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this list is not exhaustive, it shows only few modules but those are useful to setup a security layer for web servers
snort - Snort is an intrusion detection and prevention system. It can be configured to simply log detected network events to both log and block them
haproxy - HAProxy is a free, very fast and reliable solution offering high availability, load balancing, and proxying for TCP, HTTP and HTTPS-based applications, Ha proxy enable the administrator to perform SSL offloading and to configure the binding between subdomaine.domaine and IP pools
ACME - ACME let the administrator to create trusted SSL certificates via Let’s Encrypt API (green lock next to the URL) that can be used by all services running behind pfSense. Let’s Encrypt is an open, free, and completely automated Certificate Authority from the non-profit Internet Security Research Group (ISRG)
Pfblocker - Enable advanced blocked IP list or/and country block