Set up NAT loopback

README.org

@@ -12,5 +12,6 @@
  - Web services and reverse proxy: webstack.nix
  - Development tools: devops.nix
  - Smartd: monitoring.nix
+ - Systemd services and timers: periodic.nix
 
  All the modules are imported in *configuration.nix*

configuration.nix

@@ -107,6 +107,7 @@
     ./modules/webstack.nix
     ./modules/devops.nix
     ./modules/monitoring.nix
+    ./modules/periodic.nix
   ];
 
 }

modules/networking.nix

@@ -33,11 +33,13 @@ in {
     allowedTCPPorts = [
       631 # Cups
       6566 # SANE
-      80
+      80 # HTTP
-      443
+      443 # HTTPS
+      53 # DNS
     ];
     allowedUDPPorts = [
       1194 # Wireguard
+      53 # DNS
     ];
     autoLoadConntrackHelpers = true;
     connectionTrackingModules = [ "sane" ];
@@ -77,5 +79,26 @@ in {
     };
   };
 
+  # DNS server with ad-block
+  services.dnsmasq = {
+    enable = true;
+    servers = [ "176.9.37.132" "116.203.147.31" ];
+    extraConfig = ''
+      domain-needed
+      bogus-priv
+      no-resolv
+
+      listen-address=127.0.0.1,192.168.1.2,10.8.0.1
+      bind-interfaces
+
+      cache-size=10000
+      local-ttl=300
+
+      conf-file=/var/lib/dnsmasq/dnsmasq.blacklist.txt
+
+      address=/coolneng.duckdns.org/192.168.1.2
+    '';
+  };
+
 }
 

modules/periodic.nix

@@ -0,0 +1,30 @@
+{ config, lib, pkgs, ... }:
+
+let
+  stateDir = "/var/lib/dnsmasq";
+  blocklist = "${stateDir}/dnsmasq.blacklist.txt";
+
+in {
+  # Fetch hosts-blocklists daily
+  systemd.services.download-dns-blocklist = {
+    description = "Download hosts-blocklists";
+    wantedBy = [ "default.target" ];
+    path = with pkgs; [ curl ];
+    script =
+      "curl -L https://github.com/notracking/hosts-blocklists/raw/master/dnsmasq/dnsmasq.blacklist.txt -o ${blocklist}";
+    serviceConfig = { Type = "oneshot"; };
+    postStop = ''
+      chown -R dnsmasq ${stateDir}
+      systemctl restart dnsmasq
+    '';
+  };
+
+  systemd.timers.download-dns-blocklist = {
+    description = "Daily download of hosts-blocklists";
+    wantedBy = [ "default.target" ];
+    timerConfig = {
+      OnCalendar = "02:00:00";
+      Unit = "download-dns-blocklist.service";
+    };
+  };
+}