4 editcap - Edit and/or translate the format of capture files
9 S<[ B<-c> E<lt>packets per fileE<gt> ]>
10 S<[ B<-C> E<lt>choplenE<gt> ]>
11 S<[ B<-E> E<lt>error probabilityE<gt> ]>
12 S<[ B<-F> E<lt>file formatE<gt> ]>
13 S<[ B<-W> E<lt>file format optionE<gt>]>
14 S<[ B<-H> E<lt>input hosts file<gt> ]>
15 S<[ B<-A> E<lt>start timeE<gt> ]>
16 S<[ B<-B> E<lt>stop timeE<gt> ]>
18 S<[ B<-i> E<lt>seconds per fileE<gt> ]>
20 S<[ B<-s> E<lt>snaplenE<gt> ]>
21 S<[ B<-t> E<lt>time adjustmentE<gt> ]>
22 S<[ B<-S> E<lt>strict time adjustmentE<gt> ]>
23 S<[ B<-T> E<lt>encapsulation typeE<gt> ]>
27 S<[ I<packet#>[-I<packet#>] ... ]>
31 S< B<-D> E<lt>dup windowE<gt> > |
32 S< B<-w> E<lt>dup time windowE<gt> >
39 B<Editcap> is a program that reads some or all of the captured packets from the
40 I<infile>, optionally converts them in various ways and writes the
41 resulting packets to the capture I<outfile> (or outfiles).
43 By default, it reads all packets from the I<infile> and writes them to the
44 I<outfile> in libpcap file format.
46 An optional list of packet numbers can be specified on the command tail;
47 individual packet numbers separated by whitespace and/or ranges of packet
48 numbers can be specified as I<start>-I<end>, referring to all packets from
49 I<start> to I<end>. By default the selected packets with those numbers will
50 I<not> be written to the capture file. If the B<-r> flag is specified, the
51 whole packet selection is reversed; in that case I<only> the selected packets
52 will be written to the capture file.
54 B<Editcap> can also be used to remove duplicate packets. Several different
55 options (B<-d>, B<-D> and B<-w>) are used to control the packet window
56 or relative time window to be used for duplicate comparison.
58 B<Editcap> is able to detect, read and write the same capture files that
59 are supported by B<Wireshark>.
60 The input file doesn't need a specific filename extension; the file
61 format and an optional gzip compression will be automatically detected.
62 Near the beginning of the DESCRIPTION section of wireshark(1) or
63 L<http://www.wireshark.org/docs/man-pages/wireshark.html>
64 is a detailed description of the way B<Wireshark> handles this, which is
65 the same way B<Editcap> handles this.
67 B<Editcap> can write the file in several output formats. The B<-F>
68 flag can be used to specify the format in which to write the capture
69 file; B<editcap -F> provides a list of the available output formats.
75 =item -c E<lt>packets per fileE<gt>
77 Splits the packet output to different files based on uniform packet counts
78 with a maximum of <packets per file> each. Each output file will
79 be created with a suffix -nnnnn, starting with 00000. If the specified
80 number of packets is written to the output file, the next output file is
81 opened. The default is to use a single output file.
83 =item -C E<lt>choplenE<gt>
85 Sets the chop length to use when writing the packet data. Each packet is
86 chopped by a few <choplen> bytes of data. Positive values chop at the packet
87 beginning while negative values chop at the packet end.
89 This is useful for chopping headers for decapsulation of an entire capture or
90 in the rare case that the conversion between two file formats leaves some random
91 bytes at the end of each packet.
95 Attempts to remove duplicate packets. The length and MD5 hash of the
96 current packet are compared to the previous four (4) packets. If a
97 match is found, the current packet is skipped. This option is equivalent
98 to using the option B<-D 5>.
100 =item -D E<lt>dup windowE<gt>
102 Attempts to remove duplicate packets. The length and MD5 hash of the
103 current packet are compared to the previous <dup window> - 1 packets.
104 If a match is found, the current packet is skipped.
106 The use of the option B<-D 0> combined with the B<-v> option is useful
107 in that each packet's Packet number, Len and MD5 Hash will be printed
108 to standard out. This verbose output (specifically the MD5 hash strings)
109 can be useful in scripts to identify duplicate packets across trace
112 The <dup window> is specified as an integer value between 0 and 1000000 (inclusive).
114 NOTE: Specifying large <dup window> values with large tracefiles can
115 result in very long processing times for B<editcap>.
117 =item -w E<lt>dup time windowE<gt>
119 Attempts to remove duplicate packets. The current packet's arrival time
120 is compared with up to 1000000 previous packets. If the packet's relative
121 arrival time is I<less than or equal to> the <dup time window> of a previous packet
122 and the packet length and MD5 hash of the current packet are the same then
123 the packet to skipped. The duplicate comparison test stops when
124 the current packet's relative arrival time is greater than <dup time window>.
126 The <dup time window> is specified as I<seconds>[I<.fractional seconds>].
128 The [.fractional seconds] component can be specified to nine (9) decimal
129 places (billionths of a second) but most typical trace files have resolution
130 to six (6) decimal places (millionths of a second).
132 NOTE: Specifying large <dup time window> values with large tracefiles can
133 result in very long processing times for B<editcap>.
135 NOTE: The B<-w> option assumes that the packets are in chronological order.
136 If the packets are NOT in chronological order then the B<-w> duplication
137 removal option may not identify some duplicates.
139 =item -E E<lt>error probabilityE<gt>
141 Sets the probability that bytes in the output file are randomly changed.
142 B<Editcap> uses that probability (between 0.0 and 1.0 inclusive)
143 to apply errors to each data byte in the file. For instance, a
144 probability of 0.02 means that each byte has a 2% chance of having an error.
146 This option is meant to be used for fuzz-testing protocol dissectors.
148 =item -F E<lt>file formatE<gt>
150 Sets the file format of the output capture file.
151 B<Editcap> can write the file in several formats, B<editcap -F>
152 provides a list of the available output formats. The default
153 is the B<libpcap> format.
155 =item -W E<lt>file format optionE<gt>
157 Save extra information in the file if the format supports it. For
162 will save host name resolution records along with captured packets.
164 Future versions of Wireshark may automatically change the capture format to
167 The argument is a string that may contain the following letter:
169 B<n> write network address resolution information (pcapng only)
171 =item -H E<lt>input "hosts" fileE<gt>
173 Read a list of address to host name mappings and include the result in
174 the output file. Implies B<-W n>.
176 The input file format is described at
177 L<http://en.wikipedia.org/wiki/Hosts_%28file%29>.
179 =item -A E<lt>start timeE<gt>
181 Saves only the packets whose timestamp is on or after start time.
182 The time is given in the following format YYYY-MM-DD HH:MM:SS
184 =item -B E<lt>stop timeE<gt>
186 Saves only the packets whose timestamp is before stop time.
187 The time is given in the following format YYYY-MM-DD HH:MM:SS
191 Prints the version and options and exits.
193 =item -i E<lt>seconds per fileE<gt>
195 Splits the packet output to different files based on uniform time intervals
196 using a maximum interval of <seconds per file> each. Each output file will
197 be created with a suffix -nnnnn, starting with 00000. If packets for the specified
198 time interval are written to the output file, the next output file is
199 opened. The default is to use a single output file.
203 Reverse the packet selection.
204 Causes the packets whose packet numbers are specified on the command
205 line to be written to the output capture file, instead of discarding them.
207 =item -s E<lt>snaplenE<gt>
209 Sets the snapshot length to use when writing the data.
210 If the B<-s> flag is used to specify a snapshot length, packets in the
211 input file with more captured data than the specified snapshot length
212 will have only the amount of data specified by the snapshot length
213 written to the output file.
215 This may be useful if the program that is
216 to read the output file cannot handle packets larger than a certain size
217 (for example, the versions of snoop in Solaris 2.5.1 and Solaris 2.6
218 appear to reject Ethernet packets larger than the standard Ethernet MTU,
219 making them incapable of handling gigabit Ethernet captures if jumbo
222 =item -t E<lt>time adjustmentE<gt>
224 Sets the time adjustment to use on selected packets.
225 If the B<-t> flag is used to specify a time adjustment, the specified
226 adjustment will be applied to all selected packets in the capture file.
227 The adjustment is specified as [-]I<seconds>[I<.fractional seconds>].
228 For example, B<-t> 3600 advances the timestamp on selected packets by one
229 hour while B<-t> -0.5 reduces the timestamp on selected packets by
232 This feature is useful when synchronizing dumps
233 collected on different machines where the time difference between the
234 two machines is known or can be estimated.
236 =item -S E<lt>strict time adjustmentE<gt>
238 Time adjust selected packets to insure strict chronological order.
240 The <strict time adjustment> value represents relative seconds
241 specified as [-]I<seconds>[I<.fractional seconds>].
243 As the capture file is processed each packet's absolute time is
244 I<possibly> adjusted to be equal to or greater than the previous
245 packet's absolute timestamp depending on the <strict time
248 If <strict time adjustment> value is 0 or greater (e.g. 0.000001)
249 then B<only> packets with a timestamp less than the previous packet
250 will adjusted. The adjusted timestamp value will be set to be
251 equal to the timestamp value of the previous packet plus the value
252 of the <strict time adjustment> value. A <strict time adjustment>
253 value of 0 will adjust the minimum number of timestamp values
254 necessary to insure that the resulting capture file is in
255 strict chronological order.
257 If <strict time adjustment> value is specified as a
258 negative value, then the timestamp values of B<all>
259 packets will be adjusted to be equal to the timestamp value
260 of the previous packet plus the absolute value of the
261 <lt>strict time adjustment<gt> value. A <strict time
262 adjustment> value of -0 will result in all packets
263 having the timestamp value of the first packet.
265 This feature is useful when the trace file has an occasional
266 packet with a negative delta time relative to the previous
269 =item -T E<lt>encapsulation typeE<gt>
271 Sets the packet encapsulation type of the output capture file.
272 If the B<-T> flag is used to specify an encapsulation type, the
273 encapsulation type of the output capture file will be forced to the
275 B<editcap -T> provides a list of the available types. The default
276 type is the one appropriate to the encapsulation type of the input
280 forces the encapsulation type of the output file to be the specified
281 type; the packet headers of the packets will not be translated from the
282 encapsulation type of the input capture file to the specified
283 encapsulation type (for example, it will not translate an Ethernet
284 capture to an FDDI capture if an Ethernet capture is read and 'B<-T
285 fddi>' is specified). If you need to remove/add headers from/to a
286 packet, you will need od(1)/text2pcap(1).
290 Causes B<editcap> to print verbose messages while it's working.
292 Use of B<-v> with the de-duplication switches of B<-d>, B<-D> or B<-w>
293 will cause all MD5 hashes to be printed whether the packet is skipped
300 To see more detailed description of the options use:
304 To shrink the capture file by truncating the packets at 64 bytes and writing it as Sun snoop file use:
306 editcap -s 64 -F snoop capture.pcap shortcapture.snoop
308 To delete packet 1000 from the capture file use:
310 editcap capture.pcap sans1000.pcap 1000
312 To limit a capture file to packets from number 200 to 750 (inclusive) use:
314 editcap -r capture.pcap small.pcap 200-750
316 To get all packets from number 1-500 (inclusive) use:
318 editcap -r capture.pcap first500.pcap 1-500
322 editcap capture.pcap first500.pcap 501-9999999
324 To exclude packets 1, 5, 10 to 20 and 30 to 40 from the new file use:
326 editcap capture.pcap exclude.pcap 1 5 10-20 30-40
328 To select just packets 1, 5, 10 to 20 and 30 to 40 for the new file use:
330 editcap -r capture.pcap select.pcap 1 5 10-20 30-40
332 To remove duplicate packets seen within the prior four frames use:
334 editcap -d capture.pcap dedup.pcap
336 To remove duplicate packets seen within the prior 100 frames use:
338 editcap -D 101 capture.pcap dedup.pcap
340 To remove duplicate packets seen I<equal to or less than> 1/10th of a second:
342 editcap -w 0.1 capture.pcap dedup.pcap
344 To display the MD5 hash for all of the packets (and NOT generate any
347 editcap -v -D 0 capture.pcap /dev/null
349 or on Windows systems
351 editcap -v -D 0 capture.pcap NUL
353 To advance the timestamps of each packet forward by 3.0827 seconds:
355 editcap -t 3.0827 capture.pcap adjusted.pcap
357 To insure all timestamps are in strict chronological order:
359 editcap -S 0 capture.pcap adjusted.pcap
361 To introduce 5% random errors in a capture file use:
365 editcap -E 0.05 capture.pcap capture_error.pcap
371 tcpdump(8), pcap(3), wireshark(1), tshark(1), mergecap(1), dumpcap(1),
372 capinfos(1), text2pcap(1), od(1)
376 B<Editcap> is part of the B<Wireshark> distribution. The latest version
377 of B<Wireshark> can be found at L<http://www.wireshark.org>.
379 HTML versions of the Wireshark project man pages are available at:
380 L<http://www.wireshark.org/docs/man-pages>.
386 Richard Sharpe <sharpe[AT]ns.aus.com>
391 Guy Harris <guy[AT]alum.mit.edu>
392 Ulf Lamping <ulf.lamping[AT]web.de>