The netprobe has been started without a logfile defined and is writing messages to STDOUT.
This occurs when the user explicitly starts the netprobe with the "-nolog" option, in which case the netprobe will write to stdout.
Many times users will redirect stdout to a file e.g. netprobe.linux -nolog &> custom.log
Unfortunately, there is no way for the netprobe to know what its logfile is under this configuration.