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
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
<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
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The Wireshark Network Analyzer EDITCAP(1)
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.
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The Wireshark Network Analyzer EDITCAP(1)
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
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The Wireshark Network Analyzer EDITCAP(1)
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.
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The Wireshark Network Analyzer EDITCAP(1)
-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
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The Wireshark Network Analyzer EDITCAP(1)
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:
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The Wireshark Network Analyzer EDITCAP(1)
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
ATTRIBUTES
See attributes(5) for descriptions of the following
attributes:
+---------------+---------------------------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+---------------------------------------+
|Availability | diagnostic/wireshark/wireshark-common |
+---------------+---------------------------------------+
|Stability | Uncommitted |
+---------------+---------------------------------------+
SEE ALSO
pcap(3), wireshark(1), tshark(1), mergecap(1), dumpcap(1),
capinfos(1), text2pcap(1), od(1), pcap-filter(5) or
tcpdump(1)
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
<http://www.wireshark.org/docs/man-pages>.
AUTHORS
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The Wireshark Network Analyzer EDITCAP(1)
Original Author
-------- ------
Richard Sharpe <sharpe[AT]ns.aus.com>
Contributors
------------
Guy Harris <guy[AT]alum.mit.edu>
Ulf Lamping <ulf.lamping[AT]web.de>
This software was built from source available at
https://java.net/projects/solaris-userland. The original
community source was downloaded from
http://www.wireshark.org/download/src/all-
versions/wireshark-1.10.7.tar.bz2
Further information about this software can be found on the
open source community website at http://www.wireshark.org/.
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