Build Housecarl 0.1.0: the nftables firewall manager

Zones, address sets (IPv4 and IPv6 mixed, dynamic sets with timeouts) and
services, ordered rules in the early, input, forward and output chains,
port forwards with hairpin NAT and IPv6 pinholes, source NAT, redirects,
and switchable built-ins (loopback, conntrack, ICMPv6, antispoofing, MSS
clamping, DHCPv6 client, flowtable). Every change is validated, checked
with nft -c and applied in one transaction to Housecarl's own table,
inet housecarl; changes made over the network roll back unless
confirmed, and the confirmed ruleset is loaded at boot by
housecarl-ruleset.service. An empty configuration applies nothing.

Also: hit counters and the drop log (nflog), 'hc import' of an existing
nftables ruleset and 'hc takeover', the hc CLI, the REST API and the web
UI, users, scoped tokens (sets:write:NAME), the audit log, the web UI's
certificate through Jarl, Debian packages, docs, unit tests with real
nft 1.1.3, and an e2e test with real traffic (71 checks).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/importer/testdata/router.json

@@ -0,0 +1 @@
+{"nftables": [{"metainfo": {"version": "1.1.3", "release_name": "Commodore Bullmoose #4", "json_schema_version": 1}}, {"table": {"family": "inet", "name": "main", "handle": 1}}, {"chain": {"family": "inet", "table": "main", "name": "antispoof", "handle": 1, "type": "filter", "hook": "prerouting", "prio": -300, "policy": "accept"}}, {"chain": {"family": "inet", "table": "main", "name": "input", "handle": 2, "type": "filter", "hook": "input", "prio": 0, "policy": "drop"}}, {"chain": {"family": "inet", "table": "main", "name": "wg0_input", "handle": 3}}, {"chain": {"family": "inet", "table": "main", "name": "prerouting", "handle": 4, "type": "nat", "hook": "prerouting", "prio": -100, "policy": "accept"}}, {"chain": {"family": "inet", "table": "main", "name": "postrouting", "handle": 5, "type": "nat", "hook": "postrouting", "prio": 100, "policy": "accept"}}, {"chain": {"family": "inet", "table": "main", "name": "forward", "handle": 6, "type": "filter", "hook": "forward", "prio": 0, "policy": "drop"}}, {"chain": {"family": "inet", "table": "main", "name": "output", "handle": 7, "type": "filter", "hook": "output", "prio": 0, "policy": "accept"}}, {"rule": {"family": "inet", "table": "main", "chain": "antispoof", "handle": 9, "comment": "Private/bogus source addresses can't legitimately arrive from the internet", "expr": [{"match": {"op": "==", "left": {"meta": {"key": "iifname"}}, "right": "wan"}}, {"match": {"op": "==", "left": {"payload": {"protocol": "ip", "field": "saddr"}}, "right": {"set": [{"prefix": {"addr": "0.0.0.0", "len": 8}}, {"prefix": {"addr": "10.0.0.0", "len": 8}}, {"prefix": {"addr": "127.0.0.0", "len": 8}}, {"prefix": {"addr": "169.254.0.0", "len": 16}}, {"prefix": {"addr": "172.16.0.0", "len": 12}}, {"prefix": {"addr": "192.168.0.0", "len": 16}}]}}}, {"counter": {"packets": 0, "bytes": 0}}, {"drop": null}]}}, {"rule": {"family": "inet", "table": "main", "chain": "antispoof", "handle": 10, "comment": "Our own delegated prefix can't legitimately arrive from the internet", "expr": [{"match": {"op": "==", "left": {"meta": {"key": "iifname"}}, "right": "wan"}}, {"match": {"op": "==", "left": {"payload": {"protocol": "ip6", "field": "saddr"}}, "right": {"prefix": {"addr": "2a02:8013:7f3d::", "len": 48}}}}, {"counter": {"packets": 0, "bytes": 0}}, {"drop": null}]}}, {"rule": {"family": "inet", "table": "main", "chain": "input", "handle": 11, "expr": [{"match": {"op": "==", "left": {"meta": {"key": "iifname"}}, "right": "lo"}}, {"accept": null}]}}, {"rule": {"family": "inet", "table": "main", "chain": "input", "handle": 12, "expr": [{"match": {"op": "in", "left": {"ct": {"key": "state"}}, "right": ["established", "related"]}}, {"accept": null}]}}, {"rule": {"family": "inet", "table": "main", "chain": "input", "handle": 13, "expr": [{"match": {"op": "in", "left": {"ct": {"key": "state"}}, "right": "invalid"}}, {"drop": null}]}}, {"rule": {"family": "inet", "table": "main", "chain": "input", "handle": 15, "expr": [{"match": {"op": "!=", "left": {"meta": {"key": "iifname"}}, "right": "wan"}}, {"match": {"op": "==", "left": {"payload": {"protocol": "icmp", "field": "type"}}, "right": {"set": ["echo-reply", "echo-request"]}}}, {"counter": {"packets": 0, "bytes": 0}}, {"accept": null}]}}, {"rule": {"family": "inet", "table": "main", "chain": "input", "handle": 17, "expr": [{"match": {"op": "==", "left": {"payload": {"protocol": "icmpv6", "field": "type"}}, "right": {"set": ["destination-unreachable", "packet-too-big", "time-exceeded", "parameter-problem", "echo-request", "echo-reply"]}}}, {"counter": {"packets": 0, "bytes": 0}}, {"accept": null}]}}, {"rule": {"family": "inet", "table": "main", "chain": "input", "handle": 19, "comment": "IPv6 neighbour discovery", "expr": [{"match": {"op": "==", "left": {"payload": {"protocol": "icmpv6", "field": "type"}}, "right": {"set": ["nd-router-solicit", "nd-router-advert", "nd-neighbor-solicit", "nd-neighbor-advert"]}}}, {"match": {"op": "==", "left": {"payload": {"protocol": "ip6", "field": "hoplimit"}}, "right": 255}}, {"accept": null}]}}, {"rule": {"family": "inet", "table": "main", "chain": "input", "handle": 20, "comment": "DHCPv6 replies from Zen", "expr": [{"match": {"op": "==", "left": {"meta": {"key": "iifname"}}, "right": "wan"}}, {"match": {"op": "==", "left": {"payload": {"protocol": "udp", "field": "dport"}}, "right": 546}}, {"match": {"op": "==", "left": {"payload": {"protocol": "ip6", "field": "saddr"}}, "right": {"prefix": {"addr": "fe80::", "len": 10}}}}, {"accept": null}]}}, {"rule": {"family": "inet", "table": "main", "chain": "input", "handle": 21, "comment": "Accept new incoming wireguard connections", "expr": [{"match": {"op": "==", "left": {"payload": {"protocol": "udp", "field": "dport"}}, "right": 51820}}, {"match": {"op": "in", "left": {"ct": {"key": "state"}}, "right": "new"}}, {"accept": null}]}}, {"rule": {"family": "inet", "table": "main", "chain": "input", "handle": 22, "expr": [{"match": {"op": "==", "left": {"payload": {"protocol": "Line truncated