func GenerateMAC() net.HardwareAddr {
	hw := make(net.HardwareAddr, 6)
	copy(hw[:3], hybridnetOUI)
	_, _ = rand.Read(hw[3:])
	return hw
}
GenerateMAC will generate MAC addresses with fixed first 24 bits (CNI OUI), and the last 24 bits
will be random, so there are at most 16777216(2^24) different addresses.
To avoid MAC address collision as much as possible, this function is suggested to be used within
the limitation that each subnet should contain no more 1024(2^10) using IP addresses.
For example, a subnet whose prefix is greater or equal than 22 is safe to use this function
as MAC address generator.
package mac
import (
	"math/rand"
	"net"
	"time"
)
func init() {
	rand.Seed(int64(time.Now().Nanosecond()))
}
var hybridnetOUI = []byte{0x02, 0x12, 0x34}