OPNsense Firewall – My first network guardian

I didn't just want to understand how firewalls work in theory – I wanted to configure one myself.

So I installed OPNsense on my Raspberry Pi and set it up as my own firewall solution.

At first it was unfamiliar. Assigning interfaces. Configuring WAN and LAN correctly. Defining rules – and suddenly nothing works anymore because a rule is set incorrectly.

Working with firewall rules in particular has shown me how sensitive networks are.

One wrong rule – and all traffic is blocked.

Over time I have learned:

• selectively allowing traffic instead of "allowing everything"

• deliberately opening ports

• Analyzing logs

• To truly understand data traffic

For the first time, I not only had "Internet", but control over my network.

This project has greatly deepened my understanding of network security – especially with regard to my final apprenticeship exam.