An intrusion detection system (IDS) is a device or software application that monitors network or system activities for malicious activities or policy violations and produces reports to a management station. IDS come in a variety of “flavors” and approach the goal of detecting suspicious traffic in different ways. There are network based (NIDS) and host based (HIDS) intrusion detection systems.
Some systems may attempt to stop an intrusion attempt but this is neither required nor expected of a monitoring system. Intrusion detection and prevention systems (IDPS) are primarily focused on identifying possible incidents, logging information about them, and reporting attempts. In addition, organizations use IDPSes for other purposes, such as identifying problems with security policies, documenting existing threats and deterring individuals from violating security policies. IDPSes have become a necessary addition to the security infrastructure of nearly every organization.
A network-based intrusion prevention system (NIPS) is a system used to monitor a network as well as protect the confidentiality, integrity, and availability of a network. Its main functions include protecting the network from threats, such as denial of service (DoS) and unauthorized usage.
The NIPS monitors the network for malicious activity or suspicious traffic by analyzing the protocol activity. Once the NIPS is installed in a network, it is used to create physical security zones. This, in turn, makes the network intelligent and quickly discerns good traffic from bad traffic. In other words, the NIPS becomes like a prison for hostile traffic such as Trojans, worms, viruses, and polymorphic threats.
An intrusion prevention system (IPS) sits in-line on the network and monitors the traffic. When a suspicious event occurs, it takes action based on certain prescribed rules. An IPS is an active and real-time device unlike an intrusion detection system, which is not inline and is a passive device. IPSs are considered to be the evolution of the intrusion detection system.