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Add IPv6 inside the PPP session and use enp2s0 in the example

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- wan.ipv6.transport = "ppp": IPv6CP in pppd, router advertisements and
  DHCPv6 prefix delegation on the PPP device, DHCPv6 accepted on the PPP
  device, IPv6 MSS clamped to MTU-60. Allowed on a shared single-NIC
  link. A build-time check requires a PPPoE uplink.
- IPv4 MSS clamping now only matches IPv4 packets.
- The example uses the new box's NIC name (enp2s0).

Covered by the onestick VM test (radvd and a minimal DHCPv6-PD
responder as the ISP) and assertion cases.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
This commit is contained in:
nils
2026-10-28 15:03:57 +01:00
co-authored by Claude Sonnet 5.5
parent b5429ad876
commit 70dddad206
9 changed files with 227 additions and 22 deletions
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PLAN.md
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@@ -118,7 +118,7 @@ Learned along the way:
- **Router on a stick**: `wan.interface` may also carry LANs, but only for PPPoE on a VLAN with IPv6 disabled (the untagged link is then free for a LAN; native IPv6 needs an untagged uplink). In that mode only the PPP device is an uplink in the firewall, so LAN traffic can never match WAN rules; the WAN VLAN is created from the LAN's/trunk's networkd unit. A LAN VLAN may not reuse the PPPoE VLAN id.
- **Commit-confirm** (`router.rollback`, on by default): `router-arm [time]` starts a transient timer; `router-rollback` re-activates the confirmed generation (`/nix/var/nix/profiles/system`, else `/run/booted-system`) with `switch-to-configuration test`; `router-confirm` stops the timer, sets the profile and the boot default. Deploy with `nix run .#deploy -- <flake-attr> <user@host> [--yes]`: build, arm, `nixos-rebuild test --target-host`, check SSH, confirm. A lost connection means the timer rolls back by itself; a reboot also returns to the confirmed generation.
- `systemd.network.wait-online` waits only for the LAN devices (not the uplink) by default: an unplugged uplink must not block boot or activation, while VLAN devices still exist before Kea starts (anyInterface broke this; caught by `vlans`).
- `examples/desktop` + `nixosConfigurations.example` is the deployable starting point (single NIC `eno1`, PPPoE VLAN 1001); it is built as a flake check. Secrets stay on the device (`/var/lib/router/pppoe-password`).
- `examples/desktop` + `nixosConfigurations.example` is the deployable starting point (single NIC `enp2s0` on the new box (antigua calls its NIC `eno1`), PPPoE VLAN 1001); it is built as a flake check. Secrets stay on the device (`/var/lib/router/pppoe-password`).
- Open for real hardware: Nix is still on the device (`router-confirm` uses `nix-env`); no image/read-only root yet.
## Local DNS and DHCP reservations (confirmed)
@@ -150,7 +150,7 @@ Source: the user's infra repo (host `antigua`, NixOS, dnsmasq + networkd + pppd)
Done: PPPoE on VLAN 1001 over the shared NIC (`eno1`, LAN untagged), DNS records/domain/forward zones/DHCP reservations/DNS for site-to-site peers, WireGuard (freifunk dial-out with masquerade, family site-to-site with PSK, mobile-clients road warrior), MSS clamp.
Open (in rough order):
1. **IPv6 over the PPP session**: antigua runs `+ipv6` and DHCPv6-PD on the PPP device itself (not on an untagged link); the module only knows native IPv6 on the uplink. Needs ipv6cp in pppd, networkd DHCPv6/RA on the PPP device, PD to the LAN.
1. ~~**IPv6 over the PPP session**~~ **done**: `wan.ipv6.transport = "ppp"` (default `native`) enables IPv6CP in pppd, RA + DHCPv6-PD via networkd on the PPP device, PD to the LAN, DHCPv6 replies accepted on the PPP device and the IPv6 MSS clamped to MTU-60 (1432). Allowed on a shared link (single NIC). Tested in `onestick` (ISP with radvd and a minimal DHCPv6-PD responder, since Kea cannot serve point-to-point links); mutation-tested (MSS clamp, DHCPv6 input rule). `ipv6cp-use-ipaddr` is set as on antigua.
2. **ULA on the LAN** (`fd2c:cdef:cde9::1/64`, announced by RA): needs an extra static address / ULA option per LAN.
3. **Tunnel trust and addressing**: antigua trusts `family`, `freifunk`, `mobile-clients` fully and gives two of them no address; check the schema covers this (`allowManagement`, `dns`, `internet` per tunnel; `addresses` may be empty?).
4. **PPP device name**: `wan` on antigua, `pppoe-wan` here; `ddclient` (Cloudflare, uses the interface address) must follow, or make the name configurable.