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<-A> E<lt>start timeE<gt> ]>
14 S<[ B<-B> E<lt>stop timeE<gt> ]>
16 S<[ B<-i> E<lt>seconds per fileE<gt> ]>
18 S<[ B<-s> E<lt>snaplenE<gt> ]>
19 S<[ B<-t> E<lt>time adjustmentE<gt> ]>
20 S<[ B<-T> E<lt>encapsulation typeE<gt> ]>
24 S<[ I<packet#>[-I<packet#>] ... ]>
28 S< B<-D> E<lt>dup windowE<gt> > |
29 S< B<-w> E<lt>dup time windowE<gt> >
36 B<Editcap> is a program that reads some or all of the captured packets from the
37 I<infile>, optionally converts them in various ways and writes the
38 resulting packets to the capture I<outfile> (or outfiles).
40 By default, it reads all packets from the I<infile> and writes them to the
41 I<outfile> in libpcap file format.
43 An optional list of packet numbers can be specified on the command tail;
44 individual packet numbers separated by whitespace and/or ranges of packet
45 numbers can be specified as I<start>-I<end>, referring to all packets from
46 I<start> to I<end>. By default the selected packets with those numbers will
47 I<not> be written to the capture file. If the B<-r> flag is specified, the
48 whole packet selection is reversed; in that case I<only> the selected packets
49 will be written to the capture file.
51 B<Editcap> can also be used to remove duplicate packets. Several different
52 options (B<-d>, B<-D> and B<-w>) are used to control the packet window
53 or relative time window to be used for duplicate comparison.
55 B<Editcap> is able to detect, read and write the same capture files that
56 are supported by B<Wireshark>.
57 The input file doesn't need a specific filename extension; the file
58 format and an optional gzip compression will be automatically detected.
59 Near the beginning of the DESCRIPTION section of wireshark(1) or
60 L<http://www.wireshark.org/docs/man-pages/wireshark.html>
61 is a detailed description of the way B<Wireshark> handles this, which is
62 the same way B<Editcap> handles this.
64 B<Editcap> can write the file in several output formats. The B<-F>
65 flag can be used to specify the format in which to write the capture
66 file; B<editcap -F> provides a list of the available output formats.
72 =item -c E<lt>packets per fileE<gt>
74 Splits the packet output to different files based on uniform packet counts
75 with a maximum of <packets per file> each. Each output file will
76 be created with a suffix -nnnnn, starting with 00000. If the specified
77 number of packets is written to the output file, the next output file is
78 opened. The default is to use a single output file.
80 =item -C E<lt>choplenE<gt>
82 Sets the chop length to use when writing the packet data.
83 Each packet is chopped at the packet end by a few <choplen> bytes of data.
85 This is useful in the rare case that the conversion between two file
86 formats leaves some random bytes at the end of each packet.
90 Attempts to remove duplicate packets. The length and MD5 hash of the
91 current packet are compared to the previous four (4) packets. If a
92 match is found, the current packet is skipped. This option is equivalent
93 to using the option B<-D 5>.
95 =item -D E<lt>dup windowE<gt>
97 Attempts to remove duplicate packets. The length and MD5 hash of the
98 current packet are compared to the previous <dup window> - 1 packets.
99 If a match is found, the current packet is skipped.
101 The use of the option B<-D 0> combined with the B<-v> option is useful
102 in that each packet's Packet number, Len and MD5 Hash will be printed
103 to standard out. This verbose output (specifically the MD5 hash strings)
104 can be useful in scripts to identify duplicate packets across trace
107 The <dup window> is specifed as an integer value between 0 and 1000000 (inclusive).
109 NOTE: Specifying large <dup window> values with large tracefiles can
110 result in very long processing times for B<editcap>.
112 =item -w E<lt>dup time windowE<gt>
114 Attempts to remove duplicate packets. The current packet's arrival time
115 is compared with up to 1000000 previous packets. If the packet's relative
116 arrival time is I<less than or equal to> the <dup time window> of a previous packet
117 and the packet length and MD5 hash of the current packet are the same then
118 the packet to skipped. The duplicate comparison test stops when
119 the current packet's relative arrival time is greater than <dup time window>.
121 The <dup time window> is specifed as I<seconds>[I<.fractional seconds>].
123 The [.fractional seconds] component can be specified to nine (9) decimal
124 places (billionths of a second) but most typical trace files have resolution
125 to six (6) decimal places (millionths of a second).
127 NOTE: Specifying large <dup time window> values with large tracefiles can
128 result in very long processing times for B<editcap>.
130 NOTE: The B<-w> option assumes that the packets are in chronological order.
131 If the packets are NOT in chronological order then the B<-w> duplication
132 removal option may not identify some duplicates.
134 =item -E E<lt>error probabilityE<gt>
136 Sets the probabilty that bytes in the output file are randomly changed.
137 B<Editcap> uses that probability (between 0.0 and 1.0 inclusive)
138 to apply errors to each data byte in the file. For instance, a
139 probability of 0.02 means that each byte has a 2% chance of having an error.
141 This option is meant to be used for fuzz-testing protocol dissectors.
143 =item -F E<lt>file formatE<gt>
145 Sets the file format of the output capture file.
146 B<Editcap> can write the file in several formats, B<editcap -F>
147 provides a list of the available output formats. The default
148 is the B<libpcap> format.
150 =item -A E<lt>start timeE<gt>
152 Saves only the packets whose timestamp is on or after start time.
153 The time is given in the following format YYYY-MM-DD HH:MM:SS
155 =item -B E<lt>stop timeE<gt>
157 Saves only the packets whose timestamp is on or before stop time.
158 The time is given in the following format YYYY-MM-DD HH:MM:SS
162 Prints the version and options and exits.
164 =item -i E<lt>seconds per fileE<gt>
166 Splits the packet output to different files based on uniform time intervals
167 using a maximum interval of <seconds per file> each. Each output file will
168 be created with a suffix -nnnnn, starting with 00000. If packets for the specified
169 time interval are written to the output file, the next output file is
170 opened. The default is to use a single output file.
174 Reverse the packet selection.
175 Causes the packets whose packet numbers are specified on the command
176 line to be written to the output capture file, instead of discarding them.
178 =item -s E<lt>snaplenE<gt>
180 Sets the snapshot length to use when writing the data.
181 If the B<-s> flag is used to specify a snapshot length, packets in the
182 input file with more captured data than the specified snapshot length
183 will have only the amount of data specified by the snapshot length
184 written to the output file.
186 This may be useful if the program that is
187 to read the output file cannot handle packets larger than a certain size
188 (for example, the versions of snoop in Solaris 2.5.1 and Solaris 2.6
189 appear to reject Ethernet packets larger than the standard Ethernet MTU,
190 making them incapable of handling gigabit Ethernet captures if jumbo
193 =item -t E<lt>time adjustmentE<gt>
195 Sets the time adjustment to use on selected packets.
196 If the B<-t> flag is used to specify a time adjustment, the specified
197 adjustment will be applied to all selected packets in the capture file.
198 The adjustment is specified as [-]I<seconds>[I<.fractional seconds>].
199 For example, B<-t> 3600 advances the timestamp on selected packets by one
200 hour while B<-t> -0.5 reduces the timestamp on selected packets by
203 This feature is useful when synchronizing dumps
204 collected on different machines where the time difference between the
205 two machines is known or can be estimated.
207 =item -T E<lt>encapsulation typeE<gt>
209 Sets the packet encapsulation type of the output capture file.
210 If the B<-T> flag is used to specify an encapsulation type, the
211 encapsulation type of the output capture file will be forced to the
213 B<editcap -T> provides a list of the available types. The default
214 type is the one appropriate to the encapsulation type of the input
218 forces the encapsulation type of the output file to be the specified
219 type; the packet headers of the packets will not be translated from the
220 encapsulation type of the input capture file to the specified
221 encapsulation type (for example, it will not translate an Ethernet
222 capture to an FDDI capture if an Ethernet capture is read and 'B<-T
223 fddi>' is specified). If you need to remove/add headers from/to a
224 packet, you will need od(1)/text2pcap(1).
228 Causes B<editcap> to print verbose messages while it's working.
230 Use of B<-v> with the de-duplication switches of B<-d>, B<-D> or B<-w>
231 will cause all MD5 hashes to be printed whether the packet is skipped
238 To see more detailed description of the options use:
242 To shrink the capture file by truncating the packets at 64 bytes and writing it as Sun snoop file use:
244 editcap -s 64 -F snoop capture.pcap shortcapture.snoop
246 To delete packet 1000 from the capture file use:
248 editcap capture.pcap sans1000.pcap 1000
250 To limit a capture file to packets from number 200 to 750 (inclusive) use:
252 editcap -r capture.pcap small.pcap 200-750
254 To get all packets from number 1-500 (inclusive) use:
256 editcap -r capture.pcap first500.pcap 1-500
260 editcap capture.pcap first500.pcap 501-9999999
262 To exclude packets 1, 5, 10 to 20 and 30 to 40 from the new file use:
264 editcap capture.pcap exclude.pcap 1 5 10-20 30-40
266 To select just packets 1, 5, 10 to 20 and 30 to 40 for the new file use:
268 editcap -r capture.pcap select.pcap 1 5 10-20 30-40
270 To remove duplicate packets seen within the prior four frames use:
272 editcap -d capture.pcap dedup.pcap
274 To remove duplicate packets seen within the prior 100 frames use:
276 editcap -D 101 capture.pcap dedup.pcap
278 To remove duplicate packets seen I<equal to or less than> 1/10th of a second:
280 editcap -w 0.1 capture.pcap dedup.pcap
282 To display the MD5 hash for all of the packets (and NOT generate any
285 editcap -v -D 0 capture.pcap /dev/null
287 or on Windows systems
289 editcap -v -D 0 capture.pcap NUL
291 To introduce 5% random errors in a capture file use:
295 editcap -E 0.05 capture.pcap capture_error.pcap
301 tcpdump(8), pcap(3), wireshark(1), tshark(1), mergecap(1), dumpcap(1),
302 capinfos(1), text2pcap(1), od(1)
306 B<Editcap> is part of the B<Wireshark> distribution. The latest version
307 of B<Wireshark> can be found at L<http://www.wireshark.org>.
309 HTML versions of the Wireshark project man pages are available at:
310 L<http://www.wireshark.org/docs/man-pages>.
316 Richard Sharpe <sharpe[AT]ns.aus.com>
321 Guy Harris <guy[AT]alum.mit.edu>
322 Ulf Lamping <ulf.lamping[AT]web.de>