It is beyond the scope of this article to explain how specific VPN systems are installed and set up. In my experience these activities are very well covered in the documentation of the providers. What is less well covered is the identification, diagnosis and resolution of problems which prevent the VPN user achieving the results expected. What I will cover from this point onwards is the practical use of VPN.

There are three main scenarios which we come across when using VPN:

1.   A connection between a remote PC and a home PC

This type of scenario will occur when someone is travelling with a laptop computer and has a need to gain access to a desktop PC at home (for example, to pick up some files) as shown in the figure, below.

2.   A connection between a remote PC and a Network

This time our traveller needs to gain access to more than one PC at home or wants to connect to the network at the office, as shown in the figure below.

3.   A connection between two remote Networks

The final scenario is the requirement to connect together two networks which are geographically remote from one another, such as a branch office with a main office.