Summary

In this chapter, we learned about the OPNsense packet filtering system (the pf). We also learned what a stateful firewall is and how to check states on OPNsense, how to manage aliases and rules, how they are processed in OPNsense, creating rules' schedules, changing firewall settings, and explored firewall diagnostics and troubleshooting. Now you understand how OPNsense's firewalling works, how to create aliases and rules, how to adjust firewall settings, and how to troubleshoot firewall issues. Understanding firewalling is important in preparation for moving on to the next chapters.

In the next chapter, we'll continue the firewalling saga by exploring NAT rules!