Index: stable/10/sys/net/if_gif.h
===================================================================
--- stable/10/sys/net/if_gif.h	(revision 279514)
+++ stable/10/sys/net/if_gif.h	(working copy)
@@ -117,7 +117,9 @@ int gif_encapcheck(const struct mbuf *, int, int,
 #define GIFSOPTS	_IOW('i', 151, struct ifreq)
 
 #define	GIF_ACCEPT_REVETHIP	0x0001
+#define	GIF_IGNORE_SOURCE	0x0002
 #define	GIF_SEND_REVETHIP	0x0010
-#define	GIF_OPTMASK		(GIF_ACCEPT_REVETHIP|GIF_SEND_REVETHIP)
+#define	GIF_OPTMASK		(GIF_ACCEPT_REVETHIP|GIF_SEND_REVETHIP| \
+    GIF_IGNORE_SOURCE)
 
 #endif /* _NET_IF_GIF_H_ */
Index: stable/10/sys/netinet/in_gif.c
===================================================================
--- stable/10/sys/netinet/in_gif.c	(revision 279514)
+++ stable/10/sys/netinet/in_gif.c	(working copy)
@@ -177,13 +177,19 @@ in_gif_input(struct mbuf **mp, int *offp, int prot
 static int
 gif_validate4(const struct ip *ip, struct gif_softc *sc, struct ifnet *ifp)
 {
+	int ret;
 
 	GIF_RLOCK_ASSERT(sc);
 
 	/* check for address match */
-	if (sc->gif_iphdr->ip_src.s_addr != ip->ip_dst.s_addr ||
-	    sc->gif_iphdr->ip_dst.s_addr != ip->ip_src.s_addr)
+	if (sc->gif_iphdr->ip_src.s_addr != ip->ip_dst.s_addr)
 		return (0);
+	ret = 32;
+	if (sc->gif_iphdr->ip_dst.s_addr != ip->ip_src.s_addr) {
+		if ((sc->gif_options & GIF_IGNORE_SOURCE) == 0)
+			return (0);
+	} else
+		ret += 32;
 
 	/* martian filters on outer source - NOT done in ip_input! */
 	if (IN_MULTICAST(ntohl(ip->ip_src.s_addr)))
@@ -214,7 +220,7 @@ gif_validate4(const struct ip *ip, struct gif_soft
 		}
 		RTFREE_LOCKED(rt);
 	}
-	return (32 * 2);
+	return (ret);
 }
 
 /*
Index: stable/10/sys/netinet6/in6_gif.c
===================================================================
--- stable/10/sys/netinet6/in6_gif.c	(revision 279514)
+++ stable/10/sys/netinet6/in6_gif.c	(working copy)
@@ -180,6 +180,7 @@ static int
 gif_validate6(const struct ip6_hdr *ip6, struct gif_softc *sc,
     struct ifnet *ifp)
 {
+	int ret;
 
 	GIF_RLOCK_ASSERT(sc);
 	/*
@@ -187,9 +188,14 @@ gif_validate6(const struct ip6_hdr *ip6, struct gi
 	 * packet.  We should compare the *source* address in our configuration
 	 * and the *destination* address of the packet, and vice versa.
 	 */
-	if (!IN6_ARE_ADDR_EQUAL(&sc->gif_ip6hdr->ip6_src, &ip6->ip6_dst) ||
-	    !IN6_ARE_ADDR_EQUAL(&sc->gif_ip6hdr->ip6_dst, &ip6->ip6_src))
+	if (!IN6_ARE_ADDR_EQUAL(&sc->gif_ip6hdr->ip6_src, &ip6->ip6_dst))
 		return (0);
+	ret = 128;
+	if (!IN6_ARE_ADDR_EQUAL(&sc->gif_ip6hdr->ip6_dst, &ip6->ip6_src)) {
+		if ((sc->gif_options & GIF_IGNORE_SOURCE) == 0)
+			return (0);
+	} else
+		ret += 128;
 
 	/* martian filters on outer source - done in ip6_input */
 
@@ -214,7 +220,7 @@ gif_validate6(const struct ip6_hdr *ip6, struct gi
 		RTFREE_LOCKED(rt);
 	}
 
-	return (128 * 2);
+	return (ret);
 }
 
 /*
Index: stable/10/sbin/ifconfig/ifgif.c
===================================================================
--- stable/10/sbin/ifconfig/ifgif.c	(revision 279514)
+++ stable/10/sbin/ifconfig/ifgif.c	(working copy)
@@ -51,7 +51,7 @@ static const char rcsid[] =
 
 #include "ifconfig.h"
 
-#define	GIFBITS	"\020\1ACCEPT_REV_ETHIP_VER\5SEND_REV_ETHIP_VER"
+#define	GIFBITS	"\020\1ACCEPT_REV_ETHIP_VER\2IGNORE_SOURCE\5SEND_REV_ETHIP_VER"
 
 static void	gif_status(int);
 
@@ -95,6 +95,8 @@ setgifopts(const char *val,
 static struct cmd gif_cmds[] = {
 	DEF_CMD("accept_rev_ethip_ver",	GIF_ACCEPT_REVETHIP,	setgifopts),
 	DEF_CMD("-accept_rev_ethip_ver",-GIF_ACCEPT_REVETHIP,	setgifopts),
+	DEF_CMD("ignore_source",	GIF_IGNORE_SOURCE,	setgifopts),
+	DEF_CMD("-ignore_source",	-GIF_IGNORE_SOURCE,	setgifopts),
 	DEF_CMD("send_rev_ethip_ver",	GIF_SEND_REVETHIP,	setgifopts),
 	DEF_CMD("-send_rev_ethip_ver",	-GIF_SEND_REVETHIP,	setgifopts),
 };