func ServerPing(target string) bool  {
	pinger, err := ping.NewPinger(target)
	if err != nil {
		panic(err)
	}

	pinger.Count = ICMPCOUNT
	pinger.Timeout = time.Duration(PINGTIME*time.Millisecond)
	pinger.SetPrivileged(true)
	pinger.Run()// blocks until finished
	stats := pinger.Statistics()

	fmt.Println(stats)
	// 有回包，就是说明IP是可用的
	if stats.PacketsRecv >= 1 {
		return true
	}
	return false
}

type Statistics struct {
	// PacketsRecv is the number of packets received.
	PacketsRecv int

	// PacketsSent is the number of packets sent.
	PacketsSent int

	// PacketLoss is the percentage of packets lost.
	PacketLoss float64

	// IPAddr is the address of the host being pinged.
	IPAddr *net.IPAddr

	// Addr is the string address of the host being pinged.
	Addr string

	// Rtts is all of the round-trip times sent via this pinger.
	Rtts []time.Duration

	// MinRtt is the minimum round-trip time sent via this pinger.
	MinRtt time.Duration

	// MaxRtt is the maximum round-trip time sent via this pinger.
	MaxRtt time.Duration

	// AvgRtt is the average round-trip time sent via this pinger.
	AvgRtt time.Duration

	// StdDevRtt is the standard deviation of the round-trip times sent via
	// this pinger.
	StdDevRtt time.Duration
}