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> ]>
17 S<[ B<-s> E<lt>snaplenE<gt> ]>
18 S<[ B<-t> E<lt>time adjustmentE<gt> ]>
19 S<[ B<-T> E<lt>encapsulation typeE<gt> ]>
23 S<[ I<packet#>[-I<packet#>] ... ]>
27 B<Editcap> is a program that reads some or all of the captured packets from the
28 I<infile>, optionally converts them in various ways and writes the
29 resulting packets to the capture I<outfile> (or outfiles).
31 By default, it reads all packets from the I<infile> and writes them to the
32 I<outfile> in libpcap file format.
34 A list of packet numbers can be specified on the command line; ranges of
35 packet numbers can be specified as I<start>-I<end>, referring to all packets
36 from I<start> to I<end>.
37 The selected packets with those numbers will I<not> be written to the
39 If the B<-r> flag is specified, the whole packet selection is reversed;
40 in that case I<only> the selected packets will be written to the capture file.
42 B<Editcap> is able to detect, read and write the same capture files that
43 are supported by B<Wireshark>.
44 The input file doesn't need a specific filename extension; the file
45 format and an optional gzip compression will be automatically detected.
46 Near the beginning of the DESCRIPTION section of wireshark(1) or
47 L<http://www.wireshark.org/docs/man-pages/wireshark.1.html>
48 is a detailed description of the way B<Wireshark> handles this, which is
49 the same way B<Editcap> handles this.
51 B<Editcap> can write the file in several output formats. The B<-F>
52 flag can be used to specify the format in which to write the capture
53 file, B<editcap -F> provides a list of the available output formats.
59 =item -c E<lt>packets per fileE<gt>
61 Sets the maximum number of packets per output file. Each output file will
62 be created with a suffix -nnnnn, starting with 00000. If the specified
63 number of packets are written to the output file, the next output file is
64 opened. The default is to use a single output file.
66 =item -C E<lt>choplenE<gt>
68 Sets the chop length to use when writing the packet data.
69 Each packet is chopped at the packet end by a few <choplen> bytes of data.
71 This is useful in the rare case that the conversion between two file
72 formats leaves some random bytes at the end of each packet.
74 =item -E E<lt>error probabilityE<gt>
76 Sets the probabilty that bytes in the output file are randomly changed.
77 B<Editcap> uses that probability (between 0.0 and 1.0 inclusive)
78 to apply errors to each data byte in the file. For instance, a
79 probability of 0.02 means that each byte has a 2% chance of having an error.
81 This option is meant to be used for fuzz-testing protocol dissectors.
83 =item -F E<lt>file formatE<gt>
85 Sets the file format of the output capture file.
86 B<Editcap> can write the file in several formats, B<editcap -F>
87 provides a list of the available output formats. The default
88 is the B<libpcap> format.
90 =item -A E<lt>start timeE<gt>
92 Saves only the packets whose timestamp is on or after start time.
93 The time is given in the following format YYYY-MM-DD HH:MM:SS
95 =item -B E<lt>stop timeE<gt>
97 Saves only the packets whose timestamp is on or before stop time.
98 The time is given in the following format YYYY-MM-DD HH:MM:SS
102 Prints the version and options and exits.
106 Reverse the packet selection.
107 Causes the packets whose packet numbers are specified on the command
108 line to be written to the output capture file, instead of discarding them.
110 =item -s E<lt>snaplenE<gt>
112 Sets the snapshot length to use when writing the data.
113 If the B<-s> flag is used to specify a snapshot length, packets in the
114 input file with more captured data than the specified snapshot length
115 will have only the amount of data specified by the snapshot length
116 written to the output file.
118 This may be useful if the program that is
119 to read the output file cannot handle packets larger than a certain size
120 (for example, the versions of snoop in Solaris 2.5.1 and Solaris 2.6
121 appear to reject Ethernet packets larger than the standard Ethernet MTU,
122 making them incapable of handling gigabit Ethernet captures if jumbo
125 =item -t E<lt>time adjustmentE<gt>
127 Sets the time adjustment to use on selected packets.
128 If the B<-t> flag is used to specify a time adjustment, the specified
129 adjustment will be applied to all selected packets in the capture file.
130 The adjustment is specified as [-]I<seconds>[I<.fractional seconds>].
131 For example, B<-t> 3600 advances the timestamp on selected packets by one
132 hour while B<-t> -0.5 reduces the timestamp on selected packets by
135 This feature is useful when synchronizing dumps
136 collected on different machines where the time difference between the
137 two machines is known or can be estimated.
139 =item -T E<lt>encapsulation typeE<gt>
141 Sets the packet encapsulation type of the output capture file.
142 If the B<-T> flag is used to specify an encapsulation type, the
143 encapsulation type of the output capture file will be forced to the
145 B<editcap -T> provides a list of the available types. The default
146 type is the one appropriate to the encapsulation type of the input
150 forces the encapsulation type of the output file to be the specified
151 type; the packet headers of the packets will not be translated from the
152 encapsulation type of the input capture file to the specified
153 encapsulation type (for example, it will not translate an Ethernet
154 capture to an FDDI capture if an Ethernet capture is read and 'B<-T
155 fddi>' is specified).
159 Causes B<editcap> to print verbose messages while it's working.
165 To see more detailed description of the options use:
169 To shrink the capture file by truncating the packets at 64 bytes and writing it as Sun snoop file use:
171 editcap -s 64 -F snoop capture.pcap shortcapture.snoop
173 To delete packet 1000 from the capture file use:
175 editcap capture.pcap sans1000.pcap 1000
177 To limit a capture file to packets from number 200 to 750 (inclusive) use:
179 editcap -r capture.pcap small.pcap 200-750
181 To get all packets from number 1-500 (inclusive) use:
183 editcap -r capture.pcap 500.pcap 1-500
187 editcap capture.pcap 500.pcap 501-9999999
189 To filter out packets 10 to 20 and 30 to 40 into a new file use:
191 editcap capture.pcap selection.pcap 10-20 30-40
193 To introduce 5% random errors in a capture file use:
197 editcap -E 0.05 capture.pcap capture_error.pcap
203 tcpdump(8), pcap(3), wireshark(1), mergecap(1)
207 B<Editcap> is part of the B<Wireshark> distribution. The latest version
208 of B<Wireshark> can be found at L<http://www.wireshark.org>.
210 HTML versions of the Wireshark project man pages are available at:
211 L<http://www.wireshark.org/docs/man-pages>.
217 Richard Sharpe <sharpe[AT]ns.aus.com>
222 Guy Harris <guy[AT]alum.mit.edu>
223 Ulf Lamping <ulf.lamping[AT]web.de>