Methods and systems for using state ranges for processing regular expressions in intrusion-prevention systems

Methods and systems are provided for using state ranges for processing regular expressions in intrusion-prevention systems. In an embodiment, in an intrusion-prevention system for examining network traffic and identifying therein the presence of signature data patterns, a state-transition table is provided. The state-transition table is representative of a predetermined data pattern, and includes states each having one or more egress events defining transitions to other states. A subject is received for evaluation for the presence of the predetermined data pattern. While using the state-transition table for said evaluation, the presence of a first egress event of a first state is detected in the subject, resulting in a transition from the first state to a second state. A second-state range in the subject is calculated, and the second-state range is searched for the presence of at least one of the second state's egress events.