Provided by: bittwist_2.0-8_amd64 bug


       bittwist -- pcap based ethernet packet generator


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


       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


       -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.


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


       File your bug report and send to:

              Addy Yeow Chin Heng <>

       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 (C) 2006 - 2012 Addy Yeow Chin Heng <>

       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.


       Original author and current maintainer:

              Addy Yeow Chin Heng

       The current version is available from

                                          21 April 2012                               BITTWIST(1)