1EDITCAP(1) The Wireshark Network Analyzer EDITCAP(1)
2
6 editcap - Edit and/or translate the format of capture files
7
9 editcap [ -c <packets per file> ] [ -C <choplen> ]
10 [ -E <error probability> ] [ -F <file format> ] [ -A <start time> ]
11 [ -B <stop time> ] [ -h ] [ -i <seconds per file> ] [ -r ]
12 [ -s <snaplen> ] [ -t <time adjustment> ]
13 [ -S <strict time adjustment> ] [ -T <encapsulation type> ] [ -v ]
14 infile outfile [ packet#[-packet#] ... ]
15 editcap -d | -D <dup window> | -w <dup time window> [ -v ] infile
17 outfile
18
20 Editcap is a program that reads some or all of the captured packets
21 from the infile, optionally converts them in various ways and writes
22 the resulting packets to the capture outfile (or outfiles).
23 By default, it reads all packets from the infile and writes them to the
25 outfile in libpcap file format.
26 An optional list of packet numbers can be specified on the command
28 tail; individual packet numbers separated by whitespace and/or ranges
29 of packet numbers can be specified as start-end, referring to all
30 packets from start to end. By default the selected packets with those
31 numbers will not be written to the capture file. If the -r flag is
32 specified, the whole packet selection is reversed; in that case only
33 the selected packets will be written to the capture file.
34 Editcap can also be used to remove duplicate packets. Several
36 different options (-d, -D and -w) are used to control the packet window
37 or relative time window to be used for duplicate comparison.
38 Editcap is able to detect, read and write the same capture files that
40 are supported by Wireshark. The input file doesn't need a specific
41 filename extension; the file format and an optional gzip compression
42 will be automatically detected. Near the beginning of the DESCRIPTION
43 section of wireshark(1) or
44 http://www.wireshark.org/docs/man-pages/wireshark.html
45 <http://www.wireshark.org/docs/man-pages/wireshark.html> is a detailed
46 description of the way Wireshark handles this, which is the same way
47 Editcap handles this.
48 Editcap can write the file in several output formats. The -F flag can
50 be used to specify the format in which to write the capture file;
51 editcap -F provides a list of the available output formats.
52
54 -c <packets per file>
55 Splits the packet output to different files based on uniform packet
56 counts with a maximum of <packets per file> each. Each output file
57 will be created with a suffix -nnnnn, starting with 00000. If the
58 specified number of packets is written to the output file, the next
59 output file is opened. The default is to use a single output file.
60 -C <choplen>
62 Sets the chop length to use when writing the packet data. Each
63 packet is chopped at the packet end by a few <choplen> bytes of
64 data.
65 This is useful in the rare case that the conversion between two
67 file formats leaves some random bytes at the end of each packet.
68 -d Attempts to remove duplicate packets. The length and MD5 hash of
70 the current packet are compared to the previous four (4) packets.
71 If a match is found, the current packet is skipped. This option is
72 equivalent to using the option -D 5.
73 -D <dup window>
75 Attempts to remove duplicate packets. The length and MD5 hash of
76 the current packet are compared to the previous <dup window> - 1
77 packets. If a match is found, the current packet is skipped.
78 The use of the option -D 0 combined with the -v option is useful in
80 that each packet's Packet number, Len and MD5 Hash will be printed
81 to standard out. This verbose output (specifically the MD5 hash
82 strings) can be useful in scripts to identify duplicate packets
83 across trace files.
84 The <dup window> is specifed as an integer value between 0 and
86 1000000 (inclusive).
87 NOTE: Specifying large <dup window> values with large tracefiles
89 can result in very long processing times for editcap.
90 -w <dup time window>
92 Attempts to remove duplicate packets. The current packet's arrival
93 time is compared with up to 1000000 previous packets. If the
94 packet's relative arrival time is less than or equal to the <dup
95 time window> of a previous packet and the packet length and MD5
96 hash of the current packet are the same then the packet to skipped.
97 The duplicate comparison test stops when the current packet's
98 relative arrival time is greater than <dup time window>.
99 The <dup time window> is specifed as seconds[.fractional seconds].
101 The [.fractional seconds] component can be specified to nine (9)
103 decimal places (billionths of a second) but most typical trace
104 files have resolution to six (6) decimal places (millionths of a
105 second).
106 NOTE: Specifying large <dup time window> values with large
108 tracefiles can result in very long processing times for editcap.
109 NOTE: The -w option assumes that the packets are in chronological
111 order. If the packets are NOT in chronological order then the -w
112 duplication removal option may not identify some duplicates.
113 -E <error probability>
115 Sets the probabilty that bytes in the output file are randomly
116 changed. Editcap uses that probability (between 0.0 and 1.0
117 inclusive) to apply errors to each data byte in the file. For
118 instance, a probability of 0.02 means that each byte has a 2%
119 chance of having an error.
120 This option is meant to be used for fuzz-testing protocol
122 dissectors.
123 -F <file format>
125 Sets the file format of the output capture file. Editcap can write
126 the file in several formats, editcap -F provides a list of the
127 available output formats. The default is the libpcap format.
128 -A <start time>
130 Saves only the packets whose timestamp is on or after start time.
131 The time is given in the following format YYYY-MM-DD HH:MM:SS
132 -B <stop time>
134 Saves only the packets whose timestamp is on or before stop time.
135 The time is given in the following format YYYY-MM-DD HH:MM:SS
136 -h Prints the version and options and exits.
138 -i <seconds per file>
140 Splits the packet output to different files based on uniform time
141 intervals using a maximum interval of <seconds per file> each. Each
142 output file will be created with a suffix -nnnnn, starting with
143 00000. If packets for the specified time interval are written to
144 the output file, the next output file is opened. The default is to
145 use a single output file.
146 -r Reverse the packet selection. Causes the packets whose packet
148 numbers are specified on the command line to be written to the
149 output capture file, instead of discarding them.
150 -s <snaplen>
152 Sets the snapshot length to use when writing the data. If the -s
153 flag is used to specify a snapshot length, packets in the input
154 file with more captured data than the specified snapshot length
155 will have only the amount of data specified by the snapshot length
156 written to the output file.
157 This may be useful if the program that is to read the output file
159 cannot handle packets larger than a certain size (for example, the
160 versions of snoop in Solaris 2.5.1 and Solaris 2.6 appear to reject
161 Ethernet packets larger than the standard Ethernet MTU, making them
162 incapable of handling gigabit Ethernet captures if jumbo packets
163 were used).
164 -t <time adjustment>
166 Sets the time adjustment to use on selected packets. If the -t
167 flag is used to specify a time adjustment, the specified adjustment
168 will be applied to all selected packets in the capture file. The
169 adjustment is specified as [-]seconds[.fractional seconds]. For
170 example, -t 3600 advances the timestamp on selected packets by one
171 hour while -t -0.5 reduces the timestamp on selected packets by
172 one-half second.
173 This feature is useful when synchronizing dumps collected on
175 different machines where the time difference between the two
176 machines is known or can be estimated.
177 -S <strict time adjustment>
179 Time adjust selected packets to insure strict chronological order.
180 The <strict time adjustment> value represents relative seconds
182 specified as [-]seconds[.fractional seconds].
183 As the capture file is processed each packet's absolute time is
185 possibly adjusted to be equal to or greater than the previous
186 packet's absolute timestamp depending on the <strict time
187 adjustment> value.
188 If <strict time adjustment> value is 0 or greater (e.g. 0.000001)
190 then only packets with a timestamp less than the previous packet
191 will adjusted. The adjusted timestamp value will be set to be
192 equal to the timestamp value of the previous packet plus the value
193 of the <strict time adjustment> value. A <strict time adjustment>
194 value of 0 will adjust the minimum number of timestamp values
195 necessary to insure that the resulting capture file is in strict
196 chronological order.
197 If <strict time adjustment> value is specified as a negative value,
199 then the timestamp values of all packets will be adjusted to be
200 equal to the timestamp value of the previous packet plus the
201 absolute value of the <lt>strict time adjustment<gt> value. A
202 <strict time adjustment> value of -0 will result in all packets
203 having the timestamp value of the first packet.
204 This feature is useful when the trace file has an occasional packet
206 with a negative delta time relative to the previous packet.
207 -T <encapsulation type>
209 Sets the packet encapsulation type of the output capture file. If
210 the -T flag is used to specify an encapsulation type, the
211 encapsulation type of the output capture file will be forced to the
212 specified type. editcap -T provides a list of the available types.
213 The default type is the one appropriate to the encapsulation type
214 of the input capture file.
215 Note: this merely forces the encapsulation type of the output file
217 to be the specified type; the packet headers of the packets will
218 not be translated from the encapsulation type of the input capture
219 file to the specified encapsulation type (for example, it will not
220 translate an Ethernet capture to an FDDI capture if an Ethernet
221 capture is read and '-T fddi' is specified). If you need to
222 remove/add headers from/to a packet, you will need
223 od(1)/text2pcap(1).
224 -v Causes editcap to print verbose messages while it's working.
226 Use of -v with the de-duplication switches of -d, -D or -w will
228 cause all MD5 hashes to be printed whether the packet is skipped or
229 not.
230
232 To see more detailed description of the options use:
233 editcap -h
235 To shrink the capture file by truncating the packets at 64 bytes and
237 writing it as Sun snoop file use:
238 editcap -s 64 -F snoop capture.pcap shortcapture.snoop
240 To delete packet 1000 from the capture file use:
242 editcap capture.pcap sans1000.pcap 1000
244 To limit a capture file to packets from number 200 to 750 (inclusive)
246 use:
247 editcap -r capture.pcap small.pcap 200-750
249 To get all packets from number 1-500 (inclusive) use:
251 editcap -r capture.pcap first500.pcap 1-500
253 or
255 editcap capture.pcap first500.pcap 501-9999999
257 To exclude packets 1, 5, 10 to 20 and 30 to 40 from the new file use:
259 editcap capture.pcap exclude.pcap 1 5 10-20 30-40
261 To select just packets 1, 5, 10 to 20 and 30 to 40 for the new file
263 use:
264 editcap -r capture.pcap select.pcap 1 5 10-20 30-40
266 To remove duplicate packets seen within the prior four frames use:
268 editcap -d capture.pcap dedup.pcap
270 To remove duplicate packets seen within the prior 100 frames use:
272 editcap -D 101 capture.pcap dedup.pcap
274 To remove duplicate packets seen equal to or less than 1/10th of a
276 second:
277 editcap -w 0.1 capture.pcap dedup.pcap
279 To display the MD5 hash for all of the packets (and NOT generate any
281 real output file):
282 editcap -v -D 0 capture.pcap /dev/null
284 or on Windows systems
286 editcap -v -D 0 capture.pcap NUL
288 To advance the timestamps of each packet forward by 3.0827 seconds:
290 editcap -t 3.0827 capture.pcap adjusted.pcap
292 To insure all timestamps are in strict chronological order:
294 editcap -S 0 capture.pcap adjusted.pcap
296 To introduce 5% random errors in a capture file use:
298 editcap -E 0.05 capture.pcap capture_error.pcap
300
302 tcpdump(8), pcap(3), wireshark(1), tshark(1), mergecap(1), dumpcap(1),
303 capinfos(1), text2pcap(1), od(1)
304
306 Editcap is part of the Wireshark distribution. The latest version of
307 Wireshark can be found at <http://www.wireshark.org>.
308 HTML versions of the Wireshark project man pages are available at:
310 http://www.wireshark.org/docs/man-pages
311 <http://www.wireshark.org/docs/man-pages>.
312
314 Original Author
315 -------- ------
316 Richard Sharpe <sharpe[AT]ns.aus.com>
317 Contributors
320 ------------
321 Guy Harris <guy[AT]alum.mit.edu>
322 Ulf Lamping <ulf.lamping[AT]web.de>
3231.4.10 2011-11-01 EDITCAP(1)