--- sys/netinet/tcp_syncache.c	(svn+ssh://svn.freebsd.org/base/head)	(revision 261548)
+++ sys/netinet/tcp_syncache.c	(working copy)
@@ -77,6 +77,7 @@ __FBSDID("$FreeBSD$");
 #include <netinet6/nd6.h>
 #include <netinet6/ip6_var.h>
 #include <netinet6/in6_pcb.h>
+#include <netinet6/scope6_var.h>
 #endif
 #include <netinet/tcp.h>
 #include <netinet/tcp_fsm.h>
@@ -712,6 +713,7 @@ syncache_socket(struct syncache *sc, struct socket
 #ifdef INET6
 	if (sc->sc_inc.inc_flags & INC_ISIPV6) {
 		inp->in6p_laddr = sc->sc_inc.inc6_laddr;
+		inp->in6p_zoneid = sc->sc_inc.inc6_zoneid;
 	} else {
 		inp->inp_vflag &= ~INP_IPV6;
 		inp->inp_vflag |= INP_IPV4;
@@ -786,7 +788,9 @@ syncache_socket(struct syncache *sc, struct socket
 		sin6.sin6_len = sizeof(sin6);
 		sin6.sin6_addr = sc->sc_inc.inc6_faddr;
 		sin6.sin6_port = sc->sc_inc.inc_fport;
-		sin6.sin6_flowinfo = sin6.sin6_scope_id = 0;
+		sin6.sin6_flowinfo = 0;
+		sin6.sin6_scope_id = IN6_IS_ADDR_LINKLOCAL(&sin6.sin6_addr) ?
+		    sc->sc_inc.inc6_zoneid: 0;
 		laddr6 = inp->in6p_laddr;
 		if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr))
 			inp->in6p_laddr = sc->sc_inc.inc6_laddr;
@@ -1534,7 +1538,7 @@ syncache_respond(struct syncache *sc)
 
 #ifdef TCP_SIGNATURE
 		if (sc->sc_flags & SCF_SIGNATURE)
-			tcp_signature_compute(m, 0, 0, optlen,
+			tcp_signature_compute(m, &sc->sc_inc, 0, optlen,
 			    to.to_signature, IPSEC_DIR_OUTBOUND);
 #endif
 #ifdef INET6
@@ -1550,10 +1554,16 @@ syncache_respond(struct syncache *sc)
 	m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
 #ifdef INET6
 	if (sc->sc_inc.inc_flags & INC_ISIPV6) {
+		struct ifnet *ifp;
+
 		m->m_pkthdr.csum_flags = CSUM_TCP_IPV6;
 		th->th_sum = in6_cksum_pseudo(ip6, tlen + optlen - hlen,
 		    IPPROTO_TCP, 0);
-		ip6->ip6_hlim = in6_selecthlim(NULL, NULL);
+		if (sc->sc_inc.inc6_zoneid != 0)
+			ifp = in6_getlinkifnet(sc->sc_inc.inc6_zoneid);
+		else
+			ifp = NULL;
+		ip6->ip6_hlim = in6_selecthlim(NULL, ifp);
 #ifdef TCP_OFFLOAD
 		if (ADDED_BY_TOE(sc)) {
 			struct toedev *tod = sc->sc_tod;
@@ -1563,7 +1573,8 @@ syncache_respond(struct syncache *sc)
 			return (error);
 		}
 #endif
-		error = ip6_output(m, NULL, NULL, 0, NULL, NULL, NULL);
+		error = ip6_output(m, NULL, NULL, ifp ? IPV6_USEROIF: 0,
+		    NULL, &ifp, NULL);
 	}
 #endif
 #if defined(INET6) && defined(INET)