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Time Protocol (RFC0868)

IP.com Disclosure Number: IPCOM000003916D
Original Publication Date: 1983-May-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 2 page(s) / 3K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

J. Postel: AUTHOR [+2]

Abstract

This RFC specifies a standard 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.

This text was extracted from a ASCII document.
This is the abbreviated version, containing approximately 95% of the total text.

Network Working Group J. Postel - ISI

Request for Comments: 868 K. Harrenstien - SRI

May 1983

Time Protocol

This RFC specifies a standard 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.

This protocol provides a site-independent, machine readable date and

time. The Time service sends back to the originating source the time in

seconds since midnight on January first 1900.

One motivation arises from the fact that not all systems have a

date/time clock, and all are subject to occasional human or machine

error. The use of time-servers makes it possible to quickly confirm or

correct a system's idea of the time, by making a brief poll of several

independent sites on the network.

This protocol may be used either above the Transmission Control Protocol

(TCP) or above the User Datagram Protocol (UDP).

When used via TCP the time service works as follows:

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. When the connection

is established, the server returns a 32-bit time value and closes the

connection. If the server is unable to determine the time at its

site, it should either refuse the connection or close it without

sending anything.

RFC 868 May 1983

Time Protocol

When used via UDP the time service works as follows:

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 a datagram

arrives, the server returns a datagram containing the 32-bit time

value. If the server is unable to determine the time at its site, it

should discard the arriving datagram and make no reply.

The Time

The time is the number of seconds since 00:00 (midnight) 1 January 1900

GMT, such that the time 1 is 12:00:01 am on 1 January 1900 GMT; this

base will serve until the year 2036.

For example:

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...