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A simple TUN/TAP library written in native Go.
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songgao/water
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water is a native Go library forTUN/TAP interfaces.
water is designed to be simple and efficient. It
- wraps almost only syscalls and uses only Go standard types;
- exposes standard interfaces; plays well with standard packages like
io,bufio, etc.. - does not handle memory management (allocating/destructing slice). It's up to user to decide whether/how to reuse buffers.
water/waterutil has some useful functions to interpret MAC frame headers and IP packet headers. It also contains some constants such as protocol numbers and ethernet frame types.
Seehttps://github.com/songgao/packets for functions for parsing various packets.
- Linux
- Windows (experimental; APIs might change)
- macOS (point-to-point TUN only)
go get -u github.com/songgao/watergo get -u github.com/songgao/water/waterutilhttp://godoc.org/github.com/songgao/water
package mainimport ("log""github.com/songgao/packets/ethernet""github.com/songgao/water")funcmain() {config:= water.Config{DeviceType:water.TAP,}config.Name="O_O"ifce,err:=water.New(config)iferr!=nil {log.Fatal(err)}varframe ethernet.Framefor {frame.Resize(1500)n,err:=ifce.Read([]byte(frame))iferr!=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 aTAP interface, and prints some header information for every frame. After pull up themain.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_Osudo ip linkset dev O_O upWait until the outputmain.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:ff2016/10/24 03:18:16 Src: 72:3c:fc:29:1c:6f2016/10/24 03:18:16 Ethertype: 08 002016/10/24 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 37package mainimport ("log""github.com/songgao/water")funcmain() {ifce,err:=water.New(water.Config{DeviceType:water.TUN,})iferr!=nil {log.Fatal(err)}log.Printf("Interface Name: %s\n",ifce.Name())packet:=make([]byte,2000)for {n,err:=ifce.Read(packet)iferr!=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. Useifconfig to see its attributes. You need to bring it up and assign IP addresses (apparently replaceutun2 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: utun22017/03/20 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- Only Point-to-Point user TUN devices are supported. TAP devices arenot supported natively by macOS.
- Custom interface names are not supported by macOS. Interface names are automatically generated serially, using the
utun<#>naming convention.
To use it with windows, you will need to install atap driver, orOpenVPN client for windows.
It's compatible with the Linux code.
package mainimport ("log""github.com/songgao/packets/ethernet""github.com/songgao/water")funcmain() {ifce,err:=water.New(water.Config{DeviceType:water.TAP,})iferr!=nil {log.Fatal(err)}varframe ethernet.Framefor {frame.Resize(1500)n,err:=ifce.Read([]byte(frame))iferr!=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.goIt 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=noneThemain.go terminal should be silenced after IP assignment, try sending some ICMP broadcast message:
ping 10.1.0.255You'll see output containing the IPv4 ICMP frame same as the Linux version.
If you are going to use multiple TAP devices on the Windows, there is a way to specify an interface name to select the exact device that you need:
ifce,err:=water.New(water.Config{DeviceType:water.TAP,PlatformSpecificParams: water.PlatformSpecificParams{ComponentID:"tap0901",InterfaceName:"Ethernet 3",Network:"192.168.1.10/24",},})
- tuntaposx for TAP on Darwin