diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index db05b3764b77..80628bf8413a 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -38,6 +38,7 @@ TEST_PROGS += srv6_end_dt6_l3vpn_test.sh
 TEST_PROGS += vrf_strict_mode_test.sh
 TEST_PROGS += arp_ndisc_evict_nocarrier.sh
 TEST_PROGS += ndisc_unsolicited_na_test.sh
+TEST_PROGS += arp_ndisc_untracked_subnets.sh
 TEST_PROGS += stress_reuseport_listen.sh
 TEST_PROGS_EXTENDED := in_netns.sh setup_loopback.sh setup_veth.sh
 TEST_PROGS_EXTENDED += toeplitz_client.sh toeplitz.sh
diff --git a/tools/testing/selftests/net/arp_ndisc_untracked_subnets.sh b/tools/testing/selftests/net/arp_ndisc_untracked_subnets.sh
new file mode 100755
index 000000000000..c899b446acb6
--- /dev/null
+++ b/tools/testing/selftests/net/arp_ndisc_untracked_subnets.sh
@@ -0,0 +1,308 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# 2 namespaces: one host and one router. Use arping from the host to send a
+# garp to the router. Router accepts or ignores based on its arp_accept
+# or accept_untracked_na configuration.
+
+TESTS="arp ndisc"
+
+ROUTER_NS="ns-router"
+ROUTER_NS_V6="ns-router-v6"
+ROUTER_INTF="veth-router"
+ROUTER_ADDR="10.0.10.1"
+ROUTER_ADDR_V6="2001:db8:abcd:0012::1"
+
+HOST_NS="ns-host"
+HOST_NS_V6="ns-host-v6"
+HOST_INTF="veth-host"
+HOST_ADDR="10.0.10.2"
+HOST_ADDR_V6="2001:db8:abcd:0012::2"
+
+SUBNET_WIDTH=24
+PREFIX_WIDTH_V6=64
+
+cleanup() {
+	ip netns del ${HOST_NS}
+	ip netns del ${ROUTER_NS}
+}
+
+cleanup_v6() {
+	ip netns del ${HOST_NS_V6}
+	ip netns del ${ROUTER_NS_V6}
+}
+
+setup() {
+	set -e
+	local arp_accept=$1
+
+	# Set up two namespaces
+	ip netns add ${ROUTER_NS}
+	ip netns add ${HOST_NS}
+
+	# Set up interfaces veth0 and veth1, which are pairs in separate
+	# namespaces. veth0 is veth-router, veth1 is veth-host.
+	# first, set up the inteface's link to the namespace
+	# then, set the interface "up"
+	ip netns exec ${ROUTER_NS} ip link add name ${ROUTER_INTF} \
+		type veth peer name ${HOST_INTF}
+
+	ip netns exec ${ROUTER_NS} ip link set dev ${ROUTER_INTF} up
+	ip netns exec ${ROUTER_NS} ip link set dev ${HOST_INTF} netns ${HOST_NS}
+
+	ip netns exec ${HOST_NS} ip link set dev ${HOST_INTF} up
+	ip netns exec ${ROUTER_NS} ip addr add ${ROUTER_ADDR}/${SUBNET_WIDTH} \
+		dev ${ROUTER_INTF}
+
+	ip netns exec ${HOST_NS} ip addr add ${HOST_ADDR}/${SUBNET_WIDTH} \
+		dev ${HOST_INTF}
+	ip netns exec ${HOST_NS} ip route add default via ${HOST_ADDR} \
+		dev ${HOST_INTF}
+	ip netns exec ${ROUTER_NS} ip route add default via ${ROUTER_ADDR} \
+		dev ${ROUTER_INTF}
+
+	ROUTER_CONF=net.ipv4.conf.${ROUTER_INTF}
+	ip netns exec ${ROUTER_NS} sysctl -w \
+		${ROUTER_CONF}.arp_accept=${arp_accept} >/dev/null 2>&1
+	set +e
+}
+
+setup_v6() {
+	set -e
+	local accept_untracked_na=$1
+
+	# Set up two namespaces
+	ip netns add ${ROUTER_NS_V6}
+	ip netns add ${HOST_NS_V6}
+
+	# Set up interfaces veth0 and veth1, which are pairs in separate
+	# namespaces. veth0 is veth-router, veth1 is veth-host.
+	# first, set up the inteface's link to the namespace
+	# then, set the interface "up"
+	ip -6 -netns ${ROUTER_NS_V6} link add name ${ROUTER_INTF} \
+		type veth peer name ${HOST_INTF}
+
+	ip -6 -netns ${ROUTER_NS_V6} link set dev ${ROUTER_INTF} up
+	ip -6 -netns ${ROUTER_NS_V6} link set dev ${HOST_INTF} netns \
+		${HOST_NS_V6}
+
+	ip -6 -netns ${HOST_NS_V6} link set dev ${HOST_INTF} up
+	ip -6 -netns ${ROUTER_NS_V6} addr add \
+		${ROUTER_ADDR_V6}/${PREFIX_WIDTH_V6} dev ${ROUTER_INTF} nodad
+
+	HOST_CONF=net.ipv6.conf.${HOST_INTF}
+	ip netns exec ${HOST_NS_V6} sysctl -qw ${HOST_CONF}.ndisc_notify=1
+	ip netns exec ${HOST_NS_V6} sysctl -qw ${HOST_CONF}.disable_ipv6=0
+	ip -6 -netns ${HOST_NS_V6} addr add ${HOST_ADDR_V6}/${PREFIX_WIDTH_V6} \
+		dev ${HOST_INTF}
+
+	ROUTER_CONF=net.ipv6.conf.${ROUTER_INTF}
+
+	ip netns exec ${ROUTER_NS_V6} sysctl -w \
+		${ROUTER_CONF}.forwarding=1 >/dev/null 2>&1
+	ip netns exec ${ROUTER_NS_V6} sysctl -w \
+		${ROUTER_CONF}.drop_unsolicited_na=0 >/dev/null 2>&1
+	ip netns exec ${ROUTER_NS_V6} sysctl -w \
+		${ROUTER_CONF}.accept_untracked_na=${accept_untracked_na} \
+		>/dev/null 2>&1
+	set +e
+}
+
+verify_arp() {
+	local arp_accept=$1
+	local same_subnet=$2
+
+	neigh_show_output=$(ip netns exec ${ROUTER_NS} ip neigh get \
+		${HOST_ADDR} dev ${ROUTER_INTF} 2>/dev/null)
+
+	if [ ${arp_accept} -eq 1 ]; then
+		# Neighbor entries expected
+		[[ ${neigh_show_output} ]]
+	elif [ ${arp_accept} -eq 2 ]; then
+		if [ ${same_subnet} -eq 1 ]; then
+			# Neighbor entries expected
+			[[ ${neigh_show_output} ]]
+		else
+			[[ -z "${neigh_show_output}" ]]
+		fi
+	else
+		[[ -z "${neigh_show_output}" ]]
+	fi
+ }
+
+arp_test_gratuitous() {
+	set -e
+	local arp_accept=$1
+	local same_subnet=$2
+
+	if [ ${arp_accept} -eq 2 ]; then
+		test_msg=("test_arp: "
+			  "accept_arp=$1 "
+			  "same_subnet=$2")
+		if [ ${same_subnet} -eq 0 ]; then
+			HOST_ADDR=10.0.11.3
+		else
+			HOST_ADDR=10.0.10.3
+		fi
+	else
+		test_msg=("test_arp: "
+			  "accept_arp=$1")
+	fi
+	# Supply arp_accept option to set up which sets it in sysctl
+	setup ${arp_accept}
+	ip netns exec ${HOST_NS} arping -A -U ${HOST_ADDR} -c1 2>&1 >/dev/null
+
+	if verify_arp $1 $2; then
+		printf "    TEST: %-60s  [ OK ]\n" "${test_msg[*]}"
+	else
+		printf "    TEST: %-60s  [FAIL]\n" "${test_msg[*]}"
+	fi
+	cleanup
+	set +e
+}
+
+arp_test_gratuitous_combinations() {
+	arp_test_gratuitous 0
+	arp_test_gratuitous 1
+	arp_test_gratuitous 2 0 # Second entry indicates subnet or not
+	arp_test_gratuitous 2 1
+}
+
+cleanup_tcpdump() {
+	set -e
+	[[ ! -z  ${tcpdump_stdout} ]] && rm -f ${tcpdump_stdout}
+	[[ ! -z  ${tcpdump_stderr} ]] && rm -f ${tcpdump_stderr}
+	tcpdump_stdout=
+	tcpdump_stderr=
+	set +e
+}
+
+start_tcpdump() {
+	set -e
+	tcpdump_stdout=`mktemp`
+	tcpdump_stderr=`mktemp`
+	ip netns exec ${ROUTER_NS_V6} timeout 15s \
+		tcpdump --immediate-mode -tpni ${ROUTER_INTF} -c 1 \
+		"icmp6 && icmp6[0] == 136 && src ${HOST_ADDR_V6}" \
+		> ${tcpdump_stdout} 2> /dev/null
+	set +e
+}
+
+verify_ndisc() {
+	local accept_untracked_na=$1
+	local same_subnet=$2
+
+	neigh_show_output=$(ip -6 -netns ${ROUTER_NS_V6} neigh show \
+		to ${HOST_ADDR_V6} dev ${ROUTER_INTF} nud stale)
+
+	if [ ${accept_untracked_na} -eq 1 ]; then
+		# Neighbour entry expected to be present
+		[[ ${neigh_show_output} ]]
+	elif [ ${accept_untracked_na} -eq 2 ]; then
+		if [ ${same_subnet} -eq 1 ]; then
+			[[ ${neigh_show_output} ]]
+		else
+			[[ -z "${neigh_show_output}" ]]
+		fi
+	else
+		# Neighbour entry expected to be absent for all other cases
+		[[ -z "${neigh_show_output}" ]]
+	fi
+}
+
+ndisc_test_untracked_advertisements() {
+	set -e
+	test_msg=("test_ndisc: "
+		  "accept_untracked_na=$1")
+
+	local accept_untracked_na=$1
+	local same_subnet=$2
+	if [ ${accept_untracked_na} -eq 2 ]; then
+		test_msg=("test_ndisc: "
+			  "accept_untracked_na=$1 "
+			  "same_subnet=$2")
+		if [ ${same_subnet} -eq 0 ]; then
+			# Not same subnet
+			HOST_ADDR_V6=2000:db8:abcd:0013::4
+		else
+			HOST_ADDR_V6=2001:db8:abcd:0012::3
+		fi
+	fi
+	setup_v6 $1 $2
+	start_tcpdump
+
+	if verify_ndisc $1 $2; then
+		printf "    TEST: %-60s  [ OK ]\n" "${test_msg[*]}"
+	else
+		printf "    TEST: %-60s  [FAIL]\n" "${test_msg[*]}"
+	fi
+
+	cleanup_tcpdump
+	cleanup_v6
+	set +e
+}
+
+ndisc_test_untracked_combinations() {
+	ndisc_test_untracked_advertisements 0
+	ndisc_test_untracked_advertisements 1
+	ndisc_test_untracked_advertisements 2 0
+	ndisc_test_untracked_advertisements 2 1
+}
+
+################################################################################
+# usage
+
+usage()
+{
+	cat <<EOF
+usage: ${0##*/} OPTS
+
+	-t <test>       Test(s) to run (default: all)
+			(options: $TESTS)
+EOF
+}
+
+################################################################################
+# main
+
+while getopts ":t:h" opt; do
+	case $opt in
+		t) TESTS=$OPTARG;;
+		h) usage; exit 0;;
+		*) usage; exit 1;;
+	esac
+done
+
+if [ "$(id -u)" -ne 0 ];then
+	echo "SKIP: Need root privileges"
+	exit $ksft_skip;
+fi
+
+if [ ! -x "$(command -v ip)" ]; then
+	echo "SKIP: Could not run test without ip tool"
+	exit $ksft_skip
+fi
+
+if [ ! -x "$(command -v tcpdump)" ]; then
+	echo "SKIP: Could not run test without tcpdump tool"
+	exit $ksft_skip
+fi
+
+if [ ! -x "$(command -v arping)" ]; then
+	echo "SKIP: Could not run test without arping tool"
+	exit $ksft_skip
+fi
+
+# start clean
+cleanup &> /dev/null
+cleanup_v6 &> /dev/null
+
+for t in $TESTS
+do
+	case $t in
+	arp_test_gratuitous_combinations|arp) arp_test_gratuitous_combinations;;
+	ndisc_test_untracked_combinations|ndisc) \
+		ndisc_test_untracked_combinations;;
+	help) echo "Test names: $TESTS"; exit 0;;
+esac
+done