NIST Keep Your System's Time Up To Date

Nist.pl is a tiny Perl script that I wrote back in 1998. This tiny Perl script simply connects to a machine which runs a timeserver (NTP) and adjusts your systems time accordingly.

Download:

• CPAN ftp://ftp.cpan.org/pub/CPAN/.../nist-2.1.12.tar.gz
• Freashmeat http://freshmeat.net/redir/nist/.../nist-2.1.12.tar.gz

List of Time Servers

Here is a list of few time servers that you can probably use. Please follow this link for the complete list of time servers: http://www.eecis.udel.edu/~mills/ntp/clock1a.html

 Location                                                    IP
 NIST Central Computer Facility, Gaithersburg, Maryland      129.6.15.29
 NASA Lewis Research Center, Cleveland, OH                   128.156.1.43
 Microsoft Corporation, Redmond, Washington                  131.107.1.10
 HP Western Research Laboratory, Palo Alto, CA               204.123.2.5
 Silicon Graphics Computer Systems, Inc., Mountain View, CA  192.48.153.74
 AOL Time Warner facility, Sunnyvale, California             207.200.81.113

Configuration

Just replace the following portion of the code according to your timezone.

 $timeserver = 'time-A.timefreq.bldrdoc.gov';        # time server
 $port = '13';                                       # time port (default:13)
 $timediff = '-06:00:00';                            # time differance
 $datepr = '/bin/date';                              # full path of date

Source code for nist.pl

#!/usr/bin/perl
#        $Id: nist.pl,v 1.2 2004/12/07 15:12:38 cinar Exp $
#
# Nist.pl to keep your system time up to date by using time servers.
# Copyright (C) 1998 - 2002 Ali Onur Cinar <cinar(a)zdo.com>
#
# Y2K fixes by Frank Denis aka Jedi/Sector One <j@4u.net>
# BSD-based OS detection added by Will (dirtymac) <dirtymac@datasync.com>
#
# Latest version can be downloaded from:
#
#   http://www.zdo.com
#   http://briefcase.yahoo.com/cinara  (Downloads folder)
#   http://www.cpan.org (Check for mirror sites)
#   ftp://mirror.hiwaay.net/CPAN/authors/id/A/AO/AOCINAR/nist*
#   ftp://sunsite.unc.edu/pub/Linux/system/admin/timei/nist*
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version. And also
# please DO NOT REMOVE my name, and give me a CREDIT when you use
# whole or a part of this program in an other program.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

use Socket qw(PF_INET SOCK_STREAM AF_INET);
use POSIX qw(mktime);

$timeserver = 'time-A.timefreq.bldrdoc.gov';    # time server
$port = '13';                                   # time port (default:13)
$timediff = '-06:00:00';                        # time differance
$datepr = '/bin/date';                          # full path of date


$timediff =~/(.)(..).(..).(..)/g;
$diff = (($2*3600)+($3*60)+$4);
$diff = "$1$diff";

if ($> ne 0)
{
   print STDERR 
    "This program should run as root user to be able to update sytem date.\n";
   exit;
}

if ($timeserver =~ /^(\d+)\.(\d+)\.(\d+)\.(\d+)$/)
{
   $timeserver_addr = pack('C4', $1, $2, $3, $4);
} else {
   $timeserver_addr = gethostbyname($timeserver);
}

print "Connecting to $timeserver on port $port...\n";

if (!socket(NIST, AF_INET, SOCK_STREAM, getprotobyname("tcp") || 6))
{
  print "socket failed ($!)\n"; exit;;
}

if (!connect(NIST, pack('Sna4x8', AF_INET, $port, $timeserver_addr)))
{
   print "connect to $timeserver failed ($!)\n"; exit;
}

while (<NIST>)
{
   $time_data_raw = $_;
   last if ( /NIST/);
}

close NIST;

$time_data_raw =~ /.{6}(..).(..).(..).(..).(..).(..)/g;
print "Current GMT is $1-$2-$3 $4-$5-$6\n";

&DateToSec($1,$2,$3,$4,$5,$6);
$datsec += $diff;
&SecToDate($datsec);

printf ("Local time is  %02d-%02d-%02d %02d-%02d-%02d\n", 
  $year, $month, $day, $hour, $min, $sec);
print "Updating the system time. ";

$os = `uname`;
if ($os =~ m/BSD/i) {
  $date_command = sprintf (
    "$datepr %04d%02d%02d%02d%02d.%02d",$year,
$month, $day, $hour, $min, $sec);
} else {
  $date_command = sprintf (
    "$datepr %02d%02d%02d%02d%04d.%02d",$month,
$day, $hour,$min, $year, $sec);
}

system ($date_command);
print "Done.\n";

sub DateToSec
{
   $year = @_[0];$month = @_[1];$day = @_[2];
   $hour = @_[3];$min = @_[4];$sec = @_[5];
   $datsec = POSIX::mktime($sec, $min, $hour, $day - 1,
     $month - 1, $year + 100);
}

sub SecToDate
{
   $datsec = @_[0];
   ($sec, $min, $hour, $day, $month, $year, $wday, $yday, $isdst) =
    localtime($datsec);
   $day++;
   $month++;
   $year += 1900;
}