Abstract
Security of computer network hasbecome main
stream in most of networking field,during the past few years.
Today, mostdiscussions on computer security is centred on the
toolsor techniques used in protecting and defending networks.An
Intrusion detection system (IDS) is a security system that
monitorscomputer systems and network traffic and analyzes that
traffic for possible argumentativeattacks originating from outside
the organization and also for system misuse or attacksoriginating
from inside the organization. Intrusion detection is the method of
identifying unauthorizeduse, misuse, and abuse of computer
systems by both systeminsiders and external attackers. Our aim is
to discuss thefeasibility of monitoring the traffic of different
networks, toanalyze it for providing better security. For this
reason, we focuson all the components of intrusion sniffing and
response systemlike host and network based IDS. Intrusion
detection is theprocess used to identify intrusion. These techniques
have beenusually classified into HIDS and NIDS. In thispaper we
discuss main functionalities of IDS, characteristics ofIDS and
discussing few detection techniques they are
anomalybaseddetection, signature based, target monitoring,
StealthProbes.