There is provided a method for authenticating an attempt at establishment of a network connection by allowed code, comprising: providing a dataset having previously observed stack trace templates each representing a stack trace pattern prevailing in stack traces recorded by monitoring stacks of clients executing an allowed code during a connection establishment process for establishing network connections related to the allowed code; receiving a new stack trace recorded during a new connection establishment process for a new network connection by a new client; measuring a similarity between the new stack trace and the plurality of stack trace templates to identify a match to a stack trace template; evaluating the matched stack trace template for a predefined rule requirement; and updating a rule-set database with the matched stack trace template to authenticate new network connection establishments associated with stack templates matching the matched stack trace template.