Introduction

Today, the business world is highly connected: staff, contractors, suppliers, and customers can access information from almost any location, and through any platform or device including laptops, tablets, and smartphones, accessing networks using Wi-Fi, 3G, 4G or 5G.

The corporate infrastructure could be accessed through an extranet, and the organisation might have multiple sites – each with their own IT infrastructure. The sites could be connected using an internal Wide Area Network, with each one communicating independently with the internet.

As a result, an organisation might support many connections to the outside world, some of which are known, and some are unknown because they’ve been installed without appropriate authorisation. Clearly, this is a very risky situation so any order you can place on the existing and future connections can really help us reduce weaknesses. It can also help mitigate, or hopefully eliminate, many threats.

You will be looking at various defences in the following steps, but first let’s consider the main network 'building blocks'. These are the foundations of most networks, so you first need to look at them and understand them before moving on to seeing how you can secure them.