Chapter 5: Firewall
If you got this far, congratulations! We'll explore one of the main features of OPNsense – the firewall! In this chapter, we will learn which packet filter system OPNsense uses for firewalling, what type is it, how it works, what aliases or Packet Filter (pf) tables are, create our first rule, and explore diagnostics and troubleshooting. Through this chapter, you'll learn the firewalling basics that will be required to move on in this book, so pay attention reading it, practice the suggested exercises, and if you are unsure about some of the concepts presented here, please try to read it twice – it will be very important for you in the next chapters.
There will also be practical elements, so start your OPNsense virtual machine to follow all the topics explored here:
- Understanding firewalling concepts
- Firewall aliases
- Firewall rules
- Firewall settings
- Diagnostics and troubleshooting
