Editing Intrusion detection system (section)

====Host intrusion detection systems====
{{Main|Host-based intrusion detection system}}
Host intrusion detection systems (HIDS) run on individual hosts or devices on the network. A HIDS monitors the inbound and outbound packets from the device only and will alert the user or administrator if suspicious activity is detected. It takes a snapshot of existing system files and matches it to the previous snapshot. If the critical system files were modified or deleted, an alert is sent to the administrator to investigate. An example of HIDS usage can be seen on mission critical machines, which are not expected to change their configurations.<ref>{{Cite book|url=https://books.google.com/books?id=6BgEAAAAMBAJ&q=host+IDS+%22mission+critical%22&pg=PT30|title=Network World|date=2003-09-15|publisher=IDG Network World Inc|language=en}}</ref><ref>{{Cite book|url=https://books.google.com/books?id=3iiLDQAAQBAJ&q=hids+%22mission+critical%22&pg=PT118|title=Network and Data Security for Non-Engineers|last1=Groom|first1=Frank M.|last2=Groom|first2=Kevin|last3=Jones|first3=Stephan S.|date=2016-08-19|publisher=CRC Press|isbn=9781315350219|language=en}}</ref>