It is recommended to have a PC with 8 GB RAM and a virtual system setup with Kali Linux installed on it. Kali Linux image file for VMware/VirtualBox/Hyper-V can be downloaded from  https://www.offensive-security.com/kali-linux-vm-vmware-virtualbox-image-download/

In order to follow the recipes, you will need to be running Windows or Kali Linux, and will require Metasploitable 2 by Rapid7 with the latest versions of Nmap and Nessus. For some of the recipes, such as those to do with configuration audits, you will need to have a Nessus professional license.