This e-book was intended as a self study class on Cyber Security from England's Open University. It is aa n easily accessible overview of the topic, and also has an interesting unit on the relevant laws in the UK.
The content depth is not enough. It is really only the introduction of the cyber security. Moreover, I am not sure the book is too old or what. I did a quick scan once and found the book pointed out the VPN is a immature technology. I have doubt about it, as VPN has been here over 30 years.