61 lines
2.4 KiB
TeX
61 lines
2.4 KiB
TeX
\chapter{Using Time and Daytime Protocol}\label{cha:ntp}
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%
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\begin{description}
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\item[Used files:] nettime.scm nettime-obsolete.scm
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\item[Name of the package:] nettime nettime-obsolete
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\end{description}
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%
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\subsection{Overview}
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Most Unix hosts provide a Daytime service which sends the current date
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and time as a human-readable character string. The daytime service is
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typically served on port 13 as both TCP and UDP.
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The Time protocol provides a site-independent, machine readable date
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and time. A ``time'' consists of the number of seconds since midnight on
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1st January 1900. The Time service is typically served on port 37 as
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TCP and UDP. The idea is that you can confirm your system's idea of
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the time by polling several independent sites on the network.
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\subsection{Procedures}
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\begin{defundesc}{net-time}{host tcp/udp}{integer}
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Asks \semvar{host} about the current time. \semvar{tcp/udp} is
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either \ex{socket\=type/\ob{}stream} or
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\ex{socket\=type/\ob{}datagram}, that indicate TCP or UDP
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connection, respectively (depends on the server).\FIXME{Is it
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correct, that the tcp/udp argument describes TCP or UDP use via
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socket-type/stream or socket-type/datagram, resp.?} The number of
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second since 1970 is returned, since the time protocol returns the
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number of seconds since 1900, whereas Unix time is since 1970. The
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difference between both answers is 2208988800.
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\end{defundesc}
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\begin{defundesc}{net-daytime}{host tcp/udp}{string}
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Asks \semvar{host} about the current daytime. \semvar{tcp/udp} is
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the same as in \ex{net:time}, indicating to use TCP or UDP. The
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host's answer is returned (e.g., ``Thursday, April 4, 2'').
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\end{defundesc}
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\subsubsection*{Obsolete procedures}
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Names in further versions of \ex{nettime} contained a colon (`\ex{:}')
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after the prefix `\ex{net-}'. This is now changed to a hyphen
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('\ex{-}'), accordingly to SUnet's philosophy. If you need the old
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names, use the \ex{nettime\=obsolete}-package that maps the old names
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to the new ones.
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\subsection{Related work}
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\begin{itemize}
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\item \ex{Time.pm} is a Perl module by Graham Barr
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\item RFC~868 describes the Time protocol
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\item RFC~867 describes the Daytime protocol in all its glory
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\item For a genuinely useful protocol look at the Network Time
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Protocol defined in RFC~1305, which allows for the synchronization
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of clocks on networked computers.
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\end{itemize}
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%%% Local Variables:
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%%% mode: latex
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%%% TeX-master: t
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%%% End:
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