With the appearance of multi-gigabit network infrastructure, a typical network intrusion detection system (NIDS) has to cope with the network speed. By examining each packet flowing through a network segment, suspicious packets are detected and reported to assure security. Up to 57 % of the execution time in a NIDS is found to compare string against a predefined/known pattern. It is hard to implement a multigigabit performance NIDS without hardware support. This paper proposes a very high speed string matching algorithm which can be easily implemented into FPGAs. The parallel matching design takes a segment of text from the payload of a packet and detects all possible tokens including those crossing text segment boundaries. Simulation results show a throughput of 23.43 Gbps with a moderate operating frequency of 366.2 MHz.