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.Dd April 10, 2007
.Dt IFMCSTAT 8
.Os
.Sh NAME
.Nm ifmcstat
.Nd dump multicast group management statistics per interface
.Sh SYNOPSIS
.Nm
.Op Fl i Ar interface
.Op Fl f Ar address-family
.Op Fl M Ar core
.Op Fl N Ar system
.Nm
.Op Ar kernel
.\"
.Sh DESCRIPTION
The
.Nm
command dumps multicast group information from the kernel.
.Pp
The following options are supported:
.Bl -tag -width Fl
.It Fl i Ar interface
specifies the interface to be displayed.
.Pp
.It Fl f Ar address-family
specifies the address-family to be displayed; currently only
.Ar inet
and
.Ar inet6
are supported.
.El
.Pp
The following options are only available if
.Nm
has been built with support for
.Xr kvm 3 .
.Bl -tag -width Fl
.It Fl M Ar core
extracts values associated with the name list from the specified core,
instead of the default
.Pa /dev/kmem .
.It Fl N Ar system
extracts the name list from the specified kernel instead of the
default, which is the kernel image the system has booted from.
.It Nm Ar system
This is the same as specifying
.Nm
.Fl N Ar system .
This usage is deprecated; it is supported only for backwards compatibility.
.Sh IMPLEMENTATION NOTES
When built without
.Xr kvm 3
support, the information displayed by
.Nm
is more limited.
This support is recommended for debugging purposes.
It requires superuser privilege if used to inspect a running kernel.
.Pp
When run without using
.Xr kvm 3
support,
.Nm
may print multicast MAC addresses twice if they are
referenced by a layer 3 protocol.
.Pp
When run with
.Xr kvm 3
support,
the names of all interfaces configured in the system will be
printed in the first column of output, even if no multicast
addresses are configured on those interfaces.
.Sh SEE ALSO
.Xr getifaddrs 3 ,
.Xr getifmaddrs 3 ,
.Xr kvm 3 ,
.Xr netstat 8
.Sh BUGS
.Nm
does not support the
.Ar link
argument to the
.Ar address-family
option.