In this study the role of string matching algorithms in hardware/software applications in virus scanners or intrusion detection systems in improving data security over the internet is stressed. The author\'s contribution to an architectural design of a new string matching algorithm implemented on an FPGA for improving hardware based data security over the internet with improved performance over previously published results is reported. This can be used in applications such as hardware virus scanners or intrusion detection systems to further improve internet reliability in case of cyber attacks. After indicating the basic measures of intrinsic internet reliability such as MTTF, MTTR and availability, a new measure is introduced to account for the availability of the internet including the effect of cyber attacks. The new index that is introduced is a measure of downtime due to a cyber attack and is called mean down time due to cyber attack (MCADT). Results of empirical measurement of the intrinsic availability of a sample of 159 internet hosts in Iran using a developed software tool are presented and compared with those of a similar study over international hosts.

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