Daytime Protocol
Defines a service that returns the current date and time as text.
Postel, J., "Daytime Protocol", STD 25, RFC 867, DOI 10.17487/RFC0867, May 1983, <https://www.rfc-editor.org/info/rfc867>.
@misc{rfc867,
series = {Request for Comments},
number = 867,
howpublished = {RFC 867},
publisher = {RFC Editor},
doi = {10.17487/RFC0867},
url = {https://www.rfc-editor.org/info/rfc867},
author = {J. Postel},
title = {{Daytime Protocol}},
pagetotal = 2,
year = 1983,
month = may,
} RFC text
Network Working Group J. Postel
Request for Comments: 867 ISI
May 1983
Daytime Protocol
This RFC specifies a standard for the ARPA Internet community. Hosts on
the ARPA Internet that choose to implement a Daytime Protocol are
expected to adopt and implement this standard.
A useful debugging and measurement tool is a daytime service. A daytime
service simply sends a the current date and time as a character string
without regard to the input.
TCP Based Daytime Service
One daytime service is defined as a connection based application on
TCP. A server listens for TCP connections on TCP port 13. Once a
connection is established the current date and time is sent out the
connection as a ascii character string (and any data received is
thrown away). The service closes the connection after sending the
quote.
UDP Based Daytime Service
Another daytime service service is defined as a datagram based
application on UDP. A server listens for UDP datagrams on UDP port
13. When a datagram is received, an answering datagram is sent
containing the current date and time as a ASCII character string (the
data in the received datagram is ignored).
Daytime Syntax
There is no specific syntax for the daytime. It is recommended that
it be limited to the ASCII printing characters, space, carriage
return, and line feed. The daytime should be just one line.
One popular syntax is:
Weekday, Month Day, Year Time-Zone
Example:
Tuesday, February 22, 1982 17:37:43-PST
Daytime Protocol
Another popular syntax is that used in SMTP:
dd mmm yy hh:mm:ss zzz
Example:
02 FEB 82 07:59:01 PST
NOTE: For machine useful time use the Time Protocol (RFC-868).
ISO Plain Language
On this page
§1A Readable Date and Time
The Daytime service sends the current date and time as a character string without regard to the input. The RFC describes it as a useful debugging and measurement tool for hosts that choose to implement it.
The service tells a client the current date and time in text. It does not interpret the data sent to it.
§2TCP and UDP Services
For TCP, a server listens on TCP port 13. After the connection is established, it sends the current date and time as an ASCII string, ignores received data, and closes the connection.
For UDP, the server listens on UDP port 13. Each incoming datagram receives an answering datagram with the current date and time as an ASCII string.
Over TCP, the server sends the time and then closes the connection. Over UDP, each request gets one datagram containing the time.
§3Writing the Time
The RFC defines no specific format for the date and time. It recommends ASCII printing characters, spaces, carriage return, and line feed, and recommends that the response fit on one line.
The memo gives two popular text formats and says to use the Time Protocol, RFC 868, when a machine-usable time value is needed.
The response is meant for people to read, and the RFC does not require one exact date format. For time that a program can use directly, the memo points to the Time Protocol.