diff --git a/CHANGES b/CHANGES
index fde55804d4..594f551ef3 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,7 @@
+1146.	[func]		Allow IPV6_IPV6ONLY to be set/cleared on a socket if
+			supported by the OS by a new function
+			isc_socket_ipv6only().
+
 1145.	[func]		"host" no longer reports a NOERROR/NODATA response
 			by printing nothing. [RT #2065]
 
diff --git a/lib/isc/include/isc/socket.h b/lib/isc/include/isc/socket.h
index 50ba2c42a4..a2dd8ffb07 100644
--- a/lib/isc/include/isc/socket.h
+++ b/lib/isc/include/isc/socket.h
@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: socket.h,v 1.54 2001/03/06 01:23:02 bwelling Exp $ */
+/* $Id: socket.h,v 1.55 2001/11/29 07:31:25 marka Exp $ */
 
 #ifndef ISC_SOCKET_H
 #define ISC_SOCKET_H 1
@@ -682,6 +682,16 @@ isc_socket_gettype(isc_socket_t *sock);
 isc_boolean_t
 isc_socket_isbound(isc_socket_t *sock);
 
+void
+isc_socket_ipv6only(isc_socket_t *sock, isc_boolean_t yes);
+/*
+ * If the socket is an IPv6 socket set/clear the IPV6_IPV6ONLY socket
+ * option if the host OS supports this option.
+ *
+ * Requires:
+ *	'sock' is a valid socket.
+ */
+
 ISC_LANG_ENDDECLS
 
 #endif /* ISC_SOCKET_H */
diff --git a/lib/isc/unix/socket.c b/lib/isc/unix/socket.c
index a395b35b64..20011f7340 100644
--- a/lib/isc/unix/socket.c
+++ b/lib/isc/unix/socket.c
@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: socket.c,v 1.215 2001/11/27 01:56:19 gson Exp $ */
+/* $Id: socket.c,v 1.216 2001/11/29 07:31:22 marka Exp $ */
 
 #include <config.h>
 
@@ -3310,6 +3310,25 @@ isc_socket_isbound(isc_socket_t *sock) {
 	return (val);
 }
 
+void
+isc_socket_ipv6only(isc_socket_t *sock, isc_boolean_t yes) {
+#if defined(IPV6_V6ONLY)
+	int onoff = yes ? 1 : 0;
+#else
+	UNUSED(yes);
+	UNUSED(sock);
+#endif
+
+	REQUIRE(VALID_SOCKET(sock));
+
+#ifdef IPV6_V6ONLY
+	if (sock->pf == AF_INET6) {
+		(void)setsockopt(sock->fd, IPPROTO_IPV6, IPV6_V6ONLY,
+				 (void *)&onoff, sizeof(onoff));
+	}
+#endif
+}
+
 #ifndef ISC_PLATFORM_USETHREADS
 void
 isc__socketmgr_getfdsets(fd_set *readset, fd_set *writeset, int *maxfd) {
diff --git a/lib/isc/win32/socket.c b/lib/isc/win32/socket.c
index cc0e9769c5..442255b640 100644
--- a/lib/isc/win32/socket.c
+++ b/lib/isc/win32/socket.c
@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: socket.c,v 1.11 2001/11/27 01:56:22 gson Exp $ */
+/* $Id: socket.c,v 1.12 2001/11/29 07:31:23 marka Exp $ */
 
 
 #define MAKE_EXTERNAL 1
@@ -3401,3 +3401,11 @@ isc_socket_isbound(isc_socket_t *sock) {
 
 	return (val);
 }
+
+void
+isc_socket_ipv6only(isc_socket_t *sock, isc_boolean_t yes) {
+	UNUSED(yes);
+	UNUSED(sock);
+
+	REQUIRE(VALID_SOCKET(sock));
+}