Computer controlled method, network server (42, 43, 44, 46, 48) and system (40) for detecting data patterns in a data stream (36) received by a computer (30). The data stream (36) comprising a plurality of data symbols. The computer (30) executes a finite automata (10) comprising a plurality of states (11, 12, 13, 14, 15) including a start state (11) and at least one accepting state (15). State transitions (16) are triggered by a data symbol (17a) according to a state transition register (17) and the method comprises the steps of determining (21), by the computer (30), from a data symbol register (18) whether a data symbol of the data stream (36) is comprised in a group of data symbols not resulting in an accepting state (15), and triggering (22), by the computer (30), a transition (16) to the start state (11) for data symbols comprised in the group and a transition (23) to a state (12, 13, 14, 15) according to the state transition register (17) for detecting the data pattern otherwise.