On Ubuntu 22 (systemd 249), systemd-resolved applies interface-scoped
routing to per-link DNS servers. Configuring `resolvectl dns fips0
127.0.0.1:5354` caused resolved to attempt reaching 127.0.0.1 through
fips0 (a TUN with only fd00::/8 routes), silently failing. The DNS
responder never received queries. Newer systemd versions (250+) have
explicit handling for loopback servers on non-loopback interfaces.
Changes:
- DNS responder default bind_addr changed from "127.0.0.1" to "::"
so it listens on all interfaces, including fips0. Bind logic in
lifecycle.rs now parses bind_addr as IpAddr and constructs a
SocketAddr, handling IPv6 literal formatting. Factored into
Node::bind_dns_socket with explicit IPV6_V6ONLY=0 via socket2, so
IPv4 clients on 127.0.0.1:5354 still reach the responder
regardless of the kernel's net.ipv6.bindv6only sysctl.
- fips-dns-setup resolvectl backend now waits for fips0 to have a
global IPv6 address, then configures resolved with
[<fips0-addr>]:5354. That address is locally delivered by the
kernel regardless of which interface resolved tries to route
through. The dnsmasq and NetworkManager backends still use
127.0.0.1 (they don't have the interface-scoping issue).
- Dropped hardcoded `bind_addr: "127.0.0.1"` from the packaged
fips.yaml (Debian + OpenWrt). The shipped config was overriding
the new default.
- DNS queries are only accepted from the localhost.
Verified end-to-end in a privileged Ubuntu 22.04 systemd container:
dig @127.0.0.53 AAAA <npub>.fips resolves cleanly through
systemd-resolved.
The dns-delegate backend (systemd 258+) still uses 127.0.0.1; it
has not been verified whether that backend has the same routing
issue.
The DNS responder returned NXDOMAIN for non-AAAA queries (e.g. A record)
on valid .fips names. This caused resolvers like nslookup and tinyproxy
to give up without attempting AAAA, since NXDOMAIN means "name does not
exist." Return NOERROR with an empty answer section instead, which tells
the client the name exists but has no records of that type.
Fixesjmcorgan/fips#9.
Add a HostMap that resolves human-readable hostnames to npubs,
enabling `gateway.fips` instead of the full `npub1...xyz.fips`.
Two sources populate the map: peer `alias` fields from the YAML
config and an operator-maintained hosts file at /etc/fips/hosts.
The DNS responder auto-reloads the hosts file on each request by
checking the file modification time, so operators can update
mappings without restarting the daemon.
- New src/upper/hosts.rs: HostMap, HostMapReloader, hostname
validation, hosts file parser with auto-reload on mtime change
- DNS resolver checks host map before falling back to direct npub
- Node uses host map for peer display names
- Default hosts file added to both .deb and tarball packaging
- 26 new tests (789 total)
Johnathan CorganandGitHub