- SEE ALSO
- DIFFERENCES FROM OTHER MODULES
- DIFFERENCES BETWEEN NTP AND SNTP
- LICENSE AND COPYRIGHT
- CHANGE LOG $Log: Client.pm,v $ Revision 23.0 2019/31/10 7:01:21 pm Thanos
Net::SNTP::Client - Perl module to calculate the roundtrip delay d and system clock offset t from NTP or SNTP Server.
The Net::SNTP::Client - Perl module retrieves the time from an NTP or SNTP server and uses the local time to calculate the roundtrip delay d and system clock offset t based on RFC4330. The module is calculating with higher accuracy in comparison to other modules.
use Net::SNTP::Client qw ( getSNTPTime ); my ( $error , $hashRefOutput ) = getSNTPTime( %hashInput ); ...
The module sends a UDP packet formated according to RFC4330 to a defined NTP or SNTP server set by the user. The received packet, gets decoded to a human readable form and also calculated the roundtrip delay d and system clock offset t, based on the decoded data.
This module exports a single method (getSNTPTime) and returns an associative hash of hashes upon RFC4330 and a string in case of an error occurs. The response from the NTP or SNTP server is beeen decoded to a human readable format. The obtained information recieved from the server can be can be used into further processing or manipulation according to the user needs. Maximum accuracy down to nano seconds can only be achieved on LinuxOS.
-hostname: The mandatory key inorder the method to produce an output is only the hostname, the rest of the keys are optional.
-port: By default the the port is set to 123 (NTP default port). The user has the option to overwite the port based on the expected NTP port on the server side (e.g. -port => 123456).
-timeOut: By default the time out is set to 10 seconds. The user has the option to overwite the time out input option based on the expected connection time (e.g. timeOut => 15).
-RFC4330: This is an optional way to produce an easy visual output based on RFC4330 documentation. Expected input is a string, integer or boolean in the form (0 or 1).
-clearScreen: This is an optional choice based on user preference if he/she desires to clear the "terminal screen" before printing the captured data. Expected input is a string, integer or boolean in the form (0 or 1).
my ( $error , $hashRefOutput ) = getSNTPTime( %hashInput );
my %hashInput = ( -hostname => $hostname, # hostnmae or IP -port => $port, # default NTP port 123 -timeOut => $timeOut, # default 10 -RFC4330 => $RFC4330, # default 0 -clearScreen => $clearScreen, # default 0 ); my ( $error , $hashRefOutput ) = getSNTPTime( %hashInput );
This module exports a single method - getSNTPTime and an error string in case of an error or a faulty operation. It expects a hash as an input. The input can have four different hash keys (-hostname, port, RFC4330 and -clearScreen).
This example gets the time from a remote NTP server from the pool.ntp.org: public ntp time server for everyone and calculates the roundtrip delay d and local clock offset t as defined on RFC4330.
We use the Data::Dumper module to print the output.
#!/usr/bin/perl use strict; use warnings; use Data::Dumper; use Net::SNTP::Client; my %hashInput = ( -hostname => "0.pool.ntp.org", -port => 123, -timeOut => 10, -RFC4330 => 1, -clearScreen => 1, ); my ( $error , $hashRefOutput ) = getSNTPTime( %hashInput ); print Dumper $hashRefOutput; print "Error: $error\n" if ($error);
The module is implemented using IO::Socket::INET and Time::HiRes and requires both these modules to be installed.
<garyfalos at cpan.org>
Please report any bugs or feature requests to
bug-net-sntp-client at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Net-SNTP-Client. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
You can find documentation for this module with the perldoc command.
You can also look for information at:
RT: CPAN's request tracker (report bugs here)
AnnoCPAN: Annotated CPAN documentation
perl, IO::Socket, Net::NTP, Net::SNTP::Server, RFC4330
Net::NTP has a similar focus as this module. In my opinion it is less accurate when it comes to the precission bellow second(s).
Based on the current known modules Net::SNTP::Client is only similar to Net::NTP module. The two modules do not have in common the encoding and decoding process of fractions of seconds.
Be aware that on different OS different precision can be achieved.
SNTP (Simple Network Time Protocol) and NTP (Network Time Protocol) are describing exactly the same network package format, the differences can be found in the way how a system deals with the content of these packages in order to synchronize its time.
The original concept for this module was based on NTP.pm written by James G. Willmore <email@example.com>.
Copyright 2004 by James G. Willmore
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
Copyright 2015 Athanasios Garyfalos.
This program is free software; you can redistribute it and/or modify it under the terms of the the Artistic License (2.0). You may obtain a copy of the full license at:
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