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authorPouria Mousavizadeh Tehrani <pouria@FreeBSD.org>2026-02-12 23:06:15 +0000
committerPouria Mousavizadeh Tehrani <pouria@FreeBSD.org>2026-02-13 22:02:04 +0000
commitf2c2e5b0bf9def01b10651b9802fa38d07d9d265 (patch)
treef201bda8ce0790f4bdfec666f45ffc056ec8a06e
parentfd52a9becc62f721ad6a61c7301559afaedee010 (diff)
multicast.4: Fix disabling multicast forwarding
Reviewed by: markj, glebius MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D55266
-rw-r--r--share/man/man4/multicast.426
1 files changed, 22 insertions, 4 deletions
diff --git a/share/man/man4/multicast.4 b/share/man/man4/multicast.4
index aa3293e107eb..84c6c5c4199b 100644
--- a/share/man/man4/multicast.4
+++ b/share/man/man4/multicast.4
@@ -23,7 +23,7 @@
.\" FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
.\" DEALINGS IN THE SOFTWARE.
.\"
-.Dd May 27, 2009
+.Dd February 13, 2026
.Dt MULTICAST 4
.Os
.\"
@@ -124,15 +124,15 @@ Therefore, for portability reason the multicast
routing socket should be reused for IGMP and MLD messages as well.
.Pp
After the multicast routing socket is open, it can be used to enable
-or disable multicast forwarding in the kernel:
+multicast forwarding in the kernel:
.Bd -literal
/* IPv4 */
-int v = 1; /* 1 to enable, or 0 to disable */
+int v = 1;
setsockopt(mrouter_s4, IPPROTO_IP, MRT_INIT, (void *)&v, sizeof(v));
.Ed
.Bd -literal
/* IPv6 */
-int v = 1; /* 1 to enable, or 0 to disable */
+int v = 1;
setsockopt(mrouter_s6, IPPROTO_IPV6, MRT6_INIT, (void *)&v, sizeof(v));
\&...
/* If necessary, filter all ICMPv6 messages */
@@ -142,6 +142,24 @@ setsockopt(mrouter_s6, IPPROTO_ICMPV6, ICMP6_FILTER, (void *)&filter,
sizeof(filter));
.Ed
.Pp
+When applied to the multicast routing socket, the
+.Dv MRT_DONE
+and
+.Dv MRT6_DONE
+socket options disable multicast forwarding in the kernel:
+.Bd -literal
+/* IPv4 */
+int v = 1;
+setsockopt(mrouter_s4, IPPROTO_IP, MRT_DONE, (void *)&v, sizeof(v));
+.Ed
+.Bd -literal
+/* IPv6 */
+int v = 1;
+setsockopt(mrouter_s6, IPPROTO_IPV6, MRT6_DONE, (void *)&v, sizeof(v));
+.Ed
+.Pp
+Closing the socket has the same effect.
+.Pp
After multicast forwarding is enabled, the multicast routing socket
can be used to enable PIM processing in the kernel if we are running PIM-SM or
PIM-DM