🚀 tun-rs

High-Performance Cross-Platform TUN/TAP Library for Rust

Features • Performance • Installation • Examples • Platforms

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📖 Overview

tun-rs is a powerful, production-ready Rust library for creating and managing TUN and TAP virtual network interfaces. Built with performance and cross-platform compatibility in mind, it provides both synchronous and asynchronous APIs to suit your application's needs.

🎯 Why Choose tun-rs?

• 🏆 Exceptional Performance: Achieves up to 70.6 Gbps throughput with concurrent operations and offload features
• 🌍 True Cross-Platform: Consistent API across Windows, Linux, macOS, BSD, iOS, Android, and more
• ⚡ Async-Ready: Native support for tokio and async-io runtimes
• 🔧 Feature-Rich: Multiple IP addresses, DNS support, hardware offload, multi-queue, and more
• 🛡️ Production-Tested: Used in real-world VPN and networking applications
• 📦 Zero Hassle: Minimal dependencies and straightforward API design

🌟 Key Features

Core Capabilities

• ✅ Dual Mode Support: Both TUN (Layer 3) and TAP (Layer 2) interfaces
• ✅ Multiple IP Addresses: Assign multiple IPv4 and IPv6 addresses to a single interface
• ✅ Sync & Async APIs: Choose between synchronous blocking or async non-blocking operations
• ✅ Runtime Flexibility: Optional tokio or async-io integration for async operations

Platform-Specific Optimizations

• 🚀 Hardware Offload: TSO/GSO support on Linux for maximum throughput
• 🔀 Multi-Queue: Leverage multiple CPU cores with multi-queue support on Linux
• 🍎 macOS TAP: Native TAP implementation using feth pairs
• 🪟 Windows DNS: Full DNS configuration support on Windows

Developer Experience

• 🎯 Consistent Behavior: Unified packet format across all platforms (no platform-specific headers)
• 🔄 Automatic Routing: Consistent route setup behavior when creating devices
• 🛑 Graceful Shutdown: Proper cleanup and shutdown support for sync operations
• 📝 Rich Examples: Comprehensive examples for common use cases

💻 Supported Platforms

Platform	TUN	TAP	Notes
Linux	✅	✅	Full offload & multi-queue support
Windows	✅	✅	Requires wintun.dll / tap-windows
macOS	✅	✅*	TAP via feth pairs
FreeBSD	✅	✅	Full support
OpenBSD	✅	✅	Full support
NetBSD	✅	✅	Full support
Android	✅	-	Via VpnService API
iOS	✅	-	Via NEPacketTunnelProvider
tvOS	✅	-	Via NEPacketTunnelProvider
OpenHarmony	✅	-	TUN support
Other Unix*	✅	-	Via raw file descriptor

Note: For unlisted Unix-like platforms, you can use the raw file descriptor API to integrate with platform-specific TUN implementations.

🚀 Performance Benchmarks

tun-rs delivers exceptional performance compared to other TUN implementations. Benchmarks conducted on Linux (Ubuntu 20.04, i7-13700K, DDR5 32GB) using tun-benchmark2 show impressive results:

🏆 Highlights

• Peak Performance: Up to 70.6 Gbps with concurrent sync operations + offload
• Best Async Performance: 35.7 Gbps async without channel buffering + offload
• Optimized Async: 31.4 Gbps with BytesPool optimization
• Rust vs Go: Peak-to-peak, tun-rs achieves 2.3x higher throughput (70.6 vs 30.1 Gbps)

📊 Performance Comparison

Configuration	Throughput	CPU Usage	Memory	Retransmissions
Sync + Offload + Concurrent	🥇 70.6 Gbps	124%	10.6 MB	2748
Async + Offload	🥈 35.7 Gbps	64.9%	7.4 MB	0
Async + Offload + BytesPool	🥉 31.4 Gbps	93.0%	16.0 MB	0
Sync + Offload + Channel	29.5 Gbps	90.4%	14.9 MB	0
Go + Offload + BytesPool	30.1 Gbps	101.6%	39.5 MB	0
Go + Offload	28.8 Gbps	64.1%	4.2 MB	0
Async (no offload)	8.84 Gbps	87.6%	3.7 MB	326

💡 Key Takeaways

1. Hardware Offload is Critical: TSO/GSO increases throughput by 3-4x
2. Concurrent I/O Scales: Dual-threaded sync operations achieve the highest throughput
3. Memory Efficiency: tun-rs uses significantly less memory than Go alternatives
4. Zero Retransmissions: Offload configurations achieve reliable, lossless transmission
5. Flexible Performance Profile: Choose async for low CPU usage or sync+concurrent for maximum throughput

For detailed benchmark methodology and results, visit tun-benchmark2

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📦 Installation

Add tun-rs to your Cargo.toml:

[dependencies]

# Base synchronous API (no async runtime required)

tun-rs = "2"



# For Tokio async runtime

tun-rs = { version = "2", features = ["async"] }



# For async-std, smol, or other async-io based runtimes

tun-rs = { version = "2", features = ["async_io"] }



# For framed codec support (with tokio)

tun-rs = { version = "2", features = ["async", "async_framed"] }

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🎓 Quick Start

Basic Synchronous TUN Interface

Create and use a TUN interface in just a few lines:

use tun_rs::DeviceBuilder;

fn main() -> std::io::Result<()> {
    // Create a TUN device with IPv4 and IPv6 addresses
    let dev = DeviceBuilder::new()
        .ipv4("10.0.0.1", 24, None)
        .ipv6("CDCD:910A:2222:5498:8475:1111:3900:2021", 64)
        .mtu(1400)
        .build_sync()?;

    println!("TUN device created: {:?}", dev.name());
    
    let mut buf = [0; 1400];
    loop {
        let amount = dev.recv(&mut buf)?;
        println!("Received {} bytes: {:?}", amount, &buf[0..amount]);
    }
}

Asynchronous TUN with Tokio

Use async/await for non-blocking I/O:

use tun_rs::DeviceBuilder;

#[tokio::main]
async fn main() -> std::io::Result<()> {
    let dev = DeviceBuilder::new()
        .ipv4("10.0.0.1", 24, None)
        .build_async()?;

    println!("Async TUN device ready!");
    
    let mut buf = vec![0; 65536];
    loop {
        let len = dev.recv(&mut buf).await?;
        println!("Received packet: {} bytes", len);
        
        // Echo the packet back
        dev.send(&buf[..len]).await?;
    }
}

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📚 Examples

Multiple IP Addresses

Assign multiple IP addresses to a single interface:

use tun_rs::DeviceBuilder;

#[tokio::main]
async fn main() -> std::io::Result<()> {
    let dev = DeviceBuilder::new()
        .ipv4("10.0.0.1", 24, None)
        .build_async()?;

    // Add multiple IPv4 addresses
    dev.add_address_v4("10.1.0.1", 24)?;
    dev.add_address_v4("10.2.0.1", 24)?;
    
    // Add multiple IPv6 addresses
    dev.add_address_v6("CDCD:910A:2222:5498:8475:1111:3900:2021", 64)?;
    dev.add_address_v6("BDCD:910A:2222:5498:8475:1111:3900:2021", 64)?;

    // Remove addresses when needed
    // dev.remove_address("10.2.0.1".parse().unwrap())?;
    
    println!("All addresses: {:?}", dev.addresses()?);

    let mut buf = vec![0; 65536];
    loop {
        let len = dev.recv(&mut buf).await?;
        println!("Received on multi-IP device: {} bytes", len);
    }
}

Using Raw File Descriptor (Unix)

Create a device from an existing file descriptor (useful for iOS, Android, or custom TUN implementations):

use tun_rs::SyncDevice;
use std::os::unix::io::RawFd;

fn main() -> std::io::Result<()> {
    // The fd must be a valid file descriptor obtained from:
    // - iOS: NEPacketTunnelProvider's packetFlow.value(forKeyPath: "socket.fileDescriptor")
    // - Android: VpnService.Builder().establish().getFd()
    // - Linux: open("/dev/net/tun", O_RDWR)
    // - Or any other platform-specific TUN device API
    let fd: RawFd = get_tun_fd_from_platform(); // Your platform-specific function
    
    // Take ownership of the file descriptor
    let dev = unsafe { SyncDevice::from_fd(fd)? };
    
    // Or borrow without taking ownership
    // let dev = unsafe { tun_rs::BorrowedSyncDevice::borrow_raw(fd)? };

    // Also works with async devices
    // let async_dev = unsafe { tun_rs::AsyncDevice::from_fd(fd)? };

    let mut buf = [0; 4096];
    loop {
        let amount = dev.recv(&mut buf)?;
        println!("Received: {:?}", &buf[0..amount]);
    }
}

// NOTE: This is example-only code. In real applications, obtain the fd from:
// - iOS: tunFd = packetFlow.value(forKeyPath: "socket.fileDescriptor") as! Int32
// - Android: fd = vpnInterface.getFd()  (from VpnService.Builder().establish())
// - Linux: fd = open("/dev/net/tun", O_RDWR) or use DeviceBuilder instead
fn get_tun_fd_from_platform() -> RawFd {
    // See the iOS and Android sections below for complete working examples
    unimplemented!("Replace with your platform-specific fd acquisition code")
}

Linux Hardware Offload (TSO/GSO)

Maximize performance with hardware offload features:

use tun_rs::DeviceBuilder;
#[cfg(target_os = "linux")]
use tun_rs::{GROTable, IDEAL_BATCH_SIZE, VIRTIO_NET_HDR_LEN};

#[cfg(target_os = "linux")]
fn main() -> std::io::Result<()> {
    let builder = DeviceBuilder::new()
        .offload(true)  // Enable TSO/GSO for 3-4x throughput boost
        // .multi_queue(true)  // Enable multi-queue for concurrent I/O
        .ipv4("10.0.0.1", 24, None)
        .mtu(1400);

    let dev = builder.build_sync()?;
    
    // For multi-queue, clone the device for use in other threads
    // let dev_clone = dev.try_clone()?; 
    
    let mut original_buffer = vec![0; VIRTIO_NET_HDR_LEN + 65535];
    let mut bufs = vec![vec![0u8; 1500]; IDEAL_BATCH_SIZE];
    let mut sizes = vec![0; IDEAL_BATCH_SIZE];
    
    // Optional: Use GROTable for Generic Receive Offload optimization
    // let mut gro_table = GROTable::default();
    
    loop {
        let num = dev.recv_multiple(&mut original_buffer, &mut bufs, &mut sizes, 0)?;
        println!("Received {} packets in batch", num);
        for i in 0..num {
            println!("Packet {}: {} bytes", i, sizes[i]);
        }
    }
}

TAP Interface (Layer 2)

use tun_rs::{DeviceBuilder, Layer};

#[tokio::main]
async fn main() -> std::io::Result<()> {
    let dev = DeviceBuilder::new()
        .layer(Layer::L2)  // TAP mode for Ethernet frames
        .build_async()?;

    let mut buf = vec![0; 65536];
    loop {
        let len = dev.recv(&mut buf).await?;
        // Process Ethernet frame
        println!("Ethernet frame: {} bytes", len);
    }
}

💡 More Examples: Check out examples/ for additional use cases including:

• ICMP ping responder
• iOS/Android integration
• Framed codec usage
• Interruptible operations
• And more!

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🔧 Platform-Specific Setup

Linux

Requirements:

• TUN kernel module must be loaded: sudo modprobe tun
• Root privileges or CAP_NET_ADMIN capability required

Performance Tips:

• Enable hardware offload for 3-4x throughput improvement
• Use multi-queue for concurrent operations across multiple cores
• Consider using recv_multiple() for batch packet processing

# Load TUN module

sudo modprobe tun


# Run your application

sudo ./your_app

macOS & BSD

Automatic Routing: tun-rs automatically configures routes based on your IP settings:

# Example: This route is added automatically for 10.0.0.0/24

sudo route -n add -net 10.0.0.0/24 10.0.0.1

TAP Mode on macOS:

• Implemented using feth interface pairs
• Interfaces persist until explicitly destroyed
• Uses BPF for I/O operations
• Multiple file descriptors involved (be careful with AsRawFd)

use tun_rs::{DeviceBuilder, Layer};

fn main() -> std::io::Result<()> {
    let dev = DeviceBuilder::new()
        .layer(Layer::L2)  // TAP mode
        .ipv4("10.0.0.1", 24, None)
        .build_sync()?;
    
    // TAP interface is ready
    println!("macOS TAP device: {:?}", dev.name());
    Ok(())
}

Windows

TUN Mode:

1. Download wintun.dll matching your architecture (x64, x86, ARM, or ARM64)
2. Place wintun.dll in the same directory as your executable
3. Run your application as Administrator

TAP Mode:

1. Install tap-windows matching your architecture
2. Run your application as Administrator

use tun_rs::DeviceBuilder;

fn main() -> std::io::Result<()> {
    // Windows supports DNS configuration
    let dev = DeviceBuilder::new()
        .ipv4("10.0.0.1", 24, None)
        .build_sync()?;
    
    // Set DNS servers (Windows-specific)
    #[cfg(windows)]
    {
        // Configure DNS if needed
        println!("TUN version: {:?}", dev.version());
    }
    
    Ok(())
}

iOS / tvOS

Integrate with NEPacketTunnelProvider:

// Swift
class PacketTunnelProvider: NEPacketTunnelProvider {
    override func startTunnel(options: [String : NSObject]?, completionHandler: @escaping (Error?) -> Void) {
        let tunnelNetworkSettings = createTunnelSettings() // Configure TUN address, DNS, mtu, routing...
        setTunnelNetworkSettings(tunnelNetworkSettings) { [weak self] error in
            // Get the file descriptor from packet flow
            let tunFd = self?.packetFlow.value(forKeyPath: "socket.fileDescriptor") as! Int32
            DispatchQueue.global(qos: .default).async {
                start_tun(tunFd)
            }
            completionHandler(nil)
        }
    }
}

// Rust FFI
#[no_mangle]
pub extern "C" fn start_tun(fd: std::os::raw::c_int) {
    // Create device from file descriptor
    let tun = unsafe { tun_rs::SyncDevice::from_fd(fd).unwrap() };
    let mut buf = [0u8; 1500];
    while let Ok(len) = tun.recv(&mut buf) {
        // Process packet
        println!("iOS: received {} bytes", len);
    }
}

Android

Integrate with Android VpnService:

// Java
private void startVpn() {
    VpnService.Builder builder = new VpnService.Builder();
    builder
        .allowFamily(OsConstants.AF_INET)
        .addAddress("10.0.0.2", 24);
    ParcelFileDescriptor vpnInterface = builder
        .setSession("tun-rs")
        .establish();
    int fd = vpnInterface.getFd();
    
    // Pass fd to Rust via JNI
    startTunNative(fd);
}

// Rust JNI binding
#[no_mangle]
pub extern "C" fn startTunNative(fd: std::os::raw::c_int) {
    let tun = unsafe { tun_rs::SyncDevice::from_fd(fd).unwrap() };
    let mut buf = [0u8; 1500];
    while let Ok(len) = tun.recv(&mut buf) {
        // Process packet
    }
}

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🤝 Comparison with Other Libraries

Feature	tun-rs	go-tun	tun-tap/tokio-tun
Peak Throughput	70.6 Gbps	30.1 Gbps	Not benchmarked
Memory Usage	✅ Low (3-16 MB)	❌ High (39-43 MB)	Unknown
Cross-Platform	✅ 11+ platforms	⚠️ Limited	⚠️ Linux/macOS only
Async Support	✅ Tokio + async-io	✅ Go runtime	⚠️ Varies by lib
Hardware Offload	✅ TSO/GSO/Multi-queue	✅ TSO/GSO	❌ No
Multiple IPs	✅ Yes	❌ No	❌ No
TAP on macOS	✅ Yes (feth)	❌ No	❌ No
Mobile Support	✅ iOS/Android	❌ No	❌ No

Note: Benchmarks for go-tun were conducted in the same environment. Other Rust TUN libraries lack comprehensive cross-platform support and haven't been benchmarked in our test suite.

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🛠️ API Overview

Device Creation

use tun_rs::{DeviceBuilder, Layer};

// Build with configuration
let dev = DeviceBuilder::new()
    .name("tun0")                    // Optional: specify interface name
    .layer(Layer::L3)                // L3 (TUN) or L2 (TAP)
    .ipv4("10.0.0.1", 24, None)     // IPv4 address, prefix, destination
    .ipv6("fd00::1", 64)            // IPv6 address, prefix
    .mtu(1400)                       // Set MTU
    .offload(true)                   // Enable offload (Linux only)
    .multi_queue(true)               // Enable multi-queue (Linux only)
    .build_sync()?;                  // Or build_async()

Core Operations

// Receive packet
let mut buf = vec![0; 65536];
let len = dev.recv(&mut buf)?;

// Send packet
dev.send(&packet)?;

// Device information
let name = dev.name()?;
let mtu = dev.mtu()?;
let addresses = dev.addresses()?;
let if_index = dev.if_index()?;

// Address management
dev.add_address_v4("10.1.0.1", 24)?;
dev.add_address_v6("fd00::2", 64)?;
dev.remove_address(addr)?;

Async Operations

// Async recv/send
let len = dev.recv(&mut buf).await?;
dev.send(&packet).await?;

// Use with tokio::select!
tokio::select! {
    result = dev.recv(&mut buf) => { /* handle */ }
    _ = shutdown_signal => { /* cleanup */ }
}

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📖 Documentation

• API Documentation: docs.rs/tun-rs
• Examples: github.com/tun-rs/tun-rs/tree/main/examples
• Benchmark Details: github.com/tun-rs/tun-benchmark2

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🐛 Troubleshooting

Linux/BSD/macOS: Run with sudo or grant CAP_NET_ADMIN capability:

sudo ./your_app

# Or grant capability

sudo setcap cap_net_admin+ep ./your_app

Windows: Run as Administrator

Android/iOS: Use platform VPN APIs to obtain file descriptor

sudo modprobe tun

# Make it persistent

echo "tun" | sudo tee -a /etc/modules

1. Download from wintun.net
2. Extract the DLL for your architecture (x64, x86, ARM, ARM64)
3. Place in the same directory as your executable

On Linux, enable hardware offload for 3-4x performance boost:

let dev = DeviceBuilder::new()
    .offload(true)
    .build_sync()?;

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🙏 Contributing

Contributions are welcome! Please feel free to submit a Pull Request. For major changes, please open an issue first to discuss what you would like to change.

Development

# Clone repository

git clone https://github.com/tun-rs/tun-rs.git

cd tun-rs


# Run tests (requires root/admin)

cargo test


# Build examples

cargo build --examples --features async


# Run example

sudo ./target/debug/examples/read

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📄 License

Licensed under the Apache License 2.0

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🌟 Acknowledgments

• Thanks to all contributors
• Inspired by the networking community's need for high-performance TUN/TAP implementations
• Special thanks to the Rust async ecosystem (tokio, async-io) for making async networking seamless

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Made with ❤️ by the tun-rs team