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VNet — Lightweight Virtual Network Tool

This project is a lightweight virtual network solution based on WebSocket, supporting cross-platform TUN device creation and IPv4/IPv6 dual-stack communication. Core design concepts:

• Implement virtual network tunnel using WebSocket protocol, simplifying NAT traversal and firewall traversal
• Support multi-platform (Linux/macOS/Windows/Android) TUN device creation and configuration
• Provide unified client and server interfaces, supporting IPv4/IPv6 dual-stack communication
• Built-in broadcast/multicast support for device discovery and communication within LAN

• Note: This is an experimental project, not fully tested, not recommended for production use.

Core Features

Cross-platform TUN Support

VNet supports creating and configuring TUN virtual network devices on multiple operating systems:

• Linux: Configure network interface using ip command
• macOS: Configure network interface using ifconfig command
• Windows: Configure network interface using netsh command
• Android: Create TUN device through Android VpnService API

IPv4/IPv6 Dual Stack

VNet fully supports IPv4 and IPv6 dual-stack communication:

• Client can configure both IPv4 and IPv6 addresses simultaneously
• Server supports IPv4/IPv6 packet parsing and forwarding
• Automatic IPv6 multicast address configuration

WebSocket Tunnel

Using WebSocket protocol as transport layer, with the following advantages:

• Traverse NAT and firewalls
• Support TLS/SSL encrypted transmission
• Automatic reconnection mechanism
• Cross-platform compatibility

Broadcast/Multicast Support

Server supports fan-out forwarding of broadcast and multicast packets:

• Automatic identification of broadcast/multicast target addresses
• Support IPv4 broadcast address (255.255.255.255) and multicast address range (224.0.0.0 - 239.255.255.255)
• Support IPv6 multicast address (ff00::/8)

Quick Start

Server Deployment

# Build server
go build -o vnet-server ./vnet-server

# Start server (listening on port 8080, using key mysecret)
./vnet-server -listen :8080 -key mysecret

Client Usage

# Build client
go build -o vnet ./vnet

# Start client (connect to server, configure virtual IP)
./vnet -server ws://127.0.0.1:8080/ws -ip 10.0.0.2/24 -key mysecret

# Optional: Configure IPv6 address
./vnet -server ws://127.0.0.1:8080/ws -ip 10.0.0.2/24 -ipv6 fd00::2/64 -key mysecret

Android Application

Android application provides graphical configuration interface:

1. Configure server address
2. Enter virtual IP address (IPv4/IPv6)
3. Enter authentication key
4. Click "Connect" button

Architecture

Client Architecture

┌─────────────┐    ┌─────────────┐    ┌─────────────┐
│  Application│    │  Application│    │  Application│
├─────────────┤    ├─────────────┤    ├─────────────┤
│    TUN      │◄──►│   WebSocket │◄──►│    Server   │
│   Driver    │    │   Client    │    │             │
└─────────────┘    └─────────────┘    └─────────────┘

Server Architecture

┌─────────────┐    ┌─────────────┐    ┌─────────────┐
│  Client A   │◄──►│             │◄──►│  Client B   │
└─────────────┘    │   Server    │    └─────────────┘
                   │  WebSocket  │
┌─────────────┐    │   Server    │    ┌─────────────┐
│  Client C   │◄──►│             │◄──►│  Client D   │
└─────────────┘    └─────────────┘    └─────────────┘

Configuration Parameters

Server Parameters

Parameter	Description	Default
-listen	Listen address	:8080
-key	Authentication key	None (required)

Client Parameters

Parameter	Description	Default
-server	Server address	ws://127.0.0.1:8080/ws
-ip	IPv4 address and subnet mask	None (required)
-ipv6	IPv6 address and subnet mask	Empty (optional)
-prefix	TUN device prefix	vnet
-key	Authentication key	None (required)

Protocol Details

Packet Format

VNet uses raw IP packets as WebSocket message content:

• Message Type: BinaryMessage
• Data Format: Raw IP packet (including IP header)
• Maximum Transmission Unit: 1500 bytes

IP Address Parsing

Server extracts target address by parsing IP packet header:

• IPv4: Extract destination IP address from bytes 16-19
• IPv6: Extract destination IP address from bytes 24-39

Authentication Mechanism

Client passes authentication information through URL parameters during WebSocket connection:

ws://server:port/ws?key=secret&ip=10.0.0.2

Development Notes

Build Requirements

• Go 1.26.4 or higher
• Android Studio (for building Android application)
• Git

Project Structure

vnet/
├── vnet/                    # Client code
│   ├── main.go             # Client main program
│   ├── tun_linux.go        # Linux TUN implementation
│   ├── tun_darwin.go       # macOS TUN implementation
│   └── tun_windows.go      # Windows TUN implementation
├── vnet-server/            # Server code
│   └── main.go             # Server main program
├── android/                # Android application
│   └── app/src/main/java/com/carryrao/vnet/
│       ├── MainActivity.kt        # Main interface
│       ├── VnetVpnService.kt      # VPN service
│       ├── VnetConnection.kt      # WebSocket connection
│       ├── VnetLogger.kt          # Log recording
│       └── VnetStats.kt           # Statistics information
├── go.mod                  # Go module definition
└── go.sum                  # Dependency checksums

Dependencies

• github.com/gorilla/websocket: WebSocket protocol implementation
• golang.zx2c4.com/wireguard/tun: Cross-platform TUN device creation

Use Cases

1. Remote Work: Securely access company intranet resources
2. IoT Device Communication: Direct communication between devices
3. Game Acceleration: Low-latency network connection
4. Network Debugging: Test network applications in different network environments

License

Apache License 2.0