diff --git a/ndisc.h b/ndisc.h
new file mode 100644
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--- /dev/null
+++ b/ndisc.h
@@ -0,0 +1,29 @@
+// Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SHILL_NDISC_H_
+#define SHILL_NDISC_H_
+
+// Neighbor discovery related definitions. This is needed because kernel
+// currently does not export these definitions to the user space.
+
+// Netlink multicast group for neighbor discovery user option message.
+#define RTMGRP_ND_USEROPT 0x80000
+
+// Neighbor Discovery user option header definition.
+struct NDUserOptionHeader {
+  NDUserOptionHeader() {
+    memset(this, 0, sizeof(*this));
+  }
+  uint8 type;
+  uint8 length;
+  uint16 reserved;
+  uint32 lifetime;
+} __attribute__((__packed__));
+
+// Neighbor Discovery user option type definition.
+#define ND_OPT_RDNSS 25       /* RFC 5006 */
+#define ND_OPT_DNSSL 31       /* RFC 6106 */
+
+#endif  // SHILL_NDISC_H_