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BITTWIST(1)            DragonFly General Commands Manual           BITTWIST(1)


NAME

       bittwist -- pcap based ethernet packet generator


SYNOPSIS

       bittwist [ -dvh ] [ -i interface ] [ -s length ] [ -l loop ]
                [ -c count ] [ -m speed ] [ -r rate ] [ -p sleep ]
                pcap-file(s)


DESCRIPTION

       This document describes the bittwist program, the pcap(3) based
       Ethernet packet generator. Bittwist is designed to work under Ethernet
       II (IEEE 802.3) network with a MTU of up to 1500 bytes on 10Mbps
       (10Base-T Ethernet) or 100Mbps (Fast Ethernet) link speed. Packets are
       generated from saved tcpdump(1) capture file referred to as trace file
       in this document. Some familiarity with tcpdump(1) and its basic
       options are assumed in this document. Since bittwist uses functions
       provided by pcap(3) library, e.g. pcap_open_live() and pcap_inject(),
       to write packets onto the network, it may require that you have special
       privileges, e.g. read access to /dev/bpf* on BSD or root access on
       Linux, to generate packets or to enumerate network devices with, for
       example, the -d flag.

       Bittwist will, if not run with the -s flag, inject each packet up to
       its actual length (on-wire) instead of its captured length. If the
       captured length is less than the actual length, bittwist will pad the
       packet with zeros up to its actual length prior to injection. Bittwist
       will, if not run with the -m, -r, or -p flag, inject packets from a
       trace file based on the captured intervals, in particular, the
       timestamp difference between two adjacent packets, except for the first
       packet in a trace file, which is always injected immediately. Bittwist
       is designed to not to interfere with the packet data; it merely read a
       packet and inject it as is onto the network. If modification is desired
       prior to injection of a packet, you can use the bittwiste(1) program,
       which does just that.


OPTIONS

       -d     Print a list of network interfaces available.

       -v     Print timestamp for each packet.

       -vv    Print timestamp and hex data for each packet.

       -i interface
              Send pcap-file(s) out onto the network through interface.

       -s length
              Packet length to send. Set length to:

              0 to send the actual packet length. This is the default.
              -1 to send the captured length.

              or any other value from 14 to 1514.

       -l loop
              Send pcap-file(s) out onto the network for loop times. Set loop
              to 0 to send pcap-file(s) until stopped. To stop, type Control-
              C.

       -c count
              Send up to count packets. Default is to send all packets from
              pcap-file(s).

       -m speed
              Set interval multiplier to speed. Set speed to 0 or less to send
              the next packet immediately. Minimum positive value for speed is
              0.000001.

       -r rate
              Limit the sending to rate Mbps. Value for rate must be between 1
              to 1000. This option is meant to limit the maximum packet
              throughput.  If you want to send packets at line rate of
              100Mbps, try -m 0 -r 100

       -p sleep
              Set interval to sleep (in seconds), ignoring the actual
              interval. Value for sleep must be between 1 to 2146.

       -h     Print version information and usage.


SEE ALSO

       bittwistb(1), bittwiste(1), pcap(3), tcpdump(1)


BUGS

       File your bug report and send to:

              Addy Yeow Chin Heng <ayeowch@gmail.com>

       Make sure you are using the latest stable version before submitting
       your bug report.

       If you run bittwist with -m flag set to 0 without limiting the
       throughput with -r flag, pcap_inject() may return an error with the
       following error string:

              send: No buffer space available

       We recommend that you specify the -r flag to limit the packet
       throughput, e.g. -m 0 -r 100 to inject packets at a maximum rate of
       100Mbps.


COPYRIGHT

       Copyright (C) 2006 - 2011 Addy Yeow Chin Heng <ayeowch@gmail.com>

       This program is free software; you can redistribute it and/or modify it
       under the terms of the GNU General Public License as published by the
       Free Software Foundation; either version 2 of the License, or any later
       version.

       This program is distributed in the hope that it will be useful, but
       WITHOUT ANY WARRANTY; without even the implied warranty of
       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
       General Public License for more details.

       You should have received a copy of the GNU General Public License along
       with this program; if not, write to the Free Software Foundation, Inc.,
       51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.


AUTHORS

       Original author and current maintainer:

              Addy Yeow Chin Heng

       The current version is available from http://bittwist.sourceforge.net

                               12 December 2009                    BITTWIST(1)

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