diff --git a/hio/lib/dhcp-svr.c b/hio/lib/dhcp-svr.c
index a3ab735..dae1c2f 100644
--- a/hio/lib/dhcp-svr.c
+++ b/hio/lib/dhcp-svr.c
@@ -22,6 +22,7 @@
     THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <hio-dhcp.h>
 #include <hio-sck.h>
 #include "hio-prv.h"
 
diff --git a/hio/lib/hio-dhcp.h b/hio/lib/hio-dhcp.h
index 28e7947..7632302 100644
--- a/hio/lib/hio-dhcp.h
+++ b/hio/lib/hio-dhcp.h
@@ -28,7 +28,75 @@
 #include <hio.h>
 #include <hio-skad.h>
 
-#define HIO_DNS_PORT (53)
+#define HIO_DHCP6_SERVER_PORT     (547)
+#define HIO_DHCP6_CLIENT_PORT     (546)
+#define HIO_DHCP6_HOP_COUNT_LIMIT (32)
+
+enum hio_dhcp6_msg_t
+{
+	HIO_DHCP6_MSG_SOLICIT     = 1,
+	HIO_DHCP6_MSG_ADVERTISE   = 2,
+	HIO_DHCP6_MSG_REQUEST     = 3,
+	HIO_DHCP6_MSG_CONFIRM     = 4,
+	HIO_DHCP6_MSG_RENEW       = 5,
+	HIO_DHCP6_MSG_REBIND      = 6,
+	HIO_DHCP6_MSG_REPLY       = 7,
+	HIO_DHCP6_MSG_RELEASE     = 8,
+	HIO_DHCP6_MSG_DECLINE     = 9,
+	HIO_DHCP6_MSG_RECONFIGURE = 10,
+	HIO_DHCP6_MSG_INFOREQ     = 11,
+	HIO_DHCP6_MSG_RELAYFORW   = 12,
+	HIO_DHCP6_MSG_RELAYREPL   = 13,
+};
+typedef enum hio_dhcp6_msg_t hio_dhcp6_msg_t;
+
+enum hio_dhcp6_opt_t
+{
+	HIO_DHCP6_OPT_RELAY_MESSAGE = 9,
+	HIO_DHCP6_OPT_INTERFACE_ID = 18
+};
+typedef enum hio_dhcp6_opt_t hio_dhcp6_opt_t;
+
+
+
+/* ---------------------------------------------------------------- */
+#include <hio-pac1.h>
+
+struct hio_dhcp6_pkt_hdr_t
+{
+	hio_uint8_t msgtype;
+	hio_uint8_t transid[3];
+};
+typedef struct hio_dhcp6_pkt_hdr_t hio_dhcp6_pkt_hdr_t;
+
+struct hio_dhcp6_relay_hdr_t
+{
+	hio_uint8_t msgtype;  /* RELAY-FORW, RELAY-REPL */
+	hio_uint8_t hopcount;
+	hio_uint8_t linkaddr[16];
+	hio_uint8_t peeraddr[16];
+};
+typedef struct hio_dhcp6_relay_hdr_t hio_dhcp6_relay_hdr_t;
+
+struct hio_dhcp6_opt_hdr_t
+{
+	hio_uint16_t code;
+	hio_uint16_t len; /* length of option data, excludes the option header */
+};
+typedef struct hio_dhcp6_opt_hdr_t hio_dhcp6_opt_hdr_t;
+
+#include <hio-upac.h>
+
+
+struct hio_dhcp6_pktinf_t
+{
+	hio_dhcp6_pkt_hdr_t* hdr;
+	hio_oow_t            len;
+};
+typedef struct hio_dhcp6_pktinf_t hio_dhcp6_pktinf_t;
+
+/* ---------------------------------------------------------------- */
+
 
 typedef struct hio_svc_dhcs_t hio_svc_dhcs_t; 
 
@@ -39,12 +107,15 @@ extern "C" {
 #endif
 
 HIO_EXPORT hio_svc_dhcs_t* hio_svc_dhcs_start (
-	hio_t*             hio,
+	hio_t*             hio
+#if 0
+	,
 	const hio_skad_t*  serv_addr, /* required */
 	const hio_skad_t*  bind_addr, /* optional. can be HIO_NULL */
 	const hio_ntime_t* send_tmout, /* required */
 	const hio_ntime_t* reply_tmout, /* required */
 	hio_oow_t          max_tries /* required */
+#endif
 );
 
 HIO_EXPORT void hio_svc_dhcs_stop (