There are provided a method of automated generation of a security rule-set and a system thereof. The method comprises: obtaining a group of log records of communication events resulting from traffic related to the security gateway; generating a preliminary rule-set of permissive rules, said set covering the obtained group of log records; generating, with the help of mapping the generated preliminary rule-set to the obtained group of log records, a rule-set of non-overlapping rules covering the group of log records; and generating an operational rule-set by processing the generated rule-set of non-overlapping rules, said processing including mapping the generated rule-set of non-overlapping rule to the obtained group of log records.