100.64.0.0/10 was a bad default: it is exactly Tailscale's range, and
carrier-grade NAT's. There is no IPv4 range that is free on every host, so
there is now no default at all — IPv4 is off until --ipv4-range names one.
IPv6 is unaffected and still works out of the box, because a ULA derived
from the network id collides with essentially nothing.
The more serious problem this exposed: the range is an input to the address
derivation, and each agent derives every peer's address itself. Two members
configured with different ranges would therefore derive different addresses
for each other and IPv4 would silently misroute. So the range now travels
in the announcement — not as a request and never trusted, only so the
mismatch is seen. A peer whose range disagrees gets no IPv4 address here,
keeps working over IPv6, and the reason is reported with both ranges named.
The announcement format goes to version 2. postcard is not
self-describing, so an older peer cannot read it; the version check already
catches that and now says which side needs updating.
The (Ipv4Addr, u8) tuple that had spread across six modules is now an
Ipv4Range with validation, Display and FromStr, so a bad --ipv4-range is
refused with a reason instead of being accepted and misbehaving later. It
is also rejected when passed without --wireguard rather than ignored.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Every member now also derives an IPv4 address, from the same inputs as its
IPv6 one, into 100.64.0.0/10 by default. The range is configurable and IPv4
can be turned off with --no-ipv4.
IPv4 is honestly weaker than IPv6 here and the code says so. A 64 bit
interface identifier makes an IPv6 collision impossible in practice; IPv4
has nothing like that room, and in a /10 with 50 members two will derive the
same address about 0.03% of the time. A mesh with no coordinator cannot
allocate around that, so a collision is detected and resolved instead: the
member whose public key sorts lower keeps the address, a rule every member
computes identically and therefore agrees on. The other keeps IPv6 and is
flagged in the status. IPv6 always works; IPv4 almost always works and
degrades predictably.
Routing and address-ownership enforcement now cover both families: a packet
goes to the peer that owns its destination, and a decrypted packet is
dropped unless its source is an address derived for the peer that sent it,
IPv4 included.
Six new tests, among them a real IPv4 packet crossing a tunnel next to an
IPv6 one, a spoofed IPv4 source being dropped, and an IPv6-only overlay.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
The first IP plugin, built on the data plane boundary the core already had.
Plugin:
- one X25519 key per network in the plugin's own wireguard.sqlite, separate
from the iroh identity and from the network secret; a damaged store is an
error, never a silently regenerated identity
- deterministic IPv6 ULA overlay: every member derives the same /64 from the
network id and its own /128 from its WireGuard public key, so no
coordinator allocates addresses
- AllowedIPs are derived locally, never taken from a peer's announcement, so
a member cannot claim another member's overlay address; a mismatched claim
is rejected
- bounded, versioned, validated announcement carried as the existing opaque
capability payload, which the core still never parses
- each agent builds its own full-mesh configuration (N-1 peers) and
reconciles on every change and on a timer, repairing drift
- WireguardBackend abstraction: RecordingBackend in memory, and WgToolBackend
driving real wg/ip on Linux, split into a pure planner plus parsers and a
thin executor so everything interesting is testable without root
Core, three generic additions the plugin needed:
- IpPlugin::on_network_activated, so per-network state is ready before peers
- PluginContext for re-announcements and error reports from plugin tasks,
with errors counted by the owning network runtime
- IpPlugin::shutdown, awaited with a grace period, so system objects go away
94 tests pass offline with no privileges: 35 new WireGuard unit tests and 12
integration tests over real iroh connections. The real wg/ip backend needs
root and is behind --ignored in tests/wireguard_system.rs; it was not run.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
tsunagiandClaude Opus 5