modules: services: add fail2ban

modules/services/default.nix

@@ -7,6 +7,7 @@
     ./blog
     ./calibre-web
     ./drone
+    ./fail2ban
     ./flood
     ./gitea
     ./grocy

modules/services/fail2ban/default.nix

@@ -0,0 +1,37 @@
+# A minimalist, opinionated feed reader
+{ config, lib, ... }:
+let
+  cfg = config.my.services.fail2ban;
+  wgNetCfg = config.my.services.wireguard.net;
+in
+{
+  options.my.services.fail2ban = with lib; {
+    enable = mkEnableOption "fail2ban daemon";
+  };
+
+  config = lib.mkIf cfg.enable {
+    services.fail2ban = {
+      enable = true;
+
+      ignoreIP = [
+        # Wireguard IPs
+        "${wgNetCfg.v4.subnet}.0/${toString wgNetCfg.v4.mask}"
+        "${wgNetCfg.v6.subnet}::/${toString wgNetCfg.v6.mask}"
+        # Loopback addresses
+        "127.0.0.0/8"
+      ];
+
+      maxretry = 5;
+
+      bantime-increment = {
+        enable = true;
+        rndtime = "5m"; # Use 5 minute jitter to avoid unban evasion
+      };
+
+      jails.DEFAULT = '';
+        findtime = 4h
+        bantime = 10m
+      '';
+    };
+  };
+}