Busybox date does not support %N, this is GNU extension.
--- a/tests/scripts/common.sh
+++ b/tests/scripts/common.sh
@@ -59,7 +59,7 @@
 }
 
 # Find a port number not currently in use.
-GETPORT='rc=0; myrandom=$(date +%N | sed s/^0*//)
+GETPORT='rc=0; myrandom=$(date +%s | sed s/^0*//)
     while test $rc = 0;do
 	PORT="$(((($$<<15)|$myrandom) % 63001 + 2000))"
 	check_if_port_in_use $PORT;rc=$?