IFMCSTAT(8)             FreeBSD System Manager's Manual            IFMCSTAT(8)

NAME
     ifmcstat - dump multicast group management statistics per interface

SYNOPSIS
     ifmcstat [-i interface] [-f address-family] [-v] [-K] [-M core]
              [-N system]

DESCRIPTION
     The ifmcstat command dumps multicast group information from the kernel.

     The following options are supported:

     -i interface
                 specifies the interface to be displayed.

     -f address-family
                 specifies the address family to be displayed; inet, inet6 and
                 link are supported.

     -v          specifies that link-layer memberships should be printed; they
                 are suppressed by default.  It may not be specified for -f
                 link.  Source lists for each group will also be printed.

                 If specified twice, and kvm(3) is in use, the control plane
                 timers for each interface and the source list counters for
                 each group will also be printed.

     The following options are only available if ifmcstat has been built with
     support for kvm(3):

     -K          attempts to use kvm(3) to retrieve the multicast group
                 information.

     -M core     extracts values associated with the name list from the
                 specified core, instead of the default /dev/kmem.

     -N system   extracts the name list from the specified kernel instead of
                 the default, which is the kernel image the system has booted
                 from.

IMPLEMENTATION NOTES
     ifmcstat will always print the embedded scope IDs of IPv6 multicast group
     memberships.  This is because memberships are always scoped to an
     interface.

     When run with the -v option, ifmcstat may print multicast MAC addresses
     twice if they are referenced by a layer 3 protocol.

     When run with 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 group memberships are present on those interfaces.  The output
     may also be slightly different, as the kernel data structures are being
     traversed with minimal post-processing of the output.

     When built without kvm(3) support, the information displayed by ifmcstat
     is more limited.  This support is recommended for debugging purposes.  It
     requires super-user privilege if used to inspect a running kernel.

SEE ALSO
     netstat(1), getifaddrs(3), getifmaddrs(3), kvm(3)

FreeBSD 13.1-RELEASE-p6          May 27, 2009          FreeBSD 13.1-RELEASE-p6