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 July 9, 2008 26.Dt MCGRAB 1 27.Os 28.Sh NAME 29.Nm mcgrab 30.Nd "multicast filter overload test" 31.Sh SYNOPSIS 32.Nm 33.Op Fl i Ar interface 34.Op Fl g Ar group 35.Op Fl n Ar number 36.Sh DESCRIPTION 37The 38.Nm 39command implements a multicast test which grabs and holds 40N multicast addresses. 41The purpose of the test is to see what 42happens when a network interface is no longer able to filter 43multicasts in hardware and has to switch to promiscuous or 44multicast promiscuous mode. 45A successful test does not have any 46result, but an unsuccessful test will have deleterious side effects. 47Packet size in bytes. 48The options are as follows: 49.Bl -tag -width ".Fl i Ar interface" 50.It Fl i Ar interface 51Network interface, which can be found with 52.Xr ifconfig 8 . 53.It Fl g Ar group 54Multicast group. 55.It Fl n Ar number 56Number of groups to join. 57.El 58.Sh EXAMPLES 59The following is an example of a typical usage 60of the 61.Nm 62command: 63.Pp 64.Dl "mcgrab -i em0 -g 239.255.255.1 -n 1024" 65.Sh SEE ALSO 66.Xr mctest 1 , 67.Xr netstat 1 , 68.Xr nanosleep 2 , 69.Xr ifconfig 8 70.Sh HISTORY 71The 72.Nm 73program first appeared in 74.Fx 7.0 . 75.Sh AUTHORS 76This 77manual page was written by 78.An George V. Neville-Neil Aq Mt gnn@FreeBSD.org . 79.Sh BUGS 80Should be reported to the author or to 81.Aq Mt net@FreeBSD.org . 82