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<Ethereal>.
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 The I<capture file format> section of I<ethereal(1)> or
47 I<http://www.ethereal.com/docs/man-pages/ethereal.1.html>
48 provides a detailed description.
50 B<Editcap> can write the file in several output formats. The B<-F>
51 flag can be used to specify the format in which to write the capture
52 file, B<editcap -F> provides a list of the available output formats.
58 =item -c E<lt>packets per fileE<gt>
60 Sets the maximum number of packets per output file. Each output file will
61 be created with a suffix -nnnnn, starting with 00000. If the specified
62 number of packets are written to the output file, the next output file is
63 opened. The default is to use a single output file.
65 =item -C E<lt>choplenE<gt>
67 Sets the chop length to use when writing the packet data.
68 Each packet is chopped at the packet end by a few <choplen> bytes of data.
70 This is useful in the rare case that the conversion between two file
71 formats leaves some random bytes at the end of each packet.
73 =item -E E<lt>error probabilityE<gt>
75 Sets the probabilty that bytes in the output file are randomly changed.
76 B<Editcap> uses that probability (between 0.0 and 1.0 inclusive)
77 to apply errors to each data byte in the file. For instance, a
78 probability of 0.02 means that each byte has a 2% chance of having an error.
80 This option is meant to be used for fuzz-testing protocol dissectors.
82 =item -F E<lt>file formatE<gt>
84 Sets the file format of the output capture file.
85 B<Editcap> can write the file in several formats, B<editcap -F>
86 provides a list of the available output formats. The default
87 is the B<libpcap> format.
89 =item -A E<lt>start timeE<gt>
91 Saves only the packets whose timestamp is on or after start time.
92 The time is given in the following format YYYY-MM-DD HH:MM:SS
94 =item -B E<lt>stop timeE<gt>
96 Saves only the packets whose timestamp is on or before stop time.
97 The time is given in the following format YYYY-MM-DD HH:MM:SS
101 Prints the version and options and exits.
105 Reverse the packet selection.
106 Causes the packets whose packet numbers are specified on the command
107 line to be written to the output capture file, instead of discarding them.
109 =item -s E<lt>snaplenE<gt>
111 Sets the snapshot length to use when writing the data.
112 If the B<-s> flag is used to specify a snapshot length, packets in the
113 input file with more captured data than the specified snapshot length
114 will have only the amount of data specified by the snapshot length
115 written to the output file.
117 This may be useful if the program that is
118 to read the output file cannot handle packets larger than a certain size
119 (for example, the versions of snoop in Solaris 2.5.1 and Solaris 2.6
120 appear to reject Ethernet packets larger than the standard Ethernet MTU,
121 making them incapable of handling gigabit Ethernet captures if jumbo
124 =item -t E<lt>time adjustmentE<gt>
126 Sets the time adjustment to use on selected packets.
127 If the B<-t> flag is used to specify a time adjustment, the specified
128 adjustment will be applied to all selected packets in the capture file.
129 The adjustment is specified as [-]I<seconds>[I<.fractional seconds>].
130 For example, B<-t> 3600 advances the timestamp on selected packets by one
131 hour while B<-t> -0.5 reduces the timestamp on selected packets by
134 This feature is useful when synchronizing dumps
135 collected on different machines where the time difference between the
136 two machines is known or can be estimated.
138 =item -T E<lt>encapsulation typeE<gt>
140 Sets the packet encapsulation type of the output capture file.
141 If the B<-T> flag is used to specify an encapsulation type, the
142 encapsulation type of the output capture file will be forced to the
144 B<editcap -T> provides a list of the available types. The default
145 type is the one appropriate to the encapsulation type of the input
149 forces the encapsulation type of the output file to be the specified
150 type; the packet headers of the packets will not be translated from the
151 encapsulation type of the input capture file to the specified
152 encapsulation type (for example, it will not translate an Ethernet
153 capture to an FDDI capture if an Ethernet capture is read and 'B<-T
154 fddi>' is specified).
158 Causes B<editcap> to print verbose messages while it's working.
164 To see more detailed description of the options use:
168 To shrink the capture file by truncating the packets at 64 bytes and writing it as Sun snoop file use:
170 editcap -s 64 -F snoop capture.pcap shortcapture.snoop
172 To delete packet 1000 from the capture file use:
174 editcap capture.pcap sans1000.pcap 1000
176 To limit a capture file to packets from number 200 to 750 (inclusive) use:
178 editcap -r capture.pcap small.pcap 200-750
180 To get all packets from number 1-500 (inclusive) use:
182 editcap -r capture.pcap 500.pcap 1-500
186 editcap capture.pcap 500.pcap 501-9999999
188 To filter out packets 10 to 20 and 30 to 40 into a new file use:
190 editcap capture.pcap selection.pcap 10-20 30-40
192 To introduce 5% random errors in a capture file use:
196 editcap -E 0.05 capture.pcap capture_error.pcap
202 I<tcpdump(8)>, I<pcap(3)>, I<ethereal(1)>, I<mergecap(1)>
206 B<Editcap> is part of the B<Ethereal> distribution. The latest version
207 of B<Ethereal> can be found at B<http://www.ethereal.com>.
209 HTML versions of the Wireshark project man pages are available at:
210 http://www.ethereal.com/docs/man-pages
216 Richard Sharpe <sharpe[AT]ns.aus.com>
221 Guy Harris <guy[AT]alum.mit.edu>
222 Ulf Lamping <ulf.lamping[AT]web.de>