While a supervision scripts runs in version 6, an error is logged in universe.log like the following:
|ERROR|X|IO |pid=p.t| u_io_thread_trt | New client XXX (/ on ) authentication failed: Connection closed (recv(socket=XXX, bytes=Y) returns 0)
Dollar Universe 6.x
Issue due to a network debugging command (nc) that would try to connect to the IO_X port without being authenticated that was being used to verify if the IO port was listening.
The command was:
nc -v -w 10 ${Node_Hostname} ${IO_X_PORT}
It is expected behaviour that the universe.log logs unauthenticated connection attemps that can occur during network security scans / inventories...
An authorized command like "$UNI_DIR_EXEC/uxlst fnc fnc=IO node=$nodename" shuld be used instead of nc commands to properly check the status of a remote node.