, Windows Me}; why
+ are the time stamps on packets wrong?
+
+ 8.9 I'm trying to capture 802.11 traffic on Windows; why am I not
+ seeing any packets?
- 5.6 I'm running Ethereal on Windows; why doesn't my serial port/ADSL
- modem/ISDN modem/show up in the list of interfaces in the "Interface:"
- field in the dialog box popped up by "Capture->Start"?
+ 8.10 I'm trying to capture 802.11 traffic on Windows; why am I seeing
+ packets received by the machine on which I'm capturing traffic, but not
+ packets sent by that machine?
- 5.7 I'm running Ethereal on a UNIX-flavored OS; why does some network
+ 8.11 I'm trying to capture Ethernet VLAN traffic on Windows, and I'm
+ capturing on a "raw" Ethernet device rather than a "VLAN interface", so
+ that I can see the VLAN headers; why am I seeing packets received by
+ the machine on which I'm capturing traffic, but not packets sent by
+ that machine?
+
+9. Capturing packets on UN*Xes:
+
+ 9.1 I'm running Wireshark on a UNIX-flavored OS; why does some network
interface on my machine not show up in the list of interfaces in the
"Interface:" field in the dialog box popped up by "Capture->Start",
- and/or why does Ethereal give me an error if I try to capture on that
- interface?
+ and/or why does Wireshark give me an error if I try to capture on that
+ interface?
- 5.8 I'm running Ethereal on a UNIX-flavored OS; why do no network
+ 9.2 I'm running Wireshark on a UNIX-flavored OS; why do no network
interfaces show up in the list of interfaces in the "Interface:" field
- in the dialog box popped up by "Capture->Start"?
+ in the dialog box popped up by "Capture->Start"?
- 5.9 Can Ethereal capture on (my T1/E1 line, SS7 links, etc.)?
+ 9.3 I'm capturing packets on Linux; why do the time stamps have only
+ 100ms resolution, rather than 1us resolution?
- 5.10 How do I put an interface into promiscuous mode?
+10. Capturing packets on wireless LANs:
- 5.11 I can set a display filter just fine, but capture filters don't
- work.
+ 10.1 How can I capture raw 802.11 frames, including non-data
+ (management, beacon) frames?
- 5.12 I'm entering valid capture filters, but I still get "parse error"
- errors.
+ 10.2 How do I capture on an 802.11 device in monitor mode?
- 5.13 I saved a filter and tried to use its name to filter the display,
- but I got an "Unexpected end of filter string" error.
+11. Viewing traffic:
- 5.14 Why am I seeing lots of packets with incorrect TCP checksums?
+ 11.1 Why am I seeing lots of packets with incorrect TCP checksums?
- 5.15 I've just installed Ethereal, and the traffic on my local LAN is
- boring.
+ 11.2 I've just installed Wireshark, and the traffic on my local LAN is
+ boring. Where can I find more interesting captures?
- 5.16 When I run Ethereal on Solaris 8, it dies with a Bus Error when I
- start it.
+ 11.3 Why doesn't Wireshark correctly identify RTP packets? It shows
+ them only as UDP.
- 5.17 When I run Tethereal with the "-x" option, it crashes with an
- error "** ERROR **: file print.c: line 691 (print_line): should not be
- reached".
+ 11.4 Why doesn't Wireshark show Yahoo Messenger packets in captures
+ that contain Yahoo Messenger traffic?
- 5.18 When I run Ethereal on Windows NT, it dies with a Dr. Watson
- error, reporting an "Integer division by zero" exception, when I start
- it.
+12. Filtering traffic:
- 5.19 When I try to run Ethereal, it complains about
- sprint_realloc_objid being undefined.
+ 12.1 I saved a filter and tried to use its name to filter the display;
+ why do I get an "Unexpected end of filter string" error?
- 5.20 I'm running Ethereal on Linux; why do my time stamps have only
- 100ms resolution, rather than 1us resolution?
+ 12.2 How can I search for, or filter, packets that have a particular
+ string anywhere in them?
- 5.21 I'm capturing packets on {Windows 95, Windows 98, Windows Me};
- why are the time stamps on packets wrong?
+ 12.3 How do I filter a capture to see traffic for virus XXX?
- 5.22 When I try to run Ethereal on Windows, it fails to run because it
- can't find packet.dll.
+1. General Questions
- 5.23 I'm running Ethereal on Windows NT/2000/XP/Server; my machine has
- a PPP (dial-up POTS, ISDN, etc.) interface, and it shows up in the
- "Interface" item in the "Capture Options" dialog box. Why can no
- packets be sent on or received from that network while I'm trying to
- capture traffic on that interface?
+ Q 1.1: What is Wireshark?
- 5.24 I'm running Ethereal on Windows 95/98/Me, on a machine with more
- than one network adapter of the same type; Ethereal shows all of those
- adapters with the same name, but I can't use any of those adapters
- other than the first one.
+ A: Gerald Combs, the creator of Ethereal®, has initiated the Wireshark
+ network protocol analyzer project, a successor to Ethereal®. The
+ Ethereal® core developer team has moved with Gerald to the Wireshark
+ project. It is the world's most popular network protocol analyzer. It
+ has a rich and powerful feature set, and runs on most computing
+ platforms including Windows, OS X, and Linux. It is freely available as
+ open source, and is released under the GNU General Public License.
- 5.25 I'm running Ethereal on Windows, and I'm not seeing any traffic
- being sent by the machine running Ethereal.
+ For more information, please see the About Wireshark page.
- 5.26 I'm trying to capture traffic but I'm not seeing any.
+ Q 1.2: What's up with the name change? Is Wireshark a fork?
- 5.27 I have an XXX network card on my machine; if I try to capture on
- it, my machine crashes or resets itself.
+ A: In May of 2006, the original author of Ethereal® went to work for
+ CACE Technologies (best known for WinPcap). Unfortunately, he had to
+ leave the Ethereal® trademarks behind.
- 5.28 My machine crashes or resets itself when I select "Start" from
- the "Capture" menu or select "Preferences" from the "Edit" menu.
+ This left the project in an awkward position. The only reasonable way
+ to ensure the continued success of the project was to change the name.
+ This is how Wireshark was born.
- 5.29 Does Ethereal work on Windows Me?
+ Wireshark is almost (but not quite) a fork. Normally a "fork" of an
+ open source project results in two names, web sites, development teams,
+ support infrastructures, etc. This is the case with Wireshark except
+ for one notable exception -- every member of the core development team
+ is now working on Wireshark. More information on the name change can be
+ found here:
+ *
+ *
- 5.30 Does Ethereal work on Windows XP?
+ Q 1.3: Where can I get help?
- 5.31 Why doesn't Ethereal correctly identify RTP packets? It shows
- them only as UDP.
+ A: Community support is available on the wireshark-users mailing list.
+ Subscription information and archives for all of Wireshark's mailing
+ lists can be found at http://www.wireshark.org/mailman/listinfo. An IRC
+ channel dedicated to Wireshark can be found at
+ irc://irc.freenode.net/wireshark.
- 5.32 Why doesn't Ethereal show Yahoo Messenger packets in captures
- that contain Yahoo Messenger traffic?
+ Commercial support, training, and development services are available
+ from CACE Technologies.
- 5.33 Why do I get the error
+ Q 1.4: How much does Wireshark cost?
- Gdk-ERROR **: Palettized display (256-colour) mode not supported on
- Windows.
- aborting....
+ A: Wireshark is "free software"; you can download it without paying any
+ license fee. The version of Wireshark you download isn't a "demo"
+ version, with limitations not present in a "full" version; it is the
+ full version.
- when I try to run Ethereal on Windows?
+ The license under which Wireshark is issued is the GNU General Public
+ License. See the GNU GPL FAQ for some more information.
- 5.34 When I capture on Windows in promiscuous mode, I can see packets
- other than those sent to or from my machine; however, those packets
- show up with a "Short Frame" indication, unlike packets to or from my
- machine. What should I do to arrange that I see those packets in their
- entirety?
-
- 5.35 I'm capturing packets on a machine on a VLAN; why don't the
- packets I'm capturing have VLAN tags?
-
- 5.36 How can I capture raw 802.11 packets, including non-data
- (management, beacon) packets?
-
- 5.37 I'm trying to capture 802.11 traffic on Windows; why am I not
- seeing any packets?
-
- 5.38 I'm trying to capture 802.11 traffic on Windows; why am I seeing
- packets received by the machine on which I'm capturing traffic, but
- not packets sent by that machine?
-
- 5.39 How can I capture packets with CRC errors?
-
- 5.40 How can I capture entire frames, including the FCS?
-
- 5.41 Ethereal hangs after I stop a capture.
-
- 5.42 How can I search for, or filter, packets that have a particular
- string anywhere in them?
-
-General Questions
-
- Q 1.1: Where can I get help?
-
- A: Support is available on the ethereal-users mailing list.
- Subscription information and archives for all of Ethereal's mailing
- lists can be found at http://www.ethereal.com/lists
-
- Q 1.2: What protocols are currently supported?
-
- A: There are currently 442 supported protocols and media, listed
- below. Descriptions can be found in the ethereal(1) man page.
-
- 802.1q Virtual LAN
- 802.1x Authentication
- AAL type 2 signalling protocol - Capability set 1 (Q.2630.1)
- AFS (4.0) Replication Server call declarations
- ANSI A-I/F BSMAP
- ANSI A-I/F DTAP
- ANSI IS-637-A (SMS) Teleservice Layer
- ANSI IS-637-A (SMS) Transport Layer
- ANSI IS-683-A (OTA (Mobile))
- ANSI Mobile Application Part
- AOL Instant Messenger
- ARCNET
- ATM
- ATM AAL1
- ATM AAL3/4
- ATM LAN Emulation
- ATM OAM AAL
- AVS WLAN Capture header
- Ad hoc On-demand Distance Vector Routing Protocol
- Address Resolution Protocol
- Aggregate Server Access Protocol
- Alert Standard Forum
- Alteon - Transparent Proxy Cache Protocol
- Andrew File System (AFS)
- Apache JServ Protocol v1.3
- AppleTalk Filing Protocol
- AppleTalk Session Protocol
- AppleTalk Transaction Protocol packet
- Appletalk Address Resolution Protocol
- Application Configuration Access Protocol
- Async data over ISDN (V.120)
- Authentication Header
- BACnet Virtual Link Control
- BSS GPRS Protocol
- BSSAP/BSAP
- Banyan Vines ARP
- Banyan Vines Echo
- Banyan Vines Fragmentation Protocol
- Banyan Vines ICP
- Banyan Vines IP
- Banyan Vines IPC
- Banyan Vines LLC
- Banyan Vines RTP
- Banyan Vines SPP
- Bearer Independent Call Control
- Bi-directional Fault Detection Control Message
- Blocks Extensible Exchange Protocol
- Boardwalk
- Boot Parameters
- Bootstrap Protocol
- Border Gateway Protocol
- Building Automation and Control Network APDU
- Building Automation and Control Network NPDU
- CCSDS
- CDS Clerk Server Calls
- Check Point High Availability Protocol
- Checkpoint FW-1
- Cisco Auto-RP
- Cisco Discovery Protocol
- Cisco Group Management Protocol
- Cisco HDLC
- Cisco Hot Standby Router Protocol
- Cisco ISL
- Cisco Interior Gateway Routing Protocol
- Cisco NetFlow
- Cisco SLARP
- Clearcase NFS
- CoSine IPNOS L2 debug output
- Common Open Policy Service
- Common Unix Printing System (CUPS) Browsing Protocol
- Connectionless Lightweight Directory Access Protocol
- Cross Point Frame Injector
- DCE DFS Calls
- DCE Distributed Time Service Local Server
- DCE Distributed Time Service Provider
- DCE Name Service
- DCE RPC
- DCE Security ID Mapper
- DCE/RPC BOS Server
- DCE/RPC BUDB
- DCE/RPC BUTC
- DCE/RPC CDS Solicitation
- DCE/RPC Conversation Manager
- DCE/RPC Endpoint Mapper
- DCE/RPC Endpoint Mapper4
- DCE/RPC FLDB
- DCE/RPC FLDB UBIK TRANSFER
- DCE/RPC FLDB UBIKVOTE
- DCE/RPC ICL RPC
- DCE/RPC Kerberos V
- DCE/RPC RS_ACCT
- DCE/RPC RS_BIND
- DCE/RPC RS_MISC
- DCE/RPC RS_PROP_ACCT
- DCE/RPC RS_UNIX
- DCE/RPC Remote Management
- DCE/RPC Repserver Calls
- DCE/RPC TokenServer Calls
- DCE/RPC UpServer
- DCOM OXID Resolver
- DCOM Remote Activation
- DEC Spanning Tree Protocol
- DHCPv6
- DNS Control Program Server
- Data
- Data Link SWitching
- Data Stream Interface
- Datagram Delivery Protocol
- Diameter Protocol
- Distance Vector Multicast Routing Protocol
- Distcc Distributed Compiler
- Distributed Checksum Clearinghouse Prototocl
- Domain Name Service
- Dynamic DNS Tools Protocol
- Echo
- Encapsulating Security Payload
- Enhanced Interior Gateway Routing Protocol
- EtherNet/IP (Industrial Protocol)
- Ethernet
- Ethernet over IP
- Extensible Authentication Protocol
- FC Extended Link Svc
- FC Fabric Configuration Server
- FCIP
- FTP Data
- FTServer Operations
- Fiber Distributed Data Interface
- Fibre Channel
- Fibre Channel Common Transport
- Fibre Channel Fabric Zone Server
- Fibre Channel Name Server
- Fibre Channel Protocol for SCSI
- Fibre Channel SW_ILS
- Fibre Channel Security Protocol
- Fibre Channel Single Byte Command
- File Transfer Protocol (FTP)
- Financial Information eXchange Protocol
- Frame
- Frame Relay
- GARP Multicast Registration Protocol
- GARP VLAN Registration Protocol
- GPRS Network service
- GPRS Tunneling Protocol
- GSM A-I/F BSSMAP
- GSM A-I/F DTAP
- GSM A-I/F RP
- GSM Mobile Application Part
- GSM SMS TPDU (GSM 03.40)
- General Inter-ORB Protocol
- Generic Routing Encapsulation
- Generic Security Service Application Program Interface
- Gnutella Protocol
- H225
- H245
- H4501
- HP Extended Local-Link Control
- HP Remote Maintenance Protocol
- Hummingbird NFS Daemon
- HyperSCSI
- Hypertext Transfer Protocol
- ICQ Protocol
- IEEE 802.11 wireless LAN
- IEEE 802.11 wireless LAN management frame
- ILMI
- IP Over FC
- IP Payload Compression
- IPX Message
- IPX Routing Information Protocol
- IPX WAN
- ISDN
- ISDN Q.921-User Adaptation Layer
- ISDN User Part
- ISO 10589 ISIS InTRA Domain Routeing Information Exchange Protocol
- ISO 8073 COTP Connection-Oriented Transport Protocol
- ISO 8327-1 OSI Session Protocol
- ISO 8473 CLNP ConnectionLess Network Protocol
- ISO 8602 CLTP ConnectionLess Transport Protocol
- ISO 9542 ESIS Routeing Information Exchange Protocol
- ITU-T Recommendation H.261
- ITU-T Recommendation H.263 RTP Payload header (RFC2190)
- InMon sFlow
- Intel ANS probe
- Intelligent Platform Management Interface
- Inter-Access-Point Protocol
- Interbase
- Internet Cache Protocol
- Internet Content Adaptation Protocol
- Internet Control Message Protocol
- Internet Control Message Protocol v6
- Internet Group Management Protocol
- Internet Group membership Authentication Protocol
- Internet Message Access Protocol
- Internet Printing Protocol
- Internet Protocol
- Internet Protocol Version 6
- Internet Relay Chat
- Internet Security Association and Key Management Protocol
- Internetwork Packet eXchange
- Jabber XML Messaging
- Java RMI
- Java Serialization
- Kerberos
- Kerberos Administration
- Kernel Lock Manager
- LWAP Control Message
- LWAPP Encapsulated Packet
- LWAPP Layer 3 Packet
- Label Distribution Protocol
- Laplink
- Layer 2 Tunneling Protocol
- Lightweight Directory Access Protocol
- Line Printer Daemon Protocol
- Link Access Procedure Balanced (LAPB)
- Link Access Procedure Balanced Ethernet (LAPBETHER)
- Link Access Procedure, Channel D (LAPD)
- Link Aggregation Control Protocol
- Link Management Protocol (LMP)
- Linux cooked-mode capture
- Local Management Interface
- LocalTalk Link Access Protocol
- Logical-Link Control
- Lucent/Ascend debug output
- MDS Header
- MMS Message Encapsulation
- MS Kpasswd
- MS Proxy Protocol
- MSN Messenger Service
- MSNIP: Multicast Source Notification of Interest Protocol
- MTP 2 Transparent Proxy
- MTP 2 User Adaptation Layer
- MTP 3 User Adaptation Layer
- MTP2 Peer Adaptation Layer
- Message Transfer Part Level 2
- Message Transfer Part Level 3
- Message Transfer Part Level 3 Management
- Microsoft Directory Replication Service
- Microsoft Distributed File System
- Microsoft Exchange MAPI
- Microsoft Local Security Architecture
- Microsoft Local Security Architecture (Directory Services)
- Microsoft Messenger Service
- Microsoft Network Logon
- Microsoft Registry
- Microsoft Security Account Manager
- Microsoft Server Service
- Microsoft Service Control
- Microsoft Spool Subsystem
- Microsoft Task Scheduler Service
- Microsoft Telephony API Service
- Microsoft Windows Browser Protocol
- Microsoft Windows Lanman Remote API Protocol
- Microsoft Windows Logon Protocol
- Microsoft Workstation Service
- Mobile IP
- Mobile IPv6
- Modbus/TCP
- Mount Service
- MultiProtocol Label Switching Header
- Multicast Router DISCovery protocol
- Multicast Source Discovery Protocol
- MySQL Protocol
- NFSACL
- NFSAUTH
- NIS+
- NIS+ Callback
- NSPI
- NTLM Secure Service Provider
- Name Binding Protocol
- Name Management Protocol over IPX
- NetBIOS
- NetBIOS Datagram Service
- NetBIOS Name Service
- NetBIOS Session Service
- NetBIOS over IPX
- NetWare Core Protocol
- NetWare Link Services Protocol
- Network Data Management Protocol
- Network File System
- Network Lock Manager Protocol
- Network News Transfer Protocol
- Network Status Monitor CallBack Protocol
- Network Status Monitor Protocol
- Network Time Protocol
- Nortel SONMP
- Novell Distributed Print System
- Null/Loopback
- Open Shortest Path First
- OpenBSD Encapsulating device
- OpenBSD Packet Filter log file
- OpenBSD Packet Filter log file, pre 3.4
- PC NFS
- PPP Bandwidth Allocation Control Protocol
- PPP Bandwidth Allocation Protocol
- PPP CDP Control Protocol
- PPP Callback Control Protocol
- PPP Challenge Handshake Authentication Protocol
- PPP Compressed Datagram
- PPP Compression Control Protocol
- PPP IP Control Protocol
- PPP IPv6 Control Protocol
- PPP Link Control Protocol
- PPP MPLS Control Protocol
- PPP Multilink Protocol
- PPP Multiplexing
- PPP Password Authentication Protocol
- PPP VJ Compression
- PPP-over-Ethernet Discovery
- PPP-over-Ethernet Session
- PPPMux Control Protocol
- Packed Encoding Rules (ASN.1 X.691)
- Point-to-Point Protocol
- Point-to-Point Tunnelling Protocol
- Portmap
- Post Office Protocol
- Pragmatic General Multicast
- Prism
- Privilege Server operations
- Protocol Independent Multicast
- Q.2931
- Q.931
- Q.933
- Quake II Network Protocol
- Quake III Arena Network Protocol
- Quake Network Protocol
- QuakeWorld Network Protocol
- Qualified Logical Link Control
- RFC 2250 MPEG1
- RFC 2833 RTP Event
- RIPng
- RPC Browser
- RS Interface properties
- RSTAT
- RSYNC File Synchroniser
- RX Protocol
- Radio Access Network Application Part
- Radius Protocol
- Raw packet data
- Real Time Streaming Protocol
- Real-Time Transport Protocol
- Real-time Transport Control Protocol
- Registry Server Attributes Manipulation Interface
- Registry server administration operations.
- Remote Management Control Protocol
- Remote Override interface
- Remote Procedure Call
- Remote Program Load
- Remote Quota
- Remote Shell
- Remote Shutdown
- Remote Wall protocol
- Remote sec_login preauth interface.
- Resource ReserVation Protocol (RSVP)
- Rlogin Protocol
- Routing Information Protocol
- Routing Table Maintenance Protocol
- SADMIND
- SCSI
- SEBEK - Kernel Data Capture
- SGI Mount Service
- SMB (Server Message Block Protocol)
- SMB MailSlot Protocol
- SMB Pipe Protocol
- SNA-over-Ethernet
- SNMP Multiplex Protocol
- SPNEGO-KRB5
- SPRAY
- SS7 SCCP-User Adaptation Layer
- SSCOP
- SSH Protocol
- Secure Socket Layer
- Sequenced Packet eXchange
- Service Advertisement Protocol
- Service Location Protocol
- Session Announcement Protocol
- Session Description Protocol
- Session Initiation Protocol
- Session Initiation Protocol (SIP as raw text)
- Short Message Peer to Peer
- Signalling Connection Control Part
- Signalling Connection Control Part Management
- Simple Mail Transfer Protocol
- Simple Network Management Protocol
- Simple Traversal of UDP Through NAT
- Sinec H1 Protocol
- Skinny Client Control Protocol
- SliMP3 Communication Protocol
- Socks Protocol
- Spanning Tree Protocol
- Spnego
- Stream Control Transmission Protocol
- Synchronous Data Link Control (SDLC)
- Syslog message
- Systems Network Architecture
- Systems Network Architecture XID
- T38
- TACACS
- TACACS+
- TEREDO Tunneling IPv6 over UDP through NATs
- TPKT
- Tabular Data Stream
- Tazmen Sniffer Protocol
- Telnet
- Time Protocol
- Time Synchronization Protocol
- Token-Ring
- Token-Ring Media Access Control
- Transaction Capabilities Application Part
- Transmission Control Protocol
- Transparent Network Substrate Protocol
- Trivial File Transfer Protocol
- UDP Encapsulation of IPsec Packets
- Universal Computer Protocol
- User Datagram Protocol
- Virtual Router Redundancy Protocol
- Virtual Trunking Protocol
- WAP Binary XML
- Web Cache Coordination Protocol
- Wellfleet Breath of Life
- Wellfleet Compression
- Wellfleet HDLC
- Who
- Windows 2000 DNS
- Wireless Session Protocol
- Wireless Transaction Protocol
- Wireless Transport Layer Security
- X Display Manager Control Protocol
- X.25
- X.25 over TCP
- X.29
- X11
- Xyplex
- Yahoo Messenger Protocol
- Yahoo YMSG Messenger Protocol
- Yellow Pages Bind
- Yellow Pages Passwd
- Yellow Pages Service
- Yellow Pages Transfer
- Zebra Protocol
- Zone Information Protocol
- eDonkey Protocol
- iSCSI
- iSNS
-
- Q 1.3: Are there any plans to support {your favorite protocol}?
-
- A: Support for particular protocols is added to Ethereal as a result
- of people contributing that support; no formal plans for adding
- support for particular protocols in particular future releases exist.
-
- Q 1.4: Can Ethereal read capture files from {your favorite network
+ Q 1.5: Can I use Wireshark commercially?
+
+ A: Yes, if, for example, you mean "I work for a commercial
+ organization; can I use Wireshark to capture and analyze network
+ traffic in our company's networks or in our customer's networks?"
+
+ If you mean "Can I use Wireshark as part of my commercial product?",
+ see the next entry in the FAQ.
+
+ Q 1.6: Can I use Wireshark as part of my commercial product?
+
+ A: As noted, Wireshark is licensed under the GNU General Public
+ License. The GPL imposes conditions on your use of GPL'ed code in your
+ own products; you cannot, for example, make a "derived work" from
+ Wireshark, by making modifications to it, and then sell the resulting
+ derived work and not allow recipients to give away the resulting work.
+ You must also make the changes you've made to the Wireshark source
+ available to all recipients of your modified version; those changes
+ must also be licensed under the terms of the GPL. See the GPL FAQ for
+ more details; in particular, note the answer to the question about
+ modifying a GPLed program and selling it commercially, and the question
+ about linking GPLed code with other code to make a proprietary program.
+
+ You can combine a GPLed program such as Wireshark and a commercial
+ program as long as they communicate "at arm's length", as per this item
+ in the GPL FAQ.
+
+ Q 1.7: What protocols are currently supported?
+
+ A: There are currently hundreds of supported protocols and media.
+ Details can be found in the wireshark(1) man page.
+
+ Q 1.8: Are there any plans to support {your favorite protocol}?
+
+ A: Support for particular protocols is added to Wireshark as a result
+ of people contributing that support; no formal plans for adding support
+ for particular protocols in particular future releases exist.
+
+ Q 1.9: Can Wireshark read capture files from {your favorite network
analyzer}?
- A: Support for particular protocols is added to Ethereal as a result
- of people contributing that support; no formal plans for adding
- support for particular protocols in particular future releases exist.
+ A: Support for particular protocols is added to Wireshark as a result
+ of people contributing that support; no formal plans for adding support
+ for particular protocols in particular future releases exist.
- If a network analyzer writes out files in a format already supported
- by Ethereal (e.g., in libpcap format), Ethereal may already be able to
- read them, unless the analyzer has added its own proprietary
- extensions to that format.
+ If a network analyzer writes out files in a format already supported by
+ Wireshark (e.g., in libpcap format), Wireshark may already be able to
+ read them, unless the analyzer has added its own proprietary extensions
+ to that format.
If a network analyzer writes out files in its own format, or has added
- proprietary extensions to another format, in order to make Ethereal
+ proprietary extensions to another format, in order to make Wireshark
read captures from that network analyzer, we would either have to have
a specification for the file format, or the extensions, sufficient to
give us enough information to read the parts of the file relevant to
- Ethereal, or would need at least one capture file in that format AND a
+ Wireshark, or would need at least one capture file in that format AND a
detailed textual analysis of the packets in that capture file (showing
- packet time stamps, packet lengths, and the top-level packet header)
- in order to reverse-engineer the file format.
+ packet time stamps, packet lengths, and the top-level packet header) in
+ order to reverse-engineer the file format.
Note that there is no guarantee that we will be able to
reverse-engineer a capture file format.
- Q 1.5: What devices can Ethereal use to capture packets?
+ Q 1.10: What devices can Wireshark use to capture packets?
- A: Ethereal can read live data from Ethernet, Token-Ring, FDDI, serial
- (PPP and SLIP) (if the OS on which it's running allows Ethereal to do
+ A: Wireshark can read live data from Ethernet, Token-Ring, FDDI, serial
+ (PPP and SLIP) (if the OS on which it's running allows Wireshark to do
so), 802.11 wireless LAN (if the OS on which it's running allows
- Ethereal to do so), ATM connections (if the OS on which it's running
- allows Ethereal to do so), and the "any" device supported on Linux by
- recent versions of libpcap. See the list of supported capture media on
- various OSes for details (several items in there say "Unknown", which
- doesn't mean "Ethereal can't capture on them", it means "we don't know
- whether it can capture on them"; we expect that it will be able to
- capture on many of them, but we haven't tried it ourselves - if you
- try one of those types and it works, please send an update to
- _EWEB_MAILTO).
+ Wireshark to do so), ATM connections (if the OS on which it's running
+ allows Wireshark to do so), and the "any" device supported on Linux by
+ recent versions of libpcap.
It can also read a variety of capture file formats, including:
- * libpcap/tcpdump
- * Sun snoop/atmsnoop
- * Shomiti/Finisar Surveyor
- * LanAlyzer
- * DOS-based Sniffer (compressed and uncompressed)
- * MS Network Monitor
- * AIX iptrace
- * NetXray and Windows-based Sniffer
- * EtherPeek/TokenPeek/AiroPeek
- * RADCOM WAN/LAN analyzer
- * Lucent/Ascend debug output
- * Toshiba ISDN router "snoop" output
- * HPUX nettl
- * ISDN4BSD "i4btrace" utility.
- * Cisco Secure IDS
- * pppd log files (pppdump format)
- * VMS TCPIPtrace
- * DBS Etherwatch
- * Visual Networks' Visual UpTime
- * CoSine L2 debug
+ * AG Group/WildPackets EtherPeek/TokenPeek/AiroPeek/EtherHelp/Packet
+ Grabber captures
+ * AIX's iptrace captures
+ * Accellent's 5Views LAN agent output
+ * Cinco Networks NetXRay captures
+ * Cisco Secure Intrusion Detection System IPLog output
+ * CoSine L2 debug output
+ * DBS Etherwatch VMS text output
+ * Endace Measurement Systems' ERF format captures
+ * EyeSDN USB S0 traces
+ * HP-UX nettl captures
+ * ISDN4BSD project i4btrace captures
+ * Linux Bluez Bluetooth stack hcidump -w traces
+ * Lucent/Ascend router debug output
+ * Microsoft Network Monitor captures
+ * Network Associates Windows-based Sniffer captures
+ * Network General/Network Associates DOS-based Sniffer (compressed or
+ uncompressed) captures
+ * Network Instruments Observer version 9 captures
+ * Novell LANalyzer captures
+ * RADCOM's WAN/LAN analyzer captures
+ * Shomiti/Finisar Surveyor captures
+ * Toshiba's ISDN routers dump output
+ * VMS TCPIPtrace/TCPtrace/UCX$TRACE output
+ * Visual Networks' Visual UpTime traffic capture
+ * libpcap, tcpdump and various other tools using tcpdump's capture
+ format
+ * snoop and atmsnoop output
so that it can read traces from various network types, as captured by
other applications or equipment, even if it cannot itself capture on
those network types.
- Q 1.6: How do you pronounce Ethereal? Where did the name come from?
+ Q 1.11: Does Wireshark work on Windows Me?
+
+ A: Yes, but if you want to capture packets, you will need to install
+ the latest version of WinPcap, as 2.02 and earlier versions of WinPcap
+ didn't support Windows Me. You should also install the latest version
+ of Wireshark as well.
- A: The English pronunciation can be found in Merriam-Webster's online
- dictionary at
- http://www.m-w.com/cgi-bin/dictionary?book=Dictionary&va=ethereal.
+ Q 1.12: Does Wireshark work on Windows XP?
- According to the book "Computer Networks" by Andrew Tannenbaum,
- Ethernet was named after the "luminiferous ether" which was once
- thought to carry electromagnetic radiation. Taking that into
- consideration, Ethereal seemed like an appropriate name for an
- Ethernet analyzer.
+ A: Yes, but if you want to capture packets, you will need to install
+ the latest version of WinPcap, as 2.2 and earlier versions of WinPcap
+ didn't support Windows XP.
-Downloading Ethereal
+2. Downloading Wireshark
- Q 2.1: I downloaded the Win32 installer, but when I try to run it, I
- get an error.
+ Q 2.1: Why do I get an error when I try to run the Win32 installer?
A: The program you used to download it may have downloaded it
incorrectly. Web browsers sometimes may do this.
mode rather than ASCII mode, by using the binary command before
transferring the file.
- Q 2.2: When I try to download the WinPcap driver and library, I can't
- get to the WinPcap Web site.
-
- A: As is the case with all Web sites, that site won't necessarily
- always be accessible; the server may be down due to a problem or down
- for maintenance, or there may be a networking problem between you and
- the server. You should try again later, or try the local mirror or the
- Wiretapped.net mirror.
-
-Installing Ethereal
+3. Installing Wireshark
- Q 3.1: I installed an Ethereal RPM, but Ethereal doesn't seem to be
- installed; only Tethereal is installed.
+ Q 3.1: I installed the Wireshark RPM (or other package); why did it
+ install TShark but not Wireshark?
- A: Older versions of the Red Hat RPMs for Ethereal put only the
- non-GUI components into the ethereal RPM, the fact that Ethereal is a
- GUI program nonwithstanding; newer versions make it a bit clearer by
- giving that RPM a name starting with ethereal-base.
+ A: Many distributions have separate Wireshark packages, one for non-GUI
+ components such as TShark, editcap, dumpcap, etc. and one for the GUI.
+ If this is the case on your system, there's probably a separate package
+ named wireshark-gnome or wireshark-gtk+. Find it and install it.
- In those older versions, there's a separate ethereal-gnome RPM that
- includes GUI components such as Ethereal itself, the fact that
- Ethereal doesn't use GNOME nonwithstanding; newer versions make it a
- bit clearer by giving that RPM a name starting with ethereal-gtk+.
+4. Building Wireshark
- Find the ethereal-gnome or ethereal-gtk+ RPM, and install that also.
-
-Building Ethereal
-
- Q 4.1: The configure script can't find pcap.h or bpf.h, but I have
- libpcap installed.
+ Q 4.1: I have libpcap installed; why did the configure script not find
+ pcap.h or bpf.h?
A: Are you sure pcap.h and bpf.h are installed? The official
distribution of libpcap only installs the libpcap.a library file when
dftest_DEPENDENCIES was already defined in condition TRUE, which
implies condition HAVE_PLUGINS_TRUE
- when I try to build Ethereal from CVS or a CVS snapshot?
+ when I try to build Wireshark from SVN or a SVN snapshot?
A: You probably have automake 1.5 installed on your machine (the
command automake --version will report the version of automake on your
machine). There is a bug in that version of automake that causes this
problem; upgrade to a later version of automake (1.6 or later).
- Q 4.3: The link fails with a number of "Output line too long."
- messages followed by linker errors.
+ Q 4.3: Why does the linker fail with a number of "Output line too
+ long." messages followed by linker errors when I try to buil Wireshark?
A: The version of the sed command on your system is incapable of
handling very long lines. On Solaris, for example, /usr/bin/sed has a
searching the directory with the version of sed that came with the OS
should make the problem go away.
- Q 4.4: The link fails on Solaris because plugin_list is undefined.
+ Q 4.4: When I try to build Wireshark on Solaris, why does the link fail
+ complaining that plugin_list is undefined?
A: This appears to be due to a problem with some versions of the GTK+
and GLib packages from www.sunfreeware.org; un-install those packages,
from The Written Word, or the versions from Sun's GNOME distribution,
or the versions from the supplemental software CD that comes with the
Solaris media kit, or build them from source from the GTK Web site.
- Then re-run the configuration script, and try rebuilding Ethereal. (If
+ Then re-run the configuration script, and try rebuilding Wireshark. (If
you get the 1.2.10 versions from www.sunfreeware.org, and the problem
persists, un-install them and try installing one of the other versions
mentioned.)
- Q 4.5: The build fails on Windows because of conflicts between
- winsock.h and winsock2.h.
+ Q 4.5: When I try to build Wireshark on Windows, why does the build
+ fail because of conflicts between winsock.h and winsock2.h?
- A: As of Ethereal 0.9.5, you must install WinPcap 2.3 or later, and
+ A: As of Wireshark 0.9.5, you must install WinPcap 2.3 or later, and
the corresponding version of the developer's pack, in order to be able
- to compile Ethereal; it will not compile with older versions of the
+ to compile Wireshark; it will not compile with older versions of the
developer's pack. The symptoms of this failure are conflicts between
- definitions in winsock.h and in winsock2.h; Ethereal uses winsock2.h,
+ definitions in winsock.h and in winsock2.h; Wireshark uses winsock2.h,
but pre-2.3 versions of the WinPcap developer's packet use winsock.h.
- (2.3 uses winsock2.h, so if Ethereal were to use winsock.h, it would
+ (2.3 uses winsock2.h, so if Wireshark were to use winsock.h, it would
not be able to build with current versions of the WinPcap developer's
pack.)
Note that the installed version of the developer's pack should be the
same version as the version of WinPcap you have installed.
- Q 4.6: I'm trying to build Ethereal 0.10.0a on Windows; why is the the
- build failing with an error saying it can't find "Makefile.nmake"?
+5. Starting Wireshark
+
+ Q 5.1: Why does Wireshark crash with a Bus Error when I try to run it
+ on Solaris 8?
+
+ A: Some versions of the GTK+ library from www.sunfreeware.org appear to
+ be buggy, causing Wireshark to drop core with a Bus Error. Un-install
+ those packages, and try getting the 1.2.10 version from that site, or
+ the version from The Written Word, or the version from Sun's GNOME
+ distribution, or the version from the supplemental software CD that
+ comes with the Solaris media kit, or build it from source from the GTK
+ Web site. Update the GLib library to the 1.2.10 version, from the same
+ source, as well. (If you get the 1.2.10 versions from
+ www.sunfreeware.org, and the problem persists, un-install them and try
+ installing one of the other versions mentioned.)
+
+ Similar problems may exist with older versions of GTK+ for earlier
+ versions of Solaris.
+
+ Q 5.2: When I run Wireshark on Windows NT, why does it die with a Dr.
+ Watson error, reporting an "Integer division by zero" exception, when I
+ start it?
+
+ A: In at least some case, this appears to be due to using the default
+ VGA driver; if that's not the correct driver for your video card, try
+ running the correct driver for your video card.
+
+ Q 5.3: When I try to run Wireshark, why does it complain about
+ sprint_realloc_objid being undefined?
+
+ A: Wireshark can only be linked with version 4.2.2 or later of UCD
+ SNMP. Your version of Wireshark was dynamically linked with such a
+ version of UCD SNMP; however, you have an older version of UCD SNMP
+ installed, which means that when Wireshark is run, it tries to link to
+ the older version, and fails. You will have to replace that version of
+ UCD SNMP with version 4.2.2 or a later version.
+
+ Q 5.4: When I try to run Wireshark on Windows, why does it fail to run
+ with a complaint that it can't find packet.dll?
+
+ A: In older versions of Wireshark, there were two binary distributions
+ available for Windows, one that supported capturing packets, and one
+ that didn't. The version that supported capturing packets required that
+ you install the WinPcap driver; if you didn't install it, it would fail
+ to run because it couldn't find packet.dll.
+
+ The current version of Wireshark has only one binary distribution for
+ Windows; that version will check whether WinPcap is installed and, if
+ it's not, will disable support for packet capture.
+
+ The WinPcap driver and libraries can be downloaded from the WinPcap Web
+ site or the Wiretapped.net mirror of the WinPcap site.
+
+ Q 5.5: I've installed Wireshark from Fink on Mac OS X; why is it very
+ slow to start up?
+
+ A: When an application is installed on OS X, prior to 10.4, it is
+ usually "prebound" to speed up launching the application. (That's what
+ the "Optimizing" phase of installation is.) Fink normally performs
+ prebinding automatically when you install a package. However, in some
+ rare cases, for whatever reason the prebinding caches get corrupt, and
+ then not only does prebinding fail, but startup actually becomes much
+ slower, because the system tries in vain to perform prebinding "on the
+ fly" as you launch the application. This fails, causing sometimes huge
+ delays. To fix the prebinding caches, run the command
+ sudo /sw/var/lib/fink/prebound/update-package-prebinding.pl -f
+
+6. Crashes and other fatal errors
+
+ Q 6.1: I have an XXX network card on my machine; if I try to capture on
+ it, why does my machine crash or reset itself?
- A: There was a bug in the 0.10.0a distribution that caused
- "tools\Makefile.nmake" not to be in the source code release. You can
- download it with the URL
- http://www.ethereal.com/cgi-bin/viewcvs.cgi/*checkout*/ethereal/tools/
- Makefile.nmake?rev=1.5. Put it into "tools\Makefile.nmake" and try the
- build again.
+ A: This is almost certainly a problem with one or more of:
+ * the operating system you're using;
+ * the device driver for the interface you're using;
+ * the libpcap/WinPcap library and, if this is Windows, the WinPcap
+ device driver;
+
+ so:
+ * if you are using Windows, see the WinPcap support page - check the
+ "Submitting bugs" section;
+ * if you are using some Linux distribution, some version of BSD, or
+ some other UNIX-flavored OS, you should report the problem to the
+ company or organization that produces the OS (in the case of a
+ Linux distribution, report the problem to whoever produces the
+ distribution).
+
+ Q 6.2: Why does my machine crash or reset itself when I select "Start"
+ from the "Capture" menu or select "Preferences" from the "Edit" menu?
+
+ A: Both of those operations cause Wireshark to try to build a list of
+ the interfaces that it can open; it does so by getting a list of
+ interfaces and trying to open them. There is probably an OS, driver,
+ or, for Windows, WinPcap bug that causes the system to crash when this
+ happens; see the previous question.
-Using Ethereal
+7. Capturing packets
- Q 5.1: When I use Ethereal to capture packets, I see only packets to
- and from my machine, or I'm not seeing all the traffic I'm expecting
- to see from or to the machine I'm trying to monitor.
+ Q 7.1: When I use Wireshark to capture packets, why do I see only
+ packets to and from my machine, or not see all the traffic I'm
+ expecting to see from or to the machine I'm trying to monitor?
A: This might be because the interface on which you're capturing is
- plugged into a switch; on a switched network, unicast traffic between
- two ports will not necessarily appear on other ports - only broadcast
- and multicast traffic will be sent to all ports.
+ plugged into an Ethernet or Token Ring switch; on a switched network,
+ unicast traffic between two ports will not necessarily appear on other
+ ports - only broadcast and multicast traffic will be sent to all ports.
Note that even if your machine is plugged into a hub, the "hub" may be
a switched hub, in which case you're still on a switched network.
This problem has also been reported for Netgear dual-speed hubs, and
may exist for other "auto-sensing" or "dual-speed" hubs.
- Some switches have the ability to replicate all traffic on all ports
- to a single port so that you can plug your analyzer into that single
- port to sniff all traffic. You would have to check the documentation
- for the switch to see if this is possible and, if so, to see how to do
- this. See, for example:
- * this documentation from Cisco on the Switched Port Analyzer (SPAN)
- feature on Catalyst switches;
- * documentation from HP on how to set "monitoring"/"mirroring" on
- ports on the console for HP Advancestack Switch 208 and 224;
- * the "Network Monitoring Port Features" section of chapter 6 of
- documentation from HP for HP ProCurve Switches 1600M, 2424M,
- 4000M, and 8000M;
- * the "Switch Port-Mirroring" section of chapter 6 of documentation
- from Extreme Networks for their Summit 200 switches;
- * the documentation on "Configuring Port Mirroring and Monitoring"
- in Foundry Networks' documentation for their FastIron Edge
- Switches;
- * the documentation on "Configuring Port Mirroring and Monitoring"
- in Foundry Networks' documentation for their BigIron MG8 Layer 3
- Switches;
- * the "Port Monitor" subsection of the "Status Monitor and
- Statistics" section of the documentation from Foundry Networks for
- their EdgeIron 4802F and 10GC2F switches;
- * the "Configuring Port Mirroring" section of chapter 3 of the
- documentation from Foundry Networks for their EdgeIron 24G,
- 2402CF, and 4802CF switches;
- * the documentation on "Configuring Port Mirroring and Monitoring"
- in Foundry Networks' documentation for their other switches and
- metro routers.
+ Some switches have the ability to replicate all traffic on all ports to
+ a single port so that you can plug your analyzer into that single port
+ to sniff all traffic. You would have to check the documentation for the
+ switch to see if this is possible and, if so, to see how to do this.
+ See the switch reference page on the Wireshark Wiki for information on
+ some switches. (Note that it's a Wiki, so you can update or fix that
+ information, or add additional information on those switches or
+ information on new switches, yourself.)
Note also that many firewall/NAT boxes have a switch built into them;
this includes many of the "cable/DSL router" boxes. If you have a box
- of that sort, that has a switch with some number of Ethernet ports
- into which you plug machines on your network, and another Ethernet
- port used to connect to a cable or DSL modem, you can, at least, sniff
- traffic between the machines on your network and the Internet by
- plugging the Ethernet port on the router going to the modem, the
- Ethernet port on the modem, and the machine on which you're running
- Ethereal into a hub (make sure it's not a switching hub, and that, if
- it's a dual-speed hub, all three of those ports are running at the
- same speed.
+ of that sort, that has a switch with some number of Ethernet ports into
+ which you plug machines on your network, and another Ethernet port used
+ to connect to a cable or DSL modem, you can, at least, sniff traffic
+ between the machines on your network and the Internet by plugging the
+ Ethernet port on the router going to the modem, the Ethernet port on
+ the modem, and the machine on which you're running Wireshark into a hub
+ (make sure it's not a switching hub, and that, if it's a dual-speed
+ hub, all three of those ports are running at the same speed.
If your machine is not plugged into a switched network or a dual-speed
- hub, or it is plugged into a switched network but the port is set up
- to have all traffic replicated to it, the problem might be that the
+ hub, or it is plugged into a switched network but the port is set up to
+ have all traffic replicated to it, the problem might be that the
network interface on which you're capturing doesn't support
"promiscuous" mode, or because your OS can't put the interface into
- promiscuous mode. Normally, network interfaces supply to the host
- only:
+ promiscuous mode. Normally, network interfaces supply to the host only:
* packets sent to one of that host's link-layer addresses;
* broadcast packets;
* multicast packets sent to a multicast address that the host has
configured the interface to accept.
- Most network interfaces can also be put in "promiscuous" mode, in
- which they supply to the host all network packets they see. Ethereal
- will try to put the interface on which it's capturing into promiscuous
- mode unless the "Capture packets in promiscuous mode" option is turned
- off in the "Capture Options" dialog box, and Tethereal will try to put
- the interface on which it's capturing into promiscuous mode unless the
- -p option was specified. However, some network interfaces don't
- support promiscuous mode, and some OSes might not allow interfaces to
- be put into promiscuous mode.
+ Most network interfaces can also be put in "promiscuous" mode, in which
+ they supply to the host all network packets they see. Wireshark will
+ try to put the interface on which it's capturing into promiscuous mode
+ unless the "Capture packets in promiscuous mode" option is turned off
+ in the "Capture Options" dialog box, and TShark will try to put the
+ interface on which it's capturing into promiscuous mode unless the -p
+ option was specified. However, some network interfaces don't support
+ promiscuous mode, and some OSes might not allow interfaces to be put
+ into promiscuous mode.
If the interface is not running in promiscuous mode, it won't see any
traffic that isn't intended to be seen by your machine. It will see
broadcast packets, and multicast packets sent to a multicast MAC
address the interface is set up to receive.
- You should ask the vendor of your network interface whether it
- supports promiscuous mode. If it does, you should ask whoever supplied
- the driver for the interface (the vendor, or the supplier of the OS
- you're running on your machine) whether it supports promiscuous mode
- with that network interface.
+ You should ask the vendor of your network interface whether it supports
+ promiscuous mode. If it does, you should ask whoever supplied the
+ driver for the interface (the vendor, or the supplier of the OS you're
+ running on your machine) whether it supports promiscuous mode with that
+ network interface.
In the case of token ring interfaces, the drivers for some of them, on
- Windows, may require you to enable promiscuous mode in order to
- capture in promiscuous mode. Ask the vendor of the card how to do
- this, or see, for example, this information on promiscuous mode on
- some Madge token ring adapters (note that those cards can have
- promiscuous mode disabled permanently, in which case you can't enable
- it).
+ Windows, may require you to enable promiscuous mode in order to capture
+ in promiscuous mode. See the Wireshark Wiki item on Token Ring
+ capturing for details.
In the case of wireless LAN interfaces, it appears that, when those
interfaces are promiscuously sniffing, they're running in a
significantly different mode from the mode that they run in when
they're just acting as network interfaces (to the extent that it would
be a significant effor for those drivers to support for promiscuously
- sniffing and acting as regular network interfaces at the same time),
- so it may be that Windows drivers for those interfaces don't support
+ sniffing and acting as regular network interfaces at the same time), so
+ it may be that Windows drivers for those interfaces don't support
promiscuous mode.
- Q 5.2: I can't see any TCP packets other than packets to and from my
- machine, even though another analyzer on the network sees those
- packets.
+ Q 7.2: When I capture with Wireshark, why can't I see any TCP packets
+ other than packets to and from my machine, even though another analyzer
+ on the network sees those packets?
- A: You're probably not seeing any packets other than unicast packets
- to or from your machine, and broadcast and multicast packets; a switch
+ A: You're probably not seeing any packets other than unicast packets to
+ or from your machine, and broadcast and multicast packets; a switch
will normally send to a port only unicast traffic sent to the MAC
address for the interface on that port, and broadcast and multicast
traffic - it won't send to that port unicast traffic sent to a MAC
TCP doesn't use broadcast or multicast, so you will only see your own
TCP traffic, but UDP services may use broadcast or multicast so you'll
- see some UDP traffic - however, this is not a problem with TCP
- traffic, it's a problem with unicast traffic, as you also won't see
- all UDP traffic between other machines.
+ see some UDP traffic - however, this is not a problem with TCP traffic,
+ it's a problem with unicast traffic, as you also won't see all UDP
+ traffic between other machines.
I.e., this is probably the same question as this earlier one; see the
response to that question.
- Q 5.3: I'm only seeing ARP packets when I try to capture traffic.
+ Q 7.3: Why am I only seeing ARP packets when I try to capture traffic?
- A: You're probably on a switched network, and running Ethereal on a
- machine that's not sending traffic to the switch and not being sent
- any traffic from other machines on the switch. ARP packets are often
+ A: You're probably on a switched network, and running Wireshark on a
+ machine that's not sending traffic to the switch and not being sent any
+ traffic from other machines on the switch. ARP packets are often
broadcast packets, which are sent to all switch ports.
I.e., this is probably the same question as this earlier one; see the
response to that question.
- Q 5.4: I'm running Ethereal on Windows; why does some network
- interface on my machine not show up in the list of interfaces in the
- "Interface:" field in the dialog box popped up by "Capture->Start",
- and/or why does Ethereal give me an error if I try to capture on that
- interface?
-
- A: If you are running Ethereal on Windows NT 4.0, Windows 2000,
- Windows XP, or Windows Server, and this is the first time you have run
- a WinPcap-based program (such as Ethereal, or Tethereal, or WinDump,
- or Analyzer, or...) since the machine was rebooted, you need to run
- that program from an account with administrator privileges; once you
- have run such a program, you will not need administrator privileges to
- run any such programs until you reboot.
-
- If you are running on Windows 95/98/Me, or if you are running on
- Windows NT 4.0/2000/XP/Server and have administrator privileges or a
- WinPcap-based program has been run with those privileges since the
- machine rebooted, then note that Ethereal relies on the WinPcap
- library, on the WinPcap device driver, and on the facilities that come
- with the OS on which it's running in order to do captures.
-
- Therefore, if the OS, the WinPcap library, or the WinPcap driver don't
- support capturing on a particular network interface device, Ethereal
- won't be able to capture on that device.
-
- Note that:
- 1. 2.02 and earlier versions of the WinPcap driver and library that
- Ethereal uses for packet capture didn't support Token Ring
- interfaces; versions 2.1 and later support Token Ring, and the
- current version of Ethereal works with (and, in fact, requires)
- WinPcap 2.1 or later.
- If you are having problems capturing on Token Ring interfaces, and
- you have WinPcap 2.02 or an earlier version of WinPcap installed,
- you should uninstall WinPcap, download and install the current
- version of WinPcap, and then install the latest version of
- Ethereal.
- 2. On Windows 95, 98, or Me, sometimes more than one interface will
- be given the same name; if that is the case, you will only be able
- to capture on one of those interfaces - it's not clear to which
- one the name, when used in a WinPcap-based application, will
- refer. For example, if you have a PPP serial interface and a VPN
- interface, they might show up with the same name, for example
- "ppp-mac", and if you try to capture on "ppp-mac", it might not
- capture on the interface you're currently using. In that case, you
- might, for example, have to remove the VPN interface from the
- system in order to capture on the PPP serial interface.
- 3. WinPcap 3.0 doesn't support PPP WAN interfaces, and WinPcap 2.3
- doesn't support PPP WAN interfaces on Windows NT/2000/XP/Server,
- so Ethereal cannot capture packets on those devices with WinPcap
- 3.0, or with WInPcap 2.x when running on Windows
- NT/2000/XP/Server. Regular dial-up lines, ISDN lines, and various
- other lines such as T1/E1 lines are all PPP interfaces. This may
- cause the interface not to show up on the list of interfaces in
- the "Capture Options" dialog.
- 4. WinPcap prior to 3.0 does not support multiprocessor machines
- (note that machines with a single multi-threaded processor, such
- as Intel's new multi-threaded x86 processors, are multiprocessor
- machines as far as the OS and WinPcap are concerned), and recent
- 2.x versions of WinPcap refuse to operate if they detect that
- they're running on a multiprocessor machine, which means that they
- may not show any network interfaces. You will need to use WinPcap
- 3.0 to capture on a multiprocessor machine.
-
- If an interface doesn't show up in the list of interfaces in the
- "Interface:" field, and you know the name of the interface, try
- entering that name in the "Interface:" field and capturing on that
- device.
-
- If the attempt to capture on it succeeds, the interface is somehow not
- being reported by the mechanism Ethereal uses to get a list of
- interfaces; please report this to ethereal-dev@ethereal.com giving
- full details of the problem, including
- * the operating system you're using, and the version of that
- operating system;
- * the type of network device you're using.
-
- If you are having trouble capturing on a particular network interface,
- first try capturing on that device with WinDump; see the WinDump Web
- site or the local mirror of the WinDump Web site for information on
- using WinDump.
-
- If you can capture on the interface with WinDump, send mail to
- ethereal-users@ethereal.com giving full details of the problem,
- including
- * the operating system you're using, and the version of that
- operating system;
- * the type of network device you're using;
- * the error message you get from Ethereal.
-
- If you cannot capture on the interface with WinDump, this is almost
- certainly a problem with one or more of:
- * the operating system you're using;
- * the device driver for the interface you're using;
- * the WinPcap library and/or the WinPcap device driver;
-
- so first check the WinPcap FAQ, the local mirror of that FAQ, or the
- Wiretapped.net mirror of that FAQ, to see if your problem is mentioned
- there. If not, then see the WinPcap support page (or the local mirror
- of that page) - check the "Submitting bugs" section.
-
- You may also want to ask the ethereal-users@ethereal.com and the
- winpcap-users@winpcap.polito.it mailing lists to see if anybody
- happens to know about the problem and know a workaround or fix for the
- problem. (Note that you will have to subscribe to that list in order
- to be allowed to mail to it; see the WinPcap support page, or the
- local mirror of that page, for information on the mailing list.) In
- your mail, please give full details of the problem, as described
- above, and also indicate that the problem occurs with WinDump, not
- just with Ethereal.
-
- Q 5.5: I'm running Ethereal on Windows; why do no network interfaces
- show up in the list of interfaces in the "Interface:" field in the
- dialog box popped up by "Capture->Start"?
-
- A: This is really the same question as the previous one; see the
- response to that question.
-
- Q 5.6: I'm running Ethereal on Windows; why doesn't my serial
- port/ADSL modem/ISDN modem/show up in the list of interfaces in the
- "Interface:" field in the dialog box popped up by "Capture->Start"?
-
- A: All of those devices support Internet access using the
- Point-to-Point (PPP) protocol; WinPcap 3.0 doesn't support PPP
- interfaces, and WinPcap 2.x doesn't support PPP interfaces on Windows
- NT/2000/XP/Server, so Ethereal cannot capture packets on those devices
- with WinPcap 3.0, or with WinPcap 2.x when running on Windows
- NT/2000/XP/Server. This may cause the interface not to show up on the
- list of interfaces in the "Capture Options" dialog.
-
- Q 5.7: I'm running Ethereal on a UNIX-flavored OS; why does some
- network interface on my machine not show up in the list of interfaces
- in the "Interface:" field in the dialog box popped up by
- "Capture->Start", and/or why does Ethereal give me an error if I try
- to capture on that interface?
-
- A: You may need to run Ethereal from an account with sufficient
- privileges to capture packets, such as the super-user account. Only
- those interfaces that Ethereal can open for capturing show up in that
- list; if you don't have sufficient privileges to capture on any
- interfaces, no interfaces will show up in the list.
-
- If you are running Ethereal from an account with sufficient
- privileges, then note that Ethereal relies on the libpcap library, and
- on the facilities that come with the OS on which it's running in order
- to do captures.
-
- Therefore, if the OS or the libpcap library don't support capturing on
- a particular network interface device, Ethereal won't be able to
- capture on that device.
-
- On Linux, note that you need to have "packet socket" support enabled
- in your kernel; see the "Packet socket" item in the Linux
- "Configure.help" file.
-
- On BSD, note that you need to have BPF support enabled in your kernel;
- see the documentation for your system for information on how to enable
- BPF support (if it's not enabled by default on your system).
-
- On DEC OSF/1, Digital UNIX, or Tru64 UNIX, note that you need to have
- packet filtering support in your kernel; the doconfig command will
- allow you to configure and build a new kernel with that option.
-
- On Solaris, note that libpcap 0.6.2 and earlier didn't support Token
- Ring interfaces; the current version, 0.7.2, does support Token Ring,
- and the current version of Ethereal works with libcap 0.7.2 and later.
-
- If an interface doesn't show up in the list of interfaces in the
- "Interface:" field, and you know the name of the interface, try
- entering that name in the "Interface:" field and capturing on that
- device.
-
- If the attempt to capture on it succeeds, the interface is somehow not
- being reported by the mechanism Ethereal uses to get a list of
- interfaces; please report this to ethereal-dev@ethereal.com giving
- full details of the problem, including
- * the operating system you're using, and the version of that
- operating system (for Linux, give both the version number of the
- kernel and the name and version number of the distribution you're
- using);
- * the type of network device you're using.
-
- If you are having trouble capturing on a particular network interface,
- and you've made sure that (on platforms that require it) you've
- arranged that packet capture support is present, as per the above,
- first try capturing on that device with tcpdump.
-
- If you can capture on the interface with tcpdump, send mail to
- ethereal-users@ethereal.com giving full details of the problem,
- including
- * the operating system you're using, and the version of that
- operating system (for Linux, give both the version number of the
- kernel and the name and version number of the distribution you're
- using);
- * the type of network device you're using;
- * the error message you get from Ethereal.
-
- If you cannot capture on the interface with tcpdump, this is almost
- certainly a problem with one or more of:
- * the operating system you're using;
- * the device driver for the interface you're using;
- * the libpcap library;
-
- so you should report the problem to the company or organization that
- produces the OS (in the case of a Linux distribution, report the
- problem to whoever produces the distribution).
+ Q 7.4: Why am I not seeing any traffic when I try to capture traffic?
- You may also want to ask the ethereal-users@ethereal.com and the
- tcpdump-workers@tcpdump.org mailing lists to see if anybody happens to
- know about the problem and know a workaround or fix for the problem.
- In your mail, please give full details of the problem, as described
- above, and also indicate that the problem occurs with tcpdump not just
- with Ethereal.
+ A: Is the machine running Wireshark sending out any traffic on the
+ network interface on which you're capturing, or receiving any traffic
+ on that network, or is there any broadcast traffic on the network or
+ multicast traffic to a multicast group to which the machine running
+ Wireshark belongs?
- Q 5.8: I'm running Ethereal on a UNIX-flavored OS; why do no network
- interfaces show up in the list of interfaces in the "Interface:" field
- in the dialog box popped up by "Capture->Start"?
+ If not, this may just be a problem with promiscuous sniffing, either
+ due to running on a switched network or a dual-speed hub, or due to
+ problems with the interface not supporting promiscuous mode; see the
+ response to this earlier question.
- A: This is really the same question as the previous one; see the
- response to that question.
+ Otherwise, on Windows, see the response to this question and, on a
+ UNIX-flavored OS, see the response to this question.
- Q 5.9: Can Ethereal capture on (my T1/E1 line, SS7 links, etc.)?
+ Q 7.5: Can Wireshark capture on (my T1/E1 line, SS7 links, etc.)?
- A: Ethereal can only capture on devices supported by libpcap/WinPcap.
+ A: Wireshark can only capture on devices supported by libpcap/WinPcap.
On most OSes, only devices that can act as network interfaces of the
type that support IP are supported as capture devices for
libpcap/WinPcap, although the device doesn't necessarily have to be
On Linux and FreeBSD, libpcap 0.8 and later support the API for Endace
Measurement Systems' DAG cards, so that a system with one of those
- cards, and its driver and libraries, installed can capture traffic
- with those cards with libpcap-based applications. You would either
- have to have a version of Ethereal built with that version of libpcap,
- or a dynamically-linked version of Ethereal and a shared libpcap
- library with DAG support, in order to do so with Ethereal. You should
- ask Endace whether that could be used to capture traffic on, for
- example, your T1/E1 link.
- There is currently no hardware to support capturing on SS7 links with
- libpcap. (Note that the fact that Ethereal includes dissectors for
- many SS7 protocols doesn't imply that it can capture traffic from SS7
- links; those protocols can be run over Internet protocols.)
-
- Q 5.10: How do I put an interface into promiscuous mode?
-
- A: By not disabling promiscuous mode when running Ethereal or
- Tethereal.
+ cards, and its driver and libraries, installed can capture traffic with
+ those cards with libpcap-based applications. You would either have to
+ have a version of Wireshark built with that version of libpcap, or a
+ dynamically-linked version of Wireshark and a shared libpcap library
+ with DAG support, in order to do so with Wireshark. You should ask
+ Endace whether that could be used to capture traffic on, for example,
+ your T1/E1 link. See the SS7 capture setup page on the Wireshark Wiki
+ for current information on capturing SS7 traffic on TDM links.
+
+ Q 7.6: How do I put an interface into promiscuous mode?
+
+ A: By not disabling promiscuous mode when running Wireshark or TShark.
Note, however, that:
* the form of promiscuous mode that libpcap (the library that
- programs such as tcpdump, Ethereal, etc. use to do packet capture)
+ programs such as tcpdump, Wireshark, etc. use to do packet capture)
turns on will not necessarily be shown if you run ifconfig on the
interface on a UNIX system;
* some network interfaces might not support promiscuous mode, and
- some drivers might not allow promiscuous mode to be turned on -
- see this earlier question for more information on that;
+ some drivers might not allow promiscuous mode to be turned on - see
+ this earlier question for more information on that;
* the fact that you're not seeing any traffic, or are only seeing
- broadcast traffic, or aren't seeing any non-broadcast traffic
- other than traffic to or from the machine running Ethereal, does
- not mean that promiscuous mode isn't on - see this earlier
- question for more information on that.
+ broadcast traffic, or aren't seeing any non-broadcast traffic other
+ than traffic to or from the machine running Wireshark, does not
+ mean that promiscuous mode isn't on - see this earlier question for
+ more information on that.
I.e., this is probably the same question as this earlier one; see the
response to that question.
- Q 5.11: I can set a display filter just fine, but capture filters
- don't work.
+ Q 7.7: I can set a display filter just fine; why don't capture filters
+ work?
A: Capture filters currently use a different syntax than display
- filters. Here's the corresponding section from the ethereal(1) man
+ filters. Here's the corresponding section from the wireshark(1) man
page:
- "Display filters in Ethereal are very powerful; more fields are
- filterable in Ethereal than in other protocol analyzers, and the
- syntax you can use to create your filters is richer. As Ethereal
+ "Display filters in Wireshark are very powerful; more fields are
+ filterable in Wireshark than in other protocol analyzers, and the
+ syntax you can use to create your filters is richer. As Wireshark
progresses, expect more and more protocol fields to be allowed in
display filters.
- Packet capturing is performed with the pcap library. The capture
- filter syntax follows the rules of the pcap library. This syntax is
- different from the display filter syntax."
+ Packet capturing is performed with the pcap library. The capture filter
+ syntax follows the rules of the pcap library. This syntax is different
+ from the display filter syntax."
The capture filter syntax used by libpcap can be found in the
tcpdump(8) man page.
- Q 5.12: I'm entering valid capture filters, but I still get "parse
- error" errors.
+ Q 7.8: I'm entering valid capture filters; why do I still get "parse
+ error" errors?
A: There is a bug in some versions of libpcap/WinPcap that cause it to
report parse errors even for valid expressions if a previous filter
expression was invalid and got a parse error.
- Try exiting and restarting Ethereal; if you are using a version of
+ Try exiting and restarting Wireshark; if you are using a version of
libpcap/WinPcap with this bug, this will "erase" its memory of the
previous parse error. If the capture filter that got the "parse error"
now works, the earlier error with that filter was probably due to this
libpcap, and have this bug; WinPcap 2.3 is based on libpcap 0.6.2, and
doesn't have this bug.
- If you are running Ethereal on a UNIX-flavored platform, run "ethereal
- -v", or select "About Ethereal..." from the "Help" menu in Ethereal,
- to see what version of libpcap it's using. If it's not 0.6 or later,
- you will need either to upgrade your OS to get a later version of
- libpcap, or will need to build and install a later version of libpcap
- from the tcpdump.org Web site and then recompile Ethereal from source
- with that later version of libpcap.
+ If you are running Wireshark on a UNIX-flavored platform, run
+ "wireshark -v", or select "About Wireshark..." from the "Help" menu in
+ Wireshark, to see what version of libpcap it's using. If it's not 0.6
+ or later, you will need either to upgrade your OS to get a later
+ version of libpcap, or will need to build and install a later version
+ of libpcap from the tcpdump.org Web site and then recompile Wireshark
+ from source with that later version of libpcap.
- If you are running Ethereal on Windows with a pre-2.3 version of
+ If you are running Wireshark on Windows with a pre-2.3 version of
WinPcap, you will need to un-install WinPcap and then download and
install WinPcap 2.3.
- Q 5.13: I saved a filter and tried to use its name to filter the
- display, but I got an "Unexpected end of filter string" error.
+ Q 7.9: How can I capture packets with CRC errors?
- A: You cannot use the name of a saved display filter as a filter. To
- filter the display, you can enter a display filter expression - not
- the name of a saved display filter - in the "Filter:" box at the
- bottom of the display, and type the key or press the "Apply" button
- (that does not require you to have a saved filter), or, if you want to
- use a saved filter, you can press the "Filter:" button, select the
- filter in the dialog box that pops up, and press the "OK" button.
+ A: Wireshark can capture only the packets that the packet capture
+ library - libpcap on UNIX-flavored OSes, and the WinPcap port to
+ Windows of libpcap on Windows - can capture, and libpcap/WinPcap can
+ capture only the packets that the OS's raw packet capture mechanism (or
+ the WinPcap driver, and the underlying OS networking code and network
+ interface drivers, on Windows) will allow it to capture.
- Q 5.14: Why am I seeing lots of packets with incorrect TCP checksums?
+ Unless the OS always supplies packets with errors such as invalid CRCs
+ to the raw packet capture mechanism, or can be configured to do so,
+ invalid CRCs to the raw packet capture mechanism, Wireshark - and other
+ programs that capture raw packets, such as tcpdump - cannot capture
+ those packets. You will have to determine whether your OS needs to be
+ so configured and, if so, can be so configured, configure it if
+ necessary and possible, and make whatever changes to libpcap and the
+ packet capture program you're using are necessary, if any, to support
+ capturing those packets.
- A: If the packets that have incorrect TCP checksums are all being sent
- by the machine on which Ethereal is running, this is probably because
- the network interface on which you're capturing does TCP checksum
- offloading. That means that the TCP checksum is added to the packet by
- the network interface, not by the OS's TCP/IP stack; when capturing on
- an interface, packets being sent by the host on which you're capturing
- are directly handed to the capture interface by the OS, which means
- that they are handed to the capture interface without a TCP checksum
- being added to them.
+ Most OSes probably do not support capturing packets with invalid CRCs
+ on Ethernet, and probably do not support it on most other link-layer
+ types. Some drivers on some OSes do support it, such as some Ethernet
+ drivers on FreeBSD; in those OSes, you might always get those packets,
+ or you might only get them if you capture in promiscuous mode (you'd
+ have to determine which is the case).
- The only way to prevent this from happening would be to disable TCP
- checksum offloading, but
- 1. that might not even be possible on some OSes;
- 2. that could reduce networking performance significantly.
+ Note that libpcap does not currently supply to programs that use it an
+ indication of whether the packet's CRC was invalid (because the drivers
+ themselves do not supply that information to the raw packet capture
+ mechanism); therefore, Wireshark will not indicate which packets had
+ CRC errors unless the FCS was captured (see the next question) and
+ you're using Wireshark 0.9.15 and later, in which case Wireshark will
+ check the CRC and indicate whether it's correct or not.
- However, you can disable the check that Ethereal does of the TCP
- checksum, so that it won't report any packets as having TCP checksum
- errors, and so that it won't refuse to do TCP reassembly due to a
- packet having an incorrect TCP checksum. That can be set as an
- Ethereal preference by selecting "Preferences" from the "Edit" menu,
- opening up the "Protocols" list in the left-hand pane of the
- "Preferences" dialog box, selecting "TCP", from that list, turning off
- the "Check the validity of the TCP checksum when possible" option,
- clicking "Save" if you want to save that setting in your preference
- file, and clicking "OK".
+ Q 7.10: How can I capture entire frames, including the FCS?
- It can also be set on the Ethereal or Tethereal command line with a -o
- tcp.check_checksum:false command-line flag, or manually set in your
- preferences file by adding a tcp.check_checksum:false line.
+ A: Wireshark can only capture data that the packet capture library -
+ libpcap on UNIX-flavored OSes, and the WinPcap port to Windows of
+ libpcap on Windows - can capture, and libpcap/WinPcap can capture only
+ the data that the OS's raw packet capture mechanism (or the WinPcap
+ driver, and the underlying OS networking code and network interface
+ drivers, on Windows) will allow it to capture.
- Q 5.15: I've just installed Ethereal, and the traffic on my local LAN
- is boring.
+ For any particular link-layer network type, unless the OS supplies the
+ FCS of a frame as part of the frame, or can be configured to do so,
+ Wireshark - and other programs that capture raw packets, such as
+ tcpdump - cannot capture the FCS of a frame. You will have to determine
+ whether your OS needs to be so configured and, if so, can be so
+ configured, configure it if necessary and possible, and make whatever
+ changes to libpcap and the packet capture program you're using are
+ necessary, if any, to support capturing the FCS of a frame.
- A: We have a collection of strange and exotic sample capture files at
- http://www.ethereal.com/sample/
-
- Q 5.16: When I run Ethereal on Solaris 8, it dies with a Bus Error
- when I start it.
-
- A: Some versions of the GTK+ library from www.sunfreeware.org appear
- to be buggy, causing Ethereal to drop core with a Bus Error.
- Un-install those packages, and try getting the 1.2.10 version from
- that site, or the version from The Written Word, or the version from
- Sun's GNOME distribution, or the version from the supplemental
- software CD that comes with the Solaris media kit, or build it from
- source from the GTK Web site. Update the GLib library to the 1.2.10
- version, from the same source, as well. (If you get the 1.2.10
- versions from www.sunfreeware.org, and the problem persists,
- un-install them and try installing one of the other versions
- mentioned.)
+ Most OSes do not support capturing the FCS of a frame on Ethernet, and
+ probably do not support it on most other link-layer types. Some drivres
+ on some OSes do support it, such as some (all?) Ethernet drivers on
+ NetBSD and possibly the driver for Apple's gigabit Ethernet interface
+ in Mac OS X; in those OSes, you might always get the FCS, or you might
+ only get the FCS if you capture in promiscuous mode (you'd have to
+ determine which is the case).
+
+ Versions of Wireshark prior to 0.9.15 will not treat an Ethernet FCS in
+ a captured packet as an FCS. 0.9.15 and later will attempt to determine
+ whether there's an FCS at the end of the frame and, if it thinks there
+ is, will display it as such, and will check whether it's the correct
+ CRC-32 value or not.
+
+ Q 7.11: I'm capturing packets on a machine on a VLAN; why don't the
+ packets I'm capturing have VLAN tags?
- Similar problems may exist with older versions of GTK+ for earlier
- versions of Solaris.
+ A: You might be capturing on what might be called a "VLAN interface" -
+ the way a particular OS makes VLANs plug into the networking stack
+ might, for example, be to have a network device object for the physical
+ interface, which takes VLAN packets, strips off the VLAN header and
+ constructs an Ethernet header, and passes that packet to an internal
+ network device object for the VLAN, which then passes the packets onto
+ various higher-level protocol implementations.
- Q 5.17: When I run Tethereal with the "-x" option, it crashes with an
- error "** ERROR **: file print.c: line 691 (print_line): should not be
- reached".
-
- A: This is a bug in Ethereal 0.10.0a, which is fixed in the Ethereal
- CVS tree and will thus be fixed in the next release. To work around
- the bug, don't use "-x" unless you're also using "-V"; note that "-V"
- produces a full dissection of each packet, so you might not want to
- use it.
-
- To get a fixed version, either build the current CVS version from
- anonymous CVS or a nightly CVS snapshot, or apply to tethereal.c in
- the 0.10.0a source tarball the changes between the broken and the
- fixed versions, which you can download with the URL
- http://www.ethereal.com/cgi-bin/viewcvs.cgi/ethereal/tethereal.c.diff?
- r2=1.211&r1=1.210&diff_format=u and (re-)build from source. It might
- be easier to get the CVS version than to get the patch and apply it to
- the 0.10.0a source tarball, but it's probably easier to build from the
- source tarball than from the CVS version, as you'll need to have more
- tools and make more steps to generate from the CVS version some files
- that are bundled with the source tarball.
-
- Note that to build from the 0.10.0a source tarball on Windows with
- Microsoft Visual C++, you will need to get a file that was missing
- from the 0.10.0a source tarball; see the FAQ for that problem.
-
- Q 5.18: When I run Ethereal on Windows NT, it dies with a Dr. Watson
- error, reporting an "Integer division by zero" exception, when I start
- it.
+ In order to see the raw Ethernet packets, rather than "de-VLANized"
+ packets, you would have to capture not on the virtual interface for the
+ VLAN, but on the interface corresponding to the physical network
+ device, if possible. See the Wireshark Wiki item on VLAN capturing for
+ details.
- A: In at least some case, this appears to be due to using the default
- VGA driver; if that's not the correct driver for your video card, try
- running the correct driver for your video card.
+ Q 7.12: Why does Wireshark hang after I stop a capture?
- Q 5.19: When I try to run Ethereal, it complains about
- sprint_realloc_objid being undefined.
+ A: The most likely reason for this is that Wireshark is trying to look
+ up an IP address in the capture to convert it to a name (so that, for
+ example, it can display the name in the source address or destination
+ address columns), and that lookup process is taking a very long time.
- A: Ethereal can only be linked with version 4.2.2 or later of UCD
- SNMP. Your version of Ethereal was dynamically linked with such a
- version of UCD SNMP; however, you have an older version of UCD SNMP
- installed, which means that when Ethereal is run, it tries to link to
- the older version, and fails. You will have to replace that version of
- UCD SNMP with version 4.2.2 or a later version.
+ Wireshark calls a routine in the OS of the machine on which it's
+ running to convert of IP addresses to the corresponding names. That
+ routine probably does one or more of:
+ * a search of a system file listing IP addresses and names;
+ * a lookup using DNS;
+ * on UNIX systems, a lookup using NIS;
+ * on Windows systems, a NetBIOS-over-TCP query.
- Q 5.20: I'm running Ethereal on Linux; why do my time stamps have only
- 100ms resolution, rather than 1us resolution?
+ If a DNS server that's used in an address lookup is not responding, the
+ lookup will fail, but will only fail after a timeout while the system
+ routine waits for a reply.
- A: Ethereal gets time stamps from libpcap/WinPcap, and libpcap/WinPcap
- get them from the OS kernel, so Ethereal - and any other program using
- libpcap, such as tcpdump - is at the mercy of the time stamping code
- in the OS for time stamps.
+ In addition, on Windows systems, if the DNS lookup of the address
+ fails, either because the server isn't responding or because there are
+ no records in the DNS that could be used to map the address to a name,
+ a NetBIOS-over-TCP query will be made. That query involves sending a
+ message to the NetBIOS-over-TCP name service on that machine, asking
+ for the name and other information about the machine. If the machine
+ isn't running software that responds to those queries - for example,
+ many non-Windows machines wouldn't be running that software - the
+ lookup will only fail after a timeout. Those timeouts can cause the
+ lookup to take a long time.
- At least on x86-based machines, Linux can get high-resolution time
- stamps on newer processors with the Time Stamp Counter (TSC) register;
- for example, Intel x86 processors, starting with the Pentium Pro, and
- including all x86 processors since then, have had a TSC, and other
- vendors probably added the TSC at some point to their families of x86
- processors.
+ If you disable network address-to-name translation - for example, by
+ turning off the "Enable network name resolution" option in the "Capture
+ Options" dialog box for starting a network capture - the lookups of the
+ address won't be done, which may speed up the process of reading the
+ capture file after the capture is stopped. You can make that setting
+ the default by selecting "Preferences" from the "Edit" menu, turning
+ off the "Enable network name resolution" option in the "Name
+ resolution" options in the preferences disalog box, and using the
+ "Save" button in that dialog box; note that this will save all your
+ current preference settings.
+
+ If Wireshark hangs when reading a capture even with network name
+ resolution turned off, there might, for example, be a bug in one of
+ Wireshark's dissectors for a protocol causing it to loop infinitely. If
+ you're not running the most recent release of Wireshark, you should
+ first upgrade to that release, as, if there's a bug of that sort, it
+ might've been fixed in a release after the one you're running. If the
+ hang occurs in the most recent release of Wireshark, the bug should be
+ reported to the Wireshark developers' mailing list at
+ wireshark-dev@wireshark.org.
+
+ On UNIX-flavored OSes, please try to force Wireshark to dump core, by
+ sending it a SIGABRT signal (usually signal 6) with the kill command,
+ and then get a stack trace if you have a debugger installed. A stack
+ trace can be obtained by using your debugger (gdb in this example), the
+ Wireshark binary, and the resulting core file. Here's an example of how
+ to use the gdb command backtrace to do so.
+ $ gdb wireshark core
+ (gdb) backtrace
+ ..... prints the stack trace
+ (gdb) quit
+ $
- The Linux kernel must be configured with the CONFIG_X86_TSC option
- enabled in order to use the TSC. Make sure this option is enabled in
- your kernel.
+ The core dump file may be named "wireshark.core" rather than "core" on
+ some platforms (e.g., BSD systems).
- In addition, some Linux distributions may have bugs in their versions
- of the kernel that cause packets not to be given high-resolution time
- stamps even if the TSC is enabled. See, for example, bug 61111 for Red
- Hat Linux 7.2. If your distribution has a bug such as this, you may
- have to run a standard kernel from kernel.org in order to get
- high-resolution time stamps.
+ Also, if at all possible, please send a copy of the capture file that
+ caused the problem; when capturing packets, Wireshark normally writes
+ captured packets to a temporary file, which will probably be in /tmp or
+ /var/tmp on UNIX-flavored OSes, \TEMP on the main system disk (normally
+ C:) on Windows 9x/Me/NT 4.0, and \Documents and Settings\your login
+ name\Local Settings\Temp on the main system disk on Windows
+ 2000/Windows XP/Windows Server 2003, so the capture file will probably
+ be there. It will have a name beginning with ether, with some mixture
+ of letters and numbers after that. Please don't send a trace file
+ greater than 1 MB when compressed; instead, make it available via FTP
+ or HTTP, or say it's available but leave it up to a developer to ask
+ for it. If the trace file contains sensitive information (e.g.,
+ passwords), then please do not send it.
+
+8. Capturing packets on Windows
+
+ Q 8.1: I'm running Wireshark on Windows; why does some network
+ interface on my machine not show up in the list of interfaces in the
+ "Interface:" field in the dialog box popped up by "Capture->Start",
+ and/or why does Wireshark give me an error if I try to capture on that
+ interface?
- Q 5.21: I'm capturing packets on {Windows 95, Windows 98, Windows Me};
- why are the time stamps on packets wrong?
+ A: If you are running Wireshark on Windows NT 4.0, Windows 2000,
+ Windows XP, or Windows Server 2003, and this is the first time you have
+ run a WinPcap-based program (such as Wireshark, or TShark, or WinDump,
+ or Analyzer, or...) since the machine was rebooted, you need to run
+ that program from an account with administrator privileges; once you
+ have run such a program, you will not need administrator privileges to
+ run any such programs until you reboot.
- A: This is due to a bug in WinPcap. The bug should be fixed in WinPcap
- 3.0.
+ If you are running on Windows 95/98/Me, or if you are running on
+ Windows NT 4.0/Windows 2000/Windows XP/Windows Server 2003 and have
+ administrator privileges or a WinPcap-based program has been run with
+ those privileges since the machine rebooted, this problem might clear
+ up if you completely un-install WinPcap and then re-install it.
- Q 5.22: When I try to run Ethereal on Windows, it fails to run because
- it can't find packet.dll.
+ If that doesn't work, then note that Wireshark relies on the WinPcap
+ library, on the WinPcap device driver, and on the facilities that come
+ with the OS on which it's running in order to do captures.
- A: In older versions of Ethereal, there were two binary distributions
- available for Windows, one that supported capturing packets, and one
- that didn't. The version that supported capturing packets required
- that you install the WinPcap driver; if you didn't install it, it
- would fail to run because it couldn't find packet.dll.
+ Therefore, if the OS, the WinPcap library, or the WinPcap driver don't
+ support capturing on a particular network interface device, Wireshark
+ won't be able to capture on that device.
- The current version of Ethereal has only one binary distribution for
- Windows; that version will check whether WinPcap is installed and, if
- it's not, will disable support for packet capture.
+ Note that:
+ 1. 2.02 and earlier versions of the WinPcap driver and library that
+ Wireshark uses for packet capture didn't support Token Ring
+ interfaces; versions 2.1 and later support Token Ring, and the
+ current version of Wireshark works with (and, in fact, requires)
+ WinPcap 2.1 or later.
+ If you are having problems capturing on Token Ring interfaces, and
+ you have WinPcap 2.02 or an earlier version of WinPcap installed,
+ you should uninstall WinPcap, download and install the current
+ version of WinPcap, and then install the latest version of
+ Wireshark.
+ 2. On Windows 95, 98, or Me, sometimes more than one interface will be
+ given the same name; if that is the case, you will only be able to
+ capture on one of those interfaces - it's not clear to which one
+ the name, when used in a WinPcap-based application, will refer. For
+ example, if you have a PPP serial interface and a VPN interface,
+ they might show up with the same name, for example "ppp-mac", and
+ if you try to capture on "ppp-mac", it might not capture on the
+ interface you're currently using. In that case, you might, for
+ example, have to remove the VPN interface from the system in order
+ to capture on the PPP serial interface.
+ 3. WinPcap 2.3 has problems supporting PPP WAN interfaces on Windows
+ NT 4.0, Windows 2000, Windows XP, and Windows Server 2003, and, to
+ avoid those problems, support for PPP WAN interfaces on those
+ versions of Windows has been disabled in WinPcap 3.0. Regular
+ dial-up lines, ISDN lines, ADSL connections using PPPoE or PPPoA,
+ and various other lines such as T1/E1 lines are all PPP interfaces,
+ so those interfaces might not show up on the list of interfaces in
+ the "Capture Options" dialog on those OSes.
+ On Windows 2000, Windows XP, and Windows Server 2003, but not
+ Windows NT 4.0 or Windows Vista Beta 1, you should be able to
+ capture on the "GenericDialupAdapter" with WinPcap 3.1. (3.1 beta
+ releases called it the "NdisWanAdapter"; if you're using a 3.1 beta
+ release, you should un-install it and install the final 3.1
+ release.) See the Wireshark Wiki item on PPP capturing for details.
+ 4. WinPcap prior to 3.0 does not support multiprocessor machines (note
+ that machines with a single multi-threaded processor, such as
+ Intel's new multi-threaded x86 processors, are multiprocessor
+ machines as far as the OS and WinPcap are concerned), and recent
+ 2.x versions of WinPcap refuse to operate if they detect that
+ they're running on a multiprocessor machine, which means that they
+ may not show any network interfaces. You will need to use WinPcap
+ 3.0 to capture on a multiprocessor machine.
+
+ If an interface doesn't show up in the list of interfaces in the
+ "Interface:" field, and you know the name of the interface, try
+ entering that name in the "Interface:" field and capturing on that
+ device.
+
+ If the attempt to capture on it succeeds, the interface is somehow not
+ being reported by the mechanism Wireshark uses to get a list of
+ interfaces. Try listing the interfaces with WinDump; see the WinDump
+ Web site for information on using WinDump.
+
+ You would run WinDump with the -D flag; if it lists the interface,
+ please report this to wireshark-dev@wireshark.org giving full details
+ of the problem, including
+ * the operating system you're using, and the version of that
+ operating system;
+ * the type of network device you're using;
+ * the output of WinDump.
+
+ If WinDump does not list the interface, this is almost certainly a
+ problem with one or more of:
+ * the operating system you're using;
+ * the device driver for the interface you're using;
+ * the WinPcap library and/or the WinPcap device driver;
+
+ so first check the WinPcap FAQ or the Wiretapped.net mirror of that
+ FAQ, to see if your problem is mentioned there. If not, then see the
+ WinPcap support page - check the "Submitting bugs" section.
+
+ If you are having trouble capturing on a particular network interface,
+ first try capturing on that device with WinDump; see the WinDump Web
+ site for information on using WinDump.
+
+ If you can capture on the interface with WinDump, send mail to
+ wireshark-users@wireshark.org giving full details of the problem,
+ including
+ * the operating system you're using, and the version of that
+ operating system;
+ * the type of network device you're using;
+ * the error message you get from Wireshark.
+
+ If you cannot capture on the interface with WinDump, this is almost
+ certainly a problem with one or more of:
+ * the operating system you're using;
+ * the device driver for the interface you're using;
+ * the WinPcap library and/or the WinPcap device driver;
+
+ so first check the WinPcap FAQ or the Wiretapped.net mirror of that
+ FAQ, to see if your problem is mentioned there. If not, then see the
+ WinPcap support page - check the "Submitting bugs" section.
+
+ You may also want to ask the wireshark-users@wireshark.org and the
+ winpcap-users@winpcap.org mailing lists to see if anybody happens to
+ know about the problem and know a workaround or fix for the problem.
+ (Note that you will have to subscribe to that list in order to be
+ allowed to mail to it; see the WinPcap support page for information on
+ the mailing list.) In your mail, please give full details of the
+ problem, as described above, and also indicate that the problem occurs
+ with WinDump, not just with Wireshark.
+
+ Q 8.2: I'm running Wireshark on Windows; why do no network interfaces
+ show up in the list of interfaces in the "Interface:" field in the
+ dialog box popped up by "Capture->Start"?
+
+ A: This is really the same question as the previous one; see the
+ response to that question.
- The WinPcap driver and libraries can be downloaded from the WinPcap
- Web site, the local mirror of the WinPcap Web site, or the
- Wiretapped.net mirror of the WinPcap site.
-
- Q 5.23: I'm running Ethereal on Windows NT/2000/XP/Server; my machine
- has a PPP (dial-up POTS, ISDN, etc.) interface, and it shows up in the
- "Interface" item in the "Capture Options" dialog box. Why can no
- packets be sent on or received from that network while I'm trying to
- capture traffic on that interface?
-
- A: WinPcap doesn't support PPP WAN interfaces on Windows
- NT/2000/XP/Server; one symptom that may be seen is that attempts to
- capture in promiscuous mode on the interface cause the interface to be
- incapable of sending or receiving packets. You can disable promiscuous
- mode using the -p command-line flag or the item in the "Capture
- Preferences" dialog box, but this may mean that outgoing packets, or
- incoming packets, won't be seen in the capture.
-
- Q 5.24: I'm running Ethereal on Windows 95/98/Me, on a machine with
- more than one network adapter of the same type; Ethereal shows all of
- those adapters with the same name, but I can't use any of those
- adapters other than the first one.
+ Q 8.3: I'm running Wireshark on Windows; why doesn't my serial
+ port/ADSL modem/ISDN modem show up in the list of interfaces in the
+ "Interface:" field in the dialog box popped up by "Capture->Start"?
+
+ A: Internet access on those devices is often done with the
+ Point-to-Point (PPP) protocol; WinPcap 2.3 has problems supporting PPP
+ WAN interfaces on Windows NT 4.0, Windows 2000, Windows XP, and Windows
+ Server 2003, and, to avoid those problems, support for PPP WAN
+ interfaces on those versions of Windows has been disabled in WinPcap
+ 3.0.
+
+ On Windows 2000, Windows XP, and Windows Server 2003, but not Windows
+ NT 4.0 or Windows Vista Beta 1, you should be able to capture on the
+ "GenericDialupAdapter" with WinPcap 3.1. (3.1 beta releases called it
+ the "NdisWanAdapter"; if you're using a 3.1 beta release, you should
+ un-install it and install the final 3.1 release.) See the Wireshark
+ Wiki item on PPP capturing for details.
+
+ Q 8.4: I'm running Wireshark on Windows NT 4.0/Windows 2000/Windows
+ XP/Windows Server 2003; my machine has a PPP (dial-up POTS, ISDN, etc.)
+ interface, and it shows up in the "Interface" item in the "Capture
+ Options" dialog box. Why can no packets be sent on or received from
+ that network while I'm trying to capture traffic on that interface?
+
+ A: Some versions of WinPcap have problems with PPP WAN interfaces on
+ Windows NT 4.0, Windows 2000, Windows XP, and Windows Server 2003; one
+ symptom that may be seen is that attempts to capture in promiscuous
+ mode on the interface cause the interface to be incapable of sending or
+ receiving packets. You can disable promiscuous mode using the -p
+ command-line flag or the item in the "Capture Preferences" dialog box,
+ but this may mean that outgoing packets, or incoming packets, won't be
+ seen in the capture.
+
+ On Windows 2000, Windows XP, and Windows Server 2003, but not Windows
+ NT 4.0 or Windows Vista Beta 1, you should be able to capture on the
+ "GenericDialupAdapter" with WinPcap 3.1. (3.1 beta releases called it
+ the "NdisWanAdapter"; if you're using a 3.1 beta release, you should
+ un-install it and install the final 3.1 release.) See the Wireshark
+ Wiki item on PPP capturing for details.
+
+ Q 8.5: I'm running Wireshark on Windows 95/98/Me, on a machine with
+ more than one network adapter of the same type; why does Wireshark show
+ all of those adapters with the same name, not letting me use any of
+ those adapters other than the first one?
A: Unfortunately, Windows 95/98/Me gives the same name to multiple
instances of the type of same network adapter. Therefore, WinPcap
cannot distinguish between them, so a WinPcap-based application can
- capture only on the first such interface; Ethereal is a
+ capture only on the first such interface; Wireshark is a
libpcap/WinPcap-based application.
- Q 5.25: I'm running Ethereal on Windows, and I'm not seeing any
- traffic being sent by the machine running Ethereal.
+ Q 8.6: I'm running Wireshark on Windows; why am I not seeing any
+ traffic being sent by the machine running Wireshark?
A: If you are running some form of VPN client software, it might be
causing this problem; people have seen this problem when they have
Check Point's VPN software installed on their machine. If that's the
- cause of the problem, you will have to remove the VPN software in
- order to have Ethereal (or any other application using WinPcap) see
- outgoing packets; unfortunately, neither we nor the WinPcap developers
- know any way to make WinPcap and the VPN software work well together.
+ cause of the problem, you will have to remove the VPN software in order
+ to have Wireshark (or any other application using WinPcap) see outgoing
+ packets; unfortunately, neither we nor the WinPcap developers know any
+ way to make WinPcap and the VPN software work well together.
Also, some drivers for Windows (especially some wireless network
- interface drivers) apparently do not, when running in promiscuous
- mode, arrange that outgoing packets are delivered to the software that
- requested that the interface run promiscuously; try turning
- promiscuous mode off.
+ interface drivers) apparently do not, when running in promiscuous mode,
+ arrange that outgoing packets are delivered to the software that
+ requested that the interface run promiscuously; try turning promiscuous
+ mode off.
- Q 5.26: I'm trying to capture traffic but I'm not seeing any.
+ Q 8.7: When I capture on Windows in promiscuous mode, I can see packets
+ other than those sent to or from my machine; however, those packets
+ show up with a "Short Frame" indication, unlike packets to or from my
+ machine. What should I do to arrange that I see those packets in their
+ entirety?
- A: Is the machine running Ethereal sending out any traffic on the
- network interface on which you're capturing, or receiving any traffic
- on that network, or is there any broadcast traffic on the network or
- multicast traffic to a multicast group to which the machine running
- Ethereal belongs?
+ A: In at least some cases, this appears to be the result of PGPnet
+ running on the network interface on which you're capturing; turn it off
+ on that interface.
- If not, this may just be a problem with promiscuous sniffing, either
- due to running on a switched network or a dual-speed hub, or due to
- problems with the interface not supporting promiscuous mode; see the
- response to this earlier question.
+ Q 8.8: I'm capturing packets on {Windows 95, Windows 98, Windows Me};
+ why are the time stamps on packets wrong?
- Otherwise, on Windows, see the response to this question and, on a
- UNIX-flavored OS, see the response to this question.
+ A: This is due to a bug in WinPcap. The bug should be fixed in WinPcap
+ 3.0 and later releases.
- Q 5.27: I have an XXX network card on my machine; if I try to capture
- on it, my machine crashes or resets itself.
+ Q 8.9: I'm trying to capture 802.11 traffic on Windows; why am I not
+ seeing any packets?
- A: This is almost certainly a problem with one or more of:
- * the operating system you're using;
- * the device driver for the interface you're using;
- * the libpcap/WinPcap library and, if this is Windows, the WinPcap
- device driver;
+ A: At least some 802.11 card drivers on Windows appear not to see any
+ packets if they're running in promiscuous mode. Try turning promiscuous
+ mode off; you'll only be able to see packets sent by and received by
+ your machine, not third-party traffic, and it'll look like Ethernet
+ traffic and won't include any management or control frames, but that's
+ a limitation of the card drivers.
- so:
- * if you are using Windows, see the WinPcap support page (or the
- local mirror of that page) - check the "Submitting bugs" section;
- * if you are using some Linux distribution, some version of BSD, or
- some other UNIX-flavored OS, you should report the problem to the
- company or organization that produces the OS (in the case of a
- Linux distribution, report the problem to whoever produces the
- distribution).
+ See MicroLogix's list of cards supported with WinPcap for information
+ on support of various adapters and drivers with WinPcap.
- Q 5.28: My machine crashes or resets itself when I select "Start" from
- the "Capture" menu or select "Preferences" from the "Edit" menu.
+ Q 8.10: I'm trying to capture 802.11 traffic on Windows; why am I
+ seeing packets received by the machine on which I'm capturing traffic,
+ but not packets sent by that machine?
- A: Both of those operations cause Ethereal to try to build a list of
- the interfaces that it can open; it does so by getting a list of
- interfaces and trying to open them. There is probably an OS, driver,
- or, for Windows, WinPcap bug that causes the system to crash when this
- happens; see the previous question.
+ A: This appears to be another problem with promiscuous mode; try
+ turning it off.
- Q 5.29: Does Ethereal work on Windows Me?
+ Q 8.11: I'm trying to capture Ethernet VLAN traffic on Windows, and I'm
+ capturing on a "raw" Ethernet device rather than a "VLAN interface", so
+ that I can see the VLAN headers; why am I seeing packets received by
+ the machine on which I'm capturing traffic, but not packets sent by
+ that machine?
- A: Yes, but if you want to capture packets, you will need to install
- the latest version of WinPcap, as 2.02 and earlier versions of WinPcap
- didn't support Windows Me. You should also install the latest version
- of Ethereal as well.
+ A: The way the Windows networking code works probably means that
+ packets are sent on a "VLAN interface" rather than the "raw" device, so
+ packets sent by the machine will only be seen when you capture on the
+ "VLAN interface". If so, you will be unable to see outgoing packets
+ when capturing on the "raw" device, so you are stuck with a choice
+ between seeing VLAN headers and seeing outgoing packets.
- Q 5.30: Does Ethereal work on Windows XP?
+9. Capturing packets on UN*Xes
- A: Yes, but if you want to capture packets, you will need to install
- the latest version of WinPcap, as 2.2 and earlier versions of WinPcap
- didn't support Windows XP.
+ Q 9.1: I'm running Wireshark on a UNIX-flavored OS; why does some
+ network interface on my machine not show up in the list of interfaces
+ in the "Interface:" field in the dialog box popped up by
+ "Capture->Start", and/or why does Wireshark give me an error if I try
+ to capture on that interface?
- Q 5.31: Why doesn't Ethereal correctly identify RTP packets? It shows
- them only as UDP.
+ A: You may need to run Wireshark from an account with sufficient
+ privileges to capture packets, such as the super-user account, or may
+ need to give your account sufficient privileges to capture packets.
+ Only those interfaces that Wireshark can open for capturing show up in
+ that list; if you don't have sufficient privileges to capture on any
+ interfaces, no interfaces will show up in the list. See the Wireshark
+ Wiki item on capture privileges for details on how to give a particular
+ account or account group capture privileges on platforms where that can
+ be done.
+
+ If you are running Wireshark from an account with sufficient
+ privileges, then note that Wireshark relies on the libpcap library, and
+ on the facilities that come with the OS on which it's running in order
+ to do captures. On some OSes, those facilities aren't present by
+ default; see the Wireshark Wiki item on adding capture support for
+ details.
+
+ And, even if you're running with an account that has sufficient
+ privileges to capture, and capture support is present in your OS, if
+ the OS or the libpcap library don't support capturing on a particular
+ network interface device or particular types of devices, Wireshark
+ won't be able to capture on that device.
- A: Ethereal can identify a UDP datagram as containing a packet of a
- particular protocol running atop UDP only if
- 1. The protocol in question has a particular standard port number,
- and the UDP source or destination port number is that port
- 2. Packets of that protocol can be identified by looking for a
- "signature" of some type in the packet - i.e., some data that, if
- Ethereal finds it in some particular part of a packet, means that
- the packet is almost certainly a packet of that type.
- 3. Some other traffic earlier in the capture indicated that, for
- example, UDP traffic between two particular addresses and ports
- will be RTP traffic.
+ On Solaris, note that libpcap 0.6.2 and earlier didn't support Token
+ Ring interfaces; the current version, 0.7.2, does support Token Ring,
+ and the current version of Wireshark works with libcap 0.7.2 and later.
- RTP doesn't have a standard port number, so 1) doesn't work; it
- doesn't, as far as I know, have any "signature", so 2) doesn't work.
+ If an interface doesn't show up in the list of interfaces in the
+ "Interface:" field, and you know the name of the interface, try
+ entering that name in the "Interface:" field and capturing on that
+ device.
- That leaves 3). If there's RTSP traffic that sets up an RTP session,
- then, at least in some cases, the RTSP dissector will set things up so
- that subsequent RTP traffic will be identified. Currently, that's the
- only place we do that; there may be other places.
+ If the attempt to capture on it succeeds, the interface is somehow not
+ being reported by the mechanism Wireshark uses to get a list of
+ interfaces; please report this to wireshark-dev@wireshark.org giving
+ full details of the problem, including
+ * the operating system you're using, and the version of that
+ operating system (for Linux, give both the version number of the
+ kernel and the name and version number of the distribution you're
+ using);
+ * the type of network device you're using.
- However, there will always be places where Ethereal is simply
- incapable of deducing that a given UDP flow is RTP; a mechanism would
- be needed to allow the user to specify that a given conversation
- should be treated as RTP. As of Ethereal 0.8.16, such a mechanism
- exists; if you select a UDP or TCP packet, the right mouse button menu
- will have a "Decode As..." menu item, which will pop up a dialog box
- letting you specify that the source port, the destination port, or
- both the source and destination ports of the packet should be
- dissected as some particular protocol.
-
- Q 5.32: Why doesn't Ethereal show Yahoo Messenger packets in captures
- that contain Yahoo Messenger traffic?
+ If you are having trouble capturing on a particular network interface,
+ and you've made sure that (on platforms that require it) you've
+ arranged that packet capture support is present, as per the above,
+ first try capturing on that device with tcpdump.
- A: Ethereal only recognizes as Yahoo Messenger traffic packets to or
- from TCP port 3050 that begin with "YPNS", "YHOO", or "YMSG". TCP
- segments that start with the middle of a Yahoo Messenger packet that
- takes more than one TCP segment will not be recognized as Yahoo
- Messenger packets (even if the TCP segment also contains the beginning
- of another Yahoo Messenger packet).
+ If you can capture on the interface with tcpdump, send mail to
+ wireshark-users@wireshark.org giving full details of the problem,
+ including
+ * the operating system you're using, and the version of that
+ operating system (for Linux, give both the version number of the
+ kernel and the name and version number of the distribution you're
+ using);
+ * the type of network device you're using;
+ * the error message you get from Wireshark.
- Q 5.33: Why do I get the error
+ If you cannot capture on the interface with tcpdump, this is almost
+ certainly a problem with one or more of:
+ * the operating system you're using;
+ * the device driver for the interface you're using;
+ * the libpcap library;
- Gdk-ERROR **: Palettized display (256-colour) mode not supported on
- Windows.
- aborting....
+ so you should report the problem to the company or organization that
+ produces the OS (in the case of a Linux distribution, report the
+ problem to whoever produces the distribution).
- when I try to run Ethereal on Windows?
+ You may also want to ask the wireshark-users@wireshark.org and the
+ tcpdump-workers@tcpdump.org mailing lists to see if anybody happens to
+ know about the problem and know a workaround or fix for the problem. In
+ your mail, please give full details of the problem, as described above,
+ and also indicate that the problem occurs with tcpdump not just with
+ Wireshark.
- A: Ethereal is built using the GTK+ toolkit, which supports most
- UNIX-flavored OSes, and also supports Windows.
+ Q 9.2: I'm running Wireshark on a UNIX-flavored OS; why do no network
+ interfaces show up in the list of interfaces in the "Interface:" field
+ in the dialog box popped up by "Capture->Start"?
- Windows versions of Ethereal before 0.9.14 were built with an older
- version of that toolkit, which didn't support 256-color mode on
- Windows - it required HiColor (16-bit colors) or more.
+ A: This is really the same question as the previous one; see the
+ response to that question.
- Windows versions of Ethereal 0.9.14 and later are built with a version
- of that toolkit that supports 256-color mode; upgrade to the current
- version of Ethereal if you want to run on a display in 256-color mode.
+ Q 9.3: I'm capturing packets on Linux; why do the time stamps have only
+ 100ms resolution, rather than 1us resolution?
- Q 5.34: When I capture on Windows in promiscuous mode, I can see
- packets other than those sent to or from my machine; however, those
- packets show up with a "Short Frame" indication, unlike packets to or
- from my machine. What should I do to arrange that I see those packets
- in their entirety?
+ A: Wireshark gets time stamps from libpcap/WinPcap, and libpcap/WinPcap
+ get them from the OS kernel, so Wireshark - and any other program using
+ libpcap, such as tcpdump - is at the mercy of the time stamping code in
+ the OS for time stamps.
- A: In at least some cases, this appears to be the result of PGPnet
- running on the network interface on which you're capturing; turn it
- off on that interface.
+ At least on x86-based machines, Linux can get high-resolution time
+ stamps on newer processors with the Time Stamp Counter (TSC) register;
+ for example, Intel x86 processors, starting with the Pentium Pro, and
+ including all x86 processors since then, have had a TSC, and other
+ vendors probably added the TSC at some point to their families of x86
+ processors.
- Q 5.35: I'm capturing packets on a machine on a VLAN; why don't the
- packets I'm capturing have VLAN tags?
+ The Linux kernel must be configured with the CONFIG_X86_TSC option
+ enabled in order to use the TSC. Make sure this option is enabled in
+ your kernel.
- A: You might be capturing on what might be called a "VLAN interface" -
- the way a particular OS makes VLANs plug into the networking stack
- might, for example, be to have a network device object for the
- physical interface, which takes VLAN packets, strips off the VLAN
- header and constructs an Ethernet header, and passes that packet to an
- internal network device object for the VLAN, which then passes the
- packets onto various higher-level protocol implementations.
+ In addition, some Linux distributions may have bugs in their versions
+ of the kernel that cause packets not to be given high-resolution time
+ stamps even if the TSC is enabled. See, for example, bug 61111 for Red
+ Hat Linux 7.2. If your distribution has a bug such as this, you may
+ have to run a standard kernel from kernel.org in order to get
+ high-resolution time stamps.
- In order to see the raw Ethernet packets, rather than "de-VLANized"
- packets, you would have to capture not on the virtual interface for
- the VLAN, but on the interface corresponding to the physical network
- device, if possible.
+10. Capturing packets on wireless LANs
+
+ Q 10.1: How can I capture raw 802.11 frames, including non-data
+ (management, beacon) frames?
- Q 5.36: How can I capture raw 802.11 packets, including non-data
- (management, beacon) packets?
+ A: That depends on the operating system on which you're running, and on
+ the 802.11 interface on which you're capturing.
- A: That would require that your 802.11 interface run in the mode
- called "monitor mode" or "RFMON mode". Not all operating systems
- support that and, even on operating systems that do support it, not
- all drivers, and thus not all cards, support it.
+ This would probably require that you capture in promiscuous mode or in
+ the mode called "monitor mode" or "RFMON mode". On some platforms, or
+ with some cards, this might require that you capture in monitor mode -
+ promiscuous mode might not be sufficient. If you want to capture
+ traffic on networks other than the one with which you're associated,
+ you will have to capture in monitor mode.
+
+ Not all operating systems support capturing non-data packets and, even
+ on operating systems that do support it, not all drivers, and thus not
+ all interfaces, support it. Even on those that do, monitor mode might
+ not be supported by the operating system or by the drivers for all
+ interfaces.
NOTE: an interface running in monitor mode will, on most if not all
platforms, not be able to act as a regular network interface; putting
- it into monitor mode will, in effect, take your machine off of
- whatever network it's on as long as the interface is in monitor mode,
- allowing it only to passively capture packets.
+ it into monitor mode will, in effect, take your machine off of whatever
+ network it's on as long as the interface is in monitor mode, allowing
+ it only to passively capture packets.
This means that you should disable name resolution when capturing in
- monitor mode; otherwise, when Ethereal (or Tethereal, or tcpdump)
- tries to display IP addresses as host names, it will probably block
- for a long time trying to resolve the name because it will not be able
- to communicate with any DNS or NIS servers.
-
- Cisco Aironet cards:
-
- The only platforms that allow Ethereal to capture raw 802.11 packets
- on Cisco Aironet cards are:
- * Linux, with a 2.4.6 or later kernel;
- * FreeBSD 4.6 or later, as the driver in FreeBSD 4.5 has bugs that
- cause packets not to be captured correctly, and the driver in
- releases prior to 4.5 didn't support capturing raw packets.
-
- On FreeBSD, the ancontrol utility must be used. The command
-
-ancontrol -i anN -M flag
-
- is used to enable or disable monitor mode. If flag is 0, monitor mode
- will be turned off; otherwise, flag should be the sum of:
- * 1, to turn monitor mode on;
- * 2, if you want to capture traffic from any BSS rather than just
- the BSS with which the card is associated;
- * 4, if you want to see beacon packets (capturing beacon packets
- increases the CPU requirements of capturing).
-
- Don't add 8 in; Ethereal currently doesn't support the full Aironet
- header.
-
- On Linux with the driver in the 2.4.6 through 2.4.19 kernel, you will
- need to do
-
-echo "Mode: rfmon">/proc/driver/aironet/ethN/Config
-
- if your Aironet card is ethN. To capture traffic from any BSS rather
- than just the BSS with which the card is associated, do
-
-echo "Mode: y">/proc/driver/aironet/ethN/Config
-
- and to return to the normal mode, do
-
-echo "Mode: ess">/proc/driver/aironet/ethN/Config
-
- On Linux with the driver in the 2.4.20 or later kernel, or with the
- CVS drivers from the airo-linux SourceForge site, you will have to
- capture on the wifiN interface if your Aironet card is ethN, after
- running the commands listed above.
-
- In all of those cases, Ethereal would have to be linked with libpcap
- 0.7.1 or later; this means that most Ethereal binary packages won't
- work unless they're statically linked with libpcap 0.7.1 or later, or
- they're dynamically linked with libpcap and your system has a libpcap
- 0.7.1 or later shared library installed (note that libpcap source
- package from tcpdump.org does not build shared libraries). Some binary
- packaging mechanisms might make it difficult to install Ethereal
- binary packages built to depend on older libpcap binary packages if
- you have a newer libpcap binary package installed; the installer
- programs for those packaging mechanisms might support disabling
- dependency checking so that they will install Ethereal even though a
- newer version of libpcap is installed.
-
- Cards using the Prism II chip set (see this page of Linux 802.11
- information for details on wireless cards, including information on
- the chips they use):
-
- You can capture raw 802.11 packets with Prism II cards on Linux
- systems with the 0.1.14-pre6 or later version of the linux-wlan-ng
- drivers (see the linux-wlan page, and the linux-wlan-ng tarball
- directory).
-
- Those require either Solomon Peachy's patch to libpcap 0.7.1 (see his
- libpcap-0.7.1-prism.diff file, or his RPMs of that version of
- libpcap), or the current CVS version of libpcap, which includes his
- patch (download it from the "Current Tar files" section of the
- tcpdump.org Web site). If you apply his patches to libpcap 0.7.1 and
- rebuild and install libpcap, or if you build and install the current
- CVS version of libpcap, you would have to rebuild Ethereal from
- source, linking it with that new version of libpcap; an Ethereal
- binary package would not work. Ethereal binary packages might work if
- you install the libpcap-0.7.1-1prism.i386.rpm RPM, as it might install
- a libpcap shared library in place of the one on your system.
-
- You may have to run a command to put the interface into monitor mode,
- or to change other interface settings, and you might have to capture
- on a wlanN interface rather than a ethN interface, in order to capture
- raw 802.11 packets. The interface settings are available in your
- wlan-ng.conf file. See the wlan-ng FAQ for additional information.
-
- On other platforms, capturing raw 802.11 packets on Prism II cards is
- not currently supported.
-
- Orinoco Silver and Gold cards:
-
- On Linux systems, there are patches on the Orinoco Monitor Mode Patch
- Page that should allow you to do capture raw 802.11 packets. You will
- have to determine which version of the driver you have, and select the
- appropriate patch.
-
- Note that the page indicates that not all versions of the Orinoco
- firmware support this patch. It says, for some versions of the patch,
- "This patch should allow monitor mode with v8.10 firmware (untested w/
- 8.42);" if you have version 8.10 or later firmware on your Orinoco
- cards, you might have to use those patches, with the corresponding
- versions of the Orinoco driver, in order to run in monitor mode.
-
- That patch is written for the drivers included with the pcmcia-cs
- drivers, but works equally well for the Orinoco drivers provided with
- Linux kernels up to 2.4.20. To apply a patch to your kernel drivers,
- simply copy the orinoco-09b-patch.diff file to the
- /usr/src/linux/drivers/net directory and patch according to the
- directions on the Orinoco Monitor Mode Patch Page. You can double-
- check the version of the Orinoco drivers that shipped with your kernel
- by examining the first few lines of the orinoco.c file.
-
- The Orinoco patches require either Solomon Peachy's patch to libpcap
- 0.7.1 (see his libpcap-0.7.1-prism.diff file, or his RPMs of that
- version of libpcap), or the current CVS version of libpcap, which
- includes his patch (download it from the "Current Tar files" section
- of the tcpdump.org Web site). If you apply his patches to libpcap
- 0.7.1 and rebuild and install libpcap, or if you build and install the
- current CVS version of libpcap, you would have to rebuild Ethereal
- from source, linking it with that new version of libpcap; an Ethereal
- binary package would not work. Ethereal binary packages might work if
- you install the libpcap-0.7.1-1prism.i386.rpm RPM, as it might install
- a libpcap shared library in place of the one on your system.
-
- On other platforms, capturing raw 802.11 packets on Orinoco cards is
- not currently supported.
-
- Cards with the Atheros Communications AR5000 or AR5001 chipsets:
-
- You can capture raw 802.11 packets with AR5K cards on Linux systems
- with the v5_ar5k drivers. You will need the Linux wireless-tools
- version 25 or higher to put the card into monitor mode.
-
- Cards with the Texas Instruments ACX100 chipset:
-
- You can capture raw 802.11 packets with ACX100 cards on Linux systems
- with the ACX100 OSS drivers available from the ACX100 wireless network
- driver project SourceForge site.
-
- Other 802.11 interfaces:
-
- With other 802.11 interfaces, no platform allows Ethereal to capture
- raw 802.11 packets, as far as we know. If you know of other 802.11
- interfaces that are supported (note that there are many "Prism II
- cards", so your card might be a Prism II card), please let us know,
- and include URLs for sites containing any necessary patches to add
- this support.
-
- On platforms that don't allow Ethereal to capture raw 802.11 packets,
- the 802.11 network will appear like an Ethernet to Ethereal.
-
- Q 5.37: I'm trying to capture 802.11 traffic on Windows; why am I not
- seeing any packets?
-
- A: At least some 802.11 card drivers on Windows appear not to see any
- packets if they're running in promiscuous mode. Try turning
- promiscuous mode off; you'll only be able to see packets sent by and
- received by your machine, not third-party traffic, and it'll look like
- Ethernet traffic and won't include any management or control frames,
- but that's a limitation of the card drivers.
+ monitor mode; otherwise, when Wireshark (or TShark, or tcpdump) tries
+ to display IP addresses as host names, it will probably block for a
+ long time trying to resolve the name because it will not be able to
+ communicate with any DNS or NIS servers.
- Q 5.38: I'm trying to capture 802.11 traffic on Windows; why am I
- seeing packets received by the machine on which I'm capturing traffic,
- but not packets sent by that machine?
+ See the Wireshark Wiki item on 802.11 capturing for details.
- A: This appears to be another problem with promiscuous mode; try
- turning it off.
+ Q 10.2: How do I capture on an 802.11 device in monitor mode?
- Q 5.39: How can I capture packets with CRC errors?
+ A: Whether you will be able to capture in monitor mode depends on the
+ operating system, adapter, and driver you're using. See the previous
+ question for information on monitor mode, including a link to the
+ Wireshark Wiki page that gives details on 802.11 capturing.
- A: Ethereal can capture only the packets that the packet capture
- library - libpcap on UNIX-flavored OSes, and the WinPcap port to
- Windows of libpcap on Windows - can capture, and libpcap/WinPcap can
- capture only the packets that the OS's raw packet capture mechanism
- (or the WinPcap driver, and the underlying OS networking code and
- network interface drivers, on Windows) will allow it to capture.
+11. Viewing traffic
- Unless the OS always supplies packets with errors such as invalid CRCs
- to the raw packet capture mechanism, or can be configured to do so,
- invalid CRCs to the raw packet capture mechanism, Ethereal - and other
- programs that capture raw packets, such as tcpdump - cannot capture
- those packets. You will have to determine whether your OS needs to be
- so configured and, if so, can be so configured, configure it if
- necessary and possible, and make whatever changes to libpcap and the
- packet capture program you're using are necessary, if any, to support
- capturing those packets.
+ Q 11.1: Why am I seeing lots of packets with incorrect TCP checksums?
- Most OSes probably do not support capturing packets with invalid CRCs
- on Ethernet, and probably do not support it on most other link-layer
- types. Some drivers on some OSes do support it, such as some Ethernet
- drivers on FreeBSD; in those OSes, you might always get those packets,
- or you might only get them if you capture in promiscuous mode (you'd
- have to determine which is the case).
+ A: If the packets that have incorrect TCP checksums are all being sent
+ by the machine on which Wireshark is running, this is probably because
+ the network interface on which you're capturing does TCP checksum
+ offloading. That means that the TCP checksum is added to the packet by
+ the network interface, not by the OS's TCP/IP stack; when capturing on
+ an interface, packets being sent by the host on which you're capturing
+ are directly handed to the capture interface by the OS, which means
+ that they are handed to the capture interface without a TCP checksum
+ being added to them.
- Note that libpcap does not currently supply to programs that use it an
- indication of whether the packet's CRC was invalid (because the
- drivers themselves do not supply that information to the raw packet
- capture mechanism); therefore, Ethereal will not indicate which
- packets had CRC errors unless the FCS was captured (see the next
- question) and you're using Ethereal 0.9.15 and later, in which case
- Ethereal will check the CRC and indicate whether it's correct or not.
+ The only way to prevent this from happening would be to disable TCP
+ checksum offloading, but
+ 1. that might not even be possible on some OSes;
+ 2. that could reduce networking performance significantly.
- Q 5.40: How can I capture entire frames, including the FCS?
+ However, you can disable the check that Wireshark does of the TCP
+ checksum, so that it won't report any packets as having TCP checksum
+ errors, and so that it won't refuse to do TCP reassembly due to a
+ packet having an incorrect TCP checksum. That can be set as an
+ Wireshark preference by selecting "Preferences" from the "Edit" menu,
+ opening up the "Protocols" list in the left-hand pane of the
+ "Preferences" dialog box, selecting "TCP", from that list, turning off
+ the "Check the validity of the TCP checksum when possible" option,
+ clicking "Save" if you want to save that setting in your preference
+ file, and clicking "OK".
- A: Ethereal can't capture any data that the packet capture library -
- libpcap on UNIX-flavored OSes, and the WinPcap port to Windows of
- libpcap on Windows - can capture, and libpcap/WinPcap can capture only
- the data that the OS's raw packet capture mechanism (or the WinPcap
- driver, and the underlying OS networking code and network interface
- drivers, on Windows) will allow it to capture.
+ It can also be set on the Wireshark or TShark command line with a -o
+ tcp.check_checksum:false command-line flag, or manually set in your
+ preferences file by adding a tcp.check_checksum:false line.
- For any particular link-layer network type, unless the OS supplies the
- FCS of a frame as part of the frame, or can be configured to do so,
- Ethereal - and other programs that capture raw packets, such as
- tcpdump - cannot capture the FCS of a frame. You will have to
- determine whether your OS needs to be so configured and, if so, can be
- so configured, configure it if necessary and possible, and make
- whatever changes to libpcap and the packet capture program you're
- using are necessary, if any, to support capturing the FCS of a frame.
+ Q 11.2: I've just installed Wireshark, and the traffic on my local LAN
+ is boring. Where can I find more interesting captures?
- Most OSes do not support capturing the FCS of a frame on Ethernet, and
- probably do not support it on most other link-layer types. Some
- drivres on some OSes do support it, such as some (all?) Ethernet
- drivers on NetBSD and possibly the driver for Apple's gigabit Ethernet
- interface in Mac OS X; in those OSes, you might always get the FCS, or
- you might only get the FCS if you capture in promiscuous mode (you'd
- have to determine which is the case).
+ A: We have a collection of strange and exotic sample capture files at
+ http://wiki.wireshark.org/SampleCaptures
- Versions of Ethereal prior to 0.9.15 will not treat an Ethernet FCS in
- a captured packet as an FCS. 0.9.15 and later will attempt to
- determine whether there's an FCS at the end of the frame and, if it
- thinks there is, will display it as such, and will check whether it's
- the correct CRC-32 value or not.
+ Q 11.3: Why doesn't Wireshark correctly identify RTP packets? It shows
+ them only as UDP.
- Q 5.41: Ethereal hangs after I stop a capture.
+ A: Wireshark can identify a UDP datagram as containing a packet of a
+ particular protocol running atop UDP only if
+ 1. The protocol in question has a particular standard port number, and
+ the UDP source or destination port number is that port
+ 2. Packets of that protocol can be identified by looking for a
+ "signature" of some type in the packet - i.e., some data that, if
+ Wireshark finds it in some particular part of a packet, means that
+ the packet is almost certainly a packet of that type.
+ 3. Some other traffic earlier in the capture indicated that, for
+ example, UDP traffic between two particular addresses and ports
+ will be RTP traffic.
- A: The most likely reason for this is that Ethereal is trying to look
- up an IP address in the capture to convert it to a name (so that, for
- example, it can display the name in the source address or destination
- address columns), and that lookup process is taking a very long time.
+ RTP doesn't have a standard port number, so 1) doesn't work; it
+ doesn't, as far as I know, have any "signature", so 2) doesn't work.
- Ethereal calls a routine in the OS of the machine on which it's
- running to convert of IP addresses to the corresponding names. That
- routine probably does one or more of:
- * a search of a system file listing IP addresses and names;
- * a lookup using DNS;
- * on UNIX systems, a lookup using NIS;
- * on Windows systems, a NetBIOS-over-TCP query.
+ That leaves 3). If there's RTSP traffic that sets up an RTP session,
+ then, at least in some cases, the RTSP dissector will set things up so
+ that subsequent RTP traffic will be identified. Currently, that's the
+ only place we do that; there may be other places.
- If a DNS server that's used in an address lookup is not responding,
- the lookup will fail, but will only fail after a timeout while the
- system routine waits for a reply.
+ However, there will always be places where Wireshark is simply
+ incapable of deducing that a given UDP flow is RTP; a mechanism would
+ be needed to allow the user to specify that a given conversation should
+ be treated as RTP. As of Wireshark 0.8.16, such a mechanism exists; if
+ you select a UDP or TCP packet, the right mouse button menu will have a
+ "Decode As..." menu item, which will pop up a dialog box letting you
+ specify that the source port, the destination port, or both the source
+ and destination ports of the packet should be dissected as some
+ particular protocol.
+
+ Q 11.4: Why doesn't Wireshark show Yahoo Messenger packets in captures
+ that contain Yahoo Messenger traffic?
- In addition, on Windows systems, if the DNS lookup of the address
- fails, either because the server isn't responding or because there are
- no records in the DNS that could be used to map the address to a name,
- a NetBIOS-over-TCP query will be made. That query involves sending a
- message to the NetBIOS-over-TCP name service on that machine, asking
- for the name and other information about the machine. If the machine
- isn't running software that responds to those queries - for example,
- many non-Windows machines wouldn't be running that software - the
- lookup will only fail after a timeout. Those timeouts can cause the
- lookup to take a long time.
+ A: Wireshark only recognizes as Yahoo Messenger traffic packets to or
+ from TCP port 3050 that begin with "YPNS", "YHOO", or "YMSG". TCP
+ segments that start with the middle of a Yahoo Messenger packet that
+ takes more than one TCP segment will not be recognized as Yahoo
+ Messenger packets (even if the TCP segment also contains the beginning
+ of another Yahoo Messenger packet).
- If you disable network address-to-name translation - for example, by
- turning off the "Enable network name resolution" option in the "Name
- resolution" options in the dialog box you get by selecting
- "Preferences" from the "Edit" menu - the lookups of the address won't
- be done, which may speed up the process of reading the capture file
- after the capture is stopped. You can make that setting the default by
- using the "Save" button in that dialog box; note that this will save
- all your current preference settings.
-
- If Ethereal hangs when reading a capture even with network name
- resolution turned off, there might, for example, be a bug in one of
- Ethereal's dissectors for a protocol causing it to loop infinitely.
- The bug should be reported to the Ethereal developers' mailing list at
- ethereal-dev@ethereal.com.
+12. Filtering traffic
- On UNIX-flavored OSes, please try to force Ethereal to dump core, by
- sending it a SIGABRT signal (usually signal 6) with the kill command,
- and then get a stack trace if you have a debugger installed. A stack
- trace can be obtained by using your debugger (gdb in this example),
- the Ethereal binary, and the resulting core file. Here's an example of
- how to use the gdb command backtrace to do so.
- $ gdb ethereal core
- (gdb) backtrace
- ..... prints the stack trace
- (gdb) quit
- $
+ Q 12.1: I saved a filter and tried to use its name to filter the
+ display; why do I get an "Unexpected end of filter string" error?
- The core dump file may be named "ethereal.core" rather than "core" on
- some platforms (e.g., BSD systems)
+ A: You cannot use the name of a saved display filter as a filter. To
+ filter the display, you can enter a display filter expression - not the
+ name of a saved display filter - in the "Filter:" box at the bottom of
+ the display, and type the key or press the "Apply" button (that does
+ not require you to have a saved filter), or, if you want to use a saved
+ filter, you can press the "Filter:" button, select the filter in the
+ dialog box that pops up, and press the "OK" button.
- Also, if at all possible, please send a copy of the capture file that
- caused the problem; when capturing packets, Ethereal normally writes
- captured packets to a temporary file, which will probably be in /tmp
- or /var/tmp on UNIX-flavored OSes and \TEMP on Windows, so the capture
- file will probably be there. It will have a name beginning with ether,
- with some mixture of letters and numbers after that. Please don't send
- a trace file greater than 1 MB when compressed. If the trace file
- contains sensitive information (e.g., passwords), then please do not
- send it.
-
- Q 5.42: How can I search for, or filter, packets that have a
- particular string anywhere in them?
+ Q 12.2: How can I search for, or filter, packets that have a particular
+ string anywhere in them?
A: If you want to do this when capturing, you can't. That's a feature
that would be hard to implement in capture filters without changes to
and, on other platforms, is in the libpcap library.
In releases prior to 0.9.14, you also can't search for, or filter,
- packets containing a particular string even after you've captured
- them.
+ packets containing a particular string even after you've captured them.
In 0.9.14, you can search for, but not filter, packets that have a
particular string; this has been added to the "Find Frame" dialog
In 0.9.15 and later, you can search for those packets using either the
mechanism introduced in 0.9.14 or using the new "contains" operator in
filter expressions, which lets you search the entire packet or text
- string or byte string fields in the packet; the "contains" operator
- can also be used in expressions used to filter the display.
-
- Please send support questions about Ethereal to the
- ethereal-users[AT]ethereal.com mailing list.
- For corrections/additions/suggestions for this web page page (and not
- Ethereal support questions), please send email to
- ethereal-web[AT]ethereal.com .
- Last modified: Mon, February 16 2004.
+ string or byte string fields in the packet; the "contains" operator can
+ also be used in expressions used to filter the display.
+
+ Q 12.3: How do I filter a capture to see traffic for virus XXX?
+
+ A: For some viruses/worms there might be a capture filter to recognize
+ the virus traffic. Check the CaptureFilters page on the Wireshark Wiki
+ to see if anybody's added such a filter.
+
+ Note that Wireshark was not designed to be an intrusion detection
+ system; you might be able to use it as an IDS, but in most cases
+ software designed to be an IDS, such as Snort or Prelude, will probably
+ work better.
+
+ The Bleeding Edge of Snort has a collection of signatures for Snort to
+ detect various viruses, worms, and the like.
git.samba.org / obnox / wireshark / wip.git / blobdiff