ip.go
func IsPrivate(ip net.IP) bool {
	for _, ipnet := range privateNets {
		if ipnet.Contains(ip) {
			return true
		}
	}
	return false
}
func IsPrivate(ip net.IP) bool {
	for _, ipnet := range privateNets {
		if ipnet.Contains(ip) {
			return true
		}
	}
	return false
}
// IsPrivate determines whether a passed IP address is from one of private blocks or not.