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API v1alpha1

routerd uses Kubernetes-like API shapes:

  • apiVersion
  • kind
  • metadata.name
  • spec
  • status where applicable

API Groups​

  • routerd.net/v1alpha1 for the top-level Router config
  • net.routerd.net/v1alpha1 for network resources
  • firewall.routerd.net/v1alpha1 for firewall resources
  • system.routerd.net/v1alpha1 for local system resources
  • plugin.routerd.net/v1alpha1 for plugin manifests

MVP Resources​

  • Interface
  • PPPoEInterface
  • IPv4StaticAddress
  • IPv4DHCPAddress
  • IPv4DHCPServer
  • IPv4DHCPScope
  • HealthCheck
  • IPv4DefaultRoutePolicy
  • IPv4PolicyRoute
  • IPv4PolicyRouteSet
  • IPv4ReversePathFilter
  • PathMTUPolicy
  • Zone
  • FirewallPolicy
  • ExposeService
  • IPv4SourceNAT
  • IPv6DHCPAddress
  • IPv6PrefixDelegation
  • IPv6DelegatedAddress
  • IPv6DHCPServer
  • IPv6DHCPScope
  • SelfAddressPolicy
  • DNSConditionalForwarder
  • DSLiteTunnel
  • Hostname
  • LogSink
  • NTPClient
  • Sysctl

The schema is intentionally small and will be implemented incrementally.

Interface Ownership​

Interface resources support spec.managed.

  • managed: false means routerd observes the interface and resolves aliases, but does not change link or address state.
  • managed: true means routerd may manage the interface after existing OS networking ownership has been reviewed.

When cloud-init or netplan is detected, routerd planning reports RequiresAdoption instead of taking over automatically.

PPPoEInterface​

PPPoEInterface declares a PPPoE interface built on top of another Interface. On Linux routerd renders pppd/rp-pppoe peer configuration, CHAP/PAP secrets, and an optional systemd unit.

apiVersion: net.routerd.net/v1alpha1
kind: PPPoEInterface
metadata:
  name: wan-ppp
spec:
  interface: wan-ether
  ifname: ppp0
  username: user@example.jp
  passwordFile: /usr/local/etc/routerd/pppoe-password
  defaultRoute: true
  usePeerDNS: true
  managed: true
  mtu: 1492
  mru: 1492

interface references the lower Ethernet Interface. ifname defaults to ppp-<metadata.name> and must fit the Linux 15-character interface name limit. Exactly one of password or passwordFile is required. passwordFile is preferred so credentials do not have to live in the main YAML file.

When managed: true, routerd enables and starts routerd-pppoe-<name>.service. When managed: false, routerd still renders the local config files but does not start the systemd unit.

LogSink​

system.routerd.net/v1alpha1 LogSink declares where routerd sends internal operational events.

Local journald/syslog output:

apiVersion: system.routerd.net/v1alpha1
kind: LogSink
metadata:
  name: local-syslog
spec:
  type: syslog
  minLevel: info
  syslog:
    facility: local6
    tag: routerd

Trusted local log plugin output:

apiVersion: system.routerd.net/v1alpha1
kind: LogSink
metadata:
  name: external-log
spec:
  type: plugin
  minLevel: warning
  plugin:
    path: /usr/local/libexec/routerd/log-sinks/example
    timeout: 5s

enabled defaults to true. minLevel defaults to info. syslog.facility defaults to local6, and syslog.tag defaults to routerd. For remote syslog, set syslog.network and syslog.address, for example network: udp and address: syslog.example.net:514.

NTPClient​

system.routerd.net/v1alpha1 NTPClient declares the local NTP client. The initial implementation manages systemd-timesyncd with static servers.

apiVersion: system.routerd.net/v1alpha1
kind: NTPClient
metadata:
  name: system-time
spec:
  provider: systemd-timesyncd
  managed: true
  source: static
  interface: wan
  servers:
    - pool.ntp.org

When interface is set, routerd renders per-link NTP= through systemd-networkd for that interface. When omitted, routerd writes global systemd-timesyncd servers.

IPv4 Overlap Safety​

IPv4StaticAddress resources are checked against desired static addresses and observed IPv4 prefixes on other interfaces during planning.

Overlapping prefixes on different interfaces are blocked by default. Intentional overlap for NAT, HA, or lab cases must be explicit:

spec:
  interface: lan
  address: 192.168.160.3/24
  allowOverlap: true
  allowOverlapReason: overlapping customer network for NAT lab

Sysctl​

system.routerd.net/v1alpha1 Sysctl declares a kernel parameter.

apiVersion: system.routerd.net/v1alpha1
kind: Sysctl
metadata:
  name: ipv4-forwarding
spec:
  key: net.ipv4.ip_forward
  value: "1"
  runtime: true
  persistent: false

runtime: true means routerd should manage the running kernel value. persistent: true is reserved for OS-specific rendering such as sysctl.d or rc.conf and is not applied yet.

SelfAddressPolicy​

SelfAddressPolicy defines how dnsSource: self selects a local address. This keeps address selection explicit when an interface has multiple addresses, such as a delegated LAN address and extra DS-Lite source addresses.

apiVersion: net.routerd.net/v1alpha1
kind: SelfAddressPolicy
metadata:
  name: lan-ipv6-self
spec:
  addressFamily: ipv6
  candidates:
    - source: delegatedAddress
      delegatedAddress: lan-ipv6-pd-address
      addressSuffix: "::3"
    - source: interfaceAddress
      interface: lan
      matchSuffix: "::3"
    - source: interfaceAddress
      interface: lan
      ordinal: 1

IPv6DHCPScope can reference it:

spec:
  dnsSource: self
  selfAddressPolicy: lan-ipv6-self

Candidate order is significant. The first candidate that can be resolved wins. When omitted, IPv6 DHCP scopes use a default policy equivalent to delegated address plus the IPv6DelegatedAddress.addressSuffix, then an observed address matching that suffix, then the first observed global address.

HealthCheck And IPv4DefaultRoutePolicy​

HealthCheck declares a small reachability check. The default interval is 60s; shorter intervals are intentionally opt-in because route failover should not be overly sensitive by default.

apiVersion: net.routerd.net/v1alpha1
kind: HealthCheck
metadata:
  name: dslite-v4
spec:
  type: ping
  role: next-hop
  targetSource: dsliteRemote
  interface: transix-a

role describes what the check means operationally. It does not change the wire operation by itself; it makes route policy and status output easier to read. Supported roles are:

  • link: interface existence, carrier, or administrative link state.
  • next-hop: nearby forwarding dependency such as a gateway, AFTR, or tunnel endpoint.
  • internet: end-to-end public reachability, such as ping or TCP connect to a public target.
  • service: service-specific dependency such as DNS resolution, DHCP, AFTR FQDN resolution, or a PPPoE session.
  • policy: an aggregate answer to whether a route candidate may be selected.

The default role is next-hop, matching the current targetSource: auto behavior.

IPv4DefaultRoutePolicy selects the healthy candidate with the lowest priority. A candidate may be a direct interface route, or it may reference an IPv4PolicyRouteSet. Direct candidates use dedicated routing tables and firewall marks. New flows are marked for the active direct candidate. Existing flows keep their conntrack mark while that candidate remains healthy; if the old candidate becomes unhealthy, routerd's nftables policy rewrites that flow to the currently active candidate.

When the active candidate references routeSet, routerd leaves new flows unmarked so the referenced IPv4PolicyRouteSet can hash them across its targets. Existing conntrack marks for healthy route-set targets are preserved. If a stale mark belongs to a failed candidate, routerd clears it and lets the route set select a target again.

When target is omitted, targetSource: auto chooses a nearby check target: DS-Lite checks the AFTR IPv6 address, and ordinary/PPPoE interfaces check the IPv4 default gateway for that interface. This is a next-hop check by default. If you need end-to-end IPv4 Internet reachability, configure an explicit static IPv4 target as a separate role: internet health check. A future aggregate role: policy check can combine several lower-level checks into one answer for route candidate selection. A route candidate with no healthCheck is always treated as up.

apiVersion: net.routerd.net/v1alpha1
kind: IPv4DefaultRoutePolicy
metadata:
  name: default-v4
spec:
  mode: priority
  sourceCIDRs:
    - 192.168.160.0/24
  destinationCIDRs:
    - 0.0.0.0/0
  candidates:
    - name: dslite
      routeSet: lan-dslite-balance
      priority: 10
      healthCheck: dslite-v4
    - name: pppoe
      interface: wan-pppoe
      gatewaySource: none
      priority: 20
      table: 111
      mark: 273
      routeMetric: 60
      healthCheck: pppoe-v4
    - name: dhcp4
      interface: wan
      gatewaySource: dhcp4
      priority: 30
      table: 112
      mark: 274
      routeMetric: 100
      healthCheck: wan-dhcp4-v4

IPv6 default gateway behavior is intentionally left for a later design pass.

IPv6 Prefix Delegation​

IPv6PrefixDelegation requests a delegated prefix on an uplink interface. IPv6DelegatedAddress assigns an address on a downstream interface by combining one delegated subnet with a static interface identifier.

apiVersion: net.routerd.net/v1alpha1
kind: IPv6PrefixDelegation
metadata:
  name: wan-pd
spec:
  interface: wan
  client: networkd
  profile: ntt-hgw-lan-pd
apiVersion: net.routerd.net/v1alpha1
kind: IPv6DelegatedAddress
metadata:
  name: lan-ipv6-pd-address
spec:
  prefixDelegation: wan-pd
  interface: lan
  subnetID: "0"
  addressSuffix: "::3"
  sendRA: true
  announce: true

On Linux with systemd-networkd, routerd renders drop-ins under /etc/systemd/network/10-netplan-<ifname>.network.d/. The downstream addressSuffix maps to networkd Token=, so ::3 means the LAN interface receives the delegated prefix with host identifier ::3.

profile tunes DHCPv6-PD behavior for known upstream environments:

  • ntt-ngn-direct-hikari-denwa: the router is connected directly to the NTT NGN/ONU side on a Hikari Denwa contract.
  • ntt-hgw-lan-pd: the router is connected to the LAN side of an NTT home gateway that delegates /60 prefixes to downstream routers.

Both NTT PD profiles currently request IA_PD only, disable rapid commit, use a link-layer DUID, force DHCPv6 Solicit when necessary, and default the prefix delegation hint to /60 unless prefixLength is set explicitly.

Some NTT home gateway LAN-side environments only advertise IPv6 by RA/SLAAC and do not answer DHCPv6-PD. That mode should not be modeled as IPv6PrefixDelegation; it needs a separate RA/SLAAC resource design.

IPv4DHCPServer And IPv4DHCPScope​

IPv4DHCPServer declares a DHCPv4 server instance. IPv4DHCPScope binds that server to an interface and declares one address pool plus DHCP options. This split keeps multi-scope DHCP readable.

apiVersion: net.routerd.net/v1alpha1
kind: IPv4DHCPServer
metadata:
  name: dhcp4
spec:
  server: dnsmasq
  managed: true
  listenInterfaces:
    - lan
  dns:
    enabled: true
    upstreamSource: dhcp4
    upstreamInterface: wan
    cacheSize: 1000
apiVersion: net.routerd.net/v1alpha1
kind: IPv4DHCPScope
metadata:
  name: lan-dhcp4
spec:
  server: dhcp4
  interface: lan
  rangeStart: 192.168.160.100
  rangeEnd: 192.168.160.199
  leaseTime: 12h
  routerSource: interfaceAddress
  dnsSource: self
  authoritative: true

routerSource may be interfaceAddress, static, or none. dnsSource may be dhcp4, static, self, or none.

For server: dnsmasq, dnsSource: self advertises the router's LAN IPv4 address as the DNS server and runs dnsmasq as a DNS forwarder/cache. spec.dns.upstreamSource on IPv4DHCPServer controls where dnsmasq forwards queries:

  • dhcp4: use DNS servers observed from DHCPv4 on upstreamInterface.
  • static: use upstreamServers.
  • system: use the host resolver configuration.
  • none: run without upstream forwarders.

If dnsSource is dhcp4 or static on the scope, routerd writes those DNS server addresses directly into the DHCPv4 option and dnsmasq does not need to listen on DNS port 53 for that scope.

spec.interface must refer to an Interface. If that interface still requires adoption because cloud-init or netplan is present, planning blocks DHCP scope management as well.

IPv6DHCPServer And IPv6DHCPScope​

IPv6DHCPServer declares a DHCPv6/RA server instance. IPv6DHCPScope binds it to an IPv6DelegatedAddress, so the LAN prefix follows the WAN DHCPv6-PD lease.

apiVersion: net.routerd.net/v1alpha1
kind: IPv6DHCPServer
metadata:
  name: dhcp6
spec:
  server: dnsmasq
  managed: true
  listenInterfaces:
    - lan
apiVersion: net.routerd.net/v1alpha1
kind: IPv6DHCPScope
metadata:
  name: lan-dhcp6
spec:
  server: dhcp6
  delegatedAddress: lan-ipv6-pd-address
  mode: stateless
  leaseTime: 12h
  defaultRoute: true
  dnsSource: self

mode: stateless means clients use SLAAC for addresses and DHCPv6 for options such as DNS. mode: ra-only sends RA without DHCPv6 address assignment. IPv6 default routes are advertised by RA; DHCPv6 itself has no default gateway option. With dnsSource: self, routerd advertises the delegated LAN IPv6 address, for example pd-prefix::3, as the DNS server. Static IPv6 DNS servers can be advertised with dnsSource: static and dnsServers.

When dnsmasq RA is enabled, routerd uses the same IPv6 DNS server list for DHCPv6 DNS and RA RDNSS. This matters for Android clients, which should be treated as SLAAC/RDNSS clients rather than DHCPv6 clients.

For dnsmasq-backed DHCP and DNS, listenInterfaces is the allow-list of interfaces where dnsmasq may serve. Scopes must bind to an interface listed by their server. Interfaces not listed are rendered as except-interface, so a WAN is not served unless it is explicitly configured.

IPv4SourceNAT​

IPv4SourceNAT declares outbound source NAT without using Linux-specific API names. On Linux this may render to masquerade when translation.type is interfaceAddress. outboundInterface may reference an Interface, PPPoEInterface, or DSLiteTunnel resource.

apiVersion: net.routerd.net/v1alpha1
kind: IPv4SourceNAT
metadata:
  name: lan-to-wan
spec:
  outboundInterface: transix
  sourceCIDRs:
    - 192.168.160.0/24
  translation:
    type: interfaceAddress
    portMapping:
      type: range
      start: 1024
      end: 65535

Other translation forms are reserved for static SNAT and pools:

translation:
  type: address
  address: 203.0.113.10
translation:
  type: pool
  addresses:
    - 203.0.113.10
    - 203.0.113.11

translation.portMapping controls source port handling:

  • auto: let the platform choose source ports.
  • preserve: preserve source ports when the platform can.
  • range: map source ports into start through end.

IPv4PolicyRoute​

IPv4PolicyRoute marks forwarded IPv4 packets that match source and/or destination CIDRs, installs an ip rule for that mark, and installs a default route in a dedicated routing table. outboundInterface may reference an Interface, PPPoEInterface, or DSLiteTunnel resource.

apiVersion: net.routerd.net/v1alpha1
kind: IPv4PolicyRoute
metadata:
  name: lan-via-transix
spec:
  outboundInterface: transix
  table: 100
  priority: 10000
  mark: 256
  sourceCIDRs:
    - 192.168.160.0/24
  destinationCIDRs:
    - 0.0.0.0/0
  routeMetric: 50

This is the first building block for multiple DS-Lite tunnels. Several policies can route different client or destination prefixes through different tunnel resources. Automatic load balancing and conntrack-aware tunnel selection are intentionally separate future resources.

IPv4PolicyRouteSet​

IPv4PolicyRouteSet selects one of multiple policy-route targets by hashing packet fields. On Linux, routerd renders nftables rules that restore an existing conntrack mark, choose a mark with jhash for new flows, save the selected mark back to conntrack, and install one ip rule plus routing table per target.

apiVersion: net.routerd.net/v1alpha1
kind: IPv4PolicyRouteSet
metadata:
  name: lan-dslite-balance
spec:
  mode: hash
  hashFields:
    - sourceAddress
    - destinationAddress
  sourceCIDRs:
    - 192.168.160.0/24
  destinationCIDRs:
    - 0.0.0.0/0
  targets:
    - name: transix-a
      outboundInterface: transix-a
      table: 100
      priority: 10000
      mark: 256
      routeMetric: 50
    - name: transix-b
      outboundInterface: transix-b
      table: 101
      priority: 10001
      mark: 257
      routeMetric: 50

hashFields currently supports sourceAddress and destinationAddress. This is meant for multiple DS-Lite tunnels with different local IPv6 source addresses; each target usually points at a different DSLiteTunnel.

IPv4ReversePathFilter​

IPv4ReversePathFilter controls Linux rp_filter for policy-routing cases where reverse path checks can drop valid asymmetric traffic.

apiVersion: net.routerd.net/v1alpha1
kind: IPv4ReversePathFilter
metadata:
  name: rp-filter-transix-a
spec:
  target: interface
  interface: transix-a
  mode: disabled

target may be all, default, or interface. When target: interface, interface may reference an Interface, PPPoEInterface, or DSLiteTunnel resource. mode may be disabled, strict, or loose, corresponding to Linux values 0, 1, and 2.

PathMTUPolicy​

PathMTUPolicy derives an effective path MTU for traffic leaving one interface toward one or more upstream interfaces. It can advertise that MTU to IPv6 LAN clients through RA and clamp forwarded TCP MSS for IPv4 and IPv6.

apiVersion: net.routerd.net/v1alpha1
kind: PathMTUPolicy
metadata:
  name: lan-wan-mtu
spec:
  fromInterface: lan
  toInterfaces:
    - wan
    - transix
  mtu:
    source: minInterface
  ipv6RA:
    enabled: true
    scope: lan-dhcp6
  tcpMSSClamp:
    enabled: true
    families:
      - ipv4
      - ipv6

mtu.source: minInterface uses the minimum configured MTU among toInterfaces. Plain Interface resources currently default to 1500, PPPoEInterface defaults to 1492, and DSLiteTunnel defaults to 1454 unless their resource sets mtu. mtu.source: static uses mtu.value.

When ipv6RA.enabled is true, ipv6RA.scope references an IPv6DHCPScope. dnsmasq then renders an RA MTU option such as ra-param=ens19,1454.

When tcpMSSClamp.enabled is true, routerd renders nftables forward-chain MSS rules. The fixed MSS is derived from the effective MTU: IPv4 subtracts 40 bytes and IPv6 subtracts 60 bytes. If families is omitted, both ipv4 and ipv6 are enabled.

Minimal Firewall​

Firewall resources use firewall.routerd.net/v1alpha1. The first firewall API is intentionally smaller than a general rule language. It models home-router safety defaults and service exposure:

  • Zone: names a set of router interfaces, such as lan or wan.
  • FirewallPolicy: applies the home-router preset with explicit input and forward defaults.
  • ExposeService: publishes one internal IPv4 service with DNAT plus a matching forward allow rule.

The home-router preset renders input default drop, forward default drop, invalid drop, established/related accept, loopback input accept, LAN-to-WAN forward allow when lan and wan zones exist, and router SSH/DNS/DHCP access only from configured routerAccess zones.

apiVersion: firewall.routerd.net/v1alpha1
kind: Zone
metadata:
  name: lan
spec:
  interfaces:
    - lan
---
apiVersion: firewall.routerd.net/v1alpha1
kind: Zone
metadata:
  name: wan
spec:
  interfaces:
    - wan-pppoe
---
apiVersion: firewall.routerd.net/v1alpha1
kind: FirewallPolicy
metadata:
  name: default-home
spec:
  preset: home-router
  input:
    default: drop
  forward:
    default: drop
  routerAccess:
    ssh:
      fromZones:
        - lan
      wan:
        enabled: false
    dns:
      fromZones:
        - lan
    dhcp:
      fromZones:
        - lan

ExposeService is the first building block for IPv4 port publishing. sources is optional; when present, only those IPv4 source prefixes are accepted. hairpin is accepted in the resource shape, but the first renderer does not synthesize external-address hairpin rules yet because the external address selection model is not defined.

apiVersion: firewall.routerd.net/v1alpha1
kind: ExposeService
metadata:
  name: nas-https
spec:
  family: ipv4
  fromZone: wan
  viaInterface: wan-pppoe
  protocol: tcp
  externalPort: 443
  internalAddress: 192.168.160.20
  internalPort: 443
  sources:
    - 203.0.113.0/24
  hairpin: true

DNSConditionalForwarder​

DNSConditionalForwarder declares domain-specific DNS forwarding. With dnsmasq this renders to server=/domain/upstream.

apiVersion: net.routerd.net/v1alpha1
kind: DNSConditionalForwarder
metadata:
  name: transix-aftr
spec:
  domain: gw.transix.jp
  upstreamSource: static
  upstreamServers:
    - 2404:1a8:7f01:a::3
    - 2404:1a8:7f01:b::3

upstreamSource may be:

  • static: use upstreamServers.
  • dhcp4: use DNS servers learned on upstreamInterface by DHCPv4.
  • dhcp6: use DNS servers learned on upstreamInterface by DHCPv6.

This allows a default DNS policy such as an ad-blocking resolver while keeping provider-specific names, such as DS-Lite AFTR names, on provider DNS.

DSLiteTunnel​

DSLiteTunnel declares a DS-Lite B4 tunnel. On Linux routerd creates an ipip6 tunnel and can install an IPv4 default route through it.

apiVersion: net.routerd.net/v1alpha1
kind: DSLiteTunnel
metadata:
  name: transix
spec:
  interface: wan
  tunnelName: ds-transix
  aftrFQDN: gw.transix.jp
  aftrDNSServers:
    - 2404:1a8:7f01:a::3
    - 2404:1a8:7f01:b::3
  aftrAddressOrdinal: 1
  aftrAddressSelection: ordinalModulo
  localAddressSource: delegatedAddress
  localDelegatedAddress: lan-ipv6-pd-address
  localAddressSuffix: "::100"
  defaultRoute: true
  routeMetric: 50
  mtu: 1454

If remoteAddress is omitted, routerd resolves aftrFQDN as AAAA. aftrDNSServers may be used when the provider only returns the AFTR address from specific DNS servers. AAAA answers are sorted alphabetically; aftrAddressOrdinal selects the 1-based record to use. If omitted, routerd uses the first sorted address.

aftrAddressSelection controls what happens when aftrAddressOrdinal is outside the current AAAA record count:

  • ordinal: fail reconcile for this tunnel.
  • ordinalModulo: wrap around the current record count.

For multiple DS-Lite tunnels, configure different aftrAddressOrdinal values and run reconcile periodically. If the provider changes the AAAA set, each reconcile observes the new sorted set and recreates tunnels whose selected AFTR changed. When using ordinalModulo, keep localAddressSuffix distinct per tunnel so two tunnels can still coexist if the AFTR set shrinks. Health-based failover still needs an active health check resource.

interface is the underlay interface used to reach the AFTR. localAddressSource controls the tunnel's local IPv6 source address:

  • interface: use the first global IPv6 address on interface.
  • static: use localAddress.
  • delegatedAddress: derive an address from an IPv6DelegatedAddress resource referenced by localDelegatedAddress; localAddressSuffix overrides that delegated address suffix for this tunnel.

With delegatedAddress, routerd adds the derived local address as /128 on the delegated address interface when it is missing. This keeps the DS-Lite underlay on WAN while allowing multiple tunnels to use distinct LAN-PD-derived source addresses.