  The objective of this is to develop a Fuzzy aided Application layer Semantic
Intrusion Detection System (FASIDS) which works in the application layer of the
network stack. FASIDS consist of semantic IDS and Fuzzy based IDS. Rule based
IDS looks for the specific pattern which is defined as malicious. A
non-intrusive regular pattern can be malicious if it occurs several times with
a short time interval. For detecting such malicious activities, FASIDS is
proposed in this paper. At application layer, HTTP traffic's header and payload
are analyzed for possible intrusion. In the proposed misuse detection module,
the semantic intrusion detection system works on the basis of rules that define
various application layer misuses that are found in the network. An attack
identified by the IDS is based on a corresponding rule in the rule-base. An
event that doesn't make a 'hit' on the rule-base is given to a Fuzzy Intrusion
Detection System (FIDS) for further analysis.
