.\" Copyright (C) 2006  Stig Venaas <venaas@uninett.no>
.TH mcfirst "1" "User Manuals"
.SH NAME
mcfirst \- check if you can receive IPv4/IPv6 multicast
.SH SYNOPSIS
.B mcfirst
[
.B \-46vr
] [
.B \-I
.I interface
] [
.B \-c
.I count
] [
.B \-t
.I time
] [
.I source
]
.I group
.I port

.SH DESCRIPTION
.B mcfirst
can be used to check whether one can receive multicast packets from a host. The host may send any type of
multicast packets, any application, IPv4 or IPv6, ASM or SSM.
.B mcfirst
joins the specified (source) and group, and listens to the specified port.
.B mcfirst will by default exit when the first packet is received, and print how long it waited.
.SH OPTIONS
The options are as follows.
.TP
.B \-4
Force IPv4
.TP
.B \-6
Force IPv6
.TP
.B \-v
Print version
.TP
.B \-r
Print rate information only
.TP
\fB-I\fR \fIinterface\fR
Interface to join on
.TP
\fB-c\fR \fIcount\fR
Stop after receiving
.I count
packets. Default is 1 unless time limit is specified
.TP
\fB-t\fR \fItime\fR
Exit after
.I time
seconds. Default is to exit after the first packet. If both
.I count
and
.I time
are specified, mcfirst will exit as soon as one of them is satisfied.
.SH SEE ALSO
ssmping(1) a tool for checking whether can receive SSM.
.TP
dbeacon(1) a distributed beacon multicast implementation.
.SH BUGS
Please report them to Stig Venaas <venaas@uninett.no>, the author of this tool.
.SH HISTORY
\fBmcfirst\fR was developed by Stig Venaas during the
early days of the m6bone, the IPv6 multicast backbone.