SiLK

NAME

rwpdedupe - Eliminate duplicate packets collected by several sensors

SYNOPSIS

  rwpdedupe { --first-duplicate | --random-duplicate[=SCALAR] }
        [--threshold=MILLISECONDS] FILE... > OUTPUT-FILE

  rwpdedupe --help

  rwpdedupe --version

DESCRIPTION

Detects and eliminates duplicate records from tcpdump(1) capture files. Duplicate records are defined as having timestamps within a user-configurable time of each other. In addition, their Ethernet (OSI layer 2) headers must match. If they are not IP packets, then their entire Ethernet payload must match. If they are IP packets, then their source and destination addresses, protocol, and IP payload must match.

OPTIONS

Option names may be abbreviated if the abbreviation is unique or is an exact match for an option. A parameter to an option may be specified as --arg=param or --arg param, though the first form is required for options that take optional parameters.

--threshold=MILLISECONDS

Set the maximum number of milliseconds which may elapse between two packets and still have those packets be detected as duplicates. Default 0 (exact timestamp match). Must be a value between 0 and 1,000,000 milliseconds.

One and only one of the following switches is required:

--first-duplicate

When selecting between multiple duplicate packets, always choose the packet with the earliest timestamp. Not compatible with --random-duplicate.

--random-duplicate

--random-duplicate=SCALAR

Select a random packet from the list of duplicate packets. SCALAR is a random number seed, so that multiple runs can produce identical results.

--help

Print the available options and exit.

--version

Print the version number and information about how SiLK was configured, then exit the application.

EXAMPLES

In the following example, the dollar sign ($) represents the shell prompt. The text after the dollar sign represents the command line. Lines have been wrapped for improved readability, and the back slash (\) is used to indicate a wrapped line.

Given tcpdump files data1.tcp and data2.tcp, detect and eliminate duplicate packets which occur within one second of each other (when choosing which timestamp to output, pick one randomly.) Store the result file in out.tcp.

 $ rwpdedupe --threshold=1000 --random-duplicate \
        data1.tcp data2.tcp > out.tcp

SEE ALSO

silk(7), mergecap(1), tcpdump(1), pcap(3)

NOTES

mergecap(1) can be used to merge two tcpdump capture files without eliminating duplicate packets.