NAME

rwpdedupe - Eliminate duplicate packets collected by several sensors

SYNOPSIS

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

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 3) 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.

EXAMPLES

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

NOTES