EDITCAP(1) The Wireshark Network Analyzer EDITCAP(1)NAMEeditcap - Edit and/or translate the format of capture files
SYNOPSYSeditcap [ -c <packets per file> ] [ -C <choplen> ] [ -d ]
[ -E <error probability> ] [ -F <file format> ] [ -A <start time> ]
[ -B <stop time> ] [ -h ] [ -r ] [ -s <snaplen> ] [ -t <time adjust‐
ment> ] [ -T <encapsulation type> ] [ -v ] infile outfile
[ packet#[-packet#] ... ]
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 libpcap file format.
A list of packet numbers can be specified on the command line; ranges
of packet numbers can be specified as start-end, referring to all pack‐
ets from start to end. 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 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.wire‐
shark.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, edit‐
cap -F provides a list of the available output formats.
OPTIONS-c <packets per file>
Sets the maximum number of packets per output file. Each output
file will be created with a suffix -nnnnn, starting with 00000. If
the specified number of packets are 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 at the packet end by a few <choplen> bytes of
data.
This is useful 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 sum of
the current packet are compared to the previous four packets. If a
match is found, the packet is skipped.
-E <error probability>
Sets the probabilty that bytes in the output file are randomly
changed. Editcap uses that probability (between 0.0 and 1.0 inclu‐
sive) 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 hav‐
ing an error.
This option is meant to be used for fuzz-testing protocol dissec‐
tors.
-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 libpcap format.
-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 on or before stop time.
The time is given in the following format YYYY-MM-DD HH:MM:SS
-h Prints the version and options and exits.
-r Reverse the packet selection. Causes the packets whose packet num‐
bers 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).
-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 dif‐
ferent 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 encapsu‐
lation type of the output capture file will be forced to the speci‐
fied 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.
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 500.pcap 1-500
or
editcap capture.pcap 500.pcap 501-9999999
To filter out packets 10 to 20 and 30 to 40 into a new file use:
editcap capture.pcap selection.pcap 10-20 30-40
To introduce 5% random errors in a capture file use:
editcap-E 0.05 capture.pcap capture_error.pcap
SEE ALSOtcpdump(8), pcap(3), wireshark(1), tshark(1), mergecap(1), dumpcap(1),
capinfos(1), text2pcap(1), od(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>.
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>
1.0.3 2008-09-03 EDITCAP(1)
