feat(firewall): public zone + askari's public services in the catalog

Adds a public (0.0.0.0/0) zone and askari's Caddy (80/443) + NetBird STUN
(3478/udp) ingress so the base nftables default-deny does not drop the live
public services when applied to askari. Molecule + filter unit test cover the
public-zone rendering. Mesh-hardening 1/3 (ADR-020/024/016).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

inventories/production/group_vars/all/firewall.yml

@@ -2,14 +2,27 @@
 # Shared firewall topology — single source of truth for the host nftables layer
 # (base role) and OPNsense (future). See docs/decisions/020-firewall.md.
 
-# Zone → subnet (from ADR-007).
+# Zone → subnet (from ADR-007). `public` = the WAN (anywhere) for deliberately public
+# off-site services (askari); home/cluster services use the internal zones only.
 firewall_zones:
   mgmt: 10.10.0.0/24
   srv: 10.20.0.0/24
   lan: 10.30.0.0/24
   iot: 10.40.0.0/24
   guest: 10.50.0.0/24
+  public: 0.0.0.0/0
 
 # Service catalog: <name> → placement (host | group | hosts) + ingress[].
-# Empty until services are built; hosts still get default-deny + the management plane.
-firewall_catalog: {}
+# askari's public surface (ADR-024 Caddy + ADR-016 NetBird STUN). NOTE: the host
+# nftables template renders IPv4 source rules only; askari is reached via its A record
+# (no AAAA), so IPv4-only public rules are sufficient (see the spec's IPv6 note).
+firewall_catalog:
+  reverse_proxy:
+    host: askari
+    ingress:
+      - { from: public, port: 80, proto: tcp }
+      - { from: public, port: 443, proto: tcp }
+  netbird_stun:
+    host: askari
+    ingress:
+      - { from: public, port: 3478, proto: udp }

roles/base/molecule/default/converge.yml

@@ -17,6 +17,7 @@
       lan: 10.30.0.0/24
       srv: 10.20.0.0/24
       mgmt: 10.10.0.0/24
+      public: 0.0.0.0/0
     firewall_catalog:
       reverse_proxy:
         host: instance
@@ -26,5 +27,9 @@
         host: instance
         ingress:
           - { from: srv, port: 2342, proto: tcp }
+      netbird_stun:
+        host: instance
+        ingress:
+          - { from: public, port: 3478, proto: udp }
   roles:
     - role: base

roles/base/molecule/default/verify.yml

@@ -38,6 +38,13 @@
           - "'tcp dport 2342 accept' in nft"
         fail_msg: "missing srv->2342 rule for photoprism"
 
+    - name: Assert the public->stun:3478/udp ingress rule (0.0.0.0/0 source)
+      ansible.builtin.assert:
+        that:
+          - "'0.0.0.0/0' in nft"
+          - "'udp dport 3478 accept' in nft"
+        fail_msg: "missing public->3478/udp rule for netbird_stun"
+
     - name: Assert the docker_host extension hook is present
       ansible.builtin.assert:
         that:

tests/test_firewall_rules.py

@@ -97,3 +97,12 @@ def test_ingress_missing_port_raises():
     cat = {"svc": {"host": "docker01", "ingress": [{"from": "lan"}]}}
     with pytest.raises(ValueError):
         fr.resolve_firewall_rules(cat, ZONES, "docker01", HOSTVARS, GROUPS)
+
+
+def test_public_zone_resolves_to_anywhere():
+    catalog = {"web": {"host": "askari",
+                       "ingress": [{"from": "public", "port": 443, "proto": "tcp"}]}}
+    zones = {"public": "0.0.0.0/0"}
+    rules = fr.resolve_firewall_rules(catalog, zones, "askari",
+                                      {"askari": {"ansible_host": "100.99.226.39"}}, {})
+    assert rules == [{"proto": "tcp", "port": 443, "sources": ["0.0.0.0/0"]}]