nfsen-ng - nfsen-ng aims to be an in-place replacement for the ageing nfsen.
DaemonFS - DaemonFS is a real time file monitoring software.
Zabbix - Track, record, alert and visualize performance and availability of IT resources
WatchDirectory - WatchDirectory monitors a file system directory and performs tasks when certain conditions are met.
FastNetMon - FastNetMon is a very fast DDoS analyzer with sflow/netflow/mirror support.
iWatch - iWatch is a realtime filesystem monitoring program.