diff --git a/CHANGELOG b/CHANGELOG
index 14ac3d6..d001a3d 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -114,6 +114,12 @@ version 2.67
 	    Cope with DHCPv6 clients which send REQUESTs without
 	    address options - treat them as SOLICIT with rapid commit.
 
+	    Support identification of clients by MAC address in
+	    DHCPv6. When using a relay, the relay must support RFC
+	    6939 for this to work. It always works for directly
+	    connected clients. Thanks to Vladislav Grishenko
+	    for prompting this feature.
+
 
 version 2.66
             Add the ability to act as an authoritative DNS
diff --git a/man/dnsmasq.8 b/man/dnsmasq.8
index 05733b8..e313d54 100644
--- a/man/dnsmasq.8
+++ b/man/dnsmasq.8
@@ -766,7 +766,8 @@ the same subnet as some valid dhcp-range.  For
 subnets which don't need a pool of dynamically allocated addresses,
 use the "static" keyword in the dhcp-range declaration.
 
-It is allowed to use client identifiers rather than
+It is allowed to use client identifiers (called client
+DUID in IPv6-land rather than
 hardware addresses to identify hosts by prefixing with 'id:'. Thus: 
 .B --dhcp-host=id:01:02:03:04,..... 
 refers to the host with client identifier 01:02:03:04. It is also
@@ -781,11 +782,12 @@ IPv6 addresses may contain only the host-identifier part:
 .B --dhcp-host=laptop,[::56]
 in which case they act as wildcards in constructed dhcp ranges, with
 the appropriate network part inserted. 
-Note that in IPv6 DHCP, the hardware address is not normally
-available, so a client must be identified by client-id (called client
-DUID in IPv6-land) or hostname. 
+Note that in IPv6 DHCP, the hardware address may not be
+available, though it normally is for direct-connected clients, or
+clients using DHCP relays which support RFC 6939.
 
-The special option id:* means "ignore any client-id 
+
+For DHCPv4, the  special option id:* means "ignore any client-id 
 and use MAC addresses only." This is useful when a client presents a client-id sometimes 
 but not others.
 
@@ -1033,7 +1035,7 @@ this to set a different printer server for hosts in the class
 "accounts" than for hosts in the class "engineering".
 .TP
 .B \-4, --dhcp-mac=set:<tag>,<MAC address>
-(IPv4 only) Map from a MAC address to a tag. The MAC address may include
+Map from a MAC address to a tag. The MAC address may include
 wildcards. For example
 .B --dhcp-mac=set:3com,01:34:23:*:*:*
 will set the tag "3com" for any host whose MAC address matches the pattern.
@@ -1339,7 +1341,7 @@ every call to the script.
 DNSMASQ_IAID containing the IAID for the lease. If the lease is a
 temporary allocation, this is prefixed to 'T'.
 
-
+DNSMASQ_MAC containing the MAC address of the client, if known.
 
 Note that the supplied hostname, vendorclass and userclass data is
 only  supplied for
diff --git a/src/dhcp-common.c b/src/dhcp-common.c
index 939f25a..7b37daf 100644
--- a/src/dhcp-common.c
+++ b/src/dhcp-common.c
@@ -253,6 +253,110 @@ int match_bytes(struct dhcp_opt *o, unsigned char *p, int len)
   return 0;
 }
 
+int config_has_mac(struct dhcp_config *config, unsigned char *hwaddr, int len, int type)
+{
+  struct hwaddr_config *conf_addr;
+  
+  for (conf_addr = config->hwaddr; conf_addr; conf_addr = conf_addr->next)
+    if (conf_addr->wildcard_mask == 0 &&
+	conf_addr->hwaddr_len == len &&
+	(conf_addr->hwaddr_type == type || conf_addr->hwaddr_type == 0) &&
+	memcmp(conf_addr->hwaddr, hwaddr, len) == 0)
+      return 1;
+  
+  return 0;
+}
+
+static int is_config_in_context(struct dhcp_context *context, struct dhcp_config *config)
+{
+  if (!context) /* called via find_config() from lease_update_from_configs() */
+    return 1; 
+
+  if (!(context->flags & CONTEXT_V6))
+    {
+      if (!(config->flags & CONFIG_ADDR))
+	return 1;
+
+      for (; context; context = context->current)
+	if (is_same_net(config->addr, context->start, context->netmask))
+	  return 1;
+    }
+#ifdef HAVE_DHCP6
+  else 
+    {
+      if (!(config->flags & CONFIG_ADDR6) || (config->flags & CONFIG_WILDCARD))
+	return 1;
+      
+      for (; context; context = context->current)
+	if (is_same_net6(&config->addr6, &context->start6, context->prefix))
+      return 1;
+    }
+#endif
+  
+  return 0;
+}
+
+struct dhcp_config *find_config(struct dhcp_config *configs,
+				struct dhcp_context *context,
+				unsigned char *clid, int clid_len,
+				unsigned char *hwaddr, int hw_len, 
+				int hw_type, char *hostname)
+{
+  int count, new;
+  struct dhcp_config *config, *candidate; 
+  struct hwaddr_config *conf_addr;
+
+  if (clid)
+    for (config = configs; config; config = config->next)
+      if (config->flags & CONFIG_CLID)
+	{
+	  if (config->clid_len == clid_len && 
+	      memcmp(config->clid, clid, clid_len) == 0 &&
+	      is_config_in_context(context, config))
+	    return config;
+	  
+	  /* dhcpcd prefixes ASCII client IDs by zero which is wrong, but we try and
+	     cope with that here */
+	  if (!(context->flags & CONTEXT_V6) && *clid == 0 && config->clid_len == clid_len-1  &&
+	      memcmp(config->clid, clid+1, clid_len-1) == 0 &&
+	      is_config_in_context(context, config))
+	    return config;
+	}
+  
+
+  if (hwaddr)
+    for (config = configs; config; config = config->next)
+      if (config_has_mac(config, hwaddr, hw_len, hw_type) &&
+	  is_config_in_context(context, config))
+	return config;
+  
+  if (hostname && context)
+    for (config = configs; config; config = config->next)
+      if ((config->flags & CONFIG_NAME) && 
+	  hostname_isequal(config->hostname, hostname) &&
+	  is_config_in_context(context, config))
+	return config;
+
+  
+  if (!hwaddr)
+    return NULL;
+
+  /* use match with fewest wildcard octets */
+  for (candidate = NULL, count = 0, config = configs; config; config = config->next)
+    if (is_config_in_context(context, config))
+      for (conf_addr = config->hwaddr; conf_addr; conf_addr = conf_addr->next)
+	if (conf_addr->wildcard_mask != 0 &&
+	    conf_addr->hwaddr_len == hw_len &&	
+	    (conf_addr->hwaddr_type == hw_type || conf_addr->hwaddr_type == 0) &&
+	    (new = memcmp_masked(conf_addr->hwaddr, hwaddr, hw_len, conf_addr->wildcard_mask)) > count)
+	  {
+	      count = new;
+	      candidate = config;
+	  }
+  
+  return candidate;
+}
+
 void dhcp_update_configs(struct dhcp_config *configs)
 {
   /* Some people like to keep all static IP addresses in /etc/hosts.
diff --git a/src/dhcp.c b/src/dhcp.c
index 573de5b..67a82b5 100644
--- a/src/dhcp.c
+++ b/src/dhcp.c
@@ -749,89 +749,6 @@ int address_allocate(struct dhcp_context *context,
   return 0;
 }
 
-static int is_addr_in_context(struct dhcp_context *context, struct dhcp_config *config)
-{
-  if (!context) /* called via find_config() from lease_update_from_configs() */
-    return 1; 
-  if (!(config->flags & CONFIG_ADDR))
-    return 1;
-  for (; context; context = context->current)
-    if (is_same_net(config->addr, context->start, context->netmask))
-      return 1;
-  
-  return 0;
-}
-
-int config_has_mac(struct dhcp_config *config, unsigned char *hwaddr, int len, int type)
-{
-  struct hwaddr_config *conf_addr;
-  
-  for (conf_addr = config->hwaddr; conf_addr; conf_addr = conf_addr->next)
-    if (conf_addr->wildcard_mask == 0 &&
-	conf_addr->hwaddr_len == len &&
-	(conf_addr->hwaddr_type == type || conf_addr->hwaddr_type == 0) &&
-	memcmp(conf_addr->hwaddr, hwaddr, len) == 0)
-      return 1;
-  
-  return 0;
-}
-
-struct dhcp_config *find_config(struct dhcp_config *configs,
-				struct dhcp_context *context,
-				unsigned char *clid, int clid_len,
-				unsigned char *hwaddr, int hw_len, 
-				int hw_type, char *hostname)
-{
-  int count, new;
-  struct dhcp_config *config, *candidate; 
-  struct hwaddr_config *conf_addr;
-
-  if (clid)
-    for (config = configs; config; config = config->next)
-      if (config->flags & CONFIG_CLID)
-	{
-	  if (config->clid_len == clid_len && 
-	      memcmp(config->clid, clid, clid_len) == 0 &&
-	      is_addr_in_context(context, config))
-	    return config;
-	  
-	  /* dhcpcd prefixes ASCII client IDs by zero which is wrong, but we try and
-	     cope with that here */
-	  if (*clid == 0 && config->clid_len == clid_len-1  &&
-	      memcmp(config->clid, clid+1, clid_len-1) == 0 &&
-	      is_addr_in_context(context, config))
-	    return config;
-	}
-  
-
-  for (config = configs; config; config = config->next)
-    if (config_has_mac(config, hwaddr, hw_len, hw_type) &&
-	is_addr_in_context(context, config))
-      return config;
-  
-  if (hostname && context)
-    for (config = configs; config; config = config->next)
-      if ((config->flags & CONFIG_NAME) && 
-	  hostname_isequal(config->hostname, hostname) &&
-	  is_addr_in_context(context, config))
-	return config;
-
-  /* use match with fewest wildcard octets */
-  for (candidate = NULL, count = 0, config = configs; config; config = config->next)
-    if (is_addr_in_context(context, config))
-      for (conf_addr = config->hwaddr; conf_addr; conf_addr = conf_addr->next)
-	if (conf_addr->wildcard_mask != 0 &&
-	    conf_addr->hwaddr_len == hw_len &&	
-	    (conf_addr->hwaddr_type == hw_type || conf_addr->hwaddr_type == 0) &&
-	    (new = memcmp_masked(conf_addr->hwaddr, hwaddr, hw_len, conf_addr->wildcard_mask)) > count)
-	  {
-	    count = new;
-	    candidate = config;
-	  }
-
-  return candidate;
-}
-
 void dhcp_read_ethers(void)
 {
   FILE *f = fopen(ETHERSFILE, "r");
diff --git a/src/dhcp6-protocol.h b/src/dhcp6-protocol.h
index c4eef35..f8e98ec 100644
--- a/src/dhcp6-protocol.h
+++ b/src/dhcp6-protocol.h
@@ -59,6 +59,7 @@
 #define OPTION6_REMOTE_ID       37
 #define OPTION6_SUBSCRIBER_ID   38
 #define OPTION6_FQDN            39
+#define OPTION6_CLIENT_MAC      79
 
 /* replace this with the real number when allocated.
    defining this also enables the relevant code. */ 
diff --git a/src/dhcp6.c b/src/dhcp6.c
index 35bb748..527d797 100644
--- a/src/dhcp6.c
+++ b/src/dhcp6.c
@@ -18,6 +18,8 @@
 
 #ifdef HAVE_DHCP6
 
+#include <netinet/icmp6.h>
+
 struct iface_param {
   struct dhcp_context *current;
   struct dhcp_relay *relay;
@@ -25,10 +27,17 @@ struct iface_param {
   int ind, addr_match;
 };
 
+struct mac_param {
+  struct in6_addr *target;
+  unsigned char mac[DHCP_CHADDR_MAX];
+  unsigned int maclen;
+};
+
+
 static int complete_context6(struct in6_addr *local,  int prefix,
 			     int scope, int if_index, int flags, 
 			     unsigned int preferred, unsigned int valid, void *vparam);
-
+static int find_mac(int family, char *addrp, char *mac, size_t maclen, void *parmv);
 static int make_duid1(int index, unsigned int type, char *mac, size_t maclen, void *parm); 
 
 void dhcp6_init(void)
@@ -90,6 +99,7 @@ void dhcp6_packet(time_t now)
   struct dhcp_context *context;
   struct dhcp_relay *relay;
   struct iface_param parm;
+  struct mac_param mac_param;
   struct cmsghdr *cmptr;
   struct msghdr msg;
   int if_index = 0;
@@ -102,6 +112,7 @@ void dhcp6_packet(time_t now)
   struct ifreq ifr;
   struct iname *tmp;
   unsigned short port;
+  struct in6_addr dst_addr;
 
   msg.msg_control = control_u.control6;
   msg.msg_controllen = sizeof(control_u);
@@ -124,6 +135,7 @@ void dhcp6_packet(time_t now)
 	p.c = CMSG_DATA(cmptr);
         
 	if_index = p.p->ipi6_ifindex;
+	dst_addr = p.p->ipi6_addr;
       }
 
   if (!indextoname(daemon->dhcp6fd, if_index, ifr.ifr_name))
@@ -131,7 +143,8 @@ void dhcp6_packet(time_t now)
 
   if ((port = relay_reply6(&from, sz, ifr.ifr_name)) == 0)
     {
-      
+      int i;
+
       for (tmp = daemon->if_except; tmp; tmp = tmp->next)
 	if (tmp->name && wildcard_match(tmp->name, ifr.ifr_name))
 	  return;
@@ -166,7 +179,48 @@ void dhcp6_packet(time_t now)
       
       if (!iface_enumerate(AF_INET6, &parm, complete_context6))
 	return;
+
+      /* Recieving a packet from a host does not populate the neighbour
+	 cache, so we send a ping to prompt neighbour discovery if we can't 
+	 find the sender. Repeat a few times in case of packet loss. */
       
+      for (i = 0; i < 5; i++)
+	{
+	  struct timespec ts;
+	  struct ping_packet *ping;
+	  struct sockaddr_in6 addr;
+	  
+	  mac_param.target = &from.sin6_addr;
+	  mac_param.maclen = 0;
+	  
+	  iface_enumerate(AF_UNSPEC, &mac_param, find_mac);
+	  
+	  if (mac_param.maclen != 0)
+	    break;
+	 
+	  save_counter(0);
+	  ping = expand(sizeof(struct ping_packet));
+	  ping->type = ICMP6_ECHO_REQUEST;
+	  ping->code = 0;
+	  ping->identifier = 1;
+	  ping->sequence_no = 1;
+            
+	  memset(&addr, 0, sizeof(addr));
+#ifdef HAVE_SOCKADDR_SA_LEN
+	  addr.sin6_len = sizeof(struct sockaddr_in6);
+#endif
+	  addr.sin6_family = AF_INET6;
+	  addr.sin6_port = htons(IPPROTO_ICMPV6);
+	  addr.sin6_addr = from.sin6_addr;
+          
+	  sendto(daemon->icmp6fd, daemon->outpacket.iov_base, save_counter(0), 0,
+		 (struct sockaddr *)&addr,  sizeof(addr));
+	  
+	  ts.tv_sec = 0;
+	  ts.tv_nsec = 100000000; /* 100ms */
+	  nanosleep(&ts, NULL);
+	}
+    
       if (daemon->if_names || daemon->if_addrs)
 	{
 	  
@@ -180,7 +234,15 @@ void dhcp6_packet(time_t now)
       
       if (parm.relay)
 	{
-	  relay_upstream6(parm.relay, sz, &from.sin6_addr, from.sin6_scope_id);
+	  /* Ignore requests sent to the ALL_SERVERS multicast address for relay when
+	     we're listening there for DHCPv6 server reasons. */
+	  struct in6_addr all_servers;
+	  
+	  inet_pton(AF_INET6, ALL_SERVERS, &all_servers);
+	  
+	  if (!IN6_ARE_ADDR_EQUAL(&dst_addr, &all_servers))
+	    relay_upstream6(parm.relay, sz, &from.sin6_addr, from.sin6_scope_id,
+			    mac_param.maclen == 0 ? NULL : &mac_param.mac[0], mac_param.maclen, ARPHRD_ETHER);
 	  return;
 	}
       
@@ -191,7 +253,8 @@ void dhcp6_packet(time_t now)
       lease_prune(NULL, now); /* lose any expired leases */
       
       port = dhcp6_reply(parm.current, if_index, ifr.ifr_name, &parm.fallback, 
-			 sz, IN6_IS_ADDR_MULTICAST(&from.sin6_addr), now);
+			 sz, IN6_IS_ADDR_MULTICAST(&from.sin6_addr), now,
+			 mac_param.maclen == 0 ? NULL : &mac_param.mac[0], mac_param.maclen, ARPHRD_ETHER);
       
       lease_update_file(now);
       lease_update_dns(0);
@@ -210,6 +273,24 @@ void dhcp6_packet(time_t now)
     }
 }
 
+static int find_mac(int family, char *addrp, char *mac, size_t maclen, void *parmv)
+{
+  struct mac_param *parm = parmv;
+  
+  if (family == AF_INET6 && IN6_ARE_ADDR_EQUAL(parm->target, addrp))
+    {
+      if (maclen <= DHCP_CHADDR_MAX)
+	{
+	  parm->maclen = maclen;
+	  memcpy(parm->mac, mac, maclen);
+	}
+      
+      return 0; /* found, abort */
+    }
+  
+  return 1;
+}
+
 static int complete_context6(struct in6_addr *local,  int prefix,
 			     int scope, int if_index, int flags, unsigned int preferred, 
 			     unsigned int valid, void *vparam)
@@ -435,48 +516,6 @@ int config_valid(struct dhcp_config *config, struct dhcp_context *context, struc
   return 0;
 }
 
-static int is_config_in_context6(struct dhcp_context *context, struct dhcp_config *config)
-{
-  if (!(config->flags & CONFIG_ADDR6) || 
-      (config->flags & CONFIG_WILDCARD))
-
-    return 1;
-  
-  for (; context; context = context->current)
-    if (is_same_net6(&config->addr6, &context->start6, context->prefix))
-      return 1;
-      
-  return 0;
-}
-
-
-struct dhcp_config *find_config6(struct dhcp_config *configs,
-				 struct dhcp_context *context,
-				 unsigned char *duid, int duid_len,
-				 char *hostname)
-{
-  struct dhcp_config *config; 
-      
-  if (duid)
-    for (config = configs; config; config = config->next)
-      if (config->flags & CONFIG_CLID)
-	{
-	  if (config->clid_len == duid_len && 
-	      memcmp(config->clid, duid, duid_len) == 0 &&
-	      is_config_in_context6(context, config))
-	    return config;
-	}
-    
-  if (hostname && context)
-    for (config = configs; config; config = config->next)
-      if ((config->flags & CONFIG_NAME) && 
-          hostname_isequal(config->hostname, hostname) &&
-          is_config_in_context6(context, config))
-        return config;
-
-  return NULL;
-}
-
 void make_duid(time_t now)
 {
   if (daemon->duid_config)
diff --git a/src/dnsmasq.c b/src/dnsmasq.c
index 5c65f81..8dcb1d4 100644
--- a/src/dnsmasq.c
+++ b/src/dnsmasq.c
@@ -202,7 +202,7 @@ int main (int argc, char **argv)
     dhcp_init();
   
 #  ifdef HAVE_DHCP6
-  if (daemon->doing_ra)
+  if (daemon->doing_ra || daemon->doing_dhcp6 || daemon->relay6)
     ra_init(now);
   
   if (daemon->doing_dhcp6 || daemon->relay6)
diff --git a/src/dnsmasq.h b/src/dnsmasq.h
index b1a1644..2d9a3a5 100644
--- a/src/dnsmasq.h
+++ b/src/dnsmasq.h
@@ -539,13 +539,15 @@ struct dhcp_lease {
 #ifdef HAVE_BROKEN_RTC
   unsigned int length;
 #endif
-  int hwaddr_len, hwaddr_type; /* hw_type used for iaid in v6 */
-  unsigned char hwaddr[DHCP_CHADDR_MAX]; /* also IPv6 address */
+  int hwaddr_len, hwaddr_type;
+  unsigned char hwaddr[DHCP_CHADDR_MAX]; 
   struct in_addr addr, override, giaddr;
   unsigned char *extradata;
   unsigned int extradata_len, extradata_size;
   int last_interface;
 #ifdef HAVE_DHCP6
+  struct in6_addr addr6;
+  int iaid;
   struct slaac_address {
     struct in6_addr addr, local;
     time_t ping_time;
@@ -717,24 +719,25 @@ struct dhcp_context {
   struct dhcp_context *next, *current;
 };
 
-#define CONTEXT_STATIC         1
-#define CONTEXT_NETMASK        2
-#define CONTEXT_BRDCAST        4
-#define CONTEXT_PROXY          8
-#define CONTEXT_RA_ONLY       16
-#define CONTEXT_RA_DONE       32
-#define CONTEXT_RA_NAME       64
-#define CONTEXT_RA_STATELESS 128
-#define CONTEXT_DHCP         256
-#define CONTEXT_DEPRECATE    512
-#define CONTEXT_TEMPLATE    1024    /* create contexts using addresses */
-#define CONTEXT_CONSTRUCTED 2048
-#define CONTEXT_GC          4096
-#define CONTEXT_RA          8192
-#define CONTEXT_CONF_USED  16384
-#define CONTEXT_USED       32768
-#define CONTEXT_NOAUTH     65536
-#define CONTEXT_OLD       131072
+#define CONTEXT_STATIC         (1u<<0)
+#define CONTEXT_NETMASK        (1u<<1)
+#define CONTEXT_BRDCAST        (1u<<2)
+#define CONTEXT_PROXY          (1u<<3)
+#define CONTEXT_RA_ONLY        (1u<<4)
+#define CONTEXT_RA_DONE        (1u<<5)
+#define CONTEXT_RA_NAME        (1u<<6)
+#define CONTEXT_RA_STATELESS   (1u<<7)
+#define CONTEXT_DHCP           (1u<<8)
+#define CONTEXT_DEPRECATE      (1u<<9)
+#define CONTEXT_TEMPLATE       (1u<<10)    /* create contexts using addresses */
+#define CONTEXT_CONSTRUCTED    (1u<<11)
+#define CONTEXT_GC             (1u<<12)
+#define CONTEXT_RA             (1u<<13)
+#define CONTEXT_CONF_USED      (1u<<14)
+#define CONTEXT_USED           (1u<<15)
+#define CONTEXT_NOAUTH         (1u<<16)
+#define CONTEXT_OLD            (1u<<17)
+#define CONTEXT_V6             (1u<<18)
 
 
 struct ping_result {
@@ -1072,12 +1075,6 @@ struct dhcp_context *narrow_context(struct dhcp_context *context,
 int address_allocate(struct dhcp_context *context,
 		     struct in_addr *addrp, unsigned char *hwaddr, int hw_len,
 		     struct dhcp_netid *netids, time_t now);
-int config_has_mac(struct dhcp_config *config, unsigned char *hwaddr, int len, int type);
-struct dhcp_config *find_config(struct dhcp_config *configs,
-				struct dhcp_context *context,
-				unsigned char *clid, int clid_len,
-				unsigned char *hwaddr, int hw_len, 
-				int hw_type, char *hostname);
 void dhcp_read_ethers(void);
 struct dhcp_config *config_find_by_address(struct dhcp_config *configs, struct in_addr addr);
 char *host_from_dns(struct in_addr addr);
@@ -1099,6 +1096,7 @@ struct dhcp_lease *lease6_find_by_addr(struct in6_addr *net, int prefix, u64 add
 u64 lease_find_max_addr6(struct dhcp_context *context);
 void lease_ping_reply(struct in6_addr *sender, unsigned char *packet, char *interface);
 void lease_update_slaac(time_t now);
+void lease_set_iaid(struct dhcp_lease *lease, int iaid);
 #endif
 void lease_set_hwaddr(struct dhcp_lease *lease, unsigned char *hwaddr,
 		      unsigned char *clid, int hw_len, int hw_type, int clid_len, time_t now, int force);
@@ -1210,10 +1208,6 @@ struct dhcp_context *address6_valid(struct dhcp_context *context,
 				    struct in6_addr *taddr,
 				    struct dhcp_netid *netids,
 				    int plain_range);
-struct dhcp_config *find_config6(struct dhcp_config *configs,
-				 struct dhcp_context *context,
-				 unsigned char *duid, int duid_len,
-				 char *hostname);
 struct dhcp_config *config_find_by_address6(struct dhcp_config *configs, struct in6_addr *net, 
 					    int prefix, u64 addr);
 void make_duid(time_t now);
@@ -1223,8 +1217,10 @@ void dhcp_construct_contexts(time_t now);
 /* rfc3315.c */
 #ifdef HAVE_DHCP6
 unsigned short dhcp6_reply(struct dhcp_context *context, int interface, char *iface_name,  
-			   struct in6_addr *fallback, size_t sz, int is_multicast, time_t now);
-void relay_upstream6(struct dhcp_relay *relay, ssize_t sz, struct in6_addr *peer_address, u32 scope_id);
+			   struct in6_addr *fallback, size_t sz, int is_multicast, time_t now,
+			   unsigned char *mac, unsigned int mac_len, unsigned int mac_type);
+void relay_upstream6(struct dhcp_relay *relay, ssize_t sz, struct in6_addr *peer_address, u32 scope_id,
+		     unsigned char *mac, unsigned int mac_len, unsigned int mac_type);
 
 unsigned short relay_reply6( struct sockaddr_in6 *peer, ssize_t sz, char *arrival_interface);
 #endif
@@ -1246,6 +1242,12 @@ int lookup_dhcp_opt(int prot, char *name);
 int lookup_dhcp_len(int prot, int val);
 char *option_string(int prot, unsigned int opt, unsigned char *val, 
 		    int opt_len, char *buf, int buf_len);
+struct dhcp_config *find_config(struct dhcp_config *configs,
+				struct dhcp_context *context,
+				unsigned char *clid, int clid_len,
+				unsigned char *hwaddr, int hw_len, 
+				int hw_type, char *hostname);
+int config_has_mac(struct dhcp_config *config, unsigned char *hwaddr, int len, int type);
 #ifdef HAVE_LINUX_NETWORK
 void bindtodevice(int fd);
 #endif
diff --git a/src/helper.c b/src/helper.c
index ab691b7..65410f5 100644
--- a/src/helper.c
+++ b/src/helper.c
@@ -60,10 +60,13 @@ struct script_data
   unsigned int length;
 #else
   time_t expires;
+#endif
+#ifdef HAVE_DHCP6
+  struct in6_addr addr6;
+  int iaid, vendorclass_count;
 #endif
   unsigned char hwaddr[DHCP_CHADDR_MAX];
   char interface[IF_NAMESIZE];
-
 };
 
 static struct script_data *buf = NULL;
@@ -215,20 +218,17 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
 	continue;
 
       	
-      if (!is6)
+      /* stringify MAC into dhcp_buff */
+      p = daemon->dhcp_buff;
+      if (data.hwaddr_type != ARPHRD_ETHER || data.hwaddr_len == 0) 
+	p += sprintf(p, "%.2x-", data.hwaddr_type);
+      for (i = 0; (i < data.hwaddr_len) && (i < DHCP_CHADDR_MAX); i++)
 	{
-	  /* stringify MAC into dhcp_buff */
-	  p = daemon->dhcp_buff;
-	  if (data.hwaddr_type != ARPHRD_ETHER || data.hwaddr_len == 0) 
-	    p += sprintf(p, "%.2x-", data.hwaddr_type);
-	  for (i = 0; (i < data.hwaddr_len) && (i < DHCP_CHADDR_MAX); i++)
-	    {
-	      p += sprintf(p, "%.2x", data.hwaddr[i]);
-	      if (i != data.hwaddr_len - 1)
-		p += sprintf(p, ":");
-	    }
+	  p += sprintf(p, "%.2x", data.hwaddr[i]);
+	  if (i != data.hwaddr_len - 1)
+	    p += sprintf(p, ":");
 	}
-       
+      
       /* supplied data may just exceed normal buffer (unlikely) */
       if ((data.hostname_len + data.ed_len + data.clid_len) > MAXDNAME && 
 	  !(alloc_buff = buf = malloc(data.hostname_len + data.ed_len + data.clid_len)))
@@ -239,32 +239,25 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
 	continue;
 
       /* CLID into packet */
-      if (!is6)
-	for (p = daemon->packet, i = 0; i < data.clid_len; i++)
-	  {
-	    p += sprintf(p, "%.2x", buf[i]);
-	    if (i != data.clid_len - 1) 
+      for (p = daemon->packet, i = 0; i < data.clid_len; i++)
+	{
+	  p += sprintf(p, "%.2x", buf[i]);
+	  if (i != data.clid_len - 1) 
 	      p += sprintf(p, ":");
-	  }
+	}
+
 #ifdef HAVE_DHCP6
-      else
+      if (is6)
 	{
 	  /* or IAID and server DUID for IPv6 */
-	  sprintf(daemon->dhcp_buff3, "%s%u", data.flags & LEASE_TA ? "T" : "", data.hwaddr_type);	
-	  for (p = daemon->packet, i = 0; i < daemon->duid_len; i++)
+	  sprintf(daemon->dhcp_buff3, "%s%u", data.flags & LEASE_TA ? "T" : "", data.iaid);	
+	  for (p = daemon->dhcp_packet.iov_base, i = 0; i < daemon->duid_len; i++)
 	    {
 	      p += sprintf(p, "%.2x", daemon->duid[i]);
 	      if (i != daemon->duid_len - 1) 
 		p += sprintf(p, ":");
 	    }
 
-	  /* duid not MAC for IPv6 */
-	  for (p = daemon->dhcp_buff, i = 0; i < data.clid_len; i++)
-	    {
-	      p += sprintf(p, "%.2x", buf[i]);
-	      if (i != data.clid_len - 1) 
-		p += sprintf(p, ":");
-	    } 
 	}
 #endif
 
@@ -293,7 +286,7 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
 	inet_ntop(AF_INET, &data.addr, daemon->addrbuff, ADDRSTRLEN);
 #ifdef HAVE_DHCP6
       else
-	inet_ntop(AF_INET6, &data.hwaddr, daemon->addrbuff, ADDRSTRLEN);
+	inet_ntop(AF_INET6, &data.addr6, daemon->addrbuff, ADDRSTRLEN);
 #endif
 
       /* file length */
@@ -329,9 +322,9 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
 	      
 	      if (is6)
 		{
-		  lua_pushstring(lua, daemon->dhcp_buff);
-		  lua_setfield(lua, -2, "client_duid");
 		  lua_pushstring(lua, daemon->packet);
+		  lua_setfield(lua, -2, "client_duid");
+		  lua_pushstring(lua, daemon->dhcp_packet.iov_base);
 		  lua_setfield(lua, -2, "server_duid");
 		  lua_pushstring(lua, daemon->dhcp_buff3);
 		  lua_setfield(lua, -2, "iaid");
@@ -375,12 +368,16 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
 	      if (!is6)
 		buf = grab_extradata_lua(buf, end, "vendor_class");
 #ifdef HAVE_DHCP6
-	      else
-		for (i = 0; i < data.hwaddr_len; i++)
-		  {
-		    sprintf(daemon->dhcp_buff2, "vendor_class%i", i);
-		    buf = grab_extradata_lua(buf, end, daemon->dhcp_buff2);
-		  }
+	      else  if (data.vendorclass_count != 0)
+		{
+		  sprintf(daemon->dhcp_buff2, "vendor_class_id");
+		  buf = grab_extradata_lua(buf, end, daemon->dhcp_buff2);
+		  for (i = 0; i < data.vendorclass_count - 1; i++)
+		    {
+		      sprintf(daemon->dhcp_buff2, "vendor_class%i", i);
+		      buf = grab_extradata_lua(buf, end, daemon->dhcp_buff2);
+		    }
+		}
 #endif
 	      
 	      buf = grab_extradata_lua(buf, end, "supplied_hostname");
@@ -423,7 +420,7 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
 		  lua_setfield(lua, -2, "old_hostname");
 		}
 	      
-	      if (!is6)
+	      if (!is6 || data.hwaddr_len != 0)
 		{
 		  lua_pushstring(lua, daemon->dhcp_buff);
 		  lua_setfield(lua, -2, "mac_address");
@@ -476,11 +473,15 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
       
       if (data.action != ACTION_TFTP)
 	{
+#ifdef HAVE_DHCP6
 	  if (is6)
 	    {
 	      my_setenv("DNSMASQ_IAID", daemon->dhcp_buff3, &err);
-	      my_setenv("DNSMASQ_SERVER_DUID", daemon->packet, &err);
+	      my_setenv("DNSMASQ_SERVER_DUID", daemon->dhcp_packet.iov_base, &err); 
+	      if (data.hwaddr_len != 0)
+		my_setenv("DNSMASQ_MAC", daemon->dhcp_buff, &err);
 	    }
+#endif
 	  
 	  if (!is6 && data.clid_len != 0)
 	    my_setenv("DNSMASQ_CLIENT_ID", daemon->packet, &err);
@@ -507,10 +508,10 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
 #ifdef HAVE_DHCP6
 	  else
 	    {
-	      if (data.hwaddr_len != 0)
+	      if (data.vendorclass_count != 0)
 		{
 		  buf = grab_extradata(buf, end, "DNSMASQ_VENDOR_CLASS_ID", &err);
-		  for (i = 0; i < data.hwaddr_len - 1; i++)
+		  for (i = 0; i < data.vendorclass_count - 1; i++)
 		    {
 		      sprintf(daemon->dhcp_buff2, "DNSMASQ_VENDOR_CLASS%i", i);
 		      buf = grab_extradata(buf, end, daemon->dhcp_buff2, &err);
@@ -570,7 +571,8 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
 	{
 	  execl(daemon->lease_change_command, 
 		p ? p+1 : daemon->lease_change_command,
-		action_str, daemon->dhcp_buff, daemon->addrbuff, hostname, (char*)NULL);
+		action_str, is6 ? daemon->packet : daemon->dhcp_buff, 
+		daemon->addrbuff, hostname, (char*)NULL);
 	  err = errno;
 	}
       /* failed, send event so the main process logs the problem */
@@ -656,8 +658,6 @@ void queue_script(int action, struct dhcp_lease *lease, char *hostname, time_t n
   unsigned int hostname_len = 0, clid_len = 0, ed_len = 0;
   int fd = daemon->dhcpfd;
 #ifdef HAVE_DHCP6 
-  int is6 = !!(lease->flags & (LEASE_TA | LEASE_NA));
-
   if (!daemon->dhcp)
     fd = daemon->dhcp6fd;
 #endif
@@ -678,11 +678,11 @@ void queue_script(int action, struct dhcp_lease *lease, char *hostname, time_t n
   buf->action = action;
   buf->flags = lease->flags;
 #ifdef HAVE_DHCP6 
-  if (is6)
-    buf->hwaddr_len = lease->vendorclass_count;
-  else
+  buf->vendorclass_count = lease->vendorclass_count;
+  buf->addr6 = lease->addr6;
+  buf->iaid = lease->iaid;
 #endif
-    buf->hwaddr_len = lease->hwaddr_len;
+  buf->hwaddr_len = lease->hwaddr_len;
   buf->hwaddr_type = lease->hwaddr_type;
   buf->clid_len = clid_len;
   buf->ed_len = ed_len;
diff --git a/src/lease.c b/src/lease.c
index b85cf57..7033370 100644
--- a/src/lease.c
+++ b/src/lease.c
@@ -108,6 +108,7 @@ void lease_init(time_t now)
 	  {
 	    char *s = daemon->dhcp_buff2;
 	    int lease_type = LEASE_NA;
+	    int iaid;
 
 	    if (s[0] == 'T')
 	      {
@@ -115,12 +116,12 @@ void lease_init(time_t now)
 		s++;
 	      }
 	    
-	    hw_type = strtoul(s, NULL, 10);
+	    iaid = strtoul(s, NULL, 10);
 	    
 	    if ((lease = lease6_allocate(&addr.addr.addr6, lease_type)))
 	      {
-		lease_set_hwaddr(lease, NULL, (unsigned char *)daemon->packet, 0, hw_type, clid_len, now, 0);
-		
+		lease_set_hwaddr(lease, NULL, (unsigned char *)daemon->packet, 0, 0, clid_len, now, 0);
+		lease_set_iaid(lease, iaid);
 		if (strcmp(daemon->dhcp_buff, "*") !=  0)
 		  lease_set_hostname(lease, daemon->dhcp_buff, 0, get_domain6((struct in6_addr *)lease->hwaddr), NULL);
 	      }
@@ -187,10 +188,12 @@ void lease_update_from_configs(void)
   char *name;
   
   for (lease = leases; lease; lease = lease->next)
-    if ((config = find_config(daemon->dhcp_conf, NULL, lease->clid, lease->clid_len, 
-			      lease->hwaddr, lease->hwaddr_len, lease->hwaddr_type, NULL)) && 
-	(config->flags & CONFIG_NAME) &&
-	(!(config->flags & CONFIG_ADDR) || config->addr.s_addr == lease->addr.s_addr))
+    if (lease->flags & (LEASE_TA | LEASE_NA))
+      continue;
+    else if ((config = find_config(daemon->dhcp_conf, NULL, lease->clid, lease->clid_len, 
+				   lease->hwaddr, lease->hwaddr_len, lease->hwaddr_type, NULL)) && 
+	     (config->flags & CONFIG_NAME) &&
+	     (!(config->flags & CONFIG_ADDR) || config->addr.s_addr == lease->addr.s_addr))
       lease_set_hostname(lease, config->hostname, 1, get_domain(lease->addr), NULL);
     else if ((name = host_from_dns(lease->addr)))
       lease_set_hostname(lease, name, 1, get_domain(lease->addr), NULL); /* updates auth flag only */
@@ -277,10 +280,10 @@ void lease_update_file(time_t now)
 	      ourprintf(&err, "%lu ", (unsigned long)lease->expires);
 #endif
     
-	      inet_ntop(AF_INET6, lease->hwaddr, daemon->addrbuff, ADDRSTRLEN);
+	      inet_ntop(AF_INET6, &lease->addr6, daemon->addrbuff, ADDRSTRLEN);
 	 
 	      ourprintf(&err, "%s%u %s ", (lease->flags & LEASE_TA) ? "T" : "",
-			lease->hwaddr_type, daemon->addrbuff);
+			lease->iaid, daemon->addrbuff);
 	      ourprintf(&err, "%s ", lease->hostname ? lease->hostname : "*");
 	      
 	      if (lease->clid && lease->clid_len != 0)
@@ -376,7 +379,7 @@ static int find_interface_v6(struct in6_addr *local,  int prefix,
 
   for (lease = leases; lease; lease = lease->next)
     if ((lease->flags & (LEASE_TA | LEASE_NA)))
-      if (is_same_net6(local, (struct in6_addr *)&lease->hwaddr, prefix))
+      if (is_same_net6(local, &lease->addr6, prefix))
 	lease_set_interface(lease, if_index, *((time_t *)vparam));
   
   return 1;
@@ -463,12 +466,12 @@ void lease_update_dns(int force)
 	  
 	  if (lease->fqdn)
 	    cache_add_dhcp_entry(lease->fqdn, prot, 
-				 prot == AF_INET ? (struct all_addr *)&lease->addr : (struct all_addr *)&lease->hwaddr,
+				 prot == AF_INET ? (struct all_addr *)&lease->addr : (struct all_addr *)&lease->addr6,
 				 lease->expires);
 	     
 	  if (!option_bool(OPT_DHCP_FQDN) && lease->hostname)
 	    cache_add_dhcp_entry(lease->hostname, prot, 
-				 prot == AF_INET ? (struct all_addr *)&lease->addr : (struct all_addr *)&lease->hwaddr, 
+				 prot == AF_INET ? (struct all_addr *)&lease->addr : (struct all_addr *)&lease->addr6, 
 				 lease->expires);
 	}
       
@@ -564,10 +567,10 @@ struct dhcp_lease *lease6_find(unsigned char *clid, int clid_len,
   
   for (lease = leases; lease; lease = lease->next)
     {
-      if (!(lease->flags & lease_type) || lease->hwaddr_type != iaid)
+      if (!(lease->flags & lease_type) || lease->iaid != iaid)
 	continue;
 
-      if (memcmp(lease->hwaddr, addr, IN6ADDRSZ) != 0)
+      if (!IN6_ARE_ADDR_EQUAL(&lease->addr6, addr))
 	continue;
       
       if ((clid_len != lease->clid_len ||
@@ -604,7 +607,7 @@ struct dhcp_lease *lease6_find_by_client(struct dhcp_lease *first, int lease_typ
       if (lease->flags & LEASE_USED)
 	continue;
 
-      if (!(lease->flags & lease_type) || lease->hwaddr_type != iaid)
+      if (!(lease->flags & lease_type) || lease->iaid != iaid)
 	continue;
  
       if ((clid_len != lease->clid_len ||
@@ -626,8 +629,8 @@ struct dhcp_lease *lease6_find_by_addr(struct in6_addr *net, int prefix, u64 add
       if (!(lease->flags & (LEASE_TA | LEASE_NA)))
 	continue;
       
-      if (is_same_net6((struct in6_addr *)lease->hwaddr, net, prefix) &&
-	  (prefix == 128 || addr6part((struct in6_addr *)lease->hwaddr) == addr))
+      if (is_same_net6(&lease->addr6, net, prefix) &&
+	  (prefix == 128 || addr6part(&lease->addr6) == addr))
 	return lease;
     }
   
@@ -646,11 +649,11 @@ u64 lease_find_max_addr6(struct dhcp_context *context)
 	if (!(lease->flags & (LEASE_TA | LEASE_NA)))
 	  continue;
 
-	if (is_same_net6((struct in6_addr *)lease->hwaddr, &context->start6, 64) &&
-	    addr6part((struct in6_addr *)lease->hwaddr) > addr6part(&context->start6) &&
-	    addr6part((struct in6_addr *)lease->hwaddr) <= addr6part(&context->end6) &&
-	    addr6part((struct in6_addr *)lease->hwaddr) > addr)
-	  addr = addr6part((struct in6_addr *)lease->hwaddr);
+	if (is_same_net6(&lease->addr6, &context->start6, 64) &&
+	    addr6part(&lease->addr6) > addr6part(&context->start6) &&
+	    addr6part(&lease->addr6) <= addr6part(&context->end6) &&
+	    addr6part(&lease->addr6) > addr)
+	  addr = addr6part(&lease->addr6);
       }
   
   return addr;
@@ -692,6 +695,7 @@ static struct dhcp_lease *lease_allocate(void)
 #ifdef HAVE_BROKEN_RTC
   lease->length = 0xffffffff; /* illegal value */
 #endif
+  lease->hwaddr_len = 256; /* illegal value */
   lease->next = leases;
   leases = lease;
   
@@ -705,11 +709,8 @@ struct dhcp_lease *lease4_allocate(struct in_addr addr)
 {
   struct dhcp_lease *lease = lease_allocate();
   if (lease)
-    {
-      lease->addr = addr;
-      lease->hwaddr_len = 256; /* illegal value */
-    }
-
+    lease->addr = addr;
+  
   return lease;
 }
 
@@ -720,8 +721,9 @@ struct dhcp_lease *lease6_allocate(struct in6_addr *addrp, int lease_type)
 
   if (lease)
     {
-      memcpy(lease->hwaddr, addrp, sizeof(*addrp)) ;
+      lease->addr6 = *addrp;
       lease->flags |= lease_type;
+      lease->iaid = 0;
     }
 
   return lease;
@@ -758,6 +760,17 @@ void lease_set_expires(struct dhcp_lease *lease, unsigned int len, time_t now)
 #endif
 } 
 
+#ifdef HAVE_DHCP6
+void lease_set_iaid(struct dhcp_lease *lease, int iaid)
+{
+  if (lease->iaid != iaid)
+    {
+      lease->iaid = iaid;
+      lease->flags |= LEASE_CHANGED;
+    }
+}
+#endif
+
 void lease_set_hwaddr(struct dhcp_lease *lease, unsigned char *hwaddr,
 		      unsigned char *clid, int hw_len, int hw_type, int clid_len, 
 		      time_t now, int force)
@@ -779,9 +792,6 @@ void lease_set_hwaddr(struct dhcp_lease *lease, unsigned char *hwaddr,
       lease->hwaddr_type = hw_type;
       lease->flags |= LEASE_CHANGED;
       file_dirty = 1; /* run script on change */
-#ifdef HAVE_DHCP6
-      change = 1;
-#endif
     }
 
   /* only update clid when one is available, stops packets
diff --git a/src/network.c b/src/network.c
index 8e62538..712d7ee 100644
--- a/src/network.c
+++ b/src/network.c
@@ -115,7 +115,9 @@ int iface_check(int family, struct all_addr *addr, char *name, int *auth)
   int ret = 1, match_addr = 0;
 
   /* Note: have to check all and not bail out early, so that we set the
-     "used" flags. */
+     "used" flags.
+
+     May be called with family == AF_LOCALto check interface by name only. */
   
   if (auth)
     *auth = 0;
diff --git a/src/option.c b/src/option.c
index 74f3110..eb5f413 100644
--- a/src/option.c
+++ b/src/option.c
@@ -2404,6 +2404,7 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 #ifdef HAVE_DHCP6
 	else if (inet_pton(AF_INET6, a[0], &new->start6))
 	  {
+	    new->flags |= CONTEXT_V6; 
 	    new->prefix = 64; /* default */
 	    new->end6 = new->start6;
 	    new->next = daemon->dhcp6;
diff --git a/src/radv.c b/src/radv.c
index 32dc60d..d2b3977 100644
--- a/src/radv.c
+++ b/src/radv.c
@@ -70,10 +70,15 @@ void ra_init(time_t now)
     if ((context->flags & CONTEXT_RA_NAME))
       break;
   
+  /* Need ICMP6 socket for transmission for DHCPv6 even when not doing RA. */
+
   ICMP6_FILTER_SETBLOCKALL(&filter);
-  ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filter);
-  if (context)
-    ICMP6_FILTER_SETPASS(ICMP6_ECHO_REPLY, &filter);
+  if (daemon->doing_ra)
+    {
+      ICMP6_FILTER_SETPASS(ND_ROUTER_SOLICIT, &filter);
+      if (context)
+	ICMP6_FILTER_SETPASS(ICMP6_ECHO_REPLY, &filter);
+    }
   
   if ((fd = socket(PF_INET6, SOCK_RAW, IPPROTO_ICMPV6)) == -1 ||
       getsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &hop_limit, &len) ||
@@ -89,7 +94,8 @@ void ra_init(time_t now)
   
    daemon->icmp6fd = fd;
    
-   ra_start_unsolicted(now, NULL);
+   if (daemon->doing_ra)
+     ra_start_unsolicted(now, NULL);
 }
 
 void ra_start_unsolicted(time_t now, struct dhcp_context *context)
diff --git a/src/rfc3315.c b/src/rfc3315.c
index 12df5cf..05e70ae 100644
--- a/src/rfc3315.c
+++ b/src/rfc3315.c
@@ -29,15 +29,19 @@ struct state {
   char *iface_name;
   void *packet_options, *end;
   struct dhcp_netid *tags, *context_tags;
+  unsigned char *mac;
+  unsigned int mac_len, mac_type;
 #ifdef OPTION6_PREFIX_CLASS
   struct prefix_class *send_prefix_class;
 #endif
 };
 
 static int dhcp6_maybe_relay(struct in6_addr *link_address, struct dhcp_netid **relay_tagsp, struct dhcp_context *context, 
-			     int interface, char *iface_name, struct in6_addr *fallback, void *inbuff, size_t sz, int is_unicast, time_t now);
+			     int interface, char *iface_name, struct in6_addr *fallback, void *inbuff, size_t sz, int is_unicast, time_t now,
+			     unsigned char *mac, unsigned int mac_len, unsigned int mac_type);
 static int dhcp6_no_relay(int msg_type,  struct in6_addr *link_address, struct dhcp_netid *tags, struct dhcp_context *context, 
-			  int interface, char *iface_name, struct in6_addr *fallback, void *inbuff, size_t sz, int is_unicast, time_t now);
+			  int interface, char *iface_name, struct in6_addr *fallback, void *inbuff, size_t sz, int is_unicast, time_t now,
+			  unsigned int mac_len, unsigned int mac_type, unsigned char *mac);
 static void log6_opts(int nest, unsigned int xid, void *start_opts, void *end_opts);
 static void log6_packet(struct state *state, char *type, struct in6_addr *addr, char *string);
 
@@ -68,7 +72,8 @@ static void calculate_times(struct dhcp_context *context, unsigned int *min_time
 
 
 unsigned short dhcp6_reply(struct dhcp_context *context, int interface, char *iface_name,
-			   struct in6_addr *fallback, size_t sz, int is_unicast, time_t now)
+			   struct in6_addr *fallback, size_t sz, int is_unicast, time_t now,
+			   unsigned char *mac, unsigned int mac_len, unsigned int mac_type)
 {
   struct dhcp_netid *relay_tags = NULL;
   struct dhcp_vendor *vendor;
@@ -85,7 +90,9 @@ unsigned short dhcp6_reply(struct dhcp_context *context, int interface, char *if
   
   save_counter(0);
   
-  if (dhcp6_maybe_relay(NULL, &relay_tags, context, interface, iface_name, fallback, daemon->dhcp_packet.iov_base, sz, is_unicast, now))
+  if (dhcp6_maybe_relay(NULL, &relay_tags, context, interface, iface_name, 
+			fallback, daemon->dhcp_packet.iov_base, sz, is_unicast, now,
+			mac, mac_len, mac_type))
     return msg_type == DHCP6RELAYFORW ? DHCPV6_SERVER_PORT : DHCPV6_CLIENT_PORT;
 
   return 0;
@@ -93,7 +100,8 @@ unsigned short dhcp6_reply(struct dhcp_context *context, int interface, char *if
 
 /* This cost me blood to write, it will probably cost you blood to understand - srk. */
 static int dhcp6_maybe_relay(struct in6_addr *link_address, struct dhcp_netid **relay_tagsp, struct dhcp_context *context,
-			     int interface, char *iface_name, struct in6_addr *fallback, void *inbuff, size_t sz, int is_unicast, time_t now)
+			     int interface, char *iface_name, struct in6_addr *fallback, void *inbuff, size_t sz, int is_unicast, time_t now,
+			     unsigned char *mac, unsigned int mac_len, unsigned int mac_type)
 {
   void *end = inbuff + sz;
   void *opts = inbuff + 34;
@@ -146,7 +154,8 @@ static int dhcp6_maybe_relay(struct in6_addr *link_address, struct dhcp_netid **
 	  return 0;
 	}
 
-      return dhcp6_no_relay(msg_type, link_address, *relay_tagsp, context, interface, iface_name, fallback, inbuff, sz, is_unicast, now);
+      return dhcp6_no_relay(msg_type, link_address, *relay_tagsp, context, interface, iface_name, fallback, inbuff, 
+			    sz, is_unicast, now, mac_len, mac_type, mac);
     }
 
   /* must have at least msg_type+hopcount+link_address+peer_address+minimal size option
@@ -182,6 +191,14 @@ static int dhcp6_maybe_relay(struct in6_addr *link_address, struct dhcp_netid **
 	}
     }
   
+  /* RFC-6939 */
+  if ((opt = opt6_find(opts, end, OPTION6_CLIENT_MAC, 3)))
+    {
+      mac = opt6_ptr(opt, 2);
+      mac_type = opt6_uint(opt, 0, 2);
+      mac_len = opt6_len(opt) - 2;
+    }
+  
   for (opt = opts; opt; opt = opt6_next(opt, end))
     {
       int o = new_opt6(opt6_type(opt));
@@ -192,10 +209,12 @@ static int dhcp6_maybe_relay(struct in6_addr *link_address, struct dhcp_netid **
 	  memcpy(&link_address, inbuff + 2, IN6ADDRSZ); 
 	  /* Not, zero is_unicast since that is now known to refer to the 
 	     relayed packet, not the original sent by the client */
-	  if (!dhcp6_maybe_relay(&link_address, relay_tagsp, context, interface, iface_name, fallback, opt6_ptr(opt, 0), opt6_len(opt), 0, now))
+	  if (!dhcp6_maybe_relay(&link_address, relay_tagsp, context, interface, iface_name, fallback, 
+				 opt6_ptr(opt, 0), opt6_len(opt), 0, now,
+				 mac, mac_len, mac_type))
 	    return 0;
 	}
-      else
+      else if (opt6_type(opt) != OPTION6_CLIENT_MAC)
 	put_opt6(opt6_ptr(opt, 0), opt6_len(opt));
       end_opt6(o);	    
     }
@@ -204,7 +223,8 @@ static int dhcp6_maybe_relay(struct in6_addr *link_address, struct dhcp_netid **
 }
 
 static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dhcp_netid *tags, struct dhcp_context *context, 
-			  int interface, char *iface_name, struct in6_addr *fallback, void *inbuff, size_t sz, int is_unicast, time_t now)
+			  int interface, char *iface_name, struct in6_addr *fallback, void *inbuff, size_t sz, int is_unicast, time_t now,
+			  unsigned int mac_len, unsigned int mac_type, unsigned char *mac)
 {
   void *opt;
   int i, o, o1, start_opts;
@@ -215,6 +235,7 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
   unsigned char *outmsgtypep;
   struct dhcp_vendor *vendor;
   struct dhcp_context *context_tmp;
+  struct dhcp_mac *mac_opt;
   unsigned int ignore = 0;
   struct state state;
 #ifdef OPTION6_PREFIX_CLASS
@@ -239,6 +260,9 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
   state.client_hostname = NULL;
   state.iface_name = iface_name;
   state.fqdn_flags = 0x01; /* default to send if we recieve no FQDN option */
+  state.mac = mac;
+  state.mac_len = mac_len;
+  state.mac_type = mac_type;
 #ifdef OPTION6_PREFIX_CLASS
   state.send_prefix_class = NULL;
 #endif
@@ -393,6 +417,16 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
 	  state.tags = opt_cfg->netid;
 	}
     }
+
+  if (mac_len != 0)
+    for (mac_opt = daemon->dhcp_macs; mac_opt; mac_opt = mac_opt->next)
+      if ((unsigned)mac_opt->hwaddr_len == mac_len &&
+	  ((unsigned)mac_opt->hwaddr_type == mac_type || mac_opt->hwaddr_type == 0) &&
+	  memcmp_masked(mac_opt->hwaddr, mac, mac_len, mac_opt->mask))
+	{
+	  mac_opt->netid.next = state.tags;
+	  state.tags = &mac_opt->netid;
+	}
   
   if ((opt = opt6_find(state.packet_options, state.end, OPTION6_FQDN, 1)))
     {
@@ -436,7 +470,7 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
   
   if (state.clid)
     {
-      config = find_config6(daemon->dhcp_conf, context, state.clid, state.clid_len, NULL);
+      config = find_config(daemon->dhcp_conf, context, state.clid, state.clid_len, mac, mac_len, mac_type, NULL);
       
       if (have_config(config, CONFIG_NAME))
 	{
@@ -456,7 +490,7 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
 		  /* Search again now we have a hostname. 
 		     Only accept configs without CLID here, (it won't match)
 		     to avoid impersonation by name. */
-		  struct dhcp_config *new = find_config6(daemon->dhcp_conf, context, NULL, 0, state.hostname);
+		  struct dhcp_config *new = find_config(daemon->dhcp_conf, context, NULL, 0, NULL, 0, 0, state.hostname);
 		  if (new && !have_config(new, CONFIG_CLID) && !new->hwaddr)
 		    config = new;
 		}
@@ -708,7 +742,7 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
 	    ltmp = NULL;
 	    while ((ltmp = lease6_find_by_client(ltmp, state.ia_type == OPTION6_IA_NA ? LEASE_NA : LEASE_TA, state.clid, state.clid_len, state.iaid)))
 	      {
-		req_addr = (struct in6_addr *)ltmp->hwaddr;
+		req_addr = &ltmp->addr6;
 		if ((c = address6_available(context, req_addr, solicit_tags, plain_range)))
 		  {
 #ifdef OPTION6_PREFIX_CLASS
@@ -949,6 +983,9 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
 		    calculate_times(this_context, &min_time, &valid_time, &preferred_time, lease_time); 
 		    
 		    lease_set_expires(lease, valid_time, now);
+		    /* Update MAC record in case it's new information. */
+		    if (mac_len != 0)
+		      lease_set_hwaddr(lease, mac, state.clid, mac_len, mac_type, state.clid_len, now, 0);
 		    if (state.ia_type == OPTION6_IA_NA && state.hostname)
 		      {
 			char *addr_domain = get_domain6(req_addr);
@@ -1189,8 +1226,16 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
   log_tags(tagif, state.xid);
   
   if (option_bool(OPT_LOG_OPTS))
-    log6_opts(0, state.xid, daemon->outpacket.iov_base + start_opts, daemon->outpacket.iov_base + save_counter(-1));
-  
+    {
+      if (mac_len != 0)
+	{
+	  print_mac(daemon->dhcp_buff, mac, mac_len);
+	  my_syslog(MS_DHCP | LOG_INFO, _("%u client MAC address: %s"), state.xid, daemon->dhcp_buff);
+	}
+      
+      log6_opts(0, state.xid, daemon->outpacket.iov_base + start_opts, daemon->outpacket.iov_base + save_counter(-1));
+    }
+
   return 1;
 
 }
@@ -1609,7 +1654,7 @@ static int check_address(struct state *state, struct in6_addr *addr)
 
   if (lease->clid_len != state->clid_len || 
       memcmp(lease->clid, state->clid, state->clid_len) != 0 ||
-      lease->hwaddr_type != state->iaid)
+      lease->iaid != state->iaid)
     return 0;
 
   return 1;
@@ -1690,7 +1735,8 @@ static void update_leases(struct state *state, struct dhcp_context *context, str
   if (lease)
     {
       lease_set_expires(lease, lease_time, now);
-      lease_set_hwaddr(lease, NULL, state->clid, 0, state->iaid, state->clid_len, now, 0);
+      lease_set_iaid(lease, state->iaid); 
+      lease_set_hwaddr(lease, state->mac, state->clid, state->mac_len, state->mac_type, state->clid_len, now, 0);
       lease_set_interface(lease, state->interface, now);
       if (state->hostname && state->ia_type == OPTION6_IA_NA)
 	{
@@ -1927,7 +1973,8 @@ static unsigned int opt6_uint(unsigned char *opt, int offset, int size)
   return ret;
 } 
 
-void relay_upstream6(struct dhcp_relay *relay, ssize_t sz, struct in6_addr *peer_address, u32 scope_id)
+void relay_upstream6(struct dhcp_relay *relay, ssize_t sz, struct in6_addr *peer_address, u32 scope_id,
+		     unsigned char *mac, unsigned int mac_len, unsigned int mac_type )
 {
   /* ->local is same value for all relays on ->current chain */
   
@@ -1963,6 +2010,15 @@ void relay_upstream6(struct dhcp_relay *relay, ssize_t sz, struct in6_addr *peer
       header[1] = hopcount;
       memcpy(&header[2],  &relay->local.addr.addr6, IN6ADDRSZ);
       memcpy(&header[18], peer_address, IN6ADDRSZ);
+ 
+      /* RFC-6939 */
+      if (mac)
+	{
+	  o = new_opt6(OPTION6_CLIENT_MAC);
+	  put_opt6_short(mac_type);
+	  put_opt6(mac, mac_len);
+	  end_opt6(o);
+	}
       
       o = new_opt6(OPTION6_RELAY_MSG);
       put_opt6(inbuff, sz);