RFC 867

RFC 867: Daytime Protocol 🎀

okay bestie, this one is a standard from J. Postel at ISI, dated May 1983 💅 It's a spec for the ARPA Internet community, so hosts that want to run a Daytime Protocol are expected to adopt and implement it. The title block doesn't list anything it obsoletes or updates, so it's standing on its own ✨

The whole point of a daytime service is to be a useful debugging and measurement tool 🔥 It's super simple: it just sends back the current date and time as a character string, no matter what you send it 🦋

TCP Based Daytime Service

okay so the first flavor runs as a connection-based app on TCP 💖 A server listens for TCP connections on TCP port 13 🌸 Once a connection is set up, the current date and time gets sent down it as an ASCII character string. Anything you send is just thrown away 🗑️ and the service closes the connection after it sends the answer. bye bye 👋

UDP Based Daytime Service

the second flavor is a datagram app on UDP, and it's giving stateless vibes 🧚 A server listens for UDP datagrams on UDP port 13. When one comes in, it sends back an answering datagram with the current date and time as an ASCII character string. The data in the incoming datagram gets ignored, so it doesn't matter what you put in there 🙈

Daytime Syntax

there's no specific syntax for the daytime, which is lowkey iconic 💜 It is recommended that the output be limited to the ASCII printing characters, space, carriage return, and line feed. The daytime should also be just one line ✨

Here's one popular syntax:

   Weekday, Month Day, Year Time-Zone

   Example:

      Tuesday, February 22, 1982 17:37:43-PST

and here's another popular one, the one SMTP uses:

   dd mmm yy hh:mm:ss zzz

   Example:

      02 FEB 82 07:59:01 PST

⚠️ NOTE: if you need a machine-useful time, use the Time Protocol (RFC-868) instead. The daytime is for humans 🫶