Provided by: wireshark-common_4.2.6-1_amd64 bug

NAME

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

SYNOPSIS

       editcap [ -a <frame:comment> ] [ -A <start time> ] [ -B <stop time> ]
       [ -c <packets per file> ] [ -C [offset:]<choplen> ] [ -E <error probability> ]
       [ -F <file format> ] [ -i <seconds per file> ] [ -o <change offset> ] [ -L ] [ -r ]
       [ -s <snaplen> ] [ -S <strict time adjustment> ] [ -t <time adjustment> ]
       [ -T <encapsulation type> ] [ -V ] [ --inject-secrets <secrets type>,<file> ]
       [ --discard-all-secrets ] [ --capture-comment <comment> ] [ --discard-capture-comment ]
       [ --discard-packet-comments ] infile outfile [ packet#[-packet#] ... ]

       editcap -d -D <dup window> -w <dup time window> [ -V ] [ -I <bytes to ignore> ]
       [ --skip-radiotap-header ] [ --set-unused ] infile outfile

       editcap -h|--help

       editcap -v|--version

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 pcapng
       file format. Use '-' for infile or outfile to read from standard input or write to
       standard output, respectively.

       The -A and -B option allow you to limit the time range from which packets are read from
       the infile.

       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 can be used to assign comment strings to frame numbers.

       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, zstd or lz4 compression will be automatically detected. Near the
       beginning of the DESCRIPTION section of wireshark(1) or
       https://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  <framenum:comment>

           For the specified frame number, assign the given comment string. Can be repeated for
           multiple frames. Quotes should be used with comment strings that include spaces.

       -A  <start time>

           Reads only the packets whose timestamp is on or after <start time>. The time may be
           given either in ISO 8601 format or in Unix epoch timestamp format.

           ISO 8601 format is either

               YYYY-MM-DD HH:MM:SS[.nnnnnnnnn][Z|±hh:mm]

           or

               YYYY-MM-DDTHH:MM:SS[.nnnnnnnnn][Z|±hh:mm]

           The fractional seconds are optional, as is the time zone offset from UTC (in which
           case local time is assumed).

           Unix epoch format is in seconds since the Unix epoch and nanoseconds, with either a
           period or a comma separating the seconds and nanoseconds. The nanoseconds are
           optional. The Unix epoch is 1970-01-01 00:00:00 UTC, so this format is not local time.

       -B  <stop time>

           Reads only the packets whose timestamp is before <stop time>. The time may be given
           either in ISO 8601 format or in Unix epoch timestamp format.

           ISO 8601 format is either

               YYYY-MM-DD HH:MM:SS[.nnnnnnnnn][Z|±hh:mm]

           or

               YYYY-MM-DDTHH:MM:SS[.nnnnnnnnn][Z|±hh:mm]

           The fractional seconds are optional, as is the time zone offset from UTC (in which
           case local time is assumed).

           Unix epoch format is in seconds since the Unix epoch and nanoseconds, with either a
           period or a comma separating the seconds and nanoseconds. The nanoseconds are
           optional. The Unix epoch is 1970-01-01 00:00:00 UTC, so this format is not local time.

       -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 an infix _nnnnn[_YYYYmmddHHMMSS] inserted before
           the file extension (which may be null) of outfile. The infix consists of the ordinal
           number of the output file, starting with 00000, followed by the timestamp of its first
           packet. The timestamp is omitted if the input file does not contain timestamp
           information.

           After 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. This option conflicts with
           -i.

       -C  [offset:]<choplen>

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

           If an optional offset precedes the <choplen>, then the bytes chopped will be offset
           from that value. Positive offsets are from the packet beginning, while negative
           offsets are from the packet end.

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

               Note
               This option can be used more than once, effectively allowing you to chop bytes
               from up to two different areas of a packet in a single pass provided that you
               specify at least one chop length as a positive value and at least one as a
               negative value. All positive chop lengths are added together as are all negative
               chop lengths.

       -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 error. 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 pcapng format.

       -h|--help
           Print the version number and options and exit.

       -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. Floating point values (e.g. 0.5) are
           allowed.

           Each output file will be created with an infix _nnnnn[_YYYYmmddHHMMSS] inserted before
           the file extension (which may be null) of outfile. The infix consists of the ordinal
           number of the output file, starting with 00000, followed by the timestamp of its first
           packet. The timestamp is omitted if the input file does not contain timestamp
           information.

           After 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. This option
           conflicts with -c.

       -I  <bytes to ignore>

           Ignore the specified number of bytes at the beginning of the frame during MD5 hash
           calculation, unless the frame is too short, then the full frame is used. Useful to
           remove duplicated packets taken on several routers (different mac addresses for
           example) e.g. -I 26 in case of Ether/IP will ignore ether(14) and IP header(20 - 4(src
           ip) - 4(dst ip)). The default value is 0.

       -L

           Adjust the original frame length accordingly when chopping and/or snapping (in
           addition to the captured length, which is always adjusted regardless of whether -L is
           specified or not). See also -C <choplen> and -s <snaplen>.

       -o  <change offset>

           When used in conjunction with -E, skip some bytes from the beginning of the packet
           from being changed. In this way some headers don’t get changed, and the fuzzer is more
           focused on a smaller part of the packet. Keeping a part of the packet fixed the same
           dissector is triggered, that make the fuzzing more precise.

       -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).

       --seed  <seed>

           When used in conjunction with -E, set the seed for the pseudo-random number generator.
           This is useful for recreating a particular sequence of errors.

       --skip-radiotap-header

           Skip the radiotap header of each frame when checking for packet duplicates. This is
           useful when processing a capture created by combining outputs of multiple capture
           devices on the same channel in the vicinity of each other.

       -S  <strict time adjustment>

           Time adjust selected packets to ensure 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 ensure 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 <strict time adjustment> 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|--version
           Print the full version information and exit.

       -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.

       --inject-secrets <secrets type>,<file>

           Inserts the contents of <file> into a Decryption Secrets Block (DSB) within the pcapng
           output file. This enables decryption without requiring additional configuration in
           protocol preferences.

           The file format is described by <secrets type> which can be one of:

           tls  TLS Key Log as described at https://developer.mozilla.org/NSS_Key_Log_Format
           wg   WireGuard Key Log, see
           https://gitlab.com/wireshark/wireshark/-/wikis/WireGuard#key-log-format

           This option may be specified multiple times. The available options for <secrets type>
           can be listed with --inject-secrets help.

       --discard-all-secrets

           Discard all decryption secrets from the input file when writing the output file. Does
           not discard secrets added by --inject-secrets in the same command line.

       --capture-comment <comment>

           Adds the given comment to the output file, if supported by the output file format. New
           comments will be added after any comments present in the input file unless
           --discard-capture-comment is also specified.

           This option may be specified multiple times. Note that Wireshark currently only
           displays the first comment of a capture file.

       --discard-capture-comment

           Discard all capture file comments from the input file when writing the output file.
           Does not discard comments added by --capture-comment in the same command line.

       --set-unused

           Set the unused bytes (if any) to zero in SLL link type. Useful when when checking for
           duplicates. As the unused bytes can be anything. When the packet traverses the device
           stack for bonded interfaces on Linux for example.

       --discard-packet-comments

           Discard all packet comments from the input file when writing the output file. Does not
           discard comments added by -a in the same command line.

DIAGNOSTIC OPTIONS

       --log-level <level>
           Set the active log level. Supported levels in lowest to highest order are "noisy",
           "debug", "info", "message", "warning", "critical", and "error". Messages at each level
           and higher will be printed, for example "warning" prints "warning", "critical", and
           "error" messages and "noisy" prints all messages. Levels are case insensitive.

       --log-fatal <level>
           Abort the program if any messages are logged at the specified level or higher. For
           example, "warning" aborts on any "warning", "critical", or "error" messages.

       --log-domains <list>
           Only print messages for the specified log domains, e.g. "GUI,Epan,sshdump". List of
           domains must be comma-separated. Can be negated with "!" as the first character
           (inverts the match).

       --log-debug <list>
           Force the specified domains to log at the "debug" level. List of domains must be
           comma-separated. Can be negated with "!" as the first character (inverts the match).

       --log-noisy <list>
           Force the specified domains to log at the "noisy" level. List of domains must be
           comma-separated. Can be negated with "!" as the first character (inverts the match).

       --log-fatal-domains <list>
           Abort the program if any messages are logged for the specified log domains. List of
           domains must be comma-separated.

       --log-file <path>
           Write log messages and stderr output to the specified file.

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.pcapng shortcapture.snoop

       To delete packet 1000 from the capture file use:

           editcap capture.pcapng sans1000.pcapng 1000

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

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

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

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

       or

           editcap capture.pcapng first500.pcapng 501-9999999

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

           editcap capture.pcapng exclude.pcapng 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.pcapng select.pcapng 1 5 10-20 30-40

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

           editcap -d capture.pcapng dedup.pcapng

       To remove duplicate packets seen within the prior four frames while skipping radiotap
       headers use:

           editcap -d --skip-radiotap-header capture.pcapng dedup.pcapng

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

           editcap -D 101 capture.pcapng dedup.pcapng

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

           editcap -w 0.1 capture.pcapng dedup.pcapng

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

           editcap -V -D 0 capture.pcapng /dev/null

       or on Windows systems

           editcap -V -D 0 capture.pcapng NUL

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

           editcap -t 3.0827 capture.pcapng adjusted.pcapng

       To ensure all timestamps are in strict chronological order:

           editcap -S 0 capture.pcapng adjusted.pcapng

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

           editcap -E 0.05 capture.pcapng capture_error.pcapng

       To remove vlan tags from all packets within an Ethernet-encapsulated capture file, use:

           editcap -L -C 12:4 capture_vlan.pcapng capture_no_vlan.pcapng

       To chop both the 10 byte and 20 byte regions from the following 75 byte packet in a single
       pass, use any of the 8 possible methods provided below:

           <--------------------------- 75 ---------------------------->

           +---+-------+-----------+---------------+-------------------+
           | 5 |   10  |     15    |       20      |         25        |
           +---+-------+-----------+---------------+-------------------+

           1) editcap -C 5:10 -C -25:-20 capture.pcapng chopped.pcapng
           2) editcap -C 5:10 -C 50:-20 capture.pcapng chopped.pcapng
           3) editcap -C -70:10 -C -25:-20 capture.pcapng chopped.pcapng
           4) editcap -C -70:10 -C 50:-20 capture.pcapng chopped.pcapng
           5) editcap -C 30:20 -C -60:-10 capture.pcapng chopped.pcapng
           6) editcap -C 30:20 -C 15:-10 capture.pcapng chopped.pcapng
           7) editcap -C -45:20 -C -60:-10 capture.pcapng chopped.pcapng
           8) editcap -C -45:20 -C 15:-10 capture.pcapng chopped.pcapng

       To add comment strings to the first 2 input frames, use:

           editcap -a "1:1st frame" -a 2:Second capture.pcapng capture-comments.pcapng

SEE ALSO

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

NOTES

       This is the manual page for Editcap 4.2.6. Editcap is part of the Wireshark distribution.
       The latest version of Wireshark can be found at https://www.wireshark.org.

       HTML versions of the Wireshark project man pages are available at
       https://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>

                                            2024-07-11                                 EDITCAP(1)