Archive for the 'Networking 101' Category

Introduction to ACLs (Access Control List)

Thursday, August 13th, 2009

Before looking into the configuration of ACL (Access Control Lists), it’s important to get some of the concepts and understanding of how they work and what they are used for. Firstly, most people believe that ACL’s are used purely for denying or allowing traffic, although this is certainly one of the functions of a ACL [...]

CIDR – Classless Inter Domain Routing

Monday, June 15th, 2009

CIDR was invented in 1990, and was the change that allowed routers to use classless addresses to route traffic instead of class-full addresses. This helped a huge amount as before its invention, routers could only route traffic based on full classes. If we look at Class A address for example, there are only 126 of [...]

Hashing, What is it and how does it work?

Friday, June 12th, 2009

Hashing is very different from encryption even though so many people believe it is an encryption protocol. Yes it does scramble the data, so from that aspect it is an encryption program, but the big difference between hashing and encryption, is that Hashing is mathematically impossible to reverse. Now I’m not the kind of person [...]

Ports and their use.

Thursday, June 11th, 2009

Ports are logical channels that devices use to identify a type of traffic. If you can imagine that you and I have a 10 meter cable, that has 10,000 wires running through it, and I take 2 of the wires and attach them into the ends of a battery, and you choose 2 wires on [...]

Useable IP addresses in private networks

Wednesday, June 10th, 2009

I’m sure you can imagine that trying to administer an IP address for every single person on the internet would be near impossible. Added to the fact that companies don’t want every computer in their network to be accessible on the internet for security reasons. The Internic and IANA (the two governing bodies for IP [...]

Class-full IP Addresses

Tuesday, June 9th, 2009

The way that IP addresses have been used and allocated over the years has changed somewhat, however the principles have not changed. In order to better manage IP addresses they were put into classes and each class followed certain rules. In this post we are going to focus on the Class-full address structures, and understand [...]

What is an IP address

Monday, June 8th, 2009

As the name indicates, and IP address is an address that computer equipment uses to be able to communicate with each other. It is made up of 4 octets (separated by a ‘.’), each of which is 8 bits in size (32 bits in total). If we look at our binary table for 8 bits, [...]

How to convert Hexadecimal into Decimal

Friday, June 5th, 2009

Hex or Hexadecimal, is a 16-base number system with values from 0-9 as well as ABCDEF where A=10, B=11, C=12, D=13, E=14, F=15. Hex is used in many things in IT, most commonly seen in Mac addresses (A unique identity number on every Network Card). It is also seen in certain features such as HSRP [...]

How encryption works

Thursday, June 4th, 2009

The concept of encryption can be quite daunting when you first look at it, however the basic concept of encryption is not that hard to understand   When I moved into my house, my bathroom door didn’t have a key. The previous owners of the house didn’t know what key was needed for that door [...]

How to count in Binary

Tuesday, June 2nd, 2009

The first and most important thing to understand when it comes to networking is binary. Without the fundamental understanding of binary and how it works, it would be very difficult to understand IP addresses, and without an understanding of IP addresses, it’s impossible to understand networking. So what is binary? Binary is a number system [...]