View source for Time Protocol

{{Short description|A service in the Internet Protocol Suite}}
{{Internet protocol suite|application=[[Time Protocol]]}}
The '''Time Protocol''' is a network protocol in the [[Internet Protocol Suite]].{{Ref RFC|868}} Its purpose is to provide a site-independent, machine readable date and time.

The Time Protocol may be implemented over the [[Transmission Control Protocol]] (TCP) or the [[User Datagram Protocol]] (UDP).  A host connects to a server that supports the Time Protocol on port 37. The server then sends the time as a 32-bit unsigned integer in binary format and in [[network byte order]], representing the number of seconds since 00:00 (midnight) 1 January, 1900 GMT, and closes the connection. Operation over UDP requires the sending of any datagram to the server port, as there is no connection setup for UDP.

The fixed 32-bit data format means that the timestamp rolls over approximately every 136 years, with the first such occurrence on {{Date|7 February 2036}}. Programs that use the Time Protocol must be carefully designed to use context-dependent information to distinguish these dates from those in 1900.

Many [[Unix-like]] operating systems used the Time Protocol to monitor or synchronize their clocks using the [[rdate]] utility, but this function was superseded by the [[Network Time Protocol]] (NTP) and the corresponding [[ntpdate]] utility.  NTP is more sophisticated in various ways, among them that its resolution is finer than one second.

==Inetd implementation==
On most UNIX-like operating systems a Time Protocol server is built into the [[inetd]] (or [[xinetd]]) [[daemon (computer software)|daemon]]. The service is usually not enabled by default. It may be enabled by adding the following lines to the file {{mono|/etc/inetd.conf}} and reloading the configuration.
 time   stream  tcp     nowait  root    internal
 time   dgram   udp     wait    root    internal

==See also==
* [[Echo Protocol]]
* [[Discard Protocol]]
* [[Daytime Protocol]]
* [[Character Generator Protocol]]
* [[rdate]], a tool for querying the current time from a network server

==External links==
* [http://www.vervest.org/htp/ vervest.org - HTTP Time Protocol] 
* [http://freestone-group.com/fg-time-sync.htm freestone-group.com - FG Time Sync]

==References==
{{Reflist}}

[[Category:Network time-related software]]
[[Category:Application layer protocols]]