diff --git a/tools/testing/selftests/netfilter/nat_masquerade_psid.sh b/tools/testing/selftests/netfilter/nat_masquerade_psid.sh
new file mode 100644
index 000000000000..56c1b509caf6
--- /dev/null
+++ b/tools/testing/selftests/netfilter/nat_masquerade_psid.sh
@@ -0,0 +1,182 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# <:copyright-gpl
+# Copyright (C) 2021 Allied Telesis Labs NZ
+#
+# check that NAT can masquerade using PSID defined ranges.
+#
+# Setup is:
+#
+# nsclient1(veth0) -> (veth1)nsrouter(veth2) -> (veth0)nsclient2
+# Setup a nat masquerade rule with psid defined ranges.
+#
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+ret=0
+ns_all="nsclient1 nsrouter nsclient2"
+
+readonly infile="$(mktemp)"
+readonly outfile="$(mktemp)"
+readonly datalen=32
+readonly server_port=8080
+
+conntrack -V > /dev/null 2>&1
+if [ $? -ne 0 ];then
+	echo "SKIP: Could not run test without conntrack tool"
+	exit $ksft_skip
+fi
+
+iptables --version > /dev/null 2>&1
+if [ $? -ne 0 ];then
+	echo "SKIP: Could not run test without iptables tool"
+	exit $ksft_skip
+fi
+
+ip -Version > /dev/null 2>&1
+if [ $? -ne 0 ];then
+	echo "SKIP: Could not run test without ip tool"
+	exit $ksft_skip
+fi
+
+ipv4() {
+	echo -n 192.168.$1.$2
+}
+
+cleanup() {
+	for n in $ns_all; do ip netns del $n;done
+
+	if [ -f "${outfile}" ]; then
+		rm "$outfile"
+	fi
+	if [ -f "${infile}" ]; then
+		rm "$infile"
+	fi
+}
+
+server_listen() {
+	ip netns exec nsclient2 nc -l -p "$server_port" > "$outfile" &
+	server_pid=$!
+	sleep 0.2
+}
+
+client_connect() {
+	ip netns exec nsclient1 timeout 2 nc -w 1 -p "$port" $(ipv4 2 2) "$server_port" < $infile
+}
+
+verify_data() {
+	local _ret=0
+	wait "$server_pid"
+	cmp "$infile" "$outfile" 2>/dev/null
+	_ret=$?
+	rm "$outfile"
+	return $_ret
+}
+
+test_service() {
+	server_listen
+	client_connect
+	verify_data
+}
+
+check_connection() {
+	local _ret=0
+	entry=$(ip netns exec nsrouter conntrack -p tcp --sport $port -L 2>&1)
+	entry=${entry##*sport=8080 dport=}
+	entry=${entry%% *}
+
+	if [[ "x$(( ($entry & $psid_mask) / $two_power_j ))" != "x$psid" ]]; then
+		_ret=1
+		echo "Failed psid mask check for $offset_len:$psid:$psid_length with port $entry"
+	fi
+
+	if [[ "x$_ret" = "x0" ]] &&
+	   [[ "x$offset_mask" != "x0" -a "x$(( ($entry & $offset_mask) ))" == "x0" ]]; then
+		_ret=1
+		echo "Failed offset mask check for $offset_len:$psid:$psid_length with port $entry"
+	fi
+	return $_ret
+}
+
+run_test() {
+	ip netns exec nsrouter iptables -A FORWARD -i veth1 -j ACCEPT
+	ip netns exec nsrouter iptables -P FORWARD DROP
+	ip netns exec nsrouter iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
+	ip netns exec nsrouter iptables -t nat --new psid
+	ip netns exec nsrouter iptables -t nat --insert psid -j MASQUERADE \
+		--psid $offset_len:$psid:$psid_length
+	ip netns exec nsrouter iptables -t nat -I POSTROUTING -o veth2 -j psid
+
+	# calculate psid mask
+	offset=$(( 1 << (16 - $offset_len) ))
+	two_power_j=$(( $offset / (1 << $psid_length) ))
+	offset_mask=$(( ( (1 << $offset_len) - 1 ) << (16 - $offset_len) ))
+	psid_mask=$(( ( (1 << $psid_length) - 1) * $two_power_j ))
+
+	# Create file
+	dd if=/dev/urandom of="${infile}" bs="${datalen}" count=1 >/dev/null 2>&1
+
+	# Test multiple ports
+	for p in 1 2 3 4 5; do
+		port=1080$p
+
+		test_service
+		if [ $? -ne 0 ]; then
+			ret=1
+			break
+		fi
+
+		check_connection
+		if [ $? -ne 0 ]; then
+			ret=1
+			break
+		fi
+	done
+
+	# tidy up test rules
+	ip netns exec nsrouter iptables -F
+	ip netns exec nsrouter iptables -t nat -F
+	ip netns exec nsrouter iptables -t nat -X psid
+}
+
+for n in $ns_all; do
+	ip netns add $n
+	ip -net $n link set lo up
+done
+
+for i in 1 2; do
+	ip link add veth0 netns nsclient$i type veth peer name veth$i netns nsrouter
+
+	ip -net nsclient$i link set veth0 up
+	ip -net nsclient$i addr add $(ipv4 $i 2)/24 dev veth0
+
+	ip -net nsrouter link set veth$i up
+	ip -net nsrouter addr add $(ipv4 $i 1)/24 dev veth$i
+done
+
+ip -net nsclient1 route add default via $(ipv4 1 1)
+ip -net nsclient2 route add default via $(ipv4 2 1)
+
+ip netns exec nsrouter sysctl -q net.ipv4.conf.all.forwarding=1
+
+offset_len=0
+psid_length=8
+for psid in 0 52; do
+	run_test
+	if [ $? -ne 0 ]; then
+		break
+	fi
+done
+
+offset_len=6
+psid_length=8
+for psid in 0 52; do
+	run_test
+	if [ $? -ne 0 ]; then
+		break
+	fi
+done
+
+cleanup
+exit $ret
