gistfile1.txt

package main

import (
    "fmt"
    "net"

    "golang.org/x/sys/unix"
)

func main() {
    conn, err := net.ListenUDP("udp", nil)
    if err != nil {
        panic(err)
    }
    defer conn.Close()
    rc, err := conn.SyscallConn()
    if err != nil {
        panic(err)
    }
    err = rc.Control(func(fd uintptr) {
        err := unix.SetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_MTU_DISCOVER, unix.IP_PMTUDISC_DO)
        if err != nil {
            panic(err)
        }
    })
    if err != nil {
        panic(err)
    }
    bs := make([]byte, 7000)
    fmt.Println(conn.WriteToUDP(bs, &net.UDPAddr{
        IP:   net.IPv4(8, 8, 8, 8),
        Port: 53,
    }))
}