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editcap(1)              The Wireshark Network Analyzer              editcap(1)




NAME

       editcap - Edit and/or translate the format of capture files


SYNOPSIS

       editcap [ -A <start time> ] [ -B <stop time> ]
       [ -c <packets per file> ] [ -C <choplen> ] [ -E <error probability> ]
       [ -F <file format> ] [ -h ] [ -i <seconds per file> ] [ -r ]
       [ -s <snaplen> ] [ -S <strict time adjustment> ]
       [ -t <time adjustment> ] [ -T <encapsulation type> ] [ -v ] infile
       outfile [ packet#[-packet#] ... ]

       editcap  -d  |  -D <dup window>  |  -w <dup time window>  [ -v ] infile
       outfile


DESCRIPTION

       Editcap is a program that reads some or all of the captured packets
       from the infile, optionally converts them in various ways and writes
       the resulting packets to the capture outfile (or outfiles).

       By default, it reads all packets from the infile and writes them to the
       outfile in pcap file format.

       An optional list of packet numbers can be specified on the command
       tail; individual packet numbers separated by whitespace and/or ranges
       of packet numbers can be specified as start-end, referring to all
       packets from start to end.  By default the selected packets with those
       numbers will not be written to the capture file.  If the -r flag is
       specified, the whole packet selection is reversed; in that case only
       the selected packets will be written to the capture file.

       Editcap can also be used to remove duplicate packets.  Several
       different options (-d, -D and -w) are used to control the packet window
       or relative time window to be used for duplicate comparison.

       Editcap is able to detect, read and write the same capture files that
       are supported by Wireshark.  The input file doesn't need a specific
       filename extension; the file format and an optional gzip compression
       will be automatically detected.  Near the beginning of the DESCRIPTION
       section of wireshark(1) or
       <http://www.wireshark.org/docs/man-pages/wireshark.html> is a detailed
       description of the way Wireshark handles this, which is the same way
       Editcap handles this.

       Editcap can write the file in several output formats. The -F flag can
       be used to specify the format in which to write the capture file;
       editcap -F provides a list of the available output formats.


OPTIONS

       -A  <start time>
           Saves only the packets whose timestamp is on or after start time.
           The time is given in the following format YYYY-MM-DD HH:MM:SS

       -B  <stop time>
           Saves only the packets whose timestamp is before stop time.  The
           time is given in the following format YYYY-MM-DD HH:MM:SS

       -c  <packets per file>
           Splits the packet output to different files based on uniform packet
           counts with a maximum of <packets per file> each. Each output file
           will be created with a suffix -nnnnn, starting with 00000. If the
           specified number of packets is written to the output file, the next
           output file is opened. The default is to use a single output file.

       -C  <choplen>
           Sets the chop length to use when writing the packet data. Each
           packet is chopped by a few <choplen> bytes of data. Positive values
           chop at the packet beginning while negative values chop at the
           packet end.

           This is useful for chopping headers for decapsulation of an entire
           capture or in the rare case that the conversion between two file
           formats leaves some random bytes at the end of each packet.

       -d  Attempts to remove duplicate packets.  The length and MD5 hash of
           the current packet are compared to the previous four (4) packets.
           If a match is found, the current packet is skipped.  This option is
           equivalent to using the option -D 5.

       -D  <dup window>
           Attempts to remove duplicate packets.  The length and MD5 hash of
           the current packet are compared to the previous <dup window> - 1
           packets.  If a match is found, the current packet is skipped.

           The use of the option -D 0 combined with the -v option is useful in
           that each packet's Packet number, Len and MD5 Hash will be printed
           to standard out.  This verbose output (specifically the MD5 hash
           strings) can be useful in scripts to identify duplicate packets
           across trace files.

           The <dup window> is specified as an integer value between 0 and
           1000000 (inclusive).

           NOTE: Specifying large <dup window> values with large tracefiles
           can result in very long processing times for editcap.

       -E  <error probability>
           Sets the probability that bytes in the output file are randomly
           changed.  Editcap uses that probability (between 0.0 and 1.0
           inclusive) to apply errors to each data byte in the file.  For
           instance, a probability of 0.02 means that each byte has a 2%
           chance of having an error.

           This option is meant to be used for fuzz-testing protocol
           dissectors.

       -F  <file format>
           Sets the file format of the output capture file.  Editcap can write
           the file in several formats, editcap -F provides a list of the
           available output formats. The default is the pcap format.

       -h  Prints the version and options and exits.

       -i  <seconds per file>
           Splits the packet output to different files based on uniform time
           intervals using a maximum interval of <seconds per file> each. Each
           output file will be created with a suffix -nnnnn, starting with
           00000. If packets for the specified time interval are written to
           the output file, the next output file is opened. The default is to
           use a single output file.

       -r  Reverse the packet selection.  Causes the packets whose packet
           numbers are specified on the command line to be written to the
           output capture file, instead of discarding them.

       -s  <snaplen>
           Sets the snapshot length to use when writing the data.  If the -s
           flag is used to specify a snapshot length, packets in the input
           file with more captured data than the specified snapshot length
           will have only the amount of data specified by the snapshot length
           written to the output file.

           This may be useful if the program that is to read the output file
           cannot handle packets larger than a certain size (for example, the
           versions of snoop in Solaris 2.5.1 and Solaris 2.6 appear to reject
           Ethernet packets larger than the standard Ethernet MTU, making them
           incapable of handling gigabit Ethernet captures if jumbo packets
           were used).

       -S  <strict time adjustment>
           Time adjust selected packets to insure strict chronological order.

           The <strict time adjustment> value represents relative seconds
           specified as [-]seconds[.fractional seconds].

           As the capture file is processed each packet's absolute time is
           possibly adjusted to be equal to or greater than the previous
           packet's absolute timestamp depending on the <strict time
           adjustment> value.

           If <strict time adjustment> value is 0 or greater (e.g. 0.000001)
           then only packets with a timestamp less than the previous packet
           will adjusted.  The adjusted timestamp value will be set to be
           equal to the timestamp value of the previous packet plus the value
           of the <strict time adjustment> value.  A <strict time adjustment>
           value of 0 will adjust the minimum number of timestamp values
           necessary to insure that the resulting capture file is in strict
           chronological order.

           If <strict time adjustment> value is specified as a negative value,
           then the timestamp values of all packets will be adjusted to be
           equal to the timestamp value of the previous packet plus the
           absolute value of the <lt>strict time adjustment<gt> value. A
           <strict time adjustment> value of -0 will result in all packets
           having the timestamp value of the first packet.

           This feature is useful when the trace file has an occasional packet
           with a negative delta time relative to the previous packet.

       -t  <time adjustment>
           Sets the time adjustment to use on selected packets.  If the -t
           flag is used to specify a time adjustment, the specified adjustment
           will be applied to all selected packets in the capture file.  The
           adjustment is specified as [-]seconds[.fractional seconds].  For
           example, -t 3600 advances the timestamp on selected packets by one
           hour while -t -0.5 reduces the timestamp on selected packets by
           one-half second.

           This feature is useful when synchronizing dumps collected on
           different machines where the time difference between the two
           machines is known or can be estimated.

       -T  <encapsulation type>
           Sets the packet encapsulation type of the output capture file.  If
           the -T flag is used to specify an encapsulation type, the
           encapsulation type of the output capture file will be forced to the
           specified type.  editcap -T provides a list of the available types.
           The default type is the one appropriate to the encapsulation type
           of the input capture file.

           Note: this merely forces the encapsulation type of the output file
           to be the specified type; the packet headers of the packets will
           not be translated from the encapsulation type of the input capture
           file to the specified encapsulation type (for example, it will not
           translate an Ethernet capture to an FDDI capture if an Ethernet
           capture is read and '-T fddi' is specified). If you need to
           remove/add headers from/to a packet, you will need
           od(1)/text2pcap(1).

       -v  Causes editcap to print verbose messages while it's working.

           Use of -v with the de-duplication switches of -d, -D or -w will
           cause all MD5 hashes to be printed whether the packet is skipped or
           not.

       -w  <dup time window>
           Attempts to remove duplicate packets.  The current packet's arrival
           time is compared with up to 1000000 previous packets.  If the
           packet's relative arrival time is less than or equal to the <dup
           time window> of a previous packet and the packet length and MD5
           hash of the current packet are the same then the packet to skipped.
           The duplicate comparison test stops when the current packet's
           relative arrival time is greater than <dup time window>.

           The <dup time window> is specified as seconds[.fractional seconds].

           The [.fractional seconds] component can be specified to nine (9)
           decimal places (billionths of a second) but most typical trace
           files have resolution to six (6) decimal places (millionths of a
           second).

           NOTE: Specifying large <dup time window> values with large
           tracefiles can result in very long processing times for editcap.

           NOTE: The -w option assumes that the packets are in chronological
           order.  If the packets are NOT in chronological order then the -w
           duplication removal option may not identify some duplicates.


EXAMPLES

       To see more detailed description of the options use:

           editcap -h

       To shrink the capture file by truncating the packets at 64 bytes and
       writing it as Sun snoop file use:

           editcap -s 64 -F snoop capture.pcap shortcapture.snoop

       To delete packet 1000 from the capture file use:

           editcap capture.pcap sans1000.pcap 1000

       To limit a capture file to packets from number 200 to 750 (inclusive)
       use:

           editcap -r capture.pcap small.pcap 200-750

       To get all packets from number 1-500 (inclusive) use:

           editcap -r capture.pcap first500.pcap 1-500

       or

           editcap capture.pcap first500.pcap 501-9999999

       To exclude packets 1, 5, 10 to 20 and 30 to 40 from the new file use:

           editcap capture.pcap exclude.pcap 1 5 10-20 30-40

       To select just packets 1, 5, 10 to 20 and 30 to 40 for the new file
       use:

           editcap -r capture.pcap select.pcap 1 5 10-20 30-40

       To remove duplicate packets seen within the prior four frames use:

           editcap -d capture.pcap dedup.pcap

       To remove duplicate packets seen within the prior 100 frames use:

           editcap -D 101 capture.pcap dedup.pcap

       To remove duplicate packets seen equal to or less than 1/10th of a
       second:

           editcap -w 0.1 capture.pcap dedup.pcap

       To display the MD5 hash for all of the packets (and NOT generate any
       real output file):

           editcap -v -D 0 capture.pcap /dev/null

       or on Windows systems

           editcap -v -D 0 capture.pcap NUL

       To advance the timestamps of each packet forward by 3.0827 seconds:

           editcap -t 3.0827 capture.pcap adjusted.pcap

       To insure all timestamps are in strict chronological order:

           editcap -S 0 capture.pcap adjusted.pcap

       To introduce 5% random errors in a capture file use:

           editcap -E 0.05 capture.pcap capture_error.pcap


SEE ALSO

       pcap(3), wireshark(1), tshark(1), mergecap(1), dumpcap(1), capinfos(1),
       text2pcap(1), od(1), pcap-filter(7) or tcpdump(8)


NOTES

       Editcap is part of the Wireshark distribution.  The latest version of
       Wireshark can be found at <http://www.wireshark.org>.

       HTML versions of the Wireshark project man pages are available at:
       <http://www.wireshark.org/docs/man-pages>.


AUTHORS

         Original Author
         -------- ------
         Richard Sharpe           <sharpe[AT]ns.aus.com>


         Contributors
         ------------
         Guy Harris               <guy[AT]alum.mit.edu>
         Ulf Lamping              <ulf.lamping[AT]web.de>



1.10.2                            2013-07-28                        editcap(1)

wireshark 1.10.2 - Generated Mon Sep 16 07:19:01 CDT 2013