func skipIPAddr(ip net.IP) bool {
	switch {
	case ip.IsLinkLocalMulticast():
		fallthrough
	case ip.IsLinkLocalUnicast():
		fallthrough
	case ip.IsLoopback():
		fallthrough
	case ip.IsMulticast():
		return true
	}
	return false
}
func skipIPAddr(ip net.IP) bool {
	switch {
	case ip.IsLinkLocalMulticast():
		fallthrough
	case ip.IsLinkLocalUnicast():
		fallthrough
	case ip.IsLoopback():
		fallthrough
	case ip.IsMulticast():
		return true
	}
	return false
}
// skipIPAddr defines the set of criteria that buildAndSelectGuestIPs uses to
// check to see if it needs to skip an IP address.