diff --git a/include/net/tcp.h b/include/net/tcp.h
index 3166dc15d7d6..60c384569e9c 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1576,6 +1576,7 @@ struct tcp_md5sig_key {
 	u8			keylen;
 	u8			family; /* AF_INET or AF_INET6 */
 	u8			prefixlen;
+	u8			flags;
 	union tcp_md5_addr	addr;
 	int			l3index; /* set if key added with L3 scope */
 	u8			key[TCP_MD5SIG_MAXKEYLEN];
@@ -1621,10 +1622,10 @@ struct tcp_md5sig_pool {
 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
 			const struct sock *sk, const struct sk_buff *skb);
 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
-		   int family, u8 prefixlen, int l3index,
+		   int family, u8 prefixlen, int l3index, u8 flags,
 		   const u8 *newkey, u8 newkeylen, gfp_t gfp);
 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
-		   int family, u8 prefixlen, int l3index);
+		   int family, u8 prefixlen, int l3index, u8 flags);
 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
 					 const struct sock *addr_sk);
 
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 2e62e0d6373a..5b8ce65dfc06 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1037,6 +1037,20 @@ static void tcp_v4_reqsk_destructor(struct request_sock *req)
 DEFINE_STATIC_KEY_FALSE(tcp_md5_needed);
 EXPORT_SYMBOL(tcp_md5_needed);
 
+static bool better_md5_match(struct tcp_md5sig_key *old, struct tcp_md5sig_key *new)
+{
+	if (!old)
+		return true;
+
+	/* l3index always overrides non-l3index */
+	if (old->l3index && new->l3index == 0)
+		return false;
+	if (old->l3index == 0 && new->l3index)
+		return true;
+
+	return old->prefixlen < new->prefixlen;
+}
+
 /* Find the Key structure for an address.  */
 struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index,
 					   const union tcp_md5_addr *addr,
@@ -1059,7 +1073,7 @@ struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index,
 				 lockdep_sock_is_held(sk)) {
 		if (key->family != family)
 			continue;
-		if (key->l3index && key->l3index != l3index)
+		if (key->flags & TCP_MD5SIG_FLAG_IFINDEX && key->l3index != l3index)
 			continue;
 		if (family == AF_INET) {
 			mask = inet_make_mask(key->prefixlen);
@@ -1074,8 +1088,7 @@ struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index,
 			match = false;
 		}
 
-		if (match && (!best_match ||
-			      key->prefixlen > best_match->prefixlen))
+		if (match && better_md5_match(best_match, key))
 			best_match = key;
 	}
 	return best_match;
@@ -1085,7 +1098,7 @@ EXPORT_SYMBOL(__tcp_md5_do_lookup);
 static struct tcp_md5sig_key *tcp_md5_do_lookup_exact(const struct sock *sk,
 						      const union tcp_md5_addr *addr,
 						      int family, u8 prefixlen,
-						      int l3index)
+						      int l3index, u8 flags)
 {
 	const struct tcp_sock *tp = tcp_sk(sk);
 	struct tcp_md5sig_key *key;
@@ -1105,7 +1118,9 @@ static struct tcp_md5sig_key *tcp_md5_do_lookup_exact(const struct sock *sk,
 				 lockdep_sock_is_held(sk)) {
 		if (key->family != family)
 			continue;
-		if (key->l3index && key->l3index != l3index)
+		if ((key->flags & TCP_MD5SIG_FLAG_IFINDEX) != (flags & TCP_MD5SIG_FLAG_IFINDEX))
+			continue;
+		if (key->l3index != l3index)
 			continue;
 		if (!memcmp(&key->addr, addr, size) &&
 		    key->prefixlen == prefixlen)
@@ -1129,7 +1144,7 @@ EXPORT_SYMBOL(tcp_v4_md5_lookup);
 
 /* This can be called on a newly created socket, from other files */
 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
-		   int family, u8 prefixlen, int l3index,
+		   int family, u8 prefixlen, int l3index, u8 flags,
 		   const u8 *newkey, u8 newkeylen, gfp_t gfp)
 {
 	/* Add Key to the list */
@@ -1137,7 +1152,7 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
 	struct tcp_sock *tp = tcp_sk(sk);
 	struct tcp_md5sig_info *md5sig;
 
-	key = tcp_md5_do_lookup_exact(sk, addr, family, prefixlen, l3index);
+	key = tcp_md5_do_lookup_exact(sk, addr, family, prefixlen, l3index, flags);
 	if (key) {
 		/* Pre-existing entry - just update that one.
 		 * Note that the key might be used concurrently.
@@ -1182,6 +1197,7 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
 	key->family = family;
 	key->prefixlen = prefixlen;
 	key->l3index = l3index;
+	key->flags = flags;
 	memcpy(&key->addr, addr,
 	       (family == AF_INET6) ? sizeof(struct in6_addr) :
 				      sizeof(struct in_addr));
@@ -1191,11 +1207,11 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
 EXPORT_SYMBOL(tcp_md5_do_add);
 
 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, int family,
-		   u8 prefixlen, int l3index)
+		   u8 prefixlen, int l3index, u8 flags)
 {
 	struct tcp_md5sig_key *key;
 
-	key = tcp_md5_do_lookup_exact(sk, addr, family, prefixlen, l3index);
+	key = tcp_md5_do_lookup_exact(sk, addr, family, prefixlen, l3index, flags);
 	if (!key)
 		return -ENOENT;
 	hlist_del_rcu(&key->node);
@@ -1229,6 +1245,7 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, int optname,
 	const union tcp_md5_addr *addr;
 	u8 prefixlen = 32;
 	int l3index = 0;
+	u8 flags;
 
 	if (optlen < sizeof(cmd))
 		return -EINVAL;
@@ -1239,6 +1256,8 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, int optname,
 	if (sin->sin_family != AF_INET)
 		return -EINVAL;
 
+	flags = cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX;
+
 	if (optname == TCP_MD5SIG_EXT &&
 	    cmd.tcpm_flags & TCP_MD5SIG_FLAG_PREFIX) {
 		prefixlen = cmd.tcpm_prefixlen;
@@ -1246,7 +1265,7 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, int optname,
 			return -EINVAL;
 	}
 
-	if (optname == TCP_MD5SIG_EXT &&
+	if (optname == TCP_MD5SIG_EXT && cmd.tcpm_ifindex &&
 	    cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX) {
 		struct net_device *dev;
 
@@ -1267,12 +1286,12 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, int optname,
 	addr = (union tcp_md5_addr *)&sin->sin_addr.s_addr;
 
 	if (!cmd.tcpm_keylen)
-		return tcp_md5_do_del(sk, addr, AF_INET, prefixlen, l3index);
+		return tcp_md5_do_del(sk, addr, AF_INET, prefixlen, l3index, flags);
 
 	if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
 		return -EINVAL;
 
-	return tcp_md5_do_add(sk, addr, AF_INET, prefixlen, l3index,
+	return tcp_md5_do_add(sk, addr, AF_INET, prefixlen, l3index, flags,
 			      cmd.tcpm_key, cmd.tcpm_keylen, GFP_KERNEL);
 }
 
@@ -1596,7 +1615,7 @@ struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
 		 * memory, then we end up not copying the key
 		 * across. Shucks.
 		 */
-		tcp_md5_do_add(newsk, addr, AF_INET, 32, l3index,
+		tcp_md5_do_add(newsk, addr, AF_INET, 32, l3index, key->flags,
 			       key->key, key->keylen, GFP_ATOMIC);
 		sk_nocaps_add(newsk, NETIF_F_GSO_MASK);
 	}
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 0ce52d46e4f8..b03dd02c9f13 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -599,6 +599,7 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
 	struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&cmd.tcpm_addr;
 	int l3index = 0;
 	u8 prefixlen;
+	u8 flags;
 
 	if (optlen < sizeof(cmd))
 		return -EINVAL;
@@ -609,6 +610,8 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
 	if (sin6->sin6_family != AF_INET6)
 		return -EINVAL;
 
+	flags = cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX;
+
 	if (optname == TCP_MD5SIG_EXT &&
 	    cmd.tcpm_flags & TCP_MD5SIG_FLAG_PREFIX) {
 		prefixlen = cmd.tcpm_prefixlen;
@@ -619,7 +622,7 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
 		prefixlen = ipv6_addr_v4mapped(&sin6->sin6_addr) ? 32 : 128;
 	}
 
-	if (optname == TCP_MD5SIG_EXT &&
+	if (optname == TCP_MD5SIG_EXT && cmd.tcpm_ifindex &&
 	    cmd.tcpm_flags & TCP_MD5SIG_FLAG_IFINDEX) {
 		struct net_device *dev;
 
@@ -640,9 +643,9 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
 		if (ipv6_addr_v4mapped(&sin6->sin6_addr))
 			return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin6->sin6_addr.s6_addr32[3],
 					      AF_INET, prefixlen,
-					      l3index);
+					      l3index, flags);
 		return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin6->sin6_addr,
-				      AF_INET6, prefixlen, l3index);
+				      AF_INET6, prefixlen, l3index, flags);
 	}
 
 	if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
@@ -650,12 +653,12 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
 
 	if (ipv6_addr_v4mapped(&sin6->sin6_addr))
 		return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin6->sin6_addr.s6_addr32[3],
-				      AF_INET, prefixlen, l3index,
+				      AF_INET, prefixlen, l3index, flags,
 				      cmd.tcpm_key, cmd.tcpm_keylen,
 				      GFP_KERNEL);
 
 	return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin6->sin6_addr,
-			      AF_INET6, prefixlen, l3index,
+			      AF_INET6, prefixlen, l3index, flags,
 			      cmd.tcpm_key, cmd.tcpm_keylen, GFP_KERNEL);
 }
 
@@ -1404,7 +1407,7 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
 		 * across. Shucks.
 		 */
 		tcp_md5_do_add(newsk, (union tcp_md5_addr *)&newsk->sk_v6_daddr,
-			       AF_INET6, 128, l3index, key->key, key->keylen,
+			       AF_INET6, 128, l3index, key->flags, key->key, key->keylen,
 			       sk_gfp_mask(sk, GFP_ATOMIC));
 	}
 #endif
diff --git a/tools/testing/selftests/net/fcnal-test.sh b/tools/testing/selftests/net/fcnal-test.sh
index 13350cd5c8ac..8e67a252b672 100755
--- a/tools/testing/selftests/net/fcnal-test.sh
+++ b/tools/testing/selftests/net/fcnal-test.sh
@@ -289,6 +289,12 @@ set_sysctl()
 	run_cmd sysctl -q -w $*
 }
 
+# get sysctl values in NS-A
+get_sysctl()
+{
+	${NSA_CMD} sysctl -n $*
+}
+
 ################################################################################
 # Setup for tests
 
@@ -1003,6 +1009,60 @@ ipv4_tcp_md5()
 	run_cmd nettest -s -I ${NSA_DEV} -M ${MD5_PW} -m ${NS_NET}
 	log_test $? 1 "MD5: VRF: Device must be a VRF - prefix"
 
+	test_ipv4_md5_vrf__vrf_server__no_bind_ifindex
+	test_ipv4_md5_vrf__global_server__bind_ifindex0
+}
+
+test_ipv4_md5_vrf__vrf_server__no_bind_ifindex()
+{
+	log_start
+	show_hint "Simulates applications using VRF without TCP_MD5SIG_FLAG_IFINDEX"
+	run_cmd nettest -s -I ${VRF} -M ${MD5_PW} -m ${NS_NET} --no-bind-key-ifindex &
+	sleep 1
+	run_cmd_nsb nettest -r ${NSA_IP} -X ${MD5_PW}
+	log_test $? 0 "MD5: VRF: VRF-bound server, unbound key accepts connection"
+
+	log_start
+	show_hint "Binding both the socket and the key is not required but it works"
+	run_cmd nettest -s -I ${VRF} -M ${MD5_PW} -m ${NS_NET} --force-bind-key-ifindex &
+	sleep 1
+	run_cmd_nsb nettest -r ${NSA_IP} -X ${MD5_PW}
+	log_test $? 0 "MD5: VRF: VRF-bound server, bound key accepts connection"
+}
+
+test_ipv4_md5_vrf__global_server__bind_ifindex0()
+{
+	# This particular test needs tcp_l3mdev_accept=1 for Global server to accept VRF connections
+	local old_tcp_l3mdev_accept
+	old_tcp_l3mdev_accept=$(get_sysctl net.ipv4.tcp_l3mdev_accept)
+	set_sysctl net.ipv4.tcp_l3mdev_accept=1
+
+	log_start
+	run_cmd nettest -s -M ${MD5_PW} -m ${NS_NET} --force-bind-key-ifindex &
+	sleep 1
+	run_cmd_nsb nettest -r ${NSA_IP} -X ${MD5_PW}
+	log_test $? 2 "MD5: VRF: Global server, Key bound to ifindex=0 rejects VRF connection"
+
+	log_start
+	run_cmd nettest -s -M ${MD5_PW} -m ${NS_NET} --force-bind-key-ifindex &
+	sleep 1
+	run_cmd_nsc nettest -r ${NSA_IP} -X ${MD5_PW}
+	log_test $? 0 "MD5: VRF: Global server, key bound to ifindex=0 accepts non-VRF connection"
+	log_start
+
+	run_cmd nettest -s -M ${MD5_PW} -m ${NS_NET} --no-bind-key-ifindex &
+	sleep 1
+	run_cmd_nsb nettest -r ${NSA_IP} -X ${MD5_PW}
+	log_test $? 0 "MD5: VRF: Global server, key not bound to ifindex accepts VRF connection"
+
+	log_start
+	run_cmd nettest -s -M ${MD5_PW} -m ${NS_NET} --no-bind-key-ifindex &
+	sleep 1
+	run_cmd_nsc nettest -r ${NSA_IP} -X ${MD5_PW}
+	log_test $? 0 "MD5: VRF: Global server, key not bound to ifindex accepts non-VRF connection"
+
+	# restore value
+	set_sysctl net.ipv4.tcp_l3mdev_accept="$old_tcp_l3mdev_accept"
 }
 
 ipv4_tcp_novrf()
diff --git a/tools/testing/selftests/net/nettest.c b/tools/testing/selftests/net/nettest.c
index bd6288302094..b599003eb5ba 100644
--- a/tools/testing/selftests/net/nettest.c
+++ b/tools/testing/selftests/net/nettest.c
@@ -28,6 +28,7 @@
 #include <unistd.h>
 #include <time.h>
 #include <errno.h>
+#include <getopt.h>
 
 #include <linux/xfrm.h>
 #include <linux/ipsec.h>
@@ -101,6 +102,8 @@ struct sock_args {
 		struct sockaddr_in6 v6;
 	} md5_prefix;
 	unsigned int prefix_len;
+	/* 0: default, -1: force off, +1: force on */
+	int bind_key_ifindex;
 
 	/* expected addresses and device index for connection */
 	const char *expected_dev;
@@ -271,11 +274,14 @@ static int tcp_md5sig(int sd, void *addr, socklen_t alen, struct sock_args *args
 	}
 	memcpy(&md5sig.tcpm_addr, addr, alen);
 
-	if (args->ifindex) {
+	if ((args->ifindex && args->bind_key_ifindex >= 0) || args->bind_key_ifindex >= 1) {
 		opt = TCP_MD5SIG_EXT;
 		md5sig.tcpm_flags |= TCP_MD5SIG_FLAG_IFINDEX;
 
 		md5sig.tcpm_ifindex = args->ifindex;
+		log_msg("TCP_MD5SIG_FLAG_IFINDEX set tcpm_ifindex=%d\n", md5sig.tcpm_ifindex);
+	} else {
+		log_msg("TCP_MD5SIG_FLAG_IFINDEX off\n", md5sig.tcpm_ifindex);
 	}
 
 	rc = setsockopt(sd, IPPROTO_TCP, opt, &md5sig, sizeof(md5sig));
@@ -1822,6 +1828,14 @@ static int ipc_parent(int cpid, int fd, struct sock_args *args)
 }
 
 #define GETOPT_STR  "sr:l:c:p:t:g:P:DRn:M:X:m:d:I:BN:O:SCi6xL:0:1:2:3:Fbq"
+#define OPT_FORCE_BIND_KEY_IFINDEX 1001
+#define OPT_NO_BIND_KEY_IFINDEX 1002
+
+static struct option long_opts[] = {
+	{"force-bind-key-ifindex", 0, 0, OPT_FORCE_BIND_KEY_IFINDEX},
+	{"no-bind-key-ifindex", 0, 0, OPT_NO_BIND_KEY_IFINDEX},
+	{0, 0, 0, 0}
+};
 
 static void print_usage(char *prog)
 {
@@ -1858,6 +1872,10 @@ static void print_usage(char *prog)
 	"    -M password   use MD5 sum protection\n"
 	"    -X password   MD5 password for client mode\n"
 	"    -m prefix/len prefix and length to use for MD5 key\n"
+	"    --no-bind-key-ifindex: Force TCP_MD5SIG_FLAG_IFINDEX off\n"
+	"    --force-bind-key-ifindex: Force TCP_MD5SIG_FLAG_IFINDEX on\n"
+	"        (default: only if -I is passed)\n"
+	"\n"
 	"    -g grp        multicast group (e.g., 239.1.1.1)\n"
 	"    -i            interactive mode (default is echo and terminate)\n"
 	"\n"
@@ -1893,7 +1911,7 @@ int main(int argc, char *argv[])
 	 * process input args
 	 */
 
-	while ((rc = getopt(argc, argv, GETOPT_STR)) != -1) {
+	while ((rc = getopt_long(argc, argv, GETOPT_STR, long_opts, NULL)) != -1) {
 		switch (rc) {
 		case 'B':
 			both_mode = 1;
@@ -1966,6 +1984,12 @@ int main(int argc, char *argv[])
 		case 'M':
 			args.password = optarg;
 			break;
+		case OPT_FORCE_BIND_KEY_IFINDEX:
+			args.bind_key_ifindex = 1;
+			break;
+		case OPT_NO_BIND_KEY_IFINDEX:
+			args.bind_key_ifindex = -1;
+			break;
 		case 'X':
 			args.client_pw = optarg;
 			break;