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editcap [ -c <packets per file> ] [ -C <choplen> ] [ -E <error probability> ] [ -F <file format> ] [ -A <start time> ] [ -B <stop time> ] [ -h ] [ -r ] [ -s <snaplen> ] [ -t <time adjustment> ] [ -T <encapsulation type> ] [ -v ] infile outfile [ packet#[-packet#] ... ]
Editcap is a filter that reads some or all of the captured packets from the infile, optionally converts them in various ways and writes the resulting packets to the capture outfile (or outfiles).
By default, it reads all packets from the infile and writes them to the outfile in libpcap file format.
A list of packet numbers can be specified on the command line; ranges of packet numbers can be specified as start-end, referring to all packets from start to end. The selected packets with those numbers will not be written to the capture file. If the -r flag is specified, the whole packet selection is reversed; in that case only the selected packets will be written to the capture file.
Editcap is able to detect, read and write the same capture files that are supported by Ethereal. The input file doesn't need a specific filename extension, the file format and an optional gzip compression will be automatically detected. The capture file format section of ethereal(1) or http://www.ethereal.com/docs/man-pages/ethereal.1.html provides a detailed description.
Editcap can write the file in several output formats. The -F flag can be used to specify the format in which to write the capture file, editcap -F provides a list of the available output formats.
This is useful in the rare case that the conversion between two file formats leaves some random bytes at the end of each packet.
This option is meant to be used for fuzz-testing protocol dissectors.
This may be useful if the program that is to read the output file cannot handle packets larger than a certain size (for example, the versions of snoop in Solaris 2.5.1 and Solaris 2.6 appear to reject Ethernet packets larger than the standard Ethernet MTU, making them incapable of handling gigabit Ethernet captures if jumbo packets were used).
This feature is useful when synchronizing dumps collected on different machines where the time difference between the two machines is known or can be estimated.
Note: this merely forces the encapsulation type of the output file to be the specified type; the packet headers of the packets will not be translated from the encapsulation type of the input capture file to the specified encapsulation type (for example, it will not translate an Ethernet capture to an FDDI capture if an Ethernet capture is read and '-T fddi' is specified).
To see more detailed description of the options use:
To shrink the capture file by truncating the packets at 64 bytes and writing it as Sun snoop file use:
editcap -s 64 -F snoop capture.pcap shortcapture.snoop
To delete packet 1000 from the capture file use:
editcap capture.pcap sans1000.pcap 1000
To limit a capture file to packets from number 200 to 750 (inclusive) use:
editcap -r capture.pcap small.pcap 200-750
To get all packets from number 1-500 (inclusive) use:
editcap -r capture.pcap 500.pcap 1-500
editcap capture.pcap 500.pcap 501-9999999
To filter out packets 10 to 20 and 30 to 40 into a new file use:
editcap capture.pcap selection.pcap 10-20 30-40
To introduce 5% random errors in a capture file use:
editcap -E 0.05 capture.pcap capture_error.pcap
[fw-wiz] [OT] tcpdump parsing -- editcapSloane, David DSloane@vfa.com
editcap is your friend. It will break up the log file for you in a quick, memory-efficient way. See http://www.ethereal.com/editcap.1.html -David -----Original Message----- From: email@example.com [mailto:firstname.lastname@example.org] On Behalf Of Damian Gerow Sent: October 08, 2003 2:20 PM To: email@example.com Subject: [fw-wiz] [OT] tcpdump parsing First off, apologies for the off-topic post. But I have no idea where to turn for tcpdump help, and I figured most of the folks here have used it at least moderately, if not extensively. I've been spending the past week or so trying to track down what seems to be a trojan that has been affecting our customers, that seems to come and go. To give myself a little more to work with, I've nabbed 550MB worth of network traffic from one of their links, spanning a couple of days. The problem is, I can't open this up in ethereal. The file is just too large. I've tried trimming the fat down (POP3 sessions, web browsing sessions, ICMP echo request/reply, certain gaming sites, etc.), but I'm still sitting here with 500MB of traffic. Is there a way to take a tcpdump binary file, and pull a date range from it? The tcpdump man page leads me to believe no, and a fair bit of Google searching has provided no leads. I'd also be willing to try various other GUIs that understand tcpdump output (so long as they run on X). Yes, I'm fully aware that I can do this all on the commandline, but I find the GUI a bit easier to work with in this case. Any pointers or suggestions are very welcomed at this point. It's frustrating to be sitting with the culprit on disk, but not be able to find out who or what the culprit /is/. _______________________________________________ firewall-wizards mailing list firstname.lastname@example.org http://honor.icsalabs.com/mailman/listinfo/firewall-wizards
editcap can be used to introduce errors into normal capture files
editcap can be used to "fuzz" a capture file using the '-E' flag. For example,editcap -E 0.02 infile.pcap fuzzfile.pcap
would read infile.pcap and fuzz its contents, writing them to fuzzfile.pcap. There would be a 2% chance that any given payload byte would be fuzzed. There are four different fuzzing methods, chosen at random:
- The byte can be replaced with a random byte value
- The byte can be replaced with a random letter or number
- The byte and the succeeding byte can be replaced with "%s"
- The rest of the packet can be filled with 0xAA
editcap is built together with Wireshark and is also shipped with the releases.
editcap - Edit and-or translate the format of capture files
Also at editcap - Edit and/or translate the format of capture files
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