#!perl  # it's run on windows that's why not a full path

# Code Snippet to show how to get the date of the last login time
# of an AD user on windows 2003 stored in the lastLogonTimestamp attribute.
#
# For more inforamtion about the value and windows use of Epoch, 
# basically put, the number of 100-nanosecond intervals that passed between January 1, 1601 and the time the user last logged on
#
# Reference to the maths: http://www.microsoft.com/technet/scriptcenter/topics/win2003/lastlogon.mspx
# The document also covers the issue replication of this attribute, be warned, the attribute 
# lastLogonTimestamp is replicated only once every 14 days.
#
# How to get the attribute out of AD is up to you.  I was using Net::LDAP at the time.
#
# Hopefully this will be found and help out anyone else stuck with this problem.
#

use strict;

# we need to handle the large int.  It's a 64bit int
use Math::BigInt;

# Use Date::Calc to work out the days and date since 1/1/1600
use Date::Calc qw/Add_Delta_Days/;

my $lastLoginTime = '127912653523035916';

my $loginTime = Math::BigInt->new( $lastLoginTime );

# Based on the document above and the words taken directly from:
# there are 1,000,000,000 nanoseconds in a second; 
# therefore, there are 10,000,000 100-nanosecond intervals in a single second (10,000,000 x 100 = 1,000,000,000).
$loginTime = $loginTime / (60 * 10000000  ); # 60 seconds in a minute!
# And because there are 1,440 minutes in every 24-hour day, this line of code tells us how many days have elapsed:
$loginTime = $loginTime / 1440;

# and now, to get the date of the last login:
my ($year,$month,$day) = Add_Delta_Days( 1601, 1, 1, $loginTime );
print "$year-$month-$day\n";

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