A simple TUN/TAP library written in native Go.
water is a native Go library for TUN/TAP interfaces.Supported Platforms
- Linux
- Windows (experimental; APIs might change)
- macOS (point-to-point TUN only)
Installation
go get -u github.com/songgao/water
go get -u github.com/songgao/water/waterutil
Documentation
Example
TAP on Linux:
package main
import (
"log"
"github.com/songgao/packets/ethernet"
"github.com/songgao/water"
)
func main() {
config := water.Config{
DeviceType: water.TAP,
}
config.Name = "O_O"
ifce, err := water.New(config)
if err != nil {
log.Fatal(err)
}
var frame ethernet.Frame
for {
frame.Resize(1500)
n, err := ifce.Read([]byte(frame))
if err != nil {
log.Fatal(err)
}
frame = frame[:n]
log.Printf("Dst: %s\n", frame.Destination())
log.Printf("Src: %s\n", frame.Source())
log.Printf("Ethertype: % x\n", frame.Ethertype())
log.Printf("Payload: % x\n", frame.Payload())
}
}
This piece of code creates a
TAP interface, and prints some header information for every frame. After pull up the main.go, you'll need to bring up the interface and assign an IP address. All of these need root permission.sudo go run main.go
In a new terminal:
sudo ip addr add 10.1.0.10/24 dev O_O
sudo ip link set dev O_O up
Wait until the output
main.go terminal, try sending some ICMP broadcast message:ping -c1 -b 10.1.0.255
You'll see output containing the IPv4 ICMP frame:
2016/10/24 03:18:16 Dst: ff:ff:ff:ff:ff:ff
2016/10/24 03:18:16 Src: 72:3c:fc:29:1c:6f
2016/10/24 03:18:16 Ethertype: 08 00
2016/10/24 03:18:16 Payload: 45 00 00 54 00 00 40 00 40 01 25 9f 0a 01 00 0a 0a 01 00 ff 08 00 01 c1 08 49 00 01 78 7d 0d 58 00 00 00 00 a2 4c 07 00 00 00 00 00 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f 30 31 32 33 34 35 36 37
TUN on macOS
package main
import (
"log"
"github.com/songgao/water"
)
func main() {
ifce, err := water.New(water.Config{
DeviceType: water.TUN,
})
if err != nil {
log.Fatal(err)
}
log.Printf("Interface Name: %s\n", ifce.Name())
packet := make([]byte, 2000)
for {
n, err := ifce.Read(packet)
if err != nil {
log.Fatal(err)
}
log.Printf("Packet Received: % x\n", packet[:n])
}
}
Run it!
$ sudo go run main.go
This is a point-to-point only interface. Use
ifconfig to see its attributes. You need to bring it up and assign IP addresses (apparently replace utun2 if needed):$ sudo ifconfig utun2 10.1.0.10 10.1.0.20 up
Now send some ICMP packets to the interface:
$ ping 10.1.0.20
You'd see the ICMP packets printed out:
2017/03/20 21:17:30 Interface Name: utun2
2017/03/20 21:17:40 Packet Received: 45 00 00 54 e9 1d 00 00 40 01 7d 6c 0a 01 00 0a 0a 01 00 14 08 00 ee 04 21 15 00 00 58 d0 a9 64 00 08 fb a5 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f 30 31 32 33 34 35 36 37
Caveats
- Only Point-to-Point user TUN devices are supported. TAP devices are not supported natively by macOS.
- Custom interface names are not supported by macOS. Interface names are automatically generated serially, using the
utun<#>naming convention.
TAP on Windows:
To use it with windows, you will need to install a tap driver, or OpenVPN client for windows.
It's compatible with the Linux code.
package main
import (
"log"
"github.com/songgao/packets/ethernet"
"github.com/songgao/water"
)
func main() {
ifce, err := water.New(water.Config{
DeviceType: water.TAP,
})
if err != nil {
log.Fatal(err)
}
var frame ethernet.Frame
for {
frame.Resize(1500)
n, err := ifce.Read([]byte(frame))
if err != nil {
log.Fatal(err)
}
frame = frame[:n]
log.Printf("Dst: %s\n", frame.Destination())
log.Printf("Src: %s\n", frame.Source())
log.Printf("Ethertype: % x\n", frame.Ethertype())
log.Printf("Payload: % x\n", frame.Payload())
}
}
Same as Linux version, but you don't need to bring up the device by hand, the only thing you need is to assign an IP address to it.
go run main.go
It will output a lot of lines because of some windows services and dhcp. You will need admin right to assign IP.
In a new cmd (admin right):
# Replace with your device name, it can be achieved by ifce.Name().
netsh interface ip set address name="Ehternet 2" source=static addr=10.1.0.10 mask=255.255.255.0 gateway=none
The
main.go terminal should be silenced after IP assignment, try sending some ICMP broadcast message:ping 10.1.0.255
You'll see output containing the IPv4 ICMP frame same as the Linux version.
TODO
- tuntaposx for TAP on Darwin
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