How do I receive data from NTP server?

Question

I have no idea why send data is 48 bytes 010,0,0..., someone can explain? the problem is buffer for data received, I don\'t know how big he should be, and even if I receive

Answer 1

Similar to my issue when trying to query the time from a self-hostet Windows-NTP-Server with the C++ library NTPClient which uses boost for the network tasks, msg[48] = { 010,0,0,0,0,0,0,0,0 }; configures the ntp.flags.mode. After comparing the network traffic of w32tm /stripchart /computer:10.159.96.65 using Wireshark, flag 27 or 11 seem to be the choices for my usecase: Comparison of NTP network packages

tmit = ntohl(((time_t*)tempBuffer)[6]); extracts the data from the received package. It looks like

• 4 yields the reference time (last sync with timeserver I assume),
• 8 the time when server received request and
• 10 the transmit time (which should be almost equal).