abrown38andClaude Opus 5.5
34292eeebb
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>
3.4 KiB
Connecting Housecarl to Jarl
Housecarl uses Jarl, the BIND manager, for its DNS records. In this version that means one thing: the DNS-01 challenge for the web UI's certificate (certificates.md). Naming hosts in rules by their DNS names may use the same connection later.
Housecarl talks to Jarl's REST API with an API token. Give it a user of its own, with only the permission it needs.
1. A user for Housecarl, in Jarl
On the Jarl server, make a user without a password. It can't log in to Jarl's web UI, only use its tokens. Grant it the challenge record of Housecarl's own name, and nothing else:
jarl user create housecarl --no-password --comment "Housecarl on fw01" \
--grant "records:write zones=adbraun.lol names=_acme-challenge.fw.adbraun.lol types=TXT"
Use your zone for adbraun.lol, and the name Housecarl's web UI is reached
by for fw.adbraun.lol (tls.acme.domain). The grant lets the token add
and remove TXT records at exactly _acme-challenge.fw.adbraun.lol:
- nothing else in the zone (
names=); - no other record type (
types=TXT); - no other zone (
zones=).
It can see that the zone exists, which it needs to find it, but it can't read the zone's other records.
Why not something wider:
- Jarl's
acmerole (records:write names=_acme-challenge.* types=TXT) would let the token publish challenges for any name in any zone, and so obtain certificates for all of them. Housecarl needs only its own name. - Your own account's token would carry all your permissions, and
Housecarl's certificate would stop renewing the day your account changes.
A user per program keeps the two apart, and the audit log shows
housecarl/...for what Housecarl did.
If the challenge name is a CNAME into a zone kept for challenges, such as
_acme-challenge.fw.adbraun.lol CNAME fw.acme.adbraun.lol., grant the
target instead: zones=acme.adbraun.lol names=fw.acme.adbraun.lol.
2. The token
Make the token, and copy it to the Housecarl server into a file only the
housecarl user can read:
jarl token create fw01 --user housecarl -q > housecarl.token # on the Jarl server, or with the jarl CLI anywhere
scp housecarl.token fw01:
ssh fw01 'sudo install -m 0600 -o housecarl -g housecarl housecarl.token /etc/housecarl/jarl.token && rm housecarl.token'
rm housecarl.token
A token file is better than putting the token in housecarl.yaml: the
configuration file is readable by the housecarl group, and gets copied
around more readily.
You can give the token an expiry (--expires 365d). Rotate it in Jarl with
jarl token rotate ID --grace 1d, then put the new secret in the file and
restart housecarld within the grace period. Since the certificate is renewed
every couple of months, nothing breaks while you do.
3. Housecarl's settings
In /etc/housecarl/housecarl.yaml:
jarl:
server: https://dns.adbraun.lol:8053
token_file: /etc/housecarl/jarl.token
# ca_cert: /etc/housecarl/jarl-ca.pem # if Jarl's certificate isn't from a public CA
Then restart housecarld (systemctl restart housecarl). Housecarl needs to
reach Jarl's API over the network: Jarl's listen must include an
address Housecarl can reach, ideally over HTTPS.
hc cert check (certificates.md) tests
the connection, the token's permission, and that the record reaches the
internet.