Improve Accuracy and Reliability of TCP Timestamp-Based Uptime Calculation

[biandratti]

The current implementation for calculating remote system uptime based on TCP timestamps (check_ts_tcp in src/uptime.rs) has several areas where accuracy and reliability could be improved. While it attempts to guess common clock frequencies (100Hz, 1000Hz) and validates the raw calculated frequency, the resulting uptime can still be imprecise.

Evaluate with original implementation https://github.com/p0f/p0f/blob/master/fp_tcp.c

Even the original implementation (p0f) does not offer good quality, we need to investigate the best alternative.