Copyright (c) 2009 Bruce Simpson.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. Neither the name of the project nor the names of its contributors
may be used to endorse or promote products derived from this software
without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.
$FreeBSD: releng/10.2/share/man/man4/mld.4 249253 2013-04-08 10:53:22Z joel $
.Dd April 8, 2013 .Dt MLD 4 .Os .Sh NAME .Nm mld .Nd Multicast Listener Discovery Protocol .Sh SYNOPSIS n sys/types.h n sys/socket.h n netinet/in.h n netinet/in_systm.h n netinet/ip6.h n netinet/icmp6.h n netinet6/mld6.h .Ft int .Fn socket AF_INET6 SOCK_RAW IPPROTO_ICMPV6 .Sh DESCRIPTION .Tn MLD is a control plane protocol used by IPv6 hosts and routers to propagate multicast group membership information. Normally this protocol is not used directly, except by the kernel itself, in response to multicast membership requests by user applications. Multicast routing protocol daemons may open a raw socket to directly interact with .Nm and receive membership reports.
p
As of
.Fx 8.0 ,
MLD version 2 is implemented.
This adds support for Source-Specific Multicast (SSM), whereby
applications may communicate to upstream multicast routers that
they are only interested in receiving multicast streams from
particular sources.
The retransmission of state-change reports adds some robustness
to the protocol.
.Sh SYSCTL VARIABLES
l -tag -width indent
t net.inet6.mld.ifinfo This opaque read-only variable exposes the per-link MLDv2 status to
.Xr ifmcstat 8 .
t net.inet6.mld.gsrdelay This variable specifies the time threshold, in seconds, for processing
Group-and-Source Specific Queries (GSR).
As GSR query processing requires maintaining state on the host,
it may cause memory to be allocated, and is therefore a potential
attack point for Denial-of-Service (DoS).
If more than one GSR query is received within this threshold,
it will be dropped, to mitigate the potential for DoS.
t net.inet6.mld.v1enable If this variable is non-zero, then MLDv1 membership queries (and host
reports) will be processed by this host, and backwards compatibility
will be enabled until the v1 'Older Version Querier Present' timer expires.
This sysctl is normally enabled by default.
.El
.Sh SEE ALSO
.Xr netstat 1 ,
.Xr sourcefilter 3 ,
.Xr icmp6 4 ,
.Xr inet 4 ,
.Xr multicast 4 ,
.Xr ifmcstat 8
.Sh HISTORY
The
.Nm
manual page appeared in
.Fx 8.0 .