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. The program is useful primarily to test 49the low level round trip time of packets through an Ethernet interface 50and/or a switch. Network protocols, such as IP, and the network stack 51in general are never invoked, only the device driver that implements 52the particular interface is executed. As 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. Lower times decrease 71latency at the cost of CPU. 72.It Fl p 73Set the device into promiscuous mode before testing. This is not 74usually necessary. 75.It Fl d 76Debug output. Print various small pieces of debug information. 77.El 78.Sh EXAMPLES 79The following is an example of a typical usage 80of the 81.Nm 82command: 83.Pp 84.Dl "ether_reflect -i em0 -t 1" 85.Pp 86Reflect all test packets, those with an ether type of 0x8822, which 87are seen on ineterface em0. The timeout is 1 millisecond. 88.Pp 89.Dl "ether_reflect -i em0 -a 00:00:00:aa:bb:cc -t 1" 90.Pp 91Rewrite the destination address in each packet to 00:00:00:aa:bb:cc 92before reflecting the packet. 93.Sh SEE ALSO 94.Xr tcpdump 1 , 95.Xr bpf 2 , 96.Xr pcap 4 , 97.Xr ifconfig 8 98.Sh HISTORY 99The 100.Nm 101program first appeared in 102.Fx 8.0 . 103.Sh AUTHORS 104This 105manual page was written by 106.An George V. Neville-Neil Aq Mt gnn@FreeBSD.org . 107.Sh BUGS 108Should be reported to the author or to 109.Aq Mt net@FreeBSD.org . 110