Bachelor's thesis: open-source firewalls for SMEs

Small and medium-sized businesses face more cyber threats, stricter security rules, and tight IT budgets. My thesis asks a practical question: can an open-source firewall be a technically equal and economically sensible alternative to commercial ones like Sophos?

I started with pfSense and OPNsense and scored both on five criteria weighted by what SMEs need: support, usability, hardware options, features and security, and update cycles. OPNsense won 8.35 to 7.35, so it went up against a Sophos XGS in a hands-on comparison: TLS inspection, IDS/IPS (checked with the EICAR test file), web filtering, VPN, dashboards, logging, and patch management.

OPNsense keeps up with Sophos on security features, but only with plugins like Zenarmor and Suricata and careful configuration. Over three years the total cost came out nearly identical: the lower licence fees are eaten up by roughly twice the admin effort. What decides it is licence cost against know-how and staff time. Open source pays off for teams with in-house expertise or those who want out of vendor lock-in; a micro-business with no IT support is still better served by Sophos.