diff --git a/tools/testing/selftests/net/mptcp/diag.sh b/tools/testing/selftests/net/mptcp/diag.sh
index 95b498efacd1f..13c677cc29995 100755
--- a/tools/testing/selftests/net/mptcp/diag.sh
+++ b/tools/testing/selftests/net/mptcp/diag.sh
@@ -3,9 +3,7 @@
 
 . "$(dirname "${0}")/mptcp_lib.sh"
 
-sec=$(date +%s)
-rndh=$(printf %x $sec)-$(mktemp -u XXXXXX)
-ns="ns1-$rndh"
+mptcp_lib_init_ns
 ksft_skip=4
 test_cnt=1
 timeout_poll=100
@@ -18,19 +16,19 @@ flush_pids()
 	# give it some time
 	sleep 1.1
 
-	ip netns pids "${ns}" | xargs --no-run-if-empty kill -SIGUSR1 &>/dev/null
+	ip netns pids "${ns1}" | xargs --no-run-if-empty kill -SIGUSR1 &>/dev/null
 
 	for _ in $(seq 10); do
-		[ -z "$(ip netns pids "${ns}")" ] && break
+		[ -z "$(ip netns pids "${ns1}")" ] && break
 		sleep 0.1
 	done
 }
 
 cleanup()
 {
-	ip netns pids "${ns}" | xargs --no-run-if-empty kill -SIGKILL &>/dev/null
+	ip netns pids "${ns1}" | xargs --no-run-if-empty kill -SIGKILL &>/dev/null
 
-	ip netns del $ns
+	ip netns del $ns1
 }
 
 mptcp_lib_check_mptcp
@@ -48,7 +46,7 @@ fi
 
 get_msk_inuse()
 {
-	ip netns exec $ns cat /proc/net/protocols | awk '$1~/^MPTCP$/{print $3}'
+	ip netns exec $ns1 cat /proc/net/protocols | awk '$1~/^MPTCP$/{print $3}'
 }
 
 __chk_nr()
@@ -83,7 +81,7 @@ __chk_msk_nr()
 	local condition=$1
 	shift 1
 
-	__chk_nr "ss -inmHMN $ns | $condition" "$@"
+	__chk_nr "ss -inmHMN $ns1 | $condition" "$@"
 }
 
 chk_msk_nr()
@@ -104,7 +102,7 @@ wait_msk_nr()
 	msg=$*
 
 	while [ $i -lt $timeout ]; do
-		nr=$(ss -inmHMN $ns | $condition)
+		nr=$(ss -inmHMN $ns1 | $condition)
 		[ $nr == $expected ] && break;
 		[ $nr -gt $max ] && max=$nr
 		i=$((i + 1))
@@ -143,7 +141,7 @@ __chk_listen()
 	local expected=$2
 	local msg="$3"
 
-	__chk_nr "ss -N $ns -Ml '$filter' | grep -c LISTEN" "$expected" "$msg" 0
+	__chk_nr "ss -N $ns1 -Ml '$filter' | grep -c LISTEN" "$expected" "$msg" 0
 }
 
 chk_msk_listen()
@@ -169,7 +167,7 @@ chk_msk_inuse()
 	local msg="$2"
 	local listen_nr
 
-	listen_nr=$(ss -N "${ns}" -Ml | grep -c LISTEN)
+	listen_nr=$(ss -N "${ns1}" -Ml | grep -c LISTEN)
 	expected=$((expected + listen_nr))
 
 	for _ in $(seq 10); do
@@ -197,24 +195,24 @@ wait_connected()
 }
 
 trap cleanup EXIT
-ip netns add $ns
-ip -n $ns link set dev lo up
+ip netns add $ns1
+ip -n $ns1 link set dev lo up
 
 echo "a" | \
 	timeout ${timeout_test} \
-		ip netns exec $ns \
+		ip netns exec $ns1 \
 			./mptcp_connect -p 10000 -l -t ${timeout_poll} -w 20 \
 				0.0.0.0 >/dev/null &
-mptcp_lib_wait_local_port_listen $ns 10000
+mptcp_lib_wait_local_port_listen $ns1 10000
 chk_msk_nr 0 "no msk on netns creation"
 chk_msk_listen 10000
 
 echo "b" | \
 	timeout ${timeout_test} \
-		ip netns exec $ns \
+		ip netns exec $ns1 \
 			./mptcp_connect -p 10000 -r 0 -t ${timeout_poll} -w 20 \
 				127.0.0.1 >/dev/null &
-wait_connected $ns 10000
+wait_connected $ns1 10000
 chk_msk_nr 2 "after MPC handshake "
 chk_msk_remote_key_nr 2 "....chk remote_key"
 chk_msk_fallback_nr 0 "....chk no fallback"
@@ -225,16 +223,16 @@ chk_msk_inuse 0 "....chk 0 msk in use after flush"
 
 echo "a" | \
 	timeout ${timeout_test} \
-		ip netns exec $ns \
+		ip netns exec $ns1 \
 			./mptcp_connect -p 10001 -l -s TCP -t ${timeout_poll} -w 20 \
 				0.0.0.0 >/dev/null &
-mptcp_lib_wait_local_port_listen $ns 10001
+mptcp_lib_wait_local_port_listen $ns1 10001
 echo "b" | \
 	timeout ${timeout_test} \
-		ip netns exec $ns \
+		ip netns exec $ns1 \
 			./mptcp_connect -p 10001 -r 0 -t ${timeout_poll} -w 20 \
 				127.0.0.1 >/dev/null &
-wait_connected $ns 10001
+wait_connected $ns1 10001
 chk_msk_fallback_nr 1 "check fallback"
 chk_msk_inuse 1 "....chk 1 msk in use"
 flush_pids
@@ -245,16 +243,16 @@ NR_CLIENTS=100
 for I in `seq 1 $NR_CLIENTS`; do
 	echo "a" | \
 		timeout ${timeout_test} \
-			ip netns exec $ns \
+			ip netns exec $ns1 \
 				./mptcp_connect -p $((I+10001)) -l -w 20 \
 					-t ${timeout_poll} 0.0.0.0 >/dev/null &
 done
-mptcp_lib_wait_local_port_listen $ns $((NR_CLIENTS + 10001))
+mptcp_lib_wait_local_port_listen $ns1 $((NR_CLIENTS + 10001))
 
 for I in `seq 1 $NR_CLIENTS`; do
 	echo "b" | \
 		timeout ${timeout_test} \
-			ip netns exec $ns \
+			ip netns exec $ns1 \
 				./mptcp_connect -p $((I+10001)) -w 20 \
 					-t ${timeout_poll} 127.0.0.1 >/dev/null &
 done
diff --git a/tools/testing/selftests/net/mptcp/mptcp_connect.sh b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
index 7898d62fce0b5..8a0ce9ed1e9ea 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_connect.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_connect.sh
@@ -121,12 +121,7 @@ while getopts "$optstring" option;do
 	esac
 done
 
-sec=$(date +%s)
-rndh=$(printf %x $sec)-$(mktemp -u XXXXXX)
-ns1="ns1-$rndh"
-ns2="ns2-$rndh"
-ns3="ns3-$rndh"
-ns4="ns4-$rndh"
+mptcp_lib_init_ns
 
 TEST_COUNT=0
 TEST_GROUP=""
diff --git a/tools/testing/selftests/net/mptcp/mptcp_join.sh b/tools/testing/selftests/net/mptcp/mptcp_join.sh
index ae58a38d941b9..8109f92e56a09 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_join.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_join.sh
@@ -22,8 +22,6 @@ cinsent=""
 tmpfile=""
 cout=""
 capout=""
-ns1=""
-ns2=""
 ksft_skip=4
 iptables="iptables"
 ip6tables="ip6tables"
@@ -79,12 +77,7 @@ init_partial()
 {
 	capout=$(mktemp)
 
-	local sec rndh
-	sec=$(date +%s)
-	rndh=$(printf %x $sec)-$(mktemp -u XXXXXX)
-
-	ns1="ns1-$rndh"
-	ns2="ns2-$rndh"
+	mptcp_lib_init_ns
 
 	local netns
 	for netns in "$ns1" "$ns2"; do
diff --git a/tools/testing/selftests/net/mptcp/mptcp_lib.sh b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
index 0aea2c5175d55..ee5a5b9adc476 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_lib.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_lib.sh
@@ -15,6 +15,12 @@ MPTCP_LIB_LISTENER_CLOSED=16  #MPTCP_EVENT_LISTENER_CLOSED
 readonly AF_INET=2
 readonly AF_INET6=10
 
+rndh=""
+ns1=""
+ns2=""
+ns3=""
+ns4=""
+
 MPTCP_LIB_SUBTESTS=()
 
 # only if supported (or forced) and not disabled, see no-color.org
@@ -443,3 +449,15 @@ mptcp_lib_verify_listener_events() {
 
 	mptcp_lib_check_expected "type" "family" "saddr" "sport"
 }
+
+mptcp_lib_init_ns() {
+	local sec
+
+	sec=$(date +%s)
+	rndh=$(printf %x $sec)-$(mktemp -u XXXXXX)
+
+	ns1="ns1-$rndh"
+	ns2="ns2-$rndh"
+	ns3="ns3-$rndh"
+	ns4="ns4-$rndh"
+}
diff --git a/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh b/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
index c643872ddf478..f4dfeaf52c738 100755
--- a/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
+++ b/tools/testing/selftests/net/mptcp/mptcp_sockopt.sh
@@ -14,11 +14,7 @@ timeout_test=$((timeout_poll * 2 + 1))
 iptables="iptables"
 ip6tables="ip6tables"
 
-sec=$(date +%s)
-rndh=$(printf %x $sec)-$(mktemp -u XXXXXX)
-ns1="ns1-$rndh"
-ns2="ns2-$rndh"
-ns_sbox="ns_sbox-$rndh"
+mptcp_lib_init_ns
 
 add_mark_rules()
 {
@@ -41,7 +37,7 @@ add_mark_rules()
 init()
 {
 	local netns
-	for netns in "$ns1" "$ns2" "$ns_sbox";do
+	for netns in "$ns1" "$ns2" "$ns3";do
 		ip netns add $netns || exit $ksft_skip
 		ip -net $netns link set lo up
 		ip netns exec $netns sysctl -q net.mptcp.enabled=1
@@ -80,7 +76,7 @@ init()
 cleanup()
 {
 	local netns
-	for netns in "$ns1" "$ns2" "$ns_sbox"; do
+	for netns in "$ns1" "$ns2" "$ns3"; do
 		ip netns del $netns
 	done
 	rm -f "$cin" "$cout"
@@ -240,7 +236,7 @@ do_mptcp_sockopt_tests()
 		return
 	fi
 
-	ip netns exec "$ns_sbox" ./mptcp_sockopt
+	ip netns exec "$ns3" ./mptcp_sockopt
 	lret=$?
 
 	if [ $lret -ne 0 ]; then
@@ -251,7 +247,7 @@ do_mptcp_sockopt_tests()
 	fi
 	mptcp_lib_result_pass "sockopt v4"
 
-	ip netns exec "$ns_sbox" ./mptcp_sockopt -6
+	ip netns exec "$ns3" ./mptcp_sockopt -6
 	lret=$?
 
 	if [ $lret -ne 0 ]; then
@@ -282,7 +278,7 @@ run_tests()
 
 do_tcpinq_test()
 {
-	ip netns exec "$ns_sbox" ./mptcp_inq "$@"
+	ip netns exec "$ns3" ./mptcp_inq "$@"
 	local lret=$?
 	if [ $lret -ne 0 ];then
 		ret=$lret
diff --git a/tools/testing/selftests/net/mptcp/pm_netlink.sh b/tools/testing/selftests/net/mptcp/pm_netlink.sh
index 8f4ff123a7eb9..1208cba4797f3 100755
--- a/tools/testing/selftests/net/mptcp/pm_netlink.sh
+++ b/tools/testing/selftests/net/mptcp/pm_netlink.sh
@@ -24,9 +24,7 @@ while getopts "$optstring" option;do
 	esac
 done
 
-sec=$(date +%s)
-rndh=$(printf %x $sec)-$(mktemp -u XXXXXX)
-ns1="ns1-$rndh"
+mptcp_lib_init_ns
 err=$(mktemp)
 ret=0
 
diff --git a/tools/testing/selftests/net/mptcp/simult_flows.sh b/tools/testing/selftests/net/mptcp/simult_flows.sh
index ae8ad5d6fb9da..8f8bad051b1ff 100755
--- a/tools/testing/selftests/net/mptcp/simult_flows.sh
+++ b/tools/testing/selftests/net/mptcp/simult_flows.sh
@@ -3,11 +3,7 @@
 
 . "$(dirname "${0}")/mptcp_lib.sh"
 
-sec=$(date +%s)
-rndh=$(printf %x $sec)-$(mktemp -u XXXXXX)
-ns1="ns1-$rndh"
-ns2="ns2-$rndh"
-ns3="ns3-$rndh"
+mptcp_lib_init_ns
 capture=false
 ksft_skip=4
 timeout_poll=30
diff --git a/tools/testing/selftests/net/mptcp/userspace_pm.sh b/tools/testing/selftests/net/mptcp/userspace_pm.sh
index f99edce8171f3..03b9353d93f3c 100755
--- a/tools/testing/selftests/net/mptcp/userspace_pm.sh
+++ b/tools/testing/selftests/net/mptcp/userspace_pm.sh
@@ -44,10 +44,7 @@ app6_port=50004
 client_addr_id=${RANDOM:0:2}
 server_addr_id=${RANDOM:0:2}
 
-sec=$(date +%s)
-rndh=$(printf %x "$sec")-$(mktemp -u XXXXXX)
-ns1="ns1-$rndh"
-ns2="ns2-$rndh"
+mptcp_lib_init_ns
 ret=0
 test_name=""