On reliability of clock-skew-based remote computer identification

Clocks have a small in-built error. As the error is unique, each clock can be identified. This paper explores remote computer identification based on the estimation of clock skew computed from network packets. The previous knowledge of the method is expanded in various ways: (1) we argue about the amount of data that is necessary to get accurate clock skew estimation, (2) the study of different time stamp sources unveils several irregularities that hinders the identification, and (3) the distribution of clock skew in real network makes the precise identification hard or even impossible.