TUN interfaces 
This crate allows the creation and usage of TUN interfaces, the aim is to make this cross-platform.
Usage
First, add the following to your Cargo.toml:
[dependencies]
tun = "0.5"Next, add this to your crate root:
extern crate tun;If you want to use the TUN interface with mio/tokio, you need to enable the async feature:
[dependencies]
tun = { version = "0.5", features = ["async"] }Example
The following example creates and configures a TUN interface and starts reading packets from it.
use std::io::Read;
extern crate tun;
fn main() {
let mut config = tun::Configuration::default();
config.address((10, 0, 0, 1))
.netmask((255, 255, 255, 0))
.up();
#[cfg(target_os = "linux")]
config.platform(|config| {
config.packet_information(true);
});
let mut dev = tun::create(&config).unwrap();
let mut buf = [0; 4096];
loop {
let amount = dev.read(&mut buf).unwrap();
println!("{:?}", &buf[0 .. amount]);
}
}Platforms
Not every platform is supported.
Linux
You will need the tun module to be loaded and root is required to create
interfaces.
macOS
It just werks, but you have to set up routing manually.
iOS
You can pass the file descriptor of the TUN device to rust-tun to create the interface.
Here is an example to create the TUN device on iOS and pass the fd to rust-tun:
// 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
let tunFd = self?.packetFlow.value(forKeyPath: "socket.fileDescriptor") as! Int32
DispatchQueue.global(qos: .default).async {
start_tun(tunFd)
}
completionHandler(nil)
}
}
}#[no_mangle]
pub extern "C" fn start_tun(fd: std::os::raw::c_int) {
let mut rt = tokio::runtime::Runtime::new().unwrap();
rt.block_on(async {
let mut cfg = tun::Configuration::default();
cfg.raw_fd(fd);
let mut tun = tun::create_as_async(&cfg).unwrap();
let mut framed = tun.into_framed();
while let Some(packet) = framed.next().await {
...
}
});
}