How to bind physical nic to send a ip package with golang?

I set up a virtual network card(TUN) on the windows client for the vpn to get traffic. When capturing virtual NIC traffic, I perform the following resource judgment logic: When accessing certain resources, the traffic (IP packets) will not be sent through the VPN channel. I want to send the traffic (IP packets) directly through the physical NIC. The problem now is how do I get the traffic sent directly through the physical network card.

--SYSTEM：WINDOWS --LANGUAGE：GOLANG

I tried to simulate TCP/UDP by parsing IP packets and binding network adapter addresses for sending, but this was too slow. Is there a way to directly bind the physical NIC and send IP packets?

Raw sockets are disabled since Windows XP, so you need third party software to inject IP packets.

I used WinPcap library for this. The Go binding exists: https://pkg.go.dev/github.com/google/gopacket/pcap

The function that writes Ethernet frames to the datalink is Handle.WritePacketData

The steps are:

1. Create a handle to your physical NIC with OpenLive
2. Wrap IP packed into datalink layer frame
3. Write the frame to the handle with Handle.WritePacketData

The tricky part with the step 1 is the name of the interface. In windows there are no such names as eth0. The required name looks like \Device\NPF_{BBECCD43-3F2B-4594-B17B-5F38E73787E8}

To get the proper names of the devices you can query FindAllDevs function. As Administrator!

package main

import (
    "fmt"

    "github.com/google/gopacket/pcap"
)

func main() {
    // Get device list - run as ADMINISTRATOR!
    devices, err := pcap.FindAllDevs()
    if err != nil {
        panic(err)
    }

    // Print device information
    fmt.Println("Devices:")
    for _, device := range devices {
        fmt.Println("-----------------------")
        fmt.Println("Name: ", device.Name)
        fmt.Println("Description: ", device.Description)
        fmt.Println("Addresses: ", device.Description)
        for _, address := range device.Addresses {
            fmt.Println("  IP address: ", address.IP)
            fmt.Println("  Netmask: ", address.Netmask)
        }
    }
}

Sample output (this is my WiFi adapter):

-----------------------
Name:  \Device\NPF_{BBECCD43-3F2B-4594-B17B-5F38E73787E8}
Description:  Microsoft
Addresses:  Microsoft
  IP address:  fe80::de52:6717:446:57a1
  Netmask:  <nil>
  IP address:  172.30.1.95
  Netmask:  ffffff00