Network packet analyzer and computer program product.

A computer program product comprising a non-transitory computer-readable recording medium on which an executable program to be executed by a computer is recorded, the computer including a memory to store a plurality of sets of training data in which semantics of one protocol field and one or more patterns indicating characteristics of variations of the parameters of the one protocol field are associated with each other, the executable program instructing the computer to:

• capture a network packets and extract a variable field whose parameter varies in time series;
• generate, based on the parameter varying in the time series in the variable field, one or more patterns indicating a characteristic of a variation of the parameter;
• and
• compare each of the one or more patterns with each of the one or more patterns of the training data and estimate the semantics of the variable field.