Add site gateway role (modules/router) and gw-cnx-1

Reusable cnx.router.* module for the Topton 1U boxes replacing OPNsense: PPPoE WAN (optionally VLAN-tagged, AIS: 10, secret credentials incl. username), VLAN-filtering bridge, nftables NAT/firewall with MSS clamp, Kea DHCP with per-VLAN lease time, Blocky DNS, DHCPv6-PD, CrowdSec with the ZeroTier mesh whitelisted, optional Omada controller, ZFS disk. Fleet baseline rides along: admins sops group is now derived for every machine in clan.nix (secrets encrypt to it from the first vars generate) and time sync is chrony everywhere instead of systemd-timesyncd.
2026-07-28 17:06:07 +07:00
parent a87b579eb7
commit 158252323f
20 changed files with 857 additions and 31 deletions
@@ -0,0 +1,62 @@
+# Router firewall/NAT policy (nftables). Trust model:
+#   mgmt VLAN  -> trusted: router services, all VLANs, WAN
+#   other VLANs -> DNS/DHCP on the router + WAN (if allowWan); no inter-VLAN
+#   WAN (ppp0) -> nothing inbound beyond established/related
+#   mesh       -> admin SSH + metrics scrapes (same trust boundary as the fleet)
+{
+  config,
+  lib,
+  ...
+}:
+let
+  cfg = config.cnx.router;
+  mesh = import ../mesh-hosts.nix { inherit config lib; };
+
+  vlanIfs = lib.mapAttrsToList (name: _: "vlan-${name}") cfg.vlans;
+  wanVlanIfs = lib.mapAttrsToList (name: _: "vlan-${name}") (
+    lib.filterAttrs (_: vlan: vlan.allowWan) cfg.vlans
+  );
+  nonMgmtIfs = lib.filter (i: i != "vlan-mgmt") vlanIfs;
+  ifSet = ifs: "{ ${lib.concatStringsSep ", " (map (i: "\"${i}\"") ifs)} }";
+in
+{
+  config = lib.mkIf cfg.enable {
+    networking.nftables.enable = true;
+
+    # SSH reachable only from the mgmt VLAN (trusted) and the mesh — never
+    # from the WAN or the other VLANs.
+    services.openssh.openFirewall = false;
+
+    networking.firewall = {
+      enable = true;
+      filterForward = true;
+      trustedInterfaces = [ "vlan-mgmt" ];
+
+      # Non-mgmt VLANs may only talk to the router's DNS and DHCP.
+      interfaces = lib.genAttrs nonMgmtIfs (_: {
+        allowedTCPPorts = [ 53 ];
+        allowedUDPPorts = [
+          53
+          67
+        ];
+      });
+
+      extraInputRules = ''
+        ip6 saddr ${mesh.subnet} tcp dport 22 accept comment "admin ssh over the mesh"
+        ip6 saddr ${mesh.subnet} tcp dport 4000 accept comment "blocky metrics scrape from control"
+      '';
+
+      extraForwardRules = ''
+        tcp flags syn tcp option maxseg size set rt mtu comment "MSS clamp for PPPoE mtu 1492"
+        iifname "vlan-mgmt" accept comment "mgmt reaches all VLANs and the WAN"
+        iifname ${ifSet wanVlanIfs} oifname "ppp0" accept comment "LAN to internet"
+      '';
+    };
+
+    networking.nat = {
+      enable = true;
+      externalInterface = "ppp0";
+      internalInterfaces = vlanIfs;
+    };
+  };
+}