To follow along with the examples provided in this chapter, you will need two fully functional pfSense firewalls (with one or more nodes behind each firewall), either on real physical networks or in a lab/virtualization environment. Installation and configuration of the ShrewSoft VPN client, described in the section on IPsec, requires a system running Microsoft Windows (Windows 2000, XP, Vista, 7, 8, or 10 will do). The examples presented in this chapter should not be particularly resource-intensive; however, setting up an encrypted VPN tunnel does tax the CPU somewhat. Therefore, running pfSense on hardware that barely meets the minimum specifications for pfSense is not recommended.