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.Dd December 23, 2008 26.Dt ETHER_REFLECT 1 27.Os 28.Sh NAME 29.Nm ether_reflect 30.Nd "reflect ethernet packets" 31.Sh SYNOPSIS 32.Nm 33.Op Fl a Ar ethernet address 34.Op Fl e Ar ethertype 35.Op Fl i Ar interface 36.Op Fl t Ar timeout 37.Op Fl p 38.Op Fl d 39.Sh DESCRIPTION 40The 41.Nm 42command implements a simple ethernet packet reflector using the 43.Xr pcap 3 44library and 45.Xr bpf 4 , 46the Berkeley Packet Filter. 47The program is useful primarily to test the low level round trip time 48of packets through an Ethernet interface and/or a switch. 49Network protocols, such as IP, and the network stack in general are never 50invoked, only the device driver that implements the particular interface 51is executed. 52As the 53.Nm 54command uses the 55.Xr bpf 4 56device the user must have root privileges to execute this program. 57.Pp 58The options are as follows: 59.Bl -tag -width ".Fl d Ar argument" 60.It Fl a Ar address 61Instead of reversing the ethernet destination and source addresses 62supply a different destination ethernet address for each packet 63received. 64.It Fl e Ar ether type 65Use a different ethertype than the default, 0x8822, which is the IEEE 66ether type for driver testing. 67.It Fl i Ar interface 68Network interface, which can be found with ifconfig(1). 69.It Fl t Ar timeout 70The time, in milliseconds, to wait for a packet. 71Lower times decrease latency at the cost of CPU. 72.It Fl p 73Set the device into promiscuous mode before testing. 74This is not usually necessary. 75.It Fl d 76Debug output. 77Print various small pieces of debug information. 78.El 79.Sh EXAMPLES 80The following is an example of a typical usage 81of the 82.Nm 83command: 84.Pp 85.Dl "ether_reflect -i em0 -t 1" 86.Pp 87Reflect all test packets, those with an ether type of 0x8822, which 88are seen on ineterface em0. 89The timeout is 1 millisecond. 90.Pp 91.Dl "ether_reflect -i em0 -a 00:00:00:aa:bb:cc -t 1" 92.Pp 93Rewrite the destination address in each packet to 00:00:00:aa:bb:cc 94before reflecting the packet. 95.Sh SEE ALSO 96.Xr tcpdump 1 , 97.Xr bpf 4 , 98.Xr pcap 3 , 99.Xr ifconfig 8 100.Sh HISTORY 101The 102.Nm 103program first appeared in 104.Fx 8.0 . 105.Sh AUTHORS 106This 107manual page was written by 108.An George V. Neville-Neil Aq Mt gnn@FreeBSD.org . 109.Sh BUGS 110Should be reported to the author or to 111.Aq Mt net@FreeBSD.org . 112