A host-based intrusion detection system (HIDS) is an intrusion detection system that monitors and analyzes the internals of a computing system as well as (in some cases) the network packets on its network interfaces (just like a network-based intrusion detection system (NIDS) would do). This was the first type of intrusion detection software to have been designed, with the original target system being the mainframe computer where outside interaction was infrequent.