[EMAIL PROTECTED] wrote: > On Dec 2, 9:34 pm, [EMAIL PROTECTED] (Danny Mayer) wrote: >> [EMAIL PROTECTED] wrote: >>> On Dec 1, 3:07 pm, Joseph Gwinn <[EMAIL PROTECTED]> wrote: >>>> In article >>>> <[EMAIL PROTECTED]>, >>>> [EMAIL PROTECTED] wrote: >>>>> Does anybody know of any *practical* samples on how to >>>>> implement NTP/SNTP client?. The goal is to provide accurate >>>>> time for a program/client running on Windows Vista. >>>>> Specifically, what values to include in the the request message, >>>>> how to process the reply message, etc. >>>>> I am NOT asking how to send/receive UDP datagrams, or where >>>>> to find comprehensive descriptions like RFC documents, or how >>>>> to build or design user interfaces. >>>>> Only a narrow description focused on NTP/SNTP request/reply >>>>> datagrams for a simple PC client, preferably in C/C++ source >>>>> code. >>>> I've done this in an embedded realtime system. (No, the source code is >>>> not available.) >>>> In Appendix A of RFC-1305 you will find the format of the NTPv3 >>>> request/response packet. Send this packet to port 123 of the NTP >>>> server, and read the reply packet. It's pretty easy. >>> I saw this format. From data comm point of view it is very unusual >>> to have the same format for request and reply. >> Why does that matter? The contents of the sending packet is slightly >> different from the reply. The client sends a mode 4 packet and receives >> back a mode 3 packet. The layout of the two packets are the same, the >> contents are appropriate for the mode. >> > > Actually, the client sends mode 3 and server responds with mode 4. >
Correct. My error. > In my original post I made an issue of the same ***format*** of NTP/ > SNTP > request and reply. This is very unusual in data comm. > Obviously, the requests and replies have to have different > ***contents*** > otherwise there would be no exchange of information. > > Just look at the NTP/SNTP request format and for ***every*** field > explain why would a client send it to a server. Do not pick just one > field like MODE, explain for ***all*** fields. > Read the NTPv4 draft: http://www.ietf.org/internet-drafts/draft-ietf-ntp-ntpv4-proto-08.txt which will tell you. If something is unclear or missing, send a message to the ntp working group. Danny _______________________________________________ questions mailing list questions@lists.ntp.org https://lists.ntp.org/mailman/listinfo/questions
