EasyTier

EasyTier is a distributed virtual network (SD-WAN) system built with C++20 coroutines on top of the async_net async networking library. It securely connects geographically distributed devices into a single virtual LAN, with support for smart routing, NAT traversal, subnet proxying, and more.

Features

• Decentralized Architecture — Equal peer nodes, no central service required, DHT-based discovery
• Cross-Platform — Linux / macOS / Windows / FreeBSD, x86 / ARM / MIPS compatible
• Smart Routing — Distance-vector protocol (Bellman-Ford), latency-aware, automatic path selection
• Efficient NAT Traversal — STUN + ICE + NAT type detection, can punch through NAT4-NAT4
• Subnet Proxy — Nodes share local subnets network-wide, CIDR route broadcasting
• Multi-Protocol Transport — TCP / UDP / WebSocket / QUIC with automatic fallback
• Loss Resilience — KCP reliable UDP with ARQ + fast retransmit, optimized for lossy links
• End-to-End Security — AES-256-GCM encryption + X25519 key exchange, MITM prevention
• Zero-Copy Design — Full-pipeline std::span<uint8_t> zero-copy, high-performance data transfer
• Web API — Built-in RESTful management interface for node status and configuration

Architecture

┌─────────────────────────────────────────────────┐
│                  EasyTier Node                   │
├──────────┬──────────┬───────────┬───────────────┤
│  TUN     │  Subnet  │  Smart    │  KCP          │
│  Device  │  Proxy   │  Router   │  Session      │
├──────────┴──────────┴───────────┴───────────────┤
│              Peer Manager                        │
│         (P2P / Relay / Multipath)               │
├──────────┬──────────┬───────────┬───────────────┤
│  TCP     │  UDP     │ WebSocket │  QUIC         │
│Transport │Transport │ Transport │  Transport    │
├──────────┴──────────┴───────────┴───────────────┤
│         Crypto (AES-GCM + X25519)               │
├──────────┬──────────┬───────────────────────────┤
│  NAT     │  DHT     │  Web API                  │
│Traversal │  Node    │  (REST)                   │
├──────────┴──────────┴───────────────────────────┤
│            async_net (C++20 Coroutines)          │
└─────────────────────────────────────────────────┘

Modules

Module	Path	Description
Common	include/easytier/common/	Protocol definitions, config, types
TUN	src/tun/	Virtual network device (Linux/macOS/Windows/FreeBSD)
Registry	src/registry/	Centralized registration & node discovery
Peer	src/peer/	P2P direct connect, relay, peer management
Router	src/route/	Distance-vector smart routing
Crypto	src/crypto/	AES-256-GCM encryption, X25519 key exchange
NAT	src/nat/	STUN, NAT type detection, ICE negotiation
DHT	src/dht/	Distributed hash table for decentralized discovery
Web	src/web/	RESTful Web API
Subnet	src/subnet/	Subnet proxy & route broadcasting
Transport	src/transport/	Multi-protocol transport (WS/QUIC) & transport manager
KCP	src/kcp/	KCP reliable UDP sessions
Node	src/node/	Node lifecycle management

Building

Prerequisites

• C++20 compiler (GCC 12+ / Clang 15+ / MSVC 2022+)
• CMake 3.20+
• async_net async networking library
• vcpkg (optional, for third-party dependency management)

Compile

mkdir build && cd build
cmake .. -DCMAKE_BUILD_TYPE=Release
make -j$(nproc)

Build Artifacts

Target	Description
libeasytier_lib.a	Static library
easytier_server	Registry server
easytier_client	Node client

Quick Start

1. Start Registry Server

./easytier_server --port 5599

2. Start a Node

./easytier_client \
  --name "node1" \
  --vip 10.0.0.1 \
  --registry tcp://registry.example.com:5599 \
  --peers tcp://peer2.example.com:5599

3. Check Status

curl http://localhost:8080/api/status

Configuration

Option	Description	Default
--name	Node name	easytier-node
--vip	Virtual IP address	10.0.0.1
--registry	Registry server address	tcp://127.0.0.1:5599
--peers	Initial peer addresses (comma-separated)	—
--subnet	Shared subnet (CIDR notation)	—
--enable-relay	Enable relay forwarding	false
--listen-port	Listen port	5599

Project Status

• MVP: Registry, P2P connection, relay, TUN, routing
• Security: AES-GCM + X25519 key exchange
• NAT Traversal: STUN + NAT detection + ICE
• DHT decentralized node discovery
• Web API management interface
• Smart routing (distance-vector + latency-based selection)
• Subnet proxy (CIDR broadcasting)
• Multi-protocol transport (WebSocket / QUIC)
• KCP reliable UDP
• Cross-platform TUN (Linux / macOS / Windows / FreeBSD)

License

MIT License