diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index cde041c93906..05859bb387ff 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -23,6 +23,7 @@ tmpfile=""
 cout=""
 err=""
 capout=""
+cappid=""
 ns1=""
 ns2=""
 iptables="iptables"
@@ -861,6 +862,44 @@ check_cestab()
 	fi
 }
 
+cond_start_capture()
+{
+	local ns="$1"
+
+	:> "$capout"
+
+	if $capture; then
+		local capuser capfile
+		if [ -z $SUDO_USER ]; then
+			capuser=""
+		else
+			capuser="-Z $SUDO_USER"
+		fi
+
+		capfile=$(printf "mp_join-%02u-%s.pcap" "$MPTCP_LIB_TEST_COUNTER" "$ns")
+
+		echo "Capturing traffic for test $MPTCP_LIB_TEST_COUNTER into $capfile"
+		ip netns exec "$ns" tcpdump -i any -s 65535 -B 32768 $capuser -w "$capfile" > "$capout" 2>&1 &
+		cappid=$!
+
+		sleep 1
+	fi
+}
+
+cond_stop_capture()
+{
+	if $capture; then
+		sleep 1
+		kill $cappid
+		cat "$capout"
+	fi
+}
+
+get_port()
+{
+	echo "$((10000 + MPTCP_LIB_TEST_COUNTER - 1))"
+}
+
 do_transfer()
 {
 	local listener_ns="$1"
@@ -868,33 +907,17 @@ do_transfer()
 	local cl_proto="$3"
 	local srv_proto="$4"
 	local connect_addr="$5"
+	local port
 
-	local port=$((10000 + MPTCP_LIB_TEST_COUNTER - 1))
-	local cappid
 	local FAILING_LINKS=${FAILING_LINKS:-""}
 	local fastclose=${fastclose:-""}
 	local speed=${speed:-"fast"}
+	port=$(get_port)
 
 	:> "$cout"
 	:> "$sout"
-	:> "$capout"
 
-	if $capture; then
-		local capuser
-		if [ -z $SUDO_USER ] ; then
-			capuser=""
-		else
-			capuser="-Z $SUDO_USER"
-		fi
-
-		capfile=$(printf "mp_join-%02u-%s.pcap" "$MPTCP_LIB_TEST_COUNTER" "${listener_ns}")
-
-		echo "Capturing traffic for test $MPTCP_LIB_TEST_COUNTER into $capfile"
-		ip netns exec ${listener_ns} tcpdump -i any -s 65535 -B 32768 $capuser -w $capfile > "$capout" 2>&1 &
-		cappid=$!
-
-		sleep 1
-	fi
+	cond_start_capture ${listener_ns}
 
 	NSTAT_HISTORY=/tmp/${listener_ns}.nstat ip netns exec ${listener_ns} \
 		nstat -n
@@ -981,10 +1004,7 @@ do_transfer()
 	wait $spid
 	local rets=$?
 
-	if $capture; then
-	    sleep 1
-	    kill $cappid
-	fi
+	cond_stop_capture
 
 	NSTAT_HISTORY=/tmp/${listener_ns}.nstat ip netns exec ${listener_ns} \
 		nstat | grep Tcp > /tmp/${listener_ns}.out
@@ -1000,7 +1020,6 @@ do_transfer()
 		ip netns exec ${connector_ns} ss -Menita 1>&2 -o "dport = :$port"
 		cat /tmp/${connector_ns}.out
 
-		cat "$capout"
 		return 1
 	fi
 
@@ -1017,13 +1036,7 @@ do_transfer()
 	fi
 	rets=$?
 
-	if [ $retc -eq 0 ] && [ $rets -eq 0 ];then
-		cat "$capout"
-		return 0
-	fi
-
-	cat "$capout"
-	return 1
+	[ $retc -eq 0 ] && [ $rets -eq 0 ]
 }
 
 make_file()
@@ -2786,6 +2799,32 @@ verify_listener_events()
 	fail_test
 }
 
+chk_mpc_endp_attempt()
+{
+	local retl=$1
+	local attempts=$2
+
+	print_check "Connect"
+
+	if [ ${retl} = 124 ]; then
+		fail_test "timeout on connect"
+	elif [ ${retl} = 0 ]; then
+		fail_test "unexpected successful connect"
+	else
+		print_ok
+
+		print_check "Attempts"
+		count=$(mptcp_lib_get_counter ${ns1} "MPTcpExtMPCapableEndpAttempt")
+		if [ -z "$count" ]; then
+			print_skip
+		elif [ "$count" != "$attempts" ]; then
+			fail_test "got ${count} MPC attempt[s] on port-based endpoint, expected ${attempts}"
+		else
+			print_ok
+		fi
+	fi
+}
+
 add_addr_ports_tests()
 {
 	# signal address with port
@@ -2876,6 +2915,22 @@ add_addr_ports_tests()
 		chk_join_nr 2 2 2
 		chk_add_nr 2 2 2
 	fi
+
+	if reset "port-based signal endpoint must not accept mpc"; then
+		local port retl count
+		port=$(get_port)
+
+		cond_start_capture ${ns1}
+		pm_nl_add_endpoint ${ns1} 10.0.2.1 flags signal port ${port}
+		mptcp_lib_wait_local_port_listen ${ns1} ${port}
+
+		timeout 1 ip netns exec ${ns2} \
+			./mptcp_connect -t ${timeout_poll} -p $port -s MPTCP 10.0.2.1 >/dev/null 2>&1
+		retl=$?
+		cond_stop_capture
+
+		chk_mpc_endp_attempt ${retl} 1
+	fi
 }
 
 syncookies_tests()