Surveillance systems have been widely used in areas that need monitoring such as airports, railroads, banks, shopping malls, hospitals, schools, etc. The failure of these systems should be analyzed associated with the intrusion/incident arrival process (called intrusion process) in order to achieve a comprehensive representation of the system outcomes. In reliability model okf-out-onf-surveillance systems with this paper, we develop a generalized dual-stochastic-process complete four failure modes on the subsystem level, noted as fail-dangerous detectable, fail-dangerous undetectable, fail-safe detectable and fail-safe undetectable modes. The reliability of the system is derived with considerations of the intrusion process and a(m, d, T,) opportunistic maintenance policy. The closed-form reliability function of a triple-modular redundancy (TMR) is obtained. Numerical examples are given to demonstrate the validity of the modeling.