Wireshark - Wireshark is a network protocol analyzer for Unix and Windows. It lets you capture and interactively browse the traffic running on a computer network.

WatchDirectory - WatchDirectory monitors a file system directory and performs tasks when certain conditions are met.

Zabbix - Track, record, alert and visualize performance and availability of IT resources

Watch 4 Folder - Watch 4 Folder is a simple to use, small and portable tool to monitor folders and file activities.

Datadog - See metrics from all of your apps, tools & services in one place with Datadog's cloud monitoring as a service solution. Try it for free.

iWatch - iWatch is a realtime filesystem monitoring program.