router.wireguard.<name> configures tunnels through networkd: road warrior
(listening, dual-stack), site-to-site (no transfer network) and provider
dial-out with masquerade. A tunnel has a zone like a LAN, so inter-zone rules
apply; management, DNS and internet are opt-in. Peers' allowedIPs become
routes (destination-based routing; default-route tunnels are rejected).
Tunnels have a kill switch (default on): forwarded packets for their
allowedIPs are dropped if they would leave via an uplink, before the
established-accept so flows that used the tunnel are cut too.
Private keys stay outside the Nix store and are passed to the unprivileged
systemd-networkd with LoadCredential, so key files can be root-only.
Assertions cover CIDR/key/endpoint formats, duplicate allowedIPs, overlaps
with LAN subnets, port and device clashes, and rule destinations inside
tunnel networks. A five-VM `wireguard` check covers road warrior, site-to-site,
the provider tunnel with an IPv6 transfer net, zone rules and the kill switch.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
nilsandClaude Sonnet 5.5
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