NTP Service Installation & Configuration Exercise
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1. Intro:

The packages to be installed are:

* ntp
* ntpdate

Debian provides 2 ways of installing third party software: 

	i. Binary Packages
	These are pre-built package that contains the executables, config files, man/info pages, etc for the 
        Debian system and have a distinguished file extension ".deb"
	
	ii. Source packages
	They contain the original unmodified source files in gzipped-compressed tar format.
 

For this class, we will install ntp and ntpdate using packages.

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2. Installation of ntp and ntpdate using packages:

2.1 Install ntp & ntpdate

	$ sudo apt-get install ntp ntpdate
	
	
2.2.  Once installed, the ntp startup script is placed at /etc/init.d/ . To add ntp to the System Startup

	$ sudo update-rc.d ntp enable

2.3. To start ntp run

	$ sudo /etc/init.d/ntp start

	OR:

	$ sudo service nap start

Check if the ntp service you have just installed works by issuing the following command
 
	$ sudo ntpdq -pn


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In this section we will select four (4) machines to be our internal NTP servers and 
synchronize all the other machines off these four (4) machines. 

3. Select four (4) machines to be the internal NTP servers and ensure they are synchronized 
   off stratum 1 or 2 servers on the Internet.


4. All of the other servers should be configured to synchronize their clocks off
   the four (4) selected Internal NTP servers.


5. Configure the four (4) internal NTP servers to restrict access to only machines in 
   the SSE subnet i.e. 196.200.219.0/24

6. Configure the other ntp clients/servers to prevent them from answering ntp queries.