golang编写ping失败，求大神指点

环境是在windows7下的LiteIDE集成环境，代码如下：

package main

import (
    "bytes"
    "encoding/binary"
    "fmt"
    "net"
)

type ICMP struct {
    Type        uint8
    Code        uint8
    Checksum    uint16
    Identifier  uint16
    SequenceNum uint16
}

func CheckSum(data []byte) uint16 {
    var (
        sum    uint32
        length int = len(data)
        index  int
    )
    for length > 1 {
        sum += uint32(data[index])<<8 + uint32(data[index+1])
        index += 2
        length -= 2
    }
    if length > 0 {
        sum += uint32(data[index])
    }
    sum += (sum >> 16)

    return uint16(^sum)
}

func main() {
    var (
        icmp  ICMP
        laddr net.IPAddr = net.IPAddr{IP: net.ParseIP("192.168.31.11")}
        raddr net.IPAddr = net.IPAddr{IP: net.ParseIP("192.168.31.1")}
    )
    //如果你要使用网络层的其他协议还可以设置成 ip:ospf、ip:arp 等
    conn, err := net.DialIP("ip4:icmp", &laddr, &raddr)
    if err != nil {
        fmt.Println(err.Error())
        return
    }
    defer conn.Close()

    //开始填充数据包
    icmp.Type = 8 //8->echo message  0->reply message
    icmp.Code = 0
    icmp.Checksum = 0
    icmp.Identifier = 0
    icmp.SequenceNum = 0

    var (
        buffer bytes.Buffer
    )
    //先在buffer中写入icmp数据报求去校验和
    binary.Write(&buffer, binary.BigEndian, icmp)
    icmp.Checksum = CheckSum(buffer.Bytes())
    //然后清空buffer并把求完校验和的icmp数据报写入其中准备发送
    buffer.Reset()
    binary.Write(&buffer, binary.BigEndian, icmp)

    if _, err := conn.Write(buffer.Bytes()); err != nil {
        fmt.Println(err.Error())
        return
    }
    fmt.Printf("send icmp packet success!")
}

运行提示：

socket: An attempt was made to access a socket in a way forbidden by its access permissions.

求指点调通~