diff --git a/CHANGES b/CHANGES
index 5a60b621..2d73c8e9 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,5 @@
+2016/09/18	Moved auto prefix code from config file parse to send_ra.
+
 2016/08/08	Merged ARPHRD_6LOWPAN netlink query from <Alexander Aring>
 		Add systemd service file <Craig Andrews>
 
diff --git a/gram.y b/gram.y
index 1ed4aa33..9ee19d49 100644
--- a/gram.y
+++ b/gram.y
@@ -19,9 +19,6 @@
 #include "defaults.h"
 
 #define YYERROR_VERBOSE 1
-static int countbits(int b);
-static int count_mask(struct sockaddr_in6 *m);
-static struct in6_addr get_prefix6(struct in6_addr const *addr, struct in6_addr const *mask);
 
 #if 0 /* no longer necessary? */
 #ifndef HAVE_IN6_ADDR_S6_ADDR
@@ -375,84 +372,12 @@ prefixdef	: prefixhead optional_prefixplist ';'
 					ABORT;
 				}
 
-				if ( prefix->if6[0] && prefix->if6to4[0]) {
-					flog(LOG_ERR, "Base6Interface and Base6to4Interface are mutually exclusive at this time");
-					ABORT;
-				}
-
-				if ( prefix->if6to4[0] )
-				{
-					if (get_v4addr(prefix->if6to4, &dst) < 0)
-					{
-						flog(LOG_ERR, "interface %s has no IPv4 addresses, disabling 6to4 prefix", prefix->if6to4 );
-						prefix->enabled = 0;
-					}
-					else
-					{
-						*((uint16_t *)(prefix->Prefix.s6_addr)) = htons(0x2002);
-						memcpy( prefix->Prefix.s6_addr + 2, &dst, sizeof( dst ) );
-					}
-				}
-
 				if ( prefix->if6[0] )
 				{
-#ifndef HAVE_IFADDRS_H
-					flog(LOG_ERR, "Base6Interface not supported in %s, line %d", filename, num_lines);
-					ABORT;
-#else
-					struct ifaddrs *ifap = 0, *ifa = 0;
-					struct AdvPrefix *next = prefix->next;
-
 					if (prefix->PrefixLen != 64) {
 						flog(LOG_ERR, "only /64 is allowed with Base6Interface.  %s:%d", filename, num_lines);
 						ABORT;
 					}
-
-					if (getifaddrs(&ifap) != 0)
-						flog(LOG_ERR, "getifaddrs failed: %s", strerror(errno));
-
-					for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
-						struct sockaddr_in6 *s6 = 0;
-						struct sockaddr_in6 *mask = (struct sockaddr_in6 *)ifa->ifa_netmask;
-						struct in6_addr base6prefix;
-						char buf[INET6_ADDRSTRLEN];
-						int i;
-
-						if (strncmp(ifa->ifa_name, prefix->if6, IFNAMSIZ))
-							continue;
-
-						if (ifa->ifa_addr->sa_family != AF_INET6)
-							continue;
-
-						s6 = (struct sockaddr_in6 *)(ifa->ifa_addr);
-
-						if (IN6_IS_ADDR_LINKLOCAL(&s6->sin6_addr))
-							continue;
-
-						base6prefix = get_prefix6(&s6->sin6_addr, &mask->sin6_addr);
-						for (i = 0; i < 8; ++i) {
-							prefix->Prefix.s6_addr[i] &= ~mask->sin6_addr.s6_addr[i];
-							prefix->Prefix.s6_addr[i] |= base6prefix.s6_addr[i];
-						}
-						memset(&prefix->Prefix.s6_addr[8], 0, 8);
-						prefix->AdvRouterAddr = 1;
-						prefix->AutoSelected = 1;
-						prefix->next = next;
-
-						if (inet_ntop(ifa->ifa_addr->sa_family, (void *)&(prefix->Prefix), buf, sizeof(buf)) == NULL)
-							flog(LOG_ERR, "%s: inet_ntop failed in %s, line %d!", ifa->ifa_name, filename, num_lines);
-						else
-							dlog(LOG_DEBUG, 3, "auto-selected prefix %s/%d on interface %s from interface %s",
-								buf, prefix->PrefixLen, iface->props.name, ifa->ifa_name);
-
-						/* Taking only one prefix from the Base6Interface.  Taking more than one would require allocating new
-						   prefixes and building a list.  I'm not sure how to do that from here. So for now, break. */
-						break;
-					}
-
-					if (ifap)
-						freeifaddrs(ifap);
-#endif /* ifndef HAVE_IFADDRS_H */
 				}
 			}
 			$$ = prefix;
@@ -466,94 +391,26 @@ prefixhead	: T_PREFIX IPV6ADDR '/' NUMBER
 			memset(&zeroaddr, 0, sizeof(zeroaddr));
 
 			if (!memcmp($2, &zeroaddr, sizeof(struct in6_addr))) {
-#ifndef HAVE_IFADDRS_H
-				flog(LOG_ERR, "invalid all-zeros prefix in %s, line %d", filename, num_lines);
-				ABORT;
-#else
-				struct ifaddrs *ifap = 0, *ifa = 0;
-				struct AdvPrefix *next = iface->AdvPrefixList;
-
-				while (next) {
-					if (next->AutoSelected) {
-						flog(LOG_ERR, "auto selecting prefixes works only once per interface.  See %s, line %d", filename, num_lines);
-						ABORT;
-					}
-					next = next->next;
-				}
-				next = 0;
-
-				dlog(LOG_DEBUG, 5, "all-zeros prefix in %s, line %d", filename, num_lines);
-
-				if (getifaddrs(&ifap) != 0)
-					flog(LOG_ERR, "getifaddrs failed: %s", strerror(errno));
-
-				for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
-					struct sockaddr_in6 *s6 = (struct sockaddr_in6 *)ifa->ifa_addr;
-					struct sockaddr_in6 *mask = (struct sockaddr_in6 *)ifa->ifa_netmask;
-					char buf[INET6_ADDRSTRLEN];
-
-					if (strncmp(ifa->ifa_name, iface->props.name, IFNAMSIZ))
-						continue;
-
-					if (ifa->ifa_addr->sa_family != AF_INET6)
-						continue;
-
-					s6 = (struct sockaddr_in6 *)(ifa->ifa_addr);
-
-					if (IN6_IS_ADDR_LINKLOCAL(&s6->sin6_addr))
-						continue;
-
-					prefix = malloc(sizeof(struct AdvPrefix));
-
-					if (prefix == NULL) {
-						flog(LOG_CRIT, "malloc failed: %s", strerror(errno));
-						ABORT;
-					}
-
-					prefix_init_defaults(prefix);
-					prefix->Prefix = get_prefix6(&s6->sin6_addr, &mask->sin6_addr);
-					prefix->AdvRouterAddr = 1;
-					prefix->AutoSelected = 1;
-					prefix->next = next;
-					next = prefix;
-
-					if (prefix->PrefixLen == 0)
-						prefix->PrefixLen = count_mask(mask);
-
-					if (inet_ntop(ifa->ifa_addr->sa_family, (void *)&(prefix->Prefix), buf, sizeof(buf)) == NULL)
-						flog(LOG_ERR, "%s: inet_ntop failed in %s, line %d!", ifa->ifa_name, filename, num_lines);
-					else
-						dlog(LOG_DEBUG, 3, "auto-selected prefix %s/%d on interface %s", buf, prefix->PrefixLen, ifa->ifa_name);
-				}
-
-				if (!prefix) {
-					flog(LOG_WARNING, "no auto-selected prefix on interface %s, disabling advertisements",  iface->props.name);
-				}
-
-				if (ifap)
-					freeifaddrs(ifap);
-#endif /* ifndef HAVE_IFADDRS_H */
+				flog(LOG_WARNING, "invalid all-zeros prefix in %s, line %d", filename, num_lines);
 			}
-			else {
-				prefix = malloc(sizeof(struct AdvPrefix));
+			prefix = malloc(sizeof(struct AdvPrefix));
 
-				if (prefix == NULL) {
-					flog(LOG_CRIT, "malloc failed: %s", strerror(errno));
-					ABORT;
-				}
+			if (prefix == NULL) {
+				flog(LOG_CRIT, "malloc failed: %s", strerror(errno));
+				ABORT;
+			}
 
-				prefix_init_defaults(prefix);
+			prefix_init_defaults(prefix);
 
-				if ($4 > MAX_PrefixLen)
-				{
-					flog(LOG_ERR, "invalid prefix length in %s, line %d", filename, num_lines);
-					ABORT;
-				}
+			if ($4 > MAX_PrefixLen)
+			{
+				flog(LOG_ERR, "invalid prefix length in %s, line %d", filename, num_lines);
+				ABORT;
+			}
 
-				prefix->PrefixLen = $4;
+			prefix->PrefixLen = $4;
 
-				memcpy(&prefix->Prefix, $2, sizeof(struct in6_addr));
-			}
+			memcpy(&prefix->Prefix, $2, sizeof(struct in6_addr));
 		}
 		;
 
@@ -569,72 +426,33 @@ prefixplist	: prefixplist prefixparms
 prefixparms	: T_AdvOnLink SWITCH ';'
 		{
 			if (prefix) {
-				if (prefix->AutoSelected) {
-					struct AdvPrefix *p = prefix;
-					do {
-						p->AdvOnLinkFlag = $2;
-						p = p->next;
-					} while (p && p->AutoSelected);
-				}
-				else
-					prefix->AdvOnLinkFlag = $2;
+				prefix->AdvOnLinkFlag = $2;
 			}
 		}
 		| T_AdvAutonomous SWITCH ';'
 		{
 			if (prefix) {
-				if (prefix->AutoSelected) {
-					struct AdvPrefix *p = prefix;
-					do {
-						p->AdvAutonomousFlag = $2;
-						p = p->next;
-					} while (p && p->AutoSelected);
-				}
-				else
-					prefix->AdvAutonomousFlag = $2;
+				prefix->AdvAutonomousFlag = $2;
 			}
 		}
 		| T_AdvRouterAddr SWITCH ';'
 		{
 			if (prefix) {
-				if (prefix->AutoSelected && $2 == 0)
-					flog(LOG_WARNING, "prefix automatically selected, AdvRouterAddr always enabled, ignoring config line %d", num_lines);
-				else
-					prefix->AdvRouterAddr = $2;
+				prefix->AdvRouterAddr = $2;
 			}
 		}
 		| T_AdvValidLifetime number_or_infinity ';'
 		{
 			if (prefix) {
-				if (prefix->AutoSelected) {
-					struct AdvPrefix *p = prefix;
-					do {
-						p->AdvValidLifetime = $2;
-						p->curr_validlft = $2;
-						p = p->next;
-					} while (p && p->AutoSelected);
-				}
-				else {
-					prefix->AdvValidLifetime = $2;
-					prefix->curr_validlft = $2;
-				}
+				prefix->AdvValidLifetime = $2;
+				prefix->curr_validlft = $2;
 			}
 		}
 		| T_AdvPreferredLifetime number_or_infinity ';'
 		{
 			if (prefix) {
-				if (prefix->AutoSelected) {
-					struct AdvPrefix *p = prefix;
-					do {
-						p->AdvPreferredLifetime = $2;
-						p->curr_preferredlft = $2;
-						p = p->next;
-					} while (p && p->AutoSelected);
-				}
-				else {
-					prefix->AdvPreferredLifetime = $2;
-					prefix->curr_preferredlft = $2;
-				}
+				prefix->AdvPreferredLifetime = $2;
+				prefix->curr_preferredlft = $2;
 			}
 		}
 		| T_DeprecatePrefix SWITCH ';'
@@ -651,28 +469,30 @@ prefixparms	: T_AdvOnLink SWITCH ';'
 		}
 		| T_Base6Interface name ';'
 		{
+#ifndef HAVE_IFADDRS_H
+			flog(LOG_ERR, "Base6Interface not supported in %s, line %d", filename, num_lines);
+			ABORT;
+#else
 			if (prefix) {
-				if (prefix->AutoSelected) {
-					flog(LOG_ERR, "automatically selecting the prefix and Base6Interface are mutually exclusive");
-					ABORT;
-				} /* fallthrough */
 				dlog(LOG_DEBUG, 4, "using prefixes on interface %s for prefixes on interface %s", $2, iface->props.name);
 				strncpy(prefix->if6, $2, IFNAMSIZ-1);
 				prefix->if6[IFNAMSIZ-1] = '\0';
 			}
+#endif
 		}
 
 		| T_Base6to4Interface name ';'
 		{
+#ifndef HAVE_IFADDRS_H
+			flog(LOG_ERR, "Base6to4Interface not supported in %s, line %d", filename, num_lines);
+			ABORT;
+#else
 			if (prefix) {
-				if (prefix->AutoSelected) {
-					flog(LOG_ERR, "automatically selecting the prefix and Base6to4Interface are mutually exclusive");
-					ABORT;
-				} /* fallthrough */
 				dlog(LOG_DEBUG, 4, "using interface %s for 6to4 prefixes on interface %s", $2, iface->props.name);
 				strncpy(prefix->if6to4, $2, IFNAMSIZ-1);
 				prefix->if6to4[IFNAMSIZ-1] = '\0';
 			}
+#endif
 		}
 		;
 
@@ -1036,41 +856,6 @@ number_or_infinity	: NUMBER
 
 %%
 
-static int countbits(int b)
-{
-	int count;
-
-	for (count = 0; b != 0; count++) {
-		b &= b - 1; // this clears the LSB-most set bit
-	}
-
-	return (count);
-}
-
-static int count_mask(struct sockaddr_in6 *m)
-{
-	struct in6_addr *in6 = &m->sin6_addr;
-	int i;
-	int count = 0;
-
-	for (i = 0; i < 16; ++i) {
-		count += countbits(in6->s6_addr[i]);
-	}
-	return count;
-}
-
-static struct in6_addr get_prefix6(struct in6_addr const *addr, struct in6_addr const *mask)
-{
-	struct in6_addr prefix = *addr;
-	int i = 0;
-
-	for (; i < 16; ++i) {
-		prefix.s6_addr[i] &= mask->s6_addr[i];
-	}
-
-	return prefix;
-}
-
 static void cleanup(void)
 {
 	if (iface) {
diff --git a/interface.c b/interface.c
index d09a1e71..56c3d677 100644
--- a/interface.c
+++ b/interface.c
@@ -113,8 +113,6 @@ void prefix_init_defaults(struct AdvPrefix *prefix)
 	prefix->AdvPreferredLifetime = DFLT_AdvPreferredLifetime;
 	prefix->DeprecatePrefixFlag = DFLT_DeprecatePrefixFlag;
 	prefix->DecrementLifetimesFlag = DFLT_DecrementLifetimesFlag;
-	prefix->if6to4[0] = 0;
-	prefix->enabled = 1;
 
 	prefix->curr_validlft = prefix->AdvValidLifetime;
 	prefix->curr_preferredlft = prefix->AdvPreferredLifetime;
diff --git a/process.c b/process.c
index 1e392c73..c9b9b36a 100644
--- a/process.c
+++ b/process.c
@@ -255,7 +255,7 @@ static void process_ra(struct Interface *iface, unsigned char *msg, int len, str
 				struct AdvPrefix *prefix = iface->AdvPrefixList;
 				while (prefix) {
 					char prefix_str[INET6_ADDRSTRLEN];
-					if (prefix->enabled && (prefix->PrefixLen == pinfo->nd_opt_pi_prefix_len)
+					if ((prefix->PrefixLen == pinfo->nd_opt_pi_prefix_len)
 					    && addr_match(&prefix->Prefix, &pinfo->nd_opt_pi_prefix, prefix->PrefixLen)) {
 						addrtostr(&prefix->Prefix, prefix_str, sizeof(prefix_str));
 
diff --git a/radvd.h b/radvd.h
index 08b8181b..12e403ca 100644
--- a/radvd.h
+++ b/radvd.h
@@ -144,8 +144,6 @@ struct AdvPrefix {
 
 	/* 6to4 etc. extensions */
 	char if6to4[IFNAMSIZ];
-	int enabled;
-	int AutoSelected;
 
 	/* Select prefixes from this interface. */
 	char if6[IFNAMSIZ];
@@ -310,6 +308,9 @@ void process(int sock, struct Interface *, unsigned char *, int, struct sockaddr
 int recv_rs_ra(int sock, unsigned char *, struct sockaddr_in6 *, struct in6_pktinfo **, int *, unsigned char*);
 
 /* util.c */
+int countbits(int b);
+int count_mask(struct sockaddr_in6 *m);
+struct in6_addr get_prefix6(struct in6_addr const *addr, struct in6_addr const *mask);
 char * strdupf(char const * format, ...) __attribute__ ((format(printf, 1, 2)));
 double rand_between(double, double);
 int check_dnssl_presence(struct AdvDNSSL *, const char *);
diff --git a/send.c b/send.c
index 96ded058..bbd7a23a 100644
--- a/send.c
+++ b/send.c
@@ -26,7 +26,8 @@ static void decrement_lifetime(const time_t secs, uint32_t * lifetime);
 static void update_iface_times(struct Interface * iface);
 
 static void add_ra_header(struct safe_buffer * sb, struct ra_header_info const * ra_header_info, int cease_adv);
-static void add_prefix(struct safe_buffer * sb, struct AdvPrefix const * prefix, int cease_adv);
+static void add_prefixs(struct safe_buffer * sb, char const * ifname, struct AdvPrefix const * prefix, int cease_adv);
+static void add_one_prefix(struct safe_buffer * sb, char const * ifname, struct AdvPrefix const * prefix, int cease_adv);
 static void add_route(struct safe_buffer * sb, struct AdvRoute const *route, int cease_adv);
 static void add_rdnss(struct safe_buffer * sb, struct AdvRDNSS const *rdnss, int cease_adv);
 static size_t serialize_domain_names(struct safe_buffer * safe_buffer, struct AdvDNSSL const *dnssl);
@@ -138,7 +139,7 @@ static void update_iface_times(struct Interface * iface)
 
 	struct AdvPrefix *prefix = iface->AdvPrefixList;
 	while (prefix) {
-		if (prefix->enabled && (!prefix->DecrementLifetimesFlag || prefix->curr_preferredlft > 0)) {
+		if ((!prefix->DecrementLifetimesFlag || prefix->curr_preferredlft > 0)) {
 			if (!(iface->state_info.cease_adv && prefix->DeprecatePrefixFlag)) {
 				if (prefix->DecrementLifetimesFlag) {
 
@@ -191,39 +192,130 @@ static void add_ra_header(struct safe_buffer * sb, struct ra_header_info const *
 	safe_buffer_append(sb, &radvert, sizeof(radvert));
 }
 
-static void add_prefix(struct safe_buffer * sb, struct AdvPrefix const *prefix, int cease_adv)
+static void add_one_prefix(struct safe_buffer * sb, char const * ifname, struct AdvPrefix const * prefix, int cease_adv)
+{
+	struct nd_opt_prefix_info pinfo;
+
+	memset(&pinfo, 0, sizeof(pinfo));
+
+	pinfo.nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
+	pinfo.nd_opt_pi_len = 4;
+	pinfo.nd_opt_pi_prefix_len = prefix->PrefixLen;
+
+	pinfo.nd_opt_pi_flags_reserved = (prefix->AdvOnLinkFlag) ? ND_OPT_PI_FLAG_ONLINK : 0;
+	pinfo.nd_opt_pi_flags_reserved |= (prefix->AdvAutonomousFlag) ? ND_OPT_PI_FLAG_AUTO : 0;
+	/* Mobile IPv6 ext */
+	pinfo.nd_opt_pi_flags_reserved |= (prefix->AdvRouterAddr) ? ND_OPT_PI_FLAG_RADDR : 0;
+
+	if (cease_adv && prefix->DeprecatePrefixFlag) {
+		/* RFC4862, 5.5.3, step e) */
+		if (prefix->curr_validlft < MIN_AdvValidLifetime) {
+			pinfo.nd_opt_pi_valid_time = htonl(prefix->curr_validlft);
+		} else {
+			pinfo.nd_opt_pi_valid_time = htonl(MIN_AdvValidLifetime);
+		}
+		pinfo.nd_opt_pi_preferred_time = 0;
+	} else {
+		pinfo.nd_opt_pi_valid_time = htonl(prefix->curr_validlft);
+		pinfo.nd_opt_pi_preferred_time = htonl(prefix->curr_preferredlft);
+	}
+
+	memcpy(&pinfo.nd_opt_pi_prefix, &prefix->Prefix, sizeof(struct in6_addr));
+
+	safe_buffer_append(sb, &pinfo, sizeof(pinfo));
+}
+static void add_auto_prefixes_6to4(struct safe_buffer * sb, char const * ifname, struct AdvPrefix const *prefix, int cease_adv)
+{
+#ifdef HAVE_IFADDRS_H
+	struct AdvPrefix xprefix = *prefix;
+	unsigned int dst;
+	if (get_v4addr(prefix->if6to4, &dst) < 0) {
+		flog(LOG_ERR, "Base6to4interface %s has no IPv4 addresses", prefix->if6to4);
+	} else {
+		memcpy(xprefix.Prefix.s6_addr + 2, &dst, sizeof(dst));
+		*((uint16_t *)(xprefix.Prefix.s6_addr)) = htons(0x2002);
+		xprefix.PrefixLen = 64;
+
+		char pfx_str[INET6_ADDRSTRLEN];
+		addrtostr(&xprefix.Prefix, pfx_str, sizeof(pfx_str));
+		dlog(LOG_DEBUG, 3, "auto-selected prefix %s/%d on interface %s",
+			pfx_str, xprefix.PrefixLen, ifname);
+
+		/* TODO: Something must be done with these. */
+		(void)xprefix.curr_validlft;
+		(void)xprefix.curr_preferredlft;
+
+		add_one_prefix(sb, ifname, &xprefix, cease_adv);
+	}
+#endif
+}
+
+
+static void add_auto_prefixes(struct safe_buffer * sb, char const * ifname, struct AdvPrefix const *prefix, int cease_adv)
+{
+#ifdef HAVE_IFADDRS_H
+	struct AdvPrefix xprefix;
+	struct ifaddrs *ifap = 0, *ifa = 0;
+
+	if (getifaddrs(&ifap) != 0)
+		flog(LOG_ERR, "getifaddrs failed: %s", strerror(errno));
+
+	for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
+
+		if (strncmp(ifa->ifa_name, ifname, IFNAMSIZ))
+			continue;
+
+		if (ifa->ifa_addr->sa_family != AF_INET6)
+			continue;
+
+		struct sockaddr_in6 *s6 = (struct sockaddr_in6 *)ifa->ifa_addr;
+		struct sockaddr_in6 *mask = (struct sockaddr_in6 *)ifa->ifa_netmask;
+
+		if (IN6_IS_ADDR_LINKLOCAL(&s6->sin6_addr))
+			continue;
+
+		xprefix = *prefix;
+		xprefix.Prefix = get_prefix6(&s6->sin6_addr, &mask->sin6_addr);
+		xprefix.PrefixLen = count_mask(mask);
+
+		char pfx_str[INET6_ADDRSTRLEN];
+		addrtostr(&xprefix.Prefix, pfx_str, sizeof(pfx_str));
+		dlog(LOG_DEBUG, 3, "auto-selected prefix %s/%d on interface %s",
+			pfx_str, xprefix.PrefixLen, ifname);
+
+		/* TODO: Something must be done with these. */
+		(void)xprefix.curr_validlft;
+		(void)xprefix.curr_preferredlft;
+
+		add_one_prefix(sb, ifname, &xprefix, cease_adv);
+	}
+
+	if (ifap)
+		freeifaddrs(ifap);
+#endif
+}
+
+static void add_prefixs(struct safe_buffer * sb, char const * ifname, struct AdvPrefix const *prefix, int cease_adv)
 {
 	while (prefix) {
-		if (prefix->enabled && (!prefix->DecrementLifetimesFlag || prefix->curr_preferredlft > 0)) {
-			struct nd_opt_prefix_info pinfo;
-
-			memset(&pinfo, 0, sizeof(pinfo));
-
-			pinfo.nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
-			pinfo.nd_opt_pi_len = 4;
-			pinfo.nd_opt_pi_prefix_len = prefix->PrefixLen;
-
-			pinfo.nd_opt_pi_flags_reserved = (prefix->AdvOnLinkFlag) ? ND_OPT_PI_FLAG_ONLINK : 0;
-			pinfo.nd_opt_pi_flags_reserved |= (prefix->AdvAutonomousFlag) ? ND_OPT_PI_FLAG_AUTO : 0;
-			/* Mobile IPv6 ext */
-			pinfo.nd_opt_pi_flags_reserved |= (prefix->AdvRouterAddr) ? ND_OPT_PI_FLAG_RADDR : 0;
-
-			if (cease_adv && prefix->DeprecatePrefixFlag) {
-				/* RFC4862, 5.5.3, step e) */
-				if (prefix->curr_validlft < MIN_AdvValidLifetime) {
-					pinfo.nd_opt_pi_valid_time = htonl(prefix->curr_validlft);
-				} else {
-					pinfo.nd_opt_pi_valid_time = htonl(MIN_AdvValidLifetime);
+		if ((!prefix->DecrementLifetimesFlag || prefix->curr_preferredlft > 0)) {
+			struct in6_addr zero = {};
+			if (prefix->if6to4[0] || prefix->if6[0] || 0 == memcmp(&prefix->Prefix, &zero, sizeof(zero))) {
+				if (prefix->if6to4[0]) {
+					dlog(LOG_DEBUG, 4, "if6to4 auto prefix detected on iface %s", ifname);
+					add_auto_prefixes_6to4(sb, prefix->if6to4, prefix, cease_adv);
+				}
+				if (prefix->if6[0]) {
+					dlog(LOG_DEBUG, 4, "if6 auto prefix detected on iface %s", ifname);
+					add_auto_prefixes(sb, prefix->if6, prefix, cease_adv);
+				}
+				if (0 == memcmp(&prefix->Prefix, &zero, sizeof(zero))) {
+					dlog(LOG_DEBUG, 4, "::/64 auto prefix detected on iface %s", ifname);
+					add_auto_prefixes(sb, ifname, prefix, cease_adv);
 				}
-				pinfo.nd_opt_pi_preferred_time = 0;
 			} else {
-				pinfo.nd_opt_pi_valid_time = htonl(prefix->curr_validlft);
-				pinfo.nd_opt_pi_preferred_time = htonl(prefix->curr_preferredlft);
+				add_one_prefix(sb, ifname, prefix, cease_adv);
 			}
-
-			memcpy(&pinfo.nd_opt_pi_prefix, &prefix->Prefix, sizeof(struct in6_addr));
-
-			safe_buffer_append(sb, &pinfo, sizeof(pinfo));
 		}
 
 		prefix = prefix->next;
@@ -579,7 +671,7 @@ static void build_ra(struct safe_buffer * sb, struct Interface const * iface)
 	add_ra_header(sb, &iface->ra_header_info, iface->state_info.cease_adv);
 
 	if (iface->AdvPrefixList) {
-		add_prefix(sb, iface->AdvPrefixList, iface->state_info.cease_adv);
+		add_prefixs(sb, iface->props.name, iface->AdvPrefixList, iface->state_info.cease_adv);
 	}
 
 	if (iface->AdvRouteList) {
diff --git a/test/send.c b/test/send.c
index 5a9f7108..1da8d5f8 100644
--- a/test/send.c
+++ b/test/send.c
@@ -61,7 +61,7 @@ START_TEST (test_add_prefix)
 	ck_assert_ptr_ne(0, iface);
 
 	struct safe_buffer sb = SAFE_BUFFER_INIT;
-	add_prefix(&sb, iface->AdvPrefixList, iface->state_info.cease_adv);
+	add_prefixs(&sb, iface->props.name, iface->AdvPrefixList, iface->state_info.cease_adv);
 
 #ifdef PRINT_SAFE_BUFFER
 	print_safe_buffer(&sb);
diff --git a/util.c b/util.c
index b4b4620e..30fdb1aa 100644
--- a/util.c
+++ b/util.c
@@ -171,3 +171,40 @@ ssize_t writen(int fd, const void *buf, size_t count)
 	}
 	return n;
 }
+
+int countbits(int b)
+{
+	int count;
+
+	for (count = 0; b != 0; count++) {
+		b &= b - 1; // this clears the LSB-most set bit
+	}
+
+	return (count);
+}
+
+int count_mask(struct sockaddr_in6 *m)
+{
+	struct in6_addr *in6 = &m->sin6_addr;
+	int i;
+	int count = 0;
+
+	for (i = 0; i < 16; ++i) {
+		count += countbits(in6->s6_addr[i]);
+	}
+	return count;
+}
+
+struct in6_addr get_prefix6(struct in6_addr const *addr, struct in6_addr const *mask)
+{
+	struct in6_addr prefix = *addr;
+	int i = 0;
+
+	for (; i < 16; ++i) {
+		prefix.s6_addr[i] &= mask->s6_addr[i];
+	}
+
+	return prefix;
+}
+
+