code: func (l *Link) getDefaultPort() *nat.Port {
  	var p nat.Port
  	i := len(l.Ports)
  
  	if i == 0 {
  		return nil
  	} else if i > 1 {
  		nat.Sort(l.Ports, func(ip, jp nat.Port) bool {
  			// If the two ports have the same number, tcp takes priority
  			// Sort in desc order
  			return ip.Int() < jp.Int() || (ip.Int() == jp.Int() && strings.ToLower(ip.Proto()) == "tcp")
  		})
  	}
  	p = l.Ports[0]
  	return &p
  }
docs: // Default port rules