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 that.
-d Print a list of network interfaces available.
-v Print timestamp for each packet.
-vv Print timestamp and hex data for each packet.
Send pcap-file(s) out onto the network through interface.
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.
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-
Send up to count packets. Default is to send all packets from
Set interval multiplier to speed. Set speed to 0 or less to send
the next packet immediately. Minimum positive value for speed is
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
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.
bittwistb(1), bittwiste(1), pcap(3), tcpdump(1)
File your bug report and send to:
Addy Yeow Chin Heng <firstname.lastname@example.org>
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
Copyright (C) 2006 - 2010 Addy Yeow Chin Heng <email@example.com> and
nPulse Network Systems, LLC.
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
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 http://bittwist.sourceforge.net
12 December 2009