Since one of our compatriots already shared Lesson 1 of my Computer Security 101 series I thought I would officially add the lessons to the Tutorials forum here on AO. However, due to copyright and legal restrictions I can't simply cut and paste the whole thing. I am going to post a big chunk of each lesson and then link back to the original article on for those who wish to read the entire lesson.

In Computer Security 101 – Part 1 we discussed Hosts, DNS, ISP’s and Backbone. This is the second in a series designed to provide you with a basic understanding of the technology and terminology used on the Internet. Knowing why things work the way they do and what they are called will help you to secure your computer or network against new threats. In this lesson we will cover protocols, TCP/IP, DHCP and NAT.

Communications on the Internet and between computers is governed by protocols. The Merriam-Webster Dictionary defines a protocol as “a set of conventions governing the treatment and especially the formatting of data in an electronic communications system.” I’m not sure that makes things much clearer to a lay-person.

Put simply, if you called an orange an apple and I called it a plum we would never be able to communicate. At some point we have to come to some agreement as to what to call it. For computers and the Internet there were many organizations coming up with their own proprietary way of formatting and transmitting data. In order to ensure that all computers would be able to talk to each other and not just to their “own kind” protocols were created and agreed to.

TCP/IP, which stands for Transmission Control Protocol Internet Protocol is not a single protocol. It is a set of communication standards. TCP and IP are the two main protocols of the bunch. TCP/IP has been accepted as the standard for Internet communications and comes packaged by default with all major operating systems.

In order to communicate using TCP/IP each Host must have a unique IP address. As we discussed in Lesson 1, your IP address is similar to your street address. It identifies your Host on the Internet network so that communications intended for you reach their destination.

Originally, IP addresses were manually coded to each computer. As the Internet exploded and millions of Hosts were added it became an overwhelming task to track which IP addresses were already in use or which ones were freed up when a computer was removed from the network.

Computer Security 101: Lesson 2