1.\" Copyright (c) 2008 George V. Neville-Neil 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd December 23, 2008 28.Dt ETHER_REFLECT 1 29.Os 30.Sh NAME 31.Nm ether_reflect 32.Nd "reflect ethernet packets" 33.Sh SYNOPSIS 34.Nm 35.Op Fl a Ar ethernet address 36.Op Fl e Ar ethertype 37.Op Fl i Ar interface 38.Op Fl t Ar timeout 39.Op Fl p 40.Op Fl d 41.Sh DESCRIPTION 42The 43.Nm 44command implements a simple ethernet packet reflector using the 45.Xr pcap 3 46library and 47.Xr bpf 4 , 48the Berkeley Packet Filter. 49The program is useful primarily to test the low level round trip time 50of packets through an Ethernet interface and/or a switch. 51Network protocols, such as IP, and the network stack in general are never 52invoked, only the device driver that implements the particular interface 53is executed. 54As the 55.Nm 56command uses the 57.Xr bpf 4 58device the user must have root privileges to execute this program. 59.Pp 60The options are as follows: 61.Bl -tag -width ".Fl d Ar argument" 62.It Fl a Ar address 63Instead of reversing the ethernet destination and source addresses 64supply a different destination ethernet address for each packet 65received. 66.It Fl e Ar ether type 67Use a different ethertype than the default, 0x8822, which is the IEEE 68ether type for driver testing. 69.It Fl i Ar interface 70Network interface, which can be found with ifconfig(1). 71.It Fl t Ar timeout 72The time, in milliseconds, to wait for a packet. 73Lower times decrease latency at the cost of CPU. 74.It Fl p 75Set the device into promiscuous mode before testing. 76This is not usually necessary. 77.It Fl d 78Debug output. 79Print various small pieces of debug information. 80.El 81.Sh EXAMPLES 82The following is an example of a typical usage 83of the 84.Nm 85command: 86.Pp 87.Dl "ether_reflect -i em0 -t 1" 88.Pp 89Reflect all test packets, those with an ether type of 0x8822, which 90are seen on ineterface em0. 91The timeout is 1 millisecond. 92.Pp 93.Dl "ether_reflect -i em0 -a 00:00:00:aa:bb:cc -t 1" 94.Pp 95Rewrite the destination address in each packet to 00:00:00:aa:bb:cc 96before reflecting the packet. 97.Sh SEE ALSO 98.Xr tcpdump 1 , 99.Xr bpf 4 , 100.Xr pcap 3 , 101.Xr ifconfig 8 102.Sh HISTORY 103The 104.Nm 105program first appeared in 106.Fx 8.0 . 107.Sh AUTHORS 108This 109manual page was written by 110.An George V. Neville-Neil Aq Mt gnn@FreeBSD.org . 111.Sh BUGS 112Should be reported to the author or to 113.Aq Mt net@FreeBSD.org . 114