
   The Ethereal 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
         to date version. The version of this snapshot can be found at
         the end of this document.

   INDEX


General Questions:

   1.1 Where can I get help?

   1.2 What protocols are currently supported?

   1.3 Are there any plans to support {your favorite protocol}?

   1.4 Can Ethereal read capture files from {your favorite network
   analyzer}?

   1.5 What devices can Ethereal use to capture packets?

   1.6 How do you pronounce Ethereal? Where did the name come from?

Downloading Ethereal:

   2.1 I downloaded the Win32 installer, but when I try to run it, I get
   an error.

   2.2 When I try to download the WinPcap driver and library, I can't get
   to the WinPcap Web site.

Installing Ethereal:

   3.1 I installed an Ethereal RPM, but Ethereal doesn't seem to be
   installed; only Tethereal is installed.

Building Ethereal:

   4.1 The configure script can't find pcap.h or bpf.h, but I have
   libpcap installed.

   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 SVN or a SVN snapshot?

   4.3 The link fails with a number of "Output line too long." messages
   followed by linker errors. 

   4.4 The link fails on Solaris because plugin_list is undefined. 

   4.5 The build fails on Windows because of conflicts between winsock.h
   and winsock2.h. 

Using Ethereal:

   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 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 I'm only seeing ARP packets when I try to capture traffic.

   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'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"? 

   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"? 

   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? 

   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"? 

   5.9 Can Ethereal capture on (my T1/E1 line, SS7 links, etc.)? 

   5.10 How do I put an interface into promiscuous mode?

   5.11 I can set a display filter just fine, but capture filters don't
   work.

   5.12 I'm entering valid capture filters, but I still get "parse error"
   errors.

   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.

   5.14 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.

   5.16 When I run Ethereal on Solaris 8, it dies with a Bus Error when I
   start it.

   5.17 When I run Ethereal, I get an error 

     Gtk-CRITICAL **: file gtkwindow.c: line 3107 (gtk_window_resize):
     assertion `height > 0' failed.

   5.18 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.

   5.19 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.

   5.20 When I try to run Ethereal, it complains about
   sprint_realloc_objid being undefined.

   5.21 I'm running Ethereal on Linux; why do my time stamps have only
   100ms resolution, rather than 1us resolution?

   5.22 I'm capturing packets on {Windows 95, Windows 98, Windows Me};
   why are the time stamps on packets wrong? 

   5.23 When I try to run Ethereal on Windows, it fails to run because it
   can't find packet.dll.

   5.24 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?

   5.25 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.

   5.26 I'm running Ethereal on Windows, and I'm not seeing any traffic
   being sent by the machine running Ethereal.

   5.27 I'm trying to capture traffic but I'm not seeing any.

   5.28 I have an XXX network card on my machine; if I try to capture on
   it, my machine crashes or resets itself. 

   5.29 My machine crashes or resets itself when I select "Start" from
   the "Capture" menu or select "Preferences" from the "Edit" menu. 

   5.30 Does Ethereal work on Windows Me? 

   5.31 Does Ethereal work on Windows XP? 

   5.32 Why doesn't Ethereal correctly identify RTP packets? It shows
   them only as UDP.

   5.33 Why doesn't Ethereal show Yahoo Messenger packets in captures
   that contain Yahoo Messenger traffic?

   5.34 Why do I get the error 

     Gdk-ERROR **: Palettized display (256-colour) mode not supported on
     Windows.
     aborting....

   when I try to run Ethereal on Windows?

   5.35 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? 

   5.36 I'm capturing packets on a machine on a VLAN; why don't the
   packets I'm capturing have VLAN tags? 

   5.37 How can I capture raw 802.11 packets, including non-data
   (management, beacon) packets? 

   5.38 How do I capture on an 802.11 device in monitor mode on Linux?

   5.39 How do I capture on an 802.11 device in monitor mode on FreeBSD?

   5.40 How do I capture on an 802.11 device in monitor mode on NetBSD?

   5.41 I'm trying to capture 802.11 traffic on Windows; why am I not
   seeing any packets? 

   5.42 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? 

   5.43 How can I capture packets with CRC errors? 

   5.44 How can I capture entire frames, including the FCS? 

   5.45 Ethereal hangs after I stop a capture. 

   5.46 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 518 supported protocols and media, listed
   below. Descriptions can be found in the ethereal(1) man page.

            3GPP2 A11
            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
            AIM Administrative
            AIM Advertisements
            AIM Buddylist Service
            AIM Chat Navigation
            AIM Chat Service
            AIM Directory Search
            AIM Generic Service
            AIM ICQ
            AIM Invitation Service
            AIM Location
            AIM Messaging
            AIM OFT
            AIM Popup
            AIM Privacy Management Service
            AIM Server Side Info
            AIM Signon
            AIM Statistics
            AIM Translate
            AIM User Lookup
            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 IS-801 (Location Services (PLD))
            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
            Apple IP-over-IEEE 1394
            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
            BEA Tuxedo
            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
            Basic Encoding Rules (ASN.1 X.690)
            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
            Cast Client Control Protocol
            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
            Compuserve GIF
            Connectionless Lightweight Directory Access Protocol
            Cross Point Frame Injector
            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 Directory Acl Interface
            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 NCS 1.5.1 Local Location Broker
            DCE/RPC Operations between registry server replicas
            DCE/RPC Prop Attr
            DCE/RPC RS_ACCT
            DCE/RPC RS_BIND
            DCE/RPC RS_MISC
            DCE/RPC RS_PROP_ACCT
            DCE/RPC RS_UNIX
            DCE/RPC Registry Password Management
            DCE/RPC Registry Server Attributes Schema
            DCE/RPC Registry server propagation interface - ACLs.
            DCE/RPC Registry server propagation interface - PGO items
            DCE/RPC Registry server propagation interface - properties and poli
cies
            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
            DFS Calls
            DHCPv6
            DICOM
            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 Protocol
            Distributed Network Protocol 3.0
            Domain Name Service
            Dynamic DNS Tools Protocol
            Echo
            Encapsulating Security Payload
            Endpoint Name Resolution Protocol
            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)
            GSM Short Message Service User Data
            General Inter-ORB Protocol
            Generic Routing Encapsulation
            Generic Security Service Application Program Interface
            Gnutella Protocol
            H225
            H235-SECURITY-MESSAGES
            H245
            H4501
            HP Extended Local-Link Control
            HP Remote Maintenance Protocol
            Hummingbird NFS Daemon
            HyperSCSI
            Hypertext Transfer Protocol
            ICQ Protocol
            IEEE 802.11 Radiotap Capture header
            IEEE 802.11 wireless LAN
            IEEE 802.11 wireless LAN management frame
            ILMI
            IP Device Control (SS7 over IP)
            IP Over FC
            IP Payload Compression
            IP Virtual Services Sync Daemon
            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 8823 OSI Presentation Protocol
            ISO 9542 ESIS Routeing Information Exchange Protocol
            ITU-T E.164 number
            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
            Inter-Asterisk eXchange v2
            InterSwitch Message 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
            JPEG File Interchange Format
            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
            Line-based text data
            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 GPRS
            Logical-Link Control
            Lucent/Ascend debug output
            MDS Header
            MIME Multipart Media Encapsulation
            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
            Media Type
            Media Type: message/http
            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 Distributed Link Tracking Server Service
            Microsoft Encrypted File System Service
            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
            Multiprotocol Label Switching Echo
            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
            NetWare Serialization 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
            Novell Modular Authentication Service
            Null/Loopback
            OSI ISO 8571 FTAM Protocol
            OSI ISO/IEC 10035-1 ACSE Protocol
            Open Shortest Path First
            OpenBSD Encapsulating device
            OpenBSD Packet Filter log file
            OpenBSD Packet Filter log file, pre 3.4
            Optimized Link State Routing Protocol
            PC NFS
            POSTGRESQL
            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 OSI Control Protocol
            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)
            PacketCable
            Point-to-Point Protocol
            Point-to-Point Tunnelling Protocol
            Portmap
            Post Office Protocol
            Pragmatic General Multicast
            Precision Time Protocol (IEEE1588)
            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 Publish-Subscribe Wire 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
            Signaling Compression
            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
            Sipfrag
            Skinny Client Control Protocol
            SliMP3 Communication Protocol
            Socks Protocol
            SoulSeek Protocol
            Spanning Tree Protocol
            Spnego
            Stream Control Transmission Protocol
            Subnetwork Dependent Convergence Protocol
            Symantec Enterprise Firewall
            Synchronous Data Link Control (SDLC)
            Syslog message
            Systems Network Architecture
            Systems Network Architecture XID
            T38
            TACACS
            TACACS+
            TEI Management Procedure, Channel D (LAPD)
            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
            WAP Session Initiation Request
            Web Cache Coordination Protocol
            WebSphere MQ
            WebSphere MQ Programmable Command Formats
            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
            giFT Internet File Transfer
            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
   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.

   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 its own format, or has added
   proprietary extensions to another format, in order to make Ethereal
   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
   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.

   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?

   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
   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).

   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

   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?

   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.

   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 something
   that started out as an Ethernet analyzer.

Downloading Ethereal

   Q 2.1: I downloaded the Win32 installer, but when I try to run it, I
   get an error.

   A: The program you used to download it may have downloaded it
   incorrectly. Web browsers sometimes may do this.

   Try downloading it with, for example:
     * Wget, for which Windows binaries are available on the SunSITE FTP
       server at sunsite.tk or Heiko Herold's windows wget spot - wGetGUI
       offers a GUI interface that uses wget;
     * WS_FTP from Ipswitch,
     * the ftp command that comes with Windows.

   If you use the ftp command, make sure you do the transfer in binary
   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

   Q 3.1: I installed an Ethereal RPM, but Ethereal doesn't seem to be
   installed; only Tethereal is installed.

   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.

   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+.

   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.

   A: Are you sure pcap.h and bpf.h are installed? The official
   distribution of libpcap only installs the libpcap.a library file when
   "make install" is run. To install pcap.h and bpf.h, you must run "make
   install-incl". If you're running Debian or Redhat, make sure you have
   the "libpcap-dev" or "libpcap-devel" packages installed.

   It's also possible that pcap.h and bpf.h have been installed in a
   strange location. If this is the case, you may have to tweak
   aclocal.m4.

   Q 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 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.

   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
   line length limit too low to allow libtool to work; /usr/xpg4/bin/sed
   can handle it, as can GNU sed if you have it installed.

   On Solaris, changing your command search path to search /usr/xpg4/bin
   before /usr/bin should make the problem go away; on any platform on
   which you have this problem, installing GNU sed and changing your
   command path to search the directory in which it is installed before
   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.

   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,
   and try getting the 1.2.10 versions from that site, or the versions
   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
   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.

   A: As of Ethereal 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
   developer's pack. The symptoms of this failure are conflicts between
   definitions in winsock.h and in winsock2.h; Ethereal 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
   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.

Using Ethereal

   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.

   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.

   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.

   Note also that on the Linksys Web site, they say that their
   auto-sensing hubs "broadcast the 10Mb packets to the port that operate
   at 10Mb only and broadcast the 100Mb packets to the ports that operate
   at 100Mb only", which would indicate that if you sniff on a 10Mb port,
   you will not see traffic coming sent to a 100Mb port, and vice versa.
   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.

   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.

   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
   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:
     * 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.

   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.

   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).

   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
   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.

   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
   address for some other interface - and a network interface not in
   promiscuous mode will receive only unicast traffic sent to the MAC
   address for that interface, broadcast traffic, and multicast traffic
   sent to a multicast MAC address the interface is set up to receive.

   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.

   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.

   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
   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. Try listing the interfaces with WinDump; see the WinDump
   Web site or the local mirror of 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 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;
     * 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, 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.

   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).

   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.

   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"?

   A: This is really the same question as the previous one; see the
   response to that question.

   Q 5.9: Can Ethereal capture on (my T1/E1 line, SS7 links, etc.)?

   A: Ethereal 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
   running as an IP interface in order to support traffic capture.

   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.

   Note, however, that:
     * the form of promiscuous mode that libpcap (the library that
       programs such as tcpdump, Ethereal, 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;
     * 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.

   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.

   A: Capture filters currently use a different syntax than display
   filters. Here's the corresponding section from the ethereal(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
   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."

   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.

   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
   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
   bug.

   The bug was fixed in libpcap 0.6; 0.4[.x] and 0.5[.x] versions of
   libpcap have this bug, but 0.6[.x] and later versions don't.

   Versions of WinPcap prior to 2.3 are based on pre-0.6 versions of
   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 Ethereal 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.

   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.

   Q 5.14: Why am I seeing lots of packets with incorrect TCP checksums?

   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.

   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.

   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".

   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.

   Q 5.15: I've just installed Ethereal, and the traffic on my local LAN
   is boring.

   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.)

   Similar problems may exist with older versions of GTK+ for earlier
   versions of Solaris.

   Q 5.17: When I run Ethereal, I get an error

     Gtk-CRITICAL **: file gtkwindow.c: line 3107 (gtk_window_resize):
     assertion `height > 0' failed.

   A: This is a bug in Ethereal 0.10.5, which will be fixed in the next
   release of Ethereal. To work around this bug:
    1. On Windows, this message will appear in a console window; do NOT,
       under any circumstances, close that window!
    2. Make sure the "Save window size" prefrence is set the "User
       Interface" prefrences in the preferences window opened by
       "Preferences" under the "Edit" menu.
    3. Quit Ethereal.
    4. On Windows, a "Press any key to exit" message might appear in the
       command window; if that message appears in the window, click on
       that window and press any key (such as Enter).

   The next time Ethereal starts, it should not produce that error
   message.

   Q 5.18: 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 0.10.1 and
   later releases. 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 SVN version from
   anonymous SVN or a nightly SVN 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 SVN 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 SVN version, as you'll need to have more
   tools and make more steps to generate from the SVN 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 5.19: 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.

   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 5.20: When I try to run Ethereal, it complains about
   sprint_realloc_objid being undefined.

   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.

   Q 5.21: I'm running Ethereal on Linux; why do my time stamps have only
   100ms resolution, rather than 1us resolution?

   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.

   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.

   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.

   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.

   Q 5.22: I'm capturing packets on {Windows 95, Windows 98, Windows Me};
   why are the time stamps on packets wrong?

   A: This is due to a bug in WinPcap. The bug should be fixed in WinPcap
   3.0.

   Q 5.23: When I try to run Ethereal on Windows, it fails to run because
   it can't find packet.dll.

   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.

   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.

   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 5.24: 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 5.25: 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: 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
   libpcap/WinPcap-based application.

   Q 5.26: I'm running Ethereal on Windows, and I'm not seeing any
   traffic being sent by the machine running Ethereal.

   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.

   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.

   Q 5.27: I'm trying to capture traffic but I'm not seeing any.

   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?

   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.

   Otherwise, on Windows, see the response to this question and, on a
   UNIX-flavored OS, see the response to this question.

   Q 5.28: I have an XXX network card on my machine; if I try to capture
   on it, my machine crashes or resets itself.

   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 (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).

   Q 5.29: My machine crashes or resets itself when I select "Start" from
   the "Capture" menu or select "Preferences" from the "Edit" menu.

   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.

   Q 5.30: Does Ethereal 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 Ethereal as well.

   Q 5.31: Does Ethereal work on Windows XP?

   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 5.32: Why doesn't Ethereal correctly identify RTP packets? It shows
   them only as UDP.

   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.

   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.

   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.

   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 5.33: Why doesn't Ethereal show Yahoo Messenger packets in captures
   that contain Yahoo Messenger traffic?

   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).

   Q 5.34: Why do I get the error

     Gdk-ERROR **: Palettized display (256-colour) mode not supported on
     Windows.
     aborting....

   when I try to run Ethereal on Windows?

   A: Ethereal is built using the GTK+ toolkit, which supports most
   UNIX-flavored OSes, and also supports Windows.

   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.

   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 5.35: 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: 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.

   Q 5.36: I'm capturing packets on a machine on a VLAN; why don't the
   packets I'm capturing have VLAN tags?

   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 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.

   Q 5.37: 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.

   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.

   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.

   There are FAQ items below with information on capturing in monitor
   mode on Linux, FreeBSD, and NetBSD.

   On Windows, you will not be able to capture in monitor mode on any
   interfaces, and you might not be able to capture in promiscuous mode,
   either. You might have some success in promiscuous mode with Centrino
   interfaces, although you will need the not-yet-released Ethereal
   0.10.6 in order to have the non-data packets recognized and properly
   dissected.

   You will not be able to capture in monitor mode on any other platforms
   (including Mac OS X). You might be able to capture in promiscuous
   mode, but this won't capture non-data packets.

   Q 5.38: How do I capture on an 802.11 device in monitor mode on Linux?

   A: Whether you will be able to capture in monitor mode depends on the
   card and driver you're using. See this page of Linux 802.11b
   information for details on 802.11b wireless cards, including
   information on the chips they use, and see this page of Linux
   802.11b+/a/g information for details on 802.11b+, 802.11a, and 802.11g
   wireless cards, including information on the chips they use.

   Cisco Aironet cards:

   On Linux with the driver in the 2.4.6 through 2.4.19 kernel:
    1. Put the card into monitor mode with the command echo "Mode: rfmon"
       >/proc/driver/aironet/interface/Config. If you want to capture
       traffic for any BSS rather than just the BSS with which the card
       is associated, use "Mode: y" rather than "Mode: rfmon".
    2. When the capture completes, turn off monitor mode with the command
       echo "Mode: ess" >/proc/driver/aironet/interface/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:

   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), or with the hostap driver for Prism II/2.5/3.

   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.

   With the linux-wlan-ng driver, you should:
    1. Put the card into monitor mode with the command wlanctl-ng
       interface lnxreq_wlansniffer enable=true. You should request
       802.11 headers by adding to that command the option
       prismheader=true or, if supported, wlanheader=true; the latter
       might require libpcap 0.8.1 or later. You can also set the channel
       to monitor by adding the argument channel=channel_number to that
       command.
    2. When the capture completes, turn off monitor mode with the command
       wlanctl-ng interface enable=false. You might also have to turn
       802.11 headers off with prismheader=false or wlanheader=false.

   See the wlan-ng FAQ for additional information, although note that it
   does not appear to be up-to-date.

   With the hostap driver, you should:
    1. Put the card into monitor mode with the command iwpriv interface
       monitor mode, where mode is 2 or 3 (mode 3 would require libpcap
       0.8.1 or later).
    2. When the capture completes, turn off monitor mode with the command
       iwpriv interface monitor 0.

   Orinoco Silver and Gold cards:

   On Linux systems, the current version of the SourceForge orinoco_cs
   driver should support monitor mode. There also exist patches to
   earlier versions of the Orinoco driver, on the Orinoco Monitor Mode
   Patch Page, to add support for monitor mode. You will have to
   determine which version of the driver you have, and select the
   appropriate patch, if one is necessary.

   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 and SourceForge driver 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.

   With a driver that supports monitor mode, you should:
    1. Put the card into monitor mode with the command iwpriv interface
       monitor mode channel_number, where mode is 1 or 2, and
       channel_number is the number of the channel to monitor.
    2. When the capture completes, turn off monitor mode with the command
       iwpriv interface monitor 0.

   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.

   With that driver:

    1. Put the card into monitor mode with the command iwpriv interface
       monitor 2 channel_number, where channel_number is the number of
       the channel to monitor.
    2. When the capture completes, turn off monitor mode with the command
       iwpriv interface monitor 0.

   Cards with Atheros Communications 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. It might also
   be possible to do so with the madwifi driver. If you have information
   on how to do this, please supply it to us, so that we can incorporate
   that information into the FAQ in the future.

   Other cards:

   It might be possible to capture in monitor mode on other cards. If so,
   please supply us with information on how to do so, so that we can
   incorporate that information into this FAQ in the future.

   Q 5.39: How do I capture on an 802.11 device in monitor mode on
   FreeBSD?

   A: On FreeBSD 5.2 and later, you should be able to capture in monitor
   mode on 802.11 interfaces supported by the wi and acx drivers, if
   Ethereal is linked with libpcap 0.8.1 or later, and on 802.11
   interfaces supported by the an driver, if Ethereal is linked with
   libpcap 0.7.1 or later.

   For cards supported by the wi and acx drivers, you should:
    1. Put the card into monitor mode with the command ifconfig interface
       monitor. You can also set the channel to monitor by adding the
       argument channel channel_number to that command.
    2. When you start the capture, in Ethereal select "802.11" as the
       "Link-layer header type", and in Tethereal add the command-line
       argument -y 802.11.
    3. When the capture completes, turn off monitor mode with the command
       ifconfig interface -monitor.

   For cards supported by the an driver, you should:
    1. Put the card into monitor mode with the command ancontrol -i
       interface -M flag, where 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).
    2. When the capture completes, turn off monitor mode with the command
       ancontrol -i interface -M 0.

   Don't add 8 in to flag; Ethereal currently doesn't support the full
   Aironet header.

   On FreeBSD 4.6 through 5.1, you should be able to capture in monitor
   mode on 802.11 interfaces supported by the an driver, but not on any
   other interfaces; see the instructions for FreeBSD 5.2 or later for
   those cards.

   In FreeBSD 4.5 and earlier, you will not be able to capture in monitor
   mode on 802.11 interfaces (no drivers supported it prior to 4.5, and
   in 4.5 the an driver had bugs that caused packets not to be captured
   correctly).

   Q 5.40: How do I capture on an 802.11 device in monitor mode on
   NetBSD?

   A: On NetBSD 2.0-beta and later, you should be able to capture in
   monitor mode on 802.11 interfaces supported by the wi and acx drivers,
   if Ethereal is linked with libpcap 0.8.1 or later. The instructions
   are the same as for FreeBSD 5.2 and later.

   Q 5.41: 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.

   Q 5.42: 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: This appears to be another problem with promiscuous mode; try
   turning it off.

   Q 5.43: How can I capture packets with CRC errors?

   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.

   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.

   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).

   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.

   Q 5.44: How can I capture entire frames, including the FCS?

   A: Ethereal 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.

   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.

   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 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 5.45: Ethereal hangs after I stop a capture.

   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.

   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.

   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.

   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.

   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.

   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
        $

   The core dump file may be named "ethereal.core" rather than "core" on
   some platforms (e.g., BSD systems)

   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 5.46: 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
   the capture filter code, which, on many platforms, is in the OS kernel
   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.

   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
   ("Find Frame" under the "Edit" menu, or control-F).

   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 (and not
   Ethereal support questions), please send email to
   ethereal-web[AT]ethereal.com .
   Last modified: Sun, August 08 2004.
