ddidderr 956650ea8a feat(relay): filter unsafe Ethernet control traffic
Relay forwarding now applies the MVP L2 safety policy before choosing output
peers. It drops jumbo frames, link-local switch-control destinations, EAPOL,
LLDP, and slow-protocol frames in both directions, and it blocks remote clients
from sending DHCP server replies or IPv6 router advertisements toward the LAN.

The filters live in the room forwarding path so the pure admission/forwarding
tests and live QUIC datagram path share the same policy. Gateway-origin DHCP
server replies remain allowed, which preserves the plan's goal that remote TAP
clients can receive LAN DHCP through the tunnel.

Test Plan:
- cargo fmt --check
- cargo test --workspace
- cargo clippy --workspace --all-targets -- -D warnings

Refs: PLAN.md L2 control-plane safety filters
2026-05-21 18:00:11 +02:00
2026-05-21 16:54:26 +02:00
2026-05-21 17:00:58 +02:00

softlan-vpn

Monorepo for a Layer 2 over QUIC LAN party bridge.

Workspace crates

  • lanparty-proto: shared frame format, MAC validation, MTU helpers.
  • lanparty-ctrl: control-plane messages (join/hello/role/version).
  • lanparty-obs: shared diagnostics/logging event models.
  • lanparty-client-core: platform-agnostic client session state.
  • lanparty-client-win: Windows TAP + route/metric handling binary.
  • lanparty-gateway: Linux AF_PACKET gateway binary.
  • lanparty-relay: public QUIC relay binary.

lanparty-proto

Transport-agnostic tunnel contract shared by all binaries:

  • overlay datagram header encoding and decoding
  • Ethernet frame header parsing
  • MAC address parsing and identity validation
  • QUIC datagram to TAP MTU budget helpers

lanparty-ctrl

Reliable control-plane schema shared by the QUIC stream handlers:

  • endpoint hello messages with role, room, MAC, and datagram budget
  • server welcome, reject, peer lifecycle, stats, and disconnect messages
  • room-code, role/MAC, peer-id, and effective-MTU validation
  • length-prefixed JSON control frames for reliable QUIC streams

lanparty-obs

Shared diagnostics and structured logging vocabulary:

  • gateway/relay frame logs with MACs, ethertype, length, peer, and action
  • tunnel counters shared by control messages and runtime diagnostics
  • client connectivity/TAP diagnostics and user-facing status messages

lanparty-relay

Public relay binary and relay-owned room state:

  • QUIC endpoint binding and first-stream hello/welcome admission
  • room admission for clients and gateways
  • one gateway per room, duplicate client MAC rejection, and room limits
  • stable effective room MTU chosen before Ethernet datagrams flow
  • live Ethernet datagram forwarding with no ingress reflection
  • L2 safety filters for jumbo, switch-control, DHCP-server, and IPv6-RA frames
  • peer leave cleanup for room membership and MAC indexes

Build

cargo check --workspace

Relay

cargo run -p lanparty-relay -- --listen 443/udp

--listen accepts either a socket address or a UDP port shorthand such as 443/udp. The relay binds a QUIC endpoint, accepts a control-stream hello, replies with welcome or reject, and forwards live Ethernet QUIC datagrams between accepted peers in the same room. It currently uses a generated self-signed development certificate; production certificate and client trust handling remain future work.

S
Description
A simple one-click Layer 2 tunnel software (Windows 11 client) to bridge people who cannot participate in person at a LAN party to the LAN party. And a simple server endpoint (Linux) software that runs physically at the LAN party and bridges the tunneled traffic and the real LAN network.
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