RFC 868

Time Protocol ✨

okay bestie, RFC 868 is the Time Protocol and it's giving clock-sync glow-up 💖🕰️

• Network Working Group, Request for Comments: 868 🌸
• Authors: J. Postel (ISI) and K. Harrenstien (SRI) 🧚
• Date: May 1983 📅
• Category: this one specifies a standard for the ARPA Internet community 👑
• Obsoletes: nothing listed 🙈
• Updates: nothing listed 🙈

This doc is for the ARPA Internet community. Hosts on the ARPA Internet that choose to implement a Time Protocol are expected to adopt and implement this standard 💅

The protocol gives you a site-independent, machine-readable date and time 🦋 The Time service sends the time back to whoever asked, as seconds since midnight on January first 1900.

Why do we even need this? 🤔 Not every system has a date/time clock, and everybody is subject to the occasional human or machine error 🙈 Time-servers let you quickly confirm or correct your system's idea of the time by making a brief poll of several independent sites on the network. Main character energy for your clock ✨

This protocol can run either above the Transmission Control Protocol (TCP) or above the User Datagram Protocol (UDP) 🎀

TCP Version 🧚

When you use TCP, the time service goes like this:

   S: Listen on port 37 (45 octal).

   U: Connect to port 37.

   S: Send the time as a 32 bit binary number.

   U: Receive the time.

   U: Close the connection.

   S: Close the connection.

The server listens for a connection on port 37. Once the connection is established, the server sends back a 32-bit time value and closes the connection 💜 If the server can't figure out the time at its site, it should either refuse the connection or close it without sending anything. Honest, no drama 😭

UDP Version 🌈

When you use UDP, the vibe is a little different:

   S: Listen on port 37 (45 octal).

   U: Send an empty datagram to port 37.

   S: Receive the empty datagram.

   S: Send a datagram containing the time as a 32 bit binary number.

   U: Receive the time datagram.

The server listens for a datagram on port 37. When one arrives, the server sends back a datagram with the 32-bit time value ⭐ If the server can't determine the time at its site, it should discard the arriving datagram and make no reply. Ghosted, but make it iconic 💀

The Time 🕰️

The time is the number of seconds since 00:00 (midnight) 1 January 1900 GMT. The time 1 is 12:00:01 am on 1 January 1900 GMT. This base will serve until the year 2036, so we're solid for a while 🔥

Here are some examples so you can see the math slay:

   the time  2,208,988,800 corresponds to 00:00  1 Jan 1970 GMT,

             2,398,291,200 corresponds to 00:00  1 Jan 1976 GMT,

             2,524,521,600 corresponds to 00:00  1 Jan 1980 GMT,

             2,629,584,000 corresponds to 00:00  1 May 1983 GMT,

        and -1,297,728,000 corresponds to 00:00 17 Nov 1858 GMT.

Bestie, that's the whole protocol 🌈💅 Clocks, polls, and seconds since 1900. Iconic 👑